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+@c Copyright (C) 1988-2022 Free Software Foundation, Inc.
+@c This is part of the GCC manual.
+@c For copying conditions, see the file gcc.texi.
+
+@ignore
+@c man begin INCLUDE
+@include gcc-vers.texi
+@c man end
+
+@c man begin COPYRIGHT
+Copyright @copyright{} 1988-2022 Free Software Foundation, Inc.
+
+Permission is granted to copy, distribute and/or modify this document
+under the terms of the GNU Free Documentation License, Version 1.3 or
+any later version published by the Free Software Foundation; with the
+Invariant Sections being ``GNU General Public License'' and ``Funding
+Free Software'', the Front-Cover texts being (a) (see below), and with
+the Back-Cover Texts being (b) (see below).  A copy of the license is
+included in the gfdl(7) man page.
+
+(a) The FSF's Front-Cover Text is:
+
+     A GNU Manual
+
+(b) The FSF's Back-Cover Text is:
+
+     You have freedom to copy and modify this GNU Manual, like GNU
+     software.  Copies published by the Free Software Foundation raise
+     funds for GNU development.
+@c man end
+@c Set file name and title for the man page.
+@setfilename gcc
+@settitle GNU project C and C++ compiler
+@c man begin SYNOPSIS
+gcc [@option{-c}|@option{-S}|@option{-E}] [@option{-std=}@var{standard}]
+    [@option{-g}] [@option{-pg}] [@option{-O}@var{level}]
+    [@option{-W}@var{warn}@dots{}] [@option{-Wpedantic}]
+    [@option{-I}@var{dir}@dots{}] [@option{-L}@var{dir}@dots{}]
+    [@option{-D}@var{macro}[=@var{defn}]@dots{}] [@option{-U}@var{macro}]
+    [@option{-f}@var{option}@dots{}] [@option{-m}@var{machine-option}@dots{}]
+    [@option{-o} @var{outfile}] [@@@var{file}] @var{infile}@dots{}
+
+Only the most useful options are listed here; see below for the
+remainder.  @command{g++} accepts mostly the same options as @command{gcc}.
+@c man end
+@c man begin SEEALSO
+gpl(7), gfdl(7), fsf-funding(7),
+cpp(1), gcov(1), as(1), ld(1), gdb(1)
+and the Info entries for @file{gcc}, @file{cpp}, @file{as},
+@file{ld}, @file{binutils} and @file{gdb}.
+@c man end
+@c man begin BUGS
+For instructions on reporting bugs, see
+@w{@value{BUGURL}}.
+@c man end
+@c man begin AUTHOR
+See the Info entry for @command{gcc}, or
+@w{@uref{https://gcc.gnu.org/onlinedocs/gcc/Contributors.html}},
+for contributors to GCC@.
+@c man end
+@end ignore
+
+@node Invoking GCC
+@chapter GCC Command Options
+@cindex GCC command options
+@cindex command options
+@cindex options, GCC command
+
+@c man begin DESCRIPTION
+When you invoke GCC, it normally does preprocessing, compilation,
+assembly and linking.  The ``overall options'' allow you to stop this
+process at an intermediate stage.  For example, the @option{-c} option
+says not to run the linker.  Then the output consists of object files
+output by the assembler.
+@xref{Overall Options,,Options Controlling the Kind of Output}.
+
+Other options are passed on to one or more stages of processing.  Some options
+control the preprocessor and others the compiler itself.  Yet other
+options control the assembler and linker; most of these are not
+documented here, since you rarely need to use any of them.
+
+@cindex C compilation options
+Most of the command-line options that you can use with GCC are useful
+for C programs; when an option is only useful with another language
+(usually C++), the explanation says so explicitly.  If the description
+for a particular option does not mention a source language, you can use
+that option with all supported languages.
+
+@cindex cross compiling
+@cindex specifying machine version
+@cindex specifying compiler version and target machine
+@cindex compiler version, specifying
+@cindex target machine, specifying
+The usual way to run GCC is to run the executable called @command{gcc}, or
+@command{@var{machine}-gcc} when cross-compiling, or
+@command{@var{machine}-gcc-@var{version}} to run a specific version of GCC.
+When you compile C++ programs, you should invoke GCC as @command{g++} 
+instead.  @xref{Invoking G++,,Compiling C++ Programs}, 
+for information about the differences in behavior between @command{gcc} 
+and @command{g++} when compiling C++ programs.
+
+@cindex grouping options
+@cindex options, grouping
+The @command{gcc} program accepts options and file names as operands.  Many
+options have multi-letter names; therefore multiple single-letter options
+may @emph{not} be grouped: @option{-dv} is very different from @w{@samp{-d
+-v}}.
+
+@cindex order of options
+@cindex options, order
+You can mix options and other arguments.  For the most part, the order
+you use doesn't matter.  Order does matter when you use several
+options of the same kind; for example, if you specify @option{-L} more
+than once, the directories are searched in the order specified.  Also,
+the placement of the @option{-l} option is significant.
+
+Many options have long names starting with @samp{-f} or with
+@samp{-W}---for example,
+@option{-fmove-loop-invariants}, @option{-Wformat} and so on.  Most of
+these have both positive and negative forms; the negative form of
+@option{-ffoo} is @option{-fno-foo}.  This manual documents
+only one of these two forms, whichever one is not the default.
+
+Some options take one or more arguments typically separated either
+by a space or by the equals sign (@samp{=}) from the option name.
+Unless documented otherwise, an argument can be either numeric or
+a string.  Numeric arguments must typically be small unsigned decimal
+or hexadecimal integers.  Hexadecimal arguments must begin with
+the @samp{0x} prefix.  Arguments to options that specify a size
+threshold of some sort may be arbitrarily large decimal or hexadecimal
+integers followed by a byte size suffix designating a multiple of bytes
+such as @code{kB} and @code{KiB} for kilobyte and kibibyte, respectively,
+@code{MB} and @code{MiB} for megabyte and mebibyte, @code{GB} and
+@code{GiB} for gigabyte and gigibyte, and so on.  Such arguments are
+designated by @var{byte-size} in the following text.  Refer to the NIST,
+IEC, and other relevant national and international standards for the full
+listing and explanation of the binary and decimal byte size prefixes.
+
+@c man end
+
+@xref{Option Index}, for an index to GCC's options.
+
+@menu
+* Option Summary::      Brief list of all options, without explanations.
+* Overall Options::     Controlling the kind of output:
+                        an executable, object files, assembler files,
+                        or preprocessed source.
+* Invoking G++::        Compiling C++ programs.
+* C Dialect Options::   Controlling the variant of C language compiled.
+* C++ Dialect Options:: Variations on C++.
+* Objective-C and Objective-C++ Dialect Options:: Variations on Objective-C
+                        and Objective-C++.
+* Diagnostic Message Formatting Options:: Controlling how diagnostics should
+                        be formatted.
+* Warning Options::     How picky should the compiler be?
+* Static Analyzer Options:: More expensive warnings.
+* Debugging Options::   Producing debuggable code.
+* Optimize Options::    How much optimization?
+* Instrumentation Options:: Enabling profiling and extra run-time error checking.
+* Preprocessor Options:: Controlling header files and macro definitions.
+                         Also, getting dependency information for Make.
+* Assembler Options::   Passing options to the assembler.
+* Link Options::        Specifying libraries and so on.
+* Directory Options::   Where to find header files and libraries.
+                        Where to find the compiler executable files.
+* Code Gen Options::    Specifying conventions for function calls, data layout
+                        and register usage.
+* Developer Options::   Printing GCC configuration info, statistics, and
+                        debugging dumps.
+* Submodel Options::    Target-specific options, such as compiling for a
+                        specific processor variant.
+* Spec Files::          How to pass switches to sub-processes.
+* Environment Variables:: Env vars that affect GCC.
+* Precompiled Headers:: Compiling a header once, and using it many times.
+* C++ Modules::		Experimental C++20 module system.
+@end menu
+
+@c man begin OPTIONS
+
+@node Option Summary
+@section Option Summary
+
+Here is a summary of all the options, grouped by type.  Explanations are
+in the following sections.
+
+@table @emph
+@item Overall Options
+@xref{Overall Options,,Options Controlling the Kind of Output}.
+@gccoptlist{-c  -S  -E  -o @var{file} @gol
+-dumpbase @var{dumpbase}  -dumpbase-ext @var{auxdropsuf} @gol
+-dumpdir @var{dumppfx}  -x @var{language}  @gol
+-v  -###  --help@r{[}=@var{class}@r{[},@dots{}@r{]]}  --target-help  --version @gol
+-pass-exit-codes  -pipe  -specs=@var{file}  -wrapper  @gol
+@@@var{file}  -ffile-prefix-map=@var{old}=@var{new}  @gol
+-fplugin=@var{file}  -fplugin-arg-@var{name}=@var{arg}  @gol
+-fdump-ada-spec@r{[}-slim@r{]}  -fada-spec-parent=@var{unit}  -fdump-go-spec=@var{file}}
+
+@item C Language Options
+@xref{C Dialect Options,,Options Controlling C Dialect}.
+@gccoptlist{-ansi  -std=@var{standard}  -aux-info @var{filename} @gol
+-fno-asm  @gol
+-fno-builtin  -fno-builtin-@var{function}  -fcond-mismatch @gol
+-ffreestanding  -fgimple  -fgnu-tm  -fgnu89-inline  -fhosted @gol
+-flax-vector-conversions  -fms-extensions @gol
+-foffload=@var{arg}  -foffload-options=@var{arg} @gol
+-fopenacc  -fopenacc-dim=@var{geom} @gol
+-fopenmp  -fopenmp-simd @gol
+-fpermitted-flt-eval-methods=@var{standard} @gol
+-fplan9-extensions  -fsigned-bitfields  -funsigned-bitfields @gol
+-fsigned-char  -funsigned-char -fstrict-flex-arrays[=@var{n}] @gol
+-fsso-struct=@var{endianness}}
+
+@item C++ Language Options
+@xref{C++ Dialect Options,,Options Controlling C++ Dialect}.
+@gccoptlist{-fabi-version=@var{n}  -fno-access-control @gol
+-faligned-new=@var{n}  -fargs-in-order=@var{n}  -fchar8_t  -fcheck-new @gol
+-fconstexpr-depth=@var{n}  -fconstexpr-cache-depth=@var{n} @gol
+-fconstexpr-loop-limit=@var{n}  -fconstexpr-ops-limit=@var{n} @gol
+-fno-elide-constructors @gol
+-fno-enforce-eh-specs @gol
+-fno-gnu-keywords @gol
+-fno-implicit-templates @gol
+-fno-implicit-inline-templates @gol
+-fno-implement-inlines  @gol
+-fmodule-header@r{[}=@var{kind}@r{]} -fmodule-only -fmodules-ts @gol
+-fmodule-implicit-inline @gol
+-fno-module-lazy @gol
+-fmodule-mapper=@var{specification} @gol
+-fmodule-version-ignore @gol
+-fms-extensions @gol
+-fnew-inheriting-ctors @gol
+-fnew-ttp-matching @gol
+-fno-nonansi-builtins  -fnothrow-opt  -fno-operator-names @gol
+-fno-optional-diags  -fpermissive @gol
+-fno-pretty-templates @gol
+-fno-rtti  -fsized-deallocation @gol
+-ftemplate-backtrace-limit=@var{n} @gol
+-ftemplate-depth=@var{n} @gol
+-fno-threadsafe-statics  -fuse-cxa-atexit @gol
+-fno-weak  -nostdinc++ @gol
+-fvisibility-inlines-hidden @gol
+-fvisibility-ms-compat @gol
+-fext-numeric-literals @gol
+-flang-info-include-translate@r{[}=@var{header}@r{]} @gol
+-flang-info-include-translate-not @gol
+-flang-info-module-cmi@r{[}=@var{module}@r{]} @gol
+-stdlib=@var{libstdc++,libc++} @gol
+-Wabi-tag  -Wcatch-value  -Wcatch-value=@var{n} @gol
+-Wno-class-conversion  -Wclass-memaccess @gol
+-Wcomma-subscript  -Wconditionally-supported @gol
+-Wno-conversion-null  -Wctad-maybe-unsupported @gol
+-Wctor-dtor-privacy  -Wdangling-reference @gol
+-Wno-delete-incomplete @gol
+-Wdelete-non-virtual-dtor  -Wno-deprecated-array-compare @gol
+-Wdeprecated-copy -Wdeprecated-copy-dtor @gol
+-Wno-deprecated-enum-enum-conversion -Wno-deprecated-enum-float-conversion @gol
+-Weffc++  -Wno-exceptions -Wextra-semi  -Wno-inaccessible-base @gol
+-Wno-inherited-variadic-ctor  -Wno-init-list-lifetime @gol
+-Winvalid-imported-macros @gol
+-Wno-invalid-offsetof  -Wno-literal-suffix @gol
+-Wmismatched-new-delete -Wmismatched-tags @gol
+-Wmultiple-inheritance  -Wnamespaces  -Wnarrowing @gol
+-Wnoexcept  -Wnoexcept-type  -Wnon-virtual-dtor @gol
+-Wpessimizing-move  -Wno-placement-new  -Wplacement-new=@var{n} @gol
+-Wrange-loop-construct -Wredundant-move -Wredundant-tags @gol
+-Wreorder  -Wregister @gol
+-Wstrict-null-sentinel  -Wno-subobject-linkage  -Wtemplates @gol
+-Wno-non-template-friend  -Wold-style-cast @gol
+-Woverloaded-virtual  -Wno-pmf-conversions -Wself-move -Wsign-promo @gol
+-Wsized-deallocation  -Wsuggest-final-methods @gol
+-Wsuggest-final-types  -Wsuggest-override  @gol
+-Wno-terminate  -Wuseless-cast  -Wno-vexing-parse  @gol
+-Wvirtual-inheritance  @gol
+-Wno-virtual-move-assign  -Wvolatile  -Wzero-as-null-pointer-constant}
+
+@item Objective-C and Objective-C++ Language Options
+@xref{Objective-C and Objective-C++ Dialect Options,,Options Controlling
+Objective-C and Objective-C++ Dialects}.
+@gccoptlist{-fconstant-string-class=@var{class-name} @gol
+-fgnu-runtime  -fnext-runtime @gol
+-fno-nil-receivers @gol
+-fobjc-abi-version=@var{n} @gol
+-fobjc-call-cxx-cdtors @gol
+-fobjc-direct-dispatch @gol
+-fobjc-exceptions @gol
+-fobjc-gc @gol
+-fobjc-nilcheck @gol
+-fobjc-std=objc1 @gol
+-fno-local-ivars @gol
+-fivar-visibility=@r{[}public@r{|}protected@r{|}private@r{|}package@r{]} @gol
+-freplace-objc-classes @gol
+-fzero-link @gol
+-gen-decls @gol
+-Wassign-intercept  -Wno-property-assign-default @gol
+-Wno-protocol -Wobjc-root-class -Wselector @gol
+-Wstrict-selector-match @gol
+-Wundeclared-selector}
+
+@item Diagnostic Message Formatting Options
+@xref{Diagnostic Message Formatting Options,,Options to Control Diagnostic Messages Formatting}.
+@gccoptlist{-fmessage-length=@var{n}  @gol
+-fdiagnostics-plain-output @gol
+-fdiagnostics-show-location=@r{[}once@r{|}every-line@r{]}  @gol
+-fdiagnostics-color=@r{[}auto@r{|}never@r{|}always@r{]}  @gol
+-fdiagnostics-urls=@r{[}auto@r{|}never@r{|}always@r{]}  @gol
+-fdiagnostics-format=@r{[}text@r{|}sarif-stderr@r{|}sarif-file@r{|}json@r{|}json-stderr@r{|}json-file@r{]}  @gol
+-fno-diagnostics-show-option  -fno-diagnostics-show-caret @gol
+-fno-diagnostics-show-labels  -fno-diagnostics-show-line-numbers @gol
+-fno-diagnostics-show-cwe  @gol
+-fno-diagnostics-show-rule  @gol
+-fdiagnostics-minimum-margin-width=@var{width} @gol
+-fdiagnostics-parseable-fixits  -fdiagnostics-generate-patch @gol
+-fdiagnostics-show-template-tree  -fno-elide-type @gol
+-fdiagnostics-path-format=@r{[}none@r{|}separate-events@r{|}inline-events@r{]} @gol
+-fdiagnostics-show-path-depths @gol
+-fno-show-column @gol
+-fdiagnostics-column-unit=@r{[}display@r{|}byte@r{]} @gol
+-fdiagnostics-column-origin=@var{origin} @gol
+-fdiagnostics-escape-format=@r{[}unicode@r{|}bytes@r{]}}
+
+@item Warning Options
+@xref{Warning Options,,Options to Request or Suppress Warnings}.
+@gccoptlist{-fsyntax-only  -fmax-errors=@var{n}  -Wpedantic @gol
+-pedantic-errors @gol
+-w  -Wextra  -Wall  -Wabi=@var{n} @gol
+-Waddress  -Wno-address-of-packed-member  -Waggregate-return @gol
+-Walloc-size-larger-than=@var{byte-size}  -Walloc-zero @gol
+-Walloca  -Walloca-larger-than=@var{byte-size} @gol
+-Wno-aggressive-loop-optimizations @gol
+-Warith-conversion @gol
+-Warray-bounds  -Warray-bounds=@var{n}  -Warray-compare @gol
+-Wno-attributes  -Wattribute-alias=@var{n} -Wno-attribute-alias @gol
+-Wno-attribute-warning  @gol
+-Wbidi-chars=@r{[}none@r{|}unpaired@r{|}any@r{|}ucn@r{]} @gol
+-Wbool-compare  -Wbool-operation @gol
+-Wno-builtin-declaration-mismatch @gol
+-Wno-builtin-macro-redefined  -Wc90-c99-compat  -Wc99-c11-compat @gol
+-Wc11-c2x-compat @gol
+-Wc++-compat  -Wc++11-compat  -Wc++14-compat  -Wc++17-compat  @gol
+-Wc++20-compat   @gol
+-Wno-c++11-extensions  -Wno-c++14-extensions -Wno-c++17-extensions  @gol
+-Wno-c++20-extensions  -Wno-c++23-extensions  @gol
+-Wcast-align  -Wcast-align=strict  -Wcast-function-type  -Wcast-qual  @gol
+-Wchar-subscripts @gol
+-Wclobbered  -Wcomment @gol
+-Wconversion  -Wno-coverage-mismatch  -Wno-cpp @gol
+-Wdangling-else  -Wdangling-pointer  -Wdangling-pointer=@var{n}  @gol
+-Wdate-time @gol
+-Wno-deprecated  -Wno-deprecated-declarations  -Wno-designated-init @gol
+-Wdisabled-optimization @gol
+-Wno-discarded-array-qualifiers  -Wno-discarded-qualifiers @gol
+-Wno-div-by-zero  -Wdouble-promotion @gol
+-Wduplicated-branches  -Wduplicated-cond @gol
+-Wempty-body  -Wno-endif-labels  -Wenum-compare  -Wenum-conversion @gol
+-Wenum-int-mismatch @gol
+-Werror  -Werror=*  -Wexpansion-to-defined  -Wfatal-errors @gol
+-Wfloat-conversion  -Wfloat-equal  -Wformat  -Wformat=2 @gol
+-Wno-format-contains-nul  -Wno-format-extra-args  @gol
+-Wformat-nonliteral  -Wformat-overflow=@var{n} @gol
+-Wformat-security  -Wformat-signedness  -Wformat-truncation=@var{n} @gol
+-Wformat-y2k  -Wframe-address @gol
+-Wframe-larger-than=@var{byte-size}  -Wno-free-nonheap-object @gol
+-Wno-if-not-aligned  -Wno-ignored-attributes @gol
+-Wignored-qualifiers  -Wno-incompatible-pointer-types @gol
+-Wimplicit  -Wimplicit-fallthrough  -Wimplicit-fallthrough=@var{n} @gol
+-Wno-implicit-function-declaration  -Wno-implicit-int @gol
+-Winfinite-recursion @gol
+-Winit-self  -Winline  -Wno-int-conversion  -Wint-in-bool-context @gol
+-Wno-int-to-pointer-cast  -Wno-invalid-memory-model @gol
+-Winvalid-pch  -Winvalid-utf8  -Wno-unicode  -Wjump-misses-init  @gol
+-Wlarger-than=@var{byte-size}  -Wlogical-not-parentheses  -Wlogical-op  @gol
+-Wlong-long  -Wno-lto-type-mismatch -Wmain  -Wmaybe-uninitialized @gol
+-Wmemset-elt-size  -Wmemset-transposed-args @gol
+-Wmisleading-indentation  -Wmissing-attributes  -Wmissing-braces @gol
+-Wmissing-field-initializers  -Wmissing-format-attribute @gol
+-Wmissing-include-dirs  -Wmissing-noreturn  -Wno-missing-profile @gol
+-Wno-multichar  -Wmultistatement-macros  -Wnonnull  -Wnonnull-compare @gol
+-Wnormalized=@r{[}none@r{|}id@r{|}nfc@r{|}nfkc@r{]} @gol
+-Wnull-dereference  -Wno-odr  @gol
+-Wopenacc-parallelism  @gol
+-Wopenmp-simd  @gol
+-Wno-overflow  -Woverlength-strings  -Wno-override-init-side-effects @gol
+-Wpacked  -Wno-packed-bitfield-compat  -Wpacked-not-aligned  -Wpadded @gol
+-Wparentheses  -Wno-pedantic-ms-format @gol
+-Wpointer-arith  -Wno-pointer-compare  -Wno-pointer-to-int-cast @gol
+-Wno-pragmas  -Wno-prio-ctor-dtor  -Wredundant-decls @gol
+-Wrestrict  -Wno-return-local-addr  -Wreturn-type @gol
+-Wno-scalar-storage-order  -Wsequence-point @gol
+-Wshadow  -Wshadow=global  -Wshadow=local  -Wshadow=compatible-local @gol
+-Wno-shadow-ivar @gol
+-Wno-shift-count-negative  -Wno-shift-count-overflow  -Wshift-negative-value @gol
+-Wno-shift-overflow  -Wshift-overflow=@var{n} @gol
+-Wsign-compare  -Wsign-conversion @gol
+-Wno-sizeof-array-argument @gol
+-Wsizeof-array-div @gol
+-Wsizeof-pointer-div  -Wsizeof-pointer-memaccess @gol
+-Wstack-protector  -Wstack-usage=@var{byte-size}  -Wstrict-aliasing @gol
+-Wstrict-aliasing=n  -Wstrict-overflow  -Wstrict-overflow=@var{n} @gol
+-Wstring-compare @gol
+-Wno-stringop-overflow -Wno-stringop-overread @gol
+-Wno-stringop-truncation @gol
+-Wsuggest-attribute=@r{[}pure@r{|}const@r{|}noreturn@r{|}format@r{|}malloc@r{]} @gol
+-Wswitch  -Wno-switch-bool  -Wswitch-default  -Wswitch-enum @gol
+-Wno-switch-outside-range  -Wno-switch-unreachable  -Wsync-nand @gol
+-Wsystem-headers  -Wtautological-compare  -Wtrampolines  -Wtrigraphs @gol
+-Wtrivial-auto-var-init -Wtsan -Wtype-limits  -Wundef @gol
+-Wuninitialized  -Wunknown-pragmas @gol
+-Wunsuffixed-float-constants  -Wunused @gol
+-Wunused-but-set-parameter  -Wunused-but-set-variable @gol
+-Wunused-const-variable  -Wunused-const-variable=@var{n} @gol
+-Wunused-function  -Wunused-label  -Wunused-local-typedefs @gol
+-Wunused-macros @gol
+-Wunused-parameter  -Wno-unused-result @gol
+-Wunused-value  -Wunused-variable @gol
+-Wno-varargs  -Wvariadic-macros @gol
+-Wvector-operation-performance @gol
+-Wvla  -Wvla-larger-than=@var{byte-size}  -Wno-vla-larger-than @gol
+-Wvolatile-register-var  -Wwrite-strings @gol
+-Wxor-used-as-pow @gol
+-Wzero-length-bounds}
+
+@item Static Analyzer Options
+@gccoptlist{
+-fanalyzer @gol
+-fanalyzer-call-summaries @gol
+-fanalyzer-checker=@var{name} @gol
+-fno-analyzer-feasibility @gol
+-fanalyzer-fine-grained @gol
+-fno-analyzer-state-merge @gol
+-fno-analyzer-state-purge @gol
+-fanalyzer-transitivity @gol
+-fno-analyzer-undo-inlining @gol
+-fanalyzer-verbose-edges @gol
+-fanalyzer-verbose-state-changes @gol
+-fanalyzer-verbosity=@var{level} @gol
+-fdump-analyzer @gol
+-fdump-analyzer-callgraph @gol
+-fdump-analyzer-exploded-graph @gol
+-fdump-analyzer-exploded-nodes @gol
+-fdump-analyzer-exploded-nodes-2 @gol
+-fdump-analyzer-exploded-nodes-3 @gol
+-fdump-analyzer-exploded-paths @gol
+-fdump-analyzer-feasibility @gol
+-fdump-analyzer-json @gol
+-fdump-analyzer-state-purge @gol
+-fdump-analyzer-stderr @gol
+-fdump-analyzer-supergraph @gol
+-fdump-analyzer-untracked @gol
+-Wno-analyzer-double-fclose @gol
+-Wno-analyzer-double-free @gol
+-Wno-analyzer-exposure-through-output-file @gol
+-Wno-analyzer-exposure-through-uninit-copy @gol
+-Wno-analyzer-fd-access-mode-mismatch @gol
+-Wno-analyzer-fd-double-close @gol
+-Wno-analyzer-fd-leak @gol
+-Wno-analyzer-fd-use-after-close @gol
+-Wno-analyzer-fd-use-without-check @gol
+-Wno-analyzer-file-leak @gol
+-Wno-analyzer-free-of-non-heap @gol
+-Wno-analyzer-imprecise-fp-arithmetic @gol
+-Wno-analyzer-jump-through-null @gol
+-Wno-analyzer-malloc-leak @gol
+-Wno-analyzer-mismatching-deallocation @gol
+-Wno-analyzer-null-argument @gol
+-Wno-analyzer-null-dereference @gol
+-Wno-analyzer-out-of-bounds @gol
+-Wno-analyzer-possible-null-argument @gol
+-Wno-analyzer-possible-null-dereference @gol
+-Wno-analyzer-putenv-of-auto-var @gol
+-Wno-analyzer-shift-count-negative @gol
+-Wno-analyzer-shift-count-overflow @gol
+-Wno-analyzer-stale-setjmp-buffer @gol
+-Wno-analyzer-tainted-allocation-size @gol
+-Wno-analyzer-tainted-array-index @gol
+-Wno-analyzer-tainted-divisor @gol
+-Wno-analyzer-tainted-offset @gol
+-Wno-analyzer-tainted-size @gol
+-Wanalyzer-too-complex @gol
+-Wno-analyzer-unsafe-call-within-signal-handler @gol
+-Wno-analyzer-use-after-free @gol
+-Wno-analyzer-use-of-pointer-in-stale-stack-frame @gol
+-Wno-analyzer-use-of-uninitialized-value @gol
+-Wno-analyzer-va-arg-type-mismatch @gol
+-Wno-analyzer-va-list-exhausted @gol
+-Wno-analyzer-va-list-leak @gol
+-Wno-analyzer-va-list-use-after-va-end @gol
+-Wno-analyzer-write-to-const @gol
+-Wno-analyzer-write-to-string-literal @gol
+}
+
+@item C and Objective-C-only Warning Options
+@gccoptlist{-Wbad-function-cast  -Wmissing-declarations @gol
+-Wmissing-parameter-type  -Wmissing-prototypes  -Wnested-externs @gol
+-Wold-style-declaration  -Wold-style-definition @gol
+-Wstrict-prototypes  -Wtraditional  -Wtraditional-conversion @gol
+-Wdeclaration-after-statement  -Wpointer-sign}
+
+@item Debugging Options
+@xref{Debugging Options,,Options for Debugging Your Program}.
+@gccoptlist{-g  -g@var{level}  -gdwarf  -gdwarf-@var{version} @gol
+-gbtf -gctf  -gctf@var{level} @gol
+-ggdb  -grecord-gcc-switches  -gno-record-gcc-switches @gol
+-gstrict-dwarf  -gno-strict-dwarf @gol
+-gas-loc-support  -gno-as-loc-support @gol
+-gas-locview-support  -gno-as-locview-support @gol
+-gcolumn-info  -gno-column-info  -gdwarf32  -gdwarf64 @gol
+-gstatement-frontiers  -gno-statement-frontiers @gol
+-gvariable-location-views  -gno-variable-location-views @gol
+-ginternal-reset-location-views  -gno-internal-reset-location-views @gol
+-ginline-points  -gno-inline-points @gol
+-gvms -gz@r{[}=@var{type}@r{]} @gol
+-gsplit-dwarf  -gdescribe-dies  -gno-describe-dies @gol
+-fdebug-prefix-map=@var{old}=@var{new}  -fdebug-types-section @gol
+-fno-eliminate-unused-debug-types @gol
+-femit-struct-debug-baseonly  -femit-struct-debug-reduced @gol
+-femit-struct-debug-detailed@r{[}=@var{spec-list}@r{]} @gol
+-fno-eliminate-unused-debug-symbols  -femit-class-debug-always @gol
+-fno-merge-debug-strings  -fno-dwarf2-cfi-asm @gol
+-fvar-tracking  -fvar-tracking-assignments}
+
+@item Optimization Options
+@xref{Optimize Options,,Options that Control Optimization}.
+@gccoptlist{-faggressive-loop-optimizations @gol
+-falign-functions[=@var{n}[:@var{m}:[@var{n2}[:@var{m2}]]]] @gol
+-falign-jumps[=@var{n}[:@var{m}:[@var{n2}[:@var{m2}]]]] @gol
+-falign-labels[=@var{n}[:@var{m}:[@var{n2}[:@var{m2}]]]] @gol
+-falign-loops[=@var{n}[:@var{m}:[@var{n2}[:@var{m2}]]]] @gol
+-fno-allocation-dce -fallow-store-data-races @gol
+-fassociative-math  -fauto-profile  -fauto-profile[=@var{path}] @gol
+-fauto-inc-dec  -fbranch-probabilities @gol
+-fcaller-saves @gol
+-fcombine-stack-adjustments  -fconserve-stack @gol
+-fcompare-elim  -fcprop-registers  -fcrossjumping @gol
+-fcse-follow-jumps  -fcse-skip-blocks  -fcx-fortran-rules @gol
+-fcx-limited-range @gol
+-fdata-sections  -fdce  -fdelayed-branch @gol
+-fdelete-null-pointer-checks  -fdevirtualize  -fdevirtualize-speculatively @gol
+-fdevirtualize-at-ltrans  -fdse @gol
+-fearly-inlining  -fipa-sra  -fexpensive-optimizations  -ffat-lto-objects @gol
+-ffast-math  -ffinite-math-only  -ffloat-store  -fexcess-precision=@var{style} @gol
+-ffinite-loops @gol
+-fforward-propagate  -ffp-contract=@var{style}  -ffunction-sections @gol
+-fgcse  -fgcse-after-reload  -fgcse-las  -fgcse-lm  -fgraphite-identity @gol
+-fgcse-sm  -fhoist-adjacent-loads  -fif-conversion @gol
+-fif-conversion2  -findirect-inlining @gol
+-finline-functions  -finline-functions-called-once  -finline-limit=@var{n} @gol
+-finline-small-functions -fipa-modref -fipa-cp  -fipa-cp-clone @gol
+-fipa-bit-cp  -fipa-vrp  -fipa-pta  -fipa-profile  -fipa-pure-const @gol
+-fipa-reference  -fipa-reference-addressable @gol
+-fipa-stack-alignment  -fipa-icf  -fira-algorithm=@var{algorithm} @gol
+-flive-patching=@var{level} @gol
+-fira-region=@var{region}  -fira-hoist-pressure @gol
+-fira-loop-pressure  -fno-ira-share-save-slots @gol
+-fno-ira-share-spill-slots @gol
+-fisolate-erroneous-paths-dereference  -fisolate-erroneous-paths-attribute @gol
+-fivopts  -fkeep-inline-functions  -fkeep-static-functions @gol
+-fkeep-static-consts  -flimit-function-alignment  -flive-range-shrinkage @gol
+-floop-block  -floop-interchange  -floop-strip-mine @gol
+-floop-unroll-and-jam  -floop-nest-optimize @gol
+-floop-parallelize-all  -flra-remat  -flto  -flto-compression-level @gol
+-flto-partition=@var{alg}  -fmerge-all-constants @gol
+-fmerge-constants  -fmodulo-sched  -fmodulo-sched-allow-regmoves @gol
+-fmove-loop-invariants  -fmove-loop-stores  -fno-branch-count-reg @gol
+-fno-defer-pop  -fno-fp-int-builtin-inexact  -fno-function-cse @gol
+-fno-guess-branch-probability  -fno-inline  -fno-math-errno  -fno-peephole @gol
+-fno-peephole2  -fno-printf-return-value  -fno-sched-interblock @gol
+-fno-sched-spec  -fno-signed-zeros @gol
+-fno-toplevel-reorder  -fno-trapping-math  -fno-zero-initialized-in-bss @gol
+-fomit-frame-pointer  -foptimize-sibling-calls @gol
+-fpartial-inlining  -fpeel-loops  -fpredictive-commoning @gol
+-fprefetch-loop-arrays @gol
+-fprofile-correction @gol
+-fprofile-use  -fprofile-use=@var{path} -fprofile-partial-training @gol
+-fprofile-values -fprofile-reorder-functions @gol
+-freciprocal-math  -free  -frename-registers  -freorder-blocks @gol
+-freorder-blocks-algorithm=@var{algorithm} @gol
+-freorder-blocks-and-partition  -freorder-functions @gol
+-frerun-cse-after-loop  -freschedule-modulo-scheduled-loops @gol
+-frounding-math  -fsave-optimization-record @gol
+-fsched2-use-superblocks  -fsched-pressure @gol
+-fsched-spec-load  -fsched-spec-load-dangerous @gol
+-fsched-stalled-insns-dep[=@var{n}]  -fsched-stalled-insns[=@var{n}] @gol
+-fsched-group-heuristic  -fsched-critical-path-heuristic @gol
+-fsched-spec-insn-heuristic  -fsched-rank-heuristic @gol
+-fsched-last-insn-heuristic  -fsched-dep-count-heuristic @gol
+-fschedule-fusion @gol
+-fschedule-insns  -fschedule-insns2  -fsection-anchors @gol
+-fselective-scheduling  -fselective-scheduling2 @gol
+-fsel-sched-pipelining  -fsel-sched-pipelining-outer-loops @gol
+-fsemantic-interposition  -fshrink-wrap  -fshrink-wrap-separate @gol
+-fsignaling-nans @gol
+-fsingle-precision-constant  -fsplit-ivs-in-unroller  -fsplit-loops@gol
+-fsplit-paths @gol
+-fsplit-wide-types  -fsplit-wide-types-early  -fssa-backprop  -fssa-phiopt @gol
+-fstdarg-opt  -fstore-merging  -fstrict-aliasing -fipa-strict-aliasing @gol
+-fthread-jumps  -ftracer  -ftree-bit-ccp @gol
+-ftree-builtin-call-dce  -ftree-ccp  -ftree-ch @gol
+-ftree-coalesce-vars  -ftree-copy-prop  -ftree-dce  -ftree-dominator-opts @gol
+-ftree-dse  -ftree-forwprop  -ftree-fre  -fcode-hoisting @gol
+-ftree-loop-if-convert  -ftree-loop-im @gol
+-ftree-phiprop  -ftree-loop-distribution  -ftree-loop-distribute-patterns @gol
+-ftree-loop-ivcanon  -ftree-loop-linear  -ftree-loop-optimize @gol
+-ftree-loop-vectorize @gol
+-ftree-parallelize-loops=@var{n}  -ftree-pre  -ftree-partial-pre  -ftree-pta @gol
+-ftree-reassoc  -ftree-scev-cprop  -ftree-sink  -ftree-slsr  -ftree-sra @gol
+-ftree-switch-conversion  -ftree-tail-merge @gol
+-ftree-ter  -ftree-vectorize  -ftree-vrp  -ftrivial-auto-var-init @gol
+-funconstrained-commons -funit-at-a-time  -funroll-all-loops @gol
+-funroll-loops -funsafe-math-optimizations  -funswitch-loops @gol
+-fipa-ra  -fvariable-expansion-in-unroller  -fvect-cost-model  -fvpt @gol
+-fweb  -fwhole-program  -fwpa  -fuse-linker-plugin -fzero-call-used-regs @gol
+--param @var{name}=@var{value}
+-O  -O0  -O1  -O2  -O3  -Os  -Ofast  -Og  -Oz}
+
+@item Program Instrumentation Options
+@xref{Instrumentation Options,,Program Instrumentation Options}.
+@gccoptlist{-p  -pg  -fprofile-arcs  --coverage  -ftest-coverage @gol
+-fprofile-abs-path @gol
+-fprofile-dir=@var{path}  -fprofile-generate  -fprofile-generate=@var{path} @gol
+-fprofile-info-section  -fprofile-info-section=@var{name} @gol
+-fprofile-note=@var{path} -fprofile-prefix-path=@var{path} @gol
+-fprofile-update=@var{method} -fprofile-filter-files=@var{regex} @gol
+-fprofile-exclude-files=@var{regex} @gol
+-fprofile-reproducible=@r{[}multithreaded@r{|}parallel-runs@r{|}serial@r{]} @gol
+-fsanitize=@var{style}  -fsanitize-recover  -fsanitize-recover=@var{style} @gol
+-fsanitize-trap   -fsanitize-trap=@var{style}  @gol
+-fasan-shadow-offset=@var{number}  -fsanitize-sections=@var{s1},@var{s2},... @gol
+-fsanitize-undefined-trap-on-error  -fbounds-check @gol
+-fcf-protection=@r{[}full@r{|}branch@r{|}return@r{|}none@r{|}check@r{]} @gol
+-fharden-compares -fharden-conditional-branches @gol
+-fstack-protector  -fstack-protector-all  -fstack-protector-strong @gol
+-fstack-protector-explicit  -fstack-check @gol
+-fstack-limit-register=@var{reg}  -fstack-limit-symbol=@var{sym} @gol
+-fno-stack-limit  -fsplit-stack @gol
+-fvtable-verify=@r{[}std@r{|}preinit@r{|}none@r{]} @gol
+-fvtv-counts  -fvtv-debug @gol
+-finstrument-functions  -finstrument-functions-once @gol
+-finstrument-functions-exclude-function-list=@var{sym},@var{sym},@dots{} @gol
+-finstrument-functions-exclude-file-list=@var{file},@var{file},@dots{}} @gol
+-fprofile-prefix-map=@var{old}=@var{new}
+
+@item Preprocessor Options
+@xref{Preprocessor Options,,Options Controlling the Preprocessor}.
+@gccoptlist{-A@var{question}=@var{answer} @gol
+-A-@var{question}@r{[}=@var{answer}@r{]} @gol
+-C  -CC  -D@var{macro}@r{[}=@var{defn}@r{]} @gol
+-dD  -dI  -dM  -dN  -dU @gol
+-fdebug-cpp  -fdirectives-only  -fdollars-in-identifiers  @gol
+-fexec-charset=@var{charset}  -fextended-identifiers  @gol
+-finput-charset=@var{charset}  -flarge-source-files  @gol
+-fmacro-prefix-map=@var{old}=@var{new} -fmax-include-depth=@var{depth} @gol
+-fno-canonical-system-headers  -fpch-deps  -fpch-preprocess  @gol
+-fpreprocessed  -ftabstop=@var{width}  -ftrack-macro-expansion  @gol
+-fwide-exec-charset=@var{charset}  -fworking-directory @gol
+-H  -imacros @var{file}  -include @var{file} @gol
+-M  -MD  -MF  -MG  -MM  -MMD  -MP  -MQ  -MT -Mno-modules @gol
+-no-integrated-cpp  -P  -pthread  -remap @gol
+-traditional  -traditional-cpp  -trigraphs @gol
+-U@var{macro}  -undef  @gol
+-Wp,@var{option}  -Xpreprocessor @var{option}}
+
+@item Assembler Options
+@xref{Assembler Options,,Passing Options to the Assembler}.
+@gccoptlist{-Wa,@var{option}  -Xassembler @var{option}}
+
+@item Linker Options
+@xref{Link Options,,Options for Linking}.
+@gccoptlist{@var{object-file-name}  -fuse-ld=@var{linker}  -l@var{library} @gol
+-nostartfiles  -nodefaultlibs  -nolibc  -nostdlib  -nostdlib++ @gol
+-e @var{entry}  --entry=@var{entry} @gol
+-pie  -pthread  -r  -rdynamic @gol
+-s  -static  -static-pie  -static-libgcc  -static-libstdc++ @gol
+-static-libasan  -static-libtsan  -static-liblsan  -static-libubsan @gol
+-shared  -shared-libgcc  -symbolic @gol
+-T @var{script}  -Wl,@var{option}  -Xlinker @var{option} @gol
+-u @var{symbol}  -z @var{keyword}}
+
+@item Directory Options
+@xref{Directory Options,,Options for Directory Search}.
+@gccoptlist{-B@var{prefix}  -I@var{dir}  -I- @gol
+-idirafter @var{dir} @gol
+-imacros @var{file}  -imultilib @var{dir} @gol
+-iplugindir=@var{dir}  -iprefix @var{file} @gol
+-iquote @var{dir}  -isysroot @var{dir}  -isystem @var{dir} @gol
+-iwithprefix @var{dir}  -iwithprefixbefore @var{dir}  @gol
+-L@var{dir}  -no-canonical-prefixes  --no-sysroot-suffix @gol
+-nostdinc  -nostdinc++  --sysroot=@var{dir}}
+
+@item Code Generation Options
+@xref{Code Gen Options,,Options for Code Generation Conventions}.
+@gccoptlist{-fcall-saved-@var{reg}  -fcall-used-@var{reg} @gol
+-ffixed-@var{reg}  -fexceptions @gol
+-fnon-call-exceptions  -fdelete-dead-exceptions  -funwind-tables @gol
+-fasynchronous-unwind-tables @gol
+-fno-gnu-unique @gol
+-finhibit-size-directive  -fcommon  -fno-ident @gol
+-fpcc-struct-return  -fpic  -fPIC  -fpie  -fPIE  -fno-plt @gol
+-fno-jump-tables -fno-bit-tests @gol
+-frecord-gcc-switches @gol
+-freg-struct-return  -fshort-enums  -fshort-wchar @gol
+-fverbose-asm  -fpack-struct[=@var{n}]  @gol
+-fleading-underscore  -ftls-model=@var{model} @gol
+-fstack-reuse=@var{reuse_level} @gol
+-ftrampolines  -ftrapv  -fwrapv @gol
+-fvisibility=@r{[}default@r{|}internal@r{|}hidden@r{|}protected@r{]} @gol
+-fstrict-volatile-bitfields  -fsync-libcalls}
+
+@item Developer Options
+@xref{Developer Options,,GCC Developer Options}.
+@gccoptlist{-d@var{letters}  -dumpspecs  -dumpmachine  -dumpversion @gol
+-dumpfullversion  -fcallgraph-info@r{[}=su,da@r{]}
+-fchecking  -fchecking=@var{n}
+-fdbg-cnt-list @gol  -fdbg-cnt=@var{counter-value-list} @gol
+-fdisable-ipa-@var{pass_name} @gol
+-fdisable-rtl-@var{pass_name} @gol
+-fdisable-rtl-@var{pass-name}=@var{range-list} @gol
+-fdisable-tree-@var{pass_name} @gol
+-fdisable-tree-@var{pass-name}=@var{range-list} @gol
+-fdump-debug  -fdump-earlydebug @gol
+-fdump-noaddr  -fdump-unnumbered  -fdump-unnumbered-links @gol
+-fdump-final-insns@r{[}=@var{file}@r{]} @gol
+-fdump-ipa-all  -fdump-ipa-cgraph  -fdump-ipa-inline @gol
+-fdump-lang-all @gol
+-fdump-lang-@var{switch} @gol
+-fdump-lang-@var{switch}-@var{options} @gol
+-fdump-lang-@var{switch}-@var{options}=@var{filename} @gol
+-fdump-passes @gol
+-fdump-rtl-@var{pass}  -fdump-rtl-@var{pass}=@var{filename} @gol
+-fdump-statistics @gol
+-fdump-tree-all @gol
+-fdump-tree-@var{switch} @gol
+-fdump-tree-@var{switch}-@var{options} @gol
+-fdump-tree-@var{switch}-@var{options}=@var{filename} @gol
+-fcompare-debug@r{[}=@var{opts}@r{]}  -fcompare-debug-second @gol
+-fenable-@var{kind}-@var{pass} @gol
+-fenable-@var{kind}-@var{pass}=@var{range-list} @gol
+-fira-verbose=@var{n} @gol
+-flto-report  -flto-report-wpa  -fmem-report-wpa @gol
+-fmem-report  -fpre-ipa-mem-report  -fpost-ipa-mem-report @gol
+-fopt-info  -fopt-info-@var{options}@r{[}=@var{file}@r{]} @gol
+-fmultiflags  -fprofile-report @gol
+-frandom-seed=@var{string}  -fsched-verbose=@var{n} @gol
+-fsel-sched-verbose  -fsel-sched-dump-cfg  -fsel-sched-pipelining-verbose @gol
+-fstats  -fstack-usage  -ftime-report  -ftime-report-details @gol
+-fvar-tracking-assignments-toggle  -gtoggle @gol
+-print-file-name=@var{library}  -print-libgcc-file-name @gol
+-print-multi-directory  -print-multi-lib  -print-multi-os-directory @gol
+-print-prog-name=@var{program}  -print-search-dirs  -Q @gol
+-print-sysroot  -print-sysroot-headers-suffix @gol
+-save-temps  -save-temps=cwd  -save-temps=obj  -time@r{[}=@var{file}@r{]}}
+
+@item Machine-Dependent Options
+@xref{Submodel Options,,Machine-Dependent Options}.
+@c This list is ordered alphanumerically by subsection name.
+@c Try and put the significant identifier (CPU or system) first,
+@c so users have a clue at guessing where the ones they want will be.
+
+@emph{AArch64 Options}
+@gccoptlist{-mabi=@var{name}  -mbig-endian  -mlittle-endian @gol
+-mgeneral-regs-only @gol
+-mcmodel=tiny  -mcmodel=small  -mcmodel=large @gol
+-mstrict-align  -mno-strict-align @gol
+-momit-leaf-frame-pointer @gol
+-mtls-dialect=desc  -mtls-dialect=traditional @gol
+-mtls-size=@var{size} @gol
+-mfix-cortex-a53-835769  -mfix-cortex-a53-843419 @gol
+-mlow-precision-recip-sqrt  -mlow-precision-sqrt  -mlow-precision-div @gol
+-mpc-relative-literal-loads @gol
+-msign-return-address=@var{scope} @gol
+-mbranch-protection=@var{none}|@var{standard}|@var{pac-ret}[+@var{leaf}
++@var{b-key}]|@var{bti} @gol
+-mharden-sls=@var{opts} @gol
+-march=@var{name}  -mcpu=@var{name}  -mtune=@var{name}  @gol
+-moverride=@var{string}  -mverbose-cost-dump @gol
+-mstack-protector-guard=@var{guard} -mstack-protector-guard-reg=@var{sysreg} @gol
+-mstack-protector-guard-offset=@var{offset} -mtrack-speculation @gol
+-moutline-atomics }
+
+@emph{Adapteva Epiphany Options}
+@gccoptlist{-mhalf-reg-file  -mprefer-short-insn-regs @gol
+-mbranch-cost=@var{num}  -mcmove  -mnops=@var{num}  -msoft-cmpsf @gol
+-msplit-lohi  -mpost-inc  -mpost-modify  -mstack-offset=@var{num} @gol
+-mround-nearest  -mlong-calls  -mshort-calls  -msmall16 @gol
+-mfp-mode=@var{mode}  -mvect-double  -max-vect-align=@var{num} @gol
+-msplit-vecmove-early  -m1reg-@var{reg}}
+
+@emph{AMD GCN Options}
+@gccoptlist{-march=@var{gpu} -mtune=@var{gpu} -mstack-size=@var{bytes}}
+
+@emph{ARC Options}
+@gccoptlist{-mbarrel-shifter  -mjli-always @gol
+-mcpu=@var{cpu}  -mA6  -mARC600  -mA7  -mARC700 @gol
+-mdpfp  -mdpfp-compact  -mdpfp-fast  -mno-dpfp-lrsr @gol
+-mea  -mno-mpy  -mmul32x16  -mmul64  -matomic @gol
+-mnorm  -mspfp  -mspfp-compact  -mspfp-fast  -msimd  -msoft-float  -mswap @gol
+-mcrc  -mdsp-packa  -mdvbf  -mlock  -mmac-d16  -mmac-24  -mrtsc  -mswape @gol
+-mtelephony  -mxy  -misize  -mannotate-align  -marclinux  -marclinux_prof @gol
+-mlong-calls  -mmedium-calls  -msdata  -mirq-ctrl-saved @gol
+-mrgf-banked-regs  -mlpc-width=@var{width}  -G @var{num} @gol
+-mvolatile-cache  -mtp-regno=@var{regno} @gol
+-malign-call  -mauto-modify-reg  -mbbit-peephole  -mno-brcc @gol
+-mcase-vector-pcrel  -mcompact-casesi  -mno-cond-exec  -mearly-cbranchsi @gol
+-mexpand-adddi  -mindexed-loads  -mlra  -mlra-priority-none @gol
+-mlra-priority-compact -mlra-priority-noncompact  -mmillicode @gol
+-mmixed-code  -mq-class  -mRcq  -mRcw  -msize-level=@var{level} @gol
+-mtune=@var{cpu}  -mmultcost=@var{num}  -mcode-density-frame @gol
+-munalign-prob-threshold=@var{probability}  -mmpy-option=@var{multo} @gol
+-mdiv-rem  -mcode-density  -mll64  -mfpu=@var{fpu}  -mrf16  -mbranch-index}
+
+@emph{ARM Options}
+@gccoptlist{-mapcs-frame  -mno-apcs-frame @gol
+-mabi=@var{name} @gol
+-mapcs-stack-check  -mno-apcs-stack-check @gol
+-mapcs-reentrant  -mno-apcs-reentrant @gol
+-mgeneral-regs-only @gol
+-msched-prolog  -mno-sched-prolog @gol
+-mlittle-endian  -mbig-endian @gol
+-mbe8  -mbe32 @gol
+-mfloat-abi=@var{name} @gol
+-mfp16-format=@var{name}
+-mthumb-interwork  -mno-thumb-interwork @gol
+-mcpu=@var{name}  -march=@var{name}  -mfpu=@var{name}  @gol
+-mtune=@var{name}  -mprint-tune-info @gol
+-mstructure-size-boundary=@var{n} @gol
+-mabort-on-noreturn @gol
+-mlong-calls  -mno-long-calls @gol
+-msingle-pic-base  -mno-single-pic-base @gol
+-mpic-register=@var{reg} @gol
+-mnop-fun-dllimport @gol
+-mpoke-function-name @gol
+-mthumb  -marm  -mflip-thumb @gol
+-mtpcs-frame  -mtpcs-leaf-frame @gol
+-mcaller-super-interworking  -mcallee-super-interworking @gol
+-mtp=@var{name}  -mtls-dialect=@var{dialect} @gol
+-mword-relocations @gol
+-mfix-cortex-m3-ldrd @gol
+-mfix-cortex-a57-aes-1742098 @gol
+-mfix-cortex-a72-aes-1655431 @gol
+-munaligned-access @gol
+-mneon-for-64bits @gol
+-mslow-flash-data @gol
+-masm-syntax-unified @gol
+-mrestrict-it @gol
+-mverbose-cost-dump @gol
+-mpure-code @gol
+-mcmse @gol
+-mfix-cmse-cve-2021-35465 @gol
+-mstack-protector-guard=@var{guard} -mstack-protector-guard-offset=@var{offset} @gol
+-mfdpic}
+
+@emph{AVR Options}
+@gccoptlist{-mmcu=@var{mcu}  -mabsdata  -maccumulate-args @gol
+-mbranch-cost=@var{cost} @gol
+-mcall-prologues  -mgas-isr-prologues  -mint8 @gol
+-mdouble=@var{bits} -mlong-double=@var{bits} @gol
+-mn_flash=@var{size}  -mno-interrupts @gol
+-mmain-is-OS_task  -mrelax  -mrmw  -mstrict-X  -mtiny-stack @gol
+-mfract-convert-truncate @gol
+-mshort-calls  -nodevicelib  -nodevicespecs @gol
+-Waddr-space-convert  -Wmisspelled-isr}
+
+@emph{Blackfin Options}
+@gccoptlist{-mcpu=@var{cpu}@r{[}-@var{sirevision}@r{]} @gol
+-msim  -momit-leaf-frame-pointer  -mno-omit-leaf-frame-pointer @gol
+-mspecld-anomaly  -mno-specld-anomaly  -mcsync-anomaly  -mno-csync-anomaly @gol
+-mlow-64k  -mno-low64k  -mstack-check-l1  -mid-shared-library @gol
+-mno-id-shared-library  -mshared-library-id=@var{n} @gol
+-mleaf-id-shared-library  -mno-leaf-id-shared-library @gol
+-msep-data  -mno-sep-data  -mlong-calls  -mno-long-calls @gol
+-mfast-fp  -minline-plt  -mmulticore  -mcorea  -mcoreb  -msdram @gol
+-micplb}
+
+@emph{C6X Options}
+@gccoptlist{-mbig-endian  -mlittle-endian  -march=@var{cpu} @gol
+-msim  -msdata=@var{sdata-type}}
+
+@emph{CRIS Options}
+@gccoptlist{-mcpu=@var{cpu}  -march=@var{cpu}
+-mtune=@var{cpu} -mmax-stack-frame=@var{n} @gol
+-metrax4  -metrax100  -mpdebug  -mcc-init  -mno-side-effects @gol
+-mstack-align  -mdata-align  -mconst-align @gol
+-m32-bit  -m16-bit  -m8-bit  -mno-prologue-epilogue @gol
+-melf  -maout  -sim  -sim2 @gol
+-mmul-bug-workaround  -mno-mul-bug-workaround}
+
+@emph{C-SKY Options}
+@gccoptlist{-march=@var{arch}  -mcpu=@var{cpu} @gol
+-mbig-endian  -EB  -mlittle-endian  -EL @gol
+-mhard-float  -msoft-float  -mfpu=@var{fpu}  -mdouble-float  -mfdivdu @gol
+-mfloat-abi=@var{name} @gol
+-melrw  -mistack  -mmp  -mcp  -mcache  -msecurity  -mtrust @gol
+-mdsp  -medsp  -mvdsp @gol
+-mdiv  -msmart  -mhigh-registers  -manchor @gol
+-mpushpop  -mmultiple-stld  -mconstpool  -mstack-size  -mccrt @gol
+-mbranch-cost=@var{n}  -mcse-cc  -msched-prolog -msim}
+
+@emph{Darwin Options}
+@gccoptlist{-all_load  -allowable_client  -arch  -arch_errors_fatal @gol
+-arch_only  -bind_at_load  -bundle  -bundle_loader @gol
+-client_name  -compatibility_version  -current_version @gol
+-dead_strip @gol
+-dependency-file  -dylib_file  -dylinker_install_name @gol
+-dynamic  -dynamiclib  -exported_symbols_list @gol
+-filelist  -flat_namespace  -force_cpusubtype_ALL @gol
+-force_flat_namespace  -headerpad_max_install_names @gol
+-iframework @gol
+-image_base  -init  -install_name  -keep_private_externs @gol
+-multi_module  -multiply_defined  -multiply_defined_unused @gol
+-noall_load   -no_dead_strip_inits_and_terms @gol
+-nofixprebinding  -nomultidefs  -noprebind  -noseglinkedit @gol
+-pagezero_size  -prebind  -prebind_all_twolevel_modules @gol
+-private_bundle  -read_only_relocs  -sectalign @gol
+-sectobjectsymbols  -whyload  -seg1addr @gol
+-sectcreate  -sectobjectsymbols  -sectorder @gol
+-segaddr  -segs_read_only_addr  -segs_read_write_addr @gol
+-seg_addr_table  -seg_addr_table_filename  -seglinkedit @gol
+-segprot  -segs_read_only_addr  -segs_read_write_addr @gol
+-single_module  -static  -sub_library  -sub_umbrella @gol
+-twolevel_namespace  -umbrella  -undefined @gol
+-unexported_symbols_list  -weak_reference_mismatches @gol
+-whatsloaded  -F  -gused  -gfull  -mmacosx-version-min=@var{version} @gol
+-mkernel  -mone-byte-bool}
+
+@emph{DEC Alpha Options}
+@gccoptlist{-mno-fp-regs  -msoft-float @gol
+-mieee  -mieee-with-inexact  -mieee-conformant @gol
+-mfp-trap-mode=@var{mode}  -mfp-rounding-mode=@var{mode} @gol
+-mtrap-precision=@var{mode}  -mbuild-constants @gol
+-mcpu=@var{cpu-type}  -mtune=@var{cpu-type} @gol
+-mbwx  -mmax  -mfix  -mcix @gol
+-mfloat-vax  -mfloat-ieee @gol
+-mexplicit-relocs  -msmall-data  -mlarge-data @gol
+-msmall-text  -mlarge-text @gol
+-mmemory-latency=@var{time}}
+
+@emph{eBPF Options}
+@gccoptlist{-mbig-endian -mlittle-endian -mkernel=@var{version}
+-mframe-limit=@var{bytes} -mxbpf -mco-re -mno-co-re
+-mjmpext -mjmp32 -malu32 -mcpu=@var{version}}
+
+@emph{FR30 Options}
+@gccoptlist{-msmall-model  -mno-lsim}
+
+@emph{FT32 Options}
+@gccoptlist{-msim  -mlra  -mnodiv  -mft32b  -mcompress  -mnopm}
+
+@emph{FRV Options}
+@gccoptlist{-mgpr-32  -mgpr-64  -mfpr-32  -mfpr-64 @gol
+-mhard-float  -msoft-float @gol
+-malloc-cc  -mfixed-cc  -mdword  -mno-dword @gol
+-mdouble  -mno-double @gol
+-mmedia  -mno-media  -mmuladd  -mno-muladd @gol
+-mfdpic  -minline-plt  -mgprel-ro  -multilib-library-pic @gol
+-mlinked-fp  -mlong-calls  -malign-labels @gol
+-mlibrary-pic  -macc-4  -macc-8 @gol
+-mpack  -mno-pack  -mno-eflags  -mcond-move  -mno-cond-move @gol
+-moptimize-membar  -mno-optimize-membar @gol
+-mscc  -mno-scc  -mcond-exec  -mno-cond-exec @gol
+-mvliw-branch  -mno-vliw-branch @gol
+-mmulti-cond-exec  -mno-multi-cond-exec  -mnested-cond-exec @gol
+-mno-nested-cond-exec  -mtomcat-stats @gol
+-mTLS  -mtls @gol
+-mcpu=@var{cpu}}
+
+@emph{GNU/Linux Options}
+@gccoptlist{-mglibc  -muclibc  -mmusl  -mbionic  -mandroid @gol
+-tno-android-cc  -tno-android-ld}
+
+@emph{H8/300 Options}
+@gccoptlist{-mrelax  -mh  -ms  -mn  -mexr  -mno-exr  -mint32  -malign-300}
+
+@emph{HPPA Options}
+@gccoptlist{-march=@var{architecture-type} @gol
+-mcaller-copies  -mdisable-fpregs  -mdisable-indexing @gol
+-mfast-indirect-calls  -mgas  -mgnu-ld   -mhp-ld @gol
+-mfixed-range=@var{register-range} @gol
+-mjump-in-delay  -mlinker-opt  -mlong-calls @gol
+-mlong-load-store  -mno-disable-fpregs @gol
+-mno-disable-indexing  -mno-fast-indirect-calls  -mno-gas @gol
+-mno-jump-in-delay  -mno-long-load-store @gol
+-mno-portable-runtime  -mno-soft-float @gol
+-mno-space-regs  -msoft-float  -mpa-risc-1-0 @gol
+-mpa-risc-1-1  -mpa-risc-2-0  -mportable-runtime @gol
+-mschedule=@var{cpu-type}  -mspace-regs  -msio  -mwsio @gol
+-munix=@var{unix-std}  -nolibdld  -static  -threads}
+
+@emph{IA-64 Options}
+@gccoptlist{-mbig-endian  -mlittle-endian  -mgnu-as  -mgnu-ld  -mno-pic @gol
+-mvolatile-asm-stop  -mregister-names  -msdata  -mno-sdata @gol
+-mconstant-gp  -mauto-pic  -mfused-madd @gol
+-minline-float-divide-min-latency @gol
+-minline-float-divide-max-throughput @gol
+-mno-inline-float-divide @gol
+-minline-int-divide-min-latency @gol
+-minline-int-divide-max-throughput  @gol
+-mno-inline-int-divide @gol
+-minline-sqrt-min-latency  -minline-sqrt-max-throughput @gol
+-mno-inline-sqrt @gol
+-mdwarf2-asm  -mearly-stop-bits @gol
+-mfixed-range=@var{register-range}  -mtls-size=@var{tls-size} @gol
+-mtune=@var{cpu-type}  -milp32  -mlp64 @gol
+-msched-br-data-spec  -msched-ar-data-spec  -msched-control-spec @gol
+-msched-br-in-data-spec  -msched-ar-in-data-spec  -msched-in-control-spec @gol
+-msched-spec-ldc  -msched-spec-control-ldc @gol
+-msched-prefer-non-data-spec-insns  -msched-prefer-non-control-spec-insns @gol
+-msched-stop-bits-after-every-cycle  -msched-count-spec-in-critical-path @gol
+-msel-sched-dont-check-control-spec  -msched-fp-mem-deps-zero-cost @gol
+-msched-max-memory-insns-hard-limit  -msched-max-memory-insns=@var{max-insns}}
+
+@emph{LM32 Options}
+@gccoptlist{-mbarrel-shift-enabled  -mdivide-enabled  -mmultiply-enabled @gol
+-msign-extend-enabled  -muser-enabled}
+
+@emph{LoongArch Options}
+@gccoptlist{-march=@var{cpu-type}  -mtune=@var{cpu-type} -mabi=@var{base-abi-type} @gol
+-mfpu=@var{fpu-type} -msoft-float -msingle-float -mdouble-float @gol
+-mbranch-cost=@var{n}  -mcheck-zero-division -mno-check-zero-division @gol
+-mcond-move-int  -mno-cond-move-int @gol
+-mcond-move-float  -mno-cond-move-float @gol
+-memcpy  -mno-memcpy -mstrict-align -mno-strict-align @gol
+-mmax-inline-memcpy-size=@var{n} @gol
+-mexplicit-relocs -mno-explicit-relocs @gol
+-mdirect-extern-access -mno-direct-extern-access @gol
+-mcmodel=@var{code-model}}
+
+@emph{M32R/D Options}
+@gccoptlist{-m32r2  -m32rx  -m32r @gol
+-mdebug @gol
+-malign-loops  -mno-align-loops @gol
+-missue-rate=@var{number} @gol
+-mbranch-cost=@var{number} @gol
+-mmodel=@var{code-size-model-type} @gol
+-msdata=@var{sdata-type} @gol
+-mno-flush-func  -mflush-func=@var{name} @gol
+-mno-flush-trap  -mflush-trap=@var{number} @gol
+-G @var{num}}
+
+@emph{M32C Options}
+@gccoptlist{-mcpu=@var{cpu}  -msim  -memregs=@var{number}}
+
+@emph{M680x0 Options}
+@gccoptlist{-march=@var{arch}  -mcpu=@var{cpu}  -mtune=@var{tune} @gol
+-m68000  -m68020  -m68020-40  -m68020-60  -m68030  -m68040 @gol
+-m68060  -mcpu32  -m5200  -m5206e  -m528x  -m5307  -m5407 @gol
+-mcfv4e  -mbitfield  -mno-bitfield  -mc68000  -mc68020 @gol
+-mnobitfield  -mrtd  -mno-rtd  -mdiv  -mno-div  -mshort @gol
+-mno-short  -mhard-float  -m68881  -msoft-float  -mpcrel @gol
+-malign-int  -mstrict-align  -msep-data  -mno-sep-data @gol
+-mshared-library-id=n  -mid-shared-library  -mno-id-shared-library @gol
+-mxgot  -mno-xgot  -mlong-jump-table-offsets}
+
+@emph{MCore Options}
+@gccoptlist{-mhardlit  -mno-hardlit  -mdiv  -mno-div  -mrelax-immediates @gol
+-mno-relax-immediates  -mwide-bitfields  -mno-wide-bitfields @gol
+-m4byte-functions  -mno-4byte-functions  -mcallgraph-data @gol
+-mno-callgraph-data  -mslow-bytes  -mno-slow-bytes  -mno-lsim @gol
+-mlittle-endian  -mbig-endian  -m210  -m340  -mstack-increment}
+
+@emph{MeP Options}
+@gccoptlist{-mabsdiff  -mall-opts  -maverage  -mbased=@var{n}  -mbitops @gol
+-mc=@var{n}  -mclip  -mconfig=@var{name}  -mcop  -mcop32  -mcop64  -mivc2 @gol
+-mdc  -mdiv  -meb  -mel  -mio-volatile  -ml  -mleadz  -mm  -mminmax @gol
+-mmult  -mno-opts  -mrepeat  -ms  -msatur  -msdram  -msim  -msimnovec  -mtf @gol
+-mtiny=@var{n}}
+
+@emph{MicroBlaze Options}
+@gccoptlist{-msoft-float  -mhard-float  -msmall-divides  -mcpu=@var{cpu} @gol
+-mmemcpy  -mxl-soft-mul  -mxl-soft-div  -mxl-barrel-shift @gol
+-mxl-pattern-compare  -mxl-stack-check  -mxl-gp-opt  -mno-clearbss @gol
+-mxl-multiply-high  -mxl-float-convert  -mxl-float-sqrt @gol
+-mbig-endian  -mlittle-endian  -mxl-reorder  -mxl-mode-@var{app-model} @gol
+-mpic-data-is-text-relative}
+
+@emph{MIPS Options}
+@gccoptlist{-EL  -EB  -march=@var{arch}  -mtune=@var{arch} @gol
+-mips1  -mips2  -mips3  -mips4  -mips32  -mips32r2  -mips32r3  -mips32r5 @gol
+-mips32r6  -mips64  -mips64r2  -mips64r3  -mips64r5  -mips64r6 @gol
+-mips16  -mno-mips16  -mflip-mips16 @gol
+-minterlink-compressed  -mno-interlink-compressed @gol
+-minterlink-mips16  -mno-interlink-mips16 @gol
+-mabi=@var{abi}  -mabicalls  -mno-abicalls @gol
+-mshared  -mno-shared  -mplt  -mno-plt  -mxgot  -mno-xgot @gol
+-mgp32  -mgp64  -mfp32  -mfpxx  -mfp64  -mhard-float  -msoft-float @gol
+-mno-float  -msingle-float  -mdouble-float @gol
+-modd-spreg  -mno-odd-spreg @gol
+-mabs=@var{mode}  -mnan=@var{encoding} @gol
+-mdsp  -mno-dsp  -mdspr2  -mno-dspr2 @gol
+-mmcu  -mmno-mcu @gol
+-meva  -mno-eva @gol
+-mvirt  -mno-virt @gol
+-mxpa  -mno-xpa @gol
+-mcrc  -mno-crc @gol
+-mginv  -mno-ginv @gol
+-mmicromips  -mno-micromips @gol
+-mmsa  -mno-msa @gol
+-mloongson-mmi  -mno-loongson-mmi @gol
+-mloongson-ext  -mno-loongson-ext @gol
+-mloongson-ext2  -mno-loongson-ext2 @gol
+-mfpu=@var{fpu-type} @gol
+-msmartmips  -mno-smartmips @gol
+-mpaired-single  -mno-paired-single  -mdmx  -mno-mdmx @gol
+-mips3d  -mno-mips3d  -mmt  -mno-mt  -mllsc  -mno-llsc @gol
+-mlong64  -mlong32  -msym32  -mno-sym32 @gol
+-G@var{num}  -mlocal-sdata  -mno-local-sdata @gol
+-mextern-sdata  -mno-extern-sdata  -mgpopt  -mno-gopt @gol
+-membedded-data  -mno-embedded-data @gol
+-muninit-const-in-rodata  -mno-uninit-const-in-rodata @gol
+-mcode-readable=@var{setting} @gol
+-msplit-addresses  -mno-split-addresses @gol
+-mexplicit-relocs  -mno-explicit-relocs @gol
+-mcheck-zero-division  -mno-check-zero-division @gol
+-mdivide-traps  -mdivide-breaks @gol
+-mload-store-pairs  -mno-load-store-pairs @gol
+-munaligned-access  -mno-unaligned-access @gol
+-mmemcpy  -mno-memcpy  -mlong-calls  -mno-long-calls @gol
+-mmad  -mno-mad  -mimadd  -mno-imadd  -mfused-madd  -mno-fused-madd  -nocpp @gol
+-mfix-24k  -mno-fix-24k @gol
+-mfix-r4000  -mno-fix-r4000  -mfix-r4400  -mno-fix-r4400 @gol
+-mfix-r5900  -mno-fix-r5900 @gol
+-mfix-r10000  -mno-fix-r10000  -mfix-rm7000  -mno-fix-rm7000 @gol
+-mfix-vr4120  -mno-fix-vr4120 @gol
+-mfix-vr4130  -mno-fix-vr4130  -mfix-sb1  -mno-fix-sb1 @gol
+-mflush-func=@var{func}  -mno-flush-func @gol
+-mbranch-cost=@var{num}  -mbranch-likely  -mno-branch-likely @gol
+-mcompact-branches=@var{policy} @gol
+-mfp-exceptions  -mno-fp-exceptions @gol
+-mvr4130-align  -mno-vr4130-align  -msynci  -mno-synci @gol
+-mlxc1-sxc1  -mno-lxc1-sxc1  -mmadd4  -mno-madd4 @gol
+-mrelax-pic-calls  -mno-relax-pic-calls  -mmcount-ra-address @gol
+-mframe-header-opt  -mno-frame-header-opt}
+
+@emph{MMIX Options}
+@gccoptlist{-mlibfuncs  -mno-libfuncs  -mepsilon  -mno-epsilon  -mabi=gnu @gol
+-mabi=mmixware  -mzero-extend  -mknuthdiv  -mtoplevel-symbols @gol
+-melf  -mbranch-predict  -mno-branch-predict  -mbase-addresses @gol
+-mno-base-addresses  -msingle-exit  -mno-single-exit}
+
+@emph{MN10300 Options}
+@gccoptlist{-mmult-bug  -mno-mult-bug @gol
+-mno-am33  -mam33  -mam33-2  -mam34 @gol
+-mtune=@var{cpu-type} @gol
+-mreturn-pointer-on-d0 @gol
+-mno-crt0  -mrelax  -mliw  -msetlb}
+
+@emph{Moxie Options}
+@gccoptlist{-meb  -mel  -mmul.x  -mno-crt0}
+
+@emph{MSP430 Options}
+@gccoptlist{-msim  -masm-hex  -mmcu=  -mcpu=  -mlarge  -msmall  -mrelax @gol
+-mwarn-mcu @gol
+-mcode-region=  -mdata-region= @gol
+-msilicon-errata=  -msilicon-errata-warn= @gol
+-mhwmult=  -minrt  -mtiny-printf  -mmax-inline-shift=}
+
+@emph{NDS32 Options}
+@gccoptlist{-mbig-endian  -mlittle-endian @gol
+-mreduced-regs  -mfull-regs @gol
+-mcmov  -mno-cmov @gol
+-mext-perf  -mno-ext-perf @gol
+-mext-perf2  -mno-ext-perf2 @gol
+-mext-string  -mno-ext-string @gol
+-mv3push  -mno-v3push @gol
+-m16bit  -mno-16bit @gol
+-misr-vector-size=@var{num} @gol
+-mcache-block-size=@var{num} @gol
+-march=@var{arch} @gol
+-mcmodel=@var{code-model} @gol
+-mctor-dtor  -mrelax}
+
+@emph{Nios II Options}
+@gccoptlist{-G @var{num}  -mgpopt=@var{option}  -mgpopt  -mno-gpopt @gol
+-mgprel-sec=@var{regexp}  -mr0rel-sec=@var{regexp} @gol
+-mel  -meb @gol
+-mno-bypass-cache  -mbypass-cache @gol
+-mno-cache-volatile  -mcache-volatile @gol
+-mno-fast-sw-div  -mfast-sw-div @gol
+-mhw-mul  -mno-hw-mul  -mhw-mulx  -mno-hw-mulx  -mno-hw-div  -mhw-div @gol
+-mcustom-@var{insn}=@var{N}  -mno-custom-@var{insn} @gol
+-mcustom-fpu-cfg=@var{name} @gol
+-mhal  -msmallc  -msys-crt0=@var{name}  -msys-lib=@var{name} @gol
+-march=@var{arch}  -mbmx  -mno-bmx  -mcdx  -mno-cdx}
+
+@emph{Nvidia PTX Options}
+@gccoptlist{-m64  -mmainkernel  -moptimize}
+
+@emph{OpenRISC Options}
+@gccoptlist{-mboard=@var{name}  -mnewlib  -mhard-mul  -mhard-div @gol
+-msoft-mul  -msoft-div @gol
+-msoft-float  -mhard-float  -mdouble-float -munordered-float @gol
+-mcmov  -mror  -mrori  -msext  -msfimm  -mshftimm @gol
+-mcmodel=@var{code-model}}
+
+@emph{PDP-11 Options}
+@gccoptlist{-mfpu  -msoft-float  -mac0  -mno-ac0  -m40  -m45  -m10 @gol
+-mint32  -mno-int16  -mint16  -mno-int32 @gol
+-msplit  -munix-asm  -mdec-asm  -mgnu-asm  -mlra}
+
+@emph{picoChip Options}
+@gccoptlist{-mae=@var{ae_type}  -mvliw-lookahead=@var{N} @gol
+-msymbol-as-address  -mno-inefficient-warnings}
+
+@emph{PowerPC Options}
+See RS/6000 and PowerPC Options.
+
+@emph{PRU Options}
+@gccoptlist{-mmcu=@var{mcu}  -minrt  -mno-relax  -mloop @gol
+-mabi=@var{variant} @gol}
+
+@emph{RISC-V Options}
+@gccoptlist{-mbranch-cost=@var{N-instruction} @gol
+-mplt  -mno-plt @gol
+-mabi=@var{ABI-string} @gol
+-mfdiv  -mno-fdiv @gol
+-mdiv  -mno-div @gol
+-misa-spec=@var{ISA-spec-string} @gol
+-march=@var{ISA-string} @gol
+-mtune=@var{processor-string} @gol
+-mpreferred-stack-boundary=@var{num} @gol
+-msmall-data-limit=@var{N-bytes} @gol
+-msave-restore  -mno-save-restore @gol
+-mshorten-memrefs  -mno-shorten-memrefs @gol
+-mstrict-align  -mno-strict-align @gol
+-mcmodel=medlow  -mcmodel=medany @gol
+-mexplicit-relocs  -mno-explicit-relocs @gol
+-mrelax  -mno-relax @gol
+-mriscv-attribute  -mno-riscv-attribute @gol
+-malign-data=@var{type} @gol
+-mbig-endian  -mlittle-endian @gol
+-mstack-protector-guard=@var{guard}  -mstack-protector-guard-reg=@var{reg} @gol
+-mstack-protector-guard-offset=@var{offset}}
+-mcsr-check -mno-csr-check @gol
+
+@emph{RL78 Options}
+@gccoptlist{-msim  -mmul=none  -mmul=g13  -mmul=g14  -mallregs @gol
+-mcpu=g10  -mcpu=g13  -mcpu=g14  -mg10  -mg13  -mg14 @gol
+-m64bit-doubles  -m32bit-doubles  -msave-mduc-in-interrupts}
+
+@emph{RS/6000 and PowerPC Options}
+@gccoptlist{-mcpu=@var{cpu-type} @gol
+-mtune=@var{cpu-type} @gol
+-mcmodel=@var{code-model} @gol
+-mpowerpc64 @gol
+-maltivec  -mno-altivec @gol
+-mpowerpc-gpopt  -mno-powerpc-gpopt @gol
+-mpowerpc-gfxopt  -mno-powerpc-gfxopt @gol
+-mmfcrf  -mno-mfcrf  -mpopcntb  -mno-popcntb  -mpopcntd  -mno-popcntd @gol
+-mfprnd  -mno-fprnd @gol
+-mcmpb  -mno-cmpb  -mhard-dfp  -mno-hard-dfp @gol
+-mfull-toc   -mminimal-toc  -mno-fp-in-toc  -mno-sum-in-toc @gol
+-m64  -m32  -mxl-compat  -mno-xl-compat  -mpe @gol
+-malign-power  -malign-natural @gol
+-msoft-float  -mhard-float  -mmultiple  -mno-multiple @gol
+-mupdate  -mno-update @gol
+-mavoid-indexed-addresses  -mno-avoid-indexed-addresses @gol
+-mfused-madd  -mno-fused-madd  -mbit-align  -mno-bit-align @gol
+-mstrict-align  -mno-strict-align  -mrelocatable @gol
+-mno-relocatable  -mrelocatable-lib  -mno-relocatable-lib @gol
+-mtoc  -mno-toc  -mlittle  -mlittle-endian  -mbig  -mbig-endian @gol
+-mdynamic-no-pic  -mswdiv  -msingle-pic-base @gol
+-mprioritize-restricted-insns=@var{priority} @gol
+-msched-costly-dep=@var{dependence_type} @gol
+-minsert-sched-nops=@var{scheme} @gol
+-mcall-aixdesc  -mcall-eabi  -mcall-freebsd  @gol
+-mcall-linux  -mcall-netbsd  -mcall-openbsd  @gol
+-mcall-sysv  -mcall-sysv-eabi  -mcall-sysv-noeabi @gol
+-mtraceback=@var{traceback_type} @gol
+-maix-struct-return  -msvr4-struct-return @gol
+-mabi=@var{abi-type}  -msecure-plt  -mbss-plt @gol
+-mlongcall  -mno-longcall  -mpltseq  -mno-pltseq  @gol
+-mblock-move-inline-limit=@var{num} @gol
+-mblock-compare-inline-limit=@var{num} @gol
+-mblock-compare-inline-loop-limit=@var{num} @gol
+-mno-block-ops-unaligned-vsx @gol
+-mstring-compare-inline-limit=@var{num} @gol
+-misel  -mno-isel @gol
+-mvrsave  -mno-vrsave @gol
+-mmulhw  -mno-mulhw @gol
+-mdlmzb  -mno-dlmzb @gol
+-mprototype  -mno-prototype @gol
+-msim  -mmvme  -mads  -myellowknife  -memb  -msdata @gol
+-msdata=@var{opt}  -mreadonly-in-sdata  -mvxworks  -G @var{num} @gol
+-mrecip  -mrecip=@var{opt}  -mno-recip  -mrecip-precision @gol
+-mno-recip-precision @gol
+-mveclibabi=@var{type}  -mfriz  -mno-friz @gol
+-mpointers-to-nested-functions  -mno-pointers-to-nested-functions @gol
+-msave-toc-indirect  -mno-save-toc-indirect @gol
+-mpower8-fusion  -mno-mpower8-fusion  -mpower8-vector  -mno-power8-vector @gol
+-mcrypto  -mno-crypto  -mhtm  -mno-htm @gol
+-mquad-memory  -mno-quad-memory @gol
+-mquad-memory-atomic  -mno-quad-memory-atomic @gol
+-mcompat-align-parm  -mno-compat-align-parm @gol
+-mfloat128  -mno-float128  -mfloat128-hardware  -mno-float128-hardware @gol
+-mgnu-attribute  -mno-gnu-attribute @gol
+-mstack-protector-guard=@var{guard} -mstack-protector-guard-reg=@var{reg} @gol
+-mstack-protector-guard-offset=@var{offset} -mprefixed -mno-prefixed @gol
+-mpcrel -mno-pcrel -mmma -mno-mmma -mrop-protect -mno-rop-protect @gol
+-mprivileged -mno-privileged}
+
+@emph{RX Options}
+@gccoptlist{-m64bit-doubles  -m32bit-doubles  -fpu  -nofpu@gol
+-mcpu=@gol
+-mbig-endian-data  -mlittle-endian-data @gol
+-msmall-data @gol
+-msim  -mno-sim@gol
+-mas100-syntax  -mno-as100-syntax@gol
+-mrelax@gol
+-mmax-constant-size=@gol
+-mint-register=@gol
+-mpid@gol
+-mallow-string-insns  -mno-allow-string-insns@gol
+-mjsr@gol
+-mno-warn-multiple-fast-interrupts@gol
+-msave-acc-in-interrupts}
+
+@emph{S/390 and zSeries Options}
+@gccoptlist{-mtune=@var{cpu-type}  -march=@var{cpu-type} @gol
+-mhard-float  -msoft-float  -mhard-dfp  -mno-hard-dfp @gol
+-mlong-double-64  -mlong-double-128 @gol
+-mbackchain  -mno-backchain  -mpacked-stack  -mno-packed-stack @gol
+-msmall-exec  -mno-small-exec  -mmvcle  -mno-mvcle @gol
+-m64  -m31  -mdebug  -mno-debug  -mesa  -mzarch @gol
+-mhtm  -mvx  -mzvector @gol
+-mtpf-trace  -mno-tpf-trace  -mtpf-trace-skip  -mno-tpf-trace-skip @gol
+-mfused-madd  -mno-fused-madd @gol
+-mwarn-framesize  -mwarn-dynamicstack  -mstack-size  -mstack-guard @gol
+-mhotpatch=@var{halfwords},@var{halfwords}}
+
+@emph{Score Options}
+@gccoptlist{-meb  -mel @gol
+-mnhwloop @gol
+-muls @gol
+-mmac @gol
+-mscore5  -mscore5u  -mscore7  -mscore7d}
+
+@emph{SH Options}
+@gccoptlist{-m1  -m2  -m2e @gol
+-m2a-nofpu  -m2a-single-only  -m2a-single  -m2a @gol
+-m3  -m3e @gol
+-m4-nofpu  -m4-single-only  -m4-single  -m4 @gol
+-m4a-nofpu  -m4a-single-only  -m4a-single  -m4a  -m4al @gol
+-mb  -ml  -mdalign  -mrelax @gol
+-mbigtable  -mfmovd  -mrenesas  -mno-renesas  -mnomacsave @gol
+-mieee  -mno-ieee  -mbitops  -misize  -minline-ic_invalidate  -mpadstruct @gol
+-mprefergot  -musermode  -multcost=@var{number}  -mdiv=@var{strategy} @gol
+-mdivsi3_libfunc=@var{name}  -mfixed-range=@var{register-range} @gol
+-maccumulate-outgoing-args @gol
+-matomic-model=@var{atomic-model} @gol
+-mbranch-cost=@var{num}  -mzdcbranch  -mno-zdcbranch @gol
+-mcbranch-force-delay-slot @gol
+-mfused-madd  -mno-fused-madd  -mfsca  -mno-fsca  -mfsrra  -mno-fsrra @gol
+-mpretend-cmove  -mtas}
+
+@emph{Solaris 2 Options}
+@gccoptlist{-mclear-hwcap  -mno-clear-hwcap  -mimpure-text  -mno-impure-text @gol
+-pthreads}
+
+@emph{SPARC Options}
+@gccoptlist{-mcpu=@var{cpu-type} @gol
+-mtune=@var{cpu-type} @gol
+-mcmodel=@var{code-model} @gol
+-mmemory-model=@var{mem-model} @gol
+-m32  -m64  -mapp-regs  -mno-app-regs @gol
+-mfaster-structs  -mno-faster-structs  -mflat  -mno-flat @gol
+-mfpu  -mno-fpu  -mhard-float  -msoft-float @gol
+-mhard-quad-float  -msoft-quad-float @gol
+-mstack-bias  -mno-stack-bias @gol
+-mstd-struct-return  -mno-std-struct-return @gol
+-munaligned-doubles  -mno-unaligned-doubles @gol
+-muser-mode  -mno-user-mode @gol
+-mv8plus  -mno-v8plus  -mvis  -mno-vis @gol
+-mvis2  -mno-vis2  -mvis3  -mno-vis3 @gol
+-mvis4  -mno-vis4  -mvis4b  -mno-vis4b @gol
+-mcbcond  -mno-cbcond  -mfmaf  -mno-fmaf  -mfsmuld  -mno-fsmuld  @gol
+-mpopc  -mno-popc  -msubxc  -mno-subxc @gol
+-mfix-at697f  -mfix-ut699  -mfix-ut700  -mfix-gr712rc @gol
+-mlra  -mno-lra}
+
+@emph{System V Options}
+@gccoptlist{-Qy  -Qn  -YP,@var{paths}  -Ym,@var{dir}}
+
+@emph{V850 Options}
+@gccoptlist{-mlong-calls  -mno-long-calls  -mep  -mno-ep @gol
+-mprolog-function  -mno-prolog-function  -mspace @gol
+-mtda=@var{n}  -msda=@var{n}  -mzda=@var{n} @gol
+-mapp-regs  -mno-app-regs @gol
+-mdisable-callt  -mno-disable-callt @gol
+-mv850e2v3  -mv850e2  -mv850e1  -mv850es @gol
+-mv850e  -mv850  -mv850e3v5 @gol
+-mloop @gol
+-mrelax @gol
+-mlong-jumps @gol
+-msoft-float @gol
+-mhard-float @gol
+-mgcc-abi @gol
+-mrh850-abi @gol
+-mbig-switch}
+
+@emph{VAX Options}
+@gccoptlist{-mg  -mgnu  -munix  -mlra}
+
+@emph{Visium Options}
+@gccoptlist{-mdebug  -msim  -mfpu  -mno-fpu  -mhard-float  -msoft-float @gol
+-mcpu=@var{cpu-type}  -mtune=@var{cpu-type}  -msv-mode  -muser-mode}
+
+@emph{VMS Options}
+@gccoptlist{-mvms-return-codes  -mdebug-main=@var{prefix}  -mmalloc64 @gol
+-mpointer-size=@var{size}}
+
+@emph{VxWorks Options}
+@gccoptlist{-mrtp  -non-static  -Bstatic  -Bdynamic @gol
+-Xbind-lazy  -Xbind-now}
+
+@emph{x86 Options}
+@gccoptlist{-mtune=@var{cpu-type}  -march=@var{cpu-type} @gol
+-mtune-ctrl=@var{feature-list}  -mdump-tune-features  -mno-default @gol
+-mfpmath=@var{unit} @gol
+-masm=@var{dialect}  -mno-fancy-math-387 @gol
+-mno-fp-ret-in-387  -m80387  -mhard-float  -msoft-float @gol
+-mno-wide-multiply  -mrtd  -malign-double @gol
+-mpreferred-stack-boundary=@var{num} @gol
+-mincoming-stack-boundary=@var{num} @gol
+-mcld  -mcx16  -msahf  -mmovbe  -mcrc32 -mmwait @gol
+-mrecip  -mrecip=@var{opt} @gol
+-mvzeroupper  -mprefer-avx128  -mprefer-vector-width=@var{opt} @gol
+-mmove-max=@var{bits} -mstore-max=@var{bits} @gol
+-mmmx  -msse  -msse2  -msse3  -mssse3  -msse4.1  -msse4.2  -msse4  -mavx @gol
+-mavx2  -mavx512f  -mavx512pf  -mavx512er  -mavx512cd  -mavx512vl @gol
+-mavx512bw  -mavx512dq  -mavx512ifma  -mavx512vbmi  -msha  -maes @gol
+-mpclmul  -mfsgsbase  -mrdrnd  -mf16c  -mfma  -mpconfig  -mwbnoinvd  @gol
+-mptwrite  -mprefetchwt1  -mclflushopt  -mclwb  -mxsavec  -mxsaves @gol
+-msse4a  -m3dnow  -m3dnowa  -mpopcnt  -mabm  -mbmi  -mtbm  -mfma4  -mxop @gol
+-madx  -mlzcnt  -mbmi2  -mfxsr  -mxsave  -mxsaveopt  -mrtm  -mhle  -mlwp @gol
+-mmwaitx  -mclzero  -mpku  -mthreads  -mgfni  -mvaes  -mwaitpkg @gol
+-mshstk -mmanual-endbr -mcet-switch -mforce-indirect-call @gol
+-mavx512vbmi2 -mavx512bf16 -menqcmd @gol
+-mvpclmulqdq  -mavx512bitalg  -mmovdiri  -mmovdir64b  -mavx512vpopcntdq @gol
+-mavx5124fmaps  -mavx512vnni  -mavx5124vnniw  -mprfchw  -mrdpid @gol
+-mrdseed  -msgx -mavx512vp2intersect -mserialize -mtsxldtrk@gol
+-mamx-tile  -mamx-int8  -mamx-bf16 -muintr -mhreset -mavxvnni@gol
+-mavx512fp16 -mavxifma -mavxvnniint8 -mavxneconvert -mcmpccxadd -mamx-fp16 @gol
+-mprefetchi -mraoint @gol
+-mcldemote  -mms-bitfields  -mno-align-stringops  -minline-all-stringops @gol
+-minline-stringops-dynamically  -mstringop-strategy=@var{alg} @gol
+-mkl -mwidekl @gol
+-mmemcpy-strategy=@var{strategy}  -mmemset-strategy=@var{strategy} @gol
+-mpush-args  -maccumulate-outgoing-args  -m128bit-long-double @gol
+-m96bit-long-double  -mlong-double-64  -mlong-double-80  -mlong-double-128 @gol
+-mregparm=@var{num}  -msseregparm @gol
+-mveclibabi=@var{type}  -mvect8-ret-in-mem @gol
+-mpc32  -mpc64  -mpc80  -mstackrealign @gol
+-momit-leaf-frame-pointer  -mno-red-zone  -mno-tls-direct-seg-refs @gol
+-mcmodel=@var{code-model}  -mabi=@var{name}  -maddress-mode=@var{mode} @gol
+-m32  -m64  -mx32  -m16  -miamcu  -mlarge-data-threshold=@var{num} @gol
+-msse2avx  -mfentry  -mrecord-mcount  -mnop-mcount  -m8bit-idiv @gol
+-minstrument-return=@var{type} -mfentry-name=@var{name} -mfentry-section=@var{name} @gol
+-mavx256-split-unaligned-load  -mavx256-split-unaligned-store @gol
+-malign-data=@var{type}  -mstack-protector-guard=@var{guard} @gol
+-mstack-protector-guard-reg=@var{reg} @gol
+-mstack-protector-guard-offset=@var{offset} @gol
+-mstack-protector-guard-symbol=@var{symbol} @gol
+-mgeneral-regs-only  -mcall-ms2sysv-xlogues -mrelax-cmpxchg-loop @gol
+-mindirect-branch=@var{choice}  -mfunction-return=@var{choice} @gol
+-mindirect-branch-register -mharden-sls=@var{choice} @gol
+-mindirect-branch-cs-prefix -mneeded -mno-direct-extern-access}
+
+@emph{x86 Windows Options}
+@gccoptlist{-mconsole  -mcygwin  -mno-cygwin  -mdll @gol
+-mnop-fun-dllimport  -mthread @gol
+-municode  -mwin32  -mwindows  -fno-set-stack-executable}
+
+@emph{Xstormy16 Options}
+@gccoptlist{-msim}
+
+@emph{Xtensa Options}
+@gccoptlist{-mconst16  -mno-const16 @gol
+-mfused-madd  -mno-fused-madd @gol
+-mforce-no-pic @gol
+-mserialize-volatile  -mno-serialize-volatile @gol
+-mtext-section-literals  -mno-text-section-literals @gol
+-mauto-litpools  -mno-auto-litpools @gol
+-mtarget-align  -mno-target-align @gol
+-mlongcalls  -mno-longcalls @gol
+-mabi=@var{abi-type} @gol
+-mextra-l32r-costs=@var{cycles}}
+
+@emph{zSeries Options}
+See S/390 and zSeries Options.
+@end table
+
+
+@node Overall Options
+@section Options Controlling the Kind of Output
+
+Compilation can involve up to four stages: preprocessing, compilation
+proper, assembly and linking, always in that order.  GCC is capable of
+preprocessing and compiling several files either into several
+assembler input files, or into one assembler input file; then each
+assembler input file produces an object file, and linking combines all
+the object files (those newly compiled, and those specified as input)
+into an executable file.
+
+@cindex file name suffix
+For any given input file, the file name suffix determines what kind of
+compilation is done:
+
+@table @gcctabopt
+@item @var{file}.c
+C source code that must be preprocessed.
+
+@item @var{file}.i
+C source code that should not be preprocessed.
+
+@item @var{file}.ii
+C++ source code that should not be preprocessed.
+
+@item @var{file}.m
+Objective-C source code.  Note that you must link with the @file{libobjc}
+library to make an Objective-C program work.
+
+@item @var{file}.mi
+Objective-C source code that should not be preprocessed.
+
+@item @var{file}.mm
+@itemx @var{file}.M
+Objective-C++ source code.  Note that you must link with the @file{libobjc}
+library to make an Objective-C++ program work.  Note that @samp{.M} refers
+to a literal capital M@.
+
+@item @var{file}.mii
+Objective-C++ source code that should not be preprocessed.
+
+@item @var{file}.h
+C, C++, Objective-C or Objective-C++ header file to be turned into a
+precompiled header (default), or C, C++ header file to be turned into an
+Ada spec (via the @option{-fdump-ada-spec} switch).
+
+@item @var{file}.cc
+@itemx @var{file}.cp
+@itemx @var{file}.cxx
+@itemx @var{file}.cpp
+@itemx @var{file}.CPP
+@itemx @var{file}.c++
+@itemx @var{file}.C
+C++ source code that must be preprocessed.  Note that in @samp{.cxx},
+the last two letters must both be literally @samp{x}.  Likewise,
+@samp{.C} refers to a literal capital C@.
+
+@item @var{file}.mm
+@itemx @var{file}.M
+Objective-C++ source code that must be preprocessed.
+
+@item @var{file}.mii
+Objective-C++ source code that should not be preprocessed.
+
+@item @var{file}.hh
+@itemx @var{file}.H
+@itemx @var{file}.hp
+@itemx @var{file}.hxx
+@itemx @var{file}.hpp
+@itemx @var{file}.HPP
+@itemx @var{file}.h++
+@itemx @var{file}.tcc
+C++ header file to be turned into a precompiled header or Ada spec.
+
+@item @var{file}.f
+@itemx @var{file}.for
+@itemx @var{file}.ftn
+Fixed form Fortran source code that should not be preprocessed.
+
+@item @var{file}.F
+@itemx @var{file}.FOR
+@itemx @var{file}.fpp
+@itemx @var{file}.FPP
+@itemx @var{file}.FTN
+Fixed form Fortran source code that must be preprocessed (with the traditional
+preprocessor).
+
+@item @var{file}.f90
+@itemx @var{file}.f95
+@itemx @var{file}.f03
+@itemx @var{file}.f08
+Free form Fortran source code that should not be preprocessed.
+
+@item @var{file}.F90
+@itemx @var{file}.F95
+@itemx @var{file}.F03
+@itemx @var{file}.F08
+Free form Fortran source code that must be preprocessed (with the
+traditional preprocessor).
+
+@item @var{file}.go
+Go source code.
+
+@item @var{file}.d
+D source code.
+
+@item @var{file}.di
+D interface file.
+
+@item @var{file}.dd
+D documentation code (Ddoc).
+
+@item @var{file}.ads
+Ada source code file that contains a library unit declaration (a
+declaration of a package, subprogram, or generic, or a generic
+instantiation), or a library unit renaming declaration (a package,
+generic, or subprogram renaming declaration).  Such files are also
+called @dfn{specs}.
+
+@item @var{file}.adb
+Ada source code file containing a library unit body (a subprogram or
+package body).  Such files are also called @dfn{bodies}.
+
+@c GCC also knows about some suffixes for languages not yet included:
+@c Ratfor:
+@c @var{file}.r
+
+@item @var{file}.s
+Assembler code.
+
+@item @var{file}.S
+@itemx @var{file}.sx
+Assembler code that must be preprocessed.
+
+@item @var{other}
+An object file to be fed straight into linking.
+Any file name with no recognized suffix is treated this way.
+@end table
+
+@opindex x
+You can specify the input language explicitly with the @option{-x} option:
+
+@table @gcctabopt
+@item -x @var{language}
+Specify explicitly the @var{language} for the following input files
+(rather than letting the compiler choose a default based on the file
+name suffix).  This option applies to all following input files until
+the next @option{-x} option.  Possible values for @var{language} are:
+@smallexample
+c  c-header  cpp-output
+c++  c++-header  c++-system-header c++-user-header c++-cpp-output
+objective-c  objective-c-header  objective-c-cpp-output
+objective-c++ objective-c++-header objective-c++-cpp-output
+assembler  assembler-with-cpp
+ada
+d
+f77  f77-cpp-input f95  f95-cpp-input
+go
+@end smallexample
+
+@item -x none
+Turn off any specification of a language, so that subsequent files are
+handled according to their file name suffixes (as they are if @option{-x}
+has not been used at all).
+@end table
+
+If you only want some of the stages of compilation, you can use
+@option{-x} (or filename suffixes) to tell @command{gcc} where to start, and
+one of the options @option{-c}, @option{-S}, or @option{-E} to say where
+@command{gcc} is to stop.  Note that some combinations (for example,
+@samp{-x cpp-output -E}) instruct @command{gcc} to do nothing at all.
+
+@table @gcctabopt
+@item -c
+@opindex c
+Compile or assemble the source files, but do not link.  The linking
+stage simply is not done.  The ultimate output is in the form of an
+object file for each source file.
+
+By default, the object file name for a source file is made by replacing
+the suffix @samp{.c}, @samp{.i}, @samp{.s}, etc., with @samp{.o}.
+
+Unrecognized input files, not requiring compilation or assembly, are
+ignored.
+
+@item -S
+@opindex S
+Stop after the stage of compilation proper; do not assemble.  The output
+is in the form of an assembler code file for each non-assembler input
+file specified.
+
+By default, the assembler file name for a source file is made by
+replacing the suffix @samp{.c}, @samp{.i}, etc., with @samp{.s}.
+
+Input files that don't require compilation are ignored.
+
+@item -E
+@opindex E
+Stop after the preprocessing stage; do not run the compiler proper.  The
+output is in the form of preprocessed source code, which is sent to the
+standard output.
+
+Input files that don't require preprocessing are ignored.
+
+@cindex output file option
+@item -o @var{file}
+@opindex o
+Place the primary output in file @var{file}.  This applies to whatever
+sort of output is being produced, whether it be an executable file, an
+object file, an assembler file or preprocessed C code.
+
+If @option{-o} is not specified, the default is to put an executable
+file in @file{a.out}, the object file for
+@file{@var{source}.@var{suffix}} in @file{@var{source}.o}, its
+assembler file in @file{@var{source}.s}, a precompiled header file in
+@file{@var{source}.@var{suffix}.gch}, and all preprocessed C source on
+standard output.
+
+Though @option{-o} names only the primary output, it also affects the
+naming of auxiliary and dump outputs.  See the examples below.  Unless
+overridden, both auxiliary outputs and dump outputs are placed in the
+same directory as the primary output.  In auxiliary outputs, the suffix
+of the input file is replaced with that of the auxiliary output file
+type; in dump outputs, the suffix of the dump file is appended to the
+input file suffix.  In compilation commands, the base name of both
+auxiliary and dump outputs is that of the primary output; in compile and
+link commands, the primary output name, minus the executable suffix, is
+combined with the input file name.  If both share the same base name,
+disregarding the suffix, the result of the combination is that base
+name, otherwise, they are concatenated, separated by a dash.
+
+@smallexample
+gcc -c foo.c ...
+@end smallexample
+
+will use @file{foo.o} as the primary output, and place aux outputs and
+dumps next to it, e.g., aux file @file{foo.dwo} for
+@option{-gsplit-dwarf}, and dump file @file{foo.c.???r.final} for
+@option{-fdump-rtl-final}.
+
+If a non-linker output file is explicitly specified, aux and dump files
+by default take the same base name:
+
+@smallexample
+gcc -c foo.c -o dir/foobar.o ...
+@end smallexample
+
+will name aux outputs @file{dir/foobar.*} and dump outputs
+@file{dir/foobar.c.*}.
+
+A linker output will instead prefix aux and dump outputs:
+
+@smallexample
+gcc foo.c bar.c -o dir/foobar ...
+@end smallexample
+
+will generally name aux outputs @file{dir/foobar-foo.*} and
+@file{dir/foobar-bar.*}, and dump outputs @file{dir/foobar-foo.c.*} and
+@file{dir/foobar-bar.c.*}.
+
+The one exception to the above is when the executable shares the base
+name with the single input:
+
+@smallexample
+gcc foo.c -o dir/foo ...
+@end smallexample
+
+in which case aux outputs are named @file{dir/foo.*} and dump outputs
+named @file{dir/foo.c.*}.
+
+The location and the names of auxiliary and dump outputs can be adjusted
+by the options @option{-dumpbase}, @option{-dumpbase-ext},
+@option{-dumpdir}, @option{-save-temps=cwd}, and
+@option{-save-temps=obj}.
+
+
+@item -dumpbase @var{dumpbase}
+@opindex dumpbase
+This option sets the base name for auxiliary and dump output files.  It
+does not affect the name of the primary output file.  Intermediate
+outputs, when preserved, are not regarded as primary outputs, but as
+auxiliary outputs:
+
+@smallexample
+gcc -save-temps -S foo.c
+@end smallexample
+
+saves the (no longer) temporary preprocessed file in @file{foo.i}, and
+then compiles to the (implied) output file @file{foo.s}, whereas:
+
+@smallexample
+gcc -save-temps -dumpbase save-foo -c foo.c
+@end smallexample
+
+preprocesses to in @file{save-foo.i}, compiles to @file{save-foo.s} (now
+an intermediate, thus auxiliary output), and then assembles to the
+(implied) output file @file{foo.o}.
+
+Absent this option, dump and aux files take their names from the input
+file, or from the (non-linker) output file, if one is explicitly
+specified: dump output files (e.g. those requested by @option{-fdump-*}
+options) with the input name suffix, and aux output files (those
+requested by other non-dump options, e.g. @code{-save-temps},
+@code{-gsplit-dwarf}, @code{-fcallgraph-info}) without it.
+
+Similar suffix differentiation of dump and aux outputs can be attained
+for explicitly-given @option{-dumpbase basename.suf} by also specifying
+@option{-dumpbase-ext .suf}.
+
+If @var{dumpbase} is explicitly specified with any directory component,
+any @var{dumppfx} specification (e.g. @option{-dumpdir} or
+@option{-save-temps=*}) is ignored, and instead of appending to it,
+@var{dumpbase} fully overrides it:
+
+@smallexample
+gcc foo.c -c -o dir/foo.o -dumpbase alt/foo \
+  -dumpdir pfx- -save-temps=cwd ...
+@end smallexample
+
+creates auxiliary and dump outputs named @file{alt/foo.*}, disregarding
+@file{dir/} in @option{-o}, the @file{./} prefix implied by
+@option{-save-temps=cwd}, and @file{pfx-} in @option{-dumpdir}.
+
+When @option{-dumpbase} is specified in a command that compiles multiple
+inputs, or that compiles and then links, it may be combined with
+@var{dumppfx}, as specified under @option{-dumpdir}.  Then, each input
+file is compiled using the combined @var{dumppfx}, and default values
+for @var{dumpbase} and @var{auxdropsuf} are computed for each input
+file:
+
+@smallexample
+gcc foo.c bar.c -c -dumpbase main ...
+@end smallexample
+
+creates @file{foo.o} and @file{bar.o} as primary outputs, and avoids
+overwriting the auxiliary and dump outputs by using the @var{dumpbase}
+as a prefix, creating auxiliary and dump outputs named @file{main-foo.*}
+and @file{main-bar.*}.
+
+An empty string specified as @var{dumpbase} avoids the influence of the
+output basename in the naming of auxiliary and dump outputs during
+compilation, computing default values :
+
+@smallexample
+gcc -c foo.c -o dir/foobar.o -dumpbase '' ...
+@end smallexample
+
+will name aux outputs @file{dir/foo.*} and dump outputs
+@file{dir/foo.c.*}.  Note how their basenames are taken from the input
+name, but the directory still defaults to that of the output.
+
+The empty-string dumpbase does not prevent the use of the output
+basename for outputs during linking:
+
+@smallexample
+gcc foo.c bar.c -o dir/foobar -dumpbase '' -flto ...
+@end smallexample
+
+The compilation of the source files will name auxiliary outputs
+@file{dir/foo.*} and @file{dir/bar.*}, and dump outputs
+@file{dir/foo.c.*} and @file{dir/bar.c.*}.  LTO recompilation during
+linking will use @file{dir/foobar.} as the prefix for dumps and
+auxiliary files.
+
+
+@item -dumpbase-ext @var{auxdropsuf}
+@opindex dumpbase-ext
+When forming the name of an auxiliary (but not a dump) output file, drop
+trailing @var{auxdropsuf} from @var{dumpbase} before appending any
+suffixes.  If not specified, this option defaults to the suffix of a
+default @var{dumpbase}, i.e., the suffix of the input file when
+@option{-dumpbase} is not present in the command line, or @var{dumpbase}
+is combined with @var{dumppfx}.
+
+@smallexample
+gcc foo.c -c -o dir/foo.o -dumpbase x-foo.c -dumpbase-ext .c ...
+@end smallexample
+
+creates @file{dir/foo.o} as the main output, and generates auxiliary
+outputs in @file{dir/x-foo.*}, taking the location of the primary
+output, and dropping the @file{.c} suffix from the @var{dumpbase}.  Dump
+outputs retain the suffix: @file{dir/x-foo.c.*}.
+
+This option is disregarded if it does not match the suffix of a
+specified @var{dumpbase}, except as an alternative to the executable
+suffix when appending the linker output base name to @var{dumppfx}, as
+specified below:
+
+@smallexample
+gcc foo.c bar.c -o main.out -dumpbase-ext .out ...
+@end smallexample
+
+creates @file{main.out} as the primary output, and avoids overwriting
+the auxiliary and dump outputs by using the executable name minus
+@var{auxdropsuf} as a prefix, creating auxiliary outputs named
+@file{main-foo.*} and @file{main-bar.*} and dump outputs named
+@file{main-foo.c.*} and @file{main-bar.c.*}.
+
+
+@item -dumpdir @var{dumppfx}
+@opindex dumpdir
+When forming the name of an auxiliary or dump output file, use
+@var{dumppfx} as a prefix:
+
+@smallexample
+gcc -dumpdir pfx- -c foo.c ...
+@end smallexample
+
+creates @file{foo.o} as the primary output, and auxiliary outputs named
+@file{pfx-foo.*}, combining the given @var{dumppfx} with the default
+@var{dumpbase} derived from the default primary output, derived in turn
+from the input name.  Dump outputs also take the input name suffix:
+@file{pfx-foo.c.*}.
+
+If @var{dumppfx} is to be used as a directory name, it must end with a
+directory separator:
+
+@smallexample
+gcc -dumpdir dir/ -c foo.c -o obj/bar.o ...
+@end smallexample
+
+creates @file{obj/bar.o} as the primary output, and auxiliary outputs
+named @file{dir/bar.*}, combining the given @var{dumppfx} with the
+default @var{dumpbase} derived from the primary output name.  Dump
+outputs also take the input name suffix: @file{dir/bar.c.*}.
+
+It defaults to the location of the output file, unless the output
+file is a special file like @code{/dev/null}. Options
+@option{-save-temps=cwd} and @option{-save-temps=obj} override this
+default, just like an explicit @option{-dumpdir} option.  In case
+multiple such options are given, the last one prevails:
+
+@smallexample
+gcc -dumpdir pfx- -c foo.c -save-temps=obj ...
+@end smallexample
+
+outputs @file{foo.o}, with auxiliary outputs named @file{foo.*} because
+@option{-save-temps=*} overrides the @var{dumppfx} given by the earlier
+@option{-dumpdir} option.  It does not matter that @option{=obj} is the
+default for @option{-save-temps}, nor that the output directory is
+implicitly the current directory.  Dump outputs are named
+@file{foo.c.*}.
+
+When compiling from multiple input files, if @option{-dumpbase} is
+specified, @var{dumpbase}, minus a @var{auxdropsuf} suffix, and a dash
+are appended to (or override, if containing any directory components) an
+explicit or defaulted @var{dumppfx}, so that each of the multiple
+compilations gets differently-named aux and dump outputs.
+
+@smallexample
+gcc foo.c bar.c -c -dumpdir dir/pfx- -dumpbase main ...
+@end smallexample
+
+outputs auxiliary dumps to @file{dir/pfx-main-foo.*} and
+@file{dir/pfx-main-bar.*}, appending @var{dumpbase}- to @var{dumppfx}.
+Dump outputs retain the input file suffix: @file{dir/pfx-main-foo.c.*}
+and @file{dir/pfx-main-bar.c.*}, respectively.  Contrast with the
+single-input compilation:
+
+@smallexample
+gcc foo.c -c -dumpdir dir/pfx- -dumpbase main ...
+@end smallexample
+
+that, applying @option{-dumpbase} to a single source, does not compute
+and append a separate @var{dumpbase} per input file.  Its auxiliary and
+dump outputs go in @file{dir/pfx-main.*}.
+
+When compiling and then linking from multiple input files, a defaulted
+or explicitly specified @var{dumppfx} also undergoes the @var{dumpbase}-
+transformation above (e.g. the compilation of @file{foo.c} and
+@file{bar.c} above, but without @option{-c}).  If neither
+@option{-dumpdir} nor @option{-dumpbase} are given, the linker output
+base name, minus @var{auxdropsuf}, if specified, or the executable
+suffix otherwise, plus a dash is appended to the default @var{dumppfx}
+instead.  Note, however, that unlike earlier cases of linking:
+
+@smallexample
+gcc foo.c bar.c -dumpdir dir/pfx- -o main ...
+@end smallexample
+
+does not append the output name @file{main} to @var{dumppfx}, because
+@option{-dumpdir} is explicitly specified.  The goal is that the
+explicitly-specified @var{dumppfx} may contain the specified output name
+as part of the prefix, if desired; only an explicitly-specified
+@option{-dumpbase} would be combined with it, in order to avoid simply
+discarding a meaningful option.
+
+When compiling and then linking from a single input file, the linker
+output base name will only be appended to the default @var{dumppfx} as
+above if it does not share the base name with the single input file
+name.  This has been covered in single-input linking cases above, but
+not with an explicit @option{-dumpdir} that inhibits the combination,
+even if overridden by @option{-save-temps=*}:
+
+@smallexample
+gcc foo.c -dumpdir alt/pfx- -o dir/main.exe -save-temps=cwd ...
+@end smallexample
+
+Auxiliary outputs are named @file{foo.*}, and dump outputs
+@file{foo.c.*}, in the current working directory as ultimately requested
+by @option{-save-temps=cwd}.
+
+Summing it all up for an intuitive though slightly imprecise data flow:
+the primary output name is broken into a directory part and a basename
+part; @var{dumppfx} is set to the former, unless overridden by
+@option{-dumpdir} or @option{-save-temps=*}, and @var{dumpbase} is set
+to the latter, unless overriden by @option{-dumpbase}.  If there are
+multiple inputs or linking, this @var{dumpbase} may be combined with
+@var{dumppfx} and taken from each input file.  Auxiliary output names
+for each input are formed by combining @var{dumppfx}, @var{dumpbase}
+minus suffix, and the auxiliary output suffix; dump output names are
+only different in that the suffix from @var{dumpbase} is retained.
+
+When it comes to auxiliary and dump outputs created during LTO
+recompilation, a combination of @var{dumppfx} and @var{dumpbase}, as
+given or as derived from the linker output name but not from inputs,
+even in cases in which this combination would not otherwise be used as
+such, is passed down with a trailing period replacing the compiler-added
+dash, if any, as a @option{-dumpdir} option to @command{lto-wrapper};
+being involved in linking, this program does not normally get any
+@option{-dumpbase} and @option{-dumpbase-ext}, and it ignores them.
+
+When running sub-compilers, @command{lto-wrapper} appends LTO stage
+names to the received @var{dumppfx}, ensures it contains a directory
+component so that it overrides any @option{-dumpdir}, and passes that as
+@option{-dumpbase} to sub-compilers.
+
+@item -v
+@opindex v
+Print (on standard error output) the commands executed to run the stages
+of compilation.  Also print the version number of the compiler driver
+program and of the preprocessor and the compiler proper.
+
+@item -###
+@opindex ###
+Like @option{-v} except the commands are not executed and arguments
+are quoted unless they contain only alphanumeric characters or @code{./-_}.
+This is useful for shell scripts to capture the driver-generated command lines.
+
+@item --help
+@opindex help
+Print (on the standard output) a description of the command-line options
+understood by @command{gcc}.  If the @option{-v} option is also specified
+then @option{--help} is also passed on to the various processes
+invoked by @command{gcc}, so that they can display the command-line options
+they accept.  If the @option{-Wextra} option has also been specified
+(prior to the @option{--help} option), then command-line options that
+have no documentation associated with them are also displayed.
+
+@item --target-help
+@opindex target-help
+Print (on the standard output) a description of target-specific command-line
+options for each tool.  For some targets extra target-specific
+information may also be printed.
+
+@item --help=@{@var{class}@r{|[}^@r{]}@var{qualifier}@}@r{[},@dots{}@r{]}
+Print (on the standard output) a description of the command-line
+options understood by the compiler that fit into all specified classes
+and qualifiers.  These are the supported classes:
+
+@table @asis
+@item @samp{optimizers}
+Display all of the optimization options supported by the
+compiler.
+
+@item @samp{warnings}
+Display all of the options controlling warning messages
+produced by the compiler.
+
+@item @samp{target}
+Display target-specific options.  Unlike the
+@option{--target-help} option however, target-specific options of the
+linker and assembler are not displayed.  This is because those
+tools do not currently support the extended @option{--help=} syntax.
+
+@item @samp{params}
+Display the values recognized by the @option{--param}
+option.
+
+@item @var{language}
+Display the options supported for @var{language}, where
+@var{language} is the name of one of the languages supported in this
+version of GCC@.  If an option is supported by all languages, one needs
+to select @samp{common} class.
+
+@item @samp{common}
+Display the options that are common to all languages.
+@end table
+
+These are the supported qualifiers:
+
+@table @asis
+@item @samp{undocumented}
+Display only those options that are undocumented.
+
+@item @samp{joined}
+Display options taking an argument that appears after an equal
+sign in the same continuous piece of text, such as:
+@samp{--help=target}.
+
+@item @samp{separate}
+Display options taking an argument that appears as a separate word
+following the original option, such as: @samp{-o output-file}.
+@end table
+
+Thus for example to display all the undocumented target-specific
+switches supported by the compiler, use:
+
+@smallexample
+--help=target,undocumented
+@end smallexample
+
+The sense of a qualifier can be inverted by prefixing it with the
+@samp{^} character, so for example to display all binary warning
+options (i.e., ones that are either on or off and that do not take an
+argument) that have a description, use:
+
+@smallexample
+--help=warnings,^joined,^undocumented
+@end smallexample
+
+The argument to @option{--help=} should not consist solely of inverted
+qualifiers.
+
+Combining several classes is possible, although this usually
+restricts the output so much that there is nothing to display.  One
+case where it does work, however, is when one of the classes is
+@var{target}.  For example, to display all the target-specific
+optimization options, use:
+
+@smallexample
+--help=target,optimizers
+@end smallexample
+
+The @option{--help=} option can be repeated on the command line.  Each
+successive use displays its requested class of options, skipping
+those that have already been displayed.  If @option{--help} is also
+specified anywhere on the command line then this takes precedence
+over any @option{--help=} option.
+
+If the @option{-Q} option appears on the command line before the
+@option{--help=} option, then the descriptive text displayed by
+@option{--help=} is changed.  Instead of describing the displayed
+options, an indication is given as to whether the option is enabled,
+disabled or set to a specific value (assuming that the compiler
+knows this at the point where the @option{--help=} option is used).
+
+Here is a truncated example from the ARM port of @command{gcc}:
+
+@smallexample
+  % gcc -Q -mabi=2 --help=target -c
+  The following options are target specific:
+  -mabi=                                2
+  -mabort-on-noreturn                   [disabled]
+  -mapcs                                [disabled]
+@end smallexample
+
+The output is sensitive to the effects of previous command-line
+options, so for example it is possible to find out which optimizations
+are enabled at @option{-O2} by using:
+
+@smallexample
+-Q -O2 --help=optimizers
+@end smallexample
+
+Alternatively you can discover which binary optimizations are enabled
+by @option{-O3} by using:
+
+@smallexample
+gcc -c -Q -O3 --help=optimizers > /tmp/O3-opts
+gcc -c -Q -O2 --help=optimizers > /tmp/O2-opts
+diff /tmp/O2-opts /tmp/O3-opts | grep enabled
+@end smallexample
+
+@item --version
+@opindex version
+Display the version number and copyrights of the invoked GCC@.
+
+@item -pass-exit-codes
+@opindex pass-exit-codes
+Normally the @command{gcc} program exits with the code of 1 if any
+phase of the compiler returns a non-success return code.  If you specify
+@option{-pass-exit-codes}, the @command{gcc} program instead returns with
+the numerically highest error produced by any phase returning an error
+indication.  The C, C++, and Fortran front ends return 4 if an internal
+compiler error is encountered.
+
+@item -pipe
+@opindex pipe
+Use pipes rather than temporary files for communication between the
+various stages of compilation.  This fails to work on some systems where
+the assembler is unable to read from a pipe; but the GNU assembler has
+no trouble.
+
+@item -specs=@var{file}
+@opindex specs
+Process @var{file} after the compiler reads in the standard @file{specs}
+file, in order to override the defaults which the @command{gcc} driver
+program uses when determining what switches to pass to @command{cc1},
+@command{cc1plus}, @command{as}, @command{ld}, etc.  More than one
+@option{-specs=@var{file}} can be specified on the command line, and they
+are processed in order, from left to right.  @xref{Spec Files}, for
+information about the format of the @var{file}.
+
+@item -wrapper
+@opindex wrapper
+Invoke all subcommands under a wrapper program.  The name of the
+wrapper program and its parameters are passed as a comma separated
+list.
+
+@smallexample
+gcc -c t.c -wrapper gdb,--args
+@end smallexample
+
+@noindent
+This invokes all subprograms of @command{gcc} under
+@samp{gdb --args}, thus the invocation of @command{cc1} is
+@samp{gdb --args cc1 @dots{}}.
+
+@item -ffile-prefix-map=@var{old}=@var{new}
+@opindex ffile-prefix-map
+When compiling files residing in directory @file{@var{old}}, record
+any references to them in the result of the compilation as if the
+files resided in directory @file{@var{new}} instead.  Specifying this
+option is equivalent to specifying all the individual
+@option{-f*-prefix-map} options.  This can be used to make reproducible
+builds that are location independent.  See also
+@option{-fmacro-prefix-map}, @option{-fdebug-prefix-map} and
+@option{-fprofile-prefix-map}.
+
+@item -fplugin=@var{name}.so
+@opindex fplugin
+Load the plugin code in file @var{name}.so, assumed to be a
+shared object to be dlopen'd by the compiler.  The base name of
+the shared object file is used to identify the plugin for the
+purposes of argument parsing (See
+@option{-fplugin-arg-@var{name}-@var{key}=@var{value}} below).
+Each plugin should define the callback functions specified in the
+Plugins API.
+
+@item -fplugin-arg-@var{name}-@var{key}=@var{value}
+@opindex fplugin-arg
+Define an argument called @var{key} with a value of @var{value}
+for the plugin called @var{name}.
+
+@item -fdump-ada-spec@r{[}-slim@r{]}
+@opindex fdump-ada-spec
+For C and C++ source and include files, generate corresponding Ada specs.
+@xref{Generating Ada Bindings for C and C++ headers,,, gnat_ugn,
+GNAT User's Guide}, which provides detailed documentation on this feature.
+
+@item -fada-spec-parent=@var{unit}
+@opindex fada-spec-parent
+In conjunction with @option{-fdump-ada-spec@r{[}-slim@r{]}} above, generate
+Ada specs as child units of parent @var{unit}.
+
+@item -fdump-go-spec=@var{file}
+@opindex fdump-go-spec
+For input files in any language, generate corresponding Go
+declarations in @var{file}.  This generates Go @code{const},
+@code{type}, @code{var}, and @code{func} declarations which may be a
+useful way to start writing a Go interface to code written in some
+other language.
+
+@include @value{srcdir}/../libiberty/at-file.texi
+@end table
+
+@node Invoking G++
+@section Compiling C++ Programs
+
+@cindex suffixes for C++ source
+@cindex C++ source file suffixes
+C++ source files conventionally use one of the suffixes @samp{.C},
+@samp{.cc}, @samp{.cpp}, @samp{.CPP}, @samp{.c++}, @samp{.cp}, or
+@samp{.cxx}; C++ header files often use @samp{.hh}, @samp{.hpp},
+@samp{.H}, or (for shared template code) @samp{.tcc}; and
+preprocessed C++ files use the suffix @samp{.ii}.  GCC recognizes
+files with these names and compiles them as C++ programs even if you
+call the compiler the same way as for compiling C programs (usually
+with the name @command{gcc}).
+
+@findex g++
+@findex c++
+However, the use of @command{gcc} does not add the C++ library.
+@command{g++} is a program that calls GCC and automatically specifies linking
+against the C++ library.  It treats @samp{.c},
+@samp{.h} and @samp{.i} files as C++ source files instead of C source
+files unless @option{-x} is used.  This program is also useful when
+precompiling a C header file with a @samp{.h} extension for use in C++
+compilations.  On many systems, @command{g++} is also installed with
+the name @command{c++}.
+
+@cindex invoking @command{g++}
+When you compile C++ programs, you may specify many of the same
+command-line options that you use for compiling programs in any
+language; or command-line options meaningful for C and related
+languages; or options that are meaningful only for C++ programs.
+@xref{C Dialect Options,,Options Controlling C Dialect}, for
+explanations of options for languages related to C@.
+@xref{C++ Dialect Options,,Options Controlling C++ Dialect}, for
+explanations of options that are meaningful only for C++ programs.
+
+@node C Dialect Options
+@section Options Controlling C Dialect
+@cindex dialect options
+@cindex language dialect options
+@cindex options, dialect
+
+The following options control the dialect of C (or languages derived
+from C, such as C++, Objective-C and Objective-C++) that the compiler
+accepts:
+
+@table @gcctabopt
+@cindex ANSI support
+@cindex ISO support
+@item -ansi
+@opindex ansi
+In C mode, this is equivalent to @option{-std=c90}. In C++ mode, it is
+equivalent to @option{-std=c++98}.
+
+This turns off certain features of GCC that are incompatible with ISO
+C90 (when compiling C code), or of standard C++ (when compiling C++ code),
+such as the @code{asm} and @code{typeof} keywords, and
+predefined macros such as @code{unix} and @code{vax} that identify the
+type of system you are using.  It also enables the undesirable and
+rarely used ISO trigraph feature.  For the C compiler,
+it disables recognition of C++ style @samp{//} comments as well as
+the @code{inline} keyword.
+
+The alternate keywords @code{__asm__}, @code{__extension__},
+@code{__inline__} and @code{__typeof__} continue to work despite
+@option{-ansi}.  You would not want to use them in an ISO C program, of
+course, but it is useful to put them in header files that might be included
+in compilations done with @option{-ansi}.  Alternate predefined macros
+such as @code{__unix__} and @code{__vax__} are also available, with or
+without @option{-ansi}.
+
+The @option{-ansi} option does not cause non-ISO programs to be
+rejected gratuitously.  For that, @option{-Wpedantic} is required in
+addition to @option{-ansi}.  @xref{Warning Options}.
+
+The macro @code{__STRICT_ANSI__} is predefined when the @option{-ansi}
+option is used.  Some header files may notice this macro and refrain
+from declaring certain functions or defining certain macros that the
+ISO standard doesn't call for; this is to avoid interfering with any
+programs that might use these names for other things.
+
+Functions that are normally built in but do not have semantics
+defined by ISO C (such as @code{alloca} and @code{ffs}) are not built-in
+functions when @option{-ansi} is used.  @xref{Other Builtins,,Other
+built-in functions provided by GCC}, for details of the functions
+affected.
+
+@item -std=
+@opindex std
+Determine the language standard. @xref{Standards,,Language Standards
+Supported by GCC}, for details of these standard versions.  This option
+is currently only supported when compiling C or C++.
+
+The compiler can accept several base standards, such as @samp{c90} or
+@samp{c++98}, and GNU dialects of those standards, such as
+@samp{gnu90} or @samp{gnu++98}.  When a base standard is specified, the
+compiler accepts all programs following that standard plus those
+using GNU extensions that do not contradict it.  For example,
+@option{-std=c90} turns off certain features of GCC that are
+incompatible with ISO C90, such as the @code{asm} and @code{typeof}
+keywords, but not other GNU extensions that do not have a meaning in
+ISO C90, such as omitting the middle term of a @code{?:}
+expression. On the other hand, when a GNU dialect of a standard is
+specified, all features supported by the compiler are enabled, even when
+those features change the meaning of the base standard.  As a result, some
+strict-conforming programs may be rejected.  The particular standard
+is used by @option{-Wpedantic} to identify which features are GNU
+extensions given that version of the standard. For example
+@option{-std=gnu90 -Wpedantic} warns about C++ style @samp{//}
+comments, while @option{-std=gnu99 -Wpedantic} does not.
+
+A value for this option must be provided; possible values are
+
+@table @samp
+@item c90
+@itemx c89
+@itemx iso9899:1990
+Support all ISO C90 programs (certain GNU extensions that conflict
+with ISO C90 are disabled). Same as @option{-ansi} for C code.
+
+@item iso9899:199409
+ISO C90 as modified in amendment 1.
+
+@item c99
+@itemx c9x
+@itemx iso9899:1999
+@itemx iso9899:199x
+ISO C99.  This standard is substantially completely supported, modulo
+bugs and floating-point issues
+(mainly but not entirely relating to optional C99 features from
+Annexes F and G).  See
+@w{@uref{https://gcc.gnu.org/c99status.html}} for more information.  The
+names @samp{c9x} and @samp{iso9899:199x} are deprecated.
+
+@item c11
+@itemx c1x
+@itemx iso9899:2011
+ISO C11, the 2011 revision of the ISO C standard.  This standard is
+substantially completely supported, modulo bugs, floating-point issues
+(mainly but not entirely relating to optional C11 features from
+Annexes F and G) and the optional Annexes K (Bounds-checking
+interfaces) and L (Analyzability).  The name @samp{c1x} is deprecated.
+
+@item c17
+@itemx c18
+@itemx iso9899:2017
+@itemx iso9899:2018
+ISO C17, the 2017 revision of the ISO C standard
+(published in 2018).  This standard is
+same as C11 except for corrections of defects (all of which are also
+applied with @option{-std=c11}) and a new value of
+@code{__STDC_VERSION__}, and so is supported to the same extent as C11.
+
+@item c2x
+The next version of the ISO C standard, still under development.  The
+support for this version is experimental and incomplete.
+
+@item gnu90
+@itemx gnu89
+GNU dialect of ISO C90 (including some C99 features).
+
+@item gnu99
+@itemx gnu9x
+GNU dialect of ISO C99.  The name @samp{gnu9x} is deprecated.
+
+@item gnu11
+@itemx gnu1x
+GNU dialect of ISO C11.
+The name @samp{gnu1x} is deprecated.
+
+@item gnu17
+@itemx gnu18
+GNU dialect of ISO C17.  This is the default for C code.
+
+@item gnu2x
+The next version of the ISO C standard, still under development, plus
+GNU extensions.  The support for this version is experimental and
+incomplete.
+
+@item c++98
+@itemx c++03
+The 1998 ISO C++ standard plus the 2003 technical corrigendum and some
+additional defect reports. Same as @option{-ansi} for C++ code.
+
+@item gnu++98
+@itemx gnu++03
+GNU dialect of @option{-std=c++98}.
+
+@item c++11
+@itemx c++0x
+The 2011 ISO C++ standard plus amendments.
+The name @samp{c++0x} is deprecated.
+
+@item gnu++11
+@itemx gnu++0x
+GNU dialect of @option{-std=c++11}.
+The name @samp{gnu++0x} is deprecated.
+
+@item c++14
+@itemx c++1y
+The 2014 ISO C++ standard plus amendments.
+The name @samp{c++1y} is deprecated.
+
+@item gnu++14
+@itemx gnu++1y
+GNU dialect of @option{-std=c++14}.
+The name @samp{gnu++1y} is deprecated.
+
+@item c++17
+@itemx c++1z
+The 2017 ISO C++ standard plus amendments.
+The name @samp{c++1z} is deprecated.
+
+@item gnu++17
+@itemx gnu++1z
+GNU dialect of @option{-std=c++17}.
+This is the default for C++ code.
+The name @samp{gnu++1z} is deprecated.
+
+@item c++20
+@itemx c++2a
+The 2020 ISO C++ standard plus amendments.
+Support is experimental, and could change in incompatible ways in
+future releases.
+The name @samp{c++2a} is deprecated.
+
+@item gnu++20
+@itemx gnu++2a
+GNU dialect of @option{-std=c++20}.
+Support is experimental, and could change in incompatible ways in
+future releases.
+The name @samp{gnu++2a} is deprecated.
+
+@item c++2b
+@itemx c++23
+The next revision of the ISO C++ standard, planned for
+2023.  Support is highly experimental, and will almost certainly
+change in incompatible ways in future releases.
+
+@item gnu++2b
+@itemx gnu++23
+GNU dialect of @option{-std=c++2b}.  Support is highly experimental,
+and will almost certainly change in incompatible ways in future
+releases.
+@end table
+
+@item -aux-info @var{filename}
+@opindex aux-info
+Output to the given filename prototyped declarations for all functions
+declared and/or defined in a translation unit, including those in header
+files.  This option is silently ignored in any language other than C@.
+
+Besides declarations, the file indicates, in comments, the origin of
+each declaration (source file and line), whether the declaration was
+implicit, prototyped or unprototyped (@samp{I}, @samp{N} for new or
+@samp{O} for old, respectively, in the first character after the line
+number and the colon), and whether it came from a declaration or a
+definition (@samp{C} or @samp{F}, respectively, in the following
+character).  In the case of function definitions, a K&R-style list of
+arguments followed by their declarations is also provided, inside
+comments, after the declaration.
+
+@item -fno-asm
+@opindex fno-asm
+@opindex fasm
+Do not recognize @code{asm}, @code{inline} or @code{typeof} as a
+keyword, so that code can use these words as identifiers.  You can use
+the keywords @code{__asm__}, @code{__inline__} and @code{__typeof__}
+instead.  In C, @option{-ansi} implies @option{-fno-asm}.
+
+In C++, @code{inline} is a standard keyword and is not affected by
+this switch.  You may want to use the @option{-fno-gnu-keywords} flag
+instead, which disables @code{typeof} but not @code{asm} and
+@code{inline}.  In C99 mode (@option{-std=c99} or @option{-std=gnu99}),
+this switch only affects the @code{asm} and @code{typeof} keywords,
+since @code{inline} is a standard keyword in ISO C99.  In C2X mode
+(@option{-std=c2x} or @option{-std=gnu2x}), this switch only affects
+the @code{asm} keyword, since @code{typeof} is a standard keyword in
+ISO C2X.
+
+@item -fno-builtin
+@itemx -fno-builtin-@var{function}
+@opindex fno-builtin
+@opindex fbuiltin
+@cindex built-in functions
+Don't recognize built-in functions that do not begin with
+@samp{__builtin_} as prefix.  @xref{Other Builtins,,Other built-in
+functions provided by GCC}, for details of the functions affected,
+including those which are not built-in functions when @option{-ansi} or
+@option{-std} options for strict ISO C conformance are used because they
+do not have an ISO standard meaning.
+
+GCC normally generates special code to handle certain built-in functions
+more efficiently; for instance, calls to @code{alloca} may become single
+instructions which adjust the stack directly, and calls to @code{memcpy}
+may become inline copy loops.  The resulting code is often both smaller
+and faster, but since the function calls no longer appear as such, you
+cannot set a breakpoint on those calls, nor can you change the behavior
+of the functions by linking with a different library.  In addition,
+when a function is recognized as a built-in function, GCC may use
+information about that function to warn about problems with calls to
+that function, or to generate more efficient code, even if the
+resulting code still contains calls to that function.  For example,
+warnings are given with @option{-Wformat} for bad calls to
+@code{printf} when @code{printf} is built in and @code{strlen} is
+known not to modify global memory.
+
+With the @option{-fno-builtin-@var{function}} option
+only the built-in function @var{function} is
+disabled.  @var{function} must not begin with @samp{__builtin_}.  If a
+function is named that is not built-in in this version of GCC, this
+option is ignored.  There is no corresponding
+@option{-fbuiltin-@var{function}} option; if you wish to enable
+built-in functions selectively when using @option{-fno-builtin} or
+@option{-ffreestanding}, you may define macros such as:
+
+@smallexample
+#define abs(n)          __builtin_abs ((n))
+#define strcpy(d, s)    __builtin_strcpy ((d), (s))
+@end smallexample
+
+@item -fcond-mismatch
+@opindex fcond-mismatch
+Allow conditional expressions with mismatched types in the second and
+third arguments.  The value of such an expression is void.  This option
+is not supported for C++.
+
+@item -ffreestanding
+@opindex ffreestanding
+@cindex hosted environment
+
+Assert that compilation targets a freestanding environment.  This
+implies @option{-fno-builtin}.  A freestanding environment
+is one in which the standard library may not exist, and program startup may
+not necessarily be at @code{main}.  The most obvious example is an OS kernel.
+This is equivalent to @option{-fno-hosted}.
+
+@xref{Standards,,Language Standards Supported by GCC}, for details of
+freestanding and hosted environments.
+
+@item -fgimple
+@opindex fgimple
+
+Enable parsing of function definitions marked with @code{__GIMPLE}.
+This is an experimental feature that allows unit testing of GIMPLE
+passes.
+
+@item -fgnu-tm
+@opindex fgnu-tm
+When the option @option{-fgnu-tm} is specified, the compiler
+generates code for the Linux variant of Intel's current Transactional
+Memory ABI specification document (Revision 1.1, May 6 2009).  This is
+an experimental feature whose interface may change in future versions
+of GCC, as the official specification changes.  Please note that not
+all architectures are supported for this feature.
+
+For more information on GCC's support for transactional memory,
+@xref{Enabling libitm,,The GNU Transactional Memory Library,libitm,GNU
+Transactional Memory Library}.
+
+Note that the transactional memory feature is not supported with
+non-call exceptions (@option{-fnon-call-exceptions}).
+
+@item -fgnu89-inline
+@opindex fgnu89-inline
+The option @option{-fgnu89-inline} tells GCC to use the traditional
+GNU semantics for @code{inline} functions when in C99 mode.
+@xref{Inline,,An Inline Function is As Fast As a Macro}.
+Using this option is roughly equivalent to adding the
+@code{gnu_inline} function attribute to all inline functions
+(@pxref{Function Attributes}).
+
+The option @option{-fno-gnu89-inline} explicitly tells GCC to use the
+C99 semantics for @code{inline} when in C99 or gnu99 mode (i.e., it
+specifies the default behavior).
+This option is not supported in @option{-std=c90} or
+@option{-std=gnu90} mode.
+
+The preprocessor macros @code{__GNUC_GNU_INLINE__} and
+@code{__GNUC_STDC_INLINE__} may be used to check which semantics are
+in effect for @code{inline} functions.  @xref{Common Predefined
+Macros,,,cpp,The C Preprocessor}.
+
+@item -fhosted
+@opindex fhosted
+@cindex hosted environment
+
+Assert that compilation targets a hosted environment.  This implies
+@option{-fbuiltin}.  A hosted environment is one in which the
+entire standard library is available, and in which @code{main} has a return
+type of @code{int}.  Examples are nearly everything except a kernel.
+This is equivalent to @option{-fno-freestanding}.
+
+@item -flax-vector-conversions
+@opindex flax-vector-conversions
+Allow implicit conversions between vectors with differing numbers of
+elements and/or incompatible element types.  This option should not be
+used for new code.
+
+@item -fms-extensions
+@opindex fms-extensions
+Accept some non-standard constructs used in Microsoft header files.
+
+In C++ code, this allows member names in structures to be similar
+to previous types declarations.
+
+@smallexample
+typedef int UOW;
+struct ABC @{
+  UOW UOW;
+@};
+@end smallexample
+
+Some cases of unnamed fields in structures and unions are only
+accepted with this option.  @xref{Unnamed Fields,,Unnamed struct/union
+fields within structs/unions}, for details.
+
+Note that this option is off for all targets except for x86
+targets using ms-abi.
+
+@item -foffload=disable
+@itemx -foffload=default
+@itemx -foffload=@var{target-list}
+@opindex foffload
+@cindex Offloading targets
+@cindex OpenACC offloading targets
+@cindex OpenMP offloading targets
+Specify for which OpenMP and OpenACC offload targets code should be generated.
+The default behavior, equivalent to @option{-foffload=default}, is to generate
+code for all supported offload targets.  The @option{-foffload=disable} form
+generates code only for the host fallback, while
+@option{-foffload=@var{target-list}} generates code only for the specified
+comma-separated list of offload targets.
+
+Offload targets are specified in GCC's internal target-triplet format. You can
+run the compiler with @option{-v} to show the list of configured offload targets
+under @code{OFFLOAD_TARGET_NAMES}.
+
+@item -foffload-options=@var{options}
+@itemx -foffload-options=@var{target-triplet-list}=@var{options}
+@opindex foffload-options
+@cindex Offloading options
+@cindex OpenACC offloading options
+@cindex OpenMP offloading options
+
+With @option{-foffload-options=@var{options}}, GCC passes the specified
+@var{options} to the compilers for all enabled offloading targets.  You can
+specify options that apply only to a specific target or targets by using
+the @option{-foffload-options=@var{target-list}=@var{options}} form.  The
+@var{target-list} is a comma-separated list in the same format as for the
+@option{-foffload=} option.
+
+Typical command lines are
+
+@smallexample
+-foffload-options=-lgfortran -foffload-options=-lm
+-foffload-options="-lgfortran -lm" -foffload-options=nvptx-none=-latomic
+-foffload-options=amdgcn-amdhsa=-march=gfx906 -foffload-options=-lm
+@end smallexample
+
+@item -fopenacc
+@opindex fopenacc
+@cindex OpenACC accelerator programming
+Enable handling of OpenACC directives @code{#pragma acc} in C/C++ and
+@code{!$acc} in Fortran.  When @option{-fopenacc} is specified, the
+compiler generates accelerated code according to the OpenACC Application
+Programming Interface v2.6 @w{@uref{https://www.openacc.org}}.  This option
+implies @option{-pthread}, and thus is only supported on targets that
+have support for @option{-pthread}.
+
+@item -fopenacc-dim=@var{geom}
+@opindex fopenacc-dim
+@cindex OpenACC accelerator programming
+Specify default compute dimensions for parallel offload regions that do
+not explicitly specify.  The @var{geom} value is a triple of
+':'-separated sizes, in order 'gang', 'worker' and, 'vector'.  A size
+can be omitted, to use a target-specific default value.
+
+@item -fopenmp
+@opindex fopenmp
+@cindex OpenMP parallel
+Enable handling of OpenMP directives @code{#pragma omp} in C/C++,
+@code{[[omp::directive(...)]]} and @code{[[omp::sequence(...)]]} in C++ and
+@code{!$omp} in Fortran.  When @option{-fopenmp} is specified, the
+compiler generates parallel code according to the OpenMP Application
+Program Interface v4.5 @w{@uref{https://www.openmp.org}}.  This option
+implies @option{-pthread}, and thus is only supported on targets that
+have support for @option{-pthread}. @option{-fopenmp} implies
+@option{-fopenmp-simd}.
+
+@item -fopenmp-simd
+@opindex fopenmp-simd
+@cindex OpenMP SIMD
+@cindex SIMD
+Enable handling of OpenMP's @code{simd}, @code{declare simd},
+@code{declare reduction}, @code{assume}, @code{ordered}, @code{scan},
+@code{loop} directives and combined or composite directives with
+@code{simd} as constituent with @code{#pragma omp} in C/C++,
+@code{[[omp::directive(...)]]} and @code{[[omp::sequence(...)]]} in C++
+and @code{!$omp} in Fortran.  Other OpenMP directives are ignored.
+
+@item -fpermitted-flt-eval-methods=@var{style}
+@opindex fpermitted-flt-eval-methods
+@opindex fpermitted-flt-eval-methods=c11
+@opindex fpermitted-flt-eval-methods=ts-18661-3
+ISO/IEC TS 18661-3 defines new permissible values for
+@code{FLT_EVAL_METHOD} that indicate that operations and constants with
+a semantic type that is an interchange or extended format should be
+evaluated to the precision and range of that type.  These new values are
+a superset of those permitted under C99/C11, which does not specify the
+meaning of other positive values of @code{FLT_EVAL_METHOD}.  As such, code
+conforming to C11 may not have been written expecting the possibility of
+the new values.
+
+@option{-fpermitted-flt-eval-methods} specifies whether the compiler
+should allow only the values of @code{FLT_EVAL_METHOD} specified in C99/C11,
+or the extended set of values specified in ISO/IEC TS 18661-3.
+
+@var{style} is either @code{c11} or @code{ts-18661-3} as appropriate.
+
+The default when in a standards compliant mode (@option{-std=c11} or similar)
+is @option{-fpermitted-flt-eval-methods=c11}.  The default when in a GNU
+dialect (@option{-std=gnu11} or similar) is
+@option{-fpermitted-flt-eval-methods=ts-18661-3}.
+
+@item -fplan9-extensions
+@opindex fplan9-extensions
+Accept some non-standard constructs used in Plan 9 code.
+
+This enables @option{-fms-extensions}, permits passing pointers to
+structures with anonymous fields to functions that expect pointers to
+elements of the type of the field, and permits referring to anonymous
+fields declared using a typedef.  @xref{Unnamed Fields,,Unnamed
+struct/union fields within structs/unions}, for details.  This is only
+supported for C, not C++.
+
+@item -fsigned-bitfields
+@itemx -funsigned-bitfields
+@itemx -fno-signed-bitfields
+@itemx -fno-unsigned-bitfields
+@opindex fsigned-bitfields
+@opindex funsigned-bitfields
+@opindex fno-signed-bitfields
+@opindex fno-unsigned-bitfields
+These options control whether a bit-field is signed or unsigned, when the
+declaration does not use either @code{signed} or @code{unsigned}.  By
+default, such a bit-field is signed, because this is consistent: the
+basic integer types such as @code{int} are signed types.
+
+@item -fsigned-char
+@opindex fsigned-char
+Let the type @code{char} be signed, like @code{signed char}.
+
+Note that this is equivalent to @option{-fno-unsigned-char}, which is
+the negative form of @option{-funsigned-char}.  Likewise, the option
+@option{-fno-signed-char} is equivalent to @option{-funsigned-char}.
+
+@item -funsigned-char
+@opindex funsigned-char
+Let the type @code{char} be unsigned, like @code{unsigned char}.
+
+Each kind of machine has a default for what @code{char} should
+be.  It is either like @code{unsigned char} by default or like
+@code{signed char} by default.
+
+Ideally, a portable program should always use @code{signed char} or
+@code{unsigned char} when it depends on the signedness of an object.
+But many programs have been written to use plain @code{char} and
+expect it to be signed, or expect it to be unsigned, depending on the
+machines they were written for.  This option, and its inverse, let you
+make such a program work with the opposite default.
+
+The type @code{char} is always a distinct type from each of
+@code{signed char} or @code{unsigned char}, even though its behavior
+is always just like one of those two.
+
+@item -fstrict-flex-arrays
+@opindex fstrict-flex-arrays
+@opindex fno-strict-flex-arrays
+Control when to treat the trailing array of a structure as a flexible array
+member for the purpose of accessing the elements of such an array.
+The positive form is equivalent to @option{-fstrict-flex-arrays=3}, which is the
+strictest.  A trailing array is treated as a flexible array member only when it
+is declared as a flexible array member per C99 standard onwards.
+The negative form is equivalent to @option{-fstrict-flex-arrays=0}, which is the
+least strict.  All trailing arrays of structures are treated as flexible array
+members.
+
+@item -fstrict-flex-arrays=@var{level}
+@opindex fstrict-flex-arrays=@var{level}
+Control when to treat the trailing array of a structure as a flexible array
+member for the purpose of accessing the elements of such an array.  The value
+of @var{level} controls the level of strictness.
+
+The possible values of @var{level} are the same as for the
+@code{strict_flex_array} attribute (@pxref{Variable Attributes}).
+
+You can control this behavior for a specific trailing array field of a
+structure by using the variable attribute @code{strict_flex_array} attribute
+(@pxref{Variable Attributes}).
+
+@item -fsso-struct=@var{endianness}
+@opindex fsso-struct
+Set the default scalar storage order of structures and unions to the
+specified endianness.  The accepted values are @samp{big-endian},
+@samp{little-endian} and @samp{native} for the native endianness of
+the target (the default).  This option is not supported for C++.
+
+@strong{Warning:} the @option{-fsso-struct} switch causes GCC to generate
+code that is not binary compatible with code generated without it if the
+specified endianness is not the native endianness of the target.
+@end table
+
+@node C++ Dialect Options
+@section Options Controlling C++ Dialect
+
+@cindex compiler options, C++
+@cindex C++ options, command-line
+@cindex options, C++
+This section describes the command-line options that are only meaningful
+for C++ programs.  You can also use most of the GNU compiler options
+regardless of what language your program is in.  For example, you
+might compile a file @file{firstClass.C} like this:
+
+@smallexample
+g++ -g -fstrict-enums -O -c firstClass.C
+@end smallexample
+
+@noindent
+In this example, only @option{-fstrict-enums} is an option meant
+only for C++ programs; you can use the other options with any
+language supported by GCC@.
+
+Some options for compiling C programs, such as @option{-std}, are also
+relevant for C++ programs.
+@xref{C Dialect Options,,Options Controlling C Dialect}.
+
+Here is a list of options that are @emph{only} for compiling C++ programs:
+
+@table @gcctabopt
+
+@item -fabi-version=@var{n}
+@opindex fabi-version
+Use version @var{n} of the C++ ABI@.  The default is version 0.
+
+Version 0 refers to the version conforming most closely to
+the C++ ABI specification.  Therefore, the ABI obtained using version 0
+will change in different versions of G++ as ABI bugs are fixed.
+
+Version 1 is the version of the C++ ABI that first appeared in G++ 3.2.
+
+Version 2 is the version of the C++ ABI that first appeared in G++
+3.4, and was the default through G++ 4.9.
+
+Version 3 corrects an error in mangling a constant address as a
+template argument.
+
+Version 4, which first appeared in G++ 4.5, implements a standard
+mangling for vector types.
+
+Version 5, which first appeared in G++ 4.6, corrects the mangling of
+attribute const/volatile on function pointer types, decltype of a
+plain decl, and use of a function parameter in the declaration of
+another parameter.
+
+Version 6, which first appeared in G++ 4.7, corrects the promotion
+behavior of C++11 scoped enums and the mangling of template argument
+packs, const/static_cast, prefix ++ and --, and a class scope function
+used as a template argument.
+
+Version 7, which first appeared in G++ 4.8, that treats nullptr_t as a
+builtin type and corrects the mangling of lambdas in default argument
+scope.
+
+Version 8, which first appeared in G++ 4.9, corrects the substitution
+behavior of function types with function-cv-qualifiers.
+
+Version 9, which first appeared in G++ 5.2, corrects the alignment of
+@code{nullptr_t}.
+
+Version 10, which first appeared in G++ 6.1, adds mangling of
+attributes that affect type identity, such as ia32 calling convention
+attributes (e.g.@: @samp{stdcall}).
+
+Version 11, which first appeared in G++ 7, corrects the mangling of
+sizeof... expressions and operator names.  For multiple entities with
+the same name within a function, that are declared in different scopes,
+the mangling now changes starting with the twelfth occurrence.  It also
+implies @option{-fnew-inheriting-ctors}.
+
+Version 12, which first appeared in G++ 8, corrects the calling
+conventions for empty classes on the x86_64 target and for classes
+with only deleted copy/move constructors.  It accidentally changes the
+calling convention for classes with a deleted copy constructor and a
+trivial move constructor.
+
+Version 13, which first appeared in G++ 8.2, fixes the accidental
+change in version 12.
+
+Version 14, which first appeared in G++ 10, corrects the mangling of
+the nullptr expression.
+
+Version 15, which first appeared in G++ 10.3, corrects G++ 10 ABI
+tag regression.
+
+Version 16, which first appeared in G++ 11, changes the mangling of
+@code{__alignof__} to be distinct from that of @code{alignof}, and
+dependent operator names.
+
+Version 17, which first appeared in G++ 12, fixes layout of classes
+that inherit from aggregate classes with default member initializers
+in C++14 and up.
+
+Version 18, which first appeard in G++ 13, fixes manglings of lambdas
+that have additional context.
+
+See also @option{-Wabi}.
+
+@item -fabi-compat-version=@var{n}
+@opindex fabi-compat-version
+On targets that support strong aliases, G++
+works around mangling changes by creating an alias with the correct
+mangled name when defining a symbol with an incorrect mangled name.
+This switch specifies which ABI version to use for the alias.
+
+With @option{-fabi-version=0} (the default), this defaults to 13 (GCC 8.2
+compatibility).  If another ABI version is explicitly selected, this
+defaults to 0.  For compatibility with GCC versions 3.2 through 4.9,
+use @option{-fabi-compat-version=2}.
+
+If this option is not provided but @option{-Wabi=@var{n}} is, that
+version is used for compatibility aliases.  If this option is provided
+along with @option{-Wabi} (without the version), the version from this
+option is used for the warning.
+
+@item -fno-access-control
+@opindex fno-access-control
+@opindex faccess-control
+Turn off all access checking.  This switch is mainly useful for working
+around bugs in the access control code.
+
+@item -faligned-new
+@opindex faligned-new
+Enable support for C++17 @code{new} of types that require more
+alignment than @code{void* ::operator new(std::size_t)} provides.  A
+numeric argument such as @code{-faligned-new=32} can be used to
+specify how much alignment (in bytes) is provided by that function,
+but few users will need to override the default of
+@code{alignof(std::max_align_t)}.
+
+This flag is enabled by default for @option{-std=c++17}.
+
+@item -fchar8_t
+@itemx -fno-char8_t
+@opindex fchar8_t
+@opindex fno-char8_t
+Enable support for @code{char8_t} as adopted for C++20.  This includes
+the addition of a new @code{char8_t} fundamental type, changes to the
+types of UTF-8 string and character literals, new signatures for
+user-defined literals, associated standard library updates, and new
+@code{__cpp_char8_t} and @code{__cpp_lib_char8_t} feature test macros.
+
+This option enables functions to be overloaded for ordinary and UTF-8
+strings:
+
+@smallexample
+int f(const char *);    // #1
+int f(const char8_t *); // #2
+int v1 = f("text");     // Calls #1
+int v2 = f(u8"text");   // Calls #2
+@end smallexample
+
+@noindent
+and introduces new signatures for user-defined literals:
+
+@smallexample
+int operator""_udl1(char8_t);
+int v3 = u8'x'_udl1;
+int operator""_udl2(const char8_t*, std::size_t);
+int v4 = u8"text"_udl2;
+template<typename T, T...> int operator""_udl3();
+int v5 = u8"text"_udl3;
+@end smallexample
+
+@noindent
+The change to the types of UTF-8 string and character literals introduces
+incompatibilities with ISO C++11 and later standards.  For example, the
+following code is well-formed under ISO C++11, but is ill-formed when
+@option{-fchar8_t} is specified.
+
+@smallexample
+char ca[] = u8"xx";     // error: char-array initialized from wide
+                        //        string
+const char *cp = u8"xx";// error: invalid conversion from
+                        //        `const char8_t*' to `const char*'
+int f(const char*);
+auto v = f(u8"xx");     // error: invalid conversion from
+                        //        `const char8_t*' to `const char*'
+std::string s@{u8"xx"@};  // error: no matching function for call to
+                        //        `std::basic_string<char>::basic_string()'
+using namespace std::literals;
+s = u8"xx"s;            // error: conversion from
+                        //        `basic_string<char8_t>' to non-scalar
+                        //        type `basic_string<char>' requested
+@end smallexample
+
+@item -fcheck-new
+@opindex fcheck-new
+Check that the pointer returned by @code{operator new} is non-null
+before attempting to modify the storage allocated.  This check is
+normally unnecessary because the C++ standard specifies that
+@code{operator new} only returns @code{0} if it is declared
+@code{throw()}, in which case the compiler always checks the
+return value even without this option.  In all other cases, when
+@code{operator new} has a non-empty exception specification, memory
+exhaustion is signalled by throwing @code{std::bad_alloc}.  See also
+@samp{new (nothrow)}.
+
+@item -fconcepts
+@itemx -fconcepts-ts
+@opindex fconcepts
+@opindex fconcepts-ts
+Enable support for the C++ Concepts feature for constraining template
+arguments.  With @option{-std=c++20} and above, Concepts are part of
+the language standard, so @option{-fconcepts} defaults to on.
+
+Some constructs that were allowed by the earlier C++ Extensions for
+Concepts Technical Specification, ISO 19217 (2015), but didn't make it
+into the standard, can additionally be enabled by
+@option{-fconcepts-ts}.
+
+@item -fconstexpr-depth=@var{n}
+@opindex fconstexpr-depth
+Set the maximum nested evaluation depth for C++11 constexpr functions
+to @var{n}.  A limit is needed to detect endless recursion during
+constant expression evaluation.  The minimum specified by the standard
+is 512.
+
+@item -fconstexpr-cache-depth=@var{n}
+@opindex fconstexpr-cache-depth
+Set the maximum level of nested evaluation depth for C++11 constexpr
+functions that will be cached to @var{n}.  This is a heuristic that
+trades off compilation speed (when the cache avoids repeated
+calculations) against memory consumption (when the cache grows very
+large from highly recursive evaluations).  The default is 8.  Very few
+users are likely to want to adjust it, but if your code does heavy
+constexpr calculations you might want to experiment to find which
+value works best for you.
+
+@item -fconstexpr-fp-except
+@opindex fconstexpr-fp-except
+Annex F of the C standard specifies that IEC559 floating point
+exceptions encountered at compile time should not stop compilation.
+C++ compilers have historically not followed this guidance, instead
+treating floating point division by zero as non-constant even though
+it has a well defined value.  This flag tells the compiler to give
+Annex F priority over other rules saying that a particular operation
+is undefined.
+
+@smallexample
+constexpr float inf = 1./0.; // OK with -fconstexpr-fp-except
+@end smallexample
+
+@item -fconstexpr-loop-limit=@var{n}
+@opindex fconstexpr-loop-limit
+Set the maximum number of iterations for a loop in C++14 constexpr functions
+to @var{n}.  A limit is needed to detect infinite loops during
+constant expression evaluation.  The default is 262144 (1<<18).
+
+@item -fconstexpr-ops-limit=@var{n}
+@opindex fconstexpr-ops-limit
+Set the maximum number of operations during a single constexpr evaluation.
+Even when number of iterations of a single loop is limited with the above limit,
+if there are several nested loops and each of them has many iterations but still
+smaller than the above limit, or if in a body of some loop or even outside
+of a loop too many expressions need to be evaluated, the resulting constexpr
+evaluation might take too long.
+The default is 33554432 (1<<25).
+
+@item -fcoroutines
+@opindex fcoroutines
+Enable support for the C++ coroutines extension (experimental).
+
+@item -fno-elide-constructors
+@opindex fno-elide-constructors
+@opindex felide-constructors
+The C++ standard allows an implementation to omit creating a temporary
+that is only used to initialize another object of the same type.
+Specifying this option disables that optimization, and forces G++ to
+call the copy constructor in all cases.  This option also causes G++
+to call trivial member functions which otherwise would be expanded inline.
+
+In C++17, the compiler is required to omit these temporaries, but this
+option still affects trivial member functions.
+
+@item -fno-enforce-eh-specs
+@opindex fno-enforce-eh-specs
+@opindex fenforce-eh-specs
+Don't generate code to check for violation of exception specifications
+at run time.  This option violates the C++ standard, but may be useful
+for reducing code size in production builds, much like defining
+@code{NDEBUG}.  This does not give user code permission to throw
+exceptions in violation of the exception specifications; the compiler
+still optimizes based on the specifications, so throwing an
+unexpected exception results in undefined behavior at run time.
+
+@item -fextern-tls-init
+@itemx -fno-extern-tls-init
+@opindex fextern-tls-init
+@opindex fno-extern-tls-init
+The C++11 and OpenMP standards allow @code{thread_local} and
+@code{threadprivate} variables to have dynamic (runtime)
+initialization.  To support this, any use of such a variable goes
+through a wrapper function that performs any necessary initialization.
+When the use and definition of the variable are in the same
+translation unit, this overhead can be optimized away, but when the
+use is in a different translation unit there is significant overhead
+even if the variable doesn't actually need dynamic initialization.  If
+the programmer can be sure that no use of the variable in a
+non-defining TU needs to trigger dynamic initialization (either
+because the variable is statically initialized, or a use of the
+variable in the defining TU will be executed before any uses in
+another TU), they can avoid this overhead with the
+@option{-fno-extern-tls-init} option.
+
+On targets that support symbol aliases, the default is
+@option{-fextern-tls-init}.  On targets that do not support symbol
+aliases, the default is @option{-fno-extern-tls-init}.
+
+@item -ffold-simple-inlines
+@itemx -fno-fold-simple-inlines
+@opindex ffold-simple-inlines
+@opindex fno-fold-simple-inlines
+Permit the C++ frontend to fold calls to @code{std::move}, @code{std::forward},
+@code{std::addressof} and @code{std::as_const}.  In contrast to inlining, this
+means no debug information will be generated for such calls.  Since these
+functions are rarely interesting to debug, this flag is enabled by default
+unless @option{-fno-inline} is active.
+
+@item -fno-gnu-keywords
+@opindex fno-gnu-keywords
+@opindex fgnu-keywords
+Do not recognize @code{typeof} as a keyword, so that code can use this
+word as an identifier.  You can use the keyword @code{__typeof__} instead.
+This option is implied by the strict ISO C++ dialects: @option{-ansi},
+@option{-std=c++98}, @option{-std=c++11}, etc.
+
+@item -fimplicit-constexpr
+@opindex fimplicit-constexpr
+Make inline functions implicitly constexpr, if they satisfy the
+requirements for a constexpr function.  This option can be used in
+C++14 mode or later.  This can result in initialization changing from
+dynamic to static and other optimizations.
+
+@item -fno-implicit-templates
+@opindex fno-implicit-templates
+@opindex fimplicit-templates
+Never emit code for non-inline templates that are instantiated
+implicitly (i.e.@: by use); only emit code for explicit instantiations.
+If you use this option, you must take care to structure your code to
+include all the necessary explicit instantiations to avoid getting
+undefined symbols at link time.
+@xref{Template Instantiation}, for more information.
+
+@item -fno-implicit-inline-templates
+@opindex fno-implicit-inline-templates
+@opindex fimplicit-inline-templates
+Don't emit code for implicit instantiations of inline templates, either.
+The default is to handle inlines differently so that compiles with and
+without optimization need the same set of explicit instantiations.
+
+@item -fno-implement-inlines
+@opindex fno-implement-inlines
+@opindex fimplement-inlines
+To save space, do not emit out-of-line copies of inline functions
+controlled by @code{#pragma implementation}.  This causes linker
+errors if these functions are not inlined everywhere they are called.
+
+@item -fmodules-ts
+@itemx -fno-modules-ts
+@opindex fmodules-ts
+@opindex fno-modules-ts
+Enable support for C++20 modules (@pxref{C++ Modules}).  The
+@option{-fno-modules-ts} is usually not needed, as that is the
+default.  Even though this is a C++20 feature, it is not currently
+implicitly enabled by selecting that standard version.
+
+@item -fmodule-header
+@itemx -fmodule-header=user
+@itemx -fmodule-header=system
+@opindex fmodule-header
+Compile a header file to create an importable header unit.
+
+@item -fmodule-implicit-inline
+@opindex fmodule-implicit-inline
+Member functions defined in their class definitions are not implicitly
+inline for modular code.  This is different to traditional C++
+behavior, for good reasons.  However, it may result in a difficulty
+during code porting.  This option makes such function definitions
+implicitly inline.  It does however generate an ABI incompatibility,
+so you must use it everywhere or nowhere.  (Such definitions outside
+of a named module remain implicitly inline, regardless.)
+
+@item -fno-module-lazy
+@opindex fno-module-lazy
+@opindex fmodule-lazy
+Disable lazy module importing and module mapper creation.
+
+@item -fmodule-mapper=@r{[}@var{hostname}@r{]}:@var{port}@r{[}?@var{ident}@r{]}
+@itemx -fmodule-mapper=|@var{program}@r{[}?@var{ident}@r{]} @var{args...}
+@itemx -fmodule-mapper==@var{socket}@r{[}?@var{ident}@r{]}
+@itemx -fmodule-mapper=<>@r{[}@var{inout}@r{]}@r{[}?@var{ident}@r{]}
+@itemx -fmodule-mapper=<@var{in}>@var{out}@r{[}?@var{ident}@r{]}
+@itemx -fmodule-mapper=@var{file}@r{[}?@var{ident}@r{]}
+@vindex CXX_MODULE_MAPPER @r{environment variable}
+@opindex fmodule-mapper
+An oracle to query for module name to filename mappings.  If
+unspecified the @env{CXX_MODULE_MAPPER} environment variable is used,
+and if that is unset, an in-process default is provided.
+
+@item -fmodule-only
+@opindex fmodule-only
+Only emit the Compiled Module Interface, inhibiting any object file.
+
+@item -fms-extensions
+@opindex fms-extensions
+Disable Wpedantic warnings about constructs used in MFC, such as implicit
+int and getting a pointer to member function via non-standard syntax.
+
+@item -fnew-inheriting-ctors
+@opindex fnew-inheriting-ctors
+Enable the P0136 adjustment to the semantics of C++11 constructor
+inheritance.  This is part of C++17 but also considered to be a Defect
+Report against C++11 and C++14.  This flag is enabled by default
+unless @option{-fabi-version=10} or lower is specified.
+
+@item -fnew-ttp-matching
+@opindex fnew-ttp-matching
+Enable the P0522 resolution to Core issue 150, template template
+parameters and default arguments: this allows a template with default
+template arguments as an argument for a template template parameter
+with fewer template parameters.  This flag is enabled by default for
+@option{-std=c++17}.
+
+@item -fno-nonansi-builtins
+@opindex fno-nonansi-builtins
+@opindex fnonansi-builtins
+Disable built-in declarations of functions that are not mandated by
+ANSI/ISO C@.  These include @code{ffs}, @code{alloca}, @code{_exit},
+@code{index}, @code{bzero}, @code{conjf}, and other related functions.
+
+@item -fnothrow-opt
+@opindex fnothrow-opt
+Treat a @code{throw()} exception specification as if it were a
+@code{noexcept} specification to reduce or eliminate the text size
+overhead relative to a function with no exception specification.  If
+the function has local variables of types with non-trivial
+destructors, the exception specification actually makes the
+function smaller because the EH cleanups for those variables can be
+optimized away.  The semantic effect is that an exception thrown out of
+a function with such an exception specification results in a call
+to @code{terminate} rather than @code{unexpected}.
+
+@item -fno-operator-names
+@opindex fno-operator-names
+@opindex foperator-names
+Do not treat the operator name keywords @code{and}, @code{bitand},
+@code{bitor}, @code{compl}, @code{not}, @code{or} and @code{xor} as
+synonyms as keywords.
+
+@item -fno-optional-diags
+@opindex fno-optional-diags
+@opindex foptional-diags
+Disable diagnostics that the standard says a compiler does not need to
+issue.  Currently, the only such diagnostic issued by G++ is the one for
+a name having multiple meanings within a class.
+
+@item -fpermissive
+@opindex fpermissive
+Downgrade some diagnostics about nonconformant code from errors to
+warnings.  Thus, using @option{-fpermissive} allows some
+nonconforming code to compile.
+
+@item -fno-pretty-templates
+@opindex fno-pretty-templates
+@opindex fpretty-templates
+When an error message refers to a specialization of a function
+template, the compiler normally prints the signature of the
+template followed by the template arguments and any typedefs or
+typenames in the signature (e.g.@: @code{void f(T) [with T = int]}
+rather than @code{void f(int)}) so that it's clear which template is
+involved.  When an error message refers to a specialization of a class
+template, the compiler omits any template arguments that match
+the default template arguments for that template.  If either of these
+behaviors make it harder to understand the error message rather than
+easier, you can use @option{-fno-pretty-templates} to disable them.
+
+@item -fno-rtti
+@opindex fno-rtti
+@opindex frtti
+Disable generation of information about every class with virtual
+functions for use by the C++ run-time type identification features
+(@code{dynamic_cast} and @code{typeid}).  If you don't use those parts
+of the language, you can save some space by using this flag.  Note that
+exception handling uses the same information, but G++ generates it as
+needed. The @code{dynamic_cast} operator can still be used for casts that
+do not require run-time type information, i.e.@: casts to @code{void *} or to
+unambiguous base classes.
+
+Mixing code compiled with @option{-frtti} with that compiled with
+@option{-fno-rtti} may not work.  For example, programs may
+fail to link if a class compiled with @option{-fno-rtti} is used as a base 
+for a class compiled with @option{-frtti}.  
+
+@item -fsized-deallocation
+@opindex fsized-deallocation
+Enable the built-in global declarations
+@smallexample
+void operator delete (void *, std::size_t) noexcept;
+void operator delete[] (void *, std::size_t) noexcept;
+@end smallexample
+as introduced in C++14.  This is useful for user-defined replacement
+deallocation functions that, for example, use the size of the object
+to make deallocation faster.  Enabled by default under
+@option{-std=c++14} and above.  The flag @option{-Wsized-deallocation}
+warns about places that might want to add a definition.
+
+@item -fstrict-enums
+@opindex fstrict-enums
+Allow the compiler to optimize using the assumption that a value of
+enumerated type can only be one of the values of the enumeration (as
+defined in the C++ standard; basically, a value that can be
+represented in the minimum number of bits needed to represent all the
+enumerators).  This assumption may not be valid if the program uses a
+cast to convert an arbitrary integer value to the enumerated type.
+
+@item -fstrong-eval-order
+@opindex fstrong-eval-order
+Evaluate member access, array subscripting, and shift expressions in
+left-to-right order, and evaluate assignment in right-to-left order,
+as adopted for C++17.  Enabled by default with @option{-std=c++17}.
+@option{-fstrong-eval-order=some} enables just the ordering of member
+access and shift expressions, and is the default without
+@option{-std=c++17}.
+
+@item -ftemplate-backtrace-limit=@var{n}
+@opindex ftemplate-backtrace-limit
+Set the maximum number of template instantiation notes for a single
+warning or error to @var{n}.  The default value is 10.
+
+@item -ftemplate-depth=@var{n}
+@opindex ftemplate-depth
+Set the maximum instantiation depth for template classes to @var{n}.
+A limit on the template instantiation depth is needed to detect
+endless recursions during template class instantiation.  ANSI/ISO C++
+conforming programs must not rely on a maximum depth greater than 17
+(changed to 1024 in C++11).  The default value is 900, as the compiler
+can run out of stack space before hitting 1024 in some situations.
+
+@item -fno-threadsafe-statics
+@opindex fno-threadsafe-statics
+@opindex fthreadsafe-statics
+Do not emit the extra code to use the routines specified in the C++
+ABI for thread-safe initialization of local statics.  You can use this
+option to reduce code size slightly in code that doesn't need to be
+thread-safe.
+
+@item -fuse-cxa-atexit
+@opindex fuse-cxa-atexit
+Register destructors for objects with static storage duration with the
+@code{__cxa_atexit} function rather than the @code{atexit} function.
+This option is required for fully standards-compliant handling of static
+destructors, but only works if your C library supports
+@code{__cxa_atexit}.
+
+@item -fno-use-cxa-get-exception-ptr
+@opindex fno-use-cxa-get-exception-ptr
+@opindex fuse-cxa-get-exception-ptr
+Don't use the @code{__cxa_get_exception_ptr} runtime routine.  This
+causes @code{std::uncaught_exception} to be incorrect, but is necessary
+if the runtime routine is not available.
+
+@item -fvisibility-inlines-hidden
+@opindex fvisibility-inlines-hidden
+This switch declares that the user does not attempt to compare
+pointers to inline functions or methods where the addresses of the two functions
+are taken in different shared objects.
+
+The effect of this is that GCC may, effectively, mark inline methods with
+@code{__attribute__ ((visibility ("hidden")))} so that they do not
+appear in the export table of a DSO and do not require a PLT indirection
+when used within the DSO@.  Enabling this option can have a dramatic effect
+on load and link times of a DSO as it massively reduces the size of the
+dynamic export table when the library makes heavy use of templates.
+
+The behavior of this switch is not quite the same as marking the
+methods as hidden directly, because it does not affect static variables
+local to the function or cause the compiler to deduce that
+the function is defined in only one shared object.
+
+You may mark a method as having a visibility explicitly to negate the
+effect of the switch for that method.  For example, if you do want to
+compare pointers to a particular inline method, you might mark it as
+having default visibility.  Marking the enclosing class with explicit
+visibility has no effect.
+
+Explicitly instantiated inline methods are unaffected by this option
+as their linkage might otherwise cross a shared library boundary.
+@xref{Template Instantiation}.
+
+@item -fvisibility-ms-compat
+@opindex fvisibility-ms-compat
+This flag attempts to use visibility settings to make GCC's C++
+linkage model compatible with that of Microsoft Visual Studio.
+
+The flag makes these changes to GCC's linkage model:
+
+@enumerate
+@item
+It sets the default visibility to @code{hidden}, like
+@option{-fvisibility=hidden}.
+
+@item
+Types, but not their members, are not hidden by default.
+
+@item
+The One Definition Rule is relaxed for types without explicit
+visibility specifications that are defined in more than one
+shared object: those declarations are permitted if they are
+permitted when this option is not used.
+@end enumerate
+
+In new code it is better to use @option{-fvisibility=hidden} and
+export those classes that are intended to be externally visible.
+Unfortunately it is possible for code to rely, perhaps accidentally,
+on the Visual Studio behavior.
+
+Among the consequences of these changes are that static data members
+of the same type with the same name but defined in different shared
+objects are different, so changing one does not change the other;
+and that pointers to function members defined in different shared
+objects may not compare equal.  When this flag is given, it is a
+violation of the ODR to define types with the same name differently.
+
+@item -fno-weak
+@opindex fno-weak
+@opindex fweak
+Do not use weak symbol support, even if it is provided by the linker.
+By default, G++ uses weak symbols if they are available.  This
+option exists only for testing, and should not be used by end-users;
+it results in inferior code and has no benefits.  This option may
+be removed in a future release of G++.
+
+@item -fext-numeric-literals @r{(C++ and Objective-C++ only)}
+@opindex fext-numeric-literals
+@opindex fno-ext-numeric-literals
+Accept imaginary, fixed-point, or machine-defined
+literal number suffixes as GNU extensions.
+When this option is turned off these suffixes are treated
+as C++11 user-defined literal numeric suffixes.
+This is on by default for all pre-C++11 dialects and all GNU dialects:
+@option{-std=c++98}, @option{-std=gnu++98}, @option{-std=gnu++11},
+@option{-std=gnu++14}.
+This option is off by default
+for ISO C++11 onwards (@option{-std=c++11}, ...).
+
+@item -nostdinc++
+@opindex nostdinc++
+Do not search for header files in the standard directories specific to
+C++, but do still search the other standard directories.  (This option
+is used when building the C++ library.)
+
+@item -flang-info-include-translate
+@itemx -flang-info-include-translate-not
+@itemx -flang-info-include-translate=@var{header}
+@opindex flang-info-include-translate
+@opindex flang-info-include-translate-not
+Inform of include translation events.  The first will note accepted
+include translations, the second will note declined include
+translations.  The @var{header} form will inform of include
+translations relating to that specific header.  If @var{header} is of
+the form @code{"user"} or @code{<system>} it will be resolved to a
+specific user or system header using the include path.
+
+@item -flang-info-module-cmi
+@itemx -flang-info-module-cmi=@var{module}
+@opindex flang-info-module-cmi
+Inform of Compiled Module Interface pathnames.  The first will note
+all read CMI pathnames.  The @var{module} form will not reading a
+specific module's CMI.  @var{module} may be a named module or a
+header-unit (the latter indicated by either being a pathname containing
+directory separators or enclosed in @code{<>} or @code{""}).
+
+@item -stdlib=@var{libstdc++,libc++}
+@opindex stdlib
+When G++ is configured to support this option, it allows specification of
+alternate C++ runtime libraries.  Two options are available: @var{libstdc++}
+(the default, native C++ runtime for G++) and @var{libc++} which is the
+C++ runtime installed on some operating systems (e.g. Darwin versions from
+Darwin11 onwards).  The option switches G++ to use the headers from the
+specified library and to emit @code{-lstdc++} or @code{-lc++} respectively,
+when a C++ runtime is required for linking.
+@end table
+
+In addition, these warning options have meanings only for C++ programs:
+
+@table @gcctabopt
+@item -Wabi-tag @r{(C++ and Objective-C++ only)}
+@opindex Wabi-tag
+Warn when a type with an ABI tag is used in a context that does not
+have that ABI tag.  See @ref{C++ Attributes} for more information
+about ABI tags.
+
+@item -Wcomma-subscript @r{(C++ and Objective-C++ only)}
+@opindex Wcomma-subscript
+@opindex Wno-comma-subscript
+Warn about uses of a comma expression within a subscripting expression.
+This usage was deprecated in C++20 and is going to be removed in C++23.
+However, a comma expression wrapped in @code{( )} is not deprecated.  Example:
+
+@smallexample
+@group
+void f(int *a, int b, int c) @{
+    a[b,c];     // deprecated in C++20, invalid in C++23
+    a[(b,c)];   // OK
+@}
+@end group
+@end smallexample
+
+In C++23 it is valid to have comma separated expressions in a subscript
+when an overloaded subscript operator is found and supports the right
+number and types of arguments.  G++ will accept the formerly valid syntax
+for code that is not valid in C++23 but used to be valid but deprecated
+in C++20 with a pedantic warning that can be disabled with
+@option{-Wno-comma-subscript}.
+
+Enabled by default with @option{-std=c++20} unless @option{-Wno-deprecated},
+and with @option{-std=c++23} regardless of @option{-Wno-deprecated}.
+
+@item -Wctad-maybe-unsupported @r{(C++ and Objective-C++ only)}
+@opindex Wctad-maybe-unsupported
+@opindex Wno-ctad-maybe-unsupported
+Warn when performing class template argument deduction (CTAD) on a type with
+no explicitly written deduction guides.  This warning will point out cases
+where CTAD succeeded only because the compiler synthesized the implicit
+deduction guides, which might not be what the programmer intended.  Certain
+style guides allow CTAD only on types that specifically "opt-in"; i.e., on
+types that are designed to support CTAD.  This warning can be suppressed with
+the following pattern:
+
+@smallexample
+struct allow_ctad_t; // any name works
+template <typename T> struct S @{
+  S(T) @{ @}
+@};
+S(allow_ctad_t) -> S<void>; // guide with incomplete parameter type will never be considered
+@end smallexample
+
+@item -Wctor-dtor-privacy @r{(C++ and Objective-C++ only)}
+@opindex Wctor-dtor-privacy
+@opindex Wno-ctor-dtor-privacy
+Warn when a class seems unusable because all the constructors or
+destructors in that class are private, and it has neither friends nor
+public static member functions.  Also warn if there are no non-private
+methods, and there's at least one private member function that isn't
+a constructor or destructor.
+
+@item -Wdangling-reference @r{(C++ and Objective-C++ only)}
+@opindex Wdangling-reference
+@opindex Wno-dangling-reference
+Warn when a reference is bound to a temporary whose lifetime has ended.
+For example:
+
+@smallexample
+int n = 1;
+const int& r = std::max(n - 1, n + 1); // r is dangling
+@end smallexample
+
+In the example above, two temporaries are created, one for each
+argument, and a reference to one of the temporaries is returned.
+However, both temporaries are destroyed at the end of the full
+expression, so the reference @code{r} is dangling.  This warning
+also detects dangling references in member initializer lists:
+
+@smallexample
+const int& f(const int& i) @{ return i; @}
+struct S @{
+  const int &r; // r is dangling
+  S() : r(f(10)) @{ @}
+@};
+@end smallexample
+
+Member functions are checked as well, but only their object argument:
+
+@smallexample
+struct S @{
+   const S& self () @{ return *this; @}
+@};
+const S& s = S().self(); // s is dangling
+@end smallexample
+
+Certain functions are safe in this respect, for example @code{std::use_facet}:
+they take and return a reference, but they don't return one of its arguments,
+which can fool the warning.  Such functions can be excluded from the warning
+by wrapping them in a @code{#pragma}:
+
+@smallexample
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdangling-reference"
+const T& foo (const T&) @{ @dots{} @}
+#pragma GCC diagnostic pop
+@end smallexample
+
+This warning is enabled by @option{-Wall}.
+
+@item -Wdelete-non-virtual-dtor @r{(C++ and Objective-C++ only)}
+@opindex Wdelete-non-virtual-dtor
+@opindex Wno-delete-non-virtual-dtor
+Warn when @code{delete} is used to destroy an instance of a class that
+has virtual functions and non-virtual destructor. It is unsafe to delete
+an instance of a derived class through a pointer to a base class if the
+base class does not have a virtual destructor.  This warning is enabled
+by @option{-Wall}.
+
+@item -Wdeprecated-copy @r{(C++ and Objective-C++ only)}
+@opindex Wdeprecated-copy
+@opindex Wno-deprecated-copy
+Warn that the implicit declaration of a copy constructor or copy
+assignment operator is deprecated if the class has a user-provided
+copy constructor or copy assignment operator, in C++11 and up.  This
+warning is enabled by @option{-Wextra}.  With
+@option{-Wdeprecated-copy-dtor}, also deprecate if the class has a
+user-provided destructor.
+
+@item -Wno-deprecated-enum-enum-conversion @r{(C++ and Objective-C++ only)}
+@opindex Wdeprecated-enum-enum-conversion
+@opindex Wno-deprecated-enum-enum-conversion
+Disable the warning about the case when the usual arithmetic conversions
+are applied on operands where one is of enumeration type and the other is
+of a different enumeration type.  This conversion was deprecated in C++20.
+For example:
+
+@smallexample
+enum E1 @{ e @};
+enum E2 @{ f @};
+int k = f - e;
+@end smallexample
+
+@option{-Wdeprecated-enum-enum-conversion} is enabled by default with
+@option{-std=c++20}.  In pre-C++20 dialects, this warning can be enabled
+by @option{-Wenum-conversion}.
+
+@item -Wno-deprecated-enum-float-conversion @r{(C++ and Objective-C++ only)}
+@opindex Wdeprecated-enum-float-conversion
+@opindex Wno-deprecated-enum-float-conversion
+Disable the warning about the case when the usual arithmetic conversions
+are applied on operands where one is of enumeration type and the other is
+of a floating-point type.  This conversion was deprecated in C++20.  For
+example:
+
+@smallexample
+enum E1 @{ e @};
+enum E2 @{ f @};
+bool b = e <= 3.7;
+@end smallexample
+
+@option{-Wdeprecated-enum-float-conversion} is enabled by default with
+@option{-std=c++20}.  In pre-C++20 dialects, this warning can be enabled
+by @option{-Wenum-conversion}.
+
+@item -Wno-init-list-lifetime @r{(C++ and Objective-C++ only)}
+@opindex Winit-list-lifetime
+@opindex Wno-init-list-lifetime
+Do not warn about uses of @code{std::initializer_list} that are likely
+to result in dangling pointers.  Since the underlying array for an
+@code{initializer_list} is handled like a normal C++ temporary object,
+it is easy to inadvertently keep a pointer to the array past the end
+of the array's lifetime.  For example:
+
+@itemize @bullet
+@item
+If a function returns a temporary @code{initializer_list}, or a local
+@code{initializer_list} variable, the array's lifetime ends at the end
+of the return statement, so the value returned has a dangling pointer.
+
+@item
+If a new-expression creates an @code{initializer_list}, the array only
+lives until the end of the enclosing full-expression, so the
+@code{initializer_list} in the heap has a dangling pointer.
+
+@item
+When an @code{initializer_list} variable is assigned from a
+brace-enclosed initializer list, the temporary array created for the
+right side of the assignment only lives until the end of the
+full-expression, so at the next statement the @code{initializer_list}
+variable has a dangling pointer.
+
+@smallexample
+// li's initial underlying array lives as long as li
+std::initializer_list<int> li = @{ 1,2,3 @};
+// assignment changes li to point to a temporary array
+li = @{ 4, 5 @};
+// now the temporary is gone and li has a dangling pointer
+int i = li.begin()[0] // undefined behavior
+@end smallexample
+
+@item
+When a list constructor stores the @code{begin} pointer from the
+@code{initializer_list} argument, this doesn't extend the lifetime of
+the array, so if a class variable is constructed from a temporary
+@code{initializer_list}, the pointer is left dangling by the end of
+the variable declaration statement.
+
+@end itemize
+
+@item -Winvalid-imported-macros
+@opindex Winvalid-imported-macros
+@opindex Wno-invalid-imported-macros
+Verify all imported macro definitions are valid at the end of
+compilation.  This is not enabled by default, as it requires
+additional processing to determine.  It may be useful when preparing
+sets of header-units to ensure consistent macros.
+
+@item -Wno-literal-suffix @r{(C++ and Objective-C++ only)}
+@opindex Wliteral-suffix
+@opindex Wno-literal-suffix
+Do not warn when a string or character literal is followed by a
+ud-suffix which does not begin with an underscore.  As a conforming
+extension, GCC treats such suffixes as separate preprocessing tokens
+in order to maintain backwards compatibility with code that uses
+formatting macros from @code{<inttypes.h>}.  For example:
+
+@smallexample
+#define __STDC_FORMAT_MACROS
+#include <inttypes.h>
+#include <stdio.h>
+
+int main() @{
+  int64_t i64 = 123;
+  printf("My int64: %" PRId64"\n", i64);
+@}
+@end smallexample
+
+In this case, @code{PRId64} is treated as a separate preprocessing token.
+
+This option also controls warnings when a user-defined literal
+operator is declared with a literal suffix identifier that doesn't
+begin with an underscore. Literal suffix identifiers that don't begin
+with an underscore are reserved for future standardization.
+
+These warnings are enabled by default.
+
+@item -Wno-narrowing @r{(C++ and Objective-C++ only)}
+@opindex Wnarrowing
+@opindex Wno-narrowing
+For C++11 and later standards, narrowing conversions are diagnosed by default,
+as required by the standard.  A narrowing conversion from a constant produces
+an error, and a narrowing conversion from a non-constant produces a warning,
+but @option{-Wno-narrowing} suppresses the diagnostic.
+Note that this does not affect the meaning of well-formed code;
+narrowing conversions are still considered ill-formed in SFINAE contexts.
+
+With @option{-Wnarrowing} in C++98, warn when a narrowing
+conversion prohibited by C++11 occurs within
+@samp{@{ @}}, e.g.
+
+@smallexample
+int i = @{ 2.2 @}; // error: narrowing from double to int
+@end smallexample
+
+This flag is included in @option{-Wall} and @option{-Wc++11-compat}.
+
+@item -Wnoexcept @r{(C++ and Objective-C++ only)}
+@opindex Wnoexcept
+@opindex Wno-noexcept
+Warn when a noexcept-expression evaluates to false because of a call
+to a function that does not have a non-throwing exception
+specification (i.e. @code{throw()} or @code{noexcept}) but is known by
+the compiler to never throw an exception.
+
+@item -Wnoexcept-type @r{(C++ and Objective-C++ only)}
+@opindex Wnoexcept-type
+@opindex Wno-noexcept-type
+Warn if the C++17 feature making @code{noexcept} part of a function
+type changes the mangled name of a symbol relative to C++14.  Enabled
+by @option{-Wabi} and @option{-Wc++17-compat}.
+
+As an example:
+
+@smallexample
+template <class T> void f(T t) @{ t(); @};
+void g() noexcept;
+void h() @{ f(g); @} 
+@end smallexample
+
+@noindent
+In C++14, @code{f} calls @code{f<void(*)()>}, but in
+C++17 it calls @code{f<void(*)()noexcept>}.
+
+@item -Wclass-memaccess @r{(C++ and Objective-C++ only)}
+@opindex Wclass-memaccess
+@opindex Wno-class-memaccess
+Warn when the destination of a call to a raw memory function such as
+@code{memset} or @code{memcpy} is an object of class type, and when writing
+into such an object might bypass the class non-trivial or deleted constructor
+or copy assignment, violate const-correctness or encapsulation, or corrupt
+virtual table pointers.  Modifying the representation of such objects may
+violate invariants maintained by member functions of the class.  For example,
+the call to @code{memset} below is undefined because it modifies a non-trivial
+class object and is, therefore, diagnosed.  The safe way to either initialize
+or clear the storage of objects of such types is by using the appropriate
+constructor or assignment operator, if one is available.
+@smallexample
+std::string str = "abc";
+memset (&str, 0, sizeof str);
+@end smallexample
+The @option{-Wclass-memaccess} option is enabled by @option{-Wall}.
+Explicitly casting the pointer to the class object to @code{void *} or
+to a type that can be safely accessed by the raw memory function suppresses
+the warning.
+
+@item -Wnon-virtual-dtor @r{(C++ and Objective-C++ only)}
+@opindex Wnon-virtual-dtor
+@opindex Wno-non-virtual-dtor
+Warn when a class has virtual functions and an accessible non-virtual
+destructor itself or in an accessible polymorphic base class, in which
+case it is possible but unsafe to delete an instance of a derived
+class through a pointer to the class itself or base class.  This
+warning is automatically enabled if @option{-Weffc++} is specified.
+
+@item -Wregister @r{(C++ and Objective-C++ only)}
+@opindex Wregister
+@opindex Wno-register
+Warn on uses of the @code{register} storage class specifier, except
+when it is part of the GNU @ref{Explicit Register Variables} extension.
+The use of the @code{register} keyword as storage class specifier has
+been deprecated in C++11 and removed in C++17.
+Enabled by default with @option{-std=c++17}.
+
+@item -Wreorder @r{(C++ and Objective-C++ only)}
+@opindex Wreorder
+@opindex Wno-reorder
+@cindex reordering, warning
+@cindex warning for reordering of member initializers
+Warn when the order of member initializers given in the code does not
+match the order in which they must be executed.  For instance:
+
+@smallexample
+struct A @{
+  int i;
+  int j;
+  A(): j (0), i (1) @{ @}
+@};
+@end smallexample
+
+@noindent
+The compiler rearranges the member initializers for @code{i}
+and @code{j} to match the declaration order of the members, emitting
+a warning to that effect.  This warning is enabled by @option{-Wall}.
+
+@item -Wno-pessimizing-move @r{(C++ and Objective-C++ only)}
+@opindex Wpessimizing-move
+@opindex Wno-pessimizing-move
+This warning warns when a call to @code{std::move} prevents copy
+elision.  A typical scenario when copy elision can occur is when returning in
+a function with a class return type, when the expression being returned is the
+name of a non-volatile automatic object, and is not a function parameter, and
+has the same type as the function return type.
+
+@smallexample
+struct T @{
+@dots{}
+@};
+T fn()
+@{
+  T t;
+  @dots{}
+  return std::move (t);
+@}
+@end smallexample
+
+But in this example, the @code{std::move} call prevents copy elision.
+
+This warning is enabled by @option{-Wall}.
+
+@item -Wno-redundant-move @r{(C++ and Objective-C++ only)}
+@opindex Wredundant-move
+@opindex Wno-redundant-move
+This warning warns about redundant calls to @code{std::move}; that is, when
+a move operation would have been performed even without the @code{std::move}
+call.  This happens because the compiler is forced to treat the object as if
+it were an rvalue in certain situations such as returning a local variable,
+where copy elision isn't applicable.  Consider:
+
+@smallexample
+struct T @{
+@dots{}
+@};
+T fn(T t)
+@{
+  @dots{}
+  return std::move (t);
+@}
+@end smallexample
+
+Here, the @code{std::move} call is redundant.  Because G++ implements Core
+Issue 1579, another example is:
+
+@smallexample
+struct T @{ // convertible to U
+@dots{}
+@};
+struct U @{
+@dots{}
+@};
+U fn()
+@{
+  T t;
+  @dots{}
+  return std::move (t);
+@}
+@end smallexample
+In this example, copy elision isn't applicable because the type of the
+expression being returned and the function return type differ, yet G++
+treats the return value as if it were designated by an rvalue.
+
+This warning is enabled by @option{-Wextra}.
+
+@item -Wrange-loop-construct @r{(C++ and Objective-C++ only)}
+@opindex Wrange-loop-construct
+@opindex Wno-range-loop-construct
+This warning warns when a C++ range-based for-loop is creating an unnecessary
+copy.  This can happen when the range declaration is not a reference, but
+probably should be.  For example:
+
+@smallexample
+struct S @{ char arr[128]; @};
+void fn () @{
+  S arr[5];
+  for (const auto x : arr) @{ @dots{} @}
+@}
+@end smallexample
+
+It does not warn when the type being copied is a trivially-copyable type whose
+size is less than 64 bytes.
+
+This warning also warns when a loop variable in a range-based for-loop is
+initialized with a value of a different type resulting in a copy.  For example:
+
+@smallexample
+void fn() @{
+  int arr[10];
+  for (const double &x : arr) @{ @dots{} @}
+@}
+@end smallexample
+
+In the example above, in every iteration of the loop a temporary value of
+type @code{double} is created and destroyed, to which the reference
+@code{const double &} is bound.
+
+This warning is enabled by @option{-Wall}.
+
+@item -Wredundant-tags @r{(C++ and Objective-C++ only)}
+@opindex Wredundant-tags
+@opindex Wno-redundant-tags
+Warn about redundant class-key and enum-key in references to class types
+and enumerated types in contexts where the key can be eliminated without
+causing an ambiguity.  For example:
+
+@smallexample
+struct foo;
+struct foo *p;   // warn that keyword struct can be eliminated
+@end smallexample
+
+@noindent
+On the other hand, in this example there is no warning:
+
+@smallexample
+struct foo;
+void foo ();   // "hides" struct foo
+void bar (struct foo&);  // no warning, keyword struct is necessary
+@end smallexample
+
+@item -Wno-subobject-linkage @r{(C++ and Objective-C++ only)}
+@opindex Wsubobject-linkage
+@opindex Wno-subobject-linkage
+Do not warn
+if a class type has a base or a field whose type uses the anonymous
+namespace or depends on a type with no linkage.  If a type A depends on
+a type B with no or internal linkage, defining it in multiple
+translation units would be an ODR violation because the meaning of B
+is different in each translation unit.  If A only appears in a single
+translation unit, the best way to silence the warning is to give it
+internal linkage by putting it in an anonymous namespace as well.  The
+compiler doesn't give this warning for types defined in the main .C
+file, as those are unlikely to have multiple definitions.
+@option{-Wsubobject-linkage} is enabled by default.
+
+@item -Weffc++ @r{(C++ and Objective-C++ only)}
+@opindex Weffc++
+@opindex Wno-effc++
+Warn about violations of the following style guidelines from Scott Meyers'
+@cite{Effective C++} series of books:
+
+@itemize @bullet
+@item
+Define a copy constructor and an assignment operator for classes
+with dynamically-allocated memory.
+
+@item
+Prefer initialization to assignment in constructors.
+
+@item
+Have @code{operator=} return a reference to @code{*this}.
+
+@item
+Don't try to return a reference when you must return an object.
+
+@item
+Distinguish between prefix and postfix forms of increment and
+decrement operators.
+
+@item
+Never overload @code{&&}, @code{||}, or @code{,}.
+
+@end itemize
+
+This option also enables @option{-Wnon-virtual-dtor}, which is also
+one of the effective C++ recommendations.  However, the check is
+extended to warn about the lack of virtual destructor in accessible
+non-polymorphic bases classes too.
+
+When selecting this option, be aware that the standard library
+headers do not obey all of these guidelines; use @samp{grep -v}
+to filter out those warnings.
+
+@item -Wno-exceptions @r{(C++ and Objective-C++ only)}
+@opindex Wexceptions
+@opindex Wno-exceptions
+Disable the warning about the case when an exception handler is shadowed by
+another handler, which can point out a wrong ordering of exception handlers.
+
+@item -Wstrict-null-sentinel @r{(C++ and Objective-C++ only)}
+@opindex Wstrict-null-sentinel
+@opindex Wno-strict-null-sentinel
+Warn about the use of an uncasted @code{NULL} as sentinel.  When
+compiling only with GCC this is a valid sentinel, as @code{NULL} is defined
+to @code{__null}.  Although it is a null pointer constant rather than a
+null pointer, it is guaranteed to be of the same size as a pointer.
+But this use is not portable across different compilers.
+
+@item -Wno-non-template-friend @r{(C++ and Objective-C++ only)}
+@opindex Wno-non-template-friend
+@opindex Wnon-template-friend
+Disable warnings when non-template friend functions are declared
+within a template.  In very old versions of GCC that predate implementation
+of the ISO standard, declarations such as 
+@samp{friend int foo(int)}, where the name of the friend is an unqualified-id,
+could be interpreted as a particular specialization of a template
+function; the warning exists to diagnose compatibility problems, 
+and is enabled by default.
+
+@item -Wold-style-cast @r{(C++ and Objective-C++ only)}
+@opindex Wold-style-cast
+@opindex Wno-old-style-cast
+Warn if an old-style (C-style) cast to a non-void type is used within
+a C++ program.  The new-style casts (@code{dynamic_cast},
+@code{static_cast}, @code{reinterpret_cast}, and @code{const_cast}) are
+less vulnerable to unintended effects and much easier to search for.
+
+@item -Woverloaded-virtual @r{(C++ and Objective-C++ only)}
+@itemx -Woverloaded-virtual=@var{n}
+@opindex Woverloaded-virtual
+@opindex Wno-overloaded-virtual
+@cindex overloaded virtual function, warning
+@cindex warning for overloaded virtual function
+Warn when a function declaration hides virtual functions from a
+base class.  For example, in:
+
+@smallexample
+struct A @{
+  virtual void f();
+@};
+
+struct B: public A @{
+  void f(int); // does not override
+@};
+@end smallexample
+
+the @code{A} class version of @code{f} is hidden in @code{B}, and code
+like:
+
+@smallexample
+B* b;
+b->f();
+@end smallexample
+
+@noindent
+fails to compile.
+
+The optional level suffix controls the behavior when all the
+declarations in the derived class override virtual functions in the
+base class, even if not all of the base functions are overridden:
+
+@smallexample
+struct C @{
+  virtual void f();
+  virtual void f(int);
+@};
+
+struct D: public C @{
+  void f(int); // does override
+@}
+@end smallexample
+
+This pattern is less likely to be a mistake; if D is only used
+virtually, the user might have decided that the base class semantics
+for some of the overloads are fine.
+
+At level 1, this case does not warn; at level 2, it does.
+@option{-Woverloaded-virtual} by itself selects level 2.  Level 1 is
+included in @option{-Wall}.
+
+@item -Wno-pmf-conversions @r{(C++ and Objective-C++ only)}
+@opindex Wno-pmf-conversions
+@opindex Wpmf-conversions
+Disable the diagnostic for converting a bound pointer to member function
+to a plain pointer.
+
+@item -Wsign-promo @r{(C++ and Objective-C++ only)}
+@opindex Wsign-promo
+@opindex Wno-sign-promo
+Warn when overload resolution chooses a promotion from unsigned or
+enumerated type to a signed type, over a conversion to an unsigned type of
+the same size.  Previous versions of G++ tried to preserve
+unsignedness, but the standard mandates the current behavior.
+
+@item -Wtemplates @r{(C++ and Objective-C++ only)}
+@opindex Wtemplates
+@opindex Wno-templates
+Warn when a primary template declaration is encountered.  Some coding
+rules disallow templates, and this may be used to enforce that rule.
+The warning is inactive inside a system header file, such as the STL, so
+one can still use the STL.  One may also instantiate or specialize
+templates.
+
+@item -Wmismatched-new-delete @r{(C++ and Objective-C++ only)}
+@opindex Wmismatched-new-delete
+@opindex Wno-mismatched-new-delete
+Warn for mismatches between calls to @code{operator new} or @code{operator
+delete} and the corresponding call to the allocation or deallocation function.
+This includes invocations of C++ @code{operator delete} with pointers
+returned from either mismatched forms of @code{operator new}, or from other
+functions that allocate objects for which the @code{operator delete} isn't
+a suitable deallocator, as well as calls to other deallocation functions
+with pointers returned from @code{operator new} for which the deallocation
+function isn't suitable.
+
+For example, the @code{delete} expression in the function below is diagnosed
+because it doesn't match the array form of the @code{new} expression
+the pointer argument was returned from.  Similarly, the call to @code{free}
+is also diagnosed.
+
+@smallexample
+void f ()
+@{
+  int *a = new int[n];
+  delete a;   // warning: mismatch in array forms of expressions
+
+  char *p = new char[n];
+  free (p);   // warning: mismatch between new and free
+@}
+@end smallexample
+
+The related option @option{-Wmismatched-dealloc} diagnoses mismatches
+involving allocation and deallocation functions other than @code{operator
+new} and @code{operator delete}.
+
+@option{-Wmismatched-new-delete} is included in @option{-Wall}.
+
+@item -Wmismatched-tags @r{(C++ and Objective-C++ only)}
+@opindex Wmismatched-tags
+@opindex Wno-mismatched-tags
+Warn for declarations of structs, classes, and class templates and their
+specializations with a class-key that does not match either the definition
+or the first declaration if no definition is provided.
+
+For example, the declaration of @code{struct Object} in the argument list
+of @code{draw} triggers the warning.  To avoid it, either remove the redundant
+class-key @code{struct} or replace it with @code{class} to match its definition.
+@smallexample
+class Object @{
+public:
+  virtual ~Object () = 0;
+@};
+void draw (struct Object*);
+@end smallexample
+
+It is not wrong to declare a class with the class-key @code{struct} as
+the example above shows.  The @option{-Wmismatched-tags} option is intended
+to help achieve a consistent style of class declarations.  In code that is
+intended to be portable to Windows-based compilers the warning helps prevent
+unresolved references due to the difference in the mangling of symbols
+declared with different class-keys.  The option can be used either on its
+own or in conjunction with @option{-Wredundant-tags}.
+
+@item -Wmultiple-inheritance @r{(C++ and Objective-C++ only)}
+@opindex Wmultiple-inheritance
+@opindex Wno-multiple-inheritance
+Warn when a class is defined with multiple direct base classes.  Some
+coding rules disallow multiple inheritance, and this may be used to
+enforce that rule.  The warning is inactive inside a system header file,
+such as the STL, so one can still use the STL.  One may also define
+classes that indirectly use multiple inheritance.
+
+@item -Wvirtual-inheritance
+@opindex Wvirtual-inheritance
+@opindex Wno-virtual-inheritance
+Warn when a class is defined with a virtual direct base class.  Some
+coding rules disallow multiple inheritance, and this may be used to
+enforce that rule.  The warning is inactive inside a system header file,
+such as the STL, so one can still use the STL.  One may also define
+classes that indirectly use virtual inheritance.
+
+@item -Wno-virtual-move-assign
+@opindex Wvirtual-move-assign
+@opindex Wno-virtual-move-assign
+Suppress warnings about inheriting from a virtual base with a
+non-trivial C++11 move assignment operator.  This is dangerous because
+if the virtual base is reachable along more than one path, it is
+moved multiple times, which can mean both objects end up in the
+moved-from state.  If the move assignment operator is written to avoid
+moving from a moved-from object, this warning can be disabled.
+
+@item -Wnamespaces
+@opindex Wnamespaces
+@opindex Wno-namespaces
+Warn when a namespace definition is opened.  Some coding rules disallow
+namespaces, and this may be used to enforce that rule.  The warning is
+inactive inside a system header file, such as the STL, so one can still
+use the STL.  One may also use using directives and qualified names.
+
+@item -Wno-terminate @r{(C++ and Objective-C++ only)}
+@opindex Wterminate
+@opindex Wno-terminate
+Disable the warning about a throw-expression that will immediately
+result in a call to @code{terminate}.
+
+@item -Wno-vexing-parse @r{(C++ and Objective-C++ only)}
+@opindex Wvexing-parse
+@opindex Wno-vexing-parse
+Warn about the most vexing parse syntactic ambiguity.  This warns about
+the cases when a declaration looks like a variable definition, but the
+C++ language requires it to be interpreted as a function declaration.
+For instance:
+
+@smallexample
+void f(double a) @{
+  int i();        // extern int i (void);
+  int n(int(a));  // extern int n (int);
+@}
+@end smallexample
+
+Another example:
+
+@smallexample
+struct S @{ S(int); @};
+void f(double a) @{
+  S x(int(a));   // extern struct S x (int);
+  S y(int());    // extern struct S y (int (*) (void));
+  S z();         // extern struct S z (void);
+@}
+@end smallexample
+
+The warning will suggest options how to deal with such an ambiguity; e.g.,
+it can suggest removing the parentheses or using braces instead.
+
+This warning is enabled by default.
+
+@item -Wno-class-conversion @r{(C++ and Objective-C++ only)}
+@opindex Wno-class-conversion
+@opindex Wclass-conversion
+Do not warn when a conversion function converts an
+object to the same type, to a base class of that type, or to void; such
+a conversion function will never be called.
+
+@item -Wvolatile @r{(C++ and Objective-C++ only)}
+@opindex Wvolatile
+@opindex Wno-volatile
+Warn about deprecated uses of the @code{volatile} qualifier.  This includes
+postfix and prefix @code{++} and @code{--} expressions of
+@code{volatile}-qualified types, using simple assignments where the left
+operand is a @code{volatile}-qualified non-class type for their value,
+compound assignments where the left operand is a @code{volatile}-qualified
+non-class type, @code{volatile}-qualified function return type,
+@code{volatile}-qualified parameter type, and structured bindings of a
+@code{volatile}-qualified type.  This usage was deprecated in C++20.
+
+Enabled by default with @option{-std=c++20}.
+
+@item -Wzero-as-null-pointer-constant @r{(C++ and Objective-C++ only)}
+@opindex Wzero-as-null-pointer-constant
+@opindex Wno-zero-as-null-pointer-constant
+Warn when a literal @samp{0} is used as null pointer constant.  This can
+be useful to facilitate the conversion to @code{nullptr} in C++11.
+
+@item -Waligned-new
+@opindex Waligned-new
+@opindex Wno-aligned-new
+Warn about a new-expression of a type that requires greater alignment
+than the @code{alignof(std::max_align_t)} but uses an allocation
+function without an explicit alignment parameter. This option is
+enabled by @option{-Wall}.
+
+Normally this only warns about global allocation functions, but
+@option{-Waligned-new=all} also warns about class member allocation
+functions.
+
+@item -Wno-placement-new
+@itemx -Wplacement-new=@var{n}
+@opindex Wplacement-new
+@opindex Wno-placement-new
+Warn about placement new expressions with undefined behavior, such as
+constructing an object in a buffer that is smaller than the type of
+the object.  For example, the placement new expression below is diagnosed
+because it attempts to construct an array of 64 integers in a buffer only
+64 bytes large.
+@smallexample
+char buf [64];
+new (buf) int[64];
+@end smallexample
+This warning is enabled by default.
+
+@table @gcctabopt
+@item -Wplacement-new=1
+This is the default warning level of @option{-Wplacement-new}.  At this
+level the warning is not issued for some strictly undefined constructs that
+GCC allows as extensions for compatibility with legacy code.  For example,
+the following @code{new} expression is not diagnosed at this level even
+though it has undefined behavior according to the C++ standard because
+it writes past the end of the one-element array.
+@smallexample
+struct S @{ int n, a[1]; @};
+S *s = (S *)malloc (sizeof *s + 31 * sizeof s->a[0]);
+new (s->a)int [32]();
+@end smallexample
+
+@item -Wplacement-new=2
+At this level, in addition to diagnosing all the same constructs as at level
+1, a diagnostic is also issued for placement new expressions that construct
+an object in the last member of structure whose type is an array of a single
+element and whose size is less than the size of the object being constructed.
+While the previous example would be diagnosed, the following construct makes
+use of the flexible member array extension to avoid the warning at level 2.
+@smallexample
+struct S @{ int n, a[]; @};
+S *s = (S *)malloc (sizeof *s + 32 * sizeof s->a[0]);
+new (s->a)int [32]();
+@end smallexample
+
+@end table
+
+@item -Wcatch-value
+@itemx -Wcatch-value=@var{n} @r{(C++ and Objective-C++ only)}
+@opindex Wcatch-value
+@opindex Wno-catch-value
+Warn about catch handlers that do not catch via reference.
+With @option{-Wcatch-value=1} (or @option{-Wcatch-value} for short)
+warn about polymorphic class types that are caught by value.
+With @option{-Wcatch-value=2} warn about all class types that are caught
+by value. With @option{-Wcatch-value=3} warn about all types that are
+not caught by reference. @option{-Wcatch-value} is enabled by @option{-Wall}.
+
+@item -Wconditionally-supported @r{(C++ and Objective-C++ only)}
+@opindex Wconditionally-supported
+@opindex Wno-conditionally-supported
+Warn for conditionally-supported (C++11 [intro.defs]) constructs.
+
+@item -Wno-delete-incomplete @r{(C++ and Objective-C++ only)}
+@opindex Wdelete-incomplete
+@opindex Wno-delete-incomplete
+Do not warn when deleting a pointer to incomplete type, which may cause
+undefined behavior at runtime.  This warning is enabled by default.
+
+@item -Wextra-semi @r{(C++, Objective-C++ only)}
+@opindex Wextra-semi
+@opindex Wno-extra-semi
+Warn about redundant semicolons after in-class function definitions.
+
+@item -Wno-inaccessible-base @r{(C++, Objective-C++ only)}
+@opindex Winaccessible-base
+@opindex Wno-inaccessible-base
+This option controls warnings
+when a base class is inaccessible in a class derived from it due to
+ambiguity.  The warning is enabled by default.
+Note that the warning for ambiguous virtual
+bases is enabled by the @option{-Wextra} option.
+@smallexample
+@group
+struct A @{ int a; @};
+
+struct B : A @{ @};
+
+struct C : B, A @{ @};
+@end group
+@end smallexample
+
+@item -Wno-inherited-variadic-ctor
+@opindex Winherited-variadic-ctor
+@opindex Wno-inherited-variadic-ctor
+Suppress warnings about use of C++11 inheriting constructors when the
+base class inherited from has a C variadic constructor; the warning is
+on by default because the ellipsis is not inherited.
+
+@item -Wno-invalid-offsetof @r{(C++ and Objective-C++ only)}
+@opindex Wno-invalid-offsetof
+@opindex Winvalid-offsetof
+Suppress warnings from applying the @code{offsetof} macro to a non-POD
+type.  According to the 2014 ISO C++ standard, applying @code{offsetof}
+to a non-standard-layout type is undefined.  In existing C++ implementations,
+however, @code{offsetof} typically gives meaningful results.
+This flag is for users who are aware that they are
+writing nonportable code and who have deliberately chosen to ignore the
+warning about it.
+
+The restrictions on @code{offsetof} may be relaxed in a future version
+of the C++ standard.
+
+@item -Wsized-deallocation @r{(C++ and Objective-C++ only)}
+@opindex Wsized-deallocation
+@opindex Wno-sized-deallocation
+Warn about a definition of an unsized deallocation function
+@smallexample
+void operator delete (void *) noexcept;
+void operator delete[] (void *) noexcept;
+@end smallexample
+without a definition of the corresponding sized deallocation function
+@smallexample
+void operator delete (void *, std::size_t) noexcept;
+void operator delete[] (void *, std::size_t) noexcept;
+@end smallexample
+or vice versa.  Enabled by @option{-Wextra} along with
+@option{-fsized-deallocation}.
+
+@item -Wsuggest-final-types
+@opindex Wno-suggest-final-types
+@opindex Wsuggest-final-types
+Warn about types with virtual methods where code quality would be improved
+if the type were declared with the C++11 @code{final} specifier,
+or, if possible,
+declared in an anonymous namespace. This allows GCC to more aggressively
+devirtualize the polymorphic calls. This warning is more effective with
+link-time optimization,
+where the information about the class hierarchy graph is
+more complete.
+
+@item -Wsuggest-final-methods
+@opindex Wno-suggest-final-methods
+@opindex Wsuggest-final-methods
+Warn about virtual methods where code quality would be improved if the method
+were declared with the C++11 @code{final} specifier,
+or, if possible, its type were
+declared in an anonymous namespace or with the @code{final} specifier.
+This warning is
+more effective with link-time optimization, where the information about the
+class hierarchy graph is more complete. It is recommended to first consider
+suggestions of @option{-Wsuggest-final-types} and then rebuild with new
+annotations.
+
+@item -Wsuggest-override
+@opindex Wsuggest-override
+@opindex Wno-suggest-override
+Warn about overriding virtual functions that are not marked with the
+@code{override} keyword.
+
+@item -Wuse-after-free
+@itemx -Wuse-after-free=@var{n}
+@opindex Wuse-after-free
+@opindex Wno-use-after-free
+Warn about uses of pointers to dynamically allocated objects that have
+been rendered indeterminate by a call to a deallocation function.
+The warning is enabled at all optimization levels but may yield different
+results with optimization than without.
+
+@table @gcctabopt
+@item -Wuse-after-free=1
+At level 1 the warning attempts to diagnose only unconditional uses
+of pointers made indeterminate by a deallocation call or a successful
+call to @code{realloc}, regardless of whether or not the call resulted
+in an actual reallocatio of memory.  This includes double-@code{free}
+calls as well as uses in arithmetic and relational expressions.  Although
+undefined, uses of indeterminate pointers in equality (or inequality)
+expressions are not diagnosed at this level.
+@item -Wuse-after-free=2
+At level 2, in addition to unconditional uses, the warning also diagnoses
+conditional uses of pointers made indeterminate by a deallocation call.
+As at level 2, uses in equality (or inequality) expressions are not
+diagnosed.  For example, the second call to @code{free} in the following
+function is diagnosed at this level:
+@smallexample
+struct A @{ int refcount; void *data; @};
+
+void release (struct A *p)
+@{
+  int refcount = --p->refcount;
+  free (p);
+  if (refcount == 0)
+    free (p->data);   // warning: p may be used after free
+@}
+@end smallexample
+@item -Wuse-after-free=3
+At level 3, the warning also diagnoses uses of indeterminate pointers in
+equality expressions.  All uses of indeterminate pointers are undefined
+but equality tests sometimes appear after calls to @code{realloc} as
+an attempt to determine whether the call resulted in relocating the object
+to a different address.  They are diagnosed at a separate level to aid
+legacy code gradually transition to safe alternatives.  For example,
+the equality test in the function below is diagnosed at this level:
+@smallexample
+void adjust_pointers (int**, int);
+
+void grow (int **p, int n)
+@{
+  int **q = (int**)realloc (p, n *= 2);
+  if (q == p)
+    return;
+  adjust_pointers ((int**)q, n);
+@}
+@end smallexample
+To avoid the warning at this level, store offsets into allocated memory
+instead of pointers.  This approach obviates needing to adjust the stored
+pointers after reallocation.
+@end table
+
+@option{-Wuse-after-free=2} is included in @option{-Wall}.
+
+@item -Wuseless-cast @r{(C++ and Objective-C++ only)}
+@opindex Wuseless-cast
+@opindex Wno-useless-cast
+Warn when an expression is cast to its own type.  This warning does not
+occur when a class object is converted to a non-reference type as that
+is a way to create a temporary:
+
+@smallexample
+struct S @{ @};
+void g (S&&);
+void f (S&& arg)
+@{
+  g (S(arg)); // make arg prvalue so that it can bind to S&&
+@}
+@end smallexample
+
+@item -Wno-conversion-null @r{(C++ and Objective-C++ only)}
+@opindex Wconversion-null
+@opindex Wno-conversion-null
+Do not warn for conversions between @code{NULL} and non-pointer
+types. @option{-Wconversion-null} is enabled by default.
+
+@end table
+
+@node Objective-C and Objective-C++ Dialect Options
+@section Options Controlling Objective-C and Objective-C++ Dialects
+
+@cindex compiler options, Objective-C and Objective-C++
+@cindex Objective-C and Objective-C++ options, command-line
+@cindex options, Objective-C and Objective-C++
+(NOTE: This manual does not describe the Objective-C and Objective-C++
+languages themselves.  @xref{Standards,,Language Standards
+Supported by GCC}, for references.)
+
+This section describes the command-line options that are only meaningful
+for Objective-C and Objective-C++ programs.  You can also use most of
+the language-independent GNU compiler options.
+For example, you might compile a file @file{some_class.m} like this:
+
+@smallexample
+gcc -g -fgnu-runtime -O -c some_class.m
+@end smallexample
+
+@noindent
+In this example, @option{-fgnu-runtime} is an option meant only for
+Objective-C and Objective-C++ programs; you can use the other options with
+any language supported by GCC@.
+
+Note that since Objective-C is an extension of the C language, Objective-C
+compilations may also use options specific to the C front-end (e.g.,
+@option{-Wtraditional}).  Similarly, Objective-C++ compilations may use
+C++-specific options (e.g., @option{-Wabi}).
+
+Here is a list of options that are @emph{only} for compiling Objective-C
+and Objective-C++ programs:
+
+@table @gcctabopt
+@item -fconstant-string-class=@var{class-name}
+@opindex fconstant-string-class
+Use @var{class-name} as the name of the class to instantiate for each
+literal string specified with the syntax @code{@@"@dots{}"}.  The default
+class name is @code{NXConstantString} if the GNU runtime is being used, and
+@code{NSConstantString} if the NeXT runtime is being used (see below).  The
+@option{-fconstant-cfstrings} option, if also present, overrides the
+@option{-fconstant-string-class} setting and cause @code{@@"@dots{}"} literals
+to be laid out as constant CoreFoundation strings.
+
+@item -fgnu-runtime
+@opindex fgnu-runtime
+Generate object code compatible with the standard GNU Objective-C
+runtime.  This is the default for most types of systems.
+
+@item -fnext-runtime
+@opindex fnext-runtime
+Generate output compatible with the NeXT runtime.  This is the default
+for NeXT-based systems, including Darwin and Mac OS X@.  The macro
+@code{__NEXT_RUNTIME__} is predefined if (and only if) this option is
+used.
+
+@item -fno-nil-receivers
+@opindex fno-nil-receivers
+@opindex fnil-receivers
+Assume that all Objective-C message dispatches (@code{[receiver
+message:arg]}) in this translation unit ensure that the receiver is
+not @code{nil}.  This allows for more efficient entry points in the
+runtime to be used.  This option is only available in conjunction with
+the NeXT runtime and ABI version 0 or 1.
+
+@item -fobjc-abi-version=@var{n}
+@opindex fobjc-abi-version
+Use version @var{n} of the Objective-C ABI for the selected runtime.
+This option is currently supported only for the NeXT runtime.  In that
+case, Version 0 is the traditional (32-bit) ABI without support for
+properties and other Objective-C 2.0 additions.  Version 1 is the
+traditional (32-bit) ABI with support for properties and other
+Objective-C 2.0 additions.  Version 2 is the modern (64-bit) ABI.  If
+nothing is specified, the default is Version 0 on 32-bit target
+machines, and Version 2 on 64-bit target machines.
+
+@item -fobjc-call-cxx-cdtors
+@opindex fobjc-call-cxx-cdtors
+For each Objective-C class, check if any of its instance variables is a
+C++ object with a non-trivial default constructor.  If so, synthesize a
+special @code{- (id) .cxx_construct} instance method which runs
+non-trivial default constructors on any such instance variables, in order,
+and then return @code{self}.  Similarly, check if any instance variable
+is a C++ object with a non-trivial destructor, and if so, synthesize a
+special @code{- (void) .cxx_destruct} method which runs
+all such default destructors, in reverse order.
+
+The @code{- (id) .cxx_construct} and @code{- (void) .cxx_destruct}
+methods thusly generated only operate on instance variables
+declared in the current Objective-C class, and not those inherited
+from superclasses.  It is the responsibility of the Objective-C
+runtime to invoke all such methods in an object's inheritance
+hierarchy.  The @code{- (id) .cxx_construct} methods are invoked
+by the runtime immediately after a new object instance is allocated;
+the @code{- (void) .cxx_destruct} methods are invoked immediately
+before the runtime deallocates an object instance.
+
+As of this writing, only the NeXT runtime on Mac OS X 10.4 and later has
+support for invoking the @code{- (id) .cxx_construct} and
+@code{- (void) .cxx_destruct} methods.
+
+@item -fobjc-direct-dispatch
+@opindex fobjc-direct-dispatch
+Allow fast jumps to the message dispatcher.  On Darwin this is
+accomplished via the comm page.
+
+@item -fobjc-exceptions
+@opindex fobjc-exceptions
+Enable syntactic support for structured exception handling in
+Objective-C, similar to what is offered by C++.  This option
+is required to use the Objective-C keywords @code{@@try},
+@code{@@throw}, @code{@@catch}, @code{@@finally} and
+@code{@@synchronized}.  This option is available with both the GNU
+runtime and the NeXT runtime (but not available in conjunction with
+the NeXT runtime on Mac OS X 10.2 and earlier).
+
+@item -fobjc-gc
+@opindex fobjc-gc
+Enable garbage collection (GC) in Objective-C and Objective-C++
+programs.  This option is only available with the NeXT runtime; the
+GNU runtime has a different garbage collection implementation that
+does not require special compiler flags.
+
+@item -fobjc-nilcheck
+@opindex fobjc-nilcheck
+For the NeXT runtime with version 2 of the ABI, check for a nil
+receiver in method invocations before doing the actual method call.
+This is the default and can be disabled using
+@option{-fno-objc-nilcheck}.  Class methods and super calls are never
+checked for nil in this way no matter what this flag is set to.
+Currently this flag does nothing when the GNU runtime, or an older
+version of the NeXT runtime ABI, is used.
+
+@item -fobjc-std=objc1
+@opindex fobjc-std
+Conform to the language syntax of Objective-C 1.0, the language
+recognized by GCC 4.0.  This only affects the Objective-C additions to
+the C/C++ language; it does not affect conformance to C/C++ standards,
+which is controlled by the separate C/C++ dialect option flags.  When
+this option is used with the Objective-C or Objective-C++ compiler,
+any Objective-C syntax that is not recognized by GCC 4.0 is rejected.
+This is useful if you need to make sure that your Objective-C code can
+be compiled with older versions of GCC@.
+
+@item -freplace-objc-classes
+@opindex freplace-objc-classes
+Emit a special marker instructing @command{ld(1)} not to statically link in
+the resulting object file, and allow @command{dyld(1)} to load it in at
+run time instead.  This is used in conjunction with the Fix-and-Continue
+debugging mode, where the object file in question may be recompiled and
+dynamically reloaded in the course of program execution, without the need
+to restart the program itself.  Currently, Fix-and-Continue functionality
+is only available in conjunction with the NeXT runtime on Mac OS X 10.3
+and later.
+
+@item -fzero-link
+@opindex fzero-link
+When compiling for the NeXT runtime, the compiler ordinarily replaces calls
+to @code{objc_getClass("@dots{}")} (when the name of the class is known at
+compile time) with static class references that get initialized at load time,
+which improves run-time performance.  Specifying the @option{-fzero-link} flag
+suppresses this behavior and causes calls to @code{objc_getClass("@dots{}")}
+to be retained.  This is useful in Zero-Link debugging mode, since it allows
+for individual class implementations to be modified during program execution.
+The GNU runtime currently always retains calls to @code{objc_get_class("@dots{}")}
+regardless of command-line options.
+
+@item -fno-local-ivars
+@opindex fno-local-ivars
+@opindex flocal-ivars
+By default instance variables in Objective-C can be accessed as if
+they were local variables from within the methods of the class they're
+declared in.  This can lead to shadowing between instance variables
+and other variables declared either locally inside a class method or
+globally with the same name.  Specifying the @option{-fno-local-ivars}
+flag disables this behavior thus avoiding variable shadowing issues.
+
+@item -fivar-visibility=@r{[}public@r{|}protected@r{|}private@r{|}package@r{]}
+@opindex fivar-visibility
+Set the default instance variable visibility to the specified option
+so that instance variables declared outside the scope of any access
+modifier directives default to the specified visibility.
+
+@item -gen-decls
+@opindex gen-decls
+Dump interface declarations for all classes seen in the source file to a
+file named @file{@var{sourcename}.decl}.
+
+@item -Wassign-intercept @r{(Objective-C and Objective-C++ only)}
+@opindex Wassign-intercept
+@opindex Wno-assign-intercept
+Warn whenever an Objective-C assignment is being intercepted by the
+garbage collector.
+
+@item -Wno-property-assign-default @r{(Objective-C and Objective-C++ only)}
+@opindex Wproperty-assign-default
+@opindex Wno-property-assign-default
+Do not warn if a property for an Objective-C object has no assign
+semantics specified.
+
+@item -Wno-protocol @r{(Objective-C and Objective-C++ only)}
+@opindex Wno-protocol
+@opindex Wprotocol
+If a class is declared to implement a protocol, a warning is issued for
+every method in the protocol that is not implemented by the class.  The
+default behavior is to issue a warning for every method not explicitly
+implemented in the class, even if a method implementation is inherited
+from the superclass.  If you use the @option{-Wno-protocol} option, then
+methods inherited from the superclass are considered to be implemented,
+and no warning is issued for them.
+
+@item -Wobjc-root-class @r{(Objective-C and Objective-C++ only)}
+@opindex Wobjc-root-class
+Warn if a class interface lacks a superclass. Most classes will inherit
+from @code{NSObject} (or @code{Object}) for example.  When declaring
+classes intended to be root classes, the warning can be suppressed by
+marking their interfaces with @code{__attribute__((objc_root_class))}.
+
+@item -Wselector @r{(Objective-C and Objective-C++ only)}
+@opindex Wselector
+@opindex Wno-selector
+Warn if multiple methods of different types for the same selector are
+found during compilation.  The check is performed on the list of methods
+in the final stage of compilation.  Additionally, a check is performed
+for each selector appearing in a @code{@@selector(@dots{})}
+expression, and a corresponding method for that selector has been found
+during compilation.  Because these checks scan the method table only at
+the end of compilation, these warnings are not produced if the final
+stage of compilation is not reached, for example because an error is
+found during compilation, or because the @option{-fsyntax-only} option is
+being used.
+
+@item -Wstrict-selector-match @r{(Objective-C and Objective-C++ only)}
+@opindex Wstrict-selector-match
+@opindex Wno-strict-selector-match
+Warn if multiple methods with differing argument and/or return types are
+found for a given selector when attempting to send a message using this
+selector to a receiver of type @code{id} or @code{Class}.  When this flag
+is off (which is the default behavior), the compiler omits such warnings
+if any differences found are confined to types that share the same size
+and alignment.
+
+@item -Wundeclared-selector @r{(Objective-C and Objective-C++ only)}
+@opindex Wundeclared-selector
+@opindex Wno-undeclared-selector
+Warn if a @code{@@selector(@dots{})} expression referring to an
+undeclared selector is found.  A selector is considered undeclared if no
+method with that name has been declared before the
+@code{@@selector(@dots{})} expression, either explicitly in an
+@code{@@interface} or @code{@@protocol} declaration, or implicitly in
+an @code{@@implementation} section.  This option always performs its
+checks as soon as a @code{@@selector(@dots{})} expression is found,
+while @option{-Wselector} only performs its checks in the final stage of
+compilation.  This also enforces the coding style convention
+that methods and selectors must be declared before being used.
+
+@item -print-objc-runtime-info
+@opindex print-objc-runtime-info
+Generate C header describing the largest structure that is passed by
+value, if any.
+
+@end table
+
+@node Diagnostic Message Formatting Options
+@section Options to Control Diagnostic Messages Formatting
+@cindex options to control diagnostics formatting
+@cindex diagnostic messages
+@cindex message formatting
+
+Traditionally, diagnostic messages have been formatted irrespective of
+the output device's aspect (e.g.@: its width, @dots{}).  You can use the
+options described below
+to control the formatting algorithm for diagnostic messages, 
+e.g.@: how many characters per line, how often source location
+information should be reported.  Note that some language front ends may not
+honor these options.
+
+@table @gcctabopt
+@item -fmessage-length=@var{n}
+@opindex fmessage-length
+Try to format error messages so that they fit on lines of about
+@var{n} characters.  If @var{n} is zero, then no line-wrapping is
+done; each error message appears on a single line.  This is the
+default for all front ends.
+
+Note - this option also affects the display of the @samp{#error} and
+@samp{#warning} pre-processor directives, and the @samp{deprecated}
+function/type/variable attribute.  It does not however affect the
+@samp{pragma GCC warning} and @samp{pragma GCC error} pragmas.
+
+@item -fdiagnostics-plain-output
+This option requests that diagnostic output look as plain as possible, which
+may be useful when running @command{dejagnu} or other utilities that need to
+parse diagnostics output and prefer that it remain more stable over time.
+@option{-fdiagnostics-plain-output} is currently equivalent to the following
+options:
+@gccoptlist{-fno-diagnostics-show-caret @gol
+-fno-diagnostics-show-line-numbers @gol
+-fdiagnostics-color=never @gol
+-fdiagnostics-urls=never @gol
+-fdiagnostics-path-format=separate-events}
+In the future, if GCC changes the default appearance of its diagnostics, the
+corresponding option to disable the new behavior will be added to this list.
+
+@item -fdiagnostics-show-location=once
+@opindex fdiagnostics-show-location
+Only meaningful in line-wrapping mode.  Instructs the diagnostic messages
+reporter to emit source location information @emph{once}; that is, in
+case the message is too long to fit on a single physical line and has to
+be wrapped, the source location won't be emitted (as prefix) again,
+over and over, in subsequent continuation lines.  This is the default
+behavior.
+
+@item -fdiagnostics-show-location=every-line
+Only meaningful in line-wrapping mode.  Instructs the diagnostic
+messages reporter to emit the same source location information (as
+prefix) for physical lines that result from the process of breaking
+a message which is too long to fit on a single line.
+
+@item -fdiagnostics-color[=@var{WHEN}]
+@itemx -fno-diagnostics-color
+@opindex fdiagnostics-color
+@cindex highlight, color
+@vindex GCC_COLORS @r{environment variable}
+Use color in diagnostics.  @var{WHEN} is @samp{never}, @samp{always},
+or @samp{auto}.  The default depends on how the compiler has been configured,
+it can be any of the above @var{WHEN} options or also @samp{never}
+if @env{GCC_COLORS} environment variable isn't present in the environment,
+and @samp{auto} otherwise.
+@samp{auto} makes GCC use color only when the standard error is a terminal,
+and when not executing in an emacs shell.
+The forms @option{-fdiagnostics-color} and @option{-fno-diagnostics-color} are
+aliases for @option{-fdiagnostics-color=always} and
+@option{-fdiagnostics-color=never}, respectively.
+
+The colors are defined by the environment variable @env{GCC_COLORS}.
+Its value is a colon-separated list of capabilities and Select Graphic
+Rendition (SGR) substrings. SGR commands are interpreted by the
+terminal or terminal emulator.  (See the section in the documentation
+of your text terminal for permitted values and their meanings as
+character attributes.)  These substring values are integers in decimal
+representation and can be concatenated with semicolons.
+Common values to concatenate include
+@samp{1} for bold,
+@samp{4} for underline,
+@samp{5} for blink,
+@samp{7} for inverse,
+@samp{39} for default foreground color,
+@samp{30} to @samp{37} for foreground colors,
+@samp{90} to @samp{97} for 16-color mode foreground colors,
+@samp{38;5;0} to @samp{38;5;255}
+for 88-color and 256-color modes foreground colors,
+@samp{49} for default background color,
+@samp{40} to @samp{47} for background colors,
+@samp{100} to @samp{107} for 16-color mode background colors,
+and @samp{48;5;0} to @samp{48;5;255}
+for 88-color and 256-color modes background colors.
+
+The default @env{GCC_COLORS} is
+@smallexample
+error=01;31:warning=01;35:note=01;36:range1=32:range2=34:locus=01:\
+quote=01:path=01;36:fixit-insert=32:fixit-delete=31:\
+diff-filename=01:diff-hunk=32:diff-delete=31:diff-insert=32:\
+type-diff=01;32:fnname=01;32:targs=35
+@end smallexample
+@noindent
+where @samp{01;31} is bold red, @samp{01;35} is bold magenta,
+@samp{01;36} is bold cyan, @samp{32} is green, @samp{34} is blue,
+@samp{01} is bold, and @samp{31} is red.
+Setting @env{GCC_COLORS} to the empty string disables colors.
+Supported capabilities are as follows.
+
+@table @code
+@item error=
+@vindex error GCC_COLORS @r{capability}
+SGR substring for error: markers.
+
+@item warning=
+@vindex warning GCC_COLORS @r{capability}
+SGR substring for warning: markers.
+
+@item note=
+@vindex note GCC_COLORS @r{capability}
+SGR substring for note: markers.
+
+@item path=
+@vindex path GCC_COLORS @r{capability}
+SGR substring for colorizing paths of control-flow events as printed
+via @option{-fdiagnostics-path-format=}, such as the identifiers of
+individual events and lines indicating interprocedural calls and returns.
+
+@item range1=
+@vindex range1 GCC_COLORS @r{capability}
+SGR substring for first additional range.
+
+@item range2=
+@vindex range2 GCC_COLORS @r{capability}
+SGR substring for second additional range.
+
+@item locus=
+@vindex locus GCC_COLORS @r{capability}
+SGR substring for location information, @samp{file:line} or
+@samp{file:line:column} etc.
+
+@item quote=
+@vindex quote GCC_COLORS @r{capability}
+SGR substring for information printed within quotes.
+
+@item fnname=
+@vindex fnname GCC_COLORS @r{capability}
+SGR substring for names of C++ functions.
+
+@item targs=
+@vindex targs GCC_COLORS @r{capability}
+SGR substring for C++ function template parameter bindings.
+
+@item fixit-insert=
+@vindex fixit-insert GCC_COLORS @r{capability}
+SGR substring for fix-it hints suggesting text to
+be inserted or replaced.
+
+@item fixit-delete=
+@vindex fixit-delete GCC_COLORS @r{capability}
+SGR substring for fix-it hints suggesting text to
+be deleted.
+
+@item diff-filename=
+@vindex diff-filename GCC_COLORS @r{capability}
+SGR substring for filename headers within generated patches.
+
+@item diff-hunk=
+@vindex diff-hunk GCC_COLORS @r{capability}
+SGR substring for the starts of hunks within generated patches.
+
+@item diff-delete=
+@vindex diff-delete GCC_COLORS @r{capability}
+SGR substring for deleted lines within generated patches.
+
+@item diff-insert=
+@vindex diff-insert GCC_COLORS @r{capability}
+SGR substring for inserted lines within generated patches.
+
+@item type-diff=
+@vindex type-diff GCC_COLORS @r{capability}
+SGR substring for highlighting mismatching types within template
+arguments in the C++ frontend.
+@end table
+
+@item -fdiagnostics-urls[=@var{WHEN}]
+@opindex fdiagnostics-urls
+@cindex urls
+@vindex GCC_URLS @r{environment variable}
+@vindex TERM_URLS @r{environment variable}
+Use escape sequences to embed URLs in diagnostics.  For example, when
+@option{-fdiagnostics-show-option} emits text showing the command-line
+option controlling a diagnostic, embed a URL for documentation of that
+option.
+
+@var{WHEN} is @samp{never}, @samp{always}, or @samp{auto}.
+@samp{auto} makes GCC use URL escape sequences only when the standard error
+is a terminal, and when not executing in an emacs shell or any graphical
+terminal which is known to be incompatible with this feature, see below.
+
+The default depends on how the compiler has been configured.
+It can be any of the above @var{WHEN} options.
+
+GCC can also be configured (via the
+@option{--with-diagnostics-urls=auto-if-env} configure-time option)
+so that the default is affected by environment variables.
+Under such a configuration, GCC defaults to using @samp{auto}
+if either @env{GCC_URLS} or @env{TERM_URLS} environment variables are
+present and non-empty in the environment of the compiler, or @samp{never}
+if neither are.
+
+However, even with @option{-fdiagnostics-urls=always} the behavior is
+dependent on those environment variables:
+If @env{GCC_URLS} is set to empty or @samp{no}, do not embed URLs in
+diagnostics.  If set to @samp{st}, URLs use ST escape sequences.
+If set to @samp{bel}, the default, URLs use BEL escape sequences.
+Any other non-empty value enables the feature.
+If @env{GCC_URLS} is not set, use @env{TERM_URLS} as a fallback.
+Note: ST is an ANSI escape sequence, string terminator @samp{ESC \},
+BEL is an ASCII character, CTRL-G that usually sounds like a beep.
+
+At this time GCC tries to detect also a few terminals that are known to
+not implement the URL feature, and have bugs or at least had bugs in
+some versions that are still in use, where the URL escapes are likely
+to misbehave, i.e. print garbage on the screen.
+That list is currently xfce4-terminal, certain known to be buggy
+gnome-terminal versions, the linux console, and mingw.
+This check can be skipped with the @option{-fdiagnostics-urls=always}.
+
+@item -fno-diagnostics-show-option
+@opindex fno-diagnostics-show-option
+@opindex fdiagnostics-show-option
+By default, each diagnostic emitted includes text indicating the
+command-line option that directly controls the diagnostic (if such an
+option is known to the diagnostic machinery).  Specifying the
+@option{-fno-diagnostics-show-option} flag suppresses that behavior.
+
+@item -fno-diagnostics-show-caret
+@opindex fno-diagnostics-show-caret
+@opindex fdiagnostics-show-caret
+By default, each diagnostic emitted includes the original source line
+and a caret @samp{^} indicating the column.  This option suppresses this
+information.  The source line is truncated to @var{n} characters, if
+the @option{-fmessage-length=n} option is given.  When the output is done
+to the terminal, the width is limited to the width given by the
+@env{COLUMNS} environment variable or, if not set, to the terminal width.
+
+@item -fno-diagnostics-show-labels
+@opindex fno-diagnostics-show-labels
+@opindex fdiagnostics-show-labels
+By default, when printing source code (via @option{-fdiagnostics-show-caret}),
+diagnostics can label ranges of source code with pertinent information, such
+as the types of expressions:
+
+@smallexample
+    printf ("foo %s bar", long_i + long_j);
+                 ~^       ~~~~~~~~~~~~~~~
+                  |              |
+                  char *         long int
+@end smallexample
+
+This option suppresses the printing of these labels (in the example above,
+the vertical bars and the ``char *'' and ``long int'' text).
+
+@item -fno-diagnostics-show-cwe
+@opindex fno-diagnostics-show-cwe
+@opindex fdiagnostics-show-cwe
+Diagnostic messages can optionally have an associated
+@uref{https://cwe.mitre.org/index.html, CWE} identifier.
+GCC itself only provides such metadata for some of the @option{-fanalyzer}
+diagnostics.  GCC plugins may also provide diagnostics with such metadata.
+By default, if this information is present, it will be printed with
+the diagnostic.  This option suppresses the printing of this metadata.
+
+@item -fno-diagnostics-show-rules
+@opindex fno-diagnostics-show-rules
+@opindex fdiagnostics-show-rules
+Diagnostic messages can optionally have rules associated with them, such
+as from a coding standard, or a specification.
+GCC itself does not do this for any of its diagnostics, but plugins may do so.
+By default, if this information is present, it will be printed with
+the diagnostic.  This option suppresses the printing of this metadata.
+
+@item -fno-diagnostics-show-line-numbers
+@opindex fno-diagnostics-show-line-numbers
+@opindex fdiagnostics-show-line-numbers
+By default, when printing source code (via @option{-fdiagnostics-show-caret}),
+a left margin is printed, showing line numbers.  This option suppresses this
+left margin.
+
+@item -fdiagnostics-minimum-margin-width=@var{width}
+@opindex fdiagnostics-minimum-margin-width
+This option controls the minimum width of the left margin printed by
+@option{-fdiagnostics-show-line-numbers}.  It defaults to 6.
+
+@item -fdiagnostics-parseable-fixits
+@opindex fdiagnostics-parseable-fixits
+Emit fix-it hints in a machine-parseable format, suitable for consumption
+by IDEs.  For each fix-it, a line will be printed after the relevant
+diagnostic, starting with the string ``fix-it:''.  For example:
+
+@smallexample
+fix-it:"test.c":@{45:3-45:21@}:"gtk_widget_show_all"
+@end smallexample
+
+The location is expressed as a half-open range, expressed as a count of
+bytes, starting at byte 1 for the initial column.  In the above example,
+bytes 3 through 20 of line 45 of ``test.c'' are to be replaced with the
+given string:
+
+@smallexample
+00000000011111111112222222222
+12345678901234567890123456789
+  gtk_widget_showall (dlg);
+  ^^^^^^^^^^^^^^^^^^
+  gtk_widget_show_all
+@end smallexample
+
+The filename and replacement string escape backslash as ``\\", tab as ``\t'',
+newline as ``\n'', double quotes as ``\"'', non-printable characters as octal
+(e.g. vertical tab as ``\013'').
+
+An empty replacement string indicates that the given range is to be removed.
+An empty range (e.g. ``45:3-45:3'') indicates that the string is to
+be inserted at the given position.
+
+@item -fdiagnostics-generate-patch
+@opindex fdiagnostics-generate-patch
+Print fix-it hints to stderr in unified diff format, after any diagnostics
+are printed.  For example:
+
+@smallexample
+--- test.c
++++ test.c
+@@ -42,5 +42,5 @@
+
+ void show_cb(GtkDialog *dlg)
+ @{
+-  gtk_widget_showall(dlg);
++  gtk_widget_show_all(dlg);
+ @}
+
+@end smallexample
+
+The diff may or may not be colorized, following the same rules
+as for diagnostics (see @option{-fdiagnostics-color}).
+
+@item -fdiagnostics-show-template-tree
+@opindex fdiagnostics-show-template-tree
+
+In the C++ frontend, when printing diagnostics showing mismatching
+template types, such as:
+
+@smallexample
+  could not convert 'std::map<int, std::vector<double> >()'
+    from 'map<[...],vector<double>>' to 'map<[...],vector<float>>
+@end smallexample
+
+the @option{-fdiagnostics-show-template-tree} flag enables printing a
+tree-like structure showing the common and differing parts of the types,
+such as:
+
+@smallexample
+  map<
+    [...],
+    vector<
+      [double != float]>>
+@end smallexample
+
+The parts that differ are highlighted with color (``double'' and
+``float'' in this case).
+
+@item -fno-elide-type
+@opindex fno-elide-type
+@opindex felide-type
+By default when the C++ frontend prints diagnostics showing mismatching
+template types, common parts of the types are printed as ``[...]'' to
+simplify the error message.  For example:
+
+@smallexample
+  could not convert 'std::map<int, std::vector<double> >()'
+    from 'map<[...],vector<double>>' to 'map<[...],vector<float>>
+@end smallexample
+
+Specifying the @option{-fno-elide-type} flag suppresses that behavior.
+This flag also affects the output of the
+@option{-fdiagnostics-show-template-tree} flag.
+
+@item -fdiagnostics-path-format=@var{KIND}
+@opindex fdiagnostics-path-format
+Specify how to print paths of control-flow events for diagnostics that
+have such a path associated with them.
+
+@var{KIND} is @samp{none}, @samp{separate-events}, or @samp{inline-events},
+the default.
+
+@samp{none} means to not print diagnostic paths.
+
+@samp{separate-events} means to print a separate ``note'' diagnostic for
+each event within the diagnostic.  For example:
+
+@smallexample
+test.c:29:5: error: passing NULL as argument 1 to 'PyList_Append' which requires a non-NULL parameter
+test.c:25:10: note: (1) when 'PyList_New' fails, returning NULL
+test.c:27:3: note: (2) when 'i < count'
+test.c:29:5: note: (3) when calling 'PyList_Append', passing NULL from (1) as argument 1
+@end smallexample
+
+@samp{inline-events} means to print the events ``inline'' within the source
+code.  This view attempts to consolidate the events into runs of
+sufficiently-close events, printing them as labelled ranges within the source.
+
+For example, the same events as above might be printed as:
+
+@smallexample
+  'test': events 1-3
+    |
+    |   25 |   list = PyList_New(0);
+    |      |          ^~~~~~~~~~~~~
+    |      |          |
+    |      |          (1) when 'PyList_New' fails, returning NULL
+    |   26 |
+    |   27 |   for (i = 0; i < count; i++) @{
+    |      |   ~~~
+    |      |   |
+    |      |   (2) when 'i < count'
+    |   28 |     item = PyLong_FromLong(random());
+    |   29 |     PyList_Append(list, item);
+    |      |     ~~~~~~~~~~~~~~~~~~~~~~~~~
+    |      |     |
+    |      |     (3) when calling 'PyList_Append', passing NULL from (1) as argument 1
+    |
+@end smallexample
+
+Interprocedural control flow is shown by grouping the events by stack frame,
+and using indentation to show how stack frames are nested, pushed, and popped.
+
+For example:
+
+@smallexample
+  'test': events 1-2
+    |
+    |  133 | @{
+    |      | ^
+    |      | |
+    |      | (1) entering 'test'
+    |  134 |   boxed_int *obj = make_boxed_int (i);
+    |      |                    ~~~~~~~~~~~~~~~~~~
+    |      |                    |
+    |      |                    (2) calling 'make_boxed_int'
+    |
+    +--> 'make_boxed_int': events 3-4
+           |
+           |  120 | @{
+           |      | ^
+           |      | |
+           |      | (3) entering 'make_boxed_int'
+           |  121 |   boxed_int *result = (boxed_int *)wrapped_malloc (sizeof (boxed_int));
+           |      |                                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+           |      |                                    |
+           |      |                                    (4) calling 'wrapped_malloc'
+           |
+           +--> 'wrapped_malloc': events 5-6
+                  |
+                  |    7 | @{
+                  |      | ^
+                  |      | |
+                  |      | (5) entering 'wrapped_malloc'
+                  |    8 |   return malloc (size);
+                  |      |          ~~~~~~~~~~~~~
+                  |      |          |
+                  |      |          (6) calling 'malloc'
+                  |
+    <-------------+
+    |
+ 'test': event 7
+    |
+    |  138 |   free_boxed_int (obj);
+    |      |   ^~~~~~~~~~~~~~~~~~~~
+    |      |   |
+    |      |   (7) calling 'free_boxed_int'
+    |
+(etc)
+@end smallexample
+
+@item -fdiagnostics-show-path-depths
+@opindex fdiagnostics-show-path-depths
+This option provides additional information when printing control-flow paths
+associated with a diagnostic.
+
+If this is option is provided then the stack depth will be printed for
+each run of events within @option{-fdiagnostics-path-format=inline-events}.
+If provided with @option{-fdiagnostics-path-format=separate-events}, then
+the stack depth and function declaration will be appended when printing
+each event.
+
+This is intended for use by GCC developers and plugin developers when
+debugging diagnostics that report interprocedural control flow.
+
+@item -fno-show-column
+@opindex fno-show-column
+@opindex fshow-column
+Do not print column numbers in diagnostics.  This may be necessary if
+diagnostics are being scanned by a program that does not understand the
+column numbers, such as @command{dejagnu}.
+
+@item -fdiagnostics-column-unit=@var{UNIT}
+@opindex fdiagnostics-column-unit
+Select the units for the column number.  This affects traditional diagnostics
+(in the absence of @option{-fno-show-column}), as well as JSON format
+diagnostics if requested.
+
+The default @var{UNIT}, @samp{display}, considers the number of display
+columns occupied by each character.  This may be larger than the number
+of bytes required to encode the character, in the case of tab
+characters, or it may be smaller, in the case of multibyte characters.
+For example, the character ``GREEK SMALL LETTER PI (U+03C0)'' occupies one
+display column, and its UTF-8 encoding requires two bytes; the character
+``SLIGHTLY SMILING FACE (U+1F642)'' occupies two display columns, and
+its UTF-8 encoding requires four bytes.
+
+Setting @var{UNIT} to @samp{byte} changes the column number to the raw byte
+count in all cases, as was traditionally output by GCC prior to version 11.1.0.
+
+@item -fdiagnostics-column-origin=@var{ORIGIN}
+@opindex fdiagnostics-column-origin
+Select the origin for column numbers, i.e. the column number assigned to the
+first column.  The default value of 1 corresponds to traditional GCC
+behavior and to the GNU style guide.  Some utilities may perform better with an
+origin of 0; any non-negative value may be specified.
+
+@item -fdiagnostics-escape-format=@var{FORMAT}
+@opindex fdiagnostics-escape-format
+When GCC prints pertinent source lines for a diagnostic it normally attempts
+to print the source bytes directly.  However, some diagnostics relate to encoding
+issues in the source file, such as malformed UTF-8, or issues with Unicode
+normalization.  These diagnostics are flagged so that GCC will escape bytes
+that are not printable ASCII when printing their pertinent source lines.
+
+This option controls how such bytes should be escaped.
+
+The default @var{FORMAT}, @samp{unicode} displays Unicode characters that
+are not printable ASCII in the form @samp{<U+XXXX>}, and bytes that do not
+correspond to a Unicode character validly-encoded in UTF-8-encoded will be
+displayed as hexadecimal in the form @samp{<XX>}.
+
+For example, a source line containing the string @samp{before} followed by the
+Unicode character U+03C0 (``GREEK SMALL LETTER PI'', with UTF-8 encoding
+0xCF 0x80) followed by the byte 0xBF (a stray UTF-8 trailing byte), followed by
+the string @samp{after} will be printed for such a diagnostic as:
+
+@smallexample
+ before<U+03C0><BF>after
+@end smallexample
+
+Setting @var{FORMAT} to @samp{bytes} will display all non-printable-ASCII bytes
+in the form @samp{<XX>}, thus showing the underlying encoding of non-ASCII
+Unicode characters.  For the example above, the following will be printed:
+
+@smallexample
+ before<CF><80><BF>after
+@end smallexample
+
+@item -fdiagnostics-format=@var{FORMAT}
+@opindex fdiagnostics-format
+Select a different format for printing diagnostics.
+@var{FORMAT} is @samp{text}, @samp{sarif-stderr}, @samp{sarif-file},
+@samp{json}, @samp{json-stderr}, or @samp{json-file}.
+
+The default is @samp{text}.
+
+The @samp{sarif-stderr} and @samp{sarif-file} formats both emit
+diagnostics in SARIF Version 2.1.0 format, either to stderr, or to a file
+named @file{@var{source}.sarif}, respectively.
+
+The @samp{json} format is a synonym for @samp{json-stderr}.
+The @samp{json-stderr} and @samp{json-file} formats are identical, apart from
+where the JSON is emitted to - with the former, the JSON is emitted to stderr,
+whereas with @samp{json-file} it is written to @file{@var{source}.gcc.json}.
+
+The emitted JSON consists of a top-level JSON array containing JSON objects
+representing the diagnostics.  The JSON is emitted as one line, without
+formatting; the examples below have been formatted for clarity.
+
+Diagnostics can have child diagnostics.  For example, this error and note:
+
+@smallexample
+misleading-indentation.c:15:3: warning: this 'if' clause does not
+  guard... [-Wmisleading-indentation]
+   15 |   if (flag)
+      |   ^~
+misleading-indentation.c:17:5: note: ...this statement, but the latter
+  is misleadingly indented as if it were guarded by the 'if'
+   17 |     y = 2;
+      |     ^
+@end smallexample
+
+@noindent
+might be printed in JSON form (after formatting) like this:
+
+@smallexample
+[
+    @{
+        "kind": "warning",
+        "locations": [
+            @{
+                "caret": @{
+		    "display-column": 3,
+		    "byte-column": 3,
+                    "column": 3,
+                    "file": "misleading-indentation.c",
+                    "line": 15
+                @},
+                "finish": @{
+		    "display-column": 4,
+		    "byte-column": 4,
+                    "column": 4,
+                    "file": "misleading-indentation.c",
+                    "line": 15
+                @}
+            @}
+        ],
+        "message": "this \u2018if\u2019 clause does not guard...",
+        "option": "-Wmisleading-indentation",
+        "option_url": "https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Wmisleading-indentation",
+        "children": [
+            @{
+                "kind": "note",
+                "locations": [
+                    @{
+                        "caret": @{
+			    "display-column": 5,
+			    "byte-column": 5,
+                            "column": 5,
+                            "file": "misleading-indentation.c",
+                            "line": 17
+                        @}
+                    @}
+                ],
+                "escape-source": false,
+                "message": "...this statement, but the latter is @dots{}"
+            @}
+        ]
+	"escape-source": false,
+	"column-origin": 1,
+    @}
+]
+@end smallexample
+
+@noindent
+where the @code{note} is a child of the @code{warning}.
+
+A diagnostic has a @code{kind}.  If this is @code{warning}, then there is
+an @code{option} key describing the command-line option controlling the
+warning.
+
+A diagnostic can contain zero or more locations.  Each location has an
+optional @code{label} string and up to three positions within it: a
+@code{caret} position and optional @code{start} and @code{finish} positions.
+A position is described by a @code{file} name, a @code{line} number, and
+three numbers indicating a column position:
+@itemize @bullet
+
+@item
+@code{display-column} counts display columns, accounting for tabs and
+multibyte characters.
+
+@item
+@code{byte-column} counts raw bytes.
+
+@item
+@code{column} is equal to one of
+the previous two, as dictated by the @option{-fdiagnostics-column-unit}
+option.
+
+@end itemize
+All three columns are relative to the origin specified by
+@option{-fdiagnostics-column-origin}, which is typically equal to 1 but may
+be set, for instance, to 0 for compatibility with other utilities that
+number columns from 0.  The column origin is recorded in the JSON output in
+the @code{column-origin} tag.  In the remaining examples below, the extra
+column number outputs have been omitted for brevity.
+
+For example, this error:
+
+@smallexample
+bad-binary-ops.c:64:23: error: invalid operands to binary + (have 'S' @{aka
+   'struct s'@} and 'T' @{aka 'struct t'@})
+   64 |   return callee_4a () + callee_4b ();
+      |          ~~~~~~~~~~~~ ^ ~~~~~~~~~~~~
+      |          |              |
+      |          |              T @{aka struct t@}
+      |          S @{aka struct s@}
+@end smallexample
+
+@noindent
+has three locations.  Its primary location is at the ``+'' token at column
+23.  It has two secondary locations, describing the left and right-hand sides
+of the expression, which have labels.  It might be printed in JSON form as:
+
+@smallexample
+    @{
+        "children": [],
+        "kind": "error",
+        "locations": [
+            @{
+                "caret": @{
+                    "column": 23, "file": "bad-binary-ops.c", "line": 64
+                @}
+            @},
+            @{
+                "caret": @{
+                    "column": 10, "file": "bad-binary-ops.c", "line": 64
+                @},
+                "finish": @{
+                    "column": 21, "file": "bad-binary-ops.c", "line": 64
+                @},
+                "label": "S @{aka struct s@}"
+            @},
+            @{
+                "caret": @{
+                    "column": 25, "file": "bad-binary-ops.c", "line": 64
+                @},
+                "finish": @{
+                    "column": 36, "file": "bad-binary-ops.c", "line": 64
+                @},
+                "label": "T @{aka struct t@}"
+            @}
+        ],
+        "escape-source": false,
+        "message": "invalid operands to binary + @dots{}"
+    @}
+@end smallexample
+
+If a diagnostic contains fix-it hints, it has a @code{fixits} array,
+consisting of half-open intervals, similar to the output of
+@option{-fdiagnostics-parseable-fixits}.  For example, this diagnostic
+with a replacement fix-it hint:
+
+@smallexample
+demo.c:8:15: error: 'struct s' has no member named 'colour'; did you
+  mean 'color'?
+    8 |   return ptr->colour;
+      |               ^~~~~~
+      |               color
+@end smallexample
+
+@noindent
+might be printed in JSON form as:
+
+@smallexample
+    @{
+        "children": [],
+        "fixits": [
+            @{
+                "next": @{
+                    "column": 21,
+                    "file": "demo.c",
+                    "line": 8
+                @},
+                "start": @{
+                    "column": 15,
+                    "file": "demo.c",
+                    "line": 8
+                @},
+                "string": "color"
+            @}
+        ],
+        "kind": "error",
+        "locations": [
+            @{
+                "caret": @{
+                    "column": 15,
+                    "file": "demo.c",
+                    "line": 8
+                @},
+                "finish": @{
+                    "column": 20,
+                    "file": "demo.c",
+                    "line": 8
+                @}
+            @}
+        ],
+        "escape-source": false,
+        "message": "\u2018struct s\u2019 has no member named @dots{}"
+    @}
+@end smallexample
+
+@noindent
+where the fix-it hint suggests replacing the text from @code{start} up
+to but not including @code{next} with @code{string}'s value.  Deletions
+are expressed via an empty value for @code{string}, insertions by
+having @code{start} equal @code{next}.
+
+If the diagnostic has a path of control-flow events associated with it,
+it has a @code{path} array of objects representing the events.  Each
+event object has a @code{description} string, a @code{location} object,
+along with a @code{function} string and a @code{depth} number for
+representing interprocedural paths.  The @code{function} represents the
+current function at that event, and the @code{depth} represents the
+stack depth relative to some baseline: the higher, the more frames are
+within the stack.
+
+For example, the intraprocedural example shown for
+@option{-fdiagnostics-path-format=} might have this JSON for its path:
+
+@smallexample
+    "path": [
+        @{
+            "depth": 0,
+            "description": "when 'PyList_New' fails, returning NULL",
+            "function": "test",
+            "location": @{
+                "column": 10,
+                "file": "test.c",
+                "line": 25
+            @}
+        @},
+        @{
+            "depth": 0,
+            "description": "when 'i < count'",
+            "function": "test",
+            "location": @{
+                "column": 3,
+                "file": "test.c",
+                "line": 27
+            @}
+        @},
+        @{
+            "depth": 0,
+            "description": "when calling 'PyList_Append', passing NULL from (1) as argument 1",
+            "function": "test",
+            "location": @{
+                "column": 5,
+                "file": "test.c",
+                "line": 29
+            @}
+        @}
+    ]
+@end smallexample
+
+Diagnostics have a boolean attribute @code{escape-source}, hinting whether
+non-ASCII bytes should be escaped when printing the pertinent lines of
+source code (@code{true} for diagnostics involving source encoding issues).
+
+@end table
+
+@node Warning Options
+@section Options to Request or Suppress Warnings
+@cindex options to control warnings
+@cindex warning messages
+@cindex messages, warning
+@cindex suppressing warnings
+
+Warnings are diagnostic messages that report constructions that
+are not inherently erroneous but that are risky or suggest there
+may have been an error.
+
+The following language-independent options do not enable specific
+warnings but control the kinds of diagnostics produced by GCC@.
+
+@table @gcctabopt
+@cindex syntax checking
+@item -fsyntax-only
+@opindex fsyntax-only
+Check the code for syntax errors, but don't do anything beyond that.
+
+@item -fmax-errors=@var{n}
+@opindex fmax-errors
+Limits the maximum number of error messages to @var{n}, at which point
+GCC bails out rather than attempting to continue processing the source
+code.  If @var{n} is 0 (the default), there is no limit on the number
+of error messages produced.  If @option{-Wfatal-errors} is also
+specified, then @option{-Wfatal-errors} takes precedence over this
+option.
+
+@item -w
+@opindex w
+Inhibit all warning messages.
+
+@item -Werror
+@opindex Werror
+@opindex Wno-error
+Make all warnings into errors.
+
+@item -Werror=
+@opindex Werror=
+@opindex Wno-error=
+Make the specified warning into an error.  The specifier for a warning
+is appended; for example @option{-Werror=switch} turns the warnings
+controlled by @option{-Wswitch} into errors.  This switch takes a
+negative form, to be used to negate @option{-Werror} for specific
+warnings; for example @option{-Wno-error=switch} makes
+@option{-Wswitch} warnings not be errors, even when @option{-Werror}
+is in effect.
+
+The warning message for each controllable warning includes the
+option that controls the warning.  That option can then be used with
+@option{-Werror=} and @option{-Wno-error=} as described above.
+(Printing of the option in the warning message can be disabled using the
+@option{-fno-diagnostics-show-option} flag.)
+
+Note that specifying @option{-Werror=}@var{foo} automatically implies
+@option{-W}@var{foo}.  However, @option{-Wno-error=}@var{foo} does not
+imply anything.
+
+@item -Wfatal-errors
+@opindex Wfatal-errors
+@opindex Wno-fatal-errors
+This option causes the compiler to abort compilation on the first error
+occurred rather than trying to keep going and printing further error
+messages.
+
+@end table
+
+You can request many specific warnings with options beginning with
+@samp{-W}, for example @option{-Wimplicit} to request warnings on
+implicit declarations.  Each of these specific warning options also
+has a negative form beginning @samp{-Wno-} to turn off warnings; for
+example, @option{-Wno-implicit}.  This manual lists only one of the
+two forms, whichever is not the default.  For further
+language-specific options also refer to @ref{C++ Dialect Options} and
+@ref{Objective-C and Objective-C++ Dialect Options}.
+Additional warnings can be produced by enabling the static analyzer;
+@xref{Static Analyzer Options}.
+
+Some options, such as @option{-Wall} and @option{-Wextra}, turn on other
+options, such as @option{-Wunused}, which may turn on further options,
+such as @option{-Wunused-value}. The combined effect of positive and
+negative forms is that more specific options have priority over less
+specific ones, independently of their position in the command-line. For
+options of the same specificity, the last one takes effect. Options
+enabled or disabled via pragmas (@pxref{Diagnostic Pragmas}) take effect
+as if they appeared at the end of the command-line.
+
+When an unrecognized warning option is requested (e.g.,
+@option{-Wunknown-warning}), GCC emits a diagnostic stating
+that the option is not recognized.  However, if the @option{-Wno-} form
+is used, the behavior is slightly different: no diagnostic is
+produced for @option{-Wno-unknown-warning} unless other diagnostics
+are being produced.  This allows the use of new @option{-Wno-} options
+with old compilers, but if something goes wrong, the compiler
+warns that an unrecognized option is present.
+
+The effectiveness of some warnings depends on optimizations also being
+enabled. For example @option{-Wsuggest-final-types} is more effective
+with link-time optimization and some instances of other warnings may
+not be issued at all unless optimization is enabled.  While optimization
+in general improves the efficacy of control and data flow sensitive
+warnings, in some cases it may also cause false positives.
+
+@table @gcctabopt
+@item -Wpedantic
+@itemx -pedantic
+@opindex pedantic
+@opindex Wpedantic
+@opindex Wno-pedantic
+Issue all the warnings demanded by strict ISO C and ISO C++;
+reject all programs that use forbidden extensions, and some other
+programs that do not follow ISO C and ISO C++.  For ISO C, follows the
+version of the ISO C standard specified by any @option{-std} option used.
+
+Valid ISO C and ISO C++ programs should compile properly with or without
+this option (though a rare few require @option{-ansi} or a
+@option{-std} option specifying the required version of ISO C)@.  However,
+without this option, certain GNU extensions and traditional C and C++
+features are supported as well.  With this option, they are rejected.
+
+@option{-Wpedantic} does not cause warning messages for use of the
+alternate keywords whose names begin and end with @samp{__}.  This alternate
+format can also be used to disable warnings for non-ISO @samp{__intN} types,
+i.e. @samp{__intN__}.
+Pedantic warnings are also disabled in the expression that follows
+@code{__extension__}.  However, only system header files should use
+these escape routes; application programs should avoid them.
+@xref{Alternate Keywords}.
+
+Some users try to use @option{-Wpedantic} to check programs for strict ISO
+C conformance.  They soon find that it does not do quite what they want:
+it finds some non-ISO practices, but not all---only those for which
+ISO C @emph{requires} a diagnostic, and some others for which
+diagnostics have been added.
+
+A feature to report any failure to conform to ISO C might be useful in
+some instances, but would require considerable additional work and would
+be quite different from @option{-Wpedantic}.  We don't have plans to
+support such a feature in the near future.
+
+Where the standard specified with @option{-std} represents a GNU
+extended dialect of C, such as @samp{gnu90} or @samp{gnu99}, there is a
+corresponding @dfn{base standard}, the version of ISO C on which the GNU
+extended dialect is based.  Warnings from @option{-Wpedantic} are given
+where they are required by the base standard.  (It does not make sense
+for such warnings to be given only for features not in the specified GNU
+C dialect, since by definition the GNU dialects of C include all
+features the compiler supports with the given option, and there would be
+nothing to warn about.)
+
+@item -pedantic-errors
+@opindex pedantic-errors
+Give an error whenever the @dfn{base standard} (see @option{-Wpedantic})
+requires a diagnostic, in some cases where there is undefined behavior
+at compile-time and in some other cases that do not prevent compilation
+of programs that are valid according to the standard. This is not
+equivalent to @option{-Werror=pedantic}, since there are errors enabled
+by this option and not enabled by the latter and vice versa.
+
+@item -Wall
+@opindex Wall
+@opindex Wno-all
+This enables all the warnings about constructions that some users
+consider questionable, and that are easy to avoid (or modify to
+prevent the warning), even in conjunction with macros.  This also
+enables some language-specific warnings described in @ref{C++ Dialect
+Options} and @ref{Objective-C and Objective-C++ Dialect Options}.
+
+@option{-Wall} turns on the following warning flags:
+
+@gccoptlist{-Waddress   @gol
+-Warray-bounds=1 @r{(only with} @option{-O2}@r{)}  @gol
+-Warray-compare @gol
+-Warray-parameter=2 @r{(C and Objective-C only)} @gol
+-Wbool-compare  @gol
+-Wbool-operation  @gol
+-Wc++11-compat  -Wc++14-compat  @gol
+-Wcatch-value @r{(C++ and Objective-C++ only)}  @gol
+-Wchar-subscripts  @gol
+-Wcomment  @gol
+-Wdangling-pointer=2  @gol
+-Wduplicate-decl-specifier @r{(C and Objective-C only)} @gol
+-Wenum-compare @r{(in C/ObjC; this is on by default in C++)} @gol
+-Wenum-int-mismatch @r{(C and Objective-C only)} @gol
+-Wformat   @gol
+-Wformat-overflow  @gol
+-Wformat-truncation  @gol
+-Wint-in-bool-context  @gol
+-Wimplicit @r{(C and Objective-C only)} @gol
+-Wimplicit-int @r{(C and Objective-C only)} @gol
+-Wimplicit-function-declaration @r{(C and Objective-C only)} @gol
+-Winit-self @r{(only for C++)} @gol
+-Wlogical-not-parentheses @gol
+-Wmain @r{(only for C/ObjC and unless} @option{-ffreestanding}@r{)}  @gol
+-Wmaybe-uninitialized @gol
+-Wmemset-elt-size @gol
+-Wmemset-transposed-args @gol
+-Wmisleading-indentation @r{(only for C/C++)} @gol
+-Wmismatched-dealloc @gol
+-Wmismatched-new-delete @r{(only for C/C++)} @gol
+-Wmissing-attributes @gol
+-Wmissing-braces @r{(only for C/ObjC)} @gol
+-Wmultistatement-macros  @gol
+-Wnarrowing @r{(only for C++)}  @gol
+-Wnonnull  @gol
+-Wnonnull-compare  @gol
+-Wopenmp-simd @gol
+-Wparentheses  @gol
+-Wpessimizing-move @r{(only for C++)}  @gol
+-Wpointer-sign  @gol
+-Wrange-loop-construct @r{(only for C++)}  @gol
+-Wreorder   @gol
+-Wrestrict   @gol
+-Wreturn-type  @gol
+-Wself-move @r{(only for C++)}  @gol
+-Wsequence-point  @gol
+-Wsign-compare @r{(only in C++)}  @gol
+-Wsizeof-array-div @gol
+-Wsizeof-pointer-div @gol
+-Wsizeof-pointer-memaccess @gol
+-Wstrict-aliasing  @gol
+-Wstrict-overflow=1  @gol
+-Wswitch  @gol
+-Wtautological-compare  @gol
+-Wtrigraphs  @gol
+-Wuninitialized  @gol
+-Wunknown-pragmas  @gol
+-Wunused-function  @gol
+-Wunused-label     @gol
+-Wunused-value     @gol
+-Wunused-variable  @gol
+-Wuse-after-free=3  @gol
+-Wvla-parameter @r{(C and Objective-C only)} @gol
+-Wvolatile-register-var  @gol
+-Wzero-length-bounds}
+
+Note that some warning flags are not implied by @option{-Wall}.  Some of
+them warn about constructions that users generally do not consider
+questionable, but which occasionally you might wish to check for;
+others warn about constructions that are necessary or hard to avoid in
+some cases, and there is no simple way to modify the code to suppress
+the warning. Some of them are enabled by @option{-Wextra} but many of
+them must be enabled individually.
+
+@item -Wextra
+@opindex W
+@opindex Wextra
+@opindex Wno-extra
+This enables some extra warning flags that are not enabled by
+@option{-Wall}. (This option used to be called @option{-W}.  The older
+name is still supported, but the newer name is more descriptive.)
+
+@gccoptlist{-Wclobbered  @gol
+-Wcast-function-type  @gol
+-Wdeprecated-copy @r{(C++ only)} @gol
+-Wempty-body  @gol
+-Wenum-conversion @r{(C only)} @gol
+-Wignored-qualifiers @gol
+-Wimplicit-fallthrough=3 @gol
+-Wmissing-field-initializers  @gol
+-Wmissing-parameter-type @r{(C only)}  @gol
+-Wold-style-declaration @r{(C only)}  @gol
+-Woverride-init  @gol
+-Wsign-compare @r{(C only)} @gol
+-Wstring-compare @gol
+-Wredundant-move @r{(only for C++)}  @gol
+-Wtype-limits  @gol
+-Wuninitialized  @gol
+-Wshift-negative-value @r{(in C++11 to C++17 and in C99 and newer)}  @gol
+-Wunused-parameter @r{(only with} @option{-Wunused} @r{or} @option{-Wall}@r{)} @gol
+-Wunused-but-set-parameter @r{(only with} @option{-Wunused} @r{or} @option{-Wall}@r{)}}
+
+
+The option @option{-Wextra} also prints warning messages for the
+following cases:
+
+@itemize @bullet
+
+@item
+A pointer is compared against integer zero with @code{<}, @code{<=},
+@code{>}, or @code{>=}.
+
+@item
+(C++ only) An enumerator and a non-enumerator both appear in a
+conditional expression.
+
+@item
+(C++ only) Ambiguous virtual bases.
+
+@item
+(C++ only) Subscripting an array that has been declared @code{register}.
+
+@item
+(C++ only) Taking the address of a variable that has been declared
+@code{register}.
+
+@item
+(C++ only) A base class is not initialized in the copy constructor
+of a derived class.
+
+@end itemize
+
+@item -Wabi @r{(C, Objective-C, C++ and Objective-C++ only)}
+@opindex Wabi
+@opindex Wno-abi
+
+Warn about code affected by ABI changes.  This includes code that may
+not be compatible with the vendor-neutral C++ ABI as well as the psABI
+for the particular target.
+
+Since G++ now defaults to updating the ABI with each major release,
+normally @option{-Wabi} warns only about C++ ABI compatibility
+problems if there is a check added later in a release series for an
+ABI issue discovered since the initial release.  @option{-Wabi} warns
+about more things if an older ABI version is selected (with
+@option{-fabi-version=@var{n}}).
+
+@option{-Wabi} can also be used with an explicit version number to
+warn about C++ ABI compatibility with a particular @option{-fabi-version}
+level, e.g.@: @option{-Wabi=2} to warn about changes relative to
+@option{-fabi-version=2}.
+
+If an explicit version number is provided and
+@option{-fabi-compat-version} is not specified, the version number
+from this option is used for compatibility aliases.  If no explicit
+version number is provided with this option, but
+@option{-fabi-compat-version} is specified, that version number is
+used for C++ ABI warnings.
+
+Although an effort has been made to warn about
+all such cases, there are probably some cases that are not warned about,
+even though G++ is generating incompatible code.  There may also be
+cases where warnings are emitted even though the code that is generated
+is compatible.
+
+You should rewrite your code to avoid these warnings if you are
+concerned about the fact that code generated by G++ may not be binary
+compatible with code generated by other compilers.
+
+Known incompatibilities in @option{-fabi-version=2} (which was the
+default from GCC 3.4 to 4.9) include:
+
+@itemize @bullet
+
+@item
+A template with a non-type template parameter of reference type was
+mangled incorrectly:
+@smallexample
+extern int N;
+template <int &> struct S @{@};
+void n (S<N>) @{2@}
+@end smallexample
+
+This was fixed in @option{-fabi-version=3}.
+
+@item
+SIMD vector types declared using @code{__attribute ((vector_size))} were
+mangled in a non-standard way that does not allow for overloading of
+functions taking vectors of different sizes.
+
+The mangling was changed in @option{-fabi-version=4}.
+
+@item
+@code{__attribute ((const))} and @code{noreturn} were mangled as type
+qualifiers, and @code{decltype} of a plain declaration was folded away.
+
+These mangling issues were fixed in @option{-fabi-version=5}.
+
+@item
+Scoped enumerators passed as arguments to a variadic function are
+promoted like unscoped enumerators, causing @code{va_arg} to complain.
+On most targets this does not actually affect the parameter passing
+ABI, as there is no way to pass an argument smaller than @code{int}.
+
+Also, the ABI changed the mangling of template argument packs,
+@code{const_cast}, @code{static_cast}, prefix increment/decrement, and
+a class scope function used as a template argument.
+
+These issues were corrected in @option{-fabi-version=6}.
+
+@item
+Lambdas in default argument scope were mangled incorrectly, and the
+ABI changed the mangling of @code{nullptr_t}.
+
+These issues were corrected in @option{-fabi-version=7}.
+
+@item
+When mangling a function type with function-cv-qualifiers, the
+un-qualified function type was incorrectly treated as a substitution
+candidate.
+
+This was fixed in @option{-fabi-version=8}, the default for GCC 5.1.
+
+@item
+@code{decltype(nullptr)} incorrectly had an alignment of 1, leading to
+unaligned accesses.  Note that this did not affect the ABI of a
+function with a @code{nullptr_t} parameter, as parameters have a
+minimum alignment.
+
+This was fixed in @option{-fabi-version=9}, the default for GCC 5.2.
+
+@item
+Target-specific attributes that affect the identity of a type, such as
+ia32 calling conventions on a function type (stdcall, regparm, etc.),
+did not affect the mangled name, leading to name collisions when
+function pointers were used as template arguments.
+
+This was fixed in @option{-fabi-version=10}, the default for GCC 6.1.
+
+@end itemize
+
+This option also enables warnings about psABI-related changes.
+The known psABI changes at this point include:
+
+@itemize @bullet
+
+@item
+For SysV/x86-64, unions with @code{long double} members are
+passed in memory as specified in psABI.  Prior to GCC 4.4, this was not
+the case.  For example:
+
+@smallexample
+union U @{
+  long double ld;
+  int i;
+@};
+@end smallexample
+
+@noindent
+@code{union U} is now always passed in memory.
+
+@end itemize
+
+@item -Wchar-subscripts
+@opindex Wchar-subscripts
+@opindex Wno-char-subscripts
+Warn if an array subscript has type @code{char}.  This is a common cause
+of error, as programmers often forget that this type is signed on some
+machines.
+This warning is enabled by @option{-Wall}.
+
+@item -Wno-coverage-mismatch
+@opindex Wno-coverage-mismatch
+@opindex Wcoverage-mismatch
+Warn if feedback profiles do not match when using the
+@option{-fprofile-use} option.
+If a source file is changed between compiling with @option{-fprofile-generate}
+and with @option{-fprofile-use}, the files with the profile feedback can fail
+to match the source file and GCC cannot use the profile feedback
+information.  By default, this warning is enabled and is treated as an
+error.  @option{-Wno-coverage-mismatch} can be used to disable the
+warning or @option{-Wno-error=coverage-mismatch} can be used to
+disable the error.  Disabling the error for this warning can result in
+poorly optimized code and is useful only in the
+case of very minor changes such as bug fixes to an existing code-base.
+Completely disabling the warning is not recommended.
+
+@item -Wno-coverage-invalid-line-number
+@opindex Wno-coverage-invalid-line-number
+@opindex Wcoverage-invalid-line-number
+Warn in case a function ends earlier than it begins due
+to an invalid linenum macros.  The warning is emitted only
+with @option{--coverage} enabled.
+
+By default, this warning is enabled and is treated as an
+error.  @option{-Wno-coverage-invalid-line-number} can be used to disable the
+warning or @option{-Wno-error=coverage-invalid-line-number} can be used to
+disable the error.
+
+@item -Wno-cpp @r{(C, Objective-C, C++, Objective-C++ and Fortran only)}
+@opindex Wno-cpp
+@opindex Wcpp
+Suppress warning messages emitted by @code{#warning} directives.
+
+@item -Wdouble-promotion @r{(C, C++, Objective-C and Objective-C++ only)}
+@opindex Wdouble-promotion
+@opindex Wno-double-promotion
+Give a warning when a value of type @code{float} is implicitly
+promoted to @code{double}.  CPUs with a 32-bit ``single-precision''
+floating-point unit implement @code{float} in hardware, but emulate
+@code{double} in software.  On such a machine, doing computations
+using @code{double} values is much more expensive because of the
+overhead required for software emulation.
+
+It is easy to accidentally do computations with @code{double} because
+floating-point literals are implicitly of type @code{double}.  For
+example, in:
+@smallexample
+@group
+float area(float radius)
+@{
+   return 3.14159 * radius * radius;
+@}
+@end group
+@end smallexample
+the compiler performs the entire computation with @code{double}
+because the floating-point literal is a @code{double}.
+
+@item -Wduplicate-decl-specifier @r{(C and Objective-C only)}
+@opindex Wduplicate-decl-specifier
+@opindex Wno-duplicate-decl-specifier
+Warn if a declaration has duplicate @code{const}, @code{volatile},
+@code{restrict} or @code{_Atomic} specifier.  This warning is enabled by
+@option{-Wall}.
+
+@item -Wformat
+@itemx -Wformat=@var{n}
+@opindex Wformat
+@opindex Wno-format
+@opindex ffreestanding
+@opindex fno-builtin
+@opindex Wformat=
+Check calls to @code{printf} and @code{scanf}, etc., to make sure that
+the arguments supplied have types appropriate to the format string
+specified, and that the conversions specified in the format string make
+sense.  This includes standard functions, and others specified by format
+attributes (@pxref{Function Attributes}), in the @code{printf},
+@code{scanf}, @code{strftime} and @code{strfmon} (an X/Open extension,
+not in the C standard) families (or other target-specific families).
+Which functions are checked without format attributes having been
+specified depends on the standard version selected, and such checks of
+functions without the attribute specified are disabled by
+@option{-ffreestanding} or @option{-fno-builtin}.
+
+The formats are checked against the format features supported by GNU
+libc version 2.2.  These include all ISO C90 and C99 features, as well
+as features from the Single Unix Specification and some BSD and GNU
+extensions.  Other library implementations may not support all these
+features; GCC does not support warning about features that go beyond a
+particular library's limitations.  However, if @option{-Wpedantic} is used
+with @option{-Wformat}, warnings are given about format features not
+in the selected standard version (but not for @code{strfmon} formats,
+since those are not in any version of the C standard).  @xref{C Dialect
+Options,,Options Controlling C Dialect}.
+
+@table @gcctabopt
+@item -Wformat=1
+@itemx -Wformat
+@opindex Wformat
+@opindex Wformat=1
+Option @option{-Wformat} is equivalent to @option{-Wformat=1}, and
+@option{-Wno-format} is equivalent to @option{-Wformat=0}.  Since
+@option{-Wformat} also checks for null format arguments for several
+functions, @option{-Wformat} also implies @option{-Wnonnull}.  Some
+aspects of this level of format checking can be disabled by the
+options: @option{-Wno-format-contains-nul},
+@option{-Wno-format-extra-args}, and @option{-Wno-format-zero-length}.
+@option{-Wformat} is enabled by @option{-Wall}.
+
+@item -Wformat=2
+@opindex Wformat=2
+Enable @option{-Wformat} plus additional format checks.  Currently
+equivalent to @option{-Wformat -Wformat-nonliteral -Wformat-security
+-Wformat-y2k}.
+@end table
+
+@item -Wno-format-contains-nul
+@opindex Wno-format-contains-nul
+@opindex Wformat-contains-nul
+If @option{-Wformat} is specified, do not warn about format strings that
+contain NUL bytes.
+
+@item -Wno-format-extra-args
+@opindex Wno-format-extra-args
+@opindex Wformat-extra-args
+If @option{-Wformat} is specified, do not warn about excess arguments to a
+@code{printf} or @code{scanf} format function.  The C standard specifies
+that such arguments are ignored.
+
+Where the unused arguments lie between used arguments that are
+specified with @samp{$} operand number specifications, normally
+warnings are still given, since the implementation could not know what
+type to pass to @code{va_arg} to skip the unused arguments.  However,
+in the case of @code{scanf} formats, this option suppresses the
+warning if the unused arguments are all pointers, since the Single
+Unix Specification says that such unused arguments are allowed.
+
+@item -Wformat-overflow
+@itemx -Wformat-overflow=@var{level}
+@opindex Wformat-overflow
+@opindex Wno-format-overflow
+Warn about calls to formatted input/output functions such as @code{sprintf}
+and @code{vsprintf} that might overflow the destination buffer.  When the
+exact number of bytes written by a format directive cannot be determined
+at compile-time it is estimated based on heuristics that depend on the
+@var{level} argument and on optimization.  While enabling optimization
+will in most cases improve the accuracy of the warning, it may also
+result in false positives.
+
+@table @gcctabopt
+@item -Wformat-overflow
+@itemx -Wformat-overflow=1
+@opindex Wformat-overflow
+@opindex Wno-format-overflow
+Level @var{1} of @option{-Wformat-overflow} enabled by @option{-Wformat}
+employs a conservative approach that warns only about calls that most
+likely overflow the buffer.  At this level, numeric arguments to format
+directives with unknown values are assumed to have the value of one, and
+strings of unknown length to be empty.  Numeric arguments that are known
+to be bounded to a subrange of their type, or string arguments whose output
+is bounded either by their directive's precision or by a finite set of
+string literals, are assumed to take on the value within the range that
+results in the most bytes on output.  For example, the call to @code{sprintf}
+below is diagnosed because even with both @var{a} and @var{b} equal to zero,
+the terminating NUL character (@code{'\0'}) appended by the function
+to the destination buffer will be written past its end.  Increasing
+the size of the buffer by a single byte is sufficient to avoid the
+warning, though it may not be sufficient to avoid the overflow.
+
+@smallexample
+void f (int a, int b)
+@{
+  char buf [13];
+  sprintf (buf, "a = %i, b = %i\n", a, b);
+@}
+@end smallexample
+
+@item -Wformat-overflow=2
+Level @var{2} warns also about calls that might overflow the destination
+buffer given an argument of sufficient length or magnitude.  At level
+@var{2}, unknown numeric arguments are assumed to have the minimum
+representable value for signed types with a precision greater than 1, and
+the maximum representable value otherwise.  Unknown string arguments whose
+length cannot be assumed to be bounded either by the directive's precision,
+or by a finite set of string literals they may evaluate to, or the character
+array they may point to, are assumed to be 1 character long.
+
+At level @var{2}, the call in the example above is again diagnosed, but
+this time because with @var{a} equal to a 32-bit @code{INT_MIN} the first
+@code{%i} directive will write some of its digits beyond the end of
+the destination buffer.  To make the call safe regardless of the values
+of the two variables, the size of the destination buffer must be increased
+to at least 34 bytes.  GCC includes the minimum size of the buffer in
+an informational note following the warning.
+
+An alternative to increasing the size of the destination buffer is to
+constrain the range of formatted values.  The maximum length of string
+arguments can be bounded by specifying the precision in the format
+directive.  When numeric arguments of format directives can be assumed
+to be bounded by less than the precision of their type, choosing
+an appropriate length modifier to the format specifier will reduce
+the required buffer size.  For example, if @var{a} and @var{b} in the
+example above can be assumed to be within the precision of
+the @code{short int} type then using either the @code{%hi} format
+directive or casting the argument to @code{short} reduces the maximum
+required size of the buffer to 24 bytes.
+
+@smallexample
+void f (int a, int b)
+@{
+  char buf [23];
+  sprintf (buf, "a = %hi, b = %i\n", a, (short)b);
+@}
+@end smallexample
+@end table
+
+@item -Wno-format-zero-length
+@opindex Wno-format-zero-length
+@opindex Wformat-zero-length
+If @option{-Wformat} is specified, do not warn about zero-length formats.
+The C standard specifies that zero-length formats are allowed.
+
+@item -Wformat-nonliteral
+@opindex Wformat-nonliteral
+@opindex Wno-format-nonliteral
+If @option{-Wformat} is specified, also warn if the format string is not a
+string literal and so cannot be checked, unless the format function
+takes its format arguments as a @code{va_list}.
+
+@item -Wformat-security
+@opindex Wformat-security
+@opindex Wno-format-security
+If @option{-Wformat} is specified, also warn about uses of format
+functions that represent possible security problems.  At present, this
+warns about calls to @code{printf} and @code{scanf} functions where the
+format string is not a string literal and there are no format arguments,
+as in @code{printf (foo);}.  This may be a security hole if the format
+string came from untrusted input and contains @samp{%n}.  (This is
+currently a subset of what @option{-Wformat-nonliteral} warns about, but
+in future warnings may be added to @option{-Wformat-security} that are not
+included in @option{-Wformat-nonliteral}.)
+
+@item -Wformat-signedness
+@opindex Wformat-signedness
+@opindex Wno-format-signedness
+If @option{-Wformat} is specified, also warn if the format string
+requires an unsigned argument and the argument is signed and vice versa.
+
+@item -Wformat-truncation
+@itemx -Wformat-truncation=@var{level}
+@opindex Wformat-truncation
+@opindex Wno-format-truncation
+Warn about calls to formatted input/output functions such as @code{snprintf}
+and @code{vsnprintf} that might result in output truncation.  When the exact
+number of bytes written by a format directive cannot be determined at
+compile-time it is estimated based on heuristics that depend on
+the @var{level} argument and on optimization.  While enabling optimization
+will in most cases improve the accuracy of the warning, it may also result
+in false positives.  Except as noted otherwise, the option uses the same
+logic @option{-Wformat-overflow}.
+
+@table @gcctabopt
+@item -Wformat-truncation
+@itemx -Wformat-truncation=1
+@opindex Wformat-truncation
+@opindex Wno-format-truncation
+Level @var{1} of @option{-Wformat-truncation} enabled by @option{-Wformat}
+employs a conservative approach that warns only about calls to bounded
+functions whose return value is unused and that will most likely result
+in output truncation.
+
+@item -Wformat-truncation=2
+Level @var{2} warns also about calls to bounded functions whose return
+value is used and that might result in truncation given an argument of
+sufficient length or magnitude.
+@end table
+
+@item -Wformat-y2k
+@opindex Wformat-y2k
+@opindex Wno-format-y2k
+If @option{-Wformat} is specified, also warn about @code{strftime}
+formats that may yield only a two-digit year.
+
+@item -Wnonnull
+@opindex Wnonnull
+@opindex Wno-nonnull
+Warn about passing a null pointer for arguments marked as
+requiring a non-null value by the @code{nonnull} function attribute.
+
+@option{-Wnonnull} is included in @option{-Wall} and @option{-Wformat}.  It
+can be disabled with the @option{-Wno-nonnull} option.
+
+@item -Wnonnull-compare
+@opindex Wnonnull-compare
+@opindex Wno-nonnull-compare
+Warn when comparing an argument marked with the @code{nonnull}
+function attribute against null inside the function.
+
+@option{-Wnonnull-compare} is included in @option{-Wall}.  It
+can be disabled with the @option{-Wno-nonnull-compare} option.
+
+@item -Wnull-dereference
+@opindex Wnull-dereference
+@opindex Wno-null-dereference
+Warn if the compiler detects paths that trigger erroneous or
+undefined behavior due to dereferencing a null pointer.  This option
+is only active when @option{-fdelete-null-pointer-checks} is active,
+which is enabled by optimizations in most targets.  The precision of
+the warnings depends on the optimization options used.
+
+@item -Winfinite-recursion
+@opindex Winfinite-recursion
+@opindex Wno-infinite-recursion
+Warn about infinitely recursive calls.  The warning is effective at all
+optimization levels but requires optimization in order to detect infinite
+recursion in calls between two or more functions.
+@option{-Winfinite-recursion} is included in @option{-Wall}.
+
+@item -Winit-self @r{(C, C++, Objective-C and Objective-C++ only)}
+@opindex Winit-self
+@opindex Wno-init-self
+Warn about uninitialized variables that are initialized with themselves.
+Note this option can only be used with the @option{-Wuninitialized} option.
+
+For example, GCC warns about @code{i} being uninitialized in the
+following snippet only when @option{-Winit-self} has been specified:
+@smallexample
+@group
+int f()
+@{
+  int i = i;
+  return i;
+@}
+@end group
+@end smallexample
+
+This warning is enabled by @option{-Wall} in C++.
+
+@item -Wno-implicit-int @r{(C and Objective-C only)}
+@opindex Wimplicit-int
+@opindex Wno-implicit-int
+This option controls warnings when a declaration does not specify a type.
+This warning is enabled by default in C99 and later dialects of C,
+and also by @option{-Wall}.
+
+@item -Wno-implicit-function-declaration @r{(C and Objective-C only)}
+@opindex Wimplicit-function-declaration
+@opindex Wno-implicit-function-declaration
+This option controls warnings when a function is used before being declared.
+This warning is enabled by default in C99 and later dialects of C,
+and also by @option{-Wall}.
+The warning is made into an error by @option{-pedantic-errors}.
+
+@item -Wimplicit @r{(C and Objective-C only)}
+@opindex Wimplicit
+@opindex Wno-implicit
+Same as @option{-Wimplicit-int} and @option{-Wimplicit-function-declaration}.
+This warning is enabled by @option{-Wall}.
+
+@item -Wimplicit-fallthrough
+@opindex Wimplicit-fallthrough
+@opindex Wno-implicit-fallthrough
+@option{-Wimplicit-fallthrough} is the same as @option{-Wimplicit-fallthrough=3}
+and @option{-Wno-implicit-fallthrough} is the same as
+@option{-Wimplicit-fallthrough=0}.
+
+@item -Wimplicit-fallthrough=@var{n}
+@opindex Wimplicit-fallthrough=
+Warn when a switch case falls through.  For example:
+
+@smallexample
+@group
+switch (cond)
+  @{
+  case 1:
+    a = 1;
+    break;
+  case 2:
+    a = 2;
+  case 3:
+    a = 3;
+    break;
+  @}
+@end group
+@end smallexample
+
+This warning does not warn when the last statement of a case cannot
+fall through, e.g. when there is a return statement or a call to function
+declared with the noreturn attribute.  @option{-Wimplicit-fallthrough=}
+also takes into account control flow statements, such as ifs, and only
+warns when appropriate.  E.g.@:
+
+@smallexample
+@group
+switch (cond)
+  @{
+  case 1:
+    if (i > 3) @{
+      bar (5);
+      break;
+    @} else if (i < 1) @{
+      bar (0);
+    @} else
+      return;
+  default:
+    @dots{}
+  @}
+@end group
+@end smallexample
+
+Since there are occasions where a switch case fall through is desirable,
+GCC provides an attribute, @code{__attribute__ ((fallthrough))}, that is
+to be used along with a null statement to suppress this warning that
+would normally occur:
+
+@smallexample
+@group
+switch (cond)
+  @{
+  case 1:
+    bar (0);
+    __attribute__ ((fallthrough));
+  default:
+    @dots{}
+  @}
+@end group
+@end smallexample
+
+C++17 provides a standard way to suppress the @option{-Wimplicit-fallthrough}
+warning using @code{[[fallthrough]];} instead of the GNU attribute.  In C++11
+or C++14 users can use @code{[[gnu::fallthrough]];}, which is a GNU extension.
+Instead of these attributes, it is also possible to add a fallthrough comment
+to silence the warning.  The whole body of the C or C++ style comment should
+match the given regular expressions listed below.  The option argument @var{n}
+specifies what kind of comments are accepted:
+
+@itemize @bullet
+
+@item @option{-Wimplicit-fallthrough=0} disables the warning altogether.
+
+@item @option{-Wimplicit-fallthrough=1} matches @code{.*} regular
+expression, any comment is used as fallthrough comment.
+
+@item @option{-Wimplicit-fallthrough=2} case insensitively matches
+@code{.*falls?[ \t-]*thr(ough|u).*} regular expression.
+
+@item @option{-Wimplicit-fallthrough=3} case sensitively matches one of the
+following regular expressions:
+
+@itemize @bullet
+
+@item @code{-fallthrough}
+
+@item @code{@@fallthrough@@}
+
+@item @code{lint -fallthrough[ \t]*}
+
+@item @code{[ \t.!]*(ELSE,? |INTENTIONAL(LY)? )?@*FALL(S | |-)?THR(OUGH|U)[ \t.!]*(-[^\n\r]*)?}
+
+@item @code{[ \t.!]*(Else,? |Intentional(ly)? )?@*Fall((s | |-)[Tt]|t)hr(ough|u)[ \t.!]*(-[^\n\r]*)?}
+
+@item @code{[ \t.!]*([Ee]lse,? |[Ii]ntentional(ly)? )?@*fall(s | |-)?thr(ough|u)[ \t.!]*(-[^\n\r]*)?}
+
+@end itemize
+
+@item @option{-Wimplicit-fallthrough=4} case sensitively matches one of the
+following regular expressions:
+
+@itemize @bullet
+
+@item @code{-fallthrough}
+
+@item @code{@@fallthrough@@}
+
+@item @code{lint -fallthrough[ \t]*}
+
+@item @code{[ \t]*FALLTHR(OUGH|U)[ \t]*}
+
+@end itemize
+
+@item @option{-Wimplicit-fallthrough=5} doesn't recognize any comments as
+fallthrough comments, only attributes disable the warning.
+
+@end itemize
+
+The comment needs to be followed after optional whitespace and other comments
+by @code{case} or @code{default} keywords or by a user label that precedes some
+@code{case} or @code{default} label.
+
+@smallexample
+@group
+switch (cond)
+  @{
+  case 1:
+    bar (0);
+    /* FALLTHRU */
+  default:
+    @dots{}
+  @}
+@end group
+@end smallexample
+
+The @option{-Wimplicit-fallthrough=3} warning is enabled by @option{-Wextra}.
+
+@item -Wno-if-not-aligned @r{(C, C++, Objective-C and Objective-C++ only)}
+@opindex Wif-not-aligned
+@opindex Wno-if-not-aligned
+Control if warnings triggered by the @code{warn_if_not_aligned} attribute
+should be issued.  These warnings are enabled by default.
+
+@item -Wignored-qualifiers @r{(C and C++ only)}
+@opindex Wignored-qualifiers
+@opindex Wno-ignored-qualifiers
+Warn if the return type of a function has a type qualifier
+such as @code{const}.  For ISO C such a type qualifier has no effect,
+since the value returned by a function is not an lvalue.
+For C++, the warning is only emitted for scalar types or @code{void}.
+ISO C prohibits qualified @code{void} return types on function
+definitions, so such return types always receive a warning
+even without this option.
+
+This warning is also enabled by @option{-Wextra}.
+
+@item -Wno-ignored-attributes @r{(C and C++ only)}
+@opindex Wignored-attributes
+@opindex Wno-ignored-attributes
+This option controls warnings when an attribute is ignored.
+This is different from the
+@option{-Wattributes} option in that it warns whenever the compiler decides
+to drop an attribute, not that the attribute is either unknown, used in a
+wrong place, etc.  This warning is enabled by default.
+
+@item -Wmain
+@opindex Wmain
+@opindex Wno-main
+Warn if the type of @code{main} is suspicious.  @code{main} should be
+a function with external linkage, returning int, taking either zero
+arguments, two, or three arguments of appropriate types.  This warning
+is enabled by default in C++ and is enabled by either @option{-Wall}
+or @option{-Wpedantic}.
+
+@item -Wmisleading-indentation @r{(C and C++ only)}
+@opindex Wmisleading-indentation
+@opindex Wno-misleading-indentation
+Warn when the indentation of the code does not reflect the block structure.
+Specifically, a warning is issued for @code{if}, @code{else}, @code{while}, and
+@code{for} clauses with a guarded statement that does not use braces,
+followed by an unguarded statement with the same indentation.
+
+In the following example, the call to ``bar'' is misleadingly indented as
+if it were guarded by the ``if'' conditional.
+
+@smallexample
+  if (some_condition ())
+    foo ();
+    bar ();  /* Gotcha: this is not guarded by the "if".  */
+@end smallexample
+
+In the case of mixed tabs and spaces, the warning uses the
+@option{-ftabstop=} option to determine if the statements line up
+(defaulting to 8).
+
+The warning is not issued for code involving multiline preprocessor logic
+such as the following example.
+
+@smallexample
+  if (flagA)
+    foo (0);
+#if SOME_CONDITION_THAT_DOES_NOT_HOLD
+  if (flagB)
+#endif
+    foo (1);
+@end smallexample
+
+The warning is not issued after a @code{#line} directive, since this
+typically indicates autogenerated code, and no assumptions can be made
+about the layout of the file that the directive references.
+
+This warning is enabled by @option{-Wall} in C and C++.
+
+@item -Wmissing-attributes
+@opindex Wmissing-attributes
+@opindex Wno-missing-attributes
+Warn when a declaration of a function is missing one or more attributes
+that a related function is declared with and whose absence may adversely
+affect the correctness or efficiency of generated code.  For example,
+the warning is issued for declarations of aliases that use attributes
+to specify less restrictive requirements than those of their targets.
+This typically represents a potential optimization opportunity.
+By contrast, the @option{-Wattribute-alias=2} option controls warnings
+issued when the alias is more restrictive than the target, which could
+lead to incorrect code generation.
+Attributes considered include @code{alloc_align}, @code{alloc_size},
+@code{cold}, @code{const}, @code{hot}, @code{leaf}, @code{malloc},
+@code{nonnull}, @code{noreturn}, @code{nothrow}, @code{pure},
+@code{returns_nonnull}, and @code{returns_twice}.
+
+In C++, the warning is issued when an explicit specialization of a primary
+template declared with attribute @code{alloc_align}, @code{alloc_size},
+@code{assume_aligned}, @code{format}, @code{format_arg}, @code{malloc},
+or @code{nonnull} is declared without it.  Attributes @code{deprecated},
+@code{error}, and @code{warning} suppress the warning.
+(@pxref{Function Attributes}).
+
+You can use the @code{copy} attribute to apply the same
+set of attributes to a declaration as that on another declaration without
+explicitly enumerating the attributes. This attribute can be applied
+to declarations of functions (@pxref{Common Function Attributes}),
+variables (@pxref{Common Variable Attributes}), or types
+(@pxref{Common Type Attributes}).
+
+@option{-Wmissing-attributes} is enabled by @option{-Wall}.
+
+For example, since the declaration of the primary function template
+below makes use of both attribute @code{malloc} and @code{alloc_size}
+the declaration of the explicit specialization of the template is
+diagnosed because it is missing one of the attributes.
+
+@smallexample
+template <class T>
+T* __attribute__ ((malloc, alloc_size (1)))
+allocate (size_t);
+
+template <>
+void* __attribute__ ((malloc))   // missing alloc_size
+allocate<void> (size_t);
+@end smallexample
+
+@item -Wmissing-braces
+@opindex Wmissing-braces
+@opindex Wno-missing-braces
+Warn if an aggregate or union initializer is not fully bracketed.  In
+the following example, the initializer for @code{a} is not fully
+bracketed, but that for @code{b} is fully bracketed.
+
+@smallexample
+int a[2][2] = @{ 0, 1, 2, 3 @};
+int b[2][2] = @{ @{ 0, 1 @}, @{ 2, 3 @} @};
+@end smallexample
+
+This warning is enabled by @option{-Wall}.
+
+@item -Wmissing-include-dirs @r{(C, C++, Objective-C, Objective-C++ and Fortran only)}
+@opindex Wmissing-include-dirs
+@opindex Wno-missing-include-dirs
+Warn if a user-supplied include directory does not exist. This opions is disabled
+by default for C, C++, Objective-C and Objective-C++. For Fortran, it is partially
+enabled by default by warning for -I and -J, only.
+
+@item -Wno-missing-profile
+@opindex Wmissing-profile
+@opindex Wno-missing-profile
+This option controls warnings if feedback profiles are missing when using the
+@option{-fprofile-use} option.
+This option diagnoses those cases where a new function or a new file is added
+between compiling with @option{-fprofile-generate} and with
+@option{-fprofile-use}, without regenerating the profiles.
+In these cases, the profile feedback data files do not contain any
+profile feedback information for
+the newly added function or file respectively.  Also, in the case when profile
+count data (.gcda) files are removed, GCC cannot use any profile feedback
+information.  In all these cases, warnings are issued to inform you that a
+profile generation step is due.
+Ignoring the warning can result in poorly optimized code.
+@option{-Wno-missing-profile} can be used to
+disable the warning, but this is not recommended and should be done only
+when non-existent profile data is justified.
+
+@item -Wmismatched-dealloc
+@opindex Wmismatched-dealloc
+@opindex Wno-mismatched-dealloc
+
+Warn for calls to deallocation functions with pointer arguments returned
+from from allocations functions for which the former isn't a suitable
+deallocator.  A pair of functions can be associated as matching allocators
+and deallocators by use of attribute @code{malloc}.  Unless disabled by
+the @option{-fno-builtin} option the standard functions @code{calloc},
+@code{malloc}, @code{realloc}, and @code{free}, as well as the corresponding
+forms of C++ @code{operator new} and @code{operator delete} are implicitly
+associated as matching allocators and deallocators.  In the following
+example @code{mydealloc} is the deallocator for pointers returned from
+@code{myalloc}.
+
+@smallexample
+void mydealloc (void*);
+
+__attribute__ ((malloc (mydealloc, 1))) void*
+myalloc (size_t);
+
+void f (void)
+@{
+  void *p = myalloc (32);
+  // @dots{}use p@dots{}
+  free (p);   // warning: not a matching deallocator for myalloc
+  mydealloc (p);   // ok
+@}
+@end smallexample
+
+In C++, the related option @option{-Wmismatched-new-delete} diagnoses
+mismatches involving either @code{operator new} or @code{operator delete}.
+
+Option @option{-Wmismatched-dealloc} is included in @option{-Wall}.
+
+@item -Wmultistatement-macros
+@opindex Wmultistatement-macros
+@opindex Wno-multistatement-macros
+Warn about unsafe multiple statement macros that appear to be guarded
+by a clause such as @code{if}, @code{else}, @code{for}, @code{switch}, or
+@code{while}, in which only the first statement is actually guarded after
+the macro is expanded.
+
+For example:
+
+@smallexample
+#define DOIT x++; y++
+if (c)
+  DOIT;
+@end smallexample
+
+will increment @code{y} unconditionally, not just when @code{c} holds.
+The can usually be fixed by wrapping the macro in a do-while loop:
+@smallexample
+#define DOIT do @{ x++; y++; @} while (0)
+if (c)
+  DOIT;
+@end smallexample
+
+This warning is enabled by @option{-Wall} in C and C++.
+
+@item -Wparentheses
+@opindex Wparentheses
+@opindex Wno-parentheses
+Warn if parentheses are omitted in certain contexts, such
+as when there is an assignment in a context where a truth value
+is expected, or when operators are nested whose precedence people
+often get confused about.
+
+Also warn if a comparison like @code{x<=y<=z} appears; this is
+equivalent to @code{(x<=y ? 1 : 0) <= z}, which is a different
+interpretation from that of ordinary mathematical notation.
+
+Also warn for dangerous uses of the GNU extension to
+@code{?:} with omitted middle operand. When the condition
+in the @code{?}: operator is a boolean expression, the omitted value is
+always 1.  Often programmers expect it to be a value computed
+inside the conditional expression instead.
+
+For C++ this also warns for some cases of unnecessary parentheses in
+declarations, which can indicate an attempt at a function call instead
+of a declaration:
+@smallexample
+@{
+  // Declares a local variable called mymutex.
+  std::unique_lock<std::mutex> (mymutex);
+  // User meant std::unique_lock<std::mutex> lock (mymutex);
+@}
+@end smallexample
+
+This warning is enabled by @option{-Wall}.
+
+@item -Wno-self-move @r{(C++ and Objective-C++ only)}
+@opindex Wself-move
+@opindex Wno-self-move
+This warning warns when a value is moved to itself with @code{std::move}.
+Such a @code{std::move} typically has no effect.
+
+@smallexample
+struct T @{
+@dots{}
+@};
+void fn()
+@{
+  T t;
+  @dots{}
+  t = std::move (t);
+@}
+@end smallexample
+
+This warning is enabled by @option{-Wall}.
+
+@item -Wsequence-point
+@opindex Wsequence-point
+@opindex Wno-sequence-point
+Warn about code that may have undefined semantics because of violations
+of sequence point rules in the C and C++ standards.
+
+The C and C++ standards define the order in which expressions in a C/C++
+program are evaluated in terms of @dfn{sequence points}, which represent
+a partial ordering between the execution of parts of the program: those
+executed before the sequence point, and those executed after it.  These
+occur after the evaluation of a full expression (one which is not part
+of a larger expression), after the evaluation of the first operand of a
+@code{&&}, @code{||}, @code{? :} or @code{,} (comma) operator, before a
+function is called (but after the evaluation of its arguments and the
+expression denoting the called function), and in certain other places.
+Other than as expressed by the sequence point rules, the order of
+evaluation of subexpressions of an expression is not specified.  All
+these rules describe only a partial order rather than a total order,
+since, for example, if two functions are called within one expression
+with no sequence point between them, the order in which the functions
+are called is not specified.  However, the standards committee have
+ruled that function calls do not overlap.
+
+It is not specified when between sequence points modifications to the
+values of objects take effect.  Programs whose behavior depends on this
+have undefined behavior; the C and C++ standards specify that ``Between
+the previous and next sequence point an object shall have its stored
+value modified at most once by the evaluation of an expression.
+Furthermore, the prior value shall be read only to determine the value
+to be stored.''.  If a program breaks these rules, the results on any
+particular implementation are entirely unpredictable.
+
+Examples of code with undefined behavior are @code{a = a++;}, @code{a[n]
+= b[n++]} and @code{a[i++] = i;}.  Some more complicated cases are not
+diagnosed by this option, and it may give an occasional false positive
+result, but in general it has been found fairly effective at detecting
+this sort of problem in programs.
+
+The C++17 standard will define the order of evaluation of operands in
+more cases: in particular it requires that the right-hand side of an
+assignment be evaluated before the left-hand side, so the above
+examples are no longer undefined.  But this option will still warn
+about them, to help people avoid writing code that is undefined in C
+and earlier revisions of C++.
+
+The standard is worded confusingly, therefore there is some debate
+over the precise meaning of the sequence point rules in subtle cases.
+Links to discussions of the problem, including proposed formal
+definitions, may be found on the GCC readings page, at
+@uref{https://gcc.gnu.org/@/readings.html}.
+
+This warning is enabled by @option{-Wall} for C and C++.
+
+@item -Wno-return-local-addr
+@opindex Wno-return-local-addr
+@opindex Wreturn-local-addr
+Do not warn about returning a pointer (or in C++, a reference) to a
+variable that goes out of scope after the function returns.
+
+@item -Wreturn-type
+@opindex Wreturn-type
+@opindex Wno-return-type
+Warn whenever a function is defined with a return type that defaults
+to @code{int}.  Also warn about any @code{return} statement with no
+return value in a function whose return type is not @code{void}
+(falling off the end of the function body is considered returning
+without a value).
+
+For C only, warn about a @code{return} statement with an expression in a
+function whose return type is @code{void}, unless the expression type is
+also @code{void}.  As a GNU extension, the latter case is accepted
+without a warning unless @option{-Wpedantic} is used.  Attempting
+to use the return value of a non-@code{void} function other than @code{main}
+that flows off the end by reaching the closing curly brace that terminates
+the function is undefined.
+
+Unlike in C, in C++, flowing off the end of a non-@code{void} function other
+than @code{main} results in undefined behavior even when the value of
+the function is not used.
+
+This warning is enabled by default in C++ and by @option{-Wall} otherwise.
+
+@item -Wno-shift-count-negative
+@opindex Wshift-count-negative
+@opindex Wno-shift-count-negative
+Controls warnings if a shift count is negative.
+This warning is enabled by default.
+
+@item -Wno-shift-count-overflow
+@opindex Wshift-count-overflow
+@opindex Wno-shift-count-overflow
+Controls warnings if a shift count is greater than or equal to the bit width
+of the type.  This warning is enabled by default.
+
+@item -Wshift-negative-value
+@opindex Wshift-negative-value
+@opindex Wno-shift-negative-value
+Warn if left shifting a negative value.  This warning is enabled by
+@option{-Wextra} in C99 (and newer) and C++11 to C++17 modes.
+
+@item -Wno-shift-overflow
+@itemx -Wshift-overflow=@var{n}
+@opindex Wshift-overflow
+@opindex Wno-shift-overflow
+These options control warnings about left shift overflows.
+
+@table @gcctabopt
+@item -Wshift-overflow=1
+This is the warning level of @option{-Wshift-overflow} and is enabled
+by default in C99 and C++11 modes (and newer).  This warning level does
+not warn about left-shifting 1 into the sign bit.  (However, in C, such
+an overflow is still rejected in contexts where an integer constant expression
+is required.)  No warning is emitted in C++20 mode (and newer), as signed left
+shifts always wrap.
+
+@item -Wshift-overflow=2
+This warning level also warns about left-shifting 1 into the sign bit,
+unless C++14 mode (or newer) is active.
+@end table
+
+@item -Wswitch
+@opindex Wswitch
+@opindex Wno-switch
+Warn whenever a @code{switch} statement has an index of enumerated type
+and lacks a @code{case} for one or more of the named codes of that
+enumeration.  (The presence of a @code{default} label prevents this
+warning.)  @code{case} labels outside the enumeration range also
+provoke warnings when this option is used (even if there is a
+@code{default} label).
+This warning is enabled by @option{-Wall}.
+
+@item -Wswitch-default
+@opindex Wswitch-default
+@opindex Wno-switch-default
+Warn whenever a @code{switch} statement does not have a @code{default}
+case.
+
+@item -Wswitch-enum
+@opindex Wswitch-enum
+@opindex Wno-switch-enum
+Warn whenever a @code{switch} statement has an index of enumerated type
+and lacks a @code{case} for one or more of the named codes of that
+enumeration.  @code{case} labels outside the enumeration range also
+provoke warnings when this option is used.  The only difference
+between @option{-Wswitch} and this option is that this option gives a
+warning about an omitted enumeration code even if there is a
+@code{default} label.
+
+@item -Wno-switch-bool
+@opindex Wswitch-bool
+@opindex Wno-switch-bool
+Do not warn when a @code{switch} statement has an index of boolean type
+and the case values are outside the range of a boolean type.
+It is possible to suppress this warning by casting the controlling
+expression to a type other than @code{bool}.  For example:
+@smallexample
+@group
+switch ((int) (a == 4))
+  @{
+  @dots{}
+  @}
+@end group
+@end smallexample
+This warning is enabled by default for C and C++ programs.
+
+@item -Wno-switch-outside-range
+@opindex Wswitch-outside-range
+@opindex Wno-switch-outside-range
+This option controls warnings when a @code{switch} case has a value
+that is outside of its
+respective type range.  This warning is enabled by default for
+C and C++ programs.
+
+@item -Wno-switch-unreachable
+@opindex Wswitch-unreachable
+@opindex Wno-switch-unreachable
+Do not warn when a @code{switch} statement contains statements between the
+controlling expression and the first case label, which will never be
+executed.  For example:
+@smallexample
+@group
+switch (cond)
+  @{
+   i = 15;
+  @dots{}
+   case 5:
+  @dots{}
+  @}
+@end group
+@end smallexample
+@option{-Wswitch-unreachable} does not warn if the statement between the
+controlling expression and the first case label is just a declaration:
+@smallexample
+@group
+switch (cond)
+  @{
+   int i;
+  @dots{}
+   case 5:
+   i = 5;
+  @dots{}
+  @}
+@end group
+@end smallexample
+This warning is enabled by default for C and C++ programs.
+
+@item -Wsync-nand @r{(C and C++ only)}
+@opindex Wsync-nand
+@opindex Wno-sync-nand
+Warn when @code{__sync_fetch_and_nand} and @code{__sync_nand_and_fetch}
+built-in functions are used.  These functions changed semantics in GCC 4.4.
+
+@item -Wtrivial-auto-var-init
+@opindex Wtrivial-auto-var-init
+@opindex Wno-trivial-auto-var-init
+Warn when @code{-ftrivial-auto-var-init} cannot initialize the automatic
+variable.  A common situation is an automatic variable that is declared
+between the controlling expression and the first case label of a @code{switch}
+statement.
+
+@item -Wunused-but-set-parameter
+@opindex Wunused-but-set-parameter
+@opindex Wno-unused-but-set-parameter
+Warn whenever a function parameter is assigned to, but otherwise unused
+(aside from its declaration).
+
+To suppress this warning use the @code{unused} attribute
+(@pxref{Variable Attributes}).
+
+This warning is also enabled by @option{-Wunused} together with
+@option{-Wextra}.
+
+@item -Wunused-but-set-variable
+@opindex Wunused-but-set-variable
+@opindex Wno-unused-but-set-variable
+Warn whenever a local variable is assigned to, but otherwise unused
+(aside from its declaration).
+This warning is enabled by @option{-Wall}.
+
+To suppress this warning use the @code{unused} attribute
+(@pxref{Variable Attributes}).
+
+This warning is also enabled by @option{-Wunused}, which is enabled
+by @option{-Wall}.
+
+@item -Wunused-function
+@opindex Wunused-function
+@opindex Wno-unused-function
+Warn whenever a static function is declared but not defined or a
+non-inline static function is unused.
+This warning is enabled by @option{-Wall}.
+
+@item -Wunused-label
+@opindex Wunused-label
+@opindex Wno-unused-label
+Warn whenever a label is declared but not used.
+This warning is enabled by @option{-Wall}.
+
+To suppress this warning use the @code{unused} attribute
+(@pxref{Variable Attributes}).
+
+@item -Wunused-local-typedefs @r{(C, Objective-C, C++ and Objective-C++ only)}
+@opindex Wunused-local-typedefs
+@opindex Wno-unused-local-typedefs
+Warn when a typedef locally defined in a function is not used.
+This warning is enabled by @option{-Wall}.
+
+@item -Wunused-parameter
+@opindex Wunused-parameter
+@opindex Wno-unused-parameter
+Warn whenever a function parameter is unused aside from its declaration.
+
+To suppress this warning use the @code{unused} attribute
+(@pxref{Variable Attributes}).
+
+@item -Wno-unused-result
+@opindex Wunused-result
+@opindex Wno-unused-result
+Do not warn if a caller of a function marked with attribute
+@code{warn_unused_result} (@pxref{Function Attributes}) does not use
+its return value. The default is @option{-Wunused-result}.
+
+@item -Wunused-variable
+@opindex Wunused-variable
+@opindex Wno-unused-variable
+Warn whenever a local or static variable is unused aside from its
+declaration. This option implies @option{-Wunused-const-variable=1} for C,
+but not for C++. This warning is enabled by @option{-Wall}.
+
+To suppress this warning use the @code{unused} attribute
+(@pxref{Variable Attributes}).
+
+@item -Wunused-const-variable
+@itemx -Wunused-const-variable=@var{n}
+@opindex Wunused-const-variable
+@opindex Wno-unused-const-variable
+Warn whenever a constant static variable is unused aside from its declaration.
+@option{-Wunused-const-variable=1} is enabled by @option{-Wunused-variable}
+for C, but not for C++. In C this declares variable storage, but in C++ this
+is not an error since const variables take the place of @code{#define}s.
+
+To suppress this warning use the @code{unused} attribute
+(@pxref{Variable Attributes}).
+
+@table @gcctabopt
+@item -Wunused-const-variable=1
+This is the warning level that is enabled by @option{-Wunused-variable} for
+C.  It warns only about unused static const variables defined in the main
+compilation unit, but not about static const variables declared in any
+header included.
+
+@item -Wunused-const-variable=2
+This warning level also warns for unused constant static variables in
+headers (excluding system headers).  This is the warning level of
+@option{-Wunused-const-variable} and must be explicitly requested since
+in C++ this isn't an error and in C it might be harder to clean up all
+headers included.
+@end table
+
+@item -Wunused-value
+@opindex Wunused-value
+@opindex Wno-unused-value
+Warn whenever a statement computes a result that is explicitly not
+used. To suppress this warning cast the unused expression to
+@code{void}. This includes an expression-statement or the left-hand
+side of a comma expression that contains no side effects. For example,
+an expression such as @code{x[i,j]} causes a warning, while
+@code{x[(void)i,j]} does not.
+
+This warning is enabled by @option{-Wall}.
+
+@item -Wunused
+@opindex Wunused
+@opindex Wno-unused
+All the above @option{-Wunused} options combined.
+
+In order to get a warning about an unused function parameter, you must
+either specify @option{-Wextra -Wunused} (note that @option{-Wall} implies
+@option{-Wunused}), or separately specify @option{-Wunused-parameter}.
+
+@item -Wuninitialized
+@opindex Wuninitialized
+@opindex Wno-uninitialized
+Warn if an object with automatic or allocated storage duration is used
+without having been initialized.  In C++, also warn if a non-static
+reference or non-static @code{const} member appears in a class without
+constructors.
+
+In addition, passing a pointer (or in C++, a reference) to an uninitialized
+object to a @code{const}-qualified argument of a built-in function known to
+read the object is also diagnosed by this warning.
+(@option{-Wmaybe-uninitialized} is issued for ordinary functions.)
+
+If you want to warn about code that uses the uninitialized value of the
+variable in its own initializer, use the @option{-Winit-self} option.
+
+These warnings occur for individual uninitialized elements of
+structure, union or array variables as well as for variables that are
+uninitialized as a whole.  They do not occur for variables or elements
+declared @code{volatile}.  Because these warnings depend on
+optimization, the exact variables or elements for which there are
+warnings depend on the precise optimization options and version of GCC
+used.
+
+Note that there may be no warning about a variable that is used only
+to compute a value that itself is never used, because such
+computations may be deleted by data flow analysis before the warnings
+are printed.
+
+In C++, this warning also warns about using uninitialized objects in
+member-initializer-lists.  For example, GCC warns about @code{b} being
+uninitialized in the following snippet:
+
+@smallexample
+struct A @{
+  int a;
+  int b;
+  A() : a(b) @{ @}
+@};
+@end smallexample
+
+@item -Wno-invalid-memory-model
+@opindex Winvalid-memory-model
+@opindex Wno-invalid-memory-model
+This option controls warnings
+for invocations of @ref{__atomic Builtins}, @ref{__sync Builtins},
+and the C11 atomic generic functions with a memory consistency argument
+that is either invalid for the operation or outside the range of values
+of the @code{memory_order} enumeration.  For example, since the
+@code{__atomic_store} and @code{__atomic_store_n} built-ins are only
+defined for the relaxed, release, and sequentially consistent memory
+orders the following code is diagnosed:
+
+@smallexample
+void store (int *i)
+@{
+  __atomic_store_n (i, 0, memory_order_consume);
+@}
+@end smallexample
+
+@option{-Winvalid-memory-model} is enabled by default.
+
+@item -Wmaybe-uninitialized
+@opindex Wmaybe-uninitialized
+@opindex Wno-maybe-uninitialized
+For an object with automatic or allocated storage duration, if there exists
+a path from the function entry to a use of the object that is initialized,
+but there exist some other paths for which the object is not initialized,
+the compiler emits a warning if it cannot prove the uninitialized paths
+are not executed at run time.
+
+In addition, passing a pointer (or in C++, a reference) to an uninitialized
+object to a @code{const}-qualified function argument is also diagnosed by
+this warning.  (@option{-Wuninitialized} is issued for built-in functions
+known to read the object.)  Annotating the function with attribute
+@code{access (none)} indicates that the argument isn't used to access
+the object and avoids the warning (@pxref{Common Function Attributes}).
+
+These warnings are only possible in optimizing compilation, because otherwise
+GCC does not keep track of the state of variables.
+
+These warnings are made optional because GCC may not be able to determine when
+the code is correct in spite of appearing to have an error.  Here is one
+example of how this can happen:
+
+@smallexample
+@group
+@{
+  int x;
+  switch (y)
+    @{
+    case 1: x = 1;
+      break;
+    case 2: x = 4;
+      break;
+    case 3: x = 5;
+    @}
+  foo (x);
+@}
+@end group
+@end smallexample
+
+@noindent
+If the value of @code{y} is always 1, 2 or 3, then @code{x} is
+always initialized, but GCC doesn't know this. To suppress the
+warning, you need to provide a default case with assert(0) or
+similar code.
+
+@cindex @code{longjmp} warnings
+This option also warns when a non-volatile automatic variable might be
+changed by a call to @code{longjmp}.
+The compiler sees only the calls to @code{setjmp}.  It cannot know
+where @code{longjmp} will be called; in fact, a signal handler could
+call it at any point in the code.  As a result, you may get a warning
+even when there is in fact no problem because @code{longjmp} cannot
+in fact be called at the place that would cause a problem.
+
+Some spurious warnings can be avoided if you declare all the functions
+you use that never return as @code{noreturn}.  @xref{Function
+Attributes}.
+
+This warning is enabled by @option{-Wall} or @option{-Wextra}.
+
+@item -Wunknown-pragmas
+@opindex Wunknown-pragmas
+@opindex Wno-unknown-pragmas
+@cindex warning for unknown pragmas
+@cindex unknown pragmas, warning
+@cindex pragmas, warning of unknown
+Warn when a @code{#pragma} directive is encountered that is not understood by 
+GCC@.  If this command-line option is used, warnings are even issued
+for unknown pragmas in system header files.  This is not the case if
+the warnings are only enabled by the @option{-Wall} command-line option.
+
+@item -Wno-pragmas
+@opindex Wno-pragmas
+@opindex Wpragmas
+Do not warn about misuses of pragmas, such as incorrect parameters,
+invalid syntax, or conflicts between pragmas.  See also
+@option{-Wunknown-pragmas}.
+
+@item -Wno-prio-ctor-dtor
+@opindex Wno-prio-ctor-dtor
+@opindex Wprio-ctor-dtor
+Do not warn if a priority from 0 to 100 is used for constructor or destructor.
+The use of constructor and destructor attributes allow you to assign a
+priority to the constructor/destructor to control its order of execution
+before @code{main} is called or after it returns.  The priority values must be
+greater than 100 as the compiler reserves priority values between 0--100 for
+the implementation.
+
+@item -Wstrict-aliasing
+@opindex Wstrict-aliasing
+@opindex Wno-strict-aliasing
+This option is only active when @option{-fstrict-aliasing} is active.
+It warns about code that might break the strict aliasing rules that the
+compiler is using for optimization.  The warning does not catch all
+cases, but does attempt to catch the more common pitfalls.  It is
+included in @option{-Wall}.
+It is equivalent to @option{-Wstrict-aliasing=3}
+
+@item -Wstrict-aliasing=n
+@opindex Wstrict-aliasing=n
+This option is only active when @option{-fstrict-aliasing} is active.
+It warns about code that might break the strict aliasing rules that the
+compiler is using for optimization.
+Higher levels correspond to higher accuracy (fewer false positives).
+Higher levels also correspond to more effort, similar to the way @option{-O} 
+works.
+@option{-Wstrict-aliasing} is equivalent to @option{-Wstrict-aliasing=3}.
+
+Level 1: Most aggressive, quick, least accurate.
+Possibly useful when higher levels
+do not warn but @option{-fstrict-aliasing} still breaks the code, as it has very few
+false negatives.  However, it has many false positives.
+Warns for all pointer conversions between possibly incompatible types,
+even if never dereferenced.  Runs in the front end only.
+
+Level 2: Aggressive, quick, not too precise.
+May still have many false positives (not as many as level 1 though),
+and few false negatives (but possibly more than level 1).
+Unlike level 1, it only warns when an address is taken.  Warns about
+incomplete types.  Runs in the front end only.
+
+Level 3 (default for @option{-Wstrict-aliasing}):
+Should have very few false positives and few false
+negatives.  Slightly slower than levels 1 or 2 when optimization is enabled.
+Takes care of the common pun+dereference pattern in the front end:
+@code{*(int*)&some_float}.
+If optimization is enabled, it also runs in the back end, where it deals
+with multiple statement cases using flow-sensitive points-to information.
+Only warns when the converted pointer is dereferenced.
+Does not warn about incomplete types.
+
+@item -Wstrict-overflow
+@itemx -Wstrict-overflow=@var{n}
+@opindex Wstrict-overflow
+@opindex Wno-strict-overflow
+This option is only active when signed overflow is undefined.
+It warns about cases where the compiler optimizes based on the
+assumption that signed overflow does not occur.  Note that it does not
+warn about all cases where the code might overflow: it only warns
+about cases where the compiler implements some optimization.  Thus
+this warning depends on the optimization level.
+
+An optimization that assumes that signed overflow does not occur is
+perfectly safe if the values of the variables involved are such that
+overflow never does, in fact, occur.  Therefore this warning can
+easily give a false positive: a warning about code that is not
+actually a problem.  To help focus on important issues, several
+warning levels are defined.  No warnings are issued for the use of
+undefined signed overflow when estimating how many iterations a loop
+requires, in particular when determining whether a loop will be
+executed at all.
+
+@table @gcctabopt
+@item -Wstrict-overflow=1
+Warn about cases that are both questionable and easy to avoid.  For
+example the compiler simplifies
+@code{x + 1 > x} to @code{1}.  This level of
+@option{-Wstrict-overflow} is enabled by @option{-Wall}; higher levels
+are not, and must be explicitly requested.
+
+@item -Wstrict-overflow=2
+Also warn about other cases where a comparison is simplified to a
+constant.  For example: @code{abs (x) >= 0}.  This can only be
+simplified when signed integer overflow is undefined, because
+@code{abs (INT_MIN)} overflows to @code{INT_MIN}, which is less than
+zero.  @option{-Wstrict-overflow} (with no level) is the same as
+@option{-Wstrict-overflow=2}.
+
+@item -Wstrict-overflow=3
+Also warn about other cases where a comparison is simplified.  For
+example: @code{x + 1 > 1} is simplified to @code{x > 0}.
+
+@item -Wstrict-overflow=4
+Also warn about other simplifications not covered by the above cases.
+For example: @code{(x * 10) / 5} is simplified to @code{x * 2}.
+
+@item -Wstrict-overflow=5
+Also warn about cases where the compiler reduces the magnitude of a
+constant involved in a comparison.  For example: @code{x + 2 > y} is
+simplified to @code{x + 1 >= y}.  This is reported only at the
+highest warning level because this simplification applies to many
+comparisons, so this warning level gives a very large number of
+false positives.
+@end table
+
+@item -Wstring-compare
+@opindex Wstring-compare
+@opindex Wno-string-compare
+Warn for calls to @code{strcmp} and @code{strncmp} whose result is
+determined to be either zero or non-zero in tests for such equality
+owing to the length of one argument being greater than the size of
+the array the other argument is stored in (or the bound in the case
+of @code{strncmp}).  Such calls could be mistakes.  For example,
+the call to @code{strcmp} below is diagnosed because its result is
+necessarily non-zero irrespective of the contents of the array @code{a}.
+
+@smallexample
+extern char a[4];
+void f (char *d)
+@{
+  strcpy (d, "string");
+  @dots{}
+  if (0 == strcmp (a, d))   // cannot be true
+    puts ("a and d are the same");
+@}
+@end smallexample
+
+@option{-Wstring-compare} is enabled by @option{-Wextra}.
+
+@item -Wno-stringop-overflow
+@item -Wstringop-overflow
+@itemx -Wstringop-overflow=@var{type}
+@opindex Wstringop-overflow
+@opindex Wno-stringop-overflow
+Warn for calls to string manipulation functions such as @code{memcpy} and
+@code{strcpy} that are determined to overflow the destination buffer.  The
+optional argument is one greater than the type of Object Size Checking to
+perform to determine the size of the destination.  @xref{Object Size Checking}.
+The argument is meaningful only for functions that operate on character arrays
+but not for raw memory functions like @code{memcpy} which always make use
+of Object Size type-0.  The option also warns for calls that specify a size
+in excess of the largest possible object or at most @code{SIZE_MAX / 2} bytes.
+The option produces the best results with optimization enabled but can detect
+a small subset of simple buffer overflows even without optimization in
+calls to the GCC built-in functions like @code{__builtin_memcpy} that
+correspond to the standard functions.  In any case, the option warns about
+just a subset of buffer overflows detected by the corresponding overflow
+checking built-ins.  For example, the option issues a warning for
+the @code{strcpy} call below because it copies at least 5 characters
+(the string @code{"blue"} including the terminating NUL) into the buffer
+of size 4.
+
+@smallexample
+enum Color @{ blue, purple, yellow @};
+const char* f (enum Color clr)
+@{
+  static char buf [4];
+  const char *str;
+  switch (clr)
+    @{
+      case blue: str = "blue"; break;
+      case purple: str = "purple"; break;
+      case yellow: str = "yellow"; break;
+    @}
+
+  return strcpy (buf, str);   // warning here
+@}
+@end smallexample
+
+Option @option{-Wstringop-overflow=2} is enabled by default.
+
+@table @gcctabopt
+@item -Wstringop-overflow
+@itemx -Wstringop-overflow=1
+@opindex Wstringop-overflow
+@opindex Wno-stringop-overflow
+The @option{-Wstringop-overflow=1} option uses type-zero Object Size Checking
+to determine the sizes of destination objects.  At this setting the option
+does not warn for writes past the end of subobjects of larger objects accessed
+by pointers unless the size of the largest surrounding object is known.  When
+the destination may be one of several objects it is assumed to be the largest
+one of them.  On Linux systems, when optimization is enabled at this setting
+the option warns for the same code as when the @code{_FORTIFY_SOURCE} macro
+is defined to a non-zero value.
+
+@item -Wstringop-overflow=2
+The @option{-Wstringop-overflow=2} option uses type-one Object Size Checking
+to determine the sizes of destination objects.  At this setting the option
+warns about overflows when writing to members of the largest complete
+objects whose exact size is known.  However, it does not warn for excessive
+writes to the same members of unknown objects referenced by pointers since
+they may point to arrays containing unknown numbers of elements.  This is
+the default setting of the option.
+
+@item -Wstringop-overflow=3
+The @option{-Wstringop-overflow=3} option uses type-two Object Size Checking
+to determine the sizes of destination objects.  At this setting the option
+warns about overflowing the smallest object or data member.  This is the
+most restrictive setting of the option that may result in warnings for safe
+code.
+
+@item -Wstringop-overflow=4
+The @option{-Wstringop-overflow=4} option uses type-three Object Size Checking
+to determine the sizes of destination objects.  At this setting the option
+warns about overflowing any data members, and when the destination is
+one of several objects it uses the size of the largest of them to decide
+whether to issue a warning.  Similarly to @option{-Wstringop-overflow=3} this
+setting of the option may result in warnings for benign code.
+@end table
+
+@item -Wno-stringop-overread
+@opindex Wstringop-overread
+@opindex Wno-stringop-overread
+Warn for calls to string manipulation functions such as @code{memchr}, or
+@code{strcpy} that are determined to read past the end of the source
+sequence.
+
+Option @option{-Wstringop-overread} is enabled by default.
+
+@item -Wno-stringop-truncation
+@opindex Wstringop-truncation
+@opindex Wno-stringop-truncation
+Do not warn for calls to bounded string manipulation functions
+such as @code{strncat},
+@code{strncpy}, and @code{stpncpy} that may either truncate the copied string
+or leave the destination unchanged.
+
+In the following example, the call to @code{strncat} specifies a bound that
+is less than the length of the source string.  As a result, the copy of
+the source will be truncated and so the call is diagnosed.  To avoid the
+warning use @code{bufsize - strlen (buf) - 1)} as the bound.
+
+@smallexample
+void append (char *buf, size_t bufsize)
+@{
+  strncat (buf, ".txt", 3);
+@}
+@end smallexample
+
+As another example, the following call to @code{strncpy} results in copying
+to @code{d} just the characters preceding the terminating NUL, without
+appending the NUL to the end.  Assuming the result of @code{strncpy} is
+necessarily a NUL-terminated string is a common mistake, and so the call
+is diagnosed.  To avoid the warning when the result is not expected to be
+NUL-terminated, call @code{memcpy} instead.
+
+@smallexample
+void copy (char *d, const char *s)
+@{
+  strncpy (d, s, strlen (s));
+@}
+@end smallexample
+
+In the following example, the call to @code{strncpy} specifies the size
+of the destination buffer as the bound.  If the length of the source
+string is equal to or greater than this size the result of the copy will
+not be NUL-terminated.  Therefore, the call is also diagnosed.  To avoid
+the warning, specify @code{sizeof buf - 1} as the bound and set the last
+element of the buffer to @code{NUL}.
+
+@smallexample
+void copy (const char *s)
+@{
+  char buf[80];
+  strncpy (buf, s, sizeof buf);
+  @dots{}
+@}
+@end smallexample
+
+In situations where a character array is intended to store a sequence
+of bytes with no terminating @code{NUL} such an array may be annotated
+with attribute @code{nonstring} to avoid this warning.  Such arrays,
+however, are not suitable arguments to functions that expect
+@code{NUL}-terminated strings.  To help detect accidental misuses of
+such arrays GCC issues warnings unless it can prove that the use is
+safe.  @xref{Common Variable Attributes}.
+
+@item -Wsuggest-attribute=@r{[}pure@r{|}const@r{|}noreturn@r{|}format@r{|}cold@r{|}malloc@r{]}
+@opindex Wsuggest-attribute=
+@opindex Wno-suggest-attribute=
+Warn for cases where adding an attribute may be beneficial. The
+attributes currently supported are listed below.
+
+@table @gcctabopt
+@item -Wsuggest-attribute=pure
+@itemx -Wsuggest-attribute=const
+@itemx -Wsuggest-attribute=noreturn
+@itemx -Wmissing-noreturn
+@itemx -Wsuggest-attribute=malloc
+@opindex Wsuggest-attribute=pure
+@opindex Wno-suggest-attribute=pure
+@opindex Wsuggest-attribute=const
+@opindex Wno-suggest-attribute=const
+@opindex Wsuggest-attribute=noreturn
+@opindex Wno-suggest-attribute=noreturn
+@opindex Wmissing-noreturn
+@opindex Wno-missing-noreturn
+@opindex Wsuggest-attribute=malloc
+@opindex Wno-suggest-attribute=malloc
+
+Warn about functions that might be candidates for attributes
+@code{pure}, @code{const} or @code{noreturn} or @code{malloc}. The compiler
+only warns for functions visible in other compilation units or (in the case of
+@code{pure} and @code{const}) if it cannot prove that the function returns
+normally. A function returns normally if it doesn't contain an infinite loop or
+return abnormally by throwing, calling @code{abort} or trapping.  This analysis
+requires option @option{-fipa-pure-const}, which is enabled by default at
+@option{-O} and higher.  Higher optimization levels improve the accuracy
+of the analysis.
+
+@item -Wsuggest-attribute=format
+@itemx -Wmissing-format-attribute
+@opindex Wsuggest-attribute=format
+@opindex Wmissing-format-attribute
+@opindex Wno-suggest-attribute=format
+@opindex Wno-missing-format-attribute
+@opindex Wformat
+@opindex Wno-format
+
+Warn about function pointers that might be candidates for @code{format}
+attributes.  Note these are only possible candidates, not absolute ones.
+GCC guesses that function pointers with @code{format} attributes that
+are used in assignment, initialization, parameter passing or return
+statements should have a corresponding @code{format} attribute in the
+resulting type.  I.e.@: the left-hand side of the assignment or
+initialization, the type of the parameter variable, or the return type
+of the containing function respectively should also have a @code{format}
+attribute to avoid the warning.
+
+GCC also warns about function definitions that might be
+candidates for @code{format} attributes.  Again, these are only
+possible candidates.  GCC guesses that @code{format} attributes
+might be appropriate for any function that calls a function like
+@code{vprintf} or @code{vscanf}, but this might not always be the
+case, and some functions for which @code{format} attributes are
+appropriate may not be detected.
+
+@item -Wsuggest-attribute=cold
+@opindex Wsuggest-attribute=cold
+@opindex Wno-suggest-attribute=cold
+
+Warn about functions that might be candidates for @code{cold} attribute.  This
+is based on static detection and generally only warns about functions which
+always leads to a call to another @code{cold} function such as wrappers of
+C++ @code{throw} or fatal error reporting functions leading to @code{abort}.
+@end table
+
+@item -Walloc-zero
+@opindex Wno-alloc-zero
+@opindex Walloc-zero
+Warn about calls to allocation functions decorated with attribute
+@code{alloc_size} that specify zero bytes, including those to the built-in
+forms of the functions @code{aligned_alloc}, @code{alloca}, @code{calloc},
+@code{malloc}, and @code{realloc}.  Because the behavior of these functions
+when called with a zero size differs among implementations (and in the case
+of @code{realloc} has been deprecated) relying on it may result in subtle
+portability bugs and should be avoided.
+
+@item -Walloc-size-larger-than=@var{byte-size}
+@opindex Walloc-size-larger-than=
+@opindex Wno-alloc-size-larger-than
+Warn about calls to functions decorated with attribute @code{alloc_size}
+that attempt to allocate objects larger than the specified number of bytes,
+or where the result of the size computation in an integer type with infinite
+precision would exceed the value of @samp{PTRDIFF_MAX} on the target.
+@option{-Walloc-size-larger-than=}@samp{PTRDIFF_MAX} is enabled by default.
+Warnings controlled by the option can be disabled either by specifying
+@var{byte-size} of @samp{SIZE_MAX} or more or by
+@option{-Wno-alloc-size-larger-than}.
+@xref{Function Attributes}.
+
+@item -Wno-alloc-size-larger-than
+@opindex Wno-alloc-size-larger-than
+Disable @option{-Walloc-size-larger-than=} warnings.  The option is
+equivalent to @option{-Walloc-size-larger-than=}@samp{SIZE_MAX} or
+larger.
+
+@item -Walloca
+@opindex Wno-alloca
+@opindex Walloca
+This option warns on all uses of @code{alloca} in the source.
+
+@item -Walloca-larger-than=@var{byte-size}
+@opindex Walloca-larger-than=
+@opindex Wno-alloca-larger-than
+This option warns on calls to @code{alloca} with an integer argument whose
+value is either zero, or that is not bounded by a controlling predicate
+that limits its value to at most @var{byte-size}.  It also warns for calls
+to @code{alloca} where the bound value is unknown.  Arguments of non-integer
+types are considered unbounded even if they appear to be constrained to
+the expected range.
+
+For example, a bounded case of @code{alloca} could be:
+
+@smallexample
+void func (size_t n)
+@{
+  void *p;
+  if (n <= 1000)
+    p = alloca (n);
+  else
+    p = malloc (n);
+  f (p);
+@}
+@end smallexample
+
+In the above example, passing @code{-Walloca-larger-than=1000} would not
+issue a warning because the call to @code{alloca} is known to be at most
+1000 bytes.  However, if @code{-Walloca-larger-than=500} were passed,
+the compiler would emit a warning.
+
+Unbounded uses, on the other hand, are uses of @code{alloca} with no
+controlling predicate constraining its integer argument.  For example:
+
+@smallexample
+void func ()
+@{
+  void *p = alloca (n);
+  f (p);
+@}
+@end smallexample
+
+If @code{-Walloca-larger-than=500} were passed, the above would trigger
+a warning, but this time because of the lack of bounds checking.
+
+Note, that even seemingly correct code involving signed integers could
+cause a warning:
+
+@smallexample
+void func (signed int n)
+@{
+  if (n < 500)
+    @{
+      p = alloca (n);
+      f (p);
+    @}
+@}
+@end smallexample
+
+In the above example, @var{n} could be negative, causing a larger than
+expected argument to be implicitly cast into the @code{alloca} call.
+
+This option also warns when @code{alloca} is used in a loop.
+
+@option{-Walloca-larger-than=}@samp{PTRDIFF_MAX} is enabled by default
+but is usually only effective  when @option{-ftree-vrp} is active (default
+for @option{-O2} and above).
+
+See also @option{-Wvla-larger-than=}@samp{byte-size}.
+
+@item -Wno-alloca-larger-than
+@opindex Wno-alloca-larger-than
+Disable @option{-Walloca-larger-than=} warnings.  The option is
+equivalent to @option{-Walloca-larger-than=}@samp{SIZE_MAX} or larger.
+
+@item -Warith-conversion
+@opindex Warith-conversion
+@opindex Wno-arith-conversion
+Do warn about implicit conversions from arithmetic operations even
+when conversion of the operands to the same type cannot change their
+values.  This affects warnings from @option{-Wconversion},
+@option{-Wfloat-conversion}, and @option{-Wsign-conversion}.
+
+@smallexample
+@group
+void f (char c, int i)
+@{
+  c = c + i; // warns with @option{-Wconversion}
+  c = c + 1; // only warns with @option{-Warith-conversion}
+@}
+@end group
+@end smallexample
+
+@item -Warray-bounds
+@itemx -Warray-bounds=@var{n}
+@opindex Wno-array-bounds
+@opindex Warray-bounds
+Warn about out of bounds subscripts or offsets into arrays.  This warning
+is enabled by @option{-Wall}.  It is more effective when @option{-ftree-vrp}
+is active (the default for @option{-O2} and above) but a subset of instances
+are issued even without optimization.
+
+@table @gcctabopt
+@item -Warray-bounds=1
+This is the default warning level of @option{-Warray-bounds} and is enabled
+by @option{-Wall}; higher levels are not, and must be explicitly requested.
+
+@item -Warray-bounds=2
+This warning level also warns about out of bounds accesses to trailing
+struct members of one-element array types (@pxref{Zero Length}) and about
+the intermediate results of pointer arithmetic that may yield out of bounds
+values.  This warning level may give a larger number of false positives and
+is deactivated by default.
+@end table
+
+@item -Warray-compare
+@opindex Warray-compare
+@opindex Wno-array-compare
+Warn about equality and relational comparisons between two operands of array
+type.  This comparison was deprecated in C++20.  For example:
+
+@smallexample
+int arr1[5];
+int arr2[5];
+bool same = arr1 == arr2;
+@end smallexample
+
+@option{-Warray-compare} is enabled by @option{-Wall}.
+
+@item -Warray-parameter
+@itemx -Warray-parameter=@var{n}
+@opindex Wno-array-parameter
+Warn about redeclarations of functions involving arguments of array or
+pointer types of inconsistent kinds or forms, and enable the detection
+of out-of-bounds accesses to such parameters by warnings such as
+@option{-Warray-bounds}.
+
+If the first function declaration uses the array form the bound specified
+in the array is assumed to be the minimum number of elements expected to
+be provided in calls to the function and the maximum number of elements
+accessed by it.  Failing to provide arguments of sufficient size or accessing
+more than the maximum number of elements may be diagnosed by warnings such
+as @option{-Warray-bounds}.  At level 1 the warning diagnoses inconsistencies
+involving array parameters declared using the @code{T[static N]} form.
+
+For example, the warning triggers for the following redeclarations because
+the first one allows an array of any size to be passed to @code{f} while
+the second one with the keyword @code{static} specifies that the array
+argument must have at least four elements.
+
+@smallexample
+void f (int[static 4]);
+void f (int[]);           // warning (inconsistent array form)
+
+void g (void)
+@{
+  int *p = (int *)malloc (4);
+  f (p);                  // warning (array too small)
+  @dots{}
+@}
+@end smallexample
+
+At level 2 the warning also triggers for redeclarations involving any other
+inconsistency in array or pointer argument forms denoting array sizes.
+Pointers and arrays of unspecified bound are considered equivalent and do
+not trigger a warning.
+
+@smallexample
+void g (int*);
+void g (int[]);     // no warning
+void g (int[8]);    // warning (inconsistent array bound)
+@end smallexample
+
+@option{-Warray-parameter=2} is included in @option{-Wall}.  The
+@option{-Wvla-parameter} option triggers warnings for similar inconsistencies
+involving Variable Length Array arguments.
+
+@item -Wattribute-alias=@var{n}
+@itemx -Wno-attribute-alias
+@opindex Wattribute-alias
+@opindex Wno-attribute-alias
+Warn about declarations using the @code{alias} and similar attributes whose
+target is incompatible with the type of the alias.
+@xref{Function Attributes,,Declaring Attributes of Functions}.
+
+@table @gcctabopt
+@item -Wattribute-alias=1
+The default warning level of the @option{-Wattribute-alias} option diagnoses
+incompatibilities between the type of the alias declaration and that of its
+target.  Such incompatibilities are typically indicative of bugs.
+
+@item -Wattribute-alias=2
+
+At this level @option{-Wattribute-alias} also diagnoses cases where
+the attributes of the alias declaration are more restrictive than the
+attributes applied to its target.  These mismatches can potentially
+result in incorrect code generation.  In other cases they may be
+benign and could be resolved simply by adding the missing attribute to
+the target.  For comparison, see the @option{-Wmissing-attributes}
+option, which controls diagnostics when the alias declaration is less
+restrictive than the target, rather than more restrictive.
+
+Attributes considered include @code{alloc_align}, @code{alloc_size},
+@code{cold}, @code{const}, @code{hot}, @code{leaf}, @code{malloc},
+@code{nonnull}, @code{noreturn}, @code{nothrow}, @code{pure},
+@code{returns_nonnull}, and @code{returns_twice}.
+@end table
+
+@option{-Wattribute-alias} is equivalent to @option{-Wattribute-alias=1}.
+This is the default.  You can disable these warnings with either
+@option{-Wno-attribute-alias} or @option{-Wattribute-alias=0}.
+
+@item -Wbidi-chars=@r{[}none@r{|}unpaired@r{|}any@r{|}ucn@r{]}
+@opindex Wbidi-chars=
+@opindex Wbidi-chars
+@opindex Wno-bidi-chars
+Warn about possibly misleading UTF-8 bidirectional control characters in
+comments, string literals, character constants, and identifiers.  Such
+characters can change left-to-right writing direction into right-to-left
+(and vice versa), which can cause confusion between the logical order and
+visual order.  This may be dangerous; for instance, it may seem that a piece
+of code is not commented out, whereas it in fact is.
+
+There are three levels of warning supported by GCC@.  The default is
+@option{-Wbidi-chars=unpaired}, which warns about improperly terminated
+bidi contexts.  @option{-Wbidi-chars=none} turns the warning off.
+@option{-Wbidi-chars=any} warns about any use of bidirectional control
+characters.
+
+By default, this warning does not warn about UCNs.  It is, however, possible
+to turn on such checking by using @option{-Wbidi-chars=unpaired,ucn} or
+@option{-Wbidi-chars=any,ucn}.  Using @option{-Wbidi-chars=ucn} is valid,
+and is equivalent to @option{-Wbidi-chars=unpaired,ucn}, if no previous
+@option{-Wbidi-chars=any} was specified.
+
+@item -Wbool-compare
+@opindex Wno-bool-compare
+@opindex Wbool-compare
+Warn about boolean expression compared with an integer value different from
+@code{true}/@code{false}.  For instance, the following comparison is
+always false:
+@smallexample
+int n = 5;
+@dots{}
+if ((n > 1) == 2) @{ @dots{} @}
+@end smallexample
+This warning is enabled by @option{-Wall}.
+
+@item -Wbool-operation
+@opindex Wno-bool-operation
+@opindex Wbool-operation
+Warn about suspicious operations on expressions of a boolean type.  For
+instance, bitwise negation of a boolean is very likely a bug in the program.
+For C, this warning also warns about incrementing or decrementing a boolean,
+which rarely makes sense.  (In C++, decrementing a boolean is always invalid.
+Incrementing a boolean is invalid in C++17, and deprecated otherwise.)
+
+This warning is enabled by @option{-Wall}.
+
+@item -Wduplicated-branches
+@opindex Wno-duplicated-branches
+@opindex Wduplicated-branches
+Warn when an if-else has identical branches.  This warning detects cases like
+@smallexample
+if (p != NULL)
+  return 0;
+else
+  return 0;
+@end smallexample
+It doesn't warn when both branches contain just a null statement.  This warning
+also warn for conditional operators:
+@smallexample
+  int i = x ? *p : *p;
+@end smallexample
+
+@item -Wduplicated-cond
+@opindex Wno-duplicated-cond
+@opindex Wduplicated-cond
+Warn about duplicated conditions in an if-else-if chain.  For instance,
+warn for the following code:
+@smallexample
+if (p->q != NULL) @{ @dots{} @}
+else if (p->q != NULL) @{ @dots{} @}
+@end smallexample
+
+@item -Wframe-address
+@opindex Wno-frame-address
+@opindex Wframe-address
+Warn when the @samp{__builtin_frame_address} or @samp{__builtin_return_address}
+is called with an argument greater than 0.  Such calls may return indeterminate
+values or crash the program.  The warning is included in @option{-Wall}.
+
+@item -Wno-discarded-qualifiers @r{(C and Objective-C only)}
+@opindex Wno-discarded-qualifiers
+@opindex Wdiscarded-qualifiers
+Do not warn if type qualifiers on pointers are being discarded.
+Typically, the compiler warns if a @code{const char *} variable is
+passed to a function that takes a @code{char *} parameter.  This option
+can be used to suppress such a warning.
+
+@item -Wno-discarded-array-qualifiers @r{(C and Objective-C only)}
+@opindex Wno-discarded-array-qualifiers
+@opindex Wdiscarded-array-qualifiers
+Do not warn if type qualifiers on arrays which are pointer targets
+are being discarded.  Typically, the compiler warns if a
+@code{const int (*)[]} variable is passed to a function that
+takes a @code{int (*)[]} parameter.  This option can be used to
+suppress such a warning.
+
+@item -Wno-incompatible-pointer-types @r{(C and Objective-C only)}
+@opindex Wno-incompatible-pointer-types
+@opindex Wincompatible-pointer-types
+Do not warn when there is a conversion between pointers that have incompatible
+types.  This warning is for cases not covered by @option{-Wno-pointer-sign},
+which warns for pointer argument passing or assignment with different
+signedness.
+
+@item -Wno-int-conversion @r{(C and Objective-C only)}
+@opindex Wno-int-conversion
+@opindex Wint-conversion
+Do not warn about incompatible integer to pointer and pointer to integer
+conversions.  This warning is about implicit conversions; for explicit
+conversions the warnings @option{-Wno-int-to-pointer-cast} and
+@option{-Wno-pointer-to-int-cast} may be used.
+
+@item -Wzero-length-bounds
+@opindex Wzero-length-bounds
+@opindex Wzero-length-bounds
+Warn about accesses to elements of zero-length array members that might
+overlap other members of the same object.  Declaring interior zero-length
+arrays is discouraged because accesses to them are undefined.  See
+@xref{Zero Length}.
+
+For example, the first two stores in function @code{bad} are diagnosed
+because the array elements overlap the subsequent members @code{b} and
+@code{c}.  The third store is diagnosed by @option{-Warray-bounds}
+because it is beyond the bounds of the enclosing object.
+
+@smallexample
+struct X @{ int a[0]; int b, c; @};
+struct X x;
+
+void bad (void)
+@{
+  x.a[0] = 0;   // -Wzero-length-bounds
+  x.a[1] = 1;   // -Wzero-length-bounds
+  x.a[2] = 2;   // -Warray-bounds
+@}
+@end smallexample
+
+Option @option{-Wzero-length-bounds} is enabled by @option{-Warray-bounds}.
+
+@item -Wno-div-by-zero
+@opindex Wno-div-by-zero
+@opindex Wdiv-by-zero
+Do not warn about compile-time integer division by zero.  Floating-point
+division by zero is not warned about, as it can be a legitimate way of
+obtaining infinities and NaNs.
+
+@item -Wsystem-headers
+@opindex Wsystem-headers
+@opindex Wno-system-headers
+@cindex warnings from system headers
+@cindex system headers, warnings from
+Print warning messages for constructs found in system header files.
+Warnings from system headers are normally suppressed, on the assumption
+that they usually do not indicate real problems and would only make the
+compiler output harder to read.  Using this command-line option tells
+GCC to emit warnings from system headers as if they occurred in user
+code.  However, note that using @option{-Wall} in conjunction with this
+option does @emph{not} warn about unknown pragmas in system
+headers---for that, @option{-Wunknown-pragmas} must also be used.
+
+@item -Wtautological-compare
+@opindex Wtautological-compare
+@opindex Wno-tautological-compare
+Warn if a self-comparison always evaluates to true or false.  This
+warning detects various mistakes such as:
+@smallexample
+int i = 1;
+@dots{}
+if (i > i) @{ @dots{} @}
+@end smallexample
+
+This warning also warns about bitwise comparisons that always evaluate
+to true or false, for instance:
+@smallexample
+if ((a & 16) == 10) @{ @dots{} @}
+@end smallexample
+will always be false.
+
+This warning is enabled by @option{-Wall}.
+
+@item -Wtrampolines
+@opindex Wtrampolines
+@opindex Wno-trampolines
+Warn about trampolines generated for pointers to nested functions.
+A trampoline is a small piece of data or code that is created at run
+time on the stack when the address of a nested function is taken, and is
+used to call the nested function indirectly.  For some targets, it is
+made up of data only and thus requires no special treatment.  But, for
+most targets, it is made up of code and thus requires the stack to be
+made executable in order for the program to work properly.
+
+@item -Wfloat-equal
+@opindex Wfloat-equal
+@opindex Wno-float-equal
+Warn if floating-point values are used in equality comparisons.
+
+The idea behind this is that sometimes it is convenient (for the
+programmer) to consider floating-point values as approximations to
+infinitely precise real numbers.  If you are doing this, then you need
+to compute (by analyzing the code, or in some other way) the maximum or
+likely maximum error that the computation introduces, and allow for it
+when performing comparisons (and when producing output, but that's a
+different problem).  In particular, instead of testing for equality, you
+should check to see whether the two values have ranges that overlap; and
+this is done with the relational operators, so equality comparisons are
+probably mistaken.
+
+@item -Wtraditional @r{(C and Objective-C only)}
+@opindex Wtraditional
+@opindex Wno-traditional
+Warn about certain constructs that behave differently in traditional and
+ISO C@.  Also warn about ISO C constructs that have no traditional C
+equivalent, and/or problematic constructs that should be avoided.
+
+@itemize @bullet
+@item
+Macro parameters that appear within string literals in the macro body.
+In traditional C macro replacement takes place within string literals,
+but in ISO C it does not.
+
+@item
+In traditional C, some preprocessor directives did not exist.
+Traditional preprocessors only considered a line to be a directive
+if the @samp{#} appeared in column 1 on the line.  Therefore
+@option{-Wtraditional} warns about directives that traditional C
+understands but ignores because the @samp{#} does not appear as the
+first character on the line.  It also suggests you hide directives like
+@code{#pragma} not understood by traditional C by indenting them.  Some
+traditional implementations do not recognize @code{#elif}, so this option
+suggests avoiding it altogether.
+
+@item
+A function-like macro that appears without arguments.
+
+@item
+The unary plus operator.
+
+@item
+The @samp{U} integer constant suffix, or the @samp{F} or @samp{L} floating-point
+constant suffixes.  (Traditional C does support the @samp{L} suffix on integer
+constants.)  Note, these suffixes appear in macros defined in the system
+headers of most modern systems, e.g.@: the @samp{_MIN}/@samp{_MAX} macros in @code{<limits.h>}.
+Use of these macros in user code might normally lead to spurious
+warnings, however GCC's integrated preprocessor has enough context to
+avoid warning in these cases.
+
+@item
+A function declared external in one block and then used after the end of
+the block.
+
+@item
+A @code{switch} statement has an operand of type @code{long}.
+
+@item
+A non-@code{static} function declaration follows a @code{static} one.
+This construct is not accepted by some traditional C compilers.
+
+@item
+The ISO type of an integer constant has a different width or
+signedness from its traditional type.  This warning is only issued if
+the base of the constant is ten.  I.e.@: hexadecimal or octal values, which
+typically represent bit patterns, are not warned about.
+
+@item
+Usage of ISO string concatenation is detected.
+
+@item
+Initialization of automatic aggregates.
+
+@item
+Identifier conflicts with labels.  Traditional C lacks a separate
+namespace for labels.
+
+@item
+Initialization of unions.  If the initializer is zero, the warning is
+omitted.  This is done under the assumption that the zero initializer in
+user code appears conditioned on e.g.@: @code{__STDC__} to avoid missing
+initializer warnings and relies on default initialization to zero in the
+traditional C case.
+
+@item
+Conversions by prototypes between fixed/floating-point values and vice
+versa.  The absence of these prototypes when compiling with traditional
+C causes serious problems.  This is a subset of the possible
+conversion warnings; for the full set use @option{-Wtraditional-conversion}.
+
+@item
+Use of ISO C style function definitions.  This warning intentionally is
+@emph{not} issued for prototype declarations or variadic functions
+because these ISO C features appear in your code when using
+libiberty's traditional C compatibility macros, @code{PARAMS} and
+@code{VPARAMS}.  This warning is also bypassed for nested functions
+because that feature is already a GCC extension and thus not relevant to
+traditional C compatibility.
+@end itemize
+
+@item -Wtraditional-conversion @r{(C and Objective-C only)}
+@opindex Wtraditional-conversion
+@opindex Wno-traditional-conversion
+Warn if a prototype causes a type conversion that is different from what
+would happen to the same argument in the absence of a prototype.  This
+includes conversions of fixed point to floating and vice versa, and
+conversions changing the width or signedness of a fixed-point argument
+except when the same as the default promotion.
+
+@item -Wdeclaration-after-statement @r{(C and Objective-C only)}
+@opindex Wdeclaration-after-statement
+@opindex Wno-declaration-after-statement
+Warn when a declaration is found after a statement in a block.  This
+construct, known from C++, was introduced with ISO C99 and is by default
+allowed in GCC@.  It is not supported by ISO C90.  @xref{Mixed Labels and Declarations}.
+
+@item -Wshadow
+@opindex Wshadow
+@opindex Wno-shadow
+Warn whenever a local variable or type declaration shadows another
+variable, parameter, type, class member (in C++), or instance variable
+(in Objective-C) or whenever a built-in function is shadowed.  Note
+that in C++, the compiler warns if a local variable shadows an
+explicit typedef, but not if it shadows a struct/class/enum.
+If this warning is enabled, it includes also all instances of
+local shadowing.  This means that @option{-Wno-shadow=local}
+and @option{-Wno-shadow=compatible-local} are ignored when
+@option{-Wshadow} is used.
+Same as @option{-Wshadow=global}.
+
+@item -Wno-shadow-ivar @r{(Objective-C only)}
+@opindex Wno-shadow-ivar
+@opindex Wshadow-ivar
+Do not warn whenever a local variable shadows an instance variable in an
+Objective-C method.
+
+@item -Wshadow=global
+@opindex Wshadow=global
+Warn for any shadowing.
+Same as @option{-Wshadow}.
+
+@item -Wshadow=local
+@opindex Wshadow=local
+Warn when a local variable shadows another local variable or parameter.
+
+@item -Wshadow=compatible-local
+@opindex Wshadow=compatible-local
+Warn when a local variable shadows another local variable or parameter
+whose type is compatible with that of the shadowing variable.  In C++,
+type compatibility here means the type of the shadowing variable can be
+converted to that of the shadowed variable.  The creation of this flag
+(in addition to @option{-Wshadow=local}) is based on the idea that when
+a local variable shadows another one of incompatible type, it is most
+likely intentional, not a bug or typo, as shown in the following example:
+
+@smallexample
+@group
+for (SomeIterator i = SomeObj.begin(); i != SomeObj.end(); ++i)
+@{
+  for (int i = 0; i < N; ++i)
+  @{
+    ...
+  @}
+  ...
+@}
+@end group
+@end smallexample
+
+Since the two variable @code{i} in the example above have incompatible types,
+enabling only @option{-Wshadow=compatible-local} does not emit a warning.
+Because their types are incompatible, if a programmer accidentally uses one
+in place of the other, type checking is expected to catch that and emit an
+error or warning.  Use of this flag instead of @option{-Wshadow=local} can
+possibly reduce the number of warnings triggered by intentional shadowing.
+Note that this also means that shadowing @code{const char *i} by
+@code{char *i} does not emit a warning.
+
+This warning is also enabled by @option{-Wshadow=local}.
+
+@item -Wlarger-than=@var{byte-size}
+@opindex Wlarger-than=
+@opindex Wlarger-than-@var{byte-size}
+Warn whenever an object is defined whose size exceeds @var{byte-size}.
+@option{-Wlarger-than=}@samp{PTRDIFF_MAX} is enabled by default.
+Warnings controlled by the option can be disabled either by specifying
+@var{byte-size} of @samp{SIZE_MAX} or more or by @option{-Wno-larger-than}.
+
+Also warn for calls to bounded functions such as @code{memchr} or
+@code{strnlen} that specify a bound greater than the largest possible
+object, which is @samp{PTRDIFF_MAX} bytes by default.  These warnings
+can only be disabled by @option{-Wno-larger-than}.
+
+@item -Wno-larger-than
+@opindex Wno-larger-than
+Disable @option{-Wlarger-than=} warnings.  The option is equivalent
+to @option{-Wlarger-than=}@samp{SIZE_MAX} or larger.
+
+@item -Wframe-larger-than=@var{byte-size}
+@opindex Wframe-larger-than=
+@opindex Wno-frame-larger-than
+Warn if the size of a function frame exceeds @var{byte-size}.
+The computation done to determine the stack frame size is approximate
+and not conservative.
+The actual requirements may be somewhat greater than @var{byte-size}
+even if you do not get a warning.  In addition, any space allocated
+via @code{alloca}, variable-length arrays, or related constructs
+is not included by the compiler when determining
+whether or not to issue a warning.
+@option{-Wframe-larger-than=}@samp{PTRDIFF_MAX} is enabled by default.
+Warnings controlled by the option can be disabled either by specifying
+@var{byte-size} of @samp{SIZE_MAX} or more or by
+@option{-Wno-frame-larger-than}.
+
+@item -Wno-frame-larger-than
+@opindex Wno-frame-larger-than
+Disable @option{-Wframe-larger-than=} warnings.  The option is equivalent
+to @option{-Wframe-larger-than=}@samp{SIZE_MAX} or larger.
+
+@item -Wfree-nonheap-object
+@opindex Wfree-nonheap-object
+@opindex Wno-free-nonheap-object
+Warn when attempting to deallocate an object that was either not allocated
+on the heap, or by using a pointer that was not returned from a prior call
+to the corresponding allocation function.  For example, because the call
+to @code{stpcpy} returns a pointer to the terminating nul character and
+not to the beginning of the object, the call to @code{free} below is
+diagnosed.
+
+@smallexample
+void f (char *p)
+@{
+  p = stpcpy (p, "abc");
+  // ...
+  free (p);   // warning
+@}
+@end smallexample
+
+@option{-Wfree-nonheap-object} is included in @option{-Wall}.
+
+@item -Wstack-usage=@var{byte-size}
+@opindex Wstack-usage
+@opindex Wno-stack-usage
+Warn if the stack usage of a function might exceed @var{byte-size}.
+The computation done to determine the stack usage is conservative.
+Any space allocated via @code{alloca}, variable-length arrays, or related
+constructs is included by the compiler when determining whether or not to
+issue a warning.
+
+The message is in keeping with the output of @option{-fstack-usage}.
+
+@itemize
+@item
+If the stack usage is fully static but exceeds the specified amount, it's:
+
+@smallexample
+  warning: stack usage is 1120 bytes
+@end smallexample
+@item
+If the stack usage is (partly) dynamic but bounded, it's:
+
+@smallexample
+  warning: stack usage might be 1648 bytes
+@end smallexample
+@item
+If the stack usage is (partly) dynamic and not bounded, it's:
+
+@smallexample
+  warning: stack usage might be unbounded
+@end smallexample
+@end itemize
+
+@option{-Wstack-usage=}@samp{PTRDIFF_MAX} is enabled by default.
+Warnings controlled by the option can be disabled either by specifying
+@var{byte-size} of @samp{SIZE_MAX} or more or by
+@option{-Wno-stack-usage}.
+
+@item -Wno-stack-usage
+@opindex Wno-stack-usage
+Disable @option{-Wstack-usage=} warnings.  The option is equivalent
+to @option{-Wstack-usage=}@samp{SIZE_MAX} or larger.
+
+@item -Wunsafe-loop-optimizations
+@opindex Wunsafe-loop-optimizations
+@opindex Wno-unsafe-loop-optimizations
+Warn if the loop cannot be optimized because the compiler cannot
+assume anything on the bounds of the loop indices.  With
+@option{-funsafe-loop-optimizations} warn if the compiler makes
+such assumptions.
+
+@item -Wno-pedantic-ms-format @r{(MinGW targets only)}
+@opindex Wno-pedantic-ms-format
+@opindex Wpedantic-ms-format
+When used in combination with @option{-Wformat}
+and @option{-pedantic} without GNU extensions, this option
+disables the warnings about non-ISO @code{printf} / @code{scanf} format
+width specifiers @code{I32}, @code{I64}, and @code{I} used on Windows targets,
+which depend on the MS runtime.
+
+@item -Wpointer-arith
+@opindex Wpointer-arith
+@opindex Wno-pointer-arith
+Warn about anything that depends on the ``size of'' a function type or
+of @code{void}.  GNU C assigns these types a size of 1, for
+convenience in calculations with @code{void *} pointers and pointers
+to functions.  In C++, warn also when an arithmetic operation involves
+@code{NULL}.  This warning is also enabled by @option{-Wpedantic}.
+
+@item -Wno-pointer-compare
+@opindex Wpointer-compare
+@opindex Wno-pointer-compare
+Do not warn if a pointer is compared with a zero character constant.
+This usually
+means that the pointer was meant to be dereferenced.  For example:
+
+@smallexample
+const char *p = foo ();
+if (p == '\0')
+  return 42;
+@end smallexample
+
+Note that the code above is invalid in C++11.
+
+This warning is enabled by default.
+
+@item -Wtsan
+@opindex Wtsan
+@opindex Wno-tsan
+Warn about unsupported features in ThreadSanitizer.
+
+ThreadSanitizer does not support @code{std::atomic_thread_fence} and
+can report false positives.
+
+This warning is enabled by default.
+
+@item -Wtype-limits
+@opindex Wtype-limits
+@opindex Wno-type-limits
+Warn if a comparison is always true or always false due to the limited
+range of the data type, but do not warn for constant expressions.  For
+example, warn if an unsigned variable is compared against zero with
+@code{<} or @code{>=}.  This warning is also enabled by
+@option{-Wextra}.
+
+@item -Wabsolute-value @r{(C and Objective-C only)}
+@opindex Wabsolute-value
+@opindex Wno-absolute-value
+Warn for calls to standard functions that compute the absolute value
+of an argument when a more appropriate standard function is available.
+For example, calling @code{abs(3.14)} triggers the warning because the
+appropriate function to call to compute the absolute value of a double
+argument is @code{fabs}.  The option also triggers warnings when the
+argument in a call to such a function has an unsigned type.  This
+warning can be suppressed with an explicit type cast and it is also
+enabled by @option{-Wextra}.
+
+@include cppwarnopts.texi
+
+@item -Wbad-function-cast @r{(C and Objective-C only)}
+@opindex Wbad-function-cast
+@opindex Wno-bad-function-cast
+Warn when a function call is cast to a non-matching type.
+For example, warn if a call to a function returning an integer type 
+is cast to a pointer type.
+
+@item -Wc90-c99-compat @r{(C and Objective-C only)}
+@opindex Wc90-c99-compat
+@opindex Wno-c90-c99-compat
+Warn about features not present in ISO C90, but present in ISO C99.
+For instance, warn about use of variable length arrays, @code{long long}
+type, @code{bool} type, compound literals, designated initializers, and so
+on.  This option is independent of the standards mode.  Warnings are disabled
+in the expression that follows @code{__extension__}.
+
+@item -Wc99-c11-compat @r{(C and Objective-C only)}
+@opindex Wc99-c11-compat
+@opindex Wno-c99-c11-compat
+Warn about features not present in ISO C99, but present in ISO C11.
+For instance, warn about use of anonymous structures and unions,
+@code{_Atomic} type qualifier, @code{_Thread_local} storage-class specifier,
+@code{_Alignas} specifier, @code{Alignof} operator, @code{_Generic} keyword,
+and so on.  This option is independent of the standards mode.  Warnings are
+disabled in the expression that follows @code{__extension__}.
+
+@item -Wc11-c2x-compat @r{(C and Objective-C only)}
+@opindex Wc11-c2x-compat
+@opindex Wno-c11-c2x-compat
+Warn about features not present in ISO C11, but present in ISO C2X.
+For instance, warn about omitting the string in @code{_Static_assert},
+use of @samp{[[]]} syntax for attributes, use of decimal
+floating-point types, and so on.  This option is independent of the
+standards mode.  Warnings are disabled in the expression that follows
+@code{__extension__}.
+
+@item -Wc++-compat @r{(C and Objective-C only)}
+@opindex Wc++-compat
+@opindex Wno-c++-compat
+Warn about ISO C constructs that are outside of the common subset of
+ISO C and ISO C++, e.g.@: request for implicit conversion from
+@code{void *} to a pointer to non-@code{void} type.
+
+@item -Wc++11-compat @r{(C++ and Objective-C++ only)}
+@opindex Wc++11-compat
+@opindex Wno-c++11-compat
+Warn about C++ constructs whose meaning differs between ISO C++ 1998
+and ISO C++ 2011, e.g., identifiers in ISO C++ 1998 that are keywords
+in ISO C++ 2011.  This warning turns on @option{-Wnarrowing} and is
+enabled by @option{-Wall}.
+
+@item -Wc++14-compat @r{(C++ and Objective-C++ only)}
+@opindex Wc++14-compat
+@opindex Wno-c++14-compat
+Warn about C++ constructs whose meaning differs between ISO C++ 2011
+and ISO C++ 2014.  This warning is enabled by @option{-Wall}.
+
+@item -Wc++17-compat @r{(C++ and Objective-C++ only)}
+@opindex Wc++17-compat
+@opindex Wno-c++17-compat
+Warn about C++ constructs whose meaning differs between ISO C++ 2014
+and ISO C++ 2017.  This warning is enabled by @option{-Wall}.
+
+@item -Wc++20-compat @r{(C++ and Objective-C++ only)}
+@opindex Wc++20-compat
+@opindex Wno-c++20-compat
+Warn about C++ constructs whose meaning differs between ISO C++ 2017
+and ISO C++ 2020.  This warning is enabled by @option{-Wall}.
+
+@item -Wno-c++11-extensions @r{(C++ and Objective-C++ only)}
+@opindex Wc++11-extensions
+@opindex Wno-c++11-extensions
+Do not warn about C++11 constructs in code being compiled using
+an older C++ standard.  Even without this option, some C++11 constructs
+will only be diagnosed if @option{-Wpedantic} is used.
+
+@item -Wno-c++14-extensions @r{(C++ and Objective-C++ only)}
+@opindex Wc++14-extensions
+@opindex Wno-c++14-extensions
+Do not warn about C++14 constructs in code being compiled using
+an older C++ standard.  Even without this option, some C++14 constructs
+will only be diagnosed if @option{-Wpedantic} is used.
+
+@item -Wno-c++17-extensions @r{(C++ and Objective-C++ only)}
+@opindex Wc++17-extensions
+@opindex Wno-c++17-extensions
+Do not warn about C++17 constructs in code being compiled using
+an older C++ standard.  Even without this option, some C++17 constructs
+will only be diagnosed if @option{-Wpedantic} is used.
+
+@item -Wno-c++20-extensions @r{(C++ and Objective-C++ only)}
+@opindex Wc++20-extensions
+@opindex Wno-c++20-extensions
+Do not warn about C++20 constructs in code being compiled using
+an older C++ standard.  Even without this option, some C++20 constructs
+will only be diagnosed if @option{-Wpedantic} is used.
+
+@item -Wno-c++23-extensions @r{(C++ and Objective-C++ only)}
+@opindex Wc++23-extensions
+@opindex Wno-c++23-extensions
+Do not warn about C++23 constructs in code being compiled using
+an older C++ standard.  Even without this option, some C++23 constructs
+will only be diagnosed if @option{-Wpedantic} is used.
+
+@item -Wcast-qual
+@opindex Wcast-qual
+@opindex Wno-cast-qual
+Warn whenever a pointer is cast so as to remove a type qualifier from
+the target type.  For example, warn if a @code{const char *} is cast
+to an ordinary @code{char *}.
+
+Also warn when making a cast that introduces a type qualifier in an
+unsafe way.  For example, casting @code{char **} to @code{const char **}
+is unsafe, as in this example:
+
+@smallexample
+  /* p is char ** value.  */
+  const char **q = (const char **) p;
+  /* Assignment of readonly string to const char * is OK.  */
+  *q = "string";
+  /* Now char** pointer points to read-only memory.  */
+  **p = 'b';
+@end smallexample
+
+@item -Wcast-align
+@opindex Wcast-align
+@opindex Wno-cast-align
+Warn whenever a pointer is cast such that the required alignment of the
+target is increased.  For example, warn if a @code{char *} is cast to
+an @code{int *} on machines where integers can only be accessed at
+two- or four-byte boundaries.
+
+@item -Wcast-align=strict
+@opindex Wcast-align=strict
+Warn whenever a pointer is cast such that the required alignment of the
+target is increased.  For example, warn if a @code{char *} is cast to
+an @code{int *} regardless of the target machine.
+
+@item -Wcast-function-type
+@opindex Wcast-function-type
+@opindex Wno-cast-function-type
+Warn when a function pointer is cast to an incompatible function pointer.
+In a cast involving function types with a variable argument list only
+the types of initial arguments that are provided are considered.
+Any parameter of pointer-type matches any other pointer-type.  Any benign
+differences in integral types are ignored, like @code{int} vs.@: @code{long}
+on ILP32 targets.  Likewise type qualifiers are ignored.  The function
+type @code{void (*) (void)} is special and matches everything, which can
+be used to suppress this warning.
+In a cast involving pointer to member types this warning warns whenever
+the type cast is changing the pointer to member type.
+This warning is enabled by @option{-Wextra}.
+
+@item -Wwrite-strings
+@opindex Wwrite-strings
+@opindex Wno-write-strings
+When compiling C, give string constants the type @code{const
+char[@var{length}]} so that copying the address of one into a
+non-@code{const} @code{char *} pointer produces a warning.  These
+warnings help you find at compile time code that can try to write
+into a string constant, but only if you have been very careful about
+using @code{const} in declarations and prototypes.  Otherwise, it is
+just a nuisance. This is why we did not make @option{-Wall} request
+these warnings.
+
+When compiling C++, warn about the deprecated conversion from string
+literals to @code{char *}.  This warning is enabled by default for C++
+programs.
+
+@item -Wclobbered
+@opindex Wclobbered
+@opindex Wno-clobbered
+Warn for variables that might be changed by @code{longjmp} or
+@code{vfork}.  This warning is also enabled by @option{-Wextra}.
+
+@item -Wconversion
+@opindex Wconversion
+@opindex Wno-conversion
+Warn for implicit conversions that may alter a value. This includes
+conversions between real and integer, like @code{abs (x)} when
+@code{x} is @code{double}; conversions between signed and unsigned,
+like @code{unsigned ui = -1}; and conversions to smaller types, like
+@code{sqrtf (M_PI)}. Do not warn for explicit casts like @code{abs
+((int) x)} and @code{ui = (unsigned) -1}, or if the value is not
+changed by the conversion like in @code{abs (2.0)}.  Warnings about
+conversions between signed and unsigned integers can be disabled by
+using @option{-Wno-sign-conversion}.
+
+For C++, also warn for confusing overload resolution for user-defined
+conversions; and conversions that never use a type conversion
+operator: conversions to @code{void}, the same type, a base class or a
+reference to them. Warnings about conversions between signed and
+unsigned integers are disabled by default in C++ unless
+@option{-Wsign-conversion} is explicitly enabled.
+
+Warnings about conversion from arithmetic on a small type back to that
+type are only given with @option{-Warith-conversion}.
+
+@item -Wdangling-else
+@opindex Wdangling-else
+@opindex Wno-dangling-else
+Warn about constructions where there may be confusion to which
+@code{if} statement an @code{else} branch belongs.  Here is an example of
+such a case:
+
+@smallexample
+@group
+@{
+  if (a)
+    if (b)
+      foo ();
+  else
+    bar ();
+@}
+@end group
+@end smallexample
+
+In C/C++, every @code{else} branch belongs to the innermost possible
+@code{if} statement, which in this example is @code{if (b)}.  This is
+often not what the programmer expected, as illustrated in the above
+example by indentation the programmer chose.  When there is the
+potential for this confusion, GCC issues a warning when this flag
+is specified.  To eliminate the warning, add explicit braces around
+the innermost @code{if} statement so there is no way the @code{else}
+can belong to the enclosing @code{if}.  The resulting code
+looks like this:
+
+@smallexample
+@group
+@{
+  if (a)
+    @{
+      if (b)
+        foo ();
+      else
+        bar ();
+    @}
+@}
+@end group
+@end smallexample
+
+This warning is enabled by @option{-Wparentheses}.
+
+@item -Wdangling-pointer
+@itemx -Wdangling-pointer=@var{n}
+@opindex Wdangling-pointer
+@opindex Wno-dangling-pointer
+Warn about uses of pointers (or C++ references) to objects with automatic
+storage duration after their lifetime has ended.  This includes local
+variables declared in nested blocks, compound literals and other unnamed
+temporary objects.  In addition, warn about storing the address of such
+objects in escaped pointers.  The warning is enabled at all optimization
+levels but may yield different results with optimization than without.
+
+@table @gcctabopt
+@item -Wdangling-pointer=1
+At level 1 the warning diagnoses only unconditional uses of dangling pointers.
+For example
+@smallexample
+int f (int c1, int c2, x)
+@{
+  char *p = strchr ((char[])@{ c1, c2 @}, c3);
+  return p ? *p : 'x';   // warning: dangling pointer to a compound literal
+@}
+@end smallexample
+In the following function the store of the address of the local variable
+@code{x} in the escaped pointer @code{*p} also triggers the warning.
+@smallexample
+void g (int **p)
+@{
+  int x = 7;
+  *p = &x;   // warning: storing the address of a local variable in *p
+@}
+@end smallexample
+
+@item -Wdangling-pointer=2
+At level 2, in addition to unconditional uses the warning also diagnoses
+conditional uses of dangling pointers.
+
+For example, because the array @var{a} in the following function is out of
+scope when the pointer @var{s} that was set to point is used, the warning
+triggers at this level.
+
+@smallexample
+void f (char *s)
+@{
+  if (!s)
+    @{
+      char a[12] = "tmpname";
+      s = a;
+    @}
+  strcat (s, ".tmp");   // warning: dangling pointer to a may be used
+  ...
+@}
+@end smallexample
+@end table
+
+@option{-Wdangling-pointer=2} is included in @option{-Wall}.
+
+@item -Wdate-time
+@opindex Wdate-time
+@opindex Wno-date-time
+Warn when macros @code{__TIME__}, @code{__DATE__} or @code{__TIMESTAMP__}
+are encountered as they might prevent bit-wise-identical reproducible
+compilations.
+
+@item -Wempty-body
+@opindex Wempty-body
+@opindex Wno-empty-body
+Warn if an empty body occurs in an @code{if}, @code{else} or @code{do
+while} statement.  This warning is also enabled by @option{-Wextra}.
+
+@item -Wno-endif-labels
+@opindex Wendif-labels
+@opindex Wno-endif-labels
+Do not warn about stray tokens after @code{#else} and @code{#endif}.
+
+@item -Wenum-compare
+@opindex Wenum-compare
+@opindex Wno-enum-compare
+Warn about a comparison between values of different enumerated types.
+In C++ enumerated type mismatches in conditional expressions are also
+diagnosed and the warning is enabled by default.  In C this warning is 
+enabled by @option{-Wall}.
+
+@item -Wenum-conversion
+@opindex Wenum-conversion
+@opindex Wno-enum-conversion
+Warn when a value of enumerated type is implicitly converted to a 
+different enumerated type.  This warning is enabled by @option{-Wextra}
+in C@.
+
+@item -Wenum-int-mismatch @r{(C and Objective-C only)}
+@opindex Wenum-int-mismatch
+@opindex Wno-enum-int-mismatch
+Warn about mismatches between an enumerated type and an integer type in
+declarations.  For example:
+
+@smallexample
+enum E @{ l = -1, z = 0, g = 1 @};
+int foo(void);
+enum E foo(void);
+@end smallexample
+
+In C, an enumerated type is compatible with @code{char}, a signed
+integer type, or an unsigned integer type.  However, since the choice
+of the underlying type of an enumerated type is implementation-defined,
+such mismatches may cause portability issues.  In C++, such mismatches
+are an error.  In C, this warning is enabled by @option{-Wall} and
+@option{-Wc++-compat}.
+
+@item -Wjump-misses-init @r{(C, Objective-C only)}
+@opindex Wjump-misses-init
+@opindex Wno-jump-misses-init
+Warn if a @code{goto} statement or a @code{switch} statement jumps
+forward across the initialization of a variable, or jumps backward to a
+label after the variable has been initialized.  This only warns about
+variables that are initialized when they are declared.  This warning is
+only supported for C and Objective-C; in C++ this sort of branch is an
+error in any case.
+
+@option{-Wjump-misses-init} is included in @option{-Wc++-compat}.  It
+can be disabled with the @option{-Wno-jump-misses-init} option.
+
+@item -Wsign-compare
+@opindex Wsign-compare
+@opindex Wno-sign-compare
+@cindex warning for comparison of signed and unsigned values
+@cindex comparison of signed and unsigned values, warning
+@cindex signed and unsigned values, comparison warning
+Warn when a comparison between signed and unsigned values could produce
+an incorrect result when the signed value is converted to unsigned.
+In C++, this warning is also enabled by @option{-Wall}.  In C, it is
+also enabled by @option{-Wextra}.
+
+@item -Wsign-conversion
+@opindex Wsign-conversion
+@opindex Wno-sign-conversion
+Warn for implicit conversions that may change the sign of an integer
+value, like assigning a signed integer expression to an unsigned
+integer variable. An explicit cast silences the warning. In C, this
+option is enabled also by @option{-Wconversion}.
+
+@item -Wfloat-conversion
+@opindex Wfloat-conversion
+@opindex Wno-float-conversion
+Warn for implicit conversions that reduce the precision of a real value.
+This includes conversions from real to integer, and from higher precision
+real to lower precision real values.  This option is also enabled by
+@option{-Wconversion}.
+
+@item -Wno-scalar-storage-order
+@opindex Wno-scalar-storage-order
+@opindex Wscalar-storage-order
+Do not warn on suspicious constructs involving reverse scalar storage order.
+
+@item -Wsizeof-array-div
+@opindex Wsizeof-array-div
+@opindex Wno-sizeof-array-div
+Warn about divisions of two sizeof operators when the first one is applied
+to an array and the divisor does not equal the size of the array element.
+In such a case, the computation will not yield the number of elements in the
+array, which is likely what the user intended.  This warning warns e.g. about
+@smallexample
+int fn ()
+@{
+  int arr[10];
+  return sizeof (arr) / sizeof (short);
+@}
+@end smallexample
+
+This warning is enabled by @option{-Wall}.
+
+@item -Wsizeof-pointer-div
+@opindex Wsizeof-pointer-div
+@opindex Wno-sizeof-pointer-div
+Warn for suspicious divisions of two sizeof expressions that divide
+the pointer size by the element size, which is the usual way to compute
+the array size but won't work out correctly with pointers.  This warning
+warns e.g.@: about @code{sizeof (ptr) / sizeof (ptr[0])} if @code{ptr} is
+not an array, but a pointer.  This warning is enabled by @option{-Wall}.
+
+@item -Wsizeof-pointer-memaccess
+@opindex Wsizeof-pointer-memaccess
+@opindex Wno-sizeof-pointer-memaccess
+Warn for suspicious length parameters to certain string and memory built-in
+functions if the argument uses @code{sizeof}.  This warning triggers for
+example for @code{memset (ptr, 0, sizeof (ptr));} if @code{ptr} is not
+an array, but a pointer, and suggests a possible fix, or about
+@code{memcpy (&foo, ptr, sizeof (&foo));}.  @option{-Wsizeof-pointer-memaccess}
+also warns about calls to bounded string copy functions like @code{strncat}
+or @code{strncpy} that specify as the bound a @code{sizeof} expression of
+the source array.  For example, in the following function the call to
+@code{strncat} specifies the size of the source string as the bound.  That
+is almost certainly a mistake and so the call is diagnosed.
+@smallexample
+void make_file (const char *name)
+@{
+  char path[PATH_MAX];
+  strncpy (path, name, sizeof path - 1);
+  strncat (path, ".text", sizeof ".text");
+  @dots{}
+@}
+@end smallexample
+
+The @option{-Wsizeof-pointer-memaccess} option is enabled by @option{-Wall}.
+
+@item -Wno-sizeof-array-argument
+@opindex Wsizeof-array-argument
+@opindex Wno-sizeof-array-argument
+Do not warn when the @code{sizeof} operator is applied to a parameter that is
+declared as an array in a function definition.  This warning is enabled by
+default for C and C++ programs.
+
+@item -Wmemset-elt-size
+@opindex Wmemset-elt-size
+@opindex Wno-memset-elt-size
+Warn for suspicious calls to the @code{memset} built-in function, if the
+first argument references an array, and the third argument is a number
+equal to the number of elements, but not equal to the size of the array
+in memory.  This indicates that the user has omitted a multiplication by
+the element size.  This warning is enabled by @option{-Wall}.
+
+@item -Wmemset-transposed-args
+@opindex Wmemset-transposed-args
+@opindex Wno-memset-transposed-args
+Warn for suspicious calls to the @code{memset} built-in function where
+the second argument is not zero and the third argument is zero.  For
+example, the call @code{memset (buf, sizeof buf, 0)} is diagnosed because
+@code{memset (buf, 0, sizeof buf)} was meant instead.  The diagnostic
+is only emitted if the third argument is a literal zero.  Otherwise, if
+it is an expression that is folded to zero, or a cast of zero to some
+type, it is far less likely that the arguments have been mistakenly
+transposed and no warning is emitted.  This warning is enabled
+by @option{-Wall}.
+
+@item -Waddress
+@opindex Waddress
+@opindex Wno-address
+Warn about suspicious uses of address expressions. These include comparing
+the address of a function or a declared object to the null pointer constant
+such as in
+@smallexample
+void f (void);
+void g (void)
+@{
+  if (!f)   // warning: expression evaluates to false
+    abort ();
+@}
+@end smallexample
+comparisons of a pointer to a string literal, such as in
+@smallexample
+void f (const char *x)
+@{
+  if (x == "abc")   // warning: expression evaluates to false
+    puts ("equal");
+@}
+@end smallexample
+and tests of the results of pointer addition or subtraction for equality
+to null, such as in
+@smallexample
+void f (const int *p, int i)
+@{
+  return p + i == NULL;
+@}
+@end smallexample
+Such uses typically indicate a programmer error: the address of most
+functions and objects necessarily evaluates to true (the exception are
+weak symbols), so their use in a conditional might indicate missing
+parentheses in a function call or a missing dereference in an array
+expression.  The subset of the warning for object pointers can be
+suppressed by casting the pointer operand to an integer type such
+as @code{intptr_t} or @code{uintptr_t}.
+Comparisons against string literals result in unspecified behavior
+and are not portable, and suggest the intent was to call @code{strcmp}.
+The warning is suppressed if the suspicious expression is the result
+of macro expansion.
+@option{-Waddress} warning is enabled by @option{-Wall}.
+
+@item -Wno-address-of-packed-member
+@opindex Waddress-of-packed-member
+@opindex Wno-address-of-packed-member
+Do not warn when the address of packed member of struct or union is taken,
+which usually results in an unaligned pointer value.  This is
+enabled by default.
+
+@item -Wlogical-op
+@opindex Wlogical-op
+@opindex Wno-logical-op
+Warn about suspicious uses of logical operators in expressions.
+This includes using logical operators in contexts where a
+bit-wise operator is likely to be expected.  Also warns when
+the operands of a logical operator are the same:
+@smallexample
+extern int a;
+if (a < 0 && a < 0) @{ @dots{} @}
+@end smallexample
+
+@item -Wlogical-not-parentheses
+@opindex Wlogical-not-parentheses
+@opindex Wno-logical-not-parentheses
+Warn about logical not used on the left hand side operand of a comparison.
+This option does not warn if the right operand is considered to be a boolean
+expression.  Its purpose is to detect suspicious code like the following:
+@smallexample
+int a;
+@dots{}
+if (!a > 1) @{ @dots{} @}
+@end smallexample
+
+It is possible to suppress the warning by wrapping the LHS into
+parentheses:
+@smallexample
+if ((!a) > 1) @{ @dots{} @}
+@end smallexample
+
+This warning is enabled by @option{-Wall}.
+
+@item -Waggregate-return
+@opindex Waggregate-return
+@opindex Wno-aggregate-return
+Warn if any functions that return structures or unions are defined or
+called.  (In languages where you can return an array, this also elicits
+a warning.)
+
+@item -Wno-aggressive-loop-optimizations
+@opindex Wno-aggressive-loop-optimizations
+@opindex Waggressive-loop-optimizations
+Warn if in a loop with constant number of iterations the compiler detects
+undefined behavior in some statement during one or more of the iterations.
+
+@item -Wno-attributes
+@opindex Wno-attributes
+@opindex Wattributes
+Do not warn if an unexpected @code{__attribute__} is used, such as
+unrecognized attributes, function attributes applied to variables,
+etc.  This does not stop errors for incorrect use of supported
+attributes.
+
+Additionally, using @option{-Wno-attributes=}, it is possible to suppress
+warnings about unknown scoped attributes (in C++11 and C2X).  For example,
+@option{-Wno-attributes=vendor::attr} disables warning about the following
+declaration:
+
+@smallexample
+[[vendor::attr]] void f();
+@end smallexample
+
+It is also possible to disable warning about all attributes in a namespace
+using @option{-Wno-attributes=vendor::} which prevents warning about both
+of these declarations:
+
+@smallexample
+[[vendor::safe]] void f();
+[[vendor::unsafe]] void f2();
+@end smallexample
+
+Note that @option{-Wno-attributes=} does not imply @option{-Wno-attributes}.
+
+@item -Wno-builtin-declaration-mismatch
+@opindex Wno-builtin-declaration-mismatch
+@opindex Wbuiltin-declaration-mismatch
+Warn if a built-in function is declared with an incompatible signature
+or as a non-function, or when a built-in function declared with a type
+that does not include a prototype is called with arguments whose promoted
+types do not match those expected by the function.  When @option{-Wextra}
+is specified, also warn when a built-in function that takes arguments is
+declared without a prototype.  The @option{-Wbuiltin-declaration-mismatch}
+warning is enabled by default.  To avoid the warning include the appropriate
+header to bring the prototypes of built-in functions into scope.
+
+For example, the call to @code{memset} below is diagnosed by the warning
+because the function expects a value of type @code{size_t} as its argument
+but the type of @code{32} is @code{int}.  With @option{-Wextra},
+the declaration of the function is diagnosed as well.
+@smallexample
+extern void* memset ();
+void f (void *d)
+@{
+  memset (d, '\0', 32);
+@}
+@end smallexample
+
+@item -Wno-builtin-macro-redefined
+@opindex Wno-builtin-macro-redefined
+@opindex Wbuiltin-macro-redefined
+Do not warn if certain built-in macros are redefined.  This suppresses
+warnings for redefinition of @code{__TIMESTAMP__}, @code{__TIME__},
+@code{__DATE__}, @code{__FILE__}, and @code{__BASE_FILE__}.
+
+@item -Wstrict-prototypes @r{(C and Objective-C only)}
+@opindex Wstrict-prototypes
+@opindex Wno-strict-prototypes
+Warn if a function is declared or defined without specifying the
+argument types.  (An old-style function definition is permitted without
+a warning if preceded by a declaration that specifies the argument
+types.)
+
+@item -Wold-style-declaration @r{(C and Objective-C only)}
+@opindex Wold-style-declaration
+@opindex Wno-old-style-declaration
+Warn for obsolescent usages, according to the C Standard, in a
+declaration. For example, warn if storage-class specifiers like
+@code{static} are not the first things in a declaration.  This warning
+is also enabled by @option{-Wextra}.
+
+@item -Wold-style-definition @r{(C and Objective-C only)}
+@opindex Wold-style-definition
+@opindex Wno-old-style-definition
+Warn if an old-style function definition is used.  A warning is given
+even if there is a previous prototype.  A definition using @samp{()}
+is not considered an old-style definition in C2X mode, because it is
+equivalent to @samp{(void)} in that case, but is considered an
+old-style definition for older standards.
+
+@item -Wmissing-parameter-type @r{(C and Objective-C only)}
+@opindex Wmissing-parameter-type
+@opindex Wno-missing-parameter-type
+A function parameter is declared without a type specifier in K&R-style
+functions:
+
+@smallexample
+void foo(bar) @{ @}
+@end smallexample
+
+This warning is also enabled by @option{-Wextra}.
+
+@item -Wmissing-prototypes @r{(C and Objective-C only)}
+@opindex Wmissing-prototypes
+@opindex Wno-missing-prototypes
+Warn if a global function is defined without a previous prototype
+declaration.  This warning is issued even if the definition itself
+provides a prototype.  Use this option to detect global functions
+that do not have a matching prototype declaration in a header file.
+This option is not valid for C++ because all function declarations
+provide prototypes and a non-matching declaration declares an
+overload rather than conflict with an earlier declaration.
+Use @option{-Wmissing-declarations} to detect missing declarations in C++.
+
+@item -Wmissing-declarations
+@opindex Wmissing-declarations
+@opindex Wno-missing-declarations
+Warn if a global function is defined without a previous declaration.
+Do so even if the definition itself provides a prototype.
+Use this option to detect global functions that are not declared in
+header files.  In C, no warnings are issued for functions with previous
+non-prototype declarations; use @option{-Wmissing-prototypes} to detect
+missing prototypes.  In C++, no warnings are issued for function templates,
+or for inline functions, or for functions in anonymous namespaces.
+
+@item -Wmissing-field-initializers
+@opindex Wmissing-field-initializers
+@opindex Wno-missing-field-initializers
+@opindex W
+@opindex Wextra
+@opindex Wno-extra
+Warn if a structure's initializer has some fields missing.  For
+example, the following code causes such a warning, because
+@code{x.h} is implicitly zero:
+
+@smallexample
+struct s @{ int f, g, h; @};
+struct s x = @{ 3, 4 @};
+@end smallexample
+
+This option does not warn about designated initializers, so the following
+modification does not trigger a warning:
+
+@smallexample
+struct s @{ int f, g, h; @};
+struct s x = @{ .f = 3, .g = 4 @};
+@end smallexample
+
+In C this option does not warn about the universal zero initializer
+@samp{@{ 0 @}}:
+
+@smallexample
+struct s @{ int f, g, h; @};
+struct s x = @{ 0 @};
+@end smallexample
+
+Likewise, in C++ this option does not warn about the empty @{ @}
+initializer, for example:
+
+@smallexample
+struct s @{ int f, g, h; @};
+s x = @{ @};
+@end smallexample
+
+This warning is included in @option{-Wextra}.  To get other @option{-Wextra}
+warnings without this one, use @option{-Wextra -Wno-missing-field-initializers}.
+
+@item -Wno-missing-requires
+@opindex Wmissing-requires
+@opindex Wno-missing-requires
+
+By default, the compiler warns about a concept-id appearing as a C++20 simple-requirement:
+
+@smallexample
+bool satisfied = requires @{ C<T> @};
+@end smallexample
+
+Here @samp{satisfied} will be true if @samp{C<T>} is a valid
+expression, which it is for all T.  Presumably the user meant to write
+
+@smallexample
+bool satisfied = requires @{ requires C<T> @};
+@end smallexample
+
+so @samp{satisfied} is only true if concept @samp{C} is satisfied for
+type @samp{T}.
+
+This warning can be disabled with @option{-Wno-missing-requires}.
+
+@item -Wno-missing-template-keyword
+@opindex Wmissing-template-keyword
+@opindex Wno-missing-template-keyword
+
+The member access tokens ., -> and :: must be followed by the @code{template}
+keyword if the parent object is dependent and the member being named is a
+template.
+
+@smallexample
+template <class X>
+void DoStuff (X x)
+@{
+  x.template DoSomeOtherStuff<X>(); // Good.
+  x.DoMoreStuff<X>(); // Warning, x is dependent.
+@}
+@end smallexample
+
+In rare cases it is possible to get false positives. To silence this, wrap
+the expression in parentheses. For example, the following is treated as a
+template, even where m and N are integers:
+
+@smallexample
+void NotATemplate (my_class t)
+@{
+  int N = 5;
+
+  bool test = t.m < N > (0); // Treated as a template.
+  test = (t.m < N) > (0); // Same meaning, but not treated as a template.
+@}
+@end smallexample
+
+This warning can be disabled with @option{-Wno-missing-template-keyword}.
+
+@item -Wno-multichar
+@opindex Wno-multichar
+@opindex Wmultichar
+Do not warn if a multicharacter constant (@samp{'FOOF'}) is used.
+Usually they indicate a typo in the user's code, as they have
+implementation-defined values, and should not be used in portable code.
+
+@item -Wnormalized=@r{[}none@r{|}id@r{|}nfc@r{|}nfkc@r{]}
+@opindex Wnormalized=
+@opindex Wnormalized
+@opindex Wno-normalized
+@cindex NFC
+@cindex NFKC
+@cindex character set, input normalization
+In ISO C and ISO C++, two identifiers are different if they are
+different sequences of characters.  However, sometimes when characters
+outside the basic ASCII character set are used, you can have two
+different character sequences that look the same.  To avoid confusion,
+the ISO 10646 standard sets out some @dfn{normalization rules} which
+when applied ensure that two sequences that look the same are turned into
+the same sequence.  GCC can warn you if you are using identifiers that
+have not been normalized; this option controls that warning.
+
+There are four levels of warning supported by GCC@.  The default is
+@option{-Wnormalized=nfc}, which warns about any identifier that is
+not in the ISO 10646 ``C'' normalized form, @dfn{NFC}.  NFC is the
+recommended form for most uses.  It is equivalent to
+@option{-Wnormalized}.
+
+Unfortunately, there are some characters allowed in identifiers by
+ISO C and ISO C++ that, when turned into NFC, are not allowed in 
+identifiers.  That is, there's no way to use these symbols in portable
+ISO C or C++ and have all your identifiers in NFC@.
+@option{-Wnormalized=id} suppresses the warning for these characters.
+It is hoped that future versions of the standards involved will correct
+this, which is why this option is not the default.
+
+You can switch the warning off for all characters by writing
+@option{-Wnormalized=none} or @option{-Wno-normalized}.  You should
+only do this if you are using some other normalization scheme (like
+``D''), because otherwise you can easily create bugs that are
+literally impossible to see.
+
+Some characters in ISO 10646 have distinct meanings but look identical
+in some fonts or display methodologies, especially once formatting has
+been applied.  For instance @code{\u207F}, ``SUPERSCRIPT LATIN SMALL
+LETTER N'', displays just like a regular @code{n} that has been
+placed in a superscript.  ISO 10646 defines the @dfn{NFKC}
+normalization scheme to convert all these into a standard form as
+well, and GCC warns if your code is not in NFKC if you use
+@option{-Wnormalized=nfkc}.  This warning is comparable to warning
+about every identifier that contains the letter O because it might be
+confused with the digit 0, and so is not the default, but may be
+useful as a local coding convention if the programming environment 
+cannot be fixed to display these characters distinctly.
+
+@item -Wno-attribute-warning
+@opindex Wno-attribute-warning
+@opindex Wattribute-warning
+Do not warn about usage of functions (@pxref{Function Attributes})
+declared with @code{warning} attribute.  By default, this warning is
+enabled.  @option{-Wno-attribute-warning} can be used to disable the
+warning or @option{-Wno-error=attribute-warning} can be used to
+disable the error when compiled with @option{-Werror} flag.
+
+@item -Wno-deprecated
+@opindex Wno-deprecated
+@opindex Wdeprecated
+Do not warn about usage of deprecated features.  @xref{Deprecated Features}.
+
+@item -Wno-deprecated-declarations
+@opindex Wno-deprecated-declarations
+@opindex Wdeprecated-declarations
+Do not warn about uses of functions (@pxref{Function Attributes}),
+variables (@pxref{Variable Attributes}), and types (@pxref{Type
+Attributes}) marked as deprecated by using the @code{deprecated}
+attribute.
+
+@item -Wno-overflow
+@opindex Wno-overflow
+@opindex Woverflow
+Do not warn about compile-time overflow in constant expressions.
+
+@item -Wno-odr
+@opindex Wno-odr
+@opindex Wodr
+Warn about One Definition Rule violations during link-time optimization.
+Enabled by default.
+
+@item -Wopenacc-parallelism
+@opindex Wopenacc-parallelism
+@opindex Wno-openacc-parallelism
+@cindex OpenACC accelerator programming
+Warn about potentially suboptimal choices related to OpenACC parallelism.
+
+@item -Wopenmp-simd
+@opindex Wopenmp-simd
+@opindex Wno-openmp-simd
+Warn if the vectorizer cost model overrides the OpenMP
+simd directive set by user.  The @option{-fsimd-cost-model=unlimited}
+option can be used to relax the cost model.
+
+@item -Woverride-init @r{(C and Objective-C only)}
+@opindex Woverride-init
+@opindex Wno-override-init
+@opindex W
+@opindex Wextra
+@opindex Wno-extra
+Warn if an initialized field without side effects is overridden when
+using designated initializers (@pxref{Designated Inits, , Designated
+Initializers}).
+
+This warning is included in @option{-Wextra}.  To get other
+@option{-Wextra} warnings without this one, use @option{-Wextra
+-Wno-override-init}.
+
+@item -Wno-override-init-side-effects @r{(C and Objective-C only)}
+@opindex Woverride-init-side-effects
+@opindex Wno-override-init-side-effects
+Do not warn if an initialized field with side effects is overridden when
+using designated initializers (@pxref{Designated Inits, , Designated
+Initializers}).  This warning is enabled by default.
+
+@item -Wpacked
+@opindex Wpacked
+@opindex Wno-packed
+Warn if a structure is given the packed attribute, but the packed
+attribute has no effect on the layout or size of the structure.
+Such structures may be mis-aligned for little benefit.  For
+instance, in this code, the variable @code{f.x} in @code{struct bar}
+is misaligned even though @code{struct bar} does not itself
+have the packed attribute:
+
+@smallexample
+@group
+struct foo @{
+  int x;
+  char a, b, c, d;
+@} __attribute__((packed));
+struct bar @{
+  char z;
+  struct foo f;
+@};
+@end group
+@end smallexample
+
+@item -Wnopacked-bitfield-compat
+@opindex Wpacked-bitfield-compat
+@opindex Wno-packed-bitfield-compat
+The 4.1, 4.2 and 4.3 series of GCC ignore the @code{packed} attribute
+on bit-fields of type @code{char}.  This was fixed in GCC 4.4 but
+the change can lead to differences in the structure layout.  GCC
+informs you when the offset of such a field has changed in GCC 4.4.
+For example there is no longer a 4-bit padding between field @code{a}
+and @code{b} in this structure:
+
+@smallexample
+struct foo
+@{
+  char a:4;
+  char b:8;
+@} __attribute__ ((packed));
+@end smallexample
+
+This warning is enabled by default.  Use
+@option{-Wno-packed-bitfield-compat} to disable this warning.
+
+@item -Wpacked-not-aligned @r{(C, C++, Objective-C and Objective-C++ only)}
+@opindex Wpacked-not-aligned
+@opindex Wno-packed-not-aligned
+Warn if a structure field with explicitly specified alignment in a
+packed struct or union is misaligned.  For example, a warning will
+be issued on @code{struct S}, like, @code{warning: alignment 1 of
+'struct S' is less than 8}, in this code:
+
+@smallexample
+@group
+struct __attribute__ ((aligned (8))) S8 @{ char a[8]; @};
+struct __attribute__ ((packed)) S @{
+  struct S8 s8;
+@};
+@end group
+@end smallexample
+
+This warning is enabled by @option{-Wall}.
+
+@item -Wpadded
+@opindex Wpadded
+@opindex Wno-padded
+Warn if padding is included in a structure, either to align an element
+of the structure or to align the whole structure.  Sometimes when this
+happens it is possible to rearrange the fields of the structure to
+reduce the padding and so make the structure smaller.
+
+@item -Wredundant-decls
+@opindex Wredundant-decls
+@opindex Wno-redundant-decls
+Warn if anything is declared more than once in the same scope, even in
+cases where multiple declaration is valid and changes nothing.
+
+@item -Wrestrict
+@opindex Wrestrict
+@opindex Wno-restrict
+Warn when an object referenced by a @code{restrict}-qualified parameter
+(or, in C++, a @code{__restrict}-qualified parameter) is aliased by another
+argument, or when copies between such objects overlap.  For example,
+the call to the @code{strcpy} function below attempts to truncate the string
+by replacing its initial characters with the last four.  However, because
+the call writes the terminating NUL into @code{a[4]}, the copies overlap and
+the call is diagnosed.
+
+@smallexample
+void foo (void)
+@{
+  char a[] = "abcd1234";
+  strcpy (a, a + 4);
+  @dots{}
+@}
+@end smallexample
+The @option{-Wrestrict} option detects some instances of simple overlap
+even without optimization but works best at @option{-O2} and above.  It
+is included in @option{-Wall}.
+
+@item -Wnested-externs @r{(C and Objective-C only)}
+@opindex Wnested-externs
+@opindex Wno-nested-externs
+Warn if an @code{extern} declaration is encountered within a function.
+
+@item -Winline
+@opindex Winline
+@opindex Wno-inline
+Warn if a function that is declared as inline cannot be inlined.
+Even with this option, the compiler does not warn about failures to
+inline functions declared in system headers.
+
+The compiler uses a variety of heuristics to determine whether or not
+to inline a function.  For example, the compiler takes into account
+the size of the function being inlined and the amount of inlining
+that has already been done in the current function.  Therefore,
+seemingly insignificant changes in the source program can cause the
+warnings produced by @option{-Winline} to appear or disappear.
+
+@item -Winterference-size
+@opindex Winterference-size
+Warn about use of C++17 @code{std::hardware_destructive_interference_size}
+without specifying its value with @option{--param destructive-interference-size}.
+Also warn about questionable values for that option.
+
+This variable is intended to be used for controlling class layout, to
+avoid false sharing in concurrent code:
+
+@smallexample
+struct independent_fields @{
+  alignas(std::hardware_destructive_interference_size) std::atomic<int> one;
+  alignas(std::hardware_destructive_interference_size) std::atomic<int> two;
+@};
+@end smallexample
+
+Here @samp{one} and @samp{two} are intended to be far enough apart
+that stores to one won't require accesses to the other to reload the
+cache line.
+
+By default, @option{--param destructive-interference-size} and
+@option{--param constructive-interference-size} are set based on the
+current @option{-mtune} option, typically to the L1 cache line size
+for the particular target CPU, sometimes to a range if tuning for a
+generic target.  So all translation units that depend on ABI
+compatibility for the use of these variables must be compiled with
+the same @option{-mtune} (or @option{-mcpu}).
+
+If ABI stability is important, such as if the use is in a header for a
+library, you should probably not use the hardware interference size
+variables at all.  Alternatively, you can force a particular value
+with @option{--param}.
+
+If you are confident that your use of the variable does not affect ABI
+outside a single build of your project, you can turn off the warning
+with @option{-Wno-interference-size}.
+
+@item -Wint-in-bool-context
+@opindex Wint-in-bool-context
+@opindex Wno-int-in-bool-context
+Warn for suspicious use of integer values where boolean values are expected,
+such as conditional expressions (?:) using non-boolean integer constants in
+boolean context, like @code{if (a <= b ? 2 : 3)}.  Or left shifting of signed
+integers in boolean context, like @code{for (a = 0; 1 << a; a++);}.  Likewise
+for all kinds of multiplications regardless of the data type.
+This warning is enabled by @option{-Wall}.
+
+@item -Wno-int-to-pointer-cast
+@opindex Wno-int-to-pointer-cast
+@opindex Wint-to-pointer-cast
+Suppress warnings from casts to pointer type of an integer of a
+different size. In C++, casting to a pointer type of smaller size is
+an error. @option{Wint-to-pointer-cast} is enabled by default.
+
+
+@item -Wno-pointer-to-int-cast @r{(C and Objective-C only)}
+@opindex Wno-pointer-to-int-cast
+@opindex Wpointer-to-int-cast
+Suppress warnings from casts from a pointer to an integer type of a
+different size.
+
+@item -Winvalid-pch
+@opindex Winvalid-pch
+@opindex Wno-invalid-pch
+Warn if a precompiled header (@pxref{Precompiled Headers}) is found in
+the search path but cannot be used.
+
+@item -Winvalid-utf8
+@opindex Winvalid-utf8
+@opindex Wno-invalid-utf8
+Warn if an invalid UTF-8 character is found.
+This warning is on by default for C++23 if @option{-finput-charset=UTF-8}
+is used and turned into error with @option{-pedantic-errors}.
+
+@item -Wno-unicode
+@opindex Wunicode
+@opindex Wno-unicode
+Don't diagnose invalid forms of delimited or named escape sequences which are
+treated as separate tokens.  @option{Wunicode} is enabled by default.
+
+@item -Wlong-long
+@opindex Wlong-long
+@opindex Wno-long-long
+Warn if @code{long long} type is used.  This is enabled by either
+@option{-Wpedantic} or @option{-Wtraditional} in ISO C90 and C++98
+modes.  To inhibit the warning messages, use @option{-Wno-long-long}.
+
+@item -Wvariadic-macros
+@opindex Wvariadic-macros
+@opindex Wno-variadic-macros
+Warn if variadic macros are used in ISO C90 mode, or if the GNU
+alternate syntax is used in ISO C99 mode.  This is enabled by either
+@option{-Wpedantic} or @option{-Wtraditional}.  To inhibit the warning
+messages, use @option{-Wno-variadic-macros}.
+
+@item -Wno-varargs
+@opindex Wvarargs
+@opindex Wno-varargs
+Do not warn upon questionable usage of the macros used to handle variable
+arguments like @code{va_start}.  These warnings are enabled by default.
+
+@item -Wvector-operation-performance
+@opindex Wvector-operation-performance
+@opindex Wno-vector-operation-performance
+Warn if vector operation is not implemented via SIMD capabilities of the
+architecture.  Mainly useful for the performance tuning.
+Vector operation can be implemented @code{piecewise}, which means that the
+scalar operation is performed on every vector element; 
+@code{in parallel}, which means that the vector operation is implemented
+using scalars of wider type, which normally is more performance efficient;
+and @code{as a single scalar}, which means that vector fits into a
+scalar type.
+
+@item -Wvla
+@opindex Wvla
+@opindex Wno-vla
+Warn if a variable-length array is used in the code.
+@option{-Wno-vla} prevents the @option{-Wpedantic} warning of
+the variable-length array.
+
+@item -Wvla-larger-than=@var{byte-size}
+@opindex Wvla-larger-than=
+@opindex Wno-vla-larger-than
+If this option is used, the compiler warns for declarations of
+variable-length arrays whose size is either unbounded, or bounded
+by an argument that allows the array size to exceed @var{byte-size}
+bytes.  This is similar to how @option{-Walloca-larger-than=}@var{byte-size}
+works, but with variable-length arrays.
+
+Note that GCC may optimize small variable-length arrays of a known
+value into plain arrays, so this warning may not get triggered for
+such arrays.
+
+@option{-Wvla-larger-than=}@samp{PTRDIFF_MAX} is enabled by default but
+is typically only effective when @option{-ftree-vrp} is active (default
+for @option{-O2} and above).
+
+See also @option{-Walloca-larger-than=@var{byte-size}}.
+
+@item -Wno-vla-larger-than
+@opindex Wno-vla-larger-than
+Disable @option{-Wvla-larger-than=} warnings.  The option is equivalent
+to @option{-Wvla-larger-than=}@samp{SIZE_MAX} or larger.
+
+@item -Wvla-parameter
+@opindex Wno-vla-parameter
+Warn about redeclarations of functions involving arguments of Variable
+Length Array types of inconsistent kinds or forms, and enable the detection
+of out-of-bounds accesses to such parameters by warnings such as
+@option{-Warray-bounds}.
+
+If the first function declaration uses the VLA form the bound specified
+in the array is assumed to be the minimum number of elements expected to
+be provided in calls to the function and the maximum number of elements
+accessed by it.  Failing to provide arguments of sufficient size or
+accessing more than the maximum number of elements may be diagnosed.
+
+For example, the warning triggers for the following redeclarations because
+the first one allows an array of any size to be passed to @code{f} while
+the second one specifies that the array argument must have at least @code{n}
+elements.  In addition, calling @code{f} with the associated VLA bound
+parameter in excess of the actual VLA bound triggers a warning as well.
+
+@smallexample
+void f (int n, int[n]);
+void f (int, int[]);     // warning: argument 2 previously declared as a VLA
+
+void g (int n)
+@{
+    if (n > 4)
+      return;
+    int a[n];
+    f (sizeof a, a);     // warning: access to a by f may be out of bounds
+  @dots{}
+@}
+
+@end smallexample
+
+@option{-Wvla-parameter} is included in @option{-Wall}.  The
+@option{-Warray-parameter} option triggers warnings for similar problems
+involving ordinary array arguments.
+
+@item -Wvolatile-register-var
+@opindex Wvolatile-register-var
+@opindex Wno-volatile-register-var
+Warn if a register variable is declared volatile.  The volatile
+modifier does not inhibit all optimizations that may eliminate reads
+and/or writes to register variables.  This warning is enabled by
+@option{-Wall}.
+
+@item -Wxor-used-as-pow @r{(C, C++, Objective-C and Objective-C++ only)}
+@opindex Wxor-used-as-pow
+@opindex Wno-xor-used-as-pow
+Warn about uses of @code{^}, the exclusive or operator, where it appears
+the user meant exponentiation.  Specifically, the warning occurs when the
+left-hand side is the decimal constant 2 or 10 and the right-hand side
+is also a decimal constant.
+
+In C and C++, @code{^} means exclusive or, whereas in some other languages
+(e.g. TeX and some versions of BASIC) it means exponentiation.
+
+This warning is enabled by default.  It can be silenced by converting one
+of the operands to hexadecimal.
+
+@item -Wdisabled-optimization
+@opindex Wdisabled-optimization
+@opindex Wno-disabled-optimization
+Warn if a requested optimization pass is disabled.  This warning does
+not generally indicate that there is anything wrong with your code; it
+merely indicates that GCC's optimizers are unable to handle the code
+effectively.  Often, the problem is that your code is too big or too
+complex; GCC refuses to optimize programs when the optimization
+itself is likely to take inordinate amounts of time.
+
+@item -Wpointer-sign @r{(C and Objective-C only)}
+@opindex Wpointer-sign
+@opindex Wno-pointer-sign
+Warn for pointer argument passing or assignment with different signedness.
+This option is only supported for C and Objective-C@.  It is implied by
+@option{-Wall} and by @option{-Wpedantic}, which can be disabled with
+@option{-Wno-pointer-sign}.
+
+@item -Wstack-protector
+@opindex Wstack-protector
+@opindex Wno-stack-protector
+This option is only active when @option{-fstack-protector} is active.  It
+warns about functions that are not protected against stack smashing.
+
+@item -Woverlength-strings
+@opindex Woverlength-strings
+@opindex Wno-overlength-strings
+Warn about string constants that are longer than the ``minimum
+maximum'' length specified in the C standard.  Modern compilers
+generally allow string constants that are much longer than the
+standard's minimum limit, but very portable programs should avoid
+using longer strings.
+
+The limit applies @emph{after} string constant concatenation, and does
+not count the trailing NUL@.  In C90, the limit was 509 characters; in
+C99, it was raised to 4095.  C++98 does not specify a normative
+minimum maximum, so we do not diagnose overlength strings in C++@.
+
+This option is implied by @option{-Wpedantic}, and can be disabled with
+@option{-Wno-overlength-strings}.
+
+@item -Wunsuffixed-float-constants @r{(C and Objective-C only)}
+@opindex Wunsuffixed-float-constants
+@opindex Wno-unsuffixed-float-constants
+
+Issue a warning for any floating constant that does not have
+a suffix.  When used together with @option{-Wsystem-headers} it
+warns about such constants in system header files.  This can be useful
+when preparing code to use with the @code{FLOAT_CONST_DECIMAL64} pragma
+from the decimal floating-point extension to C99.
+
+@item -Wno-lto-type-mismatch
+@opindex Wlto-type-mismatch
+@opindex Wno-lto-type-mismatch
+
+During the link-time optimization, do not warn about type mismatches in
+global declarations from different compilation units.
+Requires @option{-flto} to be enabled.  Enabled by default.
+
+@item -Wno-designated-init @r{(C and Objective-C only)}
+@opindex Wdesignated-init
+@opindex Wno-designated-init
+Suppress warnings when a positional initializer is used to initialize
+a structure that has been marked with the @code{designated_init}
+attribute.
+
+@end table
+
+@node Static Analyzer Options
+@section Options That Control Static Analysis
+
+@table @gcctabopt
+@item -fanalyzer
+@opindex analyzer
+@opindex fanalyzer
+@opindex fno-analyzer
+This option enables an static analysis of program flow which looks
+for ``interesting'' interprocedural paths through the
+code, and issues warnings for problems found on them.
+
+This analysis is much more expensive than other GCC warnings.
+
+Enabling this option effectively enables the following warnings:
+
+@gccoptlist{ @gol
+-Wanalyzer-allocation-size @gol
+-Wanalyzer-double-fclose @gol
+-Wanalyzer-double-free @gol
+-Wanalyzer-exposure-through-output-file @gol
+-Wanalyzer-exposure-through-uninit-copy @gol
+-Wanalyzer-fd-access-mode-mismatch @gol
+-Wanalyzer-fd-double-close @gol
+-Wanalyzer-fd-leak @gol
+-Wanalyzer-fd-use-after-close @gol
+-Wanalyzer-fd-use-without-check @gol
+-Wanalyzer-file-leak @gol
+-Wanalyzer-free-of-non-heap @gol
+-Wanalyzer-imprecise-fp-arithmetic @gol
+-Wanalyzer-jump-through-null @gol
+-Wanalyzer-malloc-leak @gol
+-Wanalyzer-mismatching-deallocation @gol
+-Wanalyzer-null-argument @gol
+-Wanalyzer-null-dereference @gol
+-Wanalyzer-out-of-bounds @gol
+-Wanalyzer-possible-null-argument @gol
+-Wanalyzer-possible-null-dereference @gol
+-Wanalyzer-putenv-of-auto-var @gol
+-Wanalyzer-shift-count-negative @gol
+-Wanalyzer-shift-count-overflow @gol
+-Wanalyzer-stale-setjmp-buffer @gol
+-Wanalyzer-unsafe-call-within-signal-handler @gol
+-Wanalyzer-use-after-free @gol
+-Wanalyzer-use-of-pointer-in-stale-stack-frame @gol
+-Wanalyzer-use-of-uninitialized-value @gol
+-Wanalyzer-va-arg-type-mismatch @gol
+-Wanalyzer-va-list-exhausted @gol
+-Wanalyzer-va-list-leak @gol
+-Wanalyzer-va-list-use-after-va-end @gol
+-Wanalyzer-write-to-const @gol
+-Wanalyzer-write-to-string-literal @gol
+}
+@ignore
+-Wanalyzer-tainted-allocation-size @gol
+-Wanalyzer-tainted-array-index @gol
+-Wanalyzer-tainted-divisor @gol
+-Wanalyzer-tainted-offset @gol
+-Wanalyzer-tainted-size @gol
+@end ignore
+
+This option is only available if GCC was configured with analyzer
+support enabled.
+
+@item -Wanalyzer-too-complex
+@opindex Wanalyzer-too-complex
+@opindex Wno-analyzer-too-complex
+If @option{-fanalyzer} is enabled, the analyzer uses various heuristics
+to attempt to explore the control flow and data flow in the program,
+but these can be defeated by sufficiently complicated code.
+
+By default, the analysis silently stops if the code is too
+complicated for the analyzer to fully explore and it reaches an internal
+limit.  The @option{-Wanalyzer-too-complex} option warns if this occurs.
+
+@item -Wno-analyzer-allocation-size
+@opindex Wanalyzer-allocation-size
+@opindex Wno-analyzer-allocation-size
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-allocation-size}
+to disable it.
+
+This diagnostic warns for paths through the code in which a pointer to
+a buffer is assigned to point at a buffer with a size that is not a
+multiple of @code{sizeof (*pointer)}.
+
+See @uref{https://cwe.mitre.org/data/definitions/131.html, CWE-131: Incorrect Calculation of Buffer Size}.
+
+@item -Wno-analyzer-double-fclose
+@opindex Wanalyzer-double-fclose
+@opindex Wno-analyzer-double-fclose
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-double-fclose} to disable it.
+
+This diagnostic warns for paths through the code in which a @code{FILE *}
+can have @code{fclose} called on it more than once.
+
+See @uref{https://cwe.mitre.org/data/definitions/1341.html, CWE-1341: Multiple Releases of Same Resource or Handle}.
+
+@item -Wno-analyzer-double-free
+@opindex Wanalyzer-double-free
+@opindex Wno-analyzer-double-free
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-double-free} to disable it.
+
+This diagnostic warns for paths through the code in which a pointer
+can have a deallocator called on it more than once, either @code{free},
+or a deallocator referenced by attribute @code{malloc}.
+
+See @uref{https://cwe.mitre.org/data/definitions/415.html, CWE-415: Double Free}.
+
+@item -Wno-analyzer-exposure-through-output-file
+@opindex Wanalyzer-exposure-through-output-file
+@opindex Wno-analyzer-exposure-through-output-file
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-exposure-through-output-file}
+to disable it.
+
+This diagnostic warns for paths through the code in which a
+security-sensitive value is written to an output file
+(such as writing a password to a log file).
+
+See @uref{https://cwe.mitre.org/data/definitions/532.html, CWE-532: Information Exposure Through Log Files}.
+
+@item -Wanalyzer-exposure-through-uninit-copy
+@opindex Wanalyzer-exposure-through-uninit-copy
+@opindex Wno-analyzer-exposure-through-uninit-copy
+This warning requires both @option{-fanalyzer} and the use of a plugin
+to specify a function that copies across a ``trust boundary''.  Use
+@option{-Wno-analyzer-exposure-through-uninit-copy} to disable it.
+
+This diagnostic warns for ``infoleaks'' - paths through the code in which
+uninitialized values are copied across a security boundary
+(such as code within an OS kernel that copies a partially-initialized
+struct on the stack to user space).
+
+See @uref{https://cwe.mitre.org/data/definitions/200.html, CWE-200: Exposure of Sensitive Information to an Unauthorized Actor}.
+
+@item -Wno-analyzer-fd-access-mode-mismatch
+@opindex Wanalyzer-fd-access-mode-mismatch
+@opindex Wno-analyzer-fd-access-mode-mismatch
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-fd-access-mode-mismatch}
+to disable it.
+
+This diagnostic warns for paths through code in which a
+@code{read} on a write-only file descriptor is attempted, or vice versa.
+
+This diagnostic also warns for code paths in a which a function with attribute
+@code{fd_arg_read (N)} is called with a file descriptor opened with
+@code{O_WRONLY} at referenced argument @code{N} or a function with attribute
+@code{fd_arg_write (N)} is called with a file descriptor opened with
+@code{O_RDONLY} at referenced argument @var{N}.
+
+@item -Wno-analyzer-fd-double-close
+@opindex Wanalyzer-fd-double-close
+@opindex Wno-analyzer-fd-double-close
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-fd-double-close}
+to disable it.
+
+This diagnostic warns for paths through code in which a
+file descriptor can be closed more than once.
+
+See @uref{https://cwe.mitre.org/data/definitions/1341.html, CWE-1341: Multiple Releases of Same Resource or Handle}.
+
+@item -Wno-analyzer-fd-leak
+@opindex Wanalyzer-fd-leak
+@opindex Wno-analyzer-fd-leak
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-fd-leak}
+to disable it.
+
+This diagnostic warns for paths through code in which an
+open file descriptor is leaked.
+
+See @uref{https://cwe.mitre.org/data/definitions/775.html, CWE-775: Missing Release of File Descriptor or Handle after Effective Lifetime}.
+
+@item -Wno-analyzer-fd-use-after-close
+@opindex Wanalyzer-fd-use-after-close
+@opindex Wno-analyzer-fd-use-after-close
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-fd-use-after-close}
+to disable it.
+
+This diagnostic warns for paths through code in which a
+read or write is called on a closed file descriptor.
+
+This diagnostic also warns for paths through code in which
+a function with attribute @code{fd_arg (N)} or @code{fd_arg_read (N)}
+or @code{fd_arg_write (N)} is called with a closed file descriptor at
+referenced argument @code{N}.
+
+@item -Wno-analyzer-fd-use-without-check
+@opindex Wanalyzer-fd-use-without-check
+@opindex Wno-analyzer-fd-use-without-check
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-fd-use-without-check}
+to disable it.
+
+This diagnostic warns for paths through code in which a
+file descriptor is used without being checked for validity.
+
+This diagnostic also warns for paths through code in which
+a function with attribute @code{fd_arg (N)} or @code{fd_arg_read (N)}
+or @code{fd_arg_write (N)} is called with a file descriptor, at referenced
+argument @code{N}, without being checked for validity.
+
+@item -Wno-analyzer-file-leak
+@opindex Wanalyzer-file-leak
+@opindex Wno-analyzer-file-leak
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-file-leak}
+to disable it.
+
+This diagnostic warns for paths through the code in which a
+@code{<stdio.h>} @code{FILE *} stream object is leaked.
+
+See @uref{https://cwe.mitre.org/data/definitions/775.html, CWE-775: Missing Release of File Descriptor or Handle after Effective Lifetime}.
+
+@item -Wno-analyzer-free-of-non-heap
+@opindex Wanalyzer-free-of-non-heap
+@opindex Wno-analyzer-free-of-non-heap
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-free-of-non-heap}
+to disable it.
+
+This diagnostic warns for paths through the code in which @code{free}
+is called on a non-heap pointer (e.g. an on-stack buffer, or a global).
+
+See @uref{https://cwe.mitre.org/data/definitions/590.html, CWE-590: Free of Memory not on the Heap}.
+
+@item -Wno-analyzer-imprecise-fp-arithmetic
+@opindex Wanalyzer-imprecise-fp-arithmetic
+@opindex Wno-analyzer-imprecise-fp-arithmetic
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-imprecise-fp-arithmetic}
+to disable it.
+
+This diagnostic warns for paths through the code in which floating-point
+arithmetic is used in locations where precise computation is needed.  This
+diagnostic only warns on use of floating-point operands inside the
+calculation of an allocation size at the moment.
+
+@item -Wno-analyzer-jump-through-null
+@opindex Wanalyzer-jump-through-null
+@opindex Wno-analyzer-jump-through-null
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-jump-through-null}
+to disable it.
+
+This diagnostic warns for paths through the code in which a @code{NULL}
+function pointer is called.
+
+@item -Wno-analyzer-malloc-leak
+@opindex Wanalyzer-malloc-leak
+@opindex Wno-analyzer-malloc-leak
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-malloc-leak}
+to disable it.
+
+This diagnostic warns for paths through the code in which a
+pointer allocated via an allocator is leaked: either @code{malloc},
+or a function marked with attribute @code{malloc}.
+
+See @uref{https://cwe.mitre.org/data/definitions/401.html, CWE-401: Missing Release of Memory after Effective Lifetime}.
+
+@item -Wno-analyzer-mismatching-deallocation
+@opindex Wanalyzer-mismatching-deallocation
+@opindex Wno-analyzer-mismatching-deallocation
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-mismatching-deallocation}
+to disable it.
+
+This diagnostic warns for paths through the code in which the
+wrong deallocation function is called on a pointer value, based on
+which function was used to allocate the pointer value.  The diagnostic
+will warn about mismatches between @code{free}, scalar @code{delete}
+and vector @code{delete[]}, and those marked as allocator/deallocator
+pairs using attribute @code{malloc}.
+
+See @uref{https://cwe.mitre.org/data/definitions/762.html, CWE-762: Mismatched Memory Management Routines}.
+
+@item -Wno-analyzer-out-of-bounds
+@opindex Wanalyzer-out-of-bounds
+@opindex Wno-analyzer-out-of-bounds
+This warning requires @option{-fanalyzer} to enable it; use
+@option{-Wno-analyzer-out-of-bounds} to disable it.
+
+This diagnostic warns for path through the code in which a buffer is
+definitely read or written out-of-bounds.  The diagnostic applies for
+cases where the analyzer is able to determine a constant offset and for
+accesses past the end of a buffer, also a constant capacity.  Further,
+the diagnostic does limited checking for accesses past the end when the
+offset as well as the capacity is symbolic.
+
+See @uref{https://cwe.mitre.org/data/definitions/119.html, CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer}.
+
+@item -Wno-analyzer-possible-null-argument
+@opindex Wanalyzer-possible-null-argument
+@opindex Wno-analyzer-possible-null-argument
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-possible-null-argument} to disable it.
+
+This diagnostic warns for paths through the code in which a
+possibly-NULL value is passed to a function argument marked
+with @code{__attribute__((nonnull))} as requiring a non-NULL
+value.
+
+See @uref{https://cwe.mitre.org/data/definitions/690.html, CWE-690: Unchecked Return Value to NULL Pointer Dereference}.
+
+@item -Wno-analyzer-possible-null-dereference
+@opindex Wanalyzer-possible-null-dereference
+@opindex Wno-analyzer-possible-null-dereference
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-possible-null-dereference} to disable it.
+
+This diagnostic warns for paths through the code in which a
+possibly-NULL value is dereferenced.
+
+See @uref{https://cwe.mitre.org/data/definitions/690.html, CWE-690: Unchecked Return Value to NULL Pointer Dereference}.
+
+@item -Wno-analyzer-null-argument
+@opindex Wanalyzer-null-argument
+@opindex Wno-analyzer-null-argument
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-null-argument} to disable it.
+
+This diagnostic warns for paths through the code in which a
+value known to be NULL is passed to a function argument marked
+with @code{__attribute__((nonnull))} as requiring a non-NULL
+value.
+
+See @uref{https://cwe.mitre.org/data/definitions/476.html, CWE-476: NULL Pointer Dereference}.
+
+@item -Wno-analyzer-null-dereference
+@opindex Wanalyzer-null-dereference
+@opindex Wno-analyzer-null-dereference
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-null-dereference} to disable it.
+
+This diagnostic warns for paths through the code in which a
+value known to be NULL is dereferenced.
+
+See @uref{https://cwe.mitre.org/data/definitions/476.html, CWE-476: NULL Pointer Dereference}.
+
+@item -Wno-analyzer-putenv-of-auto-var
+@opindex Wanalyzer-putenv-of-auto-var
+@opindex Wno-analyzer-putenv-of-auto-var
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-putenv-of-auto-var} to disable it.
+
+This diagnostic warns for paths through the code in which a
+call to @code{putenv} is passed a pointer to an automatic variable
+or an on-stack buffer.
+
+See @uref{https://wiki.sei.cmu.edu/confluence/x/6NYxBQ, POS34-C. Do not call putenv() with a pointer to an automatic variable as the argument}.
+
+@item -Wno-analyzer-shift-count-negative
+@opindex Wanalyzer-shift-count-negative
+@opindex Wno-analyzer-shift-count-negative
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-shift-count-negative} to disable it.
+
+This diagnostic warns for paths through the code in which a
+shift is attempted with a negative count.  It is analogous to
+the @option{-Wshift-count-negative} diagnostic implemented in
+the C/C++ front ends, but is implemented based on analyzing
+interprocedural paths, rather than merely parsing the syntax tree.
+However, the analyzer does not prioritize detection of such paths, so
+false negatives are more likely relative to other warnings.
+
+@item -Wno-analyzer-shift-count-overflow
+@opindex Wanalyzer-shift-count-overflow
+@opindex Wno-analyzer-shift-count-overflow
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-shift-count-overflow} to disable it.
+
+This diagnostic warns for paths through the code in which a
+shift is attempted with a count greater than or equal to the
+precision of the operand's type.  It is analogous to
+the @option{-Wshift-count-overflow} diagnostic implemented in
+the C/C++ front ends, but is implemented based on analyzing
+interprocedural paths, rather than merely parsing the syntax tree.
+However, the analyzer does not prioritize detection of such paths, so
+false negatives are more likely relative to other warnings.
+
+@item -Wno-analyzer-stale-setjmp-buffer
+@opindex Wanalyzer-stale-setjmp-buffer
+@opindex Wno-analyzer-stale-setjmp-buffer
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-stale-setjmp-buffer} to disable it.
+
+This diagnostic warns for paths through the code in which
+@code{longjmp} is called to rewind to a @code{jmp_buf} relating
+to a @code{setjmp} call in a function that has returned.
+
+When @code{setjmp} is called on a @code{jmp_buf} to record a rewind
+location, it records the stack frame.  The stack frame becomes invalid
+when the function containing the @code{setjmp} call returns.  Attempting
+to rewind to it via @code{longjmp} would reference a stack frame that
+no longer exists, and likely lead to a crash (or worse).
+
+@item -Wno-analyzer-tainted-allocation-size
+@opindex Wanalyzer-tainted-allocation-size
+@opindex Wno-analyzer-tainted-allocation-size
+This warning requires both @option{-fanalyzer} and
+@option{-fanalyzer-checker=taint} to enable it;
+use @option{-Wno-analyzer-tainted-allocation-size} to disable it.
+
+This diagnostic warns for paths through the code in which a value
+that could be under an attacker's control is used as the size
+of an allocation without being sanitized, so that an attacker could
+inject an excessively large allocation and potentially cause a denial
+of service attack.
+
+See @uref{https://cwe.mitre.org/data/definitions/789.html, CWE-789: Memory Allocation with Excessive Size Value}.
+
+@item -Wno-analyzer-tainted-array-index
+@opindex Wanalyzer-tainted-array-index
+@opindex Wno-analyzer-tainted-array-index
+This warning requires both @option{-fanalyzer} and
+@option{-fanalyzer-checker=taint} to enable it;
+use @option{-Wno-analyzer-tainted-array-index} to disable it.
+
+This diagnostic warns for paths through the code in which a value
+that could be under an attacker's control is used as the index
+of an array access without being sanitized, so that an attacker
+could inject an out-of-bounds access.
+
+See @uref{https://cwe.mitre.org/data/definitions/129.html, CWE-129: Improper Validation of Array Index}.
+
+@item -Wno-analyzer-tainted-divisor
+@opindex Wanalyzer-tainted-divisor
+@opindex Wno-analyzer-tainted-divisor
+This warning requires both @option{-fanalyzer} and
+@option{-fanalyzer-checker=taint} to enable it;
+use @option{-Wno-analyzer-tainted-divisor} to disable it.
+
+This diagnostic warns for paths through the code in which a value
+that could be under an attacker's control is used as the divisor
+in a division or modulus operation without being sanitized, so that
+an attacker could inject a division-by-zero.
+
+See @uref{https://cwe.mitre.org/data/definitions/369.html, CWE-369: Divide By Zero}.
+
+@item -Wno-analyzer-tainted-offset
+@opindex Wanalyzer-tainted-offset
+@opindex Wno-analyzer-tainted-offset
+This warning requires both @option{-fanalyzer} and
+@option{-fanalyzer-checker=taint} to enable it;
+use @option{-Wno-analyzer-tainted-offset} to disable it.
+
+This diagnostic warns for paths through the code in which a value
+that could be under an attacker's control is used as a pointer offset
+without being sanitized, so that an attacker could inject an out-of-bounds
+access.
+
+See @uref{https://cwe.mitre.org/data/definitions/823.html, CWE-823: Use of Out-of-range Pointer Offset}.
+
+@item -Wno-analyzer-tainted-size
+@opindex Wanalyzer-tainted-size
+@opindex Wno-analyzer-tainted-size
+This warning requires both @option{-fanalyzer} and
+@option{-fanalyzer-checker=taint} to enable it;
+use @option{-Wno-analyzer-tainted-size} to disable it.
+
+This diagnostic warns for paths through the code in which a value
+that could be under an attacker's control is used as the size of
+an operation such as @code{memset} without being sanitized, so that an
+attacker could inject an out-of-bounds access.
+
+See @uref{https://cwe.mitre.org/data/definitions/129.html, CWE-129: Improper Validation of Array Index}.
+
+@item -Wno-analyzer-unsafe-call-within-signal-handler
+@opindex Wanalyzer-unsafe-call-within-signal-handler
+@opindex Wno-analyzer-unsafe-call-within-signal-handler
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-unsafe-call-within-signal-handler} to disable it.
+
+This diagnostic warns for paths through the code in which a
+function known to be async-signal-unsafe (such as @code{fprintf}) is
+called from a signal handler.
+
+See @uref{https://cwe.mitre.org/data/definitions/479.html, CWE-479: Signal Handler Use of a Non-reentrant Function}.
+
+@item -Wno-analyzer-use-after-free
+@opindex Wanalyzer-use-after-free
+@opindex Wno-analyzer-use-after-free
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-use-after-free} to disable it.
+
+This diagnostic warns for paths through the code in which a
+pointer is used after a deallocator is called on it: either @code{free},
+or a deallocator referenced by attribute @code{malloc}.
+
+See @uref{https://cwe.mitre.org/data/definitions/416.html, CWE-416: Use After Free}.
+
+@item -Wno-analyzer-use-of-pointer-in-stale-stack-frame
+@opindex Wanalyzer-use-of-pointer-in-stale-stack-frame
+@opindex Wno-analyzer-use-of-pointer-in-stale-stack-frame
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-use-of-pointer-in-stale-stack-frame}
+to disable it.
+
+This diagnostic warns for paths through the code in which a pointer
+is dereferenced that points to a variable in a stale stack frame.
+
+@item -Wno-analyzer-va-arg-type-mismatch
+@opindex Wanalyzer-va-arg-type-mismatch
+@opindex Wno-analyzer-va-arg-type-mismatch
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-va-arg-type-mismatch}
+to disable it.
+
+This diagnostic warns for interprocedural paths through the code for which
+the analyzer detects an attempt to use @code{va_arg} to extract a value
+passed to a variadic call, but uses a type that does not match that of
+the expression passed to the call.
+
+See @uref{https://cwe.mitre.org/data/definitions/686.html, CWE-686: Function Call With Incorrect Argument Type}.
+
+@item -Wno-analyzer-va-list-exhausted
+@opindex Wanalyzer-va-list-exhausted
+@opindex Wno-analyzer-va-list-exhausted
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-va-list-exhausted}
+to disable it.
+
+This diagnostic warns for interprocedural paths through the code for which
+the analyzer detects an attempt to use @code{va_arg} to access the next
+value passed to a variadic call, but all of the values in the
+@code{va_list} have already been consumed.
+
+See @uref{https://cwe.mitre.org/data/definitions/685.html, CWE-685: Function Call With Incorrect Number of Arguments}.
+
+@item -Wno-analyzer-va-list-leak
+@opindex Wanalyzer-va-list-leak
+@opindex Wno-analyzer-va-list-leak
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-va-list-leak}
+to disable it.
+
+This diagnostic warns for interprocedural paths through the code for which
+the analyzer detects that @code{va_start} or @code{va_copy} has been called
+on a @code{va_list} without a corresponding call to @code{va_end}.
+
+@item -Wno-analyzer-va-list-use-after-va-end
+@opindex Wanalyzer-va-list-use-after-va-end
+@opindex Wno-analyzer-va-list-use-after-va-end
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-va-list-use-after-va-end}
+to disable it.
+
+This diagnostic warns for interprocedural paths through the code for which
+the analyzer detects an attempt to use a @code{va_list}  after
+@code{va_end} has been called on it.
+@code{va_list}.
+
+@item -Wno-analyzer-write-to-const
+@opindex Wanalyzer-write-to-const
+@opindex Wno-analyzer-write-to-const
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-write-to-const}
+to disable it.
+
+This diagnostic warns for paths through the code in which the analyzer
+detects an attempt to write through a pointer to a @code{const} object.
+However, the analyzer does not prioritize detection of such paths, so
+false negatives are more likely relative to other warnings.
+
+@item -Wno-analyzer-write-to-string-literal
+@opindex Wanalyzer-write-to-string-literal
+@opindex Wno-analyzer-write-to-string-literal
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-write-to-string-literal}
+to disable it.
+
+This diagnostic warns for paths through the code in which the analyzer
+detects an attempt to write through a pointer to a string literal.
+However, the analyzer does not prioritize detection of such paths, so
+false negatives are more likely relative to other warnings.
+
+@item -Wno-analyzer-use-of-uninitialized-value
+@opindex Wanalyzer-use-of-uninitialized-value
+@opindex Wno-analyzer-use-of-uninitialized-value
+This warning requires @option{-fanalyzer}, which enables it; use
+@option{-Wno-analyzer-use-of-uninitialized-value} to disable it.
+
+This diagnostic warns for paths through the code in which an uninitialized
+value is used.
+
+See @uref{https://cwe.mitre.org/data/definitions/457.html, CWE-457: Use of Uninitialized Variable}.
+
+@end table
+
+The analyzer has hardcoded knowledge about the behavior of the following
+memory-management functions:
+
+@itemize @bullet
+@item @code{alloca}
+@item The built-in functions @code{__builtin_alloc},
+@code{__builtin_alloc_with_align}, @item @code{__builtin_calloc},
+@code{__builtin_free}, @code{__builtin_malloc}, @code{__builtin_memcpy},
+@code{__builtin_memcpy_chk}, @code{__builtin_memset},
+@code{__builtin_memset_chk}, @code{__builtin_realloc},
+@code{__builtin_stack_restore}, and @code{__builtin_stack_save}
+@item @code{calloc}
+@item @code{free}
+@item @code{malloc}
+@item @code{memset}
+@item @code{operator delete}
+@item @code{operator delete []}
+@item @code{operator new}
+@item @code{operator new []}
+@item @code{realloc}
+@item @code{strdup}
+@item @code{strndup}
+@end itemize
+
+of the following functions for working with file descriptors:
+
+@itemize @bullet
+@item @code{open}
+@item @code{close}
+@item @code{creat}
+@item @code{dup}, @code{dup2} and @code{dup3}
+@item @code{pipe}, and @code{pipe2}
+@item @code{read}
+@item @code{write}
+@end itemize
+
+of the following functions for working with @code{<stdio.h>} streams:
+@itemize @bullet
+@item The built-in functions @code{__builtin_fprintf},
+@code{__builtin_fprintf_unlocked}, @code{__builtin_fputc},
+@code{__builtin_fputc_unlocked}, @code{__builtin_fputs},
+@code{__builtin_fputs_unlocked}, @code{__builtin_fwrite},
+@code{__builtin_fwrite_unlocked}, @code{__builtin_printf},
+@code{__builtin_printf_unlocked}, @code{__builtin_putc},
+@code{__builtin_putchar}, @code{__builtin_putchar_unlocked},
+@code{__builtin_putc_unlocked}, @code{__builtin_puts},
+@code{__builtin_puts_unlocked}, @code{__builtin_vfprintf}, and
+@code{__builtin_vprintf}
+@item @code{fopen}
+@item @code{fclose}
+@item @code{fgets}
+@item @code{fgets_unlocked}
+@item @code{fread}
+@item @code{getchar}
+@item @code{fprintf}
+@item @code{printf}
+@item @code{fwrite}
+@end itemize
+
+and of the following functions:
+
+@itemize @bullet
+@item The built-in functions @code{__builtin_expect},
+@code{__builtin_expect_with_probability}, @code{__builtin_strchr},
+@code{__builtin_strcpy}, @code{__builtin_strcpy_chk},
+@code{__builtin_strlen}, @code{__builtin_va_copy}, and
+@code{__builtin_va_start}
+@item The GNU extensions @code{error} and @code{error_at_line}
+@item @code{getpass}
+@item @code{longjmp}
+@item @code{putenv}
+@item @code{setjmp}
+@item @code{siglongjmp}
+@item @code{signal}
+@item @code{sigsetjmp}
+@item @code{strchr}
+@item @code{strlen}
+@end itemize
+
+In addition, various functions with an @code{__analyzer_} prefix have
+special meaning to the analyzer, described in the GCC Internals manual.
+
+Pertinent parameters for controlling the exploration are:
+@option{--param analyzer-bb-explosion-factor=@var{value}},
+@option{--param analyzer-max-enodes-per-program-point=@var{value}},
+@option{--param analyzer-max-recursion-depth=@var{value}}, and
+@option{--param analyzer-min-snodes-for-call-summary=@var{value}}.
+
+The following options control the analyzer.
+
+@table @gcctabopt
+
+@item -fanalyzer-call-summaries
+@opindex fanalyzer-call-summaries
+@opindex fno-analyzer-call-summaries
+Simplify interprocedural analysis by computing the effect of certain calls,
+rather than exploring all paths through the function from callsite to each
+possible return.
+
+If enabled, call summaries are only used for functions with more than one
+call site, and that are sufficiently complicated (as per
+@option{--param analyzer-min-snodes-for-call-summary=@var{value}}).
+
+@item -fanalyzer-checker=@var{name}
+@opindex fanalyzer-checker
+Restrict the analyzer to run just the named checker, and enable it.
+
+Some checkers are disabled by default (even with @option{-fanalyzer}),
+such as the @code{taint} checker that implements
+@option{-Wanalyzer-tainted-array-index}, and this option is required
+to enable them.
+
+@emph{Note:} currently, @option{-fanalyzer-checker=taint} disables the
+following warnings from @option{-fanalyzer}:
+
+@gccoptlist{ @gol
+-Wanalyzer-double-fclose @gol
+-Wanalyzer-double-free @gol
+-Wanalyzer-exposure-through-output-file @gol
+-Wanalyzer-fd-access-mode-mismatch @gol
+-Wanalyzer-fd-double-close @gol
+-Wanalyzer-fd-leak @gol
+-Wanalyzer-fd-use-after-close @gol
+-Wanalyzer-fd-use-without-check @gol
+-Wanalyzer-file-leak @gol
+-Wanalyzer-free-of-non-heap @gol
+-Wanalyzer-malloc-leak @gol
+-Wanalyzer-mismatching-deallocation @gol
+-Wanalyzer-null-argument @gol
+-Wanalyzer-null-dereference @gol
+-Wanalyzer-possible-null-argument @gol
+-Wanalyzer-possible-null-dereference @gol
+-Wanalyzer-unsafe-call-within-signal-handler @gol
+-Wanalyzer-use-after-free @gol
+-Wanalyzer-va-list-leak @gol
+-Wanalyzer-va-list-use-after-va-end @gol
+}
+
+@item -fno-analyzer-feasibility
+@opindex fanalyzer-feasibility
+@opindex fno-analyzer-feasibility
+This option is intended for analyzer developers.
+
+By default the analyzer verifies that there is a feasible control flow path
+for each diagnostic it emits: that the conditions that hold are not mutually
+exclusive.  Diagnostics for which no feasible path can be found are rejected.
+This filtering can be suppressed with @option{-fno-analyzer-feasibility}, for
+debugging issues in this code.
+
+@item -fanalyzer-fine-grained
+@opindex fanalyzer-fine-grained
+@opindex fno-analyzer-fine-grained
+This option is intended for analyzer developers.
+
+Internally the analyzer builds an ``exploded graph'' that combines
+control flow graphs with data flow information.
+
+By default, an edge in this graph can contain the effects of a run
+of multiple statements within a basic block.  With
+@option{-fanalyzer-fine-grained}, each statement gets its own edge.
+
+@item -fanalyzer-show-duplicate-count
+@opindex fanalyzer-show-duplicate-count
+@opindex fno-analyzer-show-duplicate-count
+This option is intended for analyzer developers: if multiple diagnostics
+have been detected as being duplicates of each other, it emits a note when
+reporting the best diagnostic, giving the number of additional diagnostics
+that were suppressed by the deduplication logic.
+
+@item -fno-analyzer-state-merge
+@opindex fanalyzer-state-merge
+@opindex fno-analyzer-state-merge
+This option is intended for analyzer developers.
+
+By default the analyzer attempts to simplify analysis by merging
+sufficiently similar states at each program point as it builds its
+``exploded graph''.  With @option{-fno-analyzer-state-merge} this
+merging can be suppressed, for debugging state-handling issues.
+
+@item -fno-analyzer-state-purge
+@opindex fanalyzer-state-purge
+@opindex fno-analyzer-state-purge
+This option is intended for analyzer developers.
+
+By default the analyzer attempts to simplify analysis by purging
+aspects of state at a program point that appear to no longer be relevant
+e.g. the values of locals that aren't accessed later in the function
+and which aren't relevant to leak analysis.
+
+With @option{-fno-analyzer-state-purge} this purging of state can
+be suppressed, for debugging state-handling issues.
+
+@item -fanalyzer-transitivity
+@opindex fanalyzer-transitivity
+@opindex fno-analyzer-transitivity
+This option enables transitivity of constraints within the analyzer.
+
+@item -fno-analyzer-undo-inlining
+@opindex fanalyzer-undo-inlining
+@opindex fno-analyzer-undo-inlining
+This option is intended for analyzer developers.
+
+@option{-fanalyzer} runs relatively late compared to other code analysis
+tools, and some optimizations have already been applied to the code.  In
+particular function inlining may have occurred, leading to the
+interprocedural execution paths emitted by the analyzer containing
+function frames that don't correspond to those in the original source
+code.
+
+By default the analyzer attempts to reconstruct the original function
+frames, and to emit events showing the inlined calls.
+
+With @option{-fno-analyzer-undo-inlining} this attempt to reconstruct
+the original frame information can be be disabled, which may be of help
+when debugging issues in the analyzer.
+
+@item -fanalyzer-verbose-edges
+This option is intended for analyzer developers.  It enables more
+verbose, lower-level detail in the descriptions of control flow
+within diagnostic paths.
+
+@item -fanalyzer-verbose-state-changes
+This option is intended for analyzer developers.  It enables more
+verbose, lower-level detail in the descriptions of events relating
+to state machines within diagnostic paths.
+
+@item -fanalyzer-verbosity=@var{level}
+This option controls the complexity of the control flow paths that are
+emitted for analyzer diagnostics.
+
+The @var{level} can be one of:
+
+@table @samp
+@item 0
+At this level, interprocedural call and return events are displayed,
+along with the most pertinent state-change events relating to
+a diagnostic.  For example, for a double-@code{free} diagnostic,
+both calls to @code{free} will be shown.
+
+@item 1
+As per the previous level, but also show events for the entry
+to each function.
+
+@item 2
+As per the previous level, but also show events relating to
+control flow that are significant to triggering the issue
+(e.g. ``true path taken'' at a conditional).
+
+This level is the default.
+
+@item 3
+As per the previous level, but show all control flow events, not
+just significant ones.
+
+@item 4
+This level is intended for analyzer developers; it adds various
+other events intended for debugging the analyzer.
+
+@end table
+
+@item -fdump-analyzer
+@opindex fdump-analyzer
+Dump internal details about what the analyzer is doing to
+@file{@var{file}.analyzer.txt}.
+This option is overridden by @option{-fdump-analyzer-stderr}.
+
+@item -fdump-analyzer-stderr
+@opindex fdump-analyzer-stderr
+Dump internal details about what the analyzer is doing to stderr.
+This option overrides @option{-fdump-analyzer}.
+
+@item -fdump-analyzer-callgraph
+@opindex fdump-analyzer-callgraph
+Dump a representation of the call graph suitable for viewing with
+GraphViz to @file{@var{file}.callgraph.dot}.
+
+@item -fdump-analyzer-exploded-graph
+@opindex fdump-analyzer-exploded-graph
+Dump a representation of the ``exploded graph'' suitable for viewing with
+GraphViz to @file{@var{file}.eg.dot}.
+Nodes are color-coded based on state-machine states to emphasize
+state changes.
+
+@item -fdump-analyzer-exploded-nodes
+@opindex dump-analyzer-exploded-nodes
+Emit diagnostics showing where nodes in the ``exploded graph'' are
+in relation to the program source.
+
+@item -fdump-analyzer-exploded-nodes-2
+@opindex dump-analyzer-exploded-nodes-2
+Dump a textual representation of the ``exploded graph'' to
+@file{@var{file}.eg.txt}.
+
+@item -fdump-analyzer-exploded-nodes-3
+@opindex dump-analyzer-exploded-nodes-3
+Dump a textual representation of the ``exploded graph'' to
+one dump file per node, to @file{@var{file}.eg-@var{id}.txt}.
+This is typically a large number of dump files.
+
+@item -fdump-analyzer-exploded-paths
+@opindex fdump-analyzer-exploded-paths
+Dump a textual representation of the ``exploded path'' for each
+diagnostic to @file{@var{file}.@var{idx}.@var{kind}.epath.txt}.
+
+@item -fdump-analyzer-feasibility
+@opindex dump-analyzer-feasibility
+Dump internal details about the analyzer's search for feasible paths.
+The details are written in a form suitable for viewing with GraphViz
+to filenames of the form @file{@var{file}.*.fg.dot},
+@file{@var{file}.*.tg.dot}, and @file{@var{file}.*.fpath.txt}.
+
+@item -fdump-analyzer-json
+@opindex fdump-analyzer-json
+Dump a compressed JSON representation of analyzer internals to
+@file{@var{file}.analyzer.json.gz}.  The precise format is subject
+to change.
+
+@item -fdump-analyzer-state-purge
+@opindex fdump-analyzer-state-purge
+As per @option{-fdump-analyzer-supergraph}, dump a representation of the
+``supergraph'' suitable for viewing with GraphViz, but annotate the
+graph with information on what state will be purged at each node.
+The graph is written to @file{@var{file}.state-purge.dot}.
+
+@item -fdump-analyzer-supergraph
+@opindex fdump-analyzer-supergraph
+Dump representations of the ``supergraph'' suitable for viewing with
+GraphViz to @file{@var{file}.supergraph.dot} and to
+@file{@var{file}.supergraph-eg.dot}.  These show all of the
+control flow graphs in the program, with interprocedural edges for
+calls and returns.  The second dump contains annotations showing nodes
+in the ``exploded graph'' and diagnostics associated with them.
+
+@item -fdump-analyzer-untracked
+@opindex fdump-analyzer-untracked
+Emit custom warnings with internal details intended for analyzer developers.
+
+@end table
+
+@node Debugging Options
+@section Options for Debugging Your Program
+@cindex options, debugging
+@cindex debugging information options
+
+To tell GCC to emit extra information for use by a debugger, in almost 
+all cases you need only to add @option{-g} to your other options.  Some debug
+formats can co-exist (like DWARF with CTF) when each of them is enabled
+explicitly by adding the respective command line option to your other options.
+
+GCC allows you to use @option{-g} with
+@option{-O}.  The shortcuts taken by optimized code may occasionally
+be surprising: some variables you declared may not exist
+at all; flow of control may briefly move where you did not expect it;
+some statements may not be executed because they compute constant
+results or their values are already at hand; some statements may
+execute in different places because they have been moved out of loops.
+Nevertheless it is possible to debug optimized output.  This makes
+it reasonable to use the optimizer for programs that might have bugs.
+
+If you are not using some other optimization option, consider
+using @option{-Og} (@pxref{Optimize Options}) with @option{-g}.  
+With no @option{-O} option at all, some compiler passes that collect
+information useful for debugging do not run at all, so that
+@option{-Og} may result in a better debugging experience.
+
+@table @gcctabopt
+@item -g
+@opindex g
+Produce debugging information in the operating system's native format
+(stabs, COFF, XCOFF, or DWARF)@.  GDB can work with this debugging
+information.
+
+On most systems that use stabs format, @option{-g} enables use of extra
+debugging information that only GDB can use; this extra information
+makes debugging work better in GDB but probably makes other debuggers
+crash or refuse to read the program.  If you want to control for certain whether
+to generate the extra information, use @option{-gvms} (see below).
+
+@item -ggdb
+@opindex ggdb
+Produce debugging information for use by GDB@.  This means to use the
+most expressive format available (DWARF, stabs, or the native format
+if neither of those are supported), including GDB extensions if at all
+possible.
+
+@item -gdwarf
+@itemx -gdwarf-@var{version}
+@opindex gdwarf
+Produce debugging information in DWARF format (if that is supported).
+The value of @var{version} may be either 2, 3, 4 or 5; the default
+version for most targets is 5 (with the exception of VxWorks, TPF and
+Darwin/Mac OS X, which default to version 2, and AIX, which defaults
+to version 4).
+
+Note that with DWARF Version 2, some ports require and always
+use some non-conflicting DWARF 3 extensions in the unwind tables.
+
+Version 4 may require GDB 7.0 and @option{-fvar-tracking-assignments}
+for maximum benefit. Version 5 requires GDB 8.0 or higher.
+
+GCC no longer supports DWARF Version 1, which is substantially
+different than Version 2 and later.  For historical reasons, some
+other DWARF-related options such as
+@option{-fno-dwarf2-cfi-asm}) retain a reference to DWARF Version 2
+in their names, but apply to all currently-supported versions of DWARF.
+
+@item -gbtf
+@opindex gbtf
+Request BTF debug information.  BTF is the default debugging format for the
+eBPF target.  On other targets, like x86, BTF debug information can be
+generated along with DWARF debug information when both of the debug formats are
+enabled explicitly via their respective command line options.
+
+@item -gctf
+@itemx -gctf@var{level}
+@opindex gctf
+Request CTF debug information and use level to specify how much CTF debug
+information should be produced.  If @option{-gctf} is specified
+without a value for level, the default level of CTF debug information is 2.
+
+CTF debug information can be generated along with DWARF debug information when
+both of the debug formats are enabled explicitly via their respective command
+line options.
+
+Level 0 produces no CTF debug information at all.  Thus, @option{-gctf0}
+negates @option{-gctf}.
+
+Level 1 produces CTF information for tracebacks only.  This includes callsite
+information, but does not include type information.
+
+Level 2 produces type information for entities (functions, data objects etc.)
+at file-scope or global-scope only.
+
+@item -gvms
+@opindex gvms
+Produce debugging information in Alpha/VMS debug format (if that is
+supported).  This is the format used by DEBUG on Alpha/VMS systems.
+
+@item -g@var{level}
+@itemx -ggdb@var{level}
+@itemx -gvms@var{level}
+Request debugging information and also use @var{level} to specify how
+much information.  The default level is 2.
+
+Level 0 produces no debug information at all.  Thus, @option{-g0} negates
+@option{-g}.
+
+Level 1 produces minimal information, enough for making backtraces in
+parts of the program that you don't plan to debug.  This includes
+descriptions of functions and external variables, and line number
+tables, but no information about local variables.
+
+Level 3 includes extra information, such as all the macro definitions
+present in the program.  Some debuggers support macro expansion when
+you use @option{-g3}.
+
+If you use multiple @option{-g} options, with or without level numbers,
+the last such option is the one that is effective.
+
+@option{-gdwarf} does not accept a concatenated debug level, to avoid
+confusion with @option{-gdwarf-@var{level}}.
+Instead use an additional @option{-g@var{level}} option to change the
+debug level for DWARF.
+
+@item -fno-eliminate-unused-debug-symbols
+@opindex feliminate-unused-debug-symbols
+@opindex fno-eliminate-unused-debug-symbols
+By default, no debug information is produced for symbols that are not actually
+used. Use this option if you want debug information for all symbols.
+
+@item -femit-class-debug-always
+@opindex femit-class-debug-always
+Instead of emitting debugging information for a C++ class in only one
+object file, emit it in all object files using the class.  This option
+should be used only with debuggers that are unable to handle the way GCC
+normally emits debugging information for classes because using this
+option increases the size of debugging information by as much as a
+factor of two.
+
+@item -fno-merge-debug-strings
+@opindex fmerge-debug-strings
+@opindex fno-merge-debug-strings
+Direct the linker to not merge together strings in the debugging
+information that are identical in different object files.  Merging is
+not supported by all assemblers or linkers.  Merging decreases the size
+of the debug information in the output file at the cost of increasing
+link processing time.  Merging is enabled by default.
+
+@item -fdebug-prefix-map=@var{old}=@var{new}
+@opindex fdebug-prefix-map
+When compiling files residing in directory @file{@var{old}}, record
+debugging information describing them as if the files resided in
+directory @file{@var{new}} instead.  This can be used to replace a
+build-time path with an install-time path in the debug info.  It can
+also be used to change an absolute path to a relative path by using
+@file{.} for @var{new}.  This can give more reproducible builds, which
+are location independent, but may require an extra command to tell GDB
+where to find the source files. See also @option{-ffile-prefix-map}.
+
+@item -fvar-tracking
+@opindex fvar-tracking
+Run variable tracking pass.  It computes where variables are stored at each
+position in code.  Better debugging information is then generated
+(if the debugging information format supports this information).
+
+It is enabled by default when compiling with optimization (@option{-Os},
+@option{-O}, @option{-O2}, @dots{}), debugging information (@option{-g}) and
+the debug info format supports it.
+
+@item -fvar-tracking-assignments
+@opindex fvar-tracking-assignments
+@opindex fno-var-tracking-assignments
+Annotate assignments to user variables early in the compilation and
+attempt to carry the annotations over throughout the compilation all the
+way to the end, in an attempt to improve debug information while
+optimizing.  Use of @option{-gdwarf-4} is recommended along with it.
+
+It can be enabled even if var-tracking is disabled, in which case
+annotations are created and maintained, but discarded at the end.
+By default, this flag is enabled together with @option{-fvar-tracking},
+except when selective scheduling is enabled.
+
+@item -gsplit-dwarf
+@opindex gsplit-dwarf
+If DWARF debugging information is enabled, separate as much debugging
+information as possible into a separate output file with the extension
+@file{.dwo}.  This option allows the build system to avoid linking files with
+debug information.  To be useful, this option requires a debugger capable of
+reading @file{.dwo} files.
+
+@item -gdwarf32
+@itemx -gdwarf64
+@opindex gdwarf32
+@opindex gdwarf64
+If DWARF debugging information is enabled, the @option{-gdwarf32} selects
+the 32-bit DWARF format and the @option{-gdwarf64} selects the 64-bit
+DWARF format.  The default is target specific, on most targets it is
+@option{-gdwarf32} though.  The 32-bit DWARF format is smaller, but
+can't support more than 2GiB of debug information in any of the DWARF
+debug information sections.  The 64-bit DWARF format allows larger debug
+information and might not be well supported by all consumers yet.
+
+@item -gdescribe-dies
+@opindex gdescribe-dies
+Add description attributes to some DWARF DIEs that have no name attribute,
+such as artificial variables, external references and call site
+parameter DIEs.
+
+@item -gpubnames
+@opindex gpubnames
+Generate DWARF @code{.debug_pubnames} and @code{.debug_pubtypes} sections.
+
+@item -ggnu-pubnames
+@opindex ggnu-pubnames
+Generate @code{.debug_pubnames} and @code{.debug_pubtypes} sections in a format
+suitable for conversion into a GDB@ index.  This option is only useful
+with a linker that can produce GDB@ index version 7.
+
+@item -fdebug-types-section
+@opindex fdebug-types-section
+@opindex fno-debug-types-section
+When using DWARF Version 4 or higher, type DIEs can be put into
+their own @code{.debug_types} section instead of making them part of the
+@code{.debug_info} section.  It is more efficient to put them in a separate
+comdat section since the linker can then remove duplicates.
+But not all DWARF consumers support @code{.debug_types} sections yet
+and on some objects @code{.debug_types} produces larger instead of smaller
+debugging information.
+
+@item -grecord-gcc-switches
+@itemx -gno-record-gcc-switches
+@opindex grecord-gcc-switches
+@opindex gno-record-gcc-switches
+This switch causes the command-line options used to invoke the
+compiler that may affect code generation to be appended to the
+DW_AT_producer attribute in DWARF debugging information.  The options
+are concatenated with spaces separating them from each other and from
+the compiler version.  
+It is enabled by default.
+See also @option{-frecord-gcc-switches} for another
+way of storing compiler options into the object file.  
+
+@item -gstrict-dwarf
+@opindex gstrict-dwarf
+Disallow using extensions of later DWARF standard version than selected
+with @option{-gdwarf-@var{version}}.  On most targets using non-conflicting
+DWARF extensions from later standard versions is allowed.
+
+@item -gno-strict-dwarf
+@opindex gno-strict-dwarf
+Allow using extensions of later DWARF standard version than selected with
+@option{-gdwarf-@var{version}}.
+
+@item -gas-loc-support
+@opindex gas-loc-support
+Inform the compiler that the assembler supports @code{.loc} directives.
+It may then use them for the assembler to generate DWARF2+ line number
+tables.
+
+This is generally desirable, because assembler-generated line-number
+tables are a lot more compact than those the compiler can generate
+itself.
+
+This option will be enabled by default if, at GCC configure time, the
+assembler was found to support such directives.
+
+@item -gno-as-loc-support
+@opindex gno-as-loc-support
+Force GCC to generate DWARF2+ line number tables internally, if DWARF2+
+line number tables are to be generated.
+
+@item -gas-locview-support
+@opindex gas-locview-support
+Inform the compiler that the assembler supports @code{view} assignment
+and reset assertion checking in @code{.loc} directives.
+
+This option will be enabled by default if, at GCC configure time, the
+assembler was found to support them.
+
+@item -gno-as-locview-support
+Force GCC to assign view numbers internally, if
+@option{-gvariable-location-views} are explicitly requested.
+
+@item -gcolumn-info
+@itemx -gno-column-info
+@opindex gcolumn-info
+@opindex gno-column-info
+Emit location column information into DWARF debugging information, rather
+than just file and line.
+This option is enabled by default.
+
+@item -gstatement-frontiers
+@itemx -gno-statement-frontiers
+@opindex gstatement-frontiers
+@opindex gno-statement-frontiers
+This option causes GCC to create markers in the internal representation
+at the beginning of statements, and to keep them roughly in place
+throughout compilation, using them to guide the output of @code{is_stmt}
+markers in the line number table.  This is enabled by default when
+compiling with optimization (@option{-Os}, @option{-O1}, @option{-O2},
+@dots{}), and outputting DWARF 2 debug information at the normal level.
+
+@item -gvariable-location-views
+@itemx -gvariable-location-views=incompat5
+@itemx -gno-variable-location-views
+@opindex gvariable-location-views
+@opindex gvariable-location-views=incompat5
+@opindex gno-variable-location-views
+Augment variable location lists with progressive view numbers implied
+from the line number table.  This enables debug information consumers to
+inspect state at certain points of the program, even if no instructions
+associated with the corresponding source locations are present at that
+point.  If the assembler lacks support for view numbers in line number
+tables, this will cause the compiler to emit the line number table,
+which generally makes them somewhat less compact.  The augmented line
+number tables and location lists are fully backward-compatible, so they
+can be consumed by debug information consumers that are not aware of
+these augmentations, but they won't derive any benefit from them either.
+
+This is enabled by default when outputting DWARF 2 debug information at
+the normal level, as long as there is assembler support,
+@option{-fvar-tracking-assignments} is enabled and
+@option{-gstrict-dwarf} is not.  When assembler support is not
+available, this may still be enabled, but it will force GCC to output
+internal line number tables, and if
+@option{-ginternal-reset-location-views} is not enabled, that will most
+certainly lead to silently mismatching location views.
+
+There is a proposed representation for view numbers that is not backward
+compatible with the location list format introduced in DWARF 5, that can
+be enabled with @option{-gvariable-location-views=incompat5}.  This
+option may be removed in the future, is only provided as a reference
+implementation of the proposed representation.  Debug information
+consumers are not expected to support this extended format, and they
+would be rendered unable to decode location lists using it.
+
+@item -ginternal-reset-location-views
+@itemx -gno-internal-reset-location-views
+@opindex ginternal-reset-location-views
+@opindex gno-internal-reset-location-views
+Attempt to determine location views that can be omitted from location
+view lists.  This requires the compiler to have very accurate insn
+length estimates, which isn't always the case, and it may cause
+incorrect view lists to be generated silently when using an assembler
+that does not support location view lists.  The GNU assembler will flag
+any such error as a @code{view number mismatch}.  This is only enabled
+on ports that define a reliable estimation function.
+
+@item -ginline-points
+@itemx -gno-inline-points
+@opindex ginline-points
+@opindex gno-inline-points
+Generate extended debug information for inlined functions.  Location
+view tracking markers are inserted at inlined entry points, so that
+address and view numbers can be computed and output in debug
+information.  This can be enabled independently of location views, in
+which case the view numbers won't be output, but it can only be enabled
+along with statement frontiers, and it is only enabled by default if
+location views are enabled.
+
+@item -gz@r{[}=@var{type}@r{]}
+@opindex gz
+Produce compressed debug sections in DWARF format, if that is supported.
+If @var{type} is not given, the default type depends on the capabilities
+of the assembler and linker used.  @var{type} may be one of
+@samp{none} (don't compress debug sections), or @samp{zlib} (use zlib
+compression in ELF gABI format).  If the linker doesn't support writing
+compressed debug sections, the option is rejected.  Otherwise, if the
+assembler does not support them, @option{-gz} is silently ignored when
+producing object files.
+
+@item -femit-struct-debug-baseonly
+@opindex femit-struct-debug-baseonly
+Emit debug information for struct-like types
+only when the base name of the compilation source file
+matches the base name of file in which the struct is defined.
+
+This option substantially reduces the size of debugging information,
+but at significant potential loss in type information to the debugger.
+See @option{-femit-struct-debug-reduced} for a less aggressive option.
+See @option{-femit-struct-debug-detailed} for more detailed control.
+
+This option works only with DWARF debug output.
+
+@item -femit-struct-debug-reduced
+@opindex femit-struct-debug-reduced
+Emit debug information for struct-like types
+only when the base name of the compilation source file
+matches the base name of file in which the type is defined,
+unless the struct is a template or defined in a system header.
+
+This option significantly reduces the size of debugging information,
+with some potential loss in type information to the debugger.
+See @option{-femit-struct-debug-baseonly} for a more aggressive option.
+See @option{-femit-struct-debug-detailed} for more detailed control.
+
+This option works only with DWARF debug output.
+
+@item -femit-struct-debug-detailed@r{[}=@var{spec-list}@r{]}
+@opindex femit-struct-debug-detailed
+Specify the struct-like types
+for which the compiler generates debug information.
+The intent is to reduce duplicate struct debug information
+between different object files within the same program.
+
+This option is a detailed version of
+@option{-femit-struct-debug-reduced} and @option{-femit-struct-debug-baseonly},
+which serves for most needs.
+
+A specification has the syntax@*
+[@samp{dir:}|@samp{ind:}][@samp{ord:}|@samp{gen:}](@samp{any}|@samp{sys}|@samp{base}|@samp{none})
+
+The optional first word limits the specification to
+structs that are used directly (@samp{dir:}) or used indirectly (@samp{ind:}).
+A struct type is used directly when it is the type of a variable, member.
+Indirect uses arise through pointers to structs.
+That is, when use of an incomplete struct is valid, the use is indirect.
+An example is
+@samp{struct one direct; struct two * indirect;}.
+
+The optional second word limits the specification to
+ordinary structs (@samp{ord:}) or generic structs (@samp{gen:}).
+Generic structs are a bit complicated to explain.
+For C++, these are non-explicit specializations of template classes,
+or non-template classes within the above.
+Other programming languages have generics,
+but @option{-femit-struct-debug-detailed} does not yet implement them.
+
+The third word specifies the source files for those
+structs for which the compiler should emit debug information.
+The values @samp{none} and @samp{any} have the normal meaning.
+The value @samp{base} means that
+the base of name of the file in which the type declaration appears
+must match the base of the name of the main compilation file.
+In practice, this means that when compiling @file{foo.c}, debug information
+is generated for types declared in that file and @file{foo.h},
+but not other header files.
+The value @samp{sys} means those types satisfying @samp{base}
+or declared in system or compiler headers.
+
+You may need to experiment to determine the best settings for your application.
+
+The default is @option{-femit-struct-debug-detailed=all}.
+
+This option works only with DWARF debug output.
+
+@item -fno-dwarf2-cfi-asm
+@opindex fdwarf2-cfi-asm
+@opindex fno-dwarf2-cfi-asm
+Emit DWARF unwind info as compiler generated @code{.eh_frame} section
+instead of using GAS @code{.cfi_*} directives.
+
+@item -fno-eliminate-unused-debug-types
+@opindex feliminate-unused-debug-types
+@opindex fno-eliminate-unused-debug-types
+Normally, when producing DWARF output, GCC avoids producing debug symbol 
+output for types that are nowhere used in the source file being compiled.
+Sometimes it is useful to have GCC emit debugging
+information for all types declared in a compilation
+unit, regardless of whether or not they are actually used
+in that compilation unit, for example 
+if, in the debugger, you want to cast a value to a type that is
+not actually used in your program (but is declared).  More often,
+however, this results in a significant amount of wasted space.
+@end table
+
+@node Optimize Options
+@section Options That Control Optimization
+@cindex optimize options
+@cindex options, optimization
+
+These options control various sorts of optimizations.
+
+Without any optimization option, the compiler's goal is to reduce the
+cost of compilation and to make debugging produce the expected
+results.  Statements are independent: if you stop the program with a
+breakpoint between statements, you can then assign a new value to any
+variable or change the program counter to any other statement in the
+function and get exactly the results you expect from the source
+code.
+
+Turning on optimization flags makes the compiler attempt to improve
+the performance and/or code size at the expense of compilation time
+and possibly the ability to debug the program.
+
+The compiler performs optimization based on the knowledge it has of the
+program.  Compiling multiple files at once to a single output file mode allows
+the compiler to use information gained from all of the files when compiling
+each of them.
+
+Not all optimizations are controlled directly by a flag.  Only
+optimizations that have a flag are listed in this section.
+
+Most optimizations are completely disabled at @option{-O0} or if an
+@option{-O} level is not set on the command line, even if individual
+optimization flags are specified.  Similarly, @option{-Og} suppresses
+many optimization passes.
+
+Depending on the target and how GCC was configured, a slightly different
+set of optimizations may be enabled at each @option{-O} level than
+those listed here.  You can invoke GCC with @option{-Q --help=optimizers}
+to find out the exact set of optimizations that are enabled at each level.
+@xref{Overall Options}, for examples.
+
+@table @gcctabopt
+@item -O
+@itemx -O1
+@opindex O
+@opindex O1
+Optimize.  Optimizing compilation takes somewhat more time, and a lot
+more memory for a large function.
+
+With @option{-O}, the compiler tries to reduce code size and execution
+time, without performing any optimizations that take a great deal of
+compilation time.
+
+@c Note that in addition to the default_options_table list in opts.cc,
+@c several optimization flags default to true but control optimization
+@c passes that are explicitly disabled at -O0.
+
+@option{-O} turns on the following optimization flags:
+
+@c Please keep the following list alphabetized.
+@gccoptlist{-fauto-inc-dec @gol
+-fbranch-count-reg @gol
+-fcombine-stack-adjustments @gol
+-fcompare-elim @gol
+-fcprop-registers @gol
+-fdce @gol
+-fdefer-pop @gol
+-fdelayed-branch @gol
+-fdse @gol
+-fforward-propagate @gol
+-fguess-branch-probability @gol
+-fif-conversion @gol
+-fif-conversion2 @gol
+-finline-functions-called-once @gol
+-fipa-modref @gol
+-fipa-profile @gol
+-fipa-pure-const @gol
+-fipa-reference @gol
+-fipa-reference-addressable @gol
+-fmerge-constants @gol
+-fmove-loop-invariants @gol
+-fmove-loop-stores@gol
+-fomit-frame-pointer @gol
+-freorder-blocks @gol
+-fshrink-wrap @gol
+-fshrink-wrap-separate @gol
+-fsplit-wide-types @gol
+-fssa-backprop @gol
+-fssa-phiopt @gol
+-ftree-bit-ccp @gol
+-ftree-ccp @gol
+-ftree-ch @gol
+-ftree-coalesce-vars @gol
+-ftree-copy-prop @gol
+-ftree-dce @gol
+-ftree-dominator-opts @gol
+-ftree-dse @gol
+-ftree-forwprop @gol
+-ftree-fre @gol
+-ftree-phiprop @gol
+-ftree-pta @gol
+-ftree-scev-cprop @gol
+-ftree-sink @gol
+-ftree-slsr @gol
+-ftree-sra @gol
+-ftree-ter @gol
+-funit-at-a-time}
+
+@item -O2
+@opindex O2
+Optimize even more.  GCC performs nearly all supported optimizations
+that do not involve a space-speed tradeoff.
+As compared to @option{-O}, this option increases both compilation time
+and the performance of the generated code.
+
+@option{-O2} turns on all optimization flags specified by @option{-O1}.  It
+also turns on the following optimization flags:
+
+@c Please keep the following list alphabetized!
+@gccoptlist{-falign-functions  -falign-jumps @gol
+-falign-labels  -falign-loops @gol
+-fcaller-saves @gol
+-fcode-hoisting @gol
+-fcrossjumping @gol
+-fcse-follow-jumps  -fcse-skip-blocks @gol
+-fdelete-null-pointer-checks @gol
+-fdevirtualize  -fdevirtualize-speculatively @gol
+-fexpensive-optimizations @gol
+-ffinite-loops @gol
+-fgcse  -fgcse-lm  @gol
+-fhoist-adjacent-loads @gol
+-finline-functions @gol
+-finline-small-functions @gol
+-findirect-inlining @gol
+-fipa-bit-cp  -fipa-cp  -fipa-icf @gol
+-fipa-ra  -fipa-sra  -fipa-vrp @gol
+-fisolate-erroneous-paths-dereference @gol
+-flra-remat @gol
+-foptimize-sibling-calls @gol
+-foptimize-strlen @gol
+-fpartial-inlining @gol
+-fpeephole2 @gol
+-freorder-blocks-algorithm=stc @gol
+-freorder-blocks-and-partition  -freorder-functions @gol
+-frerun-cse-after-loop  @gol
+-fschedule-insns  -fschedule-insns2 @gol
+-fsched-interblock  -fsched-spec @gol
+-fstore-merging @gol
+-fstrict-aliasing @gol
+-fthread-jumps @gol
+-ftree-builtin-call-dce @gol
+-ftree-loop-vectorize @gol
+-ftree-pre @gol
+-ftree-slp-vectorize @gol
+-ftree-switch-conversion  -ftree-tail-merge @gol
+-ftree-vrp @gol
+-fvect-cost-model=very-cheap}
+
+Please note the warning under @option{-fgcse} about
+invoking @option{-O2} on programs that use computed gotos.
+
+@item -O3
+@opindex O3
+Optimize yet more.  @option{-O3} turns on all optimizations specified
+by @option{-O2} and also turns on the following optimization flags:
+
+@c Please keep the following list alphabetized!
+@gccoptlist{-fgcse-after-reload @gol
+-fipa-cp-clone
+-floop-interchange @gol
+-floop-unroll-and-jam @gol
+-fpeel-loops @gol
+-fpredictive-commoning @gol
+-fsplit-loops @gol
+-fsplit-paths @gol
+-ftree-loop-distribution @gol
+-ftree-partial-pre @gol
+-funswitch-loops @gol
+-fvect-cost-model=dynamic @gol
+-fversion-loops-for-strides}
+
+@item -O0
+@opindex O0
+Reduce compilation time and make debugging produce the expected
+results.  This is the default.
+
+@item -Os
+@opindex Os
+Optimize for size.  @option{-Os} enables all @option{-O2} optimizations 
+except those that often increase code size:
+
+@gccoptlist{-falign-functions  -falign-jumps @gol
+-falign-labels  -falign-loops @gol
+-fprefetch-loop-arrays  -freorder-blocks-algorithm=stc}
+
+It also enables @option{-finline-functions}, causes the compiler to tune for
+code size rather than execution speed, and performs further optimizations
+designed to reduce code size.
+
+@item -Ofast
+@opindex Ofast
+Disregard strict standards compliance.  @option{-Ofast} enables all
+@option{-O3} optimizations.  It also enables optimizations that are not
+valid for all standard-compliant programs.
+It turns on @option{-ffast-math}, @option{-fallow-store-data-races}
+and the Fortran-specific @option{-fstack-arrays}, unless
+@option{-fmax-stack-var-size} is specified, and @option{-fno-protect-parens}.
+It turns off @option{-fsemantic-interposition}.
+
+@item -Og
+@opindex Og
+Optimize debugging experience.  @option{-Og} should be the optimization
+level of choice for the standard edit-compile-debug cycle, offering
+a reasonable level of optimization while maintaining fast compilation
+and a good debugging experience.  It is a better choice than @option{-O0}
+for producing debuggable code because some compiler passes
+that collect debug information are disabled at @option{-O0}.
+
+Like @option{-O0}, @option{-Og} completely disables a number of 
+optimization passes so that individual options controlling them have
+no effect.  Otherwise @option{-Og} enables all @option{-O1} 
+optimization flags except for those that may interfere with debugging:
+
+@gccoptlist{-fbranch-count-reg  -fdelayed-branch @gol
+-fdse  -fif-conversion  -fif-conversion2  @gol
+-finline-functions-called-once @gol
+-fmove-loop-invariants  -fmove-loop-stores  -fssa-phiopt @gol
+-ftree-bit-ccp  -ftree-dse  -ftree-pta  -ftree-sra}
+
+@item -Oz
+@opindex Oz
+Optimize aggressively for size rather than speed.  This may increase
+the number of instructions executed if those instructions require
+fewer bytes to encode.  @option{-Oz} behaves similarly to @option{-Os}
+including enabling most @option{-O2} optimizations.
+
+@end table
+
+If you use multiple @option{-O} options, with or without level numbers,
+the last such option is the one that is effective.
+
+Options of the form @option{-f@var{flag}} specify machine-independent
+flags.  Most flags have both positive and negative forms; the negative
+form of @option{-ffoo} is @option{-fno-foo}.  In the table
+below, only one of the forms is listed---the one you typically 
+use.  You can figure out the other form by either removing @samp{no-}
+or adding it.
+
+The following options control specific optimizations.  They are either
+activated by @option{-O} options or are related to ones that are.  You
+can use the following flags in the rare cases when ``fine-tuning'' of
+optimizations to be performed is desired.
+
+@table @gcctabopt
+@item -fno-defer-pop
+@opindex fno-defer-pop
+@opindex fdefer-pop
+For machines that must pop arguments after a function call, always pop 
+the arguments as soon as each function returns.  
+At levels @option{-O1} and higher, @option{-fdefer-pop} is the default;
+this allows the compiler to let arguments accumulate on the stack for several
+function calls and pop them all at once.
+
+@item -fforward-propagate
+@opindex fforward-propagate
+Perform a forward propagation pass on RTL@.  The pass tries to combine two
+instructions and checks if the result can be simplified.  If loop unrolling
+is active, two passes are performed and the second is scheduled after
+loop unrolling.
+
+This option is enabled by default at optimization levels @option{-O1},
+@option{-O2}, @option{-O3}, @option{-Os}.
+
+@item -ffp-contract=@var{style}
+@opindex ffp-contract
+@option{-ffp-contract=off} disables floating-point expression contraction.
+@option{-ffp-contract=fast} enables floating-point expression contraction
+such as forming of fused multiply-add operations if the target has
+native support for them.
+@option{-ffp-contract=on} enables floating-point expression contraction
+if allowed by the language standard.  This is currently not implemented
+and treated equal to @option{-ffp-contract=off}.
+
+The default is @option{-ffp-contract=fast}.
+
+@item -fomit-frame-pointer
+@opindex fomit-frame-pointer
+Omit the frame pointer in functions that don't need one.  This avoids the
+instructions to save, set up and restore the frame pointer; on many targets
+it also makes an extra register available.
+
+On some targets this flag has no effect because the standard calling sequence
+always uses a frame pointer, so it cannot be omitted.
+
+Note that @option{-fno-omit-frame-pointer} doesn't guarantee the frame pointer
+is used in all functions.  Several targets always omit the frame pointer in
+leaf functions.
+
+Enabled by default at @option{-O1} and higher.
+
+@item -foptimize-sibling-calls
+@opindex foptimize-sibling-calls
+Optimize sibling and tail recursive calls.
+
+Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
+
+@item -foptimize-strlen
+@opindex foptimize-strlen
+Optimize various standard C string functions (e.g.@: @code{strlen},
+@code{strchr} or @code{strcpy}) and
+their @code{_FORTIFY_SOURCE} counterparts into faster alternatives.
+
+Enabled at levels @option{-O2}, @option{-O3}.
+
+@item -fno-inline
+@opindex fno-inline
+@opindex finline
+Do not expand any functions inline apart from those marked with
+the @code{always_inline} attribute.  This is the default when not
+optimizing.
+
+Single functions can be exempted from inlining by marking them
+with the @code{noinline} attribute.
+
+@item -finline-small-functions
+@opindex finline-small-functions
+Integrate functions into their callers when their body is smaller than expected
+function call code (so overall size of program gets smaller).  The compiler
+heuristically decides which functions are simple enough to be worth integrating
+in this way.  This inlining applies to all functions, even those not declared
+inline.
+
+Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
+
+@item -findirect-inlining
+@opindex findirect-inlining
+Inline also indirect calls that are discovered to be known at compile
+time thanks to previous inlining.  This option has any effect only
+when inlining itself is turned on by the @option{-finline-functions}
+or @option{-finline-small-functions} options.
+
+Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
+
+@item -finline-functions
+@opindex finline-functions
+Consider all functions for inlining, even if they are not declared inline.
+The compiler heuristically decides which functions are worth integrating
+in this way.
+
+If all calls to a given function are integrated, and the function is
+declared @code{static}, then the function is normally not output as
+assembler code in its own right.
+
+Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.  Also enabled
+by @option{-fprofile-use} and @option{-fauto-profile}.
+
+@item -finline-functions-called-once
+@opindex finline-functions-called-once
+Consider all @code{static} functions called once for inlining into their
+caller even if they are not marked @code{inline}.  If a call to a given
+function is integrated, then the function is not output as assembler code
+in its own right.
+
+Enabled at levels @option{-O1}, @option{-O2}, @option{-O3} and @option{-Os},
+but not @option{-Og}.
+
+@item -fearly-inlining
+@opindex fearly-inlining
+Inline functions marked by @code{always_inline} and functions whose body seems
+smaller than the function call overhead early before doing
+@option{-fprofile-generate} instrumentation and real inlining pass.  Doing so
+makes profiling significantly cheaper and usually inlining faster on programs
+having large chains of nested wrapper functions.
+
+Enabled by default.
+
+@item -fipa-sra
+@opindex fipa-sra
+Perform interprocedural scalar replacement of aggregates, removal of
+unused parameters and replacement of parameters passed by reference
+by parameters passed by value.
+
+Enabled at levels @option{-O2}, @option{-O3} and @option{-Os}.
+
+@item -finline-limit=@var{n}
+@opindex finline-limit
+By default, GCC limits the size of functions that can be inlined.  This flag
+allows coarse control of this limit.  @var{n} is the size of functions that
+can be inlined in number of pseudo instructions.
+
+Inlining is actually controlled by a number of parameters, which may be
+specified individually by using @option{--param @var{name}=@var{value}}.
+The @option{-finline-limit=@var{n}} option sets some of these parameters
+as follows:
+
+@table @gcctabopt
+@item max-inline-insns-single
+is set to @var{n}/2.
+@item max-inline-insns-auto
+is set to @var{n}/2.
+@end table
+
+See below for a documentation of the individual
+parameters controlling inlining and for the defaults of these parameters.
+
+@emph{Note:} there may be no value to @option{-finline-limit} that results
+in default behavior.
+
+@emph{Note:} pseudo instruction represents, in this particular context, an
+abstract measurement of function's size.  In no way does it represent a count
+of assembly instructions and as such its exact meaning might change from one
+release to an another.
+
+@item -fno-keep-inline-dllexport
+@opindex fno-keep-inline-dllexport
+@opindex fkeep-inline-dllexport
+This is a more fine-grained version of @option{-fkeep-inline-functions},
+which applies only to functions that are declared using the @code{dllexport}
+attribute or declspec.  @xref{Function Attributes,,Declaring Attributes of
+Functions}.
+
+@item -fkeep-inline-functions
+@opindex fkeep-inline-functions
+In C, emit @code{static} functions that are declared @code{inline}
+into the object file, even if the function has been inlined into all
+of its callers.  This switch does not affect functions using the
+@code{extern inline} extension in GNU C90@.  In C++, emit any and all
+inline functions into the object file.
+
+@item -fkeep-static-functions
+@opindex fkeep-static-functions
+Emit @code{static} functions into the object file, even if the function
+is never used.
+
+@item -fkeep-static-consts
+@opindex fkeep-static-consts
+Emit variables declared @code{static const} when optimization isn't turned
+on, even if the variables aren't referenced.
+
+GCC enables this option by default.  If you want to force the compiler to
+check if a variable is referenced, regardless of whether or not
+optimization is turned on, use the @option{-fno-keep-static-consts} option.
+
+@item -fmerge-constants
+@opindex fmerge-constants
+Attempt to merge identical constants (string constants and floating-point
+constants) across compilation units.
+
+This option is the default for optimized compilation if the assembler and
+linker support it.  Use @option{-fno-merge-constants} to inhibit this
+behavior.
+
+Enabled at levels @option{-O1}, @option{-O2}, @option{-O3}, @option{-Os}.
+
+@item -fmerge-all-constants
+@opindex fmerge-all-constants
+Attempt to merge identical constants and identical variables.
+
+This option implies @option{-fmerge-constants}.  In addition to
+@option{-fmerge-constants} this considers e.g.@: even constant initialized
+arrays or initialized constant variables with integral or floating-point
+types.  Languages like C or C++ require each variable, including multiple
+instances of the same variable in recursive calls, to have distinct locations,
+so using this option results in non-conforming
+behavior.
+
+@item -fmodulo-sched
+@opindex fmodulo-sched
+Perform swing modulo scheduling immediately before the first scheduling
+pass.  This pass looks at innermost loops and reorders their
+instructions by overlapping different iterations.
+
+@item -fmodulo-sched-allow-regmoves
+@opindex fmodulo-sched-allow-regmoves
+Perform more aggressive SMS-based modulo scheduling with register moves
+allowed.  By setting this flag certain anti-dependences edges are
+deleted, which triggers the generation of reg-moves based on the
+life-range analysis.  This option is effective only with
+@option{-fmodulo-sched} enabled.
+
+@item -fno-branch-count-reg
+@opindex fno-branch-count-reg
+@opindex fbranch-count-reg
+Disable the optimization pass that scans for opportunities to use 
+``decrement and branch'' instructions on a count register instead of
+instruction sequences that decrement a register, compare it against zero, and
+then branch based upon the result.  This option is only meaningful on
+architectures that support such instructions, which include x86, PowerPC,
+IA-64 and S/390.  Note that the @option{-fno-branch-count-reg} option
+doesn't remove the decrement and branch instructions from the generated
+instruction stream introduced by other optimization passes.
+
+The default is @option{-fbranch-count-reg} at @option{-O1} and higher,
+except for @option{-Og}.
+
+@item -fno-function-cse
+@opindex fno-function-cse
+@opindex ffunction-cse
+Do not put function addresses in registers; make each instruction that
+calls a constant function contain the function's address explicitly.
+
+This option results in less efficient code, but some strange hacks
+that alter the assembler output may be confused by the optimizations
+performed when this option is not used.
+
+The default is @option{-ffunction-cse}
+
+@item -fno-zero-initialized-in-bss
+@opindex fno-zero-initialized-in-bss
+@opindex fzero-initialized-in-bss
+If the target supports a BSS section, GCC by default puts variables that
+are initialized to zero into BSS@.  This can save space in the resulting
+code.
+
+This option turns off this behavior because some programs explicitly
+rely on variables going to the data section---e.g., so that the
+resulting executable can find the beginning of that section and/or make
+assumptions based on that.
+
+The default is @option{-fzero-initialized-in-bss}.
+
+@item -fthread-jumps
+@opindex fthread-jumps
+Perform optimizations that check to see if a jump branches to a
+location where another comparison subsumed by the first is found.  If
+so, the first branch is redirected to either the destination of the
+second branch or a point immediately following it, depending on whether
+the condition is known to be true or false.
+
+Enabled at levels @option{-O1}, @option{-O2}, @option{-O3}, @option{-Os}.
+
+@item -fsplit-wide-types
+@opindex fsplit-wide-types
+When using a type that occupies multiple registers, such as @code{long
+long} on a 32-bit system, split the registers apart and allocate them
+independently.  This normally generates better code for those types,
+but may make debugging more difficult.
+
+Enabled at levels @option{-O1}, @option{-O2}, @option{-O3},
+@option{-Os}.
+
+@item -fsplit-wide-types-early
+@opindex fsplit-wide-types-early
+Fully split wide types early, instead of very late.
+This option has no effect unless @option{-fsplit-wide-types} is turned on.
+
+This is the default on some targets.
+
+@item -fcse-follow-jumps
+@opindex fcse-follow-jumps
+In common subexpression elimination (CSE), scan through jump instructions
+when the target of the jump is not reached by any other path.  For
+example, when CSE encounters an @code{if} statement with an
+@code{else} clause, CSE follows the jump when the condition
+tested is false.
+
+Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
+
+@item -fcse-skip-blocks
+@opindex fcse-skip-blocks
+This is similar to @option{-fcse-follow-jumps}, but causes CSE to
+follow jumps that conditionally skip over blocks.  When CSE
+encounters a simple @code{if} statement with no else clause,
+@option{-fcse-skip-blocks} causes CSE to follow the jump around the
+body of the @code{if}.
+
+Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
+
+@item -frerun-cse-after-loop
+@opindex frerun-cse-after-loop
+Re-run common subexpression elimination after loop optimizations are
+performed.
+
+Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
+
+@item -fgcse
+@opindex fgcse
+Perform a global common subexpression elimination pass.
+This pass also performs global constant and copy propagation.
+
+@emph{Note:} When compiling a program using computed gotos, a GCC
+extension, you may get better run-time performance if you disable
+the global common subexpression elimination pass by adding
+@option{-fno-gcse} to the command line.
+
+Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
+
+@item -fgcse-lm
+@opindex fgcse-lm
+When @option{-fgcse-lm} is enabled, global common subexpression elimination
+attempts to move loads that are only killed by stores into themselves.  This
+allows a loop containing a load/store sequence to be changed to a load outside
+the loop, and a copy/store within the loop.
+
+Enabled by default when @option{-fgcse} is enabled.
+
+@item -fgcse-sm
+@opindex fgcse-sm
+When @option{-fgcse-sm} is enabled, a store motion pass is run after
+global common subexpression elimination.  This pass attempts to move
+stores out of loops.  When used in conjunction with @option{-fgcse-lm},
+loops containing a load/store sequence can be changed to a load before
+the loop and a store after the loop.
+
+Not enabled at any optimization level.
+
+@item -fgcse-las
+@opindex fgcse-las
+When @option{-fgcse-las} is enabled, the global common subexpression
+elimination pass eliminates redundant loads that come after stores to the
+same memory location (both partial and full redundancies).
+
+Not enabled at any optimization level.
+
+@item -fgcse-after-reload
+@opindex fgcse-after-reload
+When @option{-fgcse-after-reload} is enabled, a redundant load elimination
+pass is performed after reload.  The purpose of this pass is to clean up
+redundant spilling.
+
+Enabled by @option{-O3}, @option{-fprofile-use} and @option{-fauto-profile}.
+
+@item -faggressive-loop-optimizations
+@opindex faggressive-loop-optimizations
+This option tells the loop optimizer to use language constraints to
+derive bounds for the number of iterations of a loop.  This assumes that
+loop code does not invoke undefined behavior by for example causing signed
+integer overflows or out-of-bound array accesses.  The bounds for the
+number of iterations of a loop are used to guide loop unrolling and peeling
+and loop exit test optimizations.
+This option is enabled by default.
+
+@item -funconstrained-commons
+@opindex funconstrained-commons
+This option tells the compiler that variables declared in common blocks
+(e.g.@: Fortran) may later be overridden with longer trailing arrays. This
+prevents certain optimizations that depend on knowing the array bounds.
+
+@item -fcrossjumping
+@opindex fcrossjumping
+Perform cross-jumping transformation.
+This transformation unifies equivalent code and saves code size.  The
+resulting code may or may not perform better than without cross-jumping.
+
+Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
+
+@item -fauto-inc-dec
+@opindex fauto-inc-dec
+Combine increments or decrements of addresses with memory accesses.
+This pass is always skipped on architectures that do not have
+instructions to support this.  Enabled by default at @option{-O1} and
+higher on architectures that support this.
+
+@item -fdce
+@opindex fdce
+Perform dead code elimination (DCE) on RTL@.
+Enabled by default at @option{-O1} and higher.
+
+@item -fdse
+@opindex fdse
+Perform dead store elimination (DSE) on RTL@.
+Enabled by default at @option{-O1} and higher.
+
+@item -fif-conversion
+@opindex fif-conversion
+Attempt to transform conditional jumps into branch-less equivalents.  This
+includes use of conditional moves, min, max, set flags and abs instructions, and
+some tricks doable by standard arithmetics.  The use of conditional execution
+on chips where it is available is controlled by @option{-fif-conversion2}.
+
+Enabled at levels @option{-O1}, @option{-O2}, @option{-O3}, @option{-Os}, but
+not with @option{-Og}.
+
+@item -fif-conversion2
+@opindex fif-conversion2
+Use conditional execution (where available) to transform conditional jumps into
+branch-less equivalents.
+
+Enabled at levels @option{-O1}, @option{-O2}, @option{-O3}, @option{-Os}, but
+not with @option{-Og}.
+
+@item -fdeclone-ctor-dtor
+@opindex fdeclone-ctor-dtor
+The C++ ABI requires multiple entry points for constructors and
+destructors: one for a base subobject, one for a complete object, and
+one for a virtual destructor that calls operator delete afterwards.
+For a hierarchy with virtual bases, the base and complete variants are
+clones, which means two copies of the function.  With this option, the
+base and complete variants are changed to be thunks that call a common
+implementation.
+
+Enabled by @option{-Os}.
+
+@item -fdelete-null-pointer-checks
+@opindex fdelete-null-pointer-checks
+Assume that programs cannot safely dereference null pointers, and that
+no code or data element resides at address zero.
+This option enables simple constant
+folding optimizations at all optimization levels.  In addition, other
+optimization passes in GCC use this flag to control global dataflow
+analyses that eliminate useless checks for null pointers; these assume
+that a memory access to address zero always results in a trap, so
+that if a pointer is checked after it has already been dereferenced,
+it cannot be null.
+
+Note however that in some environments this assumption is not true.
+Use @option{-fno-delete-null-pointer-checks} to disable this optimization
+for programs that depend on that behavior.
+
+This option is enabled by default on most targets.  On Nios II ELF, it
+defaults to off.  On AVR and MSP430, this option is completely disabled.
+
+Passes that use the dataflow information
+are enabled independently at different optimization levels.
+
+@item -fdevirtualize
+@opindex fdevirtualize
+Attempt to convert calls to virtual functions to direct calls.  This
+is done both within a procedure and interprocedurally as part of
+indirect inlining (@option{-findirect-inlining}) and interprocedural constant
+propagation (@option{-fipa-cp}).
+Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
+
+@item -fdevirtualize-speculatively
+@opindex fdevirtualize-speculatively
+Attempt to convert calls to virtual functions to speculative direct calls.
+Based on the analysis of the type inheritance graph, determine for a given call
+the set of likely targets. If the set is small, preferably of size 1, change
+the call into a conditional deciding between direct and indirect calls.  The
+speculative calls enable more optimizations, such as inlining.  When they seem
+useless after further optimization, they are converted back into original form.
+
+@item -fdevirtualize-at-ltrans
+@opindex fdevirtualize-at-ltrans
+Stream extra information needed for aggressive devirtualization when running
+the link-time optimizer in local transformation mode.  
+This option enables more devirtualization but
+significantly increases the size of streamed data. For this reason it is
+disabled by default.
+
+@item -fexpensive-optimizations
+@opindex fexpensive-optimizations
+Perform a number of minor optimizations that are relatively expensive.
+
+Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
+
+@item -free
+@opindex free
+Attempt to remove redundant extension instructions.  This is especially
+helpful for the x86-64 architecture, which implicitly zero-extends in 64-bit
+registers after writing to their lower 32-bit half.
+
+Enabled for Alpha, AArch64 and x86 at levels @option{-O2},
+@option{-O3}, @option{-Os}.
+
+@item -fno-lifetime-dse
+@opindex fno-lifetime-dse
+@opindex flifetime-dse
+In C++ the value of an object is only affected by changes within its
+lifetime: when the constructor begins, the object has an indeterminate
+value, and any changes during the lifetime of the object are dead when
+the object is destroyed.  Normally dead store elimination will take
+advantage of this; if your code relies on the value of the object
+storage persisting beyond the lifetime of the object, you can use this
+flag to disable this optimization.  To preserve stores before the
+constructor starts (e.g.@: because your operator new clears the object
+storage) but still treat the object as dead after the destructor, you
+can use @option{-flifetime-dse=1}.  The default behavior can be
+explicitly selected with @option{-flifetime-dse=2}.
+@option{-flifetime-dse=0} is equivalent to @option{-fno-lifetime-dse}.
+
+@item -flive-range-shrinkage
+@opindex flive-range-shrinkage
+Attempt to decrease register pressure through register live range
+shrinkage.  This is helpful for fast processors with small or moderate
+size register sets.
+
+@item -fira-algorithm=@var{algorithm}
+@opindex fira-algorithm
+Use the specified coloring algorithm for the integrated register
+allocator.  The @var{algorithm} argument can be @samp{priority}, which
+specifies Chow's priority coloring, or @samp{CB}, which specifies
+Chaitin-Briggs coloring.  Chaitin-Briggs coloring is not implemented
+for all architectures, but for those targets that do support it, it is
+the default because it generates better code.
+
+@item -fira-region=@var{region}
+@opindex fira-region
+Use specified regions for the integrated register allocator.  The
+@var{region} argument should be one of the following:
+
+@table @samp
+
+@item all
+Use all loops as register allocation regions.
+This can give the best results for machines with a small and/or
+irregular register set.
+
+@item mixed
+Use all loops except for loops with small register pressure 
+as the regions.  This value usually gives
+the best results in most cases and for most architectures,
+and is enabled by default when compiling with optimization for speed
+(@option{-O}, @option{-O2}, @dots{}).
+
+@item one
+Use all functions as a single region.  
+This typically results in the smallest code size, and is enabled by default for
+@option{-Os} or @option{-O0}.
+
+@end table
+
+@item -fira-hoist-pressure
+@opindex fira-hoist-pressure
+Use IRA to evaluate register pressure in the code hoisting pass for
+decisions to hoist expressions.  This option usually results in smaller
+code, but it can slow the compiler down.
+
+This option is enabled at level @option{-Os} for all targets.
+
+@item -fira-loop-pressure
+@opindex fira-loop-pressure
+Use IRA to evaluate register pressure in loops for decisions to move
+loop invariants.  This option usually results in generation
+of faster and smaller code on machines with large register files (>= 32
+registers), but it can slow the compiler down.
+
+This option is enabled at level @option{-O3} for some targets.
+
+@item -fno-ira-share-save-slots
+@opindex fno-ira-share-save-slots
+@opindex fira-share-save-slots
+Disable sharing of stack slots used for saving call-used hard
+registers living through a call.  Each hard register gets a
+separate stack slot, and as a result function stack frames are
+larger.
+
+@item -fno-ira-share-spill-slots
+@opindex fno-ira-share-spill-slots
+@opindex fira-share-spill-slots
+Disable sharing of stack slots allocated for pseudo-registers.  Each
+pseudo-register that does not get a hard register gets a separate
+stack slot, and as a result function stack frames are larger.
+
+@item -flra-remat
+@opindex flra-remat
+Enable CFG-sensitive rematerialization in LRA.  Instead of loading
+values of spilled pseudos, LRA tries to rematerialize (recalculate)
+values if it is profitable.
+
+Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
+
+@item -fdelayed-branch
+@opindex fdelayed-branch
+If supported for the target machine, attempt to reorder instructions
+to exploit instruction slots available after delayed branch
+instructions.
+
+Enabled at levels @option{-O1}, @option{-O2}, @option{-O3}, @option{-Os},
+but not at @option{-Og}.
+
+@item -fschedule-insns
+@opindex fschedule-insns
+If supported for the target machine, attempt to reorder instructions to
+eliminate execution stalls due to required data being unavailable.  This
+helps machines that have slow floating point or memory load instructions
+by allowing other instructions to be issued until the result of the load
+or floating-point instruction is required.
+
+Enabled at levels @option{-O2}, @option{-O3}.
+
+@item -fschedule-insns2
+@opindex fschedule-insns2
+Similar to @option{-fschedule-insns}, but requests an additional pass of
+instruction scheduling after register allocation has been done.  This is
+especially useful on machines with a relatively small number of
+registers and where memory load instructions take more than one cycle.
+
+Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
+
+@item -fno-sched-interblock
+@opindex fno-sched-interblock
+@opindex fsched-interblock
+Disable instruction scheduling across basic blocks, which
+is normally enabled when scheduling before register allocation, i.e.@:
+with @option{-fschedule-insns} or at @option{-O2} or higher.
+
+@item -fno-sched-spec
+@opindex fno-sched-spec
+@opindex fsched-spec
+Disable speculative motion of non-load instructions, which
+is normally enabled when scheduling before register allocation, i.e.@:
+with @option{-fschedule-insns} or at @option{-O2} or higher.
+
+@item -fsched-pressure
+@opindex fsched-pressure
+Enable register pressure sensitive insn scheduling before register
+allocation.  This only makes sense when scheduling before register
+allocation is enabled, i.e.@: with @option{-fschedule-insns} or at
+@option{-O2} or higher.  Usage of this option can improve the
+generated code and decrease its size by preventing register pressure
+increase above the number of available hard registers and subsequent
+spills in register allocation.
+
+@item -fsched-spec-load
+@opindex fsched-spec-load
+Allow speculative motion of some load instructions.  This only makes
+sense when scheduling before register allocation, i.e.@: with
+@option{-fschedule-insns} or at @option{-O2} or higher.
+
+@item -fsched-spec-load-dangerous
+@opindex fsched-spec-load-dangerous
+Allow speculative motion of more load instructions.  This only makes
+sense when scheduling before register allocation, i.e.@: with
+@option{-fschedule-insns} or at @option{-O2} or higher.
+
+@item -fsched-stalled-insns
+@itemx -fsched-stalled-insns=@var{n}
+@opindex fsched-stalled-insns
+Define how many insns (if any) can be moved prematurely from the queue
+of stalled insns into the ready list during the second scheduling pass.
+@option{-fno-sched-stalled-insns} means that no insns are moved
+prematurely, @option{-fsched-stalled-insns=0} means there is no limit
+on how many queued insns can be moved prematurely.
+@option{-fsched-stalled-insns} without a value is equivalent to
+@option{-fsched-stalled-insns=1}.
+
+@item -fsched-stalled-insns-dep
+@itemx -fsched-stalled-insns-dep=@var{n}
+@opindex fsched-stalled-insns-dep
+Define how many insn groups (cycles) are examined for a dependency
+on a stalled insn that is a candidate for premature removal from the queue
+of stalled insns.  This has an effect only during the second scheduling pass,
+and only if @option{-fsched-stalled-insns} is used.
+@option{-fno-sched-stalled-insns-dep} is equivalent to
+@option{-fsched-stalled-insns-dep=0}.
+@option{-fsched-stalled-insns-dep} without a value is equivalent to
+@option{-fsched-stalled-insns-dep=1}.
+
+@item -fsched2-use-superblocks
+@opindex fsched2-use-superblocks
+When scheduling after register allocation, use superblock scheduling.
+This allows motion across basic block boundaries,
+resulting in faster schedules.  This option is experimental, as not all machine
+descriptions used by GCC model the CPU closely enough to avoid unreliable
+results from the algorithm.
+
+This only makes sense when scheduling after register allocation, i.e.@: with
+@option{-fschedule-insns2} or at @option{-O2} or higher.
+
+@item -fsched-group-heuristic
+@opindex fsched-group-heuristic
+Enable the group heuristic in the scheduler.  This heuristic favors
+the instruction that belongs to a schedule group.  This is enabled
+by default when scheduling is enabled, i.e.@: with @option{-fschedule-insns}
+or @option{-fschedule-insns2} or at @option{-O2} or higher.
+
+@item -fsched-critical-path-heuristic
+@opindex fsched-critical-path-heuristic
+Enable the critical-path heuristic in the scheduler.  This heuristic favors
+instructions on the critical path.  This is enabled by default when
+scheduling is enabled, i.e.@: with @option{-fschedule-insns}
+or @option{-fschedule-insns2} or at @option{-O2} or higher.
+
+@item -fsched-spec-insn-heuristic
+@opindex fsched-spec-insn-heuristic
+Enable the speculative instruction heuristic in the scheduler.  This
+heuristic favors speculative instructions with greater dependency weakness.
+This is enabled by default when scheduling is enabled, i.e.@:
+with @option{-fschedule-insns} or @option{-fschedule-insns2}
+or at @option{-O2} or higher.
+
+@item -fsched-rank-heuristic
+@opindex fsched-rank-heuristic
+Enable the rank heuristic in the scheduler.  This heuristic favors
+the instruction belonging to a basic block with greater size or frequency.
+This is enabled by default when scheduling is enabled, i.e.@:
+with @option{-fschedule-insns} or @option{-fschedule-insns2} or
+at @option{-O2} or higher.
+
+@item -fsched-last-insn-heuristic
+@opindex fsched-last-insn-heuristic
+Enable the last-instruction heuristic in the scheduler.  This heuristic
+favors the instruction that is less dependent on the last instruction
+scheduled.  This is enabled by default when scheduling is enabled,
+i.e.@: with @option{-fschedule-insns} or @option{-fschedule-insns2} or
+at @option{-O2} or higher.
+
+@item -fsched-dep-count-heuristic
+@opindex fsched-dep-count-heuristic
+Enable the dependent-count heuristic in the scheduler.  This heuristic
+favors the instruction that has more instructions depending on it.
+This is enabled by default when scheduling is enabled, i.e.@:
+with @option{-fschedule-insns} or @option{-fschedule-insns2} or
+at @option{-O2} or higher.
+
+@item -freschedule-modulo-scheduled-loops
+@opindex freschedule-modulo-scheduled-loops
+Modulo scheduling is performed before traditional scheduling.  If a loop
+is modulo scheduled, later scheduling passes may change its schedule.  
+Use this option to control that behavior.
+
+@item -fselective-scheduling
+@opindex fselective-scheduling
+Schedule instructions using selective scheduling algorithm.  Selective
+scheduling runs instead of the first scheduler pass.
+
+@item -fselective-scheduling2
+@opindex fselective-scheduling2
+Schedule instructions using selective scheduling algorithm.  Selective
+scheduling runs instead of the second scheduler pass.
+
+@item -fsel-sched-pipelining
+@opindex fsel-sched-pipelining
+Enable software pipelining of innermost loops during selective scheduling.
+This option has no effect unless one of @option{-fselective-scheduling} or
+@option{-fselective-scheduling2} is turned on.
+
+@item -fsel-sched-pipelining-outer-loops
+@opindex fsel-sched-pipelining-outer-loops
+When pipelining loops during selective scheduling, also pipeline outer loops.
+This option has no effect unless @option{-fsel-sched-pipelining} is turned on.
+
+@item -fsemantic-interposition
+@opindex fsemantic-interposition
+Some object formats, like ELF, allow interposing of symbols by the 
+dynamic linker.
+This means that for symbols exported from the DSO, the compiler cannot perform
+interprocedural propagation, inlining and other optimizations in anticipation
+that the function or variable in question may change. While this feature is
+useful, for example, to rewrite memory allocation functions by a debugging
+implementation, it is expensive in the terms of code quality.
+With @option{-fno-semantic-interposition} the compiler assumes that 
+if interposition happens for functions the overwriting function will have 
+precisely the same semantics (and side effects). 
+Similarly if interposition happens
+for variables, the constructor of the variable will be the same. The flag
+has no effect for functions explicitly declared inline 
+(where it is never allowed for interposition to change semantics) 
+and for symbols explicitly declared weak.
+
+@item -fshrink-wrap
+@opindex fshrink-wrap
+Emit function prologues only before parts of the function that need it,
+rather than at the top of the function.  This flag is enabled by default at
+@option{-O} and higher.
+
+@item -fshrink-wrap-separate
+@opindex fshrink-wrap-separate
+Shrink-wrap separate parts of the prologue and epilogue separately, so that
+those parts are only executed when needed.
+This option is on by default, but has no effect unless @option{-fshrink-wrap}
+is also turned on and the target supports this.
+
+@item -fcaller-saves
+@opindex fcaller-saves
+Enable allocation of values to registers that are clobbered by
+function calls, by emitting extra instructions to save and restore the
+registers around such calls.  Such allocation is done only when it
+seems to result in better code.
+
+This option is always enabled by default on certain machines, usually
+those which have no call-preserved registers to use instead.
+
+Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
+
+@item -fcombine-stack-adjustments
+@opindex fcombine-stack-adjustments
+Tracks stack adjustments (pushes and pops) and stack memory references
+and then tries to find ways to combine them.
+
+Enabled by default at @option{-O1} and higher.
+
+@item -fipa-ra
+@opindex fipa-ra
+Use caller save registers for allocation if those registers are not used by
+any called function.  In that case it is not necessary to save and restore
+them around calls.  This is only possible if called functions are part of
+same compilation unit as current function and they are compiled before it.
+
+Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}, however the option
+is disabled if generated code will be instrumented for profiling
+(@option{-p}, or @option{-pg}) or if callee's register usage cannot be known
+exactly (this happens on targets that do not expose prologues
+and epilogues in RTL).
+
+@item -fconserve-stack
+@opindex fconserve-stack
+Attempt to minimize stack usage.  The compiler attempts to use less
+stack space, even if that makes the program slower.  This option
+implies setting the @option{large-stack-frame} parameter to 100
+and the @option{large-stack-frame-growth} parameter to 400.
+
+@item -ftree-reassoc
+@opindex ftree-reassoc
+Perform reassociation on trees.  This flag is enabled by default
+at @option{-O1} and higher.
+
+@item -fcode-hoisting
+@opindex fcode-hoisting
+Perform code hoisting.  Code hoisting tries to move the
+evaluation of expressions executed on all paths to the function exit
+as early as possible.  This is especially useful as a code size
+optimization, but it often helps for code speed as well.
+This flag is enabled by default at @option{-O2} and higher.
+
+@item -ftree-pre
+@opindex ftree-pre
+Perform partial redundancy elimination (PRE) on trees.  This flag is
+enabled by default at @option{-O2} and @option{-O3}.
+
+@item -ftree-partial-pre
+@opindex ftree-partial-pre
+Make partial redundancy elimination (PRE) more aggressive.  This flag is
+enabled by default at @option{-O3}.
+
+@item -ftree-forwprop
+@opindex ftree-forwprop
+Perform forward propagation on trees.  This flag is enabled by default
+at @option{-O1} and higher.
+
+@item -ftree-fre
+@opindex ftree-fre
+Perform full redundancy elimination (FRE) on trees.  The difference
+between FRE and PRE is that FRE only considers expressions
+that are computed on all paths leading to the redundant computation.
+This analysis is faster than PRE, though it exposes fewer redundancies.
+This flag is enabled by default at @option{-O1} and higher.
+
+@item -ftree-phiprop
+@opindex ftree-phiprop
+Perform hoisting of loads from conditional pointers on trees.  This
+pass is enabled by default at @option{-O1} and higher.
+
+@item -fhoist-adjacent-loads
+@opindex fhoist-adjacent-loads
+Speculatively hoist loads from both branches of an if-then-else if the
+loads are from adjacent locations in the same structure and the target
+architecture has a conditional move instruction.  This flag is enabled
+by default at @option{-O2} and higher.
+
+@item -ftree-copy-prop
+@opindex ftree-copy-prop
+Perform copy propagation on trees.  This pass eliminates unnecessary
+copy operations.  This flag is enabled by default at @option{-O1} and
+higher.
+
+@item -fipa-pure-const
+@opindex fipa-pure-const
+Discover which functions are pure or constant.
+Enabled by default at @option{-O1} and higher.
+
+@item -fipa-reference
+@opindex fipa-reference
+Discover which static variables do not escape the
+compilation unit.
+Enabled by default at @option{-O1} and higher.
+
+@item -fipa-reference-addressable
+@opindex fipa-reference-addressable
+Discover read-only, write-only and non-addressable static variables.
+Enabled by default at @option{-O1} and higher.
+
+@item -fipa-stack-alignment
+@opindex fipa-stack-alignment
+Reduce stack alignment on call sites if possible.
+Enabled by default.
+
+@item -fipa-pta
+@opindex fipa-pta
+Perform interprocedural pointer analysis and interprocedural modification
+and reference analysis.  This option can cause excessive memory and
+compile-time usage on large compilation units.  It is not enabled by
+default at any optimization level.
+
+@item -fipa-profile
+@opindex fipa-profile
+Perform interprocedural profile propagation.  The functions called only from
+cold functions are marked as cold. Also functions executed once (such as
+@code{cold}, @code{noreturn}, static constructors or destructors) are
+identified. Cold functions and loop less parts of functions executed once are
+then optimized for size.
+Enabled by default at @option{-O1} and higher.
+
+@item -fipa-modref
+@opindex fipa-modref
+Perform interprocedural mod/ref analysis.  This optimization analyzes the side
+effects of functions (memory locations that are modified or referenced) and
+enables better optimization across the function call boundary.  This flag is
+enabled by default at @option{-O1} and higher.
+
+@item -fipa-cp
+@opindex fipa-cp
+Perform interprocedural constant propagation.
+This optimization analyzes the program to determine when values passed
+to functions are constants and then optimizes accordingly.
+This optimization can substantially increase performance
+if the application has constants passed to functions.
+This flag is enabled by default at @option{-O2}, @option{-Os} and @option{-O3}.
+It is also enabled by @option{-fprofile-use} and @option{-fauto-profile}.
+
+@item -fipa-cp-clone
+@opindex fipa-cp-clone
+Perform function cloning to make interprocedural constant propagation stronger.
+When enabled, interprocedural constant propagation performs function cloning
+when externally visible function can be called with constant arguments.
+Because this optimization can create multiple copies of functions,
+it may significantly increase code size
+(see @option{--param ipa-cp-unit-growth=@var{value}}).
+This flag is enabled by default at @option{-O3}.
+It is also enabled by @option{-fprofile-use} and @option{-fauto-profile}.
+
+@item -fipa-bit-cp
+@opindex fipa-bit-cp
+When enabled, perform interprocedural bitwise constant
+propagation. This flag is enabled by default at @option{-O2} and
+by @option{-fprofile-use} and @option{-fauto-profile}.
+It requires that @option{-fipa-cp} is enabled.  
+
+@item -fipa-vrp
+@opindex fipa-vrp
+When enabled, perform interprocedural propagation of value
+ranges. This flag is enabled by default at @option{-O2}. It requires
+that @option{-fipa-cp} is enabled.
+
+@item -fipa-icf
+@opindex fipa-icf
+Perform Identical Code Folding for functions and read-only variables.
+The optimization reduces code size and may disturb unwind stacks by replacing
+a function by equivalent one with a different name. The optimization works
+more effectively with link-time optimization enabled.
+
+Although the behavior is similar to the Gold Linker's ICF optimization, GCC ICF
+works on different levels and thus the optimizations are not same - there are
+equivalences that are found only by GCC and equivalences found only by Gold.
+
+This flag is enabled by default at @option{-O2} and @option{-Os}.
+
+@item -flive-patching=@var{level}
+@opindex flive-patching
+Control GCC's optimizations to produce output suitable for live-patching.
+
+If the compiler's optimization uses a function's body or information extracted
+from its body to optimize/change another function, the latter is called an
+impacted function of the former.  If a function is patched, its impacted
+functions should be patched too.
+
+The impacted functions are determined by the compiler's interprocedural
+optimizations.  For example, a caller is impacted when inlining a function
+into its caller,
+cloning a function and changing its caller to call this new clone,
+or extracting a function's pureness/constness information to optimize
+its direct or indirect callers, etc.
+
+Usually, the more IPA optimizations enabled, the larger the number of
+impacted functions for each function.  In order to control the number of
+impacted functions and more easily compute the list of impacted function,
+IPA optimizations can be partially enabled at two different levels.
+
+The @var{level} argument should be one of the following:
+
+@table @samp
+
+@item inline-clone
+
+Only enable inlining and cloning optimizations, which includes inlining,
+cloning, interprocedural scalar replacement of aggregates and partial inlining.
+As a result, when patching a function, all its callers and its clones'
+callers are impacted, therefore need to be patched as well.
+
+@option{-flive-patching=inline-clone} disables the following optimization flags:
+@gccoptlist{-fwhole-program  -fipa-pta  -fipa-reference  -fipa-ra @gol
+-fipa-icf  -fipa-icf-functions  -fipa-icf-variables @gol
+-fipa-bit-cp  -fipa-vrp  -fipa-pure-const  -fipa-reference-addressable @gol
+-fipa-stack-alignment -fipa-modref}
+
+@item inline-only-static
+
+Only enable inlining of static functions.
+As a result, when patching a static function, all its callers are impacted
+and so need to be patched as well.
+
+In addition to all the flags that @option{-flive-patching=inline-clone}
+disables,
+@option{-flive-patching=inline-only-static} disables the following additional
+optimization flags:
+@gccoptlist{-fipa-cp-clone  -fipa-sra  -fpartial-inlining  -fipa-cp}
+
+@end table
+
+When @option{-flive-patching} is specified without any value, the default value
+is @var{inline-clone}.
+
+This flag is disabled by default.
+
+Note that @option{-flive-patching} is not supported with link-time optimization
+(@option{-flto}).
+
+@item -fisolate-erroneous-paths-dereference
+@opindex fisolate-erroneous-paths-dereference
+Detect paths that trigger erroneous or undefined behavior due to
+dereferencing a null pointer.  Isolate those paths from the main control
+flow and turn the statement with erroneous or undefined behavior into a trap.
+This flag is enabled by default at @option{-O2} and higher and depends on
+@option{-fdelete-null-pointer-checks} also being enabled.
+
+@item -fisolate-erroneous-paths-attribute
+@opindex fisolate-erroneous-paths-attribute
+Detect paths that trigger erroneous or undefined behavior due to a null value
+being used in a way forbidden by a @code{returns_nonnull} or @code{nonnull}
+attribute.  Isolate those paths from the main control flow and turn the
+statement with erroneous or undefined behavior into a trap.  This is not
+currently enabled, but may be enabled by @option{-O2} in the future.
+
+@item -ftree-sink
+@opindex ftree-sink
+Perform forward store motion on trees.  This flag is
+enabled by default at @option{-O1} and higher.
+
+@item -ftree-bit-ccp
+@opindex ftree-bit-ccp
+Perform sparse conditional bit constant propagation on trees and propagate
+pointer alignment information.
+This pass only operates on local scalar variables and is enabled by default
+at @option{-O1} and higher, except for @option{-Og}.
+It requires that @option{-ftree-ccp} is enabled.
+
+@item -ftree-ccp
+@opindex ftree-ccp
+Perform sparse conditional constant propagation (CCP) on trees.  This
+pass only operates on local scalar variables and is enabled by default
+at @option{-O1} and higher.
+
+@item -fssa-backprop
+@opindex fssa-backprop
+Propagate information about uses of a value up the definition chain
+in order to simplify the definitions.  For example, this pass strips
+sign operations if the sign of a value never matters.  The flag is
+enabled by default at @option{-O1} and higher.
+
+@item -fssa-phiopt
+@opindex fssa-phiopt
+Perform pattern matching on SSA PHI nodes to optimize conditional
+code.  This pass is enabled by default at @option{-O1} and higher,
+except for @option{-Og}.
+
+@item -ftree-switch-conversion
+@opindex ftree-switch-conversion
+Perform conversion of simple initializations in a switch to
+initializations from a scalar array.  This flag is enabled by default
+at @option{-O2} and higher.
+
+@item -ftree-tail-merge
+@opindex ftree-tail-merge
+Look for identical code sequences.  When found, replace one with a jump to the
+other.  This optimization is known as tail merging or cross jumping.  This flag
+is enabled by default at @option{-O2} and higher.  The compilation time
+in this pass can
+be limited using @option{max-tail-merge-comparisons} parameter and
+@option{max-tail-merge-iterations} parameter.
+
+@item -ftree-dce
+@opindex ftree-dce
+Perform dead code elimination (DCE) on trees.  This flag is enabled by
+default at @option{-O1} and higher.
+
+@item -ftree-builtin-call-dce
+@opindex ftree-builtin-call-dce
+Perform conditional dead code elimination (DCE) for calls to built-in functions
+that may set @code{errno} but are otherwise free of side effects.  This flag is
+enabled by default at @option{-O2} and higher if @option{-Os} is not also
+specified.
+
+@item -ffinite-loops
+@opindex ffinite-loops
+@opindex fno-finite-loops
+Assume that a loop with an exit will eventually take the exit and not loop
+indefinitely.  This allows the compiler to remove loops that otherwise have
+no side-effects, not considering eventual endless looping as such.
+
+This option is enabled by default at @option{-O2} for C++ with -std=c++11
+or higher.
+
+@item -ftree-dominator-opts
+@opindex ftree-dominator-opts
+Perform a variety of simple scalar cleanups (constant/copy
+propagation, redundancy elimination, range propagation and expression
+simplification) based on a dominator tree traversal.  This also
+performs jump threading (to reduce jumps to jumps). This flag is
+enabled by default at @option{-O1} and higher.
+
+@item -ftree-dse
+@opindex ftree-dse
+Perform dead store elimination (DSE) on trees.  A dead store is a store into
+a memory location that is later overwritten by another store without
+any intervening loads.  In this case the earlier store can be deleted.  This
+flag is enabled by default at @option{-O1} and higher.
+
+@item -ftree-ch
+@opindex ftree-ch
+Perform loop header copying on trees.  This is beneficial since it increases
+effectiveness of code motion optimizations.  It also saves one jump.  This flag
+is enabled by default at @option{-O1} and higher.  It is not enabled
+for @option{-Os}, since it usually increases code size.
+
+@item -ftree-loop-optimize
+@opindex ftree-loop-optimize
+Perform loop optimizations on trees.  This flag is enabled by default
+at @option{-O1} and higher.
+
+@item -ftree-loop-linear
+@itemx -floop-strip-mine
+@itemx -floop-block
+@opindex ftree-loop-linear
+@opindex floop-strip-mine
+@opindex floop-block
+Perform loop nest optimizations.  Same as
+@option{-floop-nest-optimize}.  To use this code transformation, GCC has
+to be configured with @option{--with-isl} to enable the Graphite loop
+transformation infrastructure.
+
+@item -fgraphite-identity
+@opindex fgraphite-identity
+Enable the identity transformation for graphite.  For every SCoP we generate
+the polyhedral representation and transform it back to gimple.  Using
+@option{-fgraphite-identity} we can check the costs or benefits of the
+GIMPLE -> GRAPHITE -> GIMPLE transformation.  Some minimal optimizations
+are also performed by the code generator isl, like index splitting and
+dead code elimination in loops.
+
+@item -floop-nest-optimize
+@opindex floop-nest-optimize
+Enable the isl based loop nest optimizer.  This is a generic loop nest
+optimizer based on the Pluto optimization algorithms.  It calculates a loop
+structure optimized for data-locality and parallelism.  This option
+is experimental.
+
+@item -floop-parallelize-all
+@opindex floop-parallelize-all
+Use the Graphite data dependence analysis to identify loops that can
+be parallelized.  Parallelize all the loops that can be analyzed to
+not contain loop carried dependences without checking that it is
+profitable to parallelize the loops.
+
+@item -ftree-coalesce-vars
+@opindex ftree-coalesce-vars
+While transforming the program out of the SSA representation, attempt to
+reduce copying by coalescing versions of different user-defined
+variables, instead of just compiler temporaries.  This may severely
+limit the ability to debug an optimized program compiled with
+@option{-fno-var-tracking-assignments}.  In the negated form, this flag
+prevents SSA coalescing of user variables.  This option is enabled by
+default if optimization is enabled, and it does very little otherwise.
+
+@item -ftree-loop-if-convert
+@opindex ftree-loop-if-convert
+Attempt to transform conditional jumps in the innermost loops to
+branch-less equivalents.  The intent is to remove control-flow from
+the innermost loops in order to improve the ability of the
+vectorization pass to handle these loops.  This is enabled by default
+if vectorization is enabled.
+
+@item -ftree-loop-distribution
+@opindex ftree-loop-distribution
+Perform loop distribution.  This flag can improve cache performance on
+big loop bodies and allow further loop optimizations, like
+parallelization or vectorization, to take place.  For example, the loop
+@smallexample
+DO I = 1, N
+  A(I) = B(I) + C
+  D(I) = E(I) * F
+ENDDO
+@end smallexample
+is transformed to
+@smallexample
+DO I = 1, N
+   A(I) = B(I) + C
+ENDDO
+DO I = 1, N
+   D(I) = E(I) * F
+ENDDO
+@end smallexample
+This flag is enabled by default at @option{-O3}.
+It is also enabled by @option{-fprofile-use} and @option{-fauto-profile}.
+
+@item -ftree-loop-distribute-patterns
+@opindex ftree-loop-distribute-patterns
+Perform loop distribution of patterns that can be code generated with
+calls to a library.  This flag is enabled by default at @option{-O2} and
+higher, and by @option{-fprofile-use} and @option{-fauto-profile}.
+
+This pass distributes the initialization loops and generates a call to
+memset zero.  For example, the loop
+@smallexample
+DO I = 1, N
+  A(I) = 0
+  B(I) = A(I) + I
+ENDDO
+@end smallexample
+is transformed to
+@smallexample
+DO I = 1, N
+   A(I) = 0
+ENDDO
+DO I = 1, N
+   B(I) = A(I) + I
+ENDDO
+@end smallexample
+and the initialization loop is transformed into a call to memset zero.
+This flag is enabled by default at @option{-O3}.
+It is also enabled by @option{-fprofile-use} and @option{-fauto-profile}.
+
+@item -floop-interchange
+@opindex floop-interchange
+Perform loop interchange outside of graphite.  This flag can improve cache
+performance on loop nest and allow further loop optimizations, like
+vectorization, to take place.  For example, the loop
+@smallexample
+for (int i = 0; i < N; i++)
+  for (int j = 0; j < N; j++)
+    for (int k = 0; k < N; k++)
+      c[i][j] = c[i][j] + a[i][k]*b[k][j];
+@end smallexample
+is transformed to
+@smallexample
+for (int i = 0; i < N; i++)
+  for (int k = 0; k < N; k++)
+    for (int j = 0; j < N; j++)
+      c[i][j] = c[i][j] + a[i][k]*b[k][j];
+@end smallexample
+This flag is enabled by default at @option{-O3}.
+It is also enabled by @option{-fprofile-use} and @option{-fauto-profile}.
+
+@item -floop-unroll-and-jam
+@opindex floop-unroll-and-jam
+Apply unroll and jam transformations on feasible loops.  In a loop
+nest this unrolls the outer loop by some factor and fuses the resulting
+multiple inner loops.  This flag is enabled by default at @option{-O3}.
+It is also enabled by @option{-fprofile-use} and @option{-fauto-profile}.
+
+@item -ftree-loop-im
+@opindex ftree-loop-im
+Perform loop invariant motion on trees.  This pass moves only invariants that
+are hard to handle at RTL level (function calls, operations that expand to
+nontrivial sequences of insns).  With @option{-funswitch-loops} it also moves
+operands of conditions that are invariant out of the loop, so that we can use
+just trivial invariantness analysis in loop unswitching.  The pass also includes
+store motion.
+
+@item -ftree-loop-ivcanon
+@opindex ftree-loop-ivcanon
+Create a canonical counter for number of iterations in loops for which
+determining number of iterations requires complicated analysis.  Later
+optimizations then may determine the number easily.  Useful especially
+in connection with unrolling.
+
+@item -ftree-scev-cprop
+@opindex ftree-scev-cprop
+Perform final value replacement.  If a variable is modified in a loop
+in such a way that its value when exiting the loop can be determined using
+only its initial value and the number of loop iterations, replace uses of
+the final value by such a computation, provided it is sufficiently cheap.
+This reduces data dependencies and may allow further simplifications.
+Enabled by default at @option{-O1} and higher.
+
+@item -fivopts
+@opindex fivopts
+Perform induction variable optimizations (strength reduction, induction
+variable merging and induction variable elimination) on trees.
+
+@item -ftree-parallelize-loops=n
+@opindex ftree-parallelize-loops
+Parallelize loops, i.e., split their iteration space to run in n threads.
+This is only possible for loops whose iterations are independent
+and can be arbitrarily reordered.  The optimization is only
+profitable on multiprocessor machines, for loops that are CPU-intensive,
+rather than constrained e.g.@: by memory bandwidth.  This option
+implies @option{-pthread}, and thus is only supported on targets
+that have support for @option{-pthread}.
+
+@item -ftree-pta
+@opindex ftree-pta
+Perform function-local points-to analysis on trees.  This flag is
+enabled by default at @option{-O1} and higher, except for @option{-Og}.
+
+@item -ftree-sra
+@opindex ftree-sra
+Perform scalar replacement of aggregates.  This pass replaces structure
+references with scalars to prevent committing structures to memory too
+early.  This flag is enabled by default at @option{-O1} and higher,
+except for @option{-Og}.
+
+@item -fstore-merging
+@opindex fstore-merging
+Perform merging of narrow stores to consecutive memory addresses.  This pass
+merges contiguous stores of immediate values narrower than a word into fewer
+wider stores to reduce the number of instructions.  This is enabled by default
+at @option{-O2} and higher as well as @option{-Os}.
+
+@item -ftree-ter
+@opindex ftree-ter
+Perform temporary expression replacement during the SSA->normal phase.  Single
+use/single def temporaries are replaced at their use location with their
+defining expression.  This results in non-GIMPLE code, but gives the expanders
+much more complex trees to work on resulting in better RTL generation.  This is
+enabled by default at @option{-O1} and higher.
+
+@item -ftree-slsr
+@opindex ftree-slsr
+Perform straight-line strength reduction on trees.  This recognizes related
+expressions involving multiplications and replaces them by less expensive
+calculations when possible.  This is enabled by default at @option{-O1} and
+higher.
+
+@item -ftree-vectorize
+@opindex ftree-vectorize
+Perform vectorization on trees. This flag enables @option{-ftree-loop-vectorize}
+and @option{-ftree-slp-vectorize} if not explicitly specified.
+
+@item -ftree-loop-vectorize
+@opindex ftree-loop-vectorize
+Perform loop vectorization on trees. This flag is enabled by default at
+@option{-O2} and by @option{-ftree-vectorize}, @option{-fprofile-use},
+and @option{-fauto-profile}.
+
+@item -ftree-slp-vectorize
+@opindex ftree-slp-vectorize
+Perform basic block vectorization on trees. This flag is enabled by default at
+@option{-O2} and by @option{-ftree-vectorize}, @option{-fprofile-use},
+and @option{-fauto-profile}.
+
+@item -ftrivial-auto-var-init=@var{choice}
+@opindex ftrivial-auto-var-init
+Initialize automatic variables with either a pattern or with zeroes to increase
+the security and predictability of a program by preventing uninitialized memory
+disclosure and use.
+GCC still considers an automatic variable that doesn't have an explicit
+initializer as uninitialized, @option{-Wuninitialized} and
+@option{-Wanalyzer-use-of-uninitialized-value} will still report
+warning messages on such automatic variables.
+With this option, GCC will also initialize any padding of automatic variables
+that have structure or union types to zeroes.
+However, the current implementation cannot initialize automatic variables that
+are declared between the controlling expression and the first case of a
+@code{switch} statement.  Using @option{-Wtrivial-auto-var-init} to report all
+such cases.
+
+The three values of @var{choice} are:
+
+@itemize @bullet
+@item
+@samp{uninitialized} doesn't initialize any automatic variables.
+This is C and C++'s default.
+
+@item
+@samp{pattern} Initialize automatic variables with values which will likely
+transform logic bugs into crashes down the line, are easily recognized in a
+crash dump and without being values that programmers can rely on for useful
+program semantics.
+The current value is byte-repeatable pattern with byte "0xFE".
+The values used for pattern initialization might be changed in the future.
+
+@item
+@samp{zero} Initialize automatic variables with zeroes.
+@end itemize
+
+The default is @samp{uninitialized}.
+
+You can control this behavior for a specific variable by using the variable
+attribute @code{uninitialized} (@pxref{Variable Attributes}).
+
+@item -fvect-cost-model=@var{model}
+@opindex fvect-cost-model
+Alter the cost model used for vectorization.  The @var{model} argument
+should be one of @samp{unlimited}, @samp{dynamic}, @samp{cheap} or
+@samp{very-cheap}.
+With the @samp{unlimited} model the vectorized code-path is assumed
+to be profitable while with the @samp{dynamic} model a runtime check
+guards the vectorized code-path to enable it only for iteration
+counts that will likely execute faster than when executing the original
+scalar loop.  The @samp{cheap} model disables vectorization of
+loops where doing so would be cost prohibitive for example due to
+required runtime checks for data dependence or alignment but otherwise
+is equal to the @samp{dynamic} model.  The @samp{very-cheap} model only
+allows vectorization if the vector code would entirely replace the
+scalar code that is being vectorized.  For example, if each iteration
+of a vectorized loop would only be able to handle exactly four iterations
+of the scalar loop, the @samp{very-cheap} model would only allow
+vectorization if the scalar iteration count is known to be a multiple
+of four.
+
+The default cost model depends on other optimization flags and is
+either @samp{dynamic} or @samp{cheap}.
+
+@item -fsimd-cost-model=@var{model}
+@opindex fsimd-cost-model
+Alter the cost model used for vectorization of loops marked with the OpenMP
+simd directive.  The @var{model} argument should be one of
+@samp{unlimited}, @samp{dynamic}, @samp{cheap}.  All values of @var{model}
+have the same meaning as described in @option{-fvect-cost-model} and by
+default a cost model defined with @option{-fvect-cost-model} is used.
+
+@item -ftree-vrp
+@opindex ftree-vrp
+Perform Value Range Propagation on trees.  This is similar to the
+constant propagation pass, but instead of values, ranges of values are
+propagated.  This allows the optimizers to remove unnecessary range
+checks like array bound checks and null pointer checks.  This is
+enabled by default at @option{-O2} and higher.  Null pointer check
+elimination is only done if @option{-fdelete-null-pointer-checks} is
+enabled.
+
+@item -fsplit-paths
+@opindex fsplit-paths
+Split paths leading to loop backedges.  This can improve dead code
+elimination and common subexpression elimination.  This is enabled by
+default at @option{-O3} and above.
+
+@item -fsplit-ivs-in-unroller
+@opindex fsplit-ivs-in-unroller
+Enables expression of values of induction variables in later iterations
+of the unrolled loop using the value in the first iteration.  This breaks
+long dependency chains, thus improving efficiency of the scheduling passes.
+
+A combination of @option{-fweb} and CSE is often sufficient to obtain the
+same effect.  However, that is not reliable in cases where the loop body
+is more complicated than a single basic block.  It also does not work at all
+on some architectures due to restrictions in the CSE pass.
+
+This optimization is enabled by default.
+
+@item -fvariable-expansion-in-unroller
+@opindex fvariable-expansion-in-unroller
+With this option, the compiler creates multiple copies of some
+local variables when unrolling a loop, which can result in superior code.
+
+This optimization is enabled by default for PowerPC targets, but disabled
+by default otherwise.
+
+@item -fpartial-inlining
+@opindex fpartial-inlining
+Inline parts of functions.  This option has any effect only
+when inlining itself is turned on by the @option{-finline-functions}
+or @option{-finline-small-functions} options.
+
+Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
+
+@item -fpredictive-commoning
+@opindex fpredictive-commoning
+Perform predictive commoning optimization, i.e., reusing computations
+(especially memory loads and stores) performed in previous
+iterations of loops.
+
+This option is enabled at level @option{-O3}.
+It is also enabled by @option{-fprofile-use} and @option{-fauto-profile}.
+
+@item -fprefetch-loop-arrays
+@opindex fprefetch-loop-arrays
+If supported by the target machine, generate instructions to prefetch
+memory to improve the performance of loops that access large arrays.
+
+This option may generate better or worse code; results are highly
+dependent on the structure of loops within the source code.
+
+Disabled at level @option{-Os}.
+
+@item -fno-printf-return-value
+@opindex fno-printf-return-value
+@opindex fprintf-return-value
+Do not substitute constants for known return value of formatted output
+functions such as @code{sprintf}, @code{snprintf}, @code{vsprintf}, and
+@code{vsnprintf} (but not @code{printf} of @code{fprintf}).  This
+transformation allows GCC to optimize or even eliminate branches based
+on the known return value of these functions called with arguments that
+are either constant, or whose values are known to be in a range that
+makes determining the exact return value possible.  For example, when
+@option{-fprintf-return-value} is in effect, both the branch and the
+body of the @code{if} statement (but not the call to @code{snprint})
+can be optimized away when @code{i} is a 32-bit or smaller integer
+because the return value is guaranteed to be at most 8.
+
+@smallexample
+char buf[9];
+if (snprintf (buf, "%08x", i) >= sizeof buf)
+  @dots{}
+@end smallexample
+
+The @option{-fprintf-return-value} option relies on other optimizations
+and yields best results with @option{-O2} and above.  It works in tandem
+with the @option{-Wformat-overflow} and @option{-Wformat-truncation}
+options.  The @option{-fprintf-return-value} option is enabled by default.
+
+@item -fno-peephole
+@itemx -fno-peephole2
+@opindex fno-peephole
+@opindex fpeephole
+@opindex fno-peephole2
+@opindex fpeephole2
+Disable any machine-specific peephole optimizations.  The difference
+between @option{-fno-peephole} and @option{-fno-peephole2} is in how they
+are implemented in the compiler; some targets use one, some use the
+other, a few use both.
+
+@option{-fpeephole} is enabled by default.
+@option{-fpeephole2} enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
+
+@item -fno-guess-branch-probability
+@opindex fno-guess-branch-probability
+@opindex fguess-branch-probability
+Do not guess branch probabilities using heuristics.
+
+GCC uses heuristics to guess branch probabilities if they are
+not provided by profiling feedback (@option{-fprofile-arcs}).  These
+heuristics are based on the control flow graph.  If some branch probabilities
+are specified by @code{__builtin_expect}, then the heuristics are
+used to guess branch probabilities for the rest of the control flow graph,
+taking the @code{__builtin_expect} info into account.  The interactions
+between the heuristics and @code{__builtin_expect} can be complex, and in
+some cases, it may be useful to disable the heuristics so that the effects
+of @code{__builtin_expect} are easier to understand.
+
+It is also possible to specify expected probability of the expression
+with @code{__builtin_expect_with_probability} built-in function.
+
+The default is @option{-fguess-branch-probability} at levels
+@option{-O}, @option{-O2}, @option{-O3}, @option{-Os}.
+
+@item -freorder-blocks
+@opindex freorder-blocks
+Reorder basic blocks in the compiled function in order to reduce number of
+taken branches and improve code locality.
+
+Enabled at levels @option{-O1}, @option{-O2}, @option{-O3}, @option{-Os}.
+
+@item -freorder-blocks-algorithm=@var{algorithm}
+@opindex freorder-blocks-algorithm
+Use the specified algorithm for basic block reordering.  The
+@var{algorithm} argument can be @samp{simple}, which does not increase
+code size (except sometimes due to secondary effects like alignment),
+or @samp{stc}, the ``software trace cache'' algorithm, which tries to
+put all often executed code together, minimizing the number of branches
+executed by making extra copies of code.
+
+The default is @samp{simple} at levels @option{-O1}, @option{-Os}, and
+@samp{stc} at levels @option{-O2}, @option{-O3}.
+
+@item -freorder-blocks-and-partition
+@opindex freorder-blocks-and-partition
+In addition to reordering basic blocks in the compiled function, in order
+to reduce number of taken branches, partitions hot and cold basic blocks
+into separate sections of the assembly and @file{.o} files, to improve
+paging and cache locality performance.
+
+This optimization is automatically turned off in the presence of
+exception handling or unwind tables (on targets using setjump/longjump or target specific scheme), for linkonce sections, for functions with a user-defined
+section attribute and on any architecture that does not support named
+sections.  When @option{-fsplit-stack} is used this option is not
+enabled by default (to avoid linker errors), but may be enabled
+explicitly (if using a working linker).
+
+Enabled for x86 at levels @option{-O2}, @option{-O3}, @option{-Os}.
+
+@item -freorder-functions
+@opindex freorder-functions
+Reorder functions in the object file in order to
+improve code locality.  This is implemented by using special
+subsections @code{.text.hot} for most frequently executed functions and
+@code{.text.unlikely} for unlikely executed functions.  Reordering is done by
+the linker so object file format must support named sections and linker must
+place them in a reasonable way.
+
+This option isn't effective unless you either provide profile feedback
+(see @option{-fprofile-arcs} for details) or manually annotate functions with 
+@code{hot} or @code{cold} attributes (@pxref{Common Function Attributes}).
+
+Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
+
+@item -fstrict-aliasing
+@opindex fstrict-aliasing
+Allow the compiler to assume the strictest aliasing rules applicable to
+the language being compiled.  For C (and C++), this activates
+optimizations based on the type of expressions.  In particular, an
+object of one type is assumed never to reside at the same address as an
+object of a different type, unless the types are almost the same.  For
+example, an @code{unsigned int} can alias an @code{int}, but not a
+@code{void*} or a @code{double}.  A character type may alias any other
+type.
+
+@anchor{Type-punning}Pay special attention to code like this:
+@smallexample
+union a_union @{
+  int i;
+  double d;
+@};
+
+int f() @{
+  union a_union t;
+  t.d = 3.0;
+  return t.i;
+@}
+@end smallexample
+The practice of reading from a different union member than the one most
+recently written to (called ``type-punning'') is common.  Even with
+@option{-fstrict-aliasing}, type-punning is allowed, provided the memory
+is accessed through the union type.  So, the code above works as
+expected.  @xref{Structures unions enumerations and bit-fields
+implementation}.  However, this code might not:
+@smallexample
+int f() @{
+  union a_union t;
+  int* ip;
+  t.d = 3.0;
+  ip = &t.i;
+  return *ip;
+@}
+@end smallexample
+
+Similarly, access by taking the address, casting the resulting pointer
+and dereferencing the result has undefined behavior, even if the cast
+uses a union type, e.g.:
+@smallexample
+int f() @{
+  double d = 3.0;
+  return ((union a_union *) &d)->i;
+@}
+@end smallexample
+
+The @option{-fstrict-aliasing} option is enabled at levels
+@option{-O2}, @option{-O3}, @option{-Os}.
+
+@item -fipa-strict-aliasing
+@opindex fipa-strict-aliasing
+Controls whether rules of @option{-fstrict-aliasing} are applied across
+function boundaries.  Note that if multiple functions gets inlined into a
+single function the memory accesses are no longer considered to be crossing a
+function boundary.
+
+The @option{-fipa-strict-aliasing} option is enabled by default and is
+effective only in combination with @option{-fstrict-aliasing}.
+
+@item -falign-functions
+@itemx -falign-functions=@var{n}
+@itemx -falign-functions=@var{n}:@var{m}
+@itemx -falign-functions=@var{n}:@var{m}:@var{n2}
+@itemx -falign-functions=@var{n}:@var{m}:@var{n2}:@var{m2}
+@opindex falign-functions
+Align the start of functions to the next power-of-two greater than or
+equal to @var{n}, skipping up to @var{m}-1 bytes.  This ensures that at
+least the first @var{m} bytes of the function can be fetched by the CPU
+without crossing an @var{n}-byte alignment boundary.
+
+If @var{m} is not specified, it defaults to @var{n}.
+
+Examples: @option{-falign-functions=32} aligns functions to the next
+32-byte boundary, @option{-falign-functions=24} aligns to the next
+32-byte boundary only if this can be done by skipping 23 bytes or less,
+@option{-falign-functions=32:7} aligns to the next
+32-byte boundary only if this can be done by skipping 6 bytes or less.
+
+The second pair of @var{n2}:@var{m2} values allows you to specify
+a secondary alignment: @option{-falign-functions=64:7:32:3} aligns to
+the next 64-byte boundary if this can be done by skipping 6 bytes or less,
+otherwise aligns to the next 32-byte boundary if this can be done
+by skipping 2 bytes or less.
+If @var{m2} is not specified, it defaults to @var{n2}.
+
+Some assemblers only support this flag when @var{n} is a power of two;
+in that case, it is rounded up.
+
+@option{-fno-align-functions} and @option{-falign-functions=1} are
+equivalent and mean that functions are not aligned.
+
+If @var{n} is not specified or is zero, use a machine-dependent default.
+The maximum allowed @var{n} option value is 65536.
+
+Enabled at levels @option{-O2}, @option{-O3}.
+
+@item -flimit-function-alignment
+If this option is enabled, the compiler tries to avoid unnecessarily
+overaligning functions. It attempts to instruct the assembler to align
+by the amount specified by @option{-falign-functions}, but not to
+skip more bytes than the size of the function.
+
+@item -falign-labels
+@itemx -falign-labels=@var{n}
+@itemx -falign-labels=@var{n}:@var{m}
+@itemx -falign-labels=@var{n}:@var{m}:@var{n2}
+@itemx -falign-labels=@var{n}:@var{m}:@var{n2}:@var{m2}
+@opindex falign-labels
+Align all branch targets to a power-of-two boundary.
+
+Parameters of this option are analogous to the @option{-falign-functions} option.
+@option{-fno-align-labels} and @option{-falign-labels=1} are
+equivalent and mean that labels are not aligned.
+
+If @option{-falign-loops} or @option{-falign-jumps} are applicable and
+are greater than this value, then their values are used instead.
+
+If @var{n} is not specified or is zero, use a machine-dependent default
+which is very likely to be @samp{1}, meaning no alignment.
+The maximum allowed @var{n} option value is 65536.
+
+Enabled at levels @option{-O2}, @option{-O3}.
+
+@item -falign-loops
+@itemx -falign-loops=@var{n}
+@itemx -falign-loops=@var{n}:@var{m}
+@itemx -falign-loops=@var{n}:@var{m}:@var{n2}
+@itemx -falign-loops=@var{n}:@var{m}:@var{n2}:@var{m2}
+@opindex falign-loops
+Align loops to a power-of-two boundary.  If the loops are executed
+many times, this makes up for any execution of the dummy padding
+instructions.
+
+If @option{-falign-labels} is greater than this value, then its value
+is used instead.
+
+Parameters of this option are analogous to the @option{-falign-functions} option.
+@option{-fno-align-loops} and @option{-falign-loops=1} are
+equivalent and mean that loops are not aligned.
+The maximum allowed @var{n} option value is 65536.
+
+If @var{n} is not specified or is zero, use a machine-dependent default.
+
+Enabled at levels @option{-O2}, @option{-O3}.
+
+@item -falign-jumps
+@itemx -falign-jumps=@var{n}
+@itemx -falign-jumps=@var{n}:@var{m}
+@itemx -falign-jumps=@var{n}:@var{m}:@var{n2}
+@itemx -falign-jumps=@var{n}:@var{m}:@var{n2}:@var{m2}
+@opindex falign-jumps
+Align branch targets to a power-of-two boundary, for branch targets
+where the targets can only be reached by jumping.  In this case,
+no dummy operations need be executed.
+
+If @option{-falign-labels} is greater than this value, then its value
+is used instead.
+
+Parameters of this option are analogous to the @option{-falign-functions} option.
+@option{-fno-align-jumps} and @option{-falign-jumps=1} are
+equivalent and mean that loops are not aligned.
+
+If @var{n} is not specified or is zero, use a machine-dependent default.
+The maximum allowed @var{n} option value is 65536.
+
+Enabled at levels @option{-O2}, @option{-O3}.
+
+@item -fno-allocation-dce
+@opindex fno-allocation-dce
+Do not remove unused C++ allocations in dead code elimination.
+
+@item -fallow-store-data-races
+@opindex fallow-store-data-races
+Allow the compiler to perform optimizations that may introduce new data races
+on stores, without proving that the variable cannot be concurrently accessed
+by other threads.  Does not affect optimization of local data.  It is safe to
+use this option if it is known that global data will not be accessed by
+multiple threads.
+
+Examples of optimizations enabled by @option{-fallow-store-data-races} include
+hoisting or if-conversions that may cause a value that was already in memory
+to be re-written with that same value.  Such re-writing is safe in a single
+threaded context but may be unsafe in a multi-threaded context.  Note that on
+some processors, if-conversions may be required in order to enable
+vectorization.
+
+Enabled at level @option{-Ofast}.
+
+@item -funit-at-a-time
+@opindex funit-at-a-time
+This option is left for compatibility reasons. @option{-funit-at-a-time}
+has no effect, while @option{-fno-unit-at-a-time} implies
+@option{-fno-toplevel-reorder} and @option{-fno-section-anchors}.
+
+Enabled by default.
+
+@item -fno-toplevel-reorder
+@opindex fno-toplevel-reorder
+@opindex ftoplevel-reorder
+Do not reorder top-level functions, variables, and @code{asm}
+statements.  Output them in the same order that they appear in the
+input file.  When this option is used, unreferenced static variables
+are not removed.  This option is intended to support existing code
+that relies on a particular ordering.  For new code, it is better to
+use attributes when possible.
+
+@option{-ftoplevel-reorder} is the default at @option{-O1} and higher, and
+also at @option{-O0} if @option{-fsection-anchors} is explicitly requested.
+Additionally @option{-fno-toplevel-reorder} implies
+@option{-fno-section-anchors}.
+
+@item -funreachable-traps
+@opindex funreachable-traps
+With this option, the compiler turns calls to
+@code{__builtin_unreachable} into traps, instead of using them for
+optimization.  This also affects any such calls implicitly generated
+by the compiler.
+
+This option has the same effect as @option{-fsanitize=unreachable
+-fsanitize-trap=unreachable}, but does not affect the values of those
+options.  If @option{-fsanitize=unreachable} is enabled, that option
+takes priority over this one.
+
+This option is enabled by default at @option{-O0} and @option{-Og}.
+
+@item -fweb
+@opindex fweb
+Constructs webs as commonly used for register allocation purposes and assign
+each web individual pseudo register.  This allows the register allocation pass
+to operate on pseudos directly, but also strengthens several other optimization
+passes, such as CSE, loop optimizer and trivial dead code remover.  It can,
+however, make debugging impossible, since variables no longer stay in a
+``home register''.
+
+Enabled by default with @option{-funroll-loops}.
+
+@item -fwhole-program
+@opindex fwhole-program
+Assume that the current compilation unit represents the whole program being
+compiled.  All public functions and variables with the exception of @code{main}
+and those merged by attribute @code{externally_visible} become static functions
+and in effect are optimized more aggressively by interprocedural optimizers.
+
+This option should not be used in combination with @option{-flto}.
+Instead relying on a linker plugin should provide safer and more precise
+information.
+
+@item -flto[=@var{n}]
+@opindex flto
+This option runs the standard link-time optimizer.  When invoked
+with source code, it generates GIMPLE (one of GCC's internal
+representations) and writes it to special ELF sections in the object
+file.  When the object files are linked together, all the function
+bodies are read from these ELF sections and instantiated as if they
+had been part of the same translation unit.
+
+To use the link-time optimizer, @option{-flto} and optimization
+options should be specified at compile time and during the final link.
+It is recommended that you compile all the files participating in the
+same link with the same options and also specify those options at
+link time.  
+For example:
+
+@smallexample
+gcc -c -O2 -flto foo.c
+gcc -c -O2 -flto bar.c
+gcc -o myprog -flto -O2 foo.o bar.o
+@end smallexample
+
+The first two invocations to GCC save a bytecode representation
+of GIMPLE into special ELF sections inside @file{foo.o} and
+@file{bar.o}.  The final invocation reads the GIMPLE bytecode from
+@file{foo.o} and @file{bar.o}, merges the two files into a single
+internal image, and compiles the result as usual.  Since both
+@file{foo.o} and @file{bar.o} are merged into a single image, this
+causes all the interprocedural analyses and optimizations in GCC to
+work across the two files as if they were a single one.  This means,
+for example, that the inliner is able to inline functions in
+@file{bar.o} into functions in @file{foo.o} and vice-versa.
+
+Another (simpler) way to enable link-time optimization is:
+
+@smallexample
+gcc -o myprog -flto -O2 foo.c bar.c
+@end smallexample
+
+The above generates bytecode for @file{foo.c} and @file{bar.c},
+merges them together into a single GIMPLE representation and optimizes
+them as usual to produce @file{myprog}.
+
+The important thing to keep in mind is that to enable link-time
+optimizations you need to use the GCC driver to perform the link step.
+GCC automatically performs link-time optimization if any of the
+objects involved were compiled with the @option{-flto} command-line option.  
+You can always override
+the automatic decision to do link-time optimization
+by passing @option{-fno-lto} to the link command.
+
+To make whole program optimization effective, it is necessary to make
+certain whole program assumptions.  The compiler needs to know
+what functions and variables can be accessed by libraries and runtime
+outside of the link-time optimized unit.  When supported by the linker,
+the linker plugin (see @option{-fuse-linker-plugin}) passes information
+to the compiler about used and externally visible symbols.  When
+the linker plugin is not available, @option{-fwhole-program} should be
+used to allow the compiler to make these assumptions, which leads
+to more aggressive optimization decisions.
+
+When a file is compiled with @option{-flto} without
+@option{-fuse-linker-plugin}, the generated object file is larger than
+a regular object file because it contains GIMPLE bytecodes and the usual
+final code (see @option{-ffat-lto-objects}).  This means that
+object files with LTO information can be linked as normal object
+files; if @option{-fno-lto} is passed to the linker, no
+interprocedural optimizations are applied.  Note that when
+@option{-fno-fat-lto-objects} is enabled the compile stage is faster
+but you cannot perform a regular, non-LTO link on them.
+
+When producing the final binary, GCC only
+applies link-time optimizations to those files that contain bytecode.
+Therefore, you can mix and match object files and libraries with
+GIMPLE bytecodes and final object code.  GCC automatically selects
+which files to optimize in LTO mode and which files to link without
+further processing.
+
+Generally, options specified at link time override those
+specified at compile time, although in some cases GCC attempts to infer
+link-time options from the settings used to compile the input files.
+
+If you do not specify an optimization level option @option{-O} at
+link time, then GCC uses the highest optimization level 
+used when compiling the object files.  Note that it is generally 
+ineffective to specify an optimization level option only at link time and 
+not at compile time, for two reasons.  First, compiling without 
+optimization suppresses compiler passes that gather information 
+needed for effective optimization at link time.  Second, some early
+optimization passes can be performed only at compile time and 
+not at link time.
+
+There are some code generation flags preserved by GCC when
+generating bytecodes, as they need to be used during the final link.
+Currently, the following options and their settings are taken from
+the first object file that explicitly specifies them: 
+@option{-fcommon}, @option{-fexceptions}, @option{-fnon-call-exceptions},
+@option{-fgnu-tm} and all the @option{-m} target flags.
+
+The following options @option{-fPIC}, @option{-fpic}, @option{-fpie} and
+@option{-fPIE} are combined based on the following scheme:
+
+@smallexample
+@option{-fPIC} + @option{-fpic} = @option{-fpic}
+@option{-fPIC} + @option{-fno-pic} = @option{-fno-pic}
+@option{-fpic/-fPIC} + (no option) = (no option)
+@option{-fPIC} + @option{-fPIE} = @option{-fPIE}
+@option{-fpic} + @option{-fPIE} = @option{-fpie}
+@option{-fPIC/-fpic} + @option{-fpie} = @option{-fpie}
+@end smallexample
+
+Certain ABI-changing flags are required to match in all compilation units,
+and trying to override this at link time with a conflicting value
+is ignored.  This includes options such as @option{-freg-struct-return}
+and @option{-fpcc-struct-return}. 
+
+Other options such as @option{-ffp-contract}, @option{-fno-strict-overflow},
+@option{-fwrapv}, @option{-fno-trapv} or @option{-fno-strict-aliasing}
+are passed through to the link stage and merged conservatively for
+conflicting translation units.  Specifically
+@option{-fno-strict-overflow}, @option{-fwrapv} and @option{-fno-trapv} take
+precedence; and for example @option{-ffp-contract=off} takes precedence
+over @option{-ffp-contract=fast}.  You can override them at link time.
+
+Diagnostic options such as @option{-Wstringop-overflow} are passed
+through to the link stage and their setting matches that of the
+compile-step at function granularity.  Note that this matters only
+for diagnostics emitted during optimization.  Note that code
+transforms such as inlining can lead to warnings being enabled
+or disabled for regions if code not consistent with the setting
+at compile time.
+
+When you need to pass options to the assembler via @option{-Wa} or
+@option{-Xassembler} make sure to either compile such translation
+units with @option{-fno-lto} or consistently use the same assembler
+options on all translation units.  You can alternatively also
+specify assembler options at LTO link time.
+
+To enable debug info generation you need to supply @option{-g} at
+compile time.  If any of the input files at link time were built
+with debug info generation enabled the link will enable debug info
+generation as well.  Any elaborate debug info settings
+like the dwarf level @option{-gdwarf-5} need to be explicitly repeated
+at the linker command line and mixing different settings in different
+translation units is discouraged.
+
+If LTO encounters objects with C linkage declared with incompatible
+types in separate translation units to be linked together (undefined
+behavior according to ISO C99 6.2.7), a non-fatal diagnostic may be
+issued.  The behavior is still undefined at run time.  Similar
+diagnostics may be raised for other languages.
+
+Another feature of LTO is that it is possible to apply interprocedural
+optimizations on files written in different languages:
+
+@smallexample
+gcc -c -flto foo.c
+g++ -c -flto bar.cc
+gfortran -c -flto baz.f90
+g++ -o myprog -flto -O3 foo.o bar.o baz.o -lgfortran
+@end smallexample
+
+Notice that the final link is done with @command{g++} to get the C++
+runtime libraries and @option{-lgfortran} is added to get the Fortran
+runtime libraries.  In general, when mixing languages in LTO mode, you
+should use the same link command options as when mixing languages in a
+regular (non-LTO) compilation.
+
+If object files containing GIMPLE bytecode are stored in a library archive, say
+@file{libfoo.a}, it is possible to extract and use them in an LTO link if you
+are using a linker with plugin support.  To create static libraries suitable
+for LTO, use @command{gcc-ar} and @command{gcc-ranlib} instead of @command{ar}
+and @command{ranlib}; 
+to show the symbols of object files with GIMPLE bytecode, use
+@command{gcc-nm}.  Those commands require that @command{ar}, @command{ranlib}
+and @command{nm} have been compiled with plugin support.  At link time, use the
+flag @option{-fuse-linker-plugin} to ensure that the library participates in
+the LTO optimization process:
+
+@smallexample
+gcc -o myprog -O2 -flto -fuse-linker-plugin a.o b.o -lfoo
+@end smallexample
+
+With the linker plugin enabled, the linker extracts the needed
+GIMPLE files from @file{libfoo.a} and passes them on to the running GCC
+to make them part of the aggregated GIMPLE image to be optimized.
+
+If you are not using a linker with plugin support and/or do not
+enable the linker plugin, then the objects inside @file{libfoo.a}
+are extracted and linked as usual, but they do not participate
+in the LTO optimization process.  In order to make a static library suitable
+for both LTO optimization and usual linkage, compile its object files with
+@option{-flto} @option{-ffat-lto-objects}.
+
+Link-time optimizations do not require the presence of the whole program to
+operate.  If the program does not require any symbols to be exported, it is
+possible to combine @option{-flto} and @option{-fwhole-program} to allow
+the interprocedural optimizers to use more aggressive assumptions which may
+lead to improved optimization opportunities.
+Use of @option{-fwhole-program} is not needed when linker plugin is
+active (see @option{-fuse-linker-plugin}).
+
+The current implementation of LTO makes no
+attempt to generate bytecode that is portable between different
+types of hosts.  The bytecode files are versioned and there is a
+strict version check, so bytecode files generated in one version of
+GCC do not work with an older or newer version of GCC.
+
+Link-time optimization does not work well with generation of debugging
+information on systems other than those using a combination of ELF and
+DWARF.
+
+If you specify the optional @var{n}, the optimization and code
+generation done at link time is executed in parallel using @var{n}
+parallel jobs by utilizing an installed @command{make} program.  The
+environment variable @env{MAKE} may be used to override the program
+used.
+
+You can also specify @option{-flto=jobserver} to use GNU make's
+job server mode to determine the number of parallel jobs. This
+is useful when the Makefile calling GCC is already executing in parallel.
+You must prepend a @samp{+} to the command recipe in the parent Makefile
+for this to work.  This option likely only works if @env{MAKE} is
+GNU make.  Even without the option value, GCC tries to automatically
+detect a running GNU make's job server.
+
+Use @option{-flto=auto} to use GNU make's job server, if available,
+or otherwise fall back to autodetection of the number of CPU threads
+present in your system.
+
+@item -flto-partition=@var{alg}
+@opindex flto-partition
+Specify the partitioning algorithm used by the link-time optimizer.
+The value is either @samp{1to1} to specify a partitioning mirroring
+the original source files or @samp{balanced} to specify partitioning
+into equally sized chunks (whenever possible) or @samp{max} to create
+new partition for every symbol where possible.  Specifying @samp{none}
+as an algorithm disables partitioning and streaming completely. 
+The default value is @samp{balanced}. While @samp{1to1} can be used
+as an workaround for various code ordering issues, the @samp{max}
+partitioning is intended for internal testing only.
+The value @samp{one} specifies that exactly one partition should be
+used while the value @samp{none} bypasses partitioning and executes
+the link-time optimization step directly from the WPA phase.
+
+@item -flto-compression-level=@var{n}
+@opindex flto-compression-level
+This option specifies the level of compression used for intermediate
+language written to LTO object files, and is only meaningful in
+conjunction with LTO mode (@option{-flto}).  GCC currently supports two
+LTO compression algorithms. For zstd, valid values are 0 (no compression)
+to 19 (maximum compression), while zlib supports values from 0 to 9.
+Values outside this range are clamped to either minimum or maximum
+of the supported values.  If the option is not given,
+a default balanced compression setting is used.
+
+@item -fuse-linker-plugin
+@opindex fuse-linker-plugin
+Enables the use of a linker plugin during link-time optimization.  This
+option relies on plugin support in the linker, which is available in gold
+or in GNU ld 2.21 or newer.
+
+This option enables the extraction of object files with GIMPLE bytecode out
+of library archives. This improves the quality of optimization by exposing
+more code to the link-time optimizer.  This information specifies what
+symbols can be accessed externally (by non-LTO object or during dynamic
+linking).  Resulting code quality improvements on binaries (and shared
+libraries that use hidden visibility) are similar to @option{-fwhole-program}.
+See @option{-flto} for a description of the effect of this flag and how to
+use it.
+
+This option is enabled by default when LTO support in GCC is enabled
+and GCC was configured for use with
+a linker supporting plugins (GNU ld 2.21 or newer or gold).
+
+@item -ffat-lto-objects
+@opindex ffat-lto-objects
+Fat LTO objects are object files that contain both the intermediate language
+and the object code. This makes them usable for both LTO linking and normal
+linking. This option is effective only when compiling with @option{-flto}
+and is ignored at link time.
+
+@option{-fno-fat-lto-objects} improves compilation time over plain LTO, but
+requires the complete toolchain to be aware of LTO. It requires a linker with
+linker plugin support for basic functionality.  Additionally,
+@command{nm}, @command{ar} and @command{ranlib}
+need to support linker plugins to allow a full-featured build environment
+(capable of building static libraries etc).  GCC provides the @command{gcc-ar},
+@command{gcc-nm}, @command{gcc-ranlib} wrappers to pass the right options
+to these tools. With non fat LTO makefiles need to be modified to use them.
+
+Note that modern binutils provide plugin auto-load mechanism.
+Installing the linker plugin into @file{$libdir/bfd-plugins} has the same
+effect as usage of the command wrappers (@command{gcc-ar}, @command{gcc-nm} and
+@command{gcc-ranlib}).
+
+The default is @option{-fno-fat-lto-objects} on targets with linker plugin
+support.
+
+@item -fcompare-elim
+@opindex fcompare-elim
+After register allocation and post-register allocation instruction splitting,
+identify arithmetic instructions that compute processor flags similar to a
+comparison operation based on that arithmetic.  If possible, eliminate the
+explicit comparison operation.
+
+This pass only applies to certain targets that cannot explicitly represent
+the comparison operation before register allocation is complete.
+
+Enabled at levels @option{-O1}, @option{-O2}, @option{-O3}, @option{-Os}.
+
+@item -fcprop-registers
+@opindex fcprop-registers
+After register allocation and post-register allocation instruction splitting,
+perform a copy-propagation pass to try to reduce scheduling dependencies
+and occasionally eliminate the copy.
+
+Enabled at levels @option{-O1}, @option{-O2}, @option{-O3}, @option{-Os}.
+
+@item -fprofile-correction
+@opindex fprofile-correction
+Profiles collected using an instrumented binary for multi-threaded programs may
+be inconsistent due to missed counter updates. When this option is specified,
+GCC uses heuristics to correct or smooth out such inconsistencies. By
+default, GCC emits an error message when an inconsistent profile is detected.
+
+This option is enabled by @option{-fauto-profile}.
+
+@item -fprofile-partial-training
+@opindex fprofile-partial-training
+With @code{-fprofile-use} all portions of programs not executed during train
+run are optimized agressively for size rather than speed.  In some cases it is
+not practical to train all possible hot paths in the program. (For
+example, program may contain functions specific for a given hardware and
+trianing may not cover all hardware configurations program is run on.)  With
+@code{-fprofile-partial-training} profile feedback will be ignored for all
+functions not executed during the train run leading them to be optimized as if
+they were compiled without profile feedback. This leads to better performance
+when train run is not representative but also leads to significantly bigger
+code.
+
+@item -fprofile-use
+@itemx -fprofile-use=@var{path}
+@opindex fprofile-use
+Enable profile feedback-directed optimizations, 
+and the following optimizations, many of which
+are generally profitable only with profile feedback available:
+
+@gccoptlist{-fbranch-probabilities  -fprofile-values @gol
+-funroll-loops  -fpeel-loops  -ftracer  -fvpt @gol
+-finline-functions  -fipa-cp  -fipa-cp-clone  -fipa-bit-cp @gol
+-fpredictive-commoning  -fsplit-loops  -funswitch-loops @gol
+-fgcse-after-reload  -ftree-loop-vectorize  -ftree-slp-vectorize @gol
+-fvect-cost-model=dynamic  -ftree-loop-distribute-patterns @gol
+-fprofile-reorder-functions}
+
+Before you can use this option, you must first generate profiling information.
+@xref{Instrumentation Options}, for information about the
+@option{-fprofile-generate} option.
+
+By default, GCC emits an error message if the feedback profiles do not
+match the source code.  This error can be turned into a warning by using
+@option{-Wno-error=coverage-mismatch}.  Note this may result in poorly
+optimized code.  Additionally, by default, GCC also emits a warning message if
+the feedback profiles do not exist (see @option{-Wmissing-profile}).
+
+If @var{path} is specified, GCC looks at the @var{path} to find
+the profile feedback data files. See @option{-fprofile-dir}.
+
+@item -fauto-profile
+@itemx -fauto-profile=@var{path}
+@opindex fauto-profile
+Enable sampling-based feedback-directed optimizations, 
+and the following optimizations,
+many of which are generally profitable only with profile feedback available:
+
+@gccoptlist{-fbranch-probabilities  -fprofile-values @gol
+-funroll-loops  -fpeel-loops  -ftracer  -fvpt @gol
+-finline-functions  -fipa-cp  -fipa-cp-clone  -fipa-bit-cp @gol
+-fpredictive-commoning  -fsplit-loops  -funswitch-loops @gol
+-fgcse-after-reload  -ftree-loop-vectorize  -ftree-slp-vectorize @gol
+-fvect-cost-model=dynamic  -ftree-loop-distribute-patterns @gol
+-fprofile-correction}
+
+@var{path} is the name of a file containing AutoFDO profile information.
+If omitted, it defaults to @file{fbdata.afdo} in the current directory.
+
+Producing an AutoFDO profile data file requires running your program
+with the @command{perf} utility on a supported GNU/Linux target system.
+For more information, see @uref{https://perf.wiki.kernel.org/}.
+
+E.g.
+@smallexample
+perf record -e br_inst_retired:near_taken -b -o perf.data \
+    -- your_program
+@end smallexample
+
+Then use the @command{create_gcov} tool to convert the raw profile data
+to a format that can be used by GCC.@  You must also supply the 
+unstripped binary for your program to this tool.  
+See @uref{https://github.com/google/autofdo}.
+
+E.g.
+@smallexample
+create_gcov --binary=your_program.unstripped --profile=perf.data \
+    --gcov=profile.afdo
+@end smallexample
+@end table
+
+The following options control compiler behavior regarding floating-point 
+arithmetic.  These options trade off between speed and
+correctness.  All must be specifically enabled.
+
+@table @gcctabopt
+@item -ffloat-store
+@opindex ffloat-store
+Do not store floating-point variables in registers, and inhibit other
+options that might change whether a floating-point value is taken from a
+register or memory.
+
+@cindex floating-point precision
+This option prevents undesirable excess precision on machines such as
+the 68000 where the floating registers (of the 68881) keep more
+precision than a @code{double} is supposed to have.  Similarly for the
+x86 architecture.  For most programs, the excess precision does only
+good, but a few programs rely on the precise definition of IEEE floating
+point.  Use @option{-ffloat-store} for such programs, after modifying
+them to store all pertinent intermediate computations into variables.
+
+@item -fexcess-precision=@var{style}
+@opindex fexcess-precision
+This option allows further control over excess precision on machines
+where floating-point operations occur in a format with more precision or
+range than the IEEE standard and interchange floating-point types.  By
+default, @option{-fexcess-precision=fast} is in effect; this means that
+operations may be carried out in a wider precision than the types specified
+in the source if that would result in faster code, and it is unpredictable
+when rounding to the types specified in the source code takes place.
+When compiling C or C++, if @option{-fexcess-precision=standard} is specified
+then excess precision follows the rules specified in ISO C99 or C++; in particular,
+both casts and assignments cause values to be rounded to their
+semantic types (whereas @option{-ffloat-store} only affects
+assignments).  This option is enabled by default for C or C++ if a strict
+conformance option such as @option{-std=c99} or @option{-std=c++17} is used.
+@option{-ffast-math} enables @option{-fexcess-precision=fast} by default
+regardless of whether a strict conformance option is used.
+
+@opindex mfpmath
+@option{-fexcess-precision=standard} is not implemented for languages
+other than C or C++.  On the x86, it has no effect if @option{-mfpmath=sse}
+or @option{-mfpmath=sse+387} is specified; in the former case, IEEE
+semantics apply without excess precision, and in the latter, rounding
+is unpredictable.
+
+@item -ffast-math
+@opindex ffast-math
+Sets the options @option{-fno-math-errno}, @option{-funsafe-math-optimizations},
+@option{-ffinite-math-only}, @option{-fno-rounding-math},
+@option{-fno-signaling-nans}, @option{-fcx-limited-range} and
+@option{-fexcess-precision=fast}.
+
+This option causes the preprocessor macro @code{__FAST_MATH__} to be defined.
+
+This option is not turned on by any @option{-O} option besides
+@option{-Ofast} since it can result in incorrect output for programs
+that depend on an exact implementation of IEEE or ISO rules/specifications
+for math functions. It may, however, yield faster code for programs
+that do not require the guarantees of these specifications.
+
+@item -fno-math-errno
+@opindex fno-math-errno
+@opindex fmath-errno
+Do not set @code{errno} after calling math functions that are executed
+with a single instruction, e.g., @code{sqrt}.  A program that relies on
+IEEE exceptions for math error handling may want to use this flag
+for speed while maintaining IEEE arithmetic compatibility.
+
+This option is not turned on by any @option{-O} option since
+it can result in incorrect output for programs that depend on
+an exact implementation of IEEE or ISO rules/specifications for
+math functions. It may, however, yield faster code for programs
+that do not require the guarantees of these specifications.
+
+The default is @option{-fmath-errno}.
+
+On Darwin systems, the math library never sets @code{errno}.  There is
+therefore no reason for the compiler to consider the possibility that
+it might, and @option{-fno-math-errno} is the default.
+
+@item -funsafe-math-optimizations
+@opindex funsafe-math-optimizations
+
+Allow optimizations for floating-point arithmetic that (a) assume
+that arguments and results are valid and (b) may violate IEEE or
+ANSI standards.  When used at link time, it may include libraries
+or startup files that change the default FPU control word or other
+similar optimizations.
+
+This option is not turned on by any @option{-O} option since
+it can result in incorrect output for programs that depend on
+an exact implementation of IEEE or ISO rules/specifications for
+math functions. It may, however, yield faster code for programs
+that do not require the guarantees of these specifications.
+Enables @option{-fno-signed-zeros}, @option{-fno-trapping-math},
+@option{-fassociative-math} and @option{-freciprocal-math}.
+
+The default is @option{-fno-unsafe-math-optimizations}.
+
+@item -fassociative-math
+@opindex fassociative-math
+
+Allow re-association of operands in series of floating-point operations.
+This violates the ISO C and C++ language standard by possibly changing
+computation result.  NOTE: re-ordering may change the sign of zero as
+well as ignore NaNs and inhibit or create underflow or overflow (and
+thus cannot be used on code that relies on rounding behavior like
+@code{(x + 2**52) - 2**52}.  May also reorder floating-point comparisons
+and thus may not be used when ordered comparisons are required.
+This option requires that both @option{-fno-signed-zeros} and
+@option{-fno-trapping-math} be in effect.  Moreover, it doesn't make
+much sense with @option{-frounding-math}. For Fortran the option
+is automatically enabled when both @option{-fno-signed-zeros} and
+@option{-fno-trapping-math} are in effect.
+
+The default is @option{-fno-associative-math}.
+
+@item -freciprocal-math
+@opindex freciprocal-math
+
+Allow the reciprocal of a value to be used instead of dividing by
+the value if this enables optimizations.  For example @code{x / y}
+can be replaced with @code{x * (1/y)}, which is useful if @code{(1/y)}
+is subject to common subexpression elimination.  Note that this loses
+precision and increases the number of flops operating on the value.
+
+The default is @option{-fno-reciprocal-math}.
+
+@item -ffinite-math-only
+@opindex ffinite-math-only
+Allow optimizations for floating-point arithmetic that assume
+that arguments and results are not NaNs or +-Infs.
+
+This option is not turned on by any @option{-O} option since
+it can result in incorrect output for programs that depend on
+an exact implementation of IEEE or ISO rules/specifications for
+math functions. It may, however, yield faster code for programs
+that do not require the guarantees of these specifications.
+
+The default is @option{-fno-finite-math-only}.
+
+@item -fno-signed-zeros
+@opindex fno-signed-zeros
+@opindex fsigned-zeros
+Allow optimizations for floating-point arithmetic that ignore the
+signedness of zero.  IEEE arithmetic specifies the behavior of
+distinct +0.0 and @minus{}0.0 values, which then prohibits simplification
+of expressions such as x+0.0 or 0.0*x (even with @option{-ffinite-math-only}).
+This option implies that the sign of a zero result isn't significant.
+
+The default is @option{-fsigned-zeros}.
+
+@item -fno-trapping-math
+@opindex fno-trapping-math
+@opindex ftrapping-math
+Compile code assuming that floating-point operations cannot generate
+user-visible traps.  These traps include division by zero, overflow,
+underflow, inexact result and invalid operation.  This option requires
+that @option{-fno-signaling-nans} be in effect.  Setting this option may
+allow faster code if one relies on ``non-stop'' IEEE arithmetic, for example.
+
+This option should never be turned on by any @option{-O} option since
+it can result in incorrect output for programs that depend on
+an exact implementation of IEEE or ISO rules/specifications for
+math functions.
+
+The default is @option{-ftrapping-math}.
+
+Future versions of GCC may provide finer control of this setting
+using C99's @code{FENV_ACCESS} pragma.  This command-line option
+will be used along with @option{-frounding-math} to specify the
+default state for @code{FENV_ACCESS}.
+
+@item -frounding-math
+@opindex frounding-math
+Disable transformations and optimizations that assume default floating-point
+rounding behavior.  This is round-to-zero for all floating point
+to integer conversions, and round-to-nearest for all other arithmetic
+truncations.  This option should be specified for programs that change
+the FP rounding mode dynamically, or that may be executed with a
+non-default rounding mode.  This option disables constant folding of
+floating-point expressions at compile time (which may be affected by
+rounding mode) and arithmetic transformations that are unsafe in the
+presence of sign-dependent rounding modes.
+
+The default is @option{-fno-rounding-math}.
+
+This option is experimental and does not currently guarantee to
+disable all GCC optimizations that are affected by rounding mode.
+Future versions of GCC may provide finer control of this setting
+using C99's @code{FENV_ACCESS} pragma.  This command-line option
+will be used along with @option{-ftrapping-math} to specify the
+default state for @code{FENV_ACCESS}.
+
+@item -fsignaling-nans
+@opindex fsignaling-nans
+Compile code assuming that IEEE signaling NaNs may generate user-visible
+traps during floating-point operations.  Setting this option disables
+optimizations that may change the number of exceptions visible with
+signaling NaNs.  This option implies @option{-ftrapping-math}.
+
+This option causes the preprocessor macro @code{__SUPPORT_SNAN__} to
+be defined.
+
+The default is @option{-fno-signaling-nans}.
+
+This option is experimental and does not currently guarantee to
+disable all GCC optimizations that affect signaling NaN behavior.
+
+@item -fno-fp-int-builtin-inexact
+@opindex fno-fp-int-builtin-inexact
+@opindex ffp-int-builtin-inexact
+Do not allow the built-in functions @code{ceil}, @code{floor},
+@code{round} and @code{trunc}, and their @code{float} and @code{long
+double} variants, to generate code that raises the ``inexact''
+floating-point exception for noninteger arguments.  ISO C99 and C11
+allow these functions to raise the ``inexact'' exception, but ISO/IEC
+TS 18661-1:2014, the C bindings to IEEE 754-2008, as integrated into
+ISO C2X, does not allow these functions to do so.
+
+The default is @option{-ffp-int-builtin-inexact}, allowing the
+exception to be raised, unless C2X or a later C standard is selected.
+This option does nothing unless @option{-ftrapping-math} is in effect.
+
+Even if @option{-fno-fp-int-builtin-inexact} is used, if the functions
+generate a call to a library function then the ``inexact'' exception
+may be raised if the library implementation does not follow TS 18661.
+
+@item -fsingle-precision-constant
+@opindex fsingle-precision-constant
+Treat floating-point constants as single precision instead of
+implicitly converting them to double-precision constants.
+
+@item -fcx-limited-range
+@opindex fcx-limited-range
+When enabled, this option states that a range reduction step is not
+needed when performing complex division.  Also, there is no checking
+whether the result of a complex multiplication or division is @code{NaN
++ I*NaN}, with an attempt to rescue the situation in that case.  The
+default is @option{-fno-cx-limited-range}, but is enabled by
+@option{-ffast-math}.
+
+This option controls the default setting of the ISO C99
+@code{CX_LIMITED_RANGE} pragma.  Nevertheless, the option applies to
+all languages.
+
+@item -fcx-fortran-rules
+@opindex fcx-fortran-rules
+Complex multiplication and division follow Fortran rules.  Range
+reduction is done as part of complex division, but there is no checking
+whether the result of a complex multiplication or division is @code{NaN
++ I*NaN}, with an attempt to rescue the situation in that case.
+
+The default is @option{-fno-cx-fortran-rules}.
+
+@end table
+
+The following options control optimizations that may improve
+performance, but are not enabled by any @option{-O} options.  This
+section includes experimental options that may produce broken code.
+
+@table @gcctabopt
+@item -fbranch-probabilities
+@opindex fbranch-probabilities
+After running a program compiled with @option{-fprofile-arcs}
+(@pxref{Instrumentation Options}),
+you can compile it a second time using
+@option{-fbranch-probabilities}, to improve optimizations based on
+the number of times each branch was taken.  When a program
+compiled with @option{-fprofile-arcs} exits, it saves arc execution
+counts to a file called @file{@var{sourcename}.gcda} for each source
+file.  The information in this data file is very dependent on the
+structure of the generated code, so you must use the same source code
+and the same optimization options for both compilations.
+See details about the file naming in @option{-fprofile-arcs}.
+
+With @option{-fbranch-probabilities}, GCC puts a
+@samp{REG_BR_PROB} note on each @samp{JUMP_INSN} and @samp{CALL_INSN}.
+These can be used to improve optimization.  Currently, they are only
+used in one place: in @file{reorg.cc}, instead of guessing which path a
+branch is most likely to take, the @samp{REG_BR_PROB} values are used to
+exactly determine which path is taken more often.
+
+Enabled by @option{-fprofile-use} and @option{-fauto-profile}.
+
+@item -fprofile-values
+@opindex fprofile-values
+If combined with @option{-fprofile-arcs}, it adds code so that some
+data about values of expressions in the program is gathered.
+
+With @option{-fbranch-probabilities}, it reads back the data gathered
+from profiling values of expressions for usage in optimizations.
+
+Enabled by @option{-fprofile-generate}, @option{-fprofile-use}, and
+@option{-fauto-profile}.
+
+@item -fprofile-reorder-functions
+@opindex fprofile-reorder-functions
+Function reordering based on profile instrumentation collects
+first time of execution of a function and orders these functions
+in ascending order.
+
+Enabled with @option{-fprofile-use}.
+
+@item -fvpt
+@opindex fvpt
+If combined with @option{-fprofile-arcs}, this option instructs the compiler
+to add code to gather information about values of expressions.
+
+With @option{-fbranch-probabilities}, it reads back the data gathered
+and actually performs the optimizations based on them.
+Currently the optimizations include specialization of division operations
+using the knowledge about the value of the denominator.
+
+Enabled with @option{-fprofile-use} and @option{-fauto-profile}.
+
+@item -frename-registers
+@opindex frename-registers
+Attempt to avoid false dependencies in scheduled code by making use
+of registers left over after register allocation.  This optimization
+most benefits processors with lots of registers.  Depending on the
+debug information format adopted by the target, however, it can
+make debugging impossible, since variables no longer stay in
+a ``home register''.
+
+Enabled by default with @option{-funroll-loops}.
+
+@item -fschedule-fusion
+@opindex fschedule-fusion
+Performs a target dependent pass over the instruction stream to schedule
+instructions of same type together because target machine can execute them
+more efficiently if they are adjacent to each other in the instruction flow.
+
+Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
+
+@item -ftracer
+@opindex ftracer
+Perform tail duplication to enlarge superblock size.  This transformation
+simplifies the control flow of the function allowing other optimizations to do
+a better job.
+
+Enabled by @option{-fprofile-use} and @option{-fauto-profile}.
+
+@item -funroll-loops
+@opindex funroll-loops
+Unroll loops whose number of iterations can be determined at compile time or
+upon entry to the loop.  @option{-funroll-loops} implies
+@option{-frerun-cse-after-loop}, @option{-fweb} and @option{-frename-registers}.
+It also turns on complete loop peeling (i.e.@: complete removal of loops with
+a small constant number of iterations).  This option makes code larger, and may
+or may not make it run faster.
+
+Enabled by @option{-fprofile-use} and @option{-fauto-profile}.
+
+@item -funroll-all-loops
+@opindex funroll-all-loops
+Unroll all loops, even if their number of iterations is uncertain when
+the loop is entered.  This usually makes programs run more slowly.
+@option{-funroll-all-loops} implies the same options as
+@option{-funroll-loops}.
+
+@item -fpeel-loops
+@opindex fpeel-loops
+Peels loops for which there is enough information that they do not
+roll much (from profile feedback or static analysis).  It also turns on
+complete loop peeling (i.e.@: complete removal of loops with small constant
+number of iterations).
+
+Enabled by @option{-O3}, @option{-fprofile-use}, and @option{-fauto-profile}.
+
+@item -fmove-loop-invariants
+@opindex fmove-loop-invariants
+Enables the loop invariant motion pass in the RTL loop optimizer.  Enabled
+at level @option{-O1} and higher, except for @option{-Og}.
+
+@item -fmove-loop-stores
+@opindex fmove-loop-stores
+Enables the loop store motion pass in the GIMPLE loop optimizer.  This
+moves invariant stores to after the end of the loop in exchange for
+carrying the stored value in a register across the iteration.
+Note for this option to have an effect @option{-ftree-loop-im} has to
+be enabled as well.  Enabled at level @option{-O1} and higher, except
+for @option{-Og}.
+
+@item -fsplit-loops
+@opindex fsplit-loops
+Split a loop into two if it contains a condition that's always true
+for one side of the iteration space and false for the other.
+
+Enabled by @option{-fprofile-use} and @option{-fauto-profile}.
+
+@item -funswitch-loops
+@opindex funswitch-loops
+Move branches with loop invariant conditions out of the loop, with duplicates
+of the loop on both branches (modified according to result of the condition).
+
+Enabled by @option{-fprofile-use} and @option{-fauto-profile}.
+
+@item -fversion-loops-for-strides
+@opindex fversion-loops-for-strides
+If a loop iterates over an array with a variable stride, create another
+version of the loop that assumes the stride is always one.  For example:
+
+@smallexample
+for (int i = 0; i < n; ++i)
+  x[i * stride] = @dots{};
+@end smallexample
+
+becomes:
+
+@smallexample
+if (stride == 1)
+  for (int i = 0; i < n; ++i)
+    x[i] = @dots{};
+else
+  for (int i = 0; i < n; ++i)
+    x[i * stride] = @dots{};
+@end smallexample
+
+This is particularly useful for assumed-shape arrays in Fortran where
+(for example) it allows better vectorization assuming contiguous accesses.
+This flag is enabled by default at @option{-O3}.
+It is also enabled by @option{-fprofile-use} and @option{-fauto-profile}.
+
+@item -ffunction-sections
+@itemx -fdata-sections
+@opindex ffunction-sections
+@opindex fdata-sections
+Place each function or data item into its own section in the output
+file if the target supports arbitrary sections.  The name of the
+function or the name of the data item determines the section's name
+in the output file.
+
+Use these options on systems where the linker can perform optimizations to
+improve locality of reference in the instruction space.  Most systems using the
+ELF object format have linkers with such optimizations.  On AIX, the linker
+rearranges sections (CSECTs) based on the call graph.  The performance impact
+varies.
+
+Together with a linker garbage collection (linker @option{--gc-sections}
+option) these options may lead to smaller statically-linked executables (after
+stripping).
+
+On ELF/DWARF systems these options do not degenerate the quality of the debug
+information.  There could be issues with other object files/debug info formats.
+
+Only use these options when there are significant benefits from doing so.  When
+you specify these options, the assembler and linker create larger object and
+executable files and are also slower.  These options affect code generation.
+They prevent optimizations by the compiler and assembler using relative
+locations inside a translation unit since the locations are unknown until
+link time.  An example of such an optimization is relaxing calls to short call
+instructions.
+
+@item -fstdarg-opt
+@opindex fstdarg-opt
+Optimize the prologue of variadic argument functions with respect to usage of
+those arguments.
+
+@item -fsection-anchors
+@opindex fsection-anchors
+Try to reduce the number of symbolic address calculations by using
+shared ``anchor'' symbols to address nearby objects.  This transformation
+can help to reduce the number of GOT entries and GOT accesses on some
+targets.
+
+For example, the implementation of the following function @code{foo}:
+
+@smallexample
+static int a, b, c;
+int foo (void) @{ return a + b + c; @}
+@end smallexample
+
+@noindent
+usually calculates the addresses of all three variables, but if you
+compile it with @option{-fsection-anchors}, it accesses the variables
+from a common anchor point instead.  The effect is similar to the
+following pseudocode (which isn't valid C):
+
+@smallexample
+int foo (void)
+@{
+  register int *xr = &x;
+  return xr[&a - &x] + xr[&b - &x] + xr[&c - &x];
+@}
+@end smallexample
+
+Not all targets support this option.
+
+@item -fzero-call-used-regs=@var{choice}
+@opindex fzero-call-used-regs
+Zero call-used registers at function return to increase program
+security by either mitigating Return-Oriented Programming (ROP)
+attacks or preventing information leakage through registers.
+
+The possible values of @var{choice} are the same as for the
+@code{zero_call_used_regs} attribute (@pxref{Function Attributes}).
+The default is @samp{skip}.
+
+You can control this behavior for a specific function by using the function
+attribute @code{zero_call_used_regs} (@pxref{Function Attributes}).
+
+@item --param @var{name}=@var{value}
+@opindex param
+In some places, GCC uses various constants to control the amount of
+optimization that is done.  For example, GCC does not inline functions
+that contain more than a certain number of instructions.  You can
+control some of these constants on the command line using the
+@option{--param} option.
+
+The names of specific parameters, and the meaning of the values, are
+tied to the internals of the compiler, and are subject to change
+without notice in future releases.
+
+In order to get minimal, maximal and default value of a parameter,
+one can use @option{--help=param -Q} options.
+
+In each case, the @var{value} is an integer.  The following choices
+of @var{name} are recognized for all targets:
+
+@table @gcctabopt
+@item predictable-branch-outcome
+When branch is predicted to be taken with probability lower than this threshold
+(in percent), then it is considered well predictable.
+
+@item max-rtl-if-conversion-insns
+RTL if-conversion tries to remove conditional branches around a block and
+replace them with conditionally executed instructions.  This parameter
+gives the maximum number of instructions in a block which should be
+considered for if-conversion.  The compiler will
+also use other heuristics to decide whether if-conversion is likely to be
+profitable.
+
+@item max-rtl-if-conversion-predictable-cost
+RTL if-conversion will try to remove conditional branches around a block
+and replace them with conditionally executed instructions.  These parameters
+give the maximum permissible cost for the sequence that would be generated
+by if-conversion depending on whether the branch is statically determined
+to be predictable or not.  The units for this parameter are the same as
+those for the GCC internal seq_cost metric.  The compiler will try to
+provide a reasonable default for this parameter using the BRANCH_COST
+target macro.
+
+@item max-crossjump-edges
+The maximum number of incoming edges to consider for cross-jumping.
+The algorithm used by @option{-fcrossjumping} is @math{O(N^2)} in
+the number of edges incoming to each block.  Increasing values mean
+more aggressive optimization, making the compilation time increase with
+probably small improvement in executable size.
+
+@item min-crossjump-insns
+The minimum number of instructions that must be matched at the end
+of two blocks before cross-jumping is performed on them.  This
+value is ignored in the case where all instructions in the block being
+cross-jumped from are matched.
+
+@item max-grow-copy-bb-insns
+The maximum code size expansion factor when copying basic blocks
+instead of jumping.  The expansion is relative to a jump instruction.
+
+@item max-goto-duplication-insns
+The maximum number of instructions to duplicate to a block that jumps
+to a computed goto.  To avoid @math{O(N^2)} behavior in a number of
+passes, GCC factors computed gotos early in the compilation process,
+and unfactors them as late as possible.  Only computed jumps at the
+end of a basic blocks with no more than max-goto-duplication-insns are
+unfactored.
+
+@item max-delay-slot-insn-search
+The maximum number of instructions to consider when looking for an
+instruction to fill a delay slot.  If more than this arbitrary number of
+instructions are searched, the time savings from filling the delay slot
+are minimal, so stop searching.  Increasing values mean more
+aggressive optimization, making the compilation time increase with probably
+small improvement in execution time.
+
+@item max-delay-slot-live-search
+When trying to fill delay slots, the maximum number of instructions to
+consider when searching for a block with valid live register
+information.  Increasing this arbitrarily chosen value means more
+aggressive optimization, increasing the compilation time.  This parameter
+should be removed when the delay slot code is rewritten to maintain the
+control-flow graph.
+
+@item max-gcse-memory
+The approximate maximum amount of memory in @code{kB} that can be allocated in
+order to perform the global common subexpression elimination
+optimization.  If more memory than specified is required, the
+optimization is not done.
+
+@item max-gcse-insertion-ratio
+If the ratio of expression insertions to deletions is larger than this value
+for any expression, then RTL PRE inserts or removes the expression and thus
+leaves partially redundant computations in the instruction stream.
+
+@item max-pending-list-length
+The maximum number of pending dependencies scheduling allows
+before flushing the current state and starting over.  Large functions
+with few branches or calls can create excessively large lists which
+needlessly consume memory and resources.
+
+@item max-modulo-backtrack-attempts
+The maximum number of backtrack attempts the scheduler should make
+when modulo scheduling a loop.  Larger values can exponentially increase
+compilation time.
+
+@item max-inline-functions-called-once-loop-depth
+Maximal loop depth of a call considered by inline heuristics that tries to
+inline all functions called once.
+
+@item max-inline-functions-called-once-insns
+Maximal estimated size of functions produced while inlining functions called
+once.
+
+@item max-inline-insns-single
+Several parameters control the tree inliner used in GCC@.  This number sets the
+maximum number of instructions (counted in GCC's internal representation) in a
+single function that the tree inliner considers for inlining.  This only
+affects functions declared inline and methods implemented in a class
+declaration (C++). 
+
+
+@item max-inline-insns-auto
+When you use @option{-finline-functions} (included in @option{-O3}),
+a lot of functions that would otherwise not be considered for inlining
+by the compiler are investigated.  To those functions, a different
+(more restrictive) limit compared to functions declared inline can
+be applied (@option{--param max-inline-insns-auto}).
+
+@item max-inline-insns-small
+This is bound applied to calls which are considered relevant with
+@option{-finline-small-functions}.
+
+@item max-inline-insns-size
+This is bound applied to calls which are optimized for size. Small growth
+may be desirable to anticipate optimization oppurtunities exposed by inlining.
+
+@item uninlined-function-insns
+Number of instructions accounted by inliner for function overhead such as
+function prologue and epilogue.
+
+@item uninlined-function-time
+Extra time accounted by inliner for function overhead such as time needed to
+execute function prologue and epilogue.
+
+@item inline-heuristics-hint-percent
+The scale (in percents) applied to @option{inline-insns-single},
+@option{inline-insns-single-O2}, @option{inline-insns-auto}
+when inline heuristics hints that inlining is
+very profitable (will enable later optimizations).
+
+@item uninlined-thunk-insns
+@item uninlined-thunk-time
+Same as @option{--param uninlined-function-insns} and
+@option{--param uninlined-function-time} but applied to function thunks.
+
+@item inline-min-speedup
+When estimated performance improvement of caller + callee runtime exceeds this
+threshold (in percent), the function can be inlined regardless of the limit on
+@option{--param max-inline-insns-single} and @option{--param
+max-inline-insns-auto}.
+
+@item large-function-insns
+The limit specifying really large functions.  For functions larger than this
+limit after inlining, inlining is constrained by
+@option{--param large-function-growth}.  This parameter is useful primarily
+to avoid extreme compilation time caused by non-linear algorithms used by the
+back end.
+
+@item large-function-growth
+Specifies maximal growth of large function caused by inlining in percents.
+For example, parameter value 100 limits large function growth to 2.0 times
+the original size.
+
+@item large-unit-insns
+The limit specifying large translation unit.  Growth caused by inlining of
+units larger than this limit is limited by @option{--param inline-unit-growth}.
+For small units this might be too tight.
+For example, consider a unit consisting of function A
+that is inline and B that just calls A three times.  If B is small relative to
+A, the growth of unit is 300\% and yet such inlining is very sane.  For very
+large units consisting of small inlineable functions, however, the overall unit
+growth limit is needed to avoid exponential explosion of code size.  Thus for
+smaller units, the size is increased to @option{--param large-unit-insns}
+before applying @option{--param inline-unit-growth}.
+
+@item lazy-modules
+Maximum number of concurrently open C++ module files when lazy loading.
+
+@item inline-unit-growth
+Specifies maximal overall growth of the compilation unit caused by inlining.
+For example, parameter value 20 limits unit growth to 1.2 times the original
+size. Cold functions (either marked cold via an attribute or by profile
+feedback) are not accounted into the unit size.
+
+@item ipa-cp-unit-growth
+Specifies maximal overall growth of the compilation unit caused by
+interprocedural constant propagation.  For example, parameter value 10 limits
+unit growth to 1.1 times the original size.
+
+@item ipa-cp-large-unit-insns
+The size of translation unit that IPA-CP pass considers large.
+
+@item large-stack-frame
+The limit specifying large stack frames.  While inlining the algorithm is trying
+to not grow past this limit too much.
+
+@item large-stack-frame-growth
+Specifies maximal growth of large stack frames caused by inlining in percents.
+For example, parameter value 1000 limits large stack frame growth to 11 times
+the original size.
+
+@item max-inline-insns-recursive
+@itemx max-inline-insns-recursive-auto
+Specifies the maximum number of instructions an out-of-line copy of a
+self-recursive inline
+function can grow into by performing recursive inlining.
+
+@option{--param max-inline-insns-recursive} applies to functions
+declared inline.
+For functions not declared inline, recursive inlining
+happens only when @option{-finline-functions} (included in @option{-O3}) is
+enabled; @option{--param max-inline-insns-recursive-auto} applies instead.
+
+@item max-inline-recursive-depth
+@itemx max-inline-recursive-depth-auto
+Specifies the maximum recursion depth used for recursive inlining.
+
+@option{--param max-inline-recursive-depth} applies to functions
+declared inline.  For functions not declared inline, recursive inlining
+happens only when @option{-finline-functions} (included in @option{-O3}) is
+enabled; @option{--param max-inline-recursive-depth-auto} applies instead.
+
+@item min-inline-recursive-probability
+Recursive inlining is profitable only for function having deep recursion
+in average and can hurt for function having little recursion depth by
+increasing the prologue size or complexity of function body to other
+optimizers.
+
+When profile feedback is available (see @option{-fprofile-generate}) the actual
+recursion depth can be guessed from the probability that function recurses
+via a given call expression.  This parameter limits inlining only to call
+expressions whose probability exceeds the given threshold (in percents).
+
+@item early-inlining-insns
+Specify growth that the early inliner can make.  In effect it increases
+the amount of inlining for code having a large abstraction penalty.
+
+@item max-early-inliner-iterations
+Limit of iterations of the early inliner.  This basically bounds
+the number of nested indirect calls the early inliner can resolve.
+Deeper chains are still handled by late inlining.
+
+@item comdat-sharing-probability
+Probability (in percent) that C++ inline function with comdat visibility
+are shared across multiple compilation units.
+
+@item modref-max-bases
+@item modref-max-refs
+@item modref-max-accesses
+Specifies the maximal number of base pointers, references and accesses stored
+for a single function by mod/ref analysis.
+
+@item modref-max-tests
+Specifies the maxmal number of tests alias oracle can perform to disambiguate
+memory locations using the mod/ref information.  This parameter ought to be
+bigger than @option{--param modref-max-bases} and @option{--param
+modref-max-refs}.
+
+@item modref-max-depth
+Specifies the maximum depth of DFS walk used by modref escape analysis.
+Setting to 0 disables the analysis completely.
+
+@item modref-max-escape-points
+Specifies the maximum number of escape points tracked by modref per SSA-name.
+
+@item modref-max-adjustments
+Specifies the maximum number the access range is enlarged during modref dataflow
+analysis.
+
+@item profile-func-internal-id
+A parameter to control whether to use function internal id in profile
+database lookup. If the value is 0, the compiler uses an id that
+is based on function assembler name and filename, which makes old profile
+data more tolerant to source changes such as function reordering etc.
+
+@item min-vect-loop-bound
+The minimum number of iterations under which loops are not vectorized
+when @option{-ftree-vectorize} is used.  The number of iterations after
+vectorization needs to be greater than the value specified by this option
+to allow vectorization.
+
+@item gcse-cost-distance-ratio
+Scaling factor in calculation of maximum distance an expression
+can be moved by GCSE optimizations.  This is currently supported only in the
+code hoisting pass.  The bigger the ratio, the more aggressive code hoisting
+is with simple expressions, i.e., the expressions that have cost
+less than @option{gcse-unrestricted-cost}.  Specifying 0 disables
+hoisting of simple expressions.
+
+@item gcse-unrestricted-cost
+Cost, roughly measured as the cost of a single typical machine
+instruction, at which GCSE optimizations do not constrain
+the distance an expression can travel.  This is currently
+supported only in the code hoisting pass.  The lesser the cost,
+the more aggressive code hoisting is.  Specifying 0 
+allows all expressions to travel unrestricted distances.
+
+@item max-hoist-depth
+The depth of search in the dominator tree for expressions to hoist.
+This is used to avoid quadratic behavior in hoisting algorithm.
+The value of 0 does not limit on the search, but may slow down compilation
+of huge functions.
+
+@item max-tail-merge-comparisons
+The maximum amount of similar bbs to compare a bb with.  This is used to
+avoid quadratic behavior in tree tail merging.
+
+@item max-tail-merge-iterations
+The maximum amount of iterations of the pass over the function.  This is used to
+limit compilation time in tree tail merging.
+
+@item store-merging-allow-unaligned
+Allow the store merging pass to introduce unaligned stores if it is legal to
+do so.
+
+@item max-stores-to-merge
+The maximum number of stores to attempt to merge into wider stores in the store
+merging pass.
+
+@item max-store-chains-to-track
+The maximum number of store chains to track at the same time in the attempt
+to merge them into wider stores in the store merging pass.
+
+@item max-stores-to-track
+The maximum number of stores to track at the same time in the attemt to
+to merge them into wider stores in the store merging pass.
+
+@item max-unrolled-insns
+The maximum number of instructions that a loop may have to be unrolled.
+If a loop is unrolled, this parameter also determines how many times
+the loop code is unrolled.
+
+@item max-average-unrolled-insns
+The maximum number of instructions biased by probabilities of their execution
+that a loop may have to be unrolled.  If a loop is unrolled,
+this parameter also determines how many times the loop code is unrolled.
+
+@item max-unroll-times
+The maximum number of unrollings of a single loop.
+
+@item max-peeled-insns
+The maximum number of instructions that a loop may have to be peeled.
+If a loop is peeled, this parameter also determines how many times
+the loop code is peeled.
+
+@item max-peel-times
+The maximum number of peelings of a single loop.
+
+@item max-peel-branches
+The maximum number of branches on the hot path through the peeled sequence.
+
+@item max-completely-peeled-insns
+The maximum number of insns of a completely peeled loop.
+
+@item max-completely-peel-times
+The maximum number of iterations of a loop to be suitable for complete peeling.
+
+@item max-completely-peel-loop-nest-depth
+The maximum depth of a loop nest suitable for complete peeling.
+
+@item max-unswitch-insns
+The maximum number of insns of an unswitched loop.
+
+@item lim-expensive
+The minimum cost of an expensive expression in the loop invariant motion.
+
+@item min-loop-cond-split-prob
+When FDO profile information is available, @option{min-loop-cond-split-prob}
+specifies minimum threshold for probability of semi-invariant condition
+statement to trigger loop split.
+
+@item iv-consider-all-candidates-bound
+Bound on number of candidates for induction variables, below which
+all candidates are considered for each use in induction variable
+optimizations.  If there are more candidates than this,
+only the most relevant ones are considered to avoid quadratic time complexity.
+
+@item iv-max-considered-uses
+The induction variable optimizations give up on loops that contain more
+induction variable uses.
+
+@item iv-always-prune-cand-set-bound
+If the number of candidates in the set is smaller than this value,
+always try to remove unnecessary ivs from the set
+when adding a new one.
+
+@item avg-loop-niter
+Average number of iterations of a loop.
+
+@item dse-max-object-size
+Maximum size (in bytes) of objects tracked bytewise by dead store elimination.
+Larger values may result in larger compilation times.
+
+@item dse-max-alias-queries-per-store
+Maximum number of queries into the alias oracle per store.
+Larger values result in larger compilation times and may result in more
+removed dead stores.
+
+@item scev-max-expr-size
+Bound on size of expressions used in the scalar evolutions analyzer.
+Large expressions slow the analyzer.
+
+@item scev-max-expr-complexity
+Bound on the complexity of the expressions in the scalar evolutions analyzer.
+Complex expressions slow the analyzer.
+
+@item max-tree-if-conversion-phi-args
+Maximum number of arguments in a PHI supported by TREE if conversion
+unless the loop is marked with simd pragma.
+
+@item vect-max-layout-candidates
+The maximum number of possible vector layouts (such as permutations)
+to consider when optimizing to-be-vectorized code.
+
+@item vect-max-version-for-alignment-checks
+The maximum number of run-time checks that can be performed when
+doing loop versioning for alignment in the vectorizer.
+
+@item vect-max-version-for-alias-checks
+The maximum number of run-time checks that can be performed when
+doing loop versioning for alias in the vectorizer.
+
+@item vect-max-peeling-for-alignment
+The maximum number of loop peels to enhance access alignment
+for vectorizer. Value -1 means no limit.
+
+@item max-iterations-to-track
+The maximum number of iterations of a loop the brute-force algorithm
+for analysis of the number of iterations of the loop tries to evaluate.
+
+@item hot-bb-count-fraction
+The denominator n of fraction 1/n of the maximal execution count of a
+basic block in the entire program that a basic block needs to at least
+have in order to be considered hot.  The default is 10000, which means
+that a basic block is considered hot if its execution count is greater
+than 1/10000 of the maximal execution count.  0 means that it is never
+considered hot.  Used in non-LTO mode.
+
+@item hot-bb-count-ws-permille
+The number of most executed permilles, ranging from 0 to 1000, of the
+profiled execution of the entire program to which the execution count
+of a basic block must be part of in order to be considered hot.  The
+default is 990, which means that a basic block is considered hot if
+its execution count contributes to the upper 990 permilles, or 99.0%,
+of the profiled execution of the entire program.  0 means that it is
+never considered hot.  Used in LTO mode.
+
+@item hot-bb-frequency-fraction
+The denominator n of fraction 1/n of the execution frequency of the
+entry block of a function that a basic block of this function needs
+to at least have in order to be considered hot.  The default is 1000,
+which means that a basic block is considered hot in a function if it
+is executed more frequently than 1/1000 of the frequency of the entry
+block of the function.  0 means that it is never considered hot.
+
+@item unlikely-bb-count-fraction
+The denominator n of fraction 1/n of the number of profiled runs of
+the entire program below which the execution count of a basic block
+must be in order for the basic block to be considered unlikely executed.
+The default is 20, which means that a basic block is considered unlikely
+executed if it is executed in fewer than 1/20, or 5%, of the runs of
+the program.  0 means that it is always considered unlikely executed.
+
+@item max-predicted-iterations
+The maximum number of loop iterations we predict statically.  This is useful
+in cases where a function contains a single loop with known bound and
+another loop with unknown bound.
+The known number of iterations is predicted correctly, while
+the unknown number of iterations average to roughly 10.  This means that the
+loop without bounds appears artificially cold relative to the other one.
+
+@item builtin-expect-probability
+Control the probability of the expression having the specified value. This
+parameter takes a percentage (i.e.@: 0 ... 100) as input.
+
+@item builtin-string-cmp-inline-length
+The maximum length of a constant string for a builtin string cmp call 
+eligible for inlining.
+
+@item align-threshold
+
+Select fraction of the maximal frequency of executions of a basic block in
+a function to align the basic block.
+
+@item align-loop-iterations
+
+A loop expected to iterate at least the selected number of iterations is
+aligned.
+
+@item tracer-dynamic-coverage
+@itemx tracer-dynamic-coverage-feedback
+
+This value is used to limit superblock formation once the given percentage of
+executed instructions is covered.  This limits unnecessary code size
+expansion.
+
+The @option{tracer-dynamic-coverage-feedback} parameter
+is used only when profile
+feedback is available.  The real profiles (as opposed to statically estimated
+ones) are much less balanced allowing the threshold to be larger value.
+
+@item tracer-max-code-growth
+Stop tail duplication once code growth has reached given percentage.  This is
+a rather artificial limit, as most of the duplicates are eliminated later in
+cross jumping, so it may be set to much higher values than is the desired code
+growth.
+
+@item tracer-min-branch-ratio
+
+Stop reverse growth when the reverse probability of best edge is less than this
+threshold (in percent).
+
+@item tracer-min-branch-probability
+@itemx tracer-min-branch-probability-feedback
+
+Stop forward growth if the best edge has probability lower than this
+threshold.
+
+Similarly to @option{tracer-dynamic-coverage} two parameters are
+provided.  @option{tracer-min-branch-probability-feedback} is used for
+compilation with profile feedback and @option{tracer-min-branch-probability}
+compilation without.  The value for compilation with profile feedback
+needs to be more conservative (higher) in order to make tracer
+effective.
+
+@item stack-clash-protection-guard-size
+Specify the size of the operating system provided stack guard as
+2 raised to @var{num} bytes.  Higher values may reduce the
+number of explicit probes, but a value larger than the operating system
+provided guard will leave code vulnerable to stack clash style attacks.
+
+@item stack-clash-protection-probe-interval
+Stack clash protection involves probing stack space as it is allocated.  This
+param controls the maximum distance between probes into the stack as 2 raised
+to @var{num} bytes.  Higher values may reduce the number of explicit probes, but a value
+larger than the operating system provided guard will leave code vulnerable to
+stack clash style attacks.
+
+@item max-cse-path-length
+
+The maximum number of basic blocks on path that CSE considers.
+
+@item max-cse-insns
+The maximum number of instructions CSE processes before flushing.
+
+@item ggc-min-expand
+
+GCC uses a garbage collector to manage its own memory allocation.  This
+parameter specifies the minimum percentage by which the garbage
+collector's heap should be allowed to expand between collections.
+Tuning this may improve compilation speed; it has no effect on code
+generation.
+
+The default is 30% + 70% * (RAM/1GB) with an upper bound of 100% when
+RAM >= 1GB@.  If @code{getrlimit} is available, the notion of ``RAM'' is
+the smallest of actual RAM and @code{RLIMIT_DATA} or @code{RLIMIT_AS}.  If
+GCC is not able to calculate RAM on a particular platform, the lower
+bound of 30% is used.  Setting this parameter and
+@option{ggc-min-heapsize} to zero causes a full collection to occur at
+every opportunity.  This is extremely slow, but can be useful for
+debugging.
+
+@item ggc-min-heapsize
+
+Minimum size of the garbage collector's heap before it begins bothering
+to collect garbage.  The first collection occurs after the heap expands
+by @option{ggc-min-expand}% beyond @option{ggc-min-heapsize}.  Again,
+tuning this may improve compilation speed, and has no effect on code
+generation.
+
+The default is the smaller of RAM/8, RLIMIT_RSS, or a limit that
+tries to ensure that RLIMIT_DATA or RLIMIT_AS are not exceeded, but
+with a lower bound of 4096 (four megabytes) and an upper bound of
+131072 (128 megabytes).  If GCC is not able to calculate RAM on a
+particular platform, the lower bound is used.  Setting this parameter
+very large effectively disables garbage collection.  Setting this
+parameter and @option{ggc-min-expand} to zero causes a full collection
+to occur at every opportunity.
+
+@item max-reload-search-insns
+The maximum number of instruction reload should look backward for equivalent
+register.  Increasing values mean more aggressive optimization, making the
+compilation time increase with probably slightly better performance.
+
+@item max-cselib-memory-locations
+The maximum number of memory locations cselib should take into account.
+Increasing values mean more aggressive optimization, making the compilation time
+increase with probably slightly better performance.
+
+@item max-sched-ready-insns
+The maximum number of instructions ready to be issued the scheduler should
+consider at any given time during the first scheduling pass.  Increasing
+values mean more thorough searches, making the compilation time increase
+with probably little benefit.
+
+@item max-sched-region-blocks
+The maximum number of blocks in a region to be considered for
+interblock scheduling.
+
+@item max-pipeline-region-blocks
+The maximum number of blocks in a region to be considered for
+pipelining in the selective scheduler.
+
+@item max-sched-region-insns
+The maximum number of insns in a region to be considered for
+interblock scheduling.
+
+@item max-pipeline-region-insns
+The maximum number of insns in a region to be considered for
+pipelining in the selective scheduler.
+
+@item min-spec-prob
+The minimum probability (in percents) of reaching a source block
+for interblock speculative scheduling.
+
+@item max-sched-extend-regions-iters
+The maximum number of iterations through CFG to extend regions.
+A value of 0 disables region extensions.
+
+@item max-sched-insn-conflict-delay
+The maximum conflict delay for an insn to be considered for speculative motion.
+
+@item sched-spec-prob-cutoff
+The minimal probability of speculation success (in percents), so that
+speculative insns are scheduled.
+
+@item sched-state-edge-prob-cutoff
+The minimum probability an edge must have for the scheduler to save its
+state across it.
+
+@item sched-mem-true-dep-cost
+Minimal distance (in CPU cycles) between store and load targeting same
+memory locations.
+
+@item selsched-max-lookahead
+The maximum size of the lookahead window of selective scheduling.  It is a
+depth of search for available instructions.
+
+@item selsched-max-sched-times
+The maximum number of times that an instruction is scheduled during
+selective scheduling.  This is the limit on the number of iterations
+through which the instruction may be pipelined.
+
+@item selsched-insns-to-rename
+The maximum number of best instructions in the ready list that are considered
+for renaming in the selective scheduler.
+
+@item sms-min-sc
+The minimum value of stage count that swing modulo scheduler
+generates.
+
+@item max-last-value-rtl
+The maximum size measured as number of RTLs that can be recorded in an expression
+in combiner for a pseudo register as last known value of that register.
+
+@item max-combine-insns
+The maximum number of instructions the RTL combiner tries to combine.
+
+@item integer-share-limit
+Small integer constants can use a shared data structure, reducing the
+compiler's memory usage and increasing its speed.  This sets the maximum
+value of a shared integer constant.
+
+@item ssp-buffer-size
+The minimum size of buffers (i.e.@: arrays) that receive stack smashing
+protection when @option{-fstack-protector} is used.
+
+@item min-size-for-stack-sharing
+The minimum size of variables taking part in stack slot sharing when not
+optimizing.
+
+@item max-jump-thread-duplication-stmts
+Maximum number of statements allowed in a block that needs to be
+duplicated when threading jumps.
+
+@item max-jump-thread-paths
+The maximum number of paths to consider when searching for jump threading
+opportunities.  When arriving at a block, incoming edges are only considered
+if the number of paths to be searched so far multiplied by the number of
+incoming edges does not exhaust the specified maximum number of paths to
+consider.
+
+@item max-fields-for-field-sensitive
+Maximum number of fields in a structure treated in
+a field sensitive manner during pointer analysis.
+
+@item prefetch-latency
+Estimate on average number of instructions that are executed before
+prefetch finishes.  The distance prefetched ahead is proportional
+to this constant.  Increasing this number may also lead to less
+streams being prefetched (see @option{simultaneous-prefetches}).
+
+@item simultaneous-prefetches
+Maximum number of prefetches that can run at the same time.
+
+@item l1-cache-line-size
+The size of cache line in L1 data cache, in bytes.
+
+@item l1-cache-size
+The size of L1 data cache, in kilobytes.
+
+@item l2-cache-size
+The size of L2 data cache, in kilobytes.
+
+@item prefetch-dynamic-strides
+Whether the loop array prefetch pass should issue software prefetch hints
+for strides that are non-constant.  In some cases this may be
+beneficial, though the fact the stride is non-constant may make it
+hard to predict when there is clear benefit to issuing these hints.
+
+Set to 1 if the prefetch hints should be issued for non-constant
+strides.  Set to 0 if prefetch hints should be issued only for strides that
+are known to be constant and below @option{prefetch-minimum-stride}.
+
+@item prefetch-minimum-stride
+Minimum constant stride, in bytes, to start using prefetch hints for.  If
+the stride is less than this threshold, prefetch hints will not be issued.
+
+This setting is useful for processors that have hardware prefetchers, in
+which case there may be conflicts between the hardware prefetchers and
+the software prefetchers.  If the hardware prefetchers have a maximum
+stride they can handle, it should be used here to improve the use of
+software prefetchers.
+
+A value of -1 means we don't have a threshold and therefore
+prefetch hints can be issued for any constant stride.
+
+This setting is only useful for strides that are known and constant.
+
+@item destructive-interference-size
+@item constructive-interference-size
+The values for the C++17 variables
+@code{std::hardware_destructive_interference_size} and
+@code{std::hardware_constructive_interference_size}.  The destructive
+interference size is the minimum recommended offset between two
+independent concurrently-accessed objects; the constructive
+interference size is the maximum recommended size of contiguous memory
+accessed together.  Typically both will be the size of an L1 cache
+line for the target, in bytes.  For a generic target covering a range of L1
+cache line sizes, typically the constructive interference size will be
+the small end of the range and the destructive size will be the large
+end.
+
+The destructive interference size is intended to be used for layout,
+and thus has ABI impact.  The default value is not expected to be
+stable, and on some targets varies with @option{-mtune}, so use of
+this variable in a context where ABI stability is important, such as
+the public interface of a library, is strongly discouraged; if it is
+used in that context, users can stabilize the value using this
+option.
+
+The constructive interference size is less sensitive, as it is
+typically only used in a @samp{static_assert} to make sure that a type
+fits within a cache line.
+
+See also @option{-Winterference-size}.
+
+@item loop-interchange-max-num-stmts
+The maximum number of stmts in a loop to be interchanged.
+
+@item loop-interchange-stride-ratio
+The minimum ratio between stride of two loops for interchange to be profitable.
+
+@item min-insn-to-prefetch-ratio
+The minimum ratio between the number of instructions and the
+number of prefetches to enable prefetching in a loop.
+
+@item prefetch-min-insn-to-mem-ratio
+The minimum ratio between the number of instructions and the
+number of memory references to enable prefetching in a loop.
+
+@item use-canonical-types
+Whether the compiler should use the ``canonical'' type system.
+Should always be 1, which uses a more efficient internal
+mechanism for comparing types in C++ and Objective-C++.  However, if
+bugs in the canonical type system are causing compilation failures,
+set this value to 0 to disable canonical types.
+
+@item switch-conversion-max-branch-ratio
+Switch initialization conversion refuses to create arrays that are
+bigger than @option{switch-conversion-max-branch-ratio} times the number of
+branches in the switch.
+
+@item max-partial-antic-length
+Maximum length of the partial antic set computed during the tree
+partial redundancy elimination optimization (@option{-ftree-pre}) when
+optimizing at @option{-O3} and above.  For some sorts of source code
+the enhanced partial redundancy elimination optimization can run away,
+consuming all of the memory available on the host machine.  This
+parameter sets a limit on the length of the sets that are computed,
+which prevents the runaway behavior.  Setting a value of 0 for
+this parameter allows an unlimited set length.
+
+@item rpo-vn-max-loop-depth
+Maximum loop depth that is value-numbered optimistically.
+When the limit hits the innermost
+@var{rpo-vn-max-loop-depth} loops and the outermost loop in the
+loop nest are value-numbered optimistically and the remaining ones not.
+
+@item sccvn-max-alias-queries-per-access
+Maximum number of alias-oracle queries we perform when looking for
+redundancies for loads and stores.  If this limit is hit the search
+is aborted and the load or store is not considered redundant.  The
+number of queries is algorithmically limited to the number of
+stores on all paths from the load to the function entry.
+
+@item ira-max-loops-num
+IRA uses regional register allocation by default.  If a function
+contains more loops than the number given by this parameter, only at most
+the given number of the most frequently-executed loops form regions
+for regional register allocation.
+
+@item ira-max-conflict-table-size 
+Although IRA uses a sophisticated algorithm to compress the conflict
+table, the table can still require excessive amounts of memory for
+huge functions.  If the conflict table for a function could be more
+than the size in MB given by this parameter, the register allocator
+instead uses a faster, simpler, and lower-quality
+algorithm that does not require building a pseudo-register conflict table.  
+
+@item ira-loop-reserved-regs
+IRA can be used to evaluate more accurate register pressure in loops
+for decisions to move loop invariants (see @option{-O3}).  The number
+of available registers reserved for some other purposes is given
+by this parameter.  Default of the parameter
+is the best found from numerous experiments.
+
+@item ira-consider-dup-in-all-alts
+Make IRA to consider matching constraint (duplicated operand number)
+heavily in all available alternatives for preferred register class.
+If it is set as zero, it means IRA only respects the matching
+constraint when it's in the only available alternative with an
+appropriate register class.  Otherwise, it means IRA will check all
+available alternatives for preferred register class even if it has
+found some choice with an appropriate register class and respect the
+found qualified matching constraint.
+
+@item lra-inheritance-ebb-probability-cutoff
+LRA tries to reuse values reloaded in registers in subsequent insns.
+This optimization is called inheritance.  EBB is used as a region to
+do this optimization.  The parameter defines a minimal fall-through
+edge probability in percentage used to add BB to inheritance EBB in
+LRA.  The default value was chosen
+from numerous runs of SPEC2000 on x86-64.
+
+@item loop-invariant-max-bbs-in-loop
+Loop invariant motion can be very expensive, both in compilation time and
+in amount of needed compile-time memory, with very large loops.  Loops
+with more basic blocks than this parameter won't have loop invariant
+motion optimization performed on them.
+
+@item loop-max-datarefs-for-datadeps
+Building data dependencies is expensive for very large loops.  This
+parameter limits the number of data references in loops that are
+considered for data dependence analysis.  These large loops are no
+handled by the optimizations using loop data dependencies.
+
+@item max-vartrack-size
+Sets a maximum number of hash table slots to use during variable
+tracking dataflow analysis of any function.  If this limit is exceeded
+with variable tracking at assignments enabled, analysis for that
+function is retried without it, after removing all debug insns from
+the function.  If the limit is exceeded even without debug insns, var
+tracking analysis is completely disabled for the function.  Setting
+the parameter to zero makes it unlimited.
+
+@item max-vartrack-expr-depth
+Sets a maximum number of recursion levels when attempting to map
+variable names or debug temporaries to value expressions.  This trades
+compilation time for more complete debug information.  If this is set too
+low, value expressions that are available and could be represented in
+debug information may end up not being used; setting this higher may
+enable the compiler to find more complex debug expressions, but compile
+time and memory use may grow.
+
+@item max-debug-marker-count
+Sets a threshold on the number of debug markers (e.g.@: begin stmt
+markers) to avoid complexity explosion at inlining or expanding to RTL.
+If a function has more such gimple stmts than the set limit, such stmts
+will be dropped from the inlined copy of a function, and from its RTL
+expansion.
+
+@item min-nondebug-insn-uid
+Use uids starting at this parameter for nondebug insns.  The range below
+the parameter is reserved exclusively for debug insns created by
+@option{-fvar-tracking-assignments}, but debug insns may get
+(non-overlapping) uids above it if the reserved range is exhausted.
+
+@item ipa-sra-ptr-growth-factor
+IPA-SRA replaces a pointer to an aggregate with one or more new
+parameters only when their cumulative size is less or equal to
+@option{ipa-sra-ptr-growth-factor} times the size of the original
+pointer parameter.
+
+@item ipa-sra-max-replacements
+Maximum pieces of an aggregate that IPA-SRA tracks.  As a
+consequence, it is also the maximum number of replacements of a formal
+parameter.
+
+@item sra-max-scalarization-size-Ospeed
+@itemx sra-max-scalarization-size-Osize
+The two Scalar Reduction of Aggregates passes (SRA and IPA-SRA) aim to
+replace scalar parts of aggregates with uses of independent scalar
+variables.  These parameters control the maximum size, in storage units,
+of aggregate which is considered for replacement when compiling for
+speed
+(@option{sra-max-scalarization-size-Ospeed}) or size
+(@option{sra-max-scalarization-size-Osize}) respectively.
+
+@item sra-max-propagations
+The maximum number of artificial accesses that Scalar Replacement of
+Aggregates (SRA) will track, per one local variable, in order to
+facilitate copy propagation.
+
+@item tm-max-aggregate-size
+When making copies of thread-local variables in a transaction, this
+parameter specifies the size in bytes after which variables are
+saved with the logging functions as opposed to save/restore code
+sequence pairs.  This option only applies when using
+@option{-fgnu-tm}.
+
+@item graphite-max-nb-scop-params
+To avoid exponential effects in the Graphite loop transforms, the
+number of parameters in a Static Control Part (SCoP) is bounded.
+A value of zero can be used to lift
+the bound.  A variable whose value is unknown at compilation time and
+defined outside a SCoP is a parameter of the SCoP.
+
+@item loop-block-tile-size
+Loop blocking or strip mining transforms, enabled with
+@option{-floop-block} or @option{-floop-strip-mine}, strip mine each
+loop in the loop nest by a given number of iterations.  The strip
+length can be changed using the @option{loop-block-tile-size}
+parameter.
+
+@item ipa-jump-function-lookups
+Specifies number of statements visited during jump function offset discovery.
+
+@item ipa-cp-value-list-size
+IPA-CP attempts to track all possible values and types passed to a function's
+parameter in order to propagate them and perform devirtualization.
+@option{ipa-cp-value-list-size} is the maximum number of values and types it
+stores per one formal parameter of a function.
+
+@item ipa-cp-eval-threshold
+IPA-CP calculates its own score of cloning profitability heuristics
+and performs those cloning opportunities with scores that exceed
+@option{ipa-cp-eval-threshold}.
+
+@item ipa-cp-max-recursive-depth
+Maximum depth of recursive cloning for self-recursive function.
+
+@item ipa-cp-min-recursive-probability
+Recursive cloning only when the probability of call being executed exceeds
+the parameter.
+
+@item ipa-cp-profile-count-base
+When using @option{-fprofile-use} option, IPA-CP will consider the measured
+execution count of a call graph edge at this percentage position in their
+histogram as the basis for its heuristics calculation.
+
+@item ipa-cp-recursive-freq-factor
+The number of times interprocedural copy propagation expects recursive
+functions to call themselves.
+
+@item ipa-cp-recursion-penalty
+Percentage penalty the recursive functions will receive when they
+are evaluated for cloning.
+
+@item ipa-cp-single-call-penalty
+Percentage penalty functions containing a single call to another
+function will receive when they are evaluated for cloning.
+
+@item ipa-max-agg-items
+IPA-CP is also capable to propagate a number of scalar values passed
+in an aggregate. @option{ipa-max-agg-items} controls the maximum
+number of such values per one parameter.
+
+@item ipa-cp-loop-hint-bonus
+When IPA-CP determines that a cloning candidate would make the number
+of iterations of a loop known, it adds a bonus of
+@option{ipa-cp-loop-hint-bonus} to the profitability score of
+the candidate.
+
+@item ipa-max-loop-predicates
+The maximum number of different predicates IPA will use to describe when
+loops in a function have known properties.
+
+@item ipa-max-aa-steps
+During its analysis of function bodies, IPA-CP employs alias analysis
+in order to track values pointed to by function parameters.  In order
+not spend too much time analyzing huge functions, it gives up and
+consider all memory clobbered after examining
+@option{ipa-max-aa-steps} statements modifying memory.
+
+@item ipa-max-switch-predicate-bounds
+Maximal number of boundary endpoints of case ranges of switch statement.
+For switch exceeding this limit, IPA-CP will not construct cloning cost
+predicate, which is used to estimate cloning benefit, for default case
+of the switch statement.
+
+@item ipa-max-param-expr-ops
+IPA-CP will analyze conditional statement that references some function
+parameter to estimate benefit for cloning upon certain constant value.
+But if number of operations in a parameter expression exceeds
+@option{ipa-max-param-expr-ops}, the expression is treated as complicated
+one, and is not handled by IPA analysis.
+
+@item lto-partitions
+Specify desired number of partitions produced during WHOPR compilation.
+The number of partitions should exceed the number of CPUs used for compilation.
+
+@item lto-min-partition
+Size of minimal partition for WHOPR (in estimated instructions).
+This prevents expenses of splitting very small programs into too many
+partitions.
+
+@item lto-max-partition
+Size of max partition for WHOPR (in estimated instructions).
+to provide an upper bound for individual size of partition.
+Meant to be used only with balanced partitioning.
+
+@item lto-max-streaming-parallelism
+Maximal number of parallel processes used for LTO streaming.
+
+@item cxx-max-namespaces-for-diagnostic-help
+The maximum number of namespaces to consult for suggestions when C++
+name lookup fails for an identifier.
+
+@item sink-frequency-threshold
+The maximum relative execution frequency (in percents) of the target block
+relative to a statement's original block to allow statement sinking of a
+statement.  Larger numbers result in more aggressive statement sinking.
+A small positive adjustment is applied for
+statements with memory operands as those are even more profitable so sink.
+
+@item max-stores-to-sink
+The maximum number of conditional store pairs that can be sunk.  Set to 0
+if either vectorization (@option{-ftree-vectorize}) or if-conversion
+(@option{-ftree-loop-if-convert}) is disabled.
+
+@item case-values-threshold
+The smallest number of different values for which it is best to use a
+jump-table instead of a tree of conditional branches.  If the value is
+0, use the default for the machine.
+
+@item jump-table-max-growth-ratio-for-size
+The maximum code size growth ratio when expanding
+into a jump table (in percent).  The parameter is used when
+optimizing for size.
+
+@item jump-table-max-growth-ratio-for-speed
+The maximum code size growth ratio when expanding
+into a jump table (in percent).  The parameter is used when
+optimizing for speed.
+
+@item tree-reassoc-width
+Set the maximum number of instructions executed in parallel in
+reassociated tree. This parameter overrides target dependent
+heuristics used by default if has non zero value.
+
+@item sched-pressure-algorithm
+Choose between the two available implementations of
+@option{-fsched-pressure}.  Algorithm 1 is the original implementation
+and is the more likely to prevent instructions from being reordered.
+Algorithm 2 was designed to be a compromise between the relatively
+conservative approach taken by algorithm 1 and the rather aggressive
+approach taken by the default scheduler.  It relies more heavily on
+having a regular register file and accurate register pressure classes.
+See @file{haifa-sched.cc} in the GCC sources for more details.
+
+The default choice depends on the target.
+
+@item max-slsr-cand-scan
+Set the maximum number of existing candidates that are considered when
+seeking a basis for a new straight-line strength reduction candidate.
+
+@item asan-globals
+Enable buffer overflow detection for global objects.  This kind
+of protection is enabled by default if you are using
+@option{-fsanitize=address} option.
+To disable global objects protection use @option{--param asan-globals=0}.
+
+@item asan-stack
+Enable buffer overflow detection for stack objects.  This kind of
+protection is enabled by default when using @option{-fsanitize=address}.
+To disable stack protection use @option{--param asan-stack=0} option.
+
+@item asan-instrument-reads
+Enable buffer overflow detection for memory reads.  This kind of
+protection is enabled by default when using @option{-fsanitize=address}.
+To disable memory reads protection use
+@option{--param asan-instrument-reads=0}.
+
+@item asan-instrument-writes
+Enable buffer overflow detection for memory writes.  This kind of
+protection is enabled by default when using @option{-fsanitize=address}.
+To disable memory writes protection use
+@option{--param asan-instrument-writes=0} option.
+
+@item asan-memintrin
+Enable detection for built-in functions.  This kind of protection
+is enabled by default when using @option{-fsanitize=address}.
+To disable built-in functions protection use
+@option{--param asan-memintrin=0}.
+
+@item asan-use-after-return
+Enable detection of use-after-return.  This kind of protection
+is enabled by default when using the @option{-fsanitize=address} option.
+To disable it use @option{--param asan-use-after-return=0}.
+
+Note: By default the check is disabled at run time.  To enable it,
+add @code{detect_stack_use_after_return=1} to the environment variable
+@env{ASAN_OPTIONS}.
+
+@item asan-instrumentation-with-call-threshold
+If number of memory accesses in function being instrumented
+is greater or equal to this number, use callbacks instead of inline checks.
+E.g. to disable inline code use
+@option{--param asan-instrumentation-with-call-threshold=0}.
+
+@item hwasan-instrument-stack
+Enable hwasan instrumentation of statically sized stack-allocated variables.
+This kind of instrumentation is enabled by default when using
+@option{-fsanitize=hwaddress} and disabled by default when using
+@option{-fsanitize=kernel-hwaddress}.
+To disable stack instrumentation use
+@option{--param hwasan-instrument-stack=0}, and to enable it use
+@option{--param hwasan-instrument-stack=1}.
+
+@item hwasan-random-frame-tag
+When using stack instrumentation, decide tags for stack variables using a
+deterministic sequence beginning at a random tag for each frame.  With this
+parameter unset tags are chosen using the same sequence but beginning from 1.
+This is enabled by default for @option{-fsanitize=hwaddress} and unavailable
+for @option{-fsanitize=kernel-hwaddress}.
+To disable it use @option{--param hwasan-random-frame-tag=0}.
+
+@item hwasan-instrument-allocas
+Enable hwasan instrumentation of dynamically sized stack-allocated variables.
+This kind of instrumentation is enabled by default when using
+@option{-fsanitize=hwaddress} and disabled by default when using
+@option{-fsanitize=kernel-hwaddress}.
+To disable instrumentation of such variables use
+@option{--param hwasan-instrument-allocas=0}, and to enable it use
+@option{--param hwasan-instrument-allocas=1}.
+
+@item hwasan-instrument-reads
+Enable hwasan checks on memory reads.  Instrumentation of reads is enabled by
+default for both @option{-fsanitize=hwaddress} and
+@option{-fsanitize=kernel-hwaddress}.
+To disable checking memory reads use
+@option{--param hwasan-instrument-reads=0}.
+
+@item hwasan-instrument-writes
+Enable hwasan checks on memory writes.  Instrumentation of writes is enabled by
+default for both @option{-fsanitize=hwaddress} and
+@option{-fsanitize=kernel-hwaddress}.
+To disable checking memory writes use
+@option{--param hwasan-instrument-writes=0}.
+
+@item hwasan-instrument-mem-intrinsics
+Enable hwasan instrumentation of builtin functions.  Instrumentation of these
+builtin functions is enabled by default for both @option{-fsanitize=hwaddress}
+and @option{-fsanitize=kernel-hwaddress}.
+To disable instrumentation of builtin functions use
+@option{--param hwasan-instrument-mem-intrinsics=0}.
+
+@item use-after-scope-direct-emission-threshold
+If the size of a local variable in bytes is smaller or equal to this
+number, directly poison (or unpoison) shadow memory instead of using
+run-time callbacks.
+
+@item tsan-distinguish-volatile
+Emit special instrumentation for accesses to volatiles.
+
+@item tsan-instrument-func-entry-exit
+Emit instrumentation calls to __tsan_func_entry() and __tsan_func_exit().
+
+@item max-fsm-thread-path-insns
+Maximum number of instructions to copy when duplicating blocks on a
+finite state automaton jump thread path.
+
+@item threader-debug
+threader-debug=[none|all] Enables verbose dumping of the threader solver.
+
+@item parloops-chunk-size
+Chunk size of omp schedule for loops parallelized by parloops.
+
+@item parloops-schedule
+Schedule type of omp schedule for loops parallelized by parloops (static,
+dynamic, guided, auto, runtime).
+
+@item parloops-min-per-thread
+The minimum number of iterations per thread of an innermost parallelized
+loop for which the parallelized variant is preferred over the single threaded
+one.  Note that for a parallelized loop nest the
+minimum number of iterations of the outermost loop per thread is two.
+
+@item max-ssa-name-query-depth
+Maximum depth of recursion when querying properties of SSA names in things
+like fold routines.  One level of recursion corresponds to following a
+use-def chain.
+
+@item max-speculative-devirt-maydefs
+The maximum number of may-defs we analyze when looking for a must-def
+specifying the dynamic type of an object that invokes a virtual call
+we may be able to devirtualize speculatively.
+
+@item max-vrp-switch-assertions
+The maximum number of assertions to add along the default edge of a switch
+statement during VRP.
+
+@item evrp-sparse-threshold
+Maximum number of basic blocks before EVRP uses a sparse cache.
+
+@item vrp1-mode
+Specifies the mode VRP pass 1 should operate in.
+
+@item vrp2-mode
+Specifies the mode VRP pass 2 should operate in.
+
+@item ranger-debug
+Specifies the type of debug output to be issued for ranges.
+
+@item evrp-switch-limit
+Specifies the maximum number of switch cases before EVRP ignores a switch.
+
+@item unroll-jam-min-percent
+The minimum percentage of memory references that must be optimized
+away for the unroll-and-jam transformation to be considered profitable.
+
+@item unroll-jam-max-unroll
+The maximum number of times the outer loop should be unrolled by
+the unroll-and-jam transformation.
+
+@item max-rtl-if-conversion-unpredictable-cost
+Maximum permissible cost for the sequence that would be generated
+by the RTL if-conversion pass for a branch that is considered unpredictable.
+
+@item max-variable-expansions-in-unroller
+If @option{-fvariable-expansion-in-unroller} is used, the maximum number
+of times that an individual variable will be expanded during loop unrolling.
+
+@item partial-inlining-entry-probability
+Maximum probability of the entry BB of split region
+(in percent relative to entry BB of the function)
+to make partial inlining happen.
+
+@item max-tracked-strlens
+Maximum number of strings for which strlen optimization pass will
+track string lengths.
+
+@item gcse-after-reload-partial-fraction
+The threshold ratio for performing partial redundancy
+elimination after reload.
+
+@item gcse-after-reload-critical-fraction
+The threshold ratio of critical edges execution count that
+permit performing redundancy elimination after reload.
+
+@item max-loop-header-insns
+The maximum number of insns in loop header duplicated
+by the copy loop headers pass.
+
+@item vect-epilogues-nomask
+Enable loop epilogue vectorization using smaller vector size.
+
+@item vect-partial-vector-usage
+Controls when the loop vectorizer considers using partial vector loads
+and stores as an alternative to falling back to scalar code.  0 stops
+the vectorizer from ever using partial vector loads and stores.  1 allows
+partial vector loads and stores if vectorization removes the need for the
+code to iterate.  2 allows partial vector loads and stores in all loops.
+The parameter only has an effect on targets that support partial
+vector loads and stores.
+
+@item vect-inner-loop-cost-factor
+The maximum factor which the loop vectorizer applies to the cost of statements
+in an inner loop relative to the loop being vectorized.  The factor applied
+is the maximum of the estimated number of iterations of the inner loop and
+this parameter.  The default value of this parameter is 50.
+
+@item vect-induction-float
+Enable loop vectorization of floating point inductions.
+
+@item avoid-fma-max-bits
+Maximum number of bits for which we avoid creating FMAs.
+
+@item sms-loop-average-count-threshold
+A threshold on the average loop count considered by the swing modulo scheduler.
+
+@item sms-dfa-history
+The number of cycles the swing modulo scheduler considers when checking
+conflicts using DFA.
+
+@item graphite-allow-codegen-errors
+Whether codegen errors should be ICEs when @option{-fchecking}.
+
+@item sms-max-ii-factor
+A factor for tuning the upper bound that swing modulo scheduler
+uses for scheduling a loop.
+
+@item lra-max-considered-reload-pseudos
+The max number of reload pseudos which are considered during
+spilling a non-reload pseudo.
+
+@item max-pow-sqrt-depth
+Maximum depth of sqrt chains to use when synthesizing exponentiation
+by a real constant.
+
+@item max-dse-active-local-stores
+Maximum number of active local stores in RTL dead store elimination.
+
+@item asan-instrument-allocas
+Enable asan allocas/VLAs protection.
+
+@item max-iterations-computation-cost
+Bound on the cost of an expression to compute the number of iterations.
+
+@item max-isl-operations
+Maximum number of isl operations, 0 means unlimited.
+
+@item graphite-max-arrays-per-scop
+Maximum number of arrays per scop.
+
+@item max-vartrack-reverse-op-size
+Max. size of loc list for which reverse ops should be added.
+
+@item fsm-scale-path-stmts
+Scale factor to apply to the number of statements in a threading path
+when comparing to the number of (scaled) blocks.
+
+@item uninit-control-dep-attempts
+Maximum number of nested calls to search for control dependencies
+during uninitialized variable analysis.
+
+@item fsm-scale-path-blocks
+Scale factor to apply to the number of blocks in a threading path
+when comparing to the number of (scaled) statements.
+
+@item sched-autopref-queue-depth
+Hardware autoprefetcher scheduler model control flag.
+Number of lookahead cycles the model looks into; at '
+' only enable instruction sorting heuristic.
+
+@item loop-versioning-max-inner-insns
+The maximum number of instructions that an inner loop can have
+before the loop versioning pass considers it too big to copy.
+
+@item loop-versioning-max-outer-insns
+The maximum number of instructions that an outer loop can have
+before the loop versioning pass considers it too big to copy,
+discounting any instructions in inner loops that directly benefit
+from versioning.
+
+@item ssa-name-def-chain-limit
+The maximum number of SSA_NAME assignments to follow in determining
+a property of a variable such as its value.  This limits the number
+of iterations or recursive calls GCC performs when optimizing certain
+statements or when determining their validity prior to issuing
+diagnostics.
+
+@item store-merging-max-size
+Maximum size of a single store merging region in bytes.
+
+@item hash-table-verification-limit
+The number of elements for which hash table verification is done
+for each searched element.
+
+@item max-find-base-term-values
+Maximum number of VALUEs handled during a single find_base_term call.
+
+@item analyzer-max-enodes-per-program-point
+The maximum number of exploded nodes per program point within
+the analyzer, before terminating analysis of that point.
+
+@item analyzer-max-constraints
+The maximum number of constraints per state.
+
+@item analyzer-min-snodes-for-call-summary
+The minimum number of supernodes within a function for the
+analyzer to consider summarizing its effects at call sites.
+
+@item analyzer-max-enodes-for-full-dump
+The maximum depth of exploded nodes that should appear in a dot dump
+before switching to a less verbose format.
+
+@item analyzer-max-recursion-depth
+The maximum number of times a callsite can appear in a call stack
+within the analyzer, before terminating analysis of a call that would
+recurse deeper.
+
+@item analyzer-max-svalue-depth
+The maximum depth of a symbolic value, before approximating
+the value as unknown.
+
+@item analyzer-max-infeasible-edges
+The maximum number of infeasible edges to reject before declaring
+a diagnostic as infeasible.
+
+@item gimple-fe-computed-hot-bb-threshold
+The number of executions of a basic block which is considered hot.
+The parameter is used only in GIMPLE FE.
+
+@item analyzer-bb-explosion-factor
+The maximum number of 'after supernode' exploded nodes within the analyzer
+per supernode, before terminating analysis.
+
+@item ranger-logical-depth
+Maximum depth of logical expression evaluation ranger will look through
+when evaluating outgoing edge ranges.
+
+@item relation-block-limit
+Maximum number of relations the oracle will register in a basic block.
+
+@item min-pagesize
+Minimum page size for warning purposes.
+
+@item openacc-kernels
+Specify mode of OpenACC `kernels' constructs handling.
+With @option{--param=openacc-kernels=decompose}, OpenACC `kernels'
+constructs are decomposed into parts, a sequence of compute
+constructs, each then handled individually.
+This is work in progress.
+With @option{--param=openacc-kernels=parloops}, OpenACC `kernels'
+constructs are handled by the @samp{parloops} pass, en bloc.
+This is the current default.
+
+@item openacc-privatization
+Specify mode of OpenACC privatization diagnostics for
+@option{-fopt-info-omp-note} and applicable
+@option{-fdump-tree-*-details}.
+With @option{--param=openacc-privatization=quiet}, don't diagnose.
+This is the current default.
+With @option{--param=openacc-privatization=noisy}, do diagnose.
+
+@end table
+
+The following choices of @var{name} are available on AArch64 targets:
+
+@table @gcctabopt
+@item aarch64-sve-compare-costs
+When vectorizing for SVE, consider using ``unpacked'' vectors for
+smaller elements and use the cost model to pick the cheapest approach.
+Also use the cost model to choose between SVE and Advanced SIMD vectorization.
+
+Using unpacked vectors includes storing smaller elements in larger
+containers and accessing elements with extending loads and truncating
+stores.
+
+@item aarch64-float-recp-precision
+The number of Newton iterations for calculating the reciprocal for float type.
+The precision of division is proportional to this param when division
+approximation is enabled.  The default value is 1.
+
+@item aarch64-double-recp-precision
+The number of Newton iterations for calculating the reciprocal for double type.
+The precision of division is propotional to this param when division
+approximation is enabled.  The default value is 2.
+
+@item aarch64-autovec-preference
+Force an ISA selection strategy for auto-vectorization.  Accepts values from
+0 to 4, inclusive.
+@table @samp
+@item 0
+Use the default heuristics.
+@item 1
+Use only Advanced SIMD for auto-vectorization.
+@item 2
+Use only SVE for auto-vectorization.
+@item 3
+Use both Advanced SIMD and SVE.  Prefer Advanced SIMD when the costs are
+deemed equal.
+@item 4
+Use both Advanced SIMD and SVE.  Prefer SVE when the costs are deemed equal.
+@end table
+The default value is 0.
+
+@item aarch64-loop-vect-issue-rate-niters
+The tuning for some AArch64 CPUs tries to take both latencies and issue
+rates into account when deciding whether a loop should be vectorized
+using SVE, vectorized using Advanced SIMD, or not vectorized at all.
+If this parameter is set to @var{n}, GCC will not use this heuristic
+for loops that are known to execute in fewer than @var{n} Advanced
+SIMD iterations.
+
+@item aarch64-vect-unroll-limit
+The vectorizer will use available tuning information to determine whether it
+would be beneficial to unroll the main vectorized loop and by how much.  This
+parameter set's the upper bound of how much the vectorizer will unroll the main
+loop.  The default value is four.
+
+@end table
+
+The following choices of @var{name} are available on i386 and x86_64 targets:
+
+@table @gcctabopt
+@item x86-stlf-window-ninsns
+Instructions number above which STFL stall penalty can be compensated.
+
+@end table
+
+@end table
+
+@node Instrumentation Options
+@section Program Instrumentation Options
+@cindex instrumentation options
+@cindex program instrumentation options
+@cindex run-time error checking options
+@cindex profiling options
+@cindex options, program instrumentation
+@cindex options, run-time error checking
+@cindex options, profiling
+
+GCC supports a number of command-line options that control adding
+run-time instrumentation to the code it normally generates.  
+For example, one purpose of instrumentation is collect profiling
+statistics for use in finding program hot spots, code coverage
+analysis, or profile-guided optimizations.
+Another class of program instrumentation is adding run-time checking 
+to detect programming errors like invalid pointer
+dereferences or out-of-bounds array accesses, as well as deliberately
+hostile attacks such as stack smashing or C++ vtable hijacking.
+There is also a general hook which can be used to implement other
+forms of tracing or function-level instrumentation for debug or
+program analysis purposes.
+
+@table @gcctabopt
+@cindex @command{prof}
+@cindex @command{gprof}
+@item -p
+@itemx -pg
+@opindex p
+@opindex pg
+Generate extra code to write profile information suitable for the
+analysis program @command{prof} (for @option{-p}) or @command{gprof}
+(for @option{-pg}).  You must use this option when compiling
+the source files you want data about, and you must also use it when
+linking.
+
+You can use the function attribute @code{no_instrument_function} to
+suppress profiling of individual functions when compiling with these options.
+@xref{Common Function Attributes}.
+
+@item -fprofile-arcs
+@opindex fprofile-arcs
+Add code so that program flow @dfn{arcs} are instrumented.  During
+execution the program records how many times each branch and call is
+executed and how many times it is taken or returns.  On targets that support
+constructors with priority support, profiling properly handles constructors,
+destructors and C++ constructors (and destructors) of classes which are used
+as a type of a global variable.
+
+When the compiled
+program exits it saves this data to a file called
+@file{@var{auxname}.gcda} for each source file.  The data may be used for
+profile-directed optimizations (@option{-fbranch-probabilities}), or for
+test coverage analysis (@option{-ftest-coverage}).  Each object file's
+@var{auxname} is generated from the name of the output file, if
+explicitly specified and it is not the final executable, otherwise it is
+the basename of the source file.  In both cases any suffix is removed
+(e.g.@: @file{foo.gcda} for input file @file{dir/foo.c}, or
+@file{dir/foo.gcda} for output file specified as @option{-o dir/foo.o}).
+
+Note that if a command line directly links source files, the corresponding
+@var{.gcda} files will be prefixed with the unsuffixed name of the output file.
+E.g. @code{gcc a.c b.c -o binary} would generate @file{binary-a.gcda} and
+@file{binary-b.gcda} files.
+
+@xref{Cross-profiling}.
+
+@cindex @command{gcov}
+@item --coverage
+@opindex coverage
+
+This option is used to compile and link code instrumented for coverage
+analysis.  The option is a synonym for @option{-fprofile-arcs}
+@option{-ftest-coverage} (when compiling) and @option{-lgcov} (when
+linking).  See the documentation for those options for more details.
+
+@itemize
+
+@item
+Compile the source files with @option{-fprofile-arcs} plus optimization
+and code generation options.  For test coverage analysis, use the
+additional @option{-ftest-coverage} option.  You do not need to profile
+every source file in a program.
+
+@item
+Compile the source files additionally with @option{-fprofile-abs-path}
+to create absolute path names in the @file{.gcno} files.  This allows
+@command{gcov} to find the correct sources in projects where compilations
+occur with different working directories.
+
+@item
+Link your object files with @option{-lgcov} or @option{-fprofile-arcs}
+(the latter implies the former).
+
+@item
+Run the program on a representative workload to generate the arc profile
+information.  This may be repeated any number of times.  You can run
+concurrent instances of your program, and provided that the file system
+supports locking, the data files will be correctly updated.  Unless
+a strict ISO C dialect option is in effect, @code{fork} calls are
+detected and correctly handled without double counting.
+
+Moreover, an object file can be recompiled multiple times
+and the corresponding @file{.gcda} file merges as long as
+the source file and the compiler options are unchanged.
+
+@item
+For profile-directed optimizations, compile the source files again with
+the same optimization and code generation options plus
+@option{-fbranch-probabilities} (@pxref{Optimize Options,,Options that
+Control Optimization}).
+
+@item
+For test coverage analysis, use @command{gcov} to produce human readable
+information from the @file{.gcno} and @file{.gcda} files.  Refer to the
+@command{gcov} documentation for further information.
+
+@end itemize
+
+With @option{-fprofile-arcs}, for each function of your program GCC
+creates a program flow graph, then finds a spanning tree for the graph.
+Only arcs that are not on the spanning tree have to be instrumented: the
+compiler adds code to count the number of times that these arcs are
+executed.  When an arc is the only exit or only entrance to a block, the
+instrumentation code can be added to the block; otherwise, a new basic
+block must be created to hold the instrumentation code.
+
+@need 2000
+@item -ftest-coverage
+@opindex ftest-coverage
+Produce a notes file that the @command{gcov} code-coverage utility
+(@pxref{Gcov,, @command{gcov}---a Test Coverage Program}) can use to
+show program coverage.  Each source file's note file is called
+@file{@var{auxname}.gcno}.  Refer to the @option{-fprofile-arcs} option
+above for a description of @var{auxname} and instructions on how to
+generate test coverage data.  Coverage data matches the source files
+more closely if you do not optimize.
+
+@item -fprofile-abs-path
+@opindex fprofile-abs-path
+Automatically convert relative source file names to absolute path names
+in the @file{.gcno} files.  This allows @command{gcov} to find the correct
+sources in projects where compilations occur with different working
+directories.
+
+@item -fprofile-dir=@var{path}
+@opindex fprofile-dir
+
+Set the directory to search for the profile data files in to @var{path}.
+This option affects only the profile data generated by
+@option{-fprofile-generate}, @option{-ftest-coverage}, @option{-fprofile-arcs}
+and used by @option{-fprofile-use} and @option{-fbranch-probabilities}
+and its related options.  Both absolute and relative paths can be used.
+By default, GCC uses the current directory as @var{path}, thus the
+profile data file appears in the same directory as the object file.
+In order to prevent the file name clashing, if the object file name is
+not an absolute path, we mangle the absolute path of the
+@file{@var{sourcename}.gcda} file and use it as the file name of a
+@file{.gcda} file.  See details about the file naming in @option{-fprofile-arcs}.
+See similar option @option{-fprofile-note}.
+
+When an executable is run in a massive parallel environment, it is recommended
+to save profile to different folders.  That can be done with variables
+in @var{path} that are exported during run-time:
+
+@table @gcctabopt
+
+@item %p
+process ID.
+
+@item %q@{VAR@}
+value of environment variable @var{VAR}
+
+@end table
+
+@item -fprofile-generate
+@itemx -fprofile-generate=@var{path}
+@opindex fprofile-generate
+
+Enable options usually used for instrumenting application to produce
+profile useful for later recompilation with profile feedback based
+optimization.  You must use @option{-fprofile-generate} both when
+compiling and when linking your program.
+
+The following options are enabled:
+@option{-fprofile-arcs}, @option{-fprofile-values},
+@option{-finline-functions}, and @option{-fipa-bit-cp}.
+
+If @var{path} is specified, GCC looks at the @var{path} to find
+the profile feedback data files. See @option{-fprofile-dir}.
+
+To optimize the program based on the collected profile information, use
+@option{-fprofile-use}.  @xref{Optimize Options}, for more information.
+
+@item -fprofile-info-section
+@itemx -fprofile-info-section=@var{name}
+@opindex fprofile-info-section
+
+Register the profile information in the specified section instead of using a
+constructor/destructor.  The section name is @var{name} if it is specified,
+otherwise the section name defaults to @code{.gcov_info}.  A pointer to the
+profile information generated by @option{-fprofile-arcs} is placed in the
+specified section for each translation unit.  This option disables the profile
+information registration through a constructor and it disables the profile
+information processing through a destructor.  This option is not intended to be
+used in hosted environments such as GNU/Linux.  It targets freestanding
+environments (for example embedded systems) with limited resources which do not
+support constructors/destructors or the C library file I/O.
+
+The linker could collect the input sections in a continuous memory block and
+define start and end symbols.  A GNU linker script example which defines a
+linker output section follows:
+
+@smallexample
+  .gcov_info      :
+  @{
+    PROVIDE (__gcov_info_start = .);
+    KEEP (*(.gcov_info))
+    PROVIDE (__gcov_info_end = .);
+  @}
+@end smallexample
+
+The program could dump the profiling information registered in this linker set
+for example like this:
+
+@smallexample
+#include <gcov.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+extern const struct gcov_info *const __gcov_info_start[];
+extern const struct gcov_info *const __gcov_info_end[];
+
+static void
+dump (const void *d, unsigned n, void *arg)
+@{
+  const unsigned char *c = d;
+
+  for (unsigned i = 0; i < n; ++i)
+    printf ("%02x", c[i]);
+@}
+
+static void
+filename (const char *f, void *arg)
+@{
+  __gcov_filename_to_gcfn (f, dump, arg );
+@}
+
+static void *
+allocate (unsigned length, void *arg)
+@{
+  return malloc (length);
+@}
+
+static void
+dump_gcov_info (void)
+@{
+  const struct gcov_info *const *info = __gcov_info_start;
+  const struct gcov_info *const *end = __gcov_info_end;
+
+  /* Obfuscate variable to prevent compiler optimizations.  */
+  __asm__ ("" : "+r" (info));
+
+  while (info != end)
+  @{
+    void *arg = NULL;
+    __gcov_info_to_gcda (*info, filename, dump, allocate, arg);
+    putchar ('\n');
+    ++info;
+  @}
+@}
+
+int
+main (void)
+@{
+  dump_gcov_info ();
+  return 0;
+@}
+@end smallexample
+
+The @command{merge-stream} subcommand of @command{gcov-tool} may be used to
+deserialize the data stream generated by the @code{__gcov_filename_to_gcfn} and
+@code{__gcov_info_to_gcda} functions and merge the profile information into
+@file{.gcda} files on the host filesystem.
+
+@item -fprofile-note=@var{path}
+@opindex fprofile-note
+
+If @var{path} is specified, GCC saves @file{.gcno} file into @var{path}
+location.  If you combine the option with multiple source files,
+the @file{.gcno} file will be overwritten.
+
+@item -fprofile-prefix-path=@var{path}
+@opindex fprofile-prefix-path
+
+This option can be used in combination with
+@option{profile-generate=}@var{profile_dir} and
+@option{profile-use=}@var{profile_dir} to inform GCC where is the base
+directory of built source tree.  By default @var{profile_dir} will contain
+files with mangled absolute paths of all object files in the built project.
+This is not desirable when directory used to build the instrumented binary
+differs from the directory used to build the binary optimized with profile
+feedback because the profile data will not be found during the optimized build.
+In such setups @option{-fprofile-prefix-path=}@var{path} with @var{path}
+pointing to the base directory of the build can be used to strip the irrelevant
+part of the path and keep all file names relative to the main build directory.
+
+@item -fprofile-prefix-map=@var{old}=@var{new}
+@opindex fprofile-prefix-map
+When compiling files residing in directory @file{@var{old}}, record
+profiling information (with @option{--coverage})
+describing them as if the files resided in
+directory @file{@var{new}} instead.
+See also @option{-ffile-prefix-map}.
+
+@item -fprofile-update=@var{method}
+@opindex fprofile-update
+
+Alter the update method for an application instrumented for profile
+feedback based optimization.  The @var{method} argument should be one of
+@samp{single}, @samp{atomic} or @samp{prefer-atomic}.
+The first one is useful for single-threaded applications,
+while the second one prevents profile corruption by emitting thread-safe code.
+
+@strong{Warning:} When an application does not properly join all threads
+(or creates an detached thread), a profile file can be still corrupted.
+
+Using @samp{prefer-atomic} would be transformed either to @samp{atomic},
+when supported by a target, or to @samp{single} otherwise.  The GCC driver
+automatically selects @samp{prefer-atomic} when @option{-pthread}
+is present in the command line.
+
+@item -fprofile-filter-files=@var{regex}
+@opindex fprofile-filter-files
+
+Instrument only functions from files whose name matches
+any of the regular expressions (separated by semi-colons).
+
+For example, @option{-fprofile-filter-files=main\.c;module.*\.c} will instrument
+only @file{main.c} and all C files starting with 'module'.
+
+@item -fprofile-exclude-files=@var{regex}
+@opindex fprofile-exclude-files
+
+Instrument only functions from files whose name does not match
+any of the regular expressions (separated by semi-colons).
+
+For example, @option{-fprofile-exclude-files=/usr/.*} will prevent instrumentation
+of all files that are located in the @file{/usr/} folder.
+
+@item -fprofile-reproducible=@r{[}multithreaded@r{|}parallel-runs@r{|}serial@r{]}
+@opindex fprofile-reproducible
+Control level of reproducibility of profile gathered by
+@code{-fprofile-generate}.  This makes it possible to rebuild program
+with same outcome which is useful, for example, for distribution
+packages.
+
+With @option{-fprofile-reproducible=serial} the profile gathered by
+@option{-fprofile-generate} is reproducible provided the trained program
+behaves the same at each invocation of the train run, it is not
+multi-threaded and profile data streaming is always done in the same
+order.  Note that profile streaming happens at the end of program run but
+also before @code{fork} function is invoked.
+
+Note that it is quite common that execution counts of some part of
+programs depends, for example, on length of temporary file names or
+memory space randomization (that may affect hash-table collision rate).
+Such non-reproducible part of programs may be annotated by
+@code{no_instrument_function} function attribute. @command{gcov-dump} with
+@option{-l} can be used to dump gathered data and verify that they are
+indeed reproducible.
+
+With @option{-fprofile-reproducible=parallel-runs} collected profile
+stays reproducible regardless the order of streaming of the data into
+gcda files.  This setting makes it possible to run multiple instances of
+instrumented program in parallel (such as with @code{make -j}). This
+reduces quality of gathered data, in particular of indirect call
+profiling.
+
+@item -fsanitize=address
+@opindex fsanitize=address
+Enable AddressSanitizer, a fast memory error detector.
+Memory access instructions are instrumented to detect
+out-of-bounds and use-after-free bugs.
+The option enables @option{-fsanitize-address-use-after-scope}.
+See @uref{https://github.com/google/sanitizers/wiki/AddressSanitizer} for
+more details.  The run-time behavior can be influenced using the
+@env{ASAN_OPTIONS} environment variable.  When set to @code{help=1},
+the available options are shown at startup of the instrumented program.  See
+@url{https://github.com/google/sanitizers/wiki/AddressSanitizerFlags#run-time-flags}
+for a list of supported options.
+The option cannot be combined with @option{-fsanitize=thread} or
+@option{-fsanitize=hwaddress}.  Note that the only target
+@option{-fsanitize=hwaddress} is currently supported on is AArch64.
+
+@item -fsanitize=kernel-address
+@opindex fsanitize=kernel-address
+Enable AddressSanitizer for Linux kernel.
+See @uref{https://github.com/google/kasan} for more details.
+
+@item -fsanitize=hwaddress
+@opindex fsanitize=hwaddress
+Enable Hardware-assisted AddressSanitizer, which uses a hardware ability to
+ignore the top byte of a pointer to allow the detection of memory errors with
+a low memory overhead.
+Memory access instructions are instrumented to detect out-of-bounds and
+use-after-free bugs.
+The option enables @option{-fsanitize-address-use-after-scope}.
+See
+@uref{https://clang.llvm.org/docs/HardwareAssistedAddressSanitizerDesign.html}
+for more details.  The run-time behavior can be influenced using the
+@env{HWASAN_OPTIONS} environment variable.  When set to @code{help=1},
+the available options are shown at startup of the instrumented program.
+The option cannot be combined with @option{-fsanitize=thread} or
+@option{-fsanitize=address}, and is currently only available on AArch64.
+
+@item -fsanitize=kernel-hwaddress
+@opindex fsanitize=kernel-hwaddress
+Enable Hardware-assisted AddressSanitizer for compilation of the Linux kernel.
+Similar to @option{-fsanitize=kernel-address} but using an alternate
+instrumentation method, and similar to @option{-fsanitize=hwaddress} but with
+instrumentation differences necessary for compiling the Linux kernel.
+These differences are to avoid hwasan library initialization calls and to
+account for the stack pointer having a different value in its top byte.
+
+@emph{Note:} This option has different defaults to the @option{-fsanitize=hwaddress}.
+Instrumenting the stack and alloca calls are not on by default but are still
+possible by specifying the command-line options
+@option{--param hwasan-instrument-stack=1} and
+@option{--param hwasan-instrument-allocas=1} respectively. Using a random frame
+tag is not implemented for kernel instrumentation.
+
+@item -fsanitize=pointer-compare
+@opindex fsanitize=pointer-compare
+Instrument comparison operation (<, <=, >, >=) with pointer operands.
+The option must be combined with either @option{-fsanitize=kernel-address} or
+@option{-fsanitize=address}
+The option cannot be combined with @option{-fsanitize=thread}.
+Note: By default the check is disabled at run time.  To enable it,
+add @code{detect_invalid_pointer_pairs=2} to the environment variable
+@env{ASAN_OPTIONS}. Using @code{detect_invalid_pointer_pairs=1} detects
+invalid operation only when both pointers are non-null.
+
+@item -fsanitize=pointer-subtract
+@opindex fsanitize=pointer-subtract
+Instrument subtraction with pointer operands.
+The option must be combined with either @option{-fsanitize=kernel-address} or
+@option{-fsanitize=address}
+The option cannot be combined with @option{-fsanitize=thread}.
+Note: By default the check is disabled at run time.  To enable it,
+add @code{detect_invalid_pointer_pairs=2} to the environment variable
+@env{ASAN_OPTIONS}. Using @code{detect_invalid_pointer_pairs=1} detects
+invalid operation only when both pointers are non-null.
+
+@item -fsanitize=shadow-call-stack
+@opindex fsanitize=shadow-call-stack
+Enable ShadowCallStack, a security enhancement mechanism used to protect
+programs against return address overwrites (e.g. stack buffer overflows.)
+It works by saving a function's return address to a separately allocated
+shadow call stack in the function prologue and restoring the return address
+from the shadow call stack in the function epilogue.  Instrumentation only
+occurs in functions that need to save the return address to the stack.
+
+Currently it only supports the aarch64 platform.  It is specifically
+designed for linux kernels that enable the CONFIG_SHADOW_CALL_STACK option.
+For the user space programs, runtime support is not currently provided
+in libc and libgcc.  Users who want to use this feature in user space need
+to provide their own support for the runtime.  It should be noted that
+this may cause the ABI rules to be broken.
+
+On aarch64, the instrumentation makes use of the platform register @code{x18}.
+This generally means that any code that may run on the same thread as code
+compiled with ShadowCallStack must be compiled with the flag
+@option{-ffixed-x18}, otherwise functions compiled without
+@option{-ffixed-x18} might clobber @code{x18} and so corrupt the shadow
+stack pointer.
+
+Also, because there is no userspace runtime support, code compiled with
+ShadowCallStack cannot use exception handling.  Use @option{-fno-exceptions}
+to turn off exceptions.
+
+See @uref{https://clang.llvm.org/docs/ShadowCallStack.html} for more
+details.
+
+@item -fsanitize=thread
+@opindex fsanitize=thread
+Enable ThreadSanitizer, a fast data race detector.
+Memory access instructions are instrumented to detect
+data race bugs.  See @uref{https://github.com/google/sanitizers/wiki#threadsanitizer} for more
+details. The run-time behavior can be influenced using the @env{TSAN_OPTIONS}
+environment variable; see
+@url{https://github.com/google/sanitizers/wiki/ThreadSanitizerFlags} for a list of
+supported options.
+The option cannot be combined with @option{-fsanitize=address},
+@option{-fsanitize=leak}.
+
+Note that sanitized atomic builtins cannot throw exceptions when
+operating on invalid memory addresses with non-call exceptions
+(@option{-fnon-call-exceptions}).
+
+@item -fsanitize=leak
+@opindex fsanitize=leak
+Enable LeakSanitizer, a memory leak detector.
+This option only matters for linking of executables and
+the executable is linked against a library that overrides @code{malloc}
+and other allocator functions.  See
+@uref{https://github.com/google/sanitizers/wiki/AddressSanitizerLeakSanitizer} for more
+details.  The run-time behavior can be influenced using the
+@env{LSAN_OPTIONS} environment variable.
+The option cannot be combined with @option{-fsanitize=thread}.
+
+@item -fsanitize=undefined
+@opindex fsanitize=undefined
+Enable UndefinedBehaviorSanitizer, a fast undefined behavior detector.
+Various computations are instrumented to detect undefined behavior
+at runtime.  See @uref{https://clang.llvm.org/docs/UndefinedBehaviorSanitizer.html} for more details.   The run-time behavior can be influenced using the
+@env{UBSAN_OPTIONS} environment variable.  Current suboptions are:
+
+@table @gcctabopt
+
+@item -fsanitize=shift
+@opindex fsanitize=shift
+This option enables checking that the result of a shift operation is
+not undefined.  Note that what exactly is considered undefined differs
+slightly between C and C++, as well as between ISO C90 and C99, etc.
+This option has two suboptions, @option{-fsanitize=shift-base} and
+@option{-fsanitize=shift-exponent}.
+
+@item -fsanitize=shift-exponent
+@opindex fsanitize=shift-exponent
+This option enables checking that the second argument of a shift operation
+is not negative and is smaller than the precision of the promoted first
+argument.
+
+@item -fsanitize=shift-base
+@opindex fsanitize=shift-base
+If the second argument of a shift operation is within range, check that the
+result of a shift operation is not undefined.  Note that what exactly is
+considered undefined differs slightly between C and C++, as well as between
+ISO C90 and C99, etc.
+
+@item -fsanitize=integer-divide-by-zero
+@opindex fsanitize=integer-divide-by-zero
+Detect integer division by zero.
+
+@item -fsanitize=unreachable
+@opindex fsanitize=unreachable
+With this option, the compiler turns the @code{__builtin_unreachable}
+call into a diagnostics message call instead.  When reaching the
+@code{__builtin_unreachable} call, the behavior is undefined.
+
+@item -fsanitize=vla-bound
+@opindex fsanitize=vla-bound
+This option instructs the compiler to check that the size of a variable
+length array is positive.
+
+@item -fsanitize=null
+@opindex fsanitize=null
+This option enables pointer checking.  Particularly, the application
+built with this option turned on will issue an error message when it
+tries to dereference a NULL pointer, or if a reference (possibly an
+rvalue reference) is bound to a NULL pointer, or if a method is invoked
+on an object pointed by a NULL pointer.
+
+@item -fsanitize=return
+@opindex fsanitize=return
+This option enables return statement checking.  Programs
+built with this option turned on will issue an error message
+when the end of a non-void function is reached without actually
+returning a value.  This option works in C++ only.
+
+@item -fsanitize=signed-integer-overflow
+@opindex fsanitize=signed-integer-overflow
+This option enables signed integer overflow checking.  We check that
+the result of @code{+}, @code{*}, and both unary and binary @code{-}
+does not overflow in the signed arithmetics.  This also detects
+@code{INT_MIN / -1} signed division.  Note, integer promotion
+rules must be taken into account.  That is, the following is not an
+overflow:
+@smallexample
+signed char a = SCHAR_MAX;
+a++;
+@end smallexample
+
+@item -fsanitize=bounds
+@opindex fsanitize=bounds
+This option enables instrumentation of array bounds.  Various out of bounds
+accesses are detected.  Flexible array members, flexible array member-like
+arrays, and initializers of variables with static storage are not instrumented.
+
+@item -fsanitize=bounds-strict
+@opindex fsanitize=bounds-strict
+This option enables strict instrumentation of array bounds.  Most out of bounds
+accesses are detected, including flexible array members and flexible array
+member-like arrays.  Initializers of variables with static storage are not
+instrumented.
+
+@item -fsanitize=alignment
+@opindex fsanitize=alignment
+
+This option enables checking of alignment of pointers when they are
+dereferenced, or when a reference is bound to insufficiently aligned target,
+or when a method or constructor is invoked on insufficiently aligned object.
+
+@item -fsanitize=object-size
+@opindex fsanitize=object-size
+This option enables instrumentation of memory references using the
+@code{__builtin_object_size} function.  Various out of bounds pointer
+accesses are detected.
+
+@item -fsanitize=float-divide-by-zero
+@opindex fsanitize=float-divide-by-zero
+Detect floating-point division by zero.  Unlike other similar options,
+@option{-fsanitize=float-divide-by-zero} is not enabled by
+@option{-fsanitize=undefined}, since floating-point division by zero can
+be a legitimate way of obtaining infinities and NaNs.
+
+@item -fsanitize=float-cast-overflow
+@opindex fsanitize=float-cast-overflow
+This option enables floating-point type to integer conversion checking.
+We check that the result of the conversion does not overflow.
+Unlike other similar options, @option{-fsanitize=float-cast-overflow} is
+not enabled by @option{-fsanitize=undefined}.
+This option does not work well with @code{FE_INVALID} exceptions enabled.
+
+@item -fsanitize=nonnull-attribute
+@opindex fsanitize=nonnull-attribute
+
+This option enables instrumentation of calls, checking whether null values
+are not passed to arguments marked as requiring a non-null value by the
+@code{nonnull} function attribute.
+
+@item -fsanitize=returns-nonnull-attribute
+@opindex fsanitize=returns-nonnull-attribute
+
+This option enables instrumentation of return statements in functions
+marked with @code{returns_nonnull} function attribute, to detect returning
+of null values from such functions.
+
+@item -fsanitize=bool
+@opindex fsanitize=bool
+
+This option enables instrumentation of loads from bool.  If a value other
+than 0/1 is loaded, a run-time error is issued.
+
+@item -fsanitize=enum
+@opindex fsanitize=enum
+
+This option enables instrumentation of loads from an enum type.  If
+a value outside the range of values for the enum type is loaded,
+a run-time error is issued.
+
+@item -fsanitize=vptr
+@opindex fsanitize=vptr
+
+This option enables instrumentation of C++ member function calls, member
+accesses and some conversions between pointers to base and derived classes,
+to verify the referenced object has the correct dynamic type.
+
+@item -fsanitize=pointer-overflow
+@opindex fsanitize=pointer-overflow
+
+This option enables instrumentation of pointer arithmetics.  If the pointer
+arithmetics overflows, a run-time error is issued.
+
+@item -fsanitize=builtin
+@opindex fsanitize=builtin
+
+This option enables instrumentation of arguments to selected builtin
+functions.  If an invalid value is passed to such arguments, a run-time
+error is issued.  E.g.@ passing 0 as the argument to @code{__builtin_ctz}
+or @code{__builtin_clz} invokes undefined behavior and is diagnosed
+by this option.
+
+@end table
+
+Note that sanitizers tend to increase the rate of false positive
+warnings, most notably those around @option{-Wmaybe-uninitialized}.
+We recommend against combining @option{-Werror} and [the use of]
+sanitizers.
+
+While @option{-ftrapv} causes traps for signed overflows to be emitted,
+@option{-fsanitize=undefined} gives a diagnostic message.
+This currently works only for the C family of languages.
+
+@item -fno-sanitize=all
+@opindex fno-sanitize=all
+
+This option disables all previously enabled sanitizers.
+@option{-fsanitize=all} is not allowed, as some sanitizers cannot be used
+together.
+
+@item -fasan-shadow-offset=@var{number}
+@opindex fasan-shadow-offset
+This option forces GCC to use custom shadow offset in AddressSanitizer checks.
+It is useful for experimenting with different shadow memory layouts in
+Kernel AddressSanitizer.
+
+@item -fsanitize-sections=@var{s1},@var{s2},...
+@opindex fsanitize-sections
+Sanitize global variables in selected user-defined sections.  @var{si} may
+contain wildcards.
+
+@item -fsanitize-recover@r{[}=@var{opts}@r{]}
+@opindex fsanitize-recover
+@opindex fno-sanitize-recover
+@option{-fsanitize-recover=} controls error recovery mode for sanitizers
+mentioned in comma-separated list of @var{opts}.  Enabling this option
+for a sanitizer component causes it to attempt to continue
+running the program as if no error happened.  This means multiple
+runtime errors can be reported in a single program run, and the exit
+code of the program may indicate success even when errors
+have been reported.  The @option{-fno-sanitize-recover=} option
+can be used to alter
+this behavior: only the first detected error is reported
+and program then exits with a non-zero exit code.
+
+Currently this feature only works for @option{-fsanitize=undefined} (and its suboptions
+except for @option{-fsanitize=unreachable} and @option{-fsanitize=return}),
+@option{-fsanitize=float-cast-overflow}, @option{-fsanitize=float-divide-by-zero},
+@option{-fsanitize=bounds-strict},
+@option{-fsanitize=kernel-address} and @option{-fsanitize=address}.
+For these sanitizers error recovery is turned on by default,
+except @option{-fsanitize=address}, for which this feature is experimental.
+@option{-fsanitize-recover=all} and @option{-fno-sanitize-recover=all} is also
+accepted, the former enables recovery for all sanitizers that support it,
+the latter disables recovery for all sanitizers that support it.
+
+Even if a recovery mode is turned on the compiler side, it needs to be also
+enabled on the runtime library side, otherwise the failures are still fatal.
+The runtime library defaults to @code{halt_on_error=0} for
+ThreadSanitizer and UndefinedBehaviorSanitizer, while default value for
+AddressSanitizer is @code{halt_on_error=1}. This can be overridden through
+setting the @code{halt_on_error} flag in the corresponding environment variable.
+
+Syntax without an explicit @var{opts} parameter is deprecated.  It is
+equivalent to specifying an @var{opts} list of:
+
+@smallexample
+undefined,float-cast-overflow,float-divide-by-zero,bounds-strict
+@end smallexample
+
+@item -fsanitize-address-use-after-scope
+@opindex fsanitize-address-use-after-scope
+Enable sanitization of local variables to detect use-after-scope bugs.
+The option sets @option{-fstack-reuse} to @samp{none}.
+
+@item -fsanitize-trap@r{[}=@var{opts}@r{]}
+@opindex fsanitize-trap
+@opindex fno-sanitize-trap
+The @option{-fsanitize-trap=} option instructs the compiler to
+report for sanitizers mentioned in comma-separated list of @var{opts}
+undefined behavior using @code{__builtin_trap} rather than a @code{libubsan}
+library routine.  If this option is enabled for certain sanitizer,
+it takes precedence over the @option{-fsanitizer-recover=} for that
+sanitizer, @code{__builtin_trap} will be emitted and be fatal regardless
+of whether recovery is enabled or disabled using @option{-fsanitize-recover=}.
+
+The advantage of this is that the @code{libubsan} library is not needed
+and is not linked in, so this is usable even in freestanding environments.
+
+Currently this feature works with @option{-fsanitize=undefined} (and its suboptions
+except for @option{-fsanitize=vptr}), @option{-fsanitize=float-cast-overflow},
+@option{-fsanitize=float-divide-by-zero} and
+@option{-fsanitize=bounds-strict}.  @code{-fsanitize-trap=all} can be also
+specified, which enables it for @code{undefined} suboptions,
+@option{-fsanitize=float-cast-overflow},
+@option{-fsanitize=float-divide-by-zero} and
+@option{-fsanitize=bounds-strict}.
+If @code{-fsanitize-trap=undefined} or @code{-fsanitize-trap=all} is used
+and @code{-fsanitize=vptr} is enabled on the command line, the
+instrumentation is silently ignored as the instrumentation always needs
+@code{libubsan} support, @option{-fsanitize-trap=vptr} is not allowed.
+
+@item -fsanitize-undefined-trap-on-error
+@opindex fsanitize-undefined-trap-on-error
+The @option{-fsanitize-undefined-trap-on-error} option is deprecated
+equivalent of @option{-fsanitize-trap=all}.
+
+@item -fsanitize-coverage=trace-pc
+@opindex fsanitize-coverage=trace-pc
+Enable coverage-guided fuzzing code instrumentation.
+Inserts a call to @code{__sanitizer_cov_trace_pc} into every basic block.
+
+@item -fsanitize-coverage=trace-cmp
+@opindex fsanitize-coverage=trace-cmp
+Enable dataflow guided fuzzing code instrumentation.
+Inserts a call to @code{__sanitizer_cov_trace_cmp1},
+@code{__sanitizer_cov_trace_cmp2}, @code{__sanitizer_cov_trace_cmp4} or
+@code{__sanitizer_cov_trace_cmp8} for integral comparison with both operands
+variable or @code{__sanitizer_cov_trace_const_cmp1},
+@code{__sanitizer_cov_trace_const_cmp2},
+@code{__sanitizer_cov_trace_const_cmp4} or
+@code{__sanitizer_cov_trace_const_cmp8} for integral comparison with one
+operand constant, @code{__sanitizer_cov_trace_cmpf} or
+@code{__sanitizer_cov_trace_cmpd} for float or double comparisons and
+@code{__sanitizer_cov_trace_switch} for switch statements.
+
+@item -fcf-protection=@r{[}full@r{|}branch@r{|}return@r{|}none@r{|}check@r{]}
+@opindex fcf-protection
+Enable code instrumentation of control-flow transfers to increase
+program security by checking that target addresses of control-flow
+transfer instructions (such as indirect function call, function return,
+indirect jump) are valid.  This prevents diverting the flow of control
+to an unexpected target.  This is intended to protect against such
+threats as Return-oriented Programming (ROP), and similarly
+call/jmp-oriented programming (COP/JOP).
+
+The value @code{branch} tells the compiler to implement checking of
+validity of control-flow transfer at the point of indirect branch
+instructions, i.e.@: call/jmp instructions.  The value @code{return}
+implements checking of validity at the point of returning from a
+function.  The value @code{full} is an alias for specifying both
+@code{branch} and @code{return}. The value @code{none} turns off
+instrumentation.
+
+The value @code{check} is used for the final link with link-time
+optimization (LTO).  An error is issued if LTO object files are
+compiled with different @option{-fcf-protection} values.  The
+value @code{check} is ignored at the compile time.
+
+The macro @code{__CET__} is defined when @option{-fcf-protection} is
+used.  The first bit of @code{__CET__} is set to 1 for the value
+@code{branch} and the second bit of @code{__CET__} is set to 1 for
+the @code{return}.
+
+You can also use the @code{nocf_check} attribute to identify
+which functions and calls should be skipped from instrumentation
+(@pxref{Function Attributes}).
+
+Currently the x86 GNU/Linux target provides an implementation based
+on Intel Control-flow Enforcement Technology (CET) which works for
+i686 processor or newer.
+
+@item -fharden-compares
+@opindex fharden-compares
+For every logical test that survives gimple optimizations and is
+@emph{not} the condition in a conditional branch (for example,
+conditions tested for conditional moves, or to store in boolean
+variables), emit extra code to compute and verify the reversed
+condition, and to call @code{__builtin_trap} if the results do not
+match.  Use with @samp{-fharden-conditional-branches} to cover all
+conditionals.
+
+@item -fharden-conditional-branches
+@opindex fharden-conditional-branches
+For every non-vectorized conditional branch that survives gimple
+optimizations, emit extra code to compute and verify the reversed
+condition, and to call @code{__builtin_trap} if the result is
+unexpected.  Use with @samp{-fharden-compares} to cover all
+conditionals.
+
+@item -fstack-protector
+@opindex fstack-protector
+Emit extra code to check for buffer overflows, such as stack smashing
+attacks.  This is done by adding a guard variable to functions with
+vulnerable objects.  This includes functions that call @code{alloca}, and
+functions with buffers larger than or equal to 8 bytes.  The guards are
+initialized when a function is entered and then checked when the function
+exits.  If a guard check fails, an error message is printed and the program
+exits.  Only variables that are actually allocated on the stack are
+considered, optimized away variables or variables allocated in registers
+don't count.
+
+@item -fstack-protector-all
+@opindex fstack-protector-all
+Like @option{-fstack-protector} except that all functions are protected.
+
+@item -fstack-protector-strong
+@opindex fstack-protector-strong
+Like @option{-fstack-protector} but includes additional functions to
+be protected --- those that have local array definitions, or have
+references to local frame addresses.  Only variables that are actually
+allocated on the stack are considered, optimized away variables or variables
+allocated in registers don't count.
+
+@item -fstack-protector-explicit
+@opindex fstack-protector-explicit
+Like @option{-fstack-protector} but only protects those functions which
+have the @code{stack_protect} attribute.
+
+@item -fstack-check
+@opindex fstack-check
+Generate code to verify that you do not go beyond the boundary of the
+stack.  You should specify this flag if you are running in an
+environment with multiple threads, but you only rarely need to specify it in
+a single-threaded environment since stack overflow is automatically
+detected on nearly all systems if there is only one stack.
+
+Note that this switch does not actually cause checking to be done; the
+operating system or the language runtime must do that.  The switch causes
+generation of code to ensure that they see the stack being extended.
+
+You can additionally specify a string parameter: @samp{no} means no
+checking, @samp{generic} means force the use of old-style checking,
+@samp{specific} means use the best checking method and is equivalent
+to bare @option{-fstack-check}.
+
+Old-style checking is a generic mechanism that requires no specific
+target support in the compiler but comes with the following drawbacks:
+
+@enumerate
+@item
+Modified allocation strategy for large objects: they are always
+allocated dynamically if their size exceeds a fixed threshold.  Note this
+may change the semantics of some code.
+
+@item
+Fixed limit on the size of the static frame of functions: when it is
+topped by a particular function, stack checking is not reliable and
+a warning is issued by the compiler.
+
+@item
+Inefficiency: because of both the modified allocation strategy and the
+generic implementation, code performance is hampered.
+@end enumerate
+
+Note that old-style stack checking is also the fallback method for
+@samp{specific} if no target support has been added in the compiler.
+
+@samp{-fstack-check=} is designed for Ada's needs to detect infinite recursion
+and stack overflows.  @samp{specific} is an excellent choice when compiling
+Ada code.  It is not generally sufficient to protect against stack-clash
+attacks.  To protect against those you want @samp{-fstack-clash-protection}.
+
+@item -fstack-clash-protection
+@opindex fstack-clash-protection
+Generate code to prevent stack clash style attacks.  When this option is
+enabled, the compiler will only allocate one page of stack space at a time
+and each page is accessed immediately after allocation.  Thus, it prevents
+allocations from jumping over any stack guard page provided by the
+operating system.
+
+Most targets do not fully support stack clash protection.  However, on
+those targets @option{-fstack-clash-protection} will protect dynamic stack
+allocations.  @option{-fstack-clash-protection} may also provide limited
+protection for static stack allocations if the target supports
+@option{-fstack-check=specific}.
+
+@item -fstack-limit-register=@var{reg}
+@itemx -fstack-limit-symbol=@var{sym}
+@itemx -fno-stack-limit
+@opindex fstack-limit-register
+@opindex fstack-limit-symbol
+@opindex fno-stack-limit
+Generate code to ensure that the stack does not grow beyond a certain value,
+either the value of a register or the address of a symbol.  If a larger
+stack is required, a signal is raised at run time.  For most targets,
+the signal is raised before the stack overruns the boundary, so
+it is possible to catch the signal without taking special precautions.
+
+For instance, if the stack starts at absolute address @samp{0x80000000}
+and grows downwards, you can use the flags
+@option{-fstack-limit-symbol=__stack_limit} and
+@option{-Wl,--defsym,__stack_limit=0x7ffe0000} to enforce a stack limit
+of 128KB@.  Note that this may only work with the GNU linker.
+
+You can locally override stack limit checking by using the
+@code{no_stack_limit} function attribute (@pxref{Function Attributes}).
+
+@item -fsplit-stack
+@opindex fsplit-stack
+Generate code to automatically split the stack before it overflows.
+The resulting program has a discontiguous stack which can only
+overflow if the program is unable to allocate any more memory.  This
+is most useful when running threaded programs, as it is no longer
+necessary to calculate a good stack size to use for each thread.  This
+is currently only implemented for the x86 targets running
+GNU/Linux.
+
+When code compiled with @option{-fsplit-stack} calls code compiled
+without @option{-fsplit-stack}, there may not be much stack space
+available for the latter code to run.  If compiling all code,
+including library code, with @option{-fsplit-stack} is not an option,
+then the linker can fix up these calls so that the code compiled
+without @option{-fsplit-stack} always has a large stack.  Support for
+this is implemented in the gold linker in GNU binutils release 2.21
+and later.
+
+@item -fvtable-verify=@r{[}std@r{|}preinit@r{|}none@r{]}
+@opindex fvtable-verify
+This option is only available when compiling C++ code.
+It turns on (or off, if using @option{-fvtable-verify=none}) the security
+feature that verifies at run time, for every virtual call, that
+the vtable pointer through which the call is made is valid for the type of
+the object, and has not been corrupted or overwritten.  If an invalid vtable
+pointer is detected at run time, an error is reported and execution of the
+program is immediately halted.
+
+This option causes run-time data structures to be built at program startup,
+which are used for verifying the vtable pointers.  
+The options @samp{std} and @samp{preinit}
+control the timing of when these data structures are built.  In both cases the
+data structures are built before execution reaches @code{main}.  Using
+@option{-fvtable-verify=std} causes the data structures to be built after
+shared libraries have been loaded and initialized.
+@option{-fvtable-verify=preinit} causes them to be built before shared
+libraries have been loaded and initialized.
+
+If this option appears multiple times in the command line with different
+values specified, @samp{none} takes highest priority over both @samp{std} and
+@samp{preinit}; @samp{preinit} takes priority over @samp{std}.
+
+@item -fvtv-debug
+@opindex fvtv-debug
+When used in conjunction with @option{-fvtable-verify=std} or 
+@option{-fvtable-verify=preinit}, causes debug versions of the 
+runtime functions for the vtable verification feature to be called.  
+This flag also causes the compiler to log information about which 
+vtable pointers it finds for each class.
+This information is written to a file named @file{vtv_set_ptr_data.log} 
+in the directory named by the environment variable @env{VTV_LOGS_DIR} 
+if that is defined or the current working directory otherwise.
+
+Note:  This feature @emph{appends} data to the log file. If you want a fresh log
+file, be sure to delete any existing one.
+
+@item -fvtv-counts
+@opindex fvtv-counts
+This is a debugging flag.  When used in conjunction with
+@option{-fvtable-verify=std} or @option{-fvtable-verify=preinit}, this
+causes the compiler to keep track of the total number of virtual calls
+it encounters and the number of verifications it inserts.  It also
+counts the number of calls to certain run-time library functions
+that it inserts and logs this information for each compilation unit.
+The compiler writes this information to a file named
+@file{vtv_count_data.log} in the directory named by the environment
+variable @env{VTV_LOGS_DIR} if that is defined or the current working
+directory otherwise.  It also counts the size of the vtable pointer sets
+for each class, and writes this information to @file{vtv_class_set_sizes.log}
+in the same directory.
+
+Note:  This feature @emph{appends} data to the log files.  To get fresh log
+files, be sure to delete any existing ones.
+
+@item -finstrument-functions
+@opindex finstrument-functions
+Generate instrumentation calls for entry and exit to functions.  Just
+after function entry and just before function exit, the following
+profiling functions are called with the address of the current
+function and its call site.  (On some platforms,
+@code{__builtin_return_address} does not work beyond the current
+function, so the call site information may not be available to the
+profiling functions otherwise.)
+
+@smallexample
+void __cyg_profile_func_enter (void *this_fn,
+                               void *call_site);
+void __cyg_profile_func_exit  (void *this_fn,
+                               void *call_site);
+@end smallexample
+
+The first argument is the address of the start of the current function,
+which may be looked up exactly in the symbol table.
+
+This instrumentation is also done for functions expanded inline in other
+functions.  The profiling calls indicate where, conceptually, the
+inline function is entered and exited.  This means that addressable
+versions of such functions must be available.  If all your uses of a
+function are expanded inline, this may mean an additional expansion of
+code size.  If you use @code{extern inline} in your C code, an
+addressable version of such functions must be provided.  (This is
+normally the case anyway, but if you get lucky and the optimizer always
+expands the functions inline, you might have gotten away without
+providing static copies.)
+
+A function may be given the attribute @code{no_instrument_function}, in
+which case this instrumentation is not done.  This can be used, for
+example, for the profiling functions listed above, high-priority
+interrupt routines, and any functions from which the profiling functions
+cannot safely be called (perhaps signal handlers, if the profiling
+routines generate output or allocate memory).
+@xref{Common Function Attributes}.
+
+@item -finstrument-functions-once
+@opindex -finstrument-functions-once
+This is similar to @option{-finstrument-functions}, but the profiling
+functions are called only once per instrumented function, i.e. the first
+profiling function is called after the first entry into the instrumented
+function and the second profiling function is called before the exit
+corresponding to this first entry.
+
+The definition of @code{once} for the purpose of this option is a little
+vague because the implementation is not protected against data races.
+As a result, the implementation only guarantees that the profiling
+functions are called at @emph{least} once per process and at @emph{most}
+once per thread, but the calls are always paired, that is to say, if a
+thread calls the first function, then it will call the second function,
+unless it never reaches the exit of the instrumented function.
+
+@item -finstrument-functions-exclude-file-list=@var{file},@var{file},@dots{}
+@opindex finstrument-functions-exclude-file-list
+
+Set the list of functions that are excluded from instrumentation (see
+the description of @option{-finstrument-functions}).  If the file that
+contains a function definition matches with one of @var{file}, then
+that function is not instrumented.  The match is done on substrings:
+if the @var{file} parameter is a substring of the file name, it is
+considered to be a match.
+
+For example:
+
+@smallexample
+-finstrument-functions-exclude-file-list=/bits/stl,include/sys
+@end smallexample
+
+@noindent
+excludes any inline function defined in files whose pathnames
+contain @file{/bits/stl} or @file{include/sys}.
+
+If, for some reason, you want to include letter @samp{,} in one of
+@var{sym}, write @samp{\,}. For example,
+@option{-finstrument-functions-exclude-file-list='\,\,tmp'}
+(note the single quote surrounding the option).
+
+@item -finstrument-functions-exclude-function-list=@var{sym},@var{sym},@dots{}
+@opindex finstrument-functions-exclude-function-list
+
+This is similar to @option{-finstrument-functions-exclude-file-list},
+but this option sets the list of function names to be excluded from
+instrumentation.  The function name to be matched is its user-visible
+name, such as @code{vector<int> blah(const vector<int> &)}, not the
+internal mangled name (e.g., @code{_Z4blahRSt6vectorIiSaIiEE}).  The
+match is done on substrings: if the @var{sym} parameter is a substring
+of the function name, it is considered to be a match.  For C99 and C++
+extended identifiers, the function name must be given in UTF-8, not
+using universal character names.
+
+@item -fpatchable-function-entry=@var{N}[,@var{M}]
+@opindex fpatchable-function-entry
+Generate @var{N} NOPs right at the beginning
+of each function, with the function entry point before the @var{M}th NOP.
+If @var{M} is omitted, it defaults to @code{0} so the
+function entry points to the address just at the first NOP.
+The NOP instructions reserve extra space which can be used to patch in
+any desired instrumentation at run time, provided that the code segment
+is writable.  The amount of space is controllable indirectly via
+the number of NOPs; the NOP instruction used corresponds to the instruction
+emitted by the internal GCC back-end interface @code{gen_nop}.  This behavior
+is target-specific and may also depend on the architecture variant and/or
+other compilation options.
+
+For run-time identification, the starting addresses of these areas,
+which correspond to their respective function entries minus @var{M},
+are additionally collected in the @code{__patchable_function_entries}
+section of the resulting binary.
+
+Note that the value of @code{__attribute__ ((patchable_function_entry
+(N,M)))} takes precedence over command-line option
+@option{-fpatchable-function-entry=N,M}.  This can be used to increase
+the area size or to remove it completely on a single function.
+If @code{N=0}, no pad location is recorded.
+
+The NOP instructions are inserted at---and maybe before, depending on
+@var{M}---the function entry address, even before the prologue.  On
+PowerPC with the ELFv2 ABI, for a function with dual entry points,
+the local entry point is this function entry address.
+
+The maximum value of @var{N} and @var{M} is 65535.  On PowerPC with the
+ELFv2 ABI, for a function with dual entry points, the supported values
+for @var{M} are 0, 2, 6 and 14.
+@end table
+
+
+@node Preprocessor Options
+@section Options Controlling the Preprocessor
+@cindex preprocessor options
+@cindex options, preprocessor
+
+These options control the C preprocessor, which is run on each C source
+file before actual compilation.
+
+If you use the @option{-E} option, nothing is done except preprocessing.
+Some of these options make sense only together with @option{-E} because
+they cause the preprocessor output to be unsuitable for actual
+compilation.
+
+In addition to the options listed here, there are a number of options 
+to control search paths for include files documented in 
+@ref{Directory Options}.  
+Options to control preprocessor diagnostics are listed in 
+@ref{Warning Options}.
+
+@table @gcctabopt
+@include cppopts.texi
+
+@item -Wp,@var{option}
+@opindex Wp
+You can use @option{-Wp,@var{option}} to bypass the compiler driver
+and pass @var{option} directly through to the preprocessor.  If
+@var{option} contains commas, it is split into multiple options at the
+commas.  However, many options are modified, translated or interpreted
+by the compiler driver before being passed to the preprocessor, and
+@option{-Wp} forcibly bypasses this phase.  The preprocessor's direct
+interface is undocumented and subject to change, so whenever possible
+you should avoid using @option{-Wp} and let the driver handle the
+options instead.
+
+@item -Xpreprocessor @var{option}
+@opindex Xpreprocessor
+Pass @var{option} as an option to the preprocessor.  You can use this to
+supply system-specific preprocessor options that GCC does not 
+recognize.
+
+If you want to pass an option that takes an argument, you must use
+@option{-Xpreprocessor} twice, once for the option and once for the argument.
+
+@item -no-integrated-cpp
+@opindex no-integrated-cpp
+Perform preprocessing as a separate pass before compilation.
+By default, GCC performs preprocessing as an integrated part of
+input tokenization and parsing.
+If this option is provided, the appropriate language front end
+(@command{cc1}, @command{cc1plus}, or @command{cc1obj} for C, C++,
+and Objective-C, respectively) is instead invoked twice,
+once for preprocessing only and once for actual compilation
+of the preprocessed input.
+This option may be useful in conjunction with the @option{-B} or
+@option{-wrapper} options to specify an alternate preprocessor or
+perform additional processing of the program source between
+normal preprocessing and compilation.
+
+@item -flarge-source-files
+@opindex flarge-source-files
+Adjust GCC to expect large source files, at the expense of slower
+compilation and higher memory usage.
+
+Specifically, GCC normally tracks both column numbers and line numbers
+within source files and it normally prints both of these numbers in
+diagnostics.  However, once it has processed a certain number of source
+lines, it stops tracking column numbers and only tracks line numbers.
+This means that diagnostics for later lines do not include column numbers.
+It also means that options like @option{-Wmisleading-indentation} cease to work
+at that point, although the compiler prints a note if this happens.
+Passing @option{-flarge-source-files} significantly increases the number
+of source lines that GCC can process before it stops tracking columns.
+
+@end table
+
+@node Assembler Options
+@section Passing Options to the Assembler
+
+@c prevent bad page break with this line
+You can pass options to the assembler.
+
+@table @gcctabopt
+@item -Wa,@var{option}
+@opindex Wa
+Pass @var{option} as an option to the assembler.  If @var{option}
+contains commas, it is split into multiple options at the commas.
+
+@item -Xassembler @var{option}
+@opindex Xassembler
+Pass @var{option} as an option to the assembler.  You can use this to
+supply system-specific assembler options that GCC does not
+recognize.
+
+If you want to pass an option that takes an argument, you must use
+@option{-Xassembler} twice, once for the option and once for the argument.
+
+@end table
+
+@node Link Options
+@section Options for Linking
+@cindex link options
+@cindex options, linking
+
+These options come into play when the compiler links object files into
+an executable output file.  They are meaningless if the compiler is
+not doing a link step.
+
+@table @gcctabopt
+@cindex file names
+@item @var{object-file-name}
+A file name that does not end in a special recognized suffix is
+considered to name an object file or library.  (Object files are
+distinguished from libraries by the linker according to the file
+contents.)  If linking is done, these object files are used as input
+to the linker.
+
+@item -c
+@itemx -S
+@itemx -E
+@opindex c
+@opindex S
+@opindex E
+If any of these options is used, then the linker is not run, and
+object file names should not be used as arguments.  @xref{Overall
+Options}.
+
+@item -flinker-output=@var{type}
+@opindex flinker-output
+This option controls code generation of the link-time optimizer.  By
+default the linker output is automatically determined by the linker
+plugin.  For debugging the compiler and if incremental linking with a 
+non-LTO object file is desired, it may be useful to control the type
+manually.
+
+If @var{type} is @samp{exec}, code generation produces a static
+binary. In this case @option{-fpic} and @option{-fpie} are both
+disabled.
+
+If @var{type} is @samp{dyn}, code generation produces a shared
+library.  In this case @option{-fpic} or @option{-fPIC} is preserved,
+but not enabled automatically.  This allows to build shared libraries
+without position-independent code on architectures where this is
+possible, i.e.@: on x86.
+
+If @var{type} is @samp{pie}, code generation produces an @option{-fpie}
+executable. This results in similar optimizations as @samp{exec}
+except that @option{-fpie} is not disabled if specified at compilation
+time.
+
+If @var{type} is @samp{rel}, the compiler assumes that incremental linking is
+done.  The sections containing intermediate code for link-time optimization are
+merged, pre-optimized, and output to the resulting object file. In addition, if
+@option{-ffat-lto-objects} is specified, binary code is produced for future
+non-LTO linking. The object file produced by incremental linking is smaller
+than a static library produced from the same object files.  At link time the
+result of incremental linking also loads faster than a static
+library assuming that the majority of objects in the library are used.
+
+Finally @samp{nolto-rel} configures the compiler for incremental linking where
+code generation is forced, a final binary is produced, and the intermediate
+code for later link-time optimization is stripped. When multiple object files
+are linked together the resulting code is better optimized than with
+link-time optimizations disabled (for example, cross-module inlining 
+happens), but most of benefits of whole program optimizations are lost. 
+
+During the incremental link (by @option{-r}) the linker plugin defaults to
+@option{rel}. With current interfaces to GNU Binutils it is however not
+possible to incrementally link LTO objects and non-LTO objects into a single
+mixed object file.  If any of object files in incremental link cannot
+be used for link-time optimization, the linker plugin issues a warning and
+uses @samp{nolto-rel}. To maintain whole program optimization, it is
+recommended to link such objects into static library instead. Alternatively it
+is possible to use H.J. Lu's binutils with support for mixed objects.
+
+@item -fuse-ld=bfd
+@opindex fuse-ld=bfd
+Use the @command{bfd} linker instead of the default linker.
+
+@item -fuse-ld=gold
+@opindex fuse-ld=gold
+Use the @command{gold} linker instead of the default linker.
+
+@item -fuse-ld=lld
+@opindex fuse-ld=lld
+Use the LLVM @command{lld} linker instead of the default linker.
+
+@item -fuse-ld=mold
+@opindex fuse-ld=mold
+Use the Modern Linker (@command{mold}) instead of the default linker.
+
+@cindex Libraries
+@item -l@var{library}
+@itemx -l @var{library}
+@opindex l
+Search the library named @var{library} when linking.  (The second
+alternative with the library as a separate argument is only for
+POSIX compliance and is not recommended.)
+
+The @option{-l} option is passed directly to the linker by GCC.  Refer
+to your linker documentation for exact details.  The general
+description below applies to the GNU linker.  
+
+The linker searches a standard list of directories for the library.
+The directories searched include several standard system directories
+plus any that you specify with @option{-L}.
+
+Static libraries are archives of object files, and have file names
+like @file{lib@var{library}.a}.  Some targets also support shared
+libraries, which typically have names like @file{lib@var{library}.so}.
+If both static and shared libraries are found, the linker gives
+preference to linking with the shared library unless the
+@option{-static} option is used.
+
+It makes a difference where in the command you write this option; the
+linker searches and processes libraries and object files in the order they
+are specified.  Thus, @samp{foo.o -lz bar.o} searches library @samp{z}
+after file @file{foo.o} but before @file{bar.o}.  If @file{bar.o} refers
+to functions in @samp{z}, those functions may not be loaded.
+
+@item -lobjc
+@opindex lobjc
+You need this special case of the @option{-l} option in order to
+link an Objective-C or Objective-C++ program.
+
+@item -nostartfiles
+@opindex nostartfiles
+Do not use the standard system startup files when linking.
+The standard system libraries are used normally, unless @option{-nostdlib},
+@option{-nolibc}, or @option{-nodefaultlibs} is used.
+
+@item -nodefaultlibs
+@opindex nodefaultlibs
+Do not use the standard system libraries when linking.
+Only the libraries you specify are passed to the linker, and options
+specifying linkage of the system libraries, such as @option{-static-libgcc}
+or @option{-shared-libgcc}, are ignored.  
+The standard startup files are used normally, unless @option{-nostartfiles}
+is used.  
+
+The compiler may generate calls to @code{memcmp},
+@code{memset}, @code{memcpy} and @code{memmove}.
+These entries are usually resolved by entries in
+libc.  These entry points should be supplied through some other
+mechanism when this option is specified.
+
+@item -nolibc
+@opindex nolibc
+Do not use the C library or system libraries tightly coupled with it when
+linking.  Still link with the startup files, @file{libgcc} or toolchain
+provided language support libraries such as @file{libgnat}, @file{libgfortran}
+or @file{libstdc++} unless options preventing their inclusion are used as
+well.  This typically removes @option{-lc} from the link command line, as well
+as system libraries that normally go with it and become meaningless when
+absence of a C library is assumed, for example @option{-lpthread} or
+@option{-lm} in some configurations.  This is intended for bare-board
+targets when there is indeed no C library available.
+
+@item -nostdlib
+@opindex nostdlib
+Do not use the standard system startup files or libraries when linking.
+No startup files and only the libraries you specify are passed to
+the linker, and options specifying linkage of the system libraries, such as
+@option{-static-libgcc} or @option{-shared-libgcc}, are ignored.
+
+The compiler may generate calls to @code{memcmp}, @code{memset},
+@code{memcpy} and @code{memmove}.
+These entries are usually resolved by entries in
+libc.  These entry points should be supplied through some other
+mechanism when this option is specified.
+
+@cindex @option{-lgcc}, use with @option{-nostdlib}
+@cindex @option{-nostdlib} and unresolved references
+@cindex unresolved references and @option{-nostdlib}
+@cindex @option{-lgcc}, use with @option{-nodefaultlibs}
+@cindex @option{-nodefaultlibs} and unresolved references
+@cindex unresolved references and @option{-nodefaultlibs}
+One of the standard libraries bypassed by @option{-nostdlib} and
+@option{-nodefaultlibs} is @file{libgcc.a}, a library of internal subroutines
+which GCC uses to overcome shortcomings of particular machines, or special
+needs for some languages.
+(@xref{Interface,,Interfacing to GCC Output,gccint,GNU Compiler
+Collection (GCC) Internals},
+for more discussion of @file{libgcc.a}.)
+In most cases, you need @file{libgcc.a} even when you want to avoid
+other standard libraries.  In other words, when you specify @option{-nostdlib}
+or @option{-nodefaultlibs} you should usually specify @option{-lgcc} as well.
+This ensures that you have no unresolved references to internal GCC
+library subroutines.
+(An example of such an internal subroutine is @code{__main}, used to ensure C++
+constructors are called; @pxref{Collect2,,@code{collect2}, gccint,
+GNU Compiler Collection (GCC) Internals}.)
+
+@item -nostdlib++
+@opindex nostdlib++
+Do not implicitly link with standard C++ libraries.
+
+@item -e @var{entry}
+@itemx --entry=@var{entry}
+@opindex e
+@opindex entry
+
+Specify that the program entry point is @var{entry}.  The argument is
+interpreted by the linker; the GNU linker accepts either a symbol name
+or an address.
+
+@item -pie
+@opindex pie
+Produce a dynamically linked position independent executable on targets
+that support it.  For predictable results, you must also specify the same
+set of options used for compilation (@option{-fpie}, @option{-fPIE},
+or model suboptions) when you specify this linker option.
+
+@item -no-pie
+@opindex no-pie
+Don't produce a dynamically linked position independent executable.
+
+@item -static-pie
+@opindex static-pie
+Produce a static position independent executable on targets that support
+it.  A static position independent executable is similar to a static
+executable, but can be loaded at any address without a dynamic linker.
+For predictable results, you must also specify the same set of options
+used for compilation (@option{-fpie}, @option{-fPIE}, or model
+suboptions) when you specify this linker option.
+
+@item -pthread
+@opindex pthread
+Link with the POSIX threads library.  This option is supported on 
+GNU/Linux targets, most other Unix derivatives, and also on 
+x86 Cygwin and MinGW targets.  On some targets this option also sets 
+flags for the preprocessor, so it should be used consistently for both
+compilation and linking.
+
+@item -r
+@opindex r
+Produce a relocatable object as output.  This is also known as partial
+linking.
+
+@item -rdynamic
+@opindex rdynamic
+Pass the flag @option{-export-dynamic} to the ELF linker, on targets
+that support it. This instructs the linker to add all symbols, not
+only used ones, to the dynamic symbol table. This option is needed
+for some uses of @code{dlopen} or to allow obtaining backtraces
+from within a program.
+
+@item -s
+@opindex s
+Remove all symbol table and relocation information from the executable.
+
+@item -static
+@opindex static
+On systems that support dynamic linking, this overrides @option{-pie}
+and prevents linking with the shared libraries.  On other systems, this
+option has no effect.
+
+@item -shared
+@opindex shared
+Produce a shared object which can then be linked with other objects to
+form an executable.  Not all systems support this option.  For predictable
+results, you must also specify the same set of options used for compilation
+(@option{-fpic}, @option{-fPIC}, or model suboptions) when
+you specify this linker option.@footnote{On some systems, @samp{gcc -shared}
+needs to build supplementary stub code for constructors to work.  On
+multi-libbed systems, @samp{gcc -shared} must select the correct support
+libraries to link against.  Failing to supply the correct flags may lead
+to subtle defects.  Supplying them in cases where they are not necessary
+is innocuous.}
+
+@item -shared-libgcc
+@itemx -static-libgcc
+@opindex shared-libgcc
+@opindex static-libgcc
+On systems that provide @file{libgcc} as a shared library, these options
+force the use of either the shared or static version, respectively.
+If no shared version of @file{libgcc} was built when the compiler was
+configured, these options have no effect.
+
+There are several situations in which an application should use the
+shared @file{libgcc} instead of the static version.  The most common
+of these is when the application wishes to throw and catch exceptions
+across different shared libraries.  In that case, each of the libraries
+as well as the application itself should use the shared @file{libgcc}.
+
+Therefore, the G++ driver automatically adds @option{-shared-libgcc}
+whenever you build a shared library or a main executable, because C++
+programs typically use exceptions, so this is the right thing to do.
+
+If, instead, you use the GCC driver to create shared libraries, you may
+find that they are not always linked with the shared @file{libgcc}.
+If GCC finds, at its configuration time, that you have a non-GNU linker
+or a GNU linker that does not support option @option{--eh-frame-hdr},
+it links the shared version of @file{libgcc} into shared libraries
+by default.  Otherwise, it takes advantage of the linker and optimizes
+away the linking with the shared version of @file{libgcc}, linking with
+the static version of libgcc by default.  This allows exceptions to
+propagate through such shared libraries, without incurring relocation
+costs at library load time.
+
+However, if a library or main executable is supposed to throw or catch
+exceptions, you must link it using the G++ driver, or using the option
+@option{-shared-libgcc}, such that it is linked with the shared
+@file{libgcc}.
+
+@item -static-libasan
+@opindex static-libasan
+When the @option{-fsanitize=address} option is used to link a program,
+the GCC driver automatically links against @option{libasan}.  If
+@file{libasan} is available as a shared library, and the @option{-static}
+option is not used, then this links against the shared version of
+@file{libasan}.  The @option{-static-libasan} option directs the GCC
+driver to link @file{libasan} statically, without necessarily linking
+other libraries statically.
+
+@item -static-libtsan
+@opindex static-libtsan
+When the @option{-fsanitize=thread} option is used to link a program,
+the GCC driver automatically links against @option{libtsan}.  If
+@file{libtsan} is available as a shared library, and the @option{-static}
+option is not used, then this links against the shared version of
+@file{libtsan}.  The @option{-static-libtsan} option directs the GCC
+driver to link @file{libtsan} statically, without necessarily linking
+other libraries statically.
+
+@item -static-liblsan
+@opindex static-liblsan
+When the @option{-fsanitize=leak} option is used to link a program,
+the GCC driver automatically links against @option{liblsan}.  If
+@file{liblsan} is available as a shared library, and the @option{-static}
+option is not used, then this links against the shared version of
+@file{liblsan}.  The @option{-static-liblsan} option directs the GCC
+driver to link @file{liblsan} statically, without necessarily linking
+other libraries statically.
+
+@item -static-libubsan
+@opindex static-libubsan
+When the @option{-fsanitize=undefined} option is used to link a program,
+the GCC driver automatically links against @option{libubsan}.  If
+@file{libubsan} is available as a shared library, and the @option{-static}
+option is not used, then this links against the shared version of
+@file{libubsan}.  The @option{-static-libubsan} option directs the GCC
+driver to link @file{libubsan} statically, without necessarily linking
+other libraries statically.
+
+@item -static-libstdc++
+@opindex static-libstdc++
+When the @command{g++} program is used to link a C++ program, it
+normally automatically links against @option{libstdc++}.  If
+@file{libstdc++} is available as a shared library, and the
+@option{-static} option is not used, then this links against the
+shared version of @file{libstdc++}.  That is normally fine.  However, it
+is sometimes useful to freeze the version of @file{libstdc++} used by
+the program without going all the way to a fully static link.  The
+@option{-static-libstdc++} option directs the @command{g++} driver to
+link @file{libstdc++} statically, without necessarily linking other
+libraries statically.
+
+@item -symbolic
+@opindex symbolic
+Bind references to global symbols when building a shared object.  Warn
+about any unresolved references (unless overridden by the link editor
+option @option{-Xlinker -z -Xlinker defs}).  Only a few systems support
+this option.
+
+@item -T @var{script}
+@opindex T
+@cindex linker script
+Use @var{script} as the linker script.  This option is supported by most
+systems using the GNU linker.  On some targets, such as bare-board
+targets without an operating system, the @option{-T} option may be required
+when linking to avoid references to undefined symbols.
+
+@item -Xlinker @var{option}
+@opindex Xlinker
+Pass @var{option} as an option to the linker.  You can use this to
+supply system-specific linker options that GCC does not recognize.
+
+If you want to pass an option that takes a separate argument, you must use
+@option{-Xlinker} twice, once for the option and once for the argument.
+For example, to pass @option{-assert definitions}, you must write
+@option{-Xlinker -assert -Xlinker definitions}.  It does not work to write
+@option{-Xlinker "-assert definitions"}, because this passes the entire
+string as a single argument, which is not what the linker expects.
+
+When using the GNU linker, it is usually more convenient to pass
+arguments to linker options using the @option{@var{option}=@var{value}}
+syntax than as separate arguments.  For example, you can specify
+@option{-Xlinker -Map=output.map} rather than
+@option{-Xlinker -Map -Xlinker output.map}.  Other linkers may not support
+this syntax for command-line options.
+
+@item -Wl,@var{option}
+@opindex Wl
+Pass @var{option} as an option to the linker.  If @var{option} contains
+commas, it is split into multiple options at the commas.  You can use this
+syntax to pass an argument to the option.
+For example, @option{-Wl,-Map,output.map} passes @option{-Map output.map} to the
+linker.  When using the GNU linker, you can also get the same effect with
+@option{-Wl,-Map=output.map}.
+
+@item -u @var{symbol}
+@opindex u
+Pretend the symbol @var{symbol} is undefined, to force linking of
+library modules to define it.  You can use @option{-u} multiple times with
+different symbols to force loading of additional library modules.
+
+@item -z @var{keyword}
+@opindex z
+@option{-z} is passed directly on to the linker along with the keyword
+@var{keyword}. See the section in the documentation of your linker for
+permitted values and their meanings.
+@end table
+
+@node Directory Options
+@section Options for Directory Search
+@cindex directory options
+@cindex options, directory search
+@cindex search path
+
+These options specify directories to search for header files, for
+libraries and for parts of the compiler:
+
+@table @gcctabopt
+@include cppdiropts.texi
+
+@item -iplugindir=@var{dir}
+@opindex iplugindir=
+Set the directory to search for plugins that are passed
+by @option{-fplugin=@var{name}} instead of
+@option{-fplugin=@var{path}/@var{name}.so}.  This option is not meant
+to be used by the user, but only passed by the driver.
+
+@item -L@var{dir}
+@opindex L
+Add directory @var{dir} to the list of directories to be searched
+for @option{-l}.
+
+@item -B@var{prefix}
+@opindex B
+This option specifies where to find the executables, libraries,
+include files, and data files of the compiler itself.
+
+The compiler driver program runs one or more of the subprograms
+@command{cpp}, @command{cc1}, @command{as} and @command{ld}.  It tries
+@var{prefix} as a prefix for each program it tries to run, both with and
+without @samp{@var{machine}/@var{version}/} for the corresponding target
+machine and compiler version.
+
+For each subprogram to be run, the compiler driver first tries the
+@option{-B} prefix, if any.  If that name is not found, or if @option{-B}
+is not specified, the driver tries two standard prefixes, 
+@file{/usr/lib/gcc/} and @file{/usr/local/lib/gcc/}.  If neither of
+those results in a file name that is found, the unmodified program
+name is searched for using the directories specified in your
+@env{PATH} environment variable.
+
+The compiler checks to see if the path provided by @option{-B}
+refers to a directory, and if necessary it adds a directory
+separator character at the end of the path.
+
+@option{-B} prefixes that effectively specify directory names also apply
+to libraries in the linker, because the compiler translates these
+options into @option{-L} options for the linker.  They also apply to
+include files in the preprocessor, because the compiler translates these
+options into @option{-isystem} options for the preprocessor.  In this case,
+the compiler appends @samp{include} to the prefix.
+
+The runtime support file @file{libgcc.a} can also be searched for using
+the @option{-B} prefix, if needed.  If it is not found there, the two
+standard prefixes above are tried, and that is all.  The file is left
+out of the link if it is not found by those means.
+
+Another way to specify a prefix much like the @option{-B} prefix is to use
+the environment variable @env{GCC_EXEC_PREFIX}.  @xref{Environment
+Variables}.
+
+As a special kludge, if the path provided by @option{-B} is
+@file{[dir/]stage@var{N}/}, where @var{N} is a number in the range 0 to
+9, then it is replaced by @file{[dir/]include}.  This is to help
+with boot-strapping the compiler.
+
+@item -no-canonical-prefixes
+@opindex no-canonical-prefixes
+Do not expand any symbolic links, resolve references to @samp{/../}
+or @samp{/./}, or make the path absolute when generating a relative
+prefix.
+
+@item --sysroot=@var{dir}
+@opindex sysroot
+Use @var{dir} as the logical root directory for headers and libraries.
+For example, if the compiler normally searches for headers in
+@file{/usr/include} and libraries in @file{/usr/lib}, it instead
+searches @file{@var{dir}/usr/include} and @file{@var{dir}/usr/lib}.
+
+If you use both this option and the @option{-isysroot} option, then
+the @option{--sysroot} option applies to libraries, but the
+@option{-isysroot} option applies to header files.
+
+The GNU linker (beginning with version 2.16) has the necessary support
+for this option.  If your linker does not support this option, the
+header file aspect of @option{--sysroot} still works, but the
+library aspect does not.
+
+@item --no-sysroot-suffix
+@opindex no-sysroot-suffix
+For some targets, a suffix is added to the root directory specified
+with @option{--sysroot}, depending on the other options used, so that
+headers may for example be found in
+@file{@var{dir}/@var{suffix}/usr/include} instead of
+@file{@var{dir}/usr/include}.  This option disables the addition of
+such a suffix.
+
+@end table
+
+@node Code Gen Options
+@section Options for Code Generation Conventions
+@cindex code generation conventions
+@cindex options, code generation
+@cindex run-time options
+
+These machine-independent options control the interface conventions
+used in code generation.
+
+Most of them have both positive and negative forms; the negative form
+of @option{-ffoo} is @option{-fno-foo}.  In the table below, only
+one of the forms is listed---the one that is not the default.  You
+can figure out the other form by either removing @samp{no-} or adding
+it.
+
+@table @gcctabopt
+@item -fstack-reuse=@var{reuse-level}
+@opindex fstack_reuse
+This option controls stack space reuse for user declared local/auto variables
+and compiler generated temporaries.  @var{reuse_level} can be @samp{all},
+@samp{named_vars}, or @samp{none}. @samp{all} enables stack reuse for all
+local variables and temporaries, @samp{named_vars} enables the reuse only for
+user defined local variables with names, and @samp{none} disables stack reuse
+completely. The default value is @samp{all}. The option is needed when the
+program extends the lifetime of a scoped local variable or a compiler generated
+temporary beyond the end point defined by the language.  When a lifetime of
+a variable ends, and if the variable lives in memory, the optimizing compiler
+has the freedom to reuse its stack space with other temporaries or scoped
+local variables whose live range does not overlap with it. Legacy code extending
+local lifetime is likely to break with the stack reuse optimization.
+
+For example,
+
+@smallexample
+   int *p;
+   @{
+     int local1;
+
+     p = &local1;
+     local1 = 10;
+     ....
+   @}
+   @{
+      int local2;
+      local2 = 20;
+      ...
+   @}
+
+   if (*p == 10)  // out of scope use of local1
+     @{
+
+     @}
+@end smallexample
+
+Another example:
+@smallexample
+
+   struct A
+   @{
+       A(int k) : i(k), j(k) @{ @}
+       int i;
+       int j;
+   @};
+
+   A *ap;
+
+   void foo(const A& ar)
+   @{
+      ap = &ar;
+   @}
+
+   void bar()
+   @{
+      foo(A(10)); // temp object's lifetime ends when foo returns
+
+      @{
+        A a(20);
+        ....
+      @}
+      ap->i+= 10;  // ap references out of scope temp whose space
+                   // is reused with a. What is the value of ap->i?
+   @}
+
+@end smallexample
+
+The lifetime of a compiler generated temporary is well defined by the C++
+standard. When a lifetime of a temporary ends, and if the temporary lives
+in memory, the optimizing compiler has the freedom to reuse its stack
+space with other temporaries or scoped local variables whose live range
+does not overlap with it. However some of the legacy code relies on
+the behavior of older compilers in which temporaries' stack space is
+not reused, the aggressive stack reuse can lead to runtime errors. This
+option is used to control the temporary stack reuse optimization.
+
+@item -ftrapv
+@opindex ftrapv
+This option generates traps for signed overflow on addition, subtraction,
+multiplication operations.
+The options @option{-ftrapv} and @option{-fwrapv} override each other, so using
+@option{-ftrapv} @option{-fwrapv} on the command-line results in
+@option{-fwrapv} being effective.  Note that only active options override, so
+using @option{-ftrapv} @option{-fwrapv} @option{-fno-wrapv} on the command-line
+results in @option{-ftrapv} being effective.
+
+@item -fwrapv
+@opindex fwrapv
+This option instructs the compiler to assume that signed arithmetic
+overflow of addition, subtraction and multiplication wraps around
+using twos-complement representation.  This flag enables some optimizations
+and disables others.
+The options @option{-ftrapv} and @option{-fwrapv} override each other, so using
+@option{-ftrapv} @option{-fwrapv} on the command-line results in
+@option{-fwrapv} being effective.  Note that only active options override, so
+using @option{-ftrapv} @option{-fwrapv} @option{-fno-wrapv} on the command-line
+results in @option{-ftrapv} being effective.
+
+@item -fwrapv-pointer
+@opindex fwrapv-pointer
+This option instructs the compiler to assume that pointer arithmetic
+overflow on addition and subtraction wraps around using twos-complement
+representation.  This flag disables some optimizations which assume
+pointer overflow is invalid.
+
+@item -fstrict-overflow
+@opindex fstrict-overflow
+This option implies @option{-fno-wrapv} @option{-fno-wrapv-pointer} and when
+negated implies @option{-fwrapv} @option{-fwrapv-pointer}.
+
+@item -fexceptions
+@opindex fexceptions
+Enable exception handling.  Generates extra code needed to propagate
+exceptions.  For some targets, this implies GCC generates frame
+unwind information for all functions, which can produce significant data
+size overhead, although it does not affect execution.  If you do not
+specify this option, GCC enables it by default for languages like
+C++ that normally require exception handling, and disables it for
+languages like C that do not normally require it.  However, you may need
+to enable this option when compiling C code that needs to interoperate
+properly with exception handlers written in C++.  You may also wish to
+disable this option if you are compiling older C++ programs that don't
+use exception handling.
+
+@item -fnon-call-exceptions
+@opindex fnon-call-exceptions
+Generate code that allows trapping instructions to throw exceptions.
+Note that this requires platform-specific runtime support that does
+not exist everywhere.  Moreover, it only allows @emph{trapping}
+instructions to throw exceptions, i.e.@: memory references or floating-point
+instructions.  It does not allow exceptions to be thrown from
+arbitrary signal handlers such as @code{SIGALRM}.  This enables
+@option{-fexceptions}.
+
+@item -fdelete-dead-exceptions
+@opindex fdelete-dead-exceptions
+Consider that instructions that may throw exceptions but don't otherwise
+contribute to the execution of the program can be optimized away.
+This does not affect calls to functions except those with the
+@code{pure} or @code{const} attributes.
+This option is enabled by default for the Ada and C++ compilers, as permitted by
+the language specifications.
+Optimization passes that cause dead exceptions to be removed are enabled independently at different optimization levels.
+
+@item -funwind-tables
+@opindex funwind-tables
+Similar to @option{-fexceptions}, except that it just generates any needed
+static data, but does not affect the generated code in any other way.
+You normally do not need to enable this option; instead, a language processor
+that needs this handling enables it on your behalf.
+
+@item -fasynchronous-unwind-tables
+@opindex fasynchronous-unwind-tables
+Generate unwind table in DWARF format, if supported by target machine.  The
+table is exact at each instruction boundary, so it can be used for stack
+unwinding from asynchronous events (such as debugger or garbage collector).
+
+@item -fno-gnu-unique
+@opindex fno-gnu-unique
+@opindex fgnu-unique
+On systems with recent GNU assembler and C library, the C++ compiler
+uses the @code{STB_GNU_UNIQUE} binding to make sure that definitions
+of template static data members and static local variables in inline
+functions are unique even in the presence of @code{RTLD_LOCAL}; this
+is necessary to avoid problems with a library used by two different
+@code{RTLD_LOCAL} plugins depending on a definition in one of them and
+therefore disagreeing with the other one about the binding of the
+symbol.  But this causes @code{dlclose} to be ignored for affected
+DSOs; if your program relies on reinitialization of a DSO via
+@code{dlclose} and @code{dlopen}, you can use
+@option{-fno-gnu-unique}.
+
+@item -fpcc-struct-return
+@opindex fpcc-struct-return
+Return ``short'' @code{struct} and @code{union} values in memory like
+longer ones, rather than in registers.  This convention is less
+efficient, but it has the advantage of allowing intercallability between
+GCC-compiled files and files compiled with other compilers, particularly
+the Portable C Compiler (pcc).
+
+The precise convention for returning structures in memory depends
+on the target configuration macros.
+
+Short structures and unions are those whose size and alignment match
+that of some integer type.
+
+@strong{Warning:} code compiled with the @option{-fpcc-struct-return}
+switch is not binary compatible with code compiled with the
+@option{-freg-struct-return} switch.
+Use it to conform to a non-default application binary interface.
+
+@item -freg-struct-return
+@opindex freg-struct-return
+Return @code{struct} and @code{union} values in registers when possible.
+This is more efficient for small structures than
+@option{-fpcc-struct-return}.
+
+If you specify neither @option{-fpcc-struct-return} nor
+@option{-freg-struct-return}, GCC defaults to whichever convention is
+standard for the target.  If there is no standard convention, GCC
+defaults to @option{-fpcc-struct-return}, except on targets where GCC is
+the principal compiler.  In those cases, we can choose the standard, and
+we chose the more efficient register return alternative.
+
+@strong{Warning:} code compiled with the @option{-freg-struct-return}
+switch is not binary compatible with code compiled with the
+@option{-fpcc-struct-return} switch.
+Use it to conform to a non-default application binary interface.
+
+@item -fshort-enums
+@opindex fshort-enums
+Allocate to an @code{enum} type only as many bytes as it needs for the
+declared range of possible values.  Specifically, the @code{enum} type
+is equivalent to the smallest integer type that has enough room.
+
+@strong{Warning:} the @option{-fshort-enums} switch causes GCC to generate
+code that is not binary compatible with code generated without that switch.
+Use it to conform to a non-default application binary interface.
+
+@item -fshort-wchar
+@opindex fshort-wchar
+Override the underlying type for @code{wchar_t} to be @code{short
+unsigned int} instead of the default for the target.  This option is
+useful for building programs to run under WINE@.
+
+@strong{Warning:} the @option{-fshort-wchar} switch causes GCC to generate
+code that is not binary compatible with code generated without that switch.
+Use it to conform to a non-default application binary interface.
+
+@item -fcommon
+@opindex fcommon
+@opindex fno-common
+@cindex tentative definitions
+In C code, this option controls the placement of global variables
+defined without an initializer, known as @dfn{tentative definitions}
+in the C standard.  Tentative definitions are distinct from declarations
+of a variable with the @code{extern} keyword, which do not allocate storage.
+
+The default is @option{-fno-common}, which specifies that the compiler places
+uninitialized global variables in the BSS section of the object file.
+This inhibits the merging of tentative definitions by the linker so you get a
+multiple-definition error if the same variable is accidentally defined in more
+than one compilation unit.
+
+The @option{-fcommon} places uninitialized global variables in a common block.
+This allows the linker to resolve all tentative definitions of the same variable
+in different compilation units to the same object, or to a non-tentative
+definition.  This behavior is inconsistent with C++, and on many targets implies
+a speed and code size penalty on global variable references.  It is mainly
+useful to enable legacy code to link without errors.
+
+@item -fno-ident
+@opindex fno-ident
+@opindex fident
+Ignore the @code{#ident} directive.
+
+@item -finhibit-size-directive
+@opindex finhibit-size-directive
+Don't output a @code{.size} assembler directive, or anything else that
+would cause trouble if the function is split in the middle, and the
+two halves are placed at locations far apart in memory.  This option is
+used when compiling @file{crtstuff.c}; you should not need to use it
+for anything else.
+
+@item -fverbose-asm
+@opindex fverbose-asm
+Put extra commentary information in the generated assembly code to
+make it more readable.  This option is generally only of use to those
+who actually need to read the generated assembly code (perhaps while
+debugging the compiler itself).
+
+@option{-fno-verbose-asm}, the default, causes the
+extra information to be omitted and is useful when comparing two assembler
+files.
+
+The added comments include:
+
+@itemize @bullet
+
+@item
+information on the compiler version and command-line options,
+
+@item
+the source code lines associated with the assembly instructions,
+in the form FILENAME:LINENUMBER:CONTENT OF LINE,
+
+@item
+hints on which high-level expressions correspond to
+the various assembly instruction operands.
+
+@end itemize
+
+For example, given this C source file:
+
+@smallexample
+int test (int n)
+@{
+  int i;
+  int total = 0;
+
+  for (i = 0; i < n; i++)
+    total += i * i;
+
+  return total;
+@}
+@end smallexample
+
+compiling to (x86_64) assembly via @option{-S} and emitting the result
+direct to stdout via @option{-o} @option{-}
+
+@smallexample
+gcc -S test.c -fverbose-asm -Os -o -
+@end smallexample
+
+gives output similar to this:
+
+@smallexample
+	.file	"test.c"
+# GNU C11 (GCC) version 7.0.0 20160809 (experimental) (x86_64-pc-linux-gnu)
+  [...snip...]
+# options passed:
+  [...snip...]
+
+	.text
+	.globl	test
+	.type	test, @@function
+test:
+.LFB0:
+	.cfi_startproc
+# test.c:4:   int total = 0;
+	xorl	%eax, %eax	# <retval>
+# test.c:6:   for (i = 0; i < n; i++)
+	xorl	%edx, %edx	# i
+.L2:
+# test.c:6:   for (i = 0; i < n; i++)
+	cmpl	%edi, %edx	# n, i
+	jge	.L5	#,
+# test.c:7:     total += i * i;
+	movl	%edx, %ecx	# i, tmp92
+	imull	%edx, %ecx	# i, tmp92
+# test.c:6:   for (i = 0; i < n; i++)
+	incl	%edx	# i
+# test.c:7:     total += i * i;
+	addl	%ecx, %eax	# tmp92, <retval>
+	jmp	.L2	#
+.L5:
+# test.c:10: @}
+	ret
+	.cfi_endproc
+.LFE0:
+	.size	test, .-test
+	.ident	"GCC: (GNU) 7.0.0 20160809 (experimental)"
+	.section	.note.GNU-stack,"",@@progbits
+@end smallexample
+
+The comments are intended for humans rather than machines and hence the
+precise format of the comments is subject to change.
+
+@item -frecord-gcc-switches
+@opindex frecord-gcc-switches
+This switch causes the command line used to invoke the
+compiler to be recorded into the object file that is being created.
+This switch is only implemented on some targets and the exact format
+of the recording is target and binary file format dependent, but it
+usually takes the form of a section containing ASCII text.  This
+switch is related to the @option{-fverbose-asm} switch, but that
+switch only records information in the assembler output file as
+comments, so it never reaches the object file.
+See also @option{-grecord-gcc-switches} for another
+way of storing compiler options into the object file.
+
+@item -fpic
+@opindex fpic
+@cindex global offset table
+@cindex PIC
+Generate position-independent code (PIC) suitable for use in a shared
+library, if supported for the target machine.  Such code accesses all
+constant addresses through a global offset table (GOT)@.  The dynamic
+loader resolves the GOT entries when the program starts (the dynamic
+loader is not part of GCC; it is part of the operating system).  If
+the GOT size for the linked executable exceeds a machine-specific
+maximum size, you get an error message from the linker indicating that
+@option{-fpic} does not work; in that case, recompile with @option{-fPIC}
+instead.  (These maximums are 8k on the SPARC, 28k on AArch64 and 32k
+on the m68k and RS/6000.  The x86 has no such limit.)
+
+Position-independent code requires special support, and therefore works
+only on certain machines.  For the x86, GCC supports PIC for System V
+but not for the Sun 386i.  Code generated for the IBM RS/6000 is always
+position-independent.
+
+When this flag is set, the macros @code{__pic__} and @code{__PIC__}
+are defined to 1.
+
+@item -fPIC
+@opindex fPIC
+If supported for the target machine, emit position-independent code,
+suitable for dynamic linking and avoiding any limit on the size of the
+global offset table.  This option makes a difference on AArch64, m68k,
+PowerPC and SPARC@.
+
+Position-independent code requires special support, and therefore works
+only on certain machines.
+
+When this flag is set, the macros @code{__pic__} and @code{__PIC__}
+are defined to 2.
+
+@item -fpie
+@itemx -fPIE
+@opindex fpie
+@opindex fPIE
+These options are similar to @option{-fpic} and @option{-fPIC}, but the
+generated position-independent code can be only linked into executables.
+Usually these options are used to compile code that will be linked using
+the @option{-pie} GCC option.
+
+@option{-fpie} and @option{-fPIE} both define the macros
+@code{__pie__} and @code{__PIE__}.  The macros have the value 1
+for @option{-fpie} and 2 for @option{-fPIE}.
+
+@item -fno-plt
+@opindex fno-plt
+@opindex fplt
+Do not use the PLT for external function calls in position-independent code.
+Instead, load the callee address at call sites from the GOT and branch to it.
+This leads to more efficient code by eliminating PLT stubs and exposing
+GOT loads to optimizations.  On architectures such as 32-bit x86 where
+PLT stubs expect the GOT pointer in a specific register, this gives more
+register allocation freedom to the compiler.
+Lazy binding requires use of the PLT; 
+with @option{-fno-plt} all external symbols are resolved at load time.
+
+Alternatively, the function attribute @code{noplt} can be used to avoid calls
+through the PLT for specific external functions.
+
+In position-dependent code, a few targets also convert calls to
+functions that are marked to not use the PLT to use the GOT instead.
+
+@item -fno-jump-tables
+@opindex fno-jump-tables
+@opindex fjump-tables
+Do not use jump tables for switch statements even where it would be
+more efficient than other code generation strategies.  This option is
+of use in conjunction with @option{-fpic} or @option{-fPIC} for
+building code that forms part of a dynamic linker and cannot
+reference the address of a jump table.  On some targets, jump tables
+do not require a GOT and this option is not needed.
+
+@item -fno-bit-tests
+@opindex fno-bit-tests
+@opindex fbit-tests
+Do not use bit tests for switch statements even where it would be
+more efficient than other code generation strategies.
+
+@item -ffixed-@var{reg}
+@opindex ffixed
+Treat the register named @var{reg} as a fixed register; generated code
+should never refer to it (except perhaps as a stack pointer, frame
+pointer or in some other fixed role).
+
+@var{reg} must be the name of a register.  The register names accepted
+are machine-specific and are defined in the @code{REGISTER_NAMES}
+macro in the machine description macro file.
+
+This flag does not have a negative form, because it specifies a
+three-way choice.
+
+@item -fcall-used-@var{reg}
+@opindex fcall-used
+Treat the register named @var{reg} as an allocable register that is
+clobbered by function calls.  It may be allocated for temporaries or
+variables that do not live across a call.  Functions compiled this way
+do not save and restore the register @var{reg}.
+
+It is an error to use this flag with the frame pointer or stack pointer.
+Use of this flag for other registers that have fixed pervasive roles in
+the machine's execution model produces disastrous results.
+
+This flag does not have a negative form, because it specifies a
+three-way choice.
+
+@item -fcall-saved-@var{reg}
+@opindex fcall-saved
+Treat the register named @var{reg} as an allocable register saved by
+functions.  It may be allocated even for temporaries or variables that
+live across a call.  Functions compiled this way save and restore
+the register @var{reg} if they use it.
+
+It is an error to use this flag with the frame pointer or stack pointer.
+Use of this flag for other registers that have fixed pervasive roles in
+the machine's execution model produces disastrous results.
+
+A different sort of disaster results from the use of this flag for
+a register in which function values may be returned.
+
+This flag does not have a negative form, because it specifies a
+three-way choice.
+
+@item -fpack-struct[=@var{n}]
+@opindex fpack-struct
+Without a value specified, pack all structure members together without
+holes.  When a value is specified (which must be a small power of two), pack
+structure members according to this value, representing the maximum
+alignment (that is, objects with default alignment requirements larger than
+this are output potentially unaligned at the next fitting location.
+
+@strong{Warning:} the @option{-fpack-struct} switch causes GCC to generate
+code that is not binary compatible with code generated without that switch.
+Additionally, it makes the code suboptimal.
+Use it to conform to a non-default application binary interface.
+
+@item -fleading-underscore
+@opindex fleading-underscore
+This option and its counterpart, @option{-fno-leading-underscore}, forcibly
+change the way C symbols are represented in the object file.  One use
+is to help link with legacy assembly code.
+
+@strong{Warning:} the @option{-fleading-underscore} switch causes GCC to
+generate code that is not binary compatible with code generated without that
+switch.  Use it to conform to a non-default application binary interface.
+Not all targets provide complete support for this switch.
+
+@item -ftls-model=@var{model}
+@opindex ftls-model
+Alter the thread-local storage model to be used (@pxref{Thread-Local}).
+The @var{model} argument should be one of @samp{global-dynamic},
+@samp{local-dynamic}, @samp{initial-exec} or @samp{local-exec}.
+Note that the choice is subject to optimization: the compiler may use
+a more efficient model for symbols not visible outside of the translation
+unit, or if @option{-fpic} is not given on the command line.
+
+The default without @option{-fpic} is @samp{initial-exec}; with
+@option{-fpic} the default is @samp{global-dynamic}.
+
+@item -ftrampolines
+@opindex ftrampolines
+For targets that normally need trampolines for nested functions, always
+generate them instead of using descriptors.  Otherwise, for targets that
+do not need them, like for example HP-PA or IA-64, do nothing.
+
+A trampoline is a small piece of code that is created at run time on the
+stack when the address of a nested function is taken, and is used to call
+the nested function indirectly.  Therefore, it requires the stack to be
+made executable in order for the program to work properly.
+
+@option{-fno-trampolines} is enabled by default on a language by language
+basis to let the compiler avoid generating them, if it computes that this
+is safe, and replace them with descriptors.  Descriptors are made up of data
+only, but the generated code must be prepared to deal with them.  As of this
+writing, @option{-fno-trampolines} is enabled by default only for Ada.
+
+Moreover, code compiled with @option{-ftrampolines} and code compiled with
+@option{-fno-trampolines} are not binary compatible if nested functions are
+present.  This option must therefore be used on a program-wide basis and be
+manipulated with extreme care.
+
+For languages other than Ada, the @code{-ftrampolines} and
+@code{-fno-trampolines} options currently have no effect, and
+trampolines are always generated on platforms that need them
+for nested functions.
+
+@item -fvisibility=@r{[}default@r{|}internal@r{|}hidden@r{|}protected@r{]}
+@opindex fvisibility
+Set the default ELF image symbol visibility to the specified option---all
+symbols are marked with this unless overridden within the code.
+Using this feature can very substantially improve linking and
+load times of shared object libraries, produce more optimized
+code, provide near-perfect API export and prevent symbol clashes.
+It is @strong{strongly} recommended that you use this in any shared objects
+you distribute.
+
+Despite the nomenclature, @samp{default} always means public; i.e.,
+available to be linked against from outside the shared object.
+@samp{protected} and @samp{internal} are pretty useless in real-world
+usage so the only other commonly used option is @samp{hidden}.
+The default if @option{-fvisibility} isn't specified is
+@samp{default}, i.e., make every symbol public.
+
+A good explanation of the benefits offered by ensuring ELF
+symbols have the correct visibility is given by ``How To Write
+Shared Libraries'' by Ulrich Drepper (which can be found at
+@w{@uref{https://www.akkadia.org/drepper/}})---however a superior
+solution made possible by this option to marking things hidden when
+the default is public is to make the default hidden and mark things
+public.  This is the norm with DLLs on Windows and with @option{-fvisibility=hidden}
+and @code{__attribute__ ((visibility("default")))} instead of
+@code{__declspec(dllexport)} you get almost identical semantics with
+identical syntax.  This is a great boon to those working with
+cross-platform projects.
+
+For those adding visibility support to existing code, you may find
+@code{#pragma GCC visibility} of use.  This works by you enclosing
+the declarations you wish to set visibility for with (for example)
+@code{#pragma GCC visibility push(hidden)} and
+@code{#pragma GCC visibility pop}.
+Bear in mind that symbol visibility should be viewed @strong{as
+part of the API interface contract} and thus all new code should
+always specify visibility when it is not the default; i.e., declarations
+only for use within the local DSO should @strong{always} be marked explicitly
+as hidden as so to avoid PLT indirection overheads---making this
+abundantly clear also aids readability and self-documentation of the code.
+Note that due to ISO C++ specification requirements, @code{operator new} and
+@code{operator delete} must always be of default visibility.
+
+Be aware that headers from outside your project, in particular system
+headers and headers from any other library you use, may not be
+expecting to be compiled with visibility other than the default.  You
+may need to explicitly say @code{#pragma GCC visibility push(default)}
+before including any such headers.
+
+@code{extern} declarations are not affected by @option{-fvisibility}, so
+a lot of code can be recompiled with @option{-fvisibility=hidden} with
+no modifications.  However, this means that calls to @code{extern}
+functions with no explicit visibility use the PLT, so it is more
+effective to use @code{__attribute ((visibility))} and/or
+@code{#pragma GCC visibility} to tell the compiler which @code{extern}
+declarations should be treated as hidden.
+
+Note that @option{-fvisibility} does affect C++ vague linkage
+entities. This means that, for instance, an exception class that is
+be thrown between DSOs must be explicitly marked with default
+visibility so that the @samp{type_info} nodes are unified between
+the DSOs.
+
+An overview of these techniques, their benefits and how to use them
+is at @uref{https://gcc.gnu.org/@/wiki/@/Visibility}.
+
+@item -fstrict-volatile-bitfields
+@opindex fstrict-volatile-bitfields
+This option should be used if accesses to volatile bit-fields (or other
+structure fields, although the compiler usually honors those types
+anyway) should use a single access of the width of the
+field's type, aligned to a natural alignment if possible.  For
+example, targets with memory-mapped peripheral registers might require
+all such accesses to be 16 bits wide; with this flag you can
+declare all peripheral bit-fields as @code{unsigned short} (assuming short
+is 16 bits on these targets) to force GCC to use 16-bit accesses
+instead of, perhaps, a more efficient 32-bit access.
+
+If this option is disabled, the compiler uses the most efficient
+instruction.  In the previous example, that might be a 32-bit load
+instruction, even though that accesses bytes that do not contain
+any portion of the bit-field, or memory-mapped registers unrelated to
+the one being updated.
+
+In some cases, such as when the @code{packed} attribute is applied to a 
+structure field, it may not be possible to access the field with a single
+read or write that is correctly aligned for the target machine.  In this
+case GCC falls back to generating multiple accesses rather than code that 
+will fault or truncate the result at run time.
+
+Note:  Due to restrictions of the C/C++11 memory model, write accesses are
+not allowed to touch non bit-field members.  It is therefore recommended
+to define all bits of the field's type as bit-field members.
+
+The default value of this option is determined by the application binary
+interface for the target processor.
+
+@item -fsync-libcalls
+@opindex fsync-libcalls
+This option controls whether any out-of-line instance of the @code{__sync}
+family of functions may be used to implement the C++11 @code{__atomic}
+family of functions.
+
+The default value of this option is enabled, thus the only useful form
+of the option is @option{-fno-sync-libcalls}.  This option is used in
+the implementation of the @file{libatomic} runtime library.
+
+@end table
+
+@node Developer Options
+@section GCC Developer Options
+@cindex developer options
+@cindex debugging GCC
+@cindex debug dump options
+@cindex dump options
+@cindex compilation statistics
+
+This section describes command-line options that are primarily of
+interest to GCC developers, including options to support compiler
+testing and investigation of compiler bugs and compile-time
+performance problems.  This includes options that produce debug dumps
+at various points in the compilation; that print statistics such as
+memory use and execution time; and that print information about GCC's
+configuration, such as where it searches for libraries.  You should
+rarely need to use any of these options for ordinary compilation and
+linking tasks.
+
+Many developer options that cause GCC to dump output to a file take an
+optional @samp{=@var{filename}} suffix. You can specify @samp{stdout}
+or @samp{-} to dump to standard output, and @samp{stderr} for standard
+error.
+
+If @samp{=@var{filename}} is omitted, a default dump file name is
+constructed by concatenating the base dump file name, a pass number,
+phase letter, and pass name.  The base dump file name is the name of
+output file produced by the compiler if explicitly specified and not
+an executable; otherwise it is the source file name.
+The pass number is determined by the order passes are registered with
+the compiler's pass manager. 
+This is generally the same as the order of execution, but passes
+registered by plugins, target-specific passes, or passes that are
+otherwise registered late are numbered higher than the pass named
+@samp{final}, even if they are executed earlier.  The phase letter is
+one of @samp{i} (inter-procedural analysis), @samp{l}
+(language-specific), @samp{r} (RTL), or @samp{t} (tree). 
+The files are created in the directory of the output file. 
+
+@table @gcctabopt
+
+@item -fcallgraph-info
+@itemx -fcallgraph-info=@var{MARKERS}
+@opindex fcallgraph-info
+Makes the compiler output callgraph information for the program, on a
+per-object-file basis.  The information is generated in the common VCG
+format.  It can be decorated with additional, per-node and/or per-edge
+information, if a list of comma-separated markers is additionally
+specified.  When the @code{su} marker is specified, the callgraph is
+decorated with stack usage information; it is equivalent to
+@option{-fstack-usage}.  When the @code{da} marker is specified, the
+callgraph is decorated with information about dynamically allocated
+objects.
+
+When compiling with @option{-flto}, no callgraph information is output
+along with the object file.  At LTO link time, @option{-fcallgraph-info}
+may generate multiple callgraph information files next to intermediate
+LTO output files.
+
+@item -d@var{letters}
+@itemx -fdump-rtl-@var{pass}
+@itemx -fdump-rtl-@var{pass}=@var{filename}
+@opindex d
+@opindex fdump-rtl-@var{pass}
+Says to make debugging dumps during compilation at times specified by
+@var{letters}.  This is used for debugging the RTL-based passes of the
+compiler.
+
+Some @option{-d@var{letters}} switches have different meaning when
+@option{-E} is used for preprocessing.  @xref{Preprocessor Options},
+for information about preprocessor-specific dump options.
+
+Debug dumps can be enabled with a @option{-fdump-rtl} switch or some
+@option{-d} option @var{letters}.  Here are the possible
+letters for use in @var{pass} and @var{letters}, and their meanings:
+
+@table @gcctabopt
+
+@item -fdump-rtl-alignments
+@opindex fdump-rtl-alignments
+Dump after branch alignments have been computed.
+
+@item -fdump-rtl-asmcons
+@opindex fdump-rtl-asmcons
+Dump after fixing rtl statements that have unsatisfied in/out constraints.
+
+@item -fdump-rtl-auto_inc_dec
+@opindex fdump-rtl-auto_inc_dec
+Dump after auto-inc-dec discovery.  This pass is only run on
+architectures that have auto inc or auto dec instructions.
+
+@item -fdump-rtl-barriers
+@opindex fdump-rtl-barriers
+Dump after cleaning up the barrier instructions.
+
+@item -fdump-rtl-bbpart
+@opindex fdump-rtl-bbpart
+Dump after partitioning hot and cold basic blocks.
+
+@item -fdump-rtl-bbro
+@opindex fdump-rtl-bbro
+Dump after block reordering.
+
+@item -fdump-rtl-btl1
+@itemx -fdump-rtl-btl2
+@opindex fdump-rtl-btl2
+@opindex fdump-rtl-btl2
+@option{-fdump-rtl-btl1} and @option{-fdump-rtl-btl2} enable dumping
+after the two branch
+target load optimization passes.
+
+@item -fdump-rtl-bypass
+@opindex fdump-rtl-bypass
+Dump after jump bypassing and control flow optimizations.
+
+@item -fdump-rtl-combine
+@opindex fdump-rtl-combine
+Dump after the RTL instruction combination pass.
+
+@item -fdump-rtl-compgotos
+@opindex fdump-rtl-compgotos
+Dump after duplicating the computed gotos.
+
+@item -fdump-rtl-ce1
+@itemx -fdump-rtl-ce2
+@itemx -fdump-rtl-ce3
+@opindex fdump-rtl-ce1
+@opindex fdump-rtl-ce2
+@opindex fdump-rtl-ce3
+@option{-fdump-rtl-ce1}, @option{-fdump-rtl-ce2}, and
+@option{-fdump-rtl-ce3} enable dumping after the three
+if conversion passes.
+
+@item -fdump-rtl-cprop_hardreg
+@opindex fdump-rtl-cprop_hardreg
+Dump after hard register copy propagation.
+
+@item -fdump-rtl-csa
+@opindex fdump-rtl-csa
+Dump after combining stack adjustments.
+
+@item -fdump-rtl-cse1
+@itemx -fdump-rtl-cse2
+@opindex fdump-rtl-cse1
+@opindex fdump-rtl-cse2
+@option{-fdump-rtl-cse1} and @option{-fdump-rtl-cse2} enable dumping after
+the two common subexpression elimination passes.
+
+@item -fdump-rtl-dce
+@opindex fdump-rtl-dce
+Dump after the standalone dead code elimination passes.
+
+@item -fdump-rtl-dbr
+@opindex fdump-rtl-dbr
+Dump after delayed branch scheduling.
+
+@item -fdump-rtl-dce1
+@itemx -fdump-rtl-dce2
+@opindex fdump-rtl-dce1
+@opindex fdump-rtl-dce2
+@option{-fdump-rtl-dce1} and @option{-fdump-rtl-dce2} enable dumping after
+the two dead store elimination passes.
+
+@item -fdump-rtl-eh
+@opindex fdump-rtl-eh
+Dump after finalization of EH handling code.
+
+@item -fdump-rtl-eh_ranges
+@opindex fdump-rtl-eh_ranges
+Dump after conversion of EH handling range regions.
+
+@item -fdump-rtl-expand
+@opindex fdump-rtl-expand
+Dump after RTL generation.
+
+@item -fdump-rtl-fwprop1
+@itemx -fdump-rtl-fwprop2
+@opindex fdump-rtl-fwprop1
+@opindex fdump-rtl-fwprop2
+@option{-fdump-rtl-fwprop1} and @option{-fdump-rtl-fwprop2} enable
+dumping after the two forward propagation passes.
+
+@item -fdump-rtl-gcse1
+@itemx -fdump-rtl-gcse2
+@opindex fdump-rtl-gcse1
+@opindex fdump-rtl-gcse2
+@option{-fdump-rtl-gcse1} and @option{-fdump-rtl-gcse2} enable dumping
+after global common subexpression elimination.
+
+@item -fdump-rtl-init-regs
+@opindex fdump-rtl-init-regs
+Dump after the initialization of the registers.
+
+@item -fdump-rtl-initvals
+@opindex fdump-rtl-initvals
+Dump after the computation of the initial value sets.
+
+@item -fdump-rtl-into_cfglayout
+@opindex fdump-rtl-into_cfglayout
+Dump after converting to cfglayout mode.
+
+@item -fdump-rtl-ira
+@opindex fdump-rtl-ira
+Dump after iterated register allocation.
+
+@item -fdump-rtl-jump
+@opindex fdump-rtl-jump
+Dump after the second jump optimization.
+
+@item -fdump-rtl-loop2
+@opindex fdump-rtl-loop2
+@option{-fdump-rtl-loop2} enables dumping after the rtl
+loop optimization passes.
+
+@item -fdump-rtl-mach
+@opindex fdump-rtl-mach
+Dump after performing the machine dependent reorganization pass, if that
+pass exists.
+
+@item -fdump-rtl-mode_sw
+@opindex fdump-rtl-mode_sw
+Dump after removing redundant mode switches.
+
+@item -fdump-rtl-rnreg
+@opindex fdump-rtl-rnreg
+Dump after register renumbering.
+
+@item -fdump-rtl-outof_cfglayout
+@opindex fdump-rtl-outof_cfglayout
+Dump after converting from cfglayout mode.
+
+@item -fdump-rtl-peephole2
+@opindex fdump-rtl-peephole2
+Dump after the peephole pass.
+
+@item -fdump-rtl-postreload
+@opindex fdump-rtl-postreload
+Dump after post-reload optimizations.
+
+@item -fdump-rtl-pro_and_epilogue
+@opindex fdump-rtl-pro_and_epilogue
+Dump after generating the function prologues and epilogues.
+
+@item -fdump-rtl-sched1
+@itemx -fdump-rtl-sched2
+@opindex fdump-rtl-sched1
+@opindex fdump-rtl-sched2
+@option{-fdump-rtl-sched1} and @option{-fdump-rtl-sched2} enable dumping
+after the basic block scheduling passes.
+
+@item -fdump-rtl-ree
+@opindex fdump-rtl-ree
+Dump after sign/zero extension elimination.
+
+@item -fdump-rtl-seqabstr
+@opindex fdump-rtl-seqabstr
+Dump after common sequence discovery.
+
+@item -fdump-rtl-shorten
+@opindex fdump-rtl-shorten
+Dump after shortening branches.
+
+@item -fdump-rtl-sibling
+@opindex fdump-rtl-sibling
+Dump after sibling call optimizations.
+
+@item -fdump-rtl-split1
+@itemx -fdump-rtl-split2
+@itemx -fdump-rtl-split3
+@itemx -fdump-rtl-split4
+@itemx -fdump-rtl-split5
+@opindex fdump-rtl-split1
+@opindex fdump-rtl-split2
+@opindex fdump-rtl-split3
+@opindex fdump-rtl-split4
+@opindex fdump-rtl-split5
+These options enable dumping after five rounds of
+instruction splitting.
+
+@item -fdump-rtl-sms
+@opindex fdump-rtl-sms
+Dump after modulo scheduling.  This pass is only run on some
+architectures.
+
+@item -fdump-rtl-stack
+@opindex fdump-rtl-stack
+Dump after conversion from GCC's ``flat register file'' registers to the
+x87's stack-like registers.  This pass is only run on x86 variants.
+
+@item -fdump-rtl-subreg1
+@itemx -fdump-rtl-subreg2
+@opindex fdump-rtl-subreg1
+@opindex fdump-rtl-subreg2
+@option{-fdump-rtl-subreg1} and @option{-fdump-rtl-subreg2} enable dumping after
+the two subreg expansion passes.
+
+@item -fdump-rtl-unshare
+@opindex fdump-rtl-unshare
+Dump after all rtl has been unshared.
+
+@item -fdump-rtl-vartrack
+@opindex fdump-rtl-vartrack
+Dump after variable tracking.
+
+@item -fdump-rtl-vregs
+@opindex fdump-rtl-vregs
+Dump after converting virtual registers to hard registers.
+
+@item -fdump-rtl-web
+@opindex fdump-rtl-web
+Dump after live range splitting.
+
+@item -fdump-rtl-regclass
+@itemx -fdump-rtl-subregs_of_mode_init
+@itemx -fdump-rtl-subregs_of_mode_finish
+@itemx -fdump-rtl-dfinit
+@itemx -fdump-rtl-dfinish
+@opindex fdump-rtl-regclass
+@opindex fdump-rtl-subregs_of_mode_init
+@opindex fdump-rtl-subregs_of_mode_finish
+@opindex fdump-rtl-dfinit
+@opindex fdump-rtl-dfinish
+These dumps are defined but always produce empty files.
+
+@item -da
+@itemx -fdump-rtl-all
+@opindex da
+@opindex fdump-rtl-all
+Produce all the dumps listed above.
+
+@item -dA
+@opindex dA
+Annotate the assembler output with miscellaneous debugging information.
+
+@item -dD
+@opindex dD
+Dump all macro definitions, at the end of preprocessing, in addition to
+normal output.
+
+@item -dH
+@opindex dH
+Produce a core dump whenever an error occurs.
+
+@item -dp
+@opindex dp
+Annotate the assembler output with a comment indicating which
+pattern and alternative is used.  The length and cost of each instruction are
+also printed.
+
+@item -dP
+@opindex dP
+Dump the RTL in the assembler output as a comment before each instruction.
+Also turns on @option{-dp} annotation.
+
+@item -dx
+@opindex dx
+Just generate RTL for a function instead of compiling it.  Usually used
+with @option{-fdump-rtl-expand}.
+@end table
+
+@item -fdump-debug
+@opindex fdump-debug
+Dump debugging information generated during the debug
+generation phase.
+
+@item -fdump-earlydebug
+@opindex fdump-earlydebug
+Dump debugging information generated during the early debug
+generation phase.
+
+@item -fdump-noaddr
+@opindex fdump-noaddr
+When doing debugging dumps, suppress address output.  This makes it more
+feasible to use diff on debugging dumps for compiler invocations with
+different compiler binaries and/or different
+text / bss / data / heap / stack / dso start locations.
+
+@item -freport-bug
+@opindex freport-bug
+Collect and dump debug information into a temporary file if an
+internal compiler error (ICE) occurs.
+
+@item -fdump-unnumbered
+@opindex fdump-unnumbered
+When doing debugging dumps, suppress instruction numbers and address output.
+This makes it more feasible to use diff on debugging dumps for compiler
+invocations with different options, in particular with and without
+@option{-g}.
+
+@item -fdump-unnumbered-links
+@opindex fdump-unnumbered-links
+When doing debugging dumps (see @option{-d} option above), suppress
+instruction numbers for the links to the previous and next instructions
+in a sequence.
+
+@item -fdump-ipa-@var{switch}
+@itemx -fdump-ipa-@var{switch}-@var{options}
+@opindex fdump-ipa
+Control the dumping at various stages of inter-procedural analysis
+language tree to a file.  The file name is generated by appending a
+switch specific suffix to the source file name, and the file is created
+in the same directory as the output file.  The following dumps are
+possible:
+
+@table @samp
+@item all
+Enables all inter-procedural analysis dumps.
+
+@item cgraph
+Dumps information about call-graph optimization, unused function removal,
+and inlining decisions.
+
+@item inline
+Dump after function inlining.
+
+@end table
+
+Additionally, the options @option{-optimized}, @option{-missed},
+@option{-note}, and @option{-all} can be provided, with the same meaning
+as for @option{-fopt-info}, defaulting to @option{-optimized}.
+
+For example, @option{-fdump-ipa-inline-optimized-missed} will emit
+information on callsites that were inlined, along with callsites
+that were not inlined.
+
+By default, the dump will contain messages about successful
+optimizations (equivalent to @option{-optimized}) together with
+low-level details about the analysis.
+
+@item -fdump-lang
+@opindex fdump-lang
+Dump language-specific information.  The file name is made by appending
+@file{.lang} to the source file name.
+
+@item -fdump-lang-all
+@itemx -fdump-lang-@var{switch}
+@itemx -fdump-lang-@var{switch}-@var{options}
+@itemx -fdump-lang-@var{switch}-@var{options}=@var{filename}
+@opindex fdump-lang-all
+@opindex fdump-lang
+Control the dumping of language-specific information.  The @var{options}
+and @var{filename} portions behave as described in the
+@option{-fdump-tree} option.  The following @var{switch} values are
+accepted:
+
+@table @samp
+@item all
+
+Enable all language-specific dumps.
+
+@item class
+Dump class hierarchy information.  Virtual table information is emitted
+unless '@option{slim}' is specified.  This option is applicable to C++ only.
+
+@item module
+Dump module information.  Options @option{lineno} (locations),
+@option{graph} (reachability), @option{blocks} (clusters),
+@option{uid} (serialization), @option{alias} (mergeable),
+@option{asmname} (Elrond), @option{eh} (mapper) & @option{vops}
+(macros) may provide additional information.  This option is
+applicable to C++ only.
+
+@item raw
+Dump the raw internal tree data.  This option is applicable to C++ only.
+
+@end table
+
+@item -fdump-passes
+@opindex fdump-passes
+Print on @file{stderr} the list of optimization passes that are turned
+on and off by the current command-line options.
+
+@item -fdump-statistics-@var{option}
+@opindex fdump-statistics
+Enable and control dumping of pass statistics in a separate file.  The
+file name is generated by appending a suffix ending in
+@samp{.statistics} to the source file name, and the file is created in
+the same directory as the output file.  If the @samp{-@var{option}}
+form is used, @samp{-stats} causes counters to be summed over the
+whole compilation unit while @samp{-details} dumps every event as
+the passes generate them.  The default with no option is to sum
+counters for each function compiled.
+
+@item -fdump-tree-all
+@itemx -fdump-tree-@var{switch}
+@itemx -fdump-tree-@var{switch}-@var{options}
+@itemx -fdump-tree-@var{switch}-@var{options}=@var{filename}
+@opindex fdump-tree-all
+@opindex fdump-tree
+Control the dumping at various stages of processing the intermediate
+language tree to a file.  If the @samp{-@var{options}}
+form is used, @var{options} is a list of @samp{-} separated options
+which control the details of the dump.  Not all options are applicable
+to all dumps; those that are not meaningful are ignored.  The
+following options are available
+
+@table @samp
+@item address
+Print the address of each node.  Usually this is not meaningful as it
+changes according to the environment and source file.  Its primary use
+is for tying up a dump file with a debug environment.
+@item asmname
+If @code{DECL_ASSEMBLER_NAME} has been set for a given decl, use that
+in the dump instead of @code{DECL_NAME}.  Its primary use is ease of
+use working backward from mangled names in the assembly file.
+@item slim
+When dumping front-end intermediate representations, inhibit dumping
+of members of a scope or body of a function merely because that scope
+has been reached.  Only dump such items when they are directly reachable
+by some other path.
+
+When dumping pretty-printed trees, this option inhibits dumping the
+bodies of control structures.
+
+When dumping RTL, print the RTL in slim (condensed) form instead of
+the default LISP-like representation.
+@item raw
+Print a raw representation of the tree.  By default, trees are
+pretty-printed into a C-like representation.
+@item details
+Enable more detailed dumps (not honored by every dump option). Also
+include information from the optimization passes.
+@item stats
+Enable dumping various statistics about the pass (not honored by every dump
+option).
+@item blocks
+Enable showing basic block boundaries (disabled in raw dumps).
+@item graph
+For each of the other indicated dump files (@option{-fdump-rtl-@var{pass}}),
+dump a representation of the control flow graph suitable for viewing with
+GraphViz to @file{@var{file}.@var{passid}.@var{pass}.dot}.  Each function in
+the file is pretty-printed as a subgraph, so that GraphViz can render them
+all in a single plot.
+
+This option currently only works for RTL dumps, and the RTL is always
+dumped in slim form.
+@item vops
+Enable showing virtual operands for every statement.
+@item lineno
+Enable showing line numbers for statements.
+@item uid
+Enable showing the unique ID (@code{DECL_UID}) for each variable.
+@item verbose
+Enable showing the tree dump for each statement.
+@item eh
+Enable showing the EH region number holding each statement.
+@item scev
+Enable showing scalar evolution analysis details.
+@item optimized
+Enable showing optimization information (only available in certain
+passes).
+@item missed
+Enable showing missed optimization information (only available in certain
+passes).
+@item note
+Enable other detailed optimization information (only available in
+certain passes).
+@item all
+Turn on all options, except @option{raw}, @option{slim}, @option{verbose}
+and @option{lineno}.
+@item optall
+Turn on all optimization options, i.e., @option{optimized},
+@option{missed}, and @option{note}.
+@end table
+
+To determine what tree dumps are available or find the dump for a pass
+of interest follow the steps below.
+
+@enumerate
+@item
+Invoke GCC with @option{-fdump-passes} and in the @file{stderr} output
+look for a code that corresponds to the pass you are interested in.
+For example, the codes @code{tree-evrp}, @code{tree-vrp1}, and
+@code{tree-vrp2} correspond to the three Value Range Propagation passes.
+The number at the end distinguishes distinct invocations of the same pass.
+@item
+To enable the creation of the dump file, append the pass code to
+the @option{-fdump-} option prefix and invoke GCC with it.  For example,
+to enable the dump from the Early Value Range Propagation pass, invoke
+GCC with the @option{-fdump-tree-evrp} option.  Optionally, you may
+specify the name of the dump file.  If you don't specify one, GCC
+creates as described below.
+@item
+Find the pass dump in a file whose name is composed of three components
+separated by a period: the name of the source file GCC was invoked to
+compile, a numeric suffix indicating the pass number followed by the
+letter @samp{t} for tree passes (and the letter @samp{r} for RTL passes),
+and finally the pass code.  For example, the Early VRP pass dump might
+be in a file named @file{myfile.c.038t.evrp} in the current working
+directory.  Note that the numeric codes are not stable and may change
+from one version of GCC to another.
+@end enumerate
+
+@item -fopt-info
+@itemx -fopt-info-@var{options}
+@itemx -fopt-info-@var{options}=@var{filename}
+@opindex fopt-info
+Controls optimization dumps from various optimization passes. If the
+@samp{-@var{options}} form is used, @var{options} is a list of
+@samp{-} separated option keywords to select the dump details and
+optimizations.  
+
+The @var{options} can be divided into three groups:
+@enumerate
+@item
+options describing what kinds of messages should be emitted,
+@item
+options describing the verbosity of the dump, and
+@item
+options describing which optimizations should be included.
+@end enumerate
+The options from each group can be freely mixed as they are
+non-overlapping. However, in case of any conflicts,
+the later options override the earlier options on the command
+line. 
+
+The following options control which kinds of messages should be emitted:
+
+@table @samp
+@item optimized
+Print information when an optimization is successfully applied. It is
+up to a pass to decide which information is relevant. For example, the
+vectorizer passes print the source location of loops which are
+successfully vectorized.
+@item missed
+Print information about missed optimizations. Individual passes
+control which information to include in the output. 
+@item note
+Print verbose information about optimizations, such as certain
+transformations, more detailed messages about decisions etc.
+@item all
+Print detailed optimization information. This includes
+@samp{optimized}, @samp{missed}, and @samp{note}.
+@end table
+
+The following option controls the dump verbosity:
+
+@table @samp
+@item internals
+By default, only ``high-level'' messages are emitted. This option enables
+additional, more detailed, messages, which are likely to only be of interest
+to GCC developers.
+@end table
+
+One or more of the following option keywords can be used to describe a
+group of optimizations:
+
+@table @samp
+@item ipa
+Enable dumps from all interprocedural optimizations.
+@item loop
+Enable dumps from all loop optimizations.
+@item inline
+Enable dumps from all inlining optimizations.
+@item omp
+Enable dumps from all OMP (Offloading and Multi Processing) optimizations.
+@item vec
+Enable dumps from all vectorization optimizations.
+@item optall
+Enable dumps from all optimizations. This is a superset of
+the optimization groups listed above.
+@end table
+
+If @var{options} is
+omitted, it defaults to @samp{optimized-optall}, which means to dump messages
+about successful optimizations from all the passes, omitting messages
+that are treated as ``internals''.
+
+If the @var{filename} is provided, then the dumps from all the
+applicable optimizations are concatenated into the @var{filename}.
+Otherwise the dump is output onto @file{stderr}. Though multiple
+@option{-fopt-info} options are accepted, only one of them can include
+a @var{filename}. If other filenames are provided then all but the
+first such option are ignored.
+
+Note that the output @var{filename} is overwritten
+in case of multiple translation units. If a combined output from
+multiple translation units is desired, @file{stderr} should be used
+instead.
+
+In the following example, the optimization info is output to
+@file{stderr}:
+
+@smallexample
+gcc -O3 -fopt-info
+@end smallexample
+
+This example:
+@smallexample
+gcc -O3 -fopt-info-missed=missed.all
+@end smallexample
+
+@noindent
+outputs missed optimization report from all the passes into
+@file{missed.all}, and this one:
+
+@smallexample
+gcc -O2 -ftree-vectorize -fopt-info-vec-missed
+@end smallexample
+
+@noindent
+prints information about missed optimization opportunities from
+vectorization passes on @file{stderr}.  
+Note that @option{-fopt-info-vec-missed} is equivalent to 
+@option{-fopt-info-missed-vec}.  The order of the optimization group
+names and message types listed after @option{-fopt-info} does not matter.
+
+As another example,
+@smallexample
+gcc -O3 -fopt-info-inline-optimized-missed=inline.txt
+@end smallexample
+
+@noindent
+outputs information about missed optimizations as well as
+optimized locations from all the inlining passes into
+@file{inline.txt}.
+
+Finally, consider:
+
+@smallexample
+gcc -fopt-info-vec-missed=vec.miss -fopt-info-loop-optimized=loop.opt
+@end smallexample
+
+@noindent
+Here the two output filenames @file{vec.miss} and @file{loop.opt} are
+in conflict since only one output file is allowed. In this case, only
+the first option takes effect and the subsequent options are
+ignored. Thus only @file{vec.miss} is produced which contains
+dumps from the vectorizer about missed opportunities.
+
+@item -fsave-optimization-record
+@opindex fsave-optimization-record
+Write a SRCFILE.opt-record.json.gz file detailing what optimizations
+were performed, for those optimizations that support @option{-fopt-info}.
+
+This option is experimental and the format of the data within the
+compressed JSON file is subject to change.
+
+It is roughly equivalent to a machine-readable version of
+@option{-fopt-info-all}, as a collection of messages with source file,
+line number and column number, with the following additional data for
+each message:
+
+@itemize @bullet
+
+@item
+the execution count of the code being optimized, along with metadata about
+whether this was from actual profile data, or just an estimate, allowing
+consumers to prioritize messages by code hotness,
+
+@item
+the function name of the code being optimized, where applicable,
+
+@item
+the ``inlining chain'' for the code being optimized, so that when
+a function is inlined into several different places (which might
+themselves be inlined), the reader can distinguish between the copies,
+
+@item
+objects identifying those parts of the message that refer to expressions,
+statements or symbol-table nodes, which of these categories they are, and,
+when available, their source code location,
+
+@item
+the GCC pass that emitted the message, and
+
+@item
+the location in GCC's own code from which the message was emitted
+
+@end itemize
+
+Additionally, some messages are logically nested within other
+messages, reflecting implementation details of the optimization
+passes.
+
+@item -fsched-verbose=@var{n}
+@opindex fsched-verbose
+On targets that use instruction scheduling, this option controls the
+amount of debugging output the scheduler prints to the dump files.
+
+For @var{n} greater than zero, @option{-fsched-verbose} outputs the
+same information as @option{-fdump-rtl-sched1} and @option{-fdump-rtl-sched2}.
+For @var{n} greater than one, it also output basic block probabilities,
+detailed ready list information and unit/insn info.  For @var{n} greater
+than two, it includes RTL at abort point, control-flow and regions info.
+And for @var{n} over four, @option{-fsched-verbose} also includes
+dependence info.
+
+
+
+@item -fenable-@var{kind}-@var{pass}
+@itemx -fdisable-@var{kind}-@var{pass}=@var{range-list}
+@opindex fdisable-
+@opindex fenable-
+
+This is a set of options that are used to explicitly disable/enable
+optimization passes.  These options are intended for use for debugging GCC.
+Compiler users should use regular options for enabling/disabling
+passes instead.
+
+@table @gcctabopt
+
+@item -fdisable-ipa-@var{pass}
+Disable IPA pass @var{pass}. @var{pass} is the pass name.  If the same pass is
+statically invoked in the compiler multiple times, the pass name should be
+appended with a sequential number starting from 1.
+
+@item -fdisable-rtl-@var{pass}
+@itemx -fdisable-rtl-@var{pass}=@var{range-list}
+Disable RTL pass @var{pass}.  @var{pass} is the pass name.  If the same pass is
+statically invoked in the compiler multiple times, the pass name should be
+appended with a sequential number starting from 1.  @var{range-list} is a 
+comma-separated list of function ranges or assembler names.  Each range is a number
+pair separated by a colon.  The range is inclusive in both ends.  If the range
+is trivial, the number pair can be simplified as a single number.  If the
+function's call graph node's @var{uid} falls within one of the specified ranges,
+the @var{pass} is disabled for that function.  The @var{uid} is shown in the
+function header of a dump file, and the pass names can be dumped by using
+option @option{-fdump-passes}.
+
+@item -fdisable-tree-@var{pass}
+@itemx -fdisable-tree-@var{pass}=@var{range-list}
+Disable tree pass @var{pass}.  See @option{-fdisable-rtl} for the description of
+option arguments.
+
+@item -fenable-ipa-@var{pass}
+Enable IPA pass @var{pass}.  @var{pass} is the pass name.  If the same pass is
+statically invoked in the compiler multiple times, the pass name should be
+appended with a sequential number starting from 1.
+
+@item -fenable-rtl-@var{pass}
+@itemx -fenable-rtl-@var{pass}=@var{range-list}
+Enable RTL pass @var{pass}.  See @option{-fdisable-rtl} for option argument
+description and examples.
+
+@item -fenable-tree-@var{pass}
+@itemx -fenable-tree-@var{pass}=@var{range-list}
+Enable tree pass @var{pass}.  See @option{-fdisable-rtl} for the description
+of option arguments.
+
+@end table
+
+Here are some examples showing uses of these options.
+
+@smallexample
+
+# disable ccp1 for all functions
+   -fdisable-tree-ccp1
+# disable complete unroll for function whose cgraph node uid is 1
+   -fenable-tree-cunroll=1
+# disable gcse2 for functions at the following ranges [1,1],
+# [300,400], and [400,1000]
+# disable gcse2 for functions foo and foo2
+   -fdisable-rtl-gcse2=foo,foo2
+# disable early inlining
+   -fdisable-tree-einline
+# disable ipa inlining
+   -fdisable-ipa-inline
+# enable tree full unroll
+   -fenable-tree-unroll
+
+@end smallexample
+
+@item -fchecking
+@itemx -fchecking=@var{n}
+@opindex fchecking
+@opindex fno-checking
+Enable internal consistency checking.  The default depends on
+the compiler configuration.  @option{-fchecking=2} enables further
+internal consistency checking that might affect code generation.
+
+@item -frandom-seed=@var{string}
+@opindex frandom-seed
+This option provides a seed that GCC uses in place of
+random numbers in generating certain symbol names
+that have to be different in every compiled file.  It is also used to
+place unique stamps in coverage data files and the object files that
+produce them.  You can use the @option{-frandom-seed} option to produce
+reproducibly identical object files.
+
+The @var{string} can either be a number (decimal, octal or hex) or an
+arbitrary string (in which case it's converted to a number by
+computing CRC32).
+
+The @var{string} should be different for every file you compile.
+
+@item -save-temps
+@opindex save-temps
+Store the usual ``temporary'' intermediate files permanently; name them
+as auxiliary output files, as specified described under
+@option{-dumpbase} and @option{-dumpdir}.
+
+When used in combination with the @option{-x} command-line option,
+@option{-save-temps} is sensible enough to avoid overwriting an
+input source file with the same extension as an intermediate file.
+The corresponding intermediate file may be obtained by renaming the
+source file before using @option{-save-temps}.
+
+@item -save-temps=cwd
+@opindex save-temps=cwd
+Equivalent to @option{-save-temps -dumpdir ./}.
+
+@item -save-temps=obj
+@opindex save-temps=obj
+Equivalent to @option{-save-temps -dumpdir @file{outdir/}}, where
+@file{outdir/} is the directory of the output file specified after the
+@option{-o} option, including any directory separators.  If the
+@option{-o} option is not used, the @option{-save-temps=obj} switch
+behaves like @option{-save-temps=cwd}.
+
+@item -time@r{[}=@var{file}@r{]}
+@opindex time
+Report the CPU time taken by each subprocess in the compilation
+sequence.  For C source files, this is the compiler proper and assembler
+(plus the linker if linking is done).
+
+Without the specification of an output file, the output looks like this:
+
+@smallexample
+# cc1 0.12 0.01
+# as 0.00 0.01
+@end smallexample
+
+The first number on each line is the ``user time'', that is time spent
+executing the program itself.  The second number is ``system time'',
+time spent executing operating system routines on behalf of the program.
+Both numbers are in seconds.
+
+With the specification of an output file, the output is appended to the
+named file, and it looks like this:
+
+@smallexample
+0.12 0.01 cc1 @var{options}
+0.00 0.01 as @var{options}
+@end smallexample
+
+The ``user time'' and the ``system time'' are moved before the program
+name, and the options passed to the program are displayed, so that one
+can later tell what file was being compiled, and with which options.
+
+@item -fdump-final-insns@r{[}=@var{file}@r{]}
+@opindex fdump-final-insns
+Dump the final internal representation (RTL) to @var{file}.  If the
+optional argument is omitted (or if @var{file} is @code{.}), the name
+of the dump file is determined by appending @code{.gkd} to the
+dump base name, see @option{-dumpbase}.
+
+@item -fcompare-debug@r{[}=@var{opts}@r{]}
+@opindex fcompare-debug
+@opindex fno-compare-debug
+If no error occurs during compilation, run the compiler a second time,
+adding @var{opts} and @option{-fcompare-debug-second} to the arguments
+passed to the second compilation.  Dump the final internal
+representation in both compilations, and print an error if they differ.
+
+If the equal sign is omitted, the default @option{-gtoggle} is used.
+
+The environment variable @env{GCC_COMPARE_DEBUG}, if defined, non-empty
+and nonzero, implicitly enables @option{-fcompare-debug}.  If
+@env{GCC_COMPARE_DEBUG} is defined to a string starting with a dash,
+then it is used for @var{opts}, otherwise the default @option{-gtoggle}
+is used.
+
+@option{-fcompare-debug=}, with the equal sign but without @var{opts},
+is equivalent to @option{-fno-compare-debug}, which disables the dumping
+of the final representation and the second compilation, preventing even
+@env{GCC_COMPARE_DEBUG} from taking effect.
+
+To verify full coverage during @option{-fcompare-debug} testing, set
+@env{GCC_COMPARE_DEBUG} to say @option{-fcompare-debug-not-overridden},
+which GCC rejects as an invalid option in any actual compilation
+(rather than preprocessing, assembly or linking).  To get just a
+warning, setting @env{GCC_COMPARE_DEBUG} to @samp{-w%n-fcompare-debug
+not overridden} will do.
+
+@item -fcompare-debug-second
+@opindex fcompare-debug-second
+This option is implicitly passed to the compiler for the second
+compilation requested by @option{-fcompare-debug}, along with options to
+silence warnings, and omitting other options that would cause the compiler
+to produce output to files or to standard output as a side effect.  Dump
+files and preserved temporary files are renamed so as to contain the
+@code{.gk} additional extension during the second compilation, to avoid
+overwriting those generated by the first.
+
+When this option is passed to the compiler driver, it causes the
+@emph{first} compilation to be skipped, which makes it useful for little
+other than debugging the compiler proper.
+
+@item -gtoggle
+@opindex gtoggle
+Turn off generation of debug info, if leaving out this option
+generates it, or turn it on at level 2 otherwise.  The position of this
+argument in the command line does not matter; it takes effect after all
+other options are processed, and it does so only once, no matter how
+many times it is given.  This is mainly intended to be used with
+@option{-fcompare-debug}.
+
+@item -fvar-tracking-assignments-toggle
+@opindex fvar-tracking-assignments-toggle
+@opindex fno-var-tracking-assignments-toggle
+Toggle @option{-fvar-tracking-assignments}, in the same way that
+@option{-gtoggle} toggles @option{-g}.
+
+@item -Q
+@opindex Q
+Makes the compiler print out each function name as it is compiled, and
+print some statistics about each pass when it finishes.
+
+@item -ftime-report
+@opindex ftime-report
+Makes the compiler print some statistics about the time consumed by each
+pass when it finishes.
+
+@item -ftime-report-details
+@opindex ftime-report-details
+Record the time consumed by infrastructure parts separately for each pass.
+
+@item -fira-verbose=@var{n}
+@opindex fira-verbose
+Control the verbosity of the dump file for the integrated register allocator.
+The default value is 5.  If the value @var{n} is greater or equal to 10,
+the dump output is sent to stderr using the same format as @var{n} minus 10.
+
+@item -flto-report
+@opindex flto-report
+Prints a report with internal details on the workings of the link-time
+optimizer.  The contents of this report vary from version to version.
+It is meant to be useful to GCC developers when processing object
+files in LTO mode (via @option{-flto}).
+
+Disabled by default.
+
+@item -flto-report-wpa
+@opindex flto-report-wpa
+Like @option{-flto-report}, but only print for the WPA phase of link-time
+optimization.
+
+@item -fmem-report
+@opindex fmem-report
+Makes the compiler print some statistics about permanent memory
+allocation when it finishes.
+
+@item -fmem-report-wpa
+@opindex fmem-report-wpa
+Makes the compiler print some statistics about permanent memory
+allocation for the WPA phase only.
+
+@item -fpre-ipa-mem-report
+@opindex fpre-ipa-mem-report
+@item -fpost-ipa-mem-report
+@opindex fpost-ipa-mem-report
+Makes the compiler print some statistics about permanent memory
+allocation before or after interprocedural optimization.
+
+@item -fmultiflags
+@opindex fmultiflags
+This option enables multilib-aware @code{TFLAGS} to be used to build
+target libraries with options different from those the compiler is
+configured to use by default, through the use of specs (@xref{Spec
+Files}) set up by compiler internals, by the target, or by builders at
+configure time.
+
+Like @code{TFLAGS}, this allows the target libraries to be built for
+portable baseline environments, while the compiler defaults to more
+demanding ones.  That's useful because users can easily override the
+defaults the compiler is configured to use to build their own programs,
+if the defaults are not ideal for their target environment, whereas
+rebuilding the runtime libraries is usually not as easy or desirable.
+
+Unlike @code{TFLAGS}, the use of specs enables different flags to be
+selected for different multilibs.  The way to accomplish that is to
+build with @samp{make TFLAGS=-fmultiflags}, after configuring
+@samp{--with-specs=%@{fmultiflags:...@}}.
+
+This option is discarded by the driver once it's done processing driver
+self spec.
+
+It is also useful to check that @code{TFLAGS} are being used to build
+all target libraries, by configuring a non-bootstrap compiler
+@samp{--with-specs='%@{!fmultiflags:%emissing TFLAGS@}'} and building
+the compiler and target libraries.
+
+@item -fprofile-report
+@opindex fprofile-report
+Makes the compiler print some statistics about consistency of the
+(estimated) profile and effect of individual passes.
+
+@item -fstack-usage
+@opindex fstack-usage
+Makes the compiler output stack usage information for the program, on a
+per-function basis.  The filename for the dump is made by appending
+@file{.su} to the @var{auxname}.  @var{auxname} is generated from the name of
+the output file, if explicitly specified and it is not an executable,
+otherwise it is the basename of the source file.  An entry is made up
+of three fields:
+
+@itemize
+@item
+The name of the function.
+@item
+A number of bytes.
+@item
+One or more qualifiers: @code{static}, @code{dynamic}, @code{bounded}.
+@end itemize
+
+The qualifier @code{static} means that the function manipulates the stack
+statically: a fixed number of bytes are allocated for the frame on function
+entry and released on function exit; no stack adjustments are otherwise made
+in the function.  The second field is this fixed number of bytes.
+
+The qualifier @code{dynamic} means that the function manipulates the stack
+dynamically: in addition to the static allocation described above, stack
+adjustments are made in the body of the function, for example to push/pop
+arguments around function calls.  If the qualifier @code{bounded} is also
+present, the amount of these adjustments is bounded at compile time and
+the second field is an upper bound of the total amount of stack used by
+the function.  If it is not present, the amount of these adjustments is
+not bounded at compile time and the second field only represents the
+bounded part.
+
+@item -fstats
+@opindex fstats
+Emit statistics about front-end processing at the end of the compilation.
+This option is supported only by the C++ front end, and
+the information is generally only useful to the G++ development team.
+
+@item -fdbg-cnt-list
+@opindex fdbg-cnt-list
+Print the name and the counter upper bound for all debug counters.
+
+
+@item -fdbg-cnt=@var{counter-value-list}
+@opindex fdbg-cnt
+Set the internal debug counter lower and upper bound.  @var{counter-value-list}
+is a comma-separated list of @var{name}:@var{lower_bound1}-@var{upper_bound1}
+[:@var{lower_bound2}-@var{upper_bound2}...] tuples which sets
+the name of the counter and list of closed intervals.
+The @var{lower_bound} is optional and is zero
+initialized if not set.
+For example, with @option{-fdbg-cnt=dce:2-4:10-11,tail_call:10},
+@code{dbg_cnt(dce)} returns true only for second, third, fourth, tenth and
+eleventh invocation.
+For @code{dbg_cnt(tail_call)} true is returned for first 10 invocations.
+
+@item -print-file-name=@var{library}
+@opindex print-file-name
+Print the full absolute name of the library file @var{library} that
+would be used when linking---and don't do anything else.  With this
+option, GCC does not compile or link anything; it just prints the
+file name.
+
+@item -print-multi-directory
+@opindex print-multi-directory
+Print the directory name corresponding to the multilib selected by any
+other switches present in the command line.  This directory is supposed
+to exist in @env{GCC_EXEC_PREFIX}.
+
+@item -print-multi-lib
+@opindex print-multi-lib
+Print the mapping from multilib directory names to compiler switches
+that enable them.  The directory name is separated from the switches by
+@samp{;}, and each switch starts with an @samp{@@} instead of the
+@samp{-}, without spaces between multiple switches.  This is supposed to
+ease shell processing.
+
+@item -print-multi-os-directory
+@opindex print-multi-os-directory
+Print the path to OS libraries for the selected
+multilib, relative to some @file{lib} subdirectory.  If OS libraries are
+present in the @file{lib} subdirectory and no multilibs are used, this is
+usually just @file{.}, if OS libraries are present in @file{lib@var{suffix}}
+sibling directories this prints e.g.@: @file{../lib64}, @file{../lib} or
+@file{../lib32}, or if OS libraries are present in @file{lib/@var{subdir}}
+subdirectories it prints e.g.@: @file{amd64}, @file{sparcv9} or @file{ev6}.
+
+@item -print-multiarch
+@opindex print-multiarch
+Print the path to OS libraries for the selected multiarch,
+relative to some @file{lib} subdirectory.
+
+@item -print-prog-name=@var{program}
+@opindex print-prog-name
+Like @option{-print-file-name}, but searches for a program such as @command{cpp}.
+
+@item -print-libgcc-file-name
+@opindex print-libgcc-file-name
+Same as @option{-print-file-name=libgcc.a}.
+
+This is useful when you use @option{-nostdlib} or @option{-nodefaultlibs}
+but you do want to link with @file{libgcc.a}.  You can do:
+
+@smallexample
+gcc -nostdlib @var{files}@dots{} `gcc -print-libgcc-file-name`
+@end smallexample
+
+@item -print-search-dirs
+@opindex print-search-dirs
+Print the name of the configured installation directory and a list of
+program and library directories @command{gcc} searches---and don't do anything else.
+
+This is useful when @command{gcc} prints the error message
+@samp{installation problem, cannot exec cpp0: No such file or directory}.
+To resolve this you either need to put @file{cpp0} and the other compiler
+components where @command{gcc} expects to find them, or you can set the environment
+variable @env{GCC_EXEC_PREFIX} to the directory where you installed them.
+Don't forget the trailing @samp{/}.
+@xref{Environment Variables}.
+
+@item -print-sysroot
+@opindex print-sysroot
+Print the target sysroot directory that is used during
+compilation.  This is the target sysroot specified either at configure
+time or using the @option{--sysroot} option, possibly with an extra
+suffix that depends on compilation options.  If no target sysroot is
+specified, the option prints nothing.
+
+@item -print-sysroot-headers-suffix
+@opindex print-sysroot-headers-suffix
+Print the suffix added to the target sysroot when searching for
+headers, or give an error if the compiler is not configured with such
+a suffix---and don't do anything else.
+
+@item -dumpmachine
+@opindex dumpmachine
+Print the compiler's target machine (for example,
+@samp{i686-pc-linux-gnu})---and don't do anything else.
+
+@item -dumpversion
+@opindex dumpversion
+Print the compiler version (for example, @code{3.0}, @code{6.3.0} or @code{7})---and don't do
+anything else.  This is the compiler version used in filesystem paths and
+specs. Depending on how the compiler has been configured it can be just
+a single number (major version), two numbers separated by a dot (major and
+minor version) or three numbers separated by dots (major, minor and patchlevel
+version).
+
+@item -dumpfullversion
+@opindex dumpfullversion
+Print the full compiler version---and don't do anything else. The output is
+always three numbers separated by dots, major, minor and patchlevel version.
+
+@item -dumpspecs
+@opindex dumpspecs
+Print the compiler's built-in specs---and don't do anything else.  (This
+is used when GCC itself is being built.)  @xref{Spec Files}.
+@end table
+
+@node Submodel Options
+@section Machine-Dependent Options
+@cindex submodel options
+@cindex specifying hardware config
+@cindex hardware models and configurations, specifying
+@cindex target-dependent options
+@cindex machine-dependent options
+
+Each target machine supported by GCC can have its own options---for
+example, to allow you to compile for a particular processor variant or
+ABI, or to control optimizations specific to that machine.  By
+convention, the names of machine-specific options start with
+@samp{-m}.
+
+Some configurations of the compiler also support additional target-specific
+options, usually for compatibility with other compilers on the same
+platform.
+
+@c This list is ordered alphanumerically by subsection name.
+@c It should be the same order and spelling as these options are listed
+@c in Machine Dependent Options
+
+@menu
+* AArch64 Options::
+* Adapteva Epiphany Options::
+* AMD GCN Options::
+* ARC Options::
+* ARM Options::
+* AVR Options::
+* Blackfin Options::
+* C6X Options::
+* CRIS Options::
+* C-SKY Options::
+* Darwin Options::
+* DEC Alpha Options::
+* eBPF Options::
+* FR30 Options::
+* FT32 Options::
+* FRV Options::
+* GNU/Linux Options::
+* H8/300 Options::
+* HPPA Options::
+* IA-64 Options::
+* LM32 Options::
+* LoongArch Options::
+* M32C Options::
+* M32R/D Options::
+* M680x0 Options::
+* MCore Options::
+* MeP Options::
+* MicroBlaze Options::
+* MIPS Options::
+* MMIX Options::
+* MN10300 Options::
+* Moxie Options::
+* MSP430 Options::
+* NDS32 Options::
+* Nios II Options::
+* Nvidia PTX Options::
+* OpenRISC Options::
+* PDP-11 Options::
+* picoChip Options::
+* PowerPC Options::
+* PRU Options::
+* RISC-V Options::
+* RL78 Options::
+* RS/6000 and PowerPC Options::
+* RX Options::
+* S/390 and zSeries Options::
+* Score Options::
+* SH Options::
+* Solaris 2 Options::
+* SPARC Options::
+* System V Options::
+* V850 Options::
+* VAX Options::
+* Visium Options::
+* VMS Options::
+* VxWorks Options::
+* x86 Options::
+* x86 Windows Options::
+* Xstormy16 Options::
+* Xtensa Options::
+* zSeries Options::
+@end menu
+
+@node AArch64 Options
+@subsection AArch64 Options
+@cindex AArch64 Options
+
+These options are defined for AArch64 implementations:
+
+@table @gcctabopt
+
+@item -mabi=@var{name}
+@opindex mabi
+Generate code for the specified data model.  Permissible values
+are @samp{ilp32} for SysV-like data model where int, long int and pointers
+are 32 bits, and @samp{lp64} for SysV-like data model where int is 32 bits,
+but long int and pointers are 64 bits.
+
+The default depends on the specific target configuration.  Note that
+the LP64 and ILP32 ABIs are not link-compatible; you must compile your
+entire program with the same ABI, and link with a compatible set of libraries.
+
+@item -mbig-endian
+@opindex mbig-endian
+Generate big-endian code.  This is the default when GCC is configured for an
+@samp{aarch64_be-*-*} target.
+
+@item -mgeneral-regs-only
+@opindex mgeneral-regs-only
+Generate code which uses only the general-purpose registers.  This will prevent
+the compiler from using floating-point and Advanced SIMD registers but will not
+impose any restrictions on the assembler.
+
+@item -mlittle-endian
+@opindex mlittle-endian
+Generate little-endian code.  This is the default when GCC is configured for an
+@samp{aarch64-*-*} but not an @samp{aarch64_be-*-*} target.
+
+@item -mcmodel=tiny
+@opindex mcmodel=tiny
+Generate code for the tiny code model.  The program and its statically defined
+symbols must be within 1MB of each other.  Programs can be statically or
+dynamically linked.
+
+@item -mcmodel=small
+@opindex mcmodel=small
+Generate code for the small code model.  The program and its statically defined
+symbols must be within 4GB of each other.  Programs can be statically or
+dynamically linked.  This is the default code model.
+
+@item -mcmodel=large
+@opindex mcmodel=large
+Generate code for the large code model.  This makes no assumptions about
+addresses and sizes of sections.  Programs can be statically linked only.  The
+@option{-mcmodel=large} option is incompatible with @option{-mabi=ilp32},
+@option{-fpic} and @option{-fPIC}.
+
+@item -mstrict-align
+@itemx -mno-strict-align
+@opindex mstrict-align
+@opindex mno-strict-align
+Avoid or allow generating memory accesses that may not be aligned on a natural
+object boundary as described in the architecture specification.
+
+@item -momit-leaf-frame-pointer
+@itemx -mno-omit-leaf-frame-pointer
+@opindex momit-leaf-frame-pointer
+@opindex mno-omit-leaf-frame-pointer
+Omit or keep the frame pointer in leaf functions.  The former behavior is the
+default.
+
+@item -mstack-protector-guard=@var{guard}
+@itemx -mstack-protector-guard-reg=@var{reg}
+@itemx -mstack-protector-guard-offset=@var{offset}
+@opindex mstack-protector-guard
+@opindex mstack-protector-guard-reg
+@opindex mstack-protector-guard-offset
+Generate stack protection code using canary at @var{guard}.  Supported
+locations are @samp{global} for a global canary or @samp{sysreg} for a
+canary in an appropriate system register.
+
+With the latter choice the options
+@option{-mstack-protector-guard-reg=@var{reg}} and
+@option{-mstack-protector-guard-offset=@var{offset}} furthermore specify
+which system register to use as base register for reading the canary,
+and from what offset from that base register. There is no default
+register or offset as this is entirely for use within the Linux
+kernel.
+
+@item -mtls-dialect=desc
+@opindex mtls-dialect=desc
+Use TLS descriptors as the thread-local storage mechanism for dynamic accesses
+of TLS variables.  This is the default.
+
+@item -mtls-dialect=traditional
+@opindex mtls-dialect=traditional
+Use traditional TLS as the thread-local storage mechanism for dynamic accesses
+of TLS variables.
+
+@item -mtls-size=@var{size}
+@opindex mtls-size
+Specify bit size of immediate TLS offsets.  Valid values are 12, 24, 32, 48.
+This option requires binutils 2.26 or newer.
+
+@item -mfix-cortex-a53-835769
+@itemx -mno-fix-cortex-a53-835769
+@opindex mfix-cortex-a53-835769
+@opindex mno-fix-cortex-a53-835769
+Enable or disable the workaround for the ARM Cortex-A53 erratum number 835769.
+This involves inserting a NOP instruction between memory instructions and
+64-bit integer multiply-accumulate instructions.
+
+@item -mfix-cortex-a53-843419
+@itemx -mno-fix-cortex-a53-843419
+@opindex mfix-cortex-a53-843419
+@opindex mno-fix-cortex-a53-843419
+Enable or disable the workaround for the ARM Cortex-A53 erratum number 843419.
+This erratum workaround is made at link time and this will only pass the
+corresponding flag to the linker.
+
+@item -mlow-precision-recip-sqrt
+@itemx -mno-low-precision-recip-sqrt
+@opindex mlow-precision-recip-sqrt
+@opindex mno-low-precision-recip-sqrt
+Enable or disable the reciprocal square root approximation.
+This option only has an effect if @option{-ffast-math} or
+@option{-funsafe-math-optimizations} is used as well.  Enabling this reduces
+precision of reciprocal square root results to about 16 bits for
+single precision and to 32 bits for double precision.
+
+@item -mlow-precision-sqrt
+@itemx -mno-low-precision-sqrt
+@opindex mlow-precision-sqrt
+@opindex mno-low-precision-sqrt
+Enable or disable the square root approximation.
+This option only has an effect if @option{-ffast-math} or
+@option{-funsafe-math-optimizations} is used as well.  Enabling this reduces
+precision of square root results to about 16 bits for
+single precision and to 32 bits for double precision.
+If enabled, it implies @option{-mlow-precision-recip-sqrt}.
+
+@item -mlow-precision-div
+@itemx -mno-low-precision-div
+@opindex mlow-precision-div
+@opindex mno-low-precision-div
+Enable or disable the division approximation.
+This option only has an effect if @option{-ffast-math} or
+@option{-funsafe-math-optimizations} is used as well.  Enabling this reduces
+precision of division results to about 16 bits for
+single precision and to 32 bits for double precision.
+
+@item -mtrack-speculation
+@itemx -mno-track-speculation
+Enable or disable generation of additional code to track speculative
+execution through conditional branches.  The tracking state can then
+be used by the compiler when expanding calls to
+@code{__builtin_speculation_safe_copy} to permit a more efficient code
+sequence to be generated.
+
+@item -moutline-atomics
+@itemx -mno-outline-atomics
+Enable or disable calls to out-of-line helpers to implement atomic operations.
+These helpers will, at runtime, determine if the LSE instructions from
+ARMv8.1-A can be used; if not, they will use the load/store-exclusive
+instructions that are present in the base ARMv8.0 ISA.
+
+This option is only applicable when compiling for the base ARMv8.0
+instruction set.  If using a later revision, e.g. @option{-march=armv8.1-a}
+or @option{-march=armv8-a+lse}, the ARMv8.1-Atomics instructions will be
+used directly.  The same applies when using @option{-mcpu=} when the
+selected cpu supports the @samp{lse} feature.
+This option is on by default.
+
+@item -march=@var{name}
+@opindex march
+Specify the name of the target architecture and, optionally, one or
+more feature modifiers.  This option has the form
+@option{-march=@var{arch}@r{@{}+@r{[}no@r{]}@var{feature}@r{@}*}}.
+
+The table below summarizes the permissible values for @var{arch}
+and the features that they enable by default:
+
+@multitable @columnfractions 0.20 0.20 0.60
+@headitem @var{arch} value @tab Architecture @tab Includes by default
+@item @samp{armv8-a} @tab Armv8-A @tab @samp{+fp}, @samp{+simd}
+@item @samp{armv8.1-a} @tab Armv8.1-A @tab @samp{armv8-a}, @samp{+crc}, @samp{+lse}, @samp{+rdma}
+@item @samp{armv8.2-a} @tab Armv8.2-A @tab @samp{armv8.1-a}
+@item @samp{armv8.3-a} @tab Armv8.3-A @tab @samp{armv8.2-a}, @samp{+pauth}
+@item @samp{armv8.4-a} @tab Armv8.4-A @tab @samp{armv8.3-a}, @samp{+flagm}, @samp{+fp16fml}, @samp{+dotprod}
+@item @samp{armv8.5-a} @tab Armv8.5-A @tab @samp{armv8.4-a}, @samp{+sb}, @samp{+ssbs}, @samp{+predres}
+@item @samp{armv8.6-a} @tab Armv8.6-A @tab @samp{armv8.5-a}, @samp{+bf16}, @samp{+i8mm}
+@item @samp{armv8.7-a} @tab Armv8.7-A @tab @samp{armv8.6-a}, @samp{+ls64}
+@item @samp{armv8.8-a} @tab Armv8.8-a @tab @samp{armv8.7-a}, @samp{+mops}
+@item @samp{armv9-a} @tab Armv9-A @tab @samp{armv8.5-a}, @samp{+sve}, @samp{+sve2}
+@item @samp{armv9.1-a} @tab Armv9.1-A @tab @samp{armv9-a}, @samp{+bf16}, @samp{+i8mm}
+@item @samp{armv9.2-a} @tab Armv9.2-A @tab @samp{armv9.1-a}, @samp{+ls64}
+@item @samp{armv9.3-a} @tab Armv9.3-A @tab @samp{armv9.2-a}, @samp{+mops}
+@item @samp{armv8-r} @tab Armv8-R @tab @samp{armv8-r}
+@end multitable
+
+The value @samp{native} is available on native AArch64 GNU/Linux and
+causes the compiler to pick the architecture of the host system.  This
+option has no effect if the compiler is unable to recognize the
+architecture of the host system,
+
+The permissible values for @var{feature} are listed in the sub-section
+on @ref{aarch64-feature-modifiers,,@option{-march} and @option{-mcpu}
+Feature Modifiers}.  Where conflicting feature modifiers are
+specified, the right-most feature is used.
+
+GCC uses @var{name} to determine what kind of instructions it can emit
+when generating assembly code.  If @option{-march} is specified
+without either of @option{-mtune} or @option{-mcpu} also being
+specified, the code is tuned to perform well across a range of target
+processors implementing the target architecture.
+
+@item -mtune=@var{name}
+@opindex mtune
+Specify the name of the target processor for which GCC should tune the
+performance of the code.  Permissible values for this option are:
+@samp{generic}, @samp{cortex-a35}, @samp{cortex-a53}, @samp{cortex-a55},
+@samp{cortex-a57}, @samp{cortex-a72}, @samp{cortex-a73}, @samp{cortex-a75},
+@samp{cortex-a76}, @samp{cortex-a76ae}, @samp{cortex-a77},
+@samp{cortex-a65}, @samp{cortex-a65ae}, @samp{cortex-a34},
+@samp{cortex-a78}, @samp{cortex-a78ae}, @samp{cortex-a78c},
+@samp{ares}, @samp{exynos-m1}, @samp{emag}, @samp{falkor},
+@samp{neoverse-512tvb}, @samp{neoverse-e1}, @samp{neoverse-n1},
+@samp{neoverse-n2}, @samp{neoverse-v1}, @samp{neoverse-v2}, @samp{qdf24xx},
+@samp{saphira}, @samp{phecda}, @samp{xgene1}, @samp{vulcan},
+@samp{octeontx}, @samp{octeontx81},  @samp{octeontx83},
+@samp{octeontx2}, @samp{octeontx2t98}, @samp{octeontx2t96}
+@samp{octeontx2t93}, @samp{octeontx2f95}, @samp{octeontx2f95n},
+@samp{octeontx2f95mm},
+@samp{a64fx},
+@samp{thunderx}, @samp{thunderxt88},
+@samp{thunderxt88p1}, @samp{thunderxt81}, @samp{tsv110},
+@samp{thunderxt83}, @samp{thunderx2t99}, @samp{thunderx3t110}, @samp{zeus},
+@samp{cortex-a57.cortex-a53}, @samp{cortex-a72.cortex-a53},
+@samp{cortex-a73.cortex-a35}, @samp{cortex-a73.cortex-a53},
+@samp{cortex-a75.cortex-a55}, @samp{cortex-a76.cortex-a55},
+@samp{cortex-r82}, @samp{cortex-x1}, @samp{cortex-x2},
+@samp{cortex-a510}, @samp{cortex-a710}, @samp{ampere1}, @samp{native}.
+
+The values @samp{cortex-a57.cortex-a53}, @samp{cortex-a72.cortex-a53},
+@samp{cortex-a73.cortex-a35}, @samp{cortex-a73.cortex-a53},
+@samp{cortex-a75.cortex-a55}, @samp{cortex-a76.cortex-a55} specify that GCC
+should tune for a big.LITTLE system.
+
+The value @samp{neoverse-512tvb} specifies that GCC should tune
+for Neoverse cores that (a) implement SVE and (b) have a total vector
+bandwidth of 512 bits per cycle.  In other words, the option tells GCC to
+tune for Neoverse cores that can execute 4 128-bit Advanced SIMD arithmetic
+instructions a cycle and that can execute an equivalent number of SVE
+arithmetic instructions per cycle (2 for 256-bit SVE, 4 for 128-bit SVE).
+This is more general than tuning for a specific core like Neoverse V1
+but is more specific than the default tuning described below.
+
+Additionally on native AArch64 GNU/Linux systems the value
+@samp{native} tunes performance to the host system.  This option has no effect
+if the compiler is unable to recognize the processor of the host system.
+
+Where none of @option{-mtune=}, @option{-mcpu=} or @option{-march=}
+are specified, the code is tuned to perform well across a range
+of target processors.
+
+This option cannot be suffixed by feature modifiers.
+
+@item -mcpu=@var{name}
+@opindex mcpu
+Specify the name of the target processor, optionally suffixed by one
+or more feature modifiers.  This option has the form
+@option{-mcpu=@var{cpu}@r{@{}+@r{[}no@r{]}@var{feature}@r{@}*}}, where
+the permissible values for @var{cpu} are the same as those available
+for @option{-mtune}.  The permissible values for @var{feature} are
+documented in the sub-section on
+@ref{aarch64-feature-modifiers,,@option{-march} and @option{-mcpu}
+Feature Modifiers}.  Where conflicting feature modifiers are
+specified, the right-most feature is used.
+
+GCC uses @var{name} to determine what kind of instructions it can emit when
+generating assembly code (as if by @option{-march}) and to determine
+the target processor for which to tune for performance (as if
+by @option{-mtune}).  Where this option is used in conjunction
+with @option{-march} or @option{-mtune}, those options take precedence
+over the appropriate part of this option.
+
+@option{-mcpu=neoverse-512tvb} is special in that it does not refer
+to a specific core, but instead refers to all Neoverse cores that
+(a) implement SVE and (b) have a total vector bandwidth of 512 bits
+a cycle.  Unless overridden by @option{-march},
+@option{-mcpu=neoverse-512tvb} generates code that can run on a
+Neoverse V1 core, since Neoverse V1 is the first Neoverse core with
+these properties.  Unless overridden by @option{-mtune},
+@option{-mcpu=neoverse-512tvb} tunes code in the same way as for
+@option{-mtune=neoverse-512tvb}.
+
+@item -moverride=@var{string}
+@opindex moverride
+Override tuning decisions made by the back-end in response to a
+@option{-mtune=} switch.  The syntax, semantics, and accepted values
+for @var{string} in this option are not guaranteed to be consistent
+across releases.
+
+This option is only intended to be useful when developing GCC.
+
+@item -mverbose-cost-dump
+@opindex mverbose-cost-dump
+Enable verbose cost model dumping in the debug dump files.  This option is
+provided for use in debugging the compiler.
+
+@item -mpc-relative-literal-loads
+@itemx -mno-pc-relative-literal-loads
+@opindex mpc-relative-literal-loads
+@opindex mno-pc-relative-literal-loads
+Enable or disable PC-relative literal loads.  With this option literal pools are
+accessed using a single instruction and emitted after each function.  This
+limits the maximum size of functions to 1MB.  This is enabled by default for
+@option{-mcmodel=tiny}.
+
+@item -msign-return-address=@var{scope}
+@opindex msign-return-address
+Select the function scope on which return address signing will be applied.
+Permissible values are @samp{none}, which disables return address signing,
+@samp{non-leaf}, which enables pointer signing for functions which are not leaf
+functions, and @samp{all}, which enables pointer signing for all functions.  The
+default value is @samp{none}. This option has been deprecated by
+-mbranch-protection.
+
+@item -mbranch-protection=@var{none}|@var{standard}|@var{pac-ret}[+@var{leaf}+@var{b-key}]|@var{bti}
+@opindex mbranch-protection
+Select the branch protection features to use.
+@samp{none} is the default and turns off all types of branch protection.
+@samp{standard} turns on all types of branch protection features.  If a feature
+has additional tuning options, then @samp{standard} sets it to its standard
+level.
+@samp{pac-ret[+@var{leaf}]} turns on return address signing to its standard
+level: signing functions that save the return address to memory (non-leaf
+functions will practically always do this) using the a-key.  The optional
+argument @samp{leaf} can be used to extend the signing to include leaf
+functions.  The optional argument @samp{b-key} can be used to sign the functions
+with the B-key instead of the A-key.
+@samp{bti} turns on branch target identification mechanism.
+
+@item -mharden-sls=@var{opts}
+@opindex mharden-sls
+Enable compiler hardening against straight line speculation (SLS).
+@var{opts} is a comma-separated list of the following options:
+@table @samp
+@item retbr
+@item blr
+@end table
+In addition, @samp{-mharden-sls=all} enables all SLS hardening while
+@samp{-mharden-sls=none} disables all SLS hardening.
+
+@item -msve-vector-bits=@var{bits}
+@opindex msve-vector-bits
+Specify the number of bits in an SVE vector register.  This option only has
+an effect when SVE is enabled.
+
+GCC supports two forms of SVE code generation: ``vector-length
+agnostic'' output that works with any size of vector register and
+``vector-length specific'' output that allows GCC to make assumptions
+about the vector length when it is useful for optimization reasons.
+The possible values of @samp{bits} are: @samp{scalable}, @samp{128},
+@samp{256}, @samp{512}, @samp{1024} and @samp{2048}.
+Specifying @samp{scalable} selects vector-length agnostic
+output.  At present @samp{-msve-vector-bits=128} also generates vector-length
+agnostic output for big-endian targets.  All other values generate
+vector-length specific code.  The behavior of these values may change
+in future releases and no value except @samp{scalable} should be
+relied on for producing code that is portable across different
+hardware SVE vector lengths.
+
+The default is @samp{-msve-vector-bits=scalable}, which produces
+vector-length agnostic code.
+@end table
+
+@subsubsection @option{-march} and @option{-mcpu} Feature Modifiers
+@anchor{aarch64-feature-modifiers}
+@cindex @option{-march} feature modifiers
+@cindex @option{-mcpu} feature modifiers
+Feature modifiers used with @option{-march} and @option{-mcpu} can be any of
+the following and their inverses @option{no@var{feature}}:
+
+@table @samp
+@item crc
+Enable CRC extension.  This is on by default for
+@option{-march=armv8.1-a}.
+@item crypto
+Enable Crypto extension.  This also enables Advanced SIMD and floating-point
+instructions.
+@item fp
+Enable floating-point instructions.  This is on by default for all possible
+values for options @option{-march} and @option{-mcpu}.
+@item simd
+Enable Advanced SIMD instructions.  This also enables floating-point
+instructions.  This is on by default for all possible values for options
+@option{-march} and @option{-mcpu}.
+@item sve
+Enable Scalable Vector Extension instructions.  This also enables Advanced
+SIMD and floating-point instructions.
+@item lse
+Enable Large System Extension instructions.  This is on by default for
+@option{-march=armv8.1-a}.
+@item rdma
+Enable Round Double Multiply Accumulate instructions.  This is on by default
+for @option{-march=armv8.1-a}.
+@item fp16
+Enable FP16 extension.  This also enables floating-point instructions.
+@item fp16fml
+Enable FP16 fmla extension.  This also enables FP16 extensions and
+floating-point instructions. This option is enabled by default for @option{-march=armv8.4-a}. Use of this option with architectures prior to Armv8.2-A is not supported.
+
+@item rcpc
+Enable the RcPc extension.  This does not change code generation from GCC,
+but is passed on to the assembler, enabling inline asm statements to use
+instructions from the RcPc extension.
+@item dotprod
+Enable the Dot Product extension.  This also enables Advanced SIMD instructions.
+@item aes
+Enable the Armv8-a aes and pmull crypto extension.  This also enables Advanced
+SIMD instructions.
+@item sha2
+Enable the Armv8-a sha2 crypto extension.  This also enables Advanced SIMD instructions.
+@item sha3
+Enable the sha512 and sha3 crypto extension.  This also enables Advanced SIMD
+instructions. Use of this option with architectures prior to Armv8.2-A is not supported.
+@item sm4
+Enable the sm3 and sm4 crypto extension.  This also enables Advanced SIMD instructions.
+Use of this option with architectures prior to Armv8.2-A is not supported.
+@item profile
+Enable the Statistical Profiling extension.  This option is only to enable the
+extension at the assembler level and does not affect code generation.
+@item rng
+Enable the Armv8.5-a Random Number instructions.  This option is only to
+enable the extension at the assembler level and does not affect code
+generation.
+@item memtag
+Enable the Armv8.5-a Memory Tagging Extensions.
+Use of this option with architectures prior to Armv8.5-A is not supported.
+@item sb
+Enable the Armv8-a Speculation Barrier instruction.  This option is only to
+enable the extension at the assembler level and does not affect code
+generation.  This option is enabled by default for @option{-march=armv8.5-a}.
+@item ssbs
+Enable the Armv8-a Speculative Store Bypass Safe instruction.  This option
+is only to enable the extension at the assembler level and does not affect code
+generation.  This option is enabled by default for @option{-march=armv8.5-a}.
+@item predres
+Enable the Armv8-a Execution and Data Prediction Restriction instructions.
+This option is only to enable the extension at the assembler level and does
+not affect code generation.  This option is enabled by default for
+@option{-march=armv8.5-a}.
+@item sve2
+Enable the Armv8-a Scalable Vector Extension 2.  This also enables SVE
+instructions.
+@item sve2-bitperm
+Enable SVE2 bitperm instructions.  This also enables SVE2 instructions.
+@item sve2-sm4
+Enable SVE2 sm4 instructions.  This also enables SVE2 instructions.
+@item sve2-aes
+Enable SVE2 aes instructions.  This also enables SVE2 instructions.
+@item sve2-sha3
+Enable SVE2 sha3 instructions.  This also enables SVE2 instructions.
+@item tme
+Enable the Transactional Memory Extension.
+@item i8mm
+Enable 8-bit Integer Matrix Multiply instructions.  This also enables
+Advanced SIMD and floating-point instructions.  This option is enabled by
+default for @option{-march=armv8.6-a}.  Use of this option with architectures
+prior to Armv8.2-A is not supported.
+@item f32mm
+Enable 32-bit Floating point Matrix Multiply instructions.  This also enables
+SVE instructions.  Use of this option with architectures prior to Armv8.2-A is
+not supported.
+@item f64mm
+Enable 64-bit Floating point Matrix Multiply instructions.  This also enables
+SVE instructions.  Use of this option with architectures prior to Armv8.2-A is
+not supported.
+@item bf16
+Enable brain half-precision floating-point instructions.  This also enables
+Advanced SIMD and floating-point instructions.  This option is enabled by
+default for @option{-march=armv8.6-a}.  Use of this option with architectures
+prior to Armv8.2-A is not supported.
+@item ls64
+Enable the 64-byte atomic load and store instructions for accelerators.
+This option is enabled by default for @option{-march=armv8.7-a}.
+@item mops
+Enable the instructions to accelerate memory operations like @code{memcpy},
+@code{memmove}, @code{memset}.  This option is enabled by default for
+@option{-march=armv8.8-a}
+@item flagm
+Enable the Flag Manipulation instructions Extension.
+@item pauth
+Enable the Pointer Authentication Extension.
+
+@end table
+
+Feature @option{crypto} implies @option{aes}, @option{sha2}, and @option{simd},
+which implies @option{fp}.
+Conversely, @option{nofp} implies @option{nosimd}, which implies
+@option{nocrypto}, @option{noaes} and @option{nosha2}.
+
+@node Adapteva Epiphany Options
+@subsection Adapteva Epiphany Options
+
+These @samp{-m} options are defined for Adapteva Epiphany:
+
+@table @gcctabopt
+@item -mhalf-reg-file
+@opindex mhalf-reg-file
+Don't allocate any register in the range @code{r32}@dots{}@code{r63}.
+That allows code to run on hardware variants that lack these registers.
+
+@item -mprefer-short-insn-regs
+@opindex mprefer-short-insn-regs
+Preferentially allocate registers that allow short instruction generation.
+This can result in increased instruction count, so this may either reduce or
+increase overall code size.
+
+@item -mbranch-cost=@var{num}
+@opindex mbranch-cost
+Set the cost of branches to roughly @var{num} ``simple'' instructions.
+This cost is only a heuristic and is not guaranteed to produce
+consistent results across releases.
+
+@item -mcmove
+@opindex mcmove
+Enable the generation of conditional moves.
+
+@item -mnops=@var{num}
+@opindex mnops
+Emit @var{num} NOPs before every other generated instruction.
+
+@item -mno-soft-cmpsf
+@opindex mno-soft-cmpsf
+@opindex msoft-cmpsf
+For single-precision floating-point comparisons, emit an @code{fsub} instruction
+and test the flags.  This is faster than a software comparison, but can
+get incorrect results in the presence of NaNs, or when two different small
+numbers are compared such that their difference is calculated as zero.
+The default is @option{-msoft-cmpsf}, which uses slower, but IEEE-compliant,
+software comparisons.
+
+@item -mstack-offset=@var{num}
+@opindex mstack-offset
+Set the offset between the top of the stack and the stack pointer.
+E.g., a value of 8 means that the eight bytes in the range @code{sp+0@dots{}sp+7}
+can be used by leaf functions without stack allocation.
+Values other than @samp{8} or @samp{16} are untested and unlikely to work.
+Note also that this option changes the ABI; compiling a program with a
+different stack offset than the libraries have been compiled with
+generally does not work.
+This option can be useful if you want to evaluate if a different stack
+offset would give you better code, but to actually use a different stack
+offset to build working programs, it is recommended to configure the
+toolchain with the appropriate @option{--with-stack-offset=@var{num}} option.
+
+@item -mno-round-nearest
+@opindex mno-round-nearest
+@opindex mround-nearest
+Make the scheduler assume that the rounding mode has been set to
+truncating.  The default is @option{-mround-nearest}.
+
+@item -mlong-calls
+@opindex mlong-calls
+If not otherwise specified by an attribute, assume all calls might be beyond
+the offset range of the @code{b} / @code{bl} instructions, and therefore load the
+function address into a register before performing a (otherwise direct) call.
+This is the default.
+
+@item -mshort-calls
+@opindex short-calls
+If not otherwise specified by an attribute, assume all direct calls are
+in the range of the @code{b} / @code{bl} instructions, so use these instructions
+for direct calls.  The default is @option{-mlong-calls}.
+
+@item -msmall16
+@opindex msmall16
+Assume addresses can be loaded as 16-bit unsigned values.  This does not
+apply to function addresses for which @option{-mlong-calls} semantics
+are in effect.
+
+@item -mfp-mode=@var{mode}
+@opindex mfp-mode
+Set the prevailing mode of the floating-point unit.
+This determines the floating-point mode that is provided and expected
+at function call and return time.  Making this mode match the mode you
+predominantly need at function start can make your programs smaller and
+faster by avoiding unnecessary mode switches.
+
+@var{mode} can be set to one the following values:
+
+@table @samp
+@item caller
+Any mode at function entry is valid, and retained or restored when
+the function returns, and when it calls other functions.
+This mode is useful for compiling libraries or other compilation units
+you might want to incorporate into different programs with different
+prevailing FPU modes, and the convenience of being able to use a single
+object file outweighs the size and speed overhead for any extra
+mode switching that might be needed, compared with what would be needed
+with a more specific choice of prevailing FPU mode.
+
+@item truncate
+This is the mode used for floating-point calculations with
+truncating (i.e.@: round towards zero) rounding mode.  That includes
+conversion from floating point to integer.
+
+@item round-nearest
+This is the mode used for floating-point calculations with
+round-to-nearest-or-even rounding mode.
+
+@item int
+This is the mode used to perform integer calculations in the FPU, e.g.@:
+integer multiply, or integer multiply-and-accumulate.
+@end table
+
+The default is @option{-mfp-mode=caller}
+
+@item -mno-split-lohi
+@itemx -mno-postinc
+@itemx -mno-postmodify
+@opindex mno-split-lohi
+@opindex msplit-lohi
+@opindex mno-postinc
+@opindex mpostinc
+@opindex mno-postmodify
+@opindex mpostmodify
+Code generation tweaks that disable, respectively, splitting of 32-bit
+loads, generation of post-increment addresses, and generation of
+post-modify addresses.  The defaults are @option{msplit-lohi},
+@option{-mpost-inc}, and @option{-mpost-modify}.
+
+@item -mnovect-double
+@opindex mno-vect-double
+@opindex mvect-double
+Change the preferred SIMD mode to SImode.  The default is
+@option{-mvect-double}, which uses DImode as preferred SIMD mode.
+
+@item -max-vect-align=@var{num}
+@opindex max-vect-align
+The maximum alignment for SIMD vector mode types.
+@var{num} may be 4 or 8.  The default is 8.
+Note that this is an ABI change, even though many library function
+interfaces are unaffected if they don't use SIMD vector modes
+in places that affect size and/or alignment of relevant types.
+
+@item -msplit-vecmove-early
+@opindex msplit-vecmove-early
+Split vector moves into single word moves before reload.  In theory this
+can give better register allocation, but so far the reverse seems to be
+generally the case.
+
+@item -m1reg-@var{reg}
+@opindex m1reg-
+Specify a register to hold the constant @minus{}1, which makes loading small negative
+constants and certain bitmasks faster.
+Allowable values for @var{reg} are @samp{r43} and @samp{r63},
+which specify use of that register as a fixed register,
+and @samp{none}, which means that no register is used for this
+purpose.  The default is @option{-m1reg-none}.
+
+@end table
+
+@node AMD GCN Options
+@subsection AMD GCN Options
+@cindex AMD GCN Options
+
+These options are defined specifically for the AMD GCN port.
+
+@table @gcctabopt
+
+@item -march=@var{gpu}
+@opindex march
+@itemx -mtune=@var{gpu}
+@opindex mtune
+Set architecture type or tuning for @var{gpu}. Supported values for @var{gpu}
+are
+
+@table @samp
+@item fiji
+Compile for GCN3 Fiji devices (gfx803).
+
+@item gfx900
+Compile for GCN5 Vega 10 devices (gfx900).
+
+@item gfx906
+Compile for GCN5 Vega 20 devices (gfx906).
+
+@item gfx908
+Compile for CDNA1 Instinct MI100 series devices (gfx908).
+
+@item gfx90a
+Compile for CDNA2 Instinct MI200 series devices (gfx90a).
+
+@end table
+
+@item -msram-ecc=on
+@itemx -msram-ecc=off
+@itemx -msram-ecc=any
+@opindex msram-ecc
+Compile binaries suitable for devices with the SRAM-ECC feature enabled,
+disabled, or either mode.  This feature can be enabled per-process on some
+devices.  The compiled code must match the device mode. The default is
+@samp{any}, for devices that support it.
+
+@item -mstack-size=@var{bytes}
+@opindex mstack-size
+Specify how many @var{bytes} of stack space will be requested for each GPU
+thread (wave-front).  Beware that there may be many threads and limited memory
+available.  The size of the stack allocation may also have an impact on
+run-time performance.  The default is 32KB when using OpenACC or OpenMP, and
+1MB otherwise.
+
+@item -mxnack
+@opindex mxnack
+Compile binaries suitable for devices with the XNACK feature enabled.  Some
+devices always require XNACK and some allow the user to configure XNACK.  The
+compiled code must match the device mode.  The default is @samp{-mno-xnack}.
+At present this option is a placeholder for support that is not yet
+implemented.
+
+@end table
+
+@node ARC Options
+@subsection ARC Options
+@cindex ARC options
+
+The following options control the architecture variant for which code
+is being compiled:
+
+@c architecture variants
+@table @gcctabopt
+
+@item -mbarrel-shifter
+@opindex mbarrel-shifter
+Generate instructions supported by barrel shifter.  This is the default
+unless @option{-mcpu=ARC601} or @samp{-mcpu=ARCEM} is in effect.
+
+@item -mjli-always
+@opindex mjli-always
+Force to call a function using jli_s instruction.  This option is
+valid only for ARCv2 architecture.
+
+@item -mcpu=@var{cpu}
+@opindex mcpu
+Set architecture type, register usage, and instruction scheduling
+parameters for @var{cpu}.  There are also shortcut alias options
+available for backward compatibility and convenience.  Supported
+values for @var{cpu} are
+
+@table @samp
+@opindex mA6
+@opindex mARC600
+@item arc600
+Compile for ARC600.  Aliases: @option{-mA6}, @option{-mARC600}.
+
+@item arc601
+@opindex mARC601
+Compile for ARC601.  Alias: @option{-mARC601}.
+
+@item arc700
+@opindex mA7
+@opindex mARC700
+Compile for ARC700.  Aliases: @option{-mA7}, @option{-mARC700}.
+This is the default when configured with @option{--with-cpu=arc700}@.
+
+@item arcem
+Compile for ARC EM.
+
+@item archs
+Compile for ARC HS.
+
+@item em
+Compile for ARC EM CPU with no hardware extensions.
+
+@item em4
+Compile for ARC EM4 CPU.
+
+@item em4_dmips
+Compile for ARC EM4 DMIPS CPU.
+
+@item em4_fpus
+Compile for ARC EM4 DMIPS CPU with the single-precision floating-point
+extension.
+
+@item em4_fpuda
+Compile for ARC EM4 DMIPS CPU with single-precision floating-point and
+double assist instructions.
+
+@item hs
+Compile for ARC HS CPU with no hardware extensions except the atomic
+instructions.
+
+@item hs34
+Compile for ARC HS34 CPU.
+
+@item hs38
+Compile for ARC HS38 CPU.
+
+@item hs38_linux
+Compile for ARC HS38 CPU with all hardware extensions on.
+
+@item hs4x
+Compile for ARC HS4x CPU.
+
+@item hs4xd
+Compile for ARC HS4xD CPU.
+
+@item hs4x_rel31
+Compile for ARC HS4x CPU release 3.10a.
+
+@item arc600_norm
+Compile for ARC 600 CPU with @code{norm} instructions enabled.
+
+@item arc600_mul32x16
+Compile for ARC 600 CPU with @code{norm} and 32x16-bit multiply 
+instructions enabled.
+
+@item arc600_mul64
+Compile for ARC 600 CPU with @code{norm} and @code{mul64}-family 
+instructions enabled.
+
+@item arc601_norm
+Compile for ARC 601 CPU with @code{norm} instructions enabled.
+
+@item arc601_mul32x16
+Compile for ARC 601 CPU with @code{norm} and 32x16-bit multiply
+instructions enabled.
+
+@item arc601_mul64
+Compile for ARC 601 CPU with @code{norm} and @code{mul64}-family
+instructions enabled.
+
+@item nps400
+Compile for ARC 700 on NPS400 chip.
+
+@item em_mini
+Compile for ARC EM minimalist configuration featuring reduced register
+set.
+
+@end table
+
+@item -mdpfp
+@opindex mdpfp
+@itemx -mdpfp-compact
+@opindex mdpfp-compact
+Generate double-precision FPX instructions, tuned for the compact
+implementation.
+
+@item -mdpfp-fast
+@opindex mdpfp-fast
+Generate double-precision FPX instructions, tuned for the fast
+implementation.
+
+@item -mno-dpfp-lrsr
+@opindex mno-dpfp-lrsr
+Disable @code{lr} and @code{sr} instructions from using FPX extension
+aux registers.
+
+@item -mea
+@opindex mea
+Generate extended arithmetic instructions.  Currently only
+@code{divaw}, @code{adds}, @code{subs}, and @code{sat16} are
+supported.  Only valid for @option{-mcpu=ARC700}.
+
+@item -mno-mpy
+@opindex mno-mpy
+@opindex mmpy
+Do not generate @code{mpy}-family instructions for ARC700.  This option is
+deprecated.
+
+@item -mmul32x16
+@opindex mmul32x16
+Generate 32x16-bit multiply and multiply-accumulate instructions.
+
+@item -mmul64
+@opindex mmul64
+Generate @code{mul64} and @code{mulu64} instructions.  
+Only valid for @option{-mcpu=ARC600}.
+
+@item -mnorm
+@opindex mnorm
+Generate @code{norm} instructions.  This is the default if @option{-mcpu=ARC700}
+is in effect.
+
+@item -mspfp
+@opindex mspfp
+@itemx -mspfp-compact
+@opindex mspfp-compact
+Generate single-precision FPX instructions, tuned for the compact
+implementation.
+
+@item -mspfp-fast
+@opindex mspfp-fast
+Generate single-precision FPX instructions, tuned for the fast
+implementation.
+
+@item -msimd
+@opindex msimd
+Enable generation of ARC SIMD instructions via target-specific
+builtins.  Only valid for @option{-mcpu=ARC700}.
+
+@item -msoft-float
+@opindex msoft-float
+This option ignored; it is provided for compatibility purposes only.
+Software floating-point code is emitted by default, and this default
+can overridden by FPX options; @option{-mspfp}, @option{-mspfp-compact}, or
+@option{-mspfp-fast} for single precision, and @option{-mdpfp},
+@option{-mdpfp-compact}, or @option{-mdpfp-fast} for double precision.
+
+@item -mswap
+@opindex mswap
+Generate @code{swap} instructions.
+
+@item -matomic
+@opindex matomic
+This enables use of the locked load/store conditional extension to implement
+atomic memory built-in functions.  Not available for ARC 6xx or ARC
+EM cores.
+
+@item -mdiv-rem
+@opindex mdiv-rem
+Enable @code{div} and @code{rem} instructions for ARCv2 cores.
+
+@item -mcode-density
+@opindex mcode-density
+Enable code density instructions for ARC EM.  
+This option is on by default for ARC HS.
+
+@item -mll64
+@opindex mll64
+Enable double load/store operations for ARC HS cores.
+
+@item -mtp-regno=@var{regno}
+@opindex mtp-regno
+Specify thread pointer register number.
+
+@item -mmpy-option=@var{multo}
+@opindex mmpy-option
+Compile ARCv2 code with a multiplier design option.  You can specify 
+the option using either a string or numeric value for @var{multo}.  
+@samp{wlh1} is the default value.  The recognized values are:
+
+@table @samp
+@item 0
+@itemx none
+No multiplier available.
+
+@item 1
+@itemx w
+16x16 multiplier, fully pipelined.
+The following instructions are enabled: @code{mpyw} and @code{mpyuw}.
+
+@item 2
+@itemx wlh1
+32x32 multiplier, fully
+pipelined (1 stage).  The following instructions are additionally
+enabled: @code{mpy}, @code{mpyu}, @code{mpym}, @code{mpymu}, and @code{mpy_s}.
+
+@item 3
+@itemx wlh2
+32x32 multiplier, fully pipelined
+(2 stages).  The following instructions are additionally enabled: @code{mpy},
+@code{mpyu}, @code{mpym}, @code{mpymu}, and @code{mpy_s}.
+
+@item 4
+@itemx wlh3
+Two 16x16 multipliers, blocking,
+sequential.  The following instructions are additionally enabled: @code{mpy},
+@code{mpyu}, @code{mpym}, @code{mpymu}, and @code{mpy_s}.
+
+@item 5
+@itemx wlh4
+One 16x16 multiplier, blocking,
+sequential.  The following instructions are additionally enabled: @code{mpy},
+@code{mpyu}, @code{mpym}, @code{mpymu}, and @code{mpy_s}.
+
+@item 6
+@itemx wlh5
+One 32x4 multiplier, blocking,
+sequential.  The following instructions are additionally enabled: @code{mpy},
+@code{mpyu}, @code{mpym}, @code{mpymu}, and @code{mpy_s}.
+
+@item 7
+@itemx plus_dmpy
+ARC HS SIMD support.
+
+@item 8
+@itemx plus_macd
+ARC HS SIMD support.
+
+@item 9
+@itemx plus_qmacw
+ARC HS SIMD support.
+
+@end table
+
+This option is only available for ARCv2 cores@.
+
+@item -mfpu=@var{fpu}
+@opindex mfpu
+Enables support for specific floating-point hardware extensions for ARCv2
+cores.  Supported values for @var{fpu} are:
+
+@table @samp
+
+@item fpus
+Enables support for single-precision floating-point hardware
+extensions@.
+
+@item fpud
+Enables support for double-precision floating-point hardware
+extensions.  The single-precision floating-point extension is also
+enabled.  Not available for ARC EM@.
+
+@item fpuda
+Enables support for double-precision floating-point hardware
+extensions using double-precision assist instructions.  The single-precision
+floating-point extension is also enabled.  This option is
+only available for ARC EM@.
+
+@item fpuda_div
+Enables support for double-precision floating-point hardware
+extensions using double-precision assist instructions.
+The single-precision floating-point, square-root, and divide 
+extensions are also enabled.  This option is
+only available for ARC EM@.
+
+@item fpuda_fma
+Enables support for double-precision floating-point hardware
+extensions using double-precision assist instructions.
+The single-precision floating-point and fused multiply and add 
+hardware extensions are also enabled.  This option is
+only available for ARC EM@.
+
+@item fpuda_all
+Enables support for double-precision floating-point hardware
+extensions using double-precision assist instructions.
+All single-precision floating-point hardware extensions are also
+enabled.  This option is only available for ARC EM@.
+
+@item fpus_div
+Enables support for single-precision floating-point, square-root and divide 
+hardware extensions@.
+
+@item fpud_div
+Enables support for double-precision floating-point, square-root and divide 
+hardware extensions.  This option
+includes option @samp{fpus_div}. Not available for ARC EM@.
+
+@item fpus_fma
+Enables support for single-precision floating-point and 
+fused multiply and add hardware extensions@.
+
+@item fpud_fma
+Enables support for double-precision floating-point and 
+fused multiply and add hardware extensions.  This option
+includes option @samp{fpus_fma}.  Not available for ARC EM@.
+
+@item fpus_all
+Enables support for all single-precision floating-point hardware
+extensions@.
+
+@item fpud_all
+Enables support for all single- and double-precision floating-point
+hardware extensions.  Not available for ARC EM@.
+
+@end table
+
+@item -mirq-ctrl-saved=@var{register-range}, @var{blink}, @var{lp_count}
+@opindex mirq-ctrl-saved
+Specifies general-purposes registers that the processor automatically
+saves/restores on interrupt entry and exit.  @var{register-range} is
+specified as two registers separated by a dash.  The register range
+always starts with @code{r0}, the upper limit is @code{fp} register.
+@var{blink} and @var{lp_count} are optional.  This option is only
+valid for ARC EM and ARC HS cores.
+
+@item -mrgf-banked-regs=@var{number}
+@opindex mrgf-banked-regs
+Specifies the number of registers replicated in second register bank
+on entry to fast interrupt.  Fast interrupts are interrupts with the
+highest priority level P0.  These interrupts save only PC and STATUS32
+registers to avoid memory transactions during interrupt entry and exit
+sequences.  Use this option when you are using fast interrupts in an
+ARC V2 family processor.  Permitted values are 4, 8, 16, and 32.
+
+@item -mlpc-width=@var{width}
+@opindex mlpc-width
+Specify the width of the @code{lp_count} register.  Valid values for
+@var{width} are 8, 16, 20, 24, 28 and 32 bits.  The default width is
+fixed to 32 bits.  If the width is less than 32, the compiler does not
+attempt to transform loops in your program to use the zero-delay loop
+mechanism unless it is known that the @code{lp_count} register can
+hold the required loop-counter value.  Depending on the width
+specified, the compiler and run-time library might continue to use the
+loop mechanism for various needs.  This option defines macro
+@code{__ARC_LPC_WIDTH__} with the value of @var{width}.
+
+@item -mrf16
+@opindex mrf16
+This option instructs the compiler to generate code for a 16-entry
+register file.  This option defines the @code{__ARC_RF16__}
+preprocessor macro.
+
+@item -mbranch-index
+@opindex mbranch-index
+Enable use of @code{bi} or @code{bih} instructions to implement jump
+tables.
+
+@end table
+
+The following options are passed through to the assembler, and also
+define preprocessor macro symbols.
+
+@c Flags used by the assembler, but for which we define preprocessor
+@c macro symbols as well.
+@table @gcctabopt
+@item -mdsp-packa
+@opindex mdsp-packa
+Passed down to the assembler to enable the DSP Pack A extensions.
+Also sets the preprocessor symbol @code{__Xdsp_packa}.  This option is
+deprecated.
+
+@item -mdvbf
+@opindex mdvbf
+Passed down to the assembler to enable the dual Viterbi butterfly
+extension.  Also sets the preprocessor symbol @code{__Xdvbf}.  This
+option is deprecated.
+
+@c ARC700 4.10 extension instruction
+@item -mlock
+@opindex mlock
+Passed down to the assembler to enable the locked load/store
+conditional extension.  Also sets the preprocessor symbol
+@code{__Xlock}.
+
+@item -mmac-d16
+@opindex mmac-d16
+Passed down to the assembler.  Also sets the preprocessor symbol
+@code{__Xxmac_d16}.  This option is deprecated.
+
+@item -mmac-24
+@opindex mmac-24
+Passed down to the assembler.  Also sets the preprocessor symbol
+@code{__Xxmac_24}.  This option is deprecated.
+
+@c ARC700 4.10 extension instruction
+@item -mrtsc
+@opindex mrtsc
+Passed down to the assembler to enable the 64-bit time-stamp counter
+extension instruction.  Also sets the preprocessor symbol
+@code{__Xrtsc}.  This option is deprecated.
+
+@c ARC700 4.10 extension instruction
+@item -mswape
+@opindex mswape
+Passed down to the assembler to enable the swap byte ordering
+extension instruction.  Also sets the preprocessor symbol
+@code{__Xswape}.
+
+@item -mtelephony
+@opindex mtelephony
+Passed down to the assembler to enable dual- and single-operand
+instructions for telephony.  Also sets the preprocessor symbol
+@code{__Xtelephony}.  This option is deprecated.
+
+@item -mxy
+@opindex mxy
+Passed down to the assembler to enable the XY memory extension.  Also
+sets the preprocessor symbol @code{__Xxy}.
+
+@end table
+
+The following options control how the assembly code is annotated:
+
+@c Assembly annotation options
+@table @gcctabopt
+@item -misize
+@opindex misize
+Annotate assembler instructions with estimated addresses.
+
+@item -mannotate-align
+@opindex mannotate-align
+Explain what alignment considerations lead to the decision to make an
+instruction short or long.
+
+@end table
+
+The following options are passed through to the linker:
+
+@c options passed through to the linker
+@table @gcctabopt
+@item -marclinux
+@opindex marclinux
+Passed through to the linker, to specify use of the @code{arclinux} emulation.
+This option is enabled by default in tool chains built for
+@w{@code{arc-linux-uclibc}} and @w{@code{arceb-linux-uclibc}} targets
+when profiling is not requested.
+
+@item -marclinux_prof
+@opindex marclinux_prof
+Passed through to the linker, to specify use of the
+@code{arclinux_prof} emulation.  This option is enabled by default in
+tool chains built for @w{@code{arc-linux-uclibc}} and
+@w{@code{arceb-linux-uclibc}} targets when profiling is requested.
+
+@end table
+
+The following options control the semantics of generated code:
+
+@c semantically relevant code generation options
+@table @gcctabopt
+@item -mlong-calls
+@opindex mlong-calls
+Generate calls as register indirect calls, thus providing access
+to the full 32-bit address range.
+
+@item -mmedium-calls
+@opindex mmedium-calls
+Don't use less than 25-bit addressing range for calls, which is the
+offset available for an unconditional branch-and-link
+instruction.  Conditional execution of function calls is suppressed, to
+allow use of the 25-bit range, rather than the 21-bit range with
+conditional branch-and-link.  This is the default for tool chains built
+for @w{@code{arc-linux-uclibc}} and @w{@code{arceb-linux-uclibc}} targets.
+
+@item -G @var{num}
+@opindex G
+Put definitions of externally-visible data in a small data section if
+that data is no bigger than @var{num} bytes.  The default value of
+@var{num} is 4 for any ARC configuration, or 8 when we have double
+load/store operations.
+
+@item -mno-sdata
+@opindex mno-sdata
+@opindex msdata
+Do not generate sdata references.  This is the default for tool chains
+built for @w{@code{arc-linux-uclibc}} and @w{@code{arceb-linux-uclibc}}
+targets.
+
+@item -mvolatile-cache
+@opindex mvolatile-cache
+Use ordinarily cached memory accesses for volatile references.  This is the
+default.
+
+@item -mno-volatile-cache
+@opindex mno-volatile-cache
+@opindex mvolatile-cache
+Enable cache bypass for volatile references.
+
+@end table
+
+The following options fine tune code generation:
+@c code generation tuning options
+@table @gcctabopt
+@item -malign-call
+@opindex malign-call
+Does nothing.  Preserved for backward compatibility.
+
+@item -mauto-modify-reg
+@opindex mauto-modify-reg
+Enable the use of pre/post modify with register displacement.
+
+@item -mbbit-peephole
+@opindex mbbit-peephole
+Enable bbit peephole2.
+
+@item -mno-brcc
+@opindex mno-brcc
+This option disables a target-specific pass in @file{arc_reorg} to
+generate compare-and-branch (@code{br@var{cc}}) instructions.  
+It has no effect on
+generation of these instructions driven by the combiner pass.
+
+@item -mcase-vector-pcrel
+@opindex mcase-vector-pcrel
+Use PC-relative switch case tables to enable case table shortening.
+This is the default for @option{-Os}.
+
+@item -mcompact-casesi
+@opindex mcompact-casesi
+Enable compact @code{casesi} pattern.  This is the default for @option{-Os},
+and only available for ARCv1 cores.  This option is deprecated.
+
+@item -mno-cond-exec
+@opindex mno-cond-exec
+Disable the ARCompact-specific pass to generate conditional 
+execution instructions.
+
+Due to delay slot scheduling and interactions between operand numbers,
+literal sizes, instruction lengths, and the support for conditional execution,
+the target-independent pass to generate conditional execution is often lacking,
+so the ARC port has kept a special pass around that tries to find more
+conditional execution generation opportunities after register allocation,
+branch shortening, and delay slot scheduling have been done.  This pass
+generally, but not always, improves performance and code size, at the cost of
+extra compilation time, which is why there is an option to switch it off.
+If you have a problem with call instructions exceeding their allowable
+offset range because they are conditionalized, you should consider using
+@option{-mmedium-calls} instead.
+
+@item -mearly-cbranchsi
+@opindex mearly-cbranchsi
+Enable pre-reload use of the @code{cbranchsi} pattern.
+
+@item -mexpand-adddi
+@opindex mexpand-adddi
+Expand @code{adddi3} and @code{subdi3} at RTL generation time into
+@code{add.f}, @code{adc} etc.  This option is deprecated.
+
+@item -mindexed-loads
+@opindex mindexed-loads
+Enable the use of indexed loads.  This can be problematic because some
+optimizers then assume that indexed stores exist, which is not
+the case.
+
+@item -mlra
+@opindex mlra
+Enable Local Register Allocation.  This is still experimental for ARC,
+so by default the compiler uses standard reload
+(i.e.@: @option{-mno-lra}).
+
+@item -mlra-priority-none
+@opindex mlra-priority-none
+Don't indicate any priority for target registers.
+
+@item -mlra-priority-compact
+@opindex mlra-priority-compact
+Indicate target register priority for r0..r3 / r12..r15.
+
+@item -mlra-priority-noncompact
+@opindex mlra-priority-noncompact
+Reduce target register priority for r0..r3 / r12..r15.
+
+@item -mmillicode
+@opindex mmillicode
+When optimizing for size (using @option{-Os}), prologues and epilogues
+that have to save or restore a large number of registers are often
+shortened by using call to a special function in libgcc; this is
+referred to as a @emph{millicode} call.  As these calls can pose
+performance issues, and/or cause linking issues when linking in a
+nonstandard way, this option is provided to turn on or off millicode
+call generation.
+
+@item -mcode-density-frame
+@opindex mcode-density-frame
+This option enable the compiler to emit @code{enter} and @code{leave}
+instructions.  These instructions are only valid for CPUs with
+code-density feature.
+
+@item -mmixed-code
+@opindex mmixed-code
+Does nothing.  Preserved for backward compatibility.
+
+@item -mq-class
+@opindex mq-class
+Ths option is deprecated.  Enable @samp{q} instruction alternatives.
+This is the default for @option{-Os}.
+
+@item -mRcq
+@opindex mRcq
+Does nothing.  Preserved for backward compatibility.
+
+@item -mRcw
+@opindex mRcw
+Does nothing.  Preserved for backward compatibility.
+
+@item -msize-level=@var{level}
+@opindex msize-level
+Fine-tune size optimization with regards to instruction lengths and alignment.
+The recognized values for @var{level} are:
+@table @samp
+@item 0
+No size optimization.  This level is deprecated and treated like @samp{1}.
+
+@item 1
+Short instructions are used opportunistically.
+
+@item 2
+In addition, alignment of loops and of code after barriers are dropped.
+
+@item 3
+In addition, optional data alignment is dropped, and the option @option{Os} is enabled.
+
+@end table
+
+This defaults to @samp{3} when @option{-Os} is in effect.  Otherwise,
+the behavior when this is not set is equivalent to level @samp{1}.
+
+@item -mtune=@var{cpu}
+@opindex mtune
+Set instruction scheduling parameters for @var{cpu}, overriding any implied
+by @option{-mcpu=}.
+
+Supported values for @var{cpu} are
+
+@table @samp
+@item ARC600
+Tune for ARC600 CPU.
+
+@item ARC601
+Tune for ARC601 CPU.
+
+@item ARC700
+Tune for ARC700 CPU with standard multiplier block.
+
+@item ARC700-xmac
+Tune for ARC700 CPU with XMAC block.
+
+@item ARC725D
+Tune for ARC725D CPU.
+
+@item ARC750D
+Tune for ARC750D CPU.
+
+@item core3
+Tune for ARCv2 core3 type CPU.  This option enable usage of
+@code{dbnz} instruction.
+
+@item release31a
+Tune for ARC4x release 3.10a.
+
+@end table
+
+@item -mmultcost=@var{num}
+@opindex mmultcost
+Cost to assume for a multiply instruction, with @samp{4} being equal to a
+normal instruction.
+
+@item -munalign-prob-threshold=@var{probability}
+@opindex munalign-prob-threshold
+Does nothing.  Preserved for backward compatibility.
+
+@end table
+
+The following options are maintained for backward compatibility, but
+are now deprecated and will be removed in a future release:
+
+@c Deprecated options
+@table @gcctabopt
+
+@item -margonaut
+@opindex margonaut
+Obsolete FPX.
+
+@item -mbig-endian
+@opindex mbig-endian
+@itemx -EB
+@opindex EB
+Compile code for big-endian targets.  Use of these options is now
+deprecated.  Big-endian code is supported by configuring GCC to build
+@w{@code{arceb-elf32}} and @w{@code{arceb-linux-uclibc}} targets,
+for which big endian is the default.
+
+@item -mlittle-endian
+@opindex mlittle-endian
+@itemx -EL
+@opindex EL
+Compile code for little-endian targets.  Use of these options is now
+deprecated.  Little-endian code is supported by configuring GCC to build 
+@w{@code{arc-elf32}} and @w{@code{arc-linux-uclibc}} targets,
+for which little endian is the default.
+
+@item -mbarrel_shifter
+@opindex mbarrel_shifter
+Replaced by @option{-mbarrel-shifter}.
+
+@item -mdpfp_compact
+@opindex mdpfp_compact
+Replaced by @option{-mdpfp-compact}.
+
+@item -mdpfp_fast
+@opindex mdpfp_fast
+Replaced by @option{-mdpfp-fast}.
+
+@item -mdsp_packa
+@opindex mdsp_packa
+Replaced by @option{-mdsp-packa}.
+
+@item -mEA
+@opindex mEA
+Replaced by @option{-mea}.
+
+@item -mmac_24
+@opindex mmac_24
+Replaced by @option{-mmac-24}.
+
+@item -mmac_d16
+@opindex mmac_d16
+Replaced by @option{-mmac-d16}.
+
+@item -mspfp_compact
+@opindex mspfp_compact
+Replaced by @option{-mspfp-compact}.
+
+@item -mspfp_fast
+@opindex mspfp_fast
+Replaced by @option{-mspfp-fast}.
+
+@item -mtune=@var{cpu}
+@opindex mtune
+Values @samp{arc600}, @samp{arc601}, @samp{arc700} and
+@samp{arc700-xmac} for @var{cpu} are replaced by @samp{ARC600},
+@samp{ARC601}, @samp{ARC700} and @samp{ARC700-xmac} respectively.
+
+@item -multcost=@var{num}
+@opindex multcost
+Replaced by @option{-mmultcost}.
+
+@end table
+
+@node ARM Options
+@subsection ARM Options
+@cindex ARM options
+
+These @samp{-m} options are defined for the ARM port:
+
+@table @gcctabopt
+@item -mabi=@var{name}
+@opindex mabi
+Generate code for the specified ABI@.  Permissible values are: @samp{apcs-gnu},
+@samp{atpcs}, @samp{aapcs}, @samp{aapcs-linux} and @samp{iwmmxt}.
+
+@item -mapcs-frame
+@opindex mapcs-frame
+Generate a stack frame that is compliant with the ARM Procedure Call
+Standard for all functions, even if this is not strictly necessary for
+correct execution of the code.  Specifying @option{-fomit-frame-pointer}
+with this option causes the stack frames not to be generated for
+leaf functions.  The default is @option{-mno-apcs-frame}.
+This option is deprecated.
+
+@item -mapcs
+@opindex mapcs
+This is a synonym for @option{-mapcs-frame} and is deprecated.
+
+@ignore
+@c not currently implemented
+@item -mapcs-stack-check
+@opindex mapcs-stack-check
+Generate code to check the amount of stack space available upon entry to
+every function (that actually uses some stack space).  If there is
+insufficient space available then either the function
+@code{__rt_stkovf_split_small} or @code{__rt_stkovf_split_big} is
+called, depending upon the amount of stack space required.  The runtime
+system is required to provide these functions.  The default is
+@option{-mno-apcs-stack-check}, since this produces smaller code.
+
+@c not currently implemented
+@item -mapcs-reentrant
+@opindex mapcs-reentrant
+Generate reentrant, position-independent code.  The default is
+@option{-mno-apcs-reentrant}.
+@end ignore
+
+@item -mthumb-interwork
+@opindex mthumb-interwork
+Generate code that supports calling between the ARM and Thumb
+instruction sets.  Without this option, on pre-v5 architectures, the
+two instruction sets cannot be reliably used inside one program.  The
+default is @option{-mno-thumb-interwork}, since slightly larger code
+is generated when @option{-mthumb-interwork} is specified.  In AAPCS
+configurations this option is meaningless.
+
+@item -mno-sched-prolog
+@opindex mno-sched-prolog
+@opindex msched-prolog
+Prevent the reordering of instructions in the function prologue, or the
+merging of those instruction with the instructions in the function's
+body.  This means that all functions start with a recognizable set
+of instructions (or in fact one of a choice from a small set of
+different function prologues), and this information can be used to
+locate the start of functions inside an executable piece of code.  The
+default is @option{-msched-prolog}.
+
+@item -mfloat-abi=@var{name}
+@opindex mfloat-abi
+Specifies which floating-point ABI to use.  Permissible values
+are: @samp{soft}, @samp{softfp} and @samp{hard}.
+
+Specifying @samp{soft} causes GCC to generate output containing
+library calls for floating-point operations.
+@samp{softfp} allows the generation of code using hardware floating-point
+instructions, but still uses the soft-float calling conventions.
+@samp{hard} allows generation of floating-point instructions
+and uses FPU-specific calling conventions.
+
+The default depends on the specific target configuration.  Note that
+the hard-float and soft-float ABIs are not link-compatible; you must
+compile your entire program with the same ABI, and link with a
+compatible set of libraries.
+
+@item -mgeneral-regs-only
+@opindex mgeneral-regs-only
+Generate code which uses only the general-purpose registers.  This will prevent
+the compiler from using floating-point and Advanced SIMD registers but will not
+impose any restrictions on the assembler.
+
+@item -mlittle-endian
+@opindex mlittle-endian
+Generate code for a processor running in little-endian mode.  This is
+the default for all standard configurations.
+
+@item -mbig-endian
+@opindex mbig-endian
+Generate code for a processor running in big-endian mode; the default is
+to compile code for a little-endian processor.
+
+@item -mbe8
+@itemx -mbe32
+@opindex mbe8
+When linking a big-endian image select between BE8 and BE32 formats.
+The option has no effect for little-endian images and is ignored.  The
+default is dependent on the selected target architecture.  For ARMv6
+and later architectures the default is BE8, for older architectures
+the default is BE32.  BE32 format has been deprecated by ARM.
+
+@item -march=@var{name}@r{[}+extension@dots{}@r{]}
+@opindex march
+This specifies the name of the target ARM architecture.  GCC uses this
+name to determine what kind of instructions it can emit when generating
+assembly code.  This option can be used in conjunction with or instead
+of the @option{-mcpu=} option.
+
+Permissible names are:
+@samp{armv4t},
+@samp{armv5t}, @samp{armv5te},
+@samp{armv6}, @samp{armv6j}, @samp{armv6k}, @samp{armv6kz}, @samp{armv6t2},
+@samp{armv6z}, @samp{armv6zk},
+@samp{armv7}, @samp{armv7-a}, @samp{armv7ve}, 
+@samp{armv8-a}, @samp{armv8.1-a}, @samp{armv8.2-a}, @samp{armv8.3-a},
+@samp{armv8.4-a},
+@samp{armv8.5-a},
+@samp{armv8.6-a},
+@samp{armv9-a},
+@samp{armv7-r},
+@samp{armv8-r},
+@samp{armv6-m}, @samp{armv6s-m},
+@samp{armv7-m}, @samp{armv7e-m},
+@samp{armv8-m.base}, @samp{armv8-m.main},
+@samp{armv8.1-m.main},
+@samp{armv9-a},
+@samp{iwmmxt} and @samp{iwmmxt2}.
+
+Additionally, the following architectures, which lack support for the
+Thumb execution state, are recognized but support is deprecated: @samp{armv4}.
+
+Many of the architectures support extensions.  These can be added by
+appending @samp{+@var{extension}} to the architecture name.  Extension
+options are processed in order and capabilities accumulate.  An extension
+will also enable any necessary base extensions
+upon which it depends.  For example, the @samp{+crypto} extension
+will always enable the @samp{+simd} extension.  The exception to the
+additive construction is for extensions that are prefixed with
+@samp{+no@dots{}}: these extensions disable the specified option and
+any other extensions that may depend on the presence of that
+extension.
+
+For example, @samp{-march=armv7-a+simd+nofp+vfpv4} is equivalent to
+writing @samp{-march=armv7-a+vfpv4} since the @samp{+simd} option is
+entirely disabled by the @samp{+nofp} option that follows it.
+
+Most extension names are generically named, but have an effect that is
+dependent upon the architecture to which it is applied.  For example,
+the @samp{+simd} option can be applied to both @samp{armv7-a} and
+@samp{armv8-a} architectures, but will enable the original ARMv7-A
+Advanced SIMD (Neon) extensions for @samp{armv7-a} and the ARMv8-A
+variant for @samp{armv8-a}.
+
+The table below lists the supported extensions for each architecture.
+Architectures not mentioned do not support any extensions.
+
+@table @samp
+@item armv5te
+@itemx armv6
+@itemx armv6j
+@itemx armv6k
+@itemx armv6kz
+@itemx armv6t2
+@itemx armv6z
+@itemx armv6zk
+@table @samp
+@item +fp
+The VFPv2 floating-point instructions.  The extension @samp{+vfpv2} can be
+used as an alias for this extension.
+
+@item +nofp
+Disable the floating-point instructions.
+@end table
+
+@item armv7
+The common subset of the ARMv7-A, ARMv7-R and ARMv7-M architectures.
+@table @samp
+@item +fp
+The VFPv3 floating-point instructions, with 16 double-precision
+registers.  The extension @samp{+vfpv3-d16} can be used as an alias
+for this extension.  Note that floating-point is not supported by the
+base ARMv7-M architecture, but is compatible with both the ARMv7-A and
+ARMv7-R architectures.
+
+@item +nofp
+Disable the floating-point instructions.
+@end table
+
+@item armv7-a
+@table @samp
+@item +mp
+The multiprocessing extension.
+
+@item +sec
+The security extension.
+
+@item +fp
+The VFPv3 floating-point instructions, with 16 double-precision
+registers.  The extension @samp{+vfpv3-d16} can be used as an alias
+for this extension.
+
+@item +simd
+The Advanced SIMD (Neon) v1 and the VFPv3 floating-point instructions.
+The extensions @samp{+neon} and @samp{+neon-vfpv3} can be used as aliases
+for this extension.
+
+@item +vfpv3
+The VFPv3 floating-point instructions, with 32 double-precision
+registers.
+
+@item +vfpv3-d16-fp16
+The VFPv3 floating-point instructions, with 16 double-precision
+registers and the half-precision floating-point conversion operations.
+
+@item +vfpv3-fp16
+The VFPv3 floating-point instructions, with 32 double-precision
+registers and the half-precision floating-point conversion operations.
+
+@item +vfpv4-d16
+The VFPv4 floating-point instructions, with 16 double-precision
+registers.
+
+@item +vfpv4
+The VFPv4 floating-point instructions, with 32 double-precision
+registers.
+
+@item +neon-fp16
+The Advanced SIMD (Neon) v1 and the VFPv3 floating-point instructions, with
+the half-precision floating-point conversion operations.
+
+@item +neon-vfpv4
+The Advanced SIMD (Neon) v2 and the VFPv4 floating-point instructions.
+
+@item +nosimd
+Disable the Advanced SIMD instructions (does not disable floating point).
+
+@item +nofp
+Disable the floating-point and Advanced SIMD instructions.
+@end table
+
+@item armv7ve
+The extended version of the ARMv7-A architecture with support for
+virtualization.
+@table @samp
+@item +fp
+The VFPv4 floating-point instructions, with 16 double-precision registers.
+The extension @samp{+vfpv4-d16} can be used as an alias for this extension.
+
+@item +simd
+The Advanced SIMD (Neon) v2 and the VFPv4 floating-point instructions.  The
+extension @samp{+neon-vfpv4} can be used as an alias for this extension.
+
+@item +vfpv3-d16
+The VFPv3 floating-point instructions, with 16 double-precision
+registers.
+
+@item +vfpv3
+The VFPv3 floating-point instructions, with 32 double-precision
+registers.
+
+@item +vfpv3-d16-fp16
+The VFPv3 floating-point instructions, with 16 double-precision
+registers and the half-precision floating-point conversion operations.
+
+@item +vfpv3-fp16
+The VFPv3 floating-point instructions, with 32 double-precision
+registers and the half-precision floating-point conversion operations.
+
+@item +vfpv4-d16
+The VFPv4 floating-point instructions, with 16 double-precision
+registers.
+
+@item +vfpv4
+The VFPv4 floating-point instructions, with 32 double-precision
+registers.
+
+@item +neon
+The Advanced SIMD (Neon) v1 and the VFPv3 floating-point instructions.
+The extension @samp{+neon-vfpv3} can be used as an alias for this extension.
+
+@item +neon-fp16
+The Advanced SIMD (Neon) v1 and the VFPv3 floating-point instructions, with
+the half-precision floating-point conversion operations.
+
+@item +nosimd
+Disable the Advanced SIMD instructions (does not disable floating point).
+
+@item +nofp
+Disable the floating-point and Advanced SIMD instructions.
+@end table
+
+@item armv8-a
+@table @samp
+@item +crc
+The Cyclic Redundancy Check (CRC) instructions.
+@item +simd
+The ARMv8-A Advanced SIMD and floating-point instructions.
+@item +crypto
+The cryptographic instructions.
+@item +nocrypto
+Disable the cryptographic instructions.
+@item +nofp
+Disable the floating-point, Advanced SIMD and cryptographic instructions.
+@item +sb
+Speculation Barrier Instruction.
+@item +predres
+Execution and Data Prediction Restriction Instructions.
+@end table
+
+@item armv8.1-a
+@table @samp
+@item +simd
+The ARMv8.1-A Advanced SIMD and floating-point instructions.
+
+@item +crypto
+The cryptographic instructions.  This also enables the Advanced SIMD and
+floating-point instructions.
+
+@item +nocrypto
+Disable the cryptographic instructions.
+
+@item +nofp
+Disable the floating-point, Advanced SIMD and cryptographic instructions.
+
+@item +sb
+Speculation Barrier Instruction.
+
+@item +predres
+Execution and Data Prediction Restriction Instructions.
+@end table
+
+@item armv8.2-a
+@itemx armv8.3-a
+@table @samp
+@item +fp16
+The half-precision floating-point data processing instructions.
+This also enables the Advanced SIMD and floating-point instructions.
+
+@item +fp16fml
+The half-precision floating-point fmla extension.  This also enables
+the half-precision floating-point extension and Advanced SIMD and
+floating-point instructions.
+
+@item +simd
+The ARMv8.1-A Advanced SIMD and floating-point instructions.
+
+@item +crypto
+The cryptographic instructions.  This also enables the Advanced SIMD and
+floating-point instructions.
+
+@item +dotprod
+Enable the Dot Product extension.  This also enables Advanced SIMD instructions.
+
+@item +nocrypto
+Disable the cryptographic extension.
+
+@item +nofp
+Disable the floating-point, Advanced SIMD and cryptographic instructions.
+
+@item +sb
+Speculation Barrier Instruction.
+
+@item +predres
+Execution and Data Prediction Restriction Instructions.
+
+@item +i8mm
+8-bit Integer Matrix Multiply instructions.
+This also enables Advanced SIMD and floating-point instructions.
+
+@item +bf16
+Brain half-precision floating-point instructions.
+This also enables Advanced SIMD and floating-point instructions.
+@end table
+
+@item armv8.4-a
+@table @samp
+@item +fp16
+The half-precision floating-point data processing instructions.
+This also enables the Advanced SIMD and floating-point instructions as well
+as the Dot Product extension and the half-precision floating-point fmla
+extension.
+
+@item +simd
+The ARMv8.3-A Advanced SIMD and floating-point instructions as well as the
+Dot Product extension.
+
+@item +crypto
+The cryptographic instructions.  This also enables the Advanced SIMD and
+floating-point instructions as well as the Dot Product extension.
+
+@item +nocrypto
+Disable the cryptographic extension.
+
+@item +nofp
+Disable the floating-point, Advanced SIMD and cryptographic instructions.
+
+@item +sb
+Speculation Barrier Instruction.
+
+@item +predres
+Execution and Data Prediction Restriction Instructions.
+
+@item +i8mm
+8-bit Integer Matrix Multiply instructions.
+This also enables Advanced SIMD and floating-point instructions.
+
+@item +bf16
+Brain half-precision floating-point instructions.
+This also enables Advanced SIMD and floating-point instructions.
+@end table
+
+@item armv8.5-a
+@table @samp
+@item +fp16
+The half-precision floating-point data processing instructions.
+This also enables the Advanced SIMD and floating-point instructions as well
+as the Dot Product extension and the half-precision floating-point fmla
+extension.
+
+@item +simd
+The ARMv8.3-A Advanced SIMD and floating-point instructions as well as the
+Dot Product extension.
+
+@item +crypto
+The cryptographic instructions.  This also enables the Advanced SIMD and
+floating-point instructions as well as the Dot Product extension.
+
+@item +nocrypto
+Disable the cryptographic extension.
+
+@item +nofp
+Disable the floating-point, Advanced SIMD and cryptographic instructions.
+
+@item +i8mm
+8-bit Integer Matrix Multiply instructions.
+This also enables Advanced SIMD and floating-point instructions.
+
+@item +bf16
+Brain half-precision floating-point instructions.
+This also enables Advanced SIMD and floating-point instructions.
+@end table
+
+@item armv8.6-a
+@table @samp
+@item +fp16
+The half-precision floating-point data processing instructions.
+This also enables the Advanced SIMD and floating-point instructions as well
+as the Dot Product extension and the half-precision floating-point fmla
+extension.
+
+@item +simd
+The ARMv8.3-A Advanced SIMD and floating-point instructions as well as the
+Dot Product extension.
+
+@item +crypto
+The cryptographic instructions.  This also enables the Advanced SIMD and
+floating-point instructions as well as the Dot Product extension.
+
+@item +nocrypto
+Disable the cryptographic extension.
+
+@item +nofp
+Disable the floating-point, Advanced SIMD and cryptographic instructions.
+
+@item +i8mm
+8-bit Integer Matrix Multiply instructions.
+This also enables Advanced SIMD and floating-point instructions.
+
+@item +bf16
+Brain half-precision floating-point instructions.
+This also enables Advanced SIMD and floating-point instructions.
+@end table
+
+@item armv7-r
+@table @samp
+@item +fp.sp
+The single-precision VFPv3 floating-point instructions.  The extension
+@samp{+vfpv3xd} can be used as an alias for this extension.
+
+@item +fp
+The VFPv3 floating-point instructions with 16 double-precision registers.
+The extension +vfpv3-d16 can be used as an alias for this extension.
+
+@item +vfpv3xd-d16-fp16
+The single-precision VFPv3 floating-point instructions with 16 double-precision
+registers and the half-precision floating-point conversion operations.
+
+@item +vfpv3-d16-fp16
+The VFPv3 floating-point instructions with 16 double-precision
+registers and the half-precision floating-point conversion operations.
+
+@item +nofp
+Disable the floating-point extension.
+
+@item +idiv
+The ARM-state integer division instructions.
+
+@item +noidiv
+Disable the ARM-state integer division extension.
+@end table
+
+@item armv7e-m
+@table @samp
+@item +fp
+The single-precision VFPv4 floating-point instructions.
+
+@item +fpv5
+The single-precision FPv5 floating-point instructions.
+
+@item +fp.dp
+The single- and double-precision FPv5 floating-point instructions.
+
+@item +nofp
+Disable the floating-point extensions.
+@end table
+
+@item  armv8.1-m.main
+@table @samp
+
+@item +dsp
+The DSP instructions.
+
+@item +mve
+The M-Profile Vector Extension (MVE) integer instructions.
+
+@item +mve.fp
+The M-Profile Vector Extension (MVE) integer and single precision
+floating-point instructions.
+
+@item +fp
+The single-precision floating-point instructions.
+
+@item +fp.dp
+The single- and double-precision floating-point instructions.
+
+@item +nofp
+Disable the floating-point extension.
+
+@item +cdecp0, +cdecp1, ... , +cdecp7
+Enable the Custom Datapath Extension (CDE) on selected coprocessors according
+to the numbers given in the options in the range 0 to 7.
+@end table
+
+@item  armv8-m.main
+@table @samp
+@item +dsp
+The DSP instructions.
+
+@item +nodsp
+Disable the DSP extension.
+
+@item +fp
+The single-precision floating-point instructions.
+
+@item +fp.dp
+The single- and double-precision floating-point instructions.
+
+@item +nofp
+Disable the floating-point extension.
+
+@item +cdecp0, +cdecp1, ... , +cdecp7
+Enable the Custom Datapath Extension (CDE) on selected coprocessors according
+to the numbers given in the options in the range 0 to 7.
+@end table
+
+@item armv8-r
+@table @samp
+@item +crc
+The Cyclic Redundancy Check (CRC) instructions.
+@item +fp.sp
+The single-precision FPv5 floating-point instructions.
+@item +simd
+The ARMv8-A Advanced SIMD and floating-point instructions.
+@item +crypto
+The cryptographic instructions.
+@item +nocrypto
+Disable the cryptographic instructions.
+@item +nofp
+Disable the floating-point, Advanced SIMD and cryptographic instructions.
+@end table
+
+@end table
+
+@option{-march=native} causes the compiler to auto-detect the architecture
+of the build computer.  At present, this feature is only supported on
+GNU/Linux, and not all architectures are recognized.  If the auto-detect
+is unsuccessful the option has no effect.
+
+@item -mtune=@var{name}
+@opindex mtune
+This option specifies the name of the target ARM processor for
+which GCC should tune the performance of the code.
+For some ARM implementations better performance can be obtained by using
+this option.
+Permissible names are: @samp{arm7tdmi}, @samp{arm7tdmi-s}, @samp{arm710t},
+@samp{arm720t}, @samp{arm740t}, @samp{strongarm}, @samp{strongarm110},
+@samp{strongarm1100}, @samp{strongarm1110}, @samp{arm8}, @samp{arm810},
+@samp{arm9}, @samp{arm9e}, @samp{arm920}, @samp{arm920t}, @samp{arm922t},
+@samp{arm946e-s}, @samp{arm966e-s}, @samp{arm968e-s}, @samp{arm926ej-s},
+@samp{arm940t}, @samp{arm9tdmi}, @samp{arm10tdmi}, @samp{arm1020t},
+@samp{arm1026ej-s}, @samp{arm10e}, @samp{arm1020e}, @samp{arm1022e},
+@samp{arm1136j-s}, @samp{arm1136jf-s}, @samp{mpcore}, @samp{mpcorenovfp},
+@samp{arm1156t2-s}, @samp{arm1156t2f-s}, @samp{arm1176jz-s}, @samp{arm1176jzf-s},
+@samp{generic-armv7-a}, @samp{cortex-a5}, @samp{cortex-a7}, @samp{cortex-a8},
+@samp{cortex-a9}, @samp{cortex-a12}, @samp{cortex-a15}, @samp{cortex-a17},
+@samp{cortex-a32}, @samp{cortex-a35}, @samp{cortex-a53}, @samp{cortex-a55},
+@samp{cortex-a57}, @samp{cortex-a72}, @samp{cortex-a73}, @samp{cortex-a75},
+@samp{cortex-a76}, @samp{cortex-a76ae}, @samp{cortex-a77},
+@samp{cortex-a78}, @samp{cortex-a78ae}, @samp{cortex-a78c}, @samp{cortex-a710},
+@samp{ares}, @samp{cortex-r4}, @samp{cortex-r4f}, @samp{cortex-r5},
+@samp{cortex-r7}, @samp{cortex-r8}, @samp{cortex-r52}, @samp{cortex-r52plus},
+@samp{cortex-m0}, @samp{cortex-m0plus}, @samp{cortex-m1}, @samp{cortex-m3},
+@samp{cortex-m4}, @samp{cortex-m7}, @samp{cortex-m23}, @samp{cortex-m33},
+@samp{cortex-m35p}, @samp{cortex-m55}, @samp{cortex-x1},
+@samp{cortex-m1.small-multiply}, @samp{cortex-m0.small-multiply},
+@samp{cortex-m0plus.small-multiply}, @samp{exynos-m1}, @samp{marvell-pj4},
+@samp{neoverse-n1}, @samp{neoverse-n2}, @samp{neoverse-v1}, @samp{xscale},
+@samp{iwmmxt}, @samp{iwmmxt2}, @samp{ep9312}, @samp{fa526}, @samp{fa626},
+@samp{fa606te}, @samp{fa626te}, @samp{fmp626}, @samp{fa726te}, @samp{star-mc1},
+@samp{xgene1}.
+
+Additionally, this option can specify that GCC should tune the performance
+of the code for a big.LITTLE system.  Permissible names are:
+@samp{cortex-a15.cortex-a7}, @samp{cortex-a17.cortex-a7},
+@samp{cortex-a57.cortex-a53}, @samp{cortex-a72.cortex-a53},
+@samp{cortex-a72.cortex-a35}, @samp{cortex-a73.cortex-a53},
+@samp{cortex-a75.cortex-a55}, @samp{cortex-a76.cortex-a55}.
+
+@option{-mtune=generic-@var{arch}} specifies that GCC should tune the
+performance for a blend of processors within architecture @var{arch}.
+The aim is to generate code that run well on the current most popular
+processors, balancing between optimizations that benefit some CPUs in the
+range, and avoiding performance pitfalls of other CPUs.  The effects of
+this option may change in future GCC versions as CPU models come and go.
+
+@option{-mtune} permits the same extension options as @option{-mcpu}, but
+the extension options do not affect the tuning of the generated code.
+
+@option{-mtune=native} causes the compiler to auto-detect the CPU
+of the build computer.  At present, this feature is only supported on
+GNU/Linux, and not all architectures are recognized.  If the auto-detect is
+unsuccessful the option has no effect.
+
+@item -mcpu=@var{name}@r{[}+extension@dots{}@r{]}
+@opindex mcpu
+This specifies the name of the target ARM processor.  GCC uses this name
+to derive the name of the target ARM architecture (as if specified
+by @option{-march}) and the ARM processor type for which to tune for
+performance (as if specified by @option{-mtune}).  Where this option
+is used in conjunction with @option{-march} or @option{-mtune},
+those options take precedence over the appropriate part of this option.
+
+Many of the supported CPUs implement optional architectural
+extensions.  Where this is so the architectural extensions are
+normally enabled by default.  If implementations that lack the
+extension exist, then the extension syntax can be used to disable
+those extensions that have been omitted.  For floating-point and
+Advanced SIMD (Neon) instructions, the settings of the options
+@option{-mfloat-abi} and @option{-mfpu} must also be considered:
+floating-point and Advanced SIMD instructions will only be used if
+@option{-mfloat-abi} is not set to @samp{soft}; and any setting of
+@option{-mfpu} other than @samp{auto} will override the available
+floating-point and SIMD extension instructions.
+
+For example, @samp{cortex-a9} can be found in three major
+configurations: integer only, with just a floating-point unit or with
+floating-point and Advanced SIMD.  The default is to enable all the
+instructions, but the extensions @samp{+nosimd} and @samp{+nofp} can
+be used to disable just the SIMD or both the SIMD and floating-point
+instructions respectively.
+
+Permissible names for this option are the same as those for
+@option{-mtune}.
+
+The following extension options are common to the listed CPUs:
+
+@table @samp
+@item +nodsp
+Disable the DSP instructions on @samp{cortex-m33}, @samp{cortex-m35p}
+and @samp{cortex-m55}. Also disable the M-Profile Vector Extension (MVE)
+integer and single precision floating-point instructions on @samp{cortex-m55}.
+
+@item +nomve
+Disable the M-Profile Vector Extension (MVE) integer and single precision
+floating-point instructions on @samp{cortex-m55}.
+
+@item +nomve.fp
+Disable the M-Profile Vector Extension (MVE) single precision floating-point
+instructions on @samp{cortex-m55}.
+
+@item  +nofp
+Disables the floating-point instructions on @samp{arm9e},
+@samp{arm946e-s}, @samp{arm966e-s}, @samp{arm968e-s}, @samp{arm10e},
+@samp{arm1020e}, @samp{arm1022e}, @samp{arm926ej-s},
+@samp{arm1026ej-s}, @samp{cortex-r5}, @samp{cortex-r7}, @samp{cortex-r8},
+@samp{cortex-m4}, @samp{cortex-m7}, @samp{cortex-m33}, @samp{cortex-m35p}
+and @samp{cortex-m55}.
+Disables the floating-point and SIMD instructions on
+@samp{generic-armv7-a}, @samp{cortex-a5}, @samp{cortex-a7},
+@samp{cortex-a8}, @samp{cortex-a9}, @samp{cortex-a12},
+@samp{cortex-a15}, @samp{cortex-a17}, @samp{cortex-a15.cortex-a7},
+@samp{cortex-a17.cortex-a7}, @samp{cortex-a32}, @samp{cortex-a35},
+@samp{cortex-a53} and @samp{cortex-a55}.
+
+@item +nofp.dp
+Disables the double-precision component of the floating-point instructions
+on @samp{cortex-r5}, @samp{cortex-r7}, @samp{cortex-r8}, @samp{cortex-r52},
+@samp{cortex-r52plus} and @samp{cortex-m7}.
+
+@item +nosimd
+Disables the SIMD (but not floating-point) instructions on
+@samp{generic-armv7-a}, @samp{cortex-a5}, @samp{cortex-a7}
+and @samp{cortex-a9}.
+
+@item +crypto
+Enables the cryptographic instructions on @samp{cortex-a32},
+@samp{cortex-a35}, @samp{cortex-a53}, @samp{cortex-a55}, @samp{cortex-a57},
+@samp{cortex-a72}, @samp{cortex-a73}, @samp{cortex-a75}, @samp{exynos-m1},
+@samp{xgene1}, @samp{cortex-a57.cortex-a53}, @samp{cortex-a72.cortex-a53},
+@samp{cortex-a73.cortex-a35}, @samp{cortex-a73.cortex-a53} and
+@samp{cortex-a75.cortex-a55}.
+@end table
+
+Additionally the @samp{generic-armv7-a} pseudo target defaults to
+VFPv3 with 16 double-precision registers.  It supports the following
+extension options: @samp{mp}, @samp{sec}, @samp{vfpv3-d16},
+@samp{vfpv3}, @samp{vfpv3-d16-fp16}, @samp{vfpv3-fp16},
+@samp{vfpv4-d16}, @samp{vfpv4}, @samp{neon}, @samp{neon-vfpv3},
+@samp{neon-fp16}, @samp{neon-vfpv4}.  The meanings are the same as for
+the extensions to @option{-march=armv7-a}.
+
+@option{-mcpu=generic-@var{arch}} is also permissible, and is
+equivalent to @option{-march=@var{arch} -mtune=generic-@var{arch}}.
+See @option{-mtune} for more information.
+
+@option{-mcpu=native} causes the compiler to auto-detect the CPU
+of the build computer.  At present, this feature is only supported on
+GNU/Linux, and not all architectures are recognized.  If the auto-detect
+is unsuccessful the option has no effect.
+
+@item -mfpu=@var{name}
+@opindex mfpu
+This specifies what floating-point hardware (or hardware emulation) is
+available on the target.  Permissible names are: @samp{auto}, @samp{vfpv2},
+@samp{vfpv3},
+@samp{vfpv3-fp16}, @samp{vfpv3-d16}, @samp{vfpv3-d16-fp16}, @samp{vfpv3xd},
+@samp{vfpv3xd-fp16}, @samp{neon-vfpv3}, @samp{neon-fp16}, @samp{vfpv4},
+@samp{vfpv4-d16}, @samp{fpv4-sp-d16}, @samp{neon-vfpv4},
+@samp{fpv5-d16}, @samp{fpv5-sp-d16},
+@samp{fp-armv8}, @samp{neon-fp-armv8} and @samp{crypto-neon-fp-armv8}.
+Note that @samp{neon} is an alias for @samp{neon-vfpv3} and @samp{vfp}
+is an alias for @samp{vfpv2}.
+
+The setting @samp{auto} is the default and is special.  It causes the
+compiler to select the floating-point and Advanced SIMD instructions
+based on the settings of @option{-mcpu} and @option{-march}.
+
+If the selected floating-point hardware includes the NEON extension
+(e.g.@: @option{-mfpu=neon}), note that floating-point
+operations are not generated by GCC's auto-vectorization pass unless
+@option{-funsafe-math-optimizations} is also specified.  This is
+because NEON hardware does not fully implement the IEEE 754 standard for
+floating-point arithmetic (in particular denormal values are treated as
+zero), so the use of NEON instructions may lead to a loss of precision.
+
+You can also set the fpu name at function level by using the @code{target("fpu=")} function attributes (@pxref{ARM Function Attributes}) or pragmas (@pxref{Function Specific Option Pragmas}).
+
+@item -mfp16-format=@var{name}
+@opindex mfp16-format
+Specify the format of the @code{__fp16} half-precision floating-point type.
+Permissible names are @samp{none}, @samp{ieee}, and @samp{alternative};
+the default is @samp{none}, in which case the @code{__fp16} type is not
+defined.  @xref{Half-Precision}, for more information.
+
+@item -mstructure-size-boundary=@var{n}
+@opindex mstructure-size-boundary
+The sizes of all structures and unions are rounded up to a multiple
+of the number of bits set by this option.  Permissible values are 8, 32
+and 64.  The default value varies for different toolchains.  For the COFF
+targeted toolchain the default value is 8.  A value of 64 is only allowed
+if the underlying ABI supports it.
+
+Specifying a larger number can produce faster, more efficient code, but
+can also increase the size of the program.  Different values are potentially
+incompatible.  Code compiled with one value cannot necessarily expect to
+work with code or libraries compiled with another value, if they exchange
+information using structures or unions.
+
+This option is deprecated.
+
+@item -mabort-on-noreturn
+@opindex mabort-on-noreturn
+Generate a call to the function @code{abort} at the end of a
+@code{noreturn} function.  It is executed if the function tries to
+return.
+
+@item -mlong-calls
+@itemx -mno-long-calls
+@opindex mlong-calls
+@opindex mno-long-calls
+Tells the compiler to perform function calls by first loading the
+address of the function into a register and then performing a subroutine
+call on this register.  This switch is needed if the target function
+lies outside of the 64-megabyte addressing range of the offset-based
+version of subroutine call instruction.
+
+Even if this switch is enabled, not all function calls are turned
+into long calls.  The heuristic is that static functions, functions
+that have the @code{short_call} attribute, functions that are inside
+the scope of a @code{#pragma no_long_calls} directive, and functions whose
+definitions have already been compiled within the current compilation
+unit are not turned into long calls.  The exceptions to this rule are
+that weak function definitions, functions with the @code{long_call}
+attribute or the @code{section} attribute, and functions that are within
+the scope of a @code{#pragma long_calls} directive are always
+turned into long calls.
+
+This feature is not enabled by default.  Specifying
+@option{-mno-long-calls} restores the default behavior, as does
+placing the function calls within the scope of a @code{#pragma
+long_calls_off} directive.  Note these switches have no effect on how
+the compiler generates code to handle function calls via function
+pointers.
+
+@item -msingle-pic-base
+@opindex msingle-pic-base
+Treat the register used for PIC addressing as read-only, rather than
+loading it in the prologue for each function.  The runtime system is
+responsible for initializing this register with an appropriate value
+before execution begins.
+
+@item -mpic-register=@var{reg}
+@opindex mpic-register
+Specify the register to be used for PIC addressing.
+For standard PIC base case, the default is any suitable register
+determined by compiler.  For single PIC base case, the default is
+@samp{R9} if target is EABI based or stack-checking is enabled,
+otherwise the default is @samp{R10}.
+
+@item -mpic-data-is-text-relative
+@opindex mpic-data-is-text-relative
+Assume that the displacement between the text and data segments is fixed
+at static link time.  This permits using PC-relative addressing
+operations to access data known to be in the data segment.  For
+non-VxWorks RTP targets, this option is enabled by default.  When
+disabled on such targets, it will enable @option{-msingle-pic-base} by
+default.
+
+@item -mpoke-function-name
+@opindex mpoke-function-name
+Write the name of each function into the text section, directly
+preceding the function prologue.  The generated code is similar to this:
+
+@smallexample
+     t0
+         .ascii "arm_poke_function_name", 0
+         .align
+     t1
+         .word 0xff000000 + (t1 - t0)
+     arm_poke_function_name
+         mov     ip, sp
+         stmfd   sp!, @{fp, ip, lr, pc@}
+         sub     fp, ip, #4
+@end smallexample
+
+When performing a stack backtrace, code can inspect the value of
+@code{pc} stored at @code{fp + 0}.  If the trace function then looks at
+location @code{pc - 12} and the top 8 bits are set, then we know that
+there is a function name embedded immediately preceding this location
+and has length @code{((pc[-3]) & 0xff000000)}.
+
+@item -mthumb
+@itemx -marm
+@opindex marm
+@opindex mthumb
+
+Select between generating code that executes in ARM and Thumb
+states.  The default for most configurations is to generate code
+that executes in ARM state, but the default can be changed by
+configuring GCC with the @option{--with-mode=}@var{state}
+configure option.
+
+You can also override the ARM and Thumb mode for each function
+by using the @code{target("thumb")} and @code{target("arm")} function attributes
+(@pxref{ARM Function Attributes}) or pragmas (@pxref{Function Specific Option Pragmas}).
+
+@item -mflip-thumb 
+@opindex mflip-thumb
+Switch ARM/Thumb modes on alternating functions.
+This option is provided for regression testing of mixed Thumb/ARM code
+generation, and is not intended for ordinary use in compiling code.
+
+@item -mtpcs-frame
+@opindex mtpcs-frame
+Generate a stack frame that is compliant with the Thumb Procedure Call
+Standard for all non-leaf functions.  (A leaf function is one that does
+not call any other functions.)  The default is @option{-mno-tpcs-frame}.
+
+@item -mtpcs-leaf-frame
+@opindex mtpcs-leaf-frame
+Generate a stack frame that is compliant with the Thumb Procedure Call
+Standard for all leaf functions.  (A leaf function is one that does
+not call any other functions.)  The default is @option{-mno-apcs-leaf-frame}.
+
+@item -mcallee-super-interworking
+@opindex mcallee-super-interworking
+Gives all externally visible functions in the file being compiled an ARM
+instruction set header which switches to Thumb mode before executing the
+rest of the function.  This allows these functions to be called from
+non-interworking code.  This option is not valid in AAPCS configurations
+because interworking is enabled by default.
+
+@item -mcaller-super-interworking
+@opindex mcaller-super-interworking
+Allows calls via function pointers (including virtual functions) to
+execute correctly regardless of whether the target code has been
+compiled for interworking or not.  There is a small overhead in the cost
+of executing a function pointer if this option is enabled.  This option
+is not valid in AAPCS configurations because interworking is enabled
+by default.
+
+@item -mtp=@var{name}
+@opindex mtp
+Specify the access model for the thread local storage pointer.  The valid
+models are @samp{soft}, which generates calls to @code{__aeabi_read_tp},
+@samp{cp15}, which fetches the thread pointer from @code{cp15} directly
+(supported in the arm6k architecture), and @samp{auto}, which uses the
+best available method for the selected processor.  The default setting is
+@samp{auto}.
+
+@item -mtls-dialect=@var{dialect}
+@opindex mtls-dialect
+Specify the dialect to use for accessing thread local storage.  Two
+@var{dialect}s are supported---@samp{gnu} and @samp{gnu2}.  The
+@samp{gnu} dialect selects the original GNU scheme for supporting
+local and global dynamic TLS models.  The @samp{gnu2} dialect
+selects the GNU descriptor scheme, which provides better performance
+for shared libraries.  The GNU descriptor scheme is compatible with
+the original scheme, but does require new assembler, linker and
+library support.  Initial and local exec TLS models are unaffected by
+this option and always use the original scheme.
+
+@item -mword-relocations
+@opindex mword-relocations
+Only generate absolute relocations on word-sized values (i.e.@: R_ARM_ABS32).
+This is enabled by default on targets (uClinux, SymbianOS) where the runtime
+loader imposes this restriction, and when @option{-fpic} or @option{-fPIC}
+is specified. This option conflicts with @option{-mslow-flash-data}.
+
+@item -mfix-cortex-m3-ldrd
+@opindex mfix-cortex-m3-ldrd
+Some Cortex-M3 cores can cause data corruption when @code{ldrd} instructions
+with overlapping destination and base registers are used.  This option avoids
+generating these instructions.  This option is enabled by default when
+@option{-mcpu=cortex-m3} is specified.
+
+@item -mfix-cortex-a57-aes-1742098
+@itemx -mno-fix-cortex-a57-aes-1742098
+@itemx -mfix-cortex-a72-aes-1655431
+@itemx -mno-fix-cortex-a72-aes-1655431
+Enable (disable) mitigation for an erratum on Cortex-A57 and
+Cortex-A72 that affects the AES cryptographic instructions.  This
+option is enabled by default when either @option{-mcpu=cortex-a57} or
+@option{-mcpu=cortex-a72} is specified.
+
+@item -munaligned-access
+@itemx -mno-unaligned-access
+@opindex munaligned-access
+@opindex mno-unaligned-access
+Enables (or disables) reading and writing of 16- and 32- bit values
+from addresses that are not 16- or 32- bit aligned.  By default
+unaligned access is disabled for all pre-ARMv6, all ARMv6-M and for
+ARMv8-M Baseline architectures, and enabled for all other
+architectures.  If unaligned access is not enabled then words in packed
+data structures are accessed a byte at a time.
+
+The ARM attribute @code{Tag_CPU_unaligned_access} is set in the
+generated object file to either true or false, depending upon the
+setting of this option.  If unaligned access is enabled then the
+preprocessor symbol @code{__ARM_FEATURE_UNALIGNED} is also
+defined.
+
+@item -mneon-for-64bits
+@opindex mneon-for-64bits
+This option is deprecated and has no effect.
+
+@item -mslow-flash-data
+@opindex mslow-flash-data
+Assume loading data from flash is slower than fetching instruction.
+Therefore literal load is minimized for better performance.
+This option is only supported when compiling for ARMv7 M-profile and
+off by default. It conflicts with @option{-mword-relocations}.
+
+@item -masm-syntax-unified
+@opindex masm-syntax-unified
+Assume inline assembler is using unified asm syntax.  The default is
+currently off which implies divided syntax.  This option has no impact
+on Thumb2. However, this may change in future releases of GCC.
+Divided syntax should be considered deprecated.
+
+@item -mrestrict-it
+@opindex mrestrict-it
+Restricts generation of IT blocks to conform to the rules of ARMv8-A.
+IT blocks can only contain a single 16-bit instruction from a select
+set of instructions. This option is on by default for ARMv8-A Thumb mode.
+
+@item -mprint-tune-info
+@opindex mprint-tune-info
+Print CPU tuning information as comment in assembler file.  This is
+an option used only for regression testing of the compiler and not
+intended for ordinary use in compiling code.  This option is disabled
+by default.
+
+@item -mverbose-cost-dump
+@opindex mverbose-cost-dump
+Enable verbose cost model dumping in the debug dump files.  This option is
+provided for use in debugging the compiler.
+
+@item -mpure-code
+@opindex mpure-code
+Do not allow constant data to be placed in code sections.
+Additionally, when compiling for ELF object format give all text sections the
+ELF processor-specific section attribute @code{SHF_ARM_PURECODE}.  This option
+is only available when generating non-pic code for M-profile targets.
+
+@item -mcmse
+@opindex mcmse
+Generate secure code as per the "ARMv8-M Security Extensions: Requirements on
+Development Tools Engineering Specification", which can be found on
+@url{https://developer.arm.com/documentation/ecm0359818/latest/}.
+
+@item -mfix-cmse-cve-2021-35465
+@opindex mfix-cmse-cve-2021-35465
+Mitigate against a potential security issue with the @code{VLLDM} instruction
+in some M-profile devices when using CMSE (CVE-2021-365465).  This option is
+enabled by default when the option @option{-mcpu=} is used with
+@code{cortex-m33}, @code{cortex-m35p}, @code{cortex-m55} or @code{star-mc1}.
+The option @option{-mno-fix-cmse-cve-2021-35465} can be used to disable
+the mitigation.
+
+@item -mstack-protector-guard=@var{guard}
+@itemx -mstack-protector-guard-offset=@var{offset}
+@opindex mstack-protector-guard
+@opindex mstack-protector-guard-offset
+Generate stack protection code using canary at @var{guard}.  Supported
+locations are @samp{global} for a global canary or @samp{tls} for a
+canary accessible via the TLS register. The option
+@option{-mstack-protector-guard-offset=} is for use with
+@option{-fstack-protector-guard=tls} and not for use in user-land code.
+
+@item -mfdpic
+@itemx -mno-fdpic
+@opindex mfdpic
+@opindex mno-fdpic
+Select the FDPIC ABI, which uses 64-bit function descriptors to
+represent pointers to functions.  When the compiler is configured for
+@code{arm-*-uclinuxfdpiceabi} targets, this option is on by default
+and implies @option{-fPIE} if none of the PIC/PIE-related options is
+provided.  On other targets, it only enables the FDPIC-specific code
+generation features, and the user should explicitly provide the
+PIC/PIE-related options as needed.
+
+Note that static linking is not supported because it would still
+involve the dynamic linker when the program self-relocates.  If such
+behavior is acceptable, use -static and -Wl,-dynamic-linker options.
+
+The opposite @option{-mno-fdpic} option is useful (and required) to
+build the Linux kernel using the same (@code{arm-*-uclinuxfdpiceabi})
+toolchain as the one used to build the userland programs.
+
+@end table
+
+@node AVR Options
+@subsection AVR Options
+@cindex AVR Options
+
+These options are defined for AVR implementations:
+
+@table @gcctabopt
+@item -mmcu=@var{mcu}
+@opindex mmcu
+Specify Atmel AVR instruction set architectures (ISA) or MCU type.
+
+The default for this option is@tie{}@samp{avr2}.
+
+GCC supports the following AVR devices and ISAs:
+
+@include avr-mmcu.texi
+
+@item -mabsdata
+@opindex mabsdata
+
+Assume that all data in static storage can be accessed by LDS / STS
+instructions.  This option has only an effect on reduced Tiny devices like
+ATtiny40.  See also the @code{absdata}
+@ref{AVR Variable Attributes,variable attribute}.
+
+@item -maccumulate-args
+@opindex maccumulate-args
+Accumulate outgoing function arguments and acquire/release the needed
+stack space for outgoing function arguments once in function
+prologue/epilogue.  Without this option, outgoing arguments are pushed
+before calling a function and popped afterwards.
+
+Popping the arguments after the function call can be expensive on
+AVR so that accumulating the stack space might lead to smaller
+executables because arguments need not be removed from the
+stack after such a function call.
+
+This option can lead to reduced code size for functions that perform
+several calls to functions that get their arguments on the stack like
+calls to printf-like functions.
+
+@item -mbranch-cost=@var{cost}
+@opindex mbranch-cost
+Set the branch costs for conditional branch instructions to
+@var{cost}.  Reasonable values for @var{cost} are small, non-negative
+integers. The default branch cost is 0.
+
+@item -mcall-prologues
+@opindex mcall-prologues
+Functions prologues/epilogues are expanded as calls to appropriate
+subroutines.  Code size is smaller.
+
+@item -mdouble=@var{bits}
+@itemx -mlong-double=@var{bits}
+@opindex mdouble
+@opindex mlong-double
+Set the size (in bits) of the @code{double} or @code{long double} type,
+respectively.  Possible values for @var{bits} are 32 and 64.
+Whether or not a specific value for @var{bits} is allowed depends on
+the @code{--with-double=} and @code{--with-long-double=}
+@w{@uref{https://gcc.gnu.org/install/configure.html#avr,configure options}},
+and the same applies for the default values of the options.
+
+@item -mgas-isr-prologues
+@opindex mgas-isr-prologues
+Interrupt service routines (ISRs) may use the @code{__gcc_isr} pseudo
+instruction supported by GNU Binutils.
+If this option is on, the feature can still be disabled for individual
+ISRs by means of the @ref{AVR Function Attributes,,@code{no_gccisr}}
+function attribute.  This feature is activated per default
+if optimization is on (but not with @option{-Og}, @pxref{Optimize Options}),
+and if GNU Binutils support @w{@uref{https://sourceware.org/PR21683,PR21683}}.
+
+@item -mint8
+@opindex mint8
+Assume @code{int} to be 8-bit integer.  This affects the sizes of all types: a
+@code{char} is 1 byte, an @code{int} is 1 byte, a @code{long} is 2 bytes,
+and @code{long long} is 4 bytes.  Please note that this option does not
+conform to the C standards, but it results in smaller code
+size.
+
+@item -mmain-is-OS_task
+@opindex mmain-is-OS_task
+Do not save registers in @code{main}.  The effect is the same like
+attaching attribute @ref{AVR Function Attributes,,@code{OS_task}}
+to @code{main}. It is activated per default if optimization is on.
+
+@item -mn-flash=@var{num}
+@opindex mn-flash
+Assume that the flash memory has a size of 
+@var{num} times 64@tie{}KiB.
+
+@item -mno-interrupts
+@opindex mno-interrupts
+Generated code is not compatible with hardware interrupts.
+Code size is smaller.
+
+@item -mrelax
+@opindex mrelax
+Try to replace @code{CALL} resp.@: @code{JMP} instruction by the shorter
+@code{RCALL} resp.@: @code{RJMP} instruction if applicable.
+Setting @option{-mrelax} just adds the @option{--mlink-relax} option to
+the assembler's command line and the @option{--relax} option to the
+linker's command line.
+
+Jump relaxing is performed by the linker because jump offsets are not
+known before code is located. Therefore, the assembler code generated by the
+compiler is the same, but the instructions in the executable may
+differ from instructions in the assembler code.
+
+Relaxing must be turned on if linker stubs are needed, see the
+section on @code{EIND} and linker stubs below.
+
+@item -mrmw
+@opindex mrmw
+Assume that the device supports the Read-Modify-Write
+instructions @code{XCH}, @code{LAC}, @code{LAS} and @code{LAT}.
+
+@item -mshort-calls
+@opindex mshort-calls
+
+Assume that @code{RJMP} and @code{RCALL} can target the whole
+program memory.
+
+This option is used internally for multilib selection.  It is
+not an optimization option, and you don't need to set it by hand.
+
+@item -msp8
+@opindex msp8
+Treat the stack pointer register as an 8-bit register,
+i.e.@: assume the high byte of the stack pointer is zero.
+In general, you don't need to set this option by hand.
+
+This option is used internally by the compiler to select and
+build multilibs for architectures @code{avr2} and @code{avr25}.
+These architectures mix devices with and without @code{SPH}.
+For any setting other than @option{-mmcu=avr2} or @option{-mmcu=avr25}
+the compiler driver adds or removes this option from the compiler
+proper's command line, because the compiler then knows if the device
+or architecture has an 8-bit stack pointer and thus no @code{SPH}
+register or not.
+
+@item -mstrict-X
+@opindex mstrict-X
+Use address register @code{X} in a way proposed by the hardware.  This means
+that @code{X} is only used in indirect, post-increment or
+pre-decrement addressing.
+
+Without this option, the @code{X} register may be used in the same way
+as @code{Y} or @code{Z} which then is emulated by additional
+instructions.  
+For example, loading a value with @code{X+const} addressing with a
+small non-negative @code{const < 64} to a register @var{Rn} is
+performed as
+
+@example
+adiw r26, const   ; X += const
+ld   @var{Rn}, X        ; @var{Rn} = *X
+sbiw r26, const   ; X -= const
+@end example
+
+@item -mtiny-stack
+@opindex mtiny-stack
+Only change the lower 8@tie{}bits of the stack pointer.
+
+@item -mfract-convert-truncate
+@opindex mfract-convert-truncate
+Allow to use truncation instead of rounding towards zero for fractional fixed-point types.
+
+@item -nodevicelib
+@opindex nodevicelib
+Don't link against AVR-LibC's device specific library @code{lib<mcu>.a}.
+
+@item -nodevicespecs
+@opindex nodevicespecs
+Don't add @option{-specs=device-specs/specs-@var{mcu}} to the compiler driver's
+command line.  The user takes responsibility for supplying the sub-processes
+like compiler proper, assembler and linker with appropriate command line
+options.  This means that the user has to supply her private device specs
+file by means of @option{-specs=@var{path-to-specs-file}}.  There is no
+more need for option @option{-mmcu=@var{mcu}}.
+
+This option can also serve as a replacement for the older way of
+specifying custom device-specs files that needed @option{-B @var{some-path}} to point to a directory
+which contains a folder named @code{device-specs} which contains a specs file named
+@code{specs-@var{mcu}}, where @var{mcu} was specified by @option{-mmcu=@var{mcu}}.
+
+@item -Waddr-space-convert
+@opindex Waddr-space-convert
+@opindex Wno-addr-space-convert
+Warn about conversions between address spaces in the case where the
+resulting address space is not contained in the incoming address space.
+
+@item -Wmisspelled-isr
+@opindex Wmisspelled-isr
+@opindex Wno-misspelled-isr
+Warn if the ISR is misspelled, i.e.@: without __vector prefix.
+Enabled by default.
+@end table
+
+@subsubsection @code{EIND} and Devices with More Than 128 Ki Bytes of Flash
+@cindex @code{EIND}
+Pointers in the implementation are 16@tie{}bits wide.
+The address of a function or label is represented as word address so
+that indirect jumps and calls can target any code address in the
+range of 64@tie{}Ki words.
+
+In order to facilitate indirect jump on devices with more than 128@tie{}Ki
+bytes of program memory space, there is a special function register called
+@code{EIND} that serves as most significant part of the target address
+when @code{EICALL} or @code{EIJMP} instructions are used.
+
+Indirect jumps and calls on these devices are handled as follows by
+the compiler and are subject to some limitations:
+
+@itemize @bullet
+
+@item
+The compiler never sets @code{EIND}.
+
+@item
+The compiler uses @code{EIND} implicitly in @code{EICALL}/@code{EIJMP}
+instructions or might read @code{EIND} directly in order to emulate an
+indirect call/jump by means of a @code{RET} instruction.
+
+@item
+The compiler assumes that @code{EIND} never changes during the startup
+code or during the application. In particular, @code{EIND} is not
+saved/restored in function or interrupt service routine
+prologue/epilogue.
+
+@item
+For indirect calls to functions and computed goto, the linker
+generates @emph{stubs}. Stubs are jump pads sometimes also called
+@emph{trampolines}. Thus, the indirect call/jump jumps to such a stub.
+The stub contains a direct jump to the desired address.
+
+@item
+Linker relaxation must be turned on so that the linker generates
+the stubs correctly in all situations. See the compiler option
+@option{-mrelax} and the linker option @option{--relax}.
+There are corner cases where the linker is supposed to generate stubs
+but aborts without relaxation and without a helpful error message.
+
+@item
+The default linker script is arranged for code with @code{EIND = 0}.
+If code is supposed to work for a setup with @code{EIND != 0}, a custom
+linker script has to be used in order to place the sections whose
+name start with @code{.trampolines} into the segment where @code{EIND}
+points to.
+
+@item
+The startup code from libgcc never sets @code{EIND}.
+Notice that startup code is a blend of code from libgcc and AVR-LibC.
+For the impact of AVR-LibC on @code{EIND}, see the
+@w{@uref{http://nongnu.org/avr-libc/user-manual/,AVR-LibC user manual}}.
+
+@item
+It is legitimate for user-specific startup code to set up @code{EIND}
+early, for example by means of initialization code located in
+section @code{.init3}. Such code runs prior to general startup code
+that initializes RAM and calls constructors, but after the bit
+of startup code from AVR-LibC that sets @code{EIND} to the segment
+where the vector table is located.
+@example
+#include <avr/io.h>
+
+static void
+__attribute__((section(".init3"),naked,used,no_instrument_function))
+init3_set_eind (void)
+@{
+  __asm volatile ("ldi r24,pm_hh8(__trampolines_start)\n\t"
+                  "out %i0,r24" :: "n" (&EIND) : "r24","memory");
+@}
+@end example
+
+@noindent
+The @code{__trampolines_start} symbol is defined in the linker script.
+
+@item
+Stubs are generated automatically by the linker if
+the following two conditions are met:
+@itemize @minus
+
+@item The address of a label is taken by means of the @code{gs} modifier
+(short for @emph{generate stubs}) like so:
+@example
+LDI r24, lo8(gs(@var{func}))
+LDI r25, hi8(gs(@var{func}))
+@end example
+@item The final location of that label is in a code segment
+@emph{outside} the segment where the stubs are located.
+@end itemize
+
+@item
+The compiler emits such @code{gs} modifiers for code labels in the
+following situations:
+@itemize @minus
+@item Taking address of a function or code label.
+@item Computed goto.
+@item If prologue-save function is used, see @option{-mcall-prologues}
+command-line option.
+@item Switch/case dispatch tables. If you do not want such dispatch
+tables you can specify the @option{-fno-jump-tables} command-line option.
+@item C and C++ constructors/destructors called during startup/shutdown.
+@item If the tools hit a @code{gs()} modifier explained above.
+@end itemize
+
+@item
+Jumping to non-symbolic addresses like so is @emph{not} supported:
+
+@example
+int main (void)
+@{
+    /* Call function at word address 0x2 */
+    return ((int(*)(void)) 0x2)();
+@}
+@end example
+
+Instead, a stub has to be set up, i.e.@: the function has to be called
+through a symbol (@code{func_4} in the example):
+
+@example
+int main (void)
+@{
+    extern int func_4 (void);
+
+    /* Call function at byte address 0x4 */
+    return func_4();
+@}
+@end example
+
+and the application be linked with @option{-Wl,--defsym,func_4=0x4}.
+Alternatively, @code{func_4} can be defined in the linker script.
+@end itemize
+
+@subsubsection Handling of the @code{RAMPD}, @code{RAMPX}, @code{RAMPY} and @code{RAMPZ} Special Function Registers
+@cindex @code{RAMPD}
+@cindex @code{RAMPX}
+@cindex @code{RAMPY}
+@cindex @code{RAMPZ}
+Some AVR devices support memories larger than the 64@tie{}KiB range
+that can be accessed with 16-bit pointers.  To access memory locations
+outside this 64@tie{}KiB range, the content of a @code{RAMP}
+register is used as high part of the address:
+The @code{X}, @code{Y}, @code{Z} address register is concatenated
+with the @code{RAMPX}, @code{RAMPY}, @code{RAMPZ} special function
+register, respectively, to get a wide address. Similarly,
+@code{RAMPD} is used together with direct addressing.
+
+@itemize
+@item
+The startup code initializes the @code{RAMP} special function
+registers with zero.
+
+@item
+If a @ref{AVR Named Address Spaces,named address space} other than
+generic or @code{__flash} is used, then @code{RAMPZ} is set
+as needed before the operation.
+
+@item
+If the device supports RAM larger than 64@tie{}KiB and the compiler
+needs to change @code{RAMPZ} to accomplish an operation, @code{RAMPZ}
+is reset to zero after the operation.
+
+@item
+If the device comes with a specific @code{RAMP} register, the ISR
+prologue/epilogue saves/restores that SFR and initializes it with
+zero in case the ISR code might (implicitly) use it.
+
+@item
+RAM larger than 64@tie{}KiB is not supported by GCC for AVR targets.
+If you use inline assembler to read from locations outside the
+16-bit address range and change one of the @code{RAMP} registers,
+you must reset it to zero after the access.
+
+@end itemize
+
+@subsubsection AVR Built-in Macros
+
+GCC defines several built-in macros so that the user code can test
+for the presence or absence of features.  Almost any of the following
+built-in macros are deduced from device capabilities and thus
+triggered by the @option{-mmcu=} command-line option.
+
+For even more AVR-specific built-in macros see
+@ref{AVR Named Address Spaces} and @ref{AVR Built-in Functions}.
+
+@table @code
+
+@item __AVR_ARCH__
+Build-in macro that resolves to a decimal number that identifies the
+architecture and depends on the @option{-mmcu=@var{mcu}} option.
+Possible values are:
+
+@code{2}, @code{25}, @code{3}, @code{31}, @code{35},
+@code{4}, @code{5}, @code{51}, @code{6}
+
+for @var{mcu}=@code{avr2}, @code{avr25}, @code{avr3}, @code{avr31},
+@code{avr35}, @code{avr4}, @code{avr5}, @code{avr51}, @code{avr6},
+
+respectively and
+
+@code{100},
+@code{102}, @code{103}, @code{104},
+@code{105}, @code{106}, @code{107}
+
+for @var{mcu}=@code{avrtiny},
+@code{avrxmega2}, @code{avrxmega3}, @code{avrxmega4},
+@code{avrxmega5}, @code{avrxmega6}, @code{avrxmega7}, respectively.
+If @var{mcu} specifies a device, this built-in macro is set
+accordingly. For example, with @option{-mmcu=atmega8} the macro is
+defined to @code{4}.
+
+@item __AVR_@var{Device}__
+Setting @option{-mmcu=@var{device}} defines this built-in macro which reflects
+the device's name. For example, @option{-mmcu=atmega8} defines the
+built-in macro @code{__AVR_ATmega8__}, @option{-mmcu=attiny261a} defines
+@code{__AVR_ATtiny261A__}, etc.
+
+The built-in macros' names follow
+the scheme @code{__AVR_@var{Device}__} where @var{Device} is
+the device name as from the AVR user manual. The difference between
+@var{Device} in the built-in macro and @var{device} in
+@option{-mmcu=@var{device}} is that the latter is always lowercase.
+
+If @var{device} is not a device but only a core architecture like
+@samp{avr51}, this macro is not defined.
+
+@item __AVR_DEVICE_NAME__
+Setting @option{-mmcu=@var{device}} defines this built-in macro to
+the device's name. For example, with @option{-mmcu=atmega8} the macro
+is defined to @code{atmega8}.
+
+If @var{device} is not a device but only a core architecture like
+@samp{avr51}, this macro is not defined.
+
+@item __AVR_XMEGA__
+The device / architecture belongs to the XMEGA family of devices.
+
+@item __AVR_HAVE_ELPM__
+The device has the @code{ELPM} instruction.
+
+@item __AVR_HAVE_ELPMX__
+The device has the @code{ELPM R@var{n},Z} and @code{ELPM
+R@var{n},Z+} instructions.
+
+@item __AVR_HAVE_MOVW__
+The device has the @code{MOVW} instruction to perform 16-bit
+register-register moves.
+
+@item __AVR_HAVE_LPMX__
+The device has the @code{LPM R@var{n},Z} and
+@code{LPM R@var{n},Z+} instructions.
+
+@item __AVR_HAVE_MUL__
+The device has a hardware multiplier. 
+
+@item __AVR_HAVE_JMP_CALL__
+The device has the @code{JMP} and @code{CALL} instructions.
+This is the case for devices with more than 8@tie{}KiB of program
+memory.
+
+@item __AVR_HAVE_EIJMP_EICALL__
+@itemx __AVR_3_BYTE_PC__
+The device has the @code{EIJMP} and @code{EICALL} instructions.
+This is the case for devices with more than 128@tie{}KiB of program memory.
+This also means that the program counter
+(PC) is 3@tie{}bytes wide.
+
+@item __AVR_2_BYTE_PC__
+The program counter (PC) is 2@tie{}bytes wide. This is the case for devices
+with up to 128@tie{}KiB of program memory.
+
+@item __AVR_HAVE_8BIT_SP__
+@itemx __AVR_HAVE_16BIT_SP__
+The stack pointer (SP) register is treated as 8-bit respectively
+16-bit register by the compiler.
+The definition of these macros is affected by @option{-mtiny-stack}.
+
+@item __AVR_HAVE_SPH__
+@itemx __AVR_SP8__
+The device has the SPH (high part of stack pointer) special function
+register or has an 8-bit stack pointer, respectively.
+The definition of these macros is affected by @option{-mmcu=} and
+in the cases of @option{-mmcu=avr2} and @option{-mmcu=avr25} also
+by @option{-msp8}.
+
+@item __AVR_HAVE_RAMPD__
+@itemx __AVR_HAVE_RAMPX__
+@itemx __AVR_HAVE_RAMPY__
+@itemx __AVR_HAVE_RAMPZ__
+The device has the @code{RAMPD}, @code{RAMPX}, @code{RAMPY},
+@code{RAMPZ} special function register, respectively.
+
+@item __NO_INTERRUPTS__
+This macro reflects the @option{-mno-interrupts} command-line option.
+
+@item __AVR_ERRATA_SKIP__
+@itemx __AVR_ERRATA_SKIP_JMP_CALL__
+Some AVR devices (AT90S8515, ATmega103) must not skip 32-bit
+instructions because of a hardware erratum.  Skip instructions are
+@code{SBRS}, @code{SBRC}, @code{SBIS}, @code{SBIC} and @code{CPSE}.
+The second macro is only defined if @code{__AVR_HAVE_JMP_CALL__} is also
+set.
+
+@item __AVR_ISA_RMW__
+The device has Read-Modify-Write instructions (XCH, LAC, LAS and LAT).
+
+@item __AVR_SFR_OFFSET__=@var{offset}
+Instructions that can address I/O special function registers directly
+like @code{IN}, @code{OUT}, @code{SBI}, etc.@: may use a different
+address as if addressed by an instruction to access RAM like @code{LD}
+or @code{STS}. This offset depends on the device architecture and has
+to be subtracted from the RAM address in order to get the
+respective I/O@tie{}address.
+
+@item __AVR_SHORT_CALLS__
+The @option{-mshort-calls} command line option is set.
+
+@item __AVR_PM_BASE_ADDRESS__=@var{addr}
+Some devices support reading from flash memory by means of @code{LD*}
+instructions.  The flash memory is seen in the data address space
+at an offset of @code{__AVR_PM_BASE_ADDRESS__}.  If this macro
+is not defined, this feature is not available.  If defined,
+the address space is linear and there is no need to put
+@code{.rodata} into RAM.  This is handled by the default linker
+description file, and is currently available for
+@code{avrtiny} and @code{avrxmega3}.  Even more convenient,
+there is no need to use address spaces like @code{__flash} or
+features like attribute @code{progmem} and @code{pgm_read_*}.
+
+@item __WITH_AVRLIBC__
+The compiler is configured to be used together with AVR-Libc.
+See the @option{--with-avrlibc} configure option.
+
+@item __HAVE_DOUBLE_MULTILIB__
+Defined if @option{-mdouble=} acts as a multilib option.
+
+@item __HAVE_DOUBLE32__
+@itemx __HAVE_DOUBLE64__
+Defined if the compiler supports 32-bit double resp. 64-bit double.
+The actual layout is specified by option @option{-mdouble=}.
+
+@item __DEFAULT_DOUBLE__
+The size in bits of @code{double} if @option{-mdouble=} is not set.
+To test the layout of @code{double} in a program, use the built-in
+macro @code{__SIZEOF_DOUBLE__}.
+
+@item __HAVE_LONG_DOUBLE32__
+@itemx __HAVE_LONG_DOUBLE64__
+@itemx __HAVE_LONG_DOUBLE_MULTILIB__
+@itemx __DEFAULT_LONG_DOUBLE__
+Same as above, but for @code{long double} instead of @code{double}.
+
+@item __WITH_DOUBLE_COMPARISON__
+Reflects the @code{--with-double-comparison=@{tristate|bool|libf7@}}
+@w{@uref{https://gcc.gnu.org/install/configure.html#avr,configure option}}
+and is defined to @code{2} or @code{3}.
+
+@item __WITH_LIBF7_LIBGCC__
+@itemx __WITH_LIBF7_MATH__
+@itemx __WITH_LIBF7_MATH_SYMBOLS__
+Reflects the @code{--with-libf7=@{libgcc|math|math-symbols@}}
+@w{@uref{https://gcc.gnu.org/install/configure.html#avr,configure option}}.
+
+@end table
+
+@node Blackfin Options
+@subsection Blackfin Options
+@cindex Blackfin Options
+
+@table @gcctabopt
+@item -mcpu=@var{cpu}@r{[}-@var{sirevision}@r{]}
+@opindex mcpu=
+Specifies the name of the target Blackfin processor.  Currently, @var{cpu}
+can be one of @samp{bf512}, @samp{bf514}, @samp{bf516}, @samp{bf518},
+@samp{bf522}, @samp{bf523}, @samp{bf524}, @samp{bf525}, @samp{bf526},
+@samp{bf527}, @samp{bf531}, @samp{bf532}, @samp{bf533},
+@samp{bf534}, @samp{bf536}, @samp{bf537}, @samp{bf538}, @samp{bf539},
+@samp{bf542}, @samp{bf544}, @samp{bf547}, @samp{bf548}, @samp{bf549},
+@samp{bf542m}, @samp{bf544m}, @samp{bf547m}, @samp{bf548m}, @samp{bf549m},
+@samp{bf561}, @samp{bf592}.
+
+The optional @var{sirevision} specifies the silicon revision of the target
+Blackfin processor.  Any workarounds available for the targeted silicon revision
+are enabled.  If @var{sirevision} is @samp{none}, no workarounds are enabled.
+If @var{sirevision} is @samp{any}, all workarounds for the targeted processor
+are enabled.  The @code{__SILICON_REVISION__} macro is defined to two
+hexadecimal digits representing the major and minor numbers in the silicon
+revision.  If @var{sirevision} is @samp{none}, the @code{__SILICON_REVISION__}
+is not defined.  If @var{sirevision} is @samp{any}, the
+@code{__SILICON_REVISION__} is defined to be @code{0xffff}.
+If this optional @var{sirevision} is not used, GCC assumes the latest known
+silicon revision of the targeted Blackfin processor.
+
+GCC defines a preprocessor macro for the specified @var{cpu}.
+For the @samp{bfin-elf} toolchain, this option causes the hardware BSP
+provided by libgloss to be linked in if @option{-msim} is not given.
+
+Without this option, @samp{bf532} is used as the processor by default.
+
+Note that support for @samp{bf561} is incomplete.  For @samp{bf561},
+only the preprocessor macro is defined.
+
+@item -msim
+@opindex msim
+Specifies that the program will be run on the simulator.  This causes
+the simulator BSP provided by libgloss to be linked in.  This option
+has effect only for @samp{bfin-elf} toolchain.
+Certain other options, such as @option{-mid-shared-library} and
+@option{-mfdpic}, imply @option{-msim}.
+
+@item -momit-leaf-frame-pointer
+@opindex momit-leaf-frame-pointer
+Don't keep the frame pointer in a register for leaf functions.  This
+avoids the instructions to save, set up and restore frame pointers and
+makes an extra register available in leaf functions.
+
+@item -mspecld-anomaly
+@opindex mspecld-anomaly
+When enabled, the compiler ensures that the generated code does not
+contain speculative loads after jump instructions. If this option is used,
+@code{__WORKAROUND_SPECULATIVE_LOADS} is defined.
+
+@item -mno-specld-anomaly
+@opindex mno-specld-anomaly
+@opindex mspecld-anomaly
+Don't generate extra code to prevent speculative loads from occurring.
+
+@item -mcsync-anomaly
+@opindex mcsync-anomaly
+When enabled, the compiler ensures that the generated code does not
+contain CSYNC or SSYNC instructions too soon after conditional branches.
+If this option is used, @code{__WORKAROUND_SPECULATIVE_SYNCS} is defined.
+
+@item -mno-csync-anomaly
+@opindex mno-csync-anomaly
+@opindex mcsync-anomaly
+Don't generate extra code to prevent CSYNC or SSYNC instructions from
+occurring too soon after a conditional branch.
+
+@item -mlow64k
+@opindex mlow64k
+When enabled, the compiler is free to take advantage of the knowledge that
+the entire program fits into the low 64k of memory.
+
+@item -mno-low64k
+@opindex mno-low64k
+Assume that the program is arbitrarily large.  This is the default.
+
+@item -mstack-check-l1
+@opindex mstack-check-l1
+Do stack checking using information placed into L1 scratchpad memory by the
+uClinux kernel.
+
+@item -mid-shared-library
+@opindex mid-shared-library
+Generate code that supports shared libraries via the library ID method.
+This allows for execute in place and shared libraries in an environment
+without virtual memory management.  This option implies @option{-fPIC}.
+With a @samp{bfin-elf} target, this option implies @option{-msim}.
+
+@item -mno-id-shared-library
+@opindex mno-id-shared-library
+@opindex mid-shared-library
+Generate code that doesn't assume ID-based shared libraries are being used.
+This is the default.
+
+@item -mleaf-id-shared-library
+@opindex mleaf-id-shared-library
+Generate code that supports shared libraries via the library ID method,
+but assumes that this library or executable won't link against any other
+ID shared libraries.  That allows the compiler to use faster code for jumps
+and calls.
+
+@item -mno-leaf-id-shared-library
+@opindex mno-leaf-id-shared-library
+@opindex mleaf-id-shared-library
+Do not assume that the code being compiled won't link against any ID shared
+libraries.  Slower code is generated for jump and call insns.
+
+@item -mshared-library-id=n
+@opindex mshared-library-id
+Specifies the identification number of the ID-based shared library being
+compiled.  Specifying a value of 0 generates more compact code; specifying
+other values forces the allocation of that number to the current
+library but is no more space- or time-efficient than omitting this option.
+
+@item -msep-data
+@opindex msep-data
+Generate code that allows the data segment to be located in a different
+area of memory from the text segment.  This allows for execute in place in
+an environment without virtual memory management by eliminating relocations
+against the text section.
+
+@item -mno-sep-data
+@opindex mno-sep-data
+@opindex msep-data
+Generate code that assumes that the data segment follows the text segment.
+This is the default.
+
+@item -mlong-calls
+@itemx -mno-long-calls
+@opindex mlong-calls
+@opindex mno-long-calls
+Tells the compiler to perform function calls by first loading the
+address of the function into a register and then performing a subroutine
+call on this register.  This switch is needed if the target function
+lies outside of the 24-bit addressing range of the offset-based
+version of subroutine call instruction.
+
+This feature is not enabled by default.  Specifying
+@option{-mno-long-calls} restores the default behavior.  Note these
+switches have no effect on how the compiler generates code to handle
+function calls via function pointers.
+
+@item -mfast-fp
+@opindex mfast-fp
+Link with the fast floating-point library. This library relaxes some of
+the IEEE floating-point standard's rules for checking inputs against
+Not-a-Number (NAN), in the interest of performance.
+
+@item -minline-plt
+@opindex minline-plt
+Enable inlining of PLT entries in function calls to functions that are
+not known to bind locally.  It has no effect without @option{-mfdpic}.
+
+@item -mmulticore
+@opindex mmulticore
+Build a standalone application for multicore Blackfin processors. 
+This option causes proper start files and link scripts supporting 
+multicore to be used, and defines the macro @code{__BFIN_MULTICORE}. 
+It can only be used with @option{-mcpu=bf561@r{[}-@var{sirevision}@r{]}}. 
+
+This option can be used with @option{-mcorea} or @option{-mcoreb}, which
+selects the one-application-per-core programming model.  Without
+@option{-mcorea} or @option{-mcoreb}, the single-application/dual-core
+programming model is used. In this model, the main function of Core B
+should be named as @code{coreb_main}.
+
+If this option is not used, the single-core application programming
+model is used.
+
+@item -mcorea
+@opindex mcorea
+Build a standalone application for Core A of BF561 when using
+the one-application-per-core programming model. Proper start files
+and link scripts are used to support Core A, and the macro
+@code{__BFIN_COREA} is defined.
+This option can only be used in conjunction with @option{-mmulticore}.
+
+@item -mcoreb
+@opindex mcoreb
+Build a standalone application for Core B of BF561 when using
+the one-application-per-core programming model. Proper start files
+and link scripts are used to support Core B, and the macro
+@code{__BFIN_COREB} is defined. When this option is used, @code{coreb_main}
+should be used instead of @code{main}. 
+This option can only be used in conjunction with @option{-mmulticore}.
+
+@item -msdram
+@opindex msdram
+Build a standalone application for SDRAM. Proper start files and
+link scripts are used to put the application into SDRAM, and the macro
+@code{__BFIN_SDRAM} is defined.
+The loader should initialize SDRAM before loading the application.
+
+@item -micplb
+@opindex micplb
+Assume that ICPLBs are enabled at run time.  This has an effect on certain
+anomaly workarounds.  For Linux targets, the default is to assume ICPLBs
+are enabled; for standalone applications the default is off.
+@end table
+
+@node C6X Options
+@subsection C6X Options
+@cindex C6X Options
+
+@table @gcctabopt
+@item -march=@var{name}
+@opindex march
+This specifies the name of the target architecture.  GCC uses this
+name to determine what kind of instructions it can emit when generating
+assembly code.  Permissible names are: @samp{c62x},
+@samp{c64x}, @samp{c64x+}, @samp{c67x}, @samp{c67x+}, @samp{c674x}.
+
+@item -mbig-endian
+@opindex mbig-endian
+Generate code for a big-endian target.
+
+@item -mlittle-endian
+@opindex mlittle-endian
+Generate code for a little-endian target.  This is the default.
+
+@item -msim
+@opindex msim
+Choose startup files and linker script suitable for the simulator.
+
+@item -msdata=default
+@opindex msdata=default
+Put small global and static data in the @code{.neardata} section,
+which is pointed to by register @code{B14}.  Put small uninitialized
+global and static data in the @code{.bss} section, which is adjacent
+to the @code{.neardata} section.  Put small read-only data into the
+@code{.rodata} section.  The corresponding sections used for large
+pieces of data are @code{.fardata}, @code{.far} and @code{.const}.
+
+@item -msdata=all
+@opindex msdata=all
+Put all data, not just small objects, into the sections reserved for
+small data, and use addressing relative to the @code{B14} register to
+access them.
+
+@item -msdata=none
+@opindex msdata=none
+Make no use of the sections reserved for small data, and use absolute
+addresses to access all data.  Put all initialized global and static
+data in the @code{.fardata} section, and all uninitialized data in the
+@code{.far} section.  Put all constant data into the @code{.const}
+section.
+@end table
+
+@node CRIS Options
+@subsection CRIS Options
+@cindex CRIS Options
+
+These options are defined specifically for the CRIS ports.
+
+@table @gcctabopt
+@item -march=@var{architecture-type}
+@itemx -mcpu=@var{architecture-type}
+@opindex march
+@opindex mcpu
+Generate code for the specified architecture.  The choices for
+@var{architecture-type} are @samp{v3}, @samp{v8} and @samp{v10} for
+respectively ETRAX@w{ }4, ETRAX@w{ }100, and ETRAX@w{ }100@w{ }LX@.
+Default is @samp{v0}.
+
+@item -mtune=@var{architecture-type}
+@opindex mtune
+Tune to @var{architecture-type} everything applicable about the generated
+code, except for the ABI and the set of available instructions.  The
+choices for @var{architecture-type} are the same as for
+@option{-march=@var{architecture-type}}.
+
+@item -mmax-stack-frame=@var{n}
+@opindex mmax-stack-frame
+Warn when the stack frame of a function exceeds @var{n} bytes.
+
+@item -metrax4
+@itemx -metrax100
+@opindex metrax4
+@opindex metrax100
+The options @option{-metrax4} and @option{-metrax100} are synonyms for
+@option{-march=v3} and @option{-march=v8} respectively.
+
+@item -mmul-bug-workaround
+@itemx -mno-mul-bug-workaround
+@opindex mmul-bug-workaround
+@opindex mno-mul-bug-workaround
+Work around a bug in the @code{muls} and @code{mulu} instructions for CPU
+models where it applies.  This option is disabled by default.
+
+@item -mpdebug
+@opindex mpdebug
+Enable CRIS-specific verbose debug-related information in the assembly
+code.  This option also has the effect of turning off the @samp{#NO_APP}
+formatted-code indicator to the assembler at the beginning of the
+assembly file.
+
+@item -mcc-init
+@opindex mcc-init
+Do not use condition-code results from previous instruction; always emit
+compare and test instructions before use of condition codes.
+
+@item -mno-side-effects
+@opindex mno-side-effects
+@opindex mside-effects
+Do not emit instructions with side effects in addressing modes other than
+post-increment.
+
+@item -mstack-align
+@itemx -mno-stack-align
+@itemx -mdata-align
+@itemx -mno-data-align
+@itemx -mconst-align
+@itemx -mno-const-align
+@opindex mstack-align
+@opindex mno-stack-align
+@opindex mdata-align
+@opindex mno-data-align
+@opindex mconst-align
+@opindex mno-const-align
+These options (@samp{no-} options) arrange (eliminate arrangements) for the
+stack frame, individual data and constants to be aligned for the maximum
+single data access size for the chosen CPU model.  The default is to
+arrange for 32-bit alignment.  ABI details such as structure layout are
+not affected by these options.
+
+@item -m32-bit
+@itemx -m16-bit
+@itemx -m8-bit
+@opindex m32-bit
+@opindex m16-bit
+@opindex m8-bit
+Similar to the stack- data- and const-align options above, these options
+arrange for stack frame, writable data and constants to all be 32-bit,
+16-bit or 8-bit aligned.  The default is 32-bit alignment.
+
+@item -mno-prologue-epilogue
+@itemx -mprologue-epilogue
+@opindex mno-prologue-epilogue
+@opindex mprologue-epilogue
+With @option{-mno-prologue-epilogue}, the normal function prologue and
+epilogue which set up the stack frame are omitted and no return
+instructions or return sequences are generated in the code.  Use this
+option only together with visual inspection of the compiled code: no
+warnings or errors are generated when call-saved registers must be saved,
+or storage for local variables needs to be allocated.
+
+@item -melf
+@opindex melf
+Legacy no-op option.
+
+@item -sim
+@opindex sim
+This option arranges
+to link with input-output functions from a simulator library.  Code,
+initialized data and zero-initialized data are allocated consecutively.
+
+@item -sim2
+@opindex sim2
+Like @option{-sim}, but pass linker options to locate initialized data at
+0x40000000 and zero-initialized data at 0x80000000.
+@end table
+
+@node C-SKY Options
+@subsection C-SKY Options
+@cindex C-SKY Options
+
+GCC supports these options when compiling for C-SKY V2 processors.
+
+@table @gcctabopt
+
+@item -march=@var{arch}
+@opindex march=
+Specify the C-SKY target architecture.  Valid values for @var{arch} are:
+@samp{ck801}, @samp{ck802}, @samp{ck803}, @samp{ck807}, and @samp{ck810}.
+The default is @samp{ck810}.
+
+@item -mcpu=@var{cpu}
+@opindex mcpu=
+Specify the C-SKY target processor.  Valid values for @var{cpu} are:
+@samp{ck801}, @samp{ck801t},
+@samp{ck802}, @samp{ck802t}, @samp{ck802j},
+@samp{ck803}, @samp{ck803h}, @samp{ck803t}, @samp{ck803ht},
+@samp{ck803f}, @samp{ck803fh}, @samp{ck803e}, @samp{ck803eh},
+@samp{ck803et}, @samp{ck803eht}, @samp{ck803ef}, @samp{ck803efh},
+@samp{ck803ft}, @samp{ck803eft}, @samp{ck803efht}, @samp{ck803r1},
+@samp{ck803hr1}, @samp{ck803tr1}, @samp{ck803htr1}, @samp{ck803fr1},
+@samp{ck803fhr1}, @samp{ck803er1}, @samp{ck803ehr1}, @samp{ck803etr1},
+@samp{ck803ehtr1}, @samp{ck803efr1}, @samp{ck803efhr1}, @samp{ck803ftr1},
+@samp{ck803eftr1}, @samp{ck803efhtr1},
+@samp{ck803s}, @samp{ck803st}, @samp{ck803se}, @samp{ck803sf},
+@samp{ck803sef}, @samp{ck803seft},
+@samp{ck807e}, @samp{ck807ef}, @samp{ck807}, @samp{ck807f},
+@samp{ck810e}, @samp{ck810et}, @samp{ck810ef}, @samp{ck810eft},
+@samp{ck810}, @samp{ck810v}, @samp{ck810f}, @samp{ck810t}, @samp{ck810fv},
+@samp{ck810tv}, @samp{ck810ft}, and @samp{ck810ftv}.
+
+@item -mbig-endian
+@opindex mbig-endian
+@itemx -EB
+@opindex EB
+@itemx -mlittle-endian
+@opindex mlittle-endian
+@itemx -EL
+@opindex EL
+
+Select big- or little-endian code.  The default is little-endian.
+
+@item -mfloat-abi=@var{name}
+@opindex mfloat-abi
+Specifies which floating-point ABI to use.  Permissible values
+are: @samp{soft}, @samp{softfp} and @samp{hard}.
+
+Specifying @samp{soft} causes GCC to generate output containing
+library calls for floating-point operations.
+@samp{softfp} allows the generation of code using hardware floating-point
+instructions, but still uses the soft-float calling conventions.
+@samp{hard} allows generation of floating-point instructions
+and uses FPU-specific calling conventions.
+
+The default depends on the specific target configuration.  Note that
+the hard-float and soft-float ABIs are not link-compatible; you must
+compile your entire program with the same ABI, and link with a
+compatible set of libraries.
+
+@item -mhard-float
+@opindex mhard-float
+@itemx -msoft-float
+@opindex msoft-float
+
+Select hardware or software floating-point implementations.
+The default is soft float.
+
+@item -mdouble-float
+@itemx -mno-double-float
+@opindex mdouble-float
+When @option{-mhard-float} is in effect, enable generation of
+double-precision float instructions.  This is the default except
+when compiling for CK803.
+
+@item -mfdivdu
+@itemx -mno-fdivdu
+@opindex mfdivdu
+When @option{-mhard-float} is in effect, enable generation of
+@code{frecipd}, @code{fsqrtd}, and @code{fdivd} instructions.
+This is the default except when compiling for CK803.
+
+@item -mfpu=@var{fpu}
+@opindex mfpu=
+Select the floating-point processor.  This option can only be used with
+@option{-mhard-float}.
+Values for @var{fpu} are
+@samp{fpv2_sf} (equivalent to @samp{-mno-double-float -mno-fdivdu}),
+@samp{fpv2} (@samp{-mdouble-float -mno-divdu}), and
+@samp{fpv2_divd} (@samp{-mdouble-float -mdivdu}).
+
+@item -melrw
+@itemx -mno-elrw
+@opindex melrw
+Enable the extended @code{lrw} instruction.  This option defaults to on
+for CK801 and off otherwise.
+
+@item -mistack
+@itemx -mno-istack
+@opindex mistack
+Enable interrupt stack instructions; the default is off.
+
+The @option{-mistack} option is required to handle the
+@code{interrupt} and @code{isr} function attributes
+(@pxref{C-SKY Function Attributes}).
+
+@item -mmp
+@opindex mmp
+Enable multiprocessor instructions; the default is off.
+
+@item -mcp
+@opindex mcp
+Enable coprocessor instructions; the default is off.
+
+@item -mcache
+@opindex mcache
+Enable coprocessor instructions; the default is off.
+
+@item -msecurity
+@opindex msecurity
+Enable C-SKY security instructions; the default is off.
+
+@item -mtrust
+@opindex mtrust
+Enable C-SKY trust instructions; the default is off.
+
+@item -mdsp
+@opindex mdsp
+@itemx -medsp
+@opindex medsp
+@itemx -mvdsp
+@opindex mvdsp
+Enable C-SKY DSP, Enhanced DSP, or Vector DSP instructions, respectively.
+All of these options default to off.
+
+@item -mdiv
+@itemx -mno-div
+@opindex mdiv
+Generate divide instructions.  Default is off.
+
+@item -msmart
+@itemx -mno-smart
+@opindex msmart
+Generate code for Smart Mode, using only registers numbered 0-7 to allow
+use of 16-bit instructions.  This option is ignored for CK801 where this
+is the required behavior, and it defaults to on for CK802.
+For other targets, the default is off.
+
+@item -mhigh-registers
+@itemx -mno-high-registers
+@opindex mhigh-registers
+Generate code using the high registers numbered 16-31.  This option
+is not supported on CK801, CK802, or CK803, and is enabled by default
+for other processors.
+
+@item -manchor
+@itemx -mno-anchor
+@opindex manchor
+Generate code using global anchor symbol addresses.
+
+@item -mpushpop
+@itemx -mno-pushpop
+@opindex mpushpop
+Generate code using @code{push} and @code{pop} instructions.  This option
+defaults to on.
+
+@item -mmultiple-stld
+@itemx -mstm
+@itemx -mno-multiple-stld
+@itemx -mno-stm
+@opindex mmultiple-stld
+Generate code using @code{stm} and @code{ldm} instructions.  This option
+isn't supported on CK801 but is enabled by default on other processors.
+
+@item -mconstpool
+@itemx -mno-constpool
+@opindex mconstpool
+Create constant pools in the compiler instead of deferring it to the
+assembler.  This option is the default and required for correct code
+generation on CK801 and CK802, and is optional on other processors.
+
+@item -mstack-size
+@item -mno-stack-size
+@opindex mstack-size
+Emit @code{.stack_size} directives for each function in the assembly
+output.  This option defaults to off.
+
+@item -mccrt
+@itemx -mno-ccrt
+@opindex mccrt
+Generate code for the C-SKY compiler runtime instead of libgcc.  This
+option defaults to off.
+
+@item -mbranch-cost=@var{n}
+@opindex mbranch-cost=
+Set the branch costs to roughly @code{n} instructions.  The default is 1.
+
+@item -msched-prolog
+@itemx -mno-sched-prolog
+@opindex msched-prolog
+Permit scheduling of function prologue and epilogue sequences.  Using
+this option can result in code that is not compliant with the C-SKY V2 ABI
+prologue requirements and that cannot be debugged or backtraced.
+It is disabled by default.
+
+@item -msim
+@opindex msim
+Links the library libsemi.a which is in compatible with simulator. Applicable
+to ELF compiler only.
+
+@end table
+
+@node Darwin Options
+@subsection Darwin Options
+@cindex Darwin options
+
+These options are defined for all architectures running the Darwin operating
+system.
+
+FSF GCC on Darwin does not create ``fat'' object files; it creates
+an object file for the single architecture that GCC was built to
+target.  Apple's GCC on Darwin does create ``fat'' files if multiple
+@option{-arch} options are used; it does so by running the compiler or
+linker multiple times and joining the results together with
+@file{lipo}.
+
+The subtype of the file created (like @samp{ppc7400} or @samp{ppc970} or
+@samp{i686}) is determined by the flags that specify the ISA
+that GCC is targeting, like @option{-mcpu} or @option{-march}.  The
+@option{-force_cpusubtype_ALL} option can be used to override this.
+
+The Darwin tools vary in their behavior when presented with an ISA
+mismatch.  The assembler, @file{as}, only permits instructions to
+be used that are valid for the subtype of the file it is generating,
+so you cannot put 64-bit instructions in a @samp{ppc750} object file.
+The linker for shared libraries, @file{/usr/bin/libtool}, fails
+and prints an error if asked to create a shared library with a less
+restrictive subtype than its input files (for instance, trying to put
+a @samp{ppc970} object file in a @samp{ppc7400} library).  The linker
+for executables, @command{ld}, quietly gives the executable the most
+restrictive subtype of any of its input files.
+
+@table @gcctabopt
+@item -F@var{dir}
+@opindex F
+Add the framework directory @var{dir} to the head of the list of
+directories to be searched for header files.  These directories are
+interleaved with those specified by @option{-I} options and are
+scanned in a left-to-right order.
+
+A framework directory is a directory with frameworks in it.  A
+framework is a directory with a @file{Headers} and/or
+@file{PrivateHeaders} directory contained directly in it that ends
+in @file{.framework}.  The name of a framework is the name of this
+directory excluding the @file{.framework}.  Headers associated with
+the framework are found in one of those two directories, with
+@file{Headers} being searched first.  A subframework is a framework
+directory that is in a framework's @file{Frameworks} directory.
+Includes of subframework headers can only appear in a header of a
+framework that contains the subframework, or in a sibling subframework
+header.  Two subframeworks are siblings if they occur in the same
+framework.  A subframework should not have the same name as a
+framework; a warning is issued if this is violated.  Currently a
+subframework cannot have subframeworks; in the future, the mechanism
+may be extended to support this.  The standard frameworks can be found
+in @file{/System/Library/Frameworks} and
+@file{/Library/Frameworks}.  An example include looks like
+@code{#include <Framework/header.h>}, where @file{Framework} denotes
+the name of the framework and @file{header.h} is found in the
+@file{PrivateHeaders} or @file{Headers} directory.
+
+@item -iframework@var{dir}
+@opindex iframework
+Like @option{-F} except the directory is a treated as a system
+directory.  The main difference between this @option{-iframework} and
+@option{-F} is that with @option{-iframework} the compiler does not
+warn about constructs contained within header files found via
+@var{dir}.  This option is valid only for the C family of languages.
+
+@item -gused
+@opindex gused
+Emit debugging information for symbols that are used.  For stabs
+debugging format, this enables @option{-feliminate-unused-debug-symbols}.
+This is by default ON@.
+
+@item -gfull
+@opindex gfull
+Emit debugging information for all symbols and types.
+
+@item -mmacosx-version-min=@var{version}
+The earliest version of MacOS X that this executable will run on
+is @var{version}.  Typical values of @var{version} include @code{10.1},
+@code{10.2}, and @code{10.3.9}.
+
+If the compiler was built to use the system's headers by default,
+then the default for this option is the system version on which the
+compiler is running, otherwise the default is to make choices that
+are compatible with as many systems and code bases as possible.
+
+@item -mkernel
+@opindex mkernel
+Enable kernel development mode.  The @option{-mkernel} option sets
+@option{-static}, @option{-fno-common}, @option{-fno-use-cxa-atexit},
+@option{-fno-exceptions}, @option{-fno-non-call-exceptions},
+@option{-fapple-kext}, @option{-fno-weak} and @option{-fno-rtti} where
+applicable.  This mode also sets @option{-mno-altivec},
+@option{-msoft-float}, @option{-fno-builtin} and
+@option{-mlong-branch} for PowerPC targets.
+
+@item -mone-byte-bool
+@opindex mone-byte-bool
+Override the defaults for @code{bool} so that @code{sizeof(bool)==1}.
+By default @code{sizeof(bool)} is @code{4} when compiling for
+Darwin/PowerPC and @code{1} when compiling for Darwin/x86, so this
+option has no effect on x86.
+
+@strong{Warning:} The @option{-mone-byte-bool} switch causes GCC
+to generate code that is not binary compatible with code generated
+without that switch.  Using this switch may require recompiling all
+other modules in a program, including system libraries.  Use this
+switch to conform to a non-default data model.
+
+@item -mfix-and-continue
+@itemx -ffix-and-continue
+@itemx -findirect-data
+@opindex mfix-and-continue
+@opindex ffix-and-continue
+@opindex findirect-data
+Generate code suitable for fast turnaround development, such as to
+allow GDB to dynamically load @file{.o} files into already-running
+programs.  @option{-findirect-data} and @option{-ffix-and-continue}
+are provided for backwards compatibility.
+
+@item -all_load
+@opindex all_load
+Loads all members of static archive libraries.
+See man ld(1) for more information.
+
+@item -arch_errors_fatal
+@opindex arch_errors_fatal
+Cause the errors having to do with files that have the wrong architecture
+to be fatal.
+
+@item -bind_at_load
+@opindex bind_at_load
+Causes the output file to be marked such that the dynamic linker will
+bind all undefined references when the file is loaded or launched.
+
+@item -bundle
+@opindex bundle
+Produce a Mach-o bundle format file.
+See man ld(1) for more information.
+
+@item -bundle_loader @var{executable}
+@opindex bundle_loader
+This option specifies the @var{executable} that will load the build
+output file being linked.  See man ld(1) for more information.
+
+@item -dynamiclib
+@opindex dynamiclib
+When passed this option, GCC produces a dynamic library instead of
+an executable when linking, using the Darwin @file{libtool} command.
+
+@item -force_cpusubtype_ALL
+@opindex force_cpusubtype_ALL
+This causes GCC's output file to have the @samp{ALL} subtype, instead of
+one controlled by the @option{-mcpu} or @option{-march} option.
+
+@item -allowable_client  @var{client_name}
+@itemx -client_name
+@itemx -compatibility_version
+@itemx -current_version
+@itemx -dead_strip
+@itemx -dependency-file
+@itemx -dylib_file
+@itemx -dylinker_install_name
+@itemx -dynamic
+@itemx -exported_symbols_list
+@itemx -filelist
+@need 800
+@itemx -flat_namespace
+@itemx -force_flat_namespace
+@itemx -headerpad_max_install_names
+@itemx -image_base
+@itemx -init
+@itemx -install_name
+@itemx -keep_private_externs
+@itemx -multi_module
+@itemx -multiply_defined
+@itemx -multiply_defined_unused
+@need 800
+@itemx -noall_load
+@itemx -no_dead_strip_inits_and_terms
+@itemx -nofixprebinding
+@itemx -nomultidefs
+@itemx -noprebind
+@itemx -noseglinkedit
+@itemx -pagezero_size
+@itemx -prebind
+@itemx -prebind_all_twolevel_modules
+@itemx -private_bundle
+@need 800
+@itemx -read_only_relocs
+@itemx -sectalign
+@itemx -sectobjectsymbols
+@itemx -whyload
+@itemx -seg1addr
+@itemx -sectcreate
+@itemx -sectobjectsymbols
+@itemx -sectorder
+@itemx -segaddr
+@itemx -segs_read_only_addr
+@need 800
+@itemx -segs_read_write_addr
+@itemx -seg_addr_table
+@itemx -seg_addr_table_filename
+@itemx -seglinkedit
+@itemx -segprot
+@itemx -segs_read_only_addr
+@itemx -segs_read_write_addr
+@itemx -single_module
+@itemx -static
+@itemx -sub_library
+@need 800
+@itemx -sub_umbrella
+@itemx -twolevel_namespace
+@itemx -umbrella
+@itemx -undefined
+@itemx -unexported_symbols_list
+@itemx -weak_reference_mismatches
+@itemx -whatsloaded
+@opindex allowable_client
+@opindex client_name
+@opindex compatibility_version
+@opindex current_version
+@opindex dead_strip
+@opindex dependency-file
+@opindex dylib_file
+@opindex dylinker_install_name
+@opindex dynamic
+@opindex exported_symbols_list
+@opindex filelist
+@opindex flat_namespace
+@opindex force_flat_namespace
+@opindex headerpad_max_install_names
+@opindex image_base
+@opindex init
+@opindex install_name
+@opindex keep_private_externs
+@opindex multi_module
+@opindex multiply_defined
+@opindex multiply_defined_unused
+@opindex noall_load
+@opindex no_dead_strip_inits_and_terms
+@opindex nofixprebinding
+@opindex nomultidefs
+@opindex noprebind
+@opindex noseglinkedit
+@opindex pagezero_size
+@opindex prebind
+@opindex prebind_all_twolevel_modules
+@opindex private_bundle
+@opindex read_only_relocs
+@opindex sectalign
+@opindex sectobjectsymbols
+@opindex whyload
+@opindex seg1addr
+@opindex sectcreate
+@opindex sectobjectsymbols
+@opindex sectorder
+@opindex segaddr
+@opindex segs_read_only_addr
+@opindex segs_read_write_addr
+@opindex seg_addr_table
+@opindex seg_addr_table_filename
+@opindex seglinkedit
+@opindex segprot
+@opindex segs_read_only_addr
+@opindex segs_read_write_addr
+@opindex single_module
+@opindex static
+@opindex sub_library
+@opindex sub_umbrella
+@opindex twolevel_namespace
+@opindex umbrella
+@opindex undefined
+@opindex unexported_symbols_list
+@opindex weak_reference_mismatches
+@opindex whatsloaded
+These options are passed to the Darwin linker.  The Darwin linker man page
+describes them in detail.
+@end table
+
+@node DEC Alpha Options
+@subsection DEC Alpha Options
+
+These @samp{-m} options are defined for the DEC Alpha implementations:
+
+@table @gcctabopt
+@item -mno-soft-float
+@itemx -msoft-float
+@opindex mno-soft-float
+@opindex msoft-float
+Use (do not use) the hardware floating-point instructions for
+floating-point operations.  When @option{-msoft-float} is specified,
+functions in @file{libgcc.a} are used to perform floating-point
+operations.  Unless they are replaced by routines that emulate the
+floating-point operations, or compiled in such a way as to call such
+emulations routines, these routines issue floating-point
+operations.   If you are compiling for an Alpha without floating-point
+operations, you must ensure that the library is built so as not to call
+them.
+
+Note that Alpha implementations without floating-point operations are
+required to have floating-point registers.
+
+@item -mfp-reg
+@itemx -mno-fp-regs
+@opindex mfp-reg
+@opindex mno-fp-regs
+Generate code that uses (does not use) the floating-point register set.
+@option{-mno-fp-regs} implies @option{-msoft-float}.  If the floating-point
+register set is not used, floating-point operands are passed in integer
+registers as if they were integers and floating-point results are passed
+in @code{$0} instead of @code{$f0}.  This is a non-standard calling sequence,
+so any function with a floating-point argument or return value called by code
+compiled with @option{-mno-fp-regs} must also be compiled with that
+option.
+
+A typical use of this option is building a kernel that does not use,
+and hence need not save and restore, any floating-point registers.
+
+@item -mieee
+@opindex mieee
+The Alpha architecture implements floating-point hardware optimized for
+maximum performance.  It is mostly compliant with the IEEE floating-point
+standard.  However, for full compliance, software assistance is
+required.  This option generates code fully IEEE-compliant code
+@emph{except} that the @var{inexact-flag} is not maintained (see below).
+If this option is turned on, the preprocessor macro @code{_IEEE_FP} is
+defined during compilation.  The resulting code is less efficient but is
+able to correctly support denormalized numbers and exceptional IEEE
+values such as not-a-number and plus/minus infinity.  Other Alpha
+compilers call this option @option{-ieee_with_no_inexact}.
+
+@item -mieee-with-inexact
+@opindex mieee-with-inexact
+This is like @option{-mieee} except the generated code also maintains
+the IEEE @var{inexact-flag}.  Turning on this option causes the
+generated code to implement fully-compliant IEEE math.  In addition to
+@code{_IEEE_FP}, @code{_IEEE_FP_EXACT} is defined as a preprocessor
+macro.  On some Alpha implementations the resulting code may execute
+significantly slower than the code generated by default.  Since there is
+very little code that depends on the @var{inexact-flag}, you should
+normally not specify this option.  Other Alpha compilers call this
+option @option{-ieee_with_inexact}.
+
+@item -mfp-trap-mode=@var{trap-mode}
+@opindex mfp-trap-mode
+This option controls what floating-point related traps are enabled.
+Other Alpha compilers call this option @option{-fptm @var{trap-mode}}.
+The trap mode can be set to one of four values:
+
+@table @samp
+@item n
+This is the default (normal) setting.  The only traps that are enabled
+are the ones that cannot be disabled in software (e.g., division by zero
+trap).
+
+@item u
+In addition to the traps enabled by @samp{n}, underflow traps are enabled
+as well.
+
+@item su
+Like @samp{u}, but the instructions are marked to be safe for software
+completion (see Alpha architecture manual for details).
+
+@item sui
+Like @samp{su}, but inexact traps are enabled as well.
+@end table
+
+@item -mfp-rounding-mode=@var{rounding-mode}
+@opindex mfp-rounding-mode
+Selects the IEEE rounding mode.  Other Alpha compilers call this option
+@option{-fprm @var{rounding-mode}}.  The @var{rounding-mode} can be one
+of:
+
+@table @samp
+@item n
+Normal IEEE rounding mode.  Floating-point numbers are rounded towards
+the nearest machine number or towards the even machine number in case
+of a tie.
+
+@item m
+Round towards minus infinity.
+
+@item c
+Chopped rounding mode.  Floating-point numbers are rounded towards zero.
+
+@item d
+Dynamic rounding mode.  A field in the floating-point control register
+(@var{fpcr}, see Alpha architecture reference manual) controls the
+rounding mode in effect.  The C library initializes this register for
+rounding towards plus infinity.  Thus, unless your program modifies the
+@var{fpcr}, @samp{d} corresponds to round towards plus infinity.
+@end table
+
+@item -mtrap-precision=@var{trap-precision}
+@opindex mtrap-precision
+In the Alpha architecture, floating-point traps are imprecise.  This
+means without software assistance it is impossible to recover from a
+floating trap and program execution normally needs to be terminated.
+GCC can generate code that can assist operating system trap handlers
+in determining the exact location that caused a floating-point trap.
+Depending on the requirements of an application, different levels of
+precisions can be selected:
+
+@table @samp
+@item p
+Program precision.  This option is the default and means a trap handler
+can only identify which program caused a floating-point exception.
+
+@item f
+Function precision.  The trap handler can determine the function that
+caused a floating-point exception.
+
+@item i
+Instruction precision.  The trap handler can determine the exact
+instruction that caused a floating-point exception.
+@end table
+
+Other Alpha compilers provide the equivalent options called
+@option{-scope_safe} and @option{-resumption_safe}.
+
+@item -mieee-conformant
+@opindex mieee-conformant
+This option marks the generated code as IEEE conformant.  You must not
+use this option unless you also specify @option{-mtrap-precision=i} and either
+@option{-mfp-trap-mode=su} or @option{-mfp-trap-mode=sui}.  Its only effect
+is to emit the line @samp{.eflag 48} in the function prologue of the
+generated assembly file.
+
+@item -mbuild-constants
+@opindex mbuild-constants
+Normally GCC examines a 32- or 64-bit integer constant to
+see if it can construct it from smaller constants in two or three
+instructions.  If it cannot, it outputs the constant as a literal and
+generates code to load it from the data segment at run time.
+
+Use this option to require GCC to construct @emph{all} integer constants
+using code, even if it takes more instructions (the maximum is six).
+
+You typically use this option to build a shared library dynamic
+loader.  Itself a shared library, it must relocate itself in memory
+before it can find the variables and constants in its own data segment.
+
+@item -mbwx
+@itemx -mno-bwx
+@itemx -mcix
+@itemx -mno-cix
+@itemx -mfix
+@itemx -mno-fix
+@itemx -mmax
+@itemx -mno-max
+@opindex mbwx
+@opindex mno-bwx
+@opindex mcix
+@opindex mno-cix
+@opindex mfix
+@opindex mno-fix
+@opindex mmax
+@opindex mno-max
+Indicate whether GCC should generate code to use the optional BWX,
+CIX, FIX and MAX instruction sets.  The default is to use the instruction
+sets supported by the CPU type specified via @option{-mcpu=} option or that
+of the CPU on which GCC was built if none is specified.
+
+@item -mfloat-vax
+@itemx -mfloat-ieee
+@opindex mfloat-vax
+@opindex mfloat-ieee
+Generate code that uses (does not use) VAX F and G floating-point
+arithmetic instead of IEEE single and double precision.
+
+@item -mexplicit-relocs
+@itemx -mno-explicit-relocs
+@opindex mexplicit-relocs
+@opindex mno-explicit-relocs
+Older Alpha assemblers provided no way to generate symbol relocations
+except via assembler macros.  Use of these macros does not allow
+optimal instruction scheduling.  GNU binutils as of version 2.12
+supports a new syntax that allows the compiler to explicitly mark
+which relocations should apply to which instructions.  This option
+is mostly useful for debugging, as GCC detects the capabilities of
+the assembler when it is built and sets the default accordingly.
+
+@item -msmall-data
+@itemx -mlarge-data
+@opindex msmall-data
+@opindex mlarge-data
+When @option{-mexplicit-relocs} is in effect, static data is
+accessed via @dfn{gp-relative} relocations.  When @option{-msmall-data}
+is used, objects 8 bytes long or smaller are placed in a @dfn{small data area}
+(the @code{.sdata} and @code{.sbss} sections) and are accessed via
+16-bit relocations off of the @code{$gp} register.  This limits the
+size of the small data area to 64KB, but allows the variables to be
+directly accessed via a single instruction.
+
+The default is @option{-mlarge-data}.  With this option the data area
+is limited to just below 2GB@.  Programs that require more than 2GB of
+data must use @code{malloc} or @code{mmap} to allocate the data in the
+heap instead of in the program's data segment.
+
+When generating code for shared libraries, @option{-fpic} implies
+@option{-msmall-data} and @option{-fPIC} implies @option{-mlarge-data}.
+
+@item -msmall-text
+@itemx -mlarge-text
+@opindex msmall-text
+@opindex mlarge-text
+When @option{-msmall-text} is used, the compiler assumes that the
+code of the entire program (or shared library) fits in 4MB, and is
+thus reachable with a branch instruction.  When @option{-msmall-data}
+is used, the compiler can assume that all local symbols share the
+same @code{$gp} value, and thus reduce the number of instructions
+required for a function call from 4 to 1.
+
+The default is @option{-mlarge-text}.
+
+@item -mcpu=@var{cpu_type}
+@opindex mcpu
+Set the instruction set and instruction scheduling parameters for
+machine type @var{cpu_type}.  You can specify either the @samp{EV}
+style name or the corresponding chip number.  GCC supports scheduling
+parameters for the EV4, EV5 and EV6 family of processors and
+chooses the default values for the instruction set from the processor
+you specify.  If you do not specify a processor type, GCC defaults
+to the processor on which the compiler was built.
+
+Supported values for @var{cpu_type} are
+
+@table @samp
+@item ev4
+@itemx ev45
+@itemx 21064
+Schedules as an EV4 and has no instruction set extensions.
+
+@item ev5
+@itemx 21164
+Schedules as an EV5 and has no instruction set extensions.
+
+@item ev56
+@itemx 21164a
+Schedules as an EV5 and supports the BWX extension.
+
+@item pca56
+@itemx 21164pc
+@itemx 21164PC
+Schedules as an EV5 and supports the BWX and MAX extensions.
+
+@item ev6
+@itemx 21264
+Schedules as an EV6 and supports the BWX, FIX, and MAX extensions.
+
+@item ev67
+@itemx 21264a
+Schedules as an EV6 and supports the BWX, CIX, FIX, and MAX extensions.
+@end table
+
+Native toolchains also support the value @samp{native},
+which selects the best architecture option for the host processor.
+@option{-mcpu=native} has no effect if GCC does not recognize
+the processor.
+
+@item -mtune=@var{cpu_type}
+@opindex mtune
+Set only the instruction scheduling parameters for machine type
+@var{cpu_type}.  The instruction set is not changed.
+
+Native toolchains also support the value @samp{native},
+which selects the best architecture option for the host processor.
+@option{-mtune=native} has no effect if GCC does not recognize
+the processor.
+
+@item -mmemory-latency=@var{time}
+@opindex mmemory-latency
+Sets the latency the scheduler should assume for typical memory
+references as seen by the application.  This number is highly
+dependent on the memory access patterns used by the application
+and the size of the external cache on the machine.
+
+Valid options for @var{time} are
+
+@table @samp
+@item @var{number}
+A decimal number representing clock cycles.
+
+@item L1
+@itemx L2
+@itemx L3
+@itemx main
+The compiler contains estimates of the number of clock cycles for
+``typical'' EV4 & EV5 hardware for the Level 1, 2 & 3 caches
+(also called Dcache, Scache, and Bcache), as well as to main memory.
+Note that L3 is only valid for EV5.
+
+@end table
+@end table
+
+@node eBPF Options
+@subsection eBPF Options
+@cindex eBPF Options
+
+@table @gcctabopt
+@item -mframe-limit=@var{bytes}
+This specifies the hard limit for frame sizes, in bytes.  Currently,
+the value that can be specified should be less than or equal to
+@samp{32767}.  Defaults to whatever limit is imposed by the version of
+the Linux kernel targeted.
+
+@item -mkernel=@var{version}
+@opindex mkernel
+This specifies the minimum version of the kernel that will run the
+compiled program.  GCC uses this version to determine which
+instructions to use, what kernel helpers to allow, etc.  Currently,
+@var{version} can be one of @samp{4.0}, @samp{4.1}, @samp{4.2},
+@samp{4.3}, @samp{4.4}, @samp{4.5}, @samp{4.6}, @samp{4.7},
+@samp{4.8}, @samp{4.9}, @samp{4.10}, @samp{4.11}, @samp{4.12},
+@samp{4.13}, @samp{4.14}, @samp{4.15}, @samp{4.16}, @samp{4.17},
+@samp{4.18}, @samp{4.19}, @samp{4.20}, @samp{5.0}, @samp{5.1},
+@samp{5.2}, @samp{latest} and @samp{native}.
+
+@item -mbig-endian
+@opindex mbig-endian
+Generate code for a big-endian target.
+
+@item -mlittle-endian
+@opindex mlittle-endian
+Generate code for a little-endian target.  This is the default.
+
+@item -mjmpext
+@opindex mjmpext
+Enable generation of extra conditional-branch instructions.
+Enabled for CPU v2 and above.
+
+@item -mjmp32
+@opindex mjmp32
+Enable 32-bit jump instructions. Enabled for CPU v3 and above.
+
+@item -malu32
+@opindex malu32
+Enable 32-bit ALU instructions. Enabled for CPU v3 and above.
+
+@item -mcpu=@var{version}
+@opindex mcpu
+This specifies which version of the eBPF ISA to target. Newer versions
+may not be supported by all kernels. The default is @samp{v3}.
+
+Supported values for @var{version} are:
+
+@table @samp
+@item v1
+The first stable eBPF ISA with no special features or extensions.
+
+@item v2
+Supports the jump extensions, as in @option{-mjmpext}.
+
+@item v3
+All features of v2, plus:
+@itemize @minus
+@item 32-bit jump operations, as in @option{-mjmp32}
+@item 32-bit ALU operations, as in @option{-malu32}
+@end itemize
+
+@end table
+
+@item -mco-re
+@opindex mco-re
+Enable BPF Compile Once - Run Everywhere (CO-RE) support. Requires and
+is implied by @option{-gbtf}.
+
+@item -mno-co-re
+@opindex mno-co-re
+Disable BPF Compile Once - Run Everywhere (CO-RE) support. BPF CO-RE
+support is enabled by default when generating BTF debug information for
+the BPF target.
+
+@item -mxbpf
+Generate code for an expanded version of BPF, which relaxes some of
+the restrictions imposed by the BPF architecture:
+@itemize @minus
+@item Save and restore callee-saved registers at function entry and
+exit, respectively.
+@end itemize
+@end table
+
+@node FR30 Options
+@subsection FR30 Options
+@cindex FR30 Options
+
+These options are defined specifically for the FR30 port.
+
+@table @gcctabopt
+
+@item -msmall-model
+@opindex msmall-model
+Use the small address space model.  This can produce smaller code, but
+it does assume that all symbolic values and addresses fit into a
+20-bit range.
+
+@item -mno-lsim
+@opindex mno-lsim
+Assume that runtime support has been provided and so there is no need
+to include the simulator library (@file{libsim.a}) on the linker
+command line.
+
+@end table
+
+@node FT32 Options
+@subsection FT32 Options
+@cindex FT32 Options
+
+These options are defined specifically for the FT32 port.
+
+@table @gcctabopt
+
+@item -msim
+@opindex msim
+Specifies that the program will be run on the simulator.  This causes
+an alternate runtime startup and library to be linked.
+You must not use this option when generating programs that will run on
+real hardware; you must provide your own runtime library for whatever
+I/O functions are needed.
+
+@item -mlra
+@opindex mlra
+Enable Local Register Allocation.  This is still experimental for FT32,
+so by default the compiler uses standard reload.
+
+@item -mnodiv
+@opindex mnodiv
+Do not use div and mod instructions.
+
+@item -mft32b
+@opindex mft32b
+Enable use of the extended instructions of the FT32B processor.
+
+@item -mcompress
+@opindex mcompress
+Compress all code using the Ft32B code compression scheme.
+
+@item -mnopm
+@opindex  mnopm
+Do not generate code that reads program memory.
+
+@end table
+
+@node FRV Options
+@subsection FRV Options
+@cindex FRV Options
+
+@table @gcctabopt
+@item -mgpr-32
+@opindex mgpr-32
+
+Only use the first 32 general-purpose registers.
+
+@item -mgpr-64
+@opindex mgpr-64
+
+Use all 64 general-purpose registers.
+
+@item -mfpr-32
+@opindex mfpr-32
+
+Use only the first 32 floating-point registers.
+
+@item -mfpr-64
+@opindex mfpr-64
+
+Use all 64 floating-point registers.
+
+@item -mhard-float
+@opindex mhard-float
+
+Use hardware instructions for floating-point operations.
+
+@item -msoft-float
+@opindex msoft-float
+
+Use library routines for floating-point operations.
+
+@item -malloc-cc
+@opindex malloc-cc
+
+Dynamically allocate condition code registers.
+
+@item -mfixed-cc
+@opindex mfixed-cc
+
+Do not try to dynamically allocate condition code registers, only
+use @code{icc0} and @code{fcc0}.
+
+@item -mdword
+@opindex mdword
+
+Change ABI to use double word insns.
+
+@item -mno-dword
+@opindex mno-dword
+@opindex mdword
+
+Do not use double word instructions.
+
+@item -mdouble
+@opindex mdouble
+
+Use floating-point double instructions.
+
+@item -mno-double
+@opindex mno-double
+
+Do not use floating-point double instructions.
+
+@item -mmedia
+@opindex mmedia
+
+Use media instructions.
+
+@item -mno-media
+@opindex mno-media
+
+Do not use media instructions.
+
+@item -mmuladd
+@opindex mmuladd
+
+Use multiply and add/subtract instructions.
+
+@item -mno-muladd
+@opindex mno-muladd
+
+Do not use multiply and add/subtract instructions.
+
+@item -mfdpic
+@opindex mfdpic
+
+Select the FDPIC ABI, which uses function descriptors to represent
+pointers to functions.  Without any PIC/PIE-related options, it
+implies @option{-fPIE}.  With @option{-fpic} or @option{-fpie}, it
+assumes GOT entries and small data are within a 12-bit range from the
+GOT base address; with @option{-fPIC} or @option{-fPIE}, GOT offsets
+are computed with 32 bits.
+With a @samp{bfin-elf} target, this option implies @option{-msim}.
+
+@item -minline-plt
+@opindex minline-plt
+
+Enable inlining of PLT entries in function calls to functions that are
+not known to bind locally.  It has no effect without @option{-mfdpic}.
+It's enabled by default if optimizing for speed and compiling for
+shared libraries (i.e., @option{-fPIC} or @option{-fpic}), or when an
+optimization option such as @option{-O3} or above is present in the
+command line.
+
+@item -mTLS
+@opindex mTLS
+
+Assume a large TLS segment when generating thread-local code.
+
+@item -mtls
+@opindex mtls
+
+Do not assume a large TLS segment when generating thread-local code.
+
+@item -mgprel-ro
+@opindex mgprel-ro
+
+Enable the use of @code{GPREL} relocations in the FDPIC ABI for data
+that is known to be in read-only sections.  It's enabled by default,
+except for @option{-fpic} or @option{-fpie}: even though it may help
+make the global offset table smaller, it trades 1 instruction for 4.
+With @option{-fPIC} or @option{-fPIE}, it trades 3 instructions for 4,
+one of which may be shared by multiple symbols, and it avoids the need
+for a GOT entry for the referenced symbol, so it's more likely to be a
+win.  If it is not, @option{-mno-gprel-ro} can be used to disable it.
+
+@item -multilib-library-pic
+@opindex multilib-library-pic
+
+Link with the (library, not FD) pic libraries.  It's implied by
+@option{-mlibrary-pic}, as well as by @option{-fPIC} and
+@option{-fpic} without @option{-mfdpic}.  You should never have to use
+it explicitly.
+
+@item -mlinked-fp
+@opindex mlinked-fp
+
+Follow the EABI requirement of always creating a frame pointer whenever
+a stack frame is allocated.  This option is enabled by default and can
+be disabled with @option{-mno-linked-fp}.
+
+@item -mlong-calls
+@opindex mlong-calls
+
+Use indirect addressing to call functions outside the current
+compilation unit.  This allows the functions to be placed anywhere
+within the 32-bit address space.
+
+@item -malign-labels
+@opindex malign-labels
+
+Try to align labels to an 8-byte boundary by inserting NOPs into the
+previous packet.  This option only has an effect when VLIW packing
+is enabled.  It doesn't create new packets; it merely adds NOPs to
+existing ones.
+
+@item -mlibrary-pic
+@opindex mlibrary-pic
+
+Generate position-independent EABI code.
+
+@item -macc-4
+@opindex macc-4
+
+Use only the first four media accumulator registers.
+
+@item -macc-8
+@opindex macc-8
+
+Use all eight media accumulator registers.
+
+@item -mpack
+@opindex mpack
+
+Pack VLIW instructions.
+
+@item -mno-pack
+@opindex mno-pack
+
+Do not pack VLIW instructions.
+
+@item -mno-eflags
+@opindex mno-eflags
+
+Do not mark ABI switches in e_flags.
+
+@item -mcond-move
+@opindex mcond-move
+
+Enable the use of conditional-move instructions (default).
+
+This switch is mainly for debugging the compiler and will likely be removed
+in a future version.
+
+@item -mno-cond-move
+@opindex mno-cond-move
+
+Disable the use of conditional-move instructions.
+
+This switch is mainly for debugging the compiler and will likely be removed
+in a future version.
+
+@item -mscc
+@opindex mscc
+
+Enable the use of conditional set instructions (default).
+
+This switch is mainly for debugging the compiler and will likely be removed
+in a future version.
+
+@item -mno-scc
+@opindex mno-scc
+
+Disable the use of conditional set instructions.
+
+This switch is mainly for debugging the compiler and will likely be removed
+in a future version.
+
+@item -mcond-exec
+@opindex mcond-exec
+
+Enable the use of conditional execution (default).
+
+This switch is mainly for debugging the compiler and will likely be removed
+in a future version.
+
+@item -mno-cond-exec
+@opindex mno-cond-exec
+
+Disable the use of conditional execution.
+
+This switch is mainly for debugging the compiler and will likely be removed
+in a future version.
+
+@item -mvliw-branch
+@opindex mvliw-branch
+
+Run a pass to pack branches into VLIW instructions (default).
+
+This switch is mainly for debugging the compiler and will likely be removed
+in a future version.
+
+@item -mno-vliw-branch
+@opindex mno-vliw-branch
+
+Do not run a pass to pack branches into VLIW instructions.
+
+This switch is mainly for debugging the compiler and will likely be removed
+in a future version.
+
+@item -mmulti-cond-exec
+@opindex mmulti-cond-exec
+
+Enable optimization of @code{&&} and @code{||} in conditional execution
+(default).
+
+This switch is mainly for debugging the compiler and will likely be removed
+in a future version.
+
+@item -mno-multi-cond-exec
+@opindex mno-multi-cond-exec
+
+Disable optimization of @code{&&} and @code{||} in conditional execution.
+
+This switch is mainly for debugging the compiler and will likely be removed
+in a future version.
+
+@item -mnested-cond-exec
+@opindex mnested-cond-exec
+
+Enable nested conditional execution optimizations (default).
+
+This switch is mainly for debugging the compiler and will likely be removed
+in a future version.
+
+@item -mno-nested-cond-exec
+@opindex mno-nested-cond-exec
+
+Disable nested conditional execution optimizations.
+
+This switch is mainly for debugging the compiler and will likely be removed
+in a future version.
+
+@item -moptimize-membar
+@opindex moptimize-membar
+
+This switch removes redundant @code{membar} instructions from the
+compiler-generated code.  It is enabled by default.
+
+@item -mno-optimize-membar
+@opindex mno-optimize-membar
+@opindex moptimize-membar
+
+This switch disables the automatic removal of redundant @code{membar}
+instructions from the generated code.
+
+@item -mtomcat-stats
+@opindex mtomcat-stats
+
+Cause gas to print out tomcat statistics.
+
+@item -mcpu=@var{cpu}
+@opindex mcpu
+
+Select the processor type for which to generate code.  Possible values are
+@samp{frv}, @samp{fr550}, @samp{tomcat}, @samp{fr500}, @samp{fr450},
+@samp{fr405}, @samp{fr400}, @samp{fr300} and @samp{simple}.
+
+@end table
+
+@node GNU/Linux Options
+@subsection GNU/Linux Options
+
+These @samp{-m} options are defined for GNU/Linux targets:
+
+@table @gcctabopt
+@item -mglibc
+@opindex mglibc
+Use the GNU C library.  This is the default except
+on @samp{*-*-linux-*uclibc*}, @samp{*-*-linux-*musl*} and
+@samp{*-*-linux-*android*} targets.
+
+@item -muclibc
+@opindex muclibc
+Use uClibc C library.  This is the default on
+@samp{*-*-linux-*uclibc*} targets.
+
+@item -mmusl
+@opindex mmusl
+Use the musl C library.  This is the default on
+@samp{*-*-linux-*musl*} targets.
+
+@item -mbionic
+@opindex mbionic
+Use Bionic C library.  This is the default on
+@samp{*-*-linux-*android*} targets.
+
+@item -mandroid
+@opindex mandroid
+Compile code compatible with Android platform.  This is the default on
+@samp{*-*-linux-*android*} targets.
+
+When compiling, this option enables @option{-mbionic}, @option{-fPIC},
+@option{-fno-exceptions} and @option{-fno-rtti} by default.  When linking,
+this option makes the GCC driver pass Android-specific options to the linker.
+Finally, this option causes the preprocessor macro @code{__ANDROID__}
+to be defined.
+
+@item -tno-android-cc
+@opindex tno-android-cc
+Disable compilation effects of @option{-mandroid}, i.e., do not enable
+@option{-mbionic}, @option{-fPIC}, @option{-fno-exceptions} and
+@option{-fno-rtti} by default.
+
+@item -tno-android-ld
+@opindex tno-android-ld
+Disable linking effects of @option{-mandroid}, i.e., pass standard Linux
+linking options to the linker.
+
+@end table
+
+@node H8/300 Options
+@subsection H8/300 Options
+
+These @samp{-m} options are defined for the H8/300 implementations:
+
+@table @gcctabopt
+@item -mrelax
+@opindex mrelax
+Shorten some address references at link time, when possible; uses the
+linker option @option{-relax}.  @xref{H8/300,, @code{ld} and the H8/300,
+ld, Using ld}, for a fuller description.
+
+@item -mh
+@opindex mh
+Generate code for the H8/300H@.
+
+@item -ms
+@opindex ms
+Generate code for the H8S@.
+
+@item -mn
+@opindex mn
+Generate code for the H8S and H8/300H in the normal mode.  This switch
+must be used either with @option{-mh} or @option{-ms}.
+
+@item -ms2600
+@opindex ms2600
+Generate code for the H8S/2600.  This switch must be used with @option{-ms}.
+
+@item -mexr
+@opindex mexr
+Extended registers are stored on stack before execution of function
+with monitor attribute. Default option is @option{-mexr}.
+This option is valid only for H8S targets.
+
+@item -mno-exr
+@opindex mno-exr
+@opindex mexr
+Extended registers are not stored on stack before execution of function 
+with monitor attribute. Default option is @option{-mno-exr}. 
+This option is valid only for H8S targets.
+
+@item -mint32
+@opindex mint32
+Make @code{int} data 32 bits by default.
+
+@item -malign-300
+@opindex malign-300
+On the H8/300H and H8S, use the same alignment rules as for the H8/300.
+The default for the H8/300H and H8S is to align longs and floats on
+4-byte boundaries.
+@option{-malign-300} causes them to be aligned on 2-byte boundaries.
+This option has no effect on the H8/300.
+@end table
+
+@node HPPA Options
+@subsection HPPA Options
+@cindex HPPA Options
+
+These @samp{-m} options are defined for the HPPA family of computers:
+
+@table @gcctabopt
+@item -march=@var{architecture-type}
+@opindex march
+Generate code for the specified architecture.  The choices for
+@var{architecture-type} are @samp{1.0} for PA 1.0, @samp{1.1} for PA
+1.1, and @samp{2.0} for PA 2.0 processors.  Refer to
+@file{/usr/lib/sched.models} on an HP-UX system to determine the proper
+architecture option for your machine.  Code compiled for lower numbered
+architectures runs on higher numbered architectures, but not the
+other way around.
+
+@item -mpa-risc-1-0
+@itemx -mpa-risc-1-1
+@itemx -mpa-risc-2-0
+@opindex mpa-risc-1-0
+@opindex mpa-risc-1-1
+@opindex mpa-risc-2-0
+Synonyms for @option{-march=1.0}, @option{-march=1.1}, and @option{-march=2.0} respectively.
+
+@item -mcaller-copies
+@opindex mcaller-copies
+The caller copies function arguments passed by hidden reference.  This
+option should be used with care as it is not compatible with the default
+32-bit runtime.  However, only aggregates larger than eight bytes are
+passed by hidden reference and the option provides better compatibility
+with OpenMP.
+
+@item -mjump-in-delay
+@opindex mjump-in-delay
+This option is ignored and provided for compatibility purposes only.
+
+@item -mdisable-fpregs
+@opindex mdisable-fpregs
+Prevent floating-point registers from being used in any manner.  This is
+necessary for compiling kernels that perform lazy context switching of
+floating-point registers.  If you use this option and attempt to perform
+floating-point operations, the compiler aborts.
+
+@item -mdisable-indexing
+@opindex mdisable-indexing
+Prevent the compiler from using indexing address modes.  This avoids some
+rather obscure problems when compiling MIG generated code under MACH@.
+
+@item -mno-space-regs
+@opindex mno-space-regs
+@opindex mspace-regs
+Generate code that assumes the target has no space registers.  This allows
+GCC to generate faster indirect calls and use unscaled index address modes.
+
+Such code is suitable for level 0 PA systems and kernels.
+
+@item -mfast-indirect-calls
+@opindex mfast-indirect-calls
+Generate code that assumes calls never cross space boundaries.  This
+allows GCC to emit code that performs faster indirect calls.
+
+This option does not work in the presence of shared libraries or nested
+functions.
+
+@item -mfixed-range=@var{register-range}
+@opindex mfixed-range
+Generate code treating the given register range as fixed registers.
+A fixed register is one that the register allocator cannot use.  This is
+useful when compiling kernel code.  A register range is specified as
+two registers separated by a dash.  Multiple register ranges can be
+specified separated by a comma.
+
+@item -mlong-load-store
+@opindex mlong-load-store
+Generate 3-instruction load and store sequences as sometimes required by
+the HP-UX 10 linker.  This is equivalent to the @samp{+k} option to
+the HP compilers.
+
+@item -mportable-runtime
+@opindex mportable-runtime
+Use the portable calling conventions proposed by HP for ELF systems.
+
+@item -mgas
+@opindex mgas
+Enable the use of assembler directives only GAS understands.
+
+@item -mschedule=@var{cpu-type}
+@opindex mschedule
+Schedule code according to the constraints for the machine type
+@var{cpu-type}.  The choices for @var{cpu-type} are @samp{700}
+@samp{7100}, @samp{7100LC}, @samp{7200}, @samp{7300} and @samp{8000}.  Refer
+to @file{/usr/lib/sched.models} on an HP-UX system to determine the
+proper scheduling option for your machine.  The default scheduling is
+@samp{8000}.
+
+@item -mlinker-opt
+@opindex mlinker-opt
+Enable the optimization pass in the HP-UX linker.  Note this makes symbolic
+debugging impossible.  It also triggers a bug in the HP-UX 8 and HP-UX 9
+linkers in which they give bogus error messages when linking some programs.
+
+@item -msoft-float
+@opindex msoft-float
+Generate output containing library calls for floating point.
+@strong{Warning:} the requisite libraries are not available for all HPPA
+targets.  Normally the facilities of the machine's usual C compiler are
+used, but this cannot be done directly in cross-compilation.  You must make
+your own arrangements to provide suitable library functions for
+cross-compilation.
+
+@option{-msoft-float} changes the calling convention in the output file;
+therefore, it is only useful if you compile @emph{all} of a program with
+this option.  In particular, you need to compile @file{libgcc.a}, the
+library that comes with GCC, with @option{-msoft-float} in order for
+this to work.
+
+@item -msio
+@opindex msio
+Generate the predefine, @code{_SIO}, for server IO@.  The default is
+@option{-mwsio}.  This generates the predefines, @code{__hp9000s700},
+@code{__hp9000s700__} and @code{_WSIO}, for workstation IO@.  These
+options are available under HP-UX and HI-UX@.
+
+@item -mgnu-ld
+@opindex mgnu-ld
+Use options specific to GNU @command{ld}.
+This passes @option{-shared} to @command{ld} when
+building a shared library.  It is the default when GCC is configured,
+explicitly or implicitly, with the GNU linker.  This option does not
+affect which @command{ld} is called; it only changes what parameters
+are passed to that @command{ld}.
+The @command{ld} that is called is determined by the
+@option{--with-ld} configure option, GCC's program search path, and
+finally by the user's @env{PATH}.  The linker used by GCC can be printed
+using @samp{which `gcc -print-prog-name=ld`}.  This option is only available
+on the 64-bit HP-UX GCC, i.e.@: configured with @samp{hppa*64*-*-hpux*}.
+
+@item -mhp-ld
+@opindex mhp-ld
+Use options specific to HP @command{ld}.
+This passes @option{-b} to @command{ld} when building
+a shared library and passes @option{+Accept TypeMismatch} to @command{ld} on all
+links.  It is the default when GCC is configured, explicitly or
+implicitly, with the HP linker.  This option does not affect
+which @command{ld} is called; it only changes what parameters are passed to that
+@command{ld}.
+The @command{ld} that is called is determined by the @option{--with-ld}
+configure option, GCC's program search path, and finally by the user's
+@env{PATH}.  The linker used by GCC can be printed using @samp{which
+`gcc -print-prog-name=ld`}.  This option is only available on the 64-bit
+HP-UX GCC, i.e.@: configured with @samp{hppa*64*-*-hpux*}.
+
+@item -mlong-calls
+@opindex mno-long-calls
+@opindex mlong-calls
+Generate code that uses long call sequences.  This ensures that a call
+is always able to reach linker generated stubs.  The default is to generate
+long calls only when the distance from the call site to the beginning
+of the function or translation unit, as the case may be, exceeds a
+predefined limit set by the branch type being used.  The limits for
+normal calls are 7,600,000 and 240,000 bytes, respectively for the
+PA 2.0 and PA 1.X architectures.  Sibcalls are always limited at
+240,000 bytes.
+
+Distances are measured from the beginning of functions when using the
+@option{-ffunction-sections} option, or when using the @option{-mgas}
+and @option{-mno-portable-runtime} options together under HP-UX with
+the SOM linker.
+
+It is normally not desirable to use this option as it degrades
+performance.  However, it may be useful in large applications,
+particularly when partial linking is used to build the application.
+
+The types of long calls used depends on the capabilities of the
+assembler and linker, and the type of code being generated.  The
+impact on systems that support long absolute calls, and long pic
+symbol-difference or pc-relative calls should be relatively small.
+However, an indirect call is used on 32-bit ELF systems in pic code
+and it is quite long.
+
+@item -munix=@var{unix-std}
+@opindex march
+Generate compiler predefines and select a startfile for the specified
+UNIX standard.  The choices for @var{unix-std} are @samp{93}, @samp{95}
+and @samp{98}.  @samp{93} is supported on all HP-UX versions.  @samp{95}
+is available on HP-UX 10.10 and later.  @samp{98} is available on HP-UX
+11.11 and later.  The default values are @samp{93} for HP-UX 10.00,
+@samp{95} for HP-UX 10.10 though to 11.00, and @samp{98} for HP-UX 11.11
+and later.
+
+@option{-munix=93} provides the same predefines as GCC 3.3 and 3.4.
+@option{-munix=95} provides additional predefines for @code{XOPEN_UNIX}
+and @code{_XOPEN_SOURCE_EXTENDED}, and the startfile @file{unix95.o}.
+@option{-munix=98} provides additional predefines for @code{_XOPEN_UNIX},
+@code{_XOPEN_SOURCE_EXTENDED}, @code{_INCLUDE__STDC_A1_SOURCE} and
+@code{_INCLUDE_XOPEN_SOURCE_500}, and the startfile @file{unix98.o}.
+
+It is @emph{important} to note that this option changes the interfaces
+for various library routines.  It also affects the operational behavior
+of the C library.  Thus, @emph{extreme} care is needed in using this
+option.
+
+Library code that is intended to operate with more than one UNIX
+standard must test, set and restore the variable @code{__xpg4_extended_mask}
+as appropriate.  Most GNU software doesn't provide this capability.
+
+@item -nolibdld
+@opindex nolibdld
+Suppress the generation of link options to search libdld.sl when the
+@option{-static} option is specified on HP-UX 10 and later.
+
+@item -static
+@opindex static
+The HP-UX implementation of setlocale in libc has a dependency on
+libdld.sl.  There isn't an archive version of libdld.sl.  Thus,
+when the @option{-static} option is specified, special link options
+are needed to resolve this dependency.
+
+On HP-UX 10 and later, the GCC driver adds the necessary options to
+link with libdld.sl when the @option{-static} option is specified.
+This causes the resulting binary to be dynamic.  On the 64-bit port,
+the linkers generate dynamic binaries by default in any case.  The
+@option{-nolibdld} option can be used to prevent the GCC driver from
+adding these link options.
+
+@item -threads
+@opindex threads
+Add support for multithreading with the @dfn{dce thread} library
+under HP-UX@.  This option sets flags for both the preprocessor and
+linker.
+@end table
+
+@node IA-64 Options
+@subsection IA-64 Options
+@cindex IA-64 Options
+
+These are the @samp{-m} options defined for the Intel IA-64 architecture.
+
+@table @gcctabopt
+@item -mbig-endian
+@opindex mbig-endian
+Generate code for a big-endian target.  This is the default for HP-UX@.
+
+@item -mlittle-endian
+@opindex mlittle-endian
+Generate code for a little-endian target.  This is the default for AIX5
+and GNU/Linux.
+
+@item -mgnu-as
+@itemx -mno-gnu-as
+@opindex mgnu-as
+@opindex mno-gnu-as
+Generate (or don't) code for the GNU assembler.  This is the default.
+@c Also, this is the default if the configure option @option{--with-gnu-as}
+@c is used.
+
+@item -mgnu-ld
+@itemx -mno-gnu-ld
+@opindex mgnu-ld
+@opindex mno-gnu-ld
+Generate (or don't) code for the GNU linker.  This is the default.
+@c Also, this is the default if the configure option @option{--with-gnu-ld}
+@c is used.
+
+@item -mno-pic
+@opindex mno-pic
+Generate code that does not use a global pointer register.  The result
+is not position independent code, and violates the IA-64 ABI@.
+
+@item -mvolatile-asm-stop
+@itemx -mno-volatile-asm-stop
+@opindex mvolatile-asm-stop
+@opindex mno-volatile-asm-stop
+Generate (or don't) a stop bit immediately before and after volatile asm
+statements.
+
+@item -mregister-names
+@itemx -mno-register-names
+@opindex mregister-names
+@opindex mno-register-names
+Generate (or don't) @samp{in}, @samp{loc}, and @samp{out} register names for
+the stacked registers.  This may make assembler output more readable.
+
+@item -mno-sdata
+@itemx -msdata
+@opindex mno-sdata
+@opindex msdata
+Disable (or enable) optimizations that use the small data section.  This may
+be useful for working around optimizer bugs.
+
+@item -mconstant-gp
+@opindex mconstant-gp
+Generate code that uses a single constant global pointer value.  This is
+useful when compiling kernel code.
+
+@item -mauto-pic
+@opindex mauto-pic
+Generate code that is self-relocatable.  This implies @option{-mconstant-gp}.
+This is useful when compiling firmware code.
+
+@item -minline-float-divide-min-latency
+@opindex minline-float-divide-min-latency
+Generate code for inline divides of floating-point values
+using the minimum latency algorithm.
+
+@item -minline-float-divide-max-throughput
+@opindex minline-float-divide-max-throughput
+Generate code for inline divides of floating-point values
+using the maximum throughput algorithm.
+
+@item -mno-inline-float-divide
+@opindex mno-inline-float-divide
+Do not generate inline code for divides of floating-point values.
+
+@item -minline-int-divide-min-latency
+@opindex minline-int-divide-min-latency
+Generate code for inline divides of integer values
+using the minimum latency algorithm.
+
+@item -minline-int-divide-max-throughput
+@opindex minline-int-divide-max-throughput
+Generate code for inline divides of integer values
+using the maximum throughput algorithm.
+
+@item -mno-inline-int-divide
+@opindex mno-inline-int-divide
+@opindex minline-int-divide
+Do not generate inline code for divides of integer values.
+
+@item -minline-sqrt-min-latency
+@opindex minline-sqrt-min-latency
+Generate code for inline square roots
+using the minimum latency algorithm.
+
+@item -minline-sqrt-max-throughput
+@opindex minline-sqrt-max-throughput
+Generate code for inline square roots
+using the maximum throughput algorithm.
+
+@item -mno-inline-sqrt
+@opindex mno-inline-sqrt
+Do not generate inline code for @code{sqrt}.
+
+@item -mfused-madd
+@itemx -mno-fused-madd
+@opindex mfused-madd
+@opindex mno-fused-madd
+Do (don't) generate code that uses the fused multiply/add or multiply/subtract
+instructions.  The default is to use these instructions.
+
+@item -mno-dwarf2-asm
+@itemx -mdwarf2-asm
+@opindex mno-dwarf2-asm
+@opindex mdwarf2-asm
+Don't (or do) generate assembler code for the DWARF line number debugging
+info.  This may be useful when not using the GNU assembler.
+
+@item -mearly-stop-bits
+@itemx -mno-early-stop-bits
+@opindex mearly-stop-bits
+@opindex mno-early-stop-bits
+Allow stop bits to be placed earlier than immediately preceding the
+instruction that triggered the stop bit.  This can improve instruction
+scheduling, but does not always do so.
+
+@item -mfixed-range=@var{register-range}
+@opindex mfixed-range
+Generate code treating the given register range as fixed registers.
+A fixed register is one that the register allocator cannot use.  This is
+useful when compiling kernel code.  A register range is specified as
+two registers separated by a dash.  Multiple register ranges can be
+specified separated by a comma.
+
+@item -mtls-size=@var{tls-size}
+@opindex mtls-size
+Specify bit size of immediate TLS offsets.  Valid values are 14, 22, and
+64.
+
+@item -mtune=@var{cpu-type}
+@opindex mtune
+Tune the instruction scheduling for a particular CPU, Valid values are
+@samp{itanium}, @samp{itanium1}, @samp{merced}, @samp{itanium2},
+and @samp{mckinley}.
+
+@item -milp32
+@itemx -mlp64
+@opindex milp32
+@opindex mlp64
+Generate code for a 32-bit or 64-bit environment.
+The 32-bit environment sets int, long and pointer to 32 bits.
+The 64-bit environment sets int to 32 bits and long and pointer
+to 64 bits.  These are HP-UX specific flags.
+
+@item -mno-sched-br-data-spec
+@itemx -msched-br-data-spec
+@opindex mno-sched-br-data-spec
+@opindex msched-br-data-spec
+(Dis/En)able data speculative scheduling before reload.
+This results in generation of @code{ld.a} instructions and
+the corresponding check instructions (@code{ld.c} / @code{chk.a}).
+The default setting is disabled.
+
+@item -msched-ar-data-spec
+@itemx -mno-sched-ar-data-spec
+@opindex msched-ar-data-spec
+@opindex mno-sched-ar-data-spec
+(En/Dis)able data speculative scheduling after reload.
+This results in generation of @code{ld.a} instructions and
+the corresponding check instructions (@code{ld.c} / @code{chk.a}).
+The default setting is enabled.
+
+@item -mno-sched-control-spec
+@itemx -msched-control-spec
+@opindex mno-sched-control-spec
+@opindex msched-control-spec
+(Dis/En)able control speculative scheduling.  This feature is
+available only during region scheduling (i.e.@: before reload).
+This results in generation of the @code{ld.s} instructions and
+the corresponding check instructions @code{chk.s}.
+The default setting is disabled.
+
+@item -msched-br-in-data-spec
+@itemx -mno-sched-br-in-data-spec
+@opindex msched-br-in-data-spec
+@opindex mno-sched-br-in-data-spec
+(En/Dis)able speculative scheduling of the instructions that
+are dependent on the data speculative loads before reload.
+This is effective only with @option{-msched-br-data-spec} enabled.
+The default setting is enabled.
+
+@item -msched-ar-in-data-spec
+@itemx -mno-sched-ar-in-data-spec
+@opindex msched-ar-in-data-spec
+@opindex mno-sched-ar-in-data-spec
+(En/Dis)able speculative scheduling of the instructions that
+are dependent on the data speculative loads after reload.
+This is effective only with @option{-msched-ar-data-spec} enabled.
+The default setting is enabled.
+
+@item -msched-in-control-spec
+@itemx -mno-sched-in-control-spec
+@opindex msched-in-control-spec
+@opindex mno-sched-in-control-spec
+(En/Dis)able speculative scheduling of the instructions that
+are dependent on the control speculative loads.
+This is effective only with @option{-msched-control-spec} enabled.
+The default setting is enabled.
+
+@item -mno-sched-prefer-non-data-spec-insns
+@itemx -msched-prefer-non-data-spec-insns
+@opindex mno-sched-prefer-non-data-spec-insns
+@opindex msched-prefer-non-data-spec-insns
+If enabled, data-speculative instructions are chosen for schedule
+only if there are no other choices at the moment.  This makes
+the use of the data speculation much more conservative.
+The default setting is disabled.
+
+@item -mno-sched-prefer-non-control-spec-insns
+@itemx -msched-prefer-non-control-spec-insns
+@opindex mno-sched-prefer-non-control-spec-insns
+@opindex msched-prefer-non-control-spec-insns
+If enabled, control-speculative instructions are chosen for schedule
+only if there are no other choices at the moment.  This makes
+the use of the control speculation much more conservative.
+The default setting is disabled.
+
+@item -mno-sched-count-spec-in-critical-path
+@itemx -msched-count-spec-in-critical-path
+@opindex mno-sched-count-spec-in-critical-path
+@opindex msched-count-spec-in-critical-path
+If enabled, speculative dependencies are considered during
+computation of the instructions priorities.  This makes the use of the
+speculation a bit more conservative.
+The default setting is disabled.
+
+@item -msched-spec-ldc
+@opindex msched-spec-ldc
+Use a simple data speculation check.  This option is on by default.
+
+@item -msched-control-spec-ldc
+@opindex msched-spec-ldc
+Use a simple check for control speculation.  This option is on by default.
+
+@item -msched-stop-bits-after-every-cycle
+@opindex msched-stop-bits-after-every-cycle
+Place a stop bit after every cycle when scheduling.  This option is on
+by default.
+
+@item -msched-fp-mem-deps-zero-cost
+@opindex msched-fp-mem-deps-zero-cost
+Assume that floating-point stores and loads are not likely to cause a conflict
+when placed into the same instruction group.  This option is disabled by
+default.
+
+@item -msel-sched-dont-check-control-spec
+@opindex msel-sched-dont-check-control-spec
+Generate checks for control speculation in selective scheduling.
+This flag is disabled by default.
+
+@item -msched-max-memory-insns=@var{max-insns}
+@opindex msched-max-memory-insns
+Limit on the number of memory insns per instruction group, giving lower
+priority to subsequent memory insns attempting to schedule in the same
+instruction group. Frequently useful to prevent cache bank conflicts.
+The default value is 1.
+
+@item -msched-max-memory-insns-hard-limit
+@opindex msched-max-memory-insns-hard-limit
+Makes the limit specified by @option{msched-max-memory-insns} a hard limit,
+disallowing more than that number in an instruction group.
+Otherwise, the limit is ``soft'', meaning that non-memory operations
+are preferred when the limit is reached, but memory operations may still
+be scheduled.
+
+@end table
+
+@node LM32 Options
+@subsection LM32 Options
+@cindex LM32 options
+
+These @option{-m} options are defined for the LatticeMico32 architecture:
+
+@table @gcctabopt
+@item -mbarrel-shift-enabled
+@opindex mbarrel-shift-enabled
+Enable barrel-shift instructions.
+
+@item -mdivide-enabled
+@opindex mdivide-enabled
+Enable divide and modulus instructions.
+
+@item -mmultiply-enabled
+@opindex multiply-enabled
+Enable multiply instructions.
+
+@item -msign-extend-enabled
+@opindex msign-extend-enabled
+Enable sign extend instructions.
+
+@item -muser-enabled
+@opindex muser-enabled
+Enable user-defined instructions.
+
+@end table
+
+@node LoongArch Options
+@subsection LoongArch Options
+@cindex LoongArch Options
+
+These command-line options are defined for LoongArch targets:
+
+@table @gcctabopt
+@item -march=@var{cpu-type}
+@opindex -march
+Generate instructions for the machine type @var{cpu-type}.  In contrast to
+@option{-mtune=@var{cpu-type}}, which merely tunes the generated code
+for the specified @var{cpu-type}, @option{-march=@var{cpu-type}} allows GCC
+to generate code that may not run at all on processors other than the one
+indicated.  Specifying @option{-march=@var{cpu-type}} implies
+@option{-mtune=@var{cpu-type}}, except where noted otherwise.
+
+The choices for @var{cpu-type} are:
+
+@table @samp
+@item native
+This selects the CPU to generate code for at compilation time by determining
+the processor type of the compiling machine.  Using @option{-march=native}
+enables all instruction subsets supported by the local machine (hence
+the result might not run on different machines).  Using @option{-mtune=native}
+produces code optimized for the local machine under the constraints
+of the selected instruction set.
+@item loongarch64
+A generic CPU with 64-bit extensions.
+@item la464
+LoongArch LA464 CPU with LBT, LSX, LASX, LVZ.
+@end table
+
+@item -mtune=@var{cpu-type}
+@opindex mtune
+Optimize the output for the given processor, specified by microarchitecture
+name.
+
+@item -mabi=@var{base-abi-type}
+@opindex mabi
+Generate code for the specified calling convention.
+@var{base-abi-type} can be one of:
+@table @samp
+@item lp64d
+Uses 64-bit general purpose registers and 32/64-bit floating-point
+registers for parameter passing.  Data model is LP64, where @samp{int}
+is 32 bits, while @samp{long int} and pointers are 64 bits.
+@item lp64f
+Uses 64-bit general purpose registers and 32-bit floating-point
+registers for parameter passing.  Data model is LP64, where @samp{int}
+is 32 bits, while @samp{long int} and pointers are 64 bits.
+@item lp64s
+Uses 64-bit general purpose registers and no floating-point
+registers for parameter passing.  Data model is LP64, where @samp{int}
+is 32 bits, while @samp{long int} and pointers are 64 bits.
+@end table
+
+@item -mfpu=@var{fpu-type}
+@opindex mfpu
+Generate code for the specified FPU type, which can be one of:
+@table @samp
+@item 64
+Allow the use of hardware floating-point instructions for 32-bit
+and 64-bit operations.
+@item 32
+Allow the use of hardware floating-point instructions for 32-bit
+operations.
+@item none
+@item 0
+Prevent the use of hardware floating-point instructions.
+@end table
+
+@item -msoft-float
+@opindex msoft-float
+Force @option{-mfpu=none} and prevents the use of floating-point
+registers for parameter passing.  This option may change the target
+ABI.
+
+@item -msingle-float
+@opindex -msingle-float
+Force @option{-mfpu=32} and allow the use of 32-bit floating-point
+registers for parameter passing.  This option may change the target
+ABI.
+
+@item -mdouble-float
+@opindex -mdouble-float
+Force @option{-mfpu=64} and allow the use of 32/64-bit floating-point
+registers for parameter passing.  This option may change the target
+ABI.
+
+@item -mbranch-cost=@var{n}
+@opindex -mbranch-cost
+Set the cost of branches to roughly @var{n} instructions.
+
+@item -mcheck-zero-division
+@itemx -mno-check-zero-divison
+@opindex -mcheck-zero-division
+Trap (do not trap) on integer division by zero.  The default is
+@option{-mcheck-zero-division} for @option{-O0} or @option{-Og}, and
+@option{-mno-check-zero-division} for other optimization levels.
+
+@item -mcond-move-int
+@itemx -mno-cond-move-int
+@opindex -mcond-move-int
+Conditional moves for integral data in general-purpose registers
+are enabled (disabled).  The default is @option{-mcond-move-int}.
+
+@item -mcond-move-float
+@itemx -mno-cond-move-float
+@opindex -mcond-move-float
+Conditional moves for floating-point registers are enabled (disabled).
+The default is @option{-mcond-move-float}.
+
+@item -mmemcpy
+@itemx -mno-memcpy
+@opindex -mmemcpy
+Force (do not force) the use of @code{memcpy} for non-trivial block moves.
+The default is @option{-mno-memcpy}, which allows GCC to inline most
+constant-sized copies.  Setting optimization level to @option{-Os} also
+forces the use of @code{memcpy}, but @option{-mno-memcpy} may override this
+behavior if explicitly specified, regardless of the order these options on
+the command line.
+
+@item -mstrict-align
+@itemx -mno-strict-align
+@opindex -mstrict-align
+Avoid or allow generating memory accesses that may not be aligned on a natural
+object boundary as described in the architecture specification. The default is
+@option{-mno-strict-align}.
+
+@item -msmall-data-limit=@var{number}
+@opindex -msmall-data-limit
+Put global and static data smaller than @var{number} bytes into a special
+section (on some targets).  The default value is 0.
+
+@item -mmax-inline-memcpy-size=@var{n}
+@opindex -mmax-inline-memcpy-size
+Inline all block moves (such as calls to @code{memcpy} or structure copies)
+less than or equal to @var{n} bytes.  The default value of @var{n} is 1024.
+
+@item -mcmodel=@var{code-model}
+Set the code model to one of:
+@table @samp
+@item tiny-static (Not implemented yet)
+@item tiny (Not implemented yet)
+
+@item normal
+The text segment must be within 128MB addressing space.  The data segment must
+be within 2GB addressing space.
+
+@item medium
+The text segment and data segment must be within 2GB addressing space.
+
+@item large (Not implemented yet)
+
+@item extreme
+This mode does not limit the size of the code segment and data segment.
+The @option{-mcmodel=extreme} option is incompatible with @option{-fplt} and
+@option{-mno-explicit-relocs}.
+@end table
+The default code model is @code{normal}.
+
+@item -mexplicit-relocs
+@itemx -mno-explicit-relocs
+@opindex mexplicit-relocs
+@opindex mno-explicit-relocs
+Use or do not use assembler relocation operators when dealing with symbolic
+addresses.  The alternative is to use assembler macros instead, which may
+limit optimization.  The default value for the option is determined during
+GCC build-time by detecting corresponding assembler support:
+@code{-mexplicit-relocs} if said support is present,
+@code{-mno-explicit-relocs} otherwise.  This option is mostly useful for
+debugging, or interoperation with assemblers different from the build-time
+one.
+
+@item -mdirect-extern-access
+@itemx -mno-direct-extern-access
+@opindex mdirect-extern-access
+Do not use or use GOT to access external symbols.  The default is
+@option{-mno-direct-extern-access}: GOT is used for external symbols with
+default visibility, but not used for other external symbols.
+
+With @option{-mdirect-extern-access}, GOT is not used and all external
+symbols are PC-relatively addressed.  It is @strong{only} suitable for
+environments where no dynamic link is performed, like firmwares, OS
+kernels, executables linked with @option{-static} or @option{-static-pie}.
+@option{-mdirect-extern-access} is not compatible with @option{-fPIC} or
+@option{-fpic}.
+@end table
+
+@node M32C Options
+@subsection M32C Options
+@cindex M32C options
+
+@table @gcctabopt
+@item -mcpu=@var{name}
+@opindex mcpu=
+Select the CPU for which code is generated.  @var{name} may be one of
+@samp{r8c} for the R8C/Tiny series, @samp{m16c} for the M16C (up to
+/60) series, @samp{m32cm} for the M16C/80 series, or @samp{m32c} for
+the M32C/80 series.
+
+@item -msim
+@opindex msim
+Specifies that the program will be run on the simulator.  This causes
+an alternate runtime library to be linked in which supports, for
+example, file I/O@.  You must not use this option when generating
+programs that will run on real hardware; you must provide your own
+runtime library for whatever I/O functions are needed.
+
+@item -memregs=@var{number}
+@opindex memregs=
+Specifies the number of memory-based pseudo-registers GCC uses
+during code generation.  These pseudo-registers are used like real
+registers, so there is a tradeoff between GCC's ability to fit the
+code into available registers, and the performance penalty of using
+memory instead of registers.  Note that all modules in a program must
+be compiled with the same value for this option.  Because of that, you
+must not use this option with GCC's default runtime libraries.
+
+@end table
+
+@node M32R/D Options
+@subsection M32R/D Options
+@cindex M32R/D options
+
+These @option{-m} options are defined for Renesas M32R/D architectures:
+
+@table @gcctabopt
+@item -m32r2
+@opindex m32r2
+Generate code for the M32R/2@.
+
+@item -m32rx
+@opindex m32rx
+Generate code for the M32R/X@.
+
+@item -m32r
+@opindex m32r
+Generate code for the M32R@.  This is the default.
+
+@item -mmodel=small
+@opindex mmodel=small
+Assume all objects live in the lower 16MB of memory (so that their addresses
+can be loaded with the @code{ld24} instruction), and assume all subroutines
+are reachable with the @code{bl} instruction.
+This is the default.
+
+The addressability of a particular object can be set with the
+@code{model} attribute.
+
+@item -mmodel=medium
+@opindex mmodel=medium
+Assume objects may be anywhere in the 32-bit address space (the compiler
+generates @code{seth/add3} instructions to load their addresses), and
+assume all subroutines are reachable with the @code{bl} instruction.
+
+@item -mmodel=large
+@opindex mmodel=large
+Assume objects may be anywhere in the 32-bit address space (the compiler
+generates @code{seth/add3} instructions to load their addresses), and
+assume subroutines may not be reachable with the @code{bl} instruction
+(the compiler generates the much slower @code{seth/add3/jl}
+instruction sequence).
+
+@item -msdata=none
+@opindex msdata=none
+Disable use of the small data area.  Variables are put into
+one of @code{.data}, @code{.bss}, or @code{.rodata} (unless the
+@code{section} attribute has been specified).
+This is the default.
+
+The small data area consists of sections @code{.sdata} and @code{.sbss}.
+Objects may be explicitly put in the small data area with the
+@code{section} attribute using one of these sections.
+
+@item -msdata=sdata
+@opindex msdata=sdata
+Put small global and static data in the small data area, but do not
+generate special code to reference them.
+
+@item -msdata=use
+@opindex msdata=use
+Put small global and static data in the small data area, and generate
+special instructions to reference them.
+
+@item -G @var{num}
+@opindex G
+@cindex smaller data references
+Put global and static objects less than or equal to @var{num} bytes
+into the small data or BSS sections instead of the normal data or BSS
+sections.  The default value of @var{num} is 8.
+The @option{-msdata} option must be set to one of @samp{sdata} or @samp{use}
+for this option to have any effect.
+
+All modules should be compiled with the same @option{-G @var{num}} value.
+Compiling with different values of @var{num} may or may not work; if it
+doesn't the linker gives an error message---incorrect code is not
+generated.
+
+@item -mdebug
+@opindex mdebug
+Makes the M32R-specific code in the compiler display some statistics
+that might help in debugging programs.
+
+@item -malign-loops
+@opindex malign-loops
+Align all loops to a 32-byte boundary.
+
+@item -mno-align-loops
+@opindex mno-align-loops
+Do not enforce a 32-byte alignment for loops.  This is the default.
+
+@item -missue-rate=@var{number}
+@opindex missue-rate=@var{number}
+Issue @var{number} instructions per cycle.  @var{number} can only be 1
+or 2.
+
+@item -mbranch-cost=@var{number}
+@opindex mbranch-cost=@var{number}
+@var{number} can only be 1 or 2.  If it is 1 then branches are
+preferred over conditional code, if it is 2, then the opposite applies.
+
+@item -mflush-trap=@var{number}
+@opindex mflush-trap=@var{number}
+Specifies the trap number to use to flush the cache.  The default is
+12.  Valid numbers are between 0 and 15 inclusive.
+
+@item -mno-flush-trap
+@opindex mno-flush-trap
+Specifies that the cache cannot be flushed by using a trap.
+
+@item -mflush-func=@var{name}
+@opindex mflush-func=@var{name}
+Specifies the name of the operating system function to call to flush
+the cache.  The default is @samp{_flush_cache}, but a function call
+is only used if a trap is not available.
+
+@item -mno-flush-func
+@opindex mno-flush-func
+Indicates that there is no OS function for flushing the cache.
+
+@end table
+
+@node M680x0 Options
+@subsection M680x0 Options
+@cindex M680x0 options
+
+These are the @samp{-m} options defined for M680x0 and ColdFire processors.
+The default settings depend on which architecture was selected when
+the compiler was configured; the defaults for the most common choices
+are given below.
+
+@table @gcctabopt
+@item -march=@var{arch}
+@opindex march
+Generate code for a specific M680x0 or ColdFire instruction set
+architecture.  Permissible values of @var{arch} for M680x0
+architectures are: @samp{68000}, @samp{68010}, @samp{68020},
+@samp{68030}, @samp{68040}, @samp{68060} and @samp{cpu32}.  ColdFire
+architectures are selected according to Freescale's ISA classification
+and the permissible values are: @samp{isaa}, @samp{isaaplus},
+@samp{isab} and @samp{isac}.
+
+GCC defines a macro @code{__mcf@var{arch}__} whenever it is generating
+code for a ColdFire target.  The @var{arch} in this macro is one of the
+@option{-march} arguments given above.
+
+When used together, @option{-march} and @option{-mtune} select code
+that runs on a family of similar processors but that is optimized
+for a particular microarchitecture.
+
+@item -mcpu=@var{cpu}
+@opindex mcpu
+Generate code for a specific M680x0 or ColdFire processor.
+The M680x0 @var{cpu}s are: @samp{68000}, @samp{68010}, @samp{68020},
+@samp{68030}, @samp{68040}, @samp{68060}, @samp{68302}, @samp{68332}
+and @samp{cpu32}.  The ColdFire @var{cpu}s are given by the table
+below, which also classifies the CPUs into families:
+
+@multitable @columnfractions 0.20 0.80
+@headitem @strong{Family} @tab @strong{@samp{-mcpu} arguments}
+@item @samp{51} @tab @samp{51} @samp{51ac} @samp{51ag} @samp{51cn} @samp{51em} @samp{51je} @samp{51jf} @samp{51jg} @samp{51jm} @samp{51mm} @samp{51qe} @samp{51qm}
+@item @samp{5206} @tab @samp{5202} @samp{5204} @samp{5206}
+@item @samp{5206e} @tab @samp{5206e}
+@item @samp{5208} @tab @samp{5207} @samp{5208}
+@item @samp{5211a} @tab @samp{5210a} @samp{5211a}
+@item @samp{5213} @tab @samp{5211} @samp{5212} @samp{5213}
+@item @samp{5216} @tab @samp{5214} @samp{5216}
+@item @samp{52235} @tab @samp{52230} @samp{52231} @samp{52232} @samp{52233} @samp{52234} @samp{52235}
+@item @samp{5225} @tab @samp{5224} @samp{5225}
+@item @samp{52259} @tab @samp{52252} @samp{52254} @samp{52255} @samp{52256} @samp{52258} @samp{52259}
+@item @samp{5235} @tab @samp{5232} @samp{5233} @samp{5234} @samp{5235} @samp{523x}
+@item @samp{5249} @tab @samp{5249}
+@item @samp{5250} @tab @samp{5250}
+@item @samp{5271} @tab @samp{5270} @samp{5271}
+@item @samp{5272} @tab @samp{5272}
+@item @samp{5275} @tab @samp{5274} @samp{5275}
+@item @samp{5282} @tab @samp{5280} @samp{5281} @samp{5282} @samp{528x}
+@item @samp{53017} @tab @samp{53011} @samp{53012} @samp{53013} @samp{53014} @samp{53015} @samp{53016} @samp{53017}
+@item @samp{5307} @tab @samp{5307}
+@item @samp{5329} @tab @samp{5327} @samp{5328} @samp{5329} @samp{532x}
+@item @samp{5373} @tab @samp{5372} @samp{5373} @samp{537x}
+@item @samp{5407} @tab @samp{5407}
+@item @samp{5475} @tab @samp{5470} @samp{5471} @samp{5472} @samp{5473} @samp{5474} @samp{5475} @samp{547x} @samp{5480} @samp{5481} @samp{5482} @samp{5483} @samp{5484} @samp{5485}
+@end multitable
+
+@option{-mcpu=@var{cpu}} overrides @option{-march=@var{arch}} if
+@var{arch} is compatible with @var{cpu}.  Other combinations of
+@option{-mcpu} and @option{-march} are rejected.
+
+GCC defines the macro @code{__mcf_cpu_@var{cpu}} when ColdFire target
+@var{cpu} is selected.  It also defines @code{__mcf_family_@var{family}},
+where the value of @var{family} is given by the table above.
+
+@item -mtune=@var{tune}
+@opindex mtune
+Tune the code for a particular microarchitecture within the
+constraints set by @option{-march} and @option{-mcpu}.
+The M680x0 microarchitectures are: @samp{68000}, @samp{68010},
+@samp{68020}, @samp{68030}, @samp{68040}, @samp{68060}
+and @samp{cpu32}.  The ColdFire microarchitectures
+are: @samp{cfv1}, @samp{cfv2}, @samp{cfv3}, @samp{cfv4} and @samp{cfv4e}.
+
+You can also use @option{-mtune=68020-40} for code that needs
+to run relatively well on 68020, 68030 and 68040 targets.
+@option{-mtune=68020-60} is similar but includes 68060 targets
+as well.  These two options select the same tuning decisions as
+@option{-m68020-40} and @option{-m68020-60} respectively.
+
+GCC defines the macros @code{__mc@var{arch}} and @code{__mc@var{arch}__}
+when tuning for 680x0 architecture @var{arch}.  It also defines
+@code{mc@var{arch}} unless either @option{-ansi} or a non-GNU @option{-std}
+option is used.  If GCC is tuning for a range of architectures,
+as selected by @option{-mtune=68020-40} or @option{-mtune=68020-60},
+it defines the macros for every architecture in the range.
+
+GCC also defines the macro @code{__m@var{uarch}__} when tuning for
+ColdFire microarchitecture @var{uarch}, where @var{uarch} is one
+of the arguments given above.
+
+@item -m68000
+@itemx -mc68000
+@opindex m68000
+@opindex mc68000
+Generate output for a 68000.  This is the default
+when the compiler is configured for 68000-based systems.
+It is equivalent to @option{-march=68000}.
+
+Use this option for microcontrollers with a 68000 or EC000 core,
+including the 68008, 68302, 68306, 68307, 68322, 68328 and 68356.
+
+@item -m68010
+@opindex m68010
+Generate output for a 68010.  This is the default
+when the compiler is configured for 68010-based systems.
+It is equivalent to @option{-march=68010}.
+
+@item -m68020
+@itemx -mc68020
+@opindex m68020
+@opindex mc68020
+Generate output for a 68020.  This is the default
+when the compiler is configured for 68020-based systems.
+It is equivalent to @option{-march=68020}.
+
+@item -m68030
+@opindex m68030
+Generate output for a 68030.  This is the default when the compiler is
+configured for 68030-based systems.  It is equivalent to
+@option{-march=68030}.
+
+@item -m68040
+@opindex m68040
+Generate output for a 68040.  This is the default when the compiler is
+configured for 68040-based systems.  It is equivalent to
+@option{-march=68040}.
+
+This option inhibits the use of 68881/68882 instructions that have to be
+emulated by software on the 68040.  Use this option if your 68040 does not
+have code to emulate those instructions.
+
+@item -m68060
+@opindex m68060
+Generate output for a 68060.  This is the default when the compiler is
+configured for 68060-based systems.  It is equivalent to
+@option{-march=68060}.
+
+This option inhibits the use of 68020 and 68881/68882 instructions that
+have to be emulated by software on the 68060.  Use this option if your 68060
+does not have code to emulate those instructions.
+
+@item -mcpu32
+@opindex mcpu32
+Generate output for a CPU32.  This is the default
+when the compiler is configured for CPU32-based systems.
+It is equivalent to @option{-march=cpu32}.
+
+Use this option for microcontrollers with a
+CPU32 or CPU32+ core, including the 68330, 68331, 68332, 68333, 68334,
+68336, 68340, 68341, 68349 and 68360.
+
+@item -m5200
+@opindex m5200
+Generate output for a 520X ColdFire CPU@.  This is the default
+when the compiler is configured for 520X-based systems.
+It is equivalent to @option{-mcpu=5206}, and is now deprecated
+in favor of that option.
+
+Use this option for microcontroller with a 5200 core, including
+the MCF5202, MCF5203, MCF5204 and MCF5206.
+
+@item -m5206e
+@opindex m5206e
+Generate output for a 5206e ColdFire CPU@.  The option is now
+deprecated in favor of the equivalent @option{-mcpu=5206e}.
+
+@item -m528x
+@opindex m528x
+Generate output for a member of the ColdFire 528X family.
+The option is now deprecated in favor of the equivalent
+@option{-mcpu=528x}.
+
+@item -m5307
+@opindex m5307
+Generate output for a ColdFire 5307 CPU@.  The option is now deprecated
+in favor of the equivalent @option{-mcpu=5307}.
+
+@item -m5407
+@opindex m5407
+Generate output for a ColdFire 5407 CPU@.  The option is now deprecated
+in favor of the equivalent @option{-mcpu=5407}.
+
+@item -mcfv4e
+@opindex mcfv4e
+Generate output for a ColdFire V4e family CPU (e.g.@: 547x/548x).
+This includes use of hardware floating-point instructions.
+The option is equivalent to @option{-mcpu=547x}, and is now
+deprecated in favor of that option.
+
+@item -m68020-40
+@opindex m68020-40
+Generate output for a 68040, without using any of the new instructions.
+This results in code that can run relatively efficiently on either a
+68020/68881 or a 68030 or a 68040.  The generated code does use the
+68881 instructions that are emulated on the 68040.
+
+The option is equivalent to @option{-march=68020} @option{-mtune=68020-40}.
+
+@item -m68020-60
+@opindex m68020-60
+Generate output for a 68060, without using any of the new instructions.
+This results in code that can run relatively efficiently on either a
+68020/68881 or a 68030 or a 68040.  The generated code does use the
+68881 instructions that are emulated on the 68060.
+
+The option is equivalent to @option{-march=68020} @option{-mtune=68020-60}.
+
+@item -mhard-float
+@itemx -m68881
+@opindex mhard-float
+@opindex m68881
+Generate floating-point instructions.  This is the default for 68020
+and above, and for ColdFire devices that have an FPU@.  It defines the
+macro @code{__HAVE_68881__} on M680x0 targets and @code{__mcffpu__}
+on ColdFire targets.
+
+@item -msoft-float
+@opindex msoft-float
+Do not generate floating-point instructions; use library calls instead.
+This is the default for 68000, 68010, and 68832 targets.  It is also
+the default for ColdFire devices that have no FPU.
+
+@item -mdiv
+@itemx -mno-div
+@opindex mdiv
+@opindex mno-div
+Generate (do not generate) ColdFire hardware divide and remainder
+instructions.  If @option{-march} is used without @option{-mcpu},
+the default is ``on'' for ColdFire architectures and ``off'' for M680x0
+architectures.  Otherwise, the default is taken from the target CPU
+(either the default CPU, or the one specified by @option{-mcpu}).  For
+example, the default is ``off'' for @option{-mcpu=5206} and ``on'' for
+@option{-mcpu=5206e}.
+
+GCC defines the macro @code{__mcfhwdiv__} when this option is enabled.
+
+@item -mshort
+@opindex mshort
+Consider type @code{int} to be 16 bits wide, like @code{short int}.
+Additionally, parameters passed on the stack are also aligned to a
+16-bit boundary even on targets whose API mandates promotion to 32-bit.
+
+@item -mno-short
+@opindex mno-short
+Do not consider type @code{int} to be 16 bits wide.  This is the default.
+
+@item -mnobitfield
+@itemx -mno-bitfield
+@opindex mnobitfield
+@opindex mno-bitfield
+Do not use the bit-field instructions.  The @option{-m68000}, @option{-mcpu32}
+and @option{-m5200} options imply @w{@option{-mnobitfield}}.
+
+@item -mbitfield
+@opindex mbitfield
+Do use the bit-field instructions.  The @option{-m68020} option implies
+@option{-mbitfield}.  This is the default if you use a configuration
+designed for a 68020.
+
+@item -mrtd
+@opindex mrtd
+Use a different function-calling convention, in which functions
+that take a fixed number of arguments return with the @code{rtd}
+instruction, which pops their arguments while returning.  This
+saves one instruction in the caller since there is no need to pop
+the arguments there.
+
+This calling convention is incompatible with the one normally
+used on Unix, so you cannot use it if you need to call libraries
+compiled with the Unix compiler.
+
+Also, you must provide function prototypes for all functions that
+take variable numbers of arguments (including @code{printf});
+otherwise incorrect code is generated for calls to those
+functions.
+
+In addition, seriously incorrect code results if you call a
+function with too many arguments.  (Normally, extra arguments are
+harmlessly ignored.)
+
+The @code{rtd} instruction is supported by the 68010, 68020, 68030,
+68040, 68060 and CPU32 processors, but not by the 68000 or 5200.
+
+The default is @option{-mno-rtd}.
+
+@item -malign-int
+@itemx -mno-align-int
+@opindex malign-int
+@opindex mno-align-int
+Control whether GCC aligns @code{int}, @code{long}, @code{long long},
+@code{float}, @code{double}, and @code{long double} variables on a 32-bit
+boundary (@option{-malign-int}) or a 16-bit boundary (@option{-mno-align-int}).
+Aligning variables on 32-bit boundaries produces code that runs somewhat
+faster on processors with 32-bit busses at the expense of more memory.
+
+@strong{Warning:} if you use the @option{-malign-int} switch, GCC
+aligns structures containing the above types differently than
+most published application binary interface specifications for the m68k.
+
+@opindex mpcrel
+Use the pc-relative addressing mode of the 68000 directly, instead of
+using a global offset table.  At present, this option implies @option{-fpic},
+allowing at most a 16-bit offset for pc-relative addressing.  @option{-fPIC} is
+not presently supported with @option{-mpcrel}, though this could be supported for
+68020 and higher processors.
+
+@item -mno-strict-align
+@itemx -mstrict-align
+@opindex mno-strict-align
+@opindex mstrict-align
+Do not (do) assume that unaligned memory references are handled by
+the system.
+
+@item -msep-data
+Generate code that allows the data segment to be located in a different
+area of memory from the text segment.  This allows for execute-in-place in
+an environment without virtual memory management.  This option implies
+@option{-fPIC}.
+
+@item -mno-sep-data
+Generate code that assumes that the data segment follows the text segment.
+This is the default.
+
+@item -mid-shared-library
+Generate code that supports shared libraries via the library ID method.
+This allows for execute-in-place and shared libraries in an environment
+without virtual memory management.  This option implies @option{-fPIC}.
+
+@item -mno-id-shared-library
+Generate code that doesn't assume ID-based shared libraries are being used.
+This is the default.
+
+@item -mshared-library-id=n
+Specifies the identification number of the ID-based shared library being
+compiled.  Specifying a value of 0 generates more compact code; specifying
+other values forces the allocation of that number to the current
+library, but is no more space- or time-efficient than omitting this option.
+
+@item -mxgot
+@itemx -mno-xgot
+@opindex mxgot
+@opindex mno-xgot
+When generating position-independent code for ColdFire, generate code
+that works if the GOT has more than 8192 entries.  This code is
+larger and slower than code generated without this option.  On M680x0
+processors, this option is not needed; @option{-fPIC} suffices.
+
+GCC normally uses a single instruction to load values from the GOT@.
+While this is relatively efficient, it only works if the GOT
+is smaller than about 64k.  Anything larger causes the linker
+to report an error such as:
+
+@cindex relocation truncated to fit (ColdFire)
+@smallexample
+relocation truncated to fit: R_68K_GOT16O foobar
+@end smallexample
+
+If this happens, you should recompile your code with @option{-mxgot}.
+It should then work with very large GOTs.  However, code generated with
+@option{-mxgot} is less efficient, since it takes 4 instructions to fetch
+the value of a global symbol.
+
+Note that some linkers, including newer versions of the GNU linker,
+can create multiple GOTs and sort GOT entries.  If you have such a linker,
+you should only need to use @option{-mxgot} when compiling a single
+object file that accesses more than 8192 GOT entries.  Very few do.
+
+These options have no effect unless GCC is generating
+position-independent code.
+
+@item -mlong-jump-table-offsets
+@opindex mlong-jump-table-offsets
+Use 32-bit offsets in @code{switch} tables.  The default is to use
+16-bit offsets.
+
+@end table
+
+@node MCore Options
+@subsection MCore Options
+@cindex MCore options
+
+These are the @samp{-m} options defined for the Motorola M*Core
+processors.
+
+@table @gcctabopt
+
+@item -mhardlit
+@itemx -mno-hardlit
+@opindex mhardlit
+@opindex mno-hardlit
+Inline constants into the code stream if it can be done in two
+instructions or less.
+
+@item -mdiv
+@itemx -mno-div
+@opindex mdiv
+@opindex mno-div
+Use the divide instruction.  (Enabled by default).
+
+@item -mrelax-immediate
+@itemx -mno-relax-immediate
+@opindex mrelax-immediate
+@opindex mno-relax-immediate
+Allow arbitrary-sized immediates in bit operations.
+
+@item -mwide-bitfields
+@itemx -mno-wide-bitfields
+@opindex mwide-bitfields
+@opindex mno-wide-bitfields
+Always treat bit-fields as @code{int}-sized.
+
+@item -m4byte-functions
+@itemx -mno-4byte-functions
+@opindex m4byte-functions
+@opindex mno-4byte-functions
+Force all functions to be aligned to a 4-byte boundary.
+
+@item -mcallgraph-data
+@itemx -mno-callgraph-data
+@opindex mcallgraph-data
+@opindex mno-callgraph-data
+Emit callgraph information.
+
+@item -mslow-bytes
+@itemx -mno-slow-bytes
+@opindex mslow-bytes
+@opindex mno-slow-bytes
+Prefer word access when reading byte quantities.
+
+@item -mlittle-endian
+@itemx -mbig-endian
+@opindex mlittle-endian
+@opindex mbig-endian
+Generate code for a little-endian target.
+
+@item -m210
+@itemx -m340
+@opindex m210
+@opindex m340
+Generate code for the 210 processor.
+
+@item -mno-lsim
+@opindex mno-lsim
+Assume that runtime support has been provided and so omit the
+simulator library (@file{libsim.a)} from the linker command line.
+
+@item -mstack-increment=@var{size}
+@opindex mstack-increment
+Set the maximum amount for a single stack increment operation.  Large
+values can increase the speed of programs that contain functions
+that need a large amount of stack space, but they can also trigger a
+segmentation fault if the stack is extended too much.  The default
+value is 0x1000.
+
+@end table
+
+@node MeP Options
+@subsection MeP Options
+@cindex MeP options
+
+@table @gcctabopt
+
+@item -mabsdiff
+@opindex mabsdiff
+Enables the @code{abs} instruction, which is the absolute difference
+between two registers.
+
+@item -mall-opts
+@opindex mall-opts
+Enables all the optional instructions---average, multiply, divide, bit
+operations, leading zero, absolute difference, min/max, clip, and
+saturation.
+
+
+@item -maverage
+@opindex maverage
+Enables the @code{ave} instruction, which computes the average of two
+registers.
+
+@item -mbased=@var{n}
+@opindex mbased=
+Variables of size @var{n} bytes or smaller are placed in the
+@code{.based} section by default.  Based variables use the @code{$tp}
+register as a base register, and there is a 128-byte limit to the
+@code{.based} section.
+
+@item -mbitops
+@opindex mbitops
+Enables the bit operation instructions---bit test (@code{btstm}), set
+(@code{bsetm}), clear (@code{bclrm}), invert (@code{bnotm}), and
+test-and-set (@code{tas}).
+
+@item -mc=@var{name}
+@opindex mc=
+Selects which section constant data is placed in.  @var{name} may
+be @samp{tiny}, @samp{near}, or @samp{far}.
+
+@item -mclip
+@opindex mclip
+Enables the @code{clip} instruction.  Note that @option{-mclip} is not
+useful unless you also provide @option{-mminmax}.
+
+@item -mconfig=@var{name}
+@opindex mconfig=
+Selects one of the built-in core configurations.  Each MeP chip has
+one or more modules in it; each module has a core CPU and a variety of
+coprocessors, optional instructions, and peripherals.  The
+@code{MeP-Integrator} tool, not part of GCC, provides these
+configurations through this option; using this option is the same as
+using all the corresponding command-line options.  The default
+configuration is @samp{default}.
+
+@item -mcop
+@opindex mcop
+Enables the coprocessor instructions.  By default, this is a 32-bit
+coprocessor.  Note that the coprocessor is normally enabled via the
+@option{-mconfig=} option.
+
+@item -mcop32
+@opindex mcop32
+Enables the 32-bit coprocessor's instructions.
+
+@item -mcop64
+@opindex mcop64
+Enables the 64-bit coprocessor's instructions.
+
+@item -mivc2
+@opindex mivc2
+Enables IVC2 scheduling.  IVC2 is a 64-bit VLIW coprocessor.
+
+@item -mdc
+@opindex mdc
+Causes constant variables to be placed in the @code{.near} section.
+
+@item -mdiv
+@opindex mdiv
+Enables the @code{div} and @code{divu} instructions.
+
+@item -meb
+@opindex meb
+Generate big-endian code.
+
+@item -mel
+@opindex mel
+Generate little-endian code.
+
+@item -mio-volatile
+@opindex mio-volatile
+Tells the compiler that any variable marked with the @code{io}
+attribute is to be considered volatile.
+
+@item -ml
+@opindex ml
+Causes variables to be assigned to the @code{.far} section by default.
+
+@item -mleadz
+@opindex mleadz
+Enables the @code{leadz} (leading zero) instruction.
+
+@item -mm
+@opindex mm
+Causes variables to be assigned to the @code{.near} section by default.
+
+@item -mminmax
+@opindex mminmax
+Enables the @code{min} and @code{max} instructions.
+
+@item -mmult
+@opindex mmult
+Enables the multiplication and multiply-accumulate instructions.
+
+@item -mno-opts
+@opindex mno-opts
+Disables all the optional instructions enabled by @option{-mall-opts}.
+
+@item -mrepeat
+@opindex mrepeat
+Enables the @code{repeat} and @code{erepeat} instructions, used for
+low-overhead looping.
+
+@item -ms
+@opindex ms
+Causes all variables to default to the @code{.tiny} section.  Note
+that there is a 65536-byte limit to this section.  Accesses to these
+variables use the @code{%gp} base register.
+
+@item -msatur
+@opindex msatur
+Enables the saturation instructions.  Note that the compiler does not
+currently generate these itself, but this option is included for
+compatibility with other tools, like @code{as}.
+
+@item -msdram
+@opindex msdram
+Link the SDRAM-based runtime instead of the default ROM-based runtime.
+
+@item -msim
+@opindex msim
+Link the simulator run-time libraries.
+
+@item -msimnovec
+@opindex msimnovec
+Link the simulator runtime libraries, excluding built-in support
+for reset and exception vectors and tables.
+
+@item -mtf
+@opindex mtf
+Causes all functions to default to the @code{.far} section.  Without
+this option, functions default to the @code{.near} section.
+
+@item -mtiny=@var{n}
+@opindex mtiny=
+Variables that are @var{n} bytes or smaller are allocated to the
+@code{.tiny} section.  These variables use the @code{$gp} base
+register.  The default for this option is 4, but note that there's a
+65536-byte limit to the @code{.tiny} section.
+
+@end table
+
+@node MicroBlaze Options
+@subsection MicroBlaze Options
+@cindex MicroBlaze Options
+
+@table @gcctabopt
+
+@item -msoft-float
+@opindex msoft-float
+Use software emulation for floating point (default).
+
+@item -mhard-float
+@opindex mhard-float
+Use hardware floating-point instructions.
+
+@item -mmemcpy
+@opindex mmemcpy
+Do not optimize block moves, use @code{memcpy}.
+
+@item -mno-clearbss
+@opindex mno-clearbss
+This option is deprecated.  Use @option{-fno-zero-initialized-in-bss} instead.
+
+@item -mcpu=@var{cpu-type}
+@opindex mcpu=
+Use features of, and schedule code for, the given CPU.
+Supported values are in the format @samp{v@var{X}.@var{YY}.@var{Z}},
+where @var{X} is a major version, @var{YY} is the minor version, and
+@var{Z} is compatibility code.  Example values are @samp{v3.00.a},
+@samp{v4.00.b}, @samp{v5.00.a}, @samp{v5.00.b}, @samp{v6.00.a}.
+
+@item -mxl-soft-mul
+@opindex mxl-soft-mul
+Use software multiply emulation (default).
+
+@item -mxl-soft-div
+@opindex mxl-soft-div
+Use software emulation for divides (default).
+
+@item -mxl-barrel-shift
+@opindex mxl-barrel-shift
+Use the hardware barrel shifter.
+
+@item -mxl-pattern-compare
+@opindex mxl-pattern-compare
+Use pattern compare instructions.
+
+@item -msmall-divides
+@opindex msmall-divides
+Use table lookup optimization for small signed integer divisions.
+
+@item -mxl-stack-check
+@opindex mxl-stack-check
+This option is deprecated.  Use @option{-fstack-check} instead.
+
+@item -mxl-gp-opt
+@opindex mxl-gp-opt
+Use GP-relative @code{.sdata}/@code{.sbss} sections.
+
+@item -mxl-multiply-high
+@opindex mxl-multiply-high
+Use multiply high instructions for high part of 32x32 multiply.
+
+@item -mxl-float-convert
+@opindex mxl-float-convert
+Use hardware floating-point conversion instructions.
+
+@item -mxl-float-sqrt
+@opindex mxl-float-sqrt
+Use hardware floating-point square root instruction.
+
+@item -mbig-endian
+@opindex mbig-endian
+Generate code for a big-endian target.
+
+@item -mlittle-endian
+@opindex mlittle-endian
+Generate code for a little-endian target.
+
+@item -mxl-reorder
+@opindex mxl-reorder
+Use reorder instructions (swap and byte reversed load/store).
+
+@item -mxl-mode-@var{app-model}
+Select application model @var{app-model}.  Valid models are
+@table @samp
+@item executable
+normal executable (default), uses startup code @file{crt0.o}.
+
+@item xmdstub
+for use with Xilinx Microprocessor Debugger (XMD) based
+software intrusive debug agent called xmdstub. This uses startup file
+@file{crt1.o} and sets the start address of the program to 0x800.
+
+@item bootstrap
+for applications that are loaded using a bootloader.
+This model uses startup file @file{crt2.o} which does not contain a processor
+reset vector handler. This is suitable for transferring control on a
+processor reset to the bootloader rather than the application.
+
+@item novectors
+for applications that do not require any of the
+MicroBlaze vectors. This option may be useful for applications running
+within a monitoring application. This model uses @file{crt3.o} as a startup file.
+@end table
+
+Option @option{-xl-mode-@var{app-model}} is a deprecated alias for
+@option{-mxl-mode-@var{app-model}}.
+
+@item -mpic-data-is-text-relative
+@opindex mpic-data-is-text-relative
+Assume that the displacement between the text and data segments is fixed
+at static link time.  This allows data to be referenced by offset from start of
+text address instead of GOT since PC-relative addressing is not supported.
+
+@end table
+
+@node MIPS Options
+@subsection MIPS Options
+@cindex MIPS options
+
+@table @gcctabopt
+
+@item -EB
+@opindex EB
+Generate big-endian code.
+
+@item -EL
+@opindex EL
+Generate little-endian code.  This is the default for @samp{mips*el-*-*}
+configurations.
+
+@item -march=@var{arch}
+@opindex march
+Generate code that runs on @var{arch}, which can be the name of a
+generic MIPS ISA, or the name of a particular processor.
+The ISA names are:
+@samp{mips1}, @samp{mips2}, @samp{mips3}, @samp{mips4},
+@samp{mips32}, @samp{mips32r2}, @samp{mips32r3}, @samp{mips32r5},
+@samp{mips32r6}, @samp{mips64}, @samp{mips64r2}, @samp{mips64r3},
+@samp{mips64r5} and @samp{mips64r6}.
+The processor names are:
+@samp{4kc}, @samp{4km}, @samp{4kp}, @samp{4ksc},
+@samp{4kec}, @samp{4kem}, @samp{4kep}, @samp{4ksd},
+@samp{5kc}, @samp{5kf},
+@samp{20kc},
+@samp{24kc}, @samp{24kf2_1}, @samp{24kf1_1},
+@samp{24kec}, @samp{24kef2_1}, @samp{24kef1_1},
+@samp{34kc}, @samp{34kf2_1}, @samp{34kf1_1}, @samp{34kn},
+@samp{74kc}, @samp{74kf2_1}, @samp{74kf1_1}, @samp{74kf3_2},
+@samp{1004kc}, @samp{1004kf2_1}, @samp{1004kf1_1},
+@samp{i6400}, @samp{i6500},
+@samp{interaptiv},
+@samp{loongson2e}, @samp{loongson2f}, @samp{loongson3a}, @samp{gs464},
+@samp{gs464e}, @samp{gs264e},
+@samp{m4k},
+@samp{m14k}, @samp{m14kc}, @samp{m14ke}, @samp{m14kec},
+@samp{m5100}, @samp{m5101},
+@samp{octeon}, @samp{octeon+}, @samp{octeon2}, @samp{octeon3},
+@samp{orion},
+@samp{p5600}, @samp{p6600},
+@samp{r2000}, @samp{r3000}, @samp{r3900}, @samp{r4000}, @samp{r4400},
+@samp{r4600}, @samp{r4650}, @samp{r4700}, @samp{r5900},
+@samp{r6000}, @samp{r8000},
+@samp{rm7000}, @samp{rm9000},
+@samp{r10000}, @samp{r12000}, @samp{r14000}, @samp{r16000},
+@samp{sb1},
+@samp{sr71000},
+@samp{vr4100}, @samp{vr4111}, @samp{vr4120}, @samp{vr4130}, @samp{vr4300},
+@samp{vr5000}, @samp{vr5400}, @samp{vr5500},
+@samp{xlr} and @samp{xlp}.
+The special value @samp{from-abi} selects the
+most compatible architecture for the selected ABI (that is,
+@samp{mips1} for 32-bit ABIs and @samp{mips3} for 64-bit ABIs)@.
+
+The native Linux/GNU toolchain also supports the value @samp{native},
+which selects the best architecture option for the host processor.
+@option{-march=native} has no effect if GCC does not recognize
+the processor.
+
+In processor names, a final @samp{000} can be abbreviated as @samp{k}
+(for example, @option{-march=r2k}).  Prefixes are optional, and
+@samp{vr} may be written @samp{r}.
+
+Names of the form @samp{@var{n}f2_1} refer to processors with
+FPUs clocked at half the rate of the core, names of the form
+@samp{@var{n}f1_1} refer to processors with FPUs clocked at the same
+rate as the core, and names of the form @samp{@var{n}f3_2} refer to
+processors with FPUs clocked a ratio of 3:2 with respect to the core.
+For compatibility reasons, @samp{@var{n}f} is accepted as a synonym
+for @samp{@var{n}f2_1} while @samp{@var{n}x} and @samp{@var{b}fx} are
+accepted as synonyms for @samp{@var{n}f1_1}.
+
+GCC defines two macros based on the value of this option.  The first
+is @code{_MIPS_ARCH}, which gives the name of target architecture, as
+a string.  The second has the form @code{_MIPS_ARCH_@var{foo}},
+where @var{foo} is the capitalized value of @code{_MIPS_ARCH}@.
+For example, @option{-march=r2000} sets @code{_MIPS_ARCH}
+to @code{"r2000"} and defines the macro @code{_MIPS_ARCH_R2000}.
+
+Note that the @code{_MIPS_ARCH} macro uses the processor names given
+above.  In other words, it has the full prefix and does not
+abbreviate @samp{000} as @samp{k}.  In the case of @samp{from-abi},
+the macro names the resolved architecture (either @code{"mips1"} or
+@code{"mips3"}).  It names the default architecture when no
+@option{-march} option is given.
+
+@item -mtune=@var{arch}
+@opindex mtune
+Optimize for @var{arch}.  Among other things, this option controls
+the way instructions are scheduled, and the perceived cost of arithmetic
+operations.  The list of @var{arch} values is the same as for
+@option{-march}.
+
+When this option is not used, GCC optimizes for the processor
+specified by @option{-march}.  By using @option{-march} and
+@option{-mtune} together, it is possible to generate code that
+runs on a family of processors, but optimize the code for one
+particular member of that family.
+
+@option{-mtune} defines the macros @code{_MIPS_TUNE} and
+@code{_MIPS_TUNE_@var{foo}}, which work in the same way as the
+@option{-march} ones described above.
+
+@item -mips1
+@opindex mips1
+Equivalent to @option{-march=mips1}.
+
+@item -mips2
+@opindex mips2
+Equivalent to @option{-march=mips2}.
+
+@item -mips3
+@opindex mips3
+Equivalent to @option{-march=mips3}.
+
+@item -mips4
+@opindex mips4
+Equivalent to @option{-march=mips4}.
+
+@item -mips32
+@opindex mips32
+Equivalent to @option{-march=mips32}.
+
+@item -mips32r3
+@opindex mips32r3
+Equivalent to @option{-march=mips32r3}.
+
+@item -mips32r5
+@opindex mips32r5
+Equivalent to @option{-march=mips32r5}.
+
+@item -mips32r6
+@opindex mips32r6
+Equivalent to @option{-march=mips32r6}.
+
+@item -mips64
+@opindex mips64
+Equivalent to @option{-march=mips64}.
+
+@item -mips64r2
+@opindex mips64r2
+Equivalent to @option{-march=mips64r2}.
+
+@item -mips64r3
+@opindex mips64r3
+Equivalent to @option{-march=mips64r3}.
+
+@item -mips64r5
+@opindex mips64r5
+Equivalent to @option{-march=mips64r5}.
+
+@item -mips64r6
+@opindex mips64r6
+Equivalent to @option{-march=mips64r6}.
+
+@item -mips16
+@itemx -mno-mips16
+@opindex mips16
+@opindex mno-mips16
+Generate (do not generate) MIPS16 code.  If GCC is targeting a
+MIPS32 or MIPS64 architecture, it makes use of the MIPS16e ASE@.
+
+MIPS16 code generation can also be controlled on a per-function basis
+by means of @code{mips16} and @code{nomips16} attributes.
+@xref{Function Attributes}, for more information.
+
+@item -mflip-mips16
+@opindex mflip-mips16
+Generate MIPS16 code on alternating functions.  This option is provided
+for regression testing of mixed MIPS16/non-MIPS16 code generation, and is
+not intended for ordinary use in compiling user code.
+
+@item -minterlink-compressed
+@itemx -mno-interlink-compressed
+@opindex minterlink-compressed
+@opindex mno-interlink-compressed
+Require (do not require) that code using the standard (uncompressed) MIPS ISA
+be link-compatible with MIPS16 and microMIPS code, and vice versa.
+
+For example, code using the standard ISA encoding cannot jump directly
+to MIPS16 or microMIPS code; it must either use a call or an indirect jump.
+@option{-minterlink-compressed} therefore disables direct jumps unless GCC
+knows that the target of the jump is not compressed.
+
+@item -minterlink-mips16
+@itemx -mno-interlink-mips16
+@opindex minterlink-mips16
+@opindex mno-interlink-mips16
+Aliases of @option{-minterlink-compressed} and
+@option{-mno-interlink-compressed}.  These options predate the microMIPS ASE
+and are retained for backwards compatibility.
+
+@item -mabi=32
+@itemx -mabi=o64
+@itemx -mabi=n32
+@itemx -mabi=64
+@itemx -mabi=eabi
+@opindex mabi=32
+@opindex mabi=o64
+@opindex mabi=n32
+@opindex mabi=64
+@opindex mabi=eabi
+Generate code for the given ABI@.
+
+Note that the EABI has a 32-bit and a 64-bit variant.  GCC normally
+generates 64-bit code when you select a 64-bit architecture, but you
+can use @option{-mgp32} to get 32-bit code instead.
+
+For information about the O64 ABI, see
+@uref{https://gcc.gnu.org/@/projects/@/mipso64-abi.html}.
+
+GCC supports a variant of the o32 ABI in which floating-point registers
+are 64 rather than 32 bits wide.  You can select this combination with
+@option{-mabi=32} @option{-mfp64}.  This ABI relies on the @code{mthc1}
+and @code{mfhc1} instructions and is therefore only supported for
+MIPS32R2, MIPS32R3 and MIPS32R5 processors.
+
+The register assignments for arguments and return values remain the
+same, but each scalar value is passed in a single 64-bit register
+rather than a pair of 32-bit registers.  For example, scalar
+floating-point values are returned in @samp{$f0} only, not a
+@samp{$f0}/@samp{$f1} pair.  The set of call-saved registers also
+remains the same in that the even-numbered double-precision registers
+are saved.
+
+Two additional variants of the o32 ABI are supported to enable
+a transition from 32-bit to 64-bit registers.  These are FPXX
+(@option{-mfpxx}) and FP64A (@option{-mfp64} @option{-mno-odd-spreg}).
+The FPXX extension mandates that all code must execute correctly
+when run using 32-bit or 64-bit registers.  The code can be interlinked
+with either FP32 or FP64, but not both.
+The FP64A extension is similar to the FP64 extension but forbids the
+use of odd-numbered single-precision registers.  This can be used
+in conjunction with the @code{FRE} mode of FPUs in MIPS32R5
+processors and allows both FP32 and FP64A code to interlink and
+run in the same process without changing FPU modes.
+
+@item -mabicalls
+@itemx -mno-abicalls
+@opindex mabicalls
+@opindex mno-abicalls
+Generate (do not generate) code that is suitable for SVR4-style
+dynamic objects.  @option{-mabicalls} is the default for SVR4-based
+systems.
+
+@item -mshared
+@itemx -mno-shared
+Generate (do not generate) code that is fully position-independent,
+and that can therefore be linked into shared libraries.  This option
+only affects @option{-mabicalls}.
+
+All @option{-mabicalls} code has traditionally been position-independent,
+regardless of options like @option{-fPIC} and @option{-fpic}.  However,
+as an extension, the GNU toolchain allows executables to use absolute
+accesses for locally-binding symbols.  It can also use shorter GP
+initialization sequences and generate direct calls to locally-defined
+functions.  This mode is selected by @option{-mno-shared}.
+
+@option{-mno-shared} depends on binutils 2.16 or higher and generates
+objects that can only be linked by the GNU linker.  However, the option
+does not affect the ABI of the final executable; it only affects the ABI
+of relocatable objects.  Using @option{-mno-shared} generally makes
+executables both smaller and quicker.
+
+@option{-mshared} is the default.
+
+@item -mplt
+@itemx -mno-plt
+@opindex mplt
+@opindex mno-plt
+Assume (do not assume) that the static and dynamic linkers
+support PLTs and copy relocations.  This option only affects
+@option{-mno-shared -mabicalls}.  For the n64 ABI, this option
+has no effect without @option{-msym32}.
+
+You can make @option{-mplt} the default by configuring
+GCC with @option{--with-mips-plt}.  The default is
+@option{-mno-plt} otherwise.
+
+@item -mxgot
+@itemx -mno-xgot
+@opindex mxgot
+@opindex mno-xgot
+Lift (do not lift) the usual restrictions on the size of the global
+offset table.
+
+GCC normally uses a single instruction to load values from the GOT@.
+While this is relatively efficient, it only works if the GOT
+is smaller than about 64k.  Anything larger causes the linker
+to report an error such as:
+
+@cindex relocation truncated to fit (MIPS)
+@smallexample
+relocation truncated to fit: R_MIPS_GOT16 foobar
+@end smallexample
+
+If this happens, you should recompile your code with @option{-mxgot}.
+This works with very large GOTs, although the code is also
+less efficient, since it takes three instructions to fetch the
+value of a global symbol.
+
+Note that some linkers can create multiple GOTs.  If you have such a
+linker, you should only need to use @option{-mxgot} when a single object
+file accesses more than 64k's worth of GOT entries.  Very few do.
+
+These options have no effect unless GCC is generating position
+independent code.
+
+@item -mgp32
+@opindex mgp32
+Assume that general-purpose registers are 32 bits wide.
+
+@item -mgp64
+@opindex mgp64
+Assume that general-purpose registers are 64 bits wide.
+
+@item -mfp32
+@opindex mfp32
+Assume that floating-point registers are 32 bits wide.
+
+@item -mfp64
+@opindex mfp64
+Assume that floating-point registers are 64 bits wide.
+
+@item -mfpxx
+@opindex mfpxx
+Do not assume the width of floating-point registers.
+
+@item -mhard-float
+@opindex mhard-float
+Use floating-point coprocessor instructions.
+
+@item -msoft-float
+@opindex msoft-float
+Do not use floating-point coprocessor instructions.  Implement
+floating-point calculations using library calls instead.
+
+@item -mno-float
+@opindex mno-float
+Equivalent to @option{-msoft-float}, but additionally asserts that the
+program being compiled does not perform any floating-point operations.
+This option is presently supported only by some bare-metal MIPS
+configurations, where it may select a special set of libraries
+that lack all floating-point support (including, for example, the
+floating-point @code{printf} formats).  
+If code compiled with @option{-mno-float} accidentally contains
+floating-point operations, it is likely to suffer a link-time
+or run-time failure.
+
+@item -msingle-float
+@opindex msingle-float
+Assume that the floating-point coprocessor only supports single-precision
+operations.
+
+@item -mdouble-float
+@opindex mdouble-float
+Assume that the floating-point coprocessor supports double-precision
+operations.  This is the default.
+
+@item -modd-spreg
+@itemx -mno-odd-spreg
+@opindex modd-spreg
+@opindex mno-odd-spreg
+Enable the use of odd-numbered single-precision floating-point registers
+for the o32 ABI.  This is the default for processors that are known to
+support these registers.  When using the o32 FPXX ABI, @option{-mno-odd-spreg}
+is set by default.
+
+@item -mabs=2008
+@itemx -mabs=legacy
+@opindex mabs=2008
+@opindex mabs=legacy
+These options control the treatment of the special not-a-number (NaN)
+IEEE 754 floating-point data with the @code{abs.@i{fmt}} and
+@code{neg.@i{fmt}} machine instructions.
+
+By default or when @option{-mabs=legacy} is used the legacy
+treatment is selected.  In this case these instructions are considered
+arithmetic and avoided where correct operation is required and the
+input operand might be a NaN.  A longer sequence of instructions that
+manipulate the sign bit of floating-point datum manually is used
+instead unless the @option{-ffinite-math-only} option has also been
+specified.
+
+The @option{-mabs=2008} option selects the IEEE 754-2008 treatment.  In
+this case these instructions are considered non-arithmetic and therefore
+operating correctly in all cases, including in particular where the
+input operand is a NaN.  These instructions are therefore always used
+for the respective operations.
+
+@item -mnan=2008
+@itemx -mnan=legacy
+@opindex mnan=2008
+@opindex mnan=legacy
+These options control the encoding of the special not-a-number (NaN)
+IEEE 754 floating-point data.
+
+The @option{-mnan=legacy} option selects the legacy encoding.  In this
+case quiet NaNs (qNaNs) are denoted by the first bit of their trailing
+significand field being 0, whereas signaling NaNs (sNaNs) are denoted
+by the first bit of their trailing significand field being 1.
+
+The @option{-mnan=2008} option selects the IEEE 754-2008 encoding.  In
+this case qNaNs are denoted by the first bit of their trailing
+significand field being 1, whereas sNaNs are denoted by the first bit of
+their trailing significand field being 0.
+
+The default is @option{-mnan=legacy} unless GCC has been configured with
+@option{--with-nan=2008}.
+
+@item -mllsc
+@itemx -mno-llsc
+@opindex mllsc
+@opindex mno-llsc
+Use (do not use) @samp{ll}, @samp{sc}, and @samp{sync} instructions to
+implement atomic memory built-in functions.  When neither option is
+specified, GCC uses the instructions if the target architecture
+supports them.
+
+@option{-mllsc} is useful if the runtime environment can emulate the
+instructions and @option{-mno-llsc} can be useful when compiling for
+nonstandard ISAs.  You can make either option the default by
+configuring GCC with @option{--with-llsc} and @option{--without-llsc}
+respectively.  @option{--with-llsc} is the default for some
+configurations; see the installation documentation for details.
+
+@item -mdsp
+@itemx -mno-dsp
+@opindex mdsp
+@opindex mno-dsp
+Use (do not use) revision 1 of the MIPS DSP ASE@.
+@xref{MIPS DSP Built-in Functions}.  This option defines the
+preprocessor macro @code{__mips_dsp}.  It also defines
+@code{__mips_dsp_rev} to 1.
+
+@item -mdspr2
+@itemx -mno-dspr2
+@opindex mdspr2
+@opindex mno-dspr2
+Use (do not use) revision 2 of the MIPS DSP ASE@.
+@xref{MIPS DSP Built-in Functions}.  This option defines the
+preprocessor macros @code{__mips_dsp} and @code{__mips_dspr2}.
+It also defines @code{__mips_dsp_rev} to 2.
+
+@item -msmartmips
+@itemx -mno-smartmips
+@opindex msmartmips
+@opindex mno-smartmips
+Use (do not use) the MIPS SmartMIPS ASE.
+
+@item -mpaired-single
+@itemx -mno-paired-single
+@opindex mpaired-single
+@opindex mno-paired-single
+Use (do not use) paired-single floating-point instructions.
+@xref{MIPS Paired-Single Support}.  This option requires
+hardware floating-point support to be enabled.
+
+@item -mdmx
+@itemx -mno-mdmx
+@opindex mdmx
+@opindex mno-mdmx
+Use (do not use) MIPS Digital Media Extension instructions.
+This option can only be used when generating 64-bit code and requires
+hardware floating-point support to be enabled.
+
+@item -mips3d
+@itemx -mno-mips3d
+@opindex mips3d
+@opindex mno-mips3d
+Use (do not use) the MIPS-3D ASE@.  @xref{MIPS-3D Built-in Functions}.
+The option @option{-mips3d} implies @option{-mpaired-single}.
+
+@item -mmicromips
+@itemx -mno-micromips
+@opindex mmicromips
+@opindex mno-mmicromips
+Generate (do not generate) microMIPS code.
+
+MicroMIPS code generation can also be controlled on a per-function basis
+by means of @code{micromips} and @code{nomicromips} attributes.
+@xref{Function Attributes}, for more information.
+
+@item -mmt
+@itemx -mno-mt
+@opindex mmt
+@opindex mno-mt
+Use (do not use) MT Multithreading instructions.
+
+@item -mmcu
+@itemx -mno-mcu
+@opindex mmcu
+@opindex mno-mcu
+Use (do not use) the MIPS MCU ASE instructions.
+
+@item -meva
+@itemx -mno-eva
+@opindex meva
+@opindex mno-eva
+Use (do not use) the MIPS Enhanced Virtual Addressing instructions.
+
+@item -mvirt
+@itemx -mno-virt
+@opindex mvirt
+@opindex mno-virt
+Use (do not use) the MIPS Virtualization (VZ) instructions.
+
+@item -mxpa
+@itemx -mno-xpa
+@opindex mxpa
+@opindex mno-xpa
+Use (do not use) the MIPS eXtended Physical Address (XPA) instructions.
+
+@item -mcrc
+@itemx -mno-crc
+@opindex mcrc
+@opindex mno-crc
+Use (do not use) the MIPS Cyclic Redundancy Check (CRC) instructions.
+
+@item -mginv
+@itemx -mno-ginv
+@opindex mginv
+@opindex mno-ginv
+Use (do not use) the MIPS Global INValidate (GINV) instructions.
+
+@item -mloongson-mmi
+@itemx -mno-loongson-mmi
+@opindex mloongson-mmi
+@opindex mno-loongson-mmi
+Use (do not use) the MIPS Loongson MultiMedia extensions Instructions (MMI).
+
+@item -mloongson-ext
+@itemx -mno-loongson-ext
+@opindex mloongson-ext
+@opindex mno-loongson-ext
+Use (do not use) the MIPS Loongson EXTensions (EXT) instructions.
+
+@item -mloongson-ext2
+@itemx -mno-loongson-ext2
+@opindex mloongson-ext2
+@opindex mno-loongson-ext2
+Use (do not use) the MIPS Loongson EXTensions r2 (EXT2) instructions.
+
+@item -mlong64
+@opindex mlong64
+Force @code{long} types to be 64 bits wide.  See @option{-mlong32} for
+an explanation of the default and the way that the pointer size is
+determined.
+
+@item -mlong32
+@opindex mlong32
+Force @code{long}, @code{int}, and pointer types to be 32 bits wide.
+
+The default size of @code{int}s, @code{long}s and pointers depends on
+the ABI@.  All the supported ABIs use 32-bit @code{int}s.  The n64 ABI
+uses 64-bit @code{long}s, as does the 64-bit EABI; the others use
+32-bit @code{long}s.  Pointers are the same size as @code{long}s,
+or the same size as integer registers, whichever is smaller.
+
+@item -msym32
+@itemx -mno-sym32
+@opindex msym32
+@opindex mno-sym32
+Assume (do not assume) that all symbols have 32-bit values, regardless
+of the selected ABI@.  This option is useful in combination with
+@option{-mabi=64} and @option{-mno-abicalls} because it allows GCC
+to generate shorter and faster references to symbolic addresses.
+
+@item -G @var{num}
+@opindex G
+Put definitions of externally-visible data in a small data section
+if that data is no bigger than @var{num} bytes.  GCC can then generate
+more efficient accesses to the data; see @option{-mgpopt} for details.
+
+The default @option{-G} option depends on the configuration.
+
+@item -mlocal-sdata
+@itemx -mno-local-sdata
+@opindex mlocal-sdata
+@opindex mno-local-sdata
+Extend (do not extend) the @option{-G} behavior to local data too,
+such as to static variables in C@.  @option{-mlocal-sdata} is the
+default for all configurations.
+
+If the linker complains that an application is using too much small data,
+you might want to try rebuilding the less performance-critical parts with
+@option{-mno-local-sdata}.  You might also want to build large
+libraries with @option{-mno-local-sdata}, so that the libraries leave
+more room for the main program.
+
+@item -mextern-sdata
+@itemx -mno-extern-sdata
+@opindex mextern-sdata
+@opindex mno-extern-sdata
+Assume (do not assume) that externally-defined data is in
+a small data section if the size of that data is within the @option{-G} limit.
+@option{-mextern-sdata} is the default for all configurations.
+
+If you compile a module @var{Mod} with @option{-mextern-sdata} @option{-G
+@var{num}} @option{-mgpopt}, and @var{Mod} references a variable @var{Var}
+that is no bigger than @var{num} bytes, you must make sure that @var{Var}
+is placed in a small data section.  If @var{Var} is defined by another
+module, you must either compile that module with a high-enough
+@option{-G} setting or attach a @code{section} attribute to @var{Var}'s
+definition.  If @var{Var} is common, you must link the application
+with a high-enough @option{-G} setting.
+
+The easiest way of satisfying these restrictions is to compile
+and link every module with the same @option{-G} option.  However,
+you may wish to build a library that supports several different
+small data limits.  You can do this by compiling the library with
+the highest supported @option{-G} setting and additionally using
+@option{-mno-extern-sdata} to stop the library from making assumptions
+about externally-defined data.
+
+@item -mgpopt
+@itemx -mno-gpopt
+@opindex mgpopt
+@opindex mno-gpopt
+Use (do not use) GP-relative accesses for symbols that are known to be
+in a small data section; see @option{-G}, @option{-mlocal-sdata} and
+@option{-mextern-sdata}.  @option{-mgpopt} is the default for all
+configurations.
+
+@option{-mno-gpopt} is useful for cases where the @code{$gp} register
+might not hold the value of @code{_gp}.  For example, if the code is
+part of a library that might be used in a boot monitor, programs that
+call boot monitor routines pass an unknown value in @code{$gp}.
+(In such situations, the boot monitor itself is usually compiled
+with @option{-G0}.)
+
+@option{-mno-gpopt} implies @option{-mno-local-sdata} and
+@option{-mno-extern-sdata}.
+
+@item -membedded-data
+@itemx -mno-embedded-data
+@opindex membedded-data
+@opindex mno-embedded-data
+Allocate variables to the read-only data section first if possible, then
+next in the small data section if possible, otherwise in data.  This gives
+slightly slower code than the default, but reduces the amount of RAM required
+when executing, and thus may be preferred for some embedded systems.
+
+@item -muninit-const-in-rodata
+@itemx -mno-uninit-const-in-rodata
+@opindex muninit-const-in-rodata
+@opindex mno-uninit-const-in-rodata
+Put uninitialized @code{const} variables in the read-only data section.
+This option is only meaningful in conjunction with @option{-membedded-data}.
+
+@item -mcode-readable=@var{setting}
+@opindex mcode-readable
+Specify whether GCC may generate code that reads from executable sections.
+There are three possible settings:
+
+@table @gcctabopt
+@item -mcode-readable=yes
+Instructions may freely access executable sections.  This is the
+default setting.
+
+@item -mcode-readable=pcrel
+MIPS16 PC-relative load instructions can access executable sections,
+but other instructions must not do so.  This option is useful on 4KSc
+and 4KSd processors when the code TLBs have the Read Inhibit bit set.
+It is also useful on processors that can be configured to have a dual
+instruction/data SRAM interface and that, like the M4K, automatically
+redirect PC-relative loads to the instruction RAM.
+
+@item -mcode-readable=no
+Instructions must not access executable sections.  This option can be
+useful on targets that are configured to have a dual instruction/data
+SRAM interface but that (unlike the M4K) do not automatically redirect
+PC-relative loads to the instruction RAM.
+@end table
+
+@item -msplit-addresses
+@itemx -mno-split-addresses
+@opindex msplit-addresses
+@opindex mno-split-addresses
+Enable (disable) use of the @code{%hi()} and @code{%lo()} assembler
+relocation operators.  This option has been superseded by
+@option{-mexplicit-relocs} but is retained for backwards compatibility.
+
+@item -mexplicit-relocs
+@itemx -mno-explicit-relocs
+@opindex mexplicit-relocs
+@opindex mno-explicit-relocs
+Use (do not use) assembler relocation operators when dealing with symbolic
+addresses.  The alternative, selected by @option{-mno-explicit-relocs},
+is to use assembler macros instead.
+
+@option{-mexplicit-relocs} is the default if GCC was configured
+to use an assembler that supports relocation operators.
+
+@item -mcheck-zero-division
+@itemx -mno-check-zero-division
+@opindex mcheck-zero-division
+@opindex mno-check-zero-division
+Trap (do not trap) on integer division by zero.
+
+The default is @option{-mcheck-zero-division}.
+
+@item -mdivide-traps
+@itemx -mdivide-breaks
+@opindex mdivide-traps
+@opindex mdivide-breaks
+MIPS systems check for division by zero by generating either a
+conditional trap or a break instruction.  Using traps results in
+smaller code, but is only supported on MIPS II and later.  Also, some
+versions of the Linux kernel have a bug that prevents trap from
+generating the proper signal (@code{SIGFPE}).  Use @option{-mdivide-traps} to
+allow conditional traps on architectures that support them and
+@option{-mdivide-breaks} to force the use of breaks.
+
+The default is usually @option{-mdivide-traps}, but this can be
+overridden at configure time using @option{--with-divide=breaks}.
+Divide-by-zero checks can be completely disabled using
+@option{-mno-check-zero-division}.
+
+@item -mload-store-pairs
+@itemx -mno-load-store-pairs
+@opindex mload-store-pairs
+@opindex mno-load-store-pairs
+Enable (disable) an optimization that pairs consecutive load or store
+instructions to enable load/store bonding.  This option is enabled by
+default but only takes effect when the selected architecture is known
+to support bonding.
+
+@item -munaligned-access
+@itemx -mno-unaligned-access
+@opindex munaligned-access
+@opindex mno-unaligned-access
+Enable (disable) direct unaligned access for MIPS Release 6.
+MIPSr6 requires load/store unaligned-access support,
+by hardware or trap&emulate.
+So @option{-mno-unaligned-access} may be needed by kernel.
+
+@item -mmemcpy
+@itemx -mno-memcpy
+@opindex mmemcpy
+@opindex mno-memcpy
+Force (do not force) the use of @code{memcpy} for non-trivial block
+moves.  The default is @option{-mno-memcpy}, which allows GCC to inline
+most constant-sized copies.
+
+@item -mlong-calls
+@itemx -mno-long-calls
+@opindex mlong-calls
+@opindex mno-long-calls
+Disable (do not disable) use of the @code{jal} instruction.  Calling
+functions using @code{jal} is more efficient but requires the caller
+and callee to be in the same 256 megabyte segment.
+
+This option has no effect on abicalls code.  The default is
+@option{-mno-long-calls}.
+
+@item -mmad
+@itemx -mno-mad
+@opindex mmad
+@opindex mno-mad
+Enable (disable) use of the @code{mad}, @code{madu} and @code{mul}
+instructions, as provided by the R4650 ISA@.
+
+@item -mimadd
+@itemx -mno-imadd
+@opindex mimadd
+@opindex mno-imadd
+Enable (disable) use of the @code{madd} and @code{msub} integer
+instructions.  The default is @option{-mimadd} on architectures
+that support @code{madd} and @code{msub} except for the 74k 
+architecture where it was found to generate slower code.
+
+@item -mfused-madd
+@itemx -mno-fused-madd
+@opindex mfused-madd
+@opindex mno-fused-madd
+Enable (disable) use of the floating-point multiply-accumulate
+instructions, when they are available.  The default is
+@option{-mfused-madd}.
+
+On the R8000 CPU when multiply-accumulate instructions are used,
+the intermediate product is calculated to infinite precision
+and is not subject to the FCSR Flush to Zero bit.  This may be
+undesirable in some circumstances.  On other processors the result
+is numerically identical to the equivalent computation using
+separate multiply, add, subtract and negate instructions.
+
+@item -nocpp
+@opindex nocpp
+Tell the MIPS assembler to not run its preprocessor over user
+assembler files (with a @samp{.s} suffix) when assembling them.
+
+@item -mfix-24k
+@itemx -mno-fix-24k
+@opindex mfix-24k
+@opindex mno-fix-24k
+Work around the 24K E48 (lost data on stores during refill) errata.
+The workarounds are implemented by the assembler rather than by GCC@.
+
+@item -mfix-r4000
+@itemx -mno-fix-r4000
+@opindex mfix-r4000
+@opindex mno-fix-r4000
+Work around certain R4000 CPU errata:
+@itemize @minus
+@item
+A double-word or a variable shift may give an incorrect result if executed
+immediately after starting an integer division.
+@item
+A double-word or a variable shift may give an incorrect result if executed
+while an integer multiplication is in progress.
+@item
+An integer division may give an incorrect result if started in a delay slot
+of a taken branch or a jump.
+@end itemize
+
+@item -mfix-r4400
+@itemx -mno-fix-r4400
+@opindex mfix-r4400
+@opindex mno-fix-r4400
+Work around certain R4400 CPU errata:
+@itemize @minus
+@item
+A double-word or a variable shift may give an incorrect result if executed
+immediately after starting an integer division.
+@end itemize
+
+@item -mfix-r10000
+@itemx -mno-fix-r10000
+@opindex mfix-r10000
+@opindex mno-fix-r10000
+Work around certain R10000 errata:
+@itemize @minus
+@item
+@code{ll}/@code{sc} sequences may not behave atomically on revisions
+prior to 3.0.  They may deadlock on revisions 2.6 and earlier.
+@end itemize
+
+This option can only be used if the target architecture supports
+branch-likely instructions.  @option{-mfix-r10000} is the default when
+@option{-march=r10000} is used; @option{-mno-fix-r10000} is the default
+otherwise.
+
+@item -mfix-r5900
+@itemx -mno-fix-r5900
+@opindex mfix-r5900
+Do not attempt to schedule the preceding instruction into the delay slot
+of a branch instruction placed at the end of a short loop of six
+instructions or fewer and always schedule a @code{nop} instruction there
+instead.  The short loop bug under certain conditions causes loops to
+execute only once or twice, due to a hardware bug in the R5900 chip.  The
+workaround is implemented by the assembler rather than by GCC@.
+
+@item -mfix-rm7000
+@itemx -mno-fix-rm7000
+@opindex mfix-rm7000
+Work around the RM7000 @code{dmult}/@code{dmultu} errata.  The
+workarounds are implemented by the assembler rather than by GCC@.
+
+@item -mfix-vr4120
+@itemx -mno-fix-vr4120
+@opindex mfix-vr4120
+Work around certain VR4120 errata:
+@itemize @minus
+@item
+@code{dmultu} does not always produce the correct result.
+@item
+@code{div} and @code{ddiv} do not always produce the correct result if one
+of the operands is negative.
+@end itemize
+The workarounds for the division errata rely on special functions in
+@file{libgcc.a}.  At present, these functions are only provided by
+the @code{mips64vr*-elf} configurations.
+
+Other VR4120 errata require a NOP to be inserted between certain pairs of
+instructions.  These errata are handled by the assembler, not by GCC itself.
+
+@item -mfix-vr4130
+@opindex mfix-vr4130
+Work around the VR4130 @code{mflo}/@code{mfhi} errata.  The
+workarounds are implemented by the assembler rather than by GCC,
+although GCC avoids using @code{mflo} and @code{mfhi} if the
+VR4130 @code{macc}, @code{macchi}, @code{dmacc} and @code{dmacchi}
+instructions are available instead.
+
+@item -mfix-sb1
+@itemx -mno-fix-sb1
+@opindex mfix-sb1
+Work around certain SB-1 CPU core errata.
+(This flag currently works around the SB-1 revision 2
+``F1'' and ``F2'' floating-point errata.)
+
+@item -mr10k-cache-barrier=@var{setting}
+@opindex mr10k-cache-barrier
+Specify whether GCC should insert cache barriers to avoid the
+side effects of speculation on R10K processors.
+
+In common with many processors, the R10K tries to predict the outcome
+of a conditional branch and speculatively executes instructions from
+the ``taken'' branch.  It later aborts these instructions if the
+predicted outcome is wrong.  However, on the R10K, even aborted
+instructions can have side effects.
+
+This problem only affects kernel stores and, depending on the system,
+kernel loads.  As an example, a speculatively-executed store may load
+the target memory into cache and mark the cache line as dirty, even if
+the store itself is later aborted.  If a DMA operation writes to the
+same area of memory before the ``dirty'' line is flushed, the cached
+data overwrites the DMA-ed data.  See the R10K processor manual
+for a full description, including other potential problems.
+
+One workaround is to insert cache barrier instructions before every memory
+access that might be speculatively executed and that might have side
+effects even if aborted.  @option{-mr10k-cache-barrier=@var{setting}}
+controls GCC's implementation of this workaround.  It assumes that
+aborted accesses to any byte in the following regions does not have
+side effects:
+
+@enumerate
+@item
+the memory occupied by the current function's stack frame;
+
+@item
+the memory occupied by an incoming stack argument;
+
+@item
+the memory occupied by an object with a link-time-constant address.
+@end enumerate
+
+It is the kernel's responsibility to ensure that speculative
+accesses to these regions are indeed safe.
+
+If the input program contains a function declaration such as:
+
+@smallexample
+void foo (void);
+@end smallexample
+
+then the implementation of @code{foo} must allow @code{j foo} and
+@code{jal foo} to be executed speculatively.  GCC honors this
+restriction for functions it compiles itself.  It expects non-GCC
+functions (such as hand-written assembly code) to do the same.
+
+The option has three forms:
+
+@table @gcctabopt
+@item -mr10k-cache-barrier=load-store
+Insert a cache barrier before a load or store that might be
+speculatively executed and that might have side effects even
+if aborted.
+
+@item -mr10k-cache-barrier=store
+Insert a cache barrier before a store that might be speculatively
+executed and that might have side effects even if aborted.
+
+@item -mr10k-cache-barrier=none
+Disable the insertion of cache barriers.  This is the default setting.
+@end table
+
+@item -mflush-func=@var{func}
+@itemx -mno-flush-func
+@opindex mflush-func
+Specifies the function to call to flush the I and D caches, or to not
+call any such function.  If called, the function must take the same
+arguments as the common @code{_flush_func}, that is, the address of the
+memory range for which the cache is being flushed, the size of the
+memory range, and the number 3 (to flush both caches).  The default
+depends on the target GCC was configured for, but commonly is either
+@code{_flush_func} or @code{__cpu_flush}.
+
+@item mbranch-cost=@var{num}
+@opindex mbranch-cost
+Set the cost of branches to roughly @var{num} ``simple'' instructions.
+This cost is only a heuristic and is not guaranteed to produce
+consistent results across releases.  A zero cost redundantly selects
+the default, which is based on the @option{-mtune} setting.
+
+@item -mbranch-likely
+@itemx -mno-branch-likely
+@opindex mbranch-likely
+@opindex mno-branch-likely
+Enable or disable use of Branch Likely instructions, regardless of the
+default for the selected architecture.  By default, Branch Likely
+instructions may be generated if they are supported by the selected
+architecture.  An exception is for the MIPS32 and MIPS64 architectures
+and processors that implement those architectures; for those, Branch
+Likely instructions are not be generated by default because the MIPS32
+and MIPS64 architectures specifically deprecate their use.
+
+@item -mcompact-branches=never
+@itemx -mcompact-branches=optimal
+@itemx -mcompact-branches=always
+@opindex mcompact-branches=never
+@opindex mcompact-branches=optimal
+@opindex mcompact-branches=always
+These options control which form of branches will be generated.  The
+default is @option{-mcompact-branches=optimal}.
+
+The @option{-mcompact-branches=never} option ensures that compact branch
+instructions will never be generated.
+
+The @option{-mcompact-branches=always} option ensures that a compact
+branch instruction will be generated if available for MIPS Release 6 onwards.
+If a compact branch instruction is not available (or pre-R6),
+a delay slot form of the branch will be used instead.
+
+If it is used for MIPS16/microMIPS targets, it will be just ignored now.
+The behaviour for MIPS16/microMIPS may change in future,
+since they do have some compact branch instructions.
+
+The @option{-mcompact-branches=optimal} option will cause a delay slot
+branch to be used if one is available in the current ISA and the delay
+slot is successfully filled.  If the delay slot is not filled, a compact
+branch will be chosen if one is available.
+
+@item -mfp-exceptions
+@itemx -mno-fp-exceptions
+@opindex mfp-exceptions
+Specifies whether FP exceptions are enabled.  This affects how
+FP instructions are scheduled for some processors.
+The default is that FP exceptions are
+enabled.
+
+For instance, on the SB-1, if FP exceptions are disabled, and we are emitting
+64-bit code, then we can use both FP pipes.  Otherwise, we can only use one
+FP pipe.
+
+@item -mvr4130-align
+@itemx -mno-vr4130-align
+@opindex mvr4130-align
+The VR4130 pipeline is two-way superscalar, but can only issue two
+instructions together if the first one is 8-byte aligned.  When this
+option is enabled, GCC aligns pairs of instructions that it
+thinks should execute in parallel.
+
+This option only has an effect when optimizing for the VR4130.
+It normally makes code faster, but at the expense of making it bigger.
+It is enabled by default at optimization level @option{-O3}.
+
+@item -msynci
+@itemx -mno-synci
+@opindex msynci
+Enable (disable) generation of @code{synci} instructions on
+architectures that support it.  The @code{synci} instructions (if
+enabled) are generated when @code{__builtin___clear_cache} is
+compiled.
+
+This option defaults to @option{-mno-synci}, but the default can be
+overridden by configuring GCC with @option{--with-synci}.
+
+When compiling code for single processor systems, it is generally safe
+to use @code{synci}.  However, on many multi-core (SMP) systems, it
+does not invalidate the instruction caches on all cores and may lead
+to undefined behavior.
+
+@item -mrelax-pic-calls
+@itemx -mno-relax-pic-calls
+@opindex mrelax-pic-calls
+Try to turn PIC calls that are normally dispatched via register
+@code{$25} into direct calls.  This is only possible if the linker can
+resolve the destination at link time and if the destination is within
+range for a direct call.
+
+@option{-mrelax-pic-calls} is the default if GCC was configured to use
+an assembler and a linker that support the @code{.reloc} assembly
+directive and @option{-mexplicit-relocs} is in effect.  With
+@option{-mno-explicit-relocs}, this optimization can be performed by the
+assembler and the linker alone without help from the compiler.
+
+@item -mmcount-ra-address
+@itemx -mno-mcount-ra-address
+@opindex mmcount-ra-address
+@opindex mno-mcount-ra-address
+Emit (do not emit) code that allows @code{_mcount} to modify the
+calling function's return address.  When enabled, this option extends
+the usual @code{_mcount} interface with a new @var{ra-address}
+parameter, which has type @code{intptr_t *} and is passed in register
+@code{$12}.  @code{_mcount} can then modify the return address by
+doing both of the following:
+@itemize
+@item
+Returning the new address in register @code{$31}.
+@item
+Storing the new address in @code{*@var{ra-address}},
+if @var{ra-address} is nonnull.
+@end itemize
+
+The default is @option{-mno-mcount-ra-address}.
+
+@item -mframe-header-opt
+@itemx -mno-frame-header-opt
+@opindex mframe-header-opt
+Enable (disable) frame header optimization in the o32 ABI.  When using the
+o32 ABI, calling functions will allocate 16 bytes on the stack for the called
+function to write out register arguments.  When enabled, this optimization
+will suppress the allocation of the frame header if it can be determined that
+it is unused.
+
+This optimization is off by default at all optimization levels.
+
+@item -mlxc1-sxc1
+@itemx -mno-lxc1-sxc1
+@opindex mlxc1-sxc1
+When applicable, enable (disable) the generation of @code{lwxc1},
+@code{swxc1}, @code{ldxc1}, @code{sdxc1} instructions.  Enabled by default.
+
+@item -mmadd4
+@itemx -mno-madd4
+@opindex mmadd4
+When applicable, enable (disable) the generation of 4-operand @code{madd.s},
+@code{madd.d} and related instructions.  Enabled by default.
+
+@end table
+
+@node MMIX Options
+@subsection MMIX Options
+@cindex MMIX Options
+
+These options are defined for the MMIX:
+
+@table @gcctabopt
+@item -mlibfuncs
+@itemx -mno-libfuncs
+@opindex mlibfuncs
+@opindex mno-libfuncs
+Specify that intrinsic library functions are being compiled, passing all
+values in registers, no matter the size.
+
+@item -mepsilon
+@itemx -mno-epsilon
+@opindex mepsilon
+@opindex mno-epsilon
+Generate floating-point comparison instructions that compare with respect
+to the @code{rE} epsilon register.
+
+@item -mabi=mmixware
+@itemx -mabi=gnu
+@opindex mabi=mmixware
+@opindex mabi=gnu
+Generate code that passes function parameters and return values that (in
+the called function) are seen as registers @code{$0} and up, as opposed to
+the GNU ABI which uses global registers @code{$231} and up.
+
+@item -mzero-extend
+@itemx -mno-zero-extend
+@opindex mzero-extend
+@opindex mno-zero-extend
+When reading data from memory in sizes shorter than 64 bits, use (do not
+use) zero-extending load instructions by default, rather than
+sign-extending ones.
+
+@item -mknuthdiv
+@itemx -mno-knuthdiv
+@opindex mknuthdiv
+@opindex mno-knuthdiv
+Make the result of a division yielding a remainder have the same sign as
+the divisor.  With the default, @option{-mno-knuthdiv}, the sign of the
+remainder follows the sign of the dividend.  Both methods are
+arithmetically valid, the latter being almost exclusively used.
+
+@item -mtoplevel-symbols
+@itemx -mno-toplevel-symbols
+@opindex mtoplevel-symbols
+@opindex mno-toplevel-symbols
+Prepend (do not prepend) a @samp{:} to all global symbols, so the assembly
+code can be used with the @code{PREFIX} assembly directive.
+
+@item -melf
+@opindex melf
+Generate an executable in the ELF format, rather than the default
+@samp{mmo} format used by the @command{mmix} simulator.
+
+@item -mbranch-predict
+@itemx -mno-branch-predict
+@opindex mbranch-predict
+@opindex mno-branch-predict
+Use (do not use) the probable-branch instructions, when static branch
+prediction indicates a probable branch.
+
+@item -mbase-addresses
+@itemx -mno-base-addresses
+@opindex mbase-addresses
+@opindex mno-base-addresses
+Generate (do not generate) code that uses @emph{base addresses}.  Using a
+base address automatically generates a request (handled by the assembler
+and the linker) for a constant to be set up in a global register.  The
+register is used for one or more base address requests within the range 0
+to 255 from the value held in the register.  The generally leads to short
+and fast code, but the number of different data items that can be
+addressed is limited.  This means that a program that uses lots of static
+data may require @option{-mno-base-addresses}.
+
+@item -msingle-exit
+@itemx -mno-single-exit
+@opindex msingle-exit
+@opindex mno-single-exit
+Force (do not force) generated code to have a single exit point in each
+function.
+@end table
+
+@node MN10300 Options
+@subsection MN10300 Options
+@cindex MN10300 options
+
+These @option{-m} options are defined for Matsushita MN10300 architectures:
+
+@table @gcctabopt
+@item -mmult-bug
+@opindex mmult-bug
+Generate code to avoid bugs in the multiply instructions for the MN10300
+processors.  This is the default.
+
+@item -mno-mult-bug
+@opindex mno-mult-bug
+Do not generate code to avoid bugs in the multiply instructions for the
+MN10300 processors.
+
+@item -mam33
+@opindex mam33
+Generate code using features specific to the AM33 processor.
+
+@item -mno-am33
+@opindex mno-am33
+Do not generate code using features specific to the AM33 processor.  This
+is the default.
+
+@item -mam33-2
+@opindex mam33-2
+Generate code using features specific to the AM33/2.0 processor.
+
+@item -mam34
+@opindex mam34
+Generate code using features specific to the AM34 processor.
+
+@item -mtune=@var{cpu-type}
+@opindex mtune
+Use the timing characteristics of the indicated CPU type when
+scheduling instructions.  This does not change the targeted processor
+type.  The CPU type must be one of @samp{mn10300}, @samp{am33},
+@samp{am33-2} or @samp{am34}.
+
+@item -mreturn-pointer-on-d0
+@opindex mreturn-pointer-on-d0
+When generating a function that returns a pointer, return the pointer
+in both @code{a0} and @code{d0}.  Otherwise, the pointer is returned
+only in @code{a0}, and attempts to call such functions without a prototype
+result in errors.  Note that this option is on by default; use
+@option{-mno-return-pointer-on-d0} to disable it.
+
+@item -mno-crt0
+@opindex mno-crt0
+Do not link in the C run-time initialization object file.
+
+@item -mrelax
+@opindex mrelax
+Indicate to the linker that it should perform a relaxation optimization pass
+to shorten branches, calls and absolute memory addresses.  This option only
+has an effect when used on the command line for the final link step.
+
+This option makes symbolic debugging impossible.
+
+@item -mliw
+@opindex mliw
+Allow the compiler to generate @emph{Long Instruction Word}
+instructions if the target is the @samp{AM33} or later.  This is the
+default.  This option defines the preprocessor macro @code{__LIW__}.
+
+@item -mno-liw
+@opindex mno-liw
+Do not allow the compiler to generate @emph{Long Instruction Word}
+instructions.  This option defines the preprocessor macro
+@code{__NO_LIW__}.
+
+@item -msetlb
+@opindex msetlb
+Allow the compiler to generate the @emph{SETLB} and @emph{Lcc}
+instructions if the target is the @samp{AM33} or later.  This is the
+default.  This option defines the preprocessor macro @code{__SETLB__}.
+
+@item -mno-setlb
+@opindex mno-setlb
+Do not allow the compiler to generate @emph{SETLB} or @emph{Lcc}
+instructions.  This option defines the preprocessor macro
+@code{__NO_SETLB__}.
+
+@end table
+
+@node Moxie Options
+@subsection Moxie Options
+@cindex Moxie Options
+
+@table @gcctabopt
+
+@item -meb
+@opindex meb
+Generate big-endian code.  This is the default for @samp{moxie-*-*}
+configurations.
+
+@item -mel
+@opindex mel
+Generate little-endian code.
+
+@item -mmul.x
+@opindex mmul.x
+Generate mul.x and umul.x instructions.  This is the default for
+@samp{moxiebox-*-*} configurations.
+
+@item -mno-crt0
+@opindex mno-crt0
+Do not link in the C run-time initialization object file.
+
+@end table
+
+@node MSP430 Options
+@subsection MSP430 Options
+@cindex MSP430 Options
+
+These options are defined for the MSP430:
+
+@table @gcctabopt
+
+@item -masm-hex
+@opindex masm-hex
+Force assembly output to always use hex constants.  Normally such
+constants are signed decimals, but this option is available for
+testsuite and/or aesthetic purposes.
+
+@item -mmcu=
+@opindex mmcu=
+Select the MCU to target.  This is used to create a C preprocessor
+symbol based upon the MCU name, converted to upper case and pre- and
+post-fixed with @samp{__}.  This in turn is used by the
+@file{msp430.h} header file to select an MCU-specific supplementary
+header file.
+
+The option also sets the ISA to use.  If the MCU name is one that is
+known to only support the 430 ISA then that is selected, otherwise the
+430X ISA is selected.  A generic MCU name of @samp{msp430} can also be
+used to select the 430 ISA.  Similarly the generic @samp{msp430x} MCU
+name selects the 430X ISA.
+
+In addition an MCU-specific linker script is added to the linker
+command line.  The script's name is the name of the MCU with
+@file{.ld} appended.  Thus specifying @option{-mmcu=xxx} on the @command{gcc}
+command line defines the C preprocessor symbol @code{__XXX__} and
+cause the linker to search for a script called @file{xxx.ld}.
+
+The ISA and hardware multiply supported for the different MCUs is hard-coded
+into GCC.  However, an external @samp{devices.csv} file can be used to
+extend device support beyond those that have been hard-coded.
+
+GCC searches for the @samp{devices.csv} file using the following methods in the
+given precedence order, where the first method takes precendence over the
+second which takes precedence over the third.
+
+@table @asis
+@item Include path specified with @code{-I} and @code{-L}
+@samp{devices.csv} will be searched for in each of the directories specified by
+include paths and linker library search paths.
+@item Path specified by the environment variable @samp{MSP430_GCC_INCLUDE_DIR}
+Define the value of the global environment variable
+@samp{MSP430_GCC_INCLUDE_DIR}
+to the full path to the directory containing devices.csv, and GCC will search
+this directory for devices.csv.  If devices.csv is found, this directory will
+also be registered as an include path, and linker library path.  Header files
+and linker scripts in this directory can therefore be used without manually
+specifying @code{-I} and @code{-L} on the command line.
+@item The @samp{msp430-elf@{,bare@}/include/devices} directory
+Finally, GCC will examine @samp{msp430-elf@{,bare@}/include/devices} from the
+toolchain root directory.  This directory does not exist in a default
+installation, but if the user has created it and copied @samp{devices.csv}
+there, then the MCU data will be read.  As above, this directory will
+also be registered as an include path, and linker library path.
+
+@end table
+If none of the above search methods find @samp{devices.csv}, then the
+hard-coded MCU data is used.
+
+
+@item -mwarn-mcu
+@itemx -mno-warn-mcu
+@opindex mwarn-mcu
+@opindex mno-warn-mcu
+This option enables or disables warnings about conflicts between the
+MCU name specified by the @option{-mmcu} option and the ISA set by the
+@option{-mcpu} option and/or the hardware multiply support set by the
+@option{-mhwmult} option.  It also toggles warnings about unrecognized
+MCU names.  This option is on by default.
+
+@item -mcpu=
+@opindex mcpu=
+Specifies the ISA to use.  Accepted values are @samp{msp430},
+@samp{msp430x} and @samp{msp430xv2}.  This option is deprecated.  The
+@option{-mmcu=} option should be used to select the ISA.
+
+@item -msim
+@opindex msim
+Link to the simulator runtime libraries and linker script.  Overrides
+any scripts that would be selected by the @option{-mmcu=} option.
+
+@item -mlarge
+@opindex mlarge
+Use large-model addressing (20-bit pointers, 20-bit @code{size_t}).
+
+@item -msmall
+@opindex msmall
+Use small-model addressing (16-bit pointers, 16-bit @code{size_t}).
+
+@item -mrelax
+@opindex mrelax
+This option is passed to the assembler and linker, and allows the
+linker to perform certain optimizations that cannot be done until
+the final link.
+
+@item mhwmult=
+@opindex mhwmult=
+Describes the type of hardware multiply supported by the target.
+Accepted values are @samp{none} for no hardware multiply, @samp{16bit}
+for the original 16-bit-only multiply supported by early MCUs.
+@samp{32bit} for the 16/32-bit multiply supported by later MCUs and
+@samp{f5series} for the 16/32-bit multiply supported by F5-series MCUs.
+A value of @samp{auto} can also be given.  This tells GCC to deduce
+the hardware multiply support based upon the MCU name provided by the
+@option{-mmcu} option.  If no @option{-mmcu} option is specified or if
+the MCU name is not recognized then no hardware multiply support is
+assumed.  @code{auto} is the default setting.
+
+Hardware multiplies are normally performed by calling a library
+routine.  This saves space in the generated code.  When compiling at
+@option{-O3} or higher however the hardware multiplier is invoked
+inline.  This makes for bigger, but faster code.
+
+The hardware multiply routines disable interrupts whilst running and
+restore the previous interrupt state when they finish.  This makes
+them safe to use inside interrupt handlers as well as in normal code.
+
+@item -minrt
+@opindex minrt
+Enable the use of a minimum runtime environment - no static
+initializers or constructors.  This is intended for memory-constrained
+devices.  The compiler includes special symbols in some objects
+that tell the linker and runtime which code fragments are required.
+
+@item -mtiny-printf
+@opindex mtiny-printf
+Enable reduced code size @code{printf} and @code{puts} library functions.
+The @samp{tiny} implementations of these functions are not reentrant, so
+must be used with caution in multi-threaded applications.
+
+Support for streams has been removed and the string to be printed will
+always be sent to stdout via the @code{write} syscall.  The string is not
+buffered before it is sent to write.
+
+This option requires Newlib Nano IO, so GCC must be configured with
+@samp{--enable-newlib-nano-formatted-io}.
+
+@item -mmax-inline-shift=
+@opindex mmax-inline-shift=
+This option takes an integer between 0 and 64 inclusive, and sets
+the maximum number of inline shift instructions which should be emitted to
+perform a shift operation by a constant amount.  When this value needs to be
+exceeded, an mspabi helper function is used instead.  The default value is 4.
+
+This only affects cases where a shift by multiple positions cannot be
+completed with a single instruction (e.g. all shifts >1 on the 430 ISA).
+
+Shifts of a 32-bit value are at least twice as costly, so the value passed for
+this option is divided by 2 and the resulting value used instead.
+
+@item -mcode-region=
+@itemx -mdata-region=
+@opindex mcode-region
+@opindex mdata-region
+These options tell the compiler where to place functions and data that
+do not have one of the @code{lower}, @code{upper}, @code{either} or
+@code{section} attributes.  Possible values are @code{lower},
+@code{upper}, @code{either} or @code{any}.  The first three behave
+like the corresponding attribute.  The fourth possible value -
+@code{any} - is the default.  It leaves placement entirely up to the
+linker script and how it assigns the standard sections
+(@code{.text}, @code{.data}, etc) to the memory regions.
+
+@item -msilicon-errata=
+@opindex msilicon-errata
+This option passes on a request to assembler to enable the fixes for
+the named silicon errata.
+
+@item -msilicon-errata-warn=
+@opindex msilicon-errata-warn
+This option passes on a request to the assembler to enable warning
+messages when a silicon errata might need to be applied.
+
+@item -mwarn-devices-csv
+@itemx -mno-warn-devices-csv
+@opindex mwarn-devices-csv
+@opindex mno-warn-devices-csv
+Warn if @samp{devices.csv} is not found or there are problem parsing it
+(default: on).
+
+@end table
+
+@node NDS32 Options
+@subsection NDS32 Options
+@cindex NDS32 Options
+
+These options are defined for NDS32 implementations:
+
+@table @gcctabopt
+
+@item -mbig-endian
+@opindex mbig-endian
+Generate code in big-endian mode.
+
+@item -mlittle-endian
+@opindex mlittle-endian
+Generate code in little-endian mode.
+
+@item -mreduced-regs
+@opindex mreduced-regs
+Use reduced-set registers for register allocation.
+
+@item -mfull-regs
+@opindex mfull-regs
+Use full-set registers for register allocation.
+
+@item -mcmov
+@opindex mcmov
+Generate conditional move instructions.
+
+@item -mno-cmov
+@opindex mno-cmov
+Do not generate conditional move instructions.
+
+@item -mext-perf
+@opindex mext-perf
+Generate performance extension instructions.
+
+@item -mno-ext-perf
+@opindex mno-ext-perf
+Do not generate performance extension instructions.
+
+@item -mext-perf2
+@opindex mext-perf2
+Generate performance extension 2 instructions.
+
+@item -mno-ext-perf2
+@opindex mno-ext-perf2
+Do not generate performance extension 2 instructions.
+
+@item -mext-string
+@opindex mext-string
+Generate string extension instructions.
+
+@item -mno-ext-string
+@opindex mno-ext-string
+Do not generate string extension instructions.
+
+@item -mv3push
+@opindex mv3push
+Generate v3 push25/pop25 instructions.
+
+@item -mno-v3push
+@opindex mno-v3push
+Do not generate v3 push25/pop25 instructions.
+
+@item -m16-bit
+@opindex m16-bit
+Generate 16-bit instructions.
+
+@item -mno-16-bit
+@opindex mno-16-bit
+Do not generate 16-bit instructions.
+
+@item -misr-vector-size=@var{num}
+@opindex misr-vector-size
+Specify the size of each interrupt vector, which must be 4 or 16.
+
+@item -mcache-block-size=@var{num}
+@opindex mcache-block-size
+Specify the size of each cache block,
+which must be a power of 2 between 4 and 512.
+
+@item -march=@var{arch}
+@opindex march
+Specify the name of the target architecture.
+
+@item -mcmodel=@var{code-model}
+@opindex mcmodel
+Set the code model to one of
+@table @asis
+@item @samp{small}
+All the data and read-only data segments must be within 512KB addressing space.
+The text segment must be within 16MB addressing space.
+@item @samp{medium}
+The data segment must be within 512KB while the read-only data segment can be
+within 4GB addressing space.  The text segment should be still within 16MB
+addressing space.
+@item @samp{large}
+All the text and data segments can be within 4GB addressing space.
+@end table
+
+@item -mctor-dtor
+@opindex mctor-dtor
+Enable constructor/destructor feature.
+
+@item -mrelax
+@opindex mrelax
+Guide linker to relax instructions.
+
+@end table
+
+@node Nios II Options
+@subsection Nios II Options
+@cindex Nios II options
+@cindex Altera Nios II options
+
+These are the options defined for the Altera Nios II processor.
+
+@table @gcctabopt
+
+@item -G @var{num}
+@opindex G
+@cindex smaller data references
+Put global and static objects less than or equal to @var{num} bytes
+into the small data or BSS sections instead of the normal data or BSS
+sections.  The default value of @var{num} is 8.
+
+@item -mgpopt=@var{option}
+@itemx -mgpopt
+@itemx -mno-gpopt
+@opindex mgpopt
+@opindex mno-gpopt
+Generate (do not generate) GP-relative accesses.  The following 
+@var{option} names are recognized:
+
+@table @samp
+
+@item none
+Do not generate GP-relative accesses.
+
+@item local
+Generate GP-relative accesses for small data objects that are not 
+external, weak, or uninitialized common symbols.  
+Also use GP-relative addressing for objects that
+have been explicitly placed in a small data section via a @code{section}
+attribute.
+
+@item global
+As for @samp{local}, but also generate GP-relative accesses for
+small data objects that are external, weak, or common.  If you use this option,
+you must ensure that all parts of your program (including libraries) are
+compiled with the same @option{-G} setting.
+
+@item data
+Generate GP-relative accesses for all data objects in the program.  If you
+use this option, the entire data and BSS segments
+of your program must fit in 64K of memory and you must use an appropriate
+linker script to allocate them within the addressable range of the
+global pointer.
+
+@item all
+Generate GP-relative addresses for function pointers as well as data
+pointers.  If you use this option, the entire text, data, and BSS segments
+of your program must fit in 64K of memory and you must use an appropriate
+linker script to allocate them within the addressable range of the
+global pointer.
+
+@end table
+
+@option{-mgpopt} is equivalent to @option{-mgpopt=local}, and
+@option{-mno-gpopt} is equivalent to @option{-mgpopt=none}.
+
+The default is @option{-mgpopt} except when @option{-fpic} or
+@option{-fPIC} is specified to generate position-independent code.
+Note that the Nios II ABI does not permit GP-relative accesses from
+shared libraries.
+
+You may need to specify @option{-mno-gpopt} explicitly when building
+programs that include large amounts of small data, including large
+GOT data sections.  In this case, the 16-bit offset for GP-relative
+addressing may not be large enough to allow access to the entire 
+small data section.
+
+@item -mgprel-sec=@var{regexp}
+@opindex mgprel-sec
+This option specifies additional section names that can be accessed via
+GP-relative addressing.  It is most useful in conjunction with 
+@code{section} attributes on variable declarations 
+(@pxref{Common Variable Attributes}) and a custom linker script.  
+The @var{regexp} is a POSIX Extended Regular Expression.
+
+This option does not affect the behavior of the @option{-G} option, and 
+the specified sections are in addition to the standard @code{.sdata}
+and @code{.sbss} small-data sections that are recognized by @option{-mgpopt}.
+
+@item -mr0rel-sec=@var{regexp}
+@opindex mr0rel-sec
+This option specifies names of sections that can be accessed via a 
+16-bit offset from @code{r0}; that is, in the low 32K or high 32K 
+of the 32-bit address space.  It is most useful in conjunction with 
+@code{section} attributes on variable declarations 
+(@pxref{Common Variable Attributes}) and a custom linker script.  
+The @var{regexp} is a POSIX Extended Regular Expression.
+
+In contrast to the use of GP-relative addressing for small data, 
+zero-based addressing is never generated by default and there are no 
+conventional section names used in standard linker scripts for sections
+in the low or high areas of memory.
+
+@item -mel
+@itemx -meb
+@opindex mel
+@opindex meb
+Generate little-endian (default) or big-endian (experimental) code,
+respectively.
+
+@item -march=@var{arch}
+@opindex march
+This specifies the name of the target Nios II architecture.  GCC uses this
+name to determine what kind of instructions it can emit when generating
+assembly code.  Permissible names are: @samp{r1}, @samp{r2}.
+
+The preprocessor macro @code{__nios2_arch__} is available to programs,
+with value 1 or 2, indicating the targeted ISA level.
+
+@item -mbypass-cache
+@itemx -mno-bypass-cache
+@opindex mno-bypass-cache
+@opindex mbypass-cache
+Force all load and store instructions to always bypass cache by 
+using I/O variants of the instructions. The default is not to
+bypass the cache.
+
+@item -mno-cache-volatile 
+@itemx -mcache-volatile       
+@opindex mcache-volatile 
+@opindex mno-cache-volatile
+Volatile memory access bypass the cache using the I/O variants of 
+the load and store instructions. The default is not to bypass the cache.
+
+@item -mno-fast-sw-div
+@itemx -mfast-sw-div
+@opindex mno-fast-sw-div
+@opindex mfast-sw-div
+Do not use table-based fast divide for small numbers. The default 
+is to use the fast divide at @option{-O3} and above.
+
+@item -mno-hw-mul
+@itemx -mhw-mul
+@itemx -mno-hw-mulx
+@itemx -mhw-mulx
+@itemx -mno-hw-div
+@itemx -mhw-div
+@opindex mno-hw-mul
+@opindex mhw-mul
+@opindex mno-hw-mulx
+@opindex mhw-mulx
+@opindex mno-hw-div
+@opindex mhw-div
+Enable or disable emitting @code{mul}, @code{mulx} and @code{div} family of 
+instructions by the compiler. The default is to emit @code{mul}
+and not emit @code{div} and @code{mulx}.
+
+@item -mbmx
+@itemx -mno-bmx
+@itemx -mcdx
+@itemx -mno-cdx
+Enable or disable generation of Nios II R2 BMX (bit manipulation) and
+CDX (code density) instructions.  Enabling these instructions also
+requires @option{-march=r2}.  Since these instructions are optional
+extensions to the R2 architecture, the default is not to emit them.
+
+@item -mcustom-@var{insn}=@var{N}
+@itemx -mno-custom-@var{insn}
+@opindex mcustom-@var{insn}
+@opindex mno-custom-@var{insn}
+Each @option{-mcustom-@var{insn}=@var{N}} option enables use of a
+custom instruction with encoding @var{N} when generating code that uses 
+@var{insn}.  For example, @option{-mcustom-fadds=253} generates custom
+instruction 253 for single-precision floating-point add operations instead
+of the default behavior of using a library call.
+
+The following values of @var{insn} are supported.  Except as otherwise
+noted, floating-point operations are expected to be implemented with
+normal IEEE 754 semantics and correspond directly to the C operators or the
+equivalent GCC built-in functions (@pxref{Other Builtins}).
+
+Single-precision floating point:
+@table @asis
+
+@item @samp{fadds}, @samp{fsubs}, @samp{fdivs}, @samp{fmuls}
+Binary arithmetic operations.
+
+@item @samp{fnegs}
+Unary negation.
+
+@item @samp{fabss}
+Unary absolute value.
+
+@item @samp{fcmpeqs}, @samp{fcmpges}, @samp{fcmpgts}, @samp{fcmples}, @samp{fcmplts}, @samp{fcmpnes}
+Comparison operations.
+
+@item @samp{fmins}, @samp{fmaxs}
+Floating-point minimum and maximum.  These instructions are only
+generated if @option{-ffinite-math-only} is specified.
+
+@item @samp{fsqrts}
+Unary square root operation.
+
+@item @samp{fcoss}, @samp{fsins}, @samp{ftans}, @samp{fatans}, @samp{fexps}, @samp{flogs}
+Floating-point trigonometric and exponential functions.  These instructions
+are only generated if @option{-funsafe-math-optimizations} is also specified.
+
+@end table
+
+Double-precision floating point:
+@table @asis
+
+@item @samp{faddd}, @samp{fsubd}, @samp{fdivd}, @samp{fmuld}
+Binary arithmetic operations.
+
+@item @samp{fnegd}
+Unary negation.
+
+@item @samp{fabsd}
+Unary absolute value.
+
+@item @samp{fcmpeqd}, @samp{fcmpged}, @samp{fcmpgtd}, @samp{fcmpled}, @samp{fcmpltd}, @samp{fcmpned}
+Comparison operations.
+
+@item @samp{fmind}, @samp{fmaxd}
+Double-precision minimum and maximum.  These instructions are only
+generated if @option{-ffinite-math-only} is specified.
+
+@item @samp{fsqrtd}
+Unary square root operation.
+
+@item @samp{fcosd}, @samp{fsind}, @samp{ftand}, @samp{fatand}, @samp{fexpd}, @samp{flogd}
+Double-precision trigonometric and exponential functions.  These instructions
+are only generated if @option{-funsafe-math-optimizations} is also specified.
+
+@end table
+
+Conversions:
+@table @asis
+@item @samp{fextsd}
+Conversion from single precision to double precision.
+
+@item @samp{ftruncds}
+Conversion from double precision to single precision.
+
+@item @samp{fixsi}, @samp{fixsu}, @samp{fixdi}, @samp{fixdu}
+Conversion from floating point to signed or unsigned integer types, with
+truncation towards zero.
+
+@item @samp{round}
+Conversion from single-precision floating point to signed integer,
+rounding to the nearest integer and ties away from zero.
+This corresponds to the @code{__builtin_lroundf} function when
+@option{-fno-math-errno} is used.
+
+@item @samp{floatis}, @samp{floatus}, @samp{floatid}, @samp{floatud}
+Conversion from signed or unsigned integer types to floating-point types.
+
+@end table
+
+In addition, all of the following transfer instructions for internal
+registers X and Y must be provided to use any of the double-precision
+floating-point instructions.  Custom instructions taking two
+double-precision source operands expect the first operand in the
+64-bit register X.  The other operand (or only operand of a unary
+operation) is given to the custom arithmetic instruction with the
+least significant half in source register @var{src1} and the most
+significant half in @var{src2}.  A custom instruction that returns a
+double-precision result returns the most significant 32 bits in the
+destination register and the other half in 32-bit register Y.  
+GCC automatically generates the necessary code sequences to write
+register X and/or read register Y when double-precision floating-point
+instructions are used.
+
+@table @asis
+
+@item @samp{fwrx}
+Write @var{src1} into the least significant half of X and @var{src2} into
+the most significant half of X.
+
+@item @samp{fwry}
+Write @var{src1} into Y.
+
+@item @samp{frdxhi}, @samp{frdxlo}
+Read the most or least (respectively) significant half of X and store it in
+@var{dest}.
+
+@item @samp{frdy}
+Read the value of Y and store it into @var{dest}.
+@end table
+
+Note that you can gain more local control over generation of Nios II custom
+instructions by using the @code{target("custom-@var{insn}=@var{N}")}
+and @code{target("no-custom-@var{insn}")} function attributes
+(@pxref{Function Attributes})
+or pragmas (@pxref{Function Specific Option Pragmas}).
+
+@item -mcustom-fpu-cfg=@var{name}
+@opindex mcustom-fpu-cfg
+
+This option enables a predefined, named set of custom instruction encodings
+(see @option{-mcustom-@var{insn}} above).  
+Currently, the following sets are defined:
+
+@option{-mcustom-fpu-cfg=60-1} is equivalent to:
+@gccoptlist{-mcustom-fmuls=252 @gol
+-mcustom-fadds=253 @gol
+-mcustom-fsubs=254 @gol
+-fsingle-precision-constant}
+
+@option{-mcustom-fpu-cfg=60-2} is equivalent to:
+@gccoptlist{-mcustom-fmuls=252 @gol
+-mcustom-fadds=253 @gol
+-mcustom-fsubs=254 @gol
+-mcustom-fdivs=255 @gol
+-fsingle-precision-constant}
+
+@option{-mcustom-fpu-cfg=72-3} is equivalent to:
+@gccoptlist{-mcustom-floatus=243 @gol
+-mcustom-fixsi=244 @gol
+-mcustom-floatis=245 @gol
+-mcustom-fcmpgts=246 @gol
+-mcustom-fcmples=249 @gol
+-mcustom-fcmpeqs=250 @gol
+-mcustom-fcmpnes=251 @gol
+-mcustom-fmuls=252 @gol
+-mcustom-fadds=253 @gol
+-mcustom-fsubs=254 @gol
+-mcustom-fdivs=255 @gol
+-fsingle-precision-constant}
+
+@option{-mcustom-fpu-cfg=fph2} is equivalent to:
+@gccoptlist{-mcustom-fabss=224 @gol
+-mcustom-fnegs=225 @gol
+-mcustom-fcmpnes=226 @gol
+-mcustom-fcmpeqs=227 @gol
+-mcustom-fcmpges=228 @gol
+-mcustom-fcmpgts=229 @gol
+-mcustom-fcmples=230 @gol
+-mcustom-fcmplts=231 @gol
+-mcustom-fmaxs=232 @gol
+-mcustom-fmins=233 @gol
+-mcustom-round=248 @gol
+-mcustom-fixsi=249 @gol
+-mcustom-floatis=250 @gol
+-mcustom-fsqrts=251 @gol
+-mcustom-fmuls=252 @gol
+-mcustom-fadds=253 @gol
+-mcustom-fsubs=254 @gol
+-mcustom-fdivs=255 @gol}
+
+Custom instruction assignments given by individual
+@option{-mcustom-@var{insn}=} options override those given by
+@option{-mcustom-fpu-cfg=}, regardless of the
+order of the options on the command line.
+
+Note that you can gain more local control over selection of a FPU
+configuration by using the @code{target("custom-fpu-cfg=@var{name}")}
+function attribute (@pxref{Function Attributes})
+or pragma (@pxref{Function Specific Option Pragmas}).
+
+The name @var{fph2} is an abbreviation for @emph{Nios II Floating Point
+Hardware 2 Component}.  Please note that the custom instructions enabled by
+@option{-mcustom-fmins=233} and @option{-mcustom-fmaxs=234} are only generated
+if @option{-ffinite-math-only} is specified.  The custom instruction enabled by
+@option{-mcustom-round=248} is only generated if @option{-fno-math-errno} is
+specified.  In contrast to the other configurations,
+@option{-fsingle-precision-constant} is not set.
+
+@end table
+
+These additional @samp{-m} options are available for the Altera Nios II
+ELF (bare-metal) target:
+
+@table @gcctabopt
+
+@item -mhal
+@opindex mhal
+Link with HAL BSP.  This suppresses linking with the GCC-provided C runtime
+startup and termination code, and is typically used in conjunction with
+@option{-msys-crt0=} to specify the location of the alternate startup code
+provided by the HAL BSP.
+
+@item -msmallc
+@opindex msmallc
+Link with a limited version of the C library, @option{-lsmallc}, rather than
+Newlib.
+
+@item -msys-crt0=@var{startfile}
+@opindex msys-crt0
+@var{startfile} is the file name of the startfile (crt0) to use 
+when linking.  This option is only useful in conjunction with @option{-mhal}.
+
+@item -msys-lib=@var{systemlib}
+@opindex msys-lib
+@var{systemlib} is the library name of the library that provides
+low-level system calls required by the C library,
+e.g.@: @code{read} and @code{write}.
+This option is typically used to link with a library provided by a HAL BSP.
+
+@end table
+
+@node Nvidia PTX Options
+@subsection Nvidia PTX Options
+@cindex Nvidia PTX options
+@cindex nvptx options
+
+These options are defined for Nvidia PTX:
+
+@table @gcctabopt
+
+@item -m64
+@opindex m64
+Ignored, but preserved for backward compatibility.  Only 64-bit ABI is
+supported.
+
+@item -march=@var{architecture-string}
+@opindex march
+Generate code for the specified PTX ISA target architecture
+(e.g.@: @samp{sm_35}).  Valid architecture strings are @samp{sm_30},
+@samp{sm_35}, @samp{sm_53}, @samp{sm_70}, @samp{sm_75} and
+@samp{sm_80}.
+The default depends on how the compiler has been configured, see
+@option{--with-arch}.
+
+This option sets the value of the preprocessor macro
+@code{__PTX_SM__}; for instance, for @samp{sm_35}, it has the value
+@samp{350}.
+
+@item -misa=@var{architecture-string}
+@opindex misa
+Alias of @option{-march=}.
+
+@item -march-map=@var{architecture-string}
+@opindex march
+Select the closest available @option{-march=} value that is not more
+capable.  For instance, for @option{-march-map=sm_50} select
+@option{-march=sm_35}, and for @option{-march-map=sm_53} select
+@option{-march=sm_53}.
+
+@item -mptx=@var{version-string}
+@opindex mptx
+Generate code for the specified PTX ISA version (e.g.@: @samp{7.0}).
+Valid version strings include @samp{3.1}, @samp{6.0}, @samp{6.3}, and
+@samp{7.0}.  The default PTX ISA version is 6.0, unless a higher
+version is required for specified PTX ISA target architecture via
+option @option{-march=}.
+
+This option sets the values of the preprocessor macros
+@code{__PTX_ISA_VERSION_MAJOR__} and @code{__PTX_ISA_VERSION_MINOR__};
+for instance, for @samp{3.1} the macros have the values @samp{3} and
+@samp{1}, respectively.
+
+@item -mmainkernel
+@opindex mmainkernel
+Link in code for a __main kernel.  This is for stand-alone instead of
+offloading execution.
+
+@item -moptimize
+@opindex moptimize
+Apply partitioned execution optimizations.  This is the default when any
+level of optimization is selected.
+
+@item -msoft-stack
+@opindex msoft-stack
+Generate code that does not use @code{.local} memory
+directly for stack storage. Instead, a per-warp stack pointer is
+maintained explicitly. This enables variable-length stack allocation (with
+variable-length arrays or @code{alloca}), and when global memory is used for
+underlying storage, makes it possible to access automatic variables from other
+threads, or with atomic instructions. This code generation variant is used
+for OpenMP offloading, but the option is exposed on its own for the purpose
+of testing the compiler; to generate code suitable for linking into programs
+using OpenMP offloading, use option @option{-mgomp}.
+
+@item -muniform-simt
+@opindex muniform-simt
+Switch to code generation variant that allows to execute all threads in each
+warp, while maintaining memory state and side effects as if only one thread
+in each warp was active outside of OpenMP SIMD regions.  All atomic operations
+and calls to runtime (malloc, free, vprintf) are conditionally executed (iff
+current lane index equals the master lane index), and the register being
+assigned is copied via a shuffle instruction from the master lane.  Outside of
+SIMD regions lane 0 is the master; inside, each thread sees itself as the
+master.  Shared memory array @code{int __nvptx_uni[]} stores all-zeros or
+all-ones bitmasks for each warp, indicating current mode (0 outside of SIMD
+regions).  Each thread can bitwise-and the bitmask at position @code{tid.y}
+with current lane index to compute the master lane index.
+
+@item -mgomp
+@opindex mgomp
+Generate code for use in OpenMP offloading: enables @option{-msoft-stack} and
+@option{-muniform-simt} options, and selects corresponding multilib variant.
+
+@end table
+
+@node OpenRISC Options
+@subsection OpenRISC Options
+@cindex OpenRISC Options
+
+These options are defined for OpenRISC:
+
+@table @gcctabopt
+
+@item -mboard=@var{name}
+@opindex mboard
+Configure a board specific runtime.  This will be passed to the linker for
+newlib board library linking.  The default is @code{or1ksim}.
+
+@item -mnewlib
+@opindex mnewlib
+This option is ignored; it is for compatibility purposes only.  This used to
+select linker and preprocessor options for use with newlib.
+
+@item -msoft-div
+@itemx -mhard-div
+@opindex msoft-div
+@opindex mhard-div
+Select software or hardware divide (@code{l.div}, @code{l.divu}) instructions.
+This default is hardware divide.
+
+@item -msoft-mul
+@itemx -mhard-mul
+@opindex msoft-mul
+@opindex mhard-mul
+Select software or hardware multiply (@code{l.mul}, @code{l.muli}) instructions.
+This default is hardware multiply.
+
+@item -msoft-float
+@itemx -mhard-float
+@opindex msoft-float
+@opindex mhard-float
+Select software or hardware for floating point operations.
+The default is software.
+
+@item -mdouble-float
+@opindex mdouble-float
+When @option{-mhard-float} is selected, enables generation of double-precision
+floating point instructions.  By default functions from @file{libgcc} are used
+to perform double-precision floating point operations.
+
+@item -munordered-float
+@opindex munordered-float
+When @option{-mhard-float} is selected, enables generation of unordered
+floating point compare and set flag (@code{lf.sfun*}) instructions.  By default
+functions from @file{libgcc} are used to perform unordered floating point
+compare and set flag operations.
+
+@item -mcmov
+@opindex mcmov
+Enable generation of conditional move (@code{l.cmov}) instructions.  By
+default the equivalent will be generated using set and branch.
+
+@item -mror
+@opindex mror
+Enable generation of rotate right (@code{l.ror}) instructions.  By default
+functions from @file{libgcc} are used to perform rotate right operations.
+
+@item -mrori
+@opindex mrori
+Enable generation of rotate right with immediate (@code{l.rori}) instructions.
+By default functions from @file{libgcc} are used to perform rotate right with
+immediate operations.
+
+@item -msext
+@opindex msext
+Enable generation of sign extension (@code{l.ext*}) instructions.  By default
+memory loads are used to perform sign extension.
+
+@item -msfimm
+@opindex msfimm
+Enable generation of compare and set flag with immediate (@code{l.sf*i})
+instructions.  By default extra instructions will be generated to store the
+immediate to a register first.
+
+@item -mshftimm
+@opindex mshftimm
+Enable generation of shift with immediate (@code{l.srai}, @code{l.srli},
+@code{l.slli}) instructions.  By default extra instructions will be generated
+to store the immediate to a register first.
+
+@item -mcmodel=small
+@opindex mcmodel=small
+Generate OpenRISC code for the small model: The GOT is limited to 64k. This is
+the default model.
+
+@item -mcmodel=large
+@opindex mcmodel=large
+Generate OpenRISC code for the large model: The GOT may grow up to 4G in size.
+
+
+@end table
+
+@node PDP-11 Options
+@subsection PDP-11 Options
+@cindex PDP-11 Options
+
+These options are defined for the PDP-11:
+
+@table @gcctabopt
+@item -mfpu
+@opindex mfpu
+Use hardware FPP floating point.  This is the default.  (FIS floating
+point on the PDP-11/40 is not supported.)  Implies -m45.
+
+@item -msoft-float
+@opindex msoft-float
+Do not use hardware floating point.
+
+@item -mac0
+@opindex mac0
+Return floating-point results in ac0 (fr0 in Unix assembler syntax).
+
+@item -mno-ac0
+@opindex mno-ac0
+Return floating-point results in memory.  This is the default.
+
+@item -m40
+@opindex m40
+Generate code for a PDP-11/40.  Implies -msoft-float -mno-split.
+
+@item -m45
+@opindex m45
+Generate code for a PDP-11/45.  This is the default.
+
+@item -m10
+@opindex m10
+Generate code for a PDP-11/10.  Implies -msoft-float -mno-split.
+
+@item -mint16
+@itemx -mno-int32
+@opindex mint16
+@opindex mno-int32
+Use 16-bit @code{int}.  This is the default.
+
+@item -mint32
+@itemx -mno-int16
+@opindex mint32
+@opindex mno-int16
+Use 32-bit @code{int}.
+
+@item -msplit
+@opindex msplit
+Target has split instruction and data space.  Implies -m45.
+
+@item -munix-asm
+@opindex munix-asm
+Use Unix assembler syntax.
+
+@item -mdec-asm
+@opindex mdec-asm
+Use DEC assembler syntax.
+
+@item -mgnu-asm
+@opindex mgnu-asm
+Use GNU assembler syntax.  This is the default.
+
+@item -mlra
+@opindex mlra
+Use the new LRA register allocator.  By default, the old ``reload''
+allocator is used.
+@end table
+
+@node picoChip Options
+@subsection picoChip Options
+@cindex picoChip options
+
+These @samp{-m} options are defined for picoChip implementations:
+
+@table @gcctabopt
+
+@item -mae=@var{ae_type}
+@opindex mcpu
+Set the instruction set, register set, and instruction scheduling
+parameters for array element type @var{ae_type}.  Supported values
+for @var{ae_type} are @samp{ANY}, @samp{MUL}, and @samp{MAC}.
+
+@option{-mae=ANY} selects a completely generic AE type.  Code
+generated with this option runs on any of the other AE types.  The
+code is not as efficient as it would be if compiled for a specific
+AE type, and some types of operation (e.g., multiplication) do not
+work properly on all types of AE.
+
+@option{-mae=MUL} selects a MUL AE type.  This is the most useful AE type
+for compiled code, and is the default.
+
+@option{-mae=MAC} selects a DSP-style MAC AE.  Code compiled with this
+option may suffer from poor performance of byte (char) manipulation,
+since the DSP AE does not provide hardware support for byte load/stores.
+
+@item -msymbol-as-address
+Enable the compiler to directly use a symbol name as an address in a
+load/store instruction, without first loading it into a
+register.  Typically, the use of this option generates larger
+programs, which run faster than when the option isn't used.  However, the
+results vary from program to program, so it is left as a user option,
+rather than being permanently enabled.
+
+@item -mno-inefficient-warnings
+Disables warnings about the generation of inefficient code.  These
+warnings can be generated, for example, when compiling code that
+performs byte-level memory operations on the MAC AE type.  The MAC AE has
+no hardware support for byte-level memory operations, so all byte
+load/stores must be synthesized from word load/store operations.  This is
+inefficient and a warning is generated to indicate
+that you should rewrite the code to avoid byte operations, or to target
+an AE type that has the necessary hardware support.  This option disables
+these warnings.
+
+@end table
+
+@node PowerPC Options
+@subsection PowerPC Options
+@cindex PowerPC options
+
+These are listed under @xref{RS/6000 and PowerPC Options}.
+
+@node PRU Options
+@subsection PRU Options
+@cindex PRU Options
+
+These command-line options are defined for PRU target:
+
+@table @gcctabopt
+@item -minrt
+@opindex minrt
+Link with a minimum runtime environment, with no support for static
+initializers and constructors.  Using this option can significantly reduce
+the size of the final ELF binary.  Beware that the compiler could still
+generate code with static initializers and constructors.  It is up to the
+programmer to ensure that the source program will not use those features.
+
+@item -mmcu=@var{mcu}
+@opindex mmcu
+Specify the PRU MCU variant to use.  Check Newlib for the exact list of
+supported MCUs.
+
+@item -mno-relax
+@opindex mno-relax
+Make GCC pass the @option{--no-relax} command-line option to the linker
+instead of the @option{--relax} option.
+
+@item -mloop
+@opindex mloop
+Allow (or do not allow) GCC to use the LOOP instruction.
+
+@item -mabi=@var{variant}
+@opindex mabi
+Specify the ABI variant to output code for.  @option{-mabi=ti} selects the
+unmodified TI ABI while @option{-mabi=gnu} selects a GNU variant that copes
+more naturally with certain GCC assumptions.  These are the differences:
+
+@table @samp
+@item Function Pointer Size
+TI ABI specifies that function (code) pointers are 16-bit, whereas GNU
+supports only 32-bit data and code pointers.
+
+@item Optional Return Value Pointer
+Function return values larger than 64 bits are passed by using a hidden
+pointer as the first argument of the function.  TI ABI, though, mandates that
+the pointer can be NULL in case the caller is not using the returned value.
+GNU always passes and expects a valid return value pointer.
+
+@end table
+
+The current @option{-mabi=ti} implementation simply raises a compile error
+when any of the above code constructs is detected.  As a consequence
+the standard C library cannot be built and it is omitted when linking with
+@option{-mabi=ti}.
+
+Relaxation is a GNU feature and for safety reasons is disabled when using
+@option{-mabi=ti}.  The TI toolchain does not emit relocations for QBBx
+instructions, so the GNU linker cannot adjust them when shortening adjacent
+LDI32 pseudo instructions.
+
+@end table
+
+@node RISC-V Options
+@subsection RISC-V Options
+@cindex RISC-V Options
+
+These command-line options are defined for RISC-V targets:
+
+@table @gcctabopt
+@item -mbranch-cost=@var{n}
+@opindex mbranch-cost
+Set the cost of branches to roughly @var{n} instructions.
+
+@item -mplt
+@itemx -mno-plt
+@opindex plt
+When generating PIC code, do or don't allow the use of PLTs. Ignored for
+non-PIC.  The default is @option{-mplt}.
+
+@item -mabi=@var{ABI-string}
+@opindex mabi
+Specify integer and floating-point calling convention.  @var{ABI-string}
+contains two parts: the size of integer types and the registers used for
+floating-point types.  For example @samp{-march=rv64ifd -mabi=lp64d} means that
+@samp{long} and pointers are 64-bit (implicitly defining @samp{int} to be
+32-bit), and that floating-point values up to 64 bits wide are passed in F
+registers.  Contrast this with @samp{-march=rv64ifd -mabi=lp64f}, which still
+allows the compiler to generate code that uses the F and D extensions but only
+allows floating-point values up to 32 bits long to be passed in registers; or
+@samp{-march=rv64ifd -mabi=lp64}, in which no floating-point arguments will be
+passed in registers.
+
+The default for this argument is system dependent, users who want a specific
+calling convention should specify one explicitly.  The valid calling
+conventions are: @samp{ilp32}, @samp{ilp32f}, @samp{ilp32d}, @samp{lp64},
+@samp{lp64f}, and @samp{lp64d}.  Some calling conventions are impossible to
+implement on some ISAs: for example, @samp{-march=rv32if -mabi=ilp32d} is
+invalid because the ABI requires 64-bit values be passed in F registers, but F
+registers are only 32 bits wide.  There is also the @samp{ilp32e} ABI that can
+only be used with the @samp{rv32e} architecture.  This ABI is not well
+specified at present, and is subject to change.
+
+@item -mfdiv
+@itemx -mno-fdiv
+@opindex mfdiv
+Do or don't use hardware floating-point divide and square root instructions.
+This requires the F or D extensions for floating-point registers.  The default
+is to use them if the specified architecture has these instructions.
+
+@item -mdiv
+@itemx -mno-div
+@opindex mdiv
+Do or don't use hardware instructions for integer division.  This requires the
+M extension.  The default is to use them if the specified architecture has
+these instructions.
+
+@item -misa-spec=@var{ISA-spec-string}
+@opindex misa-spec
+Specify the version of the RISC-V Unprivileged (formerly User-Level)
+ISA specification to produce code conforming to.  The possibilities
+for @var{ISA-spec-string} are:
+@table @code
+@item 2.2
+Produce code conforming to version 2.2.
+@item 20190608
+Produce code conforming to version 20190608.
+@item 20191213
+Produce code conforming to version 20191213.
+@end table
+The default is @option{-misa-spec=20191213} unless GCC has been configured
+with @option{--with-isa-spec=} specifying a different default version.
+
+@item -march=@var{ISA-string}
+@opindex march
+Generate code for given RISC-V ISA (e.g.@: @samp{rv64im}).  ISA strings must be
+lower-case.  Examples include @samp{rv64i}, @samp{rv32g}, @samp{rv32e}, and
+@samp{rv32imaf}.
+
+When @option{-march=} is not specified, use the setting from @option{-mcpu}.
+
+If both @option{-march} and @option{-mcpu=} are not specified, the default for
+this argument is system dependent, users who want a specific architecture
+extensions should specify one explicitly.
+
+@item -mcpu=@var{processor-string}
+@opindex mcpu
+Use architecture of and optimize the output for the given processor, specified
+by particular CPU name.
+Permissible values for this option are: @samp{sifive-e20}, @samp{sifive-e21},
+@samp{sifive-e24}, @samp{sifive-e31}, @samp{sifive-e34}, @samp{sifive-e76},
+@samp{sifive-s21}, @samp{sifive-s51}, @samp{sifive-s54}, @samp{sifive-s76},
+@samp{sifive-u54}, and @samp{sifive-u74}.
+
+@item -mtune=@var{processor-string}
+@opindex mtune
+Optimize the output for the given processor, specified by microarchitecture or
+particular CPU name.  Permissible values for this option are: @samp{rocket},
+@samp{sifive-3-series}, @samp{sifive-5-series}, @samp{sifive-7-series},
+@samp{thead-c906}, @samp{size}, and all valid options for @option{-mcpu=}.
+
+When @option{-mtune=} is not specified, use the setting from @option{-mcpu},
+the default is @samp{rocket} if both are not specified.
+
+The @samp{size} choice is not intended for use by end-users.  This is used
+when @option{-Os} is specified.  It overrides the instruction cost info
+provided by @option{-mtune=}, but does not override the pipeline info.  This
+helps reduce code size while still giving good performance.
+
+@item -mpreferred-stack-boundary=@var{num}
+@opindex mpreferred-stack-boundary
+Attempt to keep the stack boundary aligned to a 2 raised to @var{num}
+byte boundary.  If @option{-mpreferred-stack-boundary} is not specified,
+the default is 4 (16 bytes or 128-bits).
+
+@strong{Warning:} If you use this switch, then you must build all modules with
+the same value, including any libraries.  This includes the system libraries
+and startup modules.
+
+@item -msmall-data-limit=@var{n}
+@opindex msmall-data-limit
+Put global and static data smaller than @var{n} bytes into a special section
+(on some targets).
+
+@item -msave-restore
+@itemx -mno-save-restore
+@opindex msave-restore
+Do or don't use smaller but slower prologue and epilogue code that uses
+library function calls.  The default is to use fast inline prologues and
+epilogues.
+
+@item -mshorten-memrefs
+@itemx -mno-shorten-memrefs
+@opindex mshorten-memrefs
+Do or do not attempt to make more use of compressed load/store instructions by
+replacing a load/store of 'base register + large offset' with a new load/store
+of 'new base + small offset'.  If the new base gets stored in a compressed
+register, then the new load/store can be compressed.  Currently targets 32-bit
+integer load/stores only.
+
+@item -mstrict-align
+@itemx -mno-strict-align
+@opindex mstrict-align
+Do not or do generate unaligned memory accesses.  The default is set depending
+on whether the processor we are optimizing for supports fast unaligned access
+or not.
+
+@item -mcmodel=medlow
+@opindex mcmodel=medlow
+Generate code for the medium-low code model. The program and its statically
+defined symbols must lie within a single 2 GiB address range and must lie
+between absolute addresses @minus{}2 GiB and +2 GiB. Programs can be
+statically or dynamically linked. This is the default code model.
+
+@item -mcmodel=medany
+@opindex mcmodel=medany
+Generate code for the medium-any code model. The program and its statically
+defined symbols must be within any single 2 GiB address range. Programs can be
+statically or dynamically linked.
+
+The code generated by the medium-any code model is position-independent, but is
+not guaranteed to function correctly when linked into position-independent
+executables or libraries.
+
+@item -mexplicit-relocs
+@itemx -mno-exlicit-relocs
+Use or do not use assembler relocation operators when dealing with symbolic
+addresses.  The alternative is to use assembler macros instead, which may
+limit optimization.
+
+@item -mrelax
+@itemx -mno-relax
+@opindex mrelax
+Take advantage of linker relaxations to reduce the number of instructions
+required to materialize symbol addresses. The default is to take advantage of
+linker relaxations.
+
+@item -mriscv-attribute
+@itemx -mno-riscv-attribute
+@opindex mriscv-attribute
+Emit (do not emit) RISC-V attribute to record extra information into ELF
+objects.  This feature requires at least binutils 2.32.
+
+@item -mcsr-check
+@itemx -mno-csr-check
+@opindex mcsr-check
+Enables or disables the CSR checking.
+
+@item -malign-data=@var{type}
+@opindex malign-data
+Control how GCC aligns variables and constants of array, structure, or union
+types.  Supported values for @var{type} are @samp{xlen} which uses x register
+width as the alignment value, and @samp{natural} which uses natural alignment.
+@samp{xlen} is the default.
+
+@item -mbig-endian
+@opindex mbig-endian
+Generate big-endian code.  This is the default when GCC is configured for a
+@samp{riscv64be-*-*} or @samp{riscv32be-*-*} target.
+
+@item -mlittle-endian
+@opindex mlittle-endian
+Generate little-endian code.  This is the default when GCC is configured for a
+@samp{riscv64-*-*} or @samp{riscv32-*-*} but not a @samp{riscv64be-*-*} or
+@samp{riscv32be-*-*} target.
+
+@item -mstack-protector-guard=@var{guard}
+@itemx -mstack-protector-guard-reg=@var{reg}
+@itemx -mstack-protector-guard-offset=@var{offset}
+@opindex mstack-protector-guard
+@opindex mstack-protector-guard-reg
+@opindex mstack-protector-guard-offset
+Generate stack protection code using canary at @var{guard}.  Supported
+locations are @samp{global} for a global canary or @samp{tls} for per-thread
+canary in the TLS block.
+
+With the latter choice the options
+@option{-mstack-protector-guard-reg=@var{reg}} and
+@option{-mstack-protector-guard-offset=@var{offset}} furthermore specify
+which register to use as base register for reading the canary,
+and from what offset from that base register. There is no default
+register or offset as this is entirely for use within the Linux
+kernel.
+@end table
+
+@node RL78 Options
+@subsection RL78 Options
+@cindex RL78 Options
+
+@table @gcctabopt
+
+@item -msim
+@opindex msim
+Links in additional target libraries to support operation within a
+simulator.
+
+@item -mmul=none
+@itemx -mmul=g10
+@itemx -mmul=g13
+@itemx -mmul=g14
+@itemx -mmul=rl78
+@opindex mmul
+Specifies the type of hardware multiplication and division support to
+be used.  The simplest is @code{none}, which uses software for both
+multiplication and division.  This is the default.  The @code{g13}
+value is for the hardware multiply/divide peripheral found on the
+RL78/G13 (S2 core) targets.  The @code{g14} value selects the use of
+the multiplication and division instructions supported by the RL78/G14
+(S3 core) parts.  The value @code{rl78} is an alias for @code{g14} and
+the value @code{mg10} is an alias for @code{none}.
+
+In addition a C preprocessor macro is defined, based upon the setting
+of this option.  Possible values are: @code{__RL78_MUL_NONE__},
+@code{__RL78_MUL_G13__} or @code{__RL78_MUL_G14__}.
+
+@item -mcpu=g10
+@itemx -mcpu=g13
+@itemx -mcpu=g14
+@itemx -mcpu=rl78
+@opindex mcpu
+Specifies the RL78 core to target.  The default is the G14 core, also
+known as an S3 core or just RL78.  The G13 or S2 core does not have
+multiply or divide instructions, instead it uses a hardware peripheral
+for these operations.  The G10 or S1 core does not have register
+banks, so it uses a different calling convention.
+
+If this option is set it also selects the type of hardware multiply
+support to use, unless this is overridden by an explicit
+@option{-mmul=none} option on the command line.  Thus specifying
+@option{-mcpu=g13} enables the use of the G13 hardware multiply
+peripheral and specifying @option{-mcpu=g10} disables the use of
+hardware multiplications altogether.
+
+Note, although the RL78/G14 core is the default target, specifying
+@option{-mcpu=g14} or @option{-mcpu=rl78} on the command line does
+change the behavior of the toolchain since it also enables G14
+hardware multiply support.  If these options are not specified on the
+command line then software multiplication routines will be used even
+though the code targets the RL78 core.  This is for backwards
+compatibility with older toolchains which did not have hardware
+multiply and divide support.
+
+In addition a C preprocessor macro is defined, based upon the setting
+of this option.  Possible values are: @code{__RL78_G10__},
+@code{__RL78_G13__} or @code{__RL78_G14__}.
+
+@item -mg10
+@itemx -mg13
+@itemx -mg14
+@itemx -mrl78
+@opindex mg10
+@opindex mg13
+@opindex mg14
+@opindex mrl78
+These are aliases for the corresponding @option{-mcpu=} option.  They
+are provided for backwards compatibility.
+
+@item -mallregs
+@opindex mallregs
+Allow the compiler to use all of the available registers.  By default
+registers @code{r24..r31} are reserved for use in interrupt handlers.
+With this option enabled these registers can be used in ordinary
+functions as well.
+
+@item -m64bit-doubles
+@itemx -m32bit-doubles
+@opindex m64bit-doubles
+@opindex m32bit-doubles
+Make the @code{double} data type be 64 bits (@option{-m64bit-doubles})
+or 32 bits (@option{-m32bit-doubles}) in size.  The default is
+@option{-m32bit-doubles}.
+
+@item -msave-mduc-in-interrupts
+@itemx -mno-save-mduc-in-interrupts
+@opindex msave-mduc-in-interrupts
+@opindex mno-save-mduc-in-interrupts
+Specifies that interrupt handler functions should preserve the
+MDUC registers.  This is only necessary if normal code might use
+the MDUC registers, for example because it performs multiplication
+and division operations.  The default is to ignore the MDUC registers
+as this makes the interrupt handlers faster.  The target option -mg13
+needs to be passed for this to work as this feature is only available
+on the G13 target (S2 core).  The MDUC registers will only be saved
+if the interrupt handler performs a multiplication or division
+operation or it calls another function.
+
+@end table
+
+@node RS/6000 and PowerPC Options
+@subsection IBM RS/6000 and PowerPC Options
+@cindex RS/6000 and PowerPC Options
+@cindex IBM RS/6000 and PowerPC Options
+
+These @samp{-m} options are defined for the IBM RS/6000 and PowerPC:
+@table @gcctabopt
+@item -mpowerpc-gpopt
+@itemx -mno-powerpc-gpopt
+@itemx -mpowerpc-gfxopt
+@itemx -mno-powerpc-gfxopt
+@need 800
+@itemx -mpowerpc64
+@itemx -mno-powerpc64
+@itemx -mmfcrf
+@itemx -mno-mfcrf
+@itemx -mpopcntb
+@itemx -mno-popcntb
+@itemx -mpopcntd
+@itemx -mno-popcntd
+@itemx -mfprnd
+@itemx -mno-fprnd
+@need 800
+@itemx -mcmpb
+@itemx -mno-cmpb
+@itemx -mhard-dfp
+@itemx -mno-hard-dfp
+@opindex mpowerpc-gpopt
+@opindex mno-powerpc-gpopt
+@opindex mpowerpc-gfxopt
+@opindex mno-powerpc-gfxopt
+@opindex mpowerpc64
+@opindex mno-powerpc64
+@opindex mmfcrf
+@opindex mno-mfcrf
+@opindex mpopcntb
+@opindex mno-popcntb
+@opindex mpopcntd
+@opindex mno-popcntd
+@opindex mfprnd
+@opindex mno-fprnd
+@opindex mcmpb
+@opindex mno-cmpb
+@opindex mhard-dfp
+@opindex mno-hard-dfp
+You use these options to specify which instructions are available on the
+processor you are using.  The default value of these options is
+determined when configuring GCC@.  Specifying the
+@option{-mcpu=@var{cpu_type}} overrides the specification of these
+options.  We recommend you use the @option{-mcpu=@var{cpu_type}} option
+rather than the options listed above.
+
+Specifying @option{-mpowerpc-gpopt} allows
+GCC to use the optional PowerPC architecture instructions in the
+General Purpose group, including floating-point square root.  Specifying
+@option{-mpowerpc-gfxopt} allows GCC to
+use the optional PowerPC architecture instructions in the Graphics
+group, including floating-point select.
+
+The @option{-mmfcrf} option allows GCC to generate the move from
+condition register field instruction implemented on the POWER4
+processor and other processors that support the PowerPC V2.01
+architecture.
+The @option{-mpopcntb} option allows GCC to generate the popcount and
+double-precision FP reciprocal estimate instruction implemented on the
+POWER5 processor and other processors that support the PowerPC V2.02
+architecture.
+The @option{-mpopcntd} option allows GCC to generate the popcount
+instruction implemented on the POWER7 processor and other processors
+that support the PowerPC V2.06 architecture.
+The @option{-mfprnd} option allows GCC to generate the FP round to
+integer instructions implemented on the POWER5+ processor and other
+processors that support the PowerPC V2.03 architecture.
+The @option{-mcmpb} option allows GCC to generate the compare bytes
+instruction implemented on the POWER6 processor and other processors
+that support the PowerPC V2.05 architecture.
+The @option{-mhard-dfp} option allows GCC to generate the decimal
+floating-point instructions implemented on some POWER processors.
+
+The @option{-mpowerpc64} option allows GCC to generate the additional
+64-bit instructions that are found in the full PowerPC64 architecture
+and to treat GPRs as 64-bit, doubleword quantities.  GCC defaults to
+@option{-mno-powerpc64}.
+
+@item -mcpu=@var{cpu_type}
+@opindex mcpu
+Set architecture type, register usage, and
+instruction scheduling parameters for machine type @var{cpu_type}.
+Supported values for @var{cpu_type} are @samp{401}, @samp{403},
+@samp{405}, @samp{405fp}, @samp{440}, @samp{440fp}, @samp{464}, @samp{464fp},
+@samp{476}, @samp{476fp}, @samp{505}, @samp{601}, @samp{602}, @samp{603},
+@samp{603e}, @samp{604}, @samp{604e}, @samp{620}, @samp{630}, @samp{740},
+@samp{7400}, @samp{7450}, @samp{750}, @samp{801}, @samp{821}, @samp{823},
+@samp{860}, @samp{970}, @samp{8540}, @samp{a2}, @samp{e300c2},
+@samp{e300c3}, @samp{e500mc}, @samp{e500mc64}, @samp{e5500},
+@samp{e6500}, @samp{ec603e}, @samp{G3}, @samp{G4}, @samp{G5},
+@samp{titan}, @samp{power3}, @samp{power4}, @samp{power5}, @samp{power5+},
+@samp{power6}, @samp{power6x}, @samp{power7}, @samp{power8},
+@samp{power9}, @samp{power10}, @samp{powerpc}, @samp{powerpc64},
+@samp{powerpc64le}, @samp{rs64}, and @samp{native}.
+
+@option{-mcpu=powerpc}, @option{-mcpu=powerpc64}, and
+@option{-mcpu=powerpc64le} specify pure 32-bit PowerPC (either
+endian), 64-bit big endian PowerPC and 64-bit little endian PowerPC
+architecture machine types, with an appropriate, generic processor
+model assumed for scheduling purposes.
+
+Specifying @samp{native} as cpu type detects and selects the
+architecture option that corresponds to the host processor of the
+system performing the compilation.
+@option{-mcpu=native} has no effect if GCC does not recognize the
+processor.
+
+The other options specify a specific processor.  Code generated under
+those options runs best on that processor, and may not run at all on
+others.
+
+The @option{-mcpu} options automatically enable or disable the
+following options:
+
+@gccoptlist{-maltivec  -mfprnd  -mhard-float  -mmfcrf  -mmultiple @gol
+-mpopcntb  -mpopcntd  -mpowerpc64 @gol
+-mpowerpc-gpopt  -mpowerpc-gfxopt @gol
+-mmulhw  -mdlmzb  -mmfpgpr  -mvsx @gol
+-mcrypto  -mhtm  -mpower8-fusion  -mpower8-vector @gol
+-mquad-memory  -mquad-memory-atomic  -mfloat128 @gol
+-mfloat128-hardware -mprefixed -mpcrel -mmma @gol
+-mrop-protect}
+
+The particular options set for any particular CPU varies between
+compiler versions, depending on what setting seems to produce optimal
+code for that CPU; it doesn't necessarily reflect the actual hardware's
+capabilities.  If you wish to set an individual option to a particular
+value, you may specify it after the @option{-mcpu} option, like
+@option{-mcpu=970 -mno-altivec}.
+
+On AIX, the @option{-maltivec} and @option{-mpowerpc64} options are
+not enabled or disabled by the @option{-mcpu} option at present because
+AIX does not have full support for these options.  You may still
+enable or disable them individually if you're sure it'll work in your
+environment.
+
+@item -mtune=@var{cpu_type}
+@opindex mtune
+Set the instruction scheduling parameters for machine type
+@var{cpu_type}, but do not set the architecture type or register usage,
+as @option{-mcpu=@var{cpu_type}} does.  The same
+values for @var{cpu_type} are used for @option{-mtune} as for
+@option{-mcpu}.  If both are specified, the code generated uses the
+architecture and registers set by @option{-mcpu}, but the
+scheduling parameters set by @option{-mtune}.
+
+@item -mcmodel=small
+@opindex mcmodel=small
+Generate PowerPC64 code for the small model: The TOC is limited to
+64k.
+
+@item -mcmodel=medium
+@opindex mcmodel=medium
+Generate PowerPC64 code for the medium model: The TOC and other static
+data may be up to a total of 4G in size.  This is the default for 64-bit
+Linux.
+
+@item -mcmodel=large
+@opindex mcmodel=large
+Generate PowerPC64 code for the large model: The TOC may be up to 4G
+in size.  Other data and code is only limited by the 64-bit address
+space.
+
+@item -maltivec
+@itemx -mno-altivec
+@opindex maltivec
+@opindex mno-altivec
+Generate code that uses (does not use) AltiVec instructions, and also
+enable the use of built-in functions that allow more direct access to
+the AltiVec instruction set.  You may also need to set
+@option{-mabi=altivec} to adjust the current ABI with AltiVec ABI
+enhancements.
+
+When @option{-maltivec} is used, the element order for AltiVec intrinsics
+such as @code{vec_splat}, @code{vec_extract}, and @code{vec_insert} 
+match array element order corresponding to the endianness of the
+target.  That is, element zero identifies the leftmost element in a
+vector register when targeting a big-endian platform, and identifies
+the rightmost element in a vector register when targeting a
+little-endian platform.
+
+@item -mvrsave
+@itemx -mno-vrsave
+@opindex mvrsave
+@opindex mno-vrsave
+Generate VRSAVE instructions when generating AltiVec code.
+
+@item -msecure-plt
+@opindex msecure-plt
+Generate code that allows @command{ld} and @command{ld.so}
+to build executables and shared
+libraries with non-executable @code{.plt} and @code{.got} sections.
+This is a PowerPC
+32-bit SYSV ABI option.
+
+@item -mbss-plt
+@opindex mbss-plt
+Generate code that uses a BSS @code{.plt} section that @command{ld.so}
+fills in, and
+requires @code{.plt} and @code{.got}
+sections that are both writable and executable.
+This is a PowerPC 32-bit SYSV ABI option.
+
+@item -misel
+@itemx -mno-isel
+@opindex misel
+@opindex mno-isel
+This switch enables or disables the generation of ISEL instructions.
+
+@item -mvsx
+@itemx -mno-vsx
+@opindex mvsx
+@opindex mno-vsx
+Generate code that uses (does not use) vector/scalar (VSX)
+instructions, and also enable the use of built-in functions that allow
+more direct access to the VSX instruction set.
+
+@item -mcrypto
+@itemx -mno-crypto
+@opindex mcrypto
+@opindex mno-crypto
+Enable the use (disable) of the built-in functions that allow direct
+access to the cryptographic instructions that were added in version
+2.07 of the PowerPC ISA.
+
+@item -mhtm
+@itemx -mno-htm
+@opindex mhtm
+@opindex mno-htm
+Enable (disable) the use of the built-in functions that allow direct
+access to the Hardware Transactional Memory (HTM) instructions that
+were added in version 2.07 of the PowerPC ISA.
+
+@item -mpower8-fusion
+@itemx -mno-power8-fusion
+@opindex mpower8-fusion
+@opindex mno-power8-fusion
+Generate code that keeps (does not keeps) some integer operations
+adjacent so that the instructions can be fused together on power8 and
+later processors.
+
+@item -mpower8-vector
+@itemx -mno-power8-vector
+@opindex mpower8-vector
+@opindex mno-power8-vector
+Generate code that uses (does not use) the vector and scalar
+instructions that were added in version 2.07 of the PowerPC ISA.  Also
+enable the use of built-in functions that allow more direct access to
+the vector instructions.
+
+@item -mquad-memory
+@itemx -mno-quad-memory
+@opindex mquad-memory
+@opindex mno-quad-memory
+Generate code that uses (does not use) the non-atomic quad word memory
+instructions.  The @option{-mquad-memory} option requires use of
+64-bit mode.
+
+@item -mquad-memory-atomic
+@itemx -mno-quad-memory-atomic
+@opindex mquad-memory-atomic
+@opindex mno-quad-memory-atomic
+Generate code that uses (does not use) the atomic quad word memory
+instructions.  The @option{-mquad-memory-atomic} option requires use of
+64-bit mode.
+
+@item -mfloat128
+@itemx -mno-float128
+@opindex mfloat128
+@opindex mno-float128
+Enable/disable the @var{__float128} keyword for IEEE 128-bit floating point
+and use either software emulation for IEEE 128-bit floating point or
+hardware instructions.
+
+The VSX instruction set (@option{-mvsx}) must be enabled to use the IEEE
+128-bit floating point support.  The IEEE 128-bit floating point is only
+supported on Linux.
+
+The default for @option{-mfloat128} is enabled on PowerPC Linux
+systems using the VSX instruction set, and disabled on other systems.
+
+If you use the ISA 3.0 instruction set (@option{-mpower9-vector} or
+@option{-mcpu=power9}) on a 64-bit system, the IEEE 128-bit floating
+point support will also enable the generation of ISA 3.0 IEEE 128-bit
+floating point instructions.  Otherwise, if you do not specify to
+generate ISA 3.0 instructions or you are targeting a 32-bit big endian
+system, IEEE 128-bit floating point will be done with software
+emulation.
+
+@item -mfloat128-hardware
+@itemx -mno-float128-hardware
+@opindex mfloat128-hardware
+@opindex mno-float128-hardware
+Enable/disable using ISA 3.0 hardware instructions to support the
+@var{__float128} data type.
+
+The default for @option{-mfloat128-hardware} is enabled on PowerPC
+Linux systems using the ISA 3.0 instruction set, and disabled on other
+systems.
+
+@item -m32
+@itemx -m64
+@opindex m32
+@opindex m64
+Generate code for 32-bit or 64-bit environments of Darwin and SVR4
+targets (including GNU/Linux).  The 32-bit environment sets int, long
+and pointer to 32 bits and generates code that runs on any PowerPC
+variant.  The 64-bit environment sets int to 32 bits and long and
+pointer to 64 bits, and generates code for PowerPC64, as for
+@option{-mpowerpc64}.
+
+@item -mfull-toc
+@itemx -mno-fp-in-toc
+@itemx -mno-sum-in-toc
+@itemx -mminimal-toc
+@opindex mfull-toc
+@opindex mno-fp-in-toc
+@opindex mno-sum-in-toc
+@opindex mminimal-toc
+Modify generation of the TOC (Table Of Contents), which is created for
+every executable file.  The @option{-mfull-toc} option is selected by
+default.  In that case, GCC allocates at least one TOC entry for
+each unique non-automatic variable reference in your program.  GCC
+also places floating-point constants in the TOC@.  However, only
+16,384 entries are available in the TOC@.
+
+If you receive a linker error message that saying you have overflowed
+the available TOC space, you can reduce the amount of TOC space used
+with the @option{-mno-fp-in-toc} and @option{-mno-sum-in-toc} options.
+@option{-mno-fp-in-toc} prevents GCC from putting floating-point
+constants in the TOC and @option{-mno-sum-in-toc} forces GCC to
+generate code to calculate the sum of an address and a constant at
+run time instead of putting that sum into the TOC@.  You may specify one
+or both of these options.  Each causes GCC to produce very slightly
+slower and larger code at the expense of conserving TOC space.
+
+If you still run out of space in the TOC even when you specify both of
+these options, specify @option{-mminimal-toc} instead.  This option causes
+GCC to make only one TOC entry for every file.  When you specify this
+option, GCC produces code that is slower and larger but which
+uses extremely little TOC space.  You may wish to use this option
+only on files that contain less frequently-executed code.
+
+@item -maix64
+@itemx -maix32
+@opindex maix64
+@opindex maix32
+Enable 64-bit AIX ABI and calling convention: 64-bit pointers, 64-bit
+@code{long} type, and the infrastructure needed to support them.
+Specifying @option{-maix64} implies @option{-mpowerpc64},
+while @option{-maix32} disables the 64-bit ABI and
+implies @option{-mno-powerpc64}.  GCC defaults to @option{-maix32}.
+
+@item -mxl-compat
+@itemx -mno-xl-compat
+@opindex mxl-compat
+@opindex mno-xl-compat
+Produce code that conforms more closely to IBM XL compiler semantics
+when using AIX-compatible ABI@.  Pass floating-point arguments to
+prototyped functions beyond the register save area (RSA) on the stack
+in addition to argument FPRs.  Do not assume that most significant
+double in 128-bit long double value is properly rounded when comparing
+values and converting to double.  Use XL symbol names for long double
+support routines.
+
+The AIX calling convention was extended but not initially documented to
+handle an obscure K&R C case of calling a function that takes the
+address of its arguments with fewer arguments than declared.  IBM XL
+compilers access floating-point arguments that do not fit in the
+RSA from the stack when a subroutine is compiled without
+optimization.  Because always storing floating-point arguments on the
+stack is inefficient and rarely needed, this option is not enabled by
+default and only is necessary when calling subroutines compiled by IBM
+XL compilers without optimization.
+
+@item -mpe
+@opindex mpe
+Support @dfn{IBM RS/6000 SP} @dfn{Parallel Environment} (PE)@.  Link an
+application written to use message passing with special startup code to
+enable the application to run.  The system must have PE installed in the
+standard location (@file{/usr/lpp/ppe.poe/}), or the @file{specs} file
+must be overridden with the @option{-specs=} option to specify the
+appropriate directory location.  The Parallel Environment does not
+support threads, so the @option{-mpe} option and the @option{-pthread}
+option are incompatible.
+
+@item -malign-natural
+@itemx -malign-power
+@opindex malign-natural
+@opindex malign-power
+On AIX, 32-bit Darwin, and 64-bit PowerPC GNU/Linux, the option
+@option{-malign-natural} overrides the ABI-defined alignment of larger
+types, such as floating-point doubles, on their natural size-based boundary.
+The option @option{-malign-power} instructs GCC to follow the ABI-specified
+alignment rules.  GCC defaults to the standard alignment defined in the ABI@.
+
+On 64-bit Darwin, natural alignment is the default, and @option{-malign-power}
+is not supported.
+
+@item -msoft-float
+@itemx -mhard-float
+@opindex msoft-float
+@opindex mhard-float
+Generate code that does not use (uses) the floating-point register set.
+Software floating-point emulation is provided if you use the
+@option{-msoft-float} option, and pass the option to GCC when linking.
+
+@item -mmultiple
+@itemx -mno-multiple
+@opindex mmultiple
+@opindex mno-multiple
+Generate code that uses (does not use) the load multiple word
+instructions and the store multiple word instructions.  These
+instructions are generated by default on POWER systems, and not
+generated on PowerPC systems.  Do not use @option{-mmultiple} on little-endian
+PowerPC systems, since those instructions do not work when the
+processor is in little-endian mode.  The exceptions are PPC740 and
+PPC750 which permit these instructions in little-endian mode.
+
+@item -mupdate
+@itemx -mno-update
+@opindex mupdate
+@opindex mno-update
+Generate code that uses (does not use) the load or store instructions
+that update the base register to the address of the calculated memory
+location.  These instructions are generated by default.  If you use
+@option{-mno-update}, there is a small window between the time that the
+stack pointer is updated and the address of the previous frame is
+stored, which means code that walks the stack frame across interrupts or
+signals may get corrupted data.
+
+@item -mavoid-indexed-addresses
+@itemx -mno-avoid-indexed-addresses
+@opindex mavoid-indexed-addresses
+@opindex mno-avoid-indexed-addresses
+Generate code that tries to avoid (not avoid) the use of indexed load
+or store instructions. These instructions can incur a performance
+penalty on Power6 processors in certain situations, such as when
+stepping through large arrays that cross a 16M boundary.  This option
+is enabled by default when targeting Power6 and disabled otherwise.
+
+@item -mfused-madd
+@itemx -mno-fused-madd
+@opindex mfused-madd
+@opindex mno-fused-madd
+Generate code that uses (does not use) the floating-point multiply and
+accumulate instructions.  These instructions are generated by default
+if hardware floating point is used.  The machine-dependent
+@option{-mfused-madd} option is now mapped to the machine-independent
+@option{-ffp-contract=fast} option, and @option{-mno-fused-madd} is
+mapped to @option{-ffp-contract=off}.
+
+@item -mmulhw
+@itemx -mno-mulhw
+@opindex mmulhw
+@opindex mno-mulhw
+Generate code that uses (does not use) the half-word multiply and
+multiply-accumulate instructions on the IBM 405, 440, 464 and 476 processors.
+These instructions are generated by default when targeting those
+processors.
+
+@item -mdlmzb
+@itemx -mno-dlmzb
+@opindex mdlmzb
+@opindex mno-dlmzb
+Generate code that uses (does not use) the string-search @samp{dlmzb}
+instruction on the IBM 405, 440, 464 and 476 processors.  This instruction is
+generated by default when targeting those processors.
+
+@item -mno-bit-align
+@itemx -mbit-align
+@opindex mno-bit-align
+@opindex mbit-align
+On System V.4 and embedded PowerPC systems do not (do) force structures
+and unions that contain bit-fields to be aligned to the base type of the
+bit-field.
+
+For example, by default a structure containing nothing but 8
+@code{unsigned} bit-fields of length 1 is aligned to a 4-byte
+boundary and has a size of 4 bytes.  By using @option{-mno-bit-align},
+the structure is aligned to a 1-byte boundary and is 1 byte in
+size.
+
+@item -mno-strict-align
+@itemx -mstrict-align
+@opindex mno-strict-align
+@opindex mstrict-align
+On System V.4 and embedded PowerPC systems do not (do) assume that
+unaligned memory references are handled by the system.
+
+@item -mrelocatable
+@itemx -mno-relocatable
+@opindex mrelocatable
+@opindex mno-relocatable
+Generate code that allows (does not allow) a static executable to be
+relocated to a different address at run time.  A simple embedded
+PowerPC system loader should relocate the entire contents of
+@code{.got2} and 4-byte locations listed in the @code{.fixup} section,
+a table of 32-bit addresses generated by this option.  For this to
+work, all objects linked together must be compiled with
+@option{-mrelocatable} or @option{-mrelocatable-lib}.
+@option{-mrelocatable} code aligns the stack to an 8-byte boundary.
+
+@item -mrelocatable-lib
+@itemx -mno-relocatable-lib
+@opindex mrelocatable-lib
+@opindex mno-relocatable-lib
+Like @option{-mrelocatable}, @option{-mrelocatable-lib} generates a
+@code{.fixup} section to allow static executables to be relocated at
+run time, but @option{-mrelocatable-lib} does not use the smaller stack
+alignment of @option{-mrelocatable}.  Objects compiled with
+@option{-mrelocatable-lib} may be linked with objects compiled with
+any combination of the @option{-mrelocatable} options.
+
+@item -mno-toc
+@itemx -mtoc
+@opindex mno-toc
+@opindex mtoc
+On System V.4 and embedded PowerPC systems do not (do) assume that
+register 2 contains a pointer to a global area pointing to the addresses
+used in the program.
+
+@item -mlittle
+@itemx -mlittle-endian
+@opindex mlittle
+@opindex mlittle-endian
+On System V.4 and embedded PowerPC systems compile code for the
+processor in little-endian mode.  The @option{-mlittle-endian} option is
+the same as @option{-mlittle}.
+
+@item -mbig
+@itemx -mbig-endian
+@opindex mbig
+@opindex mbig-endian
+On System V.4 and embedded PowerPC systems compile code for the
+processor in big-endian mode.  The @option{-mbig-endian} option is
+the same as @option{-mbig}.
+
+@item -mdynamic-no-pic
+@opindex mdynamic-no-pic
+On Darwin and Mac OS X systems, compile code so that it is not
+relocatable, but that its external references are relocatable.  The
+resulting code is suitable for applications, but not shared
+libraries.
+
+@item -msingle-pic-base
+@opindex msingle-pic-base
+Treat the register used for PIC addressing as read-only, rather than
+loading it in the prologue for each function.  The runtime system is
+responsible for initializing this register with an appropriate value
+before execution begins.
+
+@item -mprioritize-restricted-insns=@var{priority}
+@opindex mprioritize-restricted-insns
+This option controls the priority that is assigned to
+dispatch-slot restricted instructions during the second scheduling
+pass.  The argument @var{priority} takes the value @samp{0}, @samp{1},
+or @samp{2} to assign no, highest, or second-highest (respectively) 
+priority to dispatch-slot restricted
+instructions.
+
+@item -msched-costly-dep=@var{dependence_type}
+@opindex msched-costly-dep
+This option controls which dependences are considered costly
+by the target during instruction scheduling.  The argument
+@var{dependence_type} takes one of the following values:
+
+@table @asis
+@item @samp{no}
+No dependence is costly.
+
+@item @samp{all}
+All dependences are costly.
+
+@item @samp{true_store_to_load}
+A true dependence from store to load is costly.
+
+@item @samp{store_to_load}
+Any dependence from store to load is costly.
+
+@item @var{number}
+Any dependence for which the latency is greater than or equal to 
+@var{number} is costly.
+@end table
+
+@item -minsert-sched-nops=@var{scheme}
+@opindex minsert-sched-nops
+This option controls which NOP insertion scheme is used during
+the second scheduling pass.  The argument @var{scheme} takes one of the
+following values:
+
+@table @asis
+@item @samp{no}
+Don't insert NOPs.
+
+@item @samp{pad}
+Pad with NOPs any dispatch group that has vacant issue slots,
+according to the scheduler's grouping.
+
+@item @samp{regroup_exact}
+Insert NOPs to force costly dependent insns into
+separate groups.  Insert exactly as many NOPs as needed to force an insn
+to a new group, according to the estimated processor grouping.
+
+@item @var{number}
+Insert NOPs to force costly dependent insns into
+separate groups.  Insert @var{number} NOPs to force an insn to a new group.
+@end table
+
+@item -mcall-sysv
+@opindex mcall-sysv
+On System V.4 and embedded PowerPC systems compile code using calling
+conventions that adhere to the March 1995 draft of the System V
+Application Binary Interface, PowerPC processor supplement.  This is the
+default unless you configured GCC using @samp{powerpc-*-eabiaix}.
+
+@item -mcall-sysv-eabi
+@itemx -mcall-eabi
+@opindex mcall-sysv-eabi
+@opindex mcall-eabi
+Specify both @option{-mcall-sysv} and @option{-meabi} options.
+
+@item -mcall-sysv-noeabi
+@opindex mcall-sysv-noeabi
+Specify both @option{-mcall-sysv} and @option{-mno-eabi} options.
+
+@item -mcall-aixdesc
+@opindex m
+On System V.4 and embedded PowerPC systems compile code for the AIX
+operating system.
+
+@item -mcall-linux
+@opindex mcall-linux
+On System V.4 and embedded PowerPC systems compile code for the
+Linux-based GNU system.
+
+@item -mcall-freebsd
+@opindex mcall-freebsd
+On System V.4 and embedded PowerPC systems compile code for the
+FreeBSD operating system.
+
+@item -mcall-netbsd
+@opindex mcall-netbsd
+On System V.4 and embedded PowerPC systems compile code for the
+NetBSD operating system.
+
+@item -mcall-openbsd
+@opindex mcall-netbsd
+On System V.4 and embedded PowerPC systems compile code for the
+OpenBSD operating system.
+
+@item -mtraceback=@var{traceback_type}
+@opindex mtraceback
+Select the type of traceback table. Valid values for @var{traceback_type}
+are @samp{full}, @samp{part}, and @samp{no}.
+
+@item -maix-struct-return
+@opindex maix-struct-return
+Return all structures in memory (as specified by the AIX ABI)@.
+
+@item -msvr4-struct-return
+@opindex msvr4-struct-return
+Return structures smaller than 8 bytes in registers (as specified by the
+SVR4 ABI)@.
+
+@item -mabi=@var{abi-type}
+@opindex mabi
+Extend the current ABI with a particular extension, or remove such extension.
+Valid values are: @samp{altivec}, @samp{no-altivec},
+@samp{ibmlongdouble}, @samp{ieeelongdouble},
+@samp{elfv1}, @samp{elfv2},
+and for AIX: @samp{vec-extabi}, @samp{vec-default}@.
+
+@item -mabi=ibmlongdouble
+@opindex mabi=ibmlongdouble
+Change the current ABI to use IBM extended-precision long double.
+This is not likely to work if your system defaults to using IEEE
+extended-precision long double.  If you change the long double type
+from IEEE extended-precision, the compiler will issue a warning unless
+you use the @option{-Wno-psabi} option.  Requires @option{-mlong-double-128}
+to be enabled.
+
+@item -mabi=ieeelongdouble
+@opindex mabi=ieeelongdouble
+Change the current ABI to use IEEE extended-precision long double.
+This is not likely to work if your system defaults to using IBM
+extended-precision long double.  If you change the long double type
+from IBM extended-precision, the compiler will issue a warning unless
+you use the @option{-Wno-psabi} option.  Requires @option{-mlong-double-128}
+to be enabled.
+
+@item -mabi=elfv1
+@opindex mabi=elfv1
+Change the current ABI to use the ELFv1 ABI.
+This is the default ABI for big-endian PowerPC 64-bit Linux.
+Overriding the default ABI requires special system support and is
+likely to fail in spectacular ways.
+
+@item -mabi=elfv2
+@opindex mabi=elfv2
+Change the current ABI to use the ELFv2 ABI.
+This is the default ABI for little-endian PowerPC 64-bit Linux.
+Overriding the default ABI requires special system support and is
+likely to fail in spectacular ways.
+
+@item -mgnu-attribute
+@itemx -mno-gnu-attribute
+@opindex mgnu-attribute
+@opindex mno-gnu-attribute
+Emit .gnu_attribute assembly directives to set tag/value pairs in a
+.gnu.attributes section that specify ABI variations in function
+parameters or return values.
+
+@item -mprototype
+@itemx -mno-prototype
+@opindex mprototype
+@opindex mno-prototype
+On System V.4 and embedded PowerPC systems assume that all calls to
+variable argument functions are properly prototyped.  Otherwise, the
+compiler must insert an instruction before every non-prototyped call to
+set or clear bit 6 of the condition code register (@code{CR}) to
+indicate whether floating-point values are passed in the floating-point
+registers in case the function takes variable arguments.  With
+@option{-mprototype}, only calls to prototyped variable argument functions
+set or clear the bit.
+
+@item -msim
+@opindex msim
+On embedded PowerPC systems, assume that the startup module is called
+@file{sim-crt0.o} and that the standard C libraries are @file{libsim.a} and
+@file{libc.a}.  This is the default for @samp{powerpc-*-eabisim}
+configurations.
+
+@item -mmvme
+@opindex mmvme
+On embedded PowerPC systems, assume that the startup module is called
+@file{crt0.o} and the standard C libraries are @file{libmvme.a} and
+@file{libc.a}.
+
+@item -mads
+@opindex mads
+On embedded PowerPC systems, assume that the startup module is called
+@file{crt0.o} and the standard C libraries are @file{libads.a} and
+@file{libc.a}.
+
+@item -myellowknife
+@opindex myellowknife
+On embedded PowerPC systems, assume that the startup module is called
+@file{crt0.o} and the standard C libraries are @file{libyk.a} and
+@file{libc.a}.
+
+@item -mvxworks
+@opindex mvxworks
+On System V.4 and embedded PowerPC systems, specify that you are
+compiling for a VxWorks system.
+
+@item -memb
+@opindex memb
+On embedded PowerPC systems, set the @code{PPC_EMB} bit in the ELF flags
+header to indicate that @samp{eabi} extended relocations are used.
+
+@item -meabi
+@itemx -mno-eabi
+@opindex meabi
+@opindex mno-eabi
+On System V.4 and embedded PowerPC systems do (do not) adhere to the
+Embedded Applications Binary Interface (EABI), which is a set of
+modifications to the System V.4 specifications.  Selecting @option{-meabi}
+means that the stack is aligned to an 8-byte boundary, a function
+@code{__eabi} is called from @code{main} to set up the EABI
+environment, and the @option{-msdata} option can use both @code{r2} and
+@code{r13} to point to two separate small data areas.  Selecting
+@option{-mno-eabi} means that the stack is aligned to a 16-byte boundary,
+no EABI initialization function is called from @code{main}, and the
+@option{-msdata} option only uses @code{r13} to point to a single
+small data area.  The @option{-meabi} option is on by default if you
+configured GCC using one of the @samp{powerpc*-*-eabi*} options.
+
+@item -msdata=eabi
+@opindex msdata=eabi
+On System V.4 and embedded PowerPC systems, put small initialized
+@code{const} global and static data in the @code{.sdata2} section, which
+is pointed to by register @code{r2}.  Put small initialized
+non-@code{const} global and static data in the @code{.sdata} section,
+which is pointed to by register @code{r13}.  Put small uninitialized
+global and static data in the @code{.sbss} section, which is adjacent to
+the @code{.sdata} section.  The @option{-msdata=eabi} option is
+incompatible with the @option{-mrelocatable} option.  The
+@option{-msdata=eabi} option also sets the @option{-memb} option.
+
+@item -msdata=sysv
+@opindex msdata=sysv
+On System V.4 and embedded PowerPC systems, put small global and static
+data in the @code{.sdata} section, which is pointed to by register
+@code{r13}.  Put small uninitialized global and static data in the
+@code{.sbss} section, which is adjacent to the @code{.sdata} section.
+The @option{-msdata=sysv} option is incompatible with the
+@option{-mrelocatable} option.
+
+@item -msdata=default
+@itemx -msdata
+@opindex msdata=default
+@opindex msdata
+On System V.4 and embedded PowerPC systems, if @option{-meabi} is used,
+compile code the same as @option{-msdata=eabi}, otherwise compile code the
+same as @option{-msdata=sysv}.
+
+@item -msdata=data
+@opindex msdata=data
+On System V.4 and embedded PowerPC systems, put small global
+data in the @code{.sdata} section.  Put small uninitialized global
+data in the @code{.sbss} section.  Do not use register @code{r13}
+to address small data however.  This is the default behavior unless
+other @option{-msdata} options are used.
+
+@item -msdata=none
+@itemx -mno-sdata
+@opindex msdata=none
+@opindex mno-sdata
+On embedded PowerPC systems, put all initialized global and static data
+in the @code{.data} section, and all uninitialized data in the
+@code{.bss} section.
+
+@item -mreadonly-in-sdata
+@opindex mreadonly-in-sdata
+@opindex mno-readonly-in-sdata
+Put read-only objects in the @code{.sdata} section as well.  This is the
+default.
+
+@item -mblock-move-inline-limit=@var{num}
+@opindex mblock-move-inline-limit
+Inline all block moves (such as calls to @code{memcpy} or structure
+copies) less than or equal to @var{num} bytes.  The minimum value for
+@var{num} is 32 bytes on 32-bit targets and 64 bytes on 64-bit
+targets.  The default value is target-specific.
+
+@item -mblock-compare-inline-limit=@var{num}
+@opindex mblock-compare-inline-limit
+Generate non-looping inline code for all block compares (such as calls
+to @code{memcmp} or structure compares) less than or equal to @var{num}
+bytes. If @var{num} is 0, all inline expansion (non-loop and loop) of
+block compare is disabled. The default value is target-specific.
+
+@item -mblock-compare-inline-loop-limit=@var{num}
+@opindex mblock-compare-inline-loop-limit
+Generate an inline expansion using loop code for all block compares that
+are less than or equal to @var{num} bytes, but greater than the limit
+for non-loop inline block compare expansion. If the block length is not
+constant, at most @var{num} bytes will be compared before @code{memcmp}
+is called to compare the remainder of the block. The default value is
+target-specific.
+
+@item -mstring-compare-inline-limit=@var{num}
+@opindex mstring-compare-inline-limit
+Compare at most @var{num} string bytes with inline code.
+If the difference or end of string is not found at the
+end of the inline compare a call to @code{strcmp} or @code{strncmp} will
+take care of the rest of the comparison. The default is 64 bytes.
+
+@item -G @var{num}
+@opindex G
+@cindex smaller data references (PowerPC)
+@cindex .sdata/.sdata2 references (PowerPC)
+On embedded PowerPC systems, put global and static items less than or
+equal to @var{num} bytes into the small data or BSS sections instead of
+the normal data or BSS section.  By default, @var{num} is 8.  The
+@option{-G @var{num}} switch is also passed to the linker.
+All modules should be compiled with the same @option{-G @var{num}} value.
+
+@item -mregnames
+@itemx -mno-regnames
+@opindex mregnames
+@opindex mno-regnames
+On System V.4 and embedded PowerPC systems do (do not) emit register
+names in the assembly language output using symbolic forms.
+
+@item -mlongcall
+@itemx -mno-longcall
+@opindex mlongcall
+@opindex mno-longcall
+By default assume that all calls are far away so that a longer and more
+expensive calling sequence is required.  This is required for calls
+farther than 32 megabytes (33,554,432 bytes) from the current location.
+A short call is generated if the compiler knows
+the call cannot be that far away.  This setting can be overridden by
+the @code{shortcall} function attribute, or by @code{#pragma
+longcall(0)}.
+
+Some linkers are capable of detecting out-of-range calls and generating
+glue code on the fly.  On these systems, long calls are unnecessary and
+generate slower code.  As of this writing, the AIX linker can do this,
+as can the GNU linker for PowerPC/64.  It is planned to add this feature
+to the GNU linker for 32-bit PowerPC systems as well.
+
+On PowerPC64 ELFv2 and 32-bit PowerPC systems with newer GNU linkers,
+GCC can generate long calls using an inline PLT call sequence (see
+@option{-mpltseq}).  PowerPC with @option{-mbss-plt} and PowerPC64
+ELFv1 (big-endian) do not support inline PLT calls.
+
+On Darwin/PPC systems, @code{#pragma longcall} generates @code{jbsr
+callee, L42}, plus a @dfn{branch island} (glue code).  The two target
+addresses represent the callee and the branch island.  The
+Darwin/PPC linker prefers the first address and generates a @code{bl
+callee} if the PPC @code{bl} instruction reaches the callee directly;
+otherwise, the linker generates @code{bl L42} to call the branch
+island.  The branch island is appended to the body of the
+calling function; it computes the full 32-bit address of the callee
+and jumps to it.
+
+On Mach-O (Darwin) systems, this option directs the compiler emit to
+the glue for every direct call, and the Darwin linker decides whether
+to use or discard it.
+
+In the future, GCC may ignore all longcall specifications
+when the linker is known to generate glue.
+
+@item -mpltseq
+@itemx -mno-pltseq
+@opindex mpltseq
+@opindex mno-pltseq
+Implement (do not implement) -fno-plt and long calls using an inline
+PLT call sequence that supports lazy linking and long calls to
+functions in dlopen'd shared libraries.  Inline PLT calls are only
+supported on PowerPC64 ELFv2 and 32-bit PowerPC systems with newer GNU
+linkers, and are enabled by default if the support is detected when
+configuring GCC, and, in the case of 32-bit PowerPC, if GCC is
+configured with @option{--enable-secureplt}.  @option{-mpltseq} code
+and @option{-mbss-plt} 32-bit PowerPC relocatable objects may not be
+linked together.
+
+@item -mtls-markers
+@itemx -mno-tls-markers
+@opindex mtls-markers
+@opindex mno-tls-markers
+Mark (do not mark) calls to @code{__tls_get_addr} with a relocation
+specifying the function argument.  The relocation allows the linker to
+reliably associate function call with argument setup instructions for
+TLS optimization, which in turn allows GCC to better schedule the
+sequence.
+
+@item -mrecip
+@itemx -mno-recip
+@opindex mrecip
+This option enables use of the reciprocal estimate and
+reciprocal square root estimate instructions with additional
+Newton-Raphson steps to increase precision instead of doing a divide or
+square root and divide for floating-point arguments.  You should use
+the @option{-ffast-math} option when using @option{-mrecip} (or at
+least @option{-funsafe-math-optimizations},
+@option{-ffinite-math-only}, @option{-freciprocal-math} and
+@option{-fno-trapping-math}).  Note that while the throughput of the
+sequence is generally higher than the throughput of the non-reciprocal
+instruction, the precision of the sequence can be decreased by up to 2
+ulp (i.e.@: the inverse of 1.0 equals 0.99999994) for reciprocal square
+roots.
+
+@item -mrecip=@var{opt}
+@opindex mrecip=opt
+This option controls which reciprocal estimate instructions
+may be used.  @var{opt} is a comma-separated list of options, which may
+be preceded by a @code{!} to invert the option:
+
+@table @samp
+
+@item all
+Enable all estimate instructions.
+
+@item default 
+Enable the default instructions, equivalent to @option{-mrecip}.
+
+@item none 
+Disable all estimate instructions, equivalent to @option{-mno-recip}.
+
+@item div 
+Enable the reciprocal approximation instructions for both 
+single and double precision.
+
+@item divf 
+Enable the single-precision reciprocal approximation instructions.
+
+@item divd 
+Enable the double-precision reciprocal approximation instructions.
+
+@item rsqrt 
+Enable the reciprocal square root approximation instructions for both
+single and double precision.
+
+@item rsqrtf 
+Enable the single-precision reciprocal square root approximation instructions.
+
+@item rsqrtd 
+Enable the double-precision reciprocal square root approximation instructions.
+
+@end table
+
+So, for example, @option{-mrecip=all,!rsqrtd} enables
+all of the reciprocal estimate instructions, except for the
+@code{FRSQRTE}, @code{XSRSQRTEDP}, and @code{XVRSQRTEDP} instructions
+which handle the double-precision reciprocal square root calculations.
+
+@item -mrecip-precision
+@itemx -mno-recip-precision
+@opindex mrecip-precision
+Assume (do not assume) that the reciprocal estimate instructions
+provide higher-precision estimates than is mandated by the PowerPC
+ABI.  Selecting @option{-mcpu=power6}, @option{-mcpu=power7} or
+@option{-mcpu=power8} automatically selects @option{-mrecip-precision}.
+The double-precision square root estimate instructions are not generated by
+default on low-precision machines, since they do not provide an
+estimate that converges after three steps.
+
+@item -mveclibabi=@var{type}
+@opindex mveclibabi
+Specifies the ABI type to use for vectorizing intrinsics using an
+external library.  The only type supported at present is @samp{mass},
+which specifies to use IBM's Mathematical Acceleration Subsystem
+(MASS) libraries for vectorizing intrinsics using external libraries.
+GCC currently emits calls to @code{acosd2}, @code{acosf4},
+@code{acoshd2}, @code{acoshf4}, @code{asind2}, @code{asinf4},
+@code{asinhd2}, @code{asinhf4}, @code{atan2d2}, @code{atan2f4},
+@code{atand2}, @code{atanf4}, @code{atanhd2}, @code{atanhf4},
+@code{cbrtd2}, @code{cbrtf4}, @code{cosd2}, @code{cosf4},
+@code{coshd2}, @code{coshf4}, @code{erfcd2}, @code{erfcf4},
+@code{erfd2}, @code{erff4}, @code{exp2d2}, @code{exp2f4},
+@code{expd2}, @code{expf4}, @code{expm1d2}, @code{expm1f4},
+@code{hypotd2}, @code{hypotf4}, @code{lgammad2}, @code{lgammaf4},
+@code{log10d2}, @code{log10f4}, @code{log1pd2}, @code{log1pf4},
+@code{log2d2}, @code{log2f4}, @code{logd2}, @code{logf4},
+@code{powd2}, @code{powf4}, @code{sind2}, @code{sinf4}, @code{sinhd2},
+@code{sinhf4}, @code{sqrtd2}, @code{sqrtf4}, @code{tand2},
+@code{tanf4}, @code{tanhd2}, and @code{tanhf4} when generating code
+for power7.  Both @option{-ftree-vectorize} and
+@option{-funsafe-math-optimizations} must also be enabled.  The MASS
+libraries must be specified at link time.
+
+@item -mfriz
+@itemx -mno-friz
+@opindex mfriz
+Generate (do not generate) the @code{friz} instruction when the
+@option{-funsafe-math-optimizations} option is used to optimize
+rounding of floating-point values to 64-bit integer and back to floating
+point.  The @code{friz} instruction does not return the same value if
+the floating-point number is too large to fit in an integer.
+
+@item -mpointers-to-nested-functions
+@itemx -mno-pointers-to-nested-functions
+@opindex mpointers-to-nested-functions
+Generate (do not generate) code to load up the static chain register
+(@code{r11}) when calling through a pointer on AIX and 64-bit Linux
+systems where a function pointer points to a 3-word descriptor giving
+the function address, TOC value to be loaded in register @code{r2}, and
+static chain value to be loaded in register @code{r11}.  The
+@option{-mpointers-to-nested-functions} is on by default.  You cannot
+call through pointers to nested functions or pointers
+to functions compiled in other languages that use the static chain if
+you use @option{-mno-pointers-to-nested-functions}.
+
+@item -msave-toc-indirect
+@itemx -mno-save-toc-indirect
+@opindex msave-toc-indirect
+Generate (do not generate) code to save the TOC value in the reserved
+stack location in the function prologue if the function calls through
+a pointer on AIX and 64-bit Linux systems.  If the TOC value is not
+saved in the prologue, it is saved just before the call through the
+pointer.  The @option{-mno-save-toc-indirect} option is the default.
+
+@item -mcompat-align-parm
+@itemx -mno-compat-align-parm
+@opindex mcompat-align-parm
+Generate (do not generate) code to pass structure parameters with a
+maximum alignment of 64 bits, for compatibility with older versions
+of GCC.
+
+Older versions of GCC (prior to 4.9.0) incorrectly did not align a
+structure parameter on a 128-bit boundary when that structure contained
+a member requiring 128-bit alignment.  This is corrected in more
+recent versions of GCC.  This option may be used to generate code
+that is compatible with functions compiled with older versions of
+GCC.
+
+The @option{-mno-compat-align-parm} option is the default.
+
+@item -mstack-protector-guard=@var{guard}
+@itemx -mstack-protector-guard-reg=@var{reg}
+@itemx -mstack-protector-guard-offset=@var{offset}
+@itemx -mstack-protector-guard-symbol=@var{symbol}
+@opindex mstack-protector-guard
+@opindex mstack-protector-guard-reg
+@opindex mstack-protector-guard-offset
+@opindex mstack-protector-guard-symbol
+Generate stack protection code using canary at @var{guard}.  Supported
+locations are @samp{global} for global canary or @samp{tls} for per-thread
+canary in the TLS block (the default with GNU libc version 2.4 or later).
+
+With the latter choice the options
+@option{-mstack-protector-guard-reg=@var{reg}} and
+@option{-mstack-protector-guard-offset=@var{offset}} furthermore specify
+which register to use as base register for reading the canary, and from what
+offset from that base register. The default for those is as specified in the
+relevant ABI.  @option{-mstack-protector-guard-symbol=@var{symbol}} overrides
+the offset with a symbol reference to a canary in the TLS block.
+
+@item -mpcrel
+@itemx -mno-pcrel
+@opindex mpcrel
+@opindex mno-pcrel
+Generate (do not generate) pc-relative addressing.  The @option{-mpcrel}
+option requires that the medium code model (@option{-mcmodel=medium})
+and prefixed addressing (@option{-mprefixed}) options are enabled.
+
+@item -mprefixed
+@itemx -mno-prefixed
+@opindex mprefixed
+@opindex mno-prefixed
+Generate (do not generate) addressing modes using prefixed load and
+store instructions.  The @option{-mprefixed} option requires that
+the option @option{-mcpu=power10} (or later) is enabled.
+
+@item -mmma
+@itemx -mno-mma
+@opindex mmma
+@opindex mno-mma
+Generate (do not generate) the MMA instructions.  The @option{-mma}
+option requires that the option @option{-mcpu=power10} (or later)
+is enabled.
+
+@item -mrop-protect
+@itemx -mno-rop-protect
+@opindex mrop-protect
+@opindex mno-rop-protect
+Generate (do not generate) ROP protection instructions when the target
+processor supports them.  Currently this option disables the shrink-wrap
+optimization (@option{-fshrink-wrap}).
+
+@item -mprivileged
+@itemx -mno-privileged
+@opindex mprivileged
+@opindex mno-privileged
+Generate (do not generate) code that will run in privileged state.
+
+@item -mblock-ops-unaligned-vsx
+@itemx -mno-block-ops-unaligned-vsx
+@opindex block-ops-unaligned-vsx
+@opindex no-block-ops-unaligned-vsx
+Generate (do not generate) unaligned vsx loads and stores for
+inline expansion of @code{memcpy} and @code{memmove}.
+
+@item --param rs6000-vect-unroll-limit=
+The vectorizer will check with target information to determine whether it
+would be beneficial to unroll the main vectorized loop and by how much.  This
+parameter sets the upper bound of how much the vectorizer will unroll the main
+loop.  The default value is four.
+
+@end table
+
+@node RX Options
+@subsection RX Options
+@cindex RX Options
+
+These command-line options are defined for RX targets:
+
+@table @gcctabopt
+@item -m64bit-doubles
+@itemx -m32bit-doubles
+@opindex m64bit-doubles
+@opindex m32bit-doubles
+Make the @code{double} data type be 64 bits (@option{-m64bit-doubles})
+or 32 bits (@option{-m32bit-doubles}) in size.  The default is
+@option{-m32bit-doubles}.  @emph{Note} RX floating-point hardware only
+works on 32-bit values, which is why the default is
+@option{-m32bit-doubles}.
+
+@item -fpu
+@itemx -nofpu
+@opindex fpu
+@opindex nofpu
+Enables (@option{-fpu}) or disables (@option{-nofpu}) the use of RX
+floating-point hardware.  The default is enabled for the RX600
+series and disabled for the RX200 series.
+
+Floating-point instructions are only generated for 32-bit floating-point 
+values, however, so the FPU hardware is not used for doubles if the
+@option{-m64bit-doubles} option is used.
+
+@emph{Note} If the @option{-fpu} option is enabled then
+@option{-funsafe-math-optimizations} is also enabled automatically.
+This is because the RX FPU instructions are themselves unsafe.
+
+@item -mcpu=@var{name}
+@opindex mcpu
+Selects the type of RX CPU to be targeted.  Currently three types are
+supported, the generic @samp{RX600} and @samp{RX200} series hardware and
+the specific @samp{RX610} CPU.  The default is @samp{RX600}.
+
+The only difference between @samp{RX600} and @samp{RX610} is that the
+@samp{RX610} does not support the @code{MVTIPL} instruction.
+
+The @samp{RX200} series does not have a hardware floating-point unit
+and so @option{-nofpu} is enabled by default when this type is
+selected.
+
+@item -mbig-endian-data
+@itemx -mlittle-endian-data
+@opindex mbig-endian-data
+@opindex mlittle-endian-data
+Store data (but not code) in the big-endian format.  The default is
+@option{-mlittle-endian-data}, i.e.@: to store data in the little-endian
+format.
+
+@item -msmall-data-limit=@var{N}
+@opindex msmall-data-limit
+Specifies the maximum size in bytes of global and static variables
+which can be placed into the small data area.  Using the small data
+area can lead to smaller and faster code, but the size of area is
+limited and it is up to the programmer to ensure that the area does
+not overflow.  Also when the small data area is used one of the RX's
+registers (usually @code{r13}) is reserved for use pointing to this
+area, so it is no longer available for use by the compiler.  This
+could result in slower and/or larger code if variables are pushed onto
+the stack instead of being held in this register.
+
+Note, common variables (variables that have not been initialized) and
+constants are not placed into the small data area as they are assigned
+to other sections in the output executable.
+
+The default value is zero, which disables this feature.  Note, this
+feature is not enabled by default with higher optimization levels
+(@option{-O2} etc) because of the potentially detrimental effects of
+reserving a register.  It is up to the programmer to experiment and
+discover whether this feature is of benefit to their program.  See the
+description of the @option{-mpid} option for a description of how the
+actual register to hold the small data area pointer is chosen.
+
+@item -msim
+@itemx -mno-sim
+@opindex msim
+@opindex mno-sim
+Use the simulator runtime.  The default is to use the libgloss
+board-specific runtime.
+
+@item -mas100-syntax
+@itemx -mno-as100-syntax
+@opindex mas100-syntax
+@opindex mno-as100-syntax
+When generating assembler output use a syntax that is compatible with
+Renesas's AS100 assembler.  This syntax can also be handled by the GAS
+assembler, but it has some restrictions so it is not generated by default.
+
+@item -mmax-constant-size=@var{N}
+@opindex mmax-constant-size
+Specifies the maximum size, in bytes, of a constant that can be used as
+an operand in a RX instruction.  Although the RX instruction set does
+allow constants of up to 4 bytes in length to be used in instructions,
+a longer value equates to a longer instruction.  Thus in some
+circumstances it can be beneficial to restrict the size of constants
+that are used in instructions.  Constants that are too big are instead
+placed into a constant pool and referenced via register indirection.
+
+The value @var{N} can be between 0 and 4.  A value of 0 (the default)
+or 4 means that constants of any size are allowed.
+
+@item -mrelax
+@opindex mrelax
+Enable linker relaxation.  Linker relaxation is a process whereby the
+linker attempts to reduce the size of a program by finding shorter
+versions of various instructions.  Disabled by default.
+
+@item -mint-register=@var{N}
+@opindex mint-register
+Specify the number of registers to reserve for fast interrupt handler
+functions.  The value @var{N} can be between 0 and 4.  A value of 1
+means that register @code{r13} is reserved for the exclusive use
+of fast interrupt handlers.  A value of 2 reserves @code{r13} and
+@code{r12}.  A value of 3 reserves @code{r13}, @code{r12} and
+@code{r11}, and a value of 4 reserves @code{r13} through @code{r10}.
+A value of 0, the default, does not reserve any registers.
+
+@item -msave-acc-in-interrupts
+@opindex msave-acc-in-interrupts
+Specifies that interrupt handler functions should preserve the
+accumulator register.  This is only necessary if normal code might use
+the accumulator register, for example because it performs 64-bit
+multiplications.  The default is to ignore the accumulator as this
+makes the interrupt handlers faster.
+
+@item -mpid
+@itemx -mno-pid
+@opindex mpid
+@opindex mno-pid
+Enables the generation of position independent data.  When enabled any
+access to constant data is done via an offset from a base address
+held in a register.  This allows the location of constant data to be
+determined at run time without requiring the executable to be
+relocated, which is a benefit to embedded applications with tight
+memory constraints.  Data that can be modified is not affected by this
+option.
+
+Note, using this feature reserves a register, usually @code{r13}, for
+the constant data base address.  This can result in slower and/or
+larger code, especially in complicated functions.
+
+The actual register chosen to hold the constant data base address
+depends upon whether the @option{-msmall-data-limit} and/or the
+@option{-mint-register} command-line options are enabled.  Starting
+with register @code{r13} and proceeding downwards, registers are
+allocated first to satisfy the requirements of @option{-mint-register},
+then @option{-mpid} and finally @option{-msmall-data-limit}.  Thus it
+is possible for the small data area register to be @code{r8} if both
+@option{-mint-register=4} and @option{-mpid} are specified on the
+command line.
+
+By default this feature is not enabled.  The default can be restored
+via the @option{-mno-pid} command-line option.
+
+@item -mno-warn-multiple-fast-interrupts
+@itemx -mwarn-multiple-fast-interrupts
+@opindex mno-warn-multiple-fast-interrupts
+@opindex mwarn-multiple-fast-interrupts
+Prevents GCC from issuing a warning message if it finds more than one
+fast interrupt handler when it is compiling a file.  The default is to
+issue a warning for each extra fast interrupt handler found, as the RX
+only supports one such interrupt.
+
+@item -mallow-string-insns
+@itemx -mno-allow-string-insns
+@opindex mallow-string-insns
+@opindex mno-allow-string-insns
+Enables or disables the use of the string manipulation instructions
+@code{SMOVF}, @code{SCMPU}, @code{SMOVB}, @code{SMOVU}, @code{SUNTIL}
+@code{SWHILE} and also the @code{RMPA} instruction.  These
+instructions may prefetch data, which is not safe to do if accessing
+an I/O register.  (See section 12.2.7 of the RX62N Group User's Manual
+for more information).
+
+The default is to allow these instructions, but it is not possible for
+GCC to reliably detect all circumstances where a string instruction
+might be used to access an I/O register, so their use cannot be
+disabled automatically.  Instead it is reliant upon the programmer to
+use the @option{-mno-allow-string-insns} option if their program
+accesses I/O space.
+
+When the instructions are enabled GCC defines the C preprocessor
+symbol @code{__RX_ALLOW_STRING_INSNS__}, otherwise it defines the
+symbol @code{__RX_DISALLOW_STRING_INSNS__}.
+
+@item -mjsr
+@itemx -mno-jsr
+@opindex mjsr
+@opindex mno-jsr
+Use only (or not only) @code{JSR} instructions to access functions.
+This option can be used when code size exceeds the range of @code{BSR}
+instructions.  Note that @option{-mno-jsr} does not mean to not use
+@code{JSR} but instead means that any type of branch may be used.
+@end table
+
+@emph{Note:} The generic GCC command-line option @option{-ffixed-@var{reg}}
+has special significance to the RX port when used with the
+@code{interrupt} function attribute.  This attribute indicates a
+function intended to process fast interrupts.  GCC ensures
+that it only uses the registers @code{r10}, @code{r11}, @code{r12}
+and/or @code{r13} and only provided that the normal use of the
+corresponding registers have been restricted via the
+@option{-ffixed-@var{reg}} or @option{-mint-register} command-line
+options.
+
+@node S/390 and zSeries Options
+@subsection S/390 and zSeries Options
+@cindex S/390 and zSeries Options
+
+These are the @samp{-m} options defined for the S/390 and zSeries architecture.
+
+@table @gcctabopt
+@item -mhard-float
+@itemx -msoft-float
+@opindex mhard-float
+@opindex msoft-float
+Use (do not use) the hardware floating-point instructions and registers
+for floating-point operations.  When @option{-msoft-float} is specified,
+functions in @file{libgcc.a} are used to perform floating-point
+operations.  When @option{-mhard-float} is specified, the compiler
+generates IEEE floating-point instructions.  This is the default.
+
+@item -mhard-dfp
+@itemx -mno-hard-dfp
+@opindex mhard-dfp
+@opindex mno-hard-dfp
+Use (do not use) the hardware decimal-floating-point instructions for
+decimal-floating-point operations.  When @option{-mno-hard-dfp} is
+specified, functions in @file{libgcc.a} are used to perform
+decimal-floating-point operations.  When @option{-mhard-dfp} is
+specified, the compiler generates decimal-floating-point hardware
+instructions.  This is the default for @option{-march=z9-ec} or higher.
+
+@item -mlong-double-64
+@itemx -mlong-double-128
+@opindex mlong-double-64
+@opindex mlong-double-128
+These switches control the size of @code{long double} type. A size
+of 64 bits makes the @code{long double} type equivalent to the @code{double}
+type. This is the default.
+
+@item -mbackchain
+@itemx -mno-backchain
+@opindex mbackchain
+@opindex mno-backchain
+Store (do not store) the address of the caller's frame as backchain pointer
+into the callee's stack frame.
+A backchain may be needed to allow debugging using tools that do not understand
+DWARF call frame information.
+When @option{-mno-packed-stack} is in effect, the backchain pointer is stored
+at the bottom of the stack frame; when @option{-mpacked-stack} is in effect,
+the backchain is placed into the topmost word of the 96/160 byte register
+save area.
+
+In general, code compiled with @option{-mbackchain} is call-compatible with
+code compiled with @option{-mno-backchain}; however, use of the backchain
+for debugging purposes usually requires that the whole binary is built with
+@option{-mbackchain}.  Note that the combination of @option{-mbackchain},
+@option{-mpacked-stack} and @option{-mhard-float} is not supported.  In order
+to build a linux kernel use @option{-msoft-float}.
+
+The default is to not maintain the backchain.
+
+@item -mpacked-stack
+@itemx -mno-packed-stack
+@opindex mpacked-stack
+@opindex mno-packed-stack
+Use (do not use) the packed stack layout.  When @option{-mno-packed-stack} is
+specified, the compiler uses the all fields of the 96/160 byte register save
+area only for their default purpose; unused fields still take up stack space.
+When @option{-mpacked-stack} is specified, register save slots are densely
+packed at the top of the register save area; unused space is reused for other
+purposes, allowing for more efficient use of the available stack space.
+However, when @option{-mbackchain} is also in effect, the topmost word of
+the save area is always used to store the backchain, and the return address
+register is always saved two words below the backchain.
+
+As long as the stack frame backchain is not used, code generated with
+@option{-mpacked-stack} is call-compatible with code generated with
+@option{-mno-packed-stack}.  Note that some non-FSF releases of GCC 2.95 for
+S/390 or zSeries generated code that uses the stack frame backchain at run
+time, not just for debugging purposes.  Such code is not call-compatible
+with code compiled with @option{-mpacked-stack}.  Also, note that the
+combination of @option{-mbackchain},
+@option{-mpacked-stack} and @option{-mhard-float} is not supported.  In order
+to build a linux kernel use @option{-msoft-float}.
+
+The default is to not use the packed stack layout.
+
+@item -msmall-exec
+@itemx -mno-small-exec
+@opindex msmall-exec
+@opindex mno-small-exec
+Generate (or do not generate) code using the @code{bras} instruction
+to do subroutine calls.
+This only works reliably if the total executable size does not
+exceed 64k.  The default is to use the @code{basr} instruction instead,
+which does not have this limitation.
+
+@item -m64
+@itemx -m31
+@opindex m64
+@opindex m31
+When @option{-m31} is specified, generate code compliant to the
+GNU/Linux for S/390 ABI@.  When @option{-m64} is specified, generate
+code compliant to the GNU/Linux for zSeries ABI@.  This allows GCC in
+particular to generate 64-bit instructions.  For the @samp{s390}
+targets, the default is @option{-m31}, while the @samp{s390x}
+targets default to @option{-m64}.
+
+@item -mzarch
+@itemx -mesa
+@opindex mzarch
+@opindex mesa
+When @option{-mzarch} is specified, generate code using the
+instructions available on z/Architecture.
+When @option{-mesa} is specified, generate code using the
+instructions available on ESA/390.  Note that @option{-mesa} is
+not possible with @option{-m64}.
+When generating code compliant to the GNU/Linux for S/390 ABI,
+the default is @option{-mesa}.  When generating code compliant
+to the GNU/Linux for zSeries ABI, the default is @option{-mzarch}.
+
+@item -mhtm
+@itemx -mno-htm
+@opindex mhtm
+@opindex mno-htm
+The @option{-mhtm} option enables a set of builtins making use of
+instructions available with the transactional execution facility
+introduced with the IBM zEnterprise EC12 machine generation
+@ref{S/390 System z Built-in Functions}.
+@option{-mhtm} is enabled by default when using @option{-march=zEC12}.
+
+@item -mvx
+@itemx -mno-vx
+@opindex mvx
+@opindex mno-vx
+When @option{-mvx} is specified, generate code using the instructions
+available with the vector extension facility introduced with the IBM
+z13 machine generation.
+This option changes the ABI for some vector type values with regard to
+alignment and calling conventions.  In case vector type values are
+being used in an ABI-relevant context a GAS @samp{.gnu_attribute}
+command will be added to mark the resulting binary with the ABI used.
+@option{-mvx} is enabled by default when using @option{-march=z13}.
+
+@item -mzvector
+@itemx -mno-zvector
+@opindex mzvector
+@opindex mno-zvector
+The @option{-mzvector} option enables vector language extensions and
+builtins using instructions available with the vector extension
+facility introduced with the IBM z13 machine generation.
+This option adds support for @samp{vector} to be used as a keyword to
+define vector type variables and arguments.  @samp{vector} is only
+available when GNU extensions are enabled.  It will not be expanded
+when requesting strict standard compliance e.g.@: with @option{-std=c99}.
+In addition to the GCC low-level builtins @option{-mzvector} enables
+a set of builtins added for compatibility with AltiVec-style
+implementations like Power and Cell.  In order to make use of these
+builtins the header file @file{vecintrin.h} needs to be included.
+@option{-mzvector} is disabled by default.
+
+@item -mmvcle
+@itemx -mno-mvcle
+@opindex mmvcle
+@opindex mno-mvcle
+Generate (or do not generate) code using the @code{mvcle} instruction
+to perform block moves.  When @option{-mno-mvcle} is specified,
+use a @code{mvc} loop instead.  This is the default unless optimizing for
+size.
+
+@item -mdebug
+@itemx -mno-debug
+@opindex mdebug
+@opindex mno-debug
+Print (or do not print) additional debug information when compiling.
+The default is to not print debug information.
+
+@item -march=@var{cpu-type}
+@opindex march
+Generate code that runs on @var{cpu-type}, which is the name of a
+system representing a certain processor type.  Possible values for
+@var{cpu-type} are @samp{z900}/@samp{arch5}, @samp{z990}/@samp{arch6},
+@samp{z9-109}, @samp{z9-ec}/@samp{arch7}, @samp{z10}/@samp{arch8},
+@samp{z196}/@samp{arch9}, @samp{zEC12}, @samp{z13}/@samp{arch11},
+@samp{z14}/@samp{arch12}, @samp{z15}/@samp{arch13},
+@samp{z16}/@samp{arch14}, and @samp{native}.
+
+The default is @option{-march=z900}.
+
+Specifying @samp{native} as cpu type can be used to select the best
+architecture option for the host processor.
+@option{-march=native} has no effect if GCC does not recognize the
+processor.
+
+@item -mtune=@var{cpu-type}
+@opindex mtune
+Tune to @var{cpu-type} everything applicable about the generated code,
+except for the ABI and the set of available instructions.
+The list of @var{cpu-type} values is the same as for @option{-march}.
+The default is the value used for @option{-march}.
+
+@item -mtpf-trace
+@itemx -mno-tpf-trace
+@opindex mtpf-trace
+@opindex mno-tpf-trace
+Generate code that adds (does not add) in TPF OS specific branches to trace
+routines in the operating system.  This option is off by default, even
+when compiling for the TPF OS@.
+
+@item -mtpf-trace-skip
+@itemx -mno-tpf-trace-skip
+@opindex mtpf-trace-skip
+@opindex mno-tpf-trace-skip
+Generate code that changes (does not change) the default branch
+targets enabled by @option{-mtpf-trace} to point to specialized trace
+routines providing the ability of selectively skipping function trace
+entries for the TPF OS.  This option is off by default, even when
+compiling for the TPF OS and specifying @option{-mtpf-trace}.
+
+@item -mfused-madd
+@itemx -mno-fused-madd
+@opindex mfused-madd
+@opindex mno-fused-madd
+Generate code that uses (does not use) the floating-point multiply and
+accumulate instructions.  These instructions are generated by default if
+hardware floating point is used.
+
+@item -mwarn-framesize=@var{framesize}
+@opindex mwarn-framesize
+Emit a warning if the current function exceeds the given frame size.  Because
+this is a compile-time check it doesn't need to be a real problem when the program
+runs.  It is intended to identify functions that most probably cause
+a stack overflow.  It is useful to be used in an environment with limited stack
+size e.g.@: the linux kernel.
+
+@item -mwarn-dynamicstack
+@opindex mwarn-dynamicstack
+Emit a warning if the function calls @code{alloca} or uses dynamically-sized
+arrays.  This is generally a bad idea with a limited stack size.
+
+@item -mstack-guard=@var{stack-guard}
+@itemx -mstack-size=@var{stack-size}
+@opindex mstack-guard
+@opindex mstack-size
+If these options are provided the S/390 back end emits additional instructions in
+the function prologue that trigger a trap if the stack size is @var{stack-guard}
+bytes above the @var{stack-size} (remember that the stack on S/390 grows downward).
+If the @var{stack-guard} option is omitted the smallest power of 2 larger than
+the frame size of the compiled function is chosen.
+These options are intended to be used to help debugging stack overflow problems.
+The additionally emitted code causes only little overhead and hence can also be
+used in production-like systems without greater performance degradation.  The given
+values have to be exact powers of 2 and @var{stack-size} has to be greater than
+@var{stack-guard} without exceeding 64k.
+In order to be efficient the extra code makes the assumption that the stack starts
+at an address aligned to the value given by @var{stack-size}.
+The @var{stack-guard} option can only be used in conjunction with @var{stack-size}.
+
+@item -mhotpatch=@var{pre-halfwords},@var{post-halfwords}
+@opindex mhotpatch
+If the hotpatch option is enabled, a ``hot-patching'' function
+prologue is generated for all functions in the compilation unit.
+The funtion label is prepended with the given number of two-byte
+NOP instructions (@var{pre-halfwords}, maximum 1000000).  After
+the label, 2 * @var{post-halfwords} bytes are appended, using the
+largest NOP like instructions the architecture allows (maximum
+1000000).
+
+If both arguments are zero, hotpatching is disabled.
+
+This option can be overridden for individual functions with the
+@code{hotpatch} attribute.
+@end table
+
+@node Score Options
+@subsection Score Options
+@cindex Score Options
+
+These options are defined for Score implementations:
+
+@table @gcctabopt
+@item -meb
+@opindex meb
+Compile code for big-endian mode.  This is the default.
+
+@item -mel
+@opindex mel
+Compile code for little-endian mode.
+
+@item -mnhwloop
+@opindex mnhwloop
+Disable generation of @code{bcnz} instructions.
+
+@item -muls
+@opindex muls
+Enable generation of unaligned load and store instructions.
+
+@item -mmac
+@opindex mmac
+Enable the use of multiply-accumulate instructions. Disabled by default.
+
+@item -mscore5
+@opindex mscore5
+Specify the SCORE5 as the target architecture.
+
+@item -mscore5u
+@opindex mscore5u
+Specify the SCORE5U of the target architecture.
+
+@item -mscore7
+@opindex mscore7
+Specify the SCORE7 as the target architecture. This is the default.
+
+@item -mscore7d
+@opindex mscore7d
+Specify the SCORE7D as the target architecture.
+@end table
+
+@node SH Options
+@subsection SH Options
+
+These @samp{-m} options are defined for the SH implementations:
+
+@table @gcctabopt
+@item -m1
+@opindex m1
+Generate code for the SH1.
+
+@item -m2
+@opindex m2
+Generate code for the SH2.
+
+@item -m2e
+Generate code for the SH2e.
+
+@item -m2a-nofpu
+@opindex m2a-nofpu
+Generate code for the SH2a without FPU, or for a SH2a-FPU in such a way
+that the floating-point unit is not used.
+
+@item -m2a-single-only
+@opindex m2a-single-only
+Generate code for the SH2a-FPU, in such a way that no double-precision
+floating-point operations are used.
+
+@item -m2a-single
+@opindex m2a-single
+Generate code for the SH2a-FPU assuming the floating-point unit is in
+single-precision mode by default.
+
+@item -m2a
+@opindex m2a
+Generate code for the SH2a-FPU assuming the floating-point unit is in
+double-precision mode by default.
+
+@item -m3
+@opindex m3
+Generate code for the SH3.
+
+@item -m3e
+@opindex m3e
+Generate code for the SH3e.
+
+@item -m4-nofpu
+@opindex m4-nofpu
+Generate code for the SH4 without a floating-point unit.
+
+@item -m4-single-only
+@opindex m4-single-only
+Generate code for the SH4 with a floating-point unit that only
+supports single-precision arithmetic.
+
+@item -m4-single
+@opindex m4-single
+Generate code for the SH4 assuming the floating-point unit is in
+single-precision mode by default.
+
+@item -m4
+@opindex m4
+Generate code for the SH4.
+
+@item -m4-100
+@opindex m4-100
+Generate code for SH4-100.
+
+@item -m4-100-nofpu
+@opindex m4-100-nofpu
+Generate code for SH4-100 in such a way that the
+floating-point unit is not used.
+
+@item -m4-100-single
+@opindex m4-100-single
+Generate code for SH4-100 assuming the floating-point unit is in
+single-precision mode by default.
+
+@item -m4-100-single-only
+@opindex m4-100-single-only
+Generate code for SH4-100 in such a way that no double-precision
+floating-point operations are used.
+
+@item -m4-200
+@opindex m4-200
+Generate code for SH4-200.
+
+@item -m4-200-nofpu
+@opindex m4-200-nofpu
+Generate code for SH4-200 without in such a way that the
+floating-point unit is not used.
+
+@item -m4-200-single
+@opindex m4-200-single
+Generate code for SH4-200 assuming the floating-point unit is in
+single-precision mode by default.
+
+@item -m4-200-single-only
+@opindex m4-200-single-only
+Generate code for SH4-200 in such a way that no double-precision
+floating-point operations are used.
+
+@item -m4-300
+@opindex m4-300
+Generate code for SH4-300.
+
+@item -m4-300-nofpu
+@opindex m4-300-nofpu
+Generate code for SH4-300 without in such a way that the
+floating-point unit is not used.
+
+@item -m4-300-single
+@opindex m4-300-single
+Generate code for SH4-300 in such a way that no double-precision
+floating-point operations are used.
+
+@item -m4-300-single-only
+@opindex m4-300-single-only
+Generate code for SH4-300 in such a way that no double-precision
+floating-point operations are used.
+
+@item -m4-340
+@opindex m4-340
+Generate code for SH4-340 (no MMU, no FPU).
+
+@item -m4-500
+@opindex m4-500
+Generate code for SH4-500 (no FPU).  Passes @option{-isa=sh4-nofpu} to the
+assembler.
+
+@item -m4a-nofpu
+@opindex m4a-nofpu
+Generate code for the SH4al-dsp, or for a SH4a in such a way that the
+floating-point unit is not used.
+
+@item -m4a-single-only
+@opindex m4a-single-only
+Generate code for the SH4a, in such a way that no double-precision
+floating-point operations are used.
+
+@item -m4a-single
+@opindex m4a-single
+Generate code for the SH4a assuming the floating-point unit is in
+single-precision mode by default.
+
+@item -m4a
+@opindex m4a
+Generate code for the SH4a.
+
+@item -m4al
+@opindex m4al
+Same as @option{-m4a-nofpu}, except that it implicitly passes
+@option{-dsp} to the assembler.  GCC doesn't generate any DSP
+instructions at the moment.
+
+@item -mb
+@opindex mb
+Compile code for the processor in big-endian mode.
+
+@item -ml
+@opindex ml
+Compile code for the processor in little-endian mode.
+
+@item -mdalign
+@opindex mdalign
+Align doubles at 64-bit boundaries.  Note that this changes the calling
+conventions, and thus some functions from the standard C library do
+not work unless you recompile it first with @option{-mdalign}.
+
+@item -mrelax
+@opindex mrelax
+Shorten some address references at link time, when possible; uses the
+linker option @option{-relax}.
+
+@item -mbigtable
+@opindex mbigtable
+Use 32-bit offsets in @code{switch} tables.  The default is to use
+16-bit offsets.
+
+@item -mbitops
+@opindex mbitops
+Enable the use of bit manipulation instructions on SH2A.
+
+@item -mfmovd
+@opindex mfmovd
+Enable the use of the instruction @code{fmovd}.  Check @option{-mdalign} for
+alignment constraints.
+
+@item -mrenesas
+@opindex mrenesas
+Comply with the calling conventions defined by Renesas.
+
+@item -mno-renesas
+@opindex mno-renesas
+Comply with the calling conventions defined for GCC before the Renesas
+conventions were available.  This option is the default for all
+targets of the SH toolchain.
+
+@item -mnomacsave
+@opindex mnomacsave
+Mark the @code{MAC} register as call-clobbered, even if
+@option{-mrenesas} is given.
+
+@item -mieee
+@itemx -mno-ieee
+@opindex mieee
+@opindex mno-ieee
+Control the IEEE compliance of floating-point comparisons, which affects the
+handling of cases where the result of a comparison is unordered.  By default
+@option{-mieee} is implicitly enabled.  If @option{-ffinite-math-only} is
+enabled @option{-mno-ieee} is implicitly set, which results in faster
+floating-point greater-equal and less-equal comparisons.  The implicit settings
+can be overridden by specifying either @option{-mieee} or @option{-mno-ieee}.
+
+@item -minline-ic_invalidate
+@opindex minline-ic_invalidate
+Inline code to invalidate instruction cache entries after setting up
+nested function trampolines.
+This option has no effect if @option{-musermode} is in effect and the selected
+code generation option (e.g.@: @option{-m4}) does not allow the use of the @code{icbi}
+instruction.
+If the selected code generation option does not allow the use of the @code{icbi}
+instruction, and @option{-musermode} is not in effect, the inlined code
+manipulates the instruction cache address array directly with an associative
+write.  This not only requires privileged mode at run time, but it also
+fails if the cache line had been mapped via the TLB and has become unmapped.
+
+@item -misize
+@opindex misize
+Dump instruction size and location in the assembly code.
+
+@item -mpadstruct
+@opindex mpadstruct
+This option is deprecated.  It pads structures to multiple of 4 bytes,
+which is incompatible with the SH ABI@.
+
+@item -matomic-model=@var{model}
+@opindex matomic-model=@var{model}
+Sets the model of atomic operations and additional parameters as a comma
+separated list.  For details on the atomic built-in functions see
+@ref{__atomic Builtins}.  The following models and parameters are supported:
+
+@table @samp
+
+@item none
+Disable compiler generated atomic sequences and emit library calls for atomic
+operations.  This is the default if the target is not @code{sh*-*-linux*}.
+
+@item soft-gusa
+Generate GNU/Linux compatible gUSA software atomic sequences for the atomic
+built-in functions.  The generated atomic sequences require additional support
+from the interrupt/exception handling code of the system and are only suitable
+for SH3* and SH4* single-core systems.  This option is enabled by default when
+the target is @code{sh*-*-linux*} and SH3* or SH4*.  When the target is SH4A,
+this option also partially utilizes the hardware atomic instructions
+@code{movli.l} and @code{movco.l} to create more efficient code, unless
+@samp{strict} is specified.  
+
+@item soft-tcb
+Generate software atomic sequences that use a variable in the thread control
+block.  This is a variation of the gUSA sequences which can also be used on
+SH1* and SH2* targets.  The generated atomic sequences require additional
+support from the interrupt/exception handling code of the system and are only
+suitable for single-core systems.  When using this model, the @samp{gbr-offset=}
+parameter has to be specified as well.
+
+@item soft-imask
+Generate software atomic sequences that temporarily disable interrupts by
+setting @code{SR.IMASK = 1111}.  This model works only when the program runs
+in privileged mode and is only suitable for single-core systems.  Additional
+support from the interrupt/exception handling code of the system is not
+required.  This model is enabled by default when the target is
+@code{sh*-*-linux*} and SH1* or SH2*.
+
+@item hard-llcs
+Generate hardware atomic sequences using the @code{movli.l} and @code{movco.l}
+instructions only.  This is only available on SH4A and is suitable for
+multi-core systems.  Since the hardware instructions support only 32 bit atomic
+variables access to 8 or 16 bit variables is emulated with 32 bit accesses.
+Code compiled with this option is also compatible with other software
+atomic model interrupt/exception handling systems if executed on an SH4A
+system.  Additional support from the interrupt/exception handling code of the
+system is not required for this model.
+
+@item gbr-offset=
+This parameter specifies the offset in bytes of the variable in the thread
+control block structure that should be used by the generated atomic sequences
+when the @samp{soft-tcb} model has been selected.  For other models this
+parameter is ignored.  The specified value must be an integer multiple of four
+and in the range 0-1020.
+
+@item strict
+This parameter prevents mixed usage of multiple atomic models, even if they
+are compatible, and makes the compiler generate atomic sequences of the
+specified model only.
+
+@end table
+
+@item -mtas
+@opindex mtas
+Generate the @code{tas.b} opcode for @code{__atomic_test_and_set}.
+Notice that depending on the particular hardware and software configuration
+this can degrade overall performance due to the operand cache line flushes
+that are implied by the @code{tas.b} instruction.  On multi-core SH4A
+processors the @code{tas.b} instruction must be used with caution since it
+can result in data corruption for certain cache configurations.
+
+@item -mprefergot
+@opindex mprefergot
+When generating position-independent code, emit function calls using
+the Global Offset Table instead of the Procedure Linkage Table.
+
+@item -musermode
+@itemx -mno-usermode
+@opindex musermode
+@opindex mno-usermode
+Don't allow (allow) the compiler generating privileged mode code.  Specifying
+@option{-musermode} also implies @option{-mno-inline-ic_invalidate} if the
+inlined code would not work in user mode.  @option{-musermode} is the default
+when the target is @code{sh*-*-linux*}.  If the target is SH1* or SH2*
+@option{-musermode} has no effect, since there is no user mode.
+
+@item -multcost=@var{number}
+@opindex multcost=@var{number}
+Set the cost to assume for a multiply insn.
+
+@item -mdiv=@var{strategy}
+@opindex mdiv=@var{strategy}
+Set the division strategy to be used for integer division operations.
+@var{strategy} can be one of: 
+
+@table @samp
+
+@item call-div1
+Calls a library function that uses the single-step division instruction
+@code{div1} to perform the operation.  Division by zero calculates an
+unspecified result and does not trap.  This is the default except for SH4,
+SH2A and SHcompact.
+
+@item call-fp
+Calls a library function that performs the operation in double precision
+floating point.  Division by zero causes a floating-point exception.  This is
+the default for SHcompact with FPU.  Specifying this for targets that do not
+have a double precision FPU defaults to @code{call-div1}.
+
+@item call-table
+Calls a library function that uses a lookup table for small divisors and
+the @code{div1} instruction with case distinction for larger divisors.  Division
+by zero calculates an unspecified result and does not trap.  This is the default
+for SH4.  Specifying this for targets that do not have dynamic shift
+instructions defaults to @code{call-div1}.
+
+@end table
+
+When a division strategy has not been specified the default strategy is
+selected based on the current target.  For SH2A the default strategy is to
+use the @code{divs} and @code{divu} instructions instead of library function
+calls.
+
+@item -maccumulate-outgoing-args
+@opindex maccumulate-outgoing-args
+Reserve space once for outgoing arguments in the function prologue rather
+than around each call.  Generally beneficial for performance and size.  Also
+needed for unwinding to avoid changing the stack frame around conditional code.
+
+@item -mdivsi3_libfunc=@var{name}
+@opindex mdivsi3_libfunc=@var{name}
+Set the name of the library function used for 32-bit signed division to
+@var{name}.
+This only affects the name used in the @samp{call} division strategies, and
+the compiler still expects the same sets of input/output/clobbered registers as
+if this option were not present.
+
+@item -mfixed-range=@var{register-range}
+@opindex mfixed-range
+Generate code treating the given register range as fixed registers.
+A fixed register is one that the register allocator cannot use.  This is
+useful when compiling kernel code.  A register range is specified as
+two registers separated by a dash.  Multiple register ranges can be
+specified separated by a comma.
+
+@item -mbranch-cost=@var{num}
+@opindex mbranch-cost=@var{num}
+Assume @var{num} to be the cost for a branch instruction.  Higher numbers
+make the compiler try to generate more branch-free code if possible.  
+If not specified the value is selected depending on the processor type that
+is being compiled for.
+
+@item -mzdcbranch
+@itemx -mno-zdcbranch
+@opindex mzdcbranch
+@opindex mno-zdcbranch
+Assume (do not assume) that zero displacement conditional branch instructions
+@code{bt} and @code{bf} are fast.  If @option{-mzdcbranch} is specified, the
+compiler prefers zero displacement branch code sequences.  This is
+enabled by default when generating code for SH4 and SH4A.  It can be explicitly
+disabled by specifying @option{-mno-zdcbranch}.
+
+@item -mcbranch-force-delay-slot
+@opindex mcbranch-force-delay-slot
+Force the usage of delay slots for conditional branches, which stuffs the delay
+slot with a @code{nop} if a suitable instruction cannot be found.  By default
+this option is disabled.  It can be enabled to work around hardware bugs as
+found in the original SH7055.
+
+@item -mfused-madd
+@itemx -mno-fused-madd
+@opindex mfused-madd
+@opindex mno-fused-madd
+Generate code that uses (does not use) the floating-point multiply and
+accumulate instructions.  These instructions are generated by default
+if hardware floating point is used.  The machine-dependent
+@option{-mfused-madd} option is now mapped to the machine-independent
+@option{-ffp-contract=fast} option, and @option{-mno-fused-madd} is
+mapped to @option{-ffp-contract=off}.
+
+@item -mfsca
+@itemx -mno-fsca
+@opindex mfsca
+@opindex mno-fsca
+Allow or disallow the compiler to emit the @code{fsca} instruction for sine
+and cosine approximations.  The option @option{-mfsca} must be used in
+combination with @option{-funsafe-math-optimizations}.  It is enabled by default
+when generating code for SH4A.  Using @option{-mno-fsca} disables sine and cosine
+approximations even if @option{-funsafe-math-optimizations} is in effect.
+
+@item -mfsrra
+@itemx -mno-fsrra
+@opindex mfsrra
+@opindex mno-fsrra
+Allow or disallow the compiler to emit the @code{fsrra} instruction for
+reciprocal square root approximations.  The option @option{-mfsrra} must be used
+in combination with @option{-funsafe-math-optimizations} and
+@option{-ffinite-math-only}.  It is enabled by default when generating code for
+SH4A.  Using @option{-mno-fsrra} disables reciprocal square root approximations
+even if @option{-funsafe-math-optimizations} and @option{-ffinite-math-only} are
+in effect.
+
+@item -mpretend-cmove
+@opindex mpretend-cmove
+Prefer zero-displacement conditional branches for conditional move instruction
+patterns.  This can result in faster code on the SH4 processor.
+
+@item -mfdpic
+@opindex fdpic
+Generate code using the FDPIC ABI.
+
+@end table
+
+@node Solaris 2 Options
+@subsection Solaris 2 Options
+@cindex Solaris 2 options
+
+These @samp{-m} options are supported on Solaris 2:
+
+@table @gcctabopt
+@item -mclear-hwcap
+@opindex mclear-hwcap
+@option{-mclear-hwcap} tells the compiler to remove the hardware
+capabilities generated by the Solaris assembler.  This is only necessary
+when object files use ISA extensions not supported by the current
+machine, but check at runtime whether or not to use them.
+
+@item -mimpure-text
+@opindex mimpure-text
+@option{-mimpure-text}, used in addition to @option{-shared}, tells
+the compiler to not pass @option{-z text} to the linker when linking a
+shared object.  Using this option, you can link position-dependent
+code into a shared object.
+
+@option{-mimpure-text} suppresses the ``relocations remain against
+allocatable but non-writable sections'' linker error message.
+However, the necessary relocations trigger copy-on-write, and the
+shared object is not actually shared across processes.  Instead of
+using @option{-mimpure-text}, you should compile all source code with
+@option{-fpic} or @option{-fPIC}.
+
+@end table
+
+These switches are supported in addition to the above on Solaris 2:
+
+@table @gcctabopt
+@item -pthreads
+@opindex pthreads
+This is a synonym for @option{-pthread}.
+@end table
+
+@node SPARC Options
+@subsection SPARC Options
+@cindex SPARC options
+
+These @samp{-m} options are supported on the SPARC:
+
+@table @gcctabopt
+@item -mno-app-regs
+@itemx -mapp-regs
+@opindex mno-app-regs
+@opindex mapp-regs
+Specify @option{-mapp-regs} to generate output using the global registers
+2 through 4, which the SPARC SVR4 ABI reserves for applications.  Like the
+global register 1, each global register 2 through 4 is then treated as an
+allocable register that is clobbered by function calls.  This is the default.
+
+To be fully SVR4 ABI-compliant at the cost of some performance loss,
+specify @option{-mno-app-regs}.  You should compile libraries and system
+software with this option.
+
+@item -mflat
+@itemx -mno-flat
+@opindex mflat
+@opindex mno-flat
+With @option{-mflat}, the compiler does not generate save/restore instructions
+and uses a ``flat'' or single register window model.  This model is compatible
+with the regular register window model.  The local registers and the input
+registers (0--5) are still treated as ``call-saved'' registers and are
+saved on the stack as needed.
+
+With @option{-mno-flat} (the default), the compiler generates save/restore
+instructions (except for leaf functions).  This is the normal operating mode.
+
+@item -mfpu
+@itemx -mhard-float
+@opindex mfpu
+@opindex mhard-float
+Generate output containing floating-point instructions.  This is the
+default.
+
+@item -mno-fpu
+@itemx -msoft-float
+@opindex mno-fpu
+@opindex msoft-float
+Generate output containing library calls for floating point.
+@strong{Warning:} the requisite libraries are not available for all SPARC
+targets.  Normally the facilities of the machine's usual C compiler are
+used, but this cannot be done directly in cross-compilation.  You must make
+your own arrangements to provide suitable library functions for
+cross-compilation.  The embedded targets @samp{sparc-*-aout} and
+@samp{sparclite-*-*} do provide software floating-point support.
+
+@option{-msoft-float} changes the calling convention in the output file;
+therefore, it is only useful if you compile @emph{all} of a program with
+this option.  In particular, you need to compile @file{libgcc.a}, the
+library that comes with GCC, with @option{-msoft-float} in order for
+this to work.
+
+@item -mhard-quad-float
+@opindex mhard-quad-float
+Generate output containing quad-word (long double) floating-point
+instructions.
+
+@item -msoft-quad-float
+@opindex msoft-quad-float
+Generate output containing library calls for quad-word (long double)
+floating-point instructions.  The functions called are those specified
+in the SPARC ABI@.  This is the default.
+
+As of this writing, there are no SPARC implementations that have hardware
+support for the quad-word floating-point instructions.  They all invoke
+a trap handler for one of these instructions, and then the trap handler
+emulates the effect of the instruction.  Because of the trap handler overhead,
+this is much slower than calling the ABI library routines.  Thus the
+@option{-msoft-quad-float} option is the default.
+
+@item -mno-unaligned-doubles
+@itemx -munaligned-doubles
+@opindex mno-unaligned-doubles
+@opindex munaligned-doubles
+Assume that doubles have 8-byte alignment.  This is the default.
+
+With @option{-munaligned-doubles}, GCC assumes that doubles have 8-byte
+alignment only if they are contained in another type, or if they have an
+absolute address.  Otherwise, it assumes they have 4-byte alignment.
+Specifying this option avoids some rare compatibility problems with code
+generated by other compilers.  It is not the default because it results
+in a performance loss, especially for floating-point code.
+
+@item -muser-mode
+@itemx -mno-user-mode
+@opindex muser-mode
+@opindex mno-user-mode
+Do not generate code that can only run in supervisor mode.  This is relevant
+only for the @code{casa} instruction emitted for the LEON3 processor.  This
+is the default.
+
+@item -mfaster-structs
+@itemx -mno-faster-structs
+@opindex mfaster-structs
+@opindex mno-faster-structs
+With @option{-mfaster-structs}, the compiler assumes that structures
+should have 8-byte alignment.  This enables the use of pairs of
+@code{ldd} and @code{std} instructions for copies in structure
+assignment, in place of twice as many @code{ld} and @code{st} pairs.
+However, the use of this changed alignment directly violates the SPARC
+ABI@.  Thus, it's intended only for use on targets where the developer
+acknowledges that their resulting code is not directly in line with
+the rules of the ABI@.
+
+@item -mstd-struct-return
+@itemx -mno-std-struct-return
+@opindex mstd-struct-return
+@opindex mno-std-struct-return
+With @option{-mstd-struct-return}, the compiler generates checking code
+in functions returning structures or unions to detect size mismatches
+between the two sides of function calls, as per the 32-bit ABI@.
+
+The default is @option{-mno-std-struct-return}.  This option has no effect
+in 64-bit mode.
+
+@item -mlra
+@itemx -mno-lra
+@opindex mlra
+@opindex mno-lra
+Enable Local Register Allocation.  This is the default for SPARC since GCC 7
+so @option{-mno-lra} needs to be passed to get old Reload.
+
+@item -mcpu=@var{cpu_type}
+@opindex mcpu
+Set the instruction set, register set, and instruction scheduling parameters
+for machine type @var{cpu_type}.  Supported values for @var{cpu_type} are
+@samp{v7}, @samp{cypress}, @samp{v8}, @samp{supersparc}, @samp{hypersparc},
+@samp{leon}, @samp{leon3}, @samp{leon3v7}, @samp{leon5}, @samp{sparclite},
+@samp{f930}, @samp{f934}, @samp{sparclite86x}, @samp{sparclet}, @samp{tsc701},
+@samp{v9}, @samp{ultrasparc}, @samp{ultrasparc3}, @samp{niagara},
+@samp{niagara2}, @samp{niagara3}, @samp{niagara4}, @samp{niagara7} and
+@samp{m8}.
+
+Native Solaris and GNU/Linux toolchains also support the value @samp{native},
+which selects the best architecture option for the host processor.
+@option{-mcpu=native} has no effect if GCC does not recognize
+the processor.
+
+Default instruction scheduling parameters are used for values that select
+an architecture and not an implementation.  These are @samp{v7}, @samp{v8},
+@samp{sparclite}, @samp{sparclet}, @samp{v9}.
+
+Here is a list of each supported architecture and their supported
+implementations.
+
+@table @asis
+@item v7
+cypress, leon3v7
+
+@item v8
+supersparc, hypersparc, leon, leon3, leon5
+
+@item sparclite
+f930, f934, sparclite86x
+
+@item sparclet
+tsc701
+
+@item v9
+ultrasparc, ultrasparc3, niagara, niagara2, niagara3, niagara4,
+niagara7, m8
+@end table
+
+By default (unless configured otherwise), GCC generates code for the V7
+variant of the SPARC architecture.  With @option{-mcpu=cypress}, the compiler
+additionally optimizes it for the Cypress CY7C602 chip, as used in the
+SPARCStation/SPARCServer 3xx series.  This is also appropriate for the older
+SPARCStation 1, 2, IPX etc.
+
+With @option{-mcpu=v8}, GCC generates code for the V8 variant of the SPARC
+architecture.  The only difference from V7 code is that the compiler emits
+the integer multiply and integer divide instructions which exist in SPARC-V8
+but not in SPARC-V7.  With @option{-mcpu=supersparc}, the compiler additionally
+optimizes it for the SuperSPARC chip, as used in the SPARCStation 10, 1000 and
+2000 series.
+
+With @option{-mcpu=sparclite}, GCC generates code for the SPARClite variant of
+the SPARC architecture.  This adds the integer multiply, integer divide step
+and scan (@code{ffs}) instructions which exist in SPARClite but not in SPARC-V7.
+With @option{-mcpu=f930}, the compiler additionally optimizes it for the
+Fujitsu MB86930 chip, which is the original SPARClite, with no FPU@.  With
+@option{-mcpu=f934}, the compiler additionally optimizes it for the Fujitsu
+MB86934 chip, which is the more recent SPARClite with FPU@.
+
+With @option{-mcpu=sparclet}, GCC generates code for the SPARClet variant of
+the SPARC architecture.  This adds the integer multiply, multiply/accumulate,
+integer divide step and scan (@code{ffs}) instructions which exist in SPARClet
+but not in SPARC-V7.  With @option{-mcpu=tsc701}, the compiler additionally
+optimizes it for the TEMIC SPARClet chip.
+
+With @option{-mcpu=v9}, GCC generates code for the V9 variant of the SPARC
+architecture.  This adds 64-bit integer and floating-point move instructions,
+3 additional floating-point condition code registers and conditional move
+instructions.  With @option{-mcpu=ultrasparc}, the compiler additionally
+optimizes it for the Sun UltraSPARC I/II/IIi chips.  With
+@option{-mcpu=ultrasparc3}, the compiler additionally optimizes it for the
+Sun UltraSPARC III/III+/IIIi/IIIi+/IV/IV+ chips.  With
+@option{-mcpu=niagara}, the compiler additionally optimizes it for
+Sun UltraSPARC T1 chips.  With @option{-mcpu=niagara2}, the compiler
+additionally optimizes it for Sun UltraSPARC T2 chips. With
+@option{-mcpu=niagara3}, the compiler additionally optimizes it for Sun
+UltraSPARC T3 chips.  With @option{-mcpu=niagara4}, the compiler
+additionally optimizes it for Sun UltraSPARC T4 chips.  With
+@option{-mcpu=niagara7}, the compiler additionally optimizes it for
+Oracle SPARC M7 chips.  With @option{-mcpu=m8}, the compiler
+additionally optimizes it for Oracle M8 chips.
+
+@item -mtune=@var{cpu_type}
+@opindex mtune
+Set the instruction scheduling parameters for machine type
+@var{cpu_type}, but do not set the instruction set or register set that the
+option @option{-mcpu=@var{cpu_type}} does.
+
+The same values for @option{-mcpu=@var{cpu_type}} can be used for
+@option{-mtune=@var{cpu_type}}, but the only useful values are those
+that select a particular CPU implementation.  Those are
+@samp{cypress}, @samp{supersparc}, @samp{hypersparc}, @samp{leon},
+@samp{leon3}, @samp{leon3v7}, @samp{leon5}, @samp{f930}, @samp{f934},
+@samp{sparclite86x}, @samp{tsc701}, @samp{ultrasparc},
+@samp{ultrasparc3}, @samp{niagara}, @samp{niagara2}, @samp{niagara3},
+@samp{niagara4}, @samp{niagara7} and @samp{m8}.  With native Solaris
+and GNU/Linux toolchains, @samp{native} can also be used.
+
+@item -mv8plus
+@itemx -mno-v8plus
+@opindex mv8plus
+@opindex mno-v8plus
+With @option{-mv8plus}, GCC generates code for the SPARC-V8+ ABI@.  The
+difference from the V8 ABI is that the global and out registers are
+considered 64 bits wide.  This is enabled by default on Solaris in 32-bit
+mode for all SPARC-V9 processors.
+
+@item -mvis
+@itemx -mno-vis
+@opindex mvis
+@opindex mno-vis
+With @option{-mvis}, GCC generates code that takes advantage of the UltraSPARC
+Visual Instruction Set extensions.  The default is @option{-mno-vis}.
+
+@item -mvis2
+@itemx -mno-vis2
+@opindex mvis2
+@opindex mno-vis2
+With @option{-mvis2}, GCC generates code that takes advantage of
+version 2.0 of the UltraSPARC Visual Instruction Set extensions.  The
+default is @option{-mvis2} when targeting a cpu that supports such
+instructions, such as UltraSPARC-III and later.  Setting @option{-mvis2}
+also sets @option{-mvis}.
+
+@item -mvis3
+@itemx -mno-vis3
+@opindex mvis3
+@opindex mno-vis3
+With @option{-mvis3}, GCC generates code that takes advantage of
+version 3.0 of the UltraSPARC Visual Instruction Set extensions.  The
+default is @option{-mvis3} when targeting a cpu that supports such
+instructions, such as niagara-3 and later.  Setting @option{-mvis3}
+also sets @option{-mvis2} and @option{-mvis}.
+
+@item -mvis4
+@itemx -mno-vis4
+@opindex mvis4
+@opindex mno-vis4
+With @option{-mvis4}, GCC generates code that takes advantage of
+version 4.0 of the UltraSPARC Visual Instruction Set extensions.  The
+default is @option{-mvis4} when targeting a cpu that supports such
+instructions, such as niagara-7 and later.  Setting @option{-mvis4}
+also sets @option{-mvis3}, @option{-mvis2} and @option{-mvis}.
+
+@item -mvis4b
+@itemx -mno-vis4b
+@opindex mvis4b
+@opindex mno-vis4b
+With @option{-mvis4b}, GCC generates code that takes advantage of
+version 4.0 of the UltraSPARC Visual Instruction Set extensions, plus
+the additional VIS instructions introduced in the Oracle SPARC
+Architecture 2017.  The default is @option{-mvis4b} when targeting a
+cpu that supports such instructions, such as m8 and later.  Setting
+@option{-mvis4b} also sets @option{-mvis4}, @option{-mvis3},
+@option{-mvis2} and @option{-mvis}.
+
+@item -mcbcond
+@itemx -mno-cbcond
+@opindex mcbcond
+@opindex mno-cbcond
+With @option{-mcbcond}, GCC generates code that takes advantage of the UltraSPARC
+Compare-and-Branch-on-Condition instructions.  The default is @option{-mcbcond}
+when targeting a CPU that supports such instructions, such as Niagara-4 and
+later.
+
+@item -mfmaf
+@itemx -mno-fmaf
+@opindex mfmaf
+@opindex mno-fmaf
+With @option{-mfmaf}, GCC generates code that takes advantage of the UltraSPARC
+Fused Multiply-Add Floating-point instructions.  The default is @option{-mfmaf}
+when targeting a CPU that supports such instructions, such as Niagara-3 and
+later.
+
+@item -mfsmuld
+@itemx -mno-fsmuld
+@opindex mfsmuld
+@opindex mno-fsmuld
+With @option{-mfsmuld}, GCC generates code that takes advantage of the
+Floating-point Multiply Single to Double (FsMULd) instruction.  The default is
+@option{-mfsmuld} when targeting a CPU supporting the architecture versions V8
+or V9 with FPU except @option{-mcpu=leon}.
+
+@item -mpopc
+@itemx -mno-popc
+@opindex mpopc
+@opindex mno-popc
+With @option{-mpopc}, GCC generates code that takes advantage of the UltraSPARC
+Population Count instruction.  The default is @option{-mpopc}
+when targeting a CPU that supports such an instruction, such as Niagara-2 and
+later.
+
+@item -msubxc
+@itemx -mno-subxc
+@opindex msubxc
+@opindex mno-subxc
+With @option{-msubxc}, GCC generates code that takes advantage of the UltraSPARC
+Subtract-Extended-with-Carry instruction.  The default is @option{-msubxc}
+when targeting a CPU that supports such an instruction, such as Niagara-7 and
+later.
+
+@item -mfix-at697f
+@opindex mfix-at697f
+Enable the documented workaround for the single erratum of the Atmel AT697F
+processor (which corresponds to erratum #13 of the AT697E processor).
+
+@item -mfix-ut699
+@opindex mfix-ut699
+Enable the documented workarounds for the floating-point errata and the data
+cache nullify errata of the UT699 processor.
+
+@item -mfix-ut700
+@opindex mfix-ut700
+Enable the documented workaround for the back-to-back store errata of
+the UT699E/UT700 processor.
+
+@item -mfix-gr712rc
+@opindex mfix-gr712rc
+Enable the documented workaround for the back-to-back store errata of
+the GR712RC processor.
+@end table
+
+These @samp{-m} options are supported in addition to the above
+on SPARC-V9 processors in 64-bit environments:
+
+@table @gcctabopt
+@item -m32
+@itemx -m64
+@opindex m32
+@opindex m64
+Generate code for a 32-bit or 64-bit environment.
+The 32-bit environment sets int, long and pointer to 32 bits.
+The 64-bit environment sets int to 32 bits and long and pointer
+to 64 bits.
+
+@item -mcmodel=@var{which}
+@opindex mcmodel
+Set the code model to one of
+
+@table @samp
+@item medlow
+The Medium/Low code model: 64-bit addresses, programs
+must be linked in the low 32 bits of memory.  Programs can be statically
+or dynamically linked.
+
+@item medmid
+The Medium/Middle code model: 64-bit addresses, programs
+must be linked in the low 44 bits of memory, the text and data segments must
+be less than 2GB in size and the data segment must be located within 2GB of
+the text segment.
+
+@item medany
+The Medium/Anywhere code model: 64-bit addresses, programs
+may be linked anywhere in memory, the text and data segments must be less
+than 2GB in size and the data segment must be located within 2GB of the
+text segment.
+
+@item embmedany
+The Medium/Anywhere code model for embedded systems:
+64-bit addresses, the text and data segments must be less than 2GB in
+size, both starting anywhere in memory (determined at link time).  The
+global register %g4 points to the base of the data segment.  Programs
+are statically linked and PIC is not supported.
+@end table
+
+@item -mmemory-model=@var{mem-model}
+@opindex mmemory-model
+Set the memory model in force on the processor to one of
+
+@table @samp
+@item default
+The default memory model for the processor and operating system.
+
+@item rmo
+Relaxed Memory Order
+
+@item pso
+Partial Store Order
+
+@item tso
+Total Store Order
+
+@item sc
+Sequential Consistency
+@end table
+
+These memory models are formally defined in Appendix D of the SPARC-V9
+architecture manual, as set in the processor's @code{PSTATE.MM} field.
+
+@item -mstack-bias
+@itemx -mno-stack-bias
+@opindex mstack-bias
+@opindex mno-stack-bias
+With @option{-mstack-bias}, GCC assumes that the stack pointer, and
+frame pointer if present, are offset by @minus{}2047 which must be added back
+when making stack frame references.  This is the default in 64-bit mode.
+Otherwise, assume no such offset is present.
+@end table
+
+@node System V Options
+@subsection Options for System V
+
+These additional options are available on System V Release 4 for
+compatibility with other compilers on those systems:
+
+@table @gcctabopt
+@item -G
+@opindex G
+Create a shared object.
+It is recommended that @option{-symbolic} or @option{-shared} be used instead.
+
+@item -Qy
+@opindex Qy
+Identify the versions of each tool used by the compiler, in a
+@code{.ident} assembler directive in the output.
+
+@item -Qn
+@opindex Qn
+Refrain from adding @code{.ident} directives to the output file (this is
+the default).
+
+@item -YP,@var{dirs}
+@opindex YP
+Search the directories @var{dirs}, and no others, for libraries
+specified with @option{-l}.
+
+@item -Ym,@var{dir}
+@opindex Ym
+Look in the directory @var{dir} to find the M4 preprocessor.
+The assembler uses this option.
+@c This is supposed to go with a -Yd for predefined M4 macro files, but
+@c the generic assembler that comes with Solaris takes just -Ym.
+@end table
+
+@node V850 Options
+@subsection V850 Options
+@cindex V850 Options
+
+These @samp{-m} options are defined for V850 implementations:
+
+@table @gcctabopt
+@item -mlong-calls
+@itemx -mno-long-calls
+@opindex mlong-calls
+@opindex mno-long-calls
+Treat all calls as being far away (near).  If calls are assumed to be
+far away, the compiler always loads the function's address into a
+register, and calls indirect through the pointer.
+
+@item -mno-ep
+@itemx -mep
+@opindex mno-ep
+@opindex mep
+Do not optimize (do optimize) basic blocks that use the same index
+pointer 4 or more times to copy pointer into the @code{ep} register, and
+use the shorter @code{sld} and @code{sst} instructions.  The @option{-mep}
+option is on by default if you optimize.
+
+@item -mno-prolog-function
+@itemx -mprolog-function
+@opindex mno-prolog-function
+@opindex mprolog-function
+Do not use (do use) external functions to save and restore registers
+at the prologue and epilogue of a function.  The external functions
+are slower, but use less code space if more than one function saves
+the same number of registers.  The @option{-mprolog-function} option
+is on by default if you optimize.
+
+@item -mspace
+@opindex mspace
+Try to make the code as small as possible.  At present, this just turns
+on the @option{-mep} and @option{-mprolog-function} options.
+
+@item -mtda=@var{n}
+@opindex mtda
+Put static or global variables whose size is @var{n} bytes or less into
+the tiny data area that register @code{ep} points to.  The tiny data
+area can hold up to 256 bytes in total (128 bytes for byte references).
+
+@item -msda=@var{n}
+@opindex msda
+Put static or global variables whose size is @var{n} bytes or less into
+the small data area that register @code{gp} points to.  The small data
+area can hold up to 64 kilobytes.
+
+@item -mzda=@var{n}
+@opindex mzda
+Put static or global variables whose size is @var{n} bytes or less into
+the first 32 kilobytes of memory.
+
+@item -mv850
+@opindex mv850
+Specify that the target processor is the V850.
+
+@item -mv850e3v5
+@opindex mv850e3v5
+Specify that the target processor is the V850E3V5.  The preprocessor
+constant @code{__v850e3v5__} is defined if this option is used.
+
+@item -mv850e2v4
+@opindex mv850e2v4
+Specify that the target processor is the V850E3V5.  This is an alias for
+the @option{-mv850e3v5} option.
+
+@item -mv850e2v3
+@opindex mv850e2v3
+Specify that the target processor is the V850E2V3.  The preprocessor
+constant @code{__v850e2v3__} is defined if this option is used.
+
+@item -mv850e2
+@opindex mv850e2
+Specify that the target processor is the V850E2.  The preprocessor
+constant @code{__v850e2__} is defined if this option is used.
+
+@item -mv850e1
+@opindex mv850e1
+Specify that the target processor is the V850E1.  The preprocessor
+constants @code{__v850e1__} and @code{__v850e__} are defined if
+this option is used.
+
+@item -mv850es
+@opindex mv850es
+Specify that the target processor is the V850ES.  This is an alias for
+the @option{-mv850e1} option.
+
+@item -mv850e
+@opindex mv850e
+Specify that the target processor is the V850E@.  The preprocessor
+constant @code{__v850e__} is defined if this option is used.
+
+If neither @option{-mv850} nor @option{-mv850e} nor @option{-mv850e1}
+nor @option{-mv850e2} nor @option{-mv850e2v3} nor @option{-mv850e3v5}
+are defined then a default target processor is chosen and the
+relevant @samp{__v850*__} preprocessor constant is defined.
+
+The preprocessor constants @code{__v850} and @code{__v851__} are always
+defined, regardless of which processor variant is the target.
+
+@item -mdisable-callt
+@itemx -mno-disable-callt
+@opindex mdisable-callt
+@opindex mno-disable-callt
+This option suppresses generation of the @code{CALLT} instruction for the
+v850e, v850e1, v850e2, v850e2v3 and v850e3v5 flavors of the v850
+architecture.
+
+This option is enabled by default when the RH850 ABI is
+in use (see @option{-mrh850-abi}), and disabled by default when the
+GCC ABI is in use.  If @code{CALLT} instructions are being generated
+then the C preprocessor symbol @code{__V850_CALLT__} is defined.
+
+@item -mrelax
+@itemx -mno-relax
+@opindex mrelax
+@opindex mno-relax
+Pass on (or do not pass on) the @option{-mrelax} command-line option
+to the assembler.
+
+@item -mlong-jumps
+@itemx -mno-long-jumps
+@opindex mlong-jumps
+@opindex mno-long-jumps
+Disable (or re-enable) the generation of PC-relative jump instructions.
+
+@item -msoft-float
+@itemx -mhard-float
+@opindex msoft-float
+@opindex mhard-float
+Disable (or re-enable) the generation of hardware floating point
+instructions.  This option is only significant when the target
+architecture is @samp{V850E2V3} or higher.  If hardware floating point
+instructions are being generated then the C preprocessor symbol
+@code{__FPU_OK__} is defined, otherwise the symbol
+@code{__NO_FPU__} is defined.
+
+@item -mloop
+@opindex mloop
+Enables the use of the e3v5 LOOP instruction.  The use of this
+instruction is not enabled by default when the e3v5 architecture is
+selected because its use is still experimental.
+
+@item -mrh850-abi
+@itemx -mghs
+@opindex mrh850-abi
+@opindex mghs
+Enables support for the RH850 version of the V850 ABI.  This is the
+default.  With this version of the ABI the following rules apply:
+
+@itemize
+@item
+Integer sized structures and unions are returned via a memory pointer
+rather than a register.
+
+@item
+Large structures and unions (more than 8 bytes in size) are passed by
+value.
+
+@item
+Functions are aligned to 16-bit boundaries.
+
+@item
+The @option{-m8byte-align} command-line option is supported.
+
+@item
+The @option{-mdisable-callt} command-line option is enabled by
+default.  The @option{-mno-disable-callt} command-line option is not
+supported.
+@end itemize
+
+When this version of the ABI is enabled the C preprocessor symbol
+@code{__V850_RH850_ABI__} is defined.
+
+@item -mgcc-abi
+@opindex mgcc-abi
+Enables support for the old GCC version of the V850 ABI.  With this
+version of the ABI the following rules apply:
+
+@itemize
+@item
+Integer sized structures and unions are returned in register @code{r10}.
+
+@item
+Large structures and unions (more than 8 bytes in size) are passed by
+reference.
+
+@item
+Functions are aligned to 32-bit boundaries, unless optimizing for
+size.
+
+@item
+The @option{-m8byte-align} command-line option is not supported.
+
+@item
+The @option{-mdisable-callt} command-line option is supported but not
+enabled by default.
+@end itemize
+
+When this version of the ABI is enabled the C preprocessor symbol
+@code{__V850_GCC_ABI__} is defined.
+
+@item -m8byte-align
+@itemx -mno-8byte-align
+@opindex m8byte-align
+@opindex mno-8byte-align
+Enables support for @code{double} and @code{long long} types to be
+aligned on 8-byte boundaries.  The default is to restrict the
+alignment of all objects to at most 4-bytes.  When
+@option{-m8byte-align} is in effect the C preprocessor symbol
+@code{__V850_8BYTE_ALIGN__} is defined.
+
+@item -mbig-switch
+@opindex mbig-switch
+Generate code suitable for big switch tables.  Use this option only if
+the assembler/linker complain about out of range branches within a switch
+table.
+
+@item -mapp-regs
+@opindex mapp-regs
+This option causes r2 and r5 to be used in the code generated by
+the compiler.  This setting is the default.
+
+@item -mno-app-regs
+@opindex mno-app-regs
+This option causes r2 and r5 to be treated as fixed registers.
+
+@end table
+
+@node VAX Options
+@subsection VAX Options
+@cindex VAX options
+
+These @samp{-m} options are defined for the VAX:
+
+@table @gcctabopt
+@item -munix
+@opindex munix
+Do not output certain jump instructions (@code{aobleq} and so on)
+that the Unix assembler for the VAX cannot handle across long
+ranges.
+
+@item -mgnu
+@opindex mgnu
+Do output those jump instructions, on the assumption that the
+GNU assembler is being used.
+
+@item -mg
+@opindex mg
+Output code for G-format floating-point numbers instead of D-format.
+
+@item -mlra
+@itemx -mno-lra
+@opindex mlra
+@opindex mno-lra
+Enable Local Register Allocation.  This is still experimental for the VAX,
+so by default the compiler uses standard reload.
+@end table
+
+@node Visium Options
+@subsection Visium Options
+@cindex Visium options
+
+@table @gcctabopt
+
+@item -mdebug
+@opindex mdebug
+A program which performs file I/O and is destined to run on an MCM target
+should be linked with this option.  It causes the libraries libc.a and
+libdebug.a to be linked.  The program should be run on the target under
+the control of the GDB remote debugging stub.
+
+@item -msim
+@opindex msim
+A program which performs file I/O and is destined to run on the simulator
+should be linked with option.  This causes libraries libc.a and libsim.a to
+be linked.
+
+@item -mfpu
+@itemx -mhard-float
+@opindex mfpu
+@opindex mhard-float
+Generate code containing floating-point instructions.  This is the
+default.
+
+@item -mno-fpu
+@itemx -msoft-float
+@opindex mno-fpu
+@opindex msoft-float
+Generate code containing library calls for floating-point.
+
+@option{-msoft-float} changes the calling convention in the output file;
+therefore, it is only useful if you compile @emph{all} of a program with
+this option.  In particular, you need to compile @file{libgcc.a}, the
+library that comes with GCC, with @option{-msoft-float} in order for
+this to work.
+
+@item -mcpu=@var{cpu_type}
+@opindex mcpu
+Set the instruction set, register set, and instruction scheduling parameters
+for machine type @var{cpu_type}.  Supported values for @var{cpu_type} are
+@samp{mcm}, @samp{gr5} and @samp{gr6}.
+
+@samp{mcm} is a synonym of @samp{gr5} present for backward compatibility.
+
+By default (unless configured otherwise), GCC generates code for the GR5
+variant of the Visium architecture.  
+
+With @option{-mcpu=gr6}, GCC generates code for the GR6 variant of the Visium
+architecture.  The only difference from GR5 code is that the compiler will
+generate block move instructions.
+
+@item -mtune=@var{cpu_type}
+@opindex mtune
+Set the instruction scheduling parameters for machine type @var{cpu_type},
+but do not set the instruction set or register set that the option
+@option{-mcpu=@var{cpu_type}} would.
+
+@item -msv-mode
+@opindex msv-mode
+Generate code for the supervisor mode, where there are no restrictions on
+the access to general registers.  This is the default.
+
+@item -muser-mode
+@opindex muser-mode
+Generate code for the user mode, where the access to some general registers
+is forbidden: on the GR5, registers r24 to r31 cannot be accessed in this
+mode; on the GR6, only registers r29 to r31 are affected.
+@end table
+
+@node VMS Options
+@subsection VMS Options
+
+These @samp{-m} options are defined for the VMS implementations:
+
+@table @gcctabopt
+@item -mvms-return-codes
+@opindex mvms-return-codes
+Return VMS condition codes from @code{main}. The default is to return POSIX-style
+condition (e.g.@: error) codes.
+
+@item -mdebug-main=@var{prefix}
+@opindex mdebug-main=@var{prefix}
+Flag the first routine whose name starts with @var{prefix} as the main
+routine for the debugger.
+
+@item -mmalloc64
+@opindex mmalloc64
+Default to 64-bit memory allocation routines.
+
+@item -mpointer-size=@var{size}
+@opindex mpointer-size=@var{size}
+Set the default size of pointers. Possible options for @var{size} are
+@samp{32} or @samp{short} for 32 bit pointers, @samp{64} or @samp{long}
+for 64 bit pointers, and @samp{no} for supporting only 32 bit pointers.
+The later option disables @code{pragma pointer_size}.
+@end table
+
+@node VxWorks Options
+@subsection VxWorks Options
+@cindex VxWorks Options
+
+The options in this section are defined for all VxWorks targets.
+Options specific to the target hardware are listed with the other
+options for that target.
+
+@table @gcctabopt
+@item -mrtp
+@opindex mrtp
+GCC can generate code for both VxWorks kernels and real time processes
+(RTPs).  This option switches from the former to the latter.  It also
+defines the preprocessor macro @code{__RTP__}.
+
+@item -non-static
+@opindex non-static
+Link an RTP executable against shared libraries rather than static
+libraries.  The options @option{-static} and @option{-shared} can
+also be used for RTPs (@pxref{Link Options}); @option{-static}
+is the default.
+
+@item -Bstatic
+@itemx -Bdynamic
+@opindex Bstatic
+@opindex Bdynamic
+These options are passed down to the linker.  They are defined for
+compatibility with Diab.
+
+@item -Xbind-lazy
+@opindex Xbind-lazy
+Enable lazy binding of function calls.  This option is equivalent to
+@option{-Wl,-z,now} and is defined for compatibility with Diab.
+
+@item -Xbind-now
+@opindex Xbind-now
+Disable lazy binding of function calls.  This option is the default and
+is defined for compatibility with Diab.
+@end table
+
+@node x86 Options
+@subsection x86 Options
+@cindex x86 Options
+
+These @samp{-m} options are defined for the x86 family of computers.
+
+@table @gcctabopt
+
+@item -march=@var{cpu-type}
+@opindex march
+Generate instructions for the machine type @var{cpu-type}.  In contrast to
+@option{-mtune=@var{cpu-type}}, which merely tunes the generated code 
+for the specified @var{cpu-type}, @option{-march=@var{cpu-type}} allows GCC
+to generate code that may not run at all on processors other than the one
+indicated.  Specifying @option{-march=@var{cpu-type}} implies 
+@option{-mtune=@var{cpu-type}}, except where noted otherwise.
+
+The choices for @var{cpu-type} are:
+
+@table @samp
+@item native
+This selects the CPU to generate code for at compilation time by determining
+the processor type of the compiling machine.  Using @option{-march=native}
+enables all instruction subsets supported by the local machine (hence
+the result might not run on different machines).  Using @option{-mtune=native}
+produces code optimized for the local machine under the constraints
+of the selected instruction set.  
+
+@item x86-64
+A generic CPU with 64-bit extensions.
+
+@item x86-64-v2
+@itemx x86-64-v3
+@itemx x86-64-v4
+These choices for @var{cpu-type} select the corresponding
+micro-architecture level from the x86-64 psABI.  On ABIs other than
+the x86-64 psABI they select the same CPU features as the x86-64 psABI
+documents for the particular micro-architecture level.
+
+Since these @var{cpu-type} values do not have a corresponding
+@option{-mtune} setting, using @option{-march} with these values enables
+generic tuning.  Specific tuning can be enabled using the
+@option{-mtune=@var{other-cpu-type}} option with an appropriate
+@var{other-cpu-type} value.
+
+@item i386
+Original Intel i386 CPU@.
+
+@item i486
+Intel i486 CPU@.  (No scheduling is implemented for this chip.)
+
+@item i586
+@itemx pentium
+Intel Pentium CPU with no MMX support.
+
+@item lakemont
+Intel Lakemont MCU, based on Intel Pentium CPU.
+
+@item pentium-mmx
+Intel Pentium MMX CPU, based on Pentium core with MMX instruction set support.
+
+@item pentiumpro
+Intel Pentium Pro CPU@.
+
+@item i686
+When used with @option{-march}, the Pentium Pro
+instruction set is used, so the code runs on all i686 family chips.
+When used with @option{-mtune}, it has the same meaning as @samp{generic}.
+
+@item pentium2
+Intel Pentium II CPU, based on Pentium Pro core with MMX and FXSR instruction
+set support.
+
+@item pentium3
+@itemx pentium3m
+Intel Pentium III CPU, based on Pentium Pro core with MMX, FXSR and SSE
+instruction set support.
+
+@item pentium-m
+Intel Pentium M; low-power version of Intel Pentium III CPU
+with MMX, SSE, SSE2 and FXSR instruction set support.  Used by Centrino
+notebooks.
+
+@item pentium4
+@itemx pentium4m
+Intel Pentium 4 CPU with MMX, SSE, SSE2 and FXSR instruction set support.
+
+@item prescott
+Improved version of Intel Pentium 4 CPU with MMX, SSE, SSE2, SSE3 and FXSR
+instruction set support.
+
+@item nocona
+Improved version of Intel Pentium 4 CPU with 64-bit extensions, MMX, SSE,
+SSE2, SSE3 and FXSR instruction set support.
+
+@item core2
+Intel Core 2 CPU with 64-bit extensions, MMX, SSE, SSE2, SSE3, SSSE3, CX16,
+SAHF and FXSR instruction set support.
+
+@item nehalem
+Intel Nehalem CPU with 64-bit extensions, MMX, SSE, SSE2, SSE3, SSSE3,
+SSE4.1, SSE4.2, POPCNT, CX16, SAHF and FXSR instruction set support.
+
+@item westmere
+Intel Westmere CPU with 64-bit extensions, MMX, SSE, SSE2, SSE3, SSSE3,
+SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR and PCLMUL instruction set support.
+
+@item sandybridge
+Intel Sandy Bridge CPU with 64-bit extensions, MMX, SSE, SSE2, SSE3, SSSE3,
+SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE and PCLMUL instruction set
+support.
+
+@item ivybridge
+Intel Ivy Bridge CPU with 64-bit extensions, MMX, SSE, SSE2, SSE3, SSSE3,
+SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL, FSGSBASE, RDRND
+and F16C instruction set support.
+
+@item haswell
+Intel Haswell CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3,
+SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL, FSGSBASE, RDRND,
+F16C, AVX2, BMI, BMI2, LZCNT, FMA, MOVBE and HLE instruction set support.
+
+@item broadwell
+Intel Broadwell CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3,
+SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL, FSGSBASE, RDRND,
+F16C, AVX2, BMI, BMI2, LZCNT, FMA, MOVBE, HLE, RDSEED, ADCX and PREFETCHW
+instruction set support.
+
+@item skylake
+Intel Skylake CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3,
+SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL, FSGSBASE, RDRND,
+F16C, AVX2, BMI, BMI2, LZCNT, FMA, MOVBE, HLE, RDSEED, ADCX, PREFETCHW, AES,
+CLFLUSHOPT, XSAVEC, XSAVES and SGX instruction set support.
+
+@item bonnell
+Intel Bonnell CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3 and SSSE3
+instruction set support.
+
+@item silvermont
+Intel Silvermont CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3,
+SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, PCLMUL, PREFETCHW and RDRND
+instruction set support.
+
+@item goldmont
+Intel Goldmont CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3,
+SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, PCLMUL, PREFETCHW, RDRND, AES, SHA,
+RDSEED, XSAVE, XSAVEC, XSAVES, XSAVEOPT, CLFLUSHOPT and FSGSBASE instruction
+set support.
+
+@item goldmont-plus
+Intel Goldmont Plus CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3,
+SSSE3, SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, PCLMUL, PREFETCHW, RDRND, AES,
+SHA, RDSEED, XSAVE, XSAVEC, XSAVES, XSAVEOPT, CLFLUSHOPT, FSGSBASE, PTWRITE,
+RDPID and SGX instruction set support.
+
+@item tremont
+Intel Tremont CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3,
+SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, PCLMUL, PREFETCHW, RDRND, AES, SHA,
+RDSEED, XSAVE, XSAVEC, XSAVES, XSAVEOPT, CLFLUSHOPT, FSGSBASE, PTWRITE, RDPID,
+SGX, CLWB, GFNI-SSE, MOVDIRI, MOVDIR64B, CLDEMOTE and WAITPKG instruction set
+support.
+
+@item sierraforest
+Intel Sierra Forest CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3,
+SSSE3, SSE4.1, SSE4.2, POPCNT, AES, PREFETCHW, PCLMUL, RDRND, XSAVE, XSAVEC,
+XSAVES, XSAVEOPT, FSGSBASE, PTWRITE, RDPID, SGX, GFNI-SSE, CLWB, MOVDIRI,
+MOVDIR64B, CLDEMOTE, WAITPKG, ADCX, AVX, AVX2, BMI, BMI2, F16C, FMA, LZCNT,
+PCONFIG, PKU, VAES, VPCLMULQDQ, SERIALIZE, HRESET, KL, WIDEKL, AVX-VNNI,
+AVXIFMA, AVXVNNIINT8, AVXNECONVERT and CMPCCXADD instruction set support.
+
+@item grandridge
+Intel Grand Ridge CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3,
+SSSE3, SSE4.1, SSE4.2, POPCNT, AES, PREFETCHW, PCLMUL, RDRND, XSAVE, XSAVEC,
+XSAVES, XSAVEOPT, FSGSBASE, PTWRITE, RDPID, SGX, GFNI-SSE, CLWB, MOVDIRI,
+MOVDIR64B, CLDEMOTE, WAITPKG, ADCX, AVX, AVX2, BMI, BMI2, F16C, FMA, LZCNT,
+PCONFIG, PKU, VAES, VPCLMULQDQ, SERIALIZE, HRESET, KL, WIDEKL, AVX-VNNI,
+AVXIFMA, AVXVNNIINT8, AVXNECONVERT, CMPCCXADD and RAOINT instruction set
+support.
+
+@item knl
+Intel Knight's Landing CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3,
+SSSE3, SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL, FSGSBASE,
+RDRND, F16C, AVX2, BMI, BMI2, LZCNT, FMA, MOVBE, HLE, RDSEED, ADCX, PREFETCHW,
+AVX512PF, AVX512ER, AVX512F, AVX512CD and PREFETCHWT1 instruction set support.
+
+@item knm
+Intel Knights Mill CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3,
+SSSE3, SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL, FSGSBASE,
+RDRND, F16C, AVX2, BMI, BMI2, LZCNT, FMA, MOVBE, HLE, RDSEED, ADCX, PREFETCHW,
+AVX512PF, AVX512ER, AVX512F, AVX512CD and PREFETCHWT1, AVX5124VNNIW,
+AVX5124FMAPS and AVX512VPOPCNTDQ instruction set support.
+
+@item skylake-avx512
+Intel Skylake Server CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3,
+SSSE3, SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL, FSGSBASE,
+RDRND, F16C, AVX2, BMI, BMI2, LZCNT, FMA, MOVBE, HLE, RDSEED, ADCX, PREFETCHW,
+AES, CLFLUSHOPT, XSAVEC, XSAVES, SGX, AVX512F, CLWB, AVX512VL, AVX512BW,
+AVX512DQ and AVX512CD instruction set support.
+
+@item cannonlake
+Intel Cannonlake Server CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2,
+SSE3, SSSE3, SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL,
+FSGSBASE, RDRND, F16C, AVX2, BMI, BMI2, LZCNT, FMA, MOVBE, HLE, RDSEED, ADCX,
+PREFETCHW, AES, CLFLUSHOPT, XSAVEC, XSAVES, SGX, AVX512F, AVX512VL, AVX512BW,
+AVX512DQ, AVX512CD, PKU, AVX512VBMI, AVX512IFMA and SHA instruction set
+support.
+
+@item icelake-client
+Intel Icelake Client CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3,
+SSSE3, SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL, FSGSBASE,
+RDRND, F16C, AVX2, BMI, BMI2, LZCNT, FMA, MOVBE, HLE, RDSEED, ADCX, PREFETCHW,
+AES, CLFLUSHOPT, XSAVEC, XSAVES, SGX, AVX512F, AVX512VL, AVX512BW, AVX512DQ,
+AVX512CD, PKU, AVX512VBMI, AVX512IFMA, SHA, AVX512VNNI, GFNI, VAES, AVX512VBMI2
+, VPCLMULQDQ, AVX512BITALG, RDPID and AVX512VPOPCNTDQ instruction set support.
+
+@item icelake-server
+Intel Icelake Server CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3,
+SSSE3, SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL, FSGSBASE,
+RDRND, F16C, AVX2, BMI, BMI2, LZCNT, FMA, MOVBE, HLE, RDSEED, ADCX, PREFETCHW,
+AES, CLFLUSHOPT, XSAVEC, XSAVES, SGX, AVX512F, AVX512VL, AVX512BW, AVX512DQ,
+AVX512CD, PKU, AVX512VBMI, AVX512IFMA, SHA, AVX512VNNI, GFNI, VAES, AVX512VBMI2
+, VPCLMULQDQ, AVX512BITALG, RDPID, AVX512VPOPCNTDQ, PCONFIG, WBNOINVD and CLWB
+instruction set support.
+
+@item cascadelake
+Intel Cascadelake CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3,
+SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL, FSGSBASE, RDRND,
+F16C, AVX2, BMI, BMI2, LZCNT, FMA, MOVBE, HLE, RDSEED, ADCX, PREFETCHW, AES,
+CLFLUSHOPT, XSAVEC, XSAVES, SGX, AVX512F, CLWB, AVX512VL, AVX512BW, AVX512DQ,
+AVX512CD and AVX512VNNI instruction set support.
+
+@item cooperlake
+Intel cooperlake CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3,
+SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL, FSGSBASE, RDRND,
+F16C, AVX2, BMI, BMI2, LZCNT, FMA, MOVBE, HLE, RDSEED, ADCX, PREFETCHW, AES,
+CLFLUSHOPT, XSAVEC, XSAVES, SGX, AVX512F, CLWB, AVX512VL, AVX512BW, AVX512DQ,
+AVX512CD, AVX512VNNI and AVX512BF16 instruction set support.
+
+@item tigerlake
+Intel Tigerlake CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3,
+SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL, FSGSBASE, RDRND,
+F16C, AVX2, BMI, BMI2, LZCNT, FMA, MOVBE, HLE, RDSEED, ADCX, PREFETCHW, AES,
+CLFLUSHOPT, XSAVEC, XSAVES, SGX, AVX512F, AVX512VL, AVX512BW, AVX512DQ, AVX512CD
+PKU, AVX512VBMI, AVX512IFMA, SHA, AVX512VNNI, GFNI, VAES, AVX512VBMI2,
+VPCLMULQDQ, AVX512BITALG, RDPID, AVX512VPOPCNTDQ, MOVDIRI, MOVDIR64B, CLWB,
+AVX512VP2INTERSECT and KEYLOCKER instruction set support.
+
+@item sapphirerapids
+Intel sapphirerapids CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3,
+SSSE3, SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL, FSGSBASE,
+RDRND, F16C, AVX2, BMI, BMI2, LZCNT, FMA, MOVBE, HLE, RDSEED, ADCX, PREFETCHW,
+AES, CLFLUSHOPT, XSAVEC, XSAVES, SGX, AVX512F, AVX512VL, AVX512BW, AVX512DQ,
+AVX512CD, PKU, AVX512VBMI, AVX512IFMA, SHA, AVX512VNNI, GFNI, VAES, AVX512VBMI2,
+VPCLMULQDQ, AVX512BITALG, RDPID, AVX512VPOPCNTDQ, PCONFIG, WBNOINVD, CLWB,
+MOVDIRI, MOVDIR64B, ENQCMD, CLDEMOTE, PTWRITE, WAITPKG, SERIALIZE, TSXLDTRK,
+UINTR, AMX-BF16, AMX-TILE, AMX-INT8, AVX-VNNI, AVX512FP16 and AVX512BF16
+instruction set support.
+
+@item alderlake
+Intel Alderlake CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3,
+SSE4.1, SSE4.2, POPCNT, AES, PREFETCHW, PCLMUL, RDRND, XSAVE, XSAVEC, XSAVES,
+XSAVEOPT, FSGSBASE, PTWRITE, RDPID, SGX, GFNI-SSE, CLWB, MOVDIRI, MOVDIR64B,
+CLDEMOTE, WAITPKG, ADCX, AVX, AVX2, BMI, BMI2, F16C, FMA, LZCNT, PCONFIG, PKU,
+VAES, VPCLMULQDQ, SERIALIZE, HRESET, KL, WIDEKL and AVX-VNNI instruction set
+support.
+
+@item rocketlake
+Intel Rocketlake CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3
+, SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL, FSGSBASE, RDRND,
+F16C, AVX2, BMI, BMI2, LZCNT, FMA, MOVBE, HLE, RDSEED, ADCX, PREFETCHW, AES,
+CLFLUSHOPT, XSAVEC, XSAVES, AVX512F, AVX512VL, AVX512BW, AVX512DQ, AVX512CD
+PKU, AVX512VBMI, AVX512IFMA, SHA, AVX512VNNI, GFNI, VAES, AVX512VBMI2,
+VPCLMULQDQ, AVX512BITALG, RDPID and AVX512VPOPCNTDQ instruction set support.
+
+@item graniterapids
+Intel graniterapids CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3,
+SSSE3, SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL, FSGSBASE,
+RDRND, F16C, AVX2, BMI, BMI2, LZCNT, FMA, MOVBE, HLE, RDSEED, ADCX, PREFETCHW,
+AES, CLFLUSHOPT, XSAVEC, XSAVES, SGX, AVX512F, AVX512VL, AVX512BW, AVX512DQ,
+AVX512CD, PKU, AVX512VBMI, AVX512IFMA, SHA, AVX512VNNI, GFNI, VAES, AVX512VBMI2,
+VPCLMULQDQ, AVX512BITALG, RDPID, AVX512VPOPCNTDQ, PCONFIG, WBNOINVD, CLWB,
+MOVDIRI, MOVDIR64B, AVX512VP2INTERSECT, ENQCMD, CLDEMOTE, PTWRITE, WAITPKG,
+SERIALIZE, TSXLDTRK, UINTR, AMX-BF16, AMX-TILE, AMX-INT8, AVX-VNNI, AVX512FP16,
+AVX512BF16, AMX-FP16 and PREFETCHI instruction set support.
+
+@item k6
+AMD K6 CPU with MMX instruction set support.
+
+@item k6-2
+@itemx k6-3
+Improved versions of AMD K6 CPU with MMX and 3DNow!@: instruction set support.
+
+@item athlon
+@itemx athlon-tbird
+AMD Athlon CPU with MMX, 3dNOW!, enhanced 3DNow!@: and SSE prefetch instructions
+support.
+
+@item athlon-4
+@itemx athlon-xp
+@itemx athlon-mp
+Improved AMD Athlon CPU with MMX, 3DNow!, enhanced 3DNow!@: and full SSE
+instruction set support.
+
+@item k8
+@itemx opteron
+@itemx athlon64
+@itemx athlon-fx
+Processors based on the AMD K8 core with x86-64 instruction set support,
+including the AMD Opteron, Athlon 64, and Athlon 64 FX processors.
+(This supersets MMX, SSE, SSE2, 3DNow!, enhanced 3DNow!@: and 64-bit
+instruction set extensions.)
+
+@item k8-sse3
+@itemx opteron-sse3
+@itemx athlon64-sse3
+Improved versions of AMD K8 cores with SSE3 instruction set support.
+
+@item amdfam10
+@itemx barcelona
+CPUs based on AMD Family 10h cores with x86-64 instruction set support.  (This
+supersets MMX, SSE, SSE2, SSE3, SSE4A, 3DNow!, enhanced 3DNow!, ABM and 64-bit
+instruction set extensions.)
+
+@item bdver1
+CPUs based on AMD Family 15h cores with x86-64 instruction set support.  (This
+supersets FMA4, AVX, XOP, LWP, AES, PCLMUL, CX16, MMX, SSE, SSE2, SSE3, SSE4A,
+SSSE3, SSE4.1, SSE4.2, ABM and 64-bit instruction set extensions.)
+
+@item bdver2
+AMD Family 15h core based CPUs with x86-64 instruction set support.  (This
+supersets BMI, TBM, F16C, FMA, FMA4, AVX, XOP, LWP, AES, PCLMUL, CX16, MMX,
+SSE, SSE2, SSE3, SSE4A, SSSE3, SSE4.1, SSE4.2, ABM and 64-bit instruction set 
+extensions.)
+
+@item bdver3
+AMD Family 15h core based CPUs with x86-64 instruction set support.  (This
+supersets BMI, TBM, F16C, FMA, FMA4, FSGSBASE, AVX, XOP, LWP, AES, 
+PCLMUL, CX16, MMX, SSE, SSE2, SSE3, SSE4A, SSSE3, SSE4.1, SSE4.2, ABM and
+64-bit instruction set extensions.)
+
+@item bdver4
+AMD Family 15h core based CPUs with x86-64 instruction set support.  (This
+supersets BMI, BMI2, TBM, F16C, FMA, FMA4, FSGSBASE, AVX, AVX2, XOP, LWP, 
+AES, PCLMUL, CX16, MOVBE, MMX, SSE, SSE2, SSE3, SSE4A, SSSE3, SSE4.1,
+SSE4.2, ABM and 64-bit instruction set extensions.)
+
+@item znver1
+AMD Family 17h core based CPUs with x86-64 instruction set support.  (This
+supersets BMI, BMI2, F16C, FMA, FSGSBASE, AVX, AVX2, ADCX, RDSEED, MWAITX,
+SHA, CLZERO, AES, PCLMUL, CX16, MOVBE, MMX, SSE, SSE2, SSE3, SSE4A, SSSE3,
+SSE4.1, SSE4.2, ABM, XSAVEC, XSAVES, CLFLUSHOPT, POPCNT, and 64-bit
+instruction set extensions.)
+
+@item znver2
+AMD Family 17h core based CPUs with x86-64 instruction set support. (This
+supersets BMI, BMI2, CLWB, F16C, FMA, FSGSBASE, AVX, AVX2, ADCX, RDSEED,
+MWAITX, SHA, CLZERO, AES, PCLMUL, CX16, MOVBE, MMX, SSE, SSE2, SSE3, SSE4A,
+SSSE3, SSE4.1, SSE4.2, ABM, XSAVEC, XSAVES, CLFLUSHOPT, POPCNT, RDPID,
+WBNOINVD, and 64-bit instruction set extensions.)
+
+@item znver3
+AMD Family 19h core based CPUs with x86-64 instruction set support. (This
+supersets BMI, BMI2, CLWB, F16C, FMA, FSGSBASE, AVX, AVX2, ADCX, RDSEED,
+MWAITX, SHA, CLZERO, AES, PCLMUL, CX16, MOVBE, MMX, SSE, SSE2, SSE3, SSE4A,
+SSSE3, SSE4.1, SSE4.2, ABM, XSAVEC, XSAVES, CLFLUSHOPT, POPCNT, RDPID,
+WBNOINVD, PKU, VPCLMULQDQ, VAES, and 64-bit instruction set extensions.)
+
+@item znver4
+AMD Family 19h core based CPUs with x86-64 instruction set support. (This
+supersets BMI, BMI2, CLWB, F16C, FMA, FSGSBASE, AVX, AVX2, ADCX, RDSEED,
+MWAITX, SHA, CLZERO, AES, PCLMUL, CX16, MOVBE, MMX, SSE, SSE2, SSE3, SSE4A,
+SSSE3, SSE4.1, SSE4.2, ABM, XSAVEC, XSAVES, CLFLUSHOPT, POPCNT, RDPID,
+WBNOINVD, PKU, VPCLMULQDQ, VAES, AVX512F, AVX512DQ, AVX512IFMA, AVX512CD,
+AVX512BW, AVX512VL, AVX512BF16, AVX512VBMI, AVX512VBMI2, AVX512VNNI,
+AVX512BITALG, AVX512VPOPCNTDQ, GFNI and 64-bit instruction set extensions.)
+
+@item btver1
+CPUs based on AMD Family 14h cores with x86-64 instruction set support.  (This
+supersets MMX, SSE, SSE2, SSE3, SSSE3, SSE4A, CX16, ABM and 64-bit
+instruction set extensions.)
+
+@item btver2
+CPUs based on AMD Family 16h cores with x86-64 instruction set support. This
+includes MOVBE, F16C, BMI, AVX, PCLMUL, AES, SSE4.2, SSE4.1, CX16, ABM,
+SSE4A, SSSE3, SSE3, SSE2, SSE, MMX and 64-bit instruction set extensions.
+
+@item winchip-c6
+IDT WinChip C6 CPU, dealt in same way as i486 with additional MMX instruction
+set support.
+
+@item winchip2
+IDT WinChip 2 CPU, dealt in same way as i486 with additional MMX and 3DNow!@:
+instruction set support.
+
+@item c3
+VIA C3 CPU with MMX and 3DNow!@: instruction set support.
+(No scheduling is implemented for this chip.)
+
+@item c3-2
+VIA C3-2 (Nehemiah/C5XL) CPU with MMX and SSE instruction set support.
+(No scheduling is implemented for this chip.)
+
+@item c7
+VIA C7 (Esther) CPU with MMX, SSE, SSE2 and SSE3 instruction set support.
+(No scheduling is implemented for this chip.)
+
+@item samuel-2
+VIA Eden Samuel 2 CPU with MMX and 3DNow!@: instruction set support.
+(No scheduling is implemented for this chip.)
+
+@item nehemiah
+VIA Eden Nehemiah CPU with MMX and SSE instruction set support.
+(No scheduling is implemented for this chip.)
+
+@item esther
+VIA Eden Esther CPU with MMX, SSE, SSE2 and SSE3 instruction set support.
+(No scheduling is implemented for this chip.)
+
+@item eden-x2
+VIA Eden X2 CPU with x86-64, MMX, SSE, SSE2 and SSE3 instruction set support.
+(No scheduling is implemented for this chip.)
+
+@item eden-x4
+VIA Eden X4 CPU with x86-64, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2,
+AVX and AVX2 instruction set support.
+(No scheduling is implemented for this chip.)
+
+@item nano
+Generic VIA Nano CPU with x86-64, MMX, SSE, SSE2, SSE3 and SSSE3
+instruction set support.
+(No scheduling is implemented for this chip.)
+
+@item nano-1000
+VIA Nano 1xxx CPU with x86-64, MMX, SSE, SSE2, SSE3 and SSSE3
+instruction set support.
+(No scheduling is implemented for this chip.)
+
+@item nano-2000
+VIA Nano 2xxx CPU with x86-64, MMX, SSE, SSE2, SSE3 and SSSE3
+instruction set support.
+(No scheduling is implemented for this chip.)
+
+@item nano-3000
+VIA Nano 3xxx CPU with x86-64, MMX, SSE, SSE2, SSE3, SSSE3 and SSE4.1
+instruction set support.
+(No scheduling is implemented for this chip.)
+
+@item nano-x2
+VIA Nano Dual Core CPU with x86-64, MMX, SSE, SSE2, SSE3, SSSE3 and SSE4.1
+instruction set support.
+(No scheduling is implemented for this chip.)
+
+@item nano-x4
+VIA Nano Quad Core CPU with x86-64, MMX, SSE, SSE2, SSE3, SSSE3 and SSE4.1
+instruction set support.
+(No scheduling is implemented for this chip.)
+
+@item lujiazui
+ZHAOXIN lujiazui CPU with x86-64, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1,
+SSE4.2, AVX, POPCNT, AES, PCLMUL, RDRND, XSAVE, XSAVEOPT, FSGSBASE, CX16,
+ABM, BMI, BMI2, F16C, FXSR, RDSEED instruction set support.
+
+@item geode
+AMD Geode embedded processor with MMX and 3DNow!@: instruction set support.
+@end table
+
+@item -mtune=@var{cpu-type}
+@opindex mtune
+Tune to @var{cpu-type} everything applicable about the generated code, except
+for the ABI and the set of available instructions.  
+While picking a specific @var{cpu-type} schedules things appropriately
+for that particular chip, the compiler does not generate any code that
+cannot run on the default machine type unless you use a
+@option{-march=@var{cpu-type}} option.
+For example, if GCC is configured for i686-pc-linux-gnu
+then @option{-mtune=pentium4} generates code that is tuned for Pentium 4
+but still runs on i686 machines.
+
+The choices for @var{cpu-type} are the same as for @option{-march}.
+In addition, @option{-mtune} supports 2 extra choices for @var{cpu-type}:
+
+@table @samp
+@item generic
+Produce code optimized for the most common IA32/@/AMD64/@/EM64T processors.
+If you know the CPU on which your code will run, then you should use
+the corresponding @option{-mtune} or @option{-march} option instead of
+@option{-mtune=generic}.  But, if you do not know exactly what CPU users
+of your application will have, then you should use this option.
+
+As new processors are deployed in the marketplace, the behavior of this
+option will change.  Therefore, if you upgrade to a newer version of
+GCC, code generation controlled by this option will change to reflect
+the processors
+that are most common at the time that version of GCC is released.
+
+There is no @option{-march=generic} option because @option{-march}
+indicates the instruction set the compiler can use, and there is no
+generic instruction set applicable to all processors.  In contrast,
+@option{-mtune} indicates the processor (or, in this case, collection of
+processors) for which the code is optimized.
+
+@item intel
+Produce code optimized for the most current Intel processors, which are
+Haswell and Silvermont for this version of GCC.  If you know the CPU
+on which your code will run, then you should use the corresponding
+@option{-mtune} or @option{-march} option instead of @option{-mtune=intel}.
+But, if you want your application performs better on both Haswell and
+Silvermont, then you should use this option.
+
+As new Intel processors are deployed in the marketplace, the behavior of
+this option will change.  Therefore, if you upgrade to a newer version of
+GCC, code generation controlled by this option will change to reflect
+the most current Intel processors at the time that version of GCC is
+released.
+
+There is no @option{-march=intel} option because @option{-march} indicates
+the instruction set the compiler can use, and there is no common
+instruction set applicable to all processors.  In contrast,
+@option{-mtune} indicates the processor (or, in this case, collection of
+processors) for which the code is optimized.
+@end table
+
+@item -mcpu=@var{cpu-type}
+@opindex mcpu
+A deprecated synonym for @option{-mtune}.
+
+@item -mfpmath=@var{unit}
+@opindex mfpmath
+Generate floating-point arithmetic for selected unit @var{unit}.  The choices
+for @var{unit} are:
+
+@table @samp
+@item 387
+Use the standard 387 floating-point coprocessor present on the majority of chips and
+emulated otherwise.  Code compiled with this option runs almost everywhere.
+The temporary results are computed in 80-bit precision instead of the precision
+specified by the type, resulting in slightly different results compared to most
+of other chips.  See @option{-ffloat-store} for more detailed description.
+
+This is the default choice for non-Darwin x86-32 targets.
+
+@item sse
+Use scalar floating-point instructions present in the SSE instruction set.
+This instruction set is supported by Pentium III and newer chips,
+and in the AMD line
+by Athlon-4, Athlon XP and Athlon MP chips.  The earlier version of the SSE
+instruction set supports only single-precision arithmetic, thus the double and
+extended-precision arithmetic are still done using 387.  A later version, present
+only in Pentium 4 and AMD x86-64 chips, supports double-precision
+arithmetic too.
+
+For the x86-32 compiler, you must use @option{-march=@var{cpu-type}}, @option{-msse}
+or @option{-msse2} switches to enable SSE extensions and make this option
+effective.  For the x86-64 compiler, these extensions are enabled by default.
+
+The resulting code should be considerably faster in the majority of cases and avoid
+the numerical instability problems of 387 code, but may break some existing
+code that expects temporaries to be 80 bits.
+
+This is the default choice for the x86-64 compiler, Darwin x86-32 targets,
+and the default choice for x86-32 targets with the SSE2 instruction set
+when @option{-ffast-math} is enabled.
+
+@item sse,387
+@itemx sse+387
+@itemx both
+Attempt to utilize both instruction sets at once.  This effectively doubles the
+amount of available registers, and on chips with separate execution units for
+387 and SSE the execution resources too.  Use this option with care, as it is
+still experimental, because the GCC register allocator does not model separate
+functional units well, resulting in unstable performance.
+@end table
+
+@item -masm=@var{dialect}
+@opindex masm=@var{dialect}
+Output assembly instructions using selected @var{dialect}.  Also affects
+which dialect is used for basic @code{asm} (@pxref{Basic Asm}) and
+extended @code{asm} (@pxref{Extended Asm}). Supported choices (in dialect
+order) are @samp{att} or @samp{intel}. The default is @samp{att}. Darwin does
+not support @samp{intel}.
+
+@item -mieee-fp
+@itemx -mno-ieee-fp
+@opindex mieee-fp
+@opindex mno-ieee-fp
+Control whether or not the compiler uses IEEE floating-point
+comparisons.  These correctly handle the case where the result of a
+comparison is unordered.
+
+@item -m80387
+@itemx -mhard-float
+@opindex 80387
+@opindex mhard-float
+Generate output containing 80387 instructions for floating point.
+
+@item -mno-80387
+@itemx -msoft-float
+@opindex no-80387
+@opindex msoft-float
+Generate output containing library calls for floating point.
+
+@strong{Warning:} the requisite libraries are not part of GCC@.
+Normally the facilities of the machine's usual C compiler are used, but
+this cannot be done directly in cross-compilation.  You must make your
+own arrangements to provide suitable library functions for
+cross-compilation.
+
+On machines where a function returns floating-point results in the 80387
+register stack, some floating-point opcodes may be emitted even if
+@option{-msoft-float} is used.
+
+@item -mno-fp-ret-in-387
+@opindex mno-fp-ret-in-387
+@opindex mfp-ret-in-387
+Do not use the FPU registers for return values of functions.
+
+The usual calling convention has functions return values of types
+@code{float} and @code{double} in an FPU register, even if there
+is no FPU@.  The idea is that the operating system should emulate
+an FPU@.
+
+The option @option{-mno-fp-ret-in-387} causes such values to be returned
+in ordinary CPU registers instead.
+
+@item -mno-fancy-math-387
+@opindex mno-fancy-math-387
+@opindex mfancy-math-387
+Some 387 emulators do not support the @code{sin}, @code{cos} and
+@code{sqrt} instructions for the 387.  Specify this option to avoid
+generating those instructions.
+This option is overridden when @option{-march}
+indicates that the target CPU always has an FPU and so the
+instruction does not need emulation.  These
+instructions are not generated unless you also use the
+@option{-funsafe-math-optimizations} switch.
+
+@item -malign-double
+@itemx -mno-align-double
+@opindex malign-double
+@opindex mno-align-double
+Control whether GCC aligns @code{double}, @code{long double}, and
+@code{long long} variables on a two-word boundary or a one-word
+boundary.  Aligning @code{double} variables on a two-word boundary
+produces code that runs somewhat faster on a Pentium at the
+expense of more memory.
+
+On x86-64, @option{-malign-double} is enabled by default.
+
+@strong{Warning:} if you use the @option{-malign-double} switch,
+structures containing the above types are aligned differently than
+the published application binary interface specifications for the x86-32
+and are not binary compatible with structures in code compiled
+without that switch.
+
+@item -m96bit-long-double
+@itemx -m128bit-long-double
+@opindex m96bit-long-double
+@opindex m128bit-long-double
+These switches control the size of @code{long double} type.  The x86-32
+application binary interface specifies the size to be 96 bits,
+so @option{-m96bit-long-double} is the default in 32-bit mode.
+
+Modern architectures (Pentium and newer) prefer @code{long double}
+to be aligned to an 8- or 16-byte boundary.  In arrays or structures
+conforming to the ABI, this is not possible.  So specifying
+@option{-m128bit-long-double} aligns @code{long double}
+to a 16-byte boundary by padding the @code{long double} with an additional
+32-bit zero.
+
+In the x86-64 compiler, @option{-m128bit-long-double} is the default choice as
+its ABI specifies that @code{long double} is aligned on 16-byte boundary.
+
+Notice that neither of these options enable any extra precision over the x87
+standard of 80 bits for a @code{long double}.
+
+@strong{Warning:} if you override the default value for your target ABI, this
+changes the size of 
+structures and arrays containing @code{long double} variables,
+as well as modifying the function calling convention for functions taking
+@code{long double}.  Hence they are not binary-compatible
+with code compiled without that switch.
+
+@item -mlong-double-64
+@itemx -mlong-double-80
+@itemx -mlong-double-128
+@opindex mlong-double-64
+@opindex mlong-double-80
+@opindex mlong-double-128
+These switches control the size of @code{long double} type. A size
+of 64 bits makes the @code{long double} type equivalent to the @code{double}
+type. This is the default for 32-bit Bionic C library.  A size
+of 128 bits makes the @code{long double} type equivalent to the
+@code{__float128} type. This is the default for 64-bit Bionic C library.
+
+@strong{Warning:} if you override the default value for your target ABI, this
+changes the size of
+structures and arrays containing @code{long double} variables,
+as well as modifying the function calling convention for functions taking
+@code{long double}.  Hence they are not binary-compatible
+with code compiled without that switch.
+
+@item -malign-data=@var{type}
+@opindex malign-data
+Control how GCC aligns variables.  Supported values for @var{type} are
+@samp{compat} uses increased alignment value compatible uses GCC 4.8
+and earlier, @samp{abi} uses alignment value as specified by the
+psABI, and @samp{cacheline} uses increased alignment value to match
+the cache line size.  @samp{compat} is the default.
+
+@item -mlarge-data-threshold=@var{threshold}
+@opindex mlarge-data-threshold
+When @option{-mcmodel=medium} is specified, data objects larger than
+@var{threshold} are placed in the large data section.  This value must be the
+same across all objects linked into the binary, and defaults to 65535.
+
+@item -mrtd
+@opindex mrtd
+Use a different function-calling convention, in which functions that
+take a fixed number of arguments return with the @code{ret @var{num}}
+instruction, which pops their arguments while returning.  This saves one
+instruction in the caller since there is no need to pop the arguments
+there.
+
+You can specify that an individual function is called with this calling
+sequence with the function attribute @code{stdcall}.  You can also
+override the @option{-mrtd} option by using the function attribute
+@code{cdecl}.  @xref{Function Attributes}.
+
+@strong{Warning:} this calling convention is incompatible with the one
+normally used on Unix, so you cannot use it if you need to call
+libraries compiled with the Unix compiler.
+
+Also, you must provide function prototypes for all functions that
+take variable numbers of arguments (including @code{printf});
+otherwise incorrect code is generated for calls to those
+functions.
+
+In addition, seriously incorrect code results if you call a
+function with too many arguments.  (Normally, extra arguments are
+harmlessly ignored.)
+
+@item -mregparm=@var{num}
+@opindex mregparm
+Control how many registers are used to pass integer arguments.  By
+default, no registers are used to pass arguments, and at most 3
+registers can be used.  You can control this behavior for a specific
+function by using the function attribute @code{regparm}.
+@xref{Function Attributes}.
+
+@strong{Warning:} if you use this switch, and
+@var{num} is nonzero, then you must build all modules with the same
+value, including any libraries.  This includes the system libraries and
+startup modules.
+
+@item -msseregparm
+@opindex msseregparm
+Use SSE register passing conventions for float and double arguments
+and return values.  You can control this behavior for a specific
+function by using the function attribute @code{sseregparm}.
+@xref{Function Attributes}.
+
+@strong{Warning:} if you use this switch then you must build all
+modules with the same value, including any libraries.  This includes
+the system libraries and startup modules.
+
+@item -mvect8-ret-in-mem
+@opindex mvect8-ret-in-mem
+Return 8-byte vectors in memory instead of MMX registers.  This is the
+default on VxWorks to match the ABI of the Sun Studio compilers until
+version 12.  @emph{Only} use this option if you need to remain
+compatible with existing code produced by those previous compiler
+versions or older versions of GCC@.
+
+@item -mpc32
+@itemx -mpc64
+@itemx -mpc80
+@opindex mpc32
+@opindex mpc64
+@opindex mpc80
+
+Set 80387 floating-point precision to 32, 64 or 80 bits.  When @option{-mpc32}
+is specified, the significands of results of floating-point operations are
+rounded to 24 bits (single precision); @option{-mpc64} rounds the
+significands of results of floating-point operations to 53 bits (double
+precision) and @option{-mpc80} rounds the significands of results of
+floating-point operations to 64 bits (extended double precision), which is
+the default.  When this option is used, floating-point operations in higher
+precisions are not available to the programmer without setting the FPU
+control word explicitly.
+
+Setting the rounding of floating-point operations to less than the default
+80 bits can speed some programs by 2% or more.  Note that some mathematical
+libraries assume that extended-precision (80-bit) floating-point operations
+are enabled by default; routines in such libraries could suffer significant
+loss of accuracy, typically through so-called ``catastrophic cancellation'',
+when this option is used to set the precision to less than extended precision.
+
+@item -mstackrealign
+@opindex mstackrealign
+Realign the stack at entry.  On the x86, the @option{-mstackrealign}
+option generates an alternate prologue and epilogue that realigns the
+run-time stack if necessary.  This supports mixing legacy codes that keep
+4-byte stack alignment with modern codes that keep 16-byte stack alignment for
+SSE compatibility.  See also the attribute @code{force_align_arg_pointer},
+applicable to individual functions.
+
+@item -mpreferred-stack-boundary=@var{num}
+@opindex mpreferred-stack-boundary
+Attempt to keep the stack boundary aligned to a 2 raised to @var{num}
+byte boundary.  If @option{-mpreferred-stack-boundary} is not specified,
+the default is 4 (16 bytes or 128 bits).
+
+@strong{Warning:} When generating code for the x86-64 architecture with
+SSE extensions disabled, @option{-mpreferred-stack-boundary=3} can be
+used to keep the stack boundary aligned to 8 byte boundary.  Since
+x86-64 ABI require 16 byte stack alignment, this is ABI incompatible and
+intended to be used in controlled environment where stack space is
+important limitation.  This option leads to wrong code when functions
+compiled with 16 byte stack alignment (such as functions from a standard
+library) are called with misaligned stack.  In this case, SSE
+instructions may lead to misaligned memory access traps.  In addition,
+variable arguments are handled incorrectly for 16 byte aligned
+objects (including x87 long double and __int128), leading to wrong
+results.  You must build all modules with
+@option{-mpreferred-stack-boundary=3}, including any libraries.  This
+includes the system libraries and startup modules.
+
+@item -mincoming-stack-boundary=@var{num}
+@opindex mincoming-stack-boundary
+Assume the incoming stack is aligned to a 2 raised to @var{num} byte
+boundary.  If @option{-mincoming-stack-boundary} is not specified,
+the one specified by @option{-mpreferred-stack-boundary} is used.
+
+On Pentium and Pentium Pro, @code{double} and @code{long double} values
+should be aligned to an 8-byte boundary (see @option{-malign-double}) or
+suffer significant run time performance penalties.  On Pentium III, the
+Streaming SIMD Extension (SSE) data type @code{__m128} may not work
+properly if it is not 16-byte aligned.
+
+To ensure proper alignment of this values on the stack, the stack boundary
+must be as aligned as that required by any value stored on the stack.
+Further, every function must be generated such that it keeps the stack
+aligned.  Thus calling a function compiled with a higher preferred
+stack boundary from a function compiled with a lower preferred stack
+boundary most likely misaligns the stack.  It is recommended that
+libraries that use callbacks always use the default setting.
+
+This extra alignment does consume extra stack space, and generally
+increases code size.  Code that is sensitive to stack space usage, such
+as embedded systems and operating system kernels, may want to reduce the
+preferred alignment to @option{-mpreferred-stack-boundary=2}.
+
+@need 200
+@item -mmmx
+@opindex mmmx
+@need 200
+@itemx -msse
+@opindex msse
+@need 200
+@itemx -msse2
+@opindex msse2
+@need 200
+@itemx -msse3
+@opindex msse3
+@need 200
+@itemx -mssse3
+@opindex mssse3
+@need 200
+@itemx -msse4
+@opindex msse4
+@need 200
+@itemx -msse4a
+@opindex msse4a
+@need 200
+@itemx -msse4.1
+@opindex msse4.1
+@need 200
+@itemx -msse4.2
+@opindex msse4.2
+@need 200
+@itemx -mavx
+@opindex mavx
+@need 200
+@itemx -mavx2
+@opindex mavx2
+@need 200
+@itemx -mavx512f
+@opindex mavx512f
+@need 200
+@itemx -mavx512pf
+@opindex mavx512pf
+@need 200
+@itemx -mavx512er
+@opindex mavx512er
+@need 200
+@itemx -mavx512cd
+@opindex mavx512cd
+@need 200
+@itemx -mavx512vl
+@opindex mavx512vl
+@need 200
+@itemx -mavx512bw
+@opindex mavx512bw
+@need 200
+@itemx -mavx512dq
+@opindex mavx512dq
+@need 200
+@itemx -mavx512ifma
+@opindex mavx512ifma
+@need 200
+@itemx -mavx512vbmi
+@opindex mavx512vbmi
+@need 200
+@itemx -msha
+@opindex msha
+@need 200
+@itemx -maes
+@opindex maes
+@need 200
+@itemx -mpclmul
+@opindex mpclmul
+@need 200
+@itemx -mclflushopt
+@opindex mclflushopt
+@need 200
+@itemx -mclwb
+@opindex mclwb
+@need 200
+@itemx -mfsgsbase
+@opindex mfsgsbase
+@need 200
+@itemx -mptwrite
+@opindex mptwrite
+@need 200
+@itemx -mrdrnd
+@opindex mrdrnd
+@need 200
+@itemx -mf16c
+@opindex mf16c
+@need 200
+@itemx -mfma
+@opindex mfma
+@need 200
+@itemx -mpconfig
+@opindex mpconfig
+@need 200
+@itemx -mwbnoinvd
+@opindex mwbnoinvd
+@need 200
+@itemx -mfma4
+@opindex mfma4
+@need 200
+@itemx -mprfchw
+@opindex mprfchw
+@need 200
+@itemx -mrdpid
+@opindex mrdpid
+@need 200
+@itemx -mprefetchwt1
+@opindex mprefetchwt1
+@need 200
+@itemx -mrdseed
+@opindex mrdseed
+@need 200
+@itemx -msgx
+@opindex msgx
+@need 200
+@itemx -mxop
+@opindex mxop
+@need 200
+@itemx -mlwp
+@opindex mlwp
+@need 200
+@itemx -m3dnow
+@opindex m3dnow
+@need 200
+@itemx -m3dnowa
+@opindex m3dnowa
+@need 200
+@itemx -mpopcnt
+@opindex mpopcnt
+@need 200
+@itemx -mabm
+@opindex mabm
+@need 200
+@itemx -madx
+@opindex madx
+@need 200
+@itemx -mbmi
+@opindex mbmi
+@need 200
+@itemx -mbmi2
+@opindex mbmi2
+@need 200
+@itemx -mlzcnt
+@opindex mlzcnt
+@need 200
+@itemx -mfxsr
+@opindex mfxsr
+@need 200
+@itemx -mxsave
+@opindex mxsave
+@need 200
+@itemx -mxsaveopt
+@opindex mxsaveopt
+@need 200
+@itemx -mxsavec
+@opindex mxsavec
+@need 200
+@itemx -mxsaves
+@opindex mxsaves
+@need 200
+@itemx -mrtm
+@opindex mrtm
+@need 200
+@itemx -mhle
+@opindex mhle
+@need 200
+@itemx -mtbm
+@opindex mtbm
+@need 200
+@itemx -mmwaitx
+@opindex mmwaitx
+@need 200
+@itemx -mclzero
+@opindex mclzero
+@need 200
+@itemx -mpku
+@opindex mpku
+@need 200
+@itemx -mavx512vbmi2
+@opindex mavx512vbmi2
+@need 200
+@itemx -mavx512bf16
+@opindex mavx512bf16
+@need 200
+@itemx -mavx512fp16
+@opindex mavx512fp16
+@need 200
+@itemx -mgfni
+@opindex mgfni
+@need 200
+@itemx -mvaes
+@opindex mvaes
+@need 200
+@itemx -mwaitpkg
+@opindex mwaitpkg
+@need 200
+@itemx -mvpclmulqdq
+@opindex mvpclmulqdq
+@need 200
+@itemx -mavx512bitalg
+@opindex mavx512bitalg
+@need 200
+@itemx -mmovdiri
+@opindex mmovdiri
+@need 200
+@itemx -mmovdir64b
+@opindex mmovdir64b
+@need 200
+@itemx -menqcmd
+@opindex menqcmd
+@itemx -muintr
+@opindex muintr
+@need 200
+@itemx -mtsxldtrk
+@opindex mtsxldtrk
+@need 200
+@itemx -mavx512vpopcntdq
+@opindex mavx512vpopcntdq
+@need 200
+@itemx -mavx512vp2intersect
+@opindex mavx512vp2intersect
+@need 200
+@itemx -mavx5124fmaps
+@opindex mavx5124fmaps
+@need 200
+@itemx -mavx512vnni
+@opindex mavx512vnni
+@need 200
+@itemx -mavxvnni
+@opindex mavxvnni
+@need 200
+@itemx -mavx5124vnniw
+@opindex mavx5124vnniw
+@need 200
+@itemx -mcldemote
+@opindex mcldemote
+@need 200
+@itemx -mserialize
+@opindex mserialize
+@need 200
+@itemx -mamx-tile
+@opindex mamx-tile
+@need 200
+@itemx -mamx-int8
+@opindex mamx-int8
+@need 200
+@itemx -mamx-bf16
+@opindex mamx-bf16
+@need 200
+@itemx -mhreset
+@opindex mhreset
+@itemx -mkl
+@opindex mkl
+@need 200
+@itemx -mwidekl
+@opindex mwidekl
+@need 200
+@itemx -mavxifma
+@opindex mavxifma
+@need 200
+@itemx -mavxvnniint8
+@opindex mavxvnniint8
+@need 200
+@itemx -mavxneconvert
+@opindex mavxneconvert
+@need 200
+@itemx -mcmpccxadd
+@opindex mcmpccxadd
+@need 200
+@itemx -mamx-fp16
+@opindex mamx-fp16
+@need 200
+@itemx -mprefetchi
+@opindex mprefetchi
+@need 200
+@itemx -mraoint
+@opindex mraoint
+These switches enable the use of instructions in the MMX, SSE,
+SSE2, SSE3, SSSE3, SSE4, SSE4A, SSE4.1, SSE4.2, AVX, AVX2, AVX512F, AVX512PF,
+AVX512ER, AVX512CD, AVX512VL, AVX512BW, AVX512DQ, AVX512IFMA, AVX512VBMI, SHA,
+AES, PCLMUL, CLFLUSHOPT, CLWB, FSGSBASE, PTWRITE, RDRND, F16C, FMA, PCONFIG,
+WBNOINVD, FMA4, PREFETCHW, RDPID, PREFETCHWT1, RDSEED, SGX, XOP, LWP,
+3DNow!@:, enhanced 3DNow!@:, POPCNT, ABM, ADX, BMI, BMI2, LZCNT, FXSR, XSAVE,
+XSAVEOPT, XSAVEC, XSAVES, RTM, HLE, TBM, MWAITX, CLZERO, PKU, AVX512VBMI2,
+GFNI, VAES, WAITPKG, VPCLMULQDQ, AVX512BITALG, MOVDIRI, MOVDIR64B, AVX512BF16,
+ENQCMD, AVX512VPOPCNTDQ, AVX5124FMAPS, AVX512VNNI, AVX5124VNNIW, SERIALIZE,
+UINTR, HRESET, AMXTILE, AMXINT8, AMXBF16, KL, WIDEKL, AVXVNNI, AVX512FP16,
+AVXIFMA, AVXVNNIINT8, AVXNECONVERT, CMPCCXADD, AMX-FP16, PREFETCHI, RAOINT or
+CLDEMOTE extended instruction sets. Each has a corresponding @option{-mno-}
+option to disable use of these instructions.
+
+These extensions are also available as built-in functions: see
+@ref{x86 Built-in Functions}, for details of the functions enabled and
+disabled by these switches.
+
+To generate SSE/SSE2 instructions automatically from floating-point
+code (as opposed to 387 instructions), see @option{-mfpmath=sse}.
+
+GCC depresses SSEx instructions when @option{-mavx} is used. Instead, it
+generates new AVX instructions or AVX equivalence for all SSEx instructions
+when needed.
+
+These options enable GCC to use these extended instructions in
+generated code, even without @option{-mfpmath=sse}.  Applications that
+perform run-time CPU detection must compile separate files for each
+supported architecture, using the appropriate flags.  In particular,
+the file containing the CPU detection code should be compiled without
+these options.
+
+@item -mdump-tune-features
+@opindex mdump-tune-features
+This option instructs GCC to dump the names of the x86 performance 
+tuning features and default settings. The names can be used in 
+@option{-mtune-ctrl=@var{feature-list}}.
+
+@item -mtune-ctrl=@var{feature-list}
+@opindex mtune-ctrl=@var{feature-list}
+This option is used to do fine grain control of x86 code generation features.
+@var{feature-list} is a comma separated list of @var{feature} names. See also
+@option{-mdump-tune-features}. When specified, the @var{feature} is turned
+on if it is not preceded with @samp{^}, otherwise, it is turned off. 
+@option{-mtune-ctrl=@var{feature-list}} is intended to be used by GCC
+developers. Using it may lead to code paths not covered by testing and can
+potentially result in compiler ICEs or runtime errors.
+
+@item -mno-default
+@opindex mno-default
+This option instructs GCC to turn off all tunable features. See also 
+@option{-mtune-ctrl=@var{feature-list}} and @option{-mdump-tune-features}.
+
+@item -mcld
+@opindex mcld
+This option instructs GCC to emit a @code{cld} instruction in the prologue
+of functions that use string instructions.  String instructions depend on
+the DF flag to select between autoincrement or autodecrement mode.  While the
+ABI specifies the DF flag to be cleared on function entry, some operating
+systems violate this specification by not clearing the DF flag in their
+exception dispatchers.  The exception handler can be invoked with the DF flag
+set, which leads to wrong direction mode when string instructions are used.
+This option can be enabled by default on 32-bit x86 targets by configuring
+GCC with the @option{--enable-cld} configure option.  Generation of @code{cld}
+instructions can be suppressed with the @option{-mno-cld} compiler option
+in this case.
+
+@item -mvzeroupper
+@opindex mvzeroupper
+This option instructs GCC to emit a @code{vzeroupper} instruction
+before a transfer of control flow out of the function to minimize
+the AVX to SSE transition penalty as well as remove unnecessary @code{zeroupper}
+intrinsics.
+
+@item -mprefer-avx128
+@opindex mprefer-avx128
+This option instructs GCC to use 128-bit AVX instructions instead of
+256-bit AVX instructions in the auto-vectorizer.
+
+@item -mprefer-vector-width=@var{opt}
+@opindex mprefer-vector-width
+This option instructs GCC to use @var{opt}-bit vector width in instructions
+instead of default on the selected platform.
+
+@item -mmove-max=@var{bits}
+@opindex mmove-max
+This option instructs GCC to set the maximum number of bits can be
+moved from memory to memory efficiently to @var{bits}.  The valid
+@var{bits} are 128, 256 and 512.
+
+@item -mstore-max=@var{bits}
+@opindex mstore-max
+This option instructs GCC to set the maximum number of bits can be
+stored to memory efficiently to @var{bits}.  The valid @var{bits} are
+128, 256 and 512.
+
+@table @samp
+@item none
+No extra limitations applied to GCC other than defined by the selected platform.
+
+@item 128
+Prefer 128-bit vector width for instructions.
+
+@item 256
+Prefer 256-bit vector width for instructions.
+
+@item 512
+Prefer 512-bit vector width for instructions.
+@end table
+
+@item -mcx16
+@opindex mcx16
+This option enables GCC to generate @code{CMPXCHG16B} instructions in 64-bit
+code to implement compare-and-exchange operations on 16-byte aligned 128-bit
+objects.  This is useful for atomic updates of data structures exceeding one
+machine word in size.  The compiler uses this instruction to implement
+@ref{__sync Builtins}.  However, for @ref{__atomic Builtins} operating on
+128-bit integers, a library call is always used.
+
+@item -msahf
+@opindex msahf
+This option enables generation of @code{SAHF} instructions in 64-bit code.
+Early Intel Pentium 4 CPUs with Intel 64 support,
+prior to the introduction of Pentium 4 G1 step in December 2005,
+lacked the @code{LAHF} and @code{SAHF} instructions
+which are supported by AMD64.
+These are load and store instructions, respectively, for certain status flags.
+In 64-bit mode, the @code{SAHF} instruction is used to optimize @code{fmod},
+@code{drem}, and @code{remainder} built-in functions;
+see @ref{Other Builtins} for details.
+
+@item -mmovbe
+@opindex mmovbe
+This option enables use of the @code{movbe} instruction to implement
+@code{__builtin_bswap32} and @code{__builtin_bswap64}.
+
+@item -mshstk
+@opindex mshstk
+The @option{-mshstk} option enables shadow stack built-in functions
+from x86 Control-flow Enforcement Technology (CET).
+
+@item -mcrc32
+@opindex mcrc32
+This option enables built-in functions @code{__builtin_ia32_crc32qi},
+@code{__builtin_ia32_crc32hi}, @code{__builtin_ia32_crc32si} and
+@code{__builtin_ia32_crc32di} to generate the @code{crc32} machine instruction.
+
+@item -mmwait
+@opindex mmwait
+This option enables built-in functions @code{__builtin_ia32_monitor},
+and @code{__builtin_ia32_mwait} to generate the @code{monitor} and
+@code{mwait} machine instructions.
+
+@item -mrecip
+@opindex mrecip
+This option enables use of @code{RCPSS} and @code{RSQRTSS} instructions
+(and their vectorized variants @code{RCPPS} and @code{RSQRTPS})
+with an additional Newton-Raphson step
+to increase precision instead of @code{DIVSS} and @code{SQRTSS}
+(and their vectorized
+variants) for single-precision floating-point arguments.  These instructions
+are generated only when @option{-funsafe-math-optimizations} is enabled
+together with @option{-ffinite-math-only} and @option{-fno-trapping-math}.
+Note that while the throughput of the sequence is higher than the throughput
+of the non-reciprocal instruction, the precision of the sequence can be
+decreased by up to 2 ulp (i.e.@: the inverse of 1.0 equals 0.99999994).
+
+Note that GCC implements @code{1.0f/sqrtf(@var{x})} in terms of @code{RSQRTSS}
+(or @code{RSQRTPS}) already with @option{-ffast-math} (or the above option
+combination), and doesn't need @option{-mrecip}.
+
+Also note that GCC emits the above sequence with additional Newton-Raphson step
+for vectorized single-float division and vectorized @code{sqrtf(@var{x})}
+already with @option{-ffast-math} (or the above option combination), and
+doesn't need @option{-mrecip}.
+
+@item -mrecip=@var{opt}
+@opindex mrecip=opt
+This option controls which reciprocal estimate instructions
+may be used.  @var{opt} is a comma-separated list of options, which may
+be preceded by a @samp{!} to invert the option:
+
+@table @samp
+@item all
+Enable all estimate instructions.
+
+@item default
+Enable the default instructions, equivalent to @option{-mrecip}.
+
+@item none
+Disable all estimate instructions, equivalent to @option{-mno-recip}.
+
+@item div
+Enable the approximation for scalar division.
+
+@item vec-div
+Enable the approximation for vectorized division.
+
+@item sqrt
+Enable the approximation for scalar square root.
+
+@item vec-sqrt
+Enable the approximation for vectorized square root.
+@end table
+
+So, for example, @option{-mrecip=all,!sqrt} enables
+all of the reciprocal approximations, except for square root.
+
+@item -mveclibabi=@var{type}
+@opindex mveclibabi
+Specifies the ABI type to use for vectorizing intrinsics using an
+external library.  Supported values for @var{type} are @samp{svml} 
+for the Intel short
+vector math library and @samp{acml} for the AMD math core library.
+To use this option, both @option{-ftree-vectorize} and
+@option{-funsafe-math-optimizations} have to be enabled, and an SVML or ACML 
+ABI-compatible library must be specified at link time.
+
+GCC currently emits calls to @code{vmldExp2},
+@code{vmldLn2}, @code{vmldLog102}, @code{vmldPow2},
+@code{vmldTanh2}, @code{vmldTan2}, @code{vmldAtan2}, @code{vmldAtanh2},
+@code{vmldCbrt2}, @code{vmldSinh2}, @code{vmldSin2}, @code{vmldAsinh2},
+@code{vmldAsin2}, @code{vmldCosh2}, @code{vmldCos2}, @code{vmldAcosh2},
+@code{vmldAcos2}, @code{vmlsExp4}, @code{vmlsLn4},
+@code{vmlsLog104}, @code{vmlsPow4}, @code{vmlsTanh4}, @code{vmlsTan4},
+@code{vmlsAtan4}, @code{vmlsAtanh4}, @code{vmlsCbrt4}, @code{vmlsSinh4},
+@code{vmlsSin4}, @code{vmlsAsinh4}, @code{vmlsAsin4}, @code{vmlsCosh4},
+@code{vmlsCos4}, @code{vmlsAcosh4} and @code{vmlsAcos4} for corresponding
+function type when @option{-mveclibabi=svml} is used, and @code{__vrd2_sin},
+@code{__vrd2_cos}, @code{__vrd2_exp}, @code{__vrd2_log}, @code{__vrd2_log2},
+@code{__vrd2_log10}, @code{__vrs4_sinf}, @code{__vrs4_cosf},
+@code{__vrs4_expf}, @code{__vrs4_logf}, @code{__vrs4_log2f},
+@code{__vrs4_log10f} and @code{__vrs4_powf} for the corresponding function type
+when @option{-mveclibabi=acml} is used.  
+
+@item -mabi=@var{name}
+@opindex mabi
+Generate code for the specified calling convention.  Permissible values
+are @samp{sysv} for the ABI used on GNU/Linux and other systems, and
+@samp{ms} for the Microsoft ABI.  The default is to use the Microsoft
+ABI when targeting Microsoft Windows and the SysV ABI on all other systems.
+You can control this behavior for specific functions by
+using the function attributes @code{ms_abi} and @code{sysv_abi}.
+@xref{Function Attributes}.
+
+@item -mforce-indirect-call
+@opindex mforce-indirect-call
+Force all calls to functions to be indirect. This is useful
+when using Intel Processor Trace where it generates more precise timing
+information for function calls.
+
+@item -mmanual-endbr
+@opindex mmanual-endbr
+Insert ENDBR instruction at function entry only via the @code{cf_check}
+function attribute. This is useful when used with the option
+@option{-fcf-protection=branch} to control ENDBR insertion at the
+function entry.
+
+@item -mcet-switch
+@opindex mcet-switch
+By default, CET instrumentation is turned off on switch statements that
+use a jump table and indirect branch track is disabled.  Since jump
+tables are stored in read-only memory, this does not result in a direct
+loss of hardening.  But if the jump table index is attacker-controlled,
+the indirect jump may not be constrained by CET.  This option turns on
+CET instrumentation to enable indirect branch track for switch statements
+with jump tables which leads to the jump targets reachable via any indirect
+jumps.
+
+@item -mcall-ms2sysv-xlogues
+@opindex mcall-ms2sysv-xlogues
+@opindex mno-call-ms2sysv-xlogues
+Due to differences in 64-bit ABIs, any Microsoft ABI function that calls a
+System V ABI function must consider RSI, RDI and XMM6-15 as clobbered.  By
+default, the code for saving and restoring these registers is emitted inline,
+resulting in fairly lengthy prologues and epilogues.  Using
+@option{-mcall-ms2sysv-xlogues} emits prologues and epilogues that
+use stubs in the static portion of libgcc to perform these saves and restores,
+thus reducing function size at the cost of a few extra instructions.
+
+@item -mtls-dialect=@var{type}
+@opindex mtls-dialect
+Generate code to access thread-local storage using the @samp{gnu} or
+@samp{gnu2} conventions.  @samp{gnu} is the conservative default;
+@samp{gnu2} is more efficient, but it may add compile- and run-time
+requirements that cannot be satisfied on all systems.
+
+@item -mpush-args
+@itemx -mno-push-args
+@opindex mpush-args
+@opindex mno-push-args
+Use PUSH operations to store outgoing parameters.  This method is shorter
+and usually equally fast as method using SUB/MOV operations and is enabled
+by default.  In some cases disabling it may improve performance because of
+improved scheduling and reduced dependencies.
+
+@item -maccumulate-outgoing-args
+@opindex maccumulate-outgoing-args
+If enabled, the maximum amount of space required for outgoing arguments is
+computed in the function prologue.  This is faster on most modern CPUs
+because of reduced dependencies, improved scheduling and reduced stack usage
+when the preferred stack boundary is not equal to 2.  The drawback is a notable
+increase in code size.  This switch implies @option{-mno-push-args}.
+
+@item -mthreads
+@opindex mthreads
+Support thread-safe exception handling on MinGW.  Programs that rely
+on thread-safe exception handling must compile and link all code with the
+@option{-mthreads} option.  When compiling, @option{-mthreads} defines
+@option{-D_MT}; when linking, it links in a special thread helper library
+@option{-lmingwthrd} which cleans up per-thread exception-handling data.
+
+@item -mms-bitfields
+@itemx -mno-ms-bitfields
+@opindex mms-bitfields
+@opindex mno-ms-bitfields
+
+Enable/disable bit-field layout compatible with the native Microsoft
+Windows compiler.  
+
+If @code{packed} is used on a structure, or if bit-fields are used,
+it may be that the Microsoft ABI lays out the structure differently
+than the way GCC normally does.  Particularly when moving packed
+data between functions compiled with GCC and the native Microsoft compiler
+(either via function call or as data in a file), it may be necessary to access
+either format.
+
+This option is enabled by default for Microsoft Windows
+targets.  This behavior can also be controlled locally by use of variable
+or type attributes.  For more information, see @ref{x86 Variable Attributes}
+and @ref{x86 Type Attributes}.
+
+The Microsoft structure layout algorithm is fairly simple with the exception
+of the bit-field packing.  
+The padding and alignment of members of structures and whether a bit-field 
+can straddle a storage-unit boundary are determine by these rules:
+
+@enumerate
+@item Structure members are stored sequentially in the order in which they are
+declared: the first member has the lowest memory address and the last member
+the highest.
+
+@item Every data object has an alignment requirement.  The alignment requirement
+for all data except structures, unions, and arrays is either the size of the
+object or the current packing size (specified with either the
+@code{aligned} attribute or the @code{pack} pragma),
+whichever is less.  For structures, unions, and arrays,
+the alignment requirement is the largest alignment requirement of its members.
+Every object is allocated an offset so that:
+
+@smallexample
+offset % alignment_requirement == 0
+@end smallexample
+
+@item Adjacent bit-fields are packed into the same 1-, 2-, or 4-byte allocation
+unit if the integral types are the same size and if the next bit-field fits
+into the current allocation unit without crossing the boundary imposed by the
+common alignment requirements of the bit-fields.
+@end enumerate
+
+MSVC interprets zero-length bit-fields in the following ways:
+
+@enumerate
+@item If a zero-length bit-field is inserted between two bit-fields that
+are normally coalesced, the bit-fields are not coalesced.
+
+For example:
+
+@smallexample
+struct
+ @{
+   unsigned long bf_1 : 12;
+   unsigned long : 0;
+   unsigned long bf_2 : 12;
+ @} t1;
+@end smallexample
+
+@noindent
+The size of @code{t1} is 8 bytes with the zero-length bit-field.  If the
+zero-length bit-field were removed, @code{t1}'s size would be 4 bytes.
+
+@item If a zero-length bit-field is inserted after a bit-field, @code{foo}, and the
+alignment of the zero-length bit-field is greater than the member that follows it,
+@code{bar}, @code{bar} is aligned as the type of the zero-length bit-field.
+
+For example:
+
+@smallexample
+struct
+ @{
+   char foo : 4;
+   short : 0;
+   char bar;
+ @} t2;
+
+struct
+ @{
+   char foo : 4;
+   short : 0;
+   double bar;
+ @} t3;
+@end smallexample
+
+@noindent
+For @code{t2}, @code{bar} is placed at offset 2, rather than offset 1.
+Accordingly, the size of @code{t2} is 4.  For @code{t3}, the zero-length
+bit-field does not affect the alignment of @code{bar} or, as a result, the size
+of the structure.
+
+Taking this into account, it is important to note the following:
+
+@enumerate
+@item If a zero-length bit-field follows a normal bit-field, the type of the
+zero-length bit-field may affect the alignment of the structure as whole. For
+example, @code{t2} has a size of 4 bytes, since the zero-length bit-field follows a
+normal bit-field, and is of type short.
+
+@item Even if a zero-length bit-field is not followed by a normal bit-field, it may
+still affect the alignment of the structure:
+
+@smallexample
+struct
+ @{
+   char foo : 6;
+   long : 0;
+ @} t4;
+@end smallexample
+
+@noindent
+Here, @code{t4} takes up 4 bytes.
+@end enumerate
+
+@item Zero-length bit-fields following non-bit-field members are ignored:
+
+@smallexample
+struct
+ @{
+   char foo;
+   long : 0;
+   char bar;
+ @} t5;
+@end smallexample
+
+@noindent
+Here, @code{t5} takes up 2 bytes.
+@end enumerate
+
+
+@item -mno-align-stringops
+@opindex mno-align-stringops
+@opindex malign-stringops
+Do not align the destination of inlined string operations.  This switch reduces
+code size and improves performance in case the destination is already aligned,
+but GCC doesn't know about it.
+
+@item -minline-all-stringops
+@opindex minline-all-stringops
+By default GCC inlines string operations only when the destination is 
+known to be aligned to least a 4-byte boundary.  
+This enables more inlining and increases code
+size, but may improve performance of code that depends on fast
+@code{memcpy} and @code{memset} for short lengths.
+The option enables inline expansion of @code{strlen} for all
+pointer alignments.
+
+@item -minline-stringops-dynamically
+@opindex minline-stringops-dynamically
+For string operations of unknown size, use run-time checks with
+inline code for small blocks and a library call for large blocks.
+
+@item -mstringop-strategy=@var{alg}
+@opindex mstringop-strategy=@var{alg}
+Override the internal decision heuristic for the particular algorithm to use
+for inlining string operations.  The allowed values for @var{alg} are:
+
+@table @samp
+@item rep_byte
+@itemx rep_4byte
+@itemx rep_8byte
+Expand using i386 @code{rep} prefix of the specified size.
+
+@item byte_loop
+@itemx loop
+@itemx unrolled_loop
+Expand into an inline loop.
+
+@item libcall
+Always use a library call.
+@end table
+
+@item -mmemcpy-strategy=@var{strategy}
+@opindex mmemcpy-strategy=@var{strategy}
+Override the internal decision heuristic to decide if @code{__builtin_memcpy}
+should be inlined and what inline algorithm to use when the expected size
+of the copy operation is known. @var{strategy} 
+is a comma-separated list of @var{alg}:@var{max_size}:@var{dest_align} triplets. 
+@var{alg} is specified in @option{-mstringop-strategy}, @var{max_size} specifies
+the max byte size with which inline algorithm @var{alg} is allowed.  For the last
+triplet, the @var{max_size} must be @code{-1}. The @var{max_size} of the triplets
+in the list must be specified in increasing order.  The minimal byte size for 
+@var{alg} is @code{0} for the first triplet and @code{@var{max_size} + 1} of the 
+preceding range.
+
+@item -mmemset-strategy=@var{strategy}
+@opindex mmemset-strategy=@var{strategy}
+The option is similar to @option{-mmemcpy-strategy=} except that it is to control
+@code{__builtin_memset} expansion.
+
+@item -momit-leaf-frame-pointer
+@opindex momit-leaf-frame-pointer
+Don't keep the frame pointer in a register for leaf functions.  This
+avoids the instructions to save, set up, and restore frame pointers and
+makes an extra register available in leaf functions.  The option
+@option{-fomit-leaf-frame-pointer} removes the frame pointer for leaf functions,
+which might make debugging harder.
+
+@item -mtls-direct-seg-refs
+@itemx -mno-tls-direct-seg-refs
+@opindex mtls-direct-seg-refs
+Controls whether TLS variables may be accessed with offsets from the
+TLS segment register (@code{%gs} for 32-bit, @code{%fs} for 64-bit),
+or whether the thread base pointer must be added.  Whether or not this
+is valid depends on the operating system, and whether it maps the
+segment to cover the entire TLS area.
+
+For systems that use the GNU C Library, the default is on.
+
+@item -msse2avx
+@itemx -mno-sse2avx
+@opindex msse2avx
+Specify that the assembler should encode SSE instructions with VEX
+prefix.  The option @option{-mavx} turns this on by default.
+
+@item -mfentry
+@itemx -mno-fentry
+@opindex mfentry
+If profiling is active (@option{-pg}), put the profiling
+counter call before the prologue.
+Note: On x86 architectures the attribute @code{ms_hook_prologue}
+isn't possible at the moment for @option{-mfentry} and @option{-pg}.
+
+@item -mrecord-mcount
+@itemx -mno-record-mcount
+@opindex mrecord-mcount
+If profiling is active (@option{-pg}), generate a __mcount_loc section
+that contains pointers to each profiling call. This is useful for
+automatically patching and out calls.
+
+@item -mnop-mcount
+@itemx -mno-nop-mcount
+@opindex mnop-mcount
+If profiling is active (@option{-pg}), generate the calls to
+the profiling functions as NOPs. This is useful when they
+should be patched in later dynamically. This is likely only
+useful together with @option{-mrecord-mcount}.
+
+@item -minstrument-return=@var{type}
+@opindex minstrument-return
+Instrument function exit in -pg -mfentry instrumented functions with
+call to specified function. This only instruments true returns ending
+with ret, but not sibling calls ending with jump. Valid types
+are @var{none} to not instrument, @var{call} to generate a call to __return__,
+or @var{nop5} to generate a 5 byte nop.
+
+@item -mrecord-return
+@itemx -mno-record-return
+@opindex mrecord-return
+Generate a __return_loc section pointing to all return instrumentation code.
+
+@item -mfentry-name=@var{name}
+@opindex mfentry-name
+Set name of __fentry__ symbol called at function entry for -pg -mfentry functions.
+
+@item -mfentry-section=@var{name}
+@opindex mfentry-section
+Set name of section to record -mrecord-mcount calls (default __mcount_loc).
+
+@item -mskip-rax-setup
+@itemx -mno-skip-rax-setup
+@opindex mskip-rax-setup
+When generating code for the x86-64 architecture with SSE extensions
+disabled, @option{-mskip-rax-setup} can be used to skip setting up RAX
+register when there are no variable arguments passed in vector registers.
+
+@strong{Warning:} Since RAX register is used to avoid unnecessarily
+saving vector registers on stack when passing variable arguments, the
+impacts of this option are callees may waste some stack space,
+misbehave or jump to a random location.  GCC 4.4 or newer don't have
+those issues, regardless the RAX register value.
+
+@item -m8bit-idiv
+@itemx -mno-8bit-idiv
+@opindex m8bit-idiv
+On some processors, like Intel Atom, 8-bit unsigned integer divide is
+much faster than 32-bit/64-bit integer divide.  This option generates a
+run-time check.  If both dividend and divisor are within range of 0
+to 255, 8-bit unsigned integer divide is used instead of
+32-bit/64-bit integer divide.
+
+@item -mavx256-split-unaligned-load
+@itemx -mavx256-split-unaligned-store
+@opindex mavx256-split-unaligned-load
+@opindex mavx256-split-unaligned-store
+Split 32-byte AVX unaligned load and store.
+
+@item -mstack-protector-guard=@var{guard}
+@itemx -mstack-protector-guard-reg=@var{reg}
+@itemx -mstack-protector-guard-offset=@var{offset}
+@opindex mstack-protector-guard
+@opindex mstack-protector-guard-reg
+@opindex mstack-protector-guard-offset
+Generate stack protection code using canary at @var{guard}.  Supported
+locations are @samp{global} for global canary or @samp{tls} for per-thread
+canary in the TLS block (the default).  This option has effect only when
+@option{-fstack-protector} or @option{-fstack-protector-all} is specified.
+
+With the latter choice the options
+@option{-mstack-protector-guard-reg=@var{reg}} and
+@option{-mstack-protector-guard-offset=@var{offset}} furthermore specify
+which segment register (@code{%fs} or @code{%gs}) to use as base register
+for reading the canary, and from what offset from that base register.
+The default for those is as specified in the relevant ABI.
+
+@item -mgeneral-regs-only
+@opindex mgeneral-regs-only
+Generate code that uses only the general-purpose registers.  This
+prevents the compiler from using floating-point, vector, mask and bound
+registers.
+
+@item -mrelax-cmpxchg-loop
+@opindex mrelax-cmpxchg-loop
+Relax cmpxchg loop by emitting an early load and compare before cmpxchg,
+execute pause if load value is not expected. This reduces excessive
+cachline bouncing when and works for all atomic logic fetch builtins
+that generates compare and swap loop.
+
+@item -mindirect-branch=@var{choice}
+@opindex mindirect-branch
+Convert indirect call and jump with @var{choice}.  The default is
+@samp{keep}, which keeps indirect call and jump unmodified.
+@samp{thunk} converts indirect call and jump to call and return thunk.
+@samp{thunk-inline} converts indirect call and jump to inlined call
+and return thunk.  @samp{thunk-extern} converts indirect call and jump
+to external call and return thunk provided in a separate object file.
+You can control this behavior for a specific function by using the
+function attribute @code{indirect_branch}.  @xref{Function Attributes}.
+
+Note that @option{-mcmodel=large} is incompatible with
+@option{-mindirect-branch=thunk} and
+@option{-mindirect-branch=thunk-extern} since the thunk function may
+not be reachable in the large code model.
+
+Note that @option{-mindirect-branch=thunk-extern} is compatible with
+@option{-fcf-protection=branch} since the external thunk can be made
+to enable control-flow check.
+
+@item -mfunction-return=@var{choice}
+@opindex mfunction-return
+Convert function return with @var{choice}.  The default is @samp{keep},
+which keeps function return unmodified.  @samp{thunk} converts function
+return to call and return thunk.  @samp{thunk-inline} converts function
+return to inlined call and return thunk.  @samp{thunk-extern} converts
+function return to external call and return thunk provided in a separate
+object file.  You can control this behavior for a specific function by
+using the function attribute @code{function_return}.
+@xref{Function Attributes}.
+
+Note that @option{-mindirect-return=thunk-extern} is compatible with
+@option{-fcf-protection=branch} since the external thunk can be made
+to enable control-flow check.
+
+Note that @option{-mcmodel=large} is incompatible with
+@option{-mfunction-return=thunk} and
+@option{-mfunction-return=thunk-extern} since the thunk function may
+not be reachable in the large code model.
+
+
+@item -mindirect-branch-register
+@opindex mindirect-branch-register
+Force indirect call and jump via register.
+
+@item -mharden-sls=@var{choice}
+@opindex mharden-sls
+Generate code to mitigate against straight line speculation (SLS) with
+@var{choice}.  The default is @samp{none} which disables all SLS
+hardening.  @samp{return} enables SLS hardening for function returns.
+@samp{indirect-jmp} enables SLS hardening for indirect jumps.
+@samp{all} enables all SLS hardening.
+
+@item -mindirect-branch-cs-prefix
+@opindex mindirect-branch-cs-prefix
+Add CS prefix to call and jmp to indirect thunk with branch target in
+r8-r15 registers so that the call and jmp instruction length is 6 bytes
+to allow them to be replaced with @samp{lfence; call *%r8-r15} or
+@samp{lfence; jmp *%r8-r15} at run-time.
+
+@end table
+
+These @samp{-m} switches are supported in addition to the above
+on x86-64 processors in 64-bit environments.
+
+@table @gcctabopt
+@item -m32
+@itemx -m64
+@itemx -mx32
+@itemx -m16
+@itemx -miamcu
+@opindex m32
+@opindex m64
+@opindex mx32
+@opindex m16
+@opindex miamcu
+Generate code for a 16-bit, 32-bit or 64-bit environment.
+The @option{-m32} option sets @code{int}, @code{long}, and pointer types
+to 32 bits, and
+generates code that runs on any i386 system.
+
+The @option{-m64} option sets @code{int} to 32 bits and @code{long} and pointer
+types to 64 bits, and generates code for the x86-64 architecture.
+For Darwin only the @option{-m64} option also turns off the @option{-fno-pic}
+and @option{-mdynamic-no-pic} options.
+
+The @option{-mx32} option sets @code{int}, @code{long}, and pointer types
+to 32 bits, and
+generates code for the x86-64 architecture.
+
+The @option{-m16} option is the same as @option{-m32}, except for that
+it outputs the @code{.code16gcc} assembly directive at the beginning of
+the assembly output so that the binary can run in 16-bit mode.
+
+The @option{-miamcu} option generates code which conforms to Intel MCU
+psABI.  It requires the @option{-m32} option to be turned on.
+
+@item -mno-red-zone
+@opindex mno-red-zone
+@opindex mred-zone
+Do not use a so-called ``red zone'' for x86-64 code.  The red zone is mandated
+by the x86-64 ABI; it is a 128-byte area beyond the location of the
+stack pointer that is not modified by signal or interrupt handlers
+and therefore can be used for temporary data without adjusting the stack
+pointer.  The flag @option{-mno-red-zone} disables this red zone.
+
+@item -mcmodel=small
+@opindex mcmodel=small
+Generate code for the small code model: the program and its symbols must
+be linked in the lower 2 GB of the address space.  Pointers are 64 bits.
+Programs can be statically or dynamically linked.  This is the default
+code model.
+
+@item -mcmodel=kernel
+@opindex mcmodel=kernel
+Generate code for the kernel code model.  The kernel runs in the
+negative 2 GB of the address space.
+This model has to be used for Linux kernel code.
+
+@item -mcmodel=medium
+@opindex mcmodel=medium
+Generate code for the medium model: the program is linked in the lower 2
+GB of the address space.  Small symbols are also placed there.  Symbols
+with sizes larger than @option{-mlarge-data-threshold} are put into
+large data or BSS sections and can be located above 2GB.  Programs can
+be statically or dynamically linked.
+
+@item -mcmodel=large
+@opindex mcmodel=large
+Generate code for the large model.  This model makes no assumptions
+about addresses and sizes of sections.
+
+@item -maddress-mode=long
+@opindex maddress-mode=long
+Generate code for long address mode.  This is only supported for 64-bit
+and x32 environments.  It is the default address mode for 64-bit
+environments.
+
+@item -maddress-mode=short
+@opindex maddress-mode=short
+Generate code for short address mode.  This is only supported for 32-bit
+and x32 environments.  It is the default address mode for 32-bit and
+x32 environments.
+
+@item -mneeded
+@itemx -mno-needed
+@opindex mneeded
+Emit GNU_PROPERTY_X86_ISA_1_NEEDED GNU property for Linux target to
+indicate the micro-architecture ISA level required to execute the binary.
+
+@item -mno-direct-extern-access
+@opindex mno-direct-extern-access
+@opindex mdirect-extern-access
+Without @option{-fpic} nor @option{-fPIC}, always use the GOT pointer
+to access external symbols.  With @option{-fpic} or @option{-fPIC},
+treat access to protected symbols as local symbols.  The default is
+@option{-mdirect-extern-access}.
+
+@strong{Warning:} shared libraries compiled with
+@option{-mno-direct-extern-access} and executable compiled with
+@option{-mdirect-extern-access} may not be binary compatible if
+protected symbols are used in shared libraries and executable.
+@end table
+
+@node x86 Windows Options
+@subsection x86 Windows Options
+@cindex x86 Windows Options
+@cindex Windows Options for x86
+
+These additional options are available for Microsoft Windows targets:
+
+@table @gcctabopt
+@item -mconsole
+@opindex mconsole
+This option
+specifies that a console application is to be generated, by
+instructing the linker to set the PE header subsystem type
+required for console applications.
+This option is available for Cygwin and MinGW targets and is
+enabled by default on those targets.
+
+@item -mdll
+@opindex mdll
+This option is available for Cygwin and MinGW targets.  It
+specifies that a DLL---a dynamic link library---is to be
+generated, enabling the selection of the required runtime
+startup object and entry point.
+
+@item -mnop-fun-dllimport
+@opindex mnop-fun-dllimport
+This option is available for Cygwin and MinGW targets.  It
+specifies that the @code{dllimport} attribute should be ignored.
+
+@item -mthreads
+@opindex mthreads
+This option is available for MinGW targets. It specifies
+that MinGW-specific thread support is to be used.
+
+@item -municode
+@opindex municode
+This option is available for MinGW-w64 targets.  It causes
+the @code{UNICODE} preprocessor macro to be predefined, and
+chooses Unicode-capable runtime startup code.
+
+@item -mwin32
+@opindex mwin32
+This option is available for Cygwin and MinGW targets.  It
+specifies that the typical Microsoft Windows predefined macros are to
+be set in the pre-processor, but does not influence the choice
+of runtime library/startup code.
+
+@item -mwindows
+@opindex mwindows
+This option is available for Cygwin and MinGW targets.  It
+specifies that a GUI application is to be generated by
+instructing the linker to set the PE header subsystem type
+appropriately.
+
+@item -fno-set-stack-executable
+@opindex fno-set-stack-executable
+@opindex fset-stack-executable
+This option is available for MinGW targets. It specifies that
+the executable flag for the stack used by nested functions isn't
+set. This is necessary for binaries running in kernel mode of
+Microsoft Windows, as there the User32 API, which is used to set executable
+privileges, isn't available.
+
+@item -fwritable-relocated-rdata
+@opindex fno-writable-relocated-rdata
+@opindex fwritable-relocated-rdata
+This option is available for MinGW and Cygwin targets.  It specifies
+that relocated-data in read-only section is put into the @code{.data}
+section.  This is a necessary for older runtimes not supporting
+modification of @code{.rdata} sections for pseudo-relocation.
+
+@item -mpe-aligned-commons
+@opindex mpe-aligned-commons
+This option is available for Cygwin and MinGW targets.  It
+specifies that the GNU extension to the PE file format that
+permits the correct alignment of COMMON variables should be
+used when generating code.  It is enabled by default if
+GCC detects that the target assembler found during configuration
+supports the feature.
+@end table
+
+See also under @ref{x86 Options} for standard options.
+
+@node Xstormy16 Options
+@subsection Xstormy16 Options
+@cindex Xstormy16 Options
+
+These options are defined for Xstormy16:
+
+@table @gcctabopt
+@item -msim
+@opindex msim
+Choose startup files and linker script suitable for the simulator.
+@end table
+
+@node Xtensa Options
+@subsection Xtensa Options
+@cindex Xtensa Options
+
+These options are supported for Xtensa targets:
+
+@table @gcctabopt
+@item -mconst16
+@itemx -mno-const16
+@opindex mconst16
+@opindex mno-const16
+Enable or disable use of @code{CONST16} instructions for loading
+constant values.  The @code{CONST16} instruction is currently not a
+standard option from Tensilica.  When enabled, @code{CONST16}
+instructions are always used in place of the standard @code{L32R}
+instructions.  The use of @code{CONST16} is enabled by default only if
+the @code{L32R} instruction is not available.
+
+@item -mfused-madd
+@itemx -mno-fused-madd
+@opindex mfused-madd
+@opindex mno-fused-madd
+Enable or disable use of fused multiply/add and multiply/subtract
+instructions in the floating-point option.  This has no effect if the
+floating-point option is not also enabled.  Disabling fused multiply/add
+and multiply/subtract instructions forces the compiler to use separate
+instructions for the multiply and add/subtract operations.  This may be
+desirable in some cases where strict IEEE 754-compliant results are
+required: the fused multiply add/subtract instructions do not round the
+intermediate result, thereby producing results with @emph{more} bits of
+precision than specified by the IEEE standard.  Disabling fused multiply
+add/subtract instructions also ensures that the program output is not
+sensitive to the compiler's ability to combine multiply and add/subtract
+operations.
+
+@item -mserialize-volatile
+@itemx -mno-serialize-volatile
+@opindex mserialize-volatile
+@opindex mno-serialize-volatile
+When this option is enabled, GCC inserts @code{MEMW} instructions before
+@code{volatile} memory references to guarantee sequential consistency.
+The default is @option{-mserialize-volatile}.  Use
+@option{-mno-serialize-volatile} to omit the @code{MEMW} instructions.
+
+@item -mforce-no-pic
+@opindex mforce-no-pic
+For targets, like GNU/Linux, where all user-mode Xtensa code must be
+position-independent code (PIC), this option disables PIC for compiling
+kernel code.
+
+@item -mtext-section-literals
+@itemx -mno-text-section-literals
+@opindex mtext-section-literals
+@opindex mno-text-section-literals
+These options control the treatment of literal pools.  The default is
+@option{-mno-text-section-literals}, which places literals in a separate
+section in the output file.  This allows the literal pool to be placed
+in a data RAM/ROM, and it also allows the linker to combine literal
+pools from separate object files to remove redundant literals and
+improve code size.  With @option{-mtext-section-literals}, the literals
+are interspersed in the text section in order to keep them as close as
+possible to their references.  This may be necessary for large assembly
+files.  Literals for each function are placed right before that function.
+
+@item -mauto-litpools
+@itemx -mno-auto-litpools
+@opindex mauto-litpools
+@opindex mno-auto-litpools
+These options control the treatment of literal pools.  The default is
+@option{-mno-auto-litpools}, which places literals in a separate
+section in the output file unless @option{-mtext-section-literals} is
+used.  With @option{-mauto-litpools} the literals are interspersed in
+the text section by the assembler.  Compiler does not produce explicit
+@code{.literal} directives and loads literals into registers with
+@code{MOVI} instructions instead of @code{L32R} to let the assembler
+do relaxation and place literals as necessary.  This option allows
+assembler to create several literal pools per function and assemble
+very big functions, which may not be possible with
+@option{-mtext-section-literals}.
+
+@item -mtarget-align
+@itemx -mno-target-align
+@opindex mtarget-align
+@opindex mno-target-align
+When this option is enabled, GCC instructs the assembler to
+automatically align instructions to reduce branch penalties at the
+expense of some code density.  The assembler attempts to widen density
+instructions to align branch targets and the instructions following call
+instructions.  If there are not enough preceding safe density
+instructions to align a target, no widening is performed.  The
+default is @option{-mtarget-align}.  These options do not affect the
+treatment of auto-aligned instructions like @code{LOOP}, which the
+assembler always aligns, either by widening density instructions or
+by inserting NOP instructions.
+
+@item -mlongcalls
+@itemx -mno-longcalls
+@opindex mlongcalls
+@opindex mno-longcalls
+When this option is enabled, GCC instructs the assembler to translate
+direct calls to indirect calls unless it can determine that the target
+of a direct call is in the range allowed by the call instruction.  This
+translation typically occurs for calls to functions in other source
+files.  Specifically, the assembler translates a direct @code{CALL}
+instruction into an @code{L32R} followed by a @code{CALLX} instruction.
+The default is @option{-mno-longcalls}.  This option should be used in
+programs where the call target can potentially be out of range.  This
+option is implemented in the assembler, not the compiler, so the
+assembly code generated by GCC still shows direct call
+instructions---look at the disassembled object code to see the actual
+instructions.  Note that the assembler uses an indirect call for
+every cross-file call, not just those that really are out of range.
+
+@item -mabi=@var{name}
+@opindex mabi
+Generate code for the specified ABI@.  Permissible values are: @samp{call0},
+@samp{windowed}.  Default ABI is chosen by the Xtensa core configuration.
+
+@item -mabi=call0
+@opindex mabi=call0
+When this option is enabled function parameters are passed in registers
+@code{a2} through @code{a7}, registers @code{a12} through @code{a15} are
+caller-saved, and register @code{a15} may be used as a frame pointer.
+When this version of the ABI is enabled the C preprocessor symbol
+@code{__XTENSA_CALL0_ABI__} is defined.
+
+@item -mabi=windowed
+@opindex mabi=windowed
+When this option is enabled function parameters are passed in registers
+@code{a10} through @code{a15}, and called function rotates register window
+by 8 registers on entry so that its arguments are found in registers
+@code{a2} through @code{a7}.  Register @code{a7} may be used as a frame
+pointer.  Register window is rotated 8 registers back upon return.
+When this version of the ABI is enabled the C preprocessor symbol
+@code{__XTENSA_WINDOWED_ABI__} is defined.
+
+@item -mextra-l32r-costs=@var{n}
+@opindex mextra-l32r-costs
+Specify an extra cost of instruction RAM/ROM access for @code{L32R}
+instructions, in clock cycles.  This affects, when optimizing for speed,
+whether loading a constant from literal pool using @code{L32R} or
+synthesizing the constant from a small one with a couple of arithmetic
+instructions.  The default value is 0.
+@end table
+
+@node zSeries Options
+@subsection zSeries Options
+@cindex zSeries options
+
+These are listed under @xref{S/390 and zSeries Options}.
+
+
+@c man end
+
+@node Spec Files
+@section Specifying Subprocesses and the Switches to Pass to Them
+@cindex Spec Files
+
+@command{gcc} is a driver program.  It performs its job by invoking a
+sequence of other programs to do the work of compiling, assembling and
+linking.  GCC interprets its command-line parameters and uses these to
+deduce which programs it should invoke, and which command-line options
+it ought to place on their command lines.  This behavior is controlled
+by @dfn{spec strings}.  In most cases there is one spec string for each
+program that GCC can invoke, but a few programs have multiple spec
+strings to control their behavior.  The spec strings built into GCC can
+be overridden by using the @option{-specs=} command-line switch to specify
+a spec file.
+
+@dfn{Spec files} are plain-text files that are used to construct spec
+strings.  They consist of a sequence of directives separated by blank
+lines.  The type of directive is determined by the first non-whitespace
+character on the line, which can be one of the following:
+
+@table @code
+@item %@var{command}
+Issues a @var{command} to the spec file processor.  The commands that can
+appear here are:
+
+@table @code
+@item %include <@var{file}>
+@cindex @code{%include}
+Search for @var{file} and insert its text at the current point in the
+specs file.
+
+@item %include_noerr <@var{file}>
+@cindex @code{%include_noerr}
+Just like @samp{%include}, but do not generate an error message if the include
+file cannot be found.
+
+@item %rename @var{old_name} @var{new_name}
+@cindex @code{%rename}
+Rename the spec string @var{old_name} to @var{new_name}.
+
+@end table
+
+@item *[@var{spec_name}]:
+This tells the compiler to create, override or delete the named spec
+string.  All lines after this directive up to the next directive or
+blank line are considered to be the text for the spec string.  If this
+results in an empty string then the spec is deleted.  (Or, if the
+spec did not exist, then nothing happens.)  Otherwise, if the spec
+does not currently exist a new spec is created.  If the spec does
+exist then its contents are overridden by the text of this
+directive, unless the first character of that text is the @samp{+}
+character, in which case the text is appended to the spec.
+
+@item [@var{suffix}]:
+Creates a new @samp{[@var{suffix}] spec} pair.  All lines after this directive
+and up to the next directive or blank line are considered to make up the
+spec string for the indicated suffix.  When the compiler encounters an
+input file with the named suffix, it processes the spec string in
+order to work out how to compile that file.  For example:
+
+@smallexample
+.ZZ:
+z-compile -input %i
+@end smallexample
+
+This says that any input file whose name ends in @samp{.ZZ} should be
+passed to the program @samp{z-compile}, which should be invoked with the
+command-line switch @option{-input} and with the result of performing the
+@samp{%i} substitution.  (See below.)
+
+As an alternative to providing a spec string, the text following a
+suffix directive can be one of the following:
+
+@table @code
+@item @@@var{language}
+This says that the suffix is an alias for a known @var{language}.  This is
+similar to using the @option{-x} command-line switch to GCC to specify a
+language explicitly.  For example:
+
+@smallexample
+.ZZ:
+@@c++
+@end smallexample
+
+Says that .ZZ files are, in fact, C++ source files.
+
+@item #@var{name}
+This causes an error messages saying:
+
+@smallexample
+@var{name} compiler not installed on this system.
+@end smallexample
+@end table
+
+GCC already has an extensive list of suffixes built into it.
+This directive adds an entry to the end of the list of suffixes, but
+since the list is searched from the end backwards, it is effectively
+possible to override earlier entries using this technique.
+
+@end table
+
+GCC has the following spec strings built into it.  Spec files can
+override these strings or create their own.  Note that individual
+targets can also add their own spec strings to this list.
+
+@smallexample
+asm          Options to pass to the assembler
+asm_final    Options to pass to the assembler post-processor
+cpp          Options to pass to the C preprocessor
+cc1          Options to pass to the C compiler
+cc1plus      Options to pass to the C++ compiler
+endfile      Object files to include at the end of the link
+link         Options to pass to the linker
+lib          Libraries to include on the command line to the linker
+libgcc       Decides which GCC support library to pass to the linker
+linker       Sets the name of the linker
+predefines   Defines to be passed to the C preprocessor
+signed_char  Defines to pass to CPP to say whether @code{char} is signed
+             by default
+startfile    Object files to include at the start of the link
+@end smallexample
+
+Here is a small example of a spec file:
+
+@smallexample
+%rename lib                 old_lib
+
+*lib:
+--start-group -lgcc -lc -leval1 --end-group %(old_lib)
+@end smallexample
+
+This example renames the spec called @samp{lib} to @samp{old_lib} and
+then overrides the previous definition of @samp{lib} with a new one.
+The new definition adds in some extra command-line options before
+including the text of the old definition.
+
+@dfn{Spec strings} are a list of command-line options to be passed to their
+corresponding program.  In addition, the spec strings can contain
+@samp{%}-prefixed sequences to substitute variable text or to
+conditionally insert text into the command line.  Using these constructs
+it is possible to generate quite complex command lines.
+
+Here is a table of all defined @samp{%}-sequences for spec
+strings.  Note that spaces are not generated automatically around the
+results of expanding these sequences.  Therefore you can concatenate them
+together or combine them with constant text in a single argument.
+
+@table @code
+@item %%
+Substitute one @samp{%} into the program name or argument.
+
+@item %"
+Substitute an empty argument.
+
+@item %i
+Substitute the name of the input file being processed.
+
+@item %b
+Substitute the basename for outputs related with the input file being
+processed.  This is often the substring up to (and not including) the
+last period and not including the directory but, unless %w is active, it
+expands to the basename for auxiliary outputs, which may be influenced
+by an explicit output name, and by various other options that control
+how auxiliary outputs are named.
+
+@item %B
+This is the same as @samp{%b}, but include the file suffix (text after
+the last period).  Without %w, it expands to the basename for dump
+outputs.
+
+@item %d
+Marks the argument containing or following the @samp{%d} as a
+temporary file name, so that that file is deleted if GCC exits
+successfully.  Unlike @samp{%g}, this contributes no text to the
+argument.
+
+@item %g@var{suffix}
+Substitute a file name that has suffix @var{suffix} and is chosen
+once per compilation, and mark the argument in the same way as
+@samp{%d}.  To reduce exposure to denial-of-service attacks, the file
+name is now chosen in a way that is hard to predict even when previously
+chosen file names are known.  For example, @samp{%g.s @dots{} %g.o @dots{} %g.s}
+might turn into @samp{ccUVUUAU.s ccXYAXZ12.o ccUVUUAU.s}.  @var{suffix} matches
+the regexp @samp{[.A-Za-z]*} or the special string @samp{%O}, which is
+treated exactly as if @samp{%O} had been preprocessed.  Previously, @samp{%g}
+was simply substituted with a file name chosen once per compilation,
+without regard to any appended suffix (which was therefore treated
+just like ordinary text), making such attacks more likely to succeed.
+
+@item %u@var{suffix}
+Like @samp{%g}, but generates a new temporary file name
+each time it appears instead of once per compilation.
+
+@item %U@var{suffix}
+Substitutes the last file name generated with @samp{%u@var{suffix}}, generating a
+new one if there is no such last file name.  In the absence of any
+@samp{%u@var{suffix}}, this is just like @samp{%g@var{suffix}}, except they don't share
+the same suffix @emph{space}, so @samp{%g.s @dots{} %U.s @dots{} %g.s @dots{} %U.s}
+involves the generation of two distinct file names, one
+for each @samp{%g.s} and another for each @samp{%U.s}.  Previously, @samp{%U} was
+simply substituted with a file name chosen for the previous @samp{%u},
+without regard to any appended suffix.
+
+@item %j@var{suffix}
+Substitutes the name of the @code{HOST_BIT_BUCKET}, if any, and if it is
+writable, and if @option{-save-temps} is not used; 
+otherwise, substitute the name
+of a temporary file, just like @samp{%u}.  This temporary file is not
+meant for communication between processes, but rather as a junk
+disposal mechanism.
+
+@item %|@var{suffix}
+@itemx %m@var{suffix}
+Like @samp{%g}, except if @option{-pipe} is in effect.  In that case
+@samp{%|} substitutes a single dash and @samp{%m} substitutes nothing at
+all.  These are the two most common ways to instruct a program that it
+should read from standard input or write to standard output.  If you
+need something more elaborate you can use an @samp{%@{pipe:@code{X}@}}
+construct: see for example @file{gcc/fortran/lang-specs.h}.
+
+@item %.@var{SUFFIX}
+Substitutes @var{.SUFFIX} for the suffixes of a matched switch's args
+when it is subsequently output with @samp{%*}.  @var{SUFFIX} is
+terminated by the next space or %.
+
+@item %w
+Marks the argument containing or following the @samp{%w} as the
+designated output file of this compilation.  This puts the argument
+into the sequence of arguments that @samp{%o} substitutes.
+
+@item %V
+Indicates that this compilation produces no output file.
+
+@item %o
+Substitutes the names of all the output files, with spaces
+automatically placed around them.  You should write spaces
+around the @samp{%o} as well or the results are undefined.
+@samp{%o} is for use in the specs for running the linker.
+Input files whose names have no recognized suffix are not compiled
+at all, but they are included among the output files, so they are
+linked.
+
+@item %O
+Substitutes the suffix for object files.  Note that this is
+handled specially when it immediately follows @samp{%g, %u, or %U},
+because of the need for those to form complete file names.  The
+handling is such that @samp{%O} is treated exactly as if it had already
+been substituted, except that @samp{%g, %u, and %U} do not currently
+support additional @var{suffix} characters following @samp{%O} as they do
+following, for example, @samp{.o}.
+
+@item %I
+Substitute any of @option{-iprefix} (made from @env{GCC_EXEC_PREFIX}),
+@option{-isysroot} (made from @env{TARGET_SYSTEM_ROOT}),
+@option{-isystem} (made from @env{COMPILER_PATH} and @option{-B} options)
+and @option{-imultilib} as necessary.
+
+@item %s
+Current argument is the name of a library or startup file of some sort.
+Search for that file in a standard list of directories and substitute
+the full name found.  The current working directory is included in the
+list of directories scanned.
+
+@item %T
+Current argument is the name of a linker script.  Search for that file
+in the current list of directories to scan for libraries. If the file
+is located insert a @option{--script} option into the command line
+followed by the full path name found.  If the file is not found then
+generate an error message.  Note: the current working directory is not
+searched.
+
+@item %e@var{str}
+Print @var{str} as an error message.  @var{str} is terminated by a newline.
+Use this when inconsistent options are detected.
+
+@item %n@var{str}
+Print @var{str} as a notice.  @var{str} is terminated by a newline.
+
+@item %(@var{name})
+Substitute the contents of spec string @var{name} at this point.
+
+@item %x@{@var{option}@}
+Accumulate an option for @samp{%X}.
+
+@item %X
+Output the accumulated linker options specified by a @samp{%x} spec string.
+
+@item %Y
+Output the accumulated assembler options specified by @option{-Wa}.
+
+@item %Z
+Output the accumulated preprocessor options specified by @option{-Wp}.
+
+@item %M
+Output @code{multilib_os_dir}.
+
+@item %R
+Output the concatenation of @code{target_system_root} and @code{target_sysroot_suffix}.
+
+@item %a
+Process the @code{asm} spec.  This is used to compute the
+switches to be passed to the assembler.
+
+@item %A
+Process the @code{asm_final} spec.  This is a spec string for
+passing switches to an assembler post-processor, if such a program is
+needed.
+
+@item %l
+Process the @code{link} spec.  This is the spec for computing the
+command line passed to the linker.  Typically it makes use of the
+@samp{%L %G %S %D and %E} sequences.
+
+@item %D
+Dump out a @option{-L} option for each directory that GCC believes might
+contain startup files.  If the target supports multilibs then the
+current multilib directory is prepended to each of these paths.
+
+@item %L
+Process the @code{lib} spec.  This is a spec string for deciding which
+libraries are included on the command line to the linker.
+
+@item %G
+Process the @code{libgcc} spec.  This is a spec string for deciding
+which GCC support library is included on the command line to the linker.
+
+@item %S
+Process the @code{startfile} spec.  This is a spec for deciding which
+object files are the first ones passed to the linker.  Typically
+this might be a file named @file{crt0.o}.
+
+@item %E
+Process the @code{endfile} spec.  This is a spec string that specifies
+the last object files that are passed to the linker.
+
+@item %C
+Process the @code{cpp} spec.  This is used to construct the arguments
+to be passed to the C preprocessor.
+
+@item %1
+Process the @code{cc1} spec.  This is used to construct the options to be
+passed to the actual C compiler (@command{cc1}).
+
+@item %2
+Process the @code{cc1plus} spec.  This is used to construct the options to be
+passed to the actual C++ compiler (@command{cc1plus}).
+
+@item %*
+Substitute the variable part of a matched option.  See below.
+Note that each comma in the substituted string is replaced by
+a single space.
+
+@item %<S
+Remove all occurrences of @code{-S} from the command line.  Note---this
+command is position dependent.  @samp{%} commands in the spec string
+before this one see @code{-S}, @samp{%} commands in the spec string
+after this one do not.
+
+@item %<S*
+Similar to @samp{%<S}, but match all switches beginning with @code{-S}.
+
+@item %>S
+Similar to @samp{%<S}, but keep @code{-S} in the GCC command line.
+
+@item %:@var{function}(@var{args})
+Call the named function @var{function}, passing it @var{args}.
+@var{args} is first processed as a nested spec string, then split
+into an argument vector in the usual fashion.  The function returns
+a string which is processed as if it had appeared literally as part
+of the current spec.
+
+The following built-in spec functions are provided:
+
+@table @code
+@item @code{getenv}
+The @code{getenv} spec function takes two arguments: an environment
+variable name and a string.  If the environment variable is not
+defined, a fatal error is issued.  Otherwise, the return value is the
+value of the environment variable concatenated with the string.  For
+example, if @env{TOPDIR} is defined as @file{/path/to/top}, then:
+
+@smallexample
+%:getenv(TOPDIR /include)
+@end smallexample
+
+expands to @file{/path/to/top/include}.
+
+@item @code{if-exists}
+The @code{if-exists} spec function takes one argument, an absolute
+pathname to a file.  If the file exists, @code{if-exists} returns the
+pathname.  Here is a small example of its usage:
+
+@smallexample
+*startfile:
+crt0%O%s %:if-exists(crti%O%s) crtbegin%O%s
+@end smallexample
+
+@item @code{if-exists-else}
+The @code{if-exists-else} spec function is similar to the @code{if-exists}
+spec function, except that it takes two arguments.  The first argument is
+an absolute pathname to a file.  If the file exists, @code{if-exists-else}
+returns the pathname.  If it does not exist, it returns the second argument.
+This way, @code{if-exists-else} can be used to select one file or another,
+based on the existence of the first.  Here is a small example of its usage:
+
+@smallexample
+*startfile:
+crt0%O%s %:if-exists(crti%O%s) \
+%:if-exists-else(crtbeginT%O%s crtbegin%O%s)
+@end smallexample
+
+@item @code{if-exists-then-else}
+The @code{if-exists-then-else} spec function takes at least two arguments
+and an optional third one. The first argument is an absolute pathname to a
+file.  If the file exists, the function returns the second argument.
+If the file does not exist, the function returns the third argument if there
+is one, or NULL otherwise. This can be used to expand one text, or optionally
+another, based on the existence of a file.  Here is a small example of its
+usage:
+
+@smallexample
+-l%:if-exists-then-else(%:getenv(VSB_DIR rtnet.h) rtnet net)
+@end smallexample
+
+@item @code{sanitize}
+The @code{sanitize} spec function takes no arguments.  It returns non-NULL if
+any address, thread or undefined behavior sanitizers are active.
+
+@smallexample
+%@{%:sanitize(address):-funwind-tables@}
+@end smallexample
+
+@item @code{replace-outfile}
+The @code{replace-outfile} spec function takes two arguments.  It looks for the
+first argument in the outfiles array and replaces it with the second argument.  Here
+is a small example of its usage:
+
+@smallexample
+%@{fgnu-runtime:%:replace-outfile(-lobjc -lobjc-gnu)@}
+@end smallexample
+
+@item @code{remove-outfile}
+The @code{remove-outfile} spec function takes one argument.  It looks for the
+first argument in the outfiles array and removes it.  Here is a small example
+its usage:
+
+@smallexample
+%:remove-outfile(-lm)
+@end smallexample
+
+@item @code{version-compare}
+The @code{version-compare} spec function takes four or five arguments of the following
+form:
+
+@smallexample
+<comparison-op> <arg1> [<arg2>] <switch> <result>
+@end smallexample
+
+It returns @code{result} if the comparison evaluates to true, and NULL if it doesn't.
+The supported @code{comparison-op} values are:
+
+@table @code
+@item >=
+True if @code{switch} is a later (or same) version than @code{arg1}
+
+@item !>
+Opposite of @code{>=}
+
+@item <
+True if @code{switch} is an earlier version than @code{arg1}
+
+@item !<
+Opposite of @code{<}
+
+@item ><
+True if @code{switch} is @code{arg1} or later, and earlier than @code{arg2}
+
+@item <>
+True if @code{switch} is earlier than @code{arg1}, or is @code{arg2} or later
+@end table
+
+If the @code{switch} is not present at all, the condition is false unless the first character
+of the @code{comparison-op} is @code{!}.
+
+@smallexample
+%:version-compare(>= 10.3 mmacosx-version-min= -lmx)
+@end smallexample
+
+The above example would add @option{-lmx} if @option{-mmacosx-version-min=10.3.9} was
+passed.
+
+@item @code{include}
+The @code{include} spec function behaves much like @code{%include}, with the advantage
+that it can be nested inside a spec and thus be conditionalized.  It takes one argument,
+the filename, and looks for it in the startfile path.  It always returns NULL.
+
+@smallexample
+%@{static-libasan|static:%:include(libsanitizer.spec)%(link_libasan)@}
+@end smallexample
+
+@item @code{pass-through-libs}
+The @code{pass-through-libs} spec function takes any number of arguments.  It
+finds any @option{-l} options and any non-options ending in @file{.a} (which it
+assumes are the names of linker input library archive files) and returns a
+result containing all the found arguments each prepended by
+@option{-plugin-opt=-pass-through=} and joined by spaces.  This list is
+intended to be passed to the LTO linker plugin.
+
+@smallexample
+%:pass-through-libs(%G %L %G)
+@end smallexample
+
+@item @code{print-asm-header}
+The @code{print-asm-header} function takes no arguments and simply
+prints a banner like:
+
+@smallexample
+Assembler options
+=================
+
+Use "-Wa,OPTION" to pass "OPTION" to the assembler.
+@end smallexample
+
+It is used to separate compiler options from assembler options
+in the @option{--target-help} output.
+
+@item @code{gt}
+The @code{gt} spec function takes two or more arguments.  It returns @code{""} (the
+empty string) if the second-to-last argument is greater than the last argument, and NULL
+otherwise.  The following example inserts the @code{link_gomp} spec if the last
+@option{-ftree-parallelize-loops=} option given on the command line is greater than 1:
+
+@smallexample
+%@{%:gt(%@{ftree-parallelize-loops=*:%*@} 1):%:include(libgomp.spec)%(link_gomp)@}
+@end smallexample
+
+@item @code{debug-level-gt}
+The @code{debug-level-gt} spec function takes one argument and returns @code{""} (the
+empty string) if @code{debug_info_level} is greater than the specified number, and NULL
+otherwise.
+
+@smallexample
+%@{%:debug-level-gt(0):%@{gdwarf*:--gdwarf2@}@}
+@end smallexample
+@end table
+
+@item %@{S@}
+Substitutes the @code{-S} switch, if that switch is given to GCC@.
+If that switch is not specified, this substitutes nothing.  Note that
+the leading dash is omitted when specifying this option, and it is
+automatically inserted if the substitution is performed.  Thus the spec
+string @samp{%@{foo@}} matches the command-line option @option{-foo}
+and outputs the command-line option @option{-foo}.
+
+@item %W@{S@}
+Like %@{@code{S}@} but mark last argument supplied within as a file to be
+deleted on failure.
+
+@item %@@@{S@}
+Like %@{@code{S}@} but puts the result into a @code{FILE} and substitutes
+@code{@@FILE} if an @code{@@file} argument has been supplied.
+
+@item %@{S*@}
+Substitutes all the switches specified to GCC whose names start
+with @code{-S}, but which also take an argument.  This is used for
+switches like @option{-o}, @option{-D}, @option{-I}, etc.
+GCC considers @option{-o foo} as being
+one switch whose name starts with @samp{o}.  %@{o*@} substitutes this
+text, including the space.  Thus two arguments are generated.
+
+@item %@{S*&T*@}
+Like %@{@code{S}*@}, but preserve order of @code{S} and @code{T} options
+(the order of @code{S} and @code{T} in the spec is not significant).
+There can be any number of ampersand-separated variables; for each the
+wild card is optional.  Useful for CPP as @samp{%@{D*&U*&A*@}}.
+
+@item %@{S:X@}
+Substitutes @code{X}, if the @option{-S} switch is given to GCC@.
+
+@item %@{!S:X@}
+Substitutes @code{X}, if the @option{-S} switch is @emph{not} given to GCC@.
+
+@item %@{S*:X@}
+Substitutes @code{X} if one or more switches whose names start with
+@code{-S} are specified to GCC@.  Normally @code{X} is substituted only
+once, no matter how many such switches appeared.  However, if @code{%*}
+appears somewhere in @code{X}, then @code{X} is substituted once
+for each matching switch, with the @code{%*} replaced by the part of
+that switch matching the @code{*}.
+
+If @code{%*} appears as the last part of a spec sequence then a space
+is added after the end of the last substitution.  If there is more
+text in the sequence, however, then a space is not generated.  This
+allows the @code{%*} substitution to be used as part of a larger
+string.  For example, a spec string like this:
+
+@smallexample
+%@{mcu=*:--script=%*/memory.ld@}
+@end smallexample
+
+@noindent
+when matching an option like @option{-mcu=newchip} produces:
+
+@smallexample
+--script=newchip/memory.ld
+@end smallexample
+
+@item %@{.S:X@}
+Substitutes @code{X}, if processing a file with suffix @code{S}.
+
+@item %@{!.S:X@}
+Substitutes @code{X}, if @emph{not} processing a file with suffix @code{S}.
+
+@item %@{,S:X@}
+Substitutes @code{X}, if processing a file for language @code{S}.
+
+@item %@{!,S:X@}
+Substitutes @code{X}, if not processing a file for language @code{S}.
+
+@item %@{S|P:X@}
+Substitutes @code{X} if either @code{-S} or @code{-P} is given to
+GCC@.  This may be combined with @samp{!}, @samp{.}, @samp{,}, and
+@code{*} sequences as well, although they have a stronger binding than
+the @samp{|}.  If @code{%*} appears in @code{X}, all of the
+alternatives must be starred, and only the first matching alternative
+is substituted.
+
+For example, a spec string like this:
+
+@smallexample
+%@{.c:-foo@} %@{!.c:-bar@} %@{.c|d:-baz@} %@{!.c|d:-boggle@}
+@end smallexample
+
+@noindent
+outputs the following command-line options from the following input
+command-line options:
+
+@smallexample
+fred.c        -foo -baz
+jim.d         -bar -boggle
+-d fred.c     -foo -baz -boggle
+-d jim.d      -bar -baz -boggle
+@end smallexample
+
+@item %@{%:@var{function}(@var{args}):X@}
+
+Call function named @var{function} with args @var{args}.  If the
+function returns non-NULL, then @code{X} is substituted, if it returns
+NULL, it isn't substituted.
+
+@item %@{S:X; T:Y; :D@}
+
+If @code{S} is given to GCC, substitutes @code{X}; else if @code{T} is
+given to GCC, substitutes @code{Y}; else substitutes @code{D}.  There can
+be as many clauses as you need.  This may be combined with @code{.},
+@code{,}, @code{!}, @code{|}, and @code{*} as needed.
+
+
+@end table
+
+The switch matching text @code{S} in a @samp{%@{S@}}, @samp{%@{S:X@}}
+or similar construct can use a backslash to ignore the special meaning
+of the character following it, thus allowing literal matching of a
+character that is otherwise specially treated.  For example,
+@samp{%@{std=iso9899\:1999:X@}} substitutes @code{X} if the
+@option{-std=iso9899:1999} option is given.
+
+The conditional text @code{X} in a @samp{%@{S:X@}} or similar
+construct may contain other nested @samp{%} constructs or spaces, or
+even newlines.  They are processed as usual, as described above.
+Trailing white space in @code{X} is ignored.  White space may also
+appear anywhere on the left side of the colon in these constructs,
+except between @code{.} or @code{*} and the corresponding word.
+
+The @option{-O}, @option{-f}, @option{-m}, and @option{-W} switches are
+handled specifically in these constructs.  If another value of
+@option{-O} or the negated form of a @option{-f}, @option{-m}, or
+@option{-W} switch is found later in the command line, the earlier
+switch value is ignored, except with @{@code{S}*@} where @code{S} is
+just one letter, which passes all matching options.
+
+The character @samp{|} at the beginning of the predicate text is used to
+indicate that a command should be piped to the following command, but
+only if @option{-pipe} is specified.
+
+It is built into GCC which switches take arguments and which do not.
+(You might think it would be useful to generalize this to allow each
+compiler's spec to say which switches take arguments.  But this cannot
+be done in a consistent fashion.  GCC cannot even decide which input
+files have been specified without knowing which switches take arguments,
+and it must know which input files to compile in order to tell which
+compilers to run).
+
+GCC also knows implicitly that arguments starting in @option{-l} are to be
+treated as compiler output files, and passed to the linker in their
+proper position among the other output files.
+
+@node Environment Variables
+@section Environment Variables Affecting GCC
+@cindex environment variables
+
+@c man begin ENVIRONMENT
+This section describes several environment variables that affect how GCC
+operates.  Some of them work by specifying directories or prefixes to use
+when searching for various kinds of files.  Some are used to specify other
+aspects of the compilation environment.
+
+Note that you can also specify places to search using options such as
+@option{-B}, @option{-I} and @option{-L} (@pxref{Directory Options}).  These
+take precedence over places specified using environment variables, which
+in turn take precedence over those specified by the configuration of GCC@.
+@xref{Driver,, Controlling the Compilation Driver @file{gcc}, gccint,
+GNU Compiler Collection (GCC) Internals}.
+
+@table @env
+@item LANG
+@itemx LC_CTYPE
+@c @itemx LC_COLLATE
+@itemx LC_MESSAGES
+@c @itemx LC_MONETARY
+@c @itemx LC_NUMERIC
+@c @itemx LC_TIME
+@itemx LC_ALL
+@findex LANG
+@findex LC_CTYPE
+@c @findex LC_COLLATE
+@findex LC_MESSAGES
+@c @findex LC_MONETARY
+@c @findex LC_NUMERIC
+@c @findex LC_TIME
+@findex LC_ALL
+@cindex locale
+These environment variables control the way that GCC uses
+localization information which allows GCC to work with different
+national conventions.  GCC inspects the locale categories
+@env{LC_CTYPE} and @env{LC_MESSAGES} if it has been configured to do
+so.  These locale categories can be set to any value supported by your
+installation.  A typical value is @samp{en_GB.UTF-8} for English in the United
+Kingdom encoded in UTF-8.
+
+The @env{LC_CTYPE} environment variable specifies character
+classification.  GCC uses it to determine the character boundaries in
+a string; this is needed for some multibyte encodings that contain quote
+and escape characters that are otherwise interpreted as a string
+end or escape.
+
+The @env{LC_MESSAGES} environment variable specifies the language to
+use in diagnostic messages.
+
+If the @env{LC_ALL} environment variable is set, it overrides the value
+of @env{LC_CTYPE} and @env{LC_MESSAGES}; otherwise, @env{LC_CTYPE}
+and @env{LC_MESSAGES} default to the value of the @env{LANG}
+environment variable.  If none of these variables are set, GCC
+defaults to traditional C English behavior.
+
+@item TMPDIR
+@findex TMPDIR
+If @env{TMPDIR} is set, it specifies the directory to use for temporary
+files.  GCC uses temporary files to hold the output of one stage of
+compilation which is to be used as input to the next stage: for example,
+the output of the preprocessor, which is the input to the compiler
+proper.
+
+@item GCC_COMPARE_DEBUG
+@findex GCC_COMPARE_DEBUG
+Setting @env{GCC_COMPARE_DEBUG} is nearly equivalent to passing
+@option{-fcompare-debug} to the compiler driver.  See the documentation
+of this option for more details.
+
+@item GCC_EXEC_PREFIX
+@findex GCC_EXEC_PREFIX
+If @env{GCC_EXEC_PREFIX} is set, it specifies a prefix to use in the
+names of the subprograms executed by the compiler.  No slash is added
+when this prefix is combined with the name of a subprogram, but you can
+specify a prefix that ends with a slash if you wish.
+
+If @env{GCC_EXEC_PREFIX} is not set, GCC attempts to figure out
+an appropriate prefix to use based on the pathname it is invoked with.
+
+If GCC cannot find the subprogram using the specified prefix, it
+tries looking in the usual places for the subprogram.
+
+The default value of @env{GCC_EXEC_PREFIX} is
+@file{@var{prefix}/lib/gcc/} where @var{prefix} is the prefix to
+the installed compiler. In many cases @var{prefix} is the value
+of @code{prefix} when you ran the @file{configure} script.
+
+Other prefixes specified with @option{-B} take precedence over this prefix.
+
+This prefix is also used for finding files such as @file{crt0.o} that are
+used for linking.
+
+In addition, the prefix is used in an unusual way in finding the
+directories to search for header files.  For each of the standard
+directories whose name normally begins with @samp{/usr/local/lib/gcc}
+(more precisely, with the value of @env{GCC_INCLUDE_DIR}), GCC tries
+replacing that beginning with the specified prefix to produce an
+alternate directory name.  Thus, with @option{-Bfoo/}, GCC searches
+@file{foo/bar} just before it searches the standard directory 
+@file{/usr/local/lib/bar}.
+If a standard directory begins with the configured
+@var{prefix} then the value of @var{prefix} is replaced by
+@env{GCC_EXEC_PREFIX} when looking for header files.
+
+@item COMPILER_PATH
+@findex COMPILER_PATH
+The value of @env{COMPILER_PATH} is a colon-separated list of
+directories, much like @env{PATH}.  GCC tries the directories thus
+specified when searching for subprograms, if it cannot find the
+subprograms using @env{GCC_EXEC_PREFIX}.
+
+@item LIBRARY_PATH
+@findex LIBRARY_PATH
+The value of @env{LIBRARY_PATH} is a colon-separated list of
+directories, much like @env{PATH}.  When configured as a native compiler,
+GCC tries the directories thus specified when searching for special
+linker files, if it cannot find them using @env{GCC_EXEC_PREFIX}.  Linking
+using GCC also uses these directories when searching for ordinary
+libraries for the @option{-l} option (but directories specified with
+@option{-L} come first).
+
+@item LANG
+@findex LANG
+@cindex locale definition
+This variable is used to pass locale information to the compiler.  One way in
+which this information is used is to determine the character set to be used
+when character literals, string literals and comments are parsed in C and C++.
+When the compiler is configured to allow multibyte characters,
+the following values for @env{LANG} are recognized:
+
+@table @samp
+@item C-JIS
+Recognize JIS characters.
+@item C-SJIS
+Recognize SJIS characters.
+@item C-EUCJP
+Recognize EUCJP characters.
+@end table
+
+If @env{LANG} is not defined, or if it has some other value, then the
+compiler uses @code{mblen} and @code{mbtowc} as defined by the default locale to
+recognize and translate multibyte characters.
+
+@item GCC_EXTRA_DIAGNOSTIC_OUTPUT
+@findex GCC_EXTRA_DIAGNOSTIC_OUTPUT
+If @env{GCC_EXTRA_DIAGNOSTIC_OUTPUT} is set to one of the following values,
+then additional text will be emitted to stderr when fix-it hints are
+emitted.  @option{-fdiagnostics-parseable-fixits} and
+@option{-fno-diagnostics-parseable-fixits} take precedence over this
+environment variable.
+
+@table @samp
+@item fixits-v1
+Emit parseable fix-it hints, equivalent to
+@option{-fdiagnostics-parseable-fixits}.  In particular, columns are
+expressed as a count of bytes, starting at byte 1 for the initial column.
+
+@item fixits-v2
+As @code{fixits-v1}, but columns are expressed as display columns,
+as per @option{-fdiagnostics-column-unit=display}.
+@end table
+
+@end table
+
+@noindent
+Some additional environment variables affect the behavior of the
+preprocessor.
+
+@include cppenv.texi
+
+@c man end
+
+@node Precompiled Headers
+@section Using Precompiled Headers
+@cindex precompiled headers
+@cindex speed of compilation
+
+Often large projects have many header files that are included in every
+source file.  The time the compiler takes to process these header files
+over and over again can account for nearly all of the time required to
+build the project.  To make builds faster, GCC allows you to
+@dfn{precompile} a header file.
+
+To create a precompiled header file, simply compile it as you would any
+other file, if necessary using the @option{-x} option to make the driver
+treat it as a C or C++ header file.  You may want to use a
+tool like @command{make} to keep the precompiled header up-to-date when
+the headers it contains change.
+
+A precompiled header file is searched for when @code{#include} is
+seen in the compilation.  As it searches for the included file
+(@pxref{Search Path,,Search Path,cpp,The C Preprocessor}) the
+compiler looks for a precompiled header in each directory just before it
+looks for the include file in that directory.  The name searched for is
+the name specified in the @code{#include} with @samp{.gch} appended.  If
+the precompiled header file cannot be used, it is ignored.
+
+For instance, if you have @code{#include "all.h"}, and you have
+@file{all.h.gch} in the same directory as @file{all.h}, then the
+precompiled header file is used if possible, and the original
+header is used otherwise.
+
+Alternatively, you might decide to put the precompiled header file in a
+directory and use @option{-I} to ensure that directory is searched
+before (or instead of) the directory containing the original header.
+Then, if you want to check that the precompiled header file is always
+used, you can put a file of the same name as the original header in this
+directory containing an @code{#error} command.
+
+This also works with @option{-include}.  So yet another way to use
+precompiled headers, good for projects not designed with precompiled
+header files in mind, is to simply take most of the header files used by
+a project, include them from another header file, precompile that header
+file, and @option{-include} the precompiled header.  If the header files
+have guards against multiple inclusion, they are skipped because
+they've already been included (in the precompiled header).
+
+If you need to precompile the same header file for different
+languages, targets, or compiler options, you can instead make a
+@emph{directory} named like @file{all.h.gch}, and put each precompiled
+header in the directory, perhaps using @option{-o}.  It doesn't matter
+what you call the files in the directory; every precompiled header in
+the directory is considered.  The first precompiled header
+encountered in the directory that is valid for this compilation is
+used; they're searched in no particular order.
+
+There are many other possibilities, limited only by your imagination,
+good sense, and the constraints of your build system.
+
+A precompiled header file can be used only when these conditions apply:
+
+@itemize
+@item
+Only one precompiled header can be used in a particular compilation.
+
+@item
+A precompiled header cannot be used once the first C token is seen.  You
+can have preprocessor directives before a precompiled header; you cannot
+include a precompiled header from inside another header.
+
+@item
+The precompiled header file must be produced for the same language as
+the current compilation.  You cannot use a C precompiled header for a C++
+compilation.
+
+@item
+The precompiled header file must have been produced by the same compiler
+binary as the current compilation is using.
+
+@item
+Any macros defined before the precompiled header is included must
+either be defined in the same way as when the precompiled header was
+generated, or must not affect the precompiled header, which usually
+means that they don't appear in the precompiled header at all.
+
+The @option{-D} option is one way to define a macro before a
+precompiled header is included; using a @code{#define} can also do it.
+There are also some options that define macros implicitly, like
+@option{-O} and @option{-Wdeprecated}; the same rule applies to macros
+defined this way.
+
+@item If debugging information is output when using the precompiled
+header, using @option{-g} or similar, the same kind of debugging information
+must have been output when building the precompiled header.  However,
+a precompiled header built using @option{-g} can be used in a compilation
+when no debugging information is being output.
+
+@item The same @option{-m} options must generally be used when building
+and using the precompiled header.  @xref{Submodel Options},
+for any cases where this rule is relaxed.
+
+@item Each of the following options must be the same when building and using
+the precompiled header:
+
+@gccoptlist{-fexceptions}
+
+@item
+Some other command-line options starting with @option{-f},
+@option{-p}, or @option{-O} must be defined in the same way as when
+the precompiled header was generated.  At present, it's not clear
+which options are safe to change and which are not; the safest choice
+is to use exactly the same options when generating and using the
+precompiled header.  The following are known to be safe:
+
+@gccoptlist{-fmessage-length=  -fpreprocessed  -fsched-interblock @gol
+-fsched-spec  -fsched-spec-load  -fsched-spec-load-dangerous @gol
+-fsched-verbose=@var{number}  -fschedule-insns  -fvisibility= @gol
+-pedantic-errors}
+
+@item Address space layout randomization (ASLR) can lead to not binary identical
+PCH files.  If you rely on stable PCH file contents disable ASLR when generating
+PCH files.
+
+@end itemize
+
+For all of these except the last, the compiler automatically
+ignores the precompiled header if the conditions aren't met.  If you
+find an option combination that doesn't work and doesn't cause the
+precompiled header to be ignored, please consider filing a bug report,
+see @ref{Bugs}.
+
+If you do use differing options when generating and using the
+precompiled header, the actual behavior is a mixture of the
+behavior for the options.  For instance, if you use @option{-g} to
+generate the precompiled header but not when using it, you may or may
+not get debugging information for routines in the precompiled header.
+
+@node C++ Modules
+@section C++ Modules
+@cindex speed of compilation
+
+Modules are a C++20 language feature.  As the name suggests, they
+provides a modular compilation system, intending to provide both
+faster builds and better library isolation.  The ``Merging Modules''
+paper @uref{https://wg21.link/p1103}, provides the easiest to read set
+of changes to the standard, although it does not capture later
+changes.
+
+@emph{G++'s modules support is not complete.}  Other than bugs, the
+known missing pieces are:
+
+@table @emph
+
+@item Private Module Fragment
+The Private Module Fragment is recognized, but an error is emitted.
+
+@item Partition definition visibility rules
+Entities may be defined in implementation partitions, and those
+definitions are not available outside of the module.  This is not
+implemented, and the definitions are available to extra-module use.
+
+@item Textual merging of reachable GM entities
+Entities may be multiply defined across different header-units.
+These must be de-duplicated, and this is implemented across imports,
+or when an import redefines a textually-defined entity.  However the
+reverse is not implemented---textually redefining an entity that has
+been defined in an imported header-unit.  A redefinition error is
+emitted.
+
+@item Translation-Unit local referencing rules
+Papers p1815 (@uref{https://wg21.link/p1815}) and p2003
+(@uref{https://wg21.link/p2003}) add limitations on which entities an
+exported region may reference (for instance, the entities an exported
+template definition may reference).  These are not fully implemented.
+
+@item Standard Library Header Units
+The Standard Library is not provided as importable header units.  If
+you want to import such units, you must explicitly build them first.
+If you do not do this with care, you may have multiple declarations,
+which the module machinery must merge---compiler resource usage can be
+affected by how you partition header files into header units.
+
+@end table
+
+Modular compilation is @emph{not} enabled with just the
+@option{-std=c++20} option.  You must explicitly enable it with the
+@option{-fmodules-ts} option.  It is independent of the language
+version selected, although in pre-C++20 versions, it is of course an
+extension.
+
+No new source file suffixes are required or supported.  If you wish to
+use a non-standard suffix (@pxref{Overall Options}), you also need
+to provide a @option{-x c++} option too.@footnote{Some users like to
+distinguish module interface files with a new suffix, such as naming
+the source @code{module.cppm}, which involves
+teaching all tools about the new suffix.  A different scheme, such as
+naming @code{module-m.cpp} would be less invasive.}
+
+Compiling a module interface unit produces an additional output (to
+the assembly or object file), called a Compiled Module Interface
+(CMI).  This encodes the exported declarations of the module.
+Importing a module reads in the CMI.  The import graph is a Directed
+Acyclic Graph (DAG).  You must build imports before the importer.
+
+Header files may themselves be compiled to header units, which are a
+transitional ability aiming at faster compilation.  The
+@option{-fmodule-header} option is used to enable this, and implies
+the @option{-fmodules-ts} option.  These CMIs are named by the fully
+resolved underlying header file, and thus may be a complete pathname
+containing subdirectories.  If the header file is found at an absolute
+pathname, the CMI location is still relative to a CMI root directory.
+
+As header files often have no suffix, you commonly have to specify a
+@option{-x} option to tell the compiler the source is a header file.
+You may use @option{-x c++-header}, @option{-x c++-user-header} or
+@option{-x c++-system-header}.  When used in conjunction with
+@option{-fmodules-ts}, these all imply an appropriate
+@option{-fmodule-header} option.  The latter two variants use the
+user or system include path to search for the file specified.  This
+allows you to, for instance, compile standard library header files as
+header units, without needing to know exactly where they are
+installed.  Specifying the language as one of these variants also
+inhibits output of the object file, as header files have no associated
+object file.
+
+The @option{-fmodule-only} option disables generation of the
+associated object file for compiling a module interface.  Only the CMI
+is generated.  This option is implied when using the
+@option{-fmodule-header} option.
+
+The @option{-flang-info-include-translate} and
+@option{-flang-info-include-translate-not} options notes whether
+include translation occurs or not.  With no argument, the first will
+note all include translation.  The second will note all
+non-translations of include files not known to intentionally be
+textual.  With an argument, queries about include translation of a
+header files with that particular trailing pathname are noted.  You
+may repeat this form to cover several different header files.  This
+option may be helpful in determining whether include translation is
+happening---if it is working correctly, it behaves as if it isn't
+there at all.
+
+The @option{-flang-info-module-cmi} option can be used to determine
+where the compiler is reading a CMI from.  Without the option, the
+compiler is silent when such a read is successful.  This option has an
+optional argument, which will restrict the notification to just the
+set of named modules or header units specified.
+
+The @option{-Winvalid-imported-macros} option causes all imported macros
+to be resolved at the end of compilation.  Without this, imported
+macros are only resolved when expanded or (re)defined.  This option
+detects conflicting import definitions for all macros.
+
+For details of the @option{-fmodule-mapper} family of options,
+@pxref{C++ Module Mapper}.
+
+@menu
+* C++ Module Mapper::       Module Mapper
+* C++ Module Preprocessing::  Module Preprocessing
+* C++ Compiled Module Interface:: Compiled Module Interface
+@end menu
+
+@node C++ Module Mapper
+@subsection Module Mapper
+@cindex C++ Module Mapper
+
+A module mapper provides a server or file that the compiler queries to
+determine the mapping between module names and CMI files.  It is also
+used to build CMIs on demand.  @emph{Mapper functionality is in its
+infancy and is intended for experimentation with build system
+interactions.}
+
+You can specify a mapper with the @option{-fmodule-mapper=@var{val}}
+option or @env{CXX_MODULE_MAPPER} environment variable.  The value may
+have one of the following forms:
+
+@table @gcctabopt
+
+@item @r{[}@var{hostname}@r{]}:@var{port}@r{[}?@var{ident}@r{]}
+An optional hostname and a numeric port number to connect to.  If the
+hostname is omitted, the loopback address is used.  If the hostname
+corresponds to multiple IPV6 addresses, these are tried in turn, until
+one is successful.  If your host lacks IPv6, this form is
+non-functional.  If you must use IPv4 use
+@option{-fmodule-mapper='|ncat @var{ipv4host} @var{port}'}.
+
+@item =@var{socket}@r{[}?@var{ident}@r{]}
+A local domain socket.  If your host lacks local domain sockets, this
+form is non-functional.
+
+@item |@var{program}@r{[}?@var{ident}@r{]} @r{[}@var{args...}@r{]}
+A program to spawn, and communicate with on its stdin/stdout streams.
+Your @var{PATH} environment variable is searched for the program.
+Arguments are separated by space characters, (it is not possible for
+one of the arguments delivered to the program to contain a space).  An
+exception is if @var{program} begins with @@.  In that case
+@var{program} (sans @@) is looked for in the compiler's internal
+binary directory.  Thus the sample mapper-server can be specified
+with @code{@@g++-mapper-server}.
+
+@item <>@r{[}?@var{ident}@r{]}
+@item <>@var{inout}@r{[}?@var{ident}@r{]}
+@item <@var{in}>@var{out}@r{[}?@var{ident}@r{]}
+Named pipes or file descriptors to communicate over.  The first form,
+@option{<>}, communicates over stdin and stdout.  The other forms
+allow you to specify a file descriptor or name a pipe.  A numeric value
+is interpreted as a file descriptor, otherwise named pipe is opened.
+The second form specifies a bidirectional pipe and the last form
+allows specifying two independent pipes.  Using file descriptors
+directly in this manner is fragile in general, as it can require the
+cooperation of intermediate processes.  In particular using stdin &
+stdout is fraught with danger as other compiler options might also
+cause the compiler to read stdin or write stdout, and it can have
+unfortunate interactions with signal delivery from the terminal.
+
+@item @var{file}@r{[}?@var{ident}@r{]}
+A mapping file consisting of space-separated module-name, filename
+pairs, one per line.  Only the mappings for the direct imports and any
+module export name need be provided.  If other mappings are provided,
+they override those stored in any imported CMI files.  A repository
+root may be specified in the mapping file by using @samp{$root} as the
+module name in the first active line.  Use of this option will disable
+any default module->CMI name mapping.
+
+@end table
+
+As shown, an optional @var{ident} may suffix the first word of the
+option, indicated by a @samp{?} prefix.  The value is used in the
+initial handshake with the module server, or to specify a prefix on
+mapping file lines.  In the server case, the main source file name is
+used if no @var{ident} is specified.  In the file case, all non-blank
+lines are significant, unless a value is specified, in which case only
+lines beginning with @var{ident} are significant.  The @var{ident}
+must be separated by whitespace from the module name.  Be aware that
+@samp{<}, @samp{>}, @samp{?}, and @samp{|} characters are often
+significant to the shell, and therefore may need quoting.
+
+The mapper is connected to or loaded lazily, when the first module
+mapping is required.  The networking protocols are only supported on
+hosts that provide networking.  If no mapper is specified a default is
+provided.
+
+A project-specific mapper is expected to be provided by the build
+system that invokes the compiler.  It is not expected that a
+general-purpose server is provided for all compilations.  As such, the
+server will know the build configuration, the compiler it invoked, and
+the environment (such as working directory) in which that is
+operating.  As it may parallelize builds, several compilations may
+connect to the same socket.
+
+The default mapper generates CMI files in a @samp{gcm.cache}
+directory.  CMI files have a @samp{.gcm} suffix.  The module unit name
+is used directly to provide the basename.  Header units construct a
+relative path using the underlying header file name.  If the path is
+already relative, a @samp{,} directory is prepended.  Internal
+@samp{..} components are translated to @samp{,,}.  No attempt is made
+to canonicalize these filenames beyond that done by the preprocessor's
+include search algorithm, as in general it is ambiguous when symbolic
+links are present.
+
+The mapper protocol was published as ``A Module Mapper''
+@uref{https://wg21.link/p1184}.  The implementation is provided by
+@command{libcody}, @uref{https://github.com/urnathan/libcody},
+which specifies the canonical protocol definition.  A proof of concept
+server implementation embedded in @command{make} was described in
+''Make Me A Module'', @uref{https://wg21.link/p1602}.
+
+@node C++ Module Preprocessing
+@subsection Module Preprocessing
+@cindex C++ Module Preprocessing
+
+Modules affect preprocessing because of header units and include
+translation.  Some uses of the preprocessor as a separate step either
+do not produce a correct output, or require CMIs to be available.
+
+Header units import macros.  These macros can affect later conditional
+inclusion, which therefore can cascade to differing import sets.  When
+preprocessing, it is necessary to load the CMI.  If a header unit is
+unavailable, the preprocessor issues a warning and continue (when
+not just preprocessing, an error is emitted).  Detecting such imports
+requires preprocessor tokenization of the input stream to phase 4
+(macro expansion).
+
+Include translation converts @code{#include}, @code{#include_next} and
+@code{#import} directives to internal @code{import} declarations.
+Whether a particular directive is translated is controlled by the
+module mapper.  Header unit names are canonicalized during
+preprocessing.
+
+Dependency information can be emitted for macro import, extending the
+functionality of @option{-MD} and @option{-MMD} options.  Detection of
+import declarations also requires phase 4 preprocessing, and thus
+requires full preprocessing (or compilation).
+
+The @option{-M}, @option{-MM} and @option{-E -fdirectives-only} options halt
+preprocessing before phase 4.
+
+The @option{-save-temps} option uses @option{-fdirectives-only} for
+preprocessing, and preserve the macro definitions in the preprocessed
+output.  Usually you also want to use this option when explicitly
+preprocessing a header-unit, or consuming such preprocessed output:
+
+@smallexample
+g++ -fmodules-ts -E -fdirectives-only my-header.hh -o my-header.ii
+g++ -x c++-header -fmodules-ts -fpreprocessed -fdirectives-only my-header.ii
+@end smallexample
+
+@node C++ Compiled Module Interface
+@subsection Compiled Module Interface
+@cindex C++ Compiled Module Interface
+
+CMIs are an additional artifact when compiling named module
+interfaces, partitions or header units.  These are read when
+importing.  CMI contents are implementation-specific, and in GCC's
+case tied to the compiler version.  Consider them a rebuildable cache
+artifact, not a distributable object.
+
+When creating an output CMI, any missing directory components are
+created in a manner that is safe for concurrent builds creating
+multiple, different, CMIs within a common subdirectory tree.
+
+CMI contents are written to a temporary file, which is then atomically
+renamed.  Observers either see old contents (if there is an
+existing file), or complete new contents.  They do not observe the
+CMI during its creation.  This is unlike object file writing, which
+may be observed by an external process.
+
+CMIs are read in lazily, if the host OS provides @code{mmap}
+functionality.  Generally blocks are read when name lookup or template
+instantiation occurs.  To inhibit this, the @option{-fno-module-lazy}
+option may be used.
+
+The @option{--param lazy-modules=@var{n}} parameter controls the limit
+on the number of concurrently open module files during lazy loading.
+Should more modules be imported, an LRU algorithm is used to determine
+which files to close---until that file is needed again.  This limit
+may be exceeded with deep module dependency hierarchies.  With large
+code bases there may be more imports than the process limit of file
+descriptors.  By default, the limit is a few less than the per-process
+file descriptor hard limit, if that is determinable.@footnote{Where
+applicable the soft limit is incremented as needed towards the hard limit.}
+
+GCC CMIs use ELF32 as an architecture-neutral encapsulation mechanism.
+You may use @command{readelf} to inspect them, although section
+contents are largely undecipherable.  There is a section named
+@code{.gnu.c++.README}, which contains human-readable text.  Other
+than the first line, each line consists of @code{@var{tag}: @code{value}}
+tuples.
+
+@smallexample
+> @command{readelf -p.gnu.c++.README gcm.cache/foo.gcm}
+
+String dump of section '.gnu.c++.README':
+  [     0]  GNU C++ primary module interface
+  [    21]  compiler: 11.0.0 20201116 (experimental) [c++-modules revision 20201116-0454]
+  [    6f]  version: 2020/11/16-04:54
+  [    89]  module: foo
+  [    95]  source: c_b.ii
+  [    a4]  dialect: C++20/coroutines
+  [    be]  cwd: /data/users/nathans/modules/obj/x86_64/gcc
+  [    ee]  repository: gcm.cache
+  [   104]  buildtime: 2020/11/16 15:03:21 UTC
+  [   127]  localtime: 2020/11/16 07:03:21 PST
+  [   14a]  export: foo:part1 foo-part1.gcm
+@end smallexample
+
+Amongst other things, this lists the source that was built, C++
+dialect used and imports of the module.@footnote{The precise contents
+of this output may change.} The timestamp is the same value as that
+provided by the @code{__DATE__} & @code{__TIME__} macros, and may be
+explicitly specified with the environment variable
+@code{SOURCE_DATE_EPOCH}.  For further details
+@pxref{Environment Variables}.
+
+A set of related CMIs may be copied, provided the relative pathnames
+are preserved.
+
+The @code{.gnu.c++.README} contents do not affect CMI integrity, and
+it may be removed or altered.  The section numbering of the sections
+whose names do not begin with @code{.gnu.c++.}, or are not the string
+section is significant and must not be altered.