[Driver] Add support for -fembed-bitcode for assembly file

Summary:
Handle -fembed-bitcode for assembly inputs. When the input file is
assembly, write a marker as "__LLVM,__asm" section.

Fix llvm.org/pr39659

Reviewers: compnerd, dexonsmith

Reviewed By: compnerd

Subscribers: rjmccall, dblaikie, jkorous, cfe-commits

Differential Revision: https://reviews.llvm.org/D55525

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@348943 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 41 insertions, 1 deletions

diff --git a/include/clang/Driver/Options.td b/include/clang/Driver/Options.td
index 0a96820734..623ab898ec 100644
--- a/include/clang/Driver/Options.td
+++ b/include/clang/Driver/Options.td
@@ -675,7 +675,7 @@ def fno_coroutines_ts : Flag <["-"], "fno-coroutines-ts">, Group<f_Group>,
   Flags<[DriverOption]>;
 
 def fembed_bitcode_EQ : Joined<["-"], "fembed-bitcode=">,
-    Group<f_Group>, Flags<[DriverOption, CC1Option]>, MetaVarName<"<option>">,
+    Group<f_Group>, Flags<[DriverOption, CC1Option, CC1AsOption]>, MetaVarName<"<option>">,
     HelpText<"Embed LLVM bitcode (option: off, all, bitcode, marker)">;
 def fembed_bitcode : Flag<["-"], "fembed-bitcode">, Group<f_Group>,
   Alias<fembed_bitcode_EQ>, AliasArgs<["all"]>,
diff --git a/lib/Driver/ToolChains/Clang.cpp b/lib/Driver/ToolChains/Clang.cpp
index 360397cf5b..614220cba1 100644
--- a/lib/Driver/ToolChains/Clang.cpp
+++ b/lib/Driver/ToolChains/Clang.cpp
@@ -2167,6 +2167,11 @@ static void CollectArgsForIntegratedAssembler(Compilation &C,
     CmdArgs.push_back("-target-feature");
     CmdArgs.push_back(MipsTargetFeature);
   }
+
+  // forward -fembed-bitcode to assmebler
+  if (C.getDriver().embedBitcodeEnabled() ||
+      C.getDriver().embedBitcodeMarkerOnly())
+    Args.AddLastArg(CmdArgs, options::OPT_fembed_bitcode_EQ);
 }
 
 static void RenderFloatingPointOptions(const ToolChain &TC, const Driver &D,
diff --git a/test/Driver/embed-bitcode.s b/test/Driver/embed-bitcode.s
new file mode 100644
index 0000000000..71a3e9c2fb
--- /dev/null
+++ b/test/Driver/embed-bitcode.s
@@ -0,0 +1,12 @@
+// REQUIRES: arm-registered-target
+
+// RUN: %clang -c -target armv7-apple-ios10 %s -fembed-bitcode -### 2>&1 | FileCheck %s -check-prefix=CHECK-AS
+// RUN: %clang -c -target armv7-apple-ios10 %s -fembed-bitcode-marker -### 2>&1 | FileCheck %s -check-prefix=CHECK-AS-MARKER
+// CHECK-AS: -cc1as
+// CHECK-AS: -fembed-bitcode=all
+// CHECK-AS-MARKER: -fembed-bitcode=marker
+
+// RUN: %clang -c -target armv7-apple-ios10 %s -fembed-bitcode -o %t.o
+// RUN: llvm-readobj -section-headers %t.o | FileCheck --check-prefix=CHECK-SECTION %s
+// CHECK-SECTION: Name: __asm
+// CHECK-SECTION-NEXT: Segment: __LLVM
diff --git a/tools/driver/cc1as_main.cpp b/tools/driver/cc1as_main.cpp
index 9e454cdd0f..be4f174ed4 100644
--- a/tools/driver/cc1as_main.cpp
+++ b/tools/driver/cc1as_main.cpp
@@ -33,6 +33,7 @@
 #include "llvm/MC/MCParser/MCAsmParser.h"
 #include "llvm/MC/MCParser/MCTargetAsmParser.h"
 #include "llvm/MC/MCRegisterInfo.h"
+#include "llvm/MC/MCSectionMachO.h"
 #include "llvm/MC/MCStreamer.h"
 #include "llvm/MC/MCSubtargetInfo.h"
 #include "llvm/MC/MCTargetOptions.h"
@@ -132,6 +133,7 @@ struct AssemblerInvocation {
   unsigned NoExecStack : 1;
   unsigned FatalWarnings : 1;
   unsigned IncrementalLinkerCompatible : 1;
+  unsigned EmbedBitcode : 1;
 
   /// The name of the relocation model to use.
   std::string RelocationModel;
@@ -153,6 +155,7 @@ public:
     FatalWarnings = 0;
     IncrementalLinkerCompatible = 0;
     DwarfVersion = 0;
+    EmbedBitcode = 0;
   }
 
   static bool CreateFromArgs(AssemblerInvocation &Res,
@@ -284,6 +287,16 @@ bool AssemblerInvocation::CreateFromArgs(AssemblerInvocation &Opts,
       Args.hasArg(OPT_mincremental_linker_compatible);
   Opts.SymbolDefs = Args.getAllArgValues(OPT_defsym);
 
+  // EmbedBitcode Option. If -fembed-bitcode is enabled, set the flag.
+  // EmbedBitcode behaves the same for all embed options for assembly files.
+  if (auto *A = Args.getLastArg(OPT_fembed_bitcode_EQ)) {
+    Opts.EmbedBitcode = llvm::StringSwitch<unsigned>(A->getValue())
+                            .Case("all", 1)
+                            .Case("bitcode", 1)
+                            .Case("marker", 1)
+                            .Default(0);
+  }
+
   return Success;
 }
 
@@ -449,6 +462,16 @@ static bool ExecuteAssembler(AssemblerInvocation &Opts,
     Str.get()->InitSections(Opts.NoExecStack);
   }
 
+  // When -fembed-bitcode is passed to clang_as, a 1-byte marker
+  // is emitted in __LLVM,__asm section if the object file is MachO format.
+  if (Opts.EmbedBitcode && Ctx.getObjectFileInfo()->getObjectFileType() ==
+                               MCObjectFileInfo::IsMachO) {
+    MCSection *AsmLabel = Ctx.getMachOSection(
+        "__LLVM", "__asm", MachO::S_REGULAR, 4, SectionKind::getReadOnly());
+    Str.get()->SwitchSection(AsmLabel);
+    Str.get()->EmitZeros(1);
+  }
+
   // Assembly to object compilation should leverage assembly info.
   Str->setUseAssemblerInfoForParsing(true);