* config/i386/i386.c (ix86_expand_prologue): Emit a memory blockage

	after restoring registers saved to allocate the frame on Windows.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/gcc-8-branch@268594 138bc75d-0d04-0410-961f-82ee72b054a4

4 files changed, 50 insertions, 2 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 20d8649ce97..134aec4d7df 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2019-02-06  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* config/i386/i386.c (ix86_expand_prologue): Emit a memory blockage
+	after restoring registers saved to allocate the frame on Windows.
+
 2019-02-06  Richard Biener  <rguenther@suse.de>
 
 	Backport from mainline
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index f98cf0852e5..bb88b6cf471 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -14088,8 +14088,9 @@ ix86_expand_prologue (void)
 	}
       m->fs.sp_offset += allocate;
 
-      /* Use stack_pointer_rtx for relative addressing so that code
-	 works for realigned stack, too.  */
+      /* Use stack_pointer_rtx for relative addressing so that code works for
+	 realigned stack.  But this means that we need a blockage to prevent
+	 stores based on the frame pointer from being scheduled before.  */
       if (r10_live && eax_live)
         {
 	  t = gen_rtx_PLUS (Pmode, stack_pointer_rtx, eax);
@@ -14098,6 +14099,7 @@ ix86_expand_prologue (void)
 	  t = plus_constant (Pmode, t, UNITS_PER_WORD);
 	  emit_move_insn (gen_rtx_REG (word_mode, AX_REG),
 			  gen_frame_mem (word_mode, t));
+	  emit_insn (gen_memory_blockage ());
 	}
       else if (eax_live || r10_live)
 	{
@@ -14105,6 +14107,7 @@ ix86_expand_prologue (void)
 	  emit_move_insn (gen_rtx_REG (word_mode,
 				       (eax_live ? AX_REG : R10_REG)),
 			  gen_frame_mem (word_mode, t));
+	  emit_insn (gen_memory_blockage ());
 	}
     }
   gcc_assert (m->fs.sp_offset == frame.stack_pointer_offset);
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 1e2c758c2f7..04e58302975 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2019-02-06  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* gnat.dg/opt76.adb: New test.
+
 2019-02-06  Richard Biener  <rguenther@suse.de>
 
 	Backport from mainline
diff --git a/gcc/testsuite/gnat.dg/opt76.adb b/gcc/testsuite/gnat.dg/opt76.adb
new file mode 100644
index 00000000000..50f3cee9ed9
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/opt76.adb
@@ -0,0 +1,36 @@
+-- { dg-do run }
+-- { dg-options "-O2 -gnatp -fno-omit-frame-pointer" }
+
+procedure Opt76 is
+
+   type Integer_Access is access Integer;
+   type Registry_Array is array (Natural range <>) of Integer_Access;
+
+   procedure Nested (Input, Parser : Integer; A, B : Boolean) is
+
+      Index : Registry_Array (1 .. 1024);
+      Not_B : constant Boolean := not B;
+
+      procedure Inner (Input : Integer) is
+      begin
+         if Input /= 1 then
+            raise Program_Error;
+         end if;
+
+         if Parser = 128 and then A and then Not_B then
+            Inner (Input);
+            Index (Index'First) := null;
+         end if;
+      end;
+
+   begin
+      Inner (Input);
+   end;
+
+   Input : Integer := 1 with Volatile;
+   Parser : Integer := 2 with Volatile;
+      
+begin
+   Nested (Input, Parser, False, True);
+   Nested (Input, Parser, True, False);
+end;