[Bug target/63890] [4.9/5 regression] Compiling trivial program with -O -p leads to misaligned stack

[Jan Hubicka]

Hi,
the problem is that darwin output profiler after prologue.
With ACCUMULATE_OUTGOING_ARGS we leave stack pointer aligned to boundary - 4
(for return pointer) without we leave it aligned.
I guess it is possible to compensate this in FUNCTION_PROFILER, but I am not
convinced this will work reliably. Probably disabling combine-stack-adjustments
would be needed, too.
(I do not think it is reliable with ACCUMULATE_OUTGOING_ARGS either)

Honza

Index: config/i386/darwin.h
===================================================================
--- config/i386/darwin.h	(revision 221034)
+++ config/i386/darwin.h	(working copy)
@@ -210,6 +210,8 @@ extern int darwin_emit_branch_islands;
 #undef FUNCTION_PROFILER
 #define FUNCTION_PROFILER(FILE, LABELNO)				\
     do {								\
+      if (!ACCUMULATE_OUTGOING_ARGS)					\
+        fprintf (FILE, "\tpushl %%ebx\n");  /*  Align stack  */		\
       if (TARGET_MACHO_BRANCH_ISLANDS 					\
 	   && MACHOPIC_INDIRECT && !TARGET_64BIT)			\
 	{								\
@@ -218,6 +220,8 @@ extern int darwin_emit_branch_islands;
 	  machopic_validate_stub_or_non_lazy_ptr (name);		\
 	}								\
       else fprintf (FILE, "\tcall mcount\n");				\
+      if (!ACCUMULATE_OUTGOING_ARGS)					\
+       fprintf (FILE, "\tpopl %%ebx\n");  /*  Align stack  */		\
     } while (0)
 
 #define C_COMMON_OVERRIDE_OPTIONS					\
Index: config/i386/i386.c
===================================================================
--- config/i386/i386.c	(revision 221034)
+++ config/i386/i386.c	(working copy)
@@ -10061,6 +10061,13 @@ ix86_compute_frame_layout (struct ix86_f
       if (crtl->stack_alignment_needed < PREFERRED_STACK_BOUNDARY)
 	crtl->stack_alignment_needed = PREFERRED_STACK_BOUNDARY;
     }
+  /* Be sure we get stack aligned for mcount call.  */
+  else if (crtl->profile && flag_fentry)
+    {
+      crtl->preferred_stack_boundary = PREFERRED_STACK_BOUNDARY;
+      if (crtl->stack_alignment_needed < PREFERRED_STACK_BOUNDARY)
+	crtl->stack_alignment_needed = PREFERRED_STACK_BOUNDARY;
+    }
 
   stack_alignment_needed = crtl->stack_alignment_needed / BITS_PER_UNIT;
   preferred_alignment = crtl->preferred_stack_boundary / BITS_PER_UNIT;