[x86] Fix PR target/48142

[Eric Botcazou <ebotcazou at adacore dot com>]

Hi,

this is a regression present for x86-64 on mainline and 4.6 branch with the 
options -Os -mpreferred-stack-boundary=5 -fstack-check -fno-omit-frame-pointer.
This improbable combination of options is necessary because you need to have 
stack checking + stack realignment + !ACCUMULATE_OUTGOING_ARGS.  In this case, 
the DW_CFA_GNU_args_size CFIs must be correct in spite of the frame pointer.

Tested on {i586,x86_64}-suse-linux, OK for mainline and 4.6 branch?


2011-03-30  Eric Botcazou  <ebotcazou@adacore.com>

	PR target/48142
	* config/i386/i386.c (ix86_adjust_stack_and_probe): Differentiate
	frame-related from frame-unrelated adjustments to the stack pointer.


2011-03-30  Eric Botcazou  <ebotcazou@adacore.com>

	* g++.dg/other/pr48142.C: New test.


-- 
Eric Botcazou

// PR target/48142
// Testcase by Zdenek Sojka <zsojka@seznam.cz>

// { dg-do run { target i?86-*-* x86_64-*-* } }
// { dg-options "-Os -mpreferred-stack-boundary=5 -fstack-check -fno-omit-frame-pointer" }

int main()
{
  try { throw 0; }
  catch (...) {}
  return 0;
}

Index: config/i386/i386.c
===================================================================
--- config/i386/i386.c	(revision 171716)
+++ config/i386/i386.c	(working copy)
@@ -10006,7 +10006,7 @@ ix86_adjust_stack_and_probe (const HOST_
      probe that many bytes past the specified size to maintain a protection
      area at the botton of the stack.  */
   const int dope = 4 * UNITS_PER_WORD;
-  rtx size_rtx = GEN_INT (size);
+  rtx size_rtx = GEN_INT (size), last;
 
   /* See if we have a constant small number of probes to generate.  If so,
      that's the easy case.  The run-time loop is made up of 11 insns in the
@@ -10046,9 +10046,9 @@ ix86_adjust_stack_and_probe (const HOST_
       emit_stack_probe (stack_pointer_rtx);
 
       /* Adjust back to account for the additional first interval.  */
-      emit_insn (gen_rtx_SET (VOIDmode, stack_pointer_rtx,
-			      plus_constant (stack_pointer_rtx,
-					     PROBE_INTERVAL + dope)));
+      last = emit_insn (gen_rtx_SET (VOIDmode, stack_pointer_rtx,
+				     plus_constant (stack_pointer_rtx,
+						    PROBE_INTERVAL + dope)));
     }
 
   /* Otherwise, do the same as above, but in a loop.  Note that we must be
@@ -10109,15 +10109,33 @@ ix86_adjust_stack_and_probe (const HOST_
 	}
 
       /* Adjust back to account for the additional first interval.  */
-      emit_insn (gen_rtx_SET (VOIDmode, stack_pointer_rtx,
-			      plus_constant (stack_pointer_rtx,
-					     PROBE_INTERVAL + dope)));
+      last = emit_insn (gen_rtx_SET (VOIDmode, stack_pointer_rtx,
+				     plus_constant (stack_pointer_rtx,
+						    PROBE_INTERVAL + dope)));
 
       release_scratch_register_on_entry (&sr);
     }
 
   gcc_assert (cfun->machine->fs.cfa_reg != stack_pointer_rtx);
-  cfun->machine->fs.sp_offset += size;
+
+  /* Even if the stack pointer isn't the CFA register, we need to correctly
+     describe the adjustments made to it, in particular differentiate the
+     frame-related ones from the frame-unrelated ones.  */
+  if (size > 0)
+    {
+      rtx expr = gen_rtx_SEQUENCE (VOIDmode, rtvec_alloc (2));
+      XVECEXP (expr, 0, 0)
+	= gen_rtx_SET (VOIDmode, stack_pointer_rtx,
+		       plus_constant (stack_pointer_rtx, -size));
+      XVECEXP (expr, 0, 1)
+	= gen_rtx_SET (VOIDmode, stack_pointer_rtx,
+		       plus_constant (stack_pointer_rtx,
+				      PROBE_INTERVAL + dope + size));
+      add_reg_note (last, REG_FRAME_RELATED_EXPR, expr);
+      RTX_FRAME_RELATED_P (last) = 1;
+
+      cfun->machine->fs.sp_offset += size;
+    }
 
   /* Make sure nothing is scheduled before we are done.  */
   emit_insn (gen_blockage ());