[PATCH] Fix PR50389

[Richard Guenther]

This fixes missed placements of VUSEs during 
gimplify_and_update_call_from_tree.  The gimplifier doesn't fill
out virtual operands (it doesn't call update_stmt) - for a reason,
we'd mark it for renaming else.  So we have to stick a VUSE on
every stmt that can possibly have one.  update_stmt will remove
it again when it is not necessary.

Bootstrapped and tested on x86_64-unknown-linux-gnu, applied.

Richard.

2011-10-10  Richard Guenther  <rguenther@suse.de>

	PR middle-end/50389
	* gimple-fold.c (gimplify_and_update_call_from_tree): Do not
	mark symbols for renaming.  Append the VUSE to all statements
	that possibly can have one.

	* gcc.dg/torture/pr50389.c: New testcase.

Index: gcc/gimple-fold.c
===================================================================
*** gcc/gimple-fold.c	(revision 179738)
--- gcc/gimple-fold.c	(working copy)
*************** gimplify_and_update_call_from_tree (gimp
*** 588,600 ****
  	}
        new_stmt = gsi_stmt (i);
        if (gimple_in_ssa_p (cfun))
! 	{
! 	  find_new_referenced_vars (new_stmt);
! 	  mark_symbols_for_renaming (new_stmt);
! 	}
!       /* If the new statement has a VUSE, update it with exact SSA name we
!          know will reach this one.  */
!       if (gimple_vuse (new_stmt))
  	{
  	  /* If we've also seen a previous store create a new VDEF for
  	     the latter one, and make that the new reaching VUSE.  */
--- 588,597 ----
  	}
        new_stmt = gsi_stmt (i);
        if (gimple_in_ssa_p (cfun))
! 	find_new_referenced_vars (new_stmt);
!       /* If the new statement possibly has a VUSE, update it with exact SSA
! 	 name we know will reach this one.  */
!       if (gimple_has_mem_ops (new_stmt))
  	{
  	  /* If we've also seen a previous store create a new VDEF for
  	     the latter one, and make that the new reaching VUSE.  */
Index: gcc/testsuite/gcc.dg/torture/pr50389.c
===================================================================
*** gcc/testsuite/gcc.dg/torture/pr50389.c	(revision 0)
--- gcc/testsuite/gcc.dg/torture/pr50389.c	(revision 0)
***************
*** 0 ****
--- 1,15 ----
+ /* { dg-do compile } */
+ /* { dg-options "-freorder-blocks -ftracer" } */
+ 
+ extern int data[];
+ extern int i;
+ 
+ void
+ foo (void)
+ {
+   char buf[8];
+   __builtin___memcpy_chk (buf, data, i ? 8 : 4,
+ 			  __builtin_object_size (buf, 0));
+   __builtin___memcpy_chk (buf, data, i ? 8 : 4,
+ 			  __builtin_object_size (buf, 0));
+ }