[PATCH] Fix PR41728

[PATCH] Fix PR41728

[Richard Guenther]

DOM relies on the modified flag, so set it if fold_stmt folded
anything.

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

Richard.

2009-10-16  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/41728
	* tree-ssa-dom.c (optimize_stmt): Mark the stmt modified
	if fold_stmt did anything.

	* gcc.c-torture/compile/pr41728.c: New testcase.

Index: gcc/tree-ssa-dom.c
===================================================================
*** gcc/tree-ssa-dom.c	(revision 152897)
--- gcc/tree-ssa-dom.c	(working copy)
*************** optimize_stmt (basic_block bb, gimple_st
*** 2099,2104 ****
--- 2099,2105 ----
        if (fold_stmt (&si))
  	{
  	  stmt = gsi_stmt (si);
+ 	  gimple_set_modified (stmt, true);
  
  	  if (dump_file && (dump_flags & TDF_DETAILS))
  	    {
Index: gcc/testsuite/gcc.c-torture/compile/pr41728.c
===================================================================
*** gcc/testsuite/gcc.c-torture/compile/pr41728.c	(revision 0)
--- gcc/testsuite/gcc.c-torture/compile/pr41728.c	(revision 0)
***************
*** 0 ****
--- 1,12 ----
+ int a[8];
+ int s244(void)
+ {
+   int lrc, j;
+   lrc = 0;
+   for (j=0; j<7; j++)
+     if(a[j] != a[j+1])
+       lrc = 1;
+   if (lrc != 0)
+     return 0;
+   return 1;
+ }