re PR tree-optimization/33302 (dead-store not eliminated)

2007-09-06  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/33302
	* tree-ssa-dse.c (tree_ssa_dse): Connect infinite loops
	to the exit block before doing the post-dominator walk.
	* domwalk.c (walk_dominator_tree): The exit block is
	interesting even if it is not reachable.

	* gcc.dg/tree-ssa/ssa-dse-11.c: New testcase.

From-SVN: r128180

gcc/ChangeLog

+2007-09-06  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/33302
+	* domwalk.c (walk_dominator_tree): The exit block is
+	interesting even if it is not reachable.
+
 2007-09-06  Richard Sandiford  <richard@codesourcery.com>
 
 	PR middle-end/33306

gcc/domwalk.c

@@ -151,7 +151,9 @@ walk_dominator_tree (struct dom_walk_data *walk_data, basic_block bb)
   while (true)
     {
       /* Don't worry about unreachable blocks.  */
-      if (EDGE_COUNT (bb->preds) > 0 || bb == ENTRY_BLOCK_PTR)
+      if (EDGE_COUNT (bb->preds) > 0
+	  || bb == ENTRY_BLOCK_PTR
+	  || bb == EXIT_BLOCK_PTR)
 	{
 	  /* If block BB is not interesting to the caller, then none of the
 	     callbacks that walk the statements in BB are going to be

gcc/testsuite/ChangeLog

+2007-09-06  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/33302
+	* gcc.dg/tree-ssa/ssa-dse-11.c: New testcase.
+
 2007-09-06  Jerry DeLisle  <jvdelisle@gcc.gnu.org>
 
 	PR libfortran/33225

gcc/testsuite/gcc.dg/tree-ssa/ssa-dse-11.c

+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-dse1-details" } */
+
+extern void abort(void);
+void foo(int *p)
+{
+  while (1)
+   {
+      *p = 0;
+      *p = 0;
+   }
+}
+void bar(int *p)
+{
+  *p = 0;
+  *p = 0;
+  abort ();
+}
+
+/* { dg-final { scan-tree-dump-times "Deleted dead store" 2 "dse1" } } */
+/* { dg-final { cleanup-tree-dump "dse1" } } */