re PR tree-optimization/50767 (ICE: in refs_may_alias_p_1, at…

re PR tree-optimization/50767 (ICE: in refs_may_alias_p_1, at tree-ssa-alias.c:1004 with -O2 -fno-tree-copy-prop -fno-tree-dominator-opts)

2011-10-18  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/50767
	* tree-ssa-pre.c (create_expression_by_pieces): Update the
	folded statement.

	* gcc.dg/torture/pr50767.c: New testcase.

From-SVN: r180134

gcc/ChangeLog

+2011-10-18  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/50767
+	* tree-ssa-pre.c (create_expression_by_pieces): Update the
+	folded statement.
+
 2011-10-18  Julian Brown  <julian@codesourcery.com>
 
 	* config/arm/arm.c (arm_block_move_unaligned_straight)

gcc/testsuite/ChangeLog

+2011-10-18  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/50767
+	* gcc.dg/torture/pr50767.c: New testcase.
+
 2011-10-18  Julian Brown  <julian@codesourcery.com>
 
 	* lib/target-supports.exp (check_effective_target_arm_unaligned): New.

gcc/testsuite/gcc.dg/torture/pr50767.c

+/* { dg-do compile } */
+/* { dg-options "-fno-tree-copy-prop -fno-tree-dominator-opts" } */
+
+struct S
+{
+  struct S *s;
+};
+
+static struct S *ss;
+struct S *s;
+
+void bar(void);
+
+void foo(void)
+{
+  for (;;)
+    {
+      s->s = ss;
+      bar ();
+    }
+}

gcc/tree-ssa-pre.c

@@ -3188,7 +3188,8 @@ create_expression_by_pieces (basic_block block, pre_expr expr,
 
   /* Fold the last statement.  */
   gsi = gsi_last (*stmts);
-  fold_stmt_inplace (&gsi);
+  if (fold_stmt_inplace (&gsi))
+    update_stmt (gsi_stmt (gsi));
 
   /* Add a value number to the temporary.
      The value may already exist in either NEW_SETS, or AVAIL_OUT, because