re PR tree-optimization/57230 (tree-ssa-strlen incorrectly optimizes a strlen to 0)

	PR tree-optimization/57230
	* tree-ssa-strlen.c (handle_char_store): Add missing integer_zerop
	check.

	* gcc.dg/strlenopt-23.c: New test.

From-SVN: r198813

gcc/ChangeLog

+2013-05-13  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/57230
+	* tree-ssa-strlen.c (handle_char_store): Add missing integer_zerop
+	check.
+
 2013-05-12  Joern Rennecke  <joern.rennecke@embecosm.com>
 
 	* config/epiphany/epiphany.c (epiphany_init): Check size of

gcc/testsuite/ChangeLog

+2013-05-13  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/57230
+	* gcc.dg/strlenopt-23.c: New test.
+
 2013-05-12  Oleg Endo  <olegendo@gcc.gnu.org>
 
 	PR target/57108

gcc/testsuite/gcc.dg/strlenopt-23.c

+/* PR tree-optimization/57230 */
+/* { dg-do run } */
+/* { dg-options "-O2" } */
+
+#include "strlenopt.h"
+
+int
+main ()
+{
+  char p[] = "hello world";
+  p[0] = (char) (strlen (p) - 1);
+  if (strlen (p) != 11)
+    abort ();
+  return 0;
+}

gcc/tree-ssa-strlen.c

@@ -1703,7 +1703,7 @@ handle_char_store (gimple_stmt_iterator *gsi)
 	       its length may be decreased.  */
 	    adjust_last_stmt (si, stmt, false);
 	}
-      else if (si != NULL)
+      else if (si != NULL && integer_zerop (gimple_assign_rhs1 (stmt)))
 	{
 	  si = unshare_strinfo (si);
 	  si->length = build_int_cst (size_type_node, 0);