From: Richard Biener <rguenther@suse.de>
Date: Wed, 4 Jun 2014 11:59:45 +0000 (+0000)
Subject: backport: re PR tree-optimization/57230 (tree-ssa-strlen incorrectly optimizes a... 
X-Git-Tag: releases/gcc-4.7.4~53
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=29006014264a5ae4821a33301928c9c0f1cf14ff;p=thirdparty%2Fgcc.git

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

2014-06-04  Richard Biener  <rguenther@suse.de>

	Backport from mainline
	2013-05-13  Jakub Jelinek  <jakub@redhat.com>

	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: r211225
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 4acd9e7536e3..e305bf1f3f17 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,12 @@
+2014-06-04  Richard Biener  <rguenther@suse.de>
+
+	Backport from mainline
+	2013-05-13  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/57230
+	* tree-ssa-strlen.c (handle_char_store): Add missing integer_zerop
+	check.
+
 2014-05-28  Georg-Johann Lay  <avr@gjlay.de>
 
 	PR target/61044
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 8ebcd8c6c6fa..62e9a63e011d 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2014-06-04  Richard Biener  <rguenther@suse.de>
+
+	Backport from mainline
+	2013-05-13  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/57230
+	* gcc.dg/strlenopt-23.c: New test.
+
 2014-05-27  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* gnat.dg/aliasing1.adb (dg-final): Robustify pattern matching.
diff --git a/gcc/testsuite/gcc.dg/strlenopt-23.c b/gcc/testsuite/gcc.dg/strlenopt-23.c
new file mode 100644
index 000000000000..75dab2ae0bb9
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/strlenopt-23.c
@@ -0,0 +1,15 @@
+/* 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;
+}
diff --git a/gcc/tree-ssa-strlen.c b/gcc/tree-ssa-strlen.c
index 3a3aeeac9f2a..532bdac3faa5 100644
--- a/gcc/tree-ssa-strlen.c
+++ b/gcc/tree-ssa-strlen.c
@@ -1693,7 +1693,7 @@ 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);