re PR c/61741 (wrong code with -fno-strict-overflow)

2014-07-09  Richard Biener  <rguenther@suse.de>

	PR c-family/61741
	* c-gimplify.c (c_gimplify_expr): Gimplify self-modify expressions
	using unsigned arithmetic if overflow does not wrap instead of
	if overflow is undefined.

	* c-c++-common/torture/pr61741.c: New testcase.

From-SVN: r212400

gcc/c-family/ChangeLog

+2014-07-09  Richard Biener  <rguenther@suse.de>
+
+	PR c-family/61741
+	* c-gimplify.c (c_gimplify_expr): Gimplify self-modify expressions
+	using unsigned arithmetic if overflow does not wrap instead of
+	if overflow is undefined.
+
 2014-07-06  Marek Polacek  <polacek@redhat.com>
 
 	PR c/6940

gcc/c-family/c-gimplify.c

@@ -240,9 +240,7 @@ c_gimplify_expr (tree *expr_p, gimple_seq *pre_p ATTRIBUTE_UNUSED,
 	tree type = TREE_TYPE (TREE_OPERAND (*expr_p, 0));
 	if (INTEGRAL_TYPE_P (type) && c_promoting_integer_type_p (type))
 	  {
-	    if (TYPE_OVERFLOW_UNDEFINED (type)
-		|| ((flag_sanitize & SANITIZE_SI_OVERFLOW)
-		    && !TYPE_OVERFLOW_WRAPS (type)))
+	    if (!TYPE_OVERFLOW_WRAPS (type))
 	      type = unsigned_type_for (type);
 	    return gimplify_self_mod_expr (expr_p, pre_p, post_p, 1, type);
 	  }

gcc/testsuite/ChangeLog

+2014-07-09  Richard Biener  <rguenther@suse.de>
+
+	PR c-family/61741
+	* c-c++-common/torture/pr61741.c: New testcase.
+
 2014-07-09  Pat Haugen  <pthaugen@us.ibm.com>
 
 	* lib/target-supports.exp

gcc/testsuite/c-c++-common/torture/pr61741.c

+/* { dg-do run } */
+
+int a = 1, b;
+
+void
+foo (void)
+{
+  char c = 0;
+  for (; a; a--)
+    for (; c >= 0; c++);
+  if (!c)
+    b = 1;
+}
+
+int
+main ()
+{
+  foo ();
+  if (b != 0)
+    __builtin_abort ();
+  return 0;
+}