tree-vrp.c (compare_name_with_value): Always set used_strict_overflow if we get…

tree-vrp.c (compare_name_with_value): Always set used_strict_overflow if we get a result from the variable itself.

./:	* tree-vrp.c (compare_name_with_value): Always set
	used_strict_overflow if we get a result from the variable itself.
testsuite/:
	* gcc.dg/Wstrict-overflow-17.c: New test.

From-SVN: r125269

gcc/ChangeLog

 2007-06-01  Ian Lance Taylor  <iant@google.com>
 
+	* tree-vrp.c (compare_name_with_value): Always set
+	used_strict_overflow if we get a result from the variable itself.
+
+2007-06-01  Ian Lance Taylor  <iant@google.com>
+
 	PR rtl-optimization/31455
 	* lower-subreg.c (find_decomposable_subregs): Don't decompose
 	subregs which have a cast between modes which are not tieable.

gcc/testsuite/ChangeLog

+2007-06-01  Ian Lance Taylor  <iant@google.com>
+
+	* gcc.dg/Wstrict-overflow-17.c: New test.
+
 2007-06-01  Kazu Hirata  <kazu@codesourcery.com>
 
 	* gcc.dg/builtin-return-1.c (g): New.

gcc/testsuite/gcc.dg/Wstrict-overflow-17.c

+/* { dg-do compile } */
+/* { dg-options "-fstrict-overflow -O2 -Wstrict-overflow" } */
+
+/* This erroneously gave an overflow warning.  */
+
+extern void bar (char);
+void
+foo (char *s)
+{
+  int len, i;
+
+  for (len = 1; len < 5000; ++len)
+    {
+      for (i = 0; i < len; ++i)
+	{
+	  if (s[i] != '\0')
+	    bar (s[i]);
+	}
+    }
+}

gcc/tree-vrp.c

@@ -4676,8 +4676,8 @@ compare_name_with_value (enum tree_code comp, tree var, tree val,
   equiv_vr = get_vr_for_comparison (SSA_NAME_VERSION (var));
   sop = false;
   retval = compare_range_with_value (comp, &equiv_vr, val, &sop);
-  if (sop)
-    used_strict_overflow = 1;
+  if (retval)
+    used_strict_overflow = sop ? 1 : 0;
 
   /* If the equiv set is empty we have done all work we need to do.  */
   if (e == NULL)