From: Richard Guenther <rguenther@suse.de>
Date: Tue, 8 Apr 2008 22:07:20 +0000 (+0000)
Subject: re PR tree-optimization/35833 (Wrong code generated with -ftree-vrp)
X-Git-Tag: prereleases/gcc-4.2.4-rc1~42
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=97f33ffd0a6e743d6b4bb2a656cc66d1a0a1fa71;p=thirdparty%2Fgcc.git

re PR tree-optimization/35833 (Wrong code generated with -ftree-vrp)

2008-04-05  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/35833
	* tree-vrp.c (operand_less_p): Deal with non-INTEGER_CST
	results from fold_binary_to_constant.
	(compare_values_warnv): Likewise.

	* gcc.dg/torture/pr35833.c: New testcase.

From-SVN: r134111
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 9fdf703d4f7f..36e7853b765b 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2008-04-08  Richard Guenther  <rguenther@suse.de>
+
+	* fold-const.c (fold_widened_comparison): Do not allow
+	sign-changes that change the result.
+
 2008-04-03  Bob Wilson  <bob.wilson@acm.org>
 
 	* config/xtensa/xtensa.c (xtensa_secondary_reload_class): Use a
diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 23523debf41f..dde8f88720a0 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -6663,7 +6663,11 @@ fold_widened_comparison (enum tree_code code, tree type, tree arg0, tree arg1)
        || TYPE_UNSIGNED (TREE_TYPE (arg0)) == TYPE_UNSIGNED (shorter_type))
       && (TREE_TYPE (arg1_unw) == shorter_type
 	  || (TYPE_PRECISION (shorter_type)
-	      >= TYPE_PRECISION (TREE_TYPE (arg1_unw)))
+	      > TYPE_PRECISION (TREE_TYPE (arg1_unw)))
+	  || ((TYPE_PRECISION (shorter_type)
+	       == TYPE_PRECISION (TREE_TYPE (arg1_unw)))
+	      && (TYPE_UNSIGNED (shorter_type)
+		  == TYPE_UNSIGNED (TREE_TYPE (arg1_unw))))
 	  || (TREE_CODE (arg1_unw) == INTEGER_CST
 	      && (TREE_CODE (shorter_type) == INTEGER_TYPE
 		  || TREE_CODE (shorter_type) == BOOLEAN_TYPE)
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 8c8f5840357b..ad991a5b532d 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2008-04-08  Richard Guenther  <rguenther@suse.de>
+
+	* gcc.c-torture/execute/20080408-1.c: New testcase.
+
 2008-04-01  Laurent GUERBY  <laurent@guerby.net>
 
 	* ada/acats/norun.lst: Add c9a011b.
diff --git a/gcc/testsuite/gcc.c-torture/execute/20080408-1.c b/gcc/testsuite/gcc.c-torture/execute/20080408-1.c
new file mode 100644
index 000000000000..9e1ff6395174
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/20080408-1.c
@@ -0,0 +1,11 @@
+extern void abort (void);
+int main ()
+{
+  short ssi = 126;
+  unsigned short usi = 65280;
+  int fail = !(ssi < usi);
+  if (fail)
+    abort ();
+  return 0;
+}
+