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[PATCH] Fix fold_widened_comparison (PR middle-end/37103)
- From: Jakub Jelinek <jakub at redhat dot com>
- To: gcc-patches at gcc dot gnu dot org
- Date: Thu, 14 Aug 2008 05:17:58 -0400
- Subject: [PATCH] Fix fold_widened_comparison (PR middle-end/37103)
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
Hi!
As the following testcase shows, if signedness of shorter_type and
arg1_unw's type differ, narrowing comparison can be wrong no matter
whether shorter_type is wider than arg1_unw's type or if it is
the same precision.
http://gcc.gnu.org/ml/gcc-patches/2008-04/msg00720.html
changed just the case where the precision is the same, this
patch fixes also the case where shorter_type is wider than arg1_unw.
Approved by richi in bugzilla, bootstrapped/regtested on x86_64-linux,
committed to trunk/4.3.
2008-08-14 Jakub Jelinek <jakub@redhat.com>
PR middle-end/37103
* fold-const.c (fold_widened_comparison): Do not allow
sign changes that change the result even if shorter type
is wider than arg1_unw's type.
* gcc.c-torture/execute/20080813-1.c: New test.
--- gcc/fold-const.c.jj 2008-08-13 19:46:11.000000000 +0200
+++ gcc/fold-const.c 2008-08-13 20:18:21.000000000 +0200
@@ -6733,10 +6733,8 @@ fold_widened_comparison (enum tree_code
if ((code == EQ_EXPR || code == NE_EXPR
|| 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 (shorter_type)
- == TYPE_PRECISION (TREE_TYPE (arg1_unw)))
+ >= TYPE_PRECISION (TREE_TYPE (arg1_unw)))
&& (TYPE_UNSIGNED (shorter_type)
== TYPE_UNSIGNED (TREE_TYPE (arg1_unw))))
|| (TREE_CODE (arg1_unw) == INTEGER_CST
--- gcc/testsuite/gcc.c-torture/execute/20080813-1.c.jj 2008-08-13 20:22:56.000000000 +0200
+++ gcc/testsuite/gcc.c-torture/execute/20080813-1.c 2008-08-13 20:22:10.000000000 +0200
@@ -0,0 +1,30 @@
+/* PR middle-end/37103 */
+
+extern void abort (void);
+
+void
+foo (unsigned short x)
+{
+ signed char y = -1;
+ if (x == y)
+ abort ();
+}
+
+void
+bar (unsigned short x)
+{
+ unsigned char y = -1;
+ if (x == y)
+ abort ();
+}
+
+int
+main (void)
+{
+ if (sizeof (int) == sizeof (short))
+ return 0;
+ foo (-1);
+ if (sizeof (short) > 1)
+ bar (-1);
+ return 0;
+}
Jakub