------- Comment #4 from jakub at gcc dot gnu dot org 2008-08-13 18:30 -------
Verified the regression was introduced by PR35163 fix.
http://gcc.gnu.org/ml/gcc-patches/2008-04/msg00720.html
should have been IMNSHO applied for shorter_type bigger or equal than
arg1_unw's type, not just when they are equal. If shorter_type is bigger and
the signs are different, then the bits above shorter_type bits might be all 1's
in one case and all 0's in the second case.
Patch I'll be regtesting:
2008-08-13 Jakub Jelinek <[EMAIL PROTECTED]>
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.jj2008-08-13 19:46:11.000000000 +0200
+++ gcc/fold-const.c2008-08-13 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.jj2008-08-13
20:22:56.000000000 +0200
+++ gcc/testsuite/gcc.c-torture/execute/20080813-1.c2008-08-13
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 at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
AssignedTo|unassigned at gcc dot gnu |jakub at gcc dot gnu dot org
|dot org |
Status|NEW |ASSIGNED
Last reconfirmed|2008-08-13 09:16:17 |2008-08-13 18:30:25
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37103
