This is the mail archive of the
gcc-bugs@gcc.gnu.org
mailing list for the GCC project.
[Bug tree-optimization/53501] [4.5/4.6/4.7/4.8 Regression] scev introduces signed overflow
- From: "rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Wed, 30 May 2012 10:34:50 +0000
- Subject: [Bug tree-optimization/53501] [4.5/4.6/4.7/4.8 Regression] scev introduces signed overflow
- Auto-submitted: auto-generated
- References: <bug-53501-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53501
--- Comment #3 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-05-30 10:34:50 UTC ---
It's my very best friend extract_muldiv that transforms
(int)((unsigned int) n.0_26 + 4294967295) * 2
to (int)(((unsigned int) n.0_26 + 2147483647) * 2)
It is the folding of (int) (((unsigned int) n.0_26 + 2147483647) * 2) + 2
which is wrong and done by fold_plusminus_mult_expr. Patch:
Index: gcc/fold-const.c
===================================================================
--- gcc/fold-const.c (revision 188004)
+++ gcc/fold-const.c (working copy)
@@ -10045,12 +10045,12 @@ fold_binary_loc (location_t loc,
/* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the
same or one. Make sure type is not saturating.
fold_plusminus_mult_expr will re-associate. */
- if ((TREE_CODE (arg0) == MULT_EXPR
- || TREE_CODE (arg1) == MULT_EXPR)
+ if ((TREE_CODE (op0) == MULT_EXPR
+ || TREE_CODE (op1) == MULT_EXPR)
&& !TYPE_SATURATING (type)
&& (!FLOAT_TYPE_P (type) || flag_associative_math))
{
- tree tem = fold_plusminus_mult_expr (loc, code, type, arg0, arg1);
+ tree tem = fold_plusminus_mult_expr (loc, code, type, op0, op1);
if (tem)
return tem;
}
that will leave the expression unsimplified.