The following guards X * CST CMP 0 similar to how we guarded other
compare patterns.
Yuri confirmed this solves the performance regression observed.
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied.
2016-01-26 Richard Biener <rguent...@suse.de>
PR middle-end/69467
* match.pd: Guard X * CST CMP 0 pattern with single_use.
Index: gcc/match.pd
===================================================================
--- gcc/match.pd (revision 232792)
+++ gcc/match.pd (working copy)
@@ -1821,12 +1821,13 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
(for cmp (simple_comparison)
scmp (swapped_simple_comparison)
(simplify
- (cmp (mult @0 INTEGER_CST@1) integer_zerop@2)
+ (cmp (mult@3 @0 INTEGER_CST@1) integer_zerop@2)
/* Handle unfolded multiplication by zero. */
(if (integer_zerop (@1))
(cmp @1 @2)
(if (ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0))
- && TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (@0)))
+ && TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (@0))
+ && single_use (@3))
/* If @1 is negative we swap the sense of the comparison. */
(if (tree_int_cst_sgn (@1) < 0)
(scmp @0 @2)
