Hello,
before we completely forget about it, this fixes the pattern as discussed
around https://gcc.gnu.org/ml/gcc-patches/2015-10/msg01459.html .
Note that, as seen in
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68008#c1 , we would sometimes
like to allow a conversion between trunc_div and mult, but that's a
separate generalization and I did not want to think of the proper
conditions for its validity.
Bootstrap+regtest on ppc64le-redhat-linux.
2015-10-30 Marc Glisse <marc.gli...@inria.fr>
* match.pd (X-(X/Y)*Y): Properly handle conversions and commutativity.
--
Marc GlisseIndex: gcc/match.pd
===================================================================
--- gcc/match.pd (revision 229478)
+++ gcc/match.pd (working copy)
@@ -311,24 +311,24 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
/* X % -Y is the same as X % Y. */
(simplify
(trunc_mod @0 (convert? (negate @1)))
(if (!TYPE_UNSIGNED (type)
&& !TYPE_OVERFLOW_TRAPS (type)
&& tree_nop_conversion_p (type, TREE_TYPE (@1)))
(trunc_mod @0 (convert @1))))
/* X - (X / Y) * Y is the same as X % Y. */
(simplify
- (minus (convert1? @0) (convert2? (mult (trunc_div @0 @1) @1)))
- (if ((INTEGRAL_TYPE_P (type) || VECTOR_INTEGER_TYPE_P (type))
- && TYPE_UNSIGNED (TREE_TYPE (@0)) == TYPE_UNSIGNED (type))
- (trunc_mod (convert @0) (convert @1))))
+ (minus (convert1? @2) (convert2? (mult:c (trunc_div @0 @1) @1)))
+ (if (operand_equal_p (@0, @2, 0)
+ && (INTEGRAL_TYPE_P (type) || VECTOR_INTEGER_TYPE_P (type)))
+ (convert (trunc_mod @0 @1))))
/* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
i.e. "X % C" into "X & (C - 1)", if X and C are positive.
Also optimize A % (C << N) where C is a power of 2,
to A & ((C << N) - 1). */
(match (power_of_two_cand @1)
INTEGER_CST@1)
(match (power_of_two_cand @1)
(lshift INTEGER_CST@1 @2))
(for mod (trunc_mod floor_mod)
