From 8769f7e720219457d7e708d04981231c0d4501f5 Mon Sep 17 00:00:00 2001 From: Eugene Rozenfeld Date: Wed, 11 Nov 2020 17:24:48 -0800 Subject: [PATCH] Optimize two patterns with three xors. Simplify (a ^ b) & ((b ^ c) ^ a) to (a ^ b) & ~c. Simplify (a ^ b) | ((b ^ c) ^ a) to (a ^ b) | c. This fixes PR96671. gcc/ * match.pd (three xor patterns): New patterns. --- gcc/match.pd | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/gcc/match.pd b/gcc/match.pd index 349eab61d6b..1dd05c4c2a3 100644 --- a/gcc/match.pd +++ b/gcc/match.pd @@ -901,6 +901,16 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) (bit_not (bit_ior:cs (bit_not @0) @1)) (bit_and @0 (bit_not @1))) +/* (a ^ b) & ((b ^ c) ^ a) --> (a ^ b) & ~c */ +(simplify + (bit_and:c (bit_xor:c@3 @0 @1) (bit_xor:cs (bit_xor:cs @1 @2) @0)) + (bit_and @3 (bit_not @2))) + +/* (a ^ b) | ((b ^ c) ^ a) --> (a ^ b) | c */ +(simplify + (bit_ior:c (bit_xor:c@3 @0 @1) (bit_xor:c (bit_xor:c @1 @2) @0)) + (bit_ior @3 @2)) + /* Simplify (~X & Y) to X ^ Y if we know that (X & ~Y) is 0. */ #if GIMPLE (simplify -- 2.17.1