From f3c83ed46cdc2062c30551f457ac53ad635794ea Mon Sep 17 00:00:00 2001 From: protonspring Date: Mon, 23 Dec 2019 10:58:30 -0700 Subject: [PATCH] Determine opposite colors mathematically This is a non-functional speed-up: master has to access SquareBB twice while this patch determines opposite_colors just using the values of the squares. It doesn't seem to change the overall speed of bench, but calling opposite_colors(...) 10 Million times: master: 39.4 seconds patch: 11.4 seconds. The only data point I have (other than my own tests), is a quite old failed STC test: LLR: -2.93 (-2.94,2.94) [-1.50,4.50] Total: 24308 W: 5331 L: 5330 D: 13647 Ptnml(0-2): 315, 2577, 6326, 2623, 289 http://tests.stockfishchess.org/tests/view/5e010256c13ac2425c4a9a67 Closes https://github.com/official-stockfish/Stockfish/pull/2498 No functional change --- src/bitboard.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/src/bitboard.h b/src/bitboard.h index 440de1ea..d11b7e73 100644 --- a/src/bitboard.h +++ b/src/bitboard.h @@ -129,8 +129,8 @@ constexpr bool more_than_one(Bitboard b) { return b & (b - 1); } -inline bool opposite_colors(Square s1, Square s2) { - return bool(DarkSquares & s1) != bool(DarkSquares & s2); +constexpr bool opposite_colors(Square s1, Square s2) { + return (s1 + rank_of(s1) + s2 + rank_of(s2)) & 1; } -- 2.30.2