From: pb00067 Date: Thu, 17 Aug 2023 12:31:05 +0000 (+0200) Subject: Simplify slider_blocker calculation X-Git-Url: https://git.sesse.net/?a=commitdiff_plain;h=1f7ff8406d323e634a2aa1e1264042340707cdd9;hp=4f7fe255c7ac9cf705350cabfc231d87a3e75018;p=stockfish Simplify slider_blocker calculation Now that classical evaluation was removed, we can adapt this method to the needs of set_check_info. STC: 2.95 (-2.94,2.94) <-1.75,0.25> Total: 298176 W: 75802 L: 75868 D: 146506 Ptnml(0-2): 908, 33608, 80192, 33402, 978 https://tests.stockfishchess.org/tests/view/64e70b899009777747557b43 closes https://github.com/official-stockfish/Stockfish/pull/4753 no functional change --- diff --git a/src/position.cpp b/src/position.cpp index 0f15727d..12067743 100644 --- a/src/position.cpp +++ b/src/position.cpp @@ -321,8 +321,8 @@ void Position::set_castling_right(Color c, Square rfrom) { void Position::set_check_info() const { - st->blockersForKing[WHITE] = slider_blockers(pieces(BLACK), square(WHITE), st->pinners[BLACK]); - st->blockersForKing[BLACK] = slider_blockers(pieces(WHITE), square(BLACK), st->pinners[WHITE]); + update_slider_blockers(WHITE); + update_slider_blockers(BLACK); Square ksq = square(~sideToMove); @@ -443,37 +443,33 @@ string Position::fen() const { return ss.str(); } +/// update_slider_blockers() calculates st->blockersForKing[c] and st->pinners[~c], +/// which store respectively the pieces preventing king of color c from being in check +/// and the slider pieces of color ~c pinning pieces of color c to the king. +void Position::update_slider_blockers(Color c) const { -/// Position::slider_blockers() returns a bitboard of all the pieces (both colors) -/// that are blocking attacks on the square 's' from 'sliders'. A piece blocks a -/// slider if removing that piece from the board would result in a position where -/// square 's' is attacked. For example, a king-attack blocking piece can be either -/// a pinned or a discovered check piece, according if its color is the opposite -/// or the same of the color of the slider. + Square ksq = square(c); -Bitboard Position::slider_blockers(Bitboard sliders, Square s, Bitboard& pinners) const { - - Bitboard blockers = 0; - pinners = 0; + st->blockersForKing[c] = 0; + st->pinners[~c] = 0; // Snipers are sliders that attack 's' when a piece and other snipers are removed - Bitboard snipers = ( (attacks_bb< ROOK>(s) & pieces(QUEEN, ROOK)) - | (attacks_bb(s) & pieces(QUEEN, BISHOP))) & sliders; + Bitboard snipers = ( (attacks_bb< ROOK>(ksq) & pieces(QUEEN, ROOK)) + | (attacks_bb(ksq) & pieces(QUEEN, BISHOP))) & pieces(~c); Bitboard occupancy = pieces() ^ snipers; while (snipers) { Square sniperSq = pop_lsb(snipers); - Bitboard b = between_bb(s, sniperSq) & occupancy; + Bitboard b = between_bb(ksq, sniperSq) & occupancy; if (b && !more_than_one(b)) { - blockers |= b; - if (b & pieces(color_of(piece_on(s)))) - pinners |= sniperSq; + st->blockersForKing[c] |= b; + if (b & pieces(c)) + st->pinners[~c] |= sniperSq; } } - return blockers; } diff --git a/src/position.h b/src/position.h index f0546af3..ca7c3ace 100644 --- a/src/position.h +++ b/src/position.h @@ -114,7 +114,7 @@ public: // Attacks to/from a given square Bitboard attackers_to(Square s) const; Bitboard attackers_to(Square s, Bitboard occupied) const; - Bitboard slider_blockers(Bitboard sliders, Square s, Bitboard& pinners) const; + void update_slider_blockers(Color c) const; template Bitboard attacks_by(Color c) const; // Properties of moves