X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fposition.cpp;h=0d7d957141f31738c70ccbaf95c950b38e5c5693;hb=fe53a18f7a149f7e6d1a9dde8a7478692ef82997;hp=ae1da017770cd34ea79eabfc961a27359eb0ad61;hpb=385deefd807b512a1c404f5cc4c2045f265a800d;p=stockfish diff --git a/src/position.cpp b/src/position.cpp index ae1da017..0d7d9571 100644 --- a/src/position.cpp +++ b/src/position.cpp @@ -1,6 +1,6 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 - Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file) + Copyright (C) 2004-2023 The Stockfish developers (see AUTHORS file) Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -16,21 +16,29 @@ along with this program. If not, see . */ +#include "position.h" + #include +#include #include -#include // For offsetof() -#include // For std::memset, std::memcmp +#include +#include +#include +#include #include +#include #include +#include +#include #include "bitboard.h" #include "misc.h" #include "movegen.h" -#include "position.h" +#include "nnue/nnue_common.h" +#include "syzygy/tbprobe.h" #include "thread.h" #include "tt.h" #include "uci.h" -#include "syzygy/tbprobe.h" using std::string; @@ -41,12 +49,12 @@ namespace Zobrist { Key psq[PIECE_NB][SQUARE_NB]; Key enpassant[FILE_NB]; Key castling[CASTLING_RIGHT_NB]; - Key side, noPawns; + Key side; } namespace { -const string PieceToChar(" PNBRQK pnbrqk"); +constexpr std::string_view PieceToChar(" PNBRQK pnbrqk"); constexpr Piece Pieces[] = { W_PAWN, W_KNIGHT, W_BISHOP, W_ROOK, W_QUEEN, W_KING, B_PAWN, B_KNIGHT, B_BISHOP, B_ROOK, B_QUEEN, B_KING }; @@ -94,9 +102,10 @@ std::ostream& operator<<(std::ostream& os, const Position& pos) { } -// Marcel van Kervinck's cuckoo algorithm for fast detection of "upcoming repetition" -// situations. Description of the algorithm in the following paper: -// https://marcelk.net/2013-04-06/paper/upcoming-rep-v2.pdf +// Implements Marcel van Kervinck's cuckoo algorithm to detect repetition of positions +// for 3-fold repetition draws. The algorithm uses two hash tables with Zobrist hashes +// to allow fast detection of recurring positions. For details see: +// http://web.archive.org/web/20201107002606/https://marcelk.net/2013-04-06/paper/upcoming-rep-v2.pdf // First and second hash functions for indexing the cuckoo tables inline int H1(Key h) { return h & 0x1fff; } @@ -124,12 +133,11 @@ void Position::init() { Zobrist::castling[cr] = rng.rand(); Zobrist::side = rng.rand(); - Zobrist::noPawns = rng.rand(); // Prepare the cuckoo tables std::memset(cuckoo, 0, sizeof(cuckoo)); std::memset(cuckooMove, 0, sizeof(cuckooMove)); - int count = 0; + [[maybe_unused]] int count = 0; for (Piece pc : Pieces) for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1) for (Square s2 = Square(s1 + 1); s2 <= SQ_H8; ++s2) @@ -180,9 +188,9 @@ Position& Position::set(const string& fenStr, bool isChess960, StateInfo* si, Th 4) En passant target square (in algebraic notation). If there's no en passant target square, this is "-". If a pawn has just made a 2-square move, this - is the position "behind" the pawn. Following X-FEN standard, this is recorded only - if there is a pawn in position to make an en passant capture, and if there really - is a pawn that might have advanced two squares. + is the position "behind" the pawn. Following X-FEN standard, this is recorded + only if there is a pawn in position to make an en passant capture, and if + there really is a pawn that might have advanced two squares. 5) Halfmove clock. This is the number of halfmoves since the last pawn advance or capture. This is used to determine if a draw can be claimed under the @@ -281,7 +289,7 @@ Position& Position::set(const string& fenStr, bool isChess960, StateInfo* si, Th chess960 = isChess960; thisThread = th; - set_state(st); + set_state(); assert(pos_is_ok()); @@ -312,60 +320,55 @@ void Position::set_castling_right(Color c, Square rfrom) { /// Position::set_check_info() sets king attacks to detect if a move gives check -void Position::set_check_info(StateInfo* si) const { +void Position::set_check_info() const { - si->blockersForKing[WHITE] = slider_blockers(pieces(BLACK), square(WHITE), si->pinners[BLACK]); - si->blockersForKing[BLACK] = slider_blockers(pieces(WHITE), square(BLACK), si->pinners[WHITE]); + update_slider_blockers(WHITE); + update_slider_blockers(BLACK); Square ksq = square(~sideToMove); - si->checkSquares[PAWN] = pawn_attacks_bb(~sideToMove, ksq); - si->checkSquares[KNIGHT] = attacks_bb(ksq); - si->checkSquares[BISHOP] = attacks_bb(ksq, pieces()); - si->checkSquares[ROOK] = attacks_bb(ksq, pieces()); - si->checkSquares[QUEEN] = si->checkSquares[BISHOP] | si->checkSquares[ROOK]; - si->checkSquares[KING] = 0; + st->checkSquares[PAWN] = pawn_attacks_bb(~sideToMove, ksq); + st->checkSquares[KNIGHT] = attacks_bb(ksq); + st->checkSquares[BISHOP] = attacks_bb(ksq, pieces()); + st->checkSquares[ROOK] = attacks_bb(ksq, pieces()); + st->checkSquares[QUEEN] = st->checkSquares[BISHOP] | st->checkSquares[ROOK]; + st->checkSquares[KING] = 0; } /// Position::set_state() computes the hash keys of the position, and other /// data that once computed is updated incrementally as moves are made. -/// The function is only used when a new position is set up, and to verify -/// the correctness of the StateInfo data when running in debug mode. +/// The function is only used when a new position is set up -void Position::set_state(StateInfo* si) const { +void Position::set_state() const { - si->key = si->materialKey = 0; - si->pawnKey = Zobrist::noPawns; - si->nonPawnMaterial[WHITE] = si->nonPawnMaterial[BLACK] = VALUE_ZERO; - si->checkersBB = attackers_to(square(sideToMove)) & pieces(~sideToMove); + st->key = st->materialKey = 0; + st->nonPawnMaterial[WHITE] = st->nonPawnMaterial[BLACK] = VALUE_ZERO; + st->checkersBB = attackers_to(square(sideToMove)) & pieces(~sideToMove); - set_check_info(si); + set_check_info(); for (Bitboard b = pieces(); b; ) { Square s = pop_lsb(b); Piece pc = piece_on(s); - si->key ^= Zobrist::psq[pc][s]; + st->key ^= Zobrist::psq[pc][s]; - if (type_of(pc) == PAWN) - si->pawnKey ^= Zobrist::psq[pc][s]; - - else if (type_of(pc) != KING) - si->nonPawnMaterial[color_of(pc)] += PieceValue[MG][pc]; + if (type_of(pc) != KING && type_of(pc) != PAWN) + st->nonPawnMaterial[color_of(pc)] += PieceValue[pc]; } - if (si->epSquare != SQ_NONE) - si->key ^= Zobrist::enpassant[file_of(si->epSquare)]; + if (st->epSquare != SQ_NONE) + st->key ^= Zobrist::enpassant[file_of(st->epSquare)]; if (sideToMove == BLACK) - si->key ^= Zobrist::side; + st->key ^= Zobrist::side; - si->key ^= Zobrist::castling[si->castlingRights]; + st->key ^= Zobrist::castling[st->castlingRights]; for (Piece pc : Pieces) for (int cnt = 0; cnt < pieceCount[pc]; ++cnt) - si->materialKey ^= Zobrist::psq[pc][cnt]; + st->materialKey ^= Zobrist::psq[pc][cnt]; } @@ -441,37 +444,33 @@ 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; } @@ -551,7 +550,7 @@ bool Position::legal(Move m) const { /// Position::pseudo_legal() takes a random move and tests whether the move is -/// pseudo legal. It is used to validate moves from TT that can be corrupted +/// pseudo-legal. It is used to validate moves from TT that can be corrupted /// due to SMP concurrent access or hash position key aliasing. bool Position::pseudo_legal(const Move m) const { @@ -567,9 +566,8 @@ bool Position::pseudo_legal(const Move m) const { return checkers() ? MoveList< EVASIONS>(*this).contains(m) : MoveList(*this).contains(m); - // Is not a promotion, so promotion piece must be empty - if (promotion_type(m) - KNIGHT != NO_PIECE_TYPE) - return false; + // Is not a promotion, so the promotion piece must be empty + assert(promotion_type(m) - KNIGHT == NO_PIECE_TYPE); // If the 'from' square is not occupied by a piece belonging to the side to // move, the move is obviously not legal. @@ -589,8 +587,8 @@ bool Position::pseudo_legal(const Move m) const { return false; if ( !(pawn_attacks_bb(us, from) & pieces(~us) & to) // Not a capture - && !((from + pawn_push(us) == to) && empty(to)) // Not a single push - && !( (from + 2 * pawn_push(us) == to) // Not a double push + && !((from + pawn_push(us) == to) && empty(to)) // Not a single push + && !( (from + 2 * pawn_push(us) == to) // Not a double push && (relative_rank(us, from) == RANK_2) && empty(to) && empty(to - pawn_push(us)))) @@ -606,7 +604,7 @@ bool Position::pseudo_legal(const Move m) const { { if (type_of(pc) != KING) { - // Double check? In this case a king move is required + // Double check? In this case, a king move is required if (more_than_one(checkers())) return false; @@ -614,7 +612,7 @@ bool Position::pseudo_legal(const Move m) const { if (!(between_bb(square(us), lsb(checkers())) & to)) return false; } - // In case of king moves under check we have to remove king so as to catch + // In case of king moves under check we have to remove the king so as to catch // invalid moves like b1a1 when opposite queen is on c1. else if (attackers_to(to, pieces() ^ from) & pieces(~us)) return false; @@ -639,9 +637,9 @@ bool Position::gives_check(Move m) const { return true; // Is there a discovered check? - if ( (blockers_for_king(~sideToMove) & from) - && !aligned(from, to, square(~sideToMove))) - return true; + if (blockers_for_king(~sideToMove) & from) + return !aligned(from, to, square(~sideToMove)) + || type_of(m) == CASTLING; switch (type_of(m)) { @@ -666,11 +664,9 @@ bool Position::gives_check(Move m) const { default: //CASTLING { // Castling is encoded as 'king captures the rook' - Square ksq = square(~sideToMove); Square rto = relative_square(sideToMove, to > from ? SQ_F1 : SQ_D1); - return (attacks_bb(rto) & ksq) - && (attacks_bb(rto, pieces() ^ from ^ to) & ksq); + return check_squares(ROOK) & rto; } } } @@ -748,30 +744,21 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { assert(piece_on(to) == NO_PIECE); assert(piece_on(capsq) == make_piece(them, PAWN)); } - - st->pawnKey ^= Zobrist::psq[captured][capsq]; } else - st->nonPawnMaterial[them] -= PieceValue[MG][captured]; + st->nonPawnMaterial[them] -= PieceValue[captured]; - if (Eval::useNNUE) - { - dp.dirty_num = 2; // 1 piece moved, 1 piece captured - dp.piece[1] = captured; - dp.from[1] = capsq; - dp.to[1] = SQ_NONE; - } + dp.dirty_num = 2; // 1 piece moved, 1 piece captured + dp.piece[1] = captured; + dp.from[1] = capsq; + dp.to[1] = SQ_NONE; // Update board and piece lists remove_piece(capsq); - if (type_of(m) == EN_PASSANT) - board[capsq] = NO_PIECE; - // Update material hash key and prefetch access to materialTable k ^= Zobrist::psq[captured][capsq]; st->materialKey ^= Zobrist::psq[captured][pieceCount[captured]]; - prefetch(thisThread->materialTable[st->materialKey]); // Reset rule 50 counter st->rule50 = 0; @@ -798,12 +785,9 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { // Move the piece. The tricky Chess960 castling is handled earlier if (type_of(m) != CASTLING) { - if (Eval::useNNUE) - { - dp.piece[0] = pc; - dp.from[0] = from; - dp.to[0] = to; - } + dp.piece[0] = pc; + dp.from[0] = from; + dp.to[0] = to; move_piece(from, to); } @@ -829,29 +813,22 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { remove_piece(to); put_piece(promotion, to); - if (Eval::useNNUE) - { - // Promoting pawn to SQ_NONE, promoted piece from SQ_NONE - dp.to[0] = SQ_NONE; - dp.piece[dp.dirty_num] = promotion; - dp.from[dp.dirty_num] = SQ_NONE; - dp.to[dp.dirty_num] = to; - dp.dirty_num++; - } + // Promoting pawn to SQ_NONE, promoted piece from SQ_NONE + dp.to[0] = SQ_NONE; + dp.piece[dp.dirty_num] = promotion; + dp.from[dp.dirty_num] = SQ_NONE; + dp.to[dp.dirty_num] = to; + dp.dirty_num++; // Update hash keys k ^= Zobrist::psq[pc][to] ^ Zobrist::psq[promotion][to]; - st->pawnKey ^= Zobrist::psq[pc][to]; st->materialKey ^= Zobrist::psq[promotion][pieceCount[promotion]-1] ^ Zobrist::psq[pc][pieceCount[pc]]; // Update material - st->nonPawnMaterial[us] += PieceValue[MG][promotion]; + st->nonPawnMaterial[us] += PieceValue[promotion]; } - // Update pawn hash key - st->pawnKey ^= Zobrist::psq[pc][from] ^ Zobrist::psq[pc][to]; - // Reset rule 50 draw counter st->rule50 = 0; } @@ -868,7 +845,7 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { sideToMove = ~sideToMove; // Update king attacks used for fast check detection - set_check_info(st); + set_check_info(); // Calculate the repetition info. It is the ply distance from the previous // occurrence of the same position, negative in the 3-fold case, or zero @@ -967,7 +944,7 @@ void Position::do_castling(Color us, Square from, Square& to, Square& rfrom, Squ rto = relative_square(us, kingSide ? SQ_F1 : SQ_D1); to = relative_square(us, kingSide ? SQ_G1 : SQ_C1); - if (Do && Eval::useNNUE) + if (Do) { auto& dp = st->dirtyPiece; dp.piece[0] = make_piece(us, KING); @@ -982,7 +959,7 @@ void Position::do_castling(Color us, Square from, Square& to, Square& rfrom, Squ // Remove both pieces first since squares could overlap in Chess960 remove_piece(Do ? from : to); remove_piece(Do ? rfrom : rto); - board[Do ? from : to] = board[Do ? rfrom : rto] = NO_PIECE; // Since remove_piece doesn't do this for us + board[Do ? from : to] = board[Do ? rfrom : rto] = NO_PIECE; // remove_piece does not do this for us put_piece(make_piece(us, KING), Do ? to : from); put_piece(make_piece(us, ROOK), Do ? rto : rfrom); } @@ -1020,7 +997,7 @@ void Position::do_null_move(StateInfo& newSt) { sideToMove = ~sideToMove; - set_check_info(st); + set_check_info(); st->repetition = 0; @@ -1054,7 +1031,10 @@ Key Position::key_after(Move m) const { if (captured) k ^= Zobrist::psq[captured][to]; - return k ^ Zobrist::psq[pc][to] ^ Zobrist::psq[pc][from]; + k ^= Zobrist::psq[pc][to] ^ Zobrist::psq[pc][from]; + + return (captured || type_of(pc) == PAWN) + ? k : adjust_key50(k); } @@ -1072,16 +1052,16 @@ bool Position::see_ge(Move m, Value threshold) const { Square from = from_sq(m), to = to_sq(m); - int swap = PieceValue[MG][piece_on(to)] - threshold; + int swap = PieceValue[piece_on(to)] - threshold; if (swap < 0) return false; - swap = PieceValue[MG][piece_on(from)] - swap; + swap = PieceValue[piece_on(from)] - swap; if (swap <= 0) return true; assert(color_of(piece_on(from)) == sideToMove); - Bitboard occupied = pieces() ^ from ^ to; + Bitboard occupied = pieces() ^ from ^ to; // xoring to is important for pinned piece logic Color stm = sideToMove; Bitboard attackers = attackers_to(to, occupied); Bitboard stmAttackers, bb; @@ -1099,10 +1079,12 @@ bool Position::see_ge(Move m, Value threshold) const { // Don't allow pinned pieces to attack as long as there are // pinners on their original square. if (pinners(~stm) & occupied) + { stmAttackers &= ~blockers_for_king(stm); - if (!stmAttackers) - break; + if (!stmAttackers) + break; + } res ^= 1; @@ -1110,51 +1092,50 @@ bool Position::see_ge(Move m, Value threshold) const { // the bitboard 'attackers' any X-ray attackers behind it. if ((bb = stmAttackers & pieces(PAWN))) { - if ((swap = PawnValueMg - swap) < res) + if ((swap = PawnValue - swap) < res) break; - occupied ^= least_significant_square_bb(bb); + attackers |= attacks_bb(to, occupied) & pieces(BISHOP, QUEEN); } else if ((bb = stmAttackers & pieces(KNIGHT))) { - if ((swap = KnightValueMg - swap) < res) + if ((swap = KnightValue - swap) < res) break; - occupied ^= least_significant_square_bb(bb); } else if ((bb = stmAttackers & pieces(BISHOP))) { - if ((swap = BishopValueMg - swap) < res) + if ((swap = BishopValue - swap) < res) break; - occupied ^= least_significant_square_bb(bb); + attackers |= attacks_bb(to, occupied) & pieces(BISHOP, QUEEN); } else if ((bb = stmAttackers & pieces(ROOK))) { - if ((swap = RookValueMg - swap) < res) + if ((swap = RookValue - swap) < res) break; - occupied ^= least_significant_square_bb(bb); + attackers |= attacks_bb(to, occupied) & pieces(ROOK, QUEEN); } else if ((bb = stmAttackers & pieces(QUEEN))) { - if ((swap = QueenValueMg - swap) < res) + if ((swap = QueenValue - swap) < res) break; - occupied ^= least_significant_square_bb(bb); + attackers |= (attacks_bb(to, occupied) & pieces(BISHOP, QUEEN)) | (attacks_bb(to, occupied) & pieces(ROOK , QUEEN)); } else // KING - // If we "capture" with the king but opponent still has attackers, + // If we "capture" with the king but the opponent still has attackers, // reverse the result. return (attackers & ~pieces(stm)) ? res ^ 1 : res; } @@ -1162,7 +1143,6 @@ bool Position::see_ge(Move m, Value threshold) const { return bool(res); } - /// Position::is_draw() tests whether the position is drawn by 50-move rule /// or by repetition. It does not detect stalemates. @@ -1280,7 +1260,7 @@ void Position::flip() { /// Position::pos_is_ok() performs some consistency checks for the -/// position object and raises an asserts if something wrong is detected. +/// position object and raise an assert if something wrong is detected. /// This is meant to be helpful when debugging. bool Position::pos_is_ok() const { @@ -1318,12 +1298,6 @@ bool Position::pos_is_ok() const { if (p1 != p2 && (pieces(p1) & pieces(p2))) assert(0 && "pos_is_ok: Bitboards"); - StateInfo si = *st; - ASSERT_ALIGNED(&si, Eval::NNUE::CacheLineSize); - - set_state(&si); - if (std::memcmp(&si, st, sizeof(StateInfo))) - assert(0 && "pos_is_ok: State"); for (Piece pc : Pieces) if ( pieceCount[pc] != popcount(pieces(color_of(pc), type_of(pc)))