X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fposition.cpp;h=13010c1a43f49571193d745a144ad92a4867bb9d;hp=eeedbbb22d1fd8d332ed25deb83acdeb07dda9d3;hb=aa75388ec136a8cf83b09da2328c5fefd5a010bd;hpb=ca6c9f85a5c3a45a248716b8fe68821b20eee201 diff --git a/src/position.cpp b/src/position.cpp index eeedbbb2..13010c1a 100644 --- a/src/position.cpp +++ b/src/position.cpp @@ -1,8 +1,6 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 - Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad - Copyright (C) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad + Copyright (C) 2004-2020 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 @@ -20,7 +18,8 @@ #include #include -#include // For std::memset, std::memcmp +#include // For offsetof() +#include // For std::memset, std::memcmp #include #include @@ -31,6 +30,7 @@ #include "thread.h" #include "tt.h" #include "uci.h" +#include "syzygy/tbprobe.h" using std::string; @@ -39,42 +39,15 @@ namespace Zobrist { Key psq[PIECE_NB][SQUARE_NB]; Key enpassant[FILE_NB]; Key castling[CASTLING_RIGHT_NB]; - Key side; + Key side, noPawns; } namespace { const string PieceToChar(" PNBRQK pnbrqk"); -// min_attacker() is a helper function used by see() to locate the least -// valuable attacker for the side to move, remove the attacker we just found -// from the bitboards and scan for new X-ray attacks behind it. - -template -PieceType min_attacker(const Bitboard* bb, Square to, Bitboard stmAttackers, - Bitboard& occupied, Bitboard& attackers) { - - Bitboard b = stmAttackers & bb[Pt]; - if (!b) - return min_attacker(bb, to, stmAttackers, occupied, attackers); - - occupied ^= b & ~(b - 1); - - if (Pt == PAWN || Pt == BISHOP || Pt == QUEEN) - attackers |= attacks_bb(to, occupied) & (bb[BISHOP] | bb[QUEEN]); - - if (Pt == ROOK || Pt == QUEEN) - attackers |= attacks_bb(to, occupied) & (bb[ROOK] | bb[QUEEN]); - - attackers &= occupied; // After X-ray that may add already processed pieces - return (PieceType)Pt; -} - -template<> -PieceType min_attacker(const Bitboard*, Square, Bitboard, Bitboard&, Bitboard&) { - return KING; // No need to update bitboards: it is the last cycle -} - +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 }; } // namespace @@ -89,46 +62,91 @@ std::ostream& operator<<(std::ostream& os, const Position& pos) { for (File f = FILE_A; f <= FILE_H; ++f) os << " | " << PieceToChar[pos.piece_on(make_square(f, r))]; - os << " |\n +---+---+---+---+---+---+---+---+\n"; + os << " | " << (1 + r) << "\n +---+---+---+---+---+---+---+---+\n"; } - os << "\nFen: " << pos.fen() << "\nKey: " << std::hex << std::uppercase - << std::setfill('0') << std::setw(16) << pos.key() << std::dec << "\nCheckers: "; + os << " a b c d e f g h\n" + << "\nFen: " << pos.fen() << "\nKey: " << std::hex << std::uppercase + << std::setfill('0') << std::setw(16) << pos.key() + << std::setfill(' ') << std::dec << "\nCheckers: "; for (Bitboard b = pos.checkers(); b; ) os << UCI::square(pop_lsb(&b)) << " "; + if ( int(Tablebases::MaxCardinality) >= popcount(pos.pieces()) + && !pos.can_castle(ANY_CASTLING)) + { + StateInfo st; + ASSERT_ALIGNED(&st, Eval::NNUE::kCacheLineSize); + + Position p; + p.set(pos.fen(), pos.is_chess960(), &st, pos.this_thread()); + Tablebases::ProbeState s1, s2; + Tablebases::WDLScore wdl = Tablebases::probe_wdl(p, &s1); + int dtz = Tablebases::probe_dtz(p, &s2); + os << "\nTablebases WDL: " << std::setw(4) << wdl << " (" << s1 << ")" + << "\nTablebases DTZ: " << std::setw(4) << dtz << " (" << s2 << ")"; + } + return os; } -/// Position::init() initializes at startup the various arrays used to compute -/// hash keys. +// 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 + +// First and second hash functions for indexing the cuckoo tables +inline int H1(Key h) { return h & 0x1fff; } +inline int H2(Key h) { return (h >> 16) & 0x1fff; } + +// Cuckoo tables with Zobrist hashes of valid reversible moves, and the moves themselves +Key cuckoo[8192]; +Move cuckooMove[8192]; + + +/// Position::init() initializes at startup the various arrays used to compute hash keys void Position::init() { PRNG rng(1070372); - for (Color c = WHITE; c <= BLACK; ++c) - for (PieceType pt = PAWN; pt <= KING; ++pt) - for (Square s = SQ_A1; s <= SQ_H8; ++s) - Zobrist::psq[make_piece(c, pt)][s] = rng.rand(); + for (Piece pc : Pieces) + for (Square s = SQ_A1; s <= SQ_H8; ++s) + Zobrist::psq[pc][s] = rng.rand(); for (File f = FILE_A; f <= FILE_H; ++f) Zobrist::enpassant[f] = rng.rand(); for (int cr = NO_CASTLING; cr <= ANY_CASTLING; ++cr) - { - Zobrist::castling[cr] = 0; - Bitboard b = cr; - while (b) - { - Key k = Zobrist::castling[1ULL << pop_lsb(&b)]; - Zobrist::castling[cr] ^= k ? k : rng.rand(); - } - } + 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; + for (Piece pc : Pieces) + for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1) + for (Square s2 = Square(s1 + 1); s2 <= SQ_H8; ++s2) + if ((type_of(pc) != PAWN) && (attacks_bb(type_of(pc), s1, 0) & s2)) + { + Move move = make_move(s1, s2); + Key key = Zobrist::psq[pc][s1] ^ Zobrist::psq[pc][s2] ^ Zobrist::side; + int i = H1(key); + while (true) + { + std::swap(cuckoo[i], key); + std::swap(cuckooMove[i], move); + if (move == MOVE_NONE) // Arrived at empty slot? + break; + i = (i == H1(key)) ? H2(key) : H1(key); // Push victim to alternative slot + } + count++; + } + assert(count == 3668); } @@ -160,8 +178,9 @@ 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. This is recorded regardless of whether - there is a pawn in position to make an en passant capture. + 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 @@ -178,7 +197,6 @@ Position& Position::set(const string& fenStr, bool isChess960, StateInfo* si, Th std::memset(this, 0, sizeof(Position)); std::memset(si, 0, sizeof(StateInfo)); - std::fill_n(&pieceList[0][0], sizeof(pieceList) / sizeof(Square), SQ_NONE); st = si; ss >> std::noskipws; @@ -187,13 +205,12 @@ Position& Position::set(const string& fenStr, bool isChess960, StateInfo* si, Th while ((ss >> token) && !isspace(token)) { if (isdigit(token)) - sq += Square(token - '0'); // Advance the given number of files + sq += (token - '0') * EAST; // Advance the given number of files else if (token == '/') - sq -= Square(16); + sq += 2 * SOUTH; - else if ((idx = PieceToChar.find(token)) != string::npos) - { + else if ((idx = PieceToChar.find(token)) != string::npos) { put_piece(Piece(idx), sq); ++sq; } @@ -232,30 +249,39 @@ Position& Position::set(const string& fenStr, bool isChess960, StateInfo* si, Th set_castling_right(c, rsq); } - // 4. En passant square. Ignore if no pawn capture is possible + // 4. En passant square. + // Ignore if square is invalid or not on side to move relative rank 6. + bool enpassant = false; + if ( ((ss >> col) && (col >= 'a' && col <= 'h')) - && ((ss >> row) && (row == '3' || row == '6'))) + && ((ss >> row) && (row == (sideToMove == WHITE ? '6' : '3')))) { st->epSquare = make_square(File(col - 'a'), Rank(row - '1')); - if (!(attackers_to(st->epSquare) & pieces(sideToMove, PAWN))) - st->epSquare = SQ_NONE; + // En passant square will be considered only if + // a) side to move have a pawn threatening epSquare + // b) there is an enemy pawn in front of epSquare + // c) there is no piece on epSquare or behind epSquare + enpassant = pawn_attacks_bb(~sideToMove, st->epSquare) & pieces(sideToMove, PAWN) + && (pieces(~sideToMove, PAWN) & (st->epSquare + pawn_push(~sideToMove))) + && !(pieces() & (st->epSquare | (st->epSquare + pawn_push(sideToMove)))); } - else + + if (!enpassant) st->epSquare = SQ_NONE; // 5-6. Halfmove clock and fullmove number ss >> std::skipws >> st->rule50 >> gamePly; - // Convert from fullmove starting from 1 to ply starting from 0, + // Convert from fullmove starting from 1 to gamePly starting from 0, // handle also common incorrect FEN with fullmove = 0. gamePly = std::max(2 * (gamePly - 1), 0) + (sideToMove == BLACK); chess960 = isChess960; thisThread = th; set_state(st); - - assert(pos_is_ok()); + st->accumulator.state[WHITE] = Eval::NNUE::INIT; + st->accumulator.state[BLACK] = Eval::NNUE::INIT; return *this; } @@ -267,24 +293,18 @@ Position& Position::set(const string& fenStr, bool isChess960, StateInfo* si, Th void Position::set_castling_right(Color c, Square rfrom) { Square kfrom = square(c); - CastlingSide cs = kfrom < rfrom ? KING_SIDE : QUEEN_SIDE; - CastlingRight cr = (c | cs); + CastlingRights cr = c & (kfrom < rfrom ? KING_SIDE: QUEEN_SIDE); st->castlingRights |= cr; castlingRightsMask[kfrom] |= cr; castlingRightsMask[rfrom] |= cr; castlingRookSquare[cr] = rfrom; - Square kto = relative_square(c, cs == KING_SIDE ? SQ_G1 : SQ_C1); - Square rto = relative_square(c, cs == KING_SIDE ? SQ_F1 : SQ_D1); + Square kto = relative_square(c, cr & KING_SIDE ? SQ_G1 : SQ_C1); + Square rto = relative_square(c, cr & KING_SIDE ? SQ_F1 : SQ_D1); - for (Square s = std::min(rfrom, rto); s <= std::max(rfrom, rto); ++s) - if (s != kfrom && s != rfrom) - castlingPath[cr] |= s; - - for (Square s = std::min(kfrom, kto); s <= std::max(kfrom, kto); ++s) - if (s != kfrom && s != rfrom) - castlingPath[cr] |= s; + castlingPath[cr] = (between_bb(rfrom, rto) | between_bb(kfrom, kto) | rto | kto) + & ~(kfrom | rfrom); } @@ -292,15 +312,15 @@ void Position::set_castling_right(Color c, Square rfrom) { void Position::set_check_info(StateInfo* si) const { - si->blockersForKing[WHITE] = slider_blockers(pieces(BLACK), square(WHITE)); - si->blockersForKing[BLACK] = slider_blockers(pieces(WHITE), square(BLACK)); + si->blockersForKing[WHITE] = slider_blockers(pieces(BLACK), square(WHITE), si->pinners[BLACK]); + si->blockersForKing[BLACK] = slider_blockers(pieces(WHITE), square(BLACK), si->pinners[WHITE]); Square ksq = square(~sideToMove); - si->checkSquares[PAWN] = attacks_from(ksq, ~sideToMove); - si->checkSquares[KNIGHT] = attacks_from(ksq); - si->checkSquares[BISHOP] = attacks_from(ksq); - si->checkSquares[ROOK] = attacks_from(ksq); + 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; } @@ -313,9 +333,9 @@ void Position::set_check_info(StateInfo* si) const { void Position::set_state(StateInfo* si) const { - si->key = si->pawnKey = si->materialKey = 0; + si->key = si->materialKey = 0; + si->pawnKey = Zobrist::noPawns; si->nonPawnMaterial[WHITE] = si->nonPawnMaterial[BLACK] = VALUE_ZERO; - si->psq = SCORE_ZERO; si->checkersBB = attackers_to(square(sideToMove)) & pieces(~sideToMove); set_check_info(si); @@ -325,7 +345,12 @@ void Position::set_state(StateInfo* si) const { Square s = pop_lsb(&b); Piece pc = piece_on(s); si->key ^= Zobrist::psq[pc][s]; - si->psq += PSQT::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 (si->epSquare != SQ_NONE) @@ -336,20 +361,32 @@ void Position::set_state(StateInfo* si) const { si->key ^= Zobrist::castling[si->castlingRights]; - for (Bitboard b = pieces(PAWN); b; ) - { - Square s = pop_lsb(&b); - si->pawnKey ^= Zobrist::psq[piece_on(s)][s]; - } + for (Piece pc : Pieces) + for (int cnt = 0; cnt < pieceCount[pc]; ++cnt) + si->materialKey ^= Zobrist::psq[pc][cnt]; +} + + +/// Position::set() is an overload to initialize the position object with +/// the given endgame code string like "KBPKN". It is mainly a helper to +/// get the material key out of an endgame code. + +Position& Position::set(const string& code, Color c, StateInfo* si) { + + assert(code[0] == 'K'); - for (Color c = WHITE; c <= BLACK; ++c) - for (PieceType pt = PAWN; pt <= KING; ++pt) - for (int cnt = 0; cnt < pieceCount[make_piece(c, pt)]; ++cnt) - si->materialKey ^= Zobrist::psq[make_piece(c, pt)][cnt]; + string sides[] = { code.substr(code.find('K', 1)), // Weak + code.substr(0, std::min(code.find('v'), code.find('K', 1))) }; // Strong - for (Color c = WHITE; c <= BLACK; ++c) - for (PieceType pt = KNIGHT; pt <= QUEEN; ++pt) - si->nonPawnMaterial[c] += pieceCount[make_piece(c, pt)] * PieceValue[MG][pt]; + assert(sides[0].length() > 0 && sides[0].length() < 8); + assert(sides[1].length() > 0 && sides[1].length() < 8); + + std::transform(sides[c].begin(), sides[c].end(), sides[c].begin(), tolower); + + string fenStr = "8/" + sides[0] + char(8 - sides[0].length() + '0') + "/8/8/8/8/" + + sides[1] + char(8 - sides[1].length() + '0') + "/8 w - - 0 10"; + + return set(fenStr, false, si, nullptr); } @@ -382,18 +419,18 @@ const string Position::fen() const { ss << (sideToMove == WHITE ? " w " : " b "); if (can_castle(WHITE_OO)) - ss << (chess960 ? char('A' + file_of(castling_rook_square(WHITE | KING_SIDE))) : 'K'); + ss << (chess960 ? char('A' + file_of(castling_rook_square(WHITE_OO ))) : 'K'); if (can_castle(WHITE_OOO)) - ss << (chess960 ? char('A' + file_of(castling_rook_square(WHITE | QUEEN_SIDE))) : 'Q'); + ss << (chess960 ? char('A' + file_of(castling_rook_square(WHITE_OOO))) : 'Q'); if (can_castle(BLACK_OO)) - ss << (chess960 ? char('a' + file_of(castling_rook_square(BLACK | KING_SIDE))) : 'k'); + ss << (chess960 ? char('a' + file_of(castling_rook_square(BLACK_OO ))) : 'k'); if (can_castle(BLACK_OOO)) - ss << (chess960 ? char('a' + file_of(castling_rook_square(BLACK | QUEEN_SIDE))) : 'q'); + ss << (chess960 ? char('a' + file_of(castling_rook_square(BLACK_OOO))) : 'q'); - if (!can_castle(WHITE) && !can_castle(BLACK)) + if (!can_castle(ANY_CASTLING)) ss << '-'; ss << (ep_square() == SQ_NONE ? " - " : " " + UCI::square(ep_square()) + " ") @@ -403,42 +440,36 @@ const string Position::fen() const { } -/// Position::game_phase() calculates the game phase interpolating total non-pawn -/// material between endgame and midgame limits. - -Phase Position::game_phase() const { - - Value npm = st->nonPawnMaterial[WHITE] + st->nonPawnMaterial[BLACK]; - - npm = std::max(EndgameLimit, std::min(npm, MidgameLimit)); - - return Phase(((npm - EndgameLimit) * PHASE_MIDGAME) / (MidgameLimit - EndgameLimit)); -} - - -/// 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. +/// 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. -Bitboard Position::slider_blockers(Bitboard sliders, Square s) const { +Bitboard Position::slider_blockers(Bitboard sliders, Square s, Bitboard& pinners) const { - Bitboard b, pinners, result = 0; + Bitboard blockers = 0; + pinners = 0; - // Pinners are sliders that attack 's' when a pinned piece is removed - pinners = ( (PseudoAttacks[ROOK ][s] & pieces(QUEEN, ROOK)) - | (PseudoAttacks[BISHOP][s] & pieces(QUEEN, BISHOP))) & sliders; + // 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 occupancy = pieces() ^ snipers; - while (pinners) + while (snipers) { - b = between_bb(s, pop_lsb(&pinners)) & pieces(); - - if (!more_than_one(b)) - result |= b; + Square sniperSq = pop_lsb(&snipers); + Bitboard b = between_bb(s, sniperSq) & occupancy; + + if (b && !more_than_one(b)) + { + blockers |= b; + if (b & pieces(color_of(piece_on(s)))) + pinners |= sniperSq; + } } - return result; + return blockers; } @@ -447,12 +478,12 @@ Bitboard Position::slider_blockers(Bitboard sliders, Square s) const { Bitboard Position::attackers_to(Square s, Bitboard occupied) const { - return (attacks_from(s, BLACK) & pieces(WHITE, PAWN)) - | (attacks_from(s, WHITE) & pieces(BLACK, PAWN)) - | (attacks_from(s) & pieces(KNIGHT)) - | (attacks_bb(s, occupied) & pieces(ROOK, QUEEN)) + return (pawn_attacks_bb(BLACK, s) & pieces(WHITE, PAWN)) + | (pawn_attacks_bb(WHITE, s) & pieces(BLACK, PAWN)) + | (attacks_bb(s) & pieces(KNIGHT)) + | (attacks_bb< ROOK>(s, occupied) & pieces( ROOK, QUEEN)) | (attacks_bb(s, occupied) & pieces(BISHOP, QUEEN)) - | (attacks_from(s) & pieces(KING)); + | (attacks_bb(s) & pieces(KING)); } @@ -464,6 +495,7 @@ bool Position::legal(Move m) const { Color us = sideToMove; Square from = from_sq(m); + Square to = to_sq(m); assert(color_of(moved_piece(m)) == us); assert(piece_on(square(us)) == make_piece(us, KING)); @@ -474,7 +506,6 @@ bool Position::legal(Move m) const { if (type_of(m) == ENPASSANT) { Square ksq = square(us); - Square to = to_sq(m); Square capsq = to - pawn_push(us); Bitboard occupied = (pieces() ^ from ^ capsq) | to; @@ -487,16 +518,35 @@ bool Position::legal(Move m) const { && !(attacks_bb(ksq, occupied) & pieces(~us, QUEEN, BISHOP)); } - // If the moving piece is a king, check whether the destination - // square is attacked by the opponent. Castling moves are checked - // for legality during move generation. + // Castling moves generation does not check if the castling path is clear of + // enemy attacks, it is delayed at a later time: now! + if (type_of(m) == CASTLING) + { + // After castling, the rook and king final positions are the same in + // Chess960 as they would be in standard chess. + to = relative_square(us, to > from ? SQ_G1 : SQ_C1); + Direction step = to > from ? WEST : EAST; + + for (Square s = to; s != from; s += step) + if (attackers_to(s) & pieces(~us)) + return false; + + // In case of Chess960, verify that when moving the castling rook we do + // not discover some hidden checker. + // For instance an enemy queen in SQ_A1 when castling rook is in SQ_B1. + return !chess960 + || !(attacks_bb(to, pieces() ^ to_sq(m)) & pieces(~us, ROOK, QUEEN)); + } + + // If the moving piece is a king, check whether the destination square is + // attacked by the opponent. if (type_of(piece_on(from)) == KING) - return type_of(m) == CASTLING || !(attackers_to(to_sq(m)) & pieces(~us)); + return !(attackers_to(to) & pieces(~us)); // A non-king move is legal if and only if it is not pinned or it // is moving along the ray towards or away from the king. - return !(pinned_pieces(us) & from) - || aligned(from, to_sq(m), square(us)); + return !(blockers_for_king(us) & from) + || aligned(from, to, square(us)); } @@ -533,18 +583,18 @@ bool Position::pseudo_legal(const Move m) const { { // We have already handled promotion moves, so destination // cannot be on the 8th/1st rank. - if (rank_of(to) == relative_rank(us, RANK_8)) + if ((Rank8BB | Rank1BB) & to) return false; - if ( !(attacks_from(from, us) & pieces(~us) & to) // Not a capture + 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 - && (rank_of(from) == relative_rank(us, RANK_2)) + && (relative_rank(us, from) == RANK_2) && empty(to) && empty(to - pawn_push(us)))) return false; } - else if (!(attacks_from(pc, from) & to)) + else if (!(attacks_bb(type_of(pc), from, pieces()) & to)) return false; // Evasions generator already takes care to avoid some kind of illegal moves @@ -583,11 +633,11 @@ bool Position::gives_check(Move m) const { Square to = to_sq(m); // Is there a direct check? - if (st->checkSquares[type_of(piece_on(from))] & to) + if (check_squares(type_of(piece_on(from))) & to) return true; // Is there a discovered check? - if ( (discovered_check_candidates() & from) + if ( (blockers_for_king(~sideToMove) & from) && !aligned(from, to, square(~sideToMove))) return true; @@ -597,7 +647,7 @@ bool Position::gives_check(Move m) const { return false; case PROMOTION: - return attacks_bb(Piece(promotion_type(m)), to, pieces() ^ from) & square(~sideToMove); + return attacks_bb(promotion_type(m), to, pieces() ^ from) & square(~sideToMove); // En passant capture with check? We have already handled the case // of direct checks and ordinary discovered check, so the only case we @@ -614,11 +664,11 @@ bool Position::gives_check(Move m) const { case CASTLING: { Square kfrom = from; - Square rfrom = to; // Castling is encoded as 'King captures the rook' + Square rfrom = to; // Castling is encoded as 'king captures the rook' Square kto = relative_square(sideToMove, rfrom > kfrom ? SQ_G1 : SQ_C1); Square rto = relative_square(sideToMove, rfrom > kfrom ? SQ_F1 : SQ_D1); - return (PseudoAttacks[ROOK][rto] & square(~sideToMove)) + return (attacks_bb(rto) & square(~sideToMove)) && (attacks_bb(rto, (pieces() ^ kfrom ^ rfrom) | rto | kto) & square(~sideToMove)); } default: @@ -637,7 +687,7 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { assert(is_ok(m)); assert(&newSt != st); - ++nodes; + thisThread->nodes.fetch_add(1, std::memory_order_relaxed); Key k = st->key ^ Zobrist::side; // Copy some fields of the old state to our new StateInfo object except the @@ -653,6 +703,12 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { ++st->rule50; ++st->pliesFromNull; + // Used by NNUE + st->accumulator.state[WHITE] = Eval::NNUE::EMPTY; + st->accumulator.state[BLACK] = Eval::NNUE::EMPTY; + auto& dp = st->dirtyPiece; + dp.dirty_num = 1; + Color us = sideToMove; Color them = ~us; Square from = from_sq(m); @@ -672,7 +728,6 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { Square rfrom, rto; do_castling(us, from, to, rfrom, rto); - st->psq += PSQT::psq[captured][rto] - PSQT::psq[captured][rfrom]; k ^= Zobrist::psq[captured][rfrom] ^ Zobrist::psq[captured][rto]; captured = NO_PIECE; } @@ -694,8 +749,6 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { assert(relative_rank(us, to) == RANK_6); assert(piece_on(to) == NO_PIECE); assert(piece_on(capsq) == make_piece(them, PAWN)); - - board[capsq] = NO_PIECE; // Not done by remove_piece() } st->pawnKey ^= Zobrist::psq[captured][capsq]; @@ -703,17 +756,25 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { else st->nonPawnMaterial[them] -= PieceValue[MG][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; + } + // Update board and piece lists - remove_piece(captured, capsq); + remove_piece(capsq); + + if (type_of(m) == ENPASSANT) + 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]); - // Update incremental scores - st->psq -= PSQT::psq[captured][capsq]; - // Reset rule 50 counter st->rule50 = 0; } @@ -731,23 +792,32 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { // Update castling rights if needed if (st->castlingRights && (castlingRightsMask[from] | castlingRightsMask[to])) { - int cr = castlingRightsMask[from] | castlingRightsMask[to]; - k ^= Zobrist::castling[st->castlingRights & cr]; - st->castlingRights &= ~cr; + k ^= Zobrist::castling[st->castlingRights]; + st->castlingRights &= ~(castlingRightsMask[from] | castlingRightsMask[to]); + k ^= Zobrist::castling[st->castlingRights]; } // Move the piece. The tricky Chess960 castling is handled earlier if (type_of(m) != CASTLING) - move_piece(pc, from, to); + { + if (Eval::useNNUE) + { + dp.piece[0] = pc; + dp.from[0] = from; + dp.to[0] = to; + } + + move_piece(from, to); + } // If the moving piece is a pawn do some special extra work if (type_of(pc) == PAWN) { // Set en-passant square if the moved pawn can be captured if ( (int(to) ^ int(from)) == 16 - && (attacks_from(to - pawn_push(us), us) & pieces(them, PAWN))) + && (pawn_attacks_bb(us, to - pawn_push(us)) & pieces(them, PAWN))) { - st->epSquare = (from + to) / 2; + st->epSquare = to - pawn_push(us); k ^= Zobrist::enpassant[file_of(st->epSquare)]; } @@ -758,33 +828,36 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { assert(relative_rank(us, to) == RANK_8); assert(type_of(promotion) >= KNIGHT && type_of(promotion) <= QUEEN); - remove_piece(pc, to); + 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++; + } + // 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 incremental score - st->psq += PSQT::psq[promotion][to] - PSQT::psq[pc][to]; - // Update material st->nonPawnMaterial[us] += PieceValue[MG][promotion]; } - // Update pawn hash key and prefetch access to pawnsTable + // Update pawn hash key st->pawnKey ^= Zobrist::psq[pc][from] ^ Zobrist::psq[pc][to]; - prefetch(thisThread->pawnsTable[st->pawnKey]); // Reset rule 50 draw counter st->rule50 = 0; } - // Update incremental scores - st->psq += PSQT::psq[pc][to] - PSQT::psq[pc][from]; - // Set capture piece st->capturedPiece = captured; @@ -799,6 +872,25 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { // Update king attacks used for fast check detection set_check_info(st); + // 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 + // if the position was not repeated. + st->repetition = 0; + int end = std::min(st->rule50, st->pliesFromNull); + if (end >= 4) + { + StateInfo* stp = st->previous->previous; + for (int i = 4; i <= end; i += 2) + { + stp = stp->previous->previous; + if (stp->key == st->key) + { + st->repetition = stp->repetition ? -i : i; + break; + } + } + } + assert(pos_is_ok()); } @@ -826,7 +918,7 @@ void Position::undo_move(Move m) { assert(type_of(pc) == promotion_type(m)); assert(type_of(pc) >= KNIGHT && type_of(pc) <= QUEEN); - remove_piece(pc, to); + remove_piece(to); pc = make_piece(us, PAWN); put_piece(pc, to); } @@ -838,7 +930,7 @@ void Position::undo_move(Move m) { } else { - move_piece(pc, to, from); // Put the piece back at the source square + move_piece(to, from); // Put the piece back at the source square if (st->capturedPiece) { @@ -877,16 +969,28 @@ 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) + { + auto& dp = st->dirtyPiece; + dp.piece[0] = make_piece(us, KING); + dp.from[0] = from; + dp.to[0] = to; + dp.piece[1] = make_piece(us, ROOK); + dp.from[1] = rfrom; + dp.to[1] = rto; + dp.dirty_num = 2; + } + // Remove both pieces first since squares could overlap in Chess960 - remove_piece(make_piece(us, KING), Do ? from : to); - remove_piece(make_piece(us, ROOK), Do ? rfrom : rto); - board[Do ? from : to] = board[Do ? rfrom : rto] = NO_PIECE; // Since remove_piece doesn't do it for us + 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 put_piece(make_piece(us, KING), Do ? to : from); put_piece(make_piece(us, ROOK), Do ? rto : rfrom); } -/// Position::do(undo)_null_move() is used to do(undo) a "null move": It flips +/// Position::do(undo)_null_move() is used to do(undo) a "null move": it flips /// the side to move without executing any move on the board. void Position::do_null_move(StateInfo& newSt) { @@ -894,10 +998,16 @@ void Position::do_null_move(StateInfo& newSt) { assert(!checkers()); assert(&newSt != st); - std::memcpy(&newSt, st, sizeof(StateInfo)); + std::memcpy(&newSt, st, offsetof(StateInfo, accumulator)); + newSt.previous = st; st = &newSt; + st->dirtyPiece.dirty_num = 0; + st->dirtyPiece.piece[0] = NO_PIECE; // Avoid checks in UpdateAccumulator() + st->accumulator.state[WHITE] = Eval::NNUE::EMPTY; + st->accumulator.state[BLACK] = Eval::NNUE::EMPTY; + if (st->epSquare != SQ_NONE) { st->key ^= Zobrist::enpassant[file_of(st->epSquare)]; @@ -914,6 +1024,8 @@ void Position::do_null_move(StateInfo& newSt) { set_check_info(st); + st->repetition = 0; + assert(pos_is_ok()); } @@ -945,109 +1057,187 @@ Key Position::key_after(Move m) const { } -/// Position::see() is a static exchange evaluator: It tries to estimate the -/// material gain or loss resulting from a move. +/// Position::see_ge (Static Exchange Evaluation Greater or Equal) tests if the +/// SEE value of move is greater or equal to the given threshold. We'll use an +/// algorithm similar to alpha-beta pruning with a null window. -Value Position::see_sign(Move m) const { +bool Position::see_ge(Move m, Value threshold) const { assert(is_ok(m)); - // Early return if SEE cannot be negative because captured piece value - // is not less then capturing one. Note that king moves always return - // here because king midgame value is set to 0. - if (PieceValue[MG][moved_piece(m)] <= PieceValue[MG][piece_on(to_sq(m))]) - return VALUE_KNOWN_WIN; + // Only deal with normal moves, assume others pass a simple see + if (type_of(m) != NORMAL) + return VALUE_ZERO >= threshold; - return see(m); -} + Square from = from_sq(m), to = to_sq(m); -Value Position::see(Move m) const { + int swap = PieceValue[MG][piece_on(to)] - threshold; + if (swap < 0) + return false; - Square from, to; - Bitboard occupied, attackers, stmAttackers; - Value swapList[32]; - int slIndex = 1; - PieceType captured; - Color stm; + swap = PieceValue[MG][piece_on(from)] - swap; + if (swap <= 0) + return true; - assert(is_ok(m)); + Bitboard occupied = pieces() ^ from ^ to; + Color stm = color_of(piece_on(from)); + Bitboard attackers = attackers_to(to, occupied); + Bitboard stmAttackers, bb; + int res = 1; - from = from_sq(m); - to = to_sq(m); - swapList[0] = PieceValue[MG][piece_on(to)]; - stm = color_of(piece_on(from)); - occupied = pieces() ^ from; + while (true) + { + stm = ~stm; + attackers &= occupied; - // Castling moves are implemented as king capturing the rook so cannot - // be handled correctly. Simply return VALUE_ZERO that is always correct - // unless in the rare case the rook ends up under attack. - if (type_of(m) == CASTLING) - return VALUE_ZERO; + // If stm has no more attackers then give up: stm loses + if (!(stmAttackers = attackers & pieces(stm))) + break; - if (type_of(m) == ENPASSANT) - { - occupied ^= to - pawn_push(stm); // Remove the captured pawn - swapList[0] = PieceValue[MG][PAWN]; - } + // Don't allow pinned pieces to attack (except the king) as long as + // there are pinners on their original square. + if (pinners(~stm) & occupied) + stmAttackers &= ~blockers_for_king(stm); - // Find all attackers to the destination square, with the moving piece - // removed, but possibly an X-ray attacker added behind it. - attackers = attackers_to(to, occupied) & occupied; + if (!stmAttackers) + break; - // If the opponent has no attackers we are finished - stm = ~stm; - stmAttackers = attackers & pieces(stm); - if (!stmAttackers) - return swapList[0]; + res ^= 1; - // The destination square is defended, which makes things rather more - // difficult to compute. We proceed by building up a "swap list" containing - // the material gain or loss at each stop in a sequence of captures to the - // destination square, where the sides alternately capture, and always - // capture with the least valuable piece. After each capture, we look for - // new X-ray attacks from behind the capturing piece. - captured = type_of(piece_on(from)); + // Locate and remove the next least valuable attacker, and add to + // the bitboard 'attackers' any X-ray attackers behind it. + if ((bb = stmAttackers & pieces(PAWN))) + { + if ((swap = PawnValueMg - swap) < res) + break; + + occupied ^= lsb(bb); + attackers |= attacks_bb(to, occupied) & pieces(BISHOP, QUEEN); + } - do { - assert(slIndex < 32); + else if ((bb = stmAttackers & pieces(KNIGHT))) + { + if ((swap = KnightValueMg - swap) < res) + break; - // Add the new entry to the swap list - swapList[slIndex] = -swapList[slIndex - 1] + PieceValue[MG][captured]; + occupied ^= lsb(bb); + } - // Locate and remove the next least valuable attacker - captured = min_attacker(byTypeBB, to, stmAttackers, occupied, attackers); - stm = ~stm; - stmAttackers = attackers & pieces(stm); - ++slIndex; + else if ((bb = stmAttackers & pieces(BISHOP))) + { + if ((swap = BishopValueMg - swap) < res) + break; - } while (stmAttackers && (captured != KING || (--slIndex, false))); // Stop before a king capture + occupied ^= lsb(bb); + attackers |= attacks_bb(to, occupied) & pieces(BISHOP, QUEEN); + } - // Having built the swap list, we negamax through it to find the best - // achievable score from the point of view of the side to move. - while (--slIndex) - swapList[slIndex - 1] = std::min(-swapList[slIndex], swapList[slIndex - 1]); + else if ((bb = stmAttackers & pieces(ROOK))) + { + if ((swap = RookValueMg - swap) < res) + break; + + occupied ^= lsb(bb); + attackers |= attacks_bb(to, occupied) & pieces(ROOK, QUEEN); + } + + else if ((bb = stmAttackers & pieces(QUEEN))) + { + if ((swap = QueenValueMg - swap) < res) + break; + + occupied ^= lsb(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, + // reverse the result. + return (attackers & ~pieces(stm)) ? res ^ 1 : res; + } - return swapList[0]; + return bool(res); } /// Position::is_draw() tests whether the position is drawn by 50-move rule /// or by repetition. It does not detect stalemates. -bool Position::is_draw() const { +bool Position::is_draw(int ply) const { if (st->rule50 > 99 && (!checkers() || MoveList(*this).size())) return true; - StateInfo* stp = st; - for (int i = 2, e = std::min(st->rule50, st->pliesFromNull); i <= e; i += 2) + // Return a draw score if a position repeats once earlier but strictly + // after the root, or repeats twice before or at the root. + return st->repetition && st->repetition < ply; +} + + +// Position::has_repeated() tests whether there has been at least one repetition +// of positions since the last capture or pawn move. + +bool Position::has_repeated() const { + + StateInfo* stc = st; + int end = std::min(st->rule50, st->pliesFromNull); + while (end-- >= 4) + { + if (stc->repetition) + return true; + + stc = stc->previous; + } + return false; +} + + +/// Position::has_game_cycle() tests if the position has a move which draws by repetition, +/// or an earlier position has a move that directly reaches the current position. + +bool Position::has_game_cycle(int ply) const { + + int j; + + int end = std::min(st->rule50, st->pliesFromNull); + + if (end < 3) + return false; + + Key originalKey = st->key; + StateInfo* stp = st->previous; + + for (int i = 3; i <= end; i += 2) { stp = stp->previous->previous; - if (stp->key == st->key) - return true; // Draw at first repetition - } + Key moveKey = originalKey ^ stp->key; + if ( (j = H1(moveKey), cuckoo[j] == moveKey) + || (j = H2(moveKey), cuckoo[j] == moveKey)) + { + Move move = cuckooMove[j]; + Square s1 = from_sq(move); + Square s2 = to_sq(move); + if (!(between_bb(s1, s2) & pieces())) + { + if (ply > i) + return true; + + // For nodes before or at the root, check that the move is a + // repetition rather than a move to the current position. + // In the cuckoo table, both moves Rc1c5 and Rc5c1 are stored in + // the same location, so we have to select which square to check. + if (color_of(piece_on(empty(s1) ? s2 : s1)) != side_to_move()) + continue; + + // For repetitions before or at the root, require one more + if (stp->repetition) + return true; + } + } + } return false; } @@ -1087,81 +1277,68 @@ void Position::flip() { } -/// Position::pos_is_ok() performs some consistency checks for the position object. +/// Position::pos_is_ok() performs some consistency checks for the +/// position object and raises an asserts if something wrong is detected. /// This is meant to be helpful when debugging. -bool Position::pos_is_ok(int* failedStep) const { - - const bool Fast = true; // Quick (default) or full check? +bool Position::pos_is_ok() const { - enum { Default, King, Bitboards, State, Lists, Castling }; + constexpr bool Fast = true; // Quick (default) or full check? - for (int step = Default; step <= (Fast ? Default : Castling); step++) - { - if (failedStep) - *failedStep = step; - - if (step == Default) - if ( (sideToMove != WHITE && sideToMove != BLACK) - || piece_on(square(WHITE)) != W_KING - || piece_on(square(BLACK)) != B_KING - || ( ep_square() != SQ_NONE - && relative_rank(sideToMove, ep_square()) != RANK_6)) - return false; + if ( (sideToMove != WHITE && sideToMove != BLACK) + || piece_on(square(WHITE)) != W_KING + || piece_on(square(BLACK)) != B_KING + || ( ep_square() != SQ_NONE + && relative_rank(sideToMove, ep_square()) != RANK_6)) + assert(0 && "pos_is_ok: Default"); - if (step == King) - if ( std::count(board, board + SQUARE_NB, W_KING) != 1 - || std::count(board, board + SQUARE_NB, B_KING) != 1 - || attackers_to(square(~sideToMove)) & pieces(sideToMove)) - return false; + if (Fast) + return true; - if (step == Bitboards) + if ( pieceCount[W_KING] != 1 + || pieceCount[B_KING] != 1 + || attackers_to(square(~sideToMove)) & pieces(sideToMove)) + assert(0 && "pos_is_ok: Kings"); + + if ( (pieces(PAWN) & (Rank1BB | Rank8BB)) + || pieceCount[W_PAWN] > 8 + || pieceCount[B_PAWN] > 8) + assert(0 && "pos_is_ok: Pawns"); + + if ( (pieces(WHITE) & pieces(BLACK)) + || (pieces(WHITE) | pieces(BLACK)) != pieces() + || popcount(pieces(WHITE)) > 16 + || popcount(pieces(BLACK)) > 16) + assert(0 && "pos_is_ok: Bitboards"); + + for (PieceType p1 = PAWN; p1 <= KING; ++p1) + for (PieceType p2 = PAWN; p2 <= KING; ++p2) + if (p1 != p2 && (pieces(p1) & pieces(p2))) + assert(0 && "pos_is_ok: Bitboards"); + + StateInfo si = *st; + ASSERT_ALIGNED(&si, Eval::NNUE::kCacheLineSize); + + 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))) + || pieceCount[pc] != std::count(board, board + SQUARE_NB, pc)) + assert(0 && "pos_is_ok: Pieces"); + + for (Color c : { WHITE, BLACK }) + for (CastlingRights cr : {c & KING_SIDE, c & QUEEN_SIDE}) { - if ( (pieces(WHITE) & pieces(BLACK)) - ||(pieces(WHITE) | pieces(BLACK)) != pieces()) - return false; + if (!can_castle(cr)) + continue; - for (PieceType p1 = PAWN; p1 <= KING; ++p1) - for (PieceType p2 = PAWN; p2 <= KING; ++p2) - if (p1 != p2 && (pieces(p1) & pieces(p2))) - return false; + if ( piece_on(castlingRookSquare[cr]) != make_piece(c, ROOK) + || castlingRightsMask[castlingRookSquare[cr]] != cr + || (castlingRightsMask[square(c)] & cr) != cr) + assert(0 && "pos_is_ok: Castling"); } - if (step == State) - { - StateInfo si = *st; - set_state(&si); - if (std::memcmp(&si, st, sizeof(StateInfo))) - return false; - } - - if (step == Lists) - for (Color c = WHITE; c <= BLACK; ++c) - for (PieceType pt = PAWN; pt <= KING; ++pt) - { - Piece pc = make_piece(c, pt); - - if (pieceCount[pc] != popcount(pieces(c, pt))) - return false; - - for (int i = 0; i < pieceCount[pc]; ++i) - if (board[pieceList[pc][i]] != pc || index[pieceList[pc][i]] != i) - return false; - } - - if (step == Castling) - for (Color c = WHITE; c <= BLACK; ++c) - for (CastlingSide s = KING_SIDE; s <= QUEEN_SIDE; s = CastlingSide(s + 1)) - { - if (!can_castle(c | s)) - continue; - - if ( piece_on(castlingRookSquare[c | s]) != make_piece(c, ROOK) - || castlingRightsMask[castlingRookSquare[c | s]] != (c | s) - ||(castlingRightsMask[square(c)] & (c | s)) != (c | s)) - return false; - } - } - return true; }