X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovepick.cpp;h=694b9222fe573945c826e627865e6b4d5565f58c;hp=133d939de6cbd45a1c12e163b240a8c7773d1d02;hb=HEAD;hpb=9742fb10fd83e82ad760e4cac5cef3d6dff670ed diff --git a/src/movepick.cpp b/src/movepick.cpp index 133d939d..0267a8e2 100644 --- a/src/movepick.cpp +++ b/src/movepick.cpp @@ -1,14 +1,12 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 - Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008-2016 Marco Costalba, Joona Kiiski, Tord Romstad + 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 the Free Software Foundation, either version 3 of the License, or (at your option) any later version. - Stockfish is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the @@ -18,301 +16,351 @@ along with this program. If not, see . */ -#include - #include "movepick.h" -#include "thread.h" - -namespace { - - enum Stages { - MAIN_SEARCH, GOOD_CAPTURES, KILLERS, GOOD_QUIETS, BAD_QUIETS, BAD_CAPTURES, - EVASION, ALL_EVASIONS, - QSEARCH_WITH_CHECKS, QCAPTURES_1, CHECKS, - QSEARCH_WITHOUT_CHECKS, QCAPTURES_2, - PROBCUT, PROBCUT_CAPTURES, - RECAPTURE, RECAPTURES, - STOP - }; - - // Our insertion sort, which is guaranteed to be stable, as it should be - void insertion_sort(ExtMove* begin, ExtMove* end) - { - ExtMove tmp, *p, *q; - - for (p = begin + 1; p < end; ++p) - { - tmp = *p; - for (q = p; q != begin && *(q-1) < tmp; --q) - *q = *(q-1); - *q = tmp; - } - } - // pick_best() finds the best move in the range (begin, end) and moves it to - // the front. It's faster than sorting all the moves in advance when there - // are few moves e.g. the possible captures. - Move pick_best(ExtMove* begin, ExtMove* end) - { - std::swap(*begin, *std::max_element(begin, end)); - return *begin; - } +#include +#include +#include +#include -} // namespace +#include "bitboard.h" +#include "position.h" +namespace Stockfish { -/// Constructors of the MovePicker class. As arguments we pass information -/// to help it to return the (presumably) good moves first, to decide which -/// moves to return (in the quiescence search, for instance, we only want to -/// search captures, promotions and some checks) and how important good move -/// ordering is at the current node. +namespace { -MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const HistoryStats& h, - const CounterMovesStats& cmh, Move cm, Search::Stack* s) - : pos(p), history(h), counterMovesHistory(&cmh), ss(s), countermove(cm), depth(d) { +enum Stages { + // generate main search moves + MAIN_TT, + CAPTURE_INIT, + GOOD_CAPTURE, + REFUTATION, + QUIET_INIT, + QUIET, + BAD_CAPTURE, + + // generate evasion moves + EVASION_TT, + EVASION_INIT, + EVASION, + + // generate probcut moves + PROBCUT_TT, + PROBCUT_INIT, + PROBCUT, + + // generate qsearch moves + QSEARCH_TT, + QCAPTURE_INIT, + QCAPTURE, + QCHECK_INIT, + QCHECK +}; + +// Sort moves in descending order up to and including +// a given limit. The order of moves smaller than the limit is left unspecified. +void partial_insertion_sort(ExtMove* begin, ExtMove* end, int limit) { + + for (ExtMove *sortedEnd = begin, *p = begin + 1; p < end; ++p) + if (p->value >= limit) + { + ExtMove tmp = *p, *q; + *p = *++sortedEnd; + for (q = sortedEnd; q != begin && *(q - 1) < tmp; --q) + *q = *(q - 1); + *q = tmp; + } +} - assert(d > DEPTH_ZERO); +} // namespace + + +// Constructors of the MovePicker class. As arguments, we pass information +// to help it return the (presumably) good moves first, to decide which +// moves to return (in the quiescence search, for instance, we only want to +// search captures, promotions, and some checks) and how important a good +// move ordering is at the current node. + +// MovePicker constructor for the main search +MovePicker::MovePicker(const Position& p, + Move ttm, + Depth d, + const ButterflyHistory* mh, + const CapturePieceToHistory* cph, + const PieceToHistory** ch, + const PawnHistory* ph, + Move cm, + const Move* killers) : + pos(p), + mainHistory(mh), + captureHistory(cph), + continuationHistory(ch), + pawnHistory(ph), + ttMove(ttm), + refutations{{killers[0], 0}, {killers[1], 0}, {cm, 0}}, + depth(d) { + assert(d > 0); + + stage = (pos.checkers() ? EVASION_TT : MAIN_TT) + !(ttm && pos.pseudo_legal(ttm)); +} - stage = pos.checkers() ? EVASION : MAIN_SEARCH; - ttMove = ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE; - endMoves += (ttMove != MOVE_NONE); +// Constructor for quiescence search +MovePicker::MovePicker(const Position& p, + Move ttm, + Depth d, + const ButterflyHistory* mh, + const CapturePieceToHistory* cph, + const PieceToHistory** ch, + const PawnHistory* ph) : + pos(p), + mainHistory(mh), + captureHistory(cph), + continuationHistory(ch), + pawnHistory(ph), + ttMove(ttm), + depth(d) { + assert(d <= 0); + + stage = (pos.checkers() ? EVASION_TT : QSEARCH_TT) + !(ttm && pos.pseudo_legal(ttm)); } -MovePicker::MovePicker(const Position& p, Move ttm, Depth d, - const HistoryStats& h, Square s) - : pos(p), history(h), counterMovesHistory(nullptr) { +// Constructor for ProbCut: we generate captures with SEE greater +// than or equal to the given threshold. +MovePicker::MovePicker(const Position& p, Move ttm, Value th, const CapturePieceToHistory* cph) : + pos(p), + captureHistory(cph), + ttMove(ttm), + threshold(th) { + assert(!pos.checkers()); + + stage = PROBCUT_TT + + !(ttm && pos.capture_stage(ttm) && pos.pseudo_legal(ttm) && pos.see_ge(ttm, threshold)); +} - assert(d <= DEPTH_ZERO); +// Assigns a numerical value to each move in a list, used +// for sorting. Captures are ordered by Most Valuable Victim (MVV), preferring +// captures with a good history. Quiets moves are ordered using the history tables. +template +void MovePicker::score() { - if (pos.checkers()) - stage = EVASION; + static_assert(Type == CAPTURES || Type == QUIETS || Type == EVASIONS, "Wrong type"); - else if (d > DEPTH_QS_NO_CHECKS) - stage = QSEARCH_WITH_CHECKS; + [[maybe_unused]] Bitboard threatenedByPawn, threatenedByMinor, threatenedByRook, + threatenedPieces; + if constexpr (Type == QUIETS) + { + Color us = pos.side_to_move(); - else if (d > DEPTH_QS_RECAPTURES) - stage = QSEARCH_WITHOUT_CHECKS; + threatenedByPawn = pos.attacks_by(~us); + threatenedByMinor = + pos.attacks_by(~us) | pos.attacks_by(~us) | threatenedByPawn; + threatenedByRook = pos.attacks_by(~us) | threatenedByMinor; - else - { - stage = RECAPTURE; - recaptureSquare = s; - ttm = MOVE_NONE; - } + // Pieces threatened by pieces of lesser material value + threatenedPieces = (pos.pieces(us, QUEEN) & threatenedByRook) + | (pos.pieces(us, ROOK) & threatenedByMinor) + | (pos.pieces(us, KNIGHT, BISHOP) & threatenedByPawn); + } - ttMove = ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE; - endMoves += (ttMove != MOVE_NONE); + for (auto& m : *this) + if constexpr (Type == CAPTURES) + m.value = + (7 * int(PieceValue[pos.piece_on(to_sq(m))]) + + (*captureHistory)[pos.moved_piece(m)][to_sq(m)][type_of(pos.piece_on(to_sq(m)))]) + / 16; + + else if constexpr (Type == QUIETS) + { + Piece pc = pos.moved_piece(m); + PieceType pt = type_of(pos.moved_piece(m)); + Square from = from_sq(m); + Square to = to_sq(m); + + // histories + m.value = 2 * (*mainHistory)[pos.side_to_move()][from_to(m)]; + m.value += 2 * (*pawnHistory)[pawn_structure(pos)][pc][to]; + m.value += 2 * (*continuationHistory[0])[pc][to]; + m.value += (*continuationHistory[1])[pc][to]; + m.value += (*continuationHistory[2])[pc][to] / 4; + m.value += (*continuationHistory[3])[pc][to]; + m.value += (*continuationHistory[5])[pc][to]; + + // bonus for checks + m.value += bool(pos.check_squares(pt) & to) * 16384; + + // bonus for escaping from capture + m.value += threatenedPieces & from ? (pt == QUEEN && !(to & threatenedByRook) ? 50000 + : pt == ROOK && !(to & threatenedByMinor) ? 25000 + : !(to & threatenedByPawn) ? 15000 + : 0) + : 0; + + // malus for putting piece en prise + m.value -= !(threatenedPieces & from) + ? (pt == QUEEN ? bool(to & threatenedByRook) * 50000 + + bool(to & threatenedByMinor) * 10000 + + bool(to & threatenedByPawn) * 20000 + : pt == ROOK ? bool(to & threatenedByMinor) * 25000 + + bool(to & threatenedByPawn) * 10000 + : pt != PAWN ? bool(to & threatenedByPawn) * 15000 + : 0) + : 0; + } + + else // Type == EVASIONS + { + if (pos.capture_stage(m)) + m.value = PieceValue[pos.piece_on(to_sq(m))] - Value(type_of(pos.moved_piece(m))) + + (1 << 28); + else + m.value = (*mainHistory)[pos.side_to_move()][from_to(m)] + + (*continuationHistory[0])[pos.moved_piece(m)][to_sq(m)] + + (*pawnHistory)[pawn_structure(pos)][pos.moved_piece(m)][to_sq(m)]; + } } -MovePicker::MovePicker(const Position& p, Move ttm, const HistoryStats& h, Value th) - : pos(p), history(h), counterMovesHistory(nullptr), threshold(th) { - - assert(!pos.checkers()); - - stage = PROBCUT; - - // In ProbCut we generate captures with SEE higher than the given threshold - ttMove = ttm - && pos.pseudo_legal(ttm) - && pos.capture(ttm) - && pos.see(ttm) > threshold ? ttm : MOVE_NONE; +// Returns the next move satisfying a predicate function. +// It never returns the TT move. +template +Move MovePicker::select(Pred filter) { - endMoves += (ttMove != MOVE_NONE); -} + while (cur < endMoves) + { + if constexpr (T == Best) + std::swap(*cur, *std::max_element(cur, endMoves)); + if (*cur != ttMove && filter()) + return *cur++; -/// score() assigns a numerical value to each move in a move list. The moves with -/// highest values will be picked first. -template<> -void MovePicker::score() { - // Winning and equal captures in the main search are ordered by MVV, preferring - // captures near our home rank. Surprisingly, this appears to perform slightly - // better than SEE based move ordering: exchanging big pieces before capturing - // a hanging piece probably helps to reduce the subtree size. - // In main search we want to push captures with negative SEE values to the - // badCaptures[] array, but instead of doing it now we delay until the move - // has been picked up, saving some SEE calls in case we get a cutoff. - for (auto& m : *this) - m.value = PieceValue[MG][pos.piece_on(to_sq(m))] - - Value(200 * relative_rank(pos.side_to_move(), to_sq(m))); + cur++; + } + return MOVE_NONE; } -template<> -void MovePicker::score() { +// Most important method of the MovePicker class. It +// returns a new pseudo-legal move every time it is called until there are no more +// moves left, picking the move with the highest score from a list of generated moves. +Move MovePicker::next_move(bool skipQuiets) { - for (auto& m : *this) - m.value = history[pos.moved_piece(m)][to_sq(m)] - + (*counterMovesHistory)[pos.moved_piece(m)][to_sq(m)]; -} - -template<> -void MovePicker::score() { - // Try winning and equal captures captures ordered by MVV/LVA, then non-captures - // ordered by history value, then bad-captures and quiet moves with a negative - // SEE ordered by SEE value. - Value see; - - for (auto& m : *this) - if ((see = pos.see_sign(m)) < VALUE_ZERO) - m.value = see - HistoryStats::Max; // At the bottom - - else if (pos.capture(m)) - m.value = PieceValue[MG][pos.piece_on(to_sq(m))] - - Value(type_of(pos.moved_piece(m))) + HistoryStats::Max; - else - m.value = history[pos.moved_piece(m)][to_sq(m)]; -} +top: + switch (stage) + { + case MAIN_TT : + case EVASION_TT : + case QSEARCH_TT : + case PROBCUT_TT : + ++stage; + return ttMove; + + case CAPTURE_INIT : + case PROBCUT_INIT : + case QCAPTURE_INIT : + cur = endBadCaptures = moves; + endMoves = generate(pos, cur); + + score(); + partial_insertion_sort(cur, endMoves, std::numeric_limits::min()); + ++stage; + goto top; + + case GOOD_CAPTURE : + if (select([&]() { + // Move losing capture to endBadCaptures to be tried later + return pos.see_ge(*cur, Value(-cur->value)) ? true + : (*endBadCaptures++ = *cur, false); + })) + return *(cur - 1); + + // Prepare the pointers to loop over the refutations array + cur = std::begin(refutations); + endMoves = std::end(refutations); + + // If the countermove is the same as a killer, skip it + if (refutations[0].move == refutations[2].move + || refutations[1].move == refutations[2].move) + --endMoves; + + ++stage; + [[fallthrough]]; + + case REFUTATION : + if (select([&]() { + return *cur != MOVE_NONE && !pos.capture_stage(*cur) && pos.pseudo_legal(*cur); + })) + return *(cur - 1); + ++stage; + [[fallthrough]]; + + case QUIET_INIT : + if (!skipQuiets) + { + cur = endBadCaptures; + endMoves = generate(pos, cur); + + score(); + partial_insertion_sort(cur, endMoves, -1960 - 3130 * depth); + } + + ++stage; + [[fallthrough]]; + + case QUIET : + if (!skipQuiets && select([&]() { + return *cur != refutations[0].move && *cur != refutations[1].move + && *cur != refutations[2].move; + })) + return *(cur - 1); + + // Prepare the pointers to loop over the bad captures + cur = moves; + endMoves = endBadCaptures; + + ++stage; + [[fallthrough]]; + + case BAD_CAPTURE : + return select([]() { return true; }); + + case EVASION_INIT : + cur = moves; + endMoves = generate(pos, cur); + + score(); + ++stage; + [[fallthrough]]; + + case EVASION : + return select([]() { return true; }); + + case PROBCUT : + return select([&]() { return pos.see_ge(*cur, threshold); }); + + case QCAPTURE : + if (select([]() { return true; })) + return *(cur - 1); + + // If we did not find any move and we do not try checks, we have finished + if (depth != DEPTH_QS_CHECKS) + return MOVE_NONE; + + ++stage; + [[fallthrough]]; + + case QCHECK_INIT : + cur = moves; + endMoves = generate(pos, cur); + + ++stage; + [[fallthrough]]; + + case QCHECK : + return select([]() { return true; }); + } -/// generate_next_stage() generates, scores and sorts the next bunch of moves, -/// when there are no more moves to try for the current stage. - -void MovePicker::generate_next_stage() { - - assert(stage != STOP); - - cur = moves; - - switch (++stage) { - - case GOOD_CAPTURES: case QCAPTURES_1: case QCAPTURES_2: - case PROBCUT_CAPTURES: case RECAPTURES: - endMoves = generate(pos, moves); - score(); - break; - - case KILLERS: - killers[0] = ss->killers[0]; - killers[1] = ss->killers[1]; - killers[2] = countermove; - cur = killers; - endMoves = cur + 2 + (countermove != killers[0] && countermove != killers[1]); - break; - - case GOOD_QUIETS: - endQuiets = endMoves = generate(pos, moves); - score(); - endMoves = std::partition(cur, endMoves, [](const ExtMove& m) { return m.value > VALUE_ZERO; }); - insertion_sort(cur, endMoves); - break; - - case BAD_QUIETS: - cur = endMoves; - endMoves = endQuiets; - if (depth >= 3 * ONE_PLY) - insertion_sort(cur, endMoves); - break; - - case BAD_CAPTURES: - // Just pick them in reverse order to get correct ordering - cur = moves + MAX_MOVES - 1; - endMoves = endBadCaptures; - break; - - case ALL_EVASIONS: - endMoves = generate(pos, moves); - if (endMoves - moves > 1) - score(); - break; - - case CHECKS: - endMoves = generate(pos, moves); - break; - - case EVASION: case QSEARCH_WITH_CHECKS: case QSEARCH_WITHOUT_CHECKS: - case PROBCUT: case RECAPTURE: case STOP: - stage = STOP; - break; - - default: - assert(false); - } + assert(false); + return MOVE_NONE; // Silence warning } - -/// next_move() is the most important method of the MovePicker class. It returns -/// a new pseudo legal move every time it is called, until there are no more moves -/// left. It picks the move with the biggest value from a list of generated moves -/// taking care not to return the ttMove if it has already been searched. - -Move MovePicker::next_move() { - - Move move; - - while (true) - { - while (cur == endMoves && stage != STOP) - generate_next_stage(); - - switch (stage) { - - case MAIN_SEARCH: case EVASION: case QSEARCH_WITH_CHECKS: - case QSEARCH_WITHOUT_CHECKS: case PROBCUT: - ++cur; - return ttMove; - - case GOOD_CAPTURES: - move = pick_best(cur++, endMoves); - if (move != ttMove) - { - if (pos.see_sign(move) >= VALUE_ZERO) - return move; - - // Losing capture, move it to the tail of the array - *endBadCaptures-- = move; - } - break; - - case KILLERS: - move = *cur++; - if ( move != MOVE_NONE - && move != ttMove - && pos.pseudo_legal(move) - && !pos.capture(move)) - return move; - break; - - case GOOD_QUIETS: case BAD_QUIETS: - move = *cur++; - if ( move != ttMove - && move != killers[0] - && move != killers[1] - && move != killers[2]) - return move; - break; - - case BAD_CAPTURES: - return *cur--; - - case ALL_EVASIONS: case QCAPTURES_1: case QCAPTURES_2: - move = pick_best(cur++, endMoves); - if (move != ttMove) - return move; - break; - - case PROBCUT_CAPTURES: - move = pick_best(cur++, endMoves); - if (move != ttMove && pos.see(move) > threshold) - return move; - break; - - case RECAPTURES: - move = pick_best(cur++, endMoves); - if (to_sq(move) == recaptureSquare) - return move; - break; - - case CHECKS: - move = *cur++; - if (move != ttMove) - return move; - break; - - case STOP: - return MOVE_NONE; - - default: - assert(false); - } - } -} +} // namespace Stockfish