X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fmovepick.cpp;h=d2a49706fc27e34a5b75d0179cb9f16f7cec8d72;hb=ec02714b6262e26d6f96c45c4e2527f3d382a9f8;hp=cc79528027b25334be0316e2499137cd29c3c3e6;hpb=6b9a22b40d37d27ad10cafd8697d96e90a586f8a;p=stockfish diff --git a/src/movepick.cpp b/src/movepick.cpp index cc795280..d2a49706 100644 --- a/src/movepick.cpp +++ b/src/movepick.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) 2015-2017 Marco Costalba, Joona Kiiski, Gary Linscott, 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 @@ -18,330 +16,348 @@ along with this program. If not, see . */ +#include "movepick.h" + +#include #include +#include +#include -#include "movepick.h" -#include "thread.h" +#include "bitboard.h" +#include "position.h" + +namespace Stockfish { namespace { - enum Stages { - MAIN_SEARCH, CAPTURES_INIT, GOOD_CAPTURES, KILLERS, COUNTERMOVE, QUIET_INIT, QUIET, BAD_CAPTURES, - EVASION, EVASIONS_INIT, ALL_EVASIONS, - PROBCUT, PROBCUT_INIT, PROBCUT_CAPTURES, - QSEARCH_WITH_CHECKS, QCAPTURES_1_INIT, QCAPTURES_1, QCHECKS, - QSEARCH_NO_CHECKS, QCAPTURES_2_INIT, QCAPTURES_2, - QSEARCH_RECAPTURES, QRECAPTURES - }; - - // An insertion sort, which sorts moves in descending order up to and including a given limit. - // The order of moves smaller than the limit is left unspecified. - // To keep the implementation simple, *begin is always included in the list of sorted moves. - void partial_insertion_sort(ExtMove* begin, ExtMove* end, int limit) - { - for (ExtMove *sortedEnd = begin + 1, *p = begin + 1; p < end; ++p) +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); + *p = *++sortedEnd; + for (q = sortedEnd; q != begin && *(q - 1) < tmp; --q) + *q = *(q - 1); *q = tmp; - ++sortedEnd; } - } - - // 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; - } - -} // namespace - +} -/// 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 + + +// 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, + Move cm, + const Move* killers) : + pos(p), + mainHistory(mh), + captureHistory(cph), + continuationHistory(ch), + 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)); +} -MovePicker::MovePicker(const Position& p, Move ttm, Depth d, Search::Stack* s) - : pos(p), ss(s), depth(d) { +// Constructor for quiescence search +MovePicker::MovePicker(const Position& p, + Move ttm, + Depth d, + const ButterflyHistory* mh, + const CapturePieceToHistory* cph, + const PieceToHistory** ch, + Square rs) : + pos(p), + mainHistory(mh), + captureHistory(cph), + continuationHistory(ch), + ttMove(ttm), + recaptureSquare(rs), + depth(d) { + assert(d <= 0); + + stage = (pos.checkers() ? EVASION_TT : QSEARCH_TT) + !(ttm && pos.pseudo_legal(ttm)); +} - assert(d > DEPTH_ZERO); +// 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)); +} - Square prevSq = to_sq((ss-1)->currentMove); - countermove = pos.this_thread()->counterMoves[pos.piece_on(prevSq)][prevSq]; +// 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() { + + static_assert(Type == CAPTURES || Type == QUIETS || Type == EVASIONS, "Wrong type"); + + [[maybe_unused]] Bitboard threatenedByPawn, threatenedByMinor, threatenedByRook, + threatenedPieces; + if constexpr (Type == QUIETS) + { + Color us = pos.side_to_move(); + + threatenedByPawn = pos.attacks_by(~us); + threatenedByMinor = + pos.attacks_by(~us) | pos.attacks_by(~us) | threatenedByPawn; + threatenedByRook = pos.attacks_by(~us) | threatenedByMinor; + + // 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); + } + + 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 * (*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; + } - stage = pos.checkers() ? EVASION : MAIN_SEARCH; - ttMove = ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE; - stage += (ttMove == MOVE_NONE); + 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)]; + } } -MovePicker::MovePicker(const Position& p, Move ttm, Depth d, Square s) - : pos(p) { +// Returns the next move satisfying a predicate function. +// It never returns the TT move. +template +Move MovePicker::select(Pred filter) { - assert(d <= DEPTH_ZERO); + while (cur < endMoves) + { + if constexpr (T == Best) + std::swap(*cur, *std::max_element(cur, endMoves)); - if (pos.checkers()) - stage = EVASION; + if (*cur != ttMove && filter()) + return *cur++; - else if (d > DEPTH_QS_NO_CHECKS) - stage = QSEARCH_WITH_CHECKS; + cur++; + } + return MOVE_NONE; +} - else if (d > DEPTH_QS_RECAPTURES) - stage = QSEARCH_NO_CHECKS; +// 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) { - else - { - stage = QSEARCH_RECAPTURES; - recaptureSquare = s; - return; - } +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); - ttMove = ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE; - stage += (ttMove == MOVE_NONE); -} + score(); + partial_insertion_sort(cur, endMoves, -3000 * depth); + } -MovePicker::MovePicker(const Position& p, Move ttm, Value th) - : pos(p), threshold(th) { + ++stage; + [[fallthrough]]; - assert(!pos.checkers()); + case QUIET : + if (!skipQuiets && select([&]() { + return *cur != refutations[0].move && *cur != refutations[1].move + && *cur != refutations[2].move; + })) + return *(cur - 1); - stage = PROBCUT; + // Prepare the pointers to loop over the bad captures + cur = moves; + endMoves = endBadCaptures; - // In ProbCut we generate captures with SEE higher than or equal to the given threshold - ttMove = ttm - && pos.pseudo_legal(ttm) - && pos.capture(ttm) - && pos.see_ge(ttm, threshold)? ttm : MOVE_NONE; + ++stage; + [[fallthrough]]; - stage += (ttMove == MOVE_NONE); -} + case BAD_CAPTURE : + return select([]() { return true; }); + case EVASION_INIT : + cur = moves; + endMoves = generate(pos, 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 the 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))); -} - -template<> -void MovePicker::score() { + score(); + ++stage; + [[fallthrough]]; - const HistoryStats& history = pos.this_thread()->history; + case EVASION : + return select([]() { return true; }); - const CounterMoveStats& cmh = *(ss-1)->counterMoves; - const CounterMoveStats& fmh = *(ss-2)->counterMoves; - const CounterMoveStats& fm2 = *(ss-4)->counterMoves; + case PROBCUT : + return select([&]() { return pos.see_ge(*cur, threshold); }); - Color c = pos.side_to_move(); + case QCAPTURE : + if (select( + [&]() { return depth > DEPTH_QS_RECAPTURES || to_sq(*cur) == recaptureSquare; })) + return *(cur - 1); - for (auto& m : *this) - m.value = cmh[pos.moved_piece(m)][to_sq(m)] - + fmh[pos.moved_piece(m)][to_sq(m)] - + fm2[pos.moved_piece(m)][to_sq(m)] - + history.get(c, m); -} + // If we did not find any move and we do not try checks, we have finished + if (depth != DEPTH_QS_CHECKS) + return MOVE_NONE; -template<> -void MovePicker::score() { - // Try captures ordered by MVV/LVA, then non-captures ordered by stats heuristics - const HistoryStats& history = pos.this_thread()->history; - Color c = pos.side_to_move(); - - for (auto& m : *this) - 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.get(c, m); -} + ++stage; + [[fallthrough]]; + case QCHECK_INIT : + cur = moves; + endMoves = generate(pos, cur); -/// 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. + ++stage; + [[fallthrough]]; -Move MovePicker::next_move(bool skipQuiets) { + case QCHECK : + return select([]() { return true; }); + } - Move move; - - switch (stage) { - - case MAIN_SEARCH: case EVASION: case QSEARCH_WITH_CHECKS: - case QSEARCH_NO_CHECKS: case PROBCUT: - ++stage; - return ttMove; - - case CAPTURES_INIT: - endBadCaptures = cur = moves; - endMoves = generate(pos, cur); - score(); - ++stage; - - case GOOD_CAPTURES: - while (cur < endMoves) - { - move = pick_best(cur++, endMoves); - if (move != ttMove) - { - if (pos.see_ge(move, VALUE_ZERO)) - return move; - - // Losing capture, move it to the beginning of the array - *endBadCaptures++ = move; - } - } - - ++stage; - move = ss->killers[0]; // First killer move - if ( move != MOVE_NONE - && move != ttMove - && pos.pseudo_legal(move) - && !pos.capture(move)) - return move; - - case KILLERS: - ++stage; - move = ss->killers[1]; // Second killer move - if ( move != MOVE_NONE - && move != ttMove - && pos.pseudo_legal(move) - && !pos.capture(move)) - return move; - - case COUNTERMOVE: - ++stage; - move = countermove; - if ( move != MOVE_NONE - && move != ttMove - && move != ss->killers[0] - && move != ss->killers[1] - && pos.pseudo_legal(move) - && !pos.capture(move)) - return move; - - case QUIET_INIT: - cur = endBadCaptures; - endMoves = generate(pos, cur); - score(); - - partial_insertion_sort(cur, endMoves, -4000 * depth / ONE_PLY); - ++stage; - - case QUIET: - while ( cur < endMoves - && (!skipQuiets || cur->value >= VALUE_ZERO)) - { - move = *cur++; - - if ( move != ttMove - && move != ss->killers[0] - && move != ss->killers[1] - && move != countermove) - return move; - } - ++stage; - cur = moves; // Point to beginning of bad captures - - case BAD_CAPTURES: - if (cur < endBadCaptures) - return *cur++; - break; - - case EVASIONS_INIT: - cur = moves; - endMoves = generate(pos, cur); - score(); - ++stage; - - case ALL_EVASIONS: - while (cur < endMoves) - { - move = pick_best(cur++, endMoves); - if (move != ttMove) - return move; - } - break; - - case PROBCUT_INIT: - cur = moves; - endMoves = generate(pos, cur); - score(); - ++stage; - - case PROBCUT_CAPTURES: - while (cur < endMoves) - { - move = pick_best(cur++, endMoves); - if ( move != ttMove - && pos.see_ge(move, threshold)) - return move; - } - break; - - case QCAPTURES_1_INIT: case QCAPTURES_2_INIT: - cur = moves; - endMoves = generate(pos, cur); - score(); - ++stage; - - case QCAPTURES_1: case QCAPTURES_2: - while (cur < endMoves) - { - move = pick_best(cur++, endMoves); - if (move != ttMove) - return move; - } - if (stage == QCAPTURES_2) - break; - cur = moves; - endMoves = generate(pos, cur); - ++stage; - - case QCHECKS: - while (cur < endMoves) - { - move = cur++->move; - if (move != ttMove) - return move; - } - break; - - case QSEARCH_RECAPTURES: - cur = moves; - endMoves = generate(pos, cur); - score(); - ++stage; - - case QRECAPTURES: - while (cur < endMoves) - { - move = pick_best(cur++, endMoves); - if (to_sq(move) == recaptureSquare) - return move; - } - break; - - default: - assert(false); - } - - return MOVE_NONE; + assert(false); + return MOVE_NONE; // Silence warning } + +} // namespace Stockfish