X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fmovepick.cpp;h=694b9222fe573945c826e627865e6b4d5565f58c;hb=HEAD;hp=20681108c0bd7ca8e3db1c94254dcd3b10d96236;hpb=40ad5194aa08aa8baaa9c6b8625b17fea73a8074;p=stockfish diff --git a/src/movepick.cpp b/src/movepick.cpp index 20681108..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) 2008-2010 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 @@ -18,343 +16,351 @@ along with this program. If not, see . */ +#include "movepick.h" -//// -//// Includes -//// - +#include #include +#include +#include -#include "history.h" -#include "movegen.h" -#include "movepick.h" -#include "search.h" -#include "value.h" - +#include "bitboard.h" +#include "position.h" -//// -//// Local definitions -//// +namespace Stockfish { namespace { - enum MovegenPhase { - PH_TT_MOVES, // Transposition table move and mate killer - PH_GOOD_CAPTURES, // Queen promotions and captures with SEE values >= 0 - PH_KILLERS, // Killer moves from the current ply - PH_NONCAPTURES, // Non-captures and underpromotions - PH_BAD_CAPTURES, // Queen promotions and captures with SEE values < 0 - PH_EVASIONS, // Check evasions - PH_QCAPTURES, // Captures in quiescence search - PH_QCHECKS, // Non-capture checks in quiescence search - PH_STOP - }; - - CACHE_LINE_ALIGNMENT - const uint8_t MainSearchPhaseTable[] = { PH_TT_MOVES, PH_GOOD_CAPTURES, PH_KILLERS, PH_NONCAPTURES, PH_BAD_CAPTURES, PH_STOP}; - const uint8_t EvasionsPhaseTable[] = { PH_TT_MOVES, PH_EVASIONS, PH_STOP}; - const uint8_t QsearchWithChecksPhaseTable[] = { PH_TT_MOVES, PH_QCAPTURES, PH_QCHECKS, PH_STOP}; - const uint8_t QsearchWithoutChecksPhaseTable[] = { PH_TT_MOVES, PH_QCAPTURES, PH_STOP}; +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; + } } +} // 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)); +} -//// -//// Functions -//// - - -/// Constructor for the MovePicker class. Apart from the position for which -/// it is asked to pick legal moves, MovePicker also wants some 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 about how important good -/// move ordering is at the current node. - -MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const History& h, - SearchStack* ss, Value beta) : pos(p), H(h) { - int searchTT = ttm; - ttMoves[0].move = ttm; - badCaptureThreshold = 0; - lastBadCapture = badCaptures; - - pinned = p.pinned_pieces(pos.side_to_move()); - - if (ss && !p.is_check()) - { - ttMoves[1].move = (ss->mateKiller == ttm) ? MOVE_NONE : ss->mateKiller; - searchTT |= ttMoves[1].move; - killers[0].move = ss->killers[0]; - killers[1].move = ss->killers[1]; - } else - ttMoves[1].move = killers[0].move = killers[1].move = MOVE_NONE; - - if (p.is_check()) - phasePtr = EvasionsPhaseTable; - else if (d > Depth(0)) - { - // Consider sligtly negative captures as good if at low - // depth and far from beta. - if (ss && ss->eval < beta - PawnValueMidgame && d < 3 * OnePly) - badCaptureThreshold = -PawnValueMidgame; - - phasePtr = MainSearchPhaseTable; - } - else if (d == Depth(0)) - phasePtr = QsearchWithChecksPhaseTable; - else - { - phasePtr = QsearchWithoutChecksPhaseTable; - - // Skip TT move if is not a capture or a promotion, this avoids - // qsearch tree explosion due to a possible perpetual check or - // similar rare cases when TT table is full. - if (ttm != MOVE_NONE && !pos.move_is_capture_or_promotion(ttm)) - searchTT = ttMoves[0].move = MOVE_NONE; - } - - phasePtr += int(!searchTT) - 1; - go_next_phase(); +// 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)); } +// 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)); +} -/// MovePicker::go_next_phase() generates, scores and sorts the next bunch -/// of moves when there are no more moves to try for the current phase. - -void MovePicker::go_next_phase() { - - curMove = moves; - phase = *(++phasePtr); - switch (phase) { - - case PH_TT_MOVES: - curMove = ttMoves; - lastMove = curMove + 2; - return; - - case PH_GOOD_CAPTURES: - lastMove = generate_captures(pos, moves); - score_captures(); - return; - - case PH_KILLERS: - curMove = killers; - lastMove = curMove + 2; - return; - - case PH_NONCAPTURES: - lastMove = generate_noncaptures(pos, moves); - score_noncaptures(); - sort_moves(moves, lastMove, &lastGoodNonCapture); - return; - - case PH_BAD_CAPTURES: - // Bad captures SEE value is already calculated so just sort them - // to get SEE move ordering. - curMove = badCaptures; - lastMove = lastBadCapture; - return; - - case PH_EVASIONS: - assert(pos.is_check()); - lastMove = generate_evasions(pos, moves); - score_evasions_or_checks(); - return; - - case PH_QCAPTURES: - lastMove = generate_captures(pos, moves); - score_captures(); - return; - - case PH_QCHECKS: - lastMove = generate_non_capture_checks(pos, moves); - score_evasions_or_checks(); - return; - - case PH_STOP: - lastMove = curMove + 1; // Avoids another go_next_phase() call - return; - - default: - assert(false); - return; - } +// 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 * (*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)]; + } } +// Returns the next move satisfying a predicate function. +// It never returns the TT move. +template +Move MovePicker::select(Pred filter) { -/// MovePicker::score_captures(), MovePicker::score_noncaptures() and -/// MovePicker::score_evasions() assign a numerical move ordering score -/// to each move in a move list. The moves with highest scores will be -/// picked first by get_next_move(). - -void MovePicker::score_captures() { - // Winning and equal captures in the main search are ordered by MVV/LVA. - // Suprisingly, this appears to perform slightly better than SEE based - // move ordering. The reason is probably that in a position with a winning - // capture, capturing a more valuable (but sufficiently defended) piece - // first usually doesn't hurt. The opponent will have to recapture, and - // the hanging piece will still be hanging (except in the unusual cases - // where it is possible to recapture with the hanging piece). 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 - // badCaptures[] array, but instead of doing it now we delay till when - // the move has been picked up in pick_move_from_list(), this way we save - // some SEE calls in case we get a cutoff (idea from Pablo Vazquez). - Move m; - - // Use MVV/LVA ordering - for (MoveStack* cur = moves; cur != lastMove; cur++) - { - m = cur->move; - if (move_is_promotion(m)) - cur->score = QueenValueMidgame; - else - cur->score = pos.midgame_value_of_piece_on(move_to(m)) - - pos.type_of_piece_on(move_from(m)); - } -} + while (cur < endMoves) + { + if constexpr (T == Best) + std::swap(*cur, *std::max_element(cur, endMoves)); -void MovePicker::score_noncaptures() { - // First score by history, when no history is available then use - // piece/square tables values. This seems to be better then a - // random choice when we don't have an history for any move. - Move m; - Piece piece; - Square from, to; - - for (MoveStack* cur = moves; cur != lastMove; cur++) - { - m = cur->move; - from = move_from(m); - to = move_to(m); - piece = pos.piece_on(from); - cur->score = H.move_ordering_score(piece, to); - } -} + if (*cur != ttMove && filter()) + return *cur++; -void MovePicker::score_evasions_or_checks() { - // Try good captures ordered by MVV/LVA, then non-captures if - // destination square is not under attack, ordered by history - // value, and at the end bad-captures and non-captures with a - // negative SEE. This last group is ordered by the SEE score. - Move m; - int seeScore; - - // Skip if we don't have at least two moves to order - if (lastMove < moves + 2) - return; - - for (MoveStack* cur = moves; cur != lastMove; cur++) - { - m = cur->move; - if ((seeScore = pos.see_sign(m)) < 0) - cur->score = seeScore - HistoryMax; // Be sure are at the bottom - else if (pos.move_is_capture(m)) - cur->score = pos.midgame_value_of_piece_on(move_to(m)) - - pos.type_of_piece_on(move_from(m)) + HistoryMax; - else - cur->score = H.move_ordering_score(pos.piece_on(move_from(m)), move_to(m)); - } + cur++; + } + return MOVE_NONE; } -/// MovePicker::get_next_move() is the most important method of the MovePicker -/// class. It returns a new legal move every time it is called, until there -/// are no more moves left. -/// It picks the move with the biggest score from a list of generated moves taking -/// care not to return the tt move if has already been searched previously. -/// Note that this function is not thread safe so should be lock protected by -/// caller when accessed through a shared MovePicker object. - -Move MovePicker::get_next_move() { - - Move move; - - while (true) - { - while (curMove != lastMove) - { - switch (phase) { - - case PH_TT_MOVES: - move = (curMove++)->move; - if ( move != MOVE_NONE - && move_is_legal(pos, move, pinned)) - return move; - break; - - case PH_GOOD_CAPTURES: - move = pick_best(curMove++, lastMove).move; - if ( move != ttMoves[0].move - && move != ttMoves[1].move - && pos.pl_move_is_legal(move, pinned)) - { - // Check for a non negative SEE now - int seeValue = pos.see_sign(move); - if (seeValue >= badCaptureThreshold) - return move; - - // Losing capture, move it to the badCaptures[] array, note - // that move has now been already checked for legality. - assert(int(lastBadCapture - badCaptures) < 63); - lastBadCapture->move = move; - lastBadCapture->score = seeValue; - lastBadCapture++; - } - break; - - case PH_KILLERS: - move = (curMove++)->move; - if ( move != MOVE_NONE - && move_is_legal(pos, move, pinned) - && move != ttMoves[0].move - && move != ttMoves[1].move - && !pos.move_is_capture(move)) - return move; - break; - - case PH_NONCAPTURES: - - // Sort negative scored moves only when we get there - if (curMove == lastGoodNonCapture) - insertion_sort(lastGoodNonCapture, lastMove); - - move = (curMove++)->move; - if ( move != ttMoves[0].move - && move != ttMoves[1].move - && move != killers[0].move - && move != killers[1].move - && pos.pl_move_is_legal(move, pinned)) - return move; - break; - - case PH_BAD_CAPTURES: - move = pick_best(curMove++, lastMove).move; - return move; - - case PH_EVASIONS: - case PH_QCAPTURES: - move = pick_best(curMove++, lastMove).move; - if ( move != ttMoves[0].move - && pos.pl_move_is_legal(move, pinned)) - return move; - break; - - case PH_QCHECKS: - move = (curMove++)->move; - if ( move != ttMoves[0].move - && pos.pl_move_is_legal(move, pinned)) - return move; - break; - - case PH_STOP: - return MOVE_NONE; - - default: - assert(false); - break; - } - } - go_next_phase(); - } +// 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) { + +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; }); + } + + assert(false); + return MOVE_NONE; // Silence warning } +} // namespace Stockfish