X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovepick.cpp;h=08dabe0a1eedb51af077cef8677da3a3a5938b2a;hp=c4eaa902e292e64cdea5858f4f9ae3318f07ec92;hb=e0504ab876a997321102f040ab88203cb893db12;hpb=917944e9c5324cc9659e630570e1852270b22bd4 diff --git a/src/movepick.cpp b/src/movepick.cpp index c4eaa902..08dabe0a 100644 --- a/src/movepick.cpp +++ b/src/movepick.cpp @@ -1,14 +1,14 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008-2013 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad 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 @@ -26,16 +26,15 @@ namespace { enum Stages { - MAIN_SEARCH, CAPTURES_S1, KILLERS_S1, QUIETS_1_S1, QUIETS_2_S1, BAD_CAPTURES_S1, - EVASION, EVASIONS_S2, - QSEARCH_0, CAPTURES_S3, QUIET_CHECKS_S3, - QSEARCH_1, CAPTURES_S4, - PROBCUT, CAPTURES_S5, - RECAPTURE, CAPTURES_S6, - STOP + 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 }; - // Our insertion sort, guaranteed to be stable, as is needed + // Our insertion sort, which is guaranteed to be stable, as it should be void insertion_sort(ExtMove* begin, ExtMove* end) { ExtMove tmp, *p, *q; @@ -49,338 +48,300 @@ namespace { } } - // Unary predicate used by std::partition to split positive scores from remaining - // ones so to sort separately the two sets, and with the second sort delayed. - inline bool has_positive_score(const ExtMove& ms) { return ms.score > 0; } - - // Picks and moves to the front the best move in the range [begin, end), - // it is faster than sorting all the moves in advance when moves are few, as - // normally are the possible captures. - inline ExtMove* pick_best(ExtMove* begin, ExtMove* end) + // 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; + 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 +/// 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. +/// search captures, promotions, and some checks) and how important good move +/// ordering is at the current node. -MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const HistoryStats& h, - Move* cm, Search::Stack* s) : pos(p), history(h), depth(d) { +MovePicker::MovePicker(const Position& p, Move ttm, Depth d, Search::Stack* s) + : pos(p), ss(s), depth(d) { assert(d > DEPTH_ZERO); - cur = end = moves; - endBadCaptures = moves + MAX_MOVES - 1; - countermoves = cm; - ss = s; + Square prevSq = to_sq((ss-1)->currentMove); + countermove = pos.this_thread()->counterMoves[pos.piece_on(prevSq)][prevSq]; - if (p.checkers()) - stage = EVASION; - - else - stage = MAIN_SEARCH; - - ttMove = (ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE); - end += (ttMove != MOVE_NONE); + stage = pos.checkers() ? EVASION : MAIN_SEARCH; + ttMove = ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE; + stage += (ttMove == MOVE_NONE); } -MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const HistoryStats& h, - Square sq) : pos(p), history(h), cur(moves), end(moves) { +MovePicker::MovePicker(const Position& p, Move ttm, Depth d, Square s) + : pos(p) { assert(d <= DEPTH_ZERO); - if (p.checkers()) + if (pos.checkers()) stage = EVASION; else if (d > DEPTH_QS_NO_CHECKS) - stage = QSEARCH_0; + stage = QSEARCH_WITH_CHECKS; else if (d > DEPTH_QS_RECAPTURES) - { - stage = QSEARCH_1; + stage = QSEARCH_NO_CHECKS; - // 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 && !pos.capture_or_promotion(ttm)) - ttm = MOVE_NONE; - } else { - stage = RECAPTURE; - recaptureSquare = sq; - ttm = MOVE_NONE; + stage = QSEARCH_RECAPTURES; + recaptureSquare = s; + return; } - ttMove = (ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE); - end += (ttMove != MOVE_NONE); + ttMove = ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE; + stage += (ttMove == MOVE_NONE); } -MovePicker::MovePicker(const Position& p, Move ttm, const HistoryStats& h, PieceType pt) - : pos(p), history(h), cur(moves), end(moves) { +MovePicker::MovePicker(const Position& p, Move ttm, Value th) + : pos(p), threshold(th) { assert(!pos.checkers()); stage = PROBCUT; - // In ProbCut we generate only captures better than parent's captured piece - captureThreshold = PieceValue[MG][pt]; - ttMove = (ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE); - - if (ttMove && (!pos.capture(ttMove) || pos.see(ttMove) <= captureThreshold)) - ttMove = MOVE_NONE; + // 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; - end += (ttMove != MOVE_NONE); + stage += (ttMove == MOVE_NONE); } -/// quiet_moves() returns a pointer to the beginning of moves array. It -/// is used to access already tried quiet moves when updating history. - -const ExtMove* MovePicker::quiet_moves() const { - return stage == KILLERS_S1 ? killers - : stage == QUIETS_1_S1 || stage == QUIETS_2_S1 ? moves : NULL; -} - - -/// score() assign a numerical move ordering score to each move in a move list. -/// The moves with highest scores will be picked first. +/// 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/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; - - for (ExtMove* it = moves; it != end; ++it) - { - m = it->move; - it->score = PieceValue[MG][pos.piece_on(to_sq(m))] - - type_of(pos.moved_piece(m)); - - if (type_of(m) == PROMOTION) - it->score += PieceValue[MG][promotion_type(m)] - PieceValue[MG][PAWN]; - - else if (type_of(m) == ENPASSANT) - it->score += PieceValue[MG][PAWN]; - } + // 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() { - Move m; + const FromToStats& fromTo = pos.this_thread()->fromTo; - for (ExtMove* it = moves; it != end; ++it) - { - m = it->move; - it->score = history[pos.moved_piece(m)][to_sq(m)]; - } + const CounterMoveStats* cmh = (ss-1)->counterMoves; + const CounterMoveStats* fmh = (ss-2)->counterMoves; + const CounterMoveStats* fmh2 = (ss-4)->counterMoves; + + Color c = pos.side_to_move(); + + for (auto& m : *this) + m.value = (cmh ? (*cmh)[pos.moved_piece(m)][to_sq(m)] : VALUE_ZERO) + + (fmh ? (*fmh)[pos.moved_piece(m)][to_sq(m)] : VALUE_ZERO) + + (fmh2 ? (*fmh2)[pos.moved_piece(m)][to_sq(m)] : VALUE_ZERO) + + fromTo.get(c, m); } template<> void MovePicker::score() { - // Try good captures ordered by MVV/LVA, then non-captures if destination square - // is not under attack, ordered by history value, then bad-captures and quiet - // moves with a negative SEE. This last group is ordered by the SEE score. - Move m; - int seeScore; - - for (ExtMove* it = moves; it != end; ++it) - { - m = it->move; - if ((seeScore = pos.see_sign(m)) < 0) - it->score = seeScore - HistoryStats::Max; // At the bottom - - else if (pos.capture(m)) - it->score = PieceValue[MG][pos.piece_on(to_sq(m))] - - type_of(pos.moved_piece(m)) + HistoryStats::Max; + // Try captures ordered by MVV/LVA, then non-captures ordered by stats heuristics + const FromToStats& fromTo = pos.this_thread()->fromTo; + 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))) + FromToStats::Max; else - it->score = history[pos.moved_piece(m)][to_sq(m)]; - } -} - - -/// generate_next() generates, scores and sorts the next bunch of moves, when -/// there are no more moves to try for the current phase. - -void MovePicker::generate_next() { - - cur = moves; - - switch (++stage) { - - case CAPTURES_S1: case CAPTURES_S3: case CAPTURES_S4: case CAPTURES_S5: case CAPTURES_S6: - end = generate(pos, moves); - score(); - return; - - case KILLERS_S1: - cur = killers; - end = cur + 2; - - killers[0].move = ss->killers[0]; - killers[1].move = ss->killers[1]; - killers[2].move = killers[3].move = MOVE_NONE; - - // Be sure countermoves are different from killers - for (int i = 0; i < 2; ++i) - if (countermoves[i] != cur->move && countermoves[i] != (cur+1)->move) - (end++)->move = countermoves[i]; - - if (countermoves[1] && countermoves[1] == countermoves[0]) // Due to SMP races - killers[3].move = MOVE_NONE; - - return; - - case QUIETS_1_S1: - endQuiets = end = generate(pos, moves); - score(); - end = std::partition(cur, end, has_positive_score); - insertion_sort(cur, end); - return; - - case QUIETS_2_S1: - cur = end; - end = endQuiets; - if (depth >= 3 * ONE_PLY) - insertion_sort(cur, end); - return; - - case BAD_CAPTURES_S1: - // Just pick them in reverse order to get MVV/LVA ordering - cur = moves + MAX_MOVES - 1; - end = endBadCaptures; - return; - - case EVASIONS_S2: - end = generate(pos, moves); - if (end > moves + 1) - score(); - return; - - case QUIET_CHECKS_S3: - end = generate(pos, moves); - return; - - case EVASION: case QSEARCH_0: case QSEARCH_1: case PROBCUT: case RECAPTURE: - stage = STOP; - case STOP: - end = cur + 1; // Avoid another next_phase() call - return; - - default: - assert(false); - } + m.value = fromTo.get(c, m); } /// next_move() is the most important method of the MovePicker class. It returns -/// a new pseudo legal move every time 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 returning the ttMove if has already been searched previously. -template<> -Move MovePicker::next_move() { +/// 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 == end) - generate_next(); + switch (stage) { - switch (stage) { + case MAIN_SEARCH: case EVASION: case QSEARCH_WITH_CHECKS: + case QSEARCH_NO_CHECKS: case PROBCUT: + ++stage; + return ttMove; - case MAIN_SEARCH: case EVASION: case QSEARCH_0: case QSEARCH_1: case PROBCUT: - ++cur; - return ttMove; + case CAPTURES_INIT: + endBadCaptures = cur = moves; + endMoves = generate(pos, cur); + score(); + ++stage; - case CAPTURES_S1: - move = pick_best(cur++, end)->move; + case GOOD_CAPTURES: + while (cur < endMoves) + { + move = pick_best(cur++, endMoves); if (move != ttMove) { - if (pos.see_sign(move) >= 0) + if (pos.see_ge(move, VALUE_ZERO)) return move; - // Losing capture, move it to the tail of the array - (endBadCaptures--)->move = move; + // Losing capture, move it to the beginning of the array + *endBadCaptures++ = move; } - break; - - case KILLERS_S1: - move = (cur++)->move; - if ( move != MOVE_NONE - && pos.pseudo_legal(move) - && move != ttMove - && !pos.capture(move)) - return move; - break; + } - case QUIETS_1_S1: case QUIETS_2_S1: - move = (cur++)->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(); + if (depth < 3 * ONE_PLY) + { + ExtMove* goodQuiet = std::partition(cur, endMoves, [](const ExtMove& m) + { return m.value > VALUE_ZERO; }); + insertion_sort(cur, goodQuiet); + } else + insertion_sort(cur, endMoves); + ++stage; + + case QUIET: + while (cur < endMoves) + { + move = *cur++; if ( move != ttMove - && move != killers[0].move - && move != killers[1].move - && move != killers[2].move - && move != killers[3].move) + && move != ss->killers[0] + && move != ss->killers[1] + && move != countermove) return move; - break; - - case BAD_CAPTURES_S1: - return (cur--)->move; - - case EVASIONS_S2: case CAPTURES_S3: case CAPTURES_S4: - move = pick_best(cur++, end)->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; + } + break; - case CAPTURES_S5: - move = pick_best(cur++, end)->move; - if (move != ttMove && pos.see(move) > captureThreshold) - return move; - break; + case PROBCUT_INIT: + cur = moves; + endMoves = generate(pos, cur); + score(); + ++stage; - case CAPTURES_S6: - move = pick_best(cur++, end)->move; - if (to_sq(move) == recaptureSquare) + case PROBCUT_CAPTURES: + while (cur < endMoves) + { + move = pick_best(cur++, endMoves); + if ( move != ttMove + && pos.see_ge(move, threshold)) return move; - break; + } + break; + + case QCAPTURES_1_INIT: case QCAPTURES_2_INIT: + cur = moves; + endMoves = generate(pos, cur); + score(); + ++stage; - case QUIET_CHECKS_S3: - move = (cur++)->move; + 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 STOP: - return MOVE_NONE; + case QSEARCH_RECAPTURES: + cur = moves; + endMoves = generate(pos, cur); + score(); + ++stage; - default: - assert(false); + case QRECAPTURES: + while (cur < endMoves) + { + move = pick_best(cur++, endMoves); + if (to_sq(move) == recaptureSquare) + return move; } - } -} + break; + default: + assert(false); + } -/// Version of next_move() to use at split point nodes where the move is grabbed -/// from the split point's shared MovePicker object. This function is not thread -/// safe so must be lock protected by the caller. -template<> -Move MovePicker::next_move() { return ss->splitPoint->movePicker->next_move(); } + return MOVE_NONE; +}