X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovepick.cpp;h=c52384947a6381008b661b5d70d5c8496ea34f9b;hp=b03295ddb86f987b9ad859bb447af48d939a339f;hb=8fb45caadef67fb2ccc27857c15ade987d9f5e2f;hpb=1efc19ade012002afb1839326c74feb157308144 diff --git a/src/movepick.cpp b/src/movepick.cpp index b03295dd..c5238494 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) 2008-2014 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 +26,16 @@ 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, + 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 (and also needed) to be stable + // Our insertion sort, which is guaranteed to be stable, as it should be void insertion_sort(ExtMove* begin, ExtMove* end) { ExtMove tmp, *p, *q; @@ -49,243 +49,183 @@ namespace { } } - // Unary predicate used by std::partition to split positive values from remaining - // ones so as to sort the two sets separately, with the second sort delayed. - inline bool has_positive_value(const ExtMove& ms) { return ms.value > 0; } - - // Picks 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. 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 /// moves to return (in the quiescence search, for instance, we only want to -/// search captures, promotions and some checks) and how important good move +/// 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, Move* fm, Search::Stack* s) : pos(p), history(h), depth(d) { + const CounterMoveStats& cmh, const CounterMoveStats& fmh, + Move cm, Search::Stack* s) + : pos(p), history(h), counterMoveHistory(&cmh), + followupMoveHistory(&fmh), ss(s), countermove(cm), depth(d) { assert(d > DEPTH_ZERO); - cur = end = moves; - endBadCaptures = moves + MAX_MOVES - 1; - countermoves = cm; - followupmoves = fm; - ss = s; - - 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; + endMoves += (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, + const HistoryStats& h, Square s) + : pos(p), history(h) { 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_WITHOUT_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; + recaptureSquare = s; ttm = MOVE_NONE; } - ttMove = (ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE); - end += (ttMove != MOVE_NONE); + ttMove = ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE; + endMoves += (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, const HistoryStats& h, Value th) + : pos(p), history(h), threshold(th) { assert(!pos.checkers()); stage = PROBCUT; - // In ProbCut we generate only captures that are better than the parent's - // captured piece. - captureThreshold = PieceValue[MG][pt]; - ttMove = (ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE); + // 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; - if (ttMove && (!pos.capture(ttMove) || pos.see(ttMove) <= captureThreshold)) - ttMove = MOVE_NONE; - - end += (ttMove != MOVE_NONE); + endMoves += (ttMove != MOVE_NONE); } -/// score() assign a numerical value to each move in a move list. The moves with +/// 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 the + // 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 in pick_move_from_list(). This way we save some SEE - // calls in case we get a cutoff. - Move m; - - for (ExtMove* it = moves; it != end; ++it) - { - m = it->move; - it->value = PieceValue[MG][pos.piece_on(to_sq(m))] - - Value(type_of(pos.moved_piece(m))); - - if (type_of(m) == PROMOTION) - it->value += PieceValue[MG][promotion_type(m)] - PieceValue[MG][PAWN]; - - else if (type_of(m) == ENPASSANT) - it->value += PieceValue[MG][PAWN]; - } + // 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; - - for (ExtMove* it = moves; it != end; ++it) - { - m = it->move; - it->value = history[pos.moved_piece(m)][to_sq(m)]; - } + for (auto& m : *this) + m.value = history[pos.moved_piece(m)][to_sq(m)] + + (*counterMoveHistory )[pos.moved_piece(m)][to_sq(m)] + + (*followupMoveHistory)[pos.moved_piece(m)][to_sq(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 value. - Move m; + // Try winning and equal 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 (ExtMove* it = moves; it != end; ++it) - { - m = it->move; + for (auto& m : *this) if ((see = pos.see_sign(m)) < VALUE_ZERO) - it->value = see - HistoryStats::Max; // At the bottom + m.value = see - HistoryStats::Max; // At the bottom else if (pos.capture(m)) - it->value = PieceValue[MG][pos.piece_on(to_sq(m))] - - Value(type_of(pos.moved_piece(m))) + HistoryStats::Max; + m.value = PieceValue[MG][pos.piece_on(to_sq(m))] + - Value(type_of(pos.moved_piece(m))) + HistoryStats::Max; else - it->value = history[pos.moved_piece(m)][to_sq(m)]; - } + m.value = history[pos.moved_piece(m)][to_sq(m)]; } -/// generate_next_stage() generates, scores and sorts the next bunch of moves, +/// 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 CAPTURES_S1: case CAPTURES_S3: case CAPTURES_S4: case CAPTURES_S5: case CAPTURES_S6: - end = generate(pos, moves); + case GOOD_CAPTURES: case QCAPTURES_1: case QCAPTURES_2: + case PROBCUT_CAPTURES: case RECAPTURES: + endMoves = generate(pos, moves); score(); - return; + break; - case KILLERS_S1: + case KILLERS: + killers[0] = ss->killers[0]; + killers[1] = ss->killers[1]; + killers[2] = countermove; 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; - killers[4].move = killers[5].move = MOVE_NONE; - - // Please note that following code is racy and could yield to rare (less - // than 1 out of a million) duplicated entries in SMP case. This is harmless. - - // Be sure countermoves are different from killers - for (int i = 0; i < 2; ++i) - if ( countermoves[i] != (cur+0)->move - && countermoves[i] != (cur+1)->move) - (end++)->move = countermoves[i]; - - // Be sure followupmoves are different from killers and countermoves - for (int i = 0; i < 2; ++i) - if ( followupmoves[i] != (cur+0)->move - && followupmoves[i] != (cur+1)->move - && followupmoves[i] != (cur+2)->move - && followupmoves[i] != (cur+3)->move) - (end++)->move = followupmoves[i]; - return; - - case QUIETS_1_S1: - endQuiets = end = generate(pos, moves); + endMoves = cur + 2 + (countermove != killers[0] && countermove != killers[1]); + break; + + case GOOD_QUIETS: + endQuiets = endMoves = generate(pos, moves); score(); - end = std::partition(cur, end, has_positive_value); - insertion_sort(cur, end); - return; + endMoves = std::partition(cur, endMoves, [](const ExtMove& m) { return m.value > VALUE_ZERO; }); + insertion_sort(cur, endMoves); + break; - case QUIETS_2_S1: - cur = end; - end = endQuiets; + case BAD_QUIETS: + cur = endMoves; + endMoves = endQuiets; if (depth >= 3 * ONE_PLY) - insertion_sort(cur, end); - return; + insertion_sort(cur, endMoves); + break; - case BAD_CAPTURES_S1: - // Just pick them in reverse order to get MVV/LVA ordering + case BAD_CAPTURES: + // Just pick them in reverse order to get correct ordering cur = moves + MAX_MOVES - 1; - end = endBadCaptures; - return; + endMoves = endBadCaptures; + break; - case EVASIONS_S2: - end = generate(pos, moves); - if (end > moves + 1) + case ALL_EVASIONS: + endMoves = generate(pos, moves); + if (endMoves - moves > 1) score(); - return; + break; - case QUIET_CHECKS_S3: - end = generate(pos, moves); - return; + case CHECKS: + endMoves = generate(pos, moves); + break; - case EVASION: case QSEARCH_0: case QSEARCH_1: case PROBCUT: case RECAPTURE: + case EVASION: case QSEARCH_WITH_CHECKS: case QSEARCH_WITHOUT_CHECKS: + case PROBCUT: case RECAPTURE: case STOP: stage = STOP; - case STOP: - end = cur + 1; // Avoid another next_phase() call - return; + break; default: assert(false); @@ -297,78 +237,76 @@ void MovePicker::generate_next_stage() { /// 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. -template<> -Move MovePicker::next_move() { + +Move MovePicker::next_move() { Move move; while (true) { - while (cur == end) + while (cur == endMoves && stage != STOP) generate_next_stage(); switch (stage) { - case MAIN_SEARCH: case EVASION: case QSEARCH_0: case QSEARCH_1: case PROBCUT: + case MAIN_SEARCH: case EVASION: case QSEARCH_WITH_CHECKS: + case QSEARCH_WITHOUT_CHECKS: case PROBCUT: ++cur; return ttMove; - case CAPTURES_S1: - move = pick_best(cur++, end)->move; + 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 = move; + *endBadCaptures-- = move; } break; - case KILLERS_S1: - move = (cur++)->move; + case KILLERS: + move = *cur++; if ( move != MOVE_NONE - && pos.pseudo_legal(move) && move != ttMove + && pos.pseudo_legal(move) && !pos.capture(move)) return move; break; - case QUIETS_1_S1: case QUIETS_2_S1: - move = (cur++)->move; + case GOOD_QUIETS: case BAD_QUIETS: + move = *cur++; if ( move != ttMove - && move != killers[0].move - && move != killers[1].move - && move != killers[2].move - && move != killers[3].move - && move != killers[4].move - && move != killers[5].move) + && move != killers[0] + && move != killers[1] + && move != killers[2]) return move; break; - case BAD_CAPTURES_S1: - return (cur--)->move; + case BAD_CAPTURES: + return *cur--; - case EVASIONS_S2: case CAPTURES_S3: case CAPTURES_S4: - move = pick_best(cur++, end)->move; + case ALL_EVASIONS: case QCAPTURES_1: case QCAPTURES_2: + move = pick_best(cur++, endMoves); if (move != ttMove) return move; break; - case CAPTURES_S5: - move = pick_best(cur++, end)->move; - if (move != ttMove && pos.see(move) > captureThreshold) + case PROBCUT_CAPTURES: + move = pick_best(cur++, endMoves); + if (move != ttMove && pos.see(move) > threshold) return move; break; - case CAPTURES_S6: - move = pick_best(cur++, end)->move; + case RECAPTURES: + move = pick_best(cur++, endMoves); if (to_sq(move) == recaptureSquare) return move; break; - case QUIET_CHECKS_S3: - move = (cur++)->move; + case CHECKS: + move = *cur++; if (move != ttMove) return move; break; @@ -381,10 +319,3 @@ Move MovePicker::next_move() { } } } - - -/// 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(); }