X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovepick.cpp;h=4971b304ba0c12f550151564ba0fe5c038c5c61c;hp=94ceedbfd4cf4a37cca4e4db6104a982ce60576f;hb=ace8e951d70c2986a0af83effcc0d2b2312d29e3;hpb=c1d3bd2dbaa5bd29c28551baafe526a977e1f733 diff --git a/src/movepick.cpp b/src/movepick.cpp index 94ceedbf..4971b304 100644 --- a/src/movepick.cpp +++ b/src/movepick.cpp @@ -2,13 +2,13 @@ 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) 2015-2016 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 @@ -26,7 +26,7 @@ namespace { enum Stages { - MAIN_SEARCH, GOOD_CAPTURES, KILLERS, GOOD_QUIETS, BAD_QUIETS, BAD_CAPTURES, + MAIN_SEARCH, GOOD_CAPTURES, KILLERS, QUIET, BAD_CAPTURES, EVASION, ALL_EVASIONS, QSEARCH_WITH_CHECKS, QCAPTURES_1, CHECKS, QSEARCH_WITHOUT_CHECKS, QCAPTURES_2, @@ -51,7 +51,7 @@ namespace { // 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. + // are few moves, e.g., the possible captures. Move pick_best(ExtMove* begin, ExtMove* end) { std::swap(*begin, *std::max_element(begin, end)); @@ -64,30 +64,24 @@ 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, const CounterMovesHistoryStats& cmh, - Move cm, Search::Stack* s) : pos(p), history(h), counterMovesHistory(cmh), depth(d) { +MovePicker::MovePicker(const Position& p, Move ttm, Depth d, Search::Stack* s) + : pos(p), ss(s), depth(d) { assert(d > DEPTH_ZERO); - endBadCaptures = moves + MAX_MOVES - 1; - countermove = cm; - ss = s; - - if (pos.checkers()) - stage = EVASION; - - else - stage = MAIN_SEARCH; + Square prevSq = to_sq((ss-1)->currentMove); + countermove = pos.this_thread()->counterMoves[pos.piece_on(prevSq)][prevSq]; - ttMove = (ttm && pos.pseudo_legal(ttm) ? ttm : 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, const CounterMovesHistoryStats& cmh, - Square s) : pos(p), history(h), counterMovesHistory(cmh) { +MovePicker::MovePicker(const Position& p, Move ttm, Depth d, Square s) + : pos(p) { assert(d <= DEPTH_ZERO); @@ -107,67 +101,71 @@ MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const HistoryStats& ttm = MOVE_NONE; } - ttMove = (ttm && pos.pseudo_legal(ttm) ? ttm : 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, const CounterMovesHistoryStats& cmh, PieceType pt) - : pos(p), history(h), counterMovesHistory(cmh) { +MovePicker::MovePicker(const Position& p, Move ttm, Value th) + : pos(p), 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); - - if (ttMove && (!pos.capture(ttMove) || pos.see(ttMove) <= captureThreshold)) - ttMove = 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; 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. - // 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 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. + // 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))] - - 200 * relative_rank(pos.side_to_move(), to_sq(m)); + - Value(200 * relative_rank(pos.side_to_move(), to_sq(m))); } template<> void MovePicker::score() { - Square prevSq = to_sq((ss-1)->currentMove); - const HistoryStats& cmh = counterMovesHistory[pos.piece_on(prevSq)][prevSq]; + const HistoryStats& history = pos.this_thread()->history; + const FromToStats& fromTo = pos.this_thread()->fromTo; + + const CounterMoveStats* cm = (ss-1)->counterMoves; + const CounterMoveStats* fm = (ss-2)->counterMoves; + const CounterMoveStats* f2 = (ss-4)->counterMoves; + + Color c = pos.side_to_move(); for (auto& m : *this) - m.value = history[pos.moved_piece(m)][to_sq(m)] - + cmh[pos.moved_piece(m)][to_sq(m)] * 3; + m.value = history[pos.moved_piece(m)][to_sq(m)] + + (cm ? (*cm)[pos.moved_piece(m)][to_sq(m)] : VALUE_ZERO) + + (fm ? (*fm)[pos.moved_piece(m)][to_sq(m)] : VALUE_ZERO) + + (f2 ? (*f2)[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 value. + // 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. + const HistoryStats& history = pos.this_thread()->history; + const FromToStats& fromTo = pos.this_thread()->fromTo; + Color c = pos.side_to_move(); Value see; for (auto& m : *this) @@ -178,15 +176,17 @@ void MovePicker::score() { 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)]; + m.value = history[pos.moved_piece(m)][to_sq(m)] + fromTo.get(c, 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) { @@ -198,35 +198,27 @@ void MovePicker::generate_next_stage() { break; case KILLERS: - cur = killers; - endMoves = cur + 2; - killers[0] = ss->killers[0]; killers[1] = ss->killers[1]; - killers[2].move = MOVE_NONE; - - // Be sure countermoves are different from killers - if ( countermove != killers[0] - && countermove != killers[1]) - *endMoves++ = countermove; + killers[2] = countermove; + cur = killers; + endMoves = cur + 2 + (countermove != killers[0] && countermove != killers[1]); break; - case GOOD_QUIETS: - endQuiets = endMoves = generate(pos, moves); + case QUIET: + 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) + 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); break; case BAD_CAPTURES: - // Just pick them in reverse order to get MVV/LVA ordering + // Just pick them in reverse order to get correct ordering cur = moves + MAX_MOVES - 1; endMoves = endBadCaptures; break; @@ -242,12 +234,8 @@ void MovePicker::generate_next_stage() { break; case EVASION: case QSEARCH_WITH_CHECKS: case QSEARCH_WITHOUT_CHECKS: - case PROBCUT: case RECAPTURE: + case PROBCUT: case RECAPTURE: case STOP: stage = STOP; - /* Fall through */ - - case STOP: - endMoves = cur + 1; // Avoid another generate_next_stage() call break; default: @@ -255,19 +243,24 @@ void MovePicker::generate_next_stage() { } } +int MovePicker::see_sign() const +{ + return stage == GOOD_CAPTURES ? 1 + : stage == BAD_CAPTURES ? -1 : 0; +} /// 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. -template<> -Move MovePicker::next_move() { + +Move MovePicker::next_move() { Move move; while (true) { - while (cur == endMoves) + while (cur == endMoves && stage != STOP) generate_next_stage(); switch (stage) { @@ -298,7 +291,7 @@ Move MovePicker::next_move() { return move; break; - case GOOD_QUIETS: case BAD_QUIETS: + case QUIET: move = *cur++; if ( move != ttMove && move != killers[0] @@ -318,7 +311,7 @@ Move MovePicker::next_move() { case PROBCUT_CAPTURES: move = pick_best(cur++, endMoves); - if (move != ttMove && pos.see(move) > captureThreshold) + if (move != ttMove && pos.see(move) > threshold) return move; break; @@ -342,10 +335,3 @@ 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(); }