X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovepick.cpp;h=ba99df0d1262fd7edffe0f03d0f68240d47c03bc;hp=4d2d31167ea2db2641c582c545ba3c6c46b1a0fe;hb=55df3fa2d7631ed67e46f9433aa7f3a71c18e5e7;hpb=58c7a5c4775f7efa333bb2c921583ffba301f6b2 diff --git a/src/movepick.cpp b/src/movepick.cpp index 4d2d3116..ba99df0d 100644 --- a/src/movepick.cpp +++ b/src/movepick.cpp @@ -1,481 +1,364 @@ /* - Glaurung, a UCI chess playing engine. - Copyright (C) 2004-2008 Tord Romstad + Stockfish, a UCI chess playing engine derived from Glaurung 2.1 + Copyright (C) 2004-2008 Tord Romstad (Glaurung author) + Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad - Glaurung is free software: you can redistribute it and/or modify + 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. - - Glaurung is distributed in the hope that it will be useful, + + + 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 GNU General Public License for more details. - + You should have received a copy of the GNU General Public License along with this program. If not, see . */ - -//// -//// Includes -//// - +#include #include -#include "history.h" #include "movegen.h" #include "movepick.h" -#include "search.h" -#include "value.h" - - -//// -//// Local definitions -//// +#include "thread.h" namespace { - /// Variables - - MovePicker::MovegenPhase PhaseTable[32]; - int MainSearchPhaseIndex; - int EvasionsPhaseIndex; - int QsearchWithChecksPhaseIndex; - int QsearchWithoutChecksPhaseIndex; - + enum Sequencer { + 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 + }; + + // 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 MoveStack& 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 MoveStack* pick_best(MoveStack* begin, MoveStack* end) + { + std::swap(*begin, *std::max_element(begin, end)); + return begin; + } } - -//// -//// Functions -//// - - -/// Constructor for the MovePicker class. Apart from the position for which -/// it is asked to pick legal moves, MovePicker also wants some information +/// 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 about how important good /// move ordering is at the current node. -MovePicker::MovePicker(Position &p, bool pvnode, Move ttm, Move mk, - Move k1, Move k2, Depth dpth) { - pos = &p; - pvNode = pvnode; - ttMove = ttm; - mateKiller = (mk == ttm)? MOVE_NONE : mk; - killer1 = k1; - killer2 = k2; - depth = dpth; - movesPicked = 0; - numOfMoves = 0; - numOfBadCaptures = 0; - dc = p.discovered_check_candidates(p.side_to_move()); - - if(p.is_check()) - phaseIndex = EvasionsPhaseIndex; - else if(depth > Depth(0)) - phaseIndex = MainSearchPhaseIndex; - else if(depth == Depth(0)) - phaseIndex = QsearchWithChecksPhaseIndex; +MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const History& h, + Search::Stack* s, Value beta) : pos(p), H(h), depth(d) { + + assert(d > DEPTH_ZERO); + + captureThreshold = 0; + cur = end = moves; + endBadCaptures = moves + MAX_MOVES - 1; + ss = s; + + if (p.in_check()) + phase = EVASION; + else - phaseIndex = QsearchWithoutChecksPhaseIndex; + { + phase = MAIN_SEARCH; - pinned = p.pinned_pieces(p.side_to_move()); + killers[0].move = ss->killers[0]; + killers[1].move = ss->killers[1]; - finished = false; + // Consider sligtly negative captures as good if at low depth and far from beta + if (ss && ss->staticEval < beta - PawnValueMg && d < 3 * ONE_PLY) + captureThreshold = -PawnValueMg; + + // Consider negative captures as good if still enough to reach beta + else if (ss && ss->staticEval > beta) + captureThreshold = beta - ss->staticEval; + } + + ttMove = (ttm && pos.is_pseudo_legal(ttm) ? ttm : MOVE_NONE); + end += (ttMove != MOVE_NONE); } +MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const History& h, + Square sq) : pos(p), H(h), cur(moves), end(moves) { -/// 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 of the types we are interested in. + assert(d <= DEPTH_ZERO); -Move MovePicker::get_next_move() { - Move move; + if (p.in_check()) + phase = EVASION; - while(true) { - // If we already have a list of generated moves, pick the best move from - // the list, and return it: - move = this->pick_move_from_list(); - if(move != MOVE_NONE) { - assert(move_is_ok(move)); - return move; - } - - // Next phase: - phaseIndex++; - switch(PhaseTable[phaseIndex]) { - - case PH_TT_MOVE: - if(ttMove != MOVE_NONE) { - assert(move_is_ok(ttMove)); - Move m = generate_move_if_legal(*pos, ttMove, pinned); - if(m != MOVE_NONE) { - assert(m == ttMove); - return m; - } - } - break; - - case PH_MATE_KILLER: - if(mateKiller != MOVE_NONE) { - assert(move_is_ok(mateKiller)); - Move m = generate_move_if_legal(*pos, mateKiller, pinned); - if(m != MOVE_NONE) { - assert(m == mateKiller); - return m; - } - } - break; - - case PH_GOOD_CAPTURES: - // pinned = pos->pinned_pieces(pos->side_to_move()); - numOfMoves = generate_captures(*pos, moves); - this->score_captures(); - movesPicked = 0; - break; - - case PH_BAD_CAPTURES: - badCapturesPicked = 0; - break; - - case PH_NONCAPTURES: - numOfMoves = generate_noncaptures(*pos, moves); - this->score_noncaptures(); - movesPicked = 0; - break; - - case PH_EVASIONS: - assert(pos->is_check()); - // pinned = pos->pinned_pieces(pos->side_to_move()); - numOfMoves = generate_evasions(*pos, moves); - this->score_evasions(); - movesPicked = 0; - break; - - case PH_QCAPTURES: - // pinned = pos->pinned_pieces(pos->side_to_move()); - numOfMoves = generate_captures(*pos, moves); - this->score_qcaptures(); - movesPicked = 0; - break; - - case PH_QCHECKS: - numOfMoves = generate_checks(*pos, moves, dc); - movesPicked = 0; - break; - - case PH_STOP: - return MOVE_NONE; - - default: - assert(false); - return MOVE_NONE; - } - } + else if (d > DEPTH_QS_NO_CHECKS) + phase = QSEARCH_0; - assert(false); + else if (d > DEPTH_QS_RECAPTURES) + { + phase = QSEARCH_1; - return MOVE_NONE; + // 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.is_capture_or_promotion(ttm)) + ttm = MOVE_NONE; + } + else + { + phase = RECAPTURE; + recaptureSquare = sq; + ttm = MOVE_NONE; + } + + ttMove = (ttm && pos.is_pseudo_legal(ttm) ? ttm : MOVE_NONE); + end += (ttMove != MOVE_NONE); } +MovePicker::MovePicker(const Position& p, Move ttm, const History& h, PieceType pt) + : pos(p), H(h), cur(moves), end(moves) { -/// A variant of get_next_move() which takes a lock as a parameter, used to -/// prevent multiple threads from picking the same move at a split point. + assert(!pos.in_check()); -Move MovePicker::get_next_move(Lock &lock) { - Move m; + phase = PROBCUT; - lock_grab(&lock); - if(finished) { - lock_release(&lock); - return MOVE_NONE; - } - m = this->get_next_move(); - if(m == MOVE_NONE) - finished = true; - lock_release(&lock); - - return m; -} + // In ProbCut we generate only captures better than parent's captured piece + captureThreshold = PieceValue[MG][pt]; + ttMove = (ttm && pos.is_pseudo_legal(ttm) ? ttm : MOVE_NONE); - -/// MovePicker::number_of_moves() simply returns the numOfMoves member -/// variable. It is intended to be used in positions where the side to move -/// is in check, for detecting checkmates or situations where there is only -/// a single reply to check. + if (ttMove && (!pos.is_capture(ttMove) || pos.see(ttMove) <= captureThreshold)) + ttMove = MOVE_NONE; -int MovePicker::number_of_moves() const { - return numOfMoves; + end += (ttMove != MOVE_NONE); } -/// MovePicker::score_captures(), MovePicker::score_noncaptures(), -/// MovePicker::score_evasions() and MovePicker::score_qcaptures() assign a -/// numerical move ordering score to each move in a move list. The moves -/// with highest scores will be picked first by -/// MovePicker::pick_move_from_list(). +/// 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 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 + // 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 + // 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 + // 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. - for(int i = 0; i < numOfMoves; i++) { - int seeValue = pos->see(moves[i].move); - if(seeValue >= 0) { - if(move_promotion(moves[i].move)) - moves[i].score = QueenValueMidgame; - else - moves[i].score = - int(pos->midgame_value_of_piece_on(move_to(moves[i].move))) - - int(pos->type_of_piece_on(move_from(moves[i].move))); - } - else - moves[i].score = seeValue; - + // 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 (MoveStack* it = moves; it != end; ++it) + { + m = it->move; + it->score = PieceValue[MG][pos.piece_on(to_sq(m))] + - type_of(pos.piece_moved(m)); + + if (type_of(m) == PROMOTION) + it->score += PieceValue[MG][promotion_type(m)]; } } void MovePicker::score_noncaptures() { - for(int i = 0; i < numOfMoves; i++) { - Move m = moves[i].move; - if(m == killer1) - moves[i].score = HistoryMax + 2; - else if(m == killer2) - moves[i].score = HistoryMax + 1; - else - moves[i].score = H.move_ordering_score(pos->piece_on(move_from(m)), m); + + Move m; + + for (MoveStack* it = moves; it != end; ++it) + { + m = it->move; + it->score = H.value(pos.piece_moved(m), to_sq(m)); } } void MovePicker::score_evasions() { - for(int i = 0; i < numOfMoves; i++) { - Move m = moves[i].move; - if(m == ttMove) - moves[i].score = 2*HistoryMax; - else if(!pos->square_is_empty(move_to(m))) { - int seeScore = pos->see(m); - moves[i].score = (seeScore >= 0)? seeScore + HistoryMax : seeScore; - } - else - moves[i].score = H.move_ordering_score(pos->piece_on(move_from(m)), m); + // 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; + + if (end < moves + 2) + return; + + for (MoveStack* it = moves; it != end; ++it) + { + m = it->move; + if ((seeScore = pos.see_sign(m)) < 0) + it->score = seeScore - History::MaxValue; // Be sure we are at the bottom + else if (pos.is_capture(m)) + it->score = PieceValue[MG][pos.piece_on(to_sq(m))] + - type_of(pos.piece_moved(m)) + History::MaxValue; + else + it->score = H.value(pos.piece_moved(m), to_sq(m)); } } -void MovePicker::score_qcaptures() { - // Use MVV/LVA ordering. - for(int i = 0; i < numOfMoves; i++) { - Move m = moves[i].move; - if(move_promotion(m)) - moves[i].score = QueenValueMidgame; - else - moves[i].score = - int(pos->midgame_value_of_piece_on(move_to(m))) - - int(pos->midgame_value_of_piece_on(move_to(m))) / 64; + +/// MovePicker::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 (++phase) { + + case CAPTURES_S1: case CAPTURES_S3: case CAPTURES_S4: case CAPTURES_S5: case CAPTURES_S6: + end = generate(pos, moves); + score_captures(); + return; + + case KILLERS_S1: + cur = killers; + end = cur + 2; + return; + + case QUIETS_1_S1: + endQuiets = end = generate(pos, moves); + score_noncaptures(); + end = std::partition(cur, end, has_positive_score); + sort(cur, end); + return; + + case QUIETS_2_S1: + cur = end; + end = endQuiets; + if (depth >= 3 * ONE_PLY) + 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); + score_evasions(); + return; + + case QUIET_CHECKS_S3: + end = generate(pos, moves); + return; + + case EVASION: case QSEARCH_0: case QSEARCH_1: case PROBCUT: case RECAPTURE: + phase = STOP; + case STOP: + end = cur + 1; // Avoid another next_phase() call + return; + + default: + assert(false); } } -/// MovePicker::pick_move_from_list() picks the move with the biggest score -/// from a list of generated moves (moves[] or badCaptures[], depending on -/// the current move generation phase). It takes care not to return the -/// transposition table move if that has already been serched previously. -/// While picking captures in the PH_GOOD_CAPTURES phase (i.e. while picking -/// non-losing captures in the main search), it moves all captures with -/// negative SEE values to the badCaptures[] array. +/// MovePicker::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 score from a list +/// of generated moves taking care not to return the tt move if has already been +/// searched previously. +template<> +Move MovePicker::next_move() { -Move MovePicker::pick_move_from_list() { - int bestScore = -10000000; - int bestIndex; Move move; - switch(PhaseTable[phaseIndex]) { - - case PH_GOOD_CAPTURES: - assert(!pos->is_check()); - assert(movesPicked >= 0); - while(movesPicked < numOfMoves) { - bestScore = -10000000; - bestIndex = -1; - for(int i = movesPicked; i < numOfMoves; i++) { - if(moves[i].score < 0) { - // Losing capture, move it to the badCaptures[] array - assert(numOfBadCaptures < 63); - badCaptures[numOfBadCaptures++] = moves[i]; - moves[i--] = moves[--numOfMoves]; - } - else if(moves[i].score > bestScore) { - bestIndex = i; - bestScore = moves[i].score; - } - } - if(bestIndex != -1) { // Found a good capture - move = moves[bestIndex].move; - moves[bestIndex] = moves[movesPicked++]; - if(move != ttMove && move != mateKiller && - pos->move_is_legal(move, pinned)) - return move; - } - } - break; - - case PH_NONCAPTURES: - assert(!pos->is_check()); - assert(movesPicked >= 0); - while(movesPicked < numOfMoves) { - bestScore = -10000000; - - // If this is a PV node or we have only picked a few moves, scan - // the entire move list for the best move. If many moves have already - // been searched and it is not a PV node, we are probably failing low - // anyway, so we just pick the first move from the list. - if(pvNode || movesPicked < 12) { - bestIndex = -1; - for(int i = movesPicked; i < numOfMoves; i++) - if(moves[i].score > bestScore) { - bestIndex = i; - bestScore = moves[i].score; - } - } - else - bestIndex = movesPicked; - - if(bestIndex != -1) { - move = moves[bestIndex].move; - moves[bestIndex] = moves[movesPicked++]; - if(move != ttMove && move != mateKiller && - pos->move_is_legal(move, pinned)) - return move; - } - } - break; - - case PH_EVASIONS: - assert(pos->is_check()); - assert(movesPicked >= 0); - while(movesPicked < numOfMoves) { - bestScore = -10000000; - bestIndex = -1; - for(int i = movesPicked; i < numOfMoves; i++) - if(moves[i].score > bestScore) { - bestIndex = i; - bestScore = moves[i].score; - } - - if(bestIndex != -1) { - move = moves[bestIndex].move; - moves[bestIndex] = moves[movesPicked++]; - return move; - } - } - break; - - case PH_BAD_CAPTURES: - assert(!pos->is_check()); - assert(badCapturesPicked >= 0); - // It's probably a good idea to use SEE move ordering here, instead - // of just picking the first move. FIXME - while(badCapturesPicked < numOfBadCaptures) { - move = badCaptures[badCapturesPicked++].move; - if(move != ttMove && move != mateKiller && - pos->move_is_legal(move, pinned)) - return move; - } - break; - - case PH_QCAPTURES: - assert(!pos->is_check()); - assert(movesPicked >= 0); - while(movesPicked < numOfMoves) { - bestScore = -10000000; - if(movesPicked < 4) { - bestIndex = -1; - for(int i = movesPicked; i < numOfMoves; i++) - if(moves[i].score > bestScore) { - bestIndex = i; - bestScore = moves[i].score; + while (true) + { + while (cur == end) + generate_next(); + + switch (phase) { + + case MAIN_SEARCH: case EVASION: case QSEARCH_0: case QSEARCH_1: case PROBCUT: + cur++; + return ttMove; + + case CAPTURES_S1: + move = pick_best(cur++, end)->move; + if (move != ttMove) + { + assert(captureThreshold <= 0); // Otherwise we cannot use see_sign() + + if (pos.see_sign(move) >= captureThreshold) + return move; + + // Losing capture, move it to the tail of the array + (endBadCaptures--)->move = move; } + break; + + case KILLERS_S1: + move = (cur++)->move; + if ( move != MOVE_NONE + && pos.is_pseudo_legal(move) + && move != ttMove + && !pos.is_capture(move)) + return move; + break; + + case QUIETS_1_S1: case QUIETS_2_S1: + move = (cur++)->move; + if ( move != ttMove + && move != killers[0].move + && move != killers[1].move) + 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; + if (move != ttMove) + return move; + break; + + case CAPTURES_S5: + move = pick_best(cur++, end)->move; + if (move != ttMove && pos.see(move) > captureThreshold) + return move; + break; + + case CAPTURES_S6: + move = pick_best(cur++, end)->move; + if (to_sq(move) == recaptureSquare) + return move; + break; + + case QUIET_CHECKS_S3: + move = (cur++)->move; + if (move != ttMove) + return move; + break; + + case STOP: + return MOVE_NONE; + + default: + assert(false); } - else - bestIndex = movesPicked; - - if(bestIndex != -1) { - move = moves[bestIndex].move; - moves[bestIndex] = moves[movesPicked++]; - // Remember to change the line below if we decide to hash the qsearch! - // Maybe also postpone the legality check until after futility pruning? - if(/* move != ttMove && */ pos->move_is_legal(move, pinned)) - return move; - } - } - break; - - case PH_QCHECKS: - assert(!pos->is_check()); - assert(movesPicked >= 0); - // Perhaps we should do something better than just picking the first - // move here? FIXME - while(movesPicked < numOfMoves) { - move = moves[movesPicked++].move; - // Remember to change the line below if we decide to hash the qsearch! - if(/* move != ttMove && */ pos->move_is_legal(move, pinned)) - return move; - } - break; - - default: - break; } - - return MOVE_NONE; } -MovePicker::MovegenPhase MovePicker::current_move_type() const { - return PhaseTable[phaseIndex]; -} -/// MovePicker::init_phase_table() initializes the PhaseTable[], -/// MainSearchPhaseIndex, EvasionPhaseIndex, QsearchWithChecksPhaseIndex -/// and QsearchWithoutChecksPhaseIndex variables. It is only called once -/// during program startup, and never again while the program is running. - -void MovePicker::init_phase_table() { - int i = 0; - - // Main search - MainSearchPhaseIndex = i - 1; - PhaseTable[i++] = PH_TT_MOVE; - PhaseTable[i++] = PH_MATE_KILLER; - PhaseTable[i++] = PH_GOOD_CAPTURES; - // PH_KILLER_1 and PH_KILLER_2 are not yet used. - // PhaseTable[i++] = PH_KILLER_1; - // PhaseTable[i++] = PH_KILLER_2; - PhaseTable[i++] = PH_NONCAPTURES; - PhaseTable[i++] = PH_BAD_CAPTURES; - PhaseTable[i++] = PH_STOP; - - // Check evasions - EvasionsPhaseIndex = i - 1; - PhaseTable[i++] = PH_EVASIONS; - PhaseTable[i++] = PH_STOP; - - // Quiescence search with checks - QsearchWithChecksPhaseIndex = i - 1; - PhaseTable[i++] = PH_QCAPTURES; - PhaseTable[i++] = PH_QCHECKS; - PhaseTable[i++] = PH_STOP; - - // Quiescence search without checks - QsearchWithoutChecksPhaseIndex = i - 1; - PhaseTable[i++] = PH_QCAPTURES; - PhaseTable[i++] = PH_STOP; -} +/// 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 should be lock protected by the caller. +template<> +Move MovePicker::next_move() { return ss->sp->mp->next_move(); }