X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovepick.cpp;h=27245ec7c73904dd5c32a7cced6b7b4d461561d3;hp=c4eaa902e292e64cdea5858f4f9ae3318f07ec92;hb=e56e5045dd48489a304e2b46d5461361b205b237;hpb=917944e9c5324cc9659e630570e1852270b22bd4 diff --git a/src/movepick.cpp b/src/movepick.cpp index c4eaa902..27245ec7 100644 --- a/src/movepick.cpp +++ b/src/movepick.cpp @@ -1,7 +1,7 @@ /* 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 Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -35,7 +35,7 @@ namespace { STOP }; - // 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; @@ -49,108 +49,90 @@ 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. + inline 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) { + Move* cm, Move* fm, Search::Stack* s) : pos(p), history(h), depth(d) { assert(d > DEPTH_ZERO); - cur = end = moves; endBadCaptures = moves + MAX_MOVES - 1; countermoves = cm; + followupmoves = fm; ss = s; - if (p.checkers()) + if (pos.checkers()) stage = EVASION; else stage = MAIN_SEARCH; ttMove = (ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE); - end += (ttMove != 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) { + 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; else if (d > DEPTH_QS_RECAPTURES) - { stage = QSEARCH_1; - // 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); + endMoves += (ttMove != MOVE_NONE); } MovePicker::MovePicker(const Position& p, Move ttm, const HistoryStats& h, PieceType pt) - : pos(p), history(h), cur(moves), end(moves) { + : pos(p), history(h) { assert(!pos.checkers()); stage = PROBCUT; - // In ProbCut we generate only captures better than parent's captured piece + // 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; - end += (ttMove != MOVE_NONE); + endMoves += (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() assign 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. @@ -162,128 +144,109 @@ void MovePicker::score() { // 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]; - } + // In 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. + for (auto& m : *this) + if (type_of(m) == ENPASSANT) + m.value = PieceValue[MG][PAWN] - Value(PAWN); + + else if (type_of(m) == PROMOTION) + m.value = PieceValue[MG][pos.piece_on(to_sq(m))] - Value(PAWN) + + PieceValue[MG][promotion_type(m)] - PieceValue[MG][PAWN]; + else + m.value = PieceValue[MG][pos.piece_on(to_sq(m))] + - Value(type_of(pos.moved_piece(m))); } template<> void MovePicker::score() { - - Move m; - - for (ExtMove* it = moves; it != end; ++it) - { - m = it->move; - it->score = history[pos.moved_piece(m)][to_sq(m)]; - } + for (auto& m : *this) + m.value = history[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 score. - Move m; - int seeScore; + // moves with a negative SEE. This last group is ordered by the SEE value. + Value see; - 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 + for (auto& m : *this) + if ((see = pos.see_sign(m)) < VALUE_ZERO) + m.value = see - 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; + m.value = PieceValue[MG][pos.piece_on(to_sq(m))] + - Value(type_of(pos.moved_piece(m))) + HistoryStats::Max; else - it->score = history[pos.moved_piece(m)][to_sq(m)]; - } + m.value = 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. +/// 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() { +void MovePicker::generate_next_stage() { cur = moves; switch (++stage) { case CAPTURES_S1: case CAPTURES_S3: case CAPTURES_S4: case CAPTURES_S5: case CAPTURES_S6: - end = generate(pos, moves); + endMoves = generate(pos, moves); score(); - return; + break; 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; + endMoves = cur + 6; + killers[0] = ss->killers[0]; + killers[1] = ss->killers[1]; + killers[2] = countermoves[0]; + killers[3] = countermoves[1]; + killers[4] = followupmoves[0]; + killers[5] = followupmoves[1]; + break; case QUIETS_1_S1: - endQuiets = end = generate(pos, moves); + endQuiets = endMoves = generate(pos, moves); score(); - end = std::partition(cur, end, has_positive_score); - 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; + 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 cur = moves + MAX_MOVES - 1; - end = endBadCaptures; - return; + endMoves = endBadCaptures; + break; case EVASIONS_S2: - end = generate(pos, moves); - if (end > moves + 1) + endMoves = generate(pos, moves); + if (endMoves - moves > 1) score(); - return; + break; case QUIET_CHECKS_S3: - end = generate(pos, moves); - return; + endMoves = generate(pos, moves); + break; case EVASION: case QSEARCH_0: case QSEARCH_1: case PROBCUT: case RECAPTURE: stage = STOP; + /* Fall through */ + case STOP: - end = cur + 1; // Avoid another next_phase() call - return; + endMoves = cur + 1; // Avoid another next_phase() call + break; default: assert(false); @@ -292,9 +255,9 @@ void MovePicker::generate_next() { /// 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. +/// 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() { @@ -302,8 +265,8 @@ Move MovePicker::next_move() { while (true) { - while (cur == end) - generate_next(); + while (cur == endMoves) + generate_next_stage(); switch (stage) { @@ -312,59 +275,67 @@ Move MovePicker::next_move() { return ttMove; case CAPTURES_S1: - move = pick_best(cur++, end)->move; + move = pick_best(cur++, endMoves); if (move != ttMove) { - if (pos.see_sign(move) >= 0) + 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; + move = *cur++; if ( move != MOVE_NONE - && pos.pseudo_legal(move) && move != ttMove + && pos.pseudo_legal(move) && !pos.capture(move)) + { + for (int i = 0; i < cur - 1 - killers; i++) // Skip duplicated + if (move == killers[i]) + goto skip; return move; + } + skip: break; case QUIETS_1_S1: case QUIETS_2_S1: - move = (cur++)->move; + move = *cur++; if ( move != ttMove - && move != killers[0].move - && move != killers[1].move - && move != killers[2].move - && move != killers[3].move) + && move != killers[0] + && move != killers[1] + && move != killers[2] + && move != killers[3] + && move != killers[4] + && move != killers[5]) return move; break; case BAD_CAPTURES_S1: - return (cur--)->move; + return *cur--; case EVASIONS_S2: case CAPTURES_S3: case CAPTURES_S4: - move = pick_best(cur++, end)->move; + move = pick_best(cur++, endMoves); if (move != ttMove) return move; break; case CAPTURES_S5: - move = pick_best(cur++, end)->move; + move = pick_best(cur++, endMoves); if (move != ttMove && pos.see(move) > captureThreshold) return move; break; case CAPTURES_S6: - move = pick_best(cur++, end)->move; + move = pick_best(cur++, endMoves); if (to_sq(move) == recaptureSquare) return move; break; case QUIET_CHECKS_S3: - move = (cur++)->move; + move = *cur++; if (move != ttMove) return move; break;