X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovepick.cpp;h=84f26dbf7835c08a2794313aad91560d4e6f3991;hp=2f9cd146010e28c0fa0b6f7523e8f7f5cde2ab14;hb=8a7876d48d4360d14d918c1ff444b5d6eb0382de;hpb=4b232f5ddc7d8a05b7e6e3267bcb7a4119ffdc25 diff --git a/src/movepick.cpp b/src/movepick.cpp index 2f9cd146..84f26dbf 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) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2008-2014 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 @@ -20,171 +20,132 @@ #include -#include "movegen.h" #include "movepick.h" -#include "search.h" -#include "types.h" +#include "thread.h" namespace { - enum MovegenPhase { - PH_TT_MOVES, // Transposition table move and mate killer - PH_GOOD_CAPTURES, // Queen promotions and captures with SEE values >= 0 - PH_KILLERS, // Killer moves from the current ply - PH_NONCAPTURES, // Non-captures and underpromotions - PH_BAD_CAPTURES, // Queen promotions and captures with SEE values < 0 - PH_EVASIONS, // Check evasions - PH_QCAPTURES, // Captures in quiescence search - PH_QCHECKS, // Non-capture checks in quiescence search - PH_STOP + 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 }; - CACHE_LINE_ALIGNMENT - const uint8_t MainSearchTable[] = { PH_TT_MOVES, PH_GOOD_CAPTURES, PH_KILLERS, PH_NONCAPTURES, PH_BAD_CAPTURES, PH_STOP }; - const uint8_t EvasionTable[] = { PH_TT_MOVES, PH_EVASIONS, PH_STOP }; - const uint8_t QsearchWithChecksTable[] = { PH_TT_MOVES, PH_QCAPTURES, PH_QCHECKS, PH_STOP }; - const uint8_t QsearchWithoutChecksTable[] = { PH_TT_MOVES, PH_QCAPTURES, PH_STOP }; -} - -bool MovePicker::isBadCapture() const { return phase == PH_BAD_CAPTURES; } - -/// Constructor for the MovePicker class. Apart from the position for which -/// it is asked to pick legal moves, MovePicker also wants some 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(const Position& p, Move ttm, Depth d, const History& h, - SearchStack* ss, Value beta) : pos(p), H(h) { - int searchTT = ttm; - ttMoves[0].move = ttm; - badCaptureThreshold = 0; - badCaptures = moves + MAX_MOVES; + // Our insertion sort, which is guaranteed (and also needed) to be stable + void insertion_sort(ExtMove* begin, ExtMove* end) + { + ExtMove tmp, *p, *q; + + for (p = begin + 1; p < end; ++p) + { + tmp = *p; + for (q = p; q != begin && *(q-1) < tmp; --q) + *q = *(q-1); + *q = tmp; + } + } - assert(d > DEPTH_ZERO); + // 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; } - if (p.in_check()) + // 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) { - ttMoves[1].move = killers[0].move = killers[1].move = MOVE_NONE; - phasePtr = EvasionTable; + std::swap(*begin, *std::max_element(begin, end)); + return begin; } - else - { - ttMoves[1].move = (ss->mateKiller == ttm) ? MOVE_NONE : ss->mateKiller; - searchTT |= ttMoves[1].move; - killers[0].move = ss->killers[0]; - killers[1].move = ss->killers[1]; +} // namespace - // Consider sligtly negative captures as good if at low - // depth and far from beta. - if (ss && ss->eval < beta - PawnValueMidgame && d < 3 * ONE_PLY) - badCaptureThreshold = -PawnValueMidgame; - phasePtr = MainSearchTable; - } +/// 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 +/// ordering is at the current node. - phasePtr += int(!searchTT) - 1; - go_next_phase(); -} +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) { -MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const History& h) - : pos(p), H(h) { - int searchTT = ttm; - ttMoves[0].move = ttm; - ttMoves[1].move = MOVE_NONE; + assert(d > DEPTH_ZERO); - assert(d <= DEPTH_ZERO); + cur = end = moves; + endBadCaptures = moves + MAX_MOVES - 1; + countermoves = cm; + followupmoves = fm; + ss = s; - if (p.in_check()) - phasePtr = EvasionTable; - else if (d >= DEPTH_QS_CHECKS) - phasePtr = QsearchWithChecksTable; - else - { - phasePtr = QsearchWithoutChecksTable; + if (pos.checkers()) + stage = EVASION; - // 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 != MOVE_NONE && !pos.move_is_capture(ttm) && !move_is_promotion(ttm)) - searchTT = ttMoves[0].move = MOVE_NONE; - } + else + stage = MAIN_SEARCH; - phasePtr += int(!searchTT) - 1; - go_next_phase(); + ttMove = (ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE); + end += (ttMove != MOVE_NONE); } +MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const HistoryStats& h, + Square s) : pos(p), history(h), cur(moves), end(moves) { -/// MovePicker::go_next_phase() generates, scores and sorts the next bunch -/// of moves when there are no more moves to try for the current phase. + assert(d <= DEPTH_ZERO); -void MovePicker::go_next_phase() { + if (pos.checkers()) + stage = EVASION; - curMove = moves; - phase = *(++phasePtr); - switch (phase) { + else if (d > DEPTH_QS_NO_CHECKS) + stage = QSEARCH_0; - case PH_TT_MOVES: - curMove = ttMoves; - lastMove = curMove + 2; - return; - - case PH_GOOD_CAPTURES: - lastMove = generate(pos, moves); - score_captures(); - return; + else if (d > DEPTH_QS_RECAPTURES) + { + stage = QSEARCH_1; - case PH_KILLERS: - curMove = killers; - lastMove = curMove + 2; - return; + // 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 = s; + ttm = MOVE_NONE; + } - case PH_NONCAPTURES: - lastMove = generate(pos, moves); - score_noncaptures(); - sort_moves(moves, lastMove, &lastGoodNonCapture); - return; + ttMove = (ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE); + end += (ttMove != MOVE_NONE); +} - case PH_BAD_CAPTURES: - // Bad captures SEE value is already calculated so just pick - // them in order to get SEE move ordering. - curMove = badCaptures; - lastMove = moves + MAX_MOVES; - return; +MovePicker::MovePicker(const Position& p, Move ttm, const HistoryStats& h, PieceType pt) + : pos(p), history(h), cur(moves), end(moves) { - case PH_EVASIONS: - assert(pos.in_check()); - lastMove = generate(pos, moves); - score_evasions(); - return; + assert(!pos.checkers()); - case PH_QCAPTURES: - lastMove = generate(pos, moves); - score_captures(); - return; + stage = PROBCUT; - case PH_QCHECKS: - lastMove = generate(pos, moves); - return; + // 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); - case PH_STOP: - lastMove = curMove + 1; // Avoid another go_next_phase() call - return; + if (ttMove && (!pos.capture(ttMove) || pos.see(ttMove) <= captureThreshold)) + ttMove = MOVE_NONE; - default: - assert(false); - return; - } + end += (ttMove != MOVE_NONE); } -/// 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 get_next_move(). - -void MovePicker::score_captures() { +/// 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. // Suprisingly, this appears to perform slightly better than SEE based // move ordering. The reason is probably that in a position with a winning @@ -194,150 +155,238 @@ void MovePicker::score_captures() { // 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). + // 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. Move m; - // Use MVV/LVA ordering - for (MoveStack* cur = moves; cur != lastMove; cur++) + for (ExtMove* it = moves; it != end; ++it) { - m = cur->move; - if (move_is_promotion(m)) - cur->score = QueenValueMidgame; - else - cur->score = pos.midgame_value_of_piece_on(move_to(m)) - - pos.type_of_piece_on(move_from(m)); + m = it->move; + it->value = PieceValue[MG][pos.piece_on(to_sq(m))] + - Value(type_of(pos.moved_piece(m))); + + if (type_of(m) == ENPASSANT) + it->value += PieceValue[MG][PAWN]; + + else if (type_of(m) == PROMOTION) + it->value += PieceValue[MG][promotion_type(m)] - PieceValue[MG][PAWN]; } } -void MovePicker::score_noncaptures() { +template<> +void MovePicker::score() { Move m; - Square from; - for (MoveStack* cur = moves; cur != lastMove; cur++) + for (ExtMove* it = moves; it != end; ++it) { - m = cur->move; - from = move_from(m); - cur->score = H.value(pos.piece_on(from), move_to(m)); + m = it->move; + it->value = history[pos.moved_piece(m)][to_sq(m)]; } } -void MovePicker::score_evasions() { - // Try good captures ordered by MVV/LVA, then non-captures if - // destination square is not under attack, ordered by history - // value, and at the end bad-captures and non-captures with a - // negative SEE. This last group is ordered by the SEE score. +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; - int seeScore; - - // Skip if we don't have at least two moves to order - if (lastMove < moves + 2) - return; + Value see; - for (MoveStack* cur = moves; cur != lastMove; cur++) + for (ExtMove* it = moves; it != end; ++it) { - m = cur->move; - if ((seeScore = pos.see_sign(m)) < 0) - cur->score = seeScore - History::MaxValue; // Be sure we are at the bottom - else if (pos.move_is_capture(m)) - cur->score = pos.midgame_value_of_piece_on(move_to(m)) - - pos.type_of_piece_on(move_from(m)) + History::MaxValue; + m = it->move; + if ((see = pos.see_sign(m)) < VALUE_ZERO) + it->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; else - cur->score = H.value(pos.piece_on(move_from(m)), move_to(m)); + it->value = history[pos.moved_piece(m)][to_sq(m)]; + } +} + + +/// 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() { + + 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; + 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); + score(); + end = std::partition(cur, end, has_positive_value); + 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; + /* Fall through */ + + case STOP: + end = cur + 1; // Avoid another next_phase() call + return; + + default: + assert(false); } } -/// 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. 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. Note that this function is not thread safe so should be -/// lock protected by caller when accessed through a shared MovePicker object. -Move MovePicker::get_next_move() { +/// 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 move; while (true) { - while (curMove == lastMove) - go_next_phase(); + while (cur == end) + generate_next_stage(); - switch (phase) { + switch (stage) { - case PH_TT_MOVES: - move = (curMove++)->move; - if ( move != MOVE_NONE - && pos.move_is_pl(move)) - return move; - break; + case MAIN_SEARCH: case EVASION: case QSEARCH_0: case QSEARCH_1: case PROBCUT: + ++cur; + return ttMove; - case PH_GOOD_CAPTURES: - move = pick_best(curMove++, lastMove).move; - if ( move != ttMoves[0].move - && move != ttMoves[1].move) + case CAPTURES_S1: + move = pick_best(cur++, end)->move; + if (move != ttMove) { - // Check for a non negative SEE now - int seeValue = pos.see_sign(move); - if (seeValue >= badCaptureThreshold) + if (pos.see_sign(move) >= VALUE_ZERO) return move; - // Losing capture, move it to the tail of the array, note - // that move has now been already checked for legality. - (--badCaptures)->move = move; - badCaptures->score = seeValue; + // Losing capture, move it to the tail of the array + (endBadCaptures--)->move = move; } break; - case PH_KILLERS: - move = (curMove++)->move; - if ( move != MOVE_NONE - && pos.move_is_pl(move) - && move != ttMoves[0].move - && move != ttMoves[1].move - && !pos.move_is_capture(move)) + case KILLERS_S1: + move = (cur++)->move; + if ( move != MOVE_NONE + && move != ttMove + && pos.pseudo_legal(move) + && !pos.capture(move)) return move; break; - case PH_NONCAPTURES: - // Sort negative scored moves only when we get there - if (curMove == lastGoodNonCapture) - insertion_sort(lastGoodNonCapture, lastMove); - - move = (curMove++)->move; - if ( move != ttMoves[0].move - && move != ttMoves[1].move + case QUIETS_1_S1: case QUIETS_2_S1: + move = (cur++)->move; + if ( move != ttMove && move != killers[0].move - && move != killers[1].move) + && move != killers[1].move + && move != killers[2].move + && move != killers[3].move + && move != killers[4].move + && move != killers[5].move) return move; break; - case PH_BAD_CAPTURES: - move = pick_best(curMove++, lastMove).move; - return move; + case BAD_CAPTURES_S1: + return (cur--)->move; - case PH_EVASIONS: - case PH_QCAPTURES: - move = pick_best(curMove++, lastMove).move; - if (move != ttMoves[0].move) + case EVASIONS_S2: case CAPTURES_S3: case CAPTURES_S4: + move = pick_best(cur++, end)->move; + if (move != ttMove) return move; break; - case PH_QCHECKS: - move = (curMove++)->move; - if ( move != ttMoves[0].move) + 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 PH_STOP: + case QUIET_CHECKS_S3: + move = (cur++)->move; + if (move != ttMove) + return move; + break; + + case STOP: return MOVE_NONE; default: assert(false); - break; } } } + + +/// 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(); }