X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovepick.cpp;h=4e31037c0af48d39f9319a36d8fc2a857b358ef4;hp=4cf45ad36202b715bd8c8e9efcdef4353256c186;hb=f12449d492f75a83f9cd3a24cdb461bc3595536f;hpb=5f58db8c9971d8709093ca3c97cecdc99c61303e diff --git a/src/movepick.cpp b/src/movepick.cpp index 4cf45ad3..4e31037c 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) 2008-2012 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 @@ -20,13 +20,12 @@ #include -#include "movegen.h" #include "movepick.h" #include "thread.h" namespace { - enum Sequencer { + 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, @@ -36,14 +35,28 @@ namespace { 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; } + // 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; + } + } + + // 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 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) + // 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) { std::swap(*begin, *std::max_element(begin, end)); return begin; @@ -52,100 +65,87 @@ 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 History& h, - Search::Stack* s, Value beta) : pos(p), Hist(h), depth(d) { +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) { assert(d > DEPTH_ZERO); - captureThreshold = 0; cur = end = moves; endBadCaptures = moves + MAX_MOVES - 1; + countermoves = cm; + followupmoves = fm; ss = s; if (p.checkers()) - phase = EVASION; + stage = EVASION; else - { - phase = MAIN_SEARCH; + stage = MAIN_SEARCH; - killers[0].move = ss->killers[0]; - killers[1].move = ss->killers[1]; - - // 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); + ttMove = (ttm && pos.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), Hist(h), cur(moves), end(moves) { +MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const HistoryStats& h, + Square sq) : pos(p), history(h), cur(moves), end(moves) { assert(d <= DEPTH_ZERO); if (p.checkers()) - phase = EVASION; + stage = EVASION; else if (d > DEPTH_QS_NO_CHECKS) - phase = QSEARCH_0; + stage = QSEARCH_0; else if (d > DEPTH_QS_RECAPTURES) { - phase = QSEARCH_1; + stage = QSEARCH_1; - // Skip TT move if is not a capture or a promotion, this avoids qsearch + // 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)) + if (ttm && !pos.capture_or_promotion(ttm)) ttm = MOVE_NONE; } else { - phase = RECAPTURE; + stage = RECAPTURE; recaptureSquare = sq; ttm = MOVE_NONE; } - ttMove = (ttm && pos.is_pseudo_legal(ttm) ? ttm : MOVE_NONE); + ttMove = (ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE); end += (ttMove != MOVE_NONE); } -MovePicker::MovePicker(const Position& p, Move ttm, const History& h, PieceType pt) - : pos(p), Hist(h), cur(moves), end(moves) { +MovePicker::MovePicker(const Position& p, Move ttm, const HistoryStats& h, PieceType pt) + : pos(p), history(h), cur(moves), end(moves) { assert(!pos.checkers()); - phase = PROBCUT; + 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.is_pseudo_legal(ttm) ? ttm : MOVE_NONE); + ttMove = (ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE); - if (ttMove && (!pos.is_capture(ttMove) || pos.see(ttMove) <= captureThreshold)) + if (ttMove && (!pos.capture(ttMove) || pos.see(ttMove) <= captureThreshold)) ttMove = MOVE_NONE; 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 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 @@ -155,92 +155,114 @@ 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; - for (MoveStack* it = moves; it != end; ++it) + for (ExtMove* it = moves; it != end; ++it) { m = it->move; - it->score = PieceValue[MG][pos.piece_on(to_sq(m))] - - type_of(pos.piece_moved(m)); + it->value = 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]; + it->value += PieceValue[MG][promotion_type(m)] - PieceValue[MG][PAWN]; else if (type_of(m) == ENPASSANT) - it->score += PieceValue[MG][PAWN]; + it->value += PieceValue[MG][PAWN]; } } -void MovePicker::score_noncaptures() { +template<> +void MovePicker::score() { Move m; - for (MoveStack* it = moves; it != end; ++it) + for (ExtMove* it = moves; it != end; ++it) { m = it->move; - it->score = Hist[pos.piece_moved(m)][to_sq(m)]; + it->value = history[pos.moved_piece(m)][to_sq(m)]; } } -void MovePicker::score_evasions() { +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. + // moves with a negative SEE. This last group is ordered by the SEE value. Move m; - int seeScore; - - if (end < moves + 2) - return; + Value see; - for (MoveStack* it = moves; it != end; ++it) + for (ExtMove* it = moves; it != end; ++it) { m = it->move; - if ((seeScore = pos.see_sign(m)) < 0) - it->score = seeScore - History::Max; // 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::Max; + 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))] + - type_of(pos.moved_piece(m)) + HistoryStats::Max; else - it->score = Hist[pos.piece_moved(m)][to_sq(m)]; + it->value = history[pos.moved_piece(m)][to_sq(m)]; } } -/// MovePicker::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 (++phase) { + switch (++stage) { case CAPTURES_S1: case CAPTURES_S3: case CAPTURES_S4: case CAPTURES_S5: case CAPTURES_S6: end = generate(pos, moves); - score_captures(); + 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_noncaptures(); - end = std::partition(cur, end, has_positive_score); - sort(cur, end); + 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) - sort(cur, end); + insertion_sort(cur, end); return; case BAD_CAPTURES_S1: @@ -251,7 +273,8 @@ void MovePicker::generate_next() { case EVASIONS_S2: end = generate(pos, moves); - score_evasions(); + if (end > moves + 1) + score(); return; case QUIET_CHECKS_S3: @@ -259,7 +282,7 @@ void MovePicker::generate_next() { return; case EVASION: case QSEARCH_0: case QSEARCH_1: case PROBCUT: case RECAPTURE: - phase = STOP; + stage = STOP; case STOP: end = cur + 1; // Avoid another next_phase() call return; @@ -270,11 +293,10 @@ void MovePicker::generate_next() { } -/// 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. +/// 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() { @@ -283,21 +305,19 @@ Move MovePicker::next_move() { while (true) { while (cur == end) - generate_next(); + generate_next_stage(); - switch (phase) { + switch (stage) { case MAIN_SEARCH: case EVASION: case QSEARCH_0: case QSEARCH_1: case PROBCUT: - cur++; + ++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) + if (pos.see_sign(move) >= VALUE_ZERO) return move; // Losing capture, move it to the tail of the array @@ -308,9 +328,9 @@ Move MovePicker::next_move() { case KILLERS_S1: move = (cur++)->move; if ( move != MOVE_NONE - && pos.is_pseudo_legal(move) + && pos.pseudo_legal(move) && move != ttMove - && !pos.is_capture(move)) + && !pos.capture(move)) return move; break; @@ -318,7 +338,11 @@ Move MovePicker::next_move() { 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; @@ -361,6 +385,6 @@ 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 should be lock protected by the caller. +/// safe so must be lock protected by the caller. template<> -Move MovePicker::next_move() { return ss->sp->mp->next_move(); } +Move MovePicker::next_move() { return ss->splitPoint->movePicker->next_move(); }