X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovepick.cpp;h=f3e094c6517c67fecc4b883e08f0d414105790ee;hp=06ea5e25d2da257d57a1668e0ed3d2c10aa6384d;hb=216972186ea861c99d3a7bccabfff842ef87933c;hpb=d9c7cad6302ddeff9f8a32a3fe66359c556a868e diff --git a/src/movepick.cpp b/src/movepick.cpp index 06ea5e25..f3e094c6 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) 2008-2014 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 @@ -35,7 +35,7 @@ namespace { STOP }; - // Our insertion sort, guaranteed to be stable, as is needed + // Our insertion sort, which is guaranteed (and also needed) to be stable void insertion_sort(ExtMove* begin, ExtMove* end) { ExtMove tmp, *p, *q; @@ -50,12 +50,12 @@ 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. + // ones so as to sort the two sets separately, 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. + // 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)); @@ -65,19 +65,20 @@ 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()) @@ -105,7 +106,7 @@ MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const HistoryStats& { 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.capture_or_promotion(ttm)) @@ -129,7 +130,8 @@ MovePicker::MovePicker(const Position& p, Move ttm, const HistoryStats& h, Piece 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); @@ -140,15 +142,6 @@ MovePicker::MovePicker(const Position& p, Move ttm, const HistoryStats& h, Piece } -/// stage_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::stage_moves() const { - assert(stage == KILLERS_S1 || stage == QUIETS_1_S1 || stage == QUIETS_2_S1); - return stage == KILLERS_S1 ? killers : moves; -} - - /// score() assign a numerical move ordering score to each move in a move list. /// The moves with highest scores will be picked first. template<> @@ -162,10 +155,10 @@ 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). + // 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 (ExtMove* it = moves; it != end; ++it) @@ -238,15 +231,28 @@ void MovePicker::generate_next() { 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; // Be sure countermoves are different from killers for (int i = 0; i < 2; ++i) - if (countermoves[i] != cur->move && countermoves[i] != (cur+1)->move) + if ( countermoves[i] != (cur+0)->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; + // 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]; + + if (followupmoves[1] && followupmoves[1] == followupmoves[0]) // Due to SMP races + (--end)->move = MOVE_NONE; + return; case QUIETS_1_S1: @@ -292,9 +298,9 @@ 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 +/// 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 returning the ttMove if has already been searched previously. +/// taking care not to return the ttMove if it has already been searched. template<> Move MovePicker::next_move() { @@ -338,7 +344,9 @@ Move MovePicker::next_move() { && move != killers[0].move && move != killers[1].move && move != killers[2].move - && move != killers[3].move) + && move != killers[3].move + && move != killers[4].move + && move != killers[5].move) return move; break;