X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovepick.cpp;h=63f77dbaebfc14570cb4ff56408348fa4b15adb0;hp=4479c321cbba8c8fd7b4ced8e716c434ffd7fbdc;hb=6776f76d20a205b19eb8f5c000debe9df9094bb3;hpb=e59d053984466dcea45cdbb60157a32acf132028 diff --git a/src/movepick.cpp b/src/movepick.cpp index 4479c321..63f77dba 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) 2008-2009 Marco Costalba + Copyright (C) 2008-2010 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 @@ -70,34 +70,49 @@ namespace { /// 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) : pos(p), H(h) { +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; - finished = false; + badCaptureThreshold = 0; lastBadCapture = badCaptures; + pinned = p.pinned_pieces(pos.side_to_move()); + if (ss && !p.is_check()) { - ttMoves[1].move = (ss->mateKiller == ttm)? MOVE_NONE : ss->mateKiller; + 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]; } else ttMoves[1].move = killers[0].move = killers[1].move = MOVE_NONE; - pinned = p.pinned_pieces(pos.side_to_move()); - if (p.is_check()) phasePtr = EvasionsPhaseTable; else if (d > Depth(0)) + { + // Consider sligtly negative captures as good if at low + // depth and far from beta. + if (ss && ss->eval < beta - PawnValueMidgame && d < 3 * OnePly) + badCaptureThreshold = -PawnValueMidgame; + phasePtr = MainSearchPhaseTable; + } else if (d == Depth(0)) phasePtr = QsearchWithChecksPhaseTable; else + { phasePtr = QsearchWithoutChecksPhaseTable; - phasePtr += !searchTT - 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 != MOVE_NONE && !pos.move_is_capture_or_promotion(ttm)) + searchTT = ttMoves[0].move = MOVE_NONE; + } + + phasePtr += int(!searchTT) - 1; go_next_phase(); } @@ -129,7 +144,7 @@ void MovePicker::go_next_phase() { case PH_NONCAPTURES: lastMove = generate_noncaptures(pos, moves); score_noncaptures(); - sort_moves(moves, lastMove); + sort_moves(moves, lastMove, &lastGoodNonCapture); return; case PH_BAD_CAPTURES: @@ -142,7 +157,7 @@ void MovePicker::go_next_phase() { case PH_EVASIONS: assert(pos.is_check()); lastMove = generate_evasions(pos, moves); - score_evasions(); + score_evasions_or_checks(); return; case PH_QCAPTURES: @@ -151,12 +166,12 @@ void MovePicker::go_next_phase() { return; case PH_QCHECKS: - // Perhaps we should order moves move here? FIXME lastMove = generate_non_capture_checks(pos, moves); + score_evasions_or_checks(); return; case PH_STOP: - lastMove = curMove + 1; // hack to be friendly for get_next_move() + lastMove = curMove + 1; // Avoids another go_next_phase() call return; default: @@ -216,16 +231,16 @@ void MovePicker::score_noncaptures() { piece = pos.piece_on(from); hs = H.move_ordering_score(piece, to); - // Ensure history is always preferred to pst + // Ensure history has always highest priority if (hs > 0) - hs += 1000; + hs += 10000; - // pst based scoring - cur->score = hs + pos.pst_delta(piece, from, to); + // Gain table based scoring + cur->score = hs + 16 * H.gain(piece, to); } } -void MovePicker::score_evasions() { +void MovePicker::score_evasions_or_checks() { // 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 @@ -233,11 +248,15 @@ void MovePicker::score_evasions() { Move m; int seeScore; + // Skip if we don't have at least two moves to order + if (lastMove < moves + 2) + return; + for (MoveStack* cur = moves; cur != lastMove; cur++) { m = cur->move; if ((seeScore = pos.see_sign(m)) < 0) - cur->score = seeScore; + cur->score = seeScore - HistoryMax; // Be sure 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)) + HistoryMax; @@ -251,6 +270,8 @@ void MovePicker::score_evasions() { /// 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() { @@ -277,7 +298,7 @@ Move MovePicker::get_next_move() { { // Check for a non negative SEE now int seeValue = pos.see_sign(move); - if (seeValue >= 0) + if (seeValue >= badCaptureThreshold) return move; // Losing capture, move it to the badCaptures[] array, note @@ -292,14 +313,19 @@ Move MovePicker::get_next_move() { case PH_KILLERS: move = (curMove++)->move; if ( move != MOVE_NONE + && move_is_legal(pos, move, pinned) && move != ttMoves[0].move && move != ttMoves[1].move - && move_is_legal(pos, move, pinned) && !pos.move_is_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 @@ -340,21 +366,3 @@ Move MovePicker::get_next_move() { } } -/// 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. - -Move MovePicker::get_next_move(Lock &lock) { - - lock_grab(&lock); - if (finished) - { - lock_release(&lock); - return MOVE_NONE; - } - Move m = get_next_move(); - if (m == MOVE_NONE) - finished = true; - - lock_release(&lock); - return m; -}