X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovepick.cpp;h=2e8eb665b9acd04573c9e438d77212f2888ccff6;hp=45d989c91a80bdb0755a3516f19b64e29668b844;hb=7733dadfd7c8781e3bde3cc4e21751fa44ab6ed8;hpb=9e4befe3f1ea324bece88aee2e97b38659411c52 diff --git a/src/movepick.cpp b/src/movepick.cpp index 45d989c9..2e8eb665 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 @@ -23,11 +23,9 @@ //// Includes //// -#include #include #include "history.h" -#include "evaluate.h" #include "movegen.h" #include "movepick.h" #include "search.h" @@ -40,15 +38,23 @@ namespace { - /// Variables + 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 + }; CACHE_LINE_ALIGNMENT - const MovegenPhaseT MainSearchPhaseTable[] = { PH_NULL_MOVE, PH_TT_MOVES, PH_GOOD_CAPTURES, PH_KILLERS, PH_NONCAPTURES, PH_BAD_CAPTURES, PH_STOP}; - const MovegenPhaseT MainSearchNoNullPhaseTable[] = { PH_TT_MOVES, PH_GOOD_CAPTURES, PH_KILLERS, PH_NONCAPTURES, PH_BAD_CAPTURES, PH_STOP}; - const MovegenPhaseT LowSearchPhaseTable[] = { PH_TT_MOVES, PH_GOOD_CAPTURES, PH_NULL_MOVE, PH_KILLERS, PH_NONCAPTURES, PH_BAD_CAPTURES, PH_STOP}; - const MovegenPhaseT EvasionsPhaseTable[] = { PH_EVASIONS, PH_STOP}; - const MovegenPhaseT QsearchWithChecksPhaseTable[] = { PH_TT_MOVES, PH_QCAPTURES, PH_QCHECKS, PH_STOP}; - const MovegenPhaseT QsearchWithoutChecksPhaseTable[] = { PH_TT_MOVES, PH_QCAPTURES, PH_STOP}; + const uint8_t MainSearchPhaseTable[] = { PH_TT_MOVES, PH_GOOD_CAPTURES, PH_KILLERS, PH_NONCAPTURES, PH_BAD_CAPTURES, PH_STOP}; + const uint8_t EvasionsPhaseTable[] = { PH_TT_MOVES, PH_EVASIONS, PH_STOP}; + const uint8_t QsearchWithChecksPhaseTable[] = { PH_TT_MOVES, PH_QCAPTURES, PH_QCHECKS, PH_STOP}; + const uint8_t QsearchWithoutChecksPhaseTable[] = { PH_TT_MOVES, PH_QCAPTURES, PH_STOP}; } @@ -57,44 +63,56 @@ namespace { //// -/// Constructor for the MovePicker class. Apart from the position for which +/// 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, bool useNullMove) : pos(p), H(h) { - ttMoves[0] = ttm; - if (ss) - { - ttMoves[1] = (ss->mateKiller == ttm)? MOVE_NONE : ss->mateKiller; - killers[0] = ss->killers[0]; - killers[1] = ss->killers[1]; - } else - ttMoves[1] = killers[0] = killers[1] = MOVE_NONE; - - numOfBadCaptures = 0; - finished = false; +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 + MOVES_MAX; - Color us = pos.side_to_move(); + pinned = p.pinned_pieces(pos.side_to_move()); - dc = p.discovered_check_candidates(us); - pinned = p.pinned_pieces(us); + if (ss && !p.is_check()) + { + 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; if (p.is_check()) phasePtr = EvasionsPhaseTable; - else if (d >= Depth(3 * OnePly)) - phasePtr = useNullMove ? MainSearchPhaseTable : MainSearchNoNullPhaseTable; - else if (d > Depth(0)) - phasePtr = useNullMove ? LowSearchPhaseTable : MainSearchNoNullPhaseTable; - else if (d == Depth(0)) + else if (d > DEPTH_ZERO) + { + // 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 = MainSearchPhaseTable; + } + else if (d == DEPTH_ZERO) phasePtr = QsearchWithChecksPhaseTable; else + { phasePtr = QsearchWithoutChecksPhaseTable; - phasePtr--; + // 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(); } @@ -108,54 +126,51 @@ void MovePicker::go_next_phase() { phase = *(++phasePtr); switch (phase) { - case PH_NULL_MOVE: case PH_TT_MOVES: - movesPicked = 0; + curMove = ttMoves; + lastMove = curMove + 2; return; case PH_GOOD_CAPTURES: lastMove = generate_captures(pos, moves); score_captures(); - std::sort(moves, lastMove); return; case PH_KILLERS: - movesPicked = 0; + curMove = killers; + lastMove = curMove + 2; return; case PH_NONCAPTURES: lastMove = generate_noncaptures(pos, moves); score_noncaptures(); - std::sort(moves, lastMove); + sort_moves(moves, lastMove, &lastGoodNonCapture); return; case PH_BAD_CAPTURES: - // Bad captures SEE value is already calculated so just sort them - // to get SEE move ordering. + // Bad captures SEE value is already calculated so just pick + // them in order to get SEE move ordering. curMove = badCaptures; - lastMove = badCaptures + numOfBadCaptures; - std::sort(badCaptures, lastMove); + lastMove = moves + MOVES_MAX; return; case PH_EVASIONS: assert(pos.is_check()); - lastMove = generate_evasions(pos, moves, pinned); + lastMove = generate_evasions(pos, moves); score_evasions(); - std::sort(moves, lastMove); return; case PH_QCAPTURES: lastMove = generate_captures(pos, moves); score_captures(); - std::sort(moves, lastMove); return; case PH_QCHECKS: - // Perhaps we should order moves move here? FIXME - lastMove = generate_non_capture_checks(pos, moves, dc); + lastMove = generate_non_capture_checks(pos, moves); return; case PH_STOP: + lastMove = curMove + 1; // Avoids another go_next_phase() call return; default: @@ -193,8 +208,8 @@ void MovePicker::score_captures() { if (move_is_promotion(m)) cur->score = QueenValueMidgame; else - cur->score = int(pos.midgame_value_of_piece_on(move_to(m))) - -int(pos.type_of_piece_on(move_from(m))); + cur->score = pos.midgame_value_of_piece_on(move_to(m)) + - pos.type_of_piece_on(move_from(m)); } } @@ -202,39 +217,42 @@ void MovePicker::score_noncaptures() { // First score by history, when no history is available then use // piece/square tables values. This seems to be better then a // random choice when we don't have an history for any move. + Move m; Piece piece; Square from, to; - int hs; for (MoveStack* cur = moves; cur != lastMove; cur++) { - from = move_from(cur->move); - to = move_to(cur->move); + m = cur->move; + from = move_from(m); + to = move_to(m); piece = pos.piece_on(from); - hs = H.move_ordering_score(piece, to); - - // Ensure history is always preferred to pst - if (hs > 0) - hs += 1000; - - // pst based scoring - cur->score = hs + pos.pst_delta(piece, from, to); + cur->score = H.value(piece, to) + H.gain(piece, to); } } 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. + 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++) { - Move m = cur->move; - if (m == ttMoves[0]) - cur->score = 2*HistoryMax; - else if (!pos.square_is_empty(move_to(m))) - { - int seeScore = pos.see(m); - cur->score = (seeScore >= 0)? seeScore + HistoryMax : seeScore; - } else - cur->score = H.move_ordering_score(pos.piece_on(move_from(m)), move_to(m)); + m = cur->move; + if ((seeScore = pos.see_sign(m)) < 0) + 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; + else + cur->score = H.value(pos.piece_on(move_from(m)), move_to(m)); } } @@ -242,124 +260,98 @@ void MovePicker::score_evasions() { /// 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 that has already been serched previously. +/// 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() { - assert(!pos.is_check() || *phasePtr == PH_EVASIONS || *phasePtr == PH_STOP); - assert( pos.is_check() || *phasePtr != PH_EVASIONS); + Move move; while (true) { - switch (phase) { - - case PH_NULL_MOVE: - go_next_phase(); - return MOVE_NULL; + while (curMove != lastMove) + { + switch (phase) { - case PH_TT_MOVES: - while (movesPicked < 2) - { - Move move = ttMoves[movesPicked++]; + case PH_TT_MOVES: + move = (curMove++)->move; if ( move != MOVE_NONE && move_is_legal(pos, move, pinned)) return move; - } - break; - - case PH_GOOD_CAPTURES: - while (curMove != lastMove) - { - Move move = (curMove++)->move; - if ( move != ttMoves[0] - && move != ttMoves[1] + break; + + case PH_GOOD_CAPTURES: + move = pick_best(curMove++, lastMove).move; + if ( move != ttMoves[0].move + && move != ttMoves[1].move && pos.pl_move_is_legal(move, pinned)) { // 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 + // Losing capture, move it to the tail of the array, note // that move has now been already checked for legality. - assert(numOfBadCaptures < 63); - badCaptures[numOfBadCaptures].move = move; - badCaptures[numOfBadCaptures++].score = seeValue; + (--badCaptures)->move = move; + badCaptures->score = seeValue; } - } - break; + break; - case PH_KILLERS: - while (movesPicked < 2) - { - Move move = killers[movesPicked++]; + case PH_KILLERS: + move = (curMove++)->move; if ( move != MOVE_NONE - && move != ttMoves[0] - && move != ttMoves[1] && move_is_legal(pos, move, pinned) + && move != ttMoves[0].move + && move != ttMoves[1].move && !pos.move_is_capture(move)) return move; - } - break; - - case PH_NONCAPTURES: - while (curMove != lastMove) - { - Move move = (curMove++)->move; - if ( move != ttMoves[0] - && move != ttMoves[1] - && move != killers[0] - && move != killers[1] + 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 + && move != killers[0].move + && move != killers[1].move && pos.pl_move_is_legal(move, pinned)) return move; - } - break; - - case PH_EVASIONS: - case PH_BAD_CAPTURES: - if (curMove != lastMove) - return (curMove++)->move; - break; - - case PH_QCAPTURES: - case PH_QCHECKS: - while (curMove != lastMove) - { - Move move = (curMove++)->move; - // Maybe postpone the legality check until after futility pruning? - if ( move != ttMoves[0] + break; + + case PH_BAD_CAPTURES: + move = pick_best(curMove++, lastMove).move; + return move; + + case PH_EVASIONS: + case PH_QCAPTURES: + move = pick_best(curMove++, lastMove).move; + if ( move != ttMoves[0].move && pos.pl_move_is_legal(move, pinned)) return move; - } - break; + break; + + case PH_QCHECKS: + move = (curMove++)->move; + if ( move != ttMoves[0].move + && pos.pl_move_is_legal(move, pinned)) + return move; + break; - case PH_STOP: - return MOVE_NONE; + case PH_STOP: + return MOVE_NONE; - default: - assert(false); - break; + default: + assert(false); + break; + } } go_next_phase(); } - return MOVE_NONE; } -/// 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; -}