X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovepick.cpp;h=51d85192a7c4df8b9c0cfdd0ea0c3adfb7b9ff13;hp=3d44721b687059b9f8a284759112f7299732a0f4;hb=8dd6875240e05dbcc1fb6467ffb11ad360aa474c;hpb=42b77ea7eecaf5f31bf87c7075945273685aa4f5 diff --git a/src/movepick.cpp b/src/movepick.cpp index 3d44721b..51d85192 100644 --- a/src/movepick.cpp +++ b/src/movepick.cpp @@ -2,13 +2,13 @@ Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2015-2018 Marco Costalba, Joona Kiiski, Gary Linscott, 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 the Free Software Foundation, either version 3 of the License, or (at your option) any later version. - Stockfish is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the @@ -21,41 +21,38 @@ #include #include "movepick.h" -#include "thread.h" namespace { enum Stages { - MAIN_SEARCH, GOOD_CAPTURES, KILLERS, GOOD_QUIETS, BAD_QUIETS, BAD_CAPTURES, - EVASION, ALL_EVASIONS, - QSEARCH_WITH_CHECKS, QCAPTURES_1, CHECKS, - QSEARCH_WITHOUT_CHECKS, QCAPTURES_2, - PROBCUT, PROBCUT_CAPTURES, - RECAPTURE, RECAPTURES, - STOP + MAIN_SEARCH, CAPTURES_INIT, GOOD_CAPTURES, KILLERS, COUNTERMOVE, QUIET_INIT, QUIET, BAD_CAPTURES, + EVASION, EVASIONS_INIT, ALL_EVASIONS, + PROBCUT, PROBCUT_CAPTURES_INIT, PROBCUT_CAPTURES, + QSEARCH, QCAPTURES_INIT, QCAPTURES, QCHECKS, QSEARCH_RECAPTURES, QRECAPTURES }; - // Our insertion sort, which is guaranteed to be stable, as it should be - 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; - } + // partial_insertion_sort() sorts moves in descending order up to and including + // a given limit. The order of moves smaller than the limit is left unspecified. + void partial_insertion_sort(ExtMove* begin, ExtMove* end, int limit) { + + for (ExtMove *sortedEnd = begin, *p = begin + 1; p < end; ++p) + if (p->value >= limit) + { + ExtMove tmp = *p, *q; + *p = *++sortedEnd; + for (q = sortedEnd; q != begin && *(q - 1) < tmp; --q) + *q = *(q - 1); + *q = tmp; + } } // pick_best() finds 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. the possible captures. - Move pick_best(ExtMove* begin, ExtMove* end) - { - std::swap(*begin, *std::max_element(begin, end)); - return *begin; + // are few moves, e.g., the possible captures. + Move pick_best(ExtMove* begin, ExtMove* end) { + + std::swap(*begin, *std::max_element(begin, end)); + return *begin; } } // namespace @@ -64,266 +61,252 @@ namespace { /// 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 +/// 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, - const CounterMovesHistoryStats& cmh, Move cm, Search::Stack* s) - : pos(p), history(h), counterMovesHistory(cmh), ss(s), countermove(cm), depth(d) { +/// MovePicker constructor for the main search +MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHistory* mh, + const CapturePieceToHistory* cph, const PieceToHistory** ch, Move cm, Move* killers_p) + : pos(p), mainHistory(mh), captureHistory(cph), contHistory(ch), countermove(cm), + killers{killers_p[0], killers_p[1]}, depth(d){ assert(d > DEPTH_ZERO); stage = pos.checkers() ? EVASION : MAIN_SEARCH; ttMove = ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE; - endMoves += (ttMove != MOVE_NONE); + stage += (ttMove == MOVE_NONE); } -MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const HistoryStats& h, - const CounterMovesHistoryStats& cmh, Square s) - : pos(p), history(h), counterMovesHistory(cmh) { +/// MovePicker constructor for quiescence search +MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHistory* mh, const CapturePieceToHistory* cph, Square s) + : pos(p), mainHistory(mh), captureHistory(cph), depth(d) { assert(d <= DEPTH_ZERO); if (pos.checkers()) stage = EVASION; - else if (d > DEPTH_QS_NO_CHECKS) - stage = QSEARCH_WITH_CHECKS; - else if (d > DEPTH_QS_RECAPTURES) - stage = QSEARCH_WITHOUT_CHECKS; + stage = QSEARCH; else { - stage = RECAPTURE; + stage = QSEARCH_RECAPTURES; recaptureSquare = s; - ttm = MOVE_NONE; + return; } ttMove = ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE; - endMoves += (ttMove != MOVE_NONE); + stage += (ttMove == MOVE_NONE); } -MovePicker::MovePicker(const Position& p, Move ttm, const HistoryStats& h, - const CounterMovesHistoryStats& cmh, Value th) - : pos(p), history(h), counterMovesHistory(cmh), threshold(th) { +/// MovePicker constructor for ProbCut: we generate captures with SEE higher +/// than or equal to the given threshold. +MovePicker::MovePicker(const Position& p, Move ttm, Value th, const CapturePieceToHistory* cph) + : pos(p), captureHistory(cph), threshold(th) { assert(!pos.checkers()); stage = PROBCUT; - - // In ProbCut we generate captures with SEE higher than the given threshold ttMove = ttm && pos.pseudo_legal(ttm) && pos.capture(ttm) - && pos.see(ttm) > threshold ? ttm : MOVE_NONE; + && pos.see_ge(ttm, threshold) ? ttm : MOVE_NONE; - endMoves += (ttMove != MOVE_NONE); + stage += (ttMove == MOVE_NONE); } +/// score() assigns a numerical value to each move in a list, used for sorting. +/// Captures are ordered by Most Valuable Victim (MVV), preferring captures +/// with a good history. Quiets are ordered using the histories. +template +void MovePicker::score() { -/// score() assigns 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, preferring - // captures near our home rank. Suprisingly, this appears to perform slightly - // better than SEE based move ordering: 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 the - // badCaptures[] array, but instead of doing it now we delay until the move - // has been picked up, saving some SEE calls in case we get a cutoff. - for (auto& m : *this) - m.value = PieceValue[MG][pos.piece_on(to_sq(m))] - - Value(200 * relative_rank(pos.side_to_move(), to_sq(m))); -} - -template<> -void MovePicker::score() { - - Square prevSq = to_sq((ss-1)->currentMove); - const HistoryStats& cmh = counterMovesHistory[pos.piece_on(prevSq)][prevSq]; - - for (auto& m : *this) - m.value = history[pos.moved_piece(m)][to_sq(m)] - + cmh[pos.moved_piece(m)][to_sq(m)] * 3; -} - -template<> -void MovePicker::score() { - // Try winning and equal captures captures ordered by MVV/LVA, then non-captures - // ordered by history value, then bad-captures and quiet moves with a negative - // SEE ordered by SEE value. - Value see; + static_assert(Type == CAPTURES || Type == QUIETS || Type == EVASIONS, "Wrong type"); for (auto& m : *this) - if ((see = pos.see_sign(m)) < VALUE_ZERO) - m.value = see - HistoryStats::Max; // At the bottom - - else if (pos.capture(m)) + if (Type == CAPTURES) m.value = PieceValue[MG][pos.piece_on(to_sq(m))] - - Value(type_of(pos.moved_piece(m))) + HistoryStats::Max; - else - m.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() { - - assert(stage != STOP); - - cur = moves; - - switch (++stage) { - - case GOOD_CAPTURES: case QCAPTURES_1: case QCAPTURES_2: - case PROBCUT_CAPTURES: case RECAPTURES: - endMoves = generate(pos, moves); - score(); - break; - - case KILLERS: - killers[0] = ss->killers[0]; - killers[1] = ss->killers[1]; - killers[2] = countermove; - cur = killers; - endMoves = cur + 2 + (countermove != killers[0] && countermove != killers[1]); - break; - - case GOOD_QUIETS: - endQuiets = endMoves = generate(pos, moves); - score(); - endMoves = std::partition(cur, endMoves, [](const ExtMove& m) { return m.value > VALUE_ZERO; }); - insertion_sort(cur, endMoves); - break; - - case BAD_QUIETS: - cur = endMoves; - endMoves = endQuiets; - if (depth >= 3 * ONE_PLY) - insertion_sort(cur, endMoves); - break; - - case BAD_CAPTURES: - // Just pick them in reverse order to get correct ordering - cur = moves + MAX_MOVES - 1; - endMoves = endBadCaptures; - break; - - case ALL_EVASIONS: - endMoves = generate(pos, moves); - if (endMoves - moves > 1) - score(); - break; - - case CHECKS: - endMoves = generate(pos, moves); - break; - - case EVASION: case QSEARCH_WITH_CHECKS: case QSEARCH_WITHOUT_CHECKS: - case PROBCUT: case RECAPTURE: case STOP: - stage = STOP; - break; - - default: - assert(false); - } + + Value((*captureHistory)[pos.moved_piece(m)][to_sq(m)][type_of(pos.piece_on(to_sq(m)))]); + + else if (Type == QUIETS) + m.value = (*mainHistory)[pos.side_to_move()][from_to(m)] + + (*contHistory[0])[pos.moved_piece(m)][to_sq(m)] + + (*contHistory[1])[pos.moved_piece(m)][to_sq(m)] + + (*contHistory[3])[pos.moved_piece(m)][to_sq(m)]; + + else // Type == EVASIONS + { + if (pos.capture(m)) + m.value = PieceValue[MG][pos.piece_on(to_sq(m))] + - Value(type_of(pos.moved_piece(m))); + else + m.value = (*mainHistory)[pos.side_to_move()][from_to(m)] - (1 << 28); + } } - /// 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 MovePicker::next_move(bool skipQuiets) { Move move; - while (true) - { - while (cur == endMoves && stage != STOP) - generate_next_stage(); + switch (stage) { - switch (stage) { + case MAIN_SEARCH: case EVASION: case QSEARCH: case PROBCUT: + ++stage; + return ttMove; - case MAIN_SEARCH: case EVASION: case QSEARCH_WITH_CHECKS: - case QSEARCH_WITHOUT_CHECKS: case PROBCUT: - ++cur; - return ttMove; + case CAPTURES_INIT: + case PROBCUT_CAPTURES_INIT: + case QCAPTURES_INIT: + case QSEARCH_RECAPTURES: + endBadCaptures = cur = moves; + endMoves = generate(pos, cur); + score(); + ++stage; + + // Rebranch at the top of the switch via a recursive call + return next_move(skipQuiets); - case GOOD_CAPTURES: + case GOOD_CAPTURES: + while (cur < endMoves) + { move = pick_best(cur++, endMoves); if (move != ttMove) { - if (pos.see_sign(move) >= VALUE_ZERO) + if (pos.see_ge(move, Value(-55 * (cur-1)->value / 1024))) return move; - // Losing capture, move it to the tail of the array - *endBadCaptures-- = move; + // Losing capture, move it to the beginning of the array + *endBadCaptures++ = move; } - break; + } - case KILLERS: - move = *cur++; - if ( move != MOVE_NONE - && move != ttMove - && pos.pseudo_legal(move) - && !pos.capture(move)) - return move; - break; + ++stage; + move = killers[0]; // First killer move + if ( move != MOVE_NONE + && move != ttMove + && pos.pseudo_legal(move) + && !pos.capture(move)) + return move; + /* fallthrough */ - case GOOD_QUIETS: case BAD_QUIETS: - move = *cur++; - if ( move != ttMove - && move != killers[0] - && move != killers[1] - && move != killers[2]) - return move; - break; + case KILLERS: + ++stage; + move = killers[1]; // Second killer move + if ( move != MOVE_NONE + && move != ttMove + && pos.pseudo_legal(move) + && !pos.capture(move)) + return move; + /* fallthrough */ + + case COUNTERMOVE: + ++stage; + move = countermove; + if ( move != MOVE_NONE + && move != ttMove + && move != killers[0] + && move != killers[1] + && pos.pseudo_legal(move) + && !pos.capture(move)) + return move; + /* fallthrough */ + + case QUIET_INIT: + cur = endBadCaptures; + endMoves = generate(pos, cur); + score(); + partial_insertion_sort(cur, endMoves, -4000 * depth / ONE_PLY); + ++stage; + /* fallthrough */ + + case QUIET: + if (!skipQuiets) + while (cur < endMoves) + { + move = *cur++; + + if ( move != ttMove + && move != killers[0] + && move != killers[1] + && move != countermove) + return move; + } + ++stage; + cur = moves; // Point to beginning of bad captures + /* fallthrough */ + + case BAD_CAPTURES: + if (cur < endBadCaptures) + return *cur++; + break; - case BAD_CAPTURES: - return *cur--; + case EVASIONS_INIT: + cur = moves; + endMoves = generate(pos, cur); + score(); + ++stage; + /* fallthrough */ - case ALL_EVASIONS: case QCAPTURES_1: case QCAPTURES_2: + case ALL_EVASIONS: + while (cur < endMoves) + { move = pick_best(cur++, endMoves); if (move != ttMove) return move; - break; - - case PROBCUT_CAPTURES: - move = pick_best(cur++, endMoves); - if (move != ttMove && pos.see(move) > threshold) - return move; - break; + } + break; - case RECAPTURES: + case PROBCUT_CAPTURES: + while (cur < endMoves) + { move = pick_best(cur++, endMoves); - if (to_sq(move) == recaptureSquare) + if ( move != ttMove + && pos.see_ge(move, threshold)) return move; - break; + } + break; - case CHECKS: - move = *cur++; + case QCAPTURES: + while (cur < endMoves) + { + move = pick_best(cur++, endMoves); if (move != ttMove) return move; + } + if (depth <= DEPTH_QS_NO_CHECKS) break; + cur = moves; + endMoves = generate(pos, cur); + ++stage; + /* fallthrough */ + + case QCHECKS: + while (cur < endMoves) + { + move = cur++->move; + if (move != ttMove) + return move; + } + break; - case STOP: - return MOVE_NONE; - - default: - assert(false); + case QRECAPTURES: + while (cur < endMoves) + { + move = *cur++; + if (to_sq(move) == recaptureSquare) + return move; } - } -} + break; + default: + assert(false); + } -/// 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(); } + return MOVE_NONE; +}