X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovepick.cpp;h=e1042ea6005f0255ccb1f4b21f809e0f0e4a3b84;hp=c187c3ad6ee8a914ea9eb0904e89cc8dbff47374;hb=2af2c67650c4ac2531e6ab2753830f91c0999876;hpb=3686e719a14a49f54bff00b3df153e044a0206ab diff --git a/src/movepick.cpp b/src/movepick.cpp index c187c3ad..e1042ea6 100644 --- a/src/movepick.cpp +++ b/src/movepick.cpp @@ -2,7 +2,7 @@ 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) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, 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 @@ -21,40 +21,32 @@ #include #include "movepick.h" -#include "thread.h" namespace { enum Stages { - MAIN_SEARCH, CAPTURES_INIT, GOOD_CAPTURES, KILLERS, COUNTERMOVE, QUIET_INIT, QUIET, BAD_CAPTURES, - EVASION, EVASIONS_INIT, ALL_EVASIONS, - PROBCUT, PROBCUT_INIT, PROBCUT_CAPTURES, - QSEARCH_WITH_CHECKS, QCAPTURES_1_INIT, QCAPTURES_1, QCHECKS, - QSEARCH_NO_CHECKS, QCAPTURES_2_INIT, QCAPTURES_2, - QSEARCH_RECAPTURES, QRECAPTURES + MAIN_TT, CAPTURE_INIT, GOOD_CAPTURE, REFUTATION, QUIET_INIT, QUIET, BAD_CAPTURE, + EVASION_TT, EVASION_INIT, EVASION, + PROBCUT_TT, PROBCUT_INIT, PROBCUT, + QSEARCH_TT, QCAPTURE_INIT, QCAPTURE, QCHECK_INIT, QCHECK }; - // 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; - } - } - - // 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; + // Helper filter used with select() + const auto Any = [](){ return true; }; + + // 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; + } } } // namespace @@ -66,285 +58,210 @@ namespace { /// 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, Search::Stack* s) - : pos(p), ss(s), 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) + : pos(p), mainHistory(mh), captureHistory(cph), contHistory(ch), + refutations{{killers[0], 0}, {killers[1], 0}, {cm, 0}}, depth(d) { assert(d > DEPTH_ZERO); - Square prevSq = to_sq((ss-1)->currentMove); - countermove = pos.this_thread()->counterMoves[pos.piece_on(prevSq)][prevSq]; - - stage = pos.checkers() ? EVASION : MAIN_SEARCH; + stage = pos.checkers() ? EVASION_TT : MAIN_TT; ttMove = ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE; stage += (ttMove == MOVE_NONE); } -MovePicker::MovePicker(const Position& p, Move ttm, Depth d, Square s) - : pos(p) { +/// MovePicker constructor for quiescence search +MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHistory* mh, + const CapturePieceToHistory* cph, Square rs) + : pos(p), mainHistory(mh), captureHistory(cph), recaptureSquare(rs), 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_NO_CHECKS; - - else - { - stage = QSEARCH_RECAPTURES; - recaptureSquare = s; - return; - } - - ttMove = ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE; + stage = pos.checkers() ? EVASION_TT : QSEARCH_TT; + ttMove = ttm + && pos.pseudo_legal(ttm) + && (depth > DEPTH_QS_RECAPTURES || to_sq(ttm) == recaptureSquare) ? ttm : MOVE_NONE; stage += (ttMove == MOVE_NONE); } -MovePicker::MovePicker(const Position& p, Move ttm, Value th) - : pos(p), threshold(th) { +/// MovePicker constructor for ProbCut: we generate captures with SEE greater +/// 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 + stage = PROBCUT_TT; ttMove = ttm && pos.pseudo_legal(ttm) && pos.capture(ttm) - && pos.see_ge(ttm, threshold + 1)? ttm : MOVE_NONE; - + && pos.see_ge(ttm, threshold) ? ttm : MOVE_NONE; stage += (ttMove == MOVE_NONE); } +/// MovePicker::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 moves 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. Surprisingly, 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 the 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() { - - const HistoryStats& history = pos.this_thread()->history; - const FromToStats& fromTo = pos.this_thread()->fromTo; - - const CounterMoveStats* cm = (ss-1)->counterMoves; - const CounterMoveStats* fm = (ss-2)->counterMoves; - const CounterMoveStats* f2 = (ss-4)->counterMoves; - - Color c = pos.side_to_move(); + static_assert(Type == CAPTURES || Type == QUIETS || Type == EVASIONS, "Wrong type"); for (auto& m : *this) - m.value = history[pos.moved_piece(m)][to_sq(m)] - + (cm ? (*cm)[pos.moved_piece(m)][to_sq(m)] : VALUE_ZERO) - + (fm ? (*fm)[pos.moved_piece(m)][to_sq(m)] : VALUE_ZERO) - + (f2 ? (*f2)[pos.moved_piece(m)][to_sq(m)] : VALUE_ZERO) - + fromTo.get(c, m); -} + if (Type == CAPTURES) + m.value = PieceValue[MG][pos.piece_on(to_sq(m))] + + (*captureHistory)[pos.moved_piece(m)][to_sq(m)][type_of(pos.piece_on(to_sq(m)))] / 16; -template<> -void MovePicker::score() { - // Try captures ordered by MVV/LVA, then non-captures ordered by history value - const HistoryStats& history = pos.this_thread()->history; - const FromToStats& fromTo = pos.this_thread()->fromTo; - Color c = pos.side_to_move(); + 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)]; - for (auto& m : *this) - if (pos.capture(m)) - 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)] + fromTo.get(c, 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); + } } +/// MovePicker::select() returns the next move satisfying a predicate function. +/// It never returns the TT move. +template +Move MovePicker::select(Pred filter) { -/// 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. + while (cur < endMoves) + { + if (T == Best) + std::swap(*cur, *std::max_element(cur, endMoves)); -Move MovePicker::next_move() { + move = *cur++; - Move move; + if (move != ttMove && filter()) + return move; + } + return move = MOVE_NONE; +} +/// 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, picking the move with the highest score from a list of generated moves. +Move MovePicker::next_move(bool skipQuiets) { + +top: switch (stage) { - case MAIN_SEARCH: case EVASION: case QSEARCH_WITH_CHECKS: - case QSEARCH_NO_CHECKS: case PROBCUT: + case MAIN_TT: + case EVASION_TT: + case QSEARCH_TT: + case PROBCUT_TT: ++stage; return ttMove; - case CAPTURES_INIT: - endBadCaptures = cur = moves; + case CAPTURE_INIT: + case PROBCUT_INIT: + case QCAPTURE_INIT: + cur = endBadCaptures = moves; endMoves = generate(pos, cur); + score(); ++stage; + goto top; - case GOOD_CAPTURES: - while (cur < endMoves) - { - move = pick_best(cur++, endMoves); - if (move != ttMove) - { - if (pos.see_ge(move, VALUE_ZERO)) - return move; - - // Losing capture, move it to the beginning of the array - *endBadCaptures++ = move; - } - } - - ++stage; - move = ss->killers[0]; // First killer move - if ( move != MOVE_NONE - && move != ttMove - && pos.pseudo_legal(move) - && !pos.capture(move)) + case GOOD_CAPTURE: + if (select([&](){ + return pos.see_ge(move, Value(-55 * (cur-1)->value / 1024)) ? + // Move losing capture to endBadCaptures to be tried later + true : (*endBadCaptures++ = move, false); })) return move; - case KILLERS: - ++stage; - move = ss->killers[1]; // Second killer move - if ( move != MOVE_NONE - && move != ttMove - && pos.pseudo_legal(move) - && !pos.capture(move)) - return move; + // Prepare the pointers to loop over the refutations array + cur = std::begin(refutations); + endMoves = std::end(refutations); + + // If the countermove is the same as a killer, skip it + if ( refutations[0].move == refutations[2].move + || refutations[1].move == refutations[2].move) + --endMoves; - case COUNTERMOVE: ++stage; - move = countermove; - if ( move != MOVE_NONE - && move != ttMove - && move != ss->killers[0] - && move != ss->killers[1] - && pos.pseudo_legal(move) - && !pos.capture(move)) + /* fallthrough */ + + case REFUTATION: + if (select([&](){ return move != MOVE_NONE + && !pos.capture(move) + && pos.pseudo_legal(move); })) return move; + ++stage; + /* fallthrough */ case QUIET_INIT: cur = endBadCaptures; endMoves = generate(pos, cur); + score(); - if (depth < 3 * ONE_PLY) - { - ExtMove* goodQuiet = std::partition(cur, endMoves, [](const ExtMove& m) - { return m.value > VALUE_ZERO; }); - insertion_sort(cur, goodQuiet); - } else - insertion_sort(cur, endMoves); + partial_insertion_sort(cur, endMoves, -4000 * depth / ONE_PLY); ++stage; + /* fallthrough */ case QUIET: - while (cur < endMoves) - { - move = *cur++; - if ( move != ttMove - && move != ss->killers[0] - && move != ss->killers[1] - && move != countermove) - return move; - } + if ( !skipQuiets + && select([&](){return move != refutations[0] + && move != refutations[1] + && move != refutations[2];})) + return move; + + // Prepare the pointers to loop over the bad captures + cur = moves; + endMoves = endBadCaptures; + ++stage; - cur = moves; // Point to beginning of bad captures + /* fallthrough */ - case BAD_CAPTURES: - if (cur < endBadCaptures) - return *cur++; - break; + case BAD_CAPTURE: + return select(Any); - case EVASIONS_INIT: + case EVASION_INIT: cur = moves; endMoves = generate(pos, cur); + score(); ++stage; + /* fallthrough */ - case ALL_EVASIONS: - while (cur < endMoves) - { - move = pick_best(cur++, endMoves); - if (move != ttMove) - return move; - } - break; + case EVASION: + return select(Any); - case PROBCUT_INIT: - cur = moves; - endMoves = generate(pos, cur); - score(); - ++stage; + case PROBCUT: + return select([&](){ return pos.see_ge(move, threshold); }); - case PROBCUT_CAPTURES: - while (cur < endMoves) - { - move = pick_best(cur++, endMoves); - if ( move != ttMove - && pos.see_ge(move, threshold + 1)) - return move; - } - break; + case QCAPTURE: + if (select([&](){ return depth > DEPTH_QS_RECAPTURES + || to_sq(move) == recaptureSquare; })) + return move; + + // If we did not find any move and we do not try checks, we have finished + if (depth != DEPTH_QS_CHECKS) + return MOVE_NONE; - case QCAPTURES_1_INIT: case QCAPTURES_2_INIT: - cur = moves; - endMoves = generate(pos, cur); - score(); ++stage; + /* fallthrough */ - case QCAPTURES_1: case QCAPTURES_2: - while (cur < endMoves) - { - move = pick_best(cur++, endMoves); - if (move != ttMove) - return move; - } - if (stage == QCAPTURES_2) - break; + case QCHECK_INIT: cur = moves; endMoves = generate(pos, cur); - ++stage; - case QCHECKS: - while (cur < endMoves) - { - move = cur++->move; - if (move != ttMove) - return move; - } - break; - - case QSEARCH_RECAPTURES: - cur = moves; - endMoves = generate(pos, cur); - score(); ++stage; + /* fallthrough */ - case QRECAPTURES: - while (cur < endMoves) - { - move = pick_best(cur++, endMoves); - if (to_sq(move) == recaptureSquare) - return move; - } - break; - - default: - assert(false); + case QCHECK: + return select(Any); } - return MOVE_NONE; + assert(false); + return MOVE_NONE; // Silence warning }