From: Joost VandeVondele Date: Sun, 18 Mar 2018 23:56:19 +0000 (+0100) Subject: Join common code in the stages of next_move() X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=bd59560480cc4f43a4ba75dc827ba27bcebb92dd Join common code in the stages of next_move() Rewrite the MovePicker class using lambda expressions for move filtering. Includes code style changes by @mcostalba. Verified for speed, passed STC: LLR: 2.95 (-2.94,2.94) [-3.00,1.00] Total: 43191 W: 9391 L: 9312 D: 24488 http://tests.stockfishchess.org/tests/view/5a99b9df0ebc590297cc8f04 This rewrite of MovePicker.cpp seems to trigger less random crashes on Ryzen machines than the version in previous master (reported by Bojun Guo). Closes https://github.com/official-stockfish/Stockfish/pull/1454 No functional change. --- diff --git a/src/movepick.cpp b/src/movepick.cpp index d7d3377c..c013042a 100644 --- a/src/movepick.cpp +++ b/src/movepick.cpp @@ -25,12 +25,15 @@ namespace { enum Stages { - MAIN_SEARCH, CAPTURES_INIT, GOOD_CAPTURES, KILLER0, KILLER1, COUNTERMOVE, QUIET_INIT, QUIET, BAD_CAPTURES, - EVASION, EVASIONS_INIT, ALL_EVASIONS, - PROBCUT, PROBCUT_CAPTURES_INIT, PROBCUT_CAPTURES, - QSEARCH, QCAPTURES_INIT, QCAPTURES, QCHECKS + MAIN_TT, CAPTURE_INIT, GOOD_CAPTURE, KILLER0, KILLER1, COUNTERMOVE, QUIET_INIT, QUIET, BAD_CAPTURE, + EVASION_TT, EVASION_INIT, EVASION, + PROBCUT_TT, PROBCUT_INIT, PROBCUT, + QSEARCH_TT, QCAPTURE_INIT, QCAPTURE, QCHECK_INIT, QCHECK }; + // Helper filter used with select_move() + 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) { @@ -46,15 +49,6 @@ namespace { } } - // 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; - } - } // namespace @@ -72,18 +66,19 @@ MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHist assert(d > DEPTH_ZERO); - 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 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), recaptureSquare(s), depth(d) { +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); - stage = pos.checkers() ? EVASION : QSEARCH; + stage = pos.checkers() ? EVASION_TT : QSEARCH_TT; ttMove = ttm && pos.pseudo_legal(ttm) && (depth > DEPTH_QS_RECAPTURES || to_sq(ttm) == recaptureSquare) ? ttm : MOVE_NONE; @@ -97,7 +92,7 @@ MovePicker::MovePicker(const Position& p, Move ttm, Value th, const CapturePiece assert(!pos.checkers()); - stage = PROBCUT; + stage = PROBCUT_TT; ttMove = ttm && pos.pseudo_legal(ttm) && pos.capture(ttm) @@ -105,9 +100,9 @@ MovePicker::MovePicker(const Position& p, Move ttm, Value th, const CapturePiece 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. +/// 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() { @@ -134,57 +129,58 @@ void MovePicker::score() { } } -/// 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. +/// MovePicker::select_move() returns the next move satisfying a predicate function +template +Move MovePicker::select_move(Pred filter) { -Move MovePicker::next_move(bool skipQuiets) { + while (cur < endMoves) + { + if (T == BEST_SCORE) + std::swap(*cur, *std::max_element(cur, endMoves)); - Move move; + move = *cur++; -begin_switch: + 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. It picks 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: - case PROBCUT: + case MAIN_TT: + case EVASION_TT: + case QSEARCH_TT: + case PROBCUT_TT: ++stage; return ttMove; - case CAPTURES_INIT: - case PROBCUT_CAPTURES_INIT: - case QCAPTURES_INIT: + case CAPTURE_INIT: + case PROBCUT_INIT: + case QCAPTURE_INIT: endBadCaptures = cur = moves; endMoves = generate(pos, cur); score(); ++stage; + goto top; - // Rebranch at the top of the switch - goto begin_switch; - - case GOOD_CAPTURES: - while (cur < endMoves) - { - move = pick_best(cur++, endMoves); - if (move != ttMove) - { - if (pos.see_ge(move, Value(-55 * (cur-1)->value / 1024))) - return move; - - // Losing capture, move it to the beginning of the array - *endBadCaptures++ = move; - } - } - ++stage; + case GOOD_CAPTURE: + if (select_move([&](){ 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; // If the countermove is the same as a killer, skip it if ( refutations[0] == refutations[2] || refutations[1] == refutations[2]) - refutations[2] = MOVE_NONE; - + refutations[2] = MOVE_NONE; + ++stage; /* fallthrough */ case KILLER0: @@ -192,7 +188,7 @@ begin_switch: case COUNTERMOVE: while (stage <= COUNTERMOVE) { - move = refutations[ stage++ - KILLER0 ]; + move = refutations[ stage++ - KILLER0]; if ( move != MOVE_NONE && move != ttMove && pos.pseudo_legal(move) @@ -210,78 +206,55 @@ begin_switch: /* fallthrough */ case QUIET: - if (!skipQuiets) - while (cur < endMoves) - { - move = *cur++; - if ( move != ttMove - && move != refutations[0] - && move != refutations[1] - && move != refutations[2]) - return move; - } + if ( !skipQuiets + && select_move([&](){return move != refutations[0] + && move != refutations[1] + && move != refutations[2];})) + return move; + + // Point to beginning and end of 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_move(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_move(Any); - case PROBCUT_CAPTURES: - while (cur < endMoves) - { - move = pick_best(cur++, endMoves); - if ( move != ttMove - && pos.see_ge(move, threshold)) - return move; - } - break; + case PROBCUT: + return select_move([&](){ return pos.see_ge(move, threshold); }); - case QCAPTURES: - while (cur < endMoves) - { - move = pick_best(cur++, endMoves); - if ( move != ttMove - && (depth > DEPTH_QS_RECAPTURES || to_sq(move) == recaptureSquare)) - return move; - } - if (depth <= DEPTH_QS_NO_CHECKS) - break; + case QCAPTURE: + if (select_move([&](){ 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; + + ++stage; + /* fallthrough */ + + case QCHECK_INIT: cur = moves; endMoves = generate(pos, cur); ++stage; /* fallthrough */ - case QCHECKS: - while (cur < endMoves) - { - move = *cur++; - if (move != ttMove) - return move; - } - break; - - default: - assert(false); + case QCHECK: + return select_move(Any); } - return MOVE_NONE; + assert(false); + return MOVE_NONE; // Silence warning } diff --git a/src/movepick.h b/src/movepick.h index f9403f0f..0ad72933 100644 --- a/src/movepick.h +++ b/src/movepick.h @@ -49,7 +49,7 @@ public: void operator<<(int bonus) { assert(abs(bonus) <= D); // Ensure range is [-W * D, W * D] - assert(abs(W * D) < std::numeric_limits::max()); // Ensure we don't overflow + assert(W * D < std::numeric_limits::max()); // Ensure we don't overflow entry += bonus * W - entry * abs(bonus) / D; @@ -110,6 +110,8 @@ typedef Stats ContinuationHi /// beta algorithm, MovePicker attempts to return the moves which are most likely /// to get a cut-off first. +enum PickType { NEXT, BEST_SCORE }; + class MovePicker { public: MovePicker(const MovePicker&) = delete; @@ -120,6 +122,7 @@ public: Move next_move(bool skipQuiets = false); private: + template Move select_move(Pred); template void score(); ExtMove* begin() { return cur; } ExtMove* end() { return endMoves; } @@ -131,6 +134,7 @@ private: Move ttMove, refutations[3]; ExtMove *cur, *endMoves, *endBadCaptures; int stage; + Move move; Square recaptureSquare; Value threshold; Depth depth;