X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=9562bf8640d4e8b04772d0e915281107e6218f97;hp=5d6babb45f716200c82dd30b2265d9857a0e81b3;hb=c390b734c451b3d976b331244e281d261b26ac3a;hpb=8a0af1004ae898f1f7a36a00705548cc255bec28 diff --git a/src/search.cpp b/src/search.cpp index 5d6babb4..9562bf86 100644 --- a/src/search.cpp +++ b/src/search.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) 2015-2019 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad + Copyright (C) 2015-2020 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 @@ -61,59 +61,104 @@ namespace { // Different node types, used as a template parameter enum NodeType { NonPV, PV }; + constexpr uint64_t ttHitAverageWindow = 4096; + constexpr uint64_t ttHitAverageResolution = 1024; + // Razor and futility margins - constexpr int RazorMargin = 600; + constexpr int RazorMargin = 531; Value futility_margin(Depth d, bool improving) { - return Value((175 - 50 * improving) * d / ONE_PLY); + return Value(217 * (d - improving)); } // Reductions lookup table, initialized at startup int Reductions[MAX_MOVES]; // [depth or moveNumber] Depth reduction(bool i, Depth d, int mn) { - int r = Reductions[d / ONE_PLY] * Reductions[mn] / 1024; - return ((r + 512) / 1024 + (!i && r > 1024)) * ONE_PLY; + int r = Reductions[d] * Reductions[mn]; + return (r + 511) / 1024 + (!i && r > 1007); } - constexpr int futility_move_count(bool improving, int depth) { - return (5 + depth * depth) * (1 + improving) / 2; + constexpr int futility_move_count(bool improving, Depth depth) { + return (5 + depth * depth) * (1 + improving) / 2 - 1; } // History and stats update bonus, based on depth - int stat_bonus(Depth depth) { - int d = depth / ONE_PLY; - return d > 17 ? 0 : 29 * d * d + 138 * d - 134; + int stat_bonus(Depth d) { + return d > 15 ? -8 : 19 * d * d + 155 * d - 132; } // Add a small random component to draw evaluations to avoid 3fold-blindness - Value value_draw(Depth depth, Thread* thisThread) { - return depth < 4 * ONE_PLY ? VALUE_DRAW - : VALUE_DRAW + Value(2 * (thisThread->nodes & 1) - 1); + Value value_draw(Thread* thisThread) { + return VALUE_DRAW + Value(2 * (thisThread->nodes & 1) - 1); } // Skill structure is used to implement strength limit struct Skill { explicit Skill(int l) : level(l) {} bool enabled() const { return level < 20; } - bool time_to_pick(Depth depth) const { return depth / ONE_PLY == 1 + level; } + bool time_to_pick(Depth depth) const { return depth == 1 + level; } Move pick_best(size_t multiPV); int level; Move best = MOVE_NONE; }; + // Breadcrumbs are used to mark nodes as being searched by a given thread + struct Breadcrumb { + std::atomic thread; + std::atomic key; + }; + std::array breadcrumbs; + + // ThreadHolding structure keeps track of which thread left breadcrumbs at the given + // node for potential reductions. A free node will be marked upon entering the moves + // loop by the constructor, and unmarked upon leaving that loop by the destructor. + struct ThreadHolding { + explicit ThreadHolding(Thread* thisThread, Key posKey, int ply) { + location = ply < 8 ? &breadcrumbs[posKey & (breadcrumbs.size() - 1)] : nullptr; + otherThread = false; + owning = false; + if (location) + { + // See if another already marked this location, if not, mark it ourselves + Thread* tmp = (*location).thread.load(std::memory_order_relaxed); + if (tmp == nullptr) + { + (*location).thread.store(thisThread, std::memory_order_relaxed); + (*location).key.store(posKey, std::memory_order_relaxed); + owning = true; + } + else if ( tmp != thisThread + && (*location).key.load(std::memory_order_relaxed) == posKey) + otherThread = true; + } + } + + ~ThreadHolding() { + if (owning) // Free the marked location + (*location).thread.store(nullptr, std::memory_order_relaxed); + } + + bool marked() { return otherThread; } + + private: + Breadcrumb* location; + bool otherThread, owning; + }; + template Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode); template - Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth = DEPTH_ZERO); + Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth = 0); Value value_to_tt(Value v, int ply); - Value value_from_tt(Value v, int ply); + Value value_from_tt(Value v, int ply, int r50c); void update_pv(Move* pv, Move move, Move* childPv); void update_continuation_histories(Stack* ss, Piece pc, Square to, int bonus); - void update_quiet_stats(const Position& pos, Stack* ss, Move move, Move* quiets, int quietCount, int bonus); - void update_capture_stats(const Position& pos, Move move, Move* captures, int captureCount, int bonus); + void update_quiet_stats(const Position& pos, Stack* ss, Move move, int bonus); + void update_all_stats(const Position& pos, Stack* ss, Move bestMove, Value bestValue, Value beta, Square prevSq, + Move* quietsSearched, int quietCount, Move* capturesSearched, int captureCount, Depth depth); // perft() is our utility to verify move generation. All the leaf nodes up // to the given depth are generated and counted, and the sum is returned. @@ -122,16 +167,16 @@ namespace { StateInfo st; uint64_t cnt, nodes = 0; - const bool leaf = (depth == 2 * ONE_PLY); + const bool leaf = (depth == 2); for (const auto& m : MoveList(pos)) { - if (Root && depth <= ONE_PLY) + if (Root && depth <= 1) cnt = 1, nodes++; else { pos.do_move(m, st); - cnt = leaf ? MoveList(pos).size() : perft(pos, depth - ONE_PLY); + cnt = leaf ? MoveList(pos).size() : perft(pos, depth - 1); nodes += cnt; pos.undo_move(m); } @@ -149,7 +194,7 @@ namespace { void Search::init() { for (int i = 1; i < MAX_MOVES; ++i) - Reductions[i] = int(1024 * std::log(i) / std::sqrt(1.95)); + Reductions[i] = int((24.8 + std::log(Threads.size()) / 2) * std::log(i)); } @@ -173,7 +218,7 @@ void MainThread::search() { if (Limits.perft) { - nodes = perft(rootPos, Limits.perft * ONE_PLY); + nodes = perft(rootPos, Limits.perft); sync_cout << "\nNodes searched: " << nodes << "\n" << sync_endl; return; } @@ -229,31 +274,32 @@ void MainThread::search() { // Check if there are threads with a better score than main thread if ( Options["MultiPV"] == 1 && !Limits.depth - && !Skill(Options["Skill Level"]).enabled() + && !(Skill(Options["Skill Level"]).enabled() || Options["UCI_LimitStrength"]) && rootMoves[0].pv[0] != MOVE_NONE) { std::map votes; Value minScore = this->rootMoves[0].score; - // Find out minimum score and reset votes for moves which can be voted + // Find out minimum score for (Thread* th: Threads) minScore = std::min(minScore, th->rootMoves[0].score); - // Vote according to score and depth + // Vote according to score and depth, and select the best thread for (Thread* th : Threads) { - int64_t s = th->rootMoves[0].score - minScore + 1; - votes[th->rootMoves[0].pv[0]] += 200 + s * s * int(th->completedDepth); - } + votes[th->rootMoves[0].pv[0]] += + (th->rootMoves[0].score - minScore + 14) * int(th->completedDepth); - // Select best thread - auto bestVote = votes[this->rootMoves[0].pv[0]]; - for (Thread* th : Threads) - if (votes[th->rootMoves[0].pv[0]] > bestVote) + if (bestThread->rootMoves[0].score >= VALUE_MATE_IN_MAX_PLY) { - bestVote = votes[th->rootMoves[0].pv[0]]; - bestThread = th; + // Make sure we pick the shortest mate + if (th->rootMoves[0].score > bestThread->rootMoves[0].score) + bestThread = th; } + else if ( th->rootMoves[0].score >= VALUE_MATE_IN_MAX_PLY + || votes[th->rootMoves[0].pv[0]] > votes[bestThread->rootMoves[0].pv[0]]) + bestThread = th; + } } previousScore = bestThread->rootMoves[0].score; @@ -285,21 +331,45 @@ void Thread::search() { Move pv[MAX_PLY+1]; Value bestValue, alpha, beta, delta; Move lastBestMove = MOVE_NONE; - Depth lastBestMoveDepth = DEPTH_ZERO; + Depth lastBestMoveDepth = 0; MainThread* mainThread = (this == Threads.main() ? Threads.main() : nullptr); double timeReduction = 1, totBestMoveChanges = 0; Color us = rootPos.side_to_move(); + int iterIdx = 0; std::memset(ss-7, 0, 10 * sizeof(Stack)); for (int i = 7; i > 0; i--) - (ss-i)->continuationHistory = &this->continuationHistory[NO_PIECE][0]; // Use as sentinel + (ss-i)->continuationHistory = &this->continuationHistory[0][0][NO_PIECE][0]; // Use as a sentinel + ss->pv = pv; bestValue = delta = alpha = -VALUE_INFINITE; beta = VALUE_INFINITE; + if (mainThread) + { + if (mainThread->previousScore == VALUE_INFINITE) + for (int i=0; i<4; ++i) + mainThread->iterValue[i] = VALUE_ZERO; + else + for (int i=0; i<4; ++i) + mainThread->iterValue[i] = mainThread->previousScore; + } + size_t multiPV = Options["MultiPV"]; - Skill skill(Options["Skill Level"]); + + // Pick integer skill levels, but non-deterministically round up or down + // such that the average integer skill corresponds to the input floating point one. + // UCI_Elo is converted to a suitable fractional skill level, using anchoring + // to CCRL Elo (goldfish 1.13 = 2000) and a fit through Ordo derived Elo + // for match (TC 60+0.6) results spanning a wide range of k values. + PRNG rng(now()); + double floatLevel = Options["UCI_LimitStrength"] ? + clamp(std::pow((Options["UCI_Elo"] - 1346.6) / 143.4, 1 / 0.806), 0.0, 20.0) : + double(Options["Skill Level"]); + int intLevel = int(floatLevel) + + ((floatLevel - int(floatLevel)) * 1024 > rng.rand() % 1024 ? 1 : 0); + Skill skill(intLevel); // When playing with strength handicap enable MultiPV search that we will // use behind the scenes to retrieve a set of possible moves. @@ -307,6 +377,7 @@ void Thread::search() { multiPV = std::max(multiPV, (size_t)4); multiPV = std::min(multiPV, rootMoves.size()); + ttHitAverage = ttHitAverageWindow * ttHitAverageResolution / 2; int ct = int(Options["Contempt"]) * PawnValueEg / 100; // From centipawns @@ -322,10 +393,12 @@ void Thread::search() { contempt = (us == WHITE ? make_score(ct, ct / 2) : -make_score(ct, ct / 2)); + int searchAgainCounter = 0; + // Iterative deepening loop until requested to stop or the target depth is reached - while ( (rootDepth += ONE_PLY) < DEPTH_MAX + while ( ++rootDepth < MAX_PLY && !Threads.stop - && !(Limits.depth && mainThread && rootDepth / ONE_PLY > Limits.depth)) + && !(Limits.depth && mainThread && rootDepth > Limits.depth)) { // Age out PV variability metric if (mainThread) @@ -339,6 +412,9 @@ void Thread::search() { size_t pvFirst = 0; pvLast = 0; + if (!Threads.increaseDepth) + searchAgainCounter++; + // MultiPV loop. We perform a full root search for each PV line for (pvIdx = 0; pvIdx < multiPV && !Threads.stop; ++pvIdx) { @@ -354,15 +430,15 @@ void Thread::search() { selDepth = 0; // Reset aspiration window starting size - if (rootDepth >= 5 * ONE_PLY) + if (rootDepth >= 4) { Value previousScore = rootMoves[pvIdx].previousScore; - delta = Value(20); + delta = Value(21 + abs(previousScore) / 256); alpha = std::max(previousScore - delta,-VALUE_INFINITE); beta = std::min(previousScore + delta, VALUE_INFINITE); // Adjust contempt based on root move's previousScore (dynamic contempt) - int dct = ct + 88 * previousScore / (abs(previousScore) + 200); + int dct = ct + (102 - ct / 2) * previousScore / (abs(previousScore) + 157); contempt = (us == WHITE ? make_score(dct, dct / 2) : -make_score(dct, dct / 2)); @@ -374,7 +450,7 @@ void Thread::search() { int failedHighCnt = 0; while (true) { - Depth adjustedDepth = std::max(ONE_PLY, rootDepth - failedHighCnt * ONE_PLY); + Depth adjustedDepth = std::max(1, rootDepth - failedHighCnt - searchAgainCounter); bestValue = ::search(rootPos, ss, alpha, beta, adjustedDepth, false); // Bring the best move to the front. It is critical that sorting @@ -406,20 +482,20 @@ void Thread::search() { beta = (alpha + beta) / 2; alpha = std::max(bestValue - delta, -VALUE_INFINITE); + failedHighCnt = 0; if (mainThread) - { - failedHighCnt = 0; mainThread->stopOnPonderhit = false; - } } else if (bestValue >= beta) { beta = std::min(bestValue + delta, VALUE_INFINITE); - if (mainThread) - ++failedHighCnt; + ++failedHighCnt; } else + { + ++rootMoves[pvIdx].bestMoveCount; break; + } delta += delta / 4 + 5; @@ -460,12 +536,13 @@ void Thread::search() { && !Threads.stop && !mainThread->stopOnPonderhit) { - double fallingEval = (314 + 9 * (mainThread->previousScore - bestValue)) / 581.0; + double fallingEval = (332 + 6 * (mainThread->previousScore - bestValue) + + 6 * (mainThread->iterValue[iterIdx] - bestValue)) / 704.0; fallingEval = clamp(fallingEval, 0.5, 1.5); // If the bestMove is stable over several iterations, reduce time accordingly - timeReduction = lastBestMoveDepth + 10 * ONE_PLY < completedDepth ? 1.95 : 1.0; - double reduction = std::pow(mainThread->previousTimeReduction, 0.528) / timeReduction; + timeReduction = lastBestMoveDepth + 9 < completedDepth ? 1.94 : 0.91; + double reduction = (1.41 + mainThread->previousTimeReduction) / (2.27 * timeReduction); // Use part of the gained time from a previous stable move for the current move for (Thread* th : Threads) @@ -486,7 +563,16 @@ void Thread::search() { else Threads.stop = true; } + else if ( Threads.increaseDepth + && !mainThread->ponder + && Time.elapsed() > Time.optimum() * fallingEval * reduction * bestMoveInstability * 0.6) + Threads.increaseDepth = false; + else + Threads.increaseDepth = true; } + + mainThread->iterValue[iterIdx] = bestValue; + iterIdx = (iterIdx + 1) & 3; } if (!mainThread) @@ -518,20 +604,19 @@ namespace { && !rootNode && pos.has_game_cycle(ss->ply)) { - alpha = value_draw(depth, pos.this_thread()); + alpha = value_draw(pos.this_thread()); if (alpha >= beta) return alpha; } // Dive into quiescence search when the depth reaches zero - if (depth < ONE_PLY) + if (depth <= 0) return qsearch(pos, ss, alpha, beta); assert(-VALUE_INFINITE <= alpha && alpha < beta && beta <= VALUE_INFINITE); assert(PvNode || (alpha == beta - 1)); - assert(DEPTH_ZERO < depth && depth < DEPTH_MAX); + assert(0 < depth && depth < MAX_PLY); assert(!(PvNode && cutNode)); - assert(depth / ONE_PLY * ONE_PLY == depth); Move pv[MAX_PLY+1], capturesSearched[32], quietsSearched[64]; StateInfo st; @@ -540,14 +625,15 @@ namespace { Move ttMove, move, excludedMove, bestMove; Depth extension, newDepth; Value bestValue, value, ttValue, eval, maxValue; - bool ttHit, ttPv, inCheck, givesCheck, improving; - bool captureOrPromotion, doFullDepthSearch, moveCountPruning, ttCapture; + bool ttHit, ttPv, inCheck, givesCheck, improving, didLMR, priorCapture; + bool captureOrPromotion, doFullDepthSearch, moveCountPruning, ttCapture, singularLMR; Piece movedPiece; int moveCount, captureCount, quietCount; // Step 1. Initialize node Thread* thisThread = pos.this_thread(); inCheck = pos.checkers(); + priorCapture = pos.captured_piece(); Color us = pos.side_to_move(); moveCount = captureCount = quietCount = ss->moveCount = 0; bestValue = -VALUE_INFINITE; @@ -568,7 +654,7 @@ namespace { || pos.is_draw(ss->ply) || ss->ply >= MAX_PLY) return (ss->ply >= MAX_PLY && !inCheck) ? evaluate(pos) - : value_draw(depth, pos.this_thread()); + : value_draw(pos.this_thread()); // Step 3. Mate distance pruning. Even if we mate at the next move our score // would be at best mate_in(ss->ply+1), but if alpha is already bigger because @@ -594,10 +680,10 @@ namespace { // starts with statScore = 0. Later grandchildren start with the last calculated // statScore of the previous grandchild. This influences the reduction rules in // LMR which are based on the statScore of parent position. - if (rootNode) - (ss + 4)->statScore = 0; - else - (ss + 2)->statScore = 0; + if (rootNode) + (ss+4)->statScore = 0; + else + (ss+2)->statScore = 0; // Step 4. Transposition table lookup. We don't want the score of a partial // search to overwrite a previous full search TT value, so we use a different @@ -605,10 +691,13 @@ namespace { excludedMove = ss->excludedMove; posKey = pos.key() ^ Key(excludedMove << 16); // Isn't a very good hash tte = TT.probe(posKey, ttHit); - ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE; + ttValue = ttHit ? value_from_tt(tte->value(), ss->ply, pos.rule50_count()) : VALUE_NONE; ttMove = rootNode ? thisThread->rootMoves[thisThread->pvIdx].pv[0] : ttHit ? tte->move() : MOVE_NONE; - ttPv = (ttHit && tte->is_pv()) || (PvNode && depth > 4 * ONE_PLY); + ttPv = PvNode || (ttHit && tte->is_pv()); + // thisThread->ttHitAverage can be used to approximate the running average of ttHit + thisThread->ttHitAverage = (ttHitAverageWindow - 1) * thisThread->ttHitAverage / ttHitAverageWindow + + ttHitAverageResolution * ttHit; // At non-PV nodes we check for an early TT cutoff if ( !PvNode @@ -624,11 +713,11 @@ namespace { if (ttValue >= beta) { if (!pos.capture_or_promotion(ttMove)) - update_quiet_stats(pos, ss, ttMove, nullptr, 0, stat_bonus(depth)); + update_quiet_stats(pos, ss, ttMove, stat_bonus(depth)); // Extra penalty for early quiet moves of the previous ply - if ((ss-1)->moveCount <= 2 && !pos.captured_piece()) - update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY)); + if ((ss-1)->moveCount <= 2 && !priorCapture) + update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + 1)); } // Penalty for a quiet ttMove that fails low else if (!pos.capture_or_promotion(ttMove)) @@ -638,7 +727,9 @@ namespace { update_continuation_histories(ss, pos.moved_piece(ttMove), to_sq(ttMove), penalty); } } - return ttValue; + + if (pos.rule50_count() < 90) + return ttValue; } // Step 5. Tablebases probe @@ -675,7 +766,7 @@ namespace { || (b == BOUND_LOWER ? value >= beta : value <= alpha)) { tte->save(posKey, value_to_tt(value, ss->ply), ttPv, b, - std::min(DEPTH_MAX - ONE_PLY, depth + 6 * ONE_PLY), + std::min(MAX_PLY - 1, depth + 6), MOVE_NONE, VALUE_NONE); return value; @@ -701,11 +792,14 @@ namespace { } else if (ttHit) { - // Never assume anything on values stored in TT + // Never assume anything about values stored in TT ss->staticEval = eval = tte->eval(); if (eval == VALUE_NONE) ss->staticEval = eval = evaluate(pos); + if (eval == VALUE_DRAW) + eval = value_draw(thisThread); + // Can ttValue be used as a better position evaluation? if ( ttValue != VALUE_NONE && (tte->bound() & (ttValue > eval ? BOUND_LOWER : BOUND_UPPER))) @@ -725,18 +819,18 @@ namespace { tte->save(posKey, VALUE_NONE, ttPv, BOUND_NONE, DEPTH_NONE, MOVE_NONE, eval); } - // Step 7. Razoring (~2 Elo) + // Step 7. Razoring (~1 Elo) if ( !rootNode // The required rootNode PV handling is not available in qsearch - && depth < 2 * ONE_PLY + && depth < 2 && eval <= alpha - RazorMargin) return qsearch(pos, ss, alpha, beta); - improving = ss->staticEval >= (ss-2)->staticEval - || (ss-2)->staticEval == VALUE_NONE; + improving = (ss-2)->staticEval == VALUE_NONE ? (ss->staticEval > (ss-4)->staticEval + || (ss-4)->staticEval == VALUE_NONE) : ss->staticEval > (ss-2)->staticEval; - // Step 8. Futility pruning: child node (~30 Elo) + // Step 8. Futility pruning: child node (~50 Elo) if ( !PvNode - && depth < 7 * ONE_PLY + && depth < 6 && eval - futility_margin(depth, improving) >= beta && eval < VALUE_KNOWN_WIN) // Do not return unproven wins return eval; @@ -744,9 +838,10 @@ namespace { // Step 9. Null move search with verification search (~40 Elo) if ( !PvNode && (ss-1)->currentMove != MOVE_NULL - && (ss-1)->statScore < 23200 + && (ss-1)->statScore < 23397 && eval >= beta - && ss->staticEval >= beta - 36 * depth / ONE_PLY + 225 + && eval >= ss->staticEval + && ss->staticEval >= beta - 32 * depth - 30 * improving + 120 * ttPv + 292 && !excludedMove && pos.non_pawn_material(us) && (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor)) @@ -754,10 +849,10 @@ namespace { assert(eval - beta >= 0); // Null move dynamic reduction based on depth and value - Depth R = ((823 + 67 * depth / ONE_PLY) / 256 + std::min(int(eval - beta) / 200, 3)) * ONE_PLY; + Depth R = (854 + 68 * depth) / 258 + std::min(int(eval - beta) / 192, 3); ss->currentMove = MOVE_NULL; - ss->continuationHistory = &thisThread->continuationHistory[NO_PIECE][0]; + ss->continuationHistory = &thisThread->continuationHistory[0][0][NO_PIECE][0]; pos.do_null_move(st); @@ -771,14 +866,14 @@ namespace { if (nullValue >= VALUE_MATE_IN_MAX_PLY) nullValue = beta; - if (thisThread->nmpMinPly || (abs(beta) < VALUE_KNOWN_WIN && depth < 12 * ONE_PLY)) + if (thisThread->nmpMinPly || (abs(beta) < VALUE_KNOWN_WIN && depth < 13)) return nullValue; assert(!thisThread->nmpMinPly); // Recursive verification is not allowed // Do verification search at high depths, with null move pruning disabled // for us, until ply exceeds nmpMinPly. - thisThread->nmpMinPly = ss->ply + 3 * (depth-R) / (4 * ONE_PLY); + thisThread->nmpMinPly = ss->ply + 3 * (depth-R) / 4; thisThread->nmpColor = us; Value v = search(pos, ss, beta-1, beta, depth-R, false); @@ -794,10 +889,10 @@ namespace { // If we have a good enough capture and a reduced search returns a value // much above beta, we can (almost) safely prune the previous move. if ( !PvNode - && depth >= 5 * ONE_PLY + && depth >= 5 && abs(beta) < VALUE_MATE_IN_MAX_PLY) { - Value raisedBeta = std::min(beta + 216 - 48 * improving, VALUE_INFINITE); + Value raisedBeta = std::min(beta + 189 - 45 * improving, VALUE_INFINITE); MovePicker mp(pos, ttMove, raisedBeta - ss->staticEval, &thisThread->captureHistory); int probCutCount = 0; @@ -805,12 +900,17 @@ namespace { && probCutCount < 2 + 2 * cutNode) if (move != excludedMove && pos.legal(move)) { + assert(pos.capture_or_promotion(move)); + assert(depth >= 5); + + captureOrPromotion = true; probCutCount++; ss->currentMove = move; - ss->continuationHistory = &thisThread->continuationHistory[pos.moved_piece(move)][to_sq(move)]; - - assert(depth >= 5 * ONE_PLY); + ss->continuationHistory = &thisThread->continuationHistory[inCheck] + [captureOrPromotion] + [pos.moved_piece(move)] + [to_sq(move)]; pos.do_move(move, st); @@ -819,7 +919,7 @@ namespace { // If the qsearch held, perform the regular search if (value >= raisedBeta) - value = -search(pos, ss+1, -raisedBeta, -raisedBeta+1, depth - 4 * ONE_PLY, !cutNode); + value = -search(pos, ss+1, -raisedBeta, -raisedBeta+1, depth - 4, !cutNode); pos.undo_move(move); @@ -828,21 +928,21 @@ namespace { } } - // Step 11. Internal iterative deepening (~2 Elo) - if (depth >= 8 * ONE_PLY && !ttMove) + // Step 11. Internal iterative deepening (~1 Elo) + if (depth >= 7 && !ttMove) { - search(pos, ss, alpha, beta, depth - 7 * ONE_PLY, cutNode); + search(pos, ss, alpha, beta, depth - 7, cutNode); tte = TT.probe(posKey, ttHit); - ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE; + ttValue = ttHit ? value_from_tt(tte->value(), ss->ply, pos.rule50_count()) : VALUE_NONE; ttMove = ttHit ? tte->move() : MOVE_NONE; } moves_loop: // When in check, search starts from here const PieceToHistory* contHist[] = { (ss-1)->continuationHistory, (ss-2)->continuationHistory, - nullptr, (ss-4)->continuationHistory, - nullptr, (ss-6)->continuationHistory }; + nullptr , (ss-4)->continuationHistory, + nullptr , (ss-6)->continuationHistory }; Move countermove = thisThread->counterMoves[pos.piece_on(prevSq)][prevSq]; @@ -852,10 +952,13 @@ moves_loop: // When in check, search starts from here countermove, ss->killers); - value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc - moveCountPruning = false; + value = bestValue; + singularLMR = moveCountPruning = false; ttCapture = ttMove && pos.capture_or_promotion(ttMove); + // Mark this node as being searched + ThreadHolding th(thisThread, posKey, ss->ply); + // Step 12. Loop through all pseudo-legal moves until no moves remain // or a beta cutoff occurs. while ((move = mp.next_move(moveCountPruning)) != MOVE_NONE) @@ -876,116 +979,118 @@ moves_loop: // When in check, search starts from here ss->moveCount = ++moveCount; if (rootNode && thisThread == Threads.main() && Time.elapsed() > 3000) - sync_cout << "info depth " << depth / ONE_PLY + sync_cout << "info depth " << depth << " currmove " << UCI::move(move, pos.is_chess960()) << " currmovenumber " << moveCount + thisThread->pvIdx << sync_endl; if (PvNode) (ss+1)->pv = nullptr; - extension = DEPTH_ZERO; + extension = 0; captureOrPromotion = pos.capture_or_promotion(move); movedPiece = pos.moved_piece(move); givesCheck = pos.gives_check(move); - // Step 13. Extensions (~70 Elo) + // Calculate new depth for this move + newDepth = depth - 1; + + // Step 13. Pruning at shallow depth (~200 Elo) + if ( !rootNode + && pos.non_pawn_material(us) + && bestValue > VALUE_MATED_IN_MAX_PLY) + { + // Skip quiet moves if movecount exceeds our FutilityMoveCount threshold + moveCountPruning = moveCount >= futility_move_count(improving, depth); + + if ( !captureOrPromotion + && !givesCheck) + { + // Reduced depth of the next LMR search + int lmrDepth = std::max(newDepth - reduction(improving, depth, moveCount), 0); + + // Countermoves based pruning (~20 Elo) + if ( lmrDepth < 4 + ((ss-1)->statScore > 0 || (ss-1)->moveCount == 1) + && (*contHist[0])[movedPiece][to_sq(move)] < CounterMovePruneThreshold + && (*contHist[1])[movedPiece][to_sq(move)] < CounterMovePruneThreshold) + continue; + + // Futility pruning: parent node (~5 Elo) + if ( lmrDepth < 6 + && !inCheck + && ss->staticEval + 235 + 172 * lmrDepth <= alpha + && thisThread->mainHistory[us][from_to(move)] + + (*contHist[0])[movedPiece][to_sq(move)] + + (*contHist[1])[movedPiece][to_sq(move)] + + (*contHist[3])[movedPiece][to_sq(move)] < 25000) + continue; - // Singular extension search (~60 Elo). If all moves but one fail low on a + // Prune moves with negative SEE (~20 Elo) + if (!pos.see_ge(move, Value(-(32 - std::min(lmrDepth, 18)) * lmrDepth * lmrDepth))) + continue; + } + else if (!pos.see_ge(move, Value(-194) * depth)) // (~25 Elo) + continue; + } + + // Step 14. Extensions (~75 Elo) + + // Singular extension search (~70 Elo). If all moves but one fail low on a // search of (alpha-s, beta-s), and just one fails high on (alpha, beta), // then that move is singular and should be extended. To verify this we do // a reduced search on all the other moves but the ttMove and if the // result is lower than ttValue minus a margin then we will extend the ttMove. - if ( depth >= 8 * ONE_PLY + if ( depth >= 6 && move == ttMove && !rootNode && !excludedMove // Avoid recursive singular search /* && ttValue != VALUE_NONE Already implicit in the next condition */ && abs(ttValue) < VALUE_KNOWN_WIN && (tte->bound() & BOUND_LOWER) - && tte->depth() >= depth - 3 * ONE_PLY + && tte->depth() >= depth - 3 && pos.legal(move)) { - Value singularBeta = ttValue - 2 * depth / ONE_PLY; - Depth halfDepth = depth / (2 * ONE_PLY) * ONE_PLY; // ONE_PLY invariant + Value singularBeta = ttValue - 2 * depth; + Depth halfDepth = depth / 2; ss->excludedMove = move; value = search(pos, ss, singularBeta - 1, singularBeta, halfDepth, cutNode); ss->excludedMove = MOVE_NONE; if (value < singularBeta) - extension = ONE_PLY; + { + extension = 1; + singularLMR = true; + } // Multi-cut pruning // Our ttMove is assumed to fail high, and now we failed high also on a reduced // search without the ttMove. So we assume this expected Cut-node is not singular, - // that is multiple moves fail high, and we can prune the whole subtree by returning - // the hard beta bound. - else if (cutNode && singularBeta > beta) - return beta; + // that multiple moves fail high, and we can prune the whole subtree by returning + // a soft bound. + else if (singularBeta >= beta) + return singularBeta; } // Check extension (~2 Elo) else if ( givesCheck - && (pos.blockers_for_king(~us) & from_sq(move) || pos.see_ge(move))) - extension = ONE_PLY; - - // Castling extension - else if (type_of(move) == CASTLING) - extension = ONE_PLY; - - // Shuffle extension - else if ( PvNode - && pos.rule50_count() > 18 - && depth < 3 * ONE_PLY - && ss->ply < 3 * thisThread->rootDepth / ONE_PLY) // To avoid too deep searches - extension = ONE_PLY; + && (pos.is_discovery_check_on_king(~us, move) || pos.see_ge(move))) + extension = 1; // Passed pawn extension else if ( move == ss->killers[0] && pos.advanced_pawn_push(move) && pos.pawn_passed(us, to_sq(move))) - extension = ONE_PLY; + extension = 1; - // Calculate new depth for this move - newDepth = depth - ONE_PLY + extension; + // Last captures extension + else if ( PieceValue[EG][pos.captured_piece()] > PawnValueEg + && pos.non_pawn_material() <= 2 * RookValueMg) + extension = 1; - // Step 14. Pruning at shallow depth (~170 Elo) - if ( !rootNode - && pos.non_pawn_material(us) - && bestValue > VALUE_MATED_IN_MAX_PLY) - { - // Skip quiet moves if movecount exceeds our FutilityMoveCount threshold - moveCountPruning = moveCount >= futility_move_count(improving, depth / ONE_PLY); - - if ( !captureOrPromotion - && !givesCheck - && !pos.advanced_pawn_push(move)) - { - // Move count based pruning (~30 Elo) - if (moveCountPruning) - continue; - - // Reduced depth of the next LMR search - int lmrDepth = std::max(newDepth - reduction(improving, depth, moveCount), DEPTH_ZERO); - lmrDepth /= ONE_PLY; - - // Countermoves based pruning (~20 Elo) - if ( lmrDepth < 3 + ((ss-1)->statScore > 0 || (ss-1)->moveCount == 1) - && (*contHist[0])[movedPiece][to_sq(move)] < CounterMovePruneThreshold - && (*contHist[1])[movedPiece][to_sq(move)] < CounterMovePruneThreshold) - continue; - - // Futility pruning: parent node (~2 Elo) - if ( lmrDepth < 7 - && !inCheck - && ss->staticEval + 256 + 200 * lmrDepth <= alpha) - continue; + // Castling extension + if (type_of(move) == CASTLING) + extension = 1; - // Prune moves with negative SEE (~10 Elo) - if (!pos.see_ge(move, Value(-29 * lmrDepth * lmrDepth))) - continue; - } - else if (!pos.see_ge(move, -PawnValueEg * (depth / ONE_PLY))) // (~20 Elo) - continue; - } + // Add extension to new depth + newDepth += extension; // Speculative prefetch as early as possible prefetch(TT.first_entry(pos.key_after(move))); @@ -999,76 +1104,118 @@ moves_loop: // When in check, search starts from here // Update the current move (this must be done after singular extension search) ss->currentMove = move; - ss->continuationHistory = &thisThread->continuationHistory[movedPiece][to_sq(move)]; + ss->continuationHistory = &thisThread->continuationHistory[inCheck] + [captureOrPromotion] + [movedPiece] + [to_sq(move)]; // Step 15. Make the move pos.do_move(move, st, givesCheck); - // Step 16. Reduced depth search (LMR). If the move fails high it will be + // Step 16. Reduced depth search (LMR, ~200 Elo). If the move fails high it will be // re-searched at full depth. - if ( depth >= 3 * ONE_PLY - && moveCount > 1 + 3 * rootNode + if ( depth >= 3 + && moveCount > 1 + 2 * rootNode + && (!rootNode || thisThread->best_move_count(move) == 0) && ( !captureOrPromotion || moveCountPruning - || ss->staticEval + PieceValue[EG][pos.captured_piece()] <= alpha)) + || ss->staticEval + PieceValue[EG][pos.captured_piece()] <= alpha + || cutNode + || thisThread->ttHitAverage < 375 * ttHitAverageResolution * ttHitAverageWindow / 1024)) { Depth r = reduction(improving, depth, moveCount); - // Decrease reduction if position is or has been on the PV + // Decrease reduction if the ttHit running average is large + if (thisThread->ttHitAverage > 500 * ttHitAverageResolution * ttHitAverageWindow / 1024) + r--; + + // Reduction if other threads are searching this position. + if (th.marked()) + r++; + + // Decrease reduction if position is or has been on the PV (~10 Elo) if (ttPv) - r -= 2 * ONE_PLY; + r -= 2; + + // Decrease reduction if opponent's move count is high (~5 Elo) + if ((ss-1)->moveCount > 14) + r--; - // Decrease reduction if opponent's move count is high (~10 Elo) - if ((ss-1)->moveCount > 15) - r -= ONE_PLY; + // Decrease reduction if ttMove has been singularly extended (~3 Elo) + if (singularLMR) + r -= 2; if (!captureOrPromotion) { - // Increase reduction if ttMove is a capture (~0 Elo) + // Increase reduction if ttMove is a capture (~5 Elo) if (ttCapture) - r += ONE_PLY; + r++; - // Increase reduction for cut nodes (~5 Elo) + // Increase reduction for cut nodes (~10 Elo) if (cutNode) - r += 2 * ONE_PLY; + r += 2; // Decrease reduction for moves that escape a capture. Filter out // castling moves, because they are coded as "king captures rook" and - // hence break make_move(). (~5 Elo) + // hence break make_move(). (~2 Elo) else if ( type_of(move) == NORMAL - && !pos.see_ge(make_move(to_sq(move), from_sq(move)))) - r -= 2 * ONE_PLY; + && !pos.see_ge(reverse_move(move))) + r -= 2 + ttPv; ss->statScore = thisThread->mainHistory[us][from_to(move)] + (*contHist[0])[movedPiece][to_sq(move)] + (*contHist[1])[movedPiece][to_sq(move)] + (*contHist[3])[movedPiece][to_sq(move)] - - 4000; + - 4926; + + // Reset statScore to zero if negative and most stats shows >= 0 + if ( ss->statScore < 0 + && (*contHist[0])[movedPiece][to_sq(move)] >= 0 + && (*contHist[1])[movedPiece][to_sq(move)] >= 0 + && thisThread->mainHistory[us][from_to(move)] >= 0) + ss->statScore = 0; // Decrease/increase reduction by comparing opponent's stat score (~10 Elo) - if (ss->statScore >= 0 && (ss-1)->statScore < 0) - r -= ONE_PLY; + if (ss->statScore >= -102 && (ss-1)->statScore < -114) + r--; - else if ((ss-1)->statScore >= 0 && ss->statScore < 0) - r += ONE_PLY; + else if ((ss-1)->statScore >= -116 && ss->statScore < -154) + r++; // Decrease/increase reduction for moves with a good/bad history (~30 Elo) - r -= ss->statScore / 20000 * ONE_PLY; + r -= ss->statScore / 16384; } - Depth d = std::max(newDepth - std::max(r, DEPTH_ZERO), ONE_PLY); + // Increase reduction for captures/promotions if late move and at low depth + else if (depth < 8 && moveCount > 2) + r++; + + Depth d = clamp(newDepth - r, 1, newDepth); value = -search(pos, ss+1, -(alpha+1), -alpha, d, true); - doFullDepthSearch = (value > alpha && d != newDepth); + doFullDepthSearch = (value > alpha && d != newDepth), didLMR = true; } else - doFullDepthSearch = !PvNode || moveCount > 1; + doFullDepthSearch = !PvNode || moveCount > 1, didLMR = false; // Step 17. Full depth search when LMR is skipped or fails high if (doFullDepthSearch) + { value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode); + if (didLMR && !captureOrPromotion) + { + int bonus = value > alpha ? stat_bonus(newDepth) + : -stat_bonus(newDepth); + + if (move == ss->killers[0]) + bonus += bonus / 4; + + update_continuation_histories(ss, movedPiece, to_sq(move), bonus); + } + } + // For PV nodes only, do a full PV search on the first move or after a fail // high (in the latter case search only if value < beta), otherwise let the // parent node fail low with value <= alpha and try another move. @@ -1172,24 +1319,14 @@ moves_loop: // When in check, search starts from here if (!moveCount) bestValue = excludedMove ? alpha : inCheck ? mated_in(ss->ply) : VALUE_DRAW; - else if (bestMove) - { - // Quiet best move: update move sorting heuristics - if (!pos.capture_or_promotion(bestMove)) - update_quiet_stats(pos, ss, bestMove, quietsSearched, quietCount, - stat_bonus(depth + (bestValue > beta + PawnValueMg ? ONE_PLY : DEPTH_ZERO))); - - update_capture_stats(pos, bestMove, capturesSearched, captureCount, stat_bonus(depth + ONE_PLY)); - // Extra penalty for a quiet TT or main killer move in previous ply when it gets refuted - if ( ((ss-1)->moveCount == 1 || ((ss-1)->currentMove == (ss-1)->killers[0])) - && !pos.captured_piece()) - update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY)); + else if (bestMove) + update_all_stats(pos, ss, bestMove, bestValue, beta, prevSq, + quietsSearched, quietCount, capturesSearched, captureCount, depth); - } // Bonus for prior countermove that caused the fail low - else if ( (depth >= 3 * ONE_PLY || PvNode) - && !pos.captured_piece()) + else if ( (depth >= 3 || PvNode) + && !priorCapture) update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, stat_bonus(depth)); if (PvNode) @@ -1216,8 +1353,7 @@ moves_loop: // When in check, search starts from here assert(alpha >= -VALUE_INFINITE && alpha < beta && beta <= VALUE_INFINITE); assert(PvNode || (alpha == beta - 1)); - assert(depth <= DEPTH_ZERO); - assert(depth / ONE_PLY * ONE_PLY == depth); + assert(depth <= 0); Move pv[MAX_PLY+1]; StateInfo st; @@ -1226,7 +1362,7 @@ moves_loop: // When in check, search starts from here Move ttMove, move, bestMove; Depth ttDepth; Value bestValue, value, ttValue, futilityValue, futilityBase, oldAlpha; - bool ttHit, pvHit, inCheck, givesCheck, evasionPrunable; + bool ttHit, pvHit, inCheck, givesCheck, captureOrPromotion, evasionPrunable; int moveCount; if (PvNode) @@ -1257,7 +1393,7 @@ moves_loop: // When in check, search starts from here // Transposition table lookup posKey = pos.key(); tte = TT.probe(posKey, ttHit); - ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE; + ttValue = ttHit ? value_from_tt(tte->value(), ss->ply, pos.rule50_count()) : VALUE_NONE; ttMove = ttHit ? tte->move() : MOVE_NONE; pvHit = ttHit && tte->is_pv(); @@ -1279,7 +1415,7 @@ moves_loop: // When in check, search starts from here { if (ttHit) { - // Never assume anything on values stored in TT + // Never assume anything about values stored in TT if ((ss->staticEval = bestValue = tte->eval()) == VALUE_NONE) ss->staticEval = bestValue = evaluate(pos); @@ -1306,12 +1442,12 @@ moves_loop: // When in check, search starts from here if (PvNode && bestValue > alpha) alpha = bestValue; - futilityBase = bestValue + 128; + futilityBase = bestValue + 154; } const PieceToHistory* contHist[] = { (ss-1)->continuationHistory, (ss-2)->continuationHistory, - nullptr, (ss-4)->continuationHistory, - nullptr, (ss-6)->continuationHistory }; + nullptr , (ss-4)->continuationHistory, + nullptr , (ss-6)->continuationHistory }; // Initialize a MovePicker object for the current position, and prepare // to search the moves. Because the depth is <= 0 here, only captures, @@ -1328,6 +1464,7 @@ moves_loop: // When in check, search starts from here assert(is_ok(move)); givesCheck = pos.gives_check(move); + captureOrPromotion = pos.capture_or_promotion(move); moveCount++; @@ -1356,13 +1493,12 @@ moves_loop: // When in check, search starts from here // Detect non-capture evasions that are candidates to be pruned evasionPrunable = inCheck - && (depth != DEPTH_ZERO || moveCount > 2) + && (depth != 0 || moveCount > 2) && bestValue > VALUE_MATED_IN_MAX_PLY && !pos.capture(move); // Don't search moves with negative SEE values - if ( (!inCheck || evasionPrunable) - && !pos.see_ge(move)) + if ( (!inCheck || evasionPrunable) && !pos.see_ge(move)) continue; // Speculative prefetch as early as possible @@ -1376,11 +1512,14 @@ moves_loop: // When in check, search starts from here } ss->currentMove = move; - ss->continuationHistory = &thisThread->continuationHistory[pos.moved_piece(move)][to_sq(move)]; + ss->continuationHistory = &thisThread->continuationHistory[inCheck] + [captureOrPromotion] + [pos.moved_piece(move)] + [to_sq(move)]; // Make and search the move pos.do_move(move, st, givesCheck); - value = -qsearch(pos, ss+1, -beta, -alpha, depth - ONE_PLY); + value = -qsearch(pos, ss+1, -beta, -alpha, depth - 1); pos.undo_move(move); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); @@ -1438,11 +1577,11 @@ moves_loop: // When in check, search starts from here // from the transposition table (which refers to the plies to mate/be mated // from current position) to "plies to mate/be mated from the root". - Value value_from_tt(Value v, int ply) { + Value value_from_tt(Value v, int ply, int r50c) { return v == VALUE_NONE ? VALUE_NONE - : v >= VALUE_MATE_IN_MAX_PLY ? v - ply - : v <= VALUE_MATED_IN_MAX_PLY ? v + ply : v; + : v >= VALUE_MATE_IN_MAX_PLY ? VALUE_MATE - v > 99 - r50c ? VALUE_MATE_IN_MAX_PLY : v - ply + : v <= VALUE_MATED_IN_MAX_PLY ? VALUE_MATE + v > 99 - r50c ? VALUE_MATED_IN_MAX_PLY : v + ply : v; } @@ -1456,43 +1595,65 @@ moves_loop: // When in check, search starts from here } - // update_continuation_histories() updates histories of the move pairs formed - // by moves at ply -1, -2, and -4 with current move. + // update_all_stats() updates stats at the end of search() when a bestMove is found - void update_continuation_histories(Stack* ss, Piece pc, Square to, int bonus) { + void update_all_stats(const Position& pos, Stack* ss, Move bestMove, Value bestValue, Value beta, Square prevSq, + Move* quietsSearched, int quietCount, Move* capturesSearched, int captureCount, Depth depth) { - for (int i : {1, 2, 4, 6}) - if (is_ok((ss-i)->currentMove)) - (*(ss-i)->continuationHistory)[pc][to] << bonus; - } + int bonus1, bonus2; + Color us = pos.side_to_move(); + Thread* thisThread = pos.this_thread(); + CapturePieceToHistory& captureHistory = thisThread->captureHistory; + Piece moved_piece = pos.moved_piece(bestMove); + PieceType captured = type_of(pos.piece_on(to_sq(bestMove))); + bonus1 = stat_bonus(depth + 1); + bonus2 = bestValue > beta + PawnValueMg ? bonus1 // larger bonus + : stat_bonus(depth); // smaller bonus - // update_capture_stats() updates move sorting heuristics when a new capture best move is found + if (!pos.capture_or_promotion(bestMove)) + { + update_quiet_stats(pos, ss, bestMove, bonus2); - void update_capture_stats(const Position& pos, Move move, - Move* captures, int captureCount, int bonus) { + // Decrease all the non-best quiet moves + for (int i = 0; i < quietCount; ++i) + { + thisThread->mainHistory[us][from_to(quietsSearched[i])] << -bonus2; + update_continuation_histories(ss, pos.moved_piece(quietsSearched[i]), to_sq(quietsSearched[i]), -bonus2); + } + } + else + captureHistory[moved_piece][to_sq(bestMove)][captured] << bonus1; - CapturePieceToHistory& captureHistory = pos.this_thread()->captureHistory; - Piece moved_piece = pos.moved_piece(move); - PieceType captured = type_of(pos.piece_on(to_sq(move))); + // Extra penalty for a quiet TT or main killer move in previous ply when it gets refuted + if ( ((ss-1)->moveCount == 1 || ((ss-1)->currentMove == (ss-1)->killers[0])) + && !pos.captured_piece()) + update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -bonus1); - if (pos.capture_or_promotion(move)) - captureHistory[moved_piece][to_sq(move)][captured] << bonus; + // Decrease all the non-best capture moves + for (int i = 0; i < captureCount; ++i) + { + moved_piece = pos.moved_piece(capturesSearched[i]); + captured = type_of(pos.piece_on(to_sq(capturesSearched[i]))); + captureHistory[moved_piece][to_sq(capturesSearched[i])][captured] << -bonus1; + } + } - // Decrease all the other played capture moves - for (int i = 0; i < captureCount; ++i) - { - moved_piece = pos.moved_piece(captures[i]); - captured = type_of(pos.piece_on(to_sq(captures[i]))); - captureHistory[moved_piece][to_sq(captures[i])][captured] << -bonus; - } + + // update_continuation_histories() updates histories of the move pairs formed + // by moves at ply -1, -2, and -4 with current move. + + void update_continuation_histories(Stack* ss, Piece pc, Square to, int bonus) { + + for (int i : {1, 2, 4, 6}) + if (is_ok((ss-i)->currentMove)) + (*(ss-i)->continuationHistory)[pc][to] << bonus; } - // update_quiet_stats() updates move sorting heuristics when a new quiet best move is found + // update_quiet_stats() updates move sorting heuristics - void update_quiet_stats(const Position& pos, Stack* ss, Move move, - Move* quiets, int quietCount, int bonus) { + void update_quiet_stats(const Position& pos, Stack* ss, Move move, int bonus) { if (ss->killers[0] != move) { @@ -1505,18 +1666,14 @@ moves_loop: // When in check, search starts from here thisThread->mainHistory[us][from_to(move)] << bonus; update_continuation_histories(ss, pos.moved_piece(move), to_sq(move), bonus); + if (type_of(pos.moved_piece(move)) != PAWN) + thisThread->mainHistory[us][from_to(reverse_move(move))] << -bonus; + if (is_ok((ss-1)->currentMove)) { Square prevSq = to_sq((ss-1)->currentMove); thisThread->counterMoves[pos.piece_on(prevSq)][prevSq] = move; } - - // Decrease all the other played quiet moves - for (int i = 0; i < quietCount; ++i) - { - thisThread->mainHistory[us][from_to(quiets[i])] << -bonus; - update_continuation_histories(ss, pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus); - } } // When playing with strength handicap, choose best move among a set of RootMoves @@ -1602,12 +1759,12 @@ string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) { for (size_t i = 0; i < multiPV; ++i) { - bool updated = (i <= pvIdx && rootMoves[i].score != -VALUE_INFINITE); + bool updated = rootMoves[i].score != -VALUE_INFINITE; - if (depth == ONE_PLY && !updated) + if (depth == 1 && !updated) continue; - Depth d = updated ? depth : depth - ONE_PLY; + Depth d = updated ? depth : depth - 1; Value v = updated ? rootMoves[i].score : rootMoves[i].previousScore; bool tb = TB::RootInTB && abs(v) < VALUE_MATE - MAX_PLY; @@ -1617,7 +1774,7 @@ string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) { ss << "\n"; ss << "info" - << " depth " << d / ONE_PLY + << " depth " << d << " seldepth " << rootMoves[i].selDepth << " multipv " << i + 1 << " score " << UCI::value(v); @@ -1676,7 +1833,7 @@ void Tablebases::rank_root_moves(Position& pos, Search::RootMoves& rootMoves) { RootInTB = false; UseRule50 = bool(Options["Syzygy50MoveRule"]); - ProbeDepth = int(Options["SyzygyProbeDepth"]) * ONE_PLY; + ProbeDepth = int(Options["SyzygyProbeDepth"]); Cardinality = int(Options["SyzygyProbeLimit"]); bool dtz_available = true; @@ -1685,7 +1842,7 @@ void Tablebases::rank_root_moves(Position& pos, Search::RootMoves& rootMoves) { if (Cardinality > MaxCardinality) { Cardinality = MaxCardinality; - ProbeDepth = DEPTH_ZERO; + ProbeDepth = 0; } if (Cardinality >= popcount(pos.pieces()) && !pos.can_castle(ANY_CASTLING)) @@ -1713,7 +1870,7 @@ void Tablebases::rank_root_moves(Position& pos, Search::RootMoves& rootMoves) { } else { - // Assign the same rank to all moves + // Clean up if root_probe() and root_probe_wdl() have failed for (auto& m : rootMoves) m.tbRank = 0; }