X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=11ba939a95153384267210921f8032ffbf5199cb;hp=3b7fab5f31fb0196db17be3cb31f92ab93c2dda2;hb=4509eb1342fe282d08bd90340efaff4df5947a87;hpb=f2053ba19f8466ce33d9de4fa4267e77c1a6a852 diff --git a/src/search.cpp b/src/search.cpp index 3b7fab5f..11ba939a 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -19,7 +19,6 @@ #include #include -#include #include #include #include @@ -28,13 +27,12 @@ #include "evaluate.h" #include "movegen.h" #include "movepick.h" -#include "notation.h" #include "rkiss.h" #include "search.h" #include "timeman.h" #include "thread.h" #include "tt.h" -#include "ucioption.h" +#include "uci.h" namespace Search { @@ -56,21 +54,20 @@ namespace { enum NodeType { Root, PV, NonPV }; // Dynamic razoring margin based on depth - inline Value razor_margin(Depth d) { return Value(512 + 16 * d); } + inline Value razor_margin(Depth d) { return Value(512 + 32 * d); } // Futility lookup tables (initialized at startup) and their access functions - int FutilityMoveCounts[2][32]; // [improving][depth] + int FutilityMoveCounts[2][16]; // [improving][depth] inline Value futility_margin(Depth d) { - return Value(100 * d); + return Value(200 * d); } // Reduction lookup tables (initialized at startup) and their access function int8_t Reductions[2][2][64][64]; // [pv][improving][depth][moveNumber] template inline Depth reduction(bool i, Depth d, int mn) { - - return (Depth) Reductions[PvNode][i][std::min(int(d) / ONE_PLY, 63)][std::min(mn, 63)]; + return (Depth) Reductions[PvNode][i][std::min(int(d), 63)][std::min(mn, 63)]; } size_t PVIdx; @@ -90,8 +87,9 @@ namespace { void id_loop(Position& pos); Value value_to_tt(Value v, int ply); Value value_from_tt(Value v, int ply); + void update_pv(Move* pv, Move move, Move* childPv); void update_stats(const Position& pos, Stack* ss, Move move, Depth depth, Move* quiets, int quietsCnt); - string uci_pv(const Position& pos, int depth, Value alpha, Value beta); + string uci_pv(const Position& pos, Depth depth, Value alpha, Value beta); struct Skill { Skill(int l, size_t rootSize) : level(l), @@ -104,7 +102,7 @@ namespace { } size_t candidates_size() const { return candidates; } - bool time_to_pick(int depth) const { return depth == 1 + level; } + bool time_to_pick(Depth depth) const { return depth == 1 + level; } Move pick_move(); int level; @@ -119,59 +117,62 @@ namespace { void Search::init() { - int d; // depth (ONE_PLY == 2) - int hd; // half depth (ONE_PLY == 1) - int mc; // moveCount - // Init reductions array - for (hd = 1; hd < 64; ++hd) for (mc = 1; mc < 64; ++mc) - { - double pvRed = 0.00 + log(double(hd)) * log(double(mc)) / 3.00; - double nonPVRed = 0.33 + log(double(hd)) * log(double(mc)) / 2.25; - Reductions[1][1][hd][mc] = int8_t( pvRed >= 1.0 ? pvRed * int(ONE_PLY) : 0); - Reductions[0][1][hd][mc] = int8_t(nonPVRed >= 1.0 ? nonPVRed * int(ONE_PLY) : 0); + for (int d = 1; d < 64; ++d) + for (int mc = 1; mc < 64; ++mc) + { + double pvRed = 0.00 + log(double(d)) * log(double(mc)) / 3.00; + double nonPVRed = 0.33 + log(double(d)) * log(double(mc)) / 2.25; - Reductions[1][0][hd][mc] = Reductions[1][1][hd][mc]; - Reductions[0][0][hd][mc] = Reductions[0][1][hd][mc]; + Reductions[1][1][d][mc] = int8_t( pvRed >= 1.0 ? pvRed + 0.5: 0); + Reductions[0][1][d][mc] = int8_t(nonPVRed >= 1.0 ? nonPVRed + 0.5: 0); - if (Reductions[0][0][hd][mc] > 2 * ONE_PLY) - Reductions[0][0][hd][mc] += ONE_PLY; + Reductions[1][0][d][mc] = Reductions[1][1][d][mc]; + Reductions[0][0][d][mc] = Reductions[0][1][d][mc]; - else if (Reductions[0][0][hd][mc] > 1 * ONE_PLY) - Reductions[0][0][hd][mc] += ONE_PLY / 2; - } + // Increase reduction when eval is not improving + if (Reductions[0][0][d][mc] >= 2) + Reductions[0][0][d][mc] += 1; + } // Init futility move count array - for (d = 0; d < 32; ++d) + for (int d = 0; d < 16; ++d) { - FutilityMoveCounts[0][d] = int(2.4 + 0.222 * pow(d + 0.00, 1.8)); - FutilityMoveCounts[1][d] = int(3.0 + 0.300 * pow(d + 0.98, 1.8)); + FutilityMoveCounts[0][d] = int(2.4 + 0.773 * pow(d + 0.00, 1.8)); + FutilityMoveCounts[1][d] = int(2.9 + 1.045 * pow(d + 0.49, 1.8)); } } /// Search::perft() is our utility to verify move generation. All the leaf nodes /// up to the given depth are generated and counted and the sum returned. - -static uint64_t perft(Position& pos, Depth depth) { +template +uint64_t Search::perft(Position& pos, Depth depth) { StateInfo st; - uint64_t cnt = 0; + uint64_t cnt, nodes = 0; CheckInfo ci(pos); - const bool leaf = depth == 2 * ONE_PLY; + const bool leaf = (depth == 2 * ONE_PLY); for (MoveList it(pos); *it; ++it) { - pos.do_move(*it, st, ci, pos.gives_check(*it, ci)); - cnt += leaf ? MoveList(pos).size() : ::perft(pos, depth - ONE_PLY); - pos.undo_move(*it); + if (Root && depth <= ONE_PLY) + cnt = 1, nodes++; + else + { + pos.do_move(*it, st, ci, pos.gives_check(*it, ci)); + cnt = leaf ? MoveList(pos).size() : perft(pos, depth - ONE_PLY); + nodes += cnt; + pos.undo_move(*it); + } + if (Root) + sync_cout << UCI::format_move(*it, pos.is_chess960()) << ": " << cnt << sync_endl; } - return cnt; + return nodes; } -uint64_t Search::perft(Position& pos, Depth depth) { - return depth > ONE_PLY ? ::perft(pos, depth) : MoveList(pos).size(); -} +template uint64_t Search::perft(Position& pos, Depth depth); + /// Search::think() is the external interface to Stockfish's search, and is /// called by the main thread when the program receives the UCI 'go' command. It @@ -181,7 +182,7 @@ void Search::think() { TimeMgr.init(Limits, RootPos.game_ply(), RootPos.side_to_move()); - int cf = Options["Contempt Factor"] * PawnValueEg / 100; // From centipawns + int cf = Options["Contempt"] * PawnValueEg / 100; // From centipawns DrawValue[ RootPos.side_to_move()] = VALUE_DRAW - Value(cf); DrawValue[~RootPos.side_to_move()] = VALUE_DRAW + Value(cf); @@ -189,56 +190,22 @@ void Search::think() { { RootMoves.push_back(MOVE_NONE); sync_cout << "info depth 0 score " - << score_to_uci(RootPos.checkers() ? -VALUE_MATE : VALUE_DRAW) + << UCI::format_value(RootPos.checkers() ? -VALUE_MATE : VALUE_DRAW) << sync_endl; - - goto finalize; } - - if (Options["Write Search Log"]) + else { - Log log(Options["Search Log Filename"]); - log << "\nSearching: " << RootPos.fen() - << "\ninfinite: " << Limits.infinite - << " ponder: " << Limits.ponder - << " time: " << Limits.time[RootPos.side_to_move()] - << " increment: " << Limits.inc[RootPos.side_to_move()] - << " moves to go: " << Limits.movestogo - << "\n" << std::endl; - } - - // Reset the threads, still sleeping: will wake up at split time - for (size_t i = 0; i < Threads.size(); ++i) - Threads[i]->maxPly = 0; - - Threads.timer->run = true; - Threads.timer->notify_one(); // Wake up the recurring timer - - id_loop(RootPos); // Let's start searching ! - - Threads.timer->run = false; // Stop the timer + for (size_t i = 0; i < Threads.size(); ++i) + Threads[i]->maxPly = 0; - if (Options["Write Search Log"]) - { - Time::point elapsed = Time::now() - SearchTime + 1; + Threads.timer->run = true; + Threads.timer->notify_one(); // Wake up the recurring timer - Log log(Options["Search Log Filename"]); - log << "Nodes: " << RootPos.nodes_searched() - << "\nNodes/second: " << RootPos.nodes_searched() * 1000 / elapsed - << "\nBest move: " << move_to_san(RootPos, RootMoves[0].pv[0]); + id_loop(RootPos); // Let's start searching ! - StateInfo st; - RootPos.do_move(RootMoves[0].pv[0], st); - log << "\nPonder move: " << move_to_san(RootPos, RootMoves[0].pv[1]) << std::endl; - RootPos.undo_move(RootMoves[0].pv[0]); + Threads.timer->run = false; } -finalize: - - // When search is stopped this info is not printed - sync_cout << "info nodes " << RootPos.nodes_searched() - << " time " << Time::now() - SearchTime + 1 << sync_endl; - // When we reach the maximum depth, we can arrive here without a raise of // Signals.stop. However, if we are pondering or in an infinite search, // the UCI protocol states that we shouldn't print the best move before the @@ -250,10 +217,12 @@ finalize: RootPos.this_thread()->wait_for(Signals.stop); } - // Best move could be MOVE_NONE when searching on a stalemate position - sync_cout << "bestmove " << move_to_uci(RootMoves[0].pv[0], RootPos.is_chess960()) - << " ponder " << move_to_uci(RootMoves[0].pv[1], RootPos.is_chess960()) - << sync_endl; + sync_cout << "bestmove " << UCI::format_move(RootMoves[0].pv[0], RootPos.is_chess960()); + + if (RootMoves[0].pv.size() > 1) + std::cout << " ponder " << UCI::format_move(RootMoves[0].pv[1], RootPos.is_chess960()); + + std::cout << sync_endl; } @@ -265,13 +234,13 @@ namespace { void id_loop(Position& pos) { - Stack stack[MAX_PLY_PLUS_6], *ss = stack+2; // To allow referencing (ss-2) - int depth; + Stack stack[MAX_PLY+4], *ss = stack+2; // To allow referencing (ss-2) and (ss+2) + Depth depth; Value bestValue, alpha, beta, delta; std::memset(ss-2, 0, 5 * sizeof(Stack)); - depth = 0; + depth = DEPTH_ZERO; BestMoveChanges = 0; bestValue = delta = alpha = -VALUE_INFINITE; beta = VALUE_INFINITE; @@ -290,7 +259,7 @@ namespace { multiPV = std::max(multiPV, skill.candidates_size()); // Iterative deepening loop until requested to stop or target depth reached - while (++depth <= MAX_PLY && !Signals.stop && (!Limits.depth || depth <= Limits.depth)) + while (++depth < DEPTH_MAX && !Signals.stop && (!Limits.depth || depth <= Limits.depth)) { // Age out PV variability metric BestMoveChanges *= 0.5; @@ -301,10 +270,10 @@ namespace { RootMoves[i].prevScore = RootMoves[i].score; // MultiPV loop. We perform a full root search for each PV line - for (PVIdx = 0; PVIdx < multiPV && PVIdx < RootMoves.size() && !Signals.stop; ++PVIdx) + for (PVIdx = 0; PVIdx < std::min(multiPV, RootMoves.size()) && !Signals.stop; ++PVIdx) { // Reset aspiration window starting size - if (depth >= 5) + if (depth >= 5 * ONE_PLY) { delta = Value(16); alpha = std::max(RootMoves[PVIdx].prevScore - delta,-VALUE_INFINITE); @@ -316,7 +285,7 @@ namespace { // high/low anymore. while (true) { - bestValue = search(pos, ss, alpha, beta, depth * ONE_PLY, false); + bestValue = search(pos, ss, alpha, beta, depth, false); // Bring the best move to the front. It is critical that sorting // is done with a stable algorithm because all the values but the @@ -347,18 +316,21 @@ namespace { // re-search, otherwise exit the loop. if (bestValue <= alpha) { + beta = (alpha + beta) / 2; alpha = std::max(bestValue - delta, -VALUE_INFINITE); Signals.failedLowAtRoot = true; Signals.stopOnPonderhit = false; } else if (bestValue >= beta) + { + alpha = (alpha + beta) / 2; beta = std::min(bestValue + delta, VALUE_INFINITE); - + } else break; - delta += 3 * delta / 8; + delta += delta / 2; assert(alpha >= -VALUE_INFINITE && beta <= VALUE_INFINITE); } @@ -366,7 +338,12 @@ namespace { // Sort the PV lines searched so far and update the GUI std::stable_sort(RootMoves.begin(), RootMoves.begin() + PVIdx + 1); - if (PVIdx + 1 == multiPV || Time::now() - SearchTime > 3000) + if (Signals.stop) + sync_cout << "info nodes " << RootPos.nodes_searched() + << " time " << Time::now() - SearchTime << sync_endl; + + else if ( PVIdx + 1 == std::min(multiPV, RootMoves.size()) + || Time::now() - SearchTime > 3000) sync_cout << uci_pv(pos, depth, alpha, beta) << sync_endl; } @@ -374,17 +351,6 @@ namespace { if (skill.candidates_size() && skill.time_to_pick(depth)) skill.pick_move(); - if (Options["Write Search Log"]) - { - RootMove& rm = RootMoves[0]; - if (skill.best != MOVE_NONE) - rm = *std::find(RootMoves.begin(), RootMoves.end(), skill.best); - - Log log(Options["Search Log Filename"]); - log << pretty_pv(pos, depth, rm.score, Time::now() - SearchTime, &rm.pv[0]) - << std::endl; - } - // Have we found a "mate in x"? if ( Limits.mate && bestValue >= VALUE_MATE_IN_MAX_PLY @@ -395,7 +361,7 @@ namespace { if (Limits.use_time_management() && !Signals.stop && !Signals.stopOnPonderhit) { // Take some extra time if the best move has changed - if (depth > 4 && multiPV == 1) + if (depth > 4 * ONE_PLY && multiPV == 1) TimeMgr.pv_instability(BestMoveChanges); // Stop the search if only one legal move is available or all @@ -432,7 +398,7 @@ namespace { assert(PvNode || (alpha == beta - 1)); assert(depth > DEPTH_ZERO); - Move quietsSearched[64]; + Move pv[MAX_PLY+1], quietsSearched[64]; StateInfo st; const TTEntry *tte; SplitPoint* splitPoint; @@ -440,7 +406,7 @@ namespace { Move ttMove, move, excludedMove, bestMove; Depth ext, newDepth, predictedDepth; Value bestValue, value, ttValue, eval, nullValue, futilityValue; - bool inCheck, givesCheck, pvMove, singularExtensionNode, improving; + bool inCheck, givesCheck, singularExtensionNode, improving; bool captureOrPromotion, dangerous, doFullDepthSearch; int moveCount, quietCount; @@ -464,10 +430,7 @@ namespace { moveCount = quietCount = 0; bestValue = -VALUE_INFINITE; - ss->currentMove = ss->ttMove = (ss+1)->excludedMove = bestMove = MOVE_NONE; ss->ply = (ss-1)->ply + 1; - (ss+1)->skipNullMove = false; (ss+1)->reduction = DEPTH_ZERO; - (ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE; // Used to send selDepth info to GUI if (PvNode && thisThread->maxPly < ss->ply) @@ -476,8 +439,8 @@ namespace { if (!RootNode) { // Step 2. Check for aborted search and immediate draw - if (Signals.stop || pos.is_draw() || ss->ply > MAX_PLY) - return ss->ply > MAX_PLY && !inCheck ? evaluate(pos) : DrawValue[pos.side_to_move()]; + if (Signals.stop || pos.is_draw() || ss->ply >= MAX_PLY) + return ss->ply >= MAX_PLY && !inCheck ? evaluate(pos) : DrawValue[pos.side_to_move()]; // 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 @@ -491,6 +454,12 @@ namespace { return alpha; } + assert(0 <= ss->ply && ss->ply < MAX_PLY); + + ss->currentMove = ss->ttMove = (ss+1)->excludedMove = bestMove = MOVE_NONE; + (ss+1)->skipNullMove = false; (ss+1)->reduction = DEPTH_ZERO; + (ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE; + // 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 position key in case of an excluded move. @@ -500,17 +469,13 @@ namespace { ss->ttMove = ttMove = RootNode ? RootMoves[PVIdx].pv[0] : tte ? tte->move() : MOVE_NONE; ttValue = tte ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE; - // At PV nodes we check for exact scores, whilst at non-PV nodes we check for - // a fail high/low. The biggest advantage to probing at PV nodes is to have a - // smooth experience in analysis mode. We don't probe at Root nodes otherwise - // we should also update RootMoveList to avoid bogus output. - if ( !RootNode + // At non-PV nodes we check for a fail high/low. We don't probe at PV nodes + if ( !PvNode && tte && tte->depth() >= depth && ttValue != VALUE_NONE // Only in case of TT access race - && ( PvNode ? tte->bound() == BOUND_EXACT - : ttValue >= beta ? (tte->bound() & BOUND_LOWER) - : (tte->bound() & BOUND_UPPER))) + && (ttValue >= beta ? (tte->bound() & BOUND_LOWER) + : (tte->bound() & BOUND_UPPER))) { ss->currentMove = ttMove; // Can be MOVE_NONE @@ -580,8 +545,7 @@ namespace { && !ss->skipNullMove && depth < 7 * ONE_PLY && eval - futility_margin(depth) >= beta - && abs(beta) < VALUE_MATE_IN_MAX_PLY - && abs(eval) < VALUE_KNOWN_WIN + && eval < VALUE_KNOWN_WIN // Do not return unproven wins && pos.non_pawn_material(pos.side_to_move())) return eval - futility_margin(depth); @@ -597,10 +561,7 @@ namespace { assert(eval - beta >= 0); // Null move dynamic reduction based on depth and value - Depth R = 3 * ONE_PLY - + depth / 4 - + (abs(beta) < VALUE_KNOWN_WIN ? int(eval - beta) / PawnValueMg * ONE_PLY - : DEPTH_ZERO); + Depth R = (3 + depth / 4 + std::min(int(eval - beta) / PawnValueMg, 3)) * ONE_PLY; pos.do_null_move(st); (ss+1)->skipNullMove = true; @@ -665,10 +626,9 @@ namespace { && !ttMove && (PvNode || ss->staticEval + 256 >= beta)) { - Depth d = depth - 2 * ONE_PLY - (PvNode ? DEPTH_ZERO : depth / 4); - + Depth d = 2 * (depth - 2 * ONE_PLY) - (PvNode ? DEPTH_ZERO : depth / 2); ss->skipNullMove = true; - search(pos, ss, alpha, beta, d, true); + search(pos, ss, alpha, beta, d / 2, true); ss->skipNullMove = false; tte = TT.probe(posKey); @@ -695,7 +655,6 @@ moves_loop: // When in check and at SpNode search starts from here singularExtensionNode = !RootNode && !SpNode && depth >= 8 * ONE_PLY - && abs(beta) < VALUE_KNOWN_WIN && ttMove != MOVE_NONE /* && ttValue != VALUE_NONE Already implicit in the next condition */ && abs(ttValue) < VALUE_KNOWN_WIN @@ -735,11 +694,14 @@ moves_loop: // When in check and at SpNode search starts from here Signals.firstRootMove = (moveCount == 1); if (thisThread == Threads.main() && Time::now() - SearchTime > 3000) - sync_cout << "info depth " << depth / ONE_PLY - << " currmove " << move_to_uci(move, pos.is_chess960()) + sync_cout << "info depth " << depth + << " currmove " << UCI::format_move(move, pos.is_chess960()) << " currmovenumber " << moveCount + PVIdx << sync_endl; } + if (PvNode) + (ss+1)->pv = NULL; + ext = DEPTH_ZERO; captureOrPromotion = pos.capture_or_promotion(move); @@ -765,7 +727,7 @@ moves_loop: // When in check and at SpNode search starts from here && !ext && pos.legal(move, ci.pinned)) { - Value rBeta = ttValue - int(depth); + Value rBeta = ttValue - int(2 * depth); ss->excludedMove = move; ss->skipNullMove = true; value = search(pos, ss, rBeta - 1, rBeta, depth / 2, cutNode); @@ -784,12 +746,11 @@ moves_loop: // When in check and at SpNode search starts from here && !captureOrPromotion && !inCheck && !dangerous - /* && move != ttMove Already implicit in the next condition */ && bestValue > VALUE_MATED_IN_MAX_PLY) { // Move count based pruning if ( depth < 16 * ONE_PLY - && moveCount >= FutilityMoveCounts[improving][depth] ) + && moveCount >= FutilityMoveCounts[improving][depth]) { if (SpNode) splitPoint->mutex.lock(); @@ -802,8 +763,8 @@ moves_loop: // When in check and at SpNode search starts from here // Futility pruning: parent node if (predictedDepth < 7 * ONE_PLY) { - futilityValue = ss->staticEval + futility_margin(predictedDepth) - + 128 + Gains[pos.moved_piece(move)][to_sq(move)]; + futilityValue = ss->staticEval + futility_margin(predictedDepth) + + 128 + Gains[pos.moved_piece(move)][to_sq(move)]; if (futilityValue <= alpha) { @@ -829,6 +790,9 @@ moves_loop: // When in check and at SpNode search starts from here } } + // Speculative prefetch as early as possible + prefetch((char*)TT.first_entry(pos.key_after(move))); + // Check for legality just before making the move if (!RootNode && !SpNode && !pos.legal(move, ci.pinned)) { @@ -836,7 +800,6 @@ moves_loop: // When in check and at SpNode search starts from here continue; } - pvMove = PvNode && moveCount == 1; ss->currentMove = move; if (!SpNode && !captureOrPromotion && quietCount < 64) quietsSearched[quietCount++] = move; @@ -847,20 +810,17 @@ moves_loop: // When in check and at SpNode search starts from here // Step 15. Reduced depth search (LMR). If the move fails high it will be // re-searched at full depth. if ( depth >= 3 * ONE_PLY - && !pvMove + && moveCount > 1 && !captureOrPromotion - && move != ttMove && move != ss->killers[0] && move != ss->killers[1]) { ss->reduction = reduction(improving, depth, moveCount); - if (!PvNode && cutNode) + if ( (!PvNode && cutNode) + || History[pos.piece_on(to_sq(move))][to_sq(move)] < 0) ss->reduction += ONE_PLY; - else if (History[pos.piece_on(to_sq(move))][to_sq(move)] < 0) - ss->reduction += ONE_PLY / 2; - if (move == countermoves[0] || move == countermoves[1]) ss->reduction = std::max(DEPTH_ZERO, ss->reduction - ONE_PLY); @@ -888,7 +848,7 @@ moves_loop: // When in check and at SpNode search starts from here ss->reduction = DEPTH_ZERO; } else - doFullDepthSearch = !pvMove; + doFullDepthSearch = !PvNode || moveCount > 1; // Step 16. Full depth search, when LMR is skipped or fails high if (doFullDepthSearch) @@ -896,20 +856,26 @@ moves_loop: // When in check and at SpNode search starts from here if (SpNode) alpha = splitPoint->alpha; - value = newDepth < ONE_PLY ? - givesCheck ? -qsearch(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO) - : -qsearch(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO) - : - search(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode); + value = newDepth < ONE_PLY ? + givesCheck ? -qsearch(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO) + : -qsearch(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO) + : - search(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode); } // 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 to try another move. - if (PvNode && (pvMove || (value > alpha && (RootNode || value < beta)))) - value = newDepth < ONE_PLY ? - givesCheck ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) - : -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) - : - search(pos, ss+1, -beta, -alpha, newDepth, false); + if (PvNode && (moveCount == 1 || (value > alpha && (RootNode || value < beta)))) + { + (ss+1)->pv = pv; + (ss+1)->pv[0] = MOVE_NONE; + + value = newDepth < ONE_PLY ? + givesCheck ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) + : -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) + : - search(pos, ss+1, -beta, -alpha, newDepth, false); + } + // Step 17. Undo move pos.undo_move(move); @@ -934,15 +900,20 @@ moves_loop: // When in check and at SpNode search starts from here RootMove& rm = *std::find(RootMoves.begin(), RootMoves.end(), move); // PV move or new best move ? - if (pvMove || value > alpha) + if (moveCount == 1 || value > alpha) { rm.score = value; - rm.extract_pv_from_tt(pos); + rm.pv.resize(1); + + assert((ss+1)->pv); + + for (Move* m = (ss+1)->pv; *m != MOVE_NONE; ++m) + rm.pv.push_back(*m); // We record how often the best move has been changed in each // iteration. This information is used for time management: When // the best move changes frequently, we allocate some more time. - if (!pvMove) + if (moveCount > 1) ++BestMoveChanges; } else @@ -960,6 +931,9 @@ moves_loop: // When in check and at SpNode search starts from here { bestMove = SpNode ? splitPoint->bestMove = move : move; + if (PvNode && !RootNode) // Update pv even in fail-high case + update_pv(SpNode ? splitPoint->ss->pv : ss->pv, move, (ss+1)->pv); + if (PvNode && value < beta) // Update alpha! Always alpha < beta alpha = SpNode ? splitPoint->alpha = value : value; else @@ -1044,6 +1018,7 @@ moves_loop: // When in check and at SpNode search starts from here assert(PvNode || (alpha == beta - 1)); assert(depth <= DEPTH_ZERO); + Move pv[MAX_PLY+1]; StateInfo st; const TTEntry* tte; Key posKey; @@ -1052,16 +1027,21 @@ moves_loop: // When in check and at SpNode search starts from here bool givesCheck, evasionPrunable; Depth ttDepth; - // To flag BOUND_EXACT a node with eval above alpha and no available moves if (PvNode) - oldAlpha = alpha; + { + oldAlpha = alpha; // To flag BOUND_EXACT when eval above alpha and no available moves + (ss+1)->pv = pv; + ss->pv[0] = MOVE_NONE; + } ss->currentMove = bestMove = MOVE_NONE; ss->ply = (ss-1)->ply + 1; // Check for an instant draw or if the maximum ply has been reached - if (pos.is_draw() || ss->ply > MAX_PLY) - return ss->ply > MAX_PLY && !InCheck ? evaluate(pos) : DrawValue[pos.side_to_move()]; + if (pos.is_draw() || ss->ply >= MAX_PLY) + return ss->ply >= MAX_PLY && !InCheck ? evaluate(pos) : DrawValue[pos.side_to_move()]; + + assert(0 <= ss->ply && ss->ply < MAX_PLY); // Decide whether or not to include checks: this fixes also the type of // TT entry depth that we are going to use. Note that in qsearch we use @@ -1075,12 +1055,12 @@ moves_loop: // When in check and at SpNode search starts from here ttMove = tte ? tte->move() : MOVE_NONE; ttValue = tte ? value_from_tt(tte->value(),ss->ply) : VALUE_NONE; - if ( tte + if ( !PvNode + && tte && tte->depth() >= ttDepth && ttValue != VALUE_NONE // Only in case of TT access race - && ( PvNode ? tte->bound() == BOUND_EXACT - : ttValue >= beta ? (tte->bound() & BOUND_LOWER) - : (tte->bound() & BOUND_UPPER))) + && (ttValue >= beta ? (tte->bound() & BOUND_LOWER) + : (tte->bound() & BOUND_UPPER))) { ss->currentMove = ttMove; // Can be MOVE_NONE return ttValue; @@ -1145,7 +1125,6 @@ moves_loop: // When in check and at SpNode search starts from here if ( !PvNode && !InCheck && !givesCheck - && move != ttMove && futilityBase > -VALUE_KNOWN_WIN && !pos.advanced_pawn_push(move)) { @@ -1175,11 +1154,13 @@ moves_loop: // When in check and at SpNode search starts from here // Don't search moves with negative SEE values if ( !PvNode && (!InCheck || evasionPrunable) - && move != ttMove && type_of(move) != PROMOTION && pos.see_sign(move) < VALUE_ZERO) continue; + // Speculative prefetch as early as possible + prefetch((char*)TT.first_entry(pos.key_after(move))); + // Check for legality just before making the move if (!pos.legal(move, ci.pinned)) continue; @@ -1201,6 +1182,9 @@ moves_loop: // When in check and at SpNode search starts from here if (value > alpha) { + if (PvNode) // Update pv even in fail-high case + update_pv(ss->pv, move, (ss+1)->pv); + if (PvNode && value < beta) // Update alpha here! Always alpha < beta { alpha = value; @@ -1257,6 +1241,15 @@ moves_loop: // When in check and at SpNode search starts from here } + // update_pv() adds current move and appends child pv[] + + void update_pv(Move* pv, Move move, Move* childPv) { + + for (*pv++ = move; childPv && *childPv != MOVE_NONE; ) + *pv++ = *childPv++; + *pv = MOVE_NONE; + } + // update_stats() updates killers, history, countermoves and followupmoves stats after a fail-high // of a quiet move. @@ -1338,7 +1331,7 @@ moves_loop: // When in check and at SpNode search starts from here // requires that all (if any) unsearched PV lines are sent using a previous // search score. - string uci_pv(const Position& pos, int depth, Value alpha, Value beta) { + string uci_pv(const Position& pos, Depth depth, Value alpha, Value beta) { std::stringstream ss; Time::point elapsed = Time::now() - SearchTime + 1; @@ -1356,23 +1349,23 @@ moves_loop: // When in check and at SpNode search starts from here if (depth == 1 && !updated) continue; - int d = updated ? depth : depth - 1; + Depth d = updated ? depth : depth - ONE_PLY; Value v = updated ? RootMoves[i].score : RootMoves[i].prevScore; if (ss.rdbuf()->in_avail()) // Not at first line ss << "\n"; - ss << "info depth " << d + ss << "info depth " << d / ONE_PLY << " seldepth " << selDepth - << " score " << (i == PVIdx ? score_to_uci(v, alpha, beta) : score_to_uci(v)) + << " multipv " << i + 1 + << " score " << (i == PVIdx ? UCI::format_value(v, alpha, beta) : UCI::format_value(v)) << " nodes " << pos.nodes_searched() << " nps " << pos.nodes_searched() * 1000 / elapsed << " time " << elapsed - << " multipv " << i + 1 << " pv"; - for (size_t j = 0; RootMoves[i].pv[j] != MOVE_NONE; ++j) - ss << " " << move_to_uci(RootMoves[i].pv[j], pos.is_chess960()); + for (size_t j = 0; j < RootMoves[i].pv.size(); ++j) + ss << " " << UCI::format_move(RootMoves[i].pv[j], pos.is_chess960()); } return ss.str(); @@ -1381,54 +1374,18 @@ moves_loop: // When in check and at SpNode search starts from here } // namespace -/// RootMove::extract_pv_from_tt() builds a PV by adding moves from the TT table. -/// We also consider both failing high nodes and BOUND_EXACT nodes here to -/// ensure that we have a ponder move even when we fail high at root. This -/// results in a long PV to print that is important for position analysis. - -void RootMove::extract_pv_from_tt(Position& pos) { - - StateInfo state[MAX_PLY_PLUS_6], *st = state; - const TTEntry* tte; - int ply = 1; // At root ply is 1... - Move m = pv[0]; // ...instead pv[] array starts from 0 - Value expectedScore = score; - - pv.clear(); - - do { - pv.push_back(m); - - assert(MoveList(pos).contains(pv[ply - 1])); - - pos.do_move(pv[ply++ - 1], *st++); - tte = TT.probe(pos.key()); - expectedScore = -expectedScore; - - } while ( tte - && expectedScore == value_from_tt(tte->value(), ply) - && pos.pseudo_legal(m = tte->move()) // Local copy, TT could change - && pos.legal(m, pos.pinned_pieces(pos.side_to_move())) - && ply < MAX_PLY - && (!pos.is_draw() || ply <= 2)); - - pv.push_back(MOVE_NONE); // Must be zero-terminating - - while (--ply) pos.undo_move(pv[ply - 1]); -} - - /// RootMove::insert_pv_in_tt() is called at the end of a search iteration, and /// inserts the PV back into the TT. This makes sure the old PV moves are searched /// first, even if the old TT entries have been overwritten. void RootMove::insert_pv_in_tt(Position& pos) { - StateInfo state[MAX_PLY_PLUS_6], *st = state; + StateInfo state[MAX_PLY], *st = state; const TTEntry* tte; - int idx = 0; // Ply starts from 1, we need to start from 0 + size_t idx = 0; - do { + for ( ; idx < pv.size(); ++idx) + { tte = TT.probe(pos.key()); if (!tte || tte->move() != pv[idx]) // Don't overwrite correct entries @@ -1436,9 +1393,8 @@ void RootMove::insert_pv_in_tt(Position& pos) { assert(MoveList(pos).contains(pv[idx])); - pos.do_move(pv[idx++], *st++); - - } while (pv[idx] != MOVE_NONE); + pos.do_move(pv[idx], *st++); + } while (idx) pos.undo_move(pv[--idx]); } @@ -1454,52 +1410,19 @@ void Thread::idle_loop() { assert(!this_sp || (this_sp->masterThread == this && searching)); - while (true) + while (!exit) { - // If we are not searching, wait for a condition to be signaled instead of - // wasting CPU time polling for work. - while (!searching || exit) - { - if (exit) - { - assert(!this_sp); - return; - } - - // Grab the lock to avoid races with Thread::notify_one() - mutex.lock(); - - // If we are master and all slaves have finished then exit idle_loop - if (this_sp && this_sp->slavesMask.none()) - { - mutex.unlock(); - break; - } - - // Do sleep after retesting sleep conditions under lock protection. In - // particular we need to avoid a deadlock in case a master thread has, - // in the meanwhile, allocated us and sent the notify_one() call before - // we had the chance to grab the lock. - if (!searching && !exit) - sleepCondition.wait(mutex); - - mutex.unlock(); - } - // If this thread has been assigned work, launch a search - if (searching) + while (searching) { - assert(!exit); - Threads.mutex.lock(); - assert(searching); assert(activeSplitPoint); SplitPoint* sp = activeSplitPoint; Threads.mutex.unlock(); - Stack stack[MAX_PLY_PLUS_6], *ss = stack+2; // To allow referencing (ss-2) + Stack stack[MAX_PLY+4], *ss = stack+2; // To allow referencing (ss-2) and (ss+2) Position pos(*sp->pos, this); std::memcpy(ss-2, sp->ss-2, 5 * sizeof(Stack)); @@ -1577,16 +1500,23 @@ void Thread::idle_loop() { } } - // If this thread is the master of a split point and all slaves have finished - // their work at this split point, return from the idle loop. + // Grab the lock to avoid races with Thread::notify_one() + mutex.lock(); + + // If we are master and all slaves have finished then exit idle_loop if (this_sp && this_sp->slavesMask.none()) { - this_sp->mutex.lock(); - bool finished = this_sp->slavesMask.none(); // Retest under lock protection - this_sp->mutex.unlock(); - if (finished) - return; + assert(!searching); + mutex.unlock(); + break; } + + // If we are not searching, wait for a condition to be signaled instead of + // wasting CPU time polling for work. + if (!searching && !exit) + sleepCondition.wait(mutex); + + mutex.unlock(); } } @@ -1598,7 +1528,7 @@ void Thread::idle_loop() { void check_time() { static Time::point lastInfoTime = Time::now(); - int64_t nodes = 0; // Workaround silly 'uninitialized' gcc warning + Time::point elapsed = Time::now() - SearchTime; if (Time::now() - lastInfoTime >= 1000) { @@ -1606,14 +1536,28 @@ void check_time() { dbg_print(); } + // An engine may not stop pondering until told so by the GUI if (Limits.ponder) return; - if (Limits.nodes) + if (Limits.use_time_management()) + { + bool stillAtFirstMove = Signals.firstRootMove + && !Signals.failedLowAtRoot + && elapsed > TimeMgr.available_time() * 75 / 100; + + if ( stillAtFirstMove + || elapsed > TimeMgr.maximum_time() - 2 * TimerThread::Resolution) + Signals.stop = true; + } + else if (Limits.movetime && elapsed >= Limits.movetime) + Signals.stop = true; + + else if (Limits.nodes) { Threads.mutex.lock(); - nodes = RootPos.nodes_searched(); + int64_t nodes = RootPos.nodes_searched(); // Loop across all split points and sum accumulated SplitPoint nodes plus // all the currently active positions nodes. @@ -1634,18 +1578,8 @@ void check_time() { } Threads.mutex.unlock(); - } - - Time::point elapsed = Time::now() - SearchTime; - bool stillAtFirstMove = Signals.firstRootMove - && !Signals.failedLowAtRoot - && elapsed > TimeMgr.available_time() * 75 / 100; - bool noMoreTime = elapsed > TimeMgr.maximum_time() - 2 * TimerThread::Resolution - || stillAtFirstMove; - - if ( (Limits.use_time_management() && noMoreTime) - || (Limits.movetime && elapsed >= Limits.movetime) - || (Limits.nodes && nodes >= Limits.nodes)) - Signals.stop = true; + if (nodes >= Limits.nodes) + Signals.stop = true; + } }