X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=1062c9203a7bbc0c31c0b134e1d1f882d95f4a76;hp=5cdc01698f2425462fdb7ff8929fb29d55c7dcbd;hb=4f906a25897467ba8fc7c31aa634cefc1ec0dba9;hpb=ad1167c482bdda850a83c28d3938553d813e46b9 diff --git a/src/search.cpp b/src/search.cpp index 5cdc0169..1062c920 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -1,7 +1,7 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008-2014 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, 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 @@ -19,64 +19,71 @@ #include #include -#include #include -#include +#include // For std::memset #include #include #include "evaluate.h" +#include "misc.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" +#include "syzygy/tbprobe.h" namespace Search { volatile SignalsType Signals; LimitsType Limits; - std::vector RootMoves; + RootMoveVector RootMoves; Position RootPos; Time::point SearchTime; StateStackPtr SetupStates; } +namespace Tablebases { + + int Cardinality; + uint64_t Hits; + bool RootInTB; + bool UseRule50; + Depth ProbeDepth; + Value Score; +} + +namespace TB = Tablebases; + using std::string; using Eval::evaluate; using namespace Search; namespace { - // Set to true to force running with one thread. Used for debugging - const bool FakeSplit = false; - // Different node types, used as template parameter 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 MultiPV, PVIdx; + size_t PVIdx; TimeManager TimeMgr; double BestMoveChanges; Value DrawValue[COLOR_NB]; @@ -93,22 +100,26 @@ 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) : level(l), best(MOVE_NONE) {} + Skill(int l, size_t rootSize) : level(l), + candidates(l < 20 ? std::min(4, (int)rootSize) : 0), + best(MOVE_NONE) {} ~Skill() { - if (enabled()) // Swap best PV line with the sub-optimal one + if (candidates) // Swap best PV line with the sub-optimal one std::swap(RootMoves[0], *std::find(RootMoves.begin(), RootMoves.end(), best ? best : pick_move())); } - bool enabled() const { return level < 20; } - bool time_to_pick(int depth) const { return depth == 1 + level; } + size_t candidates_size() const { return candidates; } + bool time_to_pick(Depth depth) const { return depth / ONE_PLY == 1 + level; } Move pick_move(); int level; + size_t candidates; Move best; }; @@ -119,59 +130,62 @@ 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, 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::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 @@ -179,65 +193,75 @@ uint64_t Search::perft(Position& pos, Depth depth) { void Search::think() { - TimeMgr.init(Limits, RootPos.game_ply(), RootPos.side_to_move()); + TimeMgr.init(Limits, RootPos.side_to_move(), RootPos.game_ply()); + + int contempt = Options["Contempt"] * PawnValueEg / 100; // From centipawns + DrawValue[ RootPos.side_to_move()] = VALUE_DRAW - Value(contempt); + DrawValue[~RootPos.side_to_move()] = VALUE_DRAW + Value(contempt); - int cf = Options["Contempt Factor"] * PawnValueEg / 100; // From centipawns - DrawValue[ RootPos.side_to_move()] = VALUE_DRAW - Value(cf); - DrawValue[~RootPos.side_to_move()] = VALUE_DRAW + Value(cf); + TB::Hits = 0; + TB::RootInTB = false; + TB::UseRule50 = Options["Syzygy50MoveRule"]; + TB::ProbeDepth = Options["SyzygyProbeDepth"] * ONE_PLY; + TB::Cardinality = Options["SyzygyProbeLimit"]; + + // Skip TB probing when no TB found: !TBLargest -> !TB::Cardinality + if (TB::Cardinality > TB::MaxCardinality) + { + TB::Cardinality = TB::MaxCardinality; + TB::ProbeDepth = DEPTH_ZERO; + } if (RootMoves.empty()) { RootMoves.push_back(MOVE_NONE); sync_cout << "info depth 0 score " - << score_to_uci(RootPos.checkers() ? -VALUE_MATE : VALUE_DRAW) + << UCI::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; - } + if (TB::Cardinality >= RootPos.count(WHITE) + + RootPos.count(BLACK)) + { + // If the current root position is in the tablebases then RootMoves + // contains only moves that preserve the draw or win. + TB::RootInTB = Tablebases::root_probe(RootPos, RootMoves, TB::Score); - // Reset the threads, still sleeping: will wake up at split time - for (size_t i = 0; i < Threads.size(); ++i) - Threads[i]->maxPly = 0; + if (TB::RootInTB) + TB::Cardinality = 0; // Do not probe tablebases during the search - Threads.timer->run = true; - Threads.timer->notify_one(); // Wake up the recurring timer + else // If DTZ tables are missing, use WDL tables as a fallback + { + // Filter out moves that do not preserve a draw or win + TB::RootInTB = Tablebases::root_probe_wdl(RootPos, RootMoves, TB::Score); - id_loop(RootPos); // Let's start searching ! + // Only probe during search if winning + if (TB::Score <= VALUE_DRAW) + TB::Cardinality = 0; + } - Threads.timer->run = false; // Stop the timer + if (TB::RootInTB) + { + TB::Hits = RootMoves.size(); - if (Options["Write Search Log"]) - { - Time::point elapsed = Time::now() - SearchTime + 1; + if (!TB::UseRule50) + TB::Score = TB::Score > VALUE_DRAW ? VALUE_MATE - MAX_PLY - 1 + : TB::Score < VALUE_DRAW ? -VALUE_MATE + MAX_PLY + 1 + : VALUE_DRAW; + } + } - 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]); + for (size_t i = 0; i < Threads.size(); ++i) + Threads[i]->maxPly = 0; - 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 = true; + Threads.timer->notify_one(); // Wake up the recurring timer -finalize: + id_loop(RootPos); // Let's start searching ! - // When search is stopped this info is not printed - sync_cout << "info nodes " << RootPos.nodes_searched() - << " time " << Time::now() - SearchTime + 1 << sync_endl; + Threads.timer->run = false; + } // 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, @@ -250,10 +274,12 @@ 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::move(RootMoves[0].pv[0], RootPos.is_chess960()); + + if (RootMoves[0].pv.size() > 1 || RootMoves[0].extract_ponder_from_tt(RootPos)) + std::cout << " ponder " << UCI::move(RootMoves[0].pv[1], RootPos.is_chess960()); + + std::cout << sync_endl; } @@ -265,13 +291,13 @@ 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; @@ -282,18 +308,15 @@ namespace { Countermoves.clear(); Followupmoves.clear(); - MultiPV = Options["MultiPV"]; - Skill skill(Options["Skill Level"]); + size_t multiPV = Options["MultiPV"]; + Skill skill(Options["Skill Level"], RootMoves.size()); // Do we have to play with skill handicap? In this case enable MultiPV search // that we will use behind the scenes to retrieve a set of possible moves. - if (skill.enabled() && MultiPV < 4) - MultiPV = 4; - - MultiPV = std::min(MultiPV, RootMoves.size()); + 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; @@ -301,17 +324,17 @@ namespace { // Save the last iteration's scores before first PV line is searched and // all the move scores except the (new) PV are set to -VALUE_INFINITE. for (size_t i = 0; i < RootMoves.size(); ++i) - RootMoves[i].prevScore = RootMoves[i].score; + RootMoves[i].previousScore = RootMoves[i].score; // MultiPV loop. We perform a full root search for each PV line - for (PVIdx = 0; PVIdx < MultiPV && !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); - beta = std::min(RootMoves[PVIdx].prevScore + delta, VALUE_INFINITE); + alpha = std::max(RootMoves[PVIdx].previousScore - delta,-VALUE_INFINITE); + beta = std::min(RootMoves[PVIdx].previousScore + delta, VALUE_INFINITE); } // Start with a small aspiration window and, in the case of a fail @@ -319,7 +342,7 @@ 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 @@ -342,7 +365,8 @@ namespace { // When failing high/low give some update (without cluttering // the UI) before a re-search. - if ( (bestValue <= alpha || bestValue >= beta) + if ( multiPV == 1 + && (bestValue <= alpha || bestValue >= beta) && Time::now() - SearchTime > 3000) sync_cout << uci_pv(pos, depth, alpha, beta) << sync_endl; @@ -350,14 +374,17 @@ 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; @@ -369,25 +396,19 @@ 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; } // If skill levels are enabled and time is up, pick a sub-optimal best move - if (skill.enabled() && skill.time_to_pick(depth)) + 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 @@ -398,7 +419,7 @@ namespace { if (Limits.use_time_management() && !Signals.stop && !Signals.stopOnPonderhit) { // Take some extra time if the best move has changed - if (depth > 4 && depth < 50 && 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 @@ -435,15 +456,15 @@ 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; + TTEntry* tte; SplitPoint* splitPoint; Key posKey; Move ttMove, move, excludedMove, bestMove; - Depth ext, newDepth, predictedDepth; + Depth extension, newDepth, predictedDepth; Value bestValue, value, ttValue, eval, nullValue, futilityValue; - bool inCheck, givesCheck, pvMove, singularExtensionNode, improving; + bool ttHit, inCheck, givesCheck, singularExtensionNode, improving; bool captureOrPromotion, dangerous, doFullDepthSearch; int moveCount, quietCount; @@ -457,6 +478,7 @@ namespace { bestMove = splitPoint->bestMove; bestValue = splitPoint->bestValue; tte = NULL; + ttHit = false; ttMove = excludedMove = MOVE_NONE; ttValue = VALUE_NONE; @@ -467,10 +489,7 @@ 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) @@ -479,8 +498,8 @@ 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 @@ -494,26 +513,28 @@ namespace { return alpha; } + assert(0 <= ss->ply && ss->ply < MAX_PLY); + + ss->currentMove = ss->ttMove = (ss+1)->excludedMove = bestMove = MOVE_NONE; + (ss+1)->skipEarlyPruning = 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. excludedMove = ss->excludedMove; posKey = excludedMove ? pos.exclusion_key() : pos.key(); - tte = TT.probe(posKey); - 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 - && tte + tte = TT.probe(posKey, ttHit); + ss->ttMove = ttMove = RootNode ? RootMoves[PVIdx].pv[0] : ttHit ? tte->move() : MOVE_NONE; + ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE; + + // At non-PV nodes we check for a fail high/low. We don't probe at PV nodes + if ( !PvNode + && ttHit && 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 @@ -524,6 +545,36 @@ namespace { return ttValue; } + // Step 4a. Tablebase probe + if (!RootNode && TB::Cardinality) + { + int piecesCnt = pos.count(WHITE) + pos.count(BLACK); + + if ( piecesCnt <= TB::Cardinality + && (piecesCnt < TB::Cardinality || depth >= TB::ProbeDepth) + && pos.rule50_count() == 0) + { + int found, v = Tablebases::probe_wdl(pos, &found); + + if (found) + { + TB::Hits++; + + int drawScore = TB::UseRule50 ? 1 : 0; + + value = v < -drawScore ? -VALUE_MATE + MAX_PLY + ss->ply + : v > drawScore ? VALUE_MATE - MAX_PLY - ss->ply + : VALUE_DRAW + 2 * v * drawScore; + + tte->save(posKey, value_to_tt(value, ss->ply), BOUND_EXACT, + std::min(DEPTH_MAX - ONE_PLY, depth + 6 * ONE_PLY), + MOVE_NONE, VALUE_NONE, TT.generation()); + + return value; + } + } + } + // Step 5. Evaluate the position statically and update parent's gain statistics if (inCheck) { @@ -531,10 +582,10 @@ namespace { goto moves_loop; } - else if (tte) + else if (ttHit) { // Never assume anything on values stored in TT - if ((ss->staticEval = eval = tte->eval_value()) == VALUE_NONE) + if ((ss->staticEval = eval = tte->eval()) == VALUE_NONE) eval = ss->staticEval = evaluate(pos); // Can ttValue be used as a better position evaluation? @@ -547,9 +598,12 @@ namespace { eval = ss->staticEval = (ss-1)->currentMove != MOVE_NULL ? evaluate(pos) : -(ss-1)->staticEval + 2 * Eval::Tempo; - TT.store(posKey, VALUE_NONE, BOUND_NONE, DEPTH_NONE, MOVE_NONE, ss->staticEval); + tte->save(posKey, VALUE_NONE, BOUND_NONE, DEPTH_NONE, MOVE_NONE, ss->staticEval, TT.generation()); } + if (ss->skipEarlyPruning) + goto moves_loop; + if ( !pos.captured_piece_type() && ss->staticEval != VALUE_NONE && (ss-1)->staticEval != VALUE_NONE @@ -566,7 +620,6 @@ namespace { && depth < 4 * ONE_PLY && eval + razor_margin(depth) <= alpha && ttMove == MOVE_NONE - && abs(beta) < VALUE_MATE_IN_MAX_PLY && !pos.pawn_on_7th(pos.side_to_move())) { if ( depth <= ONE_PLY @@ -580,21 +633,17 @@ namespace { } // Step 7. Futility pruning: child node (skipped when in check) - if ( !PvNode - && !ss->skipNullMove + if ( !RootNode && 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); // Step 8. Null move search with verification search (is omitted in PV nodes) if ( !PvNode - && !ss->skipNullMove && depth >= 2 * ONE_PLY && eval >= beta - && abs(beta) < VALUE_MATE_IN_MAX_PLY && pos.non_pawn_material(pos.side_to_move())) { ss->currentMove = MOVE_NULL; @@ -602,15 +651,13 @@ namespace { assert(eval - beta >= 0); // Null move dynamic reduction based on depth and value - Depth R = 3 * ONE_PLY - + depth / 4 - + int(eval - beta) / PawnValueMg * ONE_PLY; + Depth R = ((823 + 67 * depth) / 256 + std::min((eval - beta) / PawnValueMg, 3)) * ONE_PLY; pos.do_null_move(st); - (ss+1)->skipNullMove = true; + (ss+1)->skipEarlyPruning = true; nullValue = depth-R < ONE_PLY ? -qsearch(pos, ss+1, -beta, -beta+1, DEPTH_ZERO) : - search(pos, ss+1, -beta, -beta+1, depth-R, !cutNode); - (ss+1)->skipNullMove = false; + (ss+1)->skipEarlyPruning = false; pos.undo_null_move(); if (nullValue >= beta) @@ -619,14 +666,14 @@ namespace { if (nullValue >= VALUE_MATE_IN_MAX_PLY) nullValue = beta; - if (depth < 12 * ONE_PLY) + if (depth < 12 * ONE_PLY && abs(beta) < VALUE_KNOWN_WIN) return nullValue; // Do verification search at high depths - ss->skipNullMove = true; + ss->skipEarlyPruning = true; Value v = depth-R < ONE_PLY ? qsearch(pos, ss, beta-1, beta, DEPTH_ZERO) : search(pos, ss, beta-1, beta, depth-R, false); - ss->skipNullMove = false; + ss->skipEarlyPruning = false; if (v >= beta) return nullValue; @@ -639,7 +686,6 @@ namespace { // prune the previous move. if ( !PvNode && depth >= 5 * ONE_PLY - && !ss->skipNullMove && abs(beta) < VALUE_MATE_IN_MAX_PLY) { Value rbeta = std::min(beta + 200, VALUE_INFINITE); @@ -656,7 +702,7 @@ namespace { if (pos.legal(move, ci.pinned)) { ss->currentMove = move; - pos.do_move(move, st, ci, pos.gives_check(move, ci)); + pos.do_move(move, st, pos.gives_check(move, ci)); value = -search(pos, ss+1, -rbeta, -rbeta+1, rdepth, !cutNode); pos.undo_move(move); if (value >= rbeta) @@ -669,14 +715,13 @@ namespace { && !ttMove && (PvNode || ss->staticEval + 256 >= beta)) { - Depth d = depth - 2 * ONE_PLY - (PvNode ? DEPTH_ZERO : depth / 4); - - ss->skipNullMove = true; - search(pos, ss, alpha, beta, d, true); - ss->skipNullMove = false; + Depth d = 2 * (depth - 2 * ONE_PLY) - (PvNode ? DEPTH_ZERO : depth / 2); + ss->skipEarlyPruning = true; + search(pos, ss, alpha, beta, d / 2, true); + ss->skipEarlyPruning = false; - tte = TT.probe(posKey); - ttMove = tte ? tte->move() : MOVE_NONE; + tte = TT.probe(posKey, ttHit); + ttMove = ttHit ? tte->move() : MOVE_NONE; } moves_loop: // When in check and at SpNode search starts from here @@ -700,6 +745,8 @@ moves_loop: // When in check and at SpNode search starts from here && !SpNode && depth >= 8 * ONE_PLY && ttMove != MOVE_NONE + /* && ttValue != VALUE_NONE Already implicit in the next condition */ + && abs(ttValue) < VALUE_KNOWN_WIN && !excludedMove // Recursive singular search is not allowed && (tte->bound() & BOUND_LOWER) && tte->depth() >= depth - 3 * ONE_PLY; @@ -737,11 +784,14 @@ moves_loop: // When in check and at SpNode search starts from here if (thisThread == Threads.main() && Time::now() - SearchTime > 3000) sync_cout << "info depth " << depth / ONE_PLY - << " currmove " << move_to_uci(move, pos.is_chess960()) + << " currmove " << UCI::move(move, pos.is_chess960()) << " currmovenumber " << moveCount + PVIdx << sync_endl; } - ext = DEPTH_ZERO; + if (PvNode) + (ss+1)->pv = NULL; + + extension = DEPTH_ZERO; captureOrPromotion = pos.capture_or_promotion(move); givesCheck = type_of(move) == NORMAL && !ci.dcCandidates @@ -754,7 +804,7 @@ moves_loop: // When in check and at SpNode search starts from here // Step 12. Extend checks if (givesCheck && pos.see_sign(move) >= VALUE_ZERO) - ext = ONE_PLY; + extension = ONE_PLY; // Singular extension search. 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 @@ -763,37 +813,33 @@ moves_loop: // When in check and at SpNode search starts from here // ttValue minus a margin then we extend the ttMove. if ( singularExtensionNode && move == ttMove - && !ext - && pos.legal(move, ci.pinned) - && abs(ttValue) < VALUE_KNOWN_WIN) + && !extension + && pos.legal(move, ci.pinned)) { - assert(ttValue != VALUE_NONE); - - Value rBeta = ttValue - int(depth); + Value rBeta = ttValue - 2 * depth / ONE_PLY; ss->excludedMove = move; - ss->skipNullMove = true; + ss->skipEarlyPruning = true; value = search(pos, ss, rBeta - 1, rBeta, depth / 2, cutNode); - ss->skipNullMove = false; + ss->skipEarlyPruning = false; ss->excludedMove = MOVE_NONE; if (value < rBeta) - ext = ONE_PLY; + extension = ONE_PLY; } // Update the current move (this must be done after singular extension search) - newDepth = depth - ONE_PLY + ext; + newDepth = depth - ONE_PLY + extension; - // Step 13. Pruning at shallow depth (exclude PV nodes) - if ( !PvNode + // Step 13. Pruning at shallow depth + if ( !RootNode && !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(); @@ -806,8 +852,8 @@ 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) { @@ -833,6 +879,9 @@ 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)) { @@ -840,31 +889,27 @@ 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; // Step 14. Make the move - pos.do_move(move, st, ci, givesCheck); + pos.do_move(move, st, givesCheck); // 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)] < VALUE_ZERO) 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); @@ -872,7 +917,7 @@ moves_loop: // When in check and at SpNode search starts from here if ( ss->reduction && type_of(move) == NORMAL && type_of(pos.piece_on(to_sq(move))) != PAWN - && pos.see(make_move(to_sq(move), from_sq(move))) < 0) + && pos.see(make_move(to_sq(move), from_sq(move))) < VALUE_ZERO) ss->reduction = std::max(DEPTH_ZERO, ss->reduction - ONE_PLY); Depth d = std::max(newDepth - ss->reduction, ONE_PLY); @@ -892,7 +937,7 @@ 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) @@ -900,20 +945,26 @@ 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); @@ -938,15 +989,20 @@ 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 @@ -964,6 +1020,9 @@ 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 @@ -983,13 +1042,15 @@ moves_loop: // When in check and at SpNode search starts from here && Threads.size() >= 2 && depth >= Threads.minimumSplitDepth && ( !thisThread->activeSplitPoint - || !thisThread->activeSplitPoint->allSlavesSearching) + || !thisThread->activeSplitPoint->allSlavesSearching + || ( int(Threads.size()) > MAX_SLAVES_PER_SPLITPOINT + && thisThread->activeSplitPoint->slavesCount == MAX_SLAVES_PER_SPLITPOINT)) && thisThread->splitPointsSize < MAX_SPLITPOINTS_PER_THREAD) { assert(bestValue > -VALUE_INFINITE && bestValue < beta); - thisThread->split(pos, ss, alpha, beta, &bestValue, &bestMove, - depth, moveCount, &mp, NT, cutNode); + thisThread->split(pos, ss, alpha, beta, &bestValue, &bestMove, + depth, moveCount, &mp, NT, cutNode); if (Signals.stop || thisThread->cutoff_occurred()) return VALUE_ZERO; @@ -1022,10 +1083,10 @@ moves_loop: // When in check and at SpNode search starts from here else if (bestValue >= beta && !pos.capture_or_promotion(bestMove) && !inCheck) update_stats(pos, ss, bestMove, depth, quietsSearched, quietCount - 1); - TT.store(posKey, value_to_tt(bestValue, ss->ply), - bestValue >= beta ? BOUND_LOWER : - PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER, - depth, bestMove, ss->staticEval); + tte->save(posKey, value_to_tt(bestValue, ss->ply), + bestValue >= beta ? BOUND_LOWER : + PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER, + depth, bestMove, ss->staticEval, TT.generation()); assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); @@ -1048,24 +1109,30 @@ 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; + TTEntry* tte; Key posKey; Move ttMove, move, bestMove; Value bestValue, value, ttValue, futilityValue, futilityBase, oldAlpha; - bool givesCheck, evasionPrunable; + bool ttHit, 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 @@ -1075,16 +1142,16 @@ moves_loop: // When in check and at SpNode search starts from here // Transposition table lookup posKey = pos.key(); - tte = TT.probe(posKey); - ttMove = tte ? tte->move() : MOVE_NONE; - ttValue = tte ? value_from_tt(tte->value(),ss->ply) : VALUE_NONE; + tte = TT.probe(posKey, ttHit); + ttMove = ttHit ? tte->move() : MOVE_NONE; + ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE; - if ( tte + if ( !PvNode + && ttHit && 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; @@ -1098,10 +1165,10 @@ moves_loop: // When in check and at SpNode search starts from here } else { - if (tte) + if (ttHit) { // Never assume anything on values stored in TT - if ((ss->staticEval = bestValue = tte->eval_value()) == VALUE_NONE) + if ((ss->staticEval = bestValue = tte->eval()) == VALUE_NONE) ss->staticEval = bestValue = evaluate(pos); // Can ttValue be used as a better position evaluation? @@ -1116,9 +1183,9 @@ moves_loop: // When in check and at SpNode search starts from here // Stand pat. Return immediately if static value is at least beta if (bestValue >= beta) { - if (!tte) - TT.store(pos.key(), value_to_tt(bestValue, ss->ply), BOUND_LOWER, - DEPTH_NONE, MOVE_NONE, ss->staticEval); + if (!ttHit) + tte->save(pos.key(), value_to_tt(bestValue, ss->ply), BOUND_LOWER, + DEPTH_NONE, MOVE_NONE, ss->staticEval, TT.generation()); return bestValue; } @@ -1146,10 +1213,8 @@ moves_loop: // When in check and at SpNode search starts from here : pos.gives_check(move, ci); // Futility pruning - if ( !PvNode - && !InCheck + if ( !InCheck && !givesCheck - && move != ttMove && futilityBase > -VALUE_KNOWN_WIN && !pos.advanced_pawn_push(move)) { @@ -1157,13 +1222,13 @@ moves_loop: // When in check and at SpNode search starts from here futilityValue = futilityBase + PieceValue[EG][pos.piece_on(to_sq(move))]; - if (futilityValue < beta) + if (futilityValue <= alpha) { bestValue = std::max(bestValue, futilityValue); continue; } - if (futilityBase < beta && pos.see(move) <= VALUE_ZERO) + if (futilityBase <= alpha && pos.see(move) <= VALUE_ZERO) { bestValue = std::max(bestValue, futilityBase); continue; @@ -1177,13 +1242,14 @@ moves_loop: // When in check and at SpNode search starts from here && !pos.can_castle(pos.side_to_move()); // Don't search moves with negative SEE values - if ( !PvNode - && (!InCheck || evasionPrunable) - && move != ttMove + if ( (!InCheck || evasionPrunable) && 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; @@ -1191,7 +1257,7 @@ moves_loop: // When in check and at SpNode search starts from here ss->currentMove = move; // Make and search the move - pos.do_move(move, st, ci, givesCheck); + pos.do_move(move, st, givesCheck); value = givesCheck ? -qsearch(pos, ss+1, -beta, -alpha, depth - ONE_PLY) : -qsearch(pos, ss+1, -beta, -alpha, depth - ONE_PLY); pos.undo_move(move); @@ -1205,6 +1271,9 @@ 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; @@ -1212,8 +1281,8 @@ moves_loop: // When in check and at SpNode search starts from here } else // Fail high { - TT.store(posKey, value_to_tt(value, ss->ply), BOUND_LOWER, - ttDepth, move, ss->staticEval); + tte->save(posKey, value_to_tt(value, ss->ply), BOUND_LOWER, + ttDepth, move, ss->staticEval, TT.generation()); return value; } @@ -1226,9 +1295,9 @@ moves_loop: // When in check and at SpNode search starts from here if (InCheck && bestValue == -VALUE_INFINITE) return mated_in(ss->ply); // Plies to mate from the root - TT.store(posKey, value_to_tt(bestValue, ss->ply), - PvNode && bestValue > oldAlpha ? BOUND_EXACT : BOUND_UPPER, - ttDepth, bestMove, ss->staticEval); + tte->save(posKey, value_to_tt(bestValue, ss->ply), + PvNode && bestValue > oldAlpha ? BOUND_EXACT : BOUND_UPPER, + ttDepth, bestMove, ss->staticEval, TT.generation()); assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); @@ -1261,6 +1330,15 @@ 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. @@ -1274,7 +1352,7 @@ moves_loop: // When in check and at SpNode search starts from here // Increase history value of the cut-off move and decrease all the other // played quiet moves. - Value bonus = Value(int(depth) * int(depth)); + Value bonus = Value((depth / ONE_PLY) * (depth / ONE_PLY)); History.update(pos.moved_piece(move), to_sq(move), bonus); for (int i = 0; i < quietsCnt; ++i) { @@ -1296,41 +1374,34 @@ moves_loop: // When in check and at SpNode search starts from here } - // When playing with a strength handicap, choose best move among the MultiPV - // set using a statistical rule dependent on 'level'. Idea by Heinz van Saanen. + // When playing with a strength handicap, choose best move among the first 'candidates' + // RootMoves using a statistical rule dependent on 'level'. Idea by Heinz van Saanen. Move Skill::pick_move() { - static RKISS rk; - - // PRNG sequence should be not deterministic - for (int i = Time::now() % 50; i > 0; --i) - rk.rand(); + // PRNG sequence should be non-deterministic, so we seed it with the time at init + static PRNG rng(Time::now()); // RootMoves are already sorted by score in descending order - int variance = std::min(RootMoves[0].score - RootMoves[MultiPV - 1].score, PawnValueMg); + int variance = std::min(RootMoves[0].score - RootMoves[candidates - 1].score, PawnValueMg); int weakness = 120 - 2 * level; - int max_s = -VALUE_INFINITE; + int maxScore = -VALUE_INFINITE; best = MOVE_NONE; // Choose best move. For each move score we add two terms both dependent on // weakness. One deterministic and bigger for weaker moves, and one random, // then we choose the move with the resulting highest score. - for (size_t i = 0; i < MultiPV; ++i) + for (size_t i = 0; i < candidates; ++i) { - int s = RootMoves[i].score; - - // Don't allow crazy blunders even at very low skills - if (i > 0 && RootMoves[i-1].score > s + 2 * PawnValueMg) - break; + int score = RootMoves[i].score; // This is our magic formula - s += ( weakness * int(RootMoves[0].score - s) - + variance * (rk.rand() % weakness)) / 128; + score += ( weakness * int(RootMoves[0].score - score) + + variance * (rng.rand() % weakness)) / 128; - if (s > max_s) + if (score > maxScore) { - max_s = s; + maxScore = score; best = RootMoves[i].pv[0]; } } @@ -1342,7 +1413,7 @@ 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; @@ -1357,26 +1428,38 @@ moves_loop: // When in check and at SpNode search starts from here { bool updated = (i <= PVIdx); - if (depth == 1 && !updated) + if (depth == ONE_PLY && !updated) continue; - int d = updated ? depth : depth - 1; - Value v = updated ? RootMoves[i].score : RootMoves[i].prevScore; + Depth d = updated ? depth : depth - ONE_PLY; + Value v = updated ? RootMoves[i].score : RootMoves[i].previousScore; + + bool tb = TB::RootInTB && abs(v) < VALUE_MATE - MAX_PLY; + v = tb ? TB::Score : v; 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)) - << " nodes " << pos.nodes_searched() - << " nps " << pos.nodes_searched() * 1000 / elapsed - << " time " << elapsed << " multipv " << i + 1 + << " score " << UCI::value(v); + + if (!tb && i == PVIdx) + ss << (v >= beta ? " lowerbound" : v <= alpha ? " upperbound" : ""); + + ss << " nodes " << pos.nodes_searched() + << " nps " << pos.nodes_searched() * 1000 / elapsed; + + if (elapsed > 1000) // Earlier makes little sense + ss << " hashfull " << TT.hashfull(); + + ss << " tbhits " << TB::Hits + << " time " << elapsed << " 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::move(RootMoves[i].pv[j], pos.is_chess960()); } return ss.str(); @@ -1385,66 +1468,53 @@ 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; +/// 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. - pv.clear(); +void RootMove::insert_pv_in_tt(Position& pos) { - do { - pv.push_back(m); + StateInfo state[MAX_PLY], *st = state; + size_t idx = 0; - assert(MoveList(pos).contains(pv[ply - 1])); + for ( ; idx < pv.size(); ++idx) + { + bool ttHit; + TTEntry* tte = TT.probe(pos.key(), ttHit); - pos.do_move(pv[ply++ - 1], *st++); - tte = TT.probe(pos.key()); - expectedScore = -expectedScore; + if (!ttHit || tte->move() != pv[idx]) // Don't overwrite correct entries + tte->save(pos.key(), VALUE_NONE, BOUND_NONE, DEPTH_NONE, pv[idx], VALUE_NONE, TT.generation()); - } 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)); + assert(MoveList(pos).contains(pv[idx])); - pv.push_back(MOVE_NONE); // Must be zero-terminating + pos.do_move(pv[idx], *st++); + } - while (--ply) pos.undo_move(pv[ply - 1]); + while (idx) pos.undo_move(pv[--idx]); } -/// 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; - const TTEntry* tte; - int idx = 0; // Ply starts from 1, we need to start from 0 - - do { - tte = TT.probe(pos.key()); +/// RootMove::extract_ponder_from_tt() is called in case we have no ponder move before +/// exiting the search, for instance in case we stop the search during a fail high at +/// root. We try hard to have a ponder move to return to the GUI, otherwise in case of +/// 'ponder on' we have nothing to think on. - if (!tte || tte->move() != pv[idx]) // Don't overwrite correct entries - TT.store(pos.key(), VALUE_NONE, BOUND_NONE, DEPTH_NONE, pv[idx], VALUE_NONE); - - assert(MoveList(pos).contains(pv[idx])); +Move RootMove::extract_ponder_from_tt(Position& pos) +{ + StateInfo st; + bool found; - pos.do_move(pv[idx++], *st++); + assert(pv.size() == 1); - } while (pv[idx] != MOVE_NONE); + pos.do_move(pv[0], st); + TTEntry* tte = TT.probe(pos.key(), found); + Move m = found ? tte->move() : MOVE_NONE; + if (!MoveList(pos).contains(m)) + m = MOVE_NONE; - while (idx) pos.undo_move(pv[--idx]); + pos.undo_move(pv[0]); + pv.push_back(m); + return m; } @@ -1458,52 +1528,19 @@ 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)); @@ -1551,46 +1588,76 @@ void Thread::idle_loop() { // Try to late join to another split point if none of its slaves has // already finished. - if (Threads.size() > 2) - for (size_t i = 0; i < Threads.size(); ++i) + SplitPoint* bestSp = NULL; + int bestThread = 0; + int bestScore = INT_MAX; + + for (size_t i = 0; i < Threads.size(); ++i) + { + const int size = Threads[i]->splitPointsSize; // Local copy + sp = size ? &Threads[i]->splitPoints[size - 1] : NULL; + + if ( sp + && sp->allSlavesSearching + && sp->slavesCount < MAX_SLAVES_PER_SPLITPOINT + && available_to(Threads[i])) { - const int size = Threads[i]->splitPointsSize; // Local copy - sp = size ? &Threads[i]->splitPoints[size - 1] : NULL; + // Compute the recursive split points chain size + int level = -1; + for (SplitPoint* spp = Threads[i]->activeSplitPoint; spp; spp = spp->parentSplitPoint) + level++; - if ( sp - && sp->allSlavesSearching - && available_to(Threads[i])) + int score = level * 256 * 256 + sp->slavesCount * 256 - sp->depth * 1; + + if (score < bestScore) { - // Recheck the conditions under lock protection - Threads.mutex.lock(); - sp->mutex.lock(); - - if ( sp->allSlavesSearching - && available_to(Threads[i])) - { - sp->slavesMask.set(idx); - activeSplitPoint = sp; - searching = true; - } - - sp->mutex.unlock(); - Threads.mutex.unlock(); - - break; // Just a single attempt + bestSp = sp; + bestThread = i; + bestScore = score; } } + } + + if (bestSp) + { + sp = bestSp; + + // Recheck the conditions under lock protection + Threads.mutex.lock(); + sp->mutex.lock(); + + if ( sp->allSlavesSearching + && sp->slavesCount < MAX_SLAVES_PER_SPLITPOINT + && available_to(Threads[bestThread])) + { + sp->slavesMask.set(idx); + sp->slavesCount++; + activeSplitPoint = sp; + searching = true; + } + + sp->mutex.unlock(); + Threads.mutex.unlock(); + } } - // 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(); } } @@ -1602,7 +1669,7 @@ 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) { @@ -1610,14 +1677,28 @@ 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. @@ -1638,18 +1719,8 @@ 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; + } }