X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=b75870ff5021968f66d0e0a0aa02271a310cec00;hp=dc488c2b8922df283d51ba1c525e452b83cab7e4;hb=f35e52f030af837ed8a89eecd67a6f746ee2e897;hpb=647402ff7910ff26f5d6b967812d85f5f4259fee diff --git a/src/search.cpp b/src/search.cpp index dc488c2b..f6cf8de8 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) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad + Copyright (C) 2015-2018 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -29,6 +29,7 @@ #include "misc.h" #include "movegen.h" #include "movepick.h" +#include "position.h" #include "search.h" #include "timeman.h" #include "thread.h" @@ -38,15 +39,12 @@ namespace Search { - SignalsType Signals; LimitsType Limits; - StateStackPtr SetupStates; } namespace Tablebases { int Cardinality; - uint64_t Hits; bool RootInTB; bool UseRule50; Depth ProbeDepth; @@ -64,118 +62,90 @@ namespace { // Different node types, used as a template parameter enum NodeType { NonPV, PV }; - // Razoring and futility margin based on depth - const int razor_margin[4] = { 483, 570, 603, 554 }; - Value futility_margin(Depth d) { return Value(200 * d); } + // Sizes and phases of the skip-blocks, used for distributing search depths across the threads + const int SkipSize[] = { 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4 }; + const int SkipPhase[] = { 0, 1, 0, 1, 2, 3, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 5, 6, 7 }; + + // Razor and futility margins + const int RazorMargin1 = 590; + const int RazorMargin2 = 604; + Value futility_margin(Depth d) { return Value(150 * d / ONE_PLY); } // Futility and reductions lookup tables, initialized at startup - int FutilityMoveCounts[2][16]; // [improving][depth] - Depth Reductions[2][2][64][64]; // [pv][improving][depth][moveNumber] + int FutilityMoveCounts[2][16]; // [improving][depth] + int Reductions[2][2][64][64]; // [pv][improving][depth][moveNumber] template Depth reduction(bool i, Depth d, int mn) { - return Reductions[PvNode][i][std::min(d, 63 * ONE_PLY)][std::min(mn, 63)]; + return Reductions[PvNode][i][std::min(d / ONE_PLY, 63)][std::min(mn, 63)] * ONE_PLY; + } + + // History and stats update bonus, based on depth + int stat_bonus(Depth depth) { + int d = depth / ONE_PLY; + return d > 17 ? 0 : d * d + 2 * d - 2; } // Skill structure is used to implement strength limit struct Skill { - Skill(int l) : level(l) {} + 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; } - Move best_move(size_t multiPV) { return best ? best : pick_best(multiPV); } Move pick_best(size_t multiPV); int level; Move best = MOVE_NONE; }; - // EasyMoveManager structure is used to detect an 'easy move'. When the PV is - // stable across multiple search iterations, we can quickly return the best move. - struct EasyMoveManager { - - void clear() { - stableCnt = 0; - expectedPosKey = 0; - pv[0] = pv[1] = pv[2] = MOVE_NONE; - } - - Move get(Key key) const { - return expectedPosKey == key ? pv[2] : MOVE_NONE; - } - - void update(Position& pos, const std::vector& newPv) { - - assert(newPv.size() >= 3); - - // Keep track of how many times in a row the 3rd ply remains stable - stableCnt = (newPv[2] == pv[2]) ? stableCnt + 1 : 0; - - if (!std::equal(newPv.begin(), newPv.begin() + 3, pv)) - { - std::copy(newPv.begin(), newPv.begin() + 3, pv); - - StateInfo st[2]; - pos.do_move(newPv[0], st[0], pos.gives_check(newPv[0], CheckInfo(pos))); - pos.do_move(newPv[1], st[1], pos.gives_check(newPv[1], CheckInfo(pos))); - expectedPosKey = pos.key(); - pos.undo_move(newPv[1]); - pos.undo_move(newPv[0]); - } - } - - int stableCnt; - Key expectedPosKey; - Move pv[3]; - }; - - // Set of rows with half bits set to 1 and half to 0. It is used to allocate - // the search depths across the threads. - typedef std::vector Row; - - const Row HalfDensity[] = { - {0, 1}, - {1, 0}, - {0, 0, 1, 1}, - {0, 1, 1, 0}, - {1, 1, 0, 0}, - {1, 0, 0, 1}, - {0, 0, 0, 1, 1, 1}, - {0, 0, 1, 1, 1, 0}, - {0, 1, 1, 1, 0, 0}, - {1, 1, 1, 0, 0, 0}, - {1, 1, 0, 0, 0, 1}, - {1, 0, 0, 0, 1, 1}, - {0, 0, 0, 0, 1, 1, 1, 1}, - {0, 0, 0, 1, 1, 1, 1, 0}, - {0, 0, 1, 1, 1, 1, 0 ,0}, - {0, 1, 1, 1, 1, 0, 0 ,0}, - {1, 1, 1, 1, 0, 0, 0 ,0}, - {1, 1, 1, 0, 0, 0, 0 ,1}, - {1, 1, 0, 0, 0, 0, 1 ,1}, - {1, 0, 0, 0, 0, 1, 1 ,1}, - }; - - const size_t HalfDensitySize = std::extent::value; - - EasyMoveManager EasyMove; - Value DrawValue[COLOR_NB]; - CounterMoveHistoryStats CounterMoveHistory; - template - Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode); + Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode, bool skipEarlyPruning); template - Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth); + Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth = DEPTH_ZERO); 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); - void check_time(); + 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 quietsCnt, int bonus); + void update_capture_stats(const Position& pos, Move move, Move* captures, int captureCnt, int bonus); + + inline bool gives_check(const Position& pos, Move move) { + Color us = pos.side_to_move(); + return type_of(move) == NORMAL && !(pos.blockers_for_king(~us) & pos.pieces(us)) + ? pos.check_squares(type_of(pos.moved_piece(move))) & to_sq(move) + : pos.gives_check(move); + } + + // 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. + template + uint64_t perft(Position& pos, Depth depth) { + + StateInfo st; + uint64_t cnt, nodes = 0; + const bool leaf = (depth == 2 * ONE_PLY); + + for (const auto& m : MoveList(pos)) + { + if (Root && depth <= ONE_PLY) + cnt = 1, nodes++; + else + { + pos.do_move(m, st); + cnt = leaf ? MoveList(pos).size() : perft(pos, depth - ONE_PLY); + nodes += cnt; + pos.undo_move(m); + } + if (Root) + sync_cout << UCI::move(m, pos.is_chess960()) << ": " << cnt << sync_endl; + } + return nodes; + } } // namespace -/// Search::init() is called during startup to initialize various lookup tables +/// Search::init() is called at startup to initialize various lookup tables void Search::init() { @@ -183,193 +153,114 @@ void Search::init() { for (int d = 1; d < 64; ++d) for (int mc = 1; mc < 64; ++mc) { - double r = log(d) * log(mc) / 2; - if (r < 0.80) - continue; + double r = log(d) * log(mc) / 1.95; - Reductions[NonPV][imp][d][mc] = int(std::round(r)) * ONE_PLY; - Reductions[PV][imp][d][mc] = std::max(Reductions[NonPV][imp][d][mc] - ONE_PLY, DEPTH_ZERO); + Reductions[NonPV][imp][d][mc] = int(std::round(r)); + Reductions[PV][imp][d][mc] = std::max(Reductions[NonPV][imp][d][mc] - 1, 0); // Increase reduction for non-PV nodes when eval is not improving - if (!imp && Reductions[NonPV][imp][d][mc] >= 2 * ONE_PLY) - Reductions[NonPV][imp][d][mc] += ONE_PLY; + if (!imp && Reductions[NonPV][imp][d][mc] >= 2) + Reductions[NonPV][imp][d][mc]++; } for (int d = 0; d < 16; ++d) { - 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)); + FutilityMoveCounts[0][d] = int(2.4 + 0.74 * pow(d, 1.78)); + FutilityMoveCounts[1][d] = int(5.0 + 1.00 * pow(d, 2.00)); } } -/// Search::clear() resets search state to zero, to obtain reproducible results +/// Search::clear() resets search state to its initial value void Search::clear() { - TT.clear(); - CounterMoveHistory.clear(); + Threads.main()->wait_for_search_finished(); - for (Thread* th : Threads) - { - th->history.clear(); - th->counterMoves.clear(); - } - - Threads.main()->previousScore = VALUE_INFINITE; -} - - -/// 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 is returned. -template -uint64_t Search::perft(Position& pos, Depth depth) { - - StateInfo st; - uint64_t cnt, nodes = 0; - CheckInfo ci(pos); - const bool leaf = (depth == 2 * ONE_PLY); - - for (const auto& m : MoveList(pos)) - { - if (Root && depth <= ONE_PLY) - cnt = 1, nodes++; - else - { - pos.do_move(m, st, pos.gives_check(m, ci)); - cnt = leaf ? MoveList(pos).size() : perft(pos, depth - ONE_PLY); - nodes += cnt; - pos.undo_move(m); - } - if (Root) - sync_cout << UCI::move(m, pos.is_chess960()) << ": " << cnt << sync_endl; - } - return nodes; + Time.availableNodes = 0; + TT.clear(); + Threads.clear(); } -template uint64_t Search::perft(Position&, Depth); - /// MainThread::search() is called by the main thread when the program receives /// the UCI 'go' command. It searches from the root position and outputs the "bestmove". void MainThread::search() { - Color us = rootPos.side_to_move(); - Time.init(Limits, us, rootPos.game_ply()); - - int contempt = Options["Contempt"] * PawnValueEg / 100; // From centipawns - DrawValue[ us] = VALUE_DRAW - Value(contempt); - DrawValue[~us] = VALUE_DRAW + Value(contempt); - - 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) + if (Limits.perft) { - TB::Cardinality = TB::MaxCardinality; - TB::ProbeDepth = DEPTH_ZERO; + nodes = perft(rootPos, Limits.perft * ONE_PLY); + sync_cout << "\nNodes searched: " << nodes << "\n" << sync_endl; + return; } + Color us = rootPos.side_to_move(); + Time.init(Limits, us, rootPos.game_ply()); + TT.new_search(); + if (rootMoves.empty()) { - rootMoves.push_back(RootMove(MOVE_NONE)); + rootMoves.emplace_back(MOVE_NONE); sync_cout << "info depth 0 score " << UCI::value(rootPos.checkers() ? -VALUE_MATE : VALUE_DRAW) << sync_endl; } else { - if ( TB::Cardinality >= rootPos.count(WHITE) - + rootPos.count(BLACK) - && !rootPos.can_castle(ANY_CASTLING)) - { - // If the current root position is in the tablebases, then RootMoves - // contains only moves that preserve the draw or the win. - TB::RootInTB = Tablebases::root_probe(rootPos, rootMoves, TB::Score); - - if (TB::RootInTB) - TB::Cardinality = 0; // Do not probe tablebases during the search - - else // If DTZ tables are missing, use WDL tables as a fallback - { - // Filter out moves that do not preserve the draw or the win. - TB::RootInTB = Tablebases::root_probe_wdl(rootPos, rootMoves, TB::Score); - - // Only probe during search if winning - if (TB::Score <= VALUE_DRAW) - TB::Cardinality = 0; - } - - if (TB::RootInTB) - { - TB::Hits = rootMoves.size(); - - 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; - } - } - for (Thread* th : Threads) - { - th->maxPly = 0; - th->rootDepth = DEPTH_ZERO; if (th != this) - { - th->rootPos = Position(rootPos, th); - th->rootMoves = rootMoves; th->start_searching(); - } - } Thread::search(); // Let's start searching! } - // When playing in 'nodes as time' mode, subtract the searched nodes from - // the available ones before exiting. - if (Limits.npmsec) - Time.availableNodes += Limits.inc[us] - Threads.nodes_searched(); - // 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, + // Threads.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 // GUI sends a "stop" or "ponderhit" command. We therefore simply wait here - // until the GUI sends one of those commands (which also raises Signals.stop). - if (!Signals.stop && (Limits.ponder || Limits.infinite)) - { - Signals.stopOnPonderhit = true; - wait(Signals.stop); - } + // until the GUI sends one of those commands (which also raises Threads.stop). + Threads.stopOnPonderhit = true; + + while (!Threads.stop && (Threads.ponder || Limits.infinite)) + {} // Busy wait for a stop or a ponder reset - // Stop the threads if not already stopped - Signals.stop = true; + // Stop the threads if not already stopped (also raise the stop if + // "ponderhit" just reset Threads.ponder). + Threads.stop = true; // Wait until all threads have finished for (Thread* th : Threads) if (th != this) th->wait_for_search_finished(); + // When playing in 'nodes as time' mode, subtract the searched nodes from + // the available ones before exiting. + if (Limits.npmsec) + Time.availableNodes += Limits.inc[us] - Threads.nodes_searched(); + // Check if there are threads with a better score than main thread Thread* bestThread = this; - if ( !this->easyMovePlayed - && Options["MultiPV"] == 1 - && !Skill(Options["Skill Level"]).enabled()) + if ( Options["MultiPV"] == 1 + && !Limits.depth + && !Skill(Options["Skill Level"]).enabled() + && rootMoves[0].pv[0] != MOVE_NONE) { for (Thread* th : Threads) - if ( th->completedDepth > bestThread->completedDepth - && th->rootMoves[0].score > bestThread->rootMoves[0].score) + { + Depth depthDiff = th->completedDepth - bestThread->completedDepth; + Value scoreDiff = th->rootMoves[0].score - bestThread->rootMoves[0].score; + + // Select the thread with the best score, always if it is a mate + if ( scoreDiff > 0 + && (depthDiff >= 0 || th->rootMoves[0].score >= VALUE_MATE_IN_MAX_PLY)) bestThread = th; + } } previousScore = bestThread->rootMoves[0].score; - // Send new PV when needed + // Send again PV info if we have a new best thread if (bestThread != this) sync_cout << UCI::pv(bestThread->rootPos, bestThread->completedDepth, -VALUE_INFINITE, VALUE_INFINITE) << sync_endl; @@ -382,31 +273,29 @@ void MainThread::search() { } -// Thread::search() is the main iterative deepening loop. It calls search() -// repeatedly with increasing depth until the allocated thinking time has been -// consumed, the user stops the search, or the maximum search depth is reached. +/// Thread::search() is the main iterative deepening loop. It calls search() +/// repeatedly with increasing depth until the allocated thinking time has been +/// consumed, the user stops the search, or the maximum search depth is reached. void Thread::search() { - Stack stack[MAX_PLY+4], *ss = stack+2; // To allow referencing (ss-2) and (ss+2) + Stack stack[MAX_PLY+7], *ss = stack+4; // To reference from (ss-4) to (ss+2) Value bestValue, alpha, beta, delta; - Move easyMove = MOVE_NONE; + Move lastBestMove = MOVE_NONE; + Depth lastBestMoveDepth = DEPTH_ZERO; MainThread* mainThread = (this == Threads.main() ? Threads.main() : nullptr); + double timeReduction = 1.0; + Color us = rootPos.side_to_move(); - std::memset(ss-2, 0, 5 * sizeof(Stack)); + std::memset(ss-4, 0, 7 * sizeof(Stack)); + for (int i = 4; i > 0; i--) + (ss-i)->contHistory = this->contHistory[NO_PIECE][0].get(); // Use as sentinel bestValue = delta = alpha = -VALUE_INFINITE; beta = VALUE_INFINITE; - completedDepth = DEPTH_ZERO; if (mainThread) - { - easyMove = EasyMove.get(rootPos.key()); - EasyMove.clear(); - mainThread->easyMovePlayed = mainThread->failedLow = false; - mainThread->bestMoveChanges = 0; - TT.new_search(); - } + mainThread->bestMoveChanges = 0, mainThread->failedLow = false; size_t multiPV = Options["MultiPV"]; Skill skill(Options["Skill Level"]); @@ -418,21 +307,26 @@ void Thread::search() { multiPV = std::min(multiPV, rootMoves.size()); - // Iterative deepening loop until requested to stop or the target depth is reached. - while (++rootDepth < DEPTH_MAX && !Signals.stop && (!Limits.depth || rootDepth <= Limits.depth)) + int ct = Options["Contempt"] * PawnValueEg / 100; // From centipawns + Eval::Contempt = (us == WHITE ? make_score(ct, ct / 2) + : -make_score(ct, ct / 2)); + + // Iterative deepening loop until requested to stop or the target depth is reached + while ( (rootDepth += ONE_PLY) < DEPTH_MAX + && !Threads.stop + && !(Limits.depth && mainThread && rootDepth / ONE_PLY > Limits.depth)) { - // Set up the new depths for the helper threads skipping on average every - // 2nd ply (using a half-density matrix). - if (!mainThread) + // Distribute search depths across the helper threads + if (idx > 0) { - const Row& row = HalfDensity[(idx - 1) % HalfDensitySize]; - if (row[(rootDepth + rootPos.game_ply()) % row.size()]) - continue; + int i = (idx - 1) % 20; + if (((rootDepth / ONE_PLY + rootPos.game_ply() + SkipPhase[i]) / SkipSize[i]) % 2) + continue; // Retry with an incremented rootDepth } // Age out PV variability metric if (mainThread) - mainThread->bestMoveChanges *= 0.505, mainThread->failedLow = false; + mainThread->bestMoveChanges *= 0.517, mainThread->failedLow = false; // 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. @@ -440,22 +334,34 @@ void Thread::search() { rm.previousScore = rm.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 < multiPV && !Threads.stop; ++PVIdx) { + // Reset UCI info selDepth for each depth and each PV line + selDepth = 0; + // Reset aspiration window starting size if (rootDepth >= 5 * ONE_PLY) { delta = Value(18); alpha = std::max(rootMoves[PVIdx].previousScore - delta,-VALUE_INFINITE); beta = std::min(rootMoves[PVIdx].previousScore + delta, VALUE_INFINITE); + + // Adjust contempt based on current bestValue + ct = Options["Contempt"] * PawnValueEg / 100 // From centipawns + + (bestValue > 500 ? 50: // Dynamic contempt + bestValue < -500 ? -50: + bestValue / 10); + + Eval::Contempt = (us == WHITE ? make_score(ct, ct / 2) + : -make_score(ct, ct / 2)); } // Start with a small aspiration window and, in the case of a fail - // high/low, re-search with a bigger window until we're not failing + // high/low, re-search with a bigger window until we don't fail // high/low anymore. while (true) { - bestValue = ::search(rootPos, ss, alpha, beta, rootDepth, false); + bestValue = ::search(rootPos, ss, alpha, beta, rootDepth, false, 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 @@ -465,15 +371,10 @@ void Thread::search() { // search the already searched PV lines are preserved. std::stable_sort(rootMoves.begin() + PVIdx, rootMoves.end()); - // Write PV back to the transposition table in case the relevant - // entries have been overwritten during the search. - for (size_t i = 0; i <= PVIdx; ++i) - rootMoves[i].insert_pv_in_tt(rootPos); - - // If search has been stopped, break immediately. Sorting and - // writing PV back to TT is safe because RootMoves is still - // valid, although it refers to the previous iteration. - if (Signals.stop) + // If search has been stopped, we break immediately. Sorting is + // safe because RootMoves is still valid, although it refers to + // the previous iteration. + if (Threads.stop) break; // When failing high/low give some update (without cluttering @@ -494,14 +395,11 @@ void Thread::search() { if (mainThread) { mainThread->failedLow = true; - Signals.stopOnPonderhit = false; + Threads.stopOnPonderhit = false; } } else if (bestValue >= beta) - { - alpha = (alpha + beta) / 2; beta = std::min(bestValue + delta, VALUE_INFINITE); - } else break; @@ -513,20 +411,25 @@ void Thread::search() { // Sort the PV lines searched so far and update the GUI std::stable_sort(rootMoves.begin(), rootMoves.begin() + PVIdx + 1); - if (!mainThread) - break; - - if (Signals.stop) - sync_cout << "info nodes " << Threads.nodes_searched() - << " time " << Time.elapsed() << sync_endl; - - else if (PVIdx + 1 == multiPV || Time.elapsed() > 3000) + if ( mainThread + && (Threads.stop || PVIdx + 1 == multiPV || Time.elapsed() > 3000)) sync_cout << UCI::pv(rootPos, rootDepth, alpha, beta) << sync_endl; } - if (!Signals.stop) + if (!Threads.stop) completedDepth = rootDepth; + if (rootMoves[0].pv[0] != lastBestMove) { + lastBestMove = rootMoves[0].pv[0]; + lastBestMoveDepth = rootDepth; + } + + // Have we found a "mate in x"? + if ( Limits.mate + && bestValue >= VALUE_MATE_IN_MAX_PLY + && VALUE_MATE - bestValue <= 2 * Limits.mate) + Threads.stop = true; + if (!mainThread) continue; @@ -534,62 +437,49 @@ void Thread::search() { if (skill.enabled() && skill.time_to_pick(rootDepth)) skill.pick_best(multiPV); - // Have we found a "mate in x"? - if ( Limits.mate - && bestValue >= VALUE_MATE_IN_MAX_PLY - && VALUE_MATE - bestValue <= 2 * Limits.mate) - Signals.stop = true; - // Do we have time for the next iteration? Can we stop searching now? - if (Limits.use_time_management()) - { - if (!Signals.stop && !Signals.stopOnPonderhit) + if ( Limits.use_time_management() + && !Threads.stop + && !Threads.stopOnPonderhit) { - // Stop the search if only one legal move is available, or if all - // of the available time has been used, or if we matched an easyMove - // from the previous search and just did a fast verification. - const bool F[] = { !mainThread->failedLow, - bestValue >= mainThread->previousScore }; + const int F[] = { mainThread->failedLow, + bestValue - mainThread->previousScore }; - int improvingFactor = 640 - 160*F[0] - 126*F[1] - 124*F[0]*F[1]; - double unstablePvFactor = 1 + mainThread->bestMoveChanges; + int improvingFactor = std::max(246, std::min(832, 306 + 119 * F[0] - 6 * F[1])); - bool doEasyMove = rootMoves[0].pv[0] == easyMove - && mainThread->bestMoveChanges < 0.03 - && Time.elapsed() > Time.optimum() * 25 / 204; + // If the bestMove is stable over several iterations, reduce time accordingly + timeReduction = 1.0; + for (int i : {3, 4, 5}) + if (lastBestMoveDepth * i < completedDepth) + timeReduction *= 1.25; + // Use part of the gained time from a previous stable move for the current move + double unstablePvFactor = 1.0 + mainThread->bestMoveChanges; + unstablePvFactor *= std::pow(mainThread->previousTimeReduction, 0.528) / timeReduction; + + // Stop the search if we have only one legal move, or if available time elapsed if ( rootMoves.size() == 1 - || Time.elapsed() > Time.optimum() * unstablePvFactor * improvingFactor / 634 - || (mainThread->easyMovePlayed = doEasyMove)) + || Time.elapsed() > Time.optimum() * unstablePvFactor * improvingFactor / 581) { // If we are allowed to ponder do not stop the search now but // keep pondering until the GUI sends "ponderhit" or "stop". - if (Limits.ponder) - Signals.stopOnPonderhit = true; + if (Threads.ponder) + Threads.stopOnPonderhit = true; else - Signals.stop = true; + Threads.stop = true; } } - - if (rootMoves[0].pv.size() >= 3) - EasyMove.update(rootPos, rootMoves[0].pv); - else - EasyMove.clear(); - } } if (!mainThread) return; - // Clear any candidate easy move that wasn't stable for the last search - // iterations; the second condition prevents consecutive fast moves. - if (EasyMove.stableCnt < 6 || mainThread->easyMovePlayed) - EasyMove.clear(); + mainThread->previousTimeReduction = timeReduction; // If skill level is enabled, swap best PV line with the sub-optimal one if (skill.enabled()) - std::swap(rootMoves[0], *std::find(rootMoves.begin(), - rootMoves.end(), skill.best_move(multiPV))); + std::swap(rootMoves[0], *std::find(rootMoves.begin(), rootMoves.end(), + skill.best ? skill.best : skill.pick_best(multiPV))); } @@ -598,57 +488,51 @@ namespace { // search<>() is the main search function for both PV and non-PV nodes template - Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode) { + Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode, bool skipEarlyPruning) { const bool PvNode = NT == PV; - const bool rootNode = PvNode && (ss-1)->ply == 0; + const bool rootNode = PvNode && ss->ply == 0; assert(-VALUE_INFINITE <= alpha && alpha < beta && beta <= VALUE_INFINITE); assert(PvNode || (alpha == beta - 1)); assert(DEPTH_ZERO < depth && depth < DEPTH_MAX); + assert(!(PvNode && cutNode)); + assert(depth / ONE_PLY * ONE_PLY == depth); - Move pv[MAX_PLY+1], quietsSearched[64]; + Move pv[MAX_PLY+1], capturesSearched[32], quietsSearched[64]; StateInfo st; TTEntry* tte; Key posKey; Move ttMove, move, excludedMove, bestMove; - Depth extension, newDepth, predictedDepth; - Value bestValue, value, ttValue, eval, nullValue, futilityValue; + Depth extension, newDepth; + Value bestValue, value, ttValue, eval, maxValue; bool ttHit, inCheck, givesCheck, singularExtensionNode, improving; - bool captureOrPromotion, doFullDepthSearch; - int moveCount, quietCount; + bool captureOrPromotion, doFullDepthSearch, moveCountPruning, skipQuiets, ttCapture, pvExact; + Piece movedPiece; + int moveCount, captureCount, quietCount; // Step 1. Initialize node Thread* thisThread = pos.this_thread(); inCheck = pos.checkers(); - moveCount = quietCount = ss->moveCount = 0; + moveCount = captureCount = quietCount = ss->moveCount = 0; bestValue = -VALUE_INFINITE; - ss->ply = (ss-1)->ply + 1; + maxValue = VALUE_INFINITE; // Check for the available remaining time - if (thisThread->resetCalls.load(std::memory_order_relaxed)) - { - thisThread->resetCalls = false; - thisThread->callsCnt = 0; - } - if (++thisThread->callsCnt > 4096) - { - for (Thread* th : Threads) - th->resetCalls = true; - - check_time(); - } + if (thisThread == Threads.main()) + static_cast(thisThread)->check_time(); - // Used to send selDepth info to GUI - if (PvNode && thisThread->maxPly < ss->ply) - thisThread->maxPly = ss->ply; + // Used to send selDepth info to GUI (selDepth counts from 1, ply from 0) + if (PvNode && thisThread->selDepth < ss->ply + 1) + thisThread->selDepth = ss->ply + 1; if (!rootNode) { // Step 2. Check for aborted search and immediate draw - if (Signals.stop.load(std::memory_order_relaxed) || pos.is_draw() || ss->ply >= MAX_PLY) - return ss->ply >= MAX_PLY && !inCheck ? evaluate(pos) - : DrawValue[pos.side_to_move()]; + if ( Threads.stop.load(std::memory_order_relaxed) + || pos.is_draw(ss->ply) + || ss->ply >= MAX_PLY) + return (ss->ply >= MAX_PLY && !inCheck) ? evaluate(pos) : VALUE_DRAW; // 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 @@ -664,15 +548,24 @@ namespace { assert(0 <= ss->ply && ss->ply < MAX_PLY); + (ss+1)->ply = ss->ply + 1; ss->currentMove = (ss+1)->excludedMove = bestMove = MOVE_NONE; - (ss+1)->skipEarlyPruning = false; + ss->contHistory = thisThread->contHistory[NO_PIECE][0].get(); (ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE; + Square prevSq = to_sq((ss-1)->currentMove); + + // Initialize statScore to zero for the grandchildren of the current position. + // So statScore is shared between all grandchildren and only the first grandchild + // 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. + (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 // position key in case of an excluded move. excludedMove = ss->excludedMove; - posKey = excludedMove ? pos.exclusion_key() : pos.key(); + 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; ttMove = rootNode ? thisThread->rootMoves[thisThread->PVIdx].pv[0] @@ -686,53 +579,82 @@ namespace { && (ttValue >= beta ? (tte->bound() & BOUND_LOWER) : (tte->bound() & BOUND_UPPER))) { - ss->currentMove = ttMove; // Can be MOVE_NONE - - // If ttMove is quiet, update killers, history, counter move on TT hit - if (ttValue >= beta && ttMove && !pos.capture_or_promotion(ttMove)) - update_stats(pos, ss, ttMove, depth, nullptr, 0); + // If ttMove is quiet, update move sorting heuristics on TT hit + if (ttMove) + { + if (ttValue >= beta) + { + if (!pos.capture_or_promotion(ttMove)) + update_quiet_stats(pos, ss, ttMove, nullptr, 0, stat_bonus(depth)); + // Extra penalty for a quiet TT move in previous ply when it gets refuted + if ((ss-1)->moveCount == 1 && !pos.captured_piece()) + update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY)); + } + // Penalty for a quiet ttMove that fails low + else if (!pos.capture_or_promotion(ttMove)) + { + int penalty = -stat_bonus(depth); + thisThread->mainHistory[pos.side_to_move()][from_to(ttMove)] << penalty; + update_continuation_histories(ss, pos.moved_piece(ttMove), to_sq(ttMove), penalty); + } + } return ttValue; } - // Step 4a. Tablebase probe + // Step 5. Tablebases probe if (!rootNode && TB::Cardinality) { - int piecesCnt = pos.count(WHITE) + pos.count(BLACK); + int piecesCount = pos.count(); - if ( piecesCnt <= TB::Cardinality - && (piecesCnt < TB::Cardinality || depth >= TB::ProbeDepth) + if ( piecesCount <= TB::Cardinality + && (piecesCount < TB::Cardinality || depth >= TB::ProbeDepth) && pos.rule50_count() == 0 && !pos.can_castle(ANY_CASTLING)) { - int found, v = Tablebases::probe_wdl(pos, &found); + TB::ProbeState err; + TB::WDLScore wdl = Tablebases::probe_wdl(pos, &err); - if (found) + if (err != TB::ProbeState::FAIL) { - TB::Hits++; + thisThread->tbHits.fetch_add(1, std::memory_order_relaxed); 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; + value = wdl < -drawScore ? -VALUE_MATE + MAX_PLY + ss->ply + 1 + : wdl > drawScore ? VALUE_MATE - MAX_PLY - ss->ply - 1 + : VALUE_DRAW + 2 * wdl * drawScore; + + Bound b = wdl < -drawScore ? BOUND_UPPER + : wdl > drawScore ? BOUND_LOWER : BOUND_EXACT; - 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()); + if ( b == BOUND_EXACT + || (b == BOUND_LOWER ? value >= beta : value <= alpha)) + { + tte->save(posKey, value_to_tt(value, ss->ply), b, + std::min(DEPTH_MAX - ONE_PLY, depth + 6 * ONE_PLY), + MOVE_NONE, VALUE_NONE, TT.generation()); - return value; + return value; + } + + if (PvNode) + { + if (b == BOUND_LOWER) + bestValue = value, alpha = std::max(alpha, bestValue); + else + maxValue = value; + } } } } - // Step 5. Evaluate the position statically + // Step 6. Evaluate the position statically if (inCheck) { ss->staticEval = eval = VALUE_NONE; goto moves_loop; } - else if (ttHit) { // Never assume anything on values stored in TT @@ -740,13 +662,13 @@ namespace { eval = ss->staticEval = evaluate(pos); // Can ttValue be used as a better position evaluation? - if (ttValue != VALUE_NONE) - if (tte->bound() & (ttValue > eval ? BOUND_LOWER : BOUND_UPPER)) - eval = ttValue; + if ( ttValue != VALUE_NONE + && (tte->bound() & (ttValue > eval ? BOUND_LOWER : BOUND_UPPER))) + eval = ttValue; } else { - eval = ss->staticEval = + ss->staticEval = eval = (ss-1)->currentMove != MOVE_NULL ? evaluate(pos) : -(ss-1)->staticEval + 2 * Eval::Tempo; @@ -754,51 +676,50 @@ namespace { ss->staticEval, TT.generation()); } - if (ss->skipEarlyPruning) + if (skipEarlyPruning || !pos.non_pawn_material(pos.side_to_move())) goto moves_loop; - // Step 6. Razoring (skipped when in check) + // Step 7. Razoring (skipped when in check) if ( !PvNode - && depth < 4 * ONE_PLY - && eval + razor_margin[depth] <= alpha - && ttMove == MOVE_NONE) + && depth <= ONE_PLY) { - if ( depth <= ONE_PLY - && eval + razor_margin[3 * ONE_PLY] <= alpha) - return qsearch(pos, ss, alpha, beta, DEPTH_ZERO); - - Value ralpha = alpha - razor_margin[depth]; - Value v = qsearch(pos, ss, ralpha, ralpha+1, DEPTH_ZERO); + if (eval + RazorMargin1 <= alpha) + return qsearch(pos, ss, alpha, alpha+1); + } + else if ( !PvNode + && depth <= 2 * ONE_PLY + && eval + RazorMargin2 <= alpha) + { + Value ralpha = alpha - RazorMargin2; + Value v = qsearch(pos, ss, ralpha, ralpha+1); if (v <= ralpha) return v; } - // Step 7. Futility pruning: child node (skipped when in check) + // Step 8. Futility pruning: child node (skipped when in check) if ( !rootNode && depth < 7 * ONE_PLY && eval - futility_margin(depth) >= beta - && eval < VALUE_KNOWN_WIN // Do not return unproven wins - && pos.non_pawn_material(pos.side_to_move())) - return eval - futility_margin(depth); + && eval < VALUE_KNOWN_WIN) // Do not return unproven wins + return eval; - // Step 8. Null move search with verification search (is omitted in PV nodes) + // Step 9. Null move search with verification search if ( !PvNode - && depth >= 2 * ONE_PLY && eval >= beta - && pos.non_pawn_material(pos.side_to_move())) + && ss->staticEval >= beta - 36 * depth / ONE_PLY + 225 + && (ss->ply >= thisThread->nmp_ply || ss->ply % 2 != thisThread->nmp_odd)) { - ss->currentMove = MOVE_NULL; - assert(eval - beta >= 0); // Null move dynamic reduction based on depth and value - Depth R = ((823 + 67 * depth) / 256 + std::min((eval - beta) / PawnValueMg, 3)) * ONE_PLY; + Depth R = ((823 + 67 * depth / ONE_PLY) / 256 + std::min((eval - beta) / PawnValueMg, 3)) * ONE_PLY; + + ss->currentMove = MOVE_NULL; + ss->contHistory = thisThread->contHistory[NO_PIECE][0].get(); pos.do_null_move(st); - (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)->skipEarlyPruning = false; + Value nullValue = depth-R < ONE_PLY ? -qsearch(pos, ss+1, -beta, -beta+1) + : - search(pos, ss+1, -beta, -beta+1, depth-R, !cutNode, true); pos.undo_null_move(); if (nullValue >= beta) @@ -807,91 +728,101 @@ namespace { if (nullValue >= VALUE_MATE_IN_MAX_PLY) nullValue = beta; - if (depth < 12 * ONE_PLY && abs(beta) < VALUE_KNOWN_WIN) + if (abs(beta) < VALUE_KNOWN_WIN && (depth < 12 * ONE_PLY || thisThread->nmp_ply)) return nullValue; - // Do verification search at high depths - 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->skipEarlyPruning = false; + // Do verification search at high depths. Disable null move pruning + // for side to move for the first part of the remaining search tree. + thisThread->nmp_ply = ss->ply + 3 * (depth-R) / 4; + thisThread->nmp_odd = ss->ply % 2; + + Value v = depth-R < ONE_PLY ? qsearch(pos, ss, beta-1, beta) + : search(pos, ss, beta-1, beta, depth-R, false, true); + + thisThread->nmp_odd = thisThread->nmp_ply = 0; if (v >= beta) return nullValue; } } - // Step 9. ProbCut (skipped when in check) - // If we have a very good capture (i.e. SEE > seeValues[captured_piece_type]) - // and a reduced search returns a value much above beta, we can (almost) - // safely prune the previous move. + // Step 10. ProbCut (skipped when in check) + // 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 && abs(beta) < VALUE_MATE_IN_MAX_PLY) { - Value rbeta = std::min(beta + 200, VALUE_INFINITE); - Depth rdepth = depth - 4 * ONE_PLY; - - assert(rdepth >= ONE_PLY); - assert((ss-1)->currentMove != MOVE_NONE); - assert((ss-1)->currentMove != MOVE_NULL); + assert(is_ok((ss-1)->currentMove)); - MovePicker mp(pos, ttMove, thisThread->history, PieceValue[MG][pos.captured_piece_type()]); - CheckInfo ci(pos); + Value rbeta = std::min(beta + 200, VALUE_INFINITE); + MovePicker mp(pos, ttMove, rbeta - ss->staticEval, &thisThread->captureHistory); while ((move = mp.next_move()) != MOVE_NONE) - if (pos.legal(move, ci.pinned)) + if (pos.legal(move)) { ss->currentMove = move; - pos.do_move(move, st, pos.gives_check(move, ci)); - value = -search(pos, ss+1, -rbeta, -rbeta+1, rdepth, !cutNode); + ss->contHistory = thisThread->contHistory[pos.moved_piece(move)][to_sq(move)].get(); + + assert(depth >= 5 * ONE_PLY); + + pos.do_move(move, st); + + // Perform a preliminary search at depth 1 to verify that the move holds. + // We will only do this search if the depth is not 5, thus avoiding two + // searches at depth 1 in a row. + if (depth != 5 * ONE_PLY) + value = -search(pos, ss+1, -rbeta, -rbeta+1, ONE_PLY, !cutNode, true); + + // If the first search was skipped or was performed and held, perform + // the regular search. + if (depth == 5 * ONE_PLY || value >= rbeta) + value = -search(pos, ss+1, -rbeta, -rbeta+1, depth - 4 * ONE_PLY, !cutNode, false); + pos.undo_move(move); if (value >= rbeta) return value; } } - // Step 10. Internal iterative deepening (skipped when in check) - if ( depth >= (PvNode ? 5 * ONE_PLY : 8 * ONE_PLY) + // Step 11. Internal iterative deepening (skipped when in check) + if ( depth >= 6 * ONE_PLY && !ttMove && (PvNode || ss->staticEval + 256 >= beta)) { - Depth d = depth - 2 * ONE_PLY - (PvNode ? DEPTH_ZERO : depth / 4); - ss->skipEarlyPruning = true; - search(pos, ss, alpha, beta, d, true); - ss->skipEarlyPruning = false; + Depth d = 3 * depth / 4 - 2 * ONE_PLY; + search(pos, ss, alpha, beta, d, cutNode, true); tte = TT.probe(posKey, ttHit); + ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE; ttMove = ttHit ? tte->move() : MOVE_NONE; } -moves_loop: // When in check search starts from here +moves_loop: // When in check, search starts from here - Square prevSq = to_sq((ss-1)->currentMove); - Square ownPrevSq = to_sq((ss-2)->currentMove); - Move cm = thisThread->counterMoves[pos.piece_on(prevSq)][prevSq]; - const CounterMoveStats& cmh = CounterMoveHistory[pos.piece_on(prevSq)][prevSq]; - const CounterMoveStats& fmh = CounterMoveHistory[pos.piece_on(ownPrevSq)][ownPrevSq]; + const PieceToHistory* contHist[] = { (ss-1)->contHistory, (ss-2)->contHistory, nullptr, (ss-4)->contHistory }; + Move countermove = thisThread->counterMoves[pos.piece_on(prevSq)][prevSq]; - MovePicker mp(pos, ttMove, depth, thisThread->history, cmh, fmh, cm, ss); - CheckInfo ci(pos); + MovePicker mp(pos, ttMove, depth, &thisThread->mainHistory, &thisThread->captureHistory, contHist, countermove, ss->killers); value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc improving = ss->staticEval >= (ss-2)->staticEval - || ss->staticEval == VALUE_NONE + /* || ss->staticEval == VALUE_NONE Already implicit in the previous condition */ ||(ss-2)->staticEval == VALUE_NONE; singularExtensionNode = !rootNode && depth >= 8 * ONE_PLY && ttMove != MOVE_NONE - /* && ttValue != VALUE_NONE Already implicit in the next condition */ - && abs(ttValue) < VALUE_KNOWN_WIN + && ttValue != VALUE_NONE && !excludedMove // Recursive singular search is not allowed && (tte->bound() & BOUND_LOWER) && tte->depth() >= depth - 3 * ONE_PLY; + skipQuiets = false; + ttCapture = false; + pvExact = PvNode && ttHit && tte->bound() == BOUND_EXACT; - // Step 11. Loop through moves - // Loop through all pseudo-legal moves until no moves remain or a beta cutoff occurs - while ((move = mp.next_move()) != MOVE_NONE) + // Step 12. Loop through all pseudo-legal moves until no moves remain + // or a beta cutoff occurs. + while ((move = mp.next_move(skipQuiets)) != MOVE_NONE) { assert(is_ok(move)); @@ -911,143 +842,173 @@ moves_loop: // When in check search starts from here sync_cout << "info depth " << depth / ONE_PLY << " currmove " << UCI::move(move, pos.is_chess960()) << " currmovenumber " << moveCount + thisThread->PVIdx << sync_endl; - if (PvNode) (ss+1)->pv = nullptr; extension = DEPTH_ZERO; captureOrPromotion = pos.capture_or_promotion(move); + movedPiece = pos.moved_piece(move); + givesCheck = gives_check(pos, move); - givesCheck = type_of(move) == NORMAL && !ci.dcCandidates - ? ci.checkSquares[type_of(pos.piece_on(from_sq(move)))] & to_sq(move) - : pos.gives_check(move, ci); + moveCountPruning = depth < 16 * ONE_PLY + && moveCount >= FutilityMoveCounts[improving][depth / ONE_PLY]; - // Step 12. Extend checks - if (givesCheck && pos.see_sign(move) >= VALUE_ZERO) - extension = ONE_PLY; + // Step 13. Extensions - // 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 - // 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 extend the ttMove. + // 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 is singular and should be extended. To verify this we do a + // reduced search on 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 ( singularExtensionNode && move == ttMove - && !extension - && pos.legal(move, ci.pinned)) + && pos.legal(move)) { - Value rBeta = ttValue - 2 * depth / ONE_PLY; + Value rBeta = std::max(ttValue - 2 * depth / ONE_PLY, -VALUE_MATE); ss->excludedMove = move; - ss->skipEarlyPruning = true; - value = search(pos, ss, rBeta - 1, rBeta, depth / 2, cutNode); - ss->skipEarlyPruning = false; + value = search(pos, ss, rBeta - 1, rBeta, depth / 2, cutNode, true); ss->excludedMove = MOVE_NONE; if (value < rBeta) extension = ONE_PLY; } + else if ( givesCheck // Check extension + && !moveCountPruning + && pos.see_ge(move)) + extension = ONE_PLY; - // Update the current move (this must be done after singular extension search) + // Calculate new depth for this move newDepth = depth - ONE_PLY + extension; - // Step 13. Pruning at shallow depth - if ( !rootNode - && !captureOrPromotion - && !inCheck - && !givesCheck - && !pos.advanced_pawn_push(move) - && bestValue > VALUE_MATED_IN_MAX_PLY) + // Step 14. Pruning at shallow depth + if ( !rootNode + && pos.non_pawn_material(pos.side_to_move()) + && bestValue > VALUE_MATED_IN_MAX_PLY) { - // Move count based pruning - if ( depth < 16 * ONE_PLY - && moveCount >= FutilityMoveCounts[improving][depth]) - continue; + if ( !captureOrPromotion + && !givesCheck + && (!pos.advanced_pawn_push(move) || pos.non_pawn_material() >= Value(5000))) + { + // Move count based pruning + if (moveCountPruning) + { + skipQuiets = true; + continue; + } - // History based pruning - if ( depth <= 4 * ONE_PLY - && move != ss->killers[0] - && thisThread->history[pos.moved_piece(move)][to_sq(move)] < VALUE_ZERO - && cmh[pos.moved_piece(move)][to_sq(move)] < VALUE_ZERO) - continue; + // Reduced depth of the next LMR search + int lmrDepth = std::max(newDepth - reduction(improving, depth, moveCount), DEPTH_ZERO) / ONE_PLY; - predictedDepth = std::max(newDepth - reduction(improving, depth, moveCount), DEPTH_ZERO); + // Countermoves based pruning + if ( lmrDepth < 3 + && (*contHist[0])[movedPiece][to_sq(move)] < CounterMovePruneThreshold + && (*contHist[1])[movedPiece][to_sq(move)] < CounterMovePruneThreshold) + continue; - // Futility pruning: parent node - if (predictedDepth < 7 * ONE_PLY) - { - futilityValue = ss->staticEval + futility_margin(predictedDepth) + 256; + // Futility pruning: parent node + if ( lmrDepth < 7 + && !inCheck + && ss->staticEval + 256 + 200 * lmrDepth <= alpha) + continue; - if (futilityValue <= alpha) - { - bestValue = std::max(bestValue, futilityValue); + // Prune moves with negative SEE + if ( lmrDepth < 8 + && !pos.see_ge(move, Value(-35 * lmrDepth * lmrDepth))) continue; - } } - - // Prune moves with negative SEE at low depths - if (predictedDepth < 4 * ONE_PLY && pos.see_sign(move) < VALUE_ZERO) - continue; + else if ( depth < 7 * ONE_PLY + && !extension + && !pos.see_ge(move, -PawnValueEg * (depth / ONE_PLY))) + continue; } // Speculative prefetch as early as possible prefetch(TT.first_entry(pos.key_after(move))); // Check for legality just before making the move - if (!rootNode && !pos.legal(move, ci.pinned)) + if (!rootNode && !pos.legal(move)) { ss->moveCount = --moveCount; continue; } + if (move == ttMove && captureOrPromotion) + ttCapture = true; + + // Update the current move (this must be done after singular extension search) ss->currentMove = move; + ss->contHistory = thisThread->contHistory[movedPiece][to_sq(move)].get(); - // Step 14. Make the move + // Step 15. Make the move pos.do_move(move, st, givesCheck); - // Step 15. Reduced depth search (LMR). If the move fails high it will be + // Step 16. Reduced depth search (LMR). If the move fails high it will be // re-searched at full depth. if ( depth >= 3 * ONE_PLY && moveCount > 1 - && !captureOrPromotion) + && (!captureOrPromotion || moveCountPruning)) { Depth r = reduction(improving, depth, moveCount); - Value hValue = thisThread->history[pos.piece_on(to_sq(move))][to_sq(move)]; - Value cmhValue = cmh[pos.piece_on(to_sq(move))][to_sq(move)]; - - // Increase reduction for cut nodes and moves with a bad history - if ( (!PvNode && cutNode) - || (hValue < VALUE_ZERO && cmhValue <= VALUE_ZERO)) - r += ONE_PLY; - - // Decrease/increase reduction for moves with a good/bad history - int rHist = (hValue + cmhValue) / 14980; - r = std::max(DEPTH_ZERO, r - rHist * ONE_PLY); - - // 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(). Also use see() instead of see_sign(), - // because the destination square is empty. - if ( r - && type_of(move) == NORMAL - && type_of(pos.piece_on(to_sq(move))) != PAWN - && pos.see(make_move(to_sq(move), from_sq(move))) < VALUE_ZERO) - r = std::max(DEPTH_ZERO, r - ONE_PLY); + + if (captureOrPromotion) + r -= r ? ONE_PLY : DEPTH_ZERO; + else + { + // Decrease reduction if opponent's move count is high + if ((ss-1)->moveCount > 15) + r -= ONE_PLY; + + // Decrease reduction for exact PV nodes + if (pvExact) + r -= ONE_PLY; + + // Increase reduction if ttMove is a capture + if (ttCapture) + r += ONE_PLY; + + // Increase reduction for cut nodes + if (cutNode) + r += 2 * ONE_PLY; + + // 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(). + else if ( type_of(move) == NORMAL + && !pos.see_ge(make_move(to_sq(move), from_sq(move)))) + r -= 2 * ONE_PLY; + + ss->statScore = thisThread->mainHistory[~pos.side_to_move()][from_to(move)] + + (*contHist[0])[movedPiece][to_sq(move)] + + (*contHist[1])[movedPiece][to_sq(move)] + + (*contHist[3])[movedPiece][to_sq(move)] + - 4000; + + // Decrease/increase reduction by comparing opponent's stat score + if (ss->statScore >= 0 && (ss-1)->statScore < 0) + r -= ONE_PLY; + + else if ((ss-1)->statScore >= 0 && ss->statScore < 0) + r += ONE_PLY; + + // Decrease/increase reduction for moves with a good/bad history + r = std::max(DEPTH_ZERO, (r / ONE_PLY - ss->statScore / 20000) * ONE_PLY); + } Depth d = std::max(newDepth - r, ONE_PLY); - value = -search(pos, ss+1, -(alpha+1), -alpha, d, true); + value = -search(pos, ss+1, -(alpha+1), -alpha, d, true, false); - doFullDepthSearch = (value > alpha && r != DEPTH_ZERO); + doFullDepthSearch = (value > alpha && d != newDepth); } else doFullDepthSearch = !PvNode || moveCount > 1; - // Step 16. Full depth search when LMR is skipped or fails high + // Step 17. Full depth search when LMR is skipped or fails high if (doFullDepthSearch) 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); + givesCheck ? -qsearch(pos, ss+1, -(alpha+1), -alpha) + : -qsearch(pos, ss+1, -(alpha+1), -alpha) + : - search(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode, false); // 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 @@ -1058,21 +1019,21 @@ moves_loop: // When in check search starts from here (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); + givesCheck ? -qsearch(pos, ss+1, -beta, -alpha) + : -qsearch(pos, ss+1, -beta, -alpha) + : - search(pos, ss+1, -beta, -alpha, newDepth, false, false); } - // Step 17. Undo move + // Step 18. Undo move pos.undo_move(move); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); - // Step 18. Check for a new best move + // Step 19. Check for a new best move // Finished searching the move. If a stop occurred, the return value of // the search cannot be trusted, and we return immediately without // updating best move, PV and TT. - if (Signals.stop.load(std::memory_order_relaxed)) + if (Threads.stop.load(std::memory_order_relaxed)) return VALUE_ZERO; if (rootNode) @@ -1080,10 +1041,11 @@ moves_loop: // When in check search starts from here RootMove& rm = *std::find(thisThread->rootMoves.begin(), thisThread->rootMoves.end(), move); - // PV move or new best move ? + // PV move or new best move? if (moveCount == 1 || value > alpha) { rm.score = value; + rm.selDepth = thisThread->selDepth; rm.pv.resize(1); assert((ss+1)->pv); @@ -1098,8 +1060,8 @@ moves_loop: // When in check search starts from here ++static_cast(thisThread)->bestMoveChanges; } else - // All other moves but the PV are set to the lowest value: this is - // not a problem when sorting because the sort is stable and the + // All other moves but the PV are set to the lowest value: this + // is not a problem when sorting because the sort is stable and the // move position in the list is preserved - just the PV is pushed up. rm.score = -VALUE_INFINITE; } @@ -1110,13 +1072,6 @@ moves_loop: // When in check search starts from here if (value > alpha) { - // If there is an easy move for this position, clear it if unstable - if ( PvNode - && thisThread == Threads.main() - && EasyMove.get(pos.key()) - && (move != EasyMove.get(pos.key()) || moveCount > 1)) - EasyMove.clear(); - bestMove = move; if (PvNode && !rootNode) // Update pv even in fail-high case @@ -1132,15 +1087,21 @@ moves_loop: // When in check search starts from here } } - if (!captureOrPromotion && move != bestMove && quietCount < 64) - quietsSearched[quietCount++] = move; + if (move != bestMove) + { + if (captureOrPromotion && captureCount < 32) + capturesSearched[captureCount++] = move; + + else if (!captureOrPromotion && quietCount < 64) + quietsSearched[quietCount++] = move; + } } // The following condition would detect a stop only after move loop has been // completed. But in this case bestValue is valid because we have fully // searched our subtree, and we can anyhow save the result in TT. /* - if (Signals.stop) + if (Threads.stop) return VALUE_DRAW; */ @@ -1148,32 +1109,38 @@ moves_loop: // When in check search starts from here // All legal moves have been searched and if there are no legal moves, it // must be a mate or a stalemate. If we are in a singular extension search then // return a fail low score. + + assert(moveCount || !inCheck || excludedMove || !MoveList(pos).size()); + if (!moveCount) bestValue = excludedMove ? alpha - : inCheck ? mated_in(ss->ply) : DrawValue[pos.side_to_move()]; - - // Quiet best move: update killers, history and countermoves - else if (bestMove && !pos.capture_or_promotion(bestMove)) - update_stats(pos, ss, bestMove, depth, quietsSearched, quietCount); + : 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)); + else + update_capture_stats(pos, bestMove, capturesSearched, captureCount, stat_bonus(depth)); + // Extra penalty for a quiet TT move in previous ply when it gets refuted + if ((ss-1)->moveCount == 1 && !pos.captured_piece()) + update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY)); + } // Bonus for prior countermove that caused the fail low else if ( depth >= 3 * ONE_PLY - && !bestMove - && !inCheck - && !pos.captured_piece_type() - && is_ok((ss - 1)->currentMove) - && is_ok((ss - 2)->currentMove)) - { - Value bonus = Value((depth / ONE_PLY) * (depth / ONE_PLY) + depth / ONE_PLY - 1); - Square prevPrevSq = to_sq((ss - 2)->currentMove); - CounterMoveStats& prevCmh = CounterMoveHistory[pos.piece_on(prevPrevSq)][prevPrevSq]; - prevCmh.update(pos.piece_on(prevSq), prevSq, bonus); - } + && !pos.captured_piece() + && is_ok((ss-1)->currentMove)) + update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, stat_bonus(depth)); - 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()); + if (PvNode) + bestValue = std::min(bestValue, maxValue); + + if (!excludedMove) + 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); @@ -1182,27 +1149,28 @@ moves_loop: // When in check search starts from here // qsearch() is the quiescence search function, which is called by the main - // search function when the remaining depth is zero (or, to be more precise, - // less than ONE_PLY). + // search function with depth zero, or recursively with depth less than ONE_PLY. template Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) { const bool PvNode = NT == PV; - assert(InCheck == !!pos.checkers()); 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(InCheck == bool(pos.checkers())); Move pv[MAX_PLY+1]; StateInfo st; TTEntry* tte; Key posKey; Move ttMove, move, bestMove; + Depth ttDepth; Value bestValue, value, ttValue, futilityValue, futilityBase, oldAlpha; bool ttHit, givesCheck, evasionPrunable; - Depth ttDepth; + int moveCount; if (PvNode) { @@ -1211,13 +1179,14 @@ moves_loop: // When in check search starts from here ss->pv[0] = MOVE_NONE; } + (ss+1)->ply = ss->ply + 1; ss->currentMove = bestMove = MOVE_NONE; - ss->ply = (ss-1)->ply + 1; + moveCount = 0; - // 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()]; + // Check for an immediate draw or maximum ply reached + if ( pos.is_draw(ss->ply) + || ss->ply >= MAX_PLY) + return (ss->ply >= MAX_PLY && !InCheck) ? evaluate(pos) : VALUE_DRAW; assert(0 <= ss->ply && ss->ply < MAX_PLY); @@ -1226,12 +1195,11 @@ moves_loop: // When in check search starts from here // only two types of depth in TT: DEPTH_QS_CHECKS or DEPTH_QS_NO_CHECKS. ttDepth = InCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS : DEPTH_QS_NO_CHECKS; - // Transposition table lookup posKey = pos.key(); tte = TT.probe(posKey, ttHit); - ttMove = ttHit ? tte->move() : MOVE_NONE; ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE; + ttMove = ttHit ? tte->move() : MOVE_NONE; if ( !PvNode && ttHit @@ -1239,10 +1207,7 @@ moves_loop: // When in check search starts from here && ttValue != VALUE_NONE // Only in case of TT access race && (ttValue >= beta ? (tte->bound() & BOUND_LOWER) : (tte->bound() & BOUND_UPPER))) - { - ss->currentMove = ttMove; // Can be MOVE_NONE return ttValue; - } // Evaluate the position statically if (InCheck) @@ -1259,9 +1224,9 @@ moves_loop: // When in check search starts from here ss->staticEval = bestValue = evaluate(pos); // Can ttValue be used as a better position evaluation? - if (ttValue != VALUE_NONE) - if (tte->bound() & (ttValue > bestValue ? BOUND_LOWER : BOUND_UPPER)) - bestValue = ttValue; + if ( ttValue != VALUE_NONE + && (tte->bound() & (ttValue > bestValue ? BOUND_LOWER : BOUND_UPPER))) + bestValue = ttValue; } else ss->staticEval = bestValue = @@ -1272,7 +1237,7 @@ moves_loop: // When in check search starts from here if (bestValue >= beta) { if (!ttHit) - tte->save(pos.key(), value_to_tt(bestValue, ss->ply), BOUND_LOWER, + tte->save(posKey, value_to_tt(bestValue, ss->ply), BOUND_LOWER, DEPTH_NONE, MOVE_NONE, ss->staticEval, TT.generation()); return bestValue; @@ -1288,17 +1253,16 @@ moves_loop: // When in check search starts from here // to search the moves. Because the depth is <= 0 here, only captures, // queen promotions and checks (only if depth >= DEPTH_QS_CHECKS) will // be generated. - MovePicker mp(pos, ttMove, depth, pos.this_thread()->history, to_sq((ss-1)->currentMove)); - CheckInfo ci(pos); + MovePicker mp(pos, ttMove, depth, &pos.this_thread()->mainHistory, &pos.this_thread()->captureHistory, to_sq((ss-1)->currentMove)); // Loop through the moves until no moves remain or a beta cutoff occurs while ((move = mp.next_move()) != MOVE_NONE) { assert(is_ok(move)); - givesCheck = type_of(move) == NORMAL && !ci.dcCandidates - ? ci.checkSquares[type_of(pos.piece_on(from_sq(move)))] & to_sq(move) - : pos.gives_check(move, ci); + givesCheck = gives_check(pos, move); + + moveCount++; // Futility pruning if ( !InCheck @@ -1316,7 +1280,7 @@ moves_loop: // When in check search starts from here continue; } - if (futilityBase <= alpha && pos.see(move) <= VALUE_ZERO) + if (futilityBase <= alpha && !pos.see_ge(move, VALUE_ZERO + 1)) { bestValue = std::max(bestValue, futilityBase); continue; @@ -1325,21 +1289,24 @@ 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) && bestValue > VALUE_MATED_IN_MAX_PLY && !pos.capture(move); // Don't search moves with negative SEE values if ( (!InCheck || evasionPrunable) - && type_of(move) != PROMOTION - && pos.see_sign(move) < VALUE_ZERO) + && !pos.see_ge(move)) continue; // Speculative prefetch as early as possible prefetch(TT.first_entry(pos.key_after(move))); // Check for legality just before making the move - if (!pos.legal(move, ci.pinned)) + if (!pos.legal(move)) + { + moveCount--; continue; + } ss->currentMove = move; @@ -1427,11 +1394,41 @@ moves_loop: // When in check search starts from here } - // update_stats() updates killers, history, countermove and countermove plus - // follow-up move history when a new quiet best move is found. + // update_continuation_histories() updates histories of the move pairs formed + // by moves at ply -1, -2, and -4 with current move. - void update_stats(const Position& pos, Stack* ss, Move move, - Depth depth, Move* quiets, int quietsCnt) { + void update_continuation_histories(Stack* ss, Piece pc, Square to, int bonus) { + + for (int i : {1, 2, 4}) + if (is_ok((ss-i)->currentMove)) + (*(ss-i)->contHistory)[pc][to] << bonus; + } + + + // update_capture_stats() updates move sorting heuristics when a new capture best move is found + + void update_capture_stats(const Position& pos, Move move, + Move* captures, int captureCnt, int bonus) { + + CapturePieceToHistory& captureHistory = pos.this_thread()->captureHistory; + Piece moved_piece = pos.moved_piece(move); + PieceType captured = type_of(pos.piece_on(to_sq(move))); + captureHistory[moved_piece][to_sq(move)][captured] << bonus; + + // Decrease all the other played capture moves + for (int i = 0; i < captureCnt; ++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_quiet_stats() updates move sorting heuristics when a new quiet best move is found + + void update_quiet_stats(const Position& pos, Stack* ss, Move move, + Move* quiets, int quietsCnt, int bonus) { if (ss->killers[0] != move) { @@ -1439,55 +1436,31 @@ moves_loop: // When in check search starts from here ss->killers[0] = move; } - Value bonus = Value((depth / ONE_PLY) * (depth / ONE_PLY) + depth / ONE_PLY - 1); - - Square prevSq = to_sq((ss-1)->currentMove); - Square ownPrevSq = to_sq((ss-2)->currentMove); - CounterMoveStats& cmh = CounterMoveHistory[pos.piece_on(prevSq)][prevSq]; - CounterMoveStats& fmh = CounterMoveHistory[pos.piece_on(ownPrevSq)][ownPrevSq]; + Color us = pos.side_to_move(); Thread* thisThread = pos.this_thread(); - - thisThread->history.update(pos.moved_piece(move), to_sq(move), bonus); + thisThread->mainHistory[us][from_to(move)] << bonus; + update_continuation_histories(ss, pos.moved_piece(move), to_sq(move), bonus); if (is_ok((ss-1)->currentMove)) { - thisThread->counterMoves.update(pos.piece_on(prevSq), prevSq, move); - cmh.update(pos.moved_piece(move), to_sq(move), bonus); + Square prevSq = to_sq((ss-1)->currentMove); + thisThread->counterMoves[pos.piece_on(prevSq)][prevSq] = move; } - if (is_ok((ss-2)->currentMove)) - fmh.update(pos.moved_piece(move), to_sq(move), bonus); - // Decrease all the other played quiet moves for (int i = 0; i < quietsCnt; ++i) { - thisThread->history.update(pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus); - - if (is_ok((ss-1)->currentMove)) - cmh.update(pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus); - - if (is_ok((ss-2)->currentMove)) - fmh.update(pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus); - } - - // Extra penalty for a quiet TT move in previous ply when it gets refuted - if ( (ss-1)->moveCount == 1 - && !pos.captured_piece_type() - && is_ok((ss-2)->currentMove)) - { - Square prevPrevSq = to_sq((ss-2)->currentMove); - CounterMoveStats& prevCmh = CounterMoveHistory[pos.piece_on(prevPrevSq)][prevPrevSq]; - prevCmh.update(pos.piece_on(prevSq), prevSq, -bonus - 2 * (depth + 1) / ONE_PLY); + 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 // using a statistical rule dependent on 'level'. Idea by Heinz van Saanen. Move Skill::pick_best(size_t multiPV) { - const Search::RootMoveVector& rootMoves = Threads.main()->rootMoves; + const RootMoves& rootMoves = Threads.main()->rootMoves; static PRNG rng(now()); // PRNG sequence should be non-deterministic // RootMoves are already sorted by score in descending order @@ -1505,7 +1478,7 @@ moves_loop: // When in check search starts from here int push = ( weakness * int(topScore - rootMoves[i].score) + delta * (rng.rand() % weakness)) / 128; - if (rootMoves[i].score + push > maxScore) + if (rootMoves[i].score + push >= maxScore) { maxScore = rootMoves[i].score + push; best = rootMoves[i].pv[0]; @@ -1515,34 +1488,39 @@ moves_loop: // When in check search starts from here return best; } +} // namespace - // check_time() is used to print debug info and, more importantly, to detect - // when we are out of available time and thus stop the search. +/// MainThread::check_time() is used to print debug info and, more importantly, +/// to detect when we are out of available time and thus stop the search. - void check_time() { +void MainThread::check_time() { - static TimePoint lastInfoTime = now(); + if (--callsCnt > 0) + return; - int elapsed = Time.elapsed(); - TimePoint tick = Limits.startTime + elapsed; + // When using nodes, ensure checking rate is not lower than 0.1% of nodes + callsCnt = Limits.nodes ? std::min(4096, int(Limits.nodes / 1024)) : 4096; - if (tick - lastInfoTime >= 1000) - { - lastInfoTime = tick; - dbg_print(); - } + static TimePoint lastInfoTime = now(); - // An engine may not stop pondering until told so by the GUI - if (Limits.ponder) - return; + int elapsed = Time.elapsed(); + TimePoint tick = Limits.startTime + elapsed; - if ( (Limits.use_time_management() && elapsed > Time.maximum() - 10) - || (Limits.movetime && elapsed >= Limits.movetime) - || (Limits.nodes && Threads.nodes_searched() >= Limits.nodes)) - Signals.stop = true; + if (tick - lastInfoTime >= 1000) + { + lastInfoTime = tick; + dbg_print(); } -} // namespace + // We should not stop pondering until told so by the GUI + if (Threads.ponder) + return; + + if ( (Limits.use_time_management() && elapsed > Time.maximum() - 10) + || (Limits.movetime && elapsed >= Limits.movetime) + || (Limits.nodes && Threads.nodes_searched() >= (uint64_t)Limits.nodes)) + Threads.stop = true; +} /// UCI::pv() formats PV information according to the UCI protocol. UCI requires @@ -1552,14 +1530,15 @@ string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) { std::stringstream ss; int elapsed = Time.elapsed() + 1; - const Search::RootMoveVector& rootMoves = pos.this_thread()->rootMoves; + const RootMoves& rootMoves = pos.this_thread()->rootMoves; size_t PVIdx = pos.this_thread()->PVIdx; size_t multiPV = std::min((size_t)Options["MultiPV"], rootMoves.size()); - uint64_t nodes_searched = Threads.nodes_searched(); + uint64_t nodesSearched = Threads.nodes_searched(); + uint64_t tbHits = Threads.tb_hits() + (TB::RootInTB ? rootMoves.size() : 0); for (size_t i = 0; i < multiPV; ++i) { - bool updated = (i <= PVIdx); + bool updated = (i <= PVIdx && rootMoves[i].score != -VALUE_INFINITE); if (depth == ONE_PLY && !updated) continue; @@ -1575,20 +1554,20 @@ string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) { ss << "info" << " depth " << d / ONE_PLY - << " seldepth " << pos.this_thread()->maxPly + << " seldepth " << rootMoves[i].selDepth << " multipv " << i + 1 << " score " << UCI::value(v); if (!tb && i == PVIdx) ss << (v >= beta ? " lowerbound" : v <= alpha ? " upperbound" : ""); - ss << " nodes " << nodes_searched - << " nps " << nodes_searched * 1000 / elapsed; + ss << " nodes " << nodesSearched + << " nps " << nodesSearched * 1000 / elapsed; if (elapsed > 1000) // Earlier makes little sense ss << " hashfull " << TT.hashfull(); - ss << " tbhits " << TB::Hits + ss << " tbhits " << tbHits << " time " << elapsed << " pv"; @@ -1600,55 +1579,81 @@ string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) { } -/// 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], *st = state; - bool ttHit; - - for (Move m : pv) - { - assert(MoveList(pos).contains(m)); - - TTEntry* tte = TT.probe(pos.key(), ttHit); - - if (!ttHit || tte->move() != m) // Don't overwrite correct entries - tte->save(pos.key(), VALUE_NONE, BOUND_NONE, DEPTH_NONE, - m, VALUE_NONE, TT.generation()); - - pos.do_move(m, *st++, pos.gives_check(m, CheckInfo(pos))); - } - - for (size_t i = pv.size(); i > 0; ) - pos.undo_move(pv[--i]); -} - - /// 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. -bool RootMove::extract_ponder_from_tt(Position& pos) -{ +bool RootMove::extract_ponder_from_tt(Position& pos) { + StateInfo st; bool ttHit; assert(pv.size() == 1); - pos.do_move(pv[0], st, pos.gives_check(pv[0], CheckInfo(pos))); + if (!pv[0]) + return false; + + pos.do_move(pv[0], st); TTEntry* tte = TT.probe(pos.key(), ttHit); - pos.undo_move(pv[0]); if (ttHit) { Move m = tte->move(); // Local copy to be SMP safe if (MoveList(pos).contains(m)) - return pv.push_back(m), true; + pv.push_back(m); + } + + pos.undo_move(pv[0]); + return pv.size() > 1; +} + + +void Tablebases::filter_root_moves(Position& pos, Search::RootMoves& rootMoves) { + + RootInTB = false; + UseRule50 = Options["Syzygy50MoveRule"]; + ProbeDepth = Options["SyzygyProbeDepth"] * ONE_PLY; + Cardinality = Options["SyzygyProbeLimit"]; + + // Skip TB probing when no TB found: !TBLargest -> !TB::Cardinality + if (Cardinality > MaxCardinality) + { + Cardinality = MaxCardinality; + ProbeDepth = DEPTH_ZERO; } - return false; + if (Cardinality < popcount(pos.pieces()) || pos.can_castle(ANY_CASTLING)) + return; + + // Don't filter any moves if the user requested analysis on multiple + if (Options["MultiPV"] != 1) + return; + + // If the current root position is in the tablebases, then RootMoves + // contains only moves that preserve the draw or the win. + RootInTB = root_probe(pos, rootMoves, TB::Score); + + if (RootInTB) + Cardinality = 0; // Do not probe tablebases during the search + + else // If DTZ tables are missing, use WDL tables as a fallback + { + // Filter out moves that do not preserve the draw or the win. + RootInTB = root_probe_wdl(pos, rootMoves, TB::Score); + + // Only probe during search if winning + if (RootInTB && TB::Score <= VALUE_DRAW) + Cardinality = 0; + } + + if (RootInTB && !UseRule50) + TB::Score = TB::Score > VALUE_DRAW ? VALUE_MATE - MAX_PLY - 1 + : TB::Score < VALUE_DRAW ? -VALUE_MATE + MAX_PLY + 1 + : VALUE_DRAW; + + // Since root_probe() and root_probe_wdl() dirty the root move scores, + // we reset them to -VALUE_INFINITE + for (RootMove& rm : rootMoves) + rm.score = -VALUE_INFINITE; }