X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=48cb4d6bdd9df3a36bacff4d04b3ce0dfd5dac34;hp=d1504e323e779671ddf2e1a88e1034132793769b;hb=189b6fc270f91f4111c1a8049c97455093f8be97;hpb=56774fff20e73ede9ea8548997c9b1798c5344d5 diff --git a/src/search.cpp b/src/search.cpp index d1504e32..a3d87818 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) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2008-2012 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 @@ -17,21 +17,19 @@ along with this program. If not, see . */ +#include #include #include #include -#include #include #include -#include -#include #include "book.h" #include "evaluate.h" #include "history.h" -#include "misc.h" #include "movegen.h" #include "movepick.h" +#include "notation.h" #include "search.h" #include "timeman.h" #include "thread.h" @@ -42,13 +40,14 @@ namespace Search { volatile SignalsType Signals; LimitsType Limits; - std::vector RootMoves; + std::vector RootMoves; Position RootPosition; + Time::point SearchTime; + StateStackPtr SetupStates; } -using std::cout; -using std::endl; using std::string; +using Eval::evaluate; using namespace Search; namespace { @@ -56,66 +55,18 @@ namespace { // Set to true to force running with one thread. Used for debugging const bool FakeSplit = false; + // This is the minimum interval in msec between two check_time() calls + const int TimerResolution = 5; + // Different node types, used as template parameter enum NodeType { Root, PV, NonPV, SplitPointRoot, SplitPointPV, SplitPointNonPV }; - // RootMove struct is used for moves at the root of the tree. For each root - // move, we store a score, a node count, and a PV (really a refutation - // in the case of moves which fail low). Score is normally set at - // -VALUE_INFINITE for all non-pv moves. - struct RootMove { - - // RootMove::operator<() is the comparison function used when - // sorting the moves. A move m1 is considered to be better - // than a move m2 if it has an higher score - bool operator<(const RootMove& m) const { return score < m.score; } - - void extract_pv_from_tt(Position& pos); - void insert_pv_in_tt(Position& pos); - - int64_t nodes; - Value score; - Value prevScore; - std::vector pv; - }; - - // RootMoveList struct is mainly a std::vector of RootMove objects - struct RootMoveList : public std::vector { - - void init(Position& pos, Move rootMoves[]); - RootMove* find(const Move& m, int startIndex = 0); - - int bestMoveChanges; - }; - - - /// Constants - // Lookup table to check if a Piece is a slider and its access function const bool Slidings[18] = { 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1 }; inline bool piece_is_slider(Piece p) { return Slidings[p]; } - // Maximum depth for razoring - const Depth RazorDepth = 4 * ONE_PLY; - // Dynamic razoring margin based on depth - inline Value razor_margin(Depth d) { return Value(0x200 + 0x10 * int(d)); } - - // Maximum depth for use of dynamic threat detection when null move fails low - const Depth ThreatDepth = 5 * ONE_PLY; - - // Minimum depth for use of internal iterative deepening - const Depth IIDDepth[] = { 8 * ONE_PLY, 5 * ONE_PLY }; - - // At Non-PV nodes we do an internal iterative deepening search - // when the static evaluation is bigger then beta - IIDMargin. - const Value IIDMargin = Value(0x100); - - // Minimum depth for use of singular extension - const Depth SingularExtensionDepth[] = { 8 * ONE_PLY, 6 * ONE_PLY }; - - // Futility margin for quiescence search - const Value FutilityMarginQS = Value(0x80); + inline Value razor_margin(Depth d) { return Value(512 + 16 * int(d)); } // Futility lookup tables (initialized at startup) and their access functions Value FutilityMargins[16][64]; // [depth][moveNumber] @@ -127,11 +78,6 @@ namespace { : 2 * VALUE_INFINITE; } - inline int futility_move_count(Depth d) { - - return d < 16 * ONE_PLY ? FutilityMoveCounts[d] : MAX_MOVES; - } - // Reduction lookup tables (initialized at startup) and their access function int8_t Reductions[2][64][64]; // [pv][depth][moveNumber] @@ -140,126 +86,33 @@ namespace { return (Depth) Reductions[PvNode][std::min(int(d) / ONE_PLY, 63)][std::min(mn, 63)]; } - // Easy move margin. An easy move candidate must be at least this much - // better than the second best move. - const Value EasyMoveMargin = Value(0x150); - - - /// Namespace variables - - // Root move list - RootMoveList Rml; - - // MultiPV mode - int MultiPV, UCIMultiPV, MultiPVIdx; - - // Time management variables + size_t MultiPV, UCIMultiPV, PVIdx; TimeManager TimeMgr; - - // Skill level adjustment + int BestMoveChanges; int SkillLevel; - bool SkillLevelEnabled; - - // History table + bool SkillLevelEnabled, Chess960; History H; - - /// Local functions - - Move id_loop(Position& pos, Move rootMoves[], Move* ponderMove); - template Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth); template Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth); - bool check_is_dangerous(Position &pos, Move move, Value futilityBase, Value beta, Value *bValue); + void id_loop(Position& pos); + bool check_is_dangerous(Position &pos, Move move, Value futilityBase, Value beta); bool connected_moves(const Position& pos, Move m1, Move m2); Value value_to_tt(Value v, int ply); Value value_from_tt(Value v, int ply); - bool can_return_tt(const TTEntry* tte, Depth depth, Value beta, int ply); bool connected_threat(const Position& pos, Move m, Move threat); - Value refine_eval(const TTEntry* tte, Value defaultEval, int ply); - void update_history(const Position& pos, Move move, Depth depth, Move movesSearched[], int moveCount); - void do_skill_level(Move* best, Move* ponder); - - int elapsed_time(bool reset = false); - string score_to_uci(Value v, Value alpha = -VALUE_INFINITE, Value beta = VALUE_INFINITE); - string speed_to_uci(int64_t nodes); - string pv_to_uci(const Move pv[], int pvNum, bool chess960); - string pretty_pv(Position& pos, int depth, Value score, int time, Move pv[]); - string depth_to_uci(Depth depth); - - // MovePickerExt template class extends MovePicker and allows to choose at compile - // time the proper moves source according to the type of node. In the default case - // we simply create and use a standard MovePicker object. - template struct MovePickerExt : public MovePicker { - - MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, Stack* ss, Value b) - : MovePicker(p, ttm, d, h, ss, b) {} - }; - - // In case of a SpNode we use split point's shared MovePicker object as moves source - template<> struct MovePickerExt : public MovePicker { - - MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, Stack* ss, Value b) - : MovePicker(p, ttm, d, h, ss, b), mp(ss->sp->mp) {} - - Move get_next_move() { return mp->get_next_move(); } - MovePicker* mp; - }; - - // Overload operator<<() to make it easier to print moves in a coordinate - // notation compatible with UCI protocol. - std::ostream& operator<<(std::ostream& os, Move m) { - - bool chess960 = (os.iword(0) != 0); // See set960() - return os << move_to_uci(m, chess960); - } - - // When formatting a move for std::cout we must know if we are in Chess960 - // or not. To keep using the handy operator<<() on the move the trick is to - // embed this flag in the stream itself. Function-like named enum set960 is - // used as a custom manipulator and the stream internal general-purpose array, - // accessed through ios_base::iword(), is used to pass the flag to the move's - // operator<<() that will read it to properly format castling moves. - enum set960 {}; - - std::ostream& operator<< (std::ostream& os, const set960& f) { - - os.iword(0) = int(f); - return os; - } - - // is_dangerous() checks whether a move belongs to some classes of known - // 'dangerous' moves so that we avoid to prune it. - FORCE_INLINE bool is_dangerous(const Position& pos, Move m, bool captureOrPromotion) { - - // Test for a pawn pushed to 7th or a passed pawn move - if (type_of(pos.piece_on(move_from(m))) == PAWN) - { - Color c = pos.side_to_move(); - if ( relative_rank(c, move_to(m)) == RANK_7 - || pos.pawn_is_passed(c, move_to(m))) - return true; - } - - // Test for a capture that triggers a pawn endgame - if ( captureOrPromotion - && type_of(pos.piece_on(move_to(m))) != PAWN - && ( pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) - - PieceValueMidgame[pos.piece_on(move_to(m))] == VALUE_ZERO) - && !is_special(m)) - return true; - - return false; - } + Value refine_eval(const TTEntry* tte, Value ttValue, Value defaultEval); + Move do_skill_level(); + string uci_pv(const Position& pos, int depth, Value alpha, Value beta); } // namespace -/// init_search() is called during startup to initialize various lookup tables +/// Search::init() is called during startup to initialize various lookup tables void Search::init() { @@ -286,158 +139,131 @@ void Search::init() { } -/// 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. - -int64_t Search::perft(Position& pos, Depth depth) { +/// 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. - StateInfo st; - int64_t sum = 0; +size_t Search::perft(Position& pos, Depth depth) { - // Generate all legal moves - MoveList ml(pos); + // At the last ply just return the number of legal moves (leaf nodes) + if (depth == ONE_PLY) + return MoveList(pos).size(); - // If we are at the last ply we don't need to do and undo - // the moves, just to count them. - if (depth <= ONE_PLY) - return ml.size(); - - // Loop through all legal moves + StateInfo st; + size_t cnt = 0; CheckInfo ci(pos); - for ( ; !ml.end(); ++ml) + + for (MoveList ml(pos); !ml.end(); ++ml) { pos.do_move(ml.move(), st, ci, pos.move_gives_check(ml.move(), ci)); - sum += perft(pos, depth - ONE_PLY); + cnt += perft(pos, depth - ONE_PLY); pos.undo_move(ml.move()); } - return sum; + + return cnt; } -/// 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 searches from -/// RootPosition and at the end prints the "bestmove" to output. +/// 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 +/// searches from RootPosition and at the end prints the "bestmove" to output. void Search::think() { - static Book book; // Defined static to initialize the PRNG only once + static PolyglotBook book; // Defined static to initialize the PRNG only once Position& pos = RootPosition; + Chess960 = pos.is_chess960(); + Eval::RootColor = pos.side_to_move(); + int scaledCF = Eval::ContemptFactor * MaterialTable::game_phase(pos) / PHASE_MIDGAME; + Eval::ValueDraw[ Eval::RootColor] = VALUE_DRAW - Value(scaledCF); + Eval::ValueDraw[~Eval::RootColor] = VALUE_DRAW + Value(scaledCF); + TimeMgr.init(Limits, pos.startpos_ply_counter(), pos.side_to_move()); + TT.new_search(); + H.clear(); + + if (RootMoves.empty()) + { + sync_cout << "info depth 0 score " + << score_to_uci(pos.in_check() ? -VALUE_MATE : VALUE_DRAW) << sync_endl; - // Reset elapsed search time - elapsed_time(true); - - // Set output stream mode: normal or chess960. Castling notation is different - cout << set960(pos.is_chess960()); + RootMoves.push_back(MOVE_NONE); + goto finalize; + } - // Look for a book move - if (Options["OwnBook"].value()) + if (Options["OwnBook"] && !Limits.infinite) { - if (Options["Book File"].value() != book.name()) - book.open(Options["Book File"].value()); + Move bookMove = book.probe(pos, Options["Book File"], Options["Best Book Move"]); - Move bookMove = book.probe(pos, Options["Best Book Move"].value()); - if (bookMove != MOVE_NONE) + if (bookMove && std::count(RootMoves.begin(), RootMoves.end(), bookMove)) { - if (!Signals.stop && (Limits.ponder || Limits.infinite)) - Threads.wait_for_stop_or_ponderhit(); - - cout << "bestmove " << bookMove << endl; - return; + std::swap(RootMoves[0], *std::find(RootMoves.begin(), RootMoves.end(), bookMove)); + goto finalize; } } - // Read UCI options: GUI could change UCI parameters during the game - read_evaluation_uci_options(pos.side_to_move()); - Threads.read_uci_options(); - - // Set a new TT size if changed - TT.set_size(Options["Hash"].value()); - - if (Options["Clear Hash"].value()) - { - Options["Clear Hash"].set_value("false"); - TT.clear(); - } - - UCIMultiPV = Options["MultiPV"].value(); - SkillLevel = Options["Skill Level"].value(); + UCIMultiPV = Options["MultiPV"]; + SkillLevel = Options["Skill Level"]; // Do we have to play with skill handicap? In this case enable MultiPV that // we will use behind the scenes to retrieve a set of possible moves. SkillLevelEnabled = (SkillLevel < 20); - MultiPV = (SkillLevelEnabled ? std::max(UCIMultiPV, 4) : UCIMultiPV); + MultiPV = (SkillLevelEnabled ? std::max(UCIMultiPV, (size_t)4) : UCIMultiPV); - // Write current search header to log file - if (Options["Use Search Log"].value()) + if (Options["Use Search Log"]) { - Log log(Options["Search Log Filename"].value()); + Log log(Options["Search Log Filename"]); log << "\nSearching: " << pos.to_fen() << "\ninfinite: " << Limits.infinite << " ponder: " << Limits.ponder - << " time: " << Limits.time - << " increment: " << Limits.increment - << " moves to go: " << Limits.movesToGo - << endl; + << " time: " << Limits.time[pos.side_to_move()] + << " increment: " << Limits.inc[pos.side_to_move()] + << " moves to go: " << Limits.movestogo + << std::endl; } - // Wake up needed threads and reset maxPly counter - for (int i = 0; i < Threads.size(); i++) - { - Threads[i].maxPly = 0; - Threads[i].wake_up(); - } + Threads.wake_up(); // Set best timer interval to avoid lagging under time pressure. Timer is // used to check for remaining available thinking time. - TimeMgr.init(Limits, pos.startpos_ply_counter()); - - if (TimeMgr.available_time()) - Threads.set_timer(std::min(100, std::max(TimeMgr.available_time() / 8, 20))); + if (Limits.use_time_management()) + Threads.set_timer(std::min(100, std::max(TimeMgr.available_time() / 16, TimerResolution))); + else if (Limits.nodes) + Threads.set_timer(2 * TimerResolution); else Threads.set_timer(100); - // We're ready to start thinking. Call the iterative deepening loop function - Move ponderMove = MOVE_NONE; - Move bestMove = id_loop(pos, &RootMoves[0], &ponderMove); - - // Stop timer, no need to check for available time any more - Threads.set_timer(0); + // We're ready to start searching. Call the iterative deepening loop function + id_loop(pos); - // This makes all the slave threads to go to sleep, if not already sleeping - Threads.set_size(1); + Threads.set_timer(0); // Stop timer + Threads.sleep(); - // Write current search final statistics to log file - if (Options["Use Search Log"].value()) + if (Options["Use Search Log"]) { - int e = elapsed_time(); + Time::point elapsed = Time::now() - SearchTime + 1; - Log log(Options["Search Log Filename"].value()); + Log log(Options["Search Log Filename"]); log << "Nodes: " << pos.nodes_searched() - << "\nNodes/second: " << (e > 0 ? pos.nodes_searched() * 1000 / e : 0) - << "\nBest move: " << move_to_san(pos, bestMove); + << "\nNodes/second: " << pos.nodes_searched() * 1000 / elapsed + << "\nBest move: " << move_to_san(pos, RootMoves[0].pv[0]); StateInfo st; - pos.do_move(bestMove, st); - log << "\nPonder move: " << move_to_san(pos, ponderMove) << endl; - pos.undo_move(bestMove); // Return from think() with unchanged position + pos.do_move(RootMoves[0].pv[0], st); + log << "\nPonder move: " << move_to_san(pos, RootMoves[0].pv[1]) << std::endl; + pos.undo_move(RootMoves[0].pv[0]); } - // When we reach max depth we arrive here even without a StopRequest, but if - // we are pondering or in infinite search, we shouldn't print the best move - // before we are told to do so. - if (!Signals.stop && (Limits.ponder || Limits.infinite)) - Threads.wait_for_stop_or_ponderhit(); +finalize: - // Could be MOVE_NONE when searching on a stalemate position - cout << "bestmove " << bestMove; - - // UCI protol is not clear on allowing sending an empty ponder move, instead - // it is clear that ponder move is optional. So skip it if empty. - if (ponderMove != MOVE_NONE) - cout << " ponder " << ponderMove; + // When we reach max depth we arrive here even without Signals.stop is raised, + // but if we are pondering or in infinite search, we shouldn't print the best + // move before we are told to do so. + if (!Signals.stop && (Limits.ponder || Limits.infinite)) + pos.this_thread()->wait_for_stop_or_ponderhit(); - cout << endl; + // Best move could be MOVE_NONE when searching on a stalemate position + sync_cout << "bestmove " << move_to_uci(RootMoves[0].pv[0], Chess960) + << " ponder " << move_to_uci(RootMoves[0].pv[1], Chess960) << sync_endl; } @@ -447,60 +273,39 @@ namespace { // with increasing depth until the allocated thinking time has been consumed, // user stops the search, or the maximum search depth is reached. - Move id_loop(Position& pos, Move rootMoves[], Move* ponderMove) { + void id_loop(Position& pos) { - Stack ss[PLY_MAX_PLUS_2]; - Value bestValues[PLY_MAX_PLUS_2]; - int bestMoveChanges[PLY_MAX_PLUS_2]; - int depth, aspirationDelta; - Value bestValue, alpha, beta; - Move bestMove, skillBest, skillPonder; + Stack ss[MAX_PLY_PLUS_2]; + int depth, prevBestMoveChanges; + Value bestValue, alpha, beta, delta; bool bestMoveNeverChanged = true; + Move skillBest = MOVE_NONE; - // Initialize stuff before a new search memset(ss, 0, 4 * sizeof(Stack)); - TT.new_search(); - H.clear(); - *ponderMove = bestMove = skillBest = skillPonder = MOVE_NONE; - depth = aspirationDelta = 0; - bestValue = alpha = -VALUE_INFINITE, beta = VALUE_INFINITE; + depth = BestMoveChanges = 0; + bestValue = delta = -VALUE_INFINITE; ss->currentMove = MOVE_NULL; // Hack to skip update gains - // Moves to search are verified and copied - Rml.init(pos, rootMoves); - - // Handle special case of searching on a mate/stalemate position - if (Rml.empty()) - { - cout << "info" << depth_to_uci(DEPTH_ZERO) - << score_to_uci(pos.in_check() ? -VALUE_MATE : VALUE_DRAW, alpha, beta) << endl; - - return MOVE_NONE; - } - // Iterative deepening loop until requested to stop or target depth reached - while (!Signals.stop && ++depth <= PLY_MAX && (!Limits.maxDepth || depth <= Limits.maxDepth)) + while (!Signals.stop && ++depth <= MAX_PLY && (!Limits.depth || depth <= Limits.depth)) { - // Save now last iteration's scores, before Rml moves are reordered - for (size_t i = 0; i < Rml.size(); i++) - Rml[i].prevScore = Rml[i].score; + // Save last iteration's scores before first PV line is searched and all + // the move scores but the (new) PV are set to -VALUE_INFINITE. + for (size_t i = 0; i < RootMoves.size(); i++) + RootMoves[i].prevScore = RootMoves[i].score; - Rml.bestMoveChanges = 0; + prevBestMoveChanges = BestMoveChanges; + BestMoveChanges = 0; // MultiPV loop. We perform a full root search for each PV line - for (MultiPVIdx = 0; MultiPVIdx < std::min(MultiPV, (int)Rml.size()); MultiPVIdx++) + for (PVIdx = 0; PVIdx < std::min(MultiPV, RootMoves.size()); PVIdx++) { - // Calculate dynamic aspiration window based on previous iterations - if (depth >= 5 && abs(Rml[MultiPVIdx].prevScore) < VALUE_KNOWN_WIN) + // Set aspiration window default width + if (depth >= 5 && abs(RootMoves[PVIdx].prevScore) < VALUE_KNOWN_WIN) { - int prevDelta1 = bestValues[depth - 1] - bestValues[depth - 2]; - int prevDelta2 = bestValues[depth - 2] - bestValues[depth - 3]; - - aspirationDelta = std::min(std::max(abs(prevDelta1) + abs(prevDelta2) / 2, 16), 24); - aspirationDelta = (aspirationDelta + 7) / 8 * 8; // Round to match grainSize - - alpha = std::max(Rml[MultiPVIdx].prevScore - aspirationDelta, -VALUE_INFINITE); - beta = std::min(Rml[MultiPVIdx].prevScore + aspirationDelta, VALUE_INFINITE); + delta = Value(16); + alpha = RootMoves[PVIdx].prevScore - delta; + beta = RootMoves[PVIdx].prevScore + delta; } else { @@ -510,7 +315,8 @@ namespace { // Start with a small aspiration window and, in case of fail high/low, // research with bigger window until not failing high/low anymore. - do { + while (true) + { // Search starts from ss+1 to allow referencing (ss-1). This is // needed by update gains and ss copy when splitting at Root. bestValue = search(pos, ss+1, alpha, beta, depth * ONE_PLY); @@ -521,114 +327,100 @@ namespace { // we want to keep the same order for all the moves but the new // PV that goes to the front. Note that in case of MultiPV search // the already searched PV lines are preserved. - sort(Rml.begin() + MultiPVIdx, Rml.end()); + sort(RootMoves.begin() + PVIdx, RootMoves.end()); // In case we have found an exact score and we are going to leave // the fail high/low loop then reorder the PV moves, otherwise // leave the last PV move in its position so to be searched again. // Of course this is needed only in MultiPV search. - if (MultiPVIdx && bestValue > alpha && bestValue < beta) - sort(Rml.begin(), Rml.begin() + MultiPVIdx); + if (PVIdx && bestValue > alpha && bestValue < beta) + sort(RootMoves.begin(), RootMoves.begin() + PVIdx); - // Write PV back to transposition table in case the relevant entries - // have been overwritten during the search. - for (int i = 0; i <= MultiPVIdx; i++) - Rml[i].insert_pv_in_tt(pos); + // Write PV back to 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(pos); - // If search has been stopped exit the aspiration window loop, - // note that sorting and writing PV back to TT is safe becuase - // Rml is still valid, although refers to the previous iteration. + // If search has been stopped exit the aspiration window loop. + // Sorting and writing PV back to TT is safe becuase RootMoves + // is still valid, although refers to previous iteration. if (Signals.stop) break; // Send full PV info to GUI if we are going to leave the loop or - // if we have a fail high/low and we are deep in the search. UCI - // protocol requires to send all the PV lines also if are still - // to be searched and so refer to the previous search's score. - if ((bestValue > alpha && bestValue < beta) || elapsed_time() > 2000) - for (int i = 0; i < std::min(UCIMultiPV, (int)Rml.size()); i++) - { - bool updated = (i <= MultiPVIdx); - - if (depth == 1 && !updated) - continue; - - Depth d = (updated ? depth : depth - 1) * ONE_PLY; - Value s = (updated ? Rml[i].score : Rml[i].prevScore); - - cout << "info" - << depth_to_uci(d) - << (i == MultiPVIdx ? score_to_uci(s, alpha, beta) : score_to_uci(s)) - << speed_to_uci(pos.nodes_searched()) - << pv_to_uci(&Rml[i].pv[0], i + 1, pos.is_chess960()) - << endl; - } + // if we have a fail high/low and we are deep in the search. + if ((bestValue > alpha && bestValue < beta) || Time::now() - SearchTime > 2000) + sync_cout << uci_pv(pos, depth, alpha, beta) << sync_endl; // In case of failing high/low increase aspiration window and // research, otherwise exit the fail high/low loop. if (bestValue >= beta) { - beta = std::min(beta + aspirationDelta, VALUE_INFINITE); - aspirationDelta += aspirationDelta / 2; + beta += delta; + delta += delta / 2; } else if (bestValue <= alpha) { Signals.failedLowAtRoot = true; Signals.stopOnPonderhit = false; - alpha = std::max(alpha - aspirationDelta, -VALUE_INFINITE); - aspirationDelta += aspirationDelta / 2; + alpha -= delta; + delta += delta / 2; } else break; - } while (abs(bestValue) < VALUE_KNOWN_WIN); - } + // Search with full window in case we have a win/mate score + if (abs(bestValue) >= VALUE_KNOWN_WIN) + { + alpha = -VALUE_INFINITE; + beta = VALUE_INFINITE; + } - // Collect info about search result - bestMove = Rml[0].pv[0]; - *ponderMove = Rml[0].pv[1]; - bestValues[depth] = bestValue; - bestMoveChanges[depth] = Rml.bestMoveChanges; + assert(alpha >= -VALUE_INFINITE && beta <= VALUE_INFINITE); + } + } - // Skills: Do we need to pick now the best and the ponder moves ? + // Skills: Do we need to pick now the best move ? if (SkillLevelEnabled && depth == 1 + SkillLevel) - do_skill_level(&skillBest, &skillPonder); + skillBest = do_skill_level(); - if (Options["Use Search Log"].value()) + if (!Signals.stop && Options["Use Search Log"]) { - Log log(Options["Search Log Filename"].value()); - log << pretty_pv(pos, depth, bestValue, elapsed_time(), &Rml[0].pv[0]) << endl; + Log log(Options["Search Log Filename"]); + log << pretty_pv(pos, depth, bestValue, Time::now() - SearchTime, &RootMoves[0].pv[0]) + << std::endl; } // Filter out startup noise when monitoring best move stability - if (depth > 2 && bestMoveChanges[depth]) + if (depth > 2 && BestMoveChanges) bestMoveNeverChanged = false; // Do we have time for the next iteration? Can we stop searching now? - if (!Signals.stop && !Signals.stopOnPonderhit && Limits.useTimeManagement()) + if (!Signals.stop && !Signals.stopOnPonderhit && Limits.use_time_management()) { - bool stop = false; // Local variable instead of the volatile Signals.stop + bool stop = false; // Local variable, not the volatile Signals.stop // Take in account some extra time if the best move has changed if (depth > 4 && depth < 50) - TimeMgr.pv_instability(bestMoveChanges[depth], bestMoveChanges[depth - 1]); + TimeMgr.pv_instability(BestMoveChanges, prevBestMoveChanges); - // Stop search if most of available time is already consumed. We probably don't - // have enough time to search the first move at the next iteration anyway. - if (elapsed_time() > (TimeMgr.available_time() * 62) / 100) + // Stop search if most of available time is already consumed. We + // probably don't have enough time to search the first move at the + // next iteration anyway. + if (Time::now() - SearchTime > (TimeMgr.available_time() * 62) / 100) stop = true; // Stop search early if one move seems to be much better than others - if ( depth >= 10 + if ( depth >= 12 && !stop - && ( bestMoveNeverChanged - || elapsed_time() > (TimeMgr.available_time() * 40) / 100)) + && ( (bestMoveNeverChanged && pos.captured_piece_type()) + || Time::now() - SearchTime > (TimeMgr.available_time() * 40) / 100)) { - Value rBeta = bestValue - EasyMoveMargin; - (ss+1)->excludedMove = bestMove; + Value rBeta = bestValue - 2 * PawnValueMg; + (ss+1)->excludedMove = RootMoves[0].pv[0]; (ss+1)->skipNullMove = true; - Value v = search(pos, ss+1, rBeta - 1, rBeta, (depth * ONE_PLY) / 2); + Value v = search(pos, ss+1, rBeta - 1, rBeta, (depth - 3) * ONE_PLY); (ss+1)->skipNullMove = false; (ss+1)->excludedMove = MOVE_NONE; @@ -648,17 +440,14 @@ namespace { } } - // When using skills overwrite best and ponder moves with the sub-optimal ones + // When using skills swap best PV line with the sub-optimal one if (SkillLevelEnabled) { if (skillBest == MOVE_NONE) // Still unassigned ? - do_skill_level(&skillBest, &skillPonder); + skillBest = do_skill_level(); - bestMove = skillBest; - *ponderMove = skillPonder; + std::swap(RootMoves[0], *std::find(RootMoves.begin(), RootMoves.end(), skillBest)); } - - return bestMove; } @@ -676,63 +465,67 @@ namespace { const bool SpNode = (NT == SplitPointPV || NT == SplitPointNonPV || NT == SplitPointRoot); const bool RootNode = (NT == Root || NT == SplitPointRoot); - assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE); - assert(beta > alpha && beta <= VALUE_INFINITE); - assert(PvNode || alpha == beta - 1); - assert(pos.thread() >= 0 && pos.thread() < Threads.size()); + assert(alpha >= -VALUE_INFINITE && alpha < beta && beta <= VALUE_INFINITE); + assert(PvNode || (alpha == beta - 1)); + assert(depth > DEPTH_ZERO); - Move movesSearched[MAX_MOVES]; - int64_t nodes; + Move movesSearched[64]; StateInfo st; const TTEntry *tte; + SplitPoint* sp; Key posKey; - Move ttMove, move, excludedMove, threatMove; + Move ttMove, move, excludedMove, bestMove, threatMove; Depth ext, newDepth; - ValueType vt; - Value bestValue, value, oldAlpha; - Value refinedValue, nullValue, futilityBase, futilityValue; - bool isPvMove, inCheck, singularExtensionNode, givesCheck; + Value bestValue, value, ttValue; + Value refinedValue, nullValue, futilityValue; + bool inCheck, givesCheck, pvMove, singularExtensionNode; bool captureOrPromotion, dangerous, doFullDepthSearch; - int moveCount = 0, playedMoveCount = 0; - Thread& thread = Threads[pos.thread()]; - SplitPoint* sp = NULL; + int moveCount, playedMoveCount; - refinedValue = bestValue = value = -VALUE_INFINITE; - oldAlpha = alpha; + // Step 1. Initialize node + Thread* thisThread = pos.this_thread(); + moveCount = playedMoveCount = 0; inCheck = pos.in_check(); - ss->ply = (ss-1)->ply + 1; - - // Used to send selDepth info to GUI - if (PvNode && thread.maxPly < ss->ply) - thread.maxPly = ss->ply; - // Step 1. Initialize node - if (!SpNode) - { - ss->currentMove = ss->bestMove = threatMove = (ss+1)->excludedMove = MOVE_NONE; - (ss+1)->skipNullMove = false; (ss+1)->reduction = DEPTH_ZERO; - (ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE; - } - else + if (SpNode) { sp = ss->sp; + bestMove = sp->bestMove; + threatMove = sp->threatMove; + bestValue = sp->bestValue; tte = NULL; ttMove = excludedMove = MOVE_NONE; - threatMove = sp->threatMove; + ttValue = VALUE_NONE; + + assert(sp->bestValue > -VALUE_INFINITE && sp->moveCount > 0); + goto split_point_start; } - // Step 2. Check for aborted search and immediate draw - if (( Signals.stop - || pos.is_draw() - || ss->ply > PLY_MAX) && !RootNode) - return VALUE_DRAW; + bestValue = -VALUE_INFINITE; + ss->currentMove = threatMove = (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) + thisThread->maxPly = ss->ply; - // Step 3. Mate distance pruning if (!RootNode) { - alpha = std::max(value_mated_in(ss->ply), alpha); - beta = std::min(value_mate_in(ss->ply+1), beta); + // Step 2. Check for aborted search and immediate draw + if (Signals.stop || pos.is_draw() || ss->ply > MAX_PLY) + return Eval::ValueDraw[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 + // a shorter mate was found upward in the tree then there is no need to search + // further, we will never beat current alpha. Same logic but with reversed signs + // applies also in the opposite condition of being mated instead of giving mate, + // in this case return a fail-high score. + alpha = std::max(mated_in(ss->ply), alpha); + beta = std::min(mate_in(ss->ply+1), beta); if (alpha >= beta) return alpha; } @@ -741,69 +534,72 @@ namespace { // 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.get_exclusion_key() : pos.get_key(); + posKey = excludedMove ? pos.exclusion_key() : pos.key(); tte = TT.probe(posKey); - ttMove = RootNode ? Rml[MultiPVIdx].pv[0] : tte ? tte->move() : MOVE_NONE; + 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, while at non-PV nodes we check for // a fail high/low. Biggest advantage at 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 && (PvNode ? tte->depth() >= depth && tte->type() == VALUE_TYPE_EXACT - : can_return_tt(tte, depth, beta, ss->ply))) + if ( !RootNode + && tte && tte->depth() >= depth + && ( PvNode ? tte->type() == BOUND_EXACT + : ttValue >= beta ? (tte->type() & BOUND_LOWER) + : (tte->type() & BOUND_UPPER))) { TT.refresh(tte); - ss->bestMove = move = ttMove; // Can be MOVE_NONE - value = value_from_tt(tte->value(), ss->ply); + ss->currentMove = ttMove; // Can be MOVE_NONE - if ( value >= beta - && move - && !pos.is_capture_or_promotion(move) - && move != ss->killers[0]) + if ( ttValue >= beta + && ttMove + && !pos.is_capture_or_promotion(ttMove) + && ttMove != ss->killers[0]) { ss->killers[1] = ss->killers[0]; - ss->killers[0] = move; + ss->killers[0] = ttMove; } - return value; + return ttValue; } // Step 5. Evaluate the position statically and update parent's gain statistics if (inCheck) - ss->eval = ss->evalMargin = VALUE_NONE; + ss->eval = ss->evalMargin = refinedValue = VALUE_NONE; else if (tte) { assert(tte->static_value() != VALUE_NONE); ss->eval = tte->static_value(); ss->evalMargin = tte->static_value_margin(); - refinedValue = refine_eval(tte, ss->eval, ss->ply); + refinedValue = refine_eval(tte, ttValue, ss->eval); } else { refinedValue = ss->eval = evaluate(pos, ss->evalMargin); - TT.store(posKey, VALUE_NONE, VALUE_TYPE_NONE, DEPTH_NONE, MOVE_NONE, ss->eval, ss->evalMargin); + TT.store(posKey, VALUE_NONE, BOUND_NONE, DEPTH_NONE, MOVE_NONE, ss->eval, ss->evalMargin); } // Update gain for the parent non-capture move given the static position // evaluation before and after the move. - if ( (move = (ss-1)->currentMove) != MOVE_NULL - && (ss-1)->eval != VALUE_NONE - && ss->eval != VALUE_NONE - && pos.captured_piece_type() == PIECE_TYPE_NONE - && !is_special(move)) + if ( (move = (ss-1)->currentMove) != MOVE_NULL + && (ss-1)->eval != VALUE_NONE + && ss->eval != VALUE_NONE + && !pos.captured_piece_type() + && type_of(move) == NORMAL) { - Square to = move_to(move); + Square to = to_sq(move); H.update_gain(pos.piece_on(to), to, -(ss-1)->eval - ss->eval); } // Step 6. Razoring (is omitted in PV nodes) if ( !PvNode - && depth < RazorDepth + && depth < 4 * ONE_PLY && !inCheck && refinedValue + razor_margin(depth) < beta && ttMove == MOVE_NONE - && abs(beta) < VALUE_MATE_IN_PLY_MAX - && !pos.has_pawn_on_7th(pos.side_to_move())) + && abs(beta) < VALUE_MATE_IN_MAX_PLY + && !pos.pawn_on_7th(pos.side_to_move())) { Value rbeta = beta - razor_margin(depth); Value v = qsearch(pos, ss, rbeta-1, rbeta, DEPTH_ZERO); @@ -818,12 +614,12 @@ namespace { // the score by more than futility_margin(depth) if we do a null move. if ( !PvNode && !ss->skipNullMove - && depth < RazorDepth + && depth < 4 * ONE_PLY && !inCheck - && refinedValue - futility_margin(depth, 0) >= beta - && abs(beta) < VALUE_MATE_IN_PLY_MAX + && refinedValue - FutilityMargins[depth][0] >= beta + && abs(beta) < VALUE_MATE_IN_MAX_PLY && pos.non_pawn_material(pos.side_to_move())) - return refinedValue - futility_margin(depth, 0); + return refinedValue - FutilityMargins[depth][0]; // Step 8. Null move search with verification search (is omitted in PV nodes) if ( !PvNode @@ -831,29 +627,29 @@ namespace { && depth > ONE_PLY && !inCheck && refinedValue >= beta - && abs(beta) < VALUE_MATE_IN_PLY_MAX + && abs(beta) < VALUE_MATE_IN_MAX_PLY && pos.non_pawn_material(pos.side_to_move())) { ss->currentMove = MOVE_NULL; // Null move dynamic reduction based on depth - int R = 3 + (depth >= 5 * ONE_PLY ? depth / 8 : 0); + Depth R = 3 * ONE_PLY + depth / 4; // Null move dynamic reduction based on value - if (refinedValue - PawnValueMidgame > beta) - R++; + if (refinedValue - PawnValueMg > beta) + R += ONE_PLY; pos.do_null_move(st); (ss+1)->skipNullMove = true; - nullValue = depth-R*ONE_PLY < ONE_PLY ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) - : - search(pos, ss+1, -beta, -alpha, depth-R*ONE_PLY); + nullValue = depth-R < ONE_PLY ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) + : - search(pos, ss+1, -beta, -alpha, depth-R); (ss+1)->skipNullMove = false; pos.do_null_move(st); if (nullValue >= beta) { // Do not return unproven mate scores - if (nullValue >= VALUE_MATE_IN_PLY_MAX) + if (nullValue >= VALUE_MATE_IN_MAX_PLY) nullValue = beta; if (depth < 6 * ONE_PLY) @@ -861,7 +657,7 @@ namespace { // Do verification search at high depths ss->skipNullMove = true; - Value v = search(pos, ss, alpha, beta, depth-R*ONE_PLY); + Value v = search(pos, ss, alpha, beta, depth-R); ss->skipNullMove = false; if (v >= beta) @@ -875,9 +671,9 @@ namespace { // move which was reduced. If a connection is found, return a fail // low score (which will cause the reduced move to fail high in the // parent node, which will trigger a re-search with full depth). - threatMove = (ss+1)->bestMove; + threatMove = (ss+1)->currentMove; - if ( depth < ThreatDepth + if ( depth < 5 * ONE_PLY && (ss-1)->reduction && threatMove != MOVE_NONE && connected_moves(pos, (ss-1)->currentMove, threatMove)) @@ -890,23 +686,26 @@ namespace { // and a reduced search returns a value much above beta, we can (almost) safely // prune the previous move. if ( !PvNode - && depth >= RazorDepth + ONE_PLY + && depth >= 5 * ONE_PLY && !inCheck && !ss->skipNullMove && excludedMove == MOVE_NONE - && abs(beta) < VALUE_MATE_IN_PLY_MAX) + && abs(beta) < VALUE_MATE_IN_MAX_PLY) { Value rbeta = beta + 200; Depth rdepth = depth - ONE_PLY - 3 * ONE_PLY; assert(rdepth >= ONE_PLY); + assert((ss-1)->currentMove != MOVE_NONE); + assert((ss-1)->currentMove != MOVE_NULL); MovePicker mp(pos, ttMove, H, pos.captured_piece_type()); CheckInfo ci(pos); - while ((move = mp.get_next_move()) != MOVE_NONE) + while ((move = mp.next_move()) != MOVE_NONE) if (pos.pl_move_is_legal(move, ci.pinned)) { + ss->currentMove = move; pos.do_move(move, st, ci, pos.move_gives_check(move, ci)); value = -search(pos, ss+1, -rbeta, -rbeta+1, rdepth); pos.undo_move(move); @@ -916,9 +715,9 @@ namespace { } // Step 10. Internal iterative deepening - if ( depth >= IIDDepth[PvNode] + if ( depth >= (PvNode ? 5 * ONE_PLY : 8 * ONE_PLY) && ttMove == MOVE_NONE - && (PvNode || (!inCheck && ss->eval + IIDMargin >= beta))) + && (PvNode || (!inCheck && ss->eval + Value(256) >= beta))) { Depth d = (PvNode ? depth - 2 * ONE_PLY : depth / 2); @@ -932,29 +731,20 @@ namespace { split_point_start: // At split points actual search starts from here - // Initialize a MovePicker object for the current position - MovePickerExt mp(pos, ttMove, depth, H, ss, PvNode ? -VALUE_INFINITE : beta); + MovePicker mp(pos, ttMove, depth, H, ss, PvNode ? -VALUE_INFINITE : beta); CheckInfo ci(pos); - ss->bestMove = MOVE_NONE; - futilityBase = ss->eval + ss->evalMargin; + value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc singularExtensionNode = !RootNode && !SpNode - && depth >= SingularExtensionDepth[PvNode] - && ttMove != MOVE_NONE - && !excludedMove // Do not allow recursive singular extension search - && (tte->type() & VALUE_TYPE_LOWER) - && tte->depth() >= depth - 3 * ONE_PLY; - if (SpNode) - { - lock_grab(&(sp->lock)); - bestValue = sp->bestValue; - } + && depth >= (PvNode ? 6 * ONE_PLY : 8 * ONE_PLY) + && ttMove != MOVE_NONE + && !excludedMove // Recursive singular search is not allowed + && (tte->type() & BOUND_LOWER) + && tte->depth() >= depth - 3 * ONE_PLY; // Step 11. Loop through moves // Loop through all pseudo-legal moves until no moves remain or a beta cutoff occurs - while ( bestValue < beta - && (move = mp.get_next_move()) != MOVE_NONE - && !thread.cutoff_occurred()) + while ((move = mp.next_move()) != MOVE_NONE) { assert(is_ok(move)); @@ -964,73 +754,70 @@ split_point_start: // At split points actual search starts from here // At root obey the "searchmoves" option and skip moves not listed in Root // Move List, as a consequence any illegal move is also skipped. In MultiPV // mode we also skip PV moves which have been already searched. - if (RootNode && !Rml.find(move, MultiPVIdx)) - continue; - - // At PV and SpNode nodes we want all moves to be legal since the beginning - if ((PvNode || SpNode) && !pos.pl_move_is_legal(move, ci.pinned)) + if (RootNode && !std::count(RootMoves.begin() + PVIdx, RootMoves.end(), move)) continue; if (SpNode) { + // Shared counter cannot be decremented later if move turns out to be illegal + if (!pos.pl_move_is_legal(move, ci.pinned)) + continue; + moveCount = ++sp->moveCount; - lock_release(&(sp->lock)); + sp->mutex.unlock(); } else moveCount++; if (RootNode) { - // This is used by time management Signals.firstRootMove = (moveCount == 1); - // Save the current node count before the move is searched - nodes = pos.nodes_searched(); - - // For long searches send current move info to GUI - if (pos.thread() == 0 && elapsed_time() > 2000) - cout << "info" << depth_to_uci(depth) - << " currmove " << move - << " currmovenumber " << moveCount + MultiPVIdx << endl; + if (thisThread == Threads.main_thread() && Time::now() - SearchTime > 2000) + sync_cout << "info depth " << depth / ONE_PLY + << " currmove " << move_to_uci(move, Chess960) + << " currmovenumber " << moveCount + PVIdx << sync_endl; } - isPvMove = (PvNode && moveCount <= 1); + ext = DEPTH_ZERO; captureOrPromotion = pos.is_capture_or_promotion(move); givesCheck = pos.move_gives_check(move, ci); - dangerous = givesCheck || is_dangerous(pos, move, captureOrPromotion); - ext = DEPTH_ZERO; + dangerous = givesCheck + || pos.is_passed_pawn_push(move) + || type_of(move) == CASTLE + || ( captureOrPromotion // Entering a pawn endgame? + && type_of(pos.piece_on(to_sq(move))) != PAWN + && type_of(move) == NORMAL + && ( pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) + - PieceValue[Mg][pos.piece_on(to_sq(move))] == VALUE_ZERO)); // Step 12. Extend checks and, in PV nodes, also dangerous moves if (PvNode && dangerous) ext = ONE_PLY; else if (givesCheck && pos.see_sign(move) >= 0) - ext = PvNode ? ONE_PLY : ONE_PLY / 2; + ext = ONE_PLY / 2; // 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, if result is lower than ttValue minus // a margin then we extend ttMove. - if ( singularExtensionNode + if ( singularExtensionNode && !ext - && move == ttMove - && pos.pl_move_is_legal(move, ci.pinned)) + && move == ttMove + && pos.pl_move_is_legal(move, ci.pinned) + && abs(ttValue) < VALUE_KNOWN_WIN) { - Value ttValue = value_from_tt(tte->value(), ss->ply); - - if (abs(ttValue) < VALUE_KNOWN_WIN) - { - Value rBeta = ttValue - int(depth); - ss->excludedMove = move; - ss->skipNullMove = true; - value = search(pos, ss, rBeta - 1, rBeta, depth / 2); - ss->skipNullMove = false; - ss->excludedMove = MOVE_NONE; - ss->bestMove = MOVE_NONE; - if (value < rBeta) - ext = ONE_PLY; - } + Value rBeta = ttValue - int(depth); + ss->excludedMove = move; + ss->skipNullMove = true; + value = search(pos, ss, rBeta - 1, rBeta, depth / 2); + ss->skipNullMove = false; + ss->excludedMove = MOVE_NONE; + + if (value < rBeta) + ext = rBeta >= beta ? ONE_PLY + ONE_PLY / 2 : ONE_PLY; } // Update current move (this must be done after singular extension search) @@ -1042,15 +829,16 @@ split_point_start: // At split points actual search starts from here && !inCheck && !dangerous && move != ttMove - && !is_castle(move)) + && (bestValue > VALUE_MATED_IN_MAX_PLY || ( bestValue == -VALUE_INFINITE + && alpha > VALUE_MATED_IN_MAX_PLY))) { // Move count based pruning - if ( moveCount >= futility_move_count(depth) - && (!threatMove || !connected_threat(pos, move, threatMove)) - && bestValue > VALUE_MATED_IN_PLY_MAX) // FIXME bestValue is racy + if ( depth < 16 * ONE_PLY + && moveCount >= FutilityMoveCounts[depth] + && (!threatMove || !connected_threat(pos, move, threatMove))) { if (SpNode) - lock_grab(&(sp->lock)); + sp->mutex.lock(); continue; } @@ -1059,30 +847,23 @@ split_point_start: // At split points actual search starts from here // We illogically ignore reduction condition depth >= 3*ONE_PLY for predicted depth, // but fixing this made program slightly weaker. Depth predictedDepth = newDepth - reduction(depth, moveCount); - futilityValue = futilityBase + futility_margin(predictedDepth, moveCount) - + H.gain(pos.piece_on(move_from(move)), move_to(move)); + futilityValue = ss->eval + ss->evalMargin + futility_margin(predictedDepth, moveCount) + + H.gain(pos.piece_moved(move), to_sq(move)); if (futilityValue < beta) { if (SpNode) - { - lock_grab(&(sp->lock)); - if (futilityValue > sp->bestValue) - sp->bestValue = bestValue = futilityValue; - } - else if (futilityValue > bestValue) - bestValue = futilityValue; + sp->mutex.lock(); continue; } // Prune moves with negative SEE at low depths if ( predictedDepth < 2 * ONE_PLY - && bestValue > VALUE_MATED_IN_PLY_MAX && pos.see_sign(move) < 0) { if (SpNode) - lock_grab(&(sp->lock)); + sp->mutex.lock(); continue; } @@ -1095,8 +876,9 @@ split_point_start: // At split points actual search starts from here continue; } + pvMove = PvNode ? moveCount == 1 : false; ss->currentMove = move; - if (!SpNode && !captureOrPromotion) + if (!SpNode && !captureOrPromotion && playedMoveCount < 64) movesSearched[playedMoveCount++] = move; // Step 14. Make the move @@ -1104,26 +886,24 @@ split_point_start: // At split points actual search starts from here // Step 15. Reduced depth search (LMR). If the move fails high will be // re-searched at full depth. - if ( depth > 3 * ONE_PLY - && !isPvMove + if ( depth > 3 * ONE_PLY + && !pvMove && !captureOrPromotion && !dangerous - && !is_castle(move) && ss->killers[0] != move && ss->killers[1] != move) { ss->reduction = reduction(depth, moveCount); - Depth d = newDepth - ss->reduction; + Depth d = std::max(newDepth - ss->reduction, ONE_PLY); alpha = SpNode ? sp->alpha : alpha; - value = d < ONE_PLY ? -qsearch(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO) - : - search(pos, ss+1, -(alpha+1), -alpha, d); + value = -search(pos, ss+1, -(alpha+1), -alpha, d); doFullDepthSearch = (value > alpha && ss->reduction != DEPTH_ZERO); ss->reduction = DEPTH_ZERO; } else - doFullDepthSearch = !isPvMove; + doFullDepthSearch = !pvMove; // Step 16. Full depth search, when LMR is skipped or fails high if (doFullDepthSearch) @@ -1136,7 +916,7 @@ split_point_start: // At split points actual search starts from here // Only for PV nodes 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 to fail low with value <= alpha and to try another move. - if (PvNode && (isPvMove || (value > alpha && (RootNode || value < beta)))) + if (PvNode && (pvMove || (value > alpha && (RootNode || value < beta)))) value = newDepth < ONE_PLY ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) : - search(pos, ss+1, -beta, -alpha, newDepth); @@ -1148,118 +928,133 @@ split_point_start: // At split points actual search starts from here // Step 18. Check for new best move if (SpNode) { - lock_grab(&(sp->lock)); + sp->mutex.lock(); bestValue = sp->bestValue; alpha = sp->alpha; } - // Finished searching the move. If StopRequest is true, the search + // Finished searching the move. If Signals.stop is true, the search // was aborted because the user interrupted the search or because we // ran out of time. In this case, the return value of the search cannot // be trusted, and we don't update the best move and/or PV. - if (RootNode && !Signals.stop) + if (Signals.stop || thisThread->cutoff_occurred()) + return bestValue; + + if (RootNode) { - // Remember searched nodes counts for this move - RootMove* rm = Rml.find(move); - rm->nodes += pos.nodes_searched() - nodes; + RootMove& rm = *std::find(RootMoves.begin(), RootMoves.end(), move); // PV move or new best move ? - if (isPvMove || value > alpha) + if (pvMove || value > alpha) { - // Update PV - rm->score = value; - rm->extract_pv_from_tt(pos); + rm.score = value; + rm.extract_pv_from_tt(pos); // 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 (!isPvMove && MultiPV == 1) - Rml.bestMoveChanges++; + if (!pvMove && MultiPV == 1) + BestMoveChanges++; } else // All other moves but the PV are set to the lowest value, this // is not a problem when sorting becuase sort is stable and move // position in the list is preserved, just the PV is pushed up. - rm->score = -VALUE_INFINITE; - - } // RootNode + rm.score = -VALUE_INFINITE; + } if (value > bestValue) { bestValue = value; - ss->bestMove = move; - - if ( PvNode - && value > alpha - && value < beta) // We want always alpha < beta - alpha = value; + if (SpNode) sp->bestValue = value; - if (SpNode && !thread.cutoff_occurred()) + if (value > alpha) { - sp->bestValue = value; - sp->ss->bestMove = move; - sp->alpha = alpha; - sp->is_betaCutoff = (value >= beta); + bestMove = move; + if (SpNode) sp->bestMove = move; + + if (PvNode && value < beta) + { + alpha = value; // Update alpha here! Always alpha < beta + if (SpNode) sp->alpha = value; + } + else // Fail high + { + if (SpNode) sp->cutoff = true; + break; + } } } - // Step 19. Check for split + // Step 19. Check for splitting the search if ( !SpNode - && depth >= Threads.min_split_depth() - && bestValue < beta - && Threads.available_slave_exists(pos.thread()) - && !Signals.stop - && !thread.cutoff_occurred()) - bestValue = Threads.split(pos, ss, alpha, beta, bestValue, depth, - threatMove, moveCount, &mp, NT); + && depth >= Threads.min_split_depth() + && bestValue < beta + && Threads.available_slave_exists(thisThread)) + { + bestValue = Threads.split(pos, ss, alpha, beta, bestValue, &bestMove, + depth, threatMove, moveCount, mp, NT); + break; + } } + if (SpNode) + return bestValue; + // Step 20. Check for mate and stalemate // All legal moves have been searched and if there are no legal moves, it // must be mate or stalemate. Note that we can have a false positive in - // case of StopRequest or thread.cutoff_occurred() are set, but this is + // case of Signals.stop or thread.cutoff_occurred() are set, but this is // harmless because return value is discarded anyhow in the parent nodes. // If we are in a singular extension search then return a fail low score. - if (!SpNode && !moveCount) - return excludedMove ? oldAlpha : inCheck ? value_mated_in(ss->ply) : VALUE_DRAW; + // A split node has at least one move, the one tried before to be splitted. + if (!moveCount) + return excludedMove ? alpha : inCheck ? mated_in(ss->ply) : VALUE_DRAW; - // Step 21. Update tables - // If the search is not aborted, update the transposition table, - // history counters, and killer moves. - if (!SpNode && !Signals.stop && !thread.cutoff_occurred()) + // If we have pruned all the moves without searching return a fail-low score + if (bestValue == -VALUE_INFINITE) { - move = bestValue <= oldAlpha ? MOVE_NONE : ss->bestMove; - vt = bestValue <= oldAlpha ? VALUE_TYPE_UPPER - : bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT; + assert(!playedMoveCount); - TT.store(posKey, value_to_tt(bestValue, ss->ply), vt, depth, move, ss->eval, ss->evalMargin); + bestValue = alpha; + } - // Update killers and history only for non capture moves that fails high - if ( bestValue >= beta - && !pos.is_capture_or_promotion(move)) + if (bestValue >= beta) // Failed high + { + TT.store(posKey, value_to_tt(bestValue, ss->ply), BOUND_LOWER, depth, + bestMove, ss->eval, ss->evalMargin); + + if (!pos.is_capture_or_promotion(bestMove) && !inCheck) { - if (move != ss->killers[0]) + if (bestMove != ss->killers[0]) { ss->killers[1] = ss->killers[0]; - ss->killers[0] = move; + ss->killers[0] = bestMove; } - update_history(pos, move, depth, movesSearched, playedMoveCount); - } - } - if (SpNode) - { - // Here we have the lock still grabbed - sp->is_slave[pos.thread()] = false; - sp->nodes += pos.nodes_searched(); - lock_release(&(sp->lock)); + // Increase history value of the cut-off move + Value bonus = Value(int(depth) * int(depth)); + H.add(pos.piece_moved(bestMove), to_sq(bestMove), bonus); + + // Decrease history of all the other played non-capture moves + for (int i = 0; i < playedMoveCount - 1; i++) + { + Move m = movesSearched[i]; + H.add(pos.piece_moved(m), to_sq(m), -bonus); + } + } } + else // Failed low or PV search + TT.store(posKey, value_to_tt(bestValue, ss->ply), + PvNode && bestMove != MOVE_NONE ? BOUND_EXACT : BOUND_UPPER, + depth, bestMove, ss->eval, ss->evalMargin); assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); return bestValue; } + // 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). @@ -1270,50 +1065,52 @@ split_point_start: // At split points actual search starts from here const bool PvNode = (NT == PV); assert(NT == PV || NT == NonPV); - assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE); - assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE); - assert(PvNode || alpha == beta - 1); - assert(depth <= 0); - assert(pos.thread() >= 0 && pos.thread() < Threads.size()); + assert(alpha >= -VALUE_INFINITE && alpha < beta && beta <= VALUE_INFINITE); + assert(PvNode || (alpha == beta - 1)); + assert(depth <= DEPTH_ZERO); StateInfo st; - Move ttMove, move; - Value bestValue, value, evalMargin, futilityValue, futilityBase; - bool inCheck, enoughMaterial, givesCheck, evasionPrunable; const TTEntry* tte; + Key posKey; + Move ttMove, move, bestMove; + Value bestValue, value, ttValue, futilityValue, futilityBase; + bool inCheck, givesCheck, enoughMaterial, evasionPrunable; Depth ttDepth; - ValueType vt; - Value oldAlpha = alpha; - ss->bestMove = ss->currentMove = MOVE_NONE; + inCheck = pos.in_check(); + ss->currentMove = bestMove = MOVE_NONE; ss->ply = (ss-1)->ply + 1; // Check for an instant draw or maximum ply reached - if (pos.is_draw() || ss->ply > PLY_MAX) - return VALUE_DRAW; + if (pos.is_draw() || ss->ply > MAX_PLY) + return Eval::ValueDraw[pos.side_to_move()]; + + // Transposition table lookup. At PV nodes, we don't use the TT for + // pruning, but only for move ordering. + posKey = pos.key(); + tte = TT.probe(posKey); + ttMove = tte ? tte->move() : MOVE_NONE; + ttValue = tte ? value_from_tt(tte->value(),ss->ply) : VALUE_NONE; // 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 // only two types of depth in TT: DEPTH_QS_CHECKS or DEPTH_QS_NO_CHECKS. - inCheck = pos.in_check(); - ttDepth = (inCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS : DEPTH_QS_NO_CHECKS); - - // Transposition table lookup. At PV nodes, we don't use the TT for - // pruning, but only for move ordering. - tte = TT.probe(pos.get_key()); - ttMove = (tte ? tte->move() : MOVE_NONE); + ttDepth = inCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS : DEPTH_QS_NO_CHECKS; - if (!PvNode && tte && can_return_tt(tte, ttDepth, beta, ss->ply)) + if ( tte && tte->depth() >= ttDepth + && ( PvNode ? tte->type() == BOUND_EXACT + : ttValue >= beta ? (tte->type() & BOUND_LOWER) + : (tte->type() & BOUND_UPPER))) { - ss->bestMove = ttMove; // Can be MOVE_NONE - return value_from_tt(tte->value(), ss->ply); + ss->currentMove = ttMove; // Can be MOVE_NONE + return ttValue; } // Evaluate the position statically if (inCheck) { + ss->eval = ss->evalMargin = VALUE_NONE; bestValue = futilityBase = -VALUE_INFINITE; - ss->eval = evalMargin = VALUE_NONE; enoughMaterial = false; } else @@ -1322,17 +1119,17 @@ split_point_start: // At split points actual search starts from here { assert(tte->static_value() != VALUE_NONE); - evalMargin = tte->static_value_margin(); ss->eval = bestValue = tte->static_value(); + ss->evalMargin = tte->static_value_margin(); } else - ss->eval = bestValue = evaluate(pos, evalMargin); + ss->eval = bestValue = evaluate(pos, ss->evalMargin); // Stand pat. Return immediately if static value is at least beta if (bestValue >= beta) { if (!tte) - TT.store(pos.get_key(), value_to_tt(bestValue, ss->ply), VALUE_TYPE_LOWER, DEPTH_NONE, MOVE_NONE, ss->eval, evalMargin); + TT.store(pos.key(), value_to_tt(bestValue, ss->ply), BOUND_LOWER, DEPTH_NONE, MOVE_NONE, ss->eval, ss->evalMargin); return bestValue; } @@ -1340,21 +1137,19 @@ split_point_start: // At split points actual search starts from here if (PvNode && bestValue > alpha) alpha = bestValue; - // Futility pruning parameters, not needed when in check - futilityBase = ss->eval + evalMargin + FutilityMarginQS; - enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame; + futilityBase = ss->eval + ss->evalMargin + Value(128); + enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMg; } // Initialize a MovePicker object for the current position, and prepare // 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, H, move_to((ss-1)->currentMove)); + MovePicker mp(pos, ttMove, depth, H, to_sq((ss-1)->currentMove)); CheckInfo ci(pos); // Loop through the moves until no moves remain or a beta cutoff occurs - while ( bestValue < beta - && (move = mp.get_next_move()) != MOVE_NONE) + while ((move = mp.next_move()) != MOVE_NONE) { assert(is_ok(move)); @@ -1366,12 +1161,12 @@ split_point_start: // At split points actual search starts from here && !givesCheck && move != ttMove && enoughMaterial - && !is_promotion(move) + && type_of(move) != PROMOTION && !pos.is_passed_pawn_push(move)) { futilityValue = futilityBase - + PieceValueEndgame[pos.piece_on(move_to(move))] - + (is_enpassant(move) ? PawnValueEndgame : VALUE_ZERO); + + PieceValue[Eg][pos.piece_on(to_sq(move))] + + (type_of(move) == ENPASSANT ? PawnValueEg : VALUE_ZERO); if (futilityValue < beta) { @@ -1390,8 +1185,8 @@ split_point_start: // At split points actual search starts from here // Detect non-capture evasions that are candidate to be pruned evasionPrunable = !PvNode - && inCheck - && bestValue > VALUE_MATED_IN_PLY_MAX + && inCheck + && bestValue > VALUE_MATED_IN_MAX_PLY && !pos.is_capture(move) && !pos.can_castle(pos.side_to_move()); @@ -1399,7 +1194,7 @@ split_point_start: // At split points actual search starts from here if ( !PvNode && (!inCheck || evasionPrunable) && move != ttMove - && !is_promotion(move) + && type_of(move) != PROMOTION && pos.see_sign(move) < 0) continue; @@ -1409,53 +1204,54 @@ split_point_start: // At split points actual search starts from here && givesCheck && move != ttMove && !pos.is_capture_or_promotion(move) - && ss->eval + PawnValueMidgame / 4 < beta - && !check_is_dangerous(pos, move, futilityBase, beta, &bestValue)) - { - if (ss->eval + PawnValueMidgame / 4 > bestValue) - bestValue = ss->eval + PawnValueMidgame / 4; - + && ss->eval + PawnValueMg / 4 < beta + && !check_is_dangerous(pos, move, futilityBase, beta)) continue; - } // Check for legality only before to do the move if (!pos.pl_move_is_legal(move, ci.pinned)) continue; - // Update current move ss->currentMove = move; // Make and search the move pos.do_move(move, st, ci, givesCheck); - value = -qsearch(pos, ss+1, -beta, -alpha, depth-ONE_PLY); + value = -qsearch(pos, ss+1, -beta, -alpha, depth - ONE_PLY); pos.undo_move(move); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); - // New best move? + // Check for new best move if (value > bestValue) { bestValue = value; - ss->bestMove = move; - if ( PvNode - && value > alpha - && value < beta) // We want always alpha < beta - alpha = value; + if (value > alpha) + { + if (PvNode && value < beta) // Update alpha here! Always alpha < beta + { + alpha = value; + bestMove = move; + } + else // Fail high + { + TT.store(posKey, value_to_tt(value, ss->ply), BOUND_LOWER, + ttDepth, move, ss->eval, ss->evalMargin); + + return value; + } + } } } // All legal moves have been searched. A special case: If we're in check // and no legal moves were found, it is checkmate. if (inCheck && bestValue == -VALUE_INFINITE) - return value_mated_in(ss->ply); - - // Update transposition table - move = bestValue <= oldAlpha ? MOVE_NONE : ss->bestMove; - vt = bestValue <= oldAlpha ? VALUE_TYPE_UPPER - : bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT; + return mated_in(ss->ply); // Plies to mate from the root - TT.store(pos.get_key(), value_to_tt(bestValue, ss->ply), vt, ttDepth, move, ss->eval, evalMargin); + TT.store(posKey, value_to_tt(bestValue, ss->ply), + PvNode && bestMove != MOVE_NONE ? BOUND_EXACT : BOUND_UPPER, + ttDepth, bestMove, ss->eval, ss->evalMargin); assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); @@ -1467,55 +1263,43 @@ split_point_start: // At split points actual search starts from here // bestValue is updated only when returning false because in that case move // will be pruned. - bool check_is_dangerous(Position &pos, Move move, Value futilityBase, Value beta, Value *bestValue) + bool check_is_dangerous(Position &pos, Move move, Value futilityBase, Value beta) { Bitboard b, occ, oldAtt, newAtt, kingAtt; - Square from, to, ksq, victimSq; + Square from, to, ksq; Piece pc; Color them; - Value futilityValue, bv = *bestValue; - from = move_from(move); - to = move_to(move); - them = flip(pos.side_to_move()); + from = from_sq(move); + to = to_sq(move); + them = ~pos.side_to_move(); ksq = pos.king_square(them); kingAtt = pos.attacks_from(ksq); - pc = pos.piece_on(from); + pc = pos.piece_moved(move); - occ = pos.occupied_squares() & ~(1ULL << from) & ~(1ULL << ksq); + occ = pos.pieces() ^ from ^ ksq; oldAtt = pos.attacks_from(pc, from, occ); newAtt = pos.attacks_from(pc, to, occ); // Rule 1. Checks which give opponent's king at most one escape square are dangerous b = kingAtt & ~pos.pieces(them) & ~newAtt & ~(1ULL << to); - if (!(b && (b & (b - 1)))) + if (!more_than_one(b)) return true; // Rule 2. Queen contact check is very dangerous - if ( type_of(pc) == QUEEN - && bit_is_set(kingAtt, to)) + if (type_of(pc) == QUEEN && (kingAtt & to)) return true; // Rule 3. Creating new double threats with checks b = pos.pieces(them) & newAtt & ~oldAtt & ~(1ULL << ksq); - while (b) { - victimSq = pop_1st_bit(&b); - futilityValue = futilityBase + PieceValueEndgame[pos.piece_on(victimSq)]; - // Note that here we generate illegal "double move"! - if ( futilityValue >= beta - && pos.see_sign(make_move(from, victimSq)) >= 0) + if (futilityBase + PieceValue[Eg][pos.piece_on(pop_lsb(&b))] >= beta) return true; - - if (futilityValue > bv) - bv = futilityValue; } - // Update bestValue only if check is not dangerous (because we will prune the move) - *bestValue = bv; return false; } @@ -1536,67 +1320,64 @@ split_point_start: // At split points actual search starts from here assert(is_ok(m2)); // Case 1: The moving piece is the same in both moves - f2 = move_from(m2); - t1 = move_to(m1); + f2 = from_sq(m2); + t1 = to_sq(m1); if (f2 == t1) return true; // Case 2: The destination square for m2 was vacated by m1 - t2 = move_to(m2); - f1 = move_from(m1); + t2 = to_sq(m2); + f1 = from_sq(m1); if (t2 == f1) return true; // Case 3: Moving through the vacated square p2 = pos.piece_on(f2); - if ( piece_is_slider(p2) - && bit_is_set(squares_between(f2, t2), f1)) + if (piece_is_slider(p2) && (between_bb(f2, t2) & f1)) return true; // Case 4: The destination square for m2 is defended by the moving piece in m1 p1 = pos.piece_on(t1); - if (bit_is_set(pos.attacks_from(p1, t1), t2)) + if (pos.attacks_from(p1, t1) & t2) return true; // Case 5: Discovered check, checking piece is the piece moved in m1 ksq = pos.king_square(pos.side_to_move()); if ( piece_is_slider(p1) - && bit_is_set(squares_between(t1, ksq), f2)) - { - Bitboard occ = pos.occupied_squares(); - clear_bit(&occ, f2); - if (bit_is_set(pos.attacks_from(p1, t1, occ), ksq)) - return true; - } + && (between_bb(t1, ksq) & f2) + && (pos.attacks_from(p1, t1, pos.pieces() ^ f2) & ksq)) + return true; + return false; } // value_to_tt() adjusts a mate score from "plies to mate from the root" to - // "plies to mate from the current ply". Non-mate scores are unchanged. + // "plies to mate from the current position". Non-mate scores are unchanged. // The function is called before storing a value to the transposition table. Value value_to_tt(Value v, int ply) { - if (v >= VALUE_MATE_IN_PLY_MAX) + if (v >= VALUE_MATE_IN_MAX_PLY) return v + ply; - if (v <= VALUE_MATED_IN_PLY_MAX) + if (v <= VALUE_MATED_IN_MAX_PLY) return v - ply; return v; } - // value_from_tt() is the inverse of value_to_tt(): It adjusts a mate score from - // the transposition table to a mate score corrected for the current ply. + // value_from_tt() is the inverse of value_to_tt(): It adjusts a mate score + // from the transposition table (where refers to the plies to mate/be mated + // from current position) to "plies to mate/be mated from the root". Value value_from_tt(Value v, int ply) { - if (v >= VALUE_MATE_IN_PLY_MAX) + if (v >= VALUE_MATE_IN_MAX_PLY) return v - ply; - if (v <= VALUE_MATED_IN_PLY_MAX) + if (v <= VALUE_MATED_IN_MAX_PLY) return v + ply; return v; @@ -1615,10 +1396,10 @@ split_point_start: // At split points actual search starts from here Square mfrom, mto, tfrom, tto; - mfrom = move_from(m); - mto = move_to(m); - tfrom = move_from(threat); - tto = move_to(threat); + mfrom = from_sq(m); + mto = to_sq(m); + tfrom = from_sq(threat); + tto = to_sq(threat); // Case 1: Don't prune moves which move the threatened piece if (mfrom == tto) @@ -1627,429 +1408,228 @@ split_point_start: // At split points actual search starts from here // Case 2: If the threatened piece has value less than or equal to the // value of the threatening piece, don't prune moves which defend it. if ( pos.is_capture(threat) - && ( PieceValueMidgame[pos.piece_on(tfrom)] >= PieceValueMidgame[pos.piece_on(tto)] + && ( PieceValue[Mg][pos.piece_on(tfrom)] >= PieceValue[Mg][pos.piece_on(tto)] || type_of(pos.piece_on(tfrom)) == KING) && pos.move_attacks_square(m, tto)) return true; // Case 3: If the moving piece in the threatened move is a slider, don't // prune safe moves which block its ray. - if ( piece_is_slider(pos.piece_on(tfrom)) - && bit_is_set(squares_between(tfrom, tto), mto) - && pos.see_sign(m) >= 0) + if ( piece_is_slider(pos.piece_on(tfrom)) + && (between_bb(tfrom, tto) & mto) + && pos.see_sign(m) >= 0) return true; return false; } - // can_return_tt() returns true if a transposition table score - // can be used to cut-off at a given point in search. - - bool can_return_tt(const TTEntry* tte, Depth depth, Value beta, int ply) { - - Value v = value_from_tt(tte->value(), ply); - - return ( tte->depth() >= depth - || v >= std::max(VALUE_MATE_IN_PLY_MAX, beta) - || v < std::min(VALUE_MATED_IN_PLY_MAX, beta)) - - && ( ((tte->type() & VALUE_TYPE_LOWER) && v >= beta) - || ((tte->type() & VALUE_TYPE_UPPER) && v < beta)); - } - + // refine_eval() returns the transposition table score if possible, otherwise + // falls back on static position evaluation. - // refine_eval() returns the transposition table score if - // possible otherwise falls back on static position evaluation. - - Value refine_eval(const TTEntry* tte, Value defaultEval, int ply) { + Value refine_eval(const TTEntry* tte, Value v, Value defaultEval) { assert(tte); - Value v = value_from_tt(tte->value(), ply); - - if ( ((tte->type() & VALUE_TYPE_LOWER) && v >= defaultEval) - || ((tte->type() & VALUE_TYPE_UPPER) && v < defaultEval)) + if ( ((tte->type() & BOUND_LOWER) && v >= defaultEval) + || ((tte->type() & BOUND_UPPER) && v < defaultEval)) return v; return defaultEval; } - // update_history() registers a good move that produced a beta-cutoff - // in history and marks as failures all the other moves of that ply. - - void update_history(const Position& pos, Move move, Depth depth, - Move movesSearched[], int moveCount) { - Move m; - Value bonus = Value(int(depth) * int(depth)); - - H.update(pos.piece_on(move_from(move)), move_to(move), bonus); - - for (int i = 0; i < moveCount - 1; i++) - { - m = movesSearched[i]; - - assert(m != move); - - H.update(pos.piece_on(move_from(m)), move_to(m), -bonus); - } - } - - - // current_search_time() returns the number of milliseconds which have passed - // since the beginning of the current search. - - int elapsed_time(bool reset) { - - static int searchStartTime; - - if (reset) - searchStartTime = get_system_time(); - - return get_system_time() - searchStartTime; - } - - - // score_to_uci() converts a value to a string suitable for use with the UCI - // protocol specifications: - // - // cp The score from the engine's point of view in centipawns. - // mate Mate in y moves, not plies. If the engine is getting mated - // use negative values for y. - - string score_to_uci(Value v, Value alpha, Value beta) { - - std::stringstream s; - - if (abs(v) < VALUE_MATE - PLY_MAX * ONE_PLY) - s << " score cp " << int(v) * 100 / int(PawnValueMidgame); // Scale to centipawns - else - s << " score mate " << (v > 0 ? VALUE_MATE - v + 1 : -VALUE_MATE - v) / 2; - - s << (v >= beta ? " lowerbound" : v <= alpha ? " upperbound" : ""); - - return s.str(); - } - - - // speed_to_uci() returns a string with time stats of current search suitable - // to be sent to UCI gui. - - string speed_to_uci(int64_t nodes) { - - std::stringstream s; - int t = elapsed_time(); - - s << " nodes " << nodes - << " nps " << (t > 0 ? int(nodes * 1000 / t) : 0) - << " time " << t; - - return s.str(); - } - - - // pv_to_uci() returns a string with information on the current PV line - // formatted according to UCI specification. - - string pv_to_uci(const Move pv[], int pvNum, bool chess960) { - - std::stringstream s; - - s << " multipv " << pvNum << " pv " << set960(chess960); - - for ( ; *pv != MOVE_NONE; pv++) - s << *pv << " "; - - return s.str(); - } - - - // depth_to_uci() returns a string with information on the current depth and - // seldepth formatted according to UCI specification. - - string depth_to_uci(Depth depth) { - - std::stringstream s; - - // Retrieve max searched depth among threads - int selDepth = 0; - for (int i = 0; i < Threads.size(); i++) - if (Threads[i].maxPly > selDepth) - selDepth = Threads[i].maxPly; - - s << " depth " << depth / ONE_PLY << " seldepth " << selDepth; - - return s.str(); - } - - string time_to_string(int millisecs) { - - const int MSecMinute = 1000 * 60; - const int MSecHour = 1000 * 60 * 60; - - int hours = millisecs / MSecHour; - int minutes = (millisecs % MSecHour) / MSecMinute; - int seconds = ((millisecs % MSecHour) % MSecMinute) / 1000; - - std::stringstream s; - - if (hours) - s << hours << ':'; - - s << std::setfill('0') << std::setw(2) << minutes << ':' << std::setw(2) << seconds; - return s.str(); - } - - string score_to_string(Value v) { - - std::stringstream s; - - if (v >= VALUE_MATE_IN_PLY_MAX) - s << "#" << (VALUE_MATE - v + 1) / 2; - else if (v <= VALUE_MATED_IN_PLY_MAX) - s << "-#" << (VALUE_MATE + v) / 2; - else - s << std::setprecision(2) << std::fixed << std::showpos << float(v) / PawnValueMidgame; - - return s.str(); - } - - - // pretty_pv() creates a human-readable string from a position and a PV. - // It is used to write search information to the log file (which is created - // when the UCI parameter "Use Search Log" is "true"). - - string pretty_pv(Position& pos, int depth, Value value, int time, Move pv[]) { - - const int64_t K = 1000; - const int64_t M = 1000000; - const int startColumn = 28; - const size_t maxLength = 80 - startColumn; - - StateInfo state[PLY_MAX_PLUS_2], *st = state; - Move* m = pv; - string san; - std::stringstream s; - size_t length = 0; - - // First print depth, score, time and searched nodes... - s << set960(pos.is_chess960()) - << std::setw(2) << depth - << std::setw(8) << score_to_string(value) - << std::setw(8) << time_to_string(time); - - if (pos.nodes_searched() < M) - s << std::setw(8) << pos.nodes_searched() / 1 << " "; - else if (pos.nodes_searched() < K * M) - s << std::setw(7) << pos.nodes_searched() / K << "K "; - else - s << std::setw(7) << pos.nodes_searched() / M << "M "; - - // ...then print the full PV line in short algebraic notation - while (*m != MOVE_NONE) - { - san = move_to_san(pos, *m); - length += san.length() + 1; - - if (length > maxLength) - { - length = san.length() + 1; - s << "\n" + string(startColumn, ' '); - } - s << san << ' '; - - pos.do_move(*m++, *st++); - } - - // Restore original position before to leave - while (m != pv) pos.undo_move(*--m); - - return s.str(); - } - - // When playing with strength handicap choose best move among the MultiPV set // using a statistical rule dependent on SkillLevel. Idea by Heinz van Saanen. - void do_skill_level(Move* best, Move* ponder) { + Move do_skill_level() { assert(MultiPV > 1); static RKISS rk; - // Rml list is already sorted by score in descending order - int s; - int max_s = -VALUE_INFINITE; - int size = std::min(MultiPV, (int)Rml.size()); - int max = Rml[0].score; - int var = std::min(max - Rml[size - 1].score, int(PawnValueMidgame)); - int wk = 120 - 2 * SkillLevel; - - // PRNG sequence should be non deterministic - for (int i = abs(get_system_time() % 50); i > 0; i--) + // PRNG sequence should be not deterministic + for (int i = Time::now() % 50; i > 0; i--) rk.rand(); - // Choose best move. For each move's score we add two terms both dependent - // on wk, one deterministic and bigger for weaker moves, and one random, + // RootMoves are already sorted by score in descending order + size_t size = std::min(MultiPV, RootMoves.size()); + int variance = std::min(RootMoves[0].score - RootMoves[size - 1].score, PawnValueMg); + int weakness = 120 - 2 * SkillLevel; + int max_s = -VALUE_INFINITE; + Move 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 (int i = 0; i < size; i++) + for (size_t i = 0; i < size; i++) { - s = Rml[i].score; + int s = RootMoves[i].score; // Don't allow crazy blunders even at very low skills - if (i > 0 && Rml[i-1].score > s + EasyMoveMargin) + if (i > 0 && RootMoves[i-1].score > s + 2 * PawnValueMg) break; - // This is our magical formula - s += ((max - s) * wk + var * (rk.rand() % wk)) / 128; + // This is our magic formula + s += ( weakness * int(RootMoves[0].score - s) + + variance * (rk.rand() % weakness)) / 128; if (s > max_s) { max_s = s; - *best = Rml[i].pv[0]; - *ponder = Rml[i].pv[1]; + best = RootMoves[i].pv[0]; } } + return best; } - /// RootMove and RootMoveList method's definitions + // uci_pv() formats PV information according to UCI protocol. UCI requires + // to send all the PV lines also if are still to be searched and so refer to + // the previous search score. - void RootMoveList::init(Position& pos, Move rootMoves[]) { + string uci_pv(const Position& pos, int depth, Value alpha, Value beta) { + + std::stringstream s; + Time::point elaspsed = Time::now() - SearchTime + 1; + int selDepth = 0; - Move* sm; - bestMoveChanges = 0; - clear(); + for (size_t i = 0; i < Threads.size(); i++) + if (Threads[i].maxPly > selDepth) + selDepth = Threads[i].maxPly; - // Generate all legal moves and add them to RootMoveList - for (MoveList ml(pos); !ml.end(); ++ml) + for (size_t i = 0; i < std::min(UCIMultiPV, RootMoves.size()); i++) { - // If we have a rootMoves[] list then verify the move - // is in the list before to add it. - for (sm = rootMoves; *sm && *sm != ml.move(); sm++) {} + bool updated = (i <= PVIdx); - if (sm != rootMoves && *sm != ml.move()) + if (depth == 1 && !updated) continue; - RootMove rm; - rm.pv.push_back(ml.move()); - rm.pv.push_back(MOVE_NONE); - rm.score = rm.prevScore = -VALUE_INFINITE; - rm.nodes = 0; - push_back(rm); - } - } + int d = (updated ? depth : depth - 1); + Value v = (updated ? RootMoves[i].score : RootMoves[i].prevScore); - RootMove* RootMoveList::find(const Move& m, int startIndex) { + if (s.rdbuf()->in_avail()) + s << "\n"; - for (size_t i = startIndex; i < size(); i++) - if ((*this)[i].pv[0] == m) - return &(*this)[i]; + s << "info depth " << d + << " seldepth " << selDepth + << " score " << (i == PVIdx ? score_to_uci(v, alpha, beta) : score_to_uci(v)) + << " nodes " << pos.nodes_searched() + << " nps " << pos.nodes_searched() * 1000 / elaspsed + << " time " << elaspsed + << " multipv " << i + 1 + << " pv"; - return NULL; + for (size_t j = 0; RootMoves[i].pv[j] != MOVE_NONE; j++) + s << " " << move_to_uci(RootMoves[i].pv[j], Chess960); + } + + return s.str(); } +} // namespace - // extract_pv_from_tt() builds a PV by adding moves from the transposition table. - // We consider also failing high nodes and not only VALUE_TYPE_EXACT nodes. This - // allow to always have a ponder move even when we fail high at root and also a - // long PV to print that is important for position analysis. - void RootMove::extract_pv_from_tt(Position& pos) { +/// RootMove::extract_pv_from_tt() builds a PV by adding moves from the TT table. +/// We consider also failing high nodes and not only BOUND_EXACT nodes so to +/// allow to always have a ponder move even when we fail high at root, and a +/// long PV to print that is important for position analysis. - StateInfo state[PLY_MAX_PLUS_2], *st = state; - TTEntry* tte; - int ply = 1; - Move m = pv[0]; +void RootMove::extract_pv_from_tt(Position& pos) { - assert(m != MOVE_NONE && pos.is_pseudo_legal(m)); + StateInfo state[MAX_PLY_PLUS_2], *st = state; + TTEntry* tte; + int ply = 1; + Move m = pv[0]; - pv.clear(); - pv.push_back(m); - pos.do_move(m, *st++); + assert(m != MOVE_NONE && pos.is_pseudo_legal(m)); - while ( (tte = TT.probe(pos.get_key())) != NULL - && tte->move() != MOVE_NONE - && pos.is_pseudo_legal(tte->move()) - && pos.pl_move_is_legal(tte->move(), pos.pinned_pieces()) - && ply < PLY_MAX - && (!pos.is_draw() || ply < 2)) - { - pv.push_back(tte->move()); - pos.do_move(tte->move(), *st++); - ply++; - } - pv.push_back(MOVE_NONE); + pv.clear(); + pv.push_back(m); + pos.do_move(m, *st++); - do pos.undo_move(pv[--ply]); while (ply); + while ( (tte = TT.probe(pos.key())) != NULL + && (m = tte->move()) != MOVE_NONE // Local copy, TT entry could change + && pos.is_pseudo_legal(m) + && pos.pl_move_is_legal(m, pos.pinned_pieces()) + && ply < MAX_PLY + && (!pos.is_draw() || ply < 2)) + { + pv.push_back(m); + pos.do_move(m, *st++); + ply++; } + pv.push_back(MOVE_NONE); + do pos.undo_move(pv[--ply]); while (ply); +} - // 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) { +/// 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. - StateInfo state[PLY_MAX_PLUS_2], *st = state; - TTEntry* tte; - Key k; - Value v, m = VALUE_NONE; - int ply = 0; +void RootMove::insert_pv_in_tt(Position& pos) { - assert(pv[0] != MOVE_NONE && pos.is_pseudo_legal(pv[0])); + StateInfo state[MAX_PLY_PLUS_2], *st = state; + TTEntry* tte; + Key k; + Value v, m = VALUE_NONE; + int ply = 0; - do { - k = pos.get_key(); - tte = TT.probe(k); + assert(pv[ply] != MOVE_NONE && pos.is_pseudo_legal(pv[ply])); - // Don't overwrite existing correct entries - if (!tte || tte->move() != pv[ply]) - { - v = (pos.in_check() ? VALUE_NONE : evaluate(pos, m)); - TT.store(k, VALUE_NONE, VALUE_TYPE_NONE, DEPTH_NONE, pv[ply], v, m); - } - pos.do_move(pv[ply], *st++); + do { + k = pos.key(); + tte = TT.probe(k); - } while (pv[++ply] != MOVE_NONE); + // Don't overwrite existing correct entries + if (!tte || tte->move() != pv[ply]) + { + v = (pos.in_check() ? VALUE_NONE : evaluate(pos, m)); + TT.store(k, VALUE_NONE, BOUND_NONE, DEPTH_NONE, pv[ply], v, m); + } + pos.do_move(pv[ply], *st++); - do pos.undo_move(pv[--ply]); while (ply); - } + } while (pv[++ply] != MOVE_NONE); + + do pos.undo_move(pv[--ply]); while (ply); +} -} // namespace +/// Thread::idle_loop() is where the thread is parked when it has no work to do -// Thread::idle_loop() is where the thread is parked when it has no work to do. -// The parameter 'sp', if non-NULL, is a pointer to an active SplitPoint object -// for which the thread is the master. +void Thread::idle_loop() { -void Thread::idle_loop(SplitPoint* sp) { + // Pointer 'sp_master', if non-NULL, points to the active SplitPoint + // object for which the thread is the master. + const SplitPoint* sp_master = splitPointsCnt ? curSplitPoint : NULL; - while (true) + assert(!sp_master || (sp_master->master == this && is_searching)); + + // 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. + while (!sp_master || sp_master->slavesMask) { // If we are not searching, wait for a condition to be signaled // instead of wasting CPU time polling for work. while ( do_sleep - || do_terminate - || (Threads.use_sleeping_threads() && !is_searching)) + || do_exit + || (!is_searching && Threads.use_sleeping_threads())) { - assert((!sp && threadID) || Threads.use_sleeping_threads()); - - // Slave thread should exit as soon as do_terminate flag raises - if (do_terminate) + if (do_exit) { - assert(!sp); + assert(!sp_master); return; } // Grab the lock to avoid races with Thread::wake_up() - lock_grab(&sleepLock); + mutex.lock(); // If we are master and all slaves have finished don't go to sleep - if (sp && Threads.split_point_finished(sp)) + if (sp_master && !sp_master->slavesMask) { - lock_release(&sleepLock); + mutex.unlock(); break; } @@ -2058,88 +1638,128 @@ void Thread::idle_loop(SplitPoint* sp) { // in the meanwhile, allocated us and sent the wake_up() call before we // had the chance to grab the lock. if (do_sleep || !is_searching) - cond_wait(&sleepCond, &sleepLock); + sleepCondition.wait(mutex); - lock_release(&sleepLock); + mutex.unlock(); } // If this thread has been assigned work, launch a search if (is_searching) { - assert(!do_terminate); - - // Copy split point position and search stack and call search() - Stack ss[PLY_MAX_PLUS_2]; - SplitPoint* tsp = splitPoint; - Position pos(*tsp->pos, threadID); - - memcpy(ss, tsp->ss - 1, 4 * sizeof(Stack)); - (ss+1)->sp = tsp; - - if (tsp->nodeType == Root) - search(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth); - else if (tsp->nodeType == PV) - search(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth); - else if (tsp->nodeType == NonPV) - search(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth); + assert(!do_sleep && !do_exit); + + Threads.mutex.lock(); + + assert(is_searching); + SplitPoint* sp = curSplitPoint; + + Threads.mutex.unlock(); + + Stack ss[MAX_PLY_PLUS_2]; + Position pos(*sp->pos, this); + + memcpy(ss, sp->ss - 1, 4 * sizeof(Stack)); + (ss+1)->sp = sp; + + sp->mutex.lock(); + + assert(sp->activePositions[idx] == NULL); + + sp->activePositions[idx] = &pos; + + if (sp->nodeType == Root) + search(pos, ss+1, sp->alpha, sp->beta, sp->depth); + else if (sp->nodeType == PV) + search(pos, ss+1, sp->alpha, sp->beta, sp->depth); + else if (sp->nodeType == NonPV) + search(pos, ss+1, sp->alpha, sp->beta, sp->depth); else assert(false); assert(is_searching); is_searching = false; + sp->activePositions[idx] = NULL; + sp->slavesMask &= ~(1ULL << idx); + sp->nodes += pos.nodes_searched(); // Wake up master thread so to allow it to return from the idle loop in // case we are the last slave of the split point. - if ( Threads.use_sleeping_threads() - && threadID != tsp->master - && !Threads[tsp->master].is_searching) - Threads[tsp->master].wake_up(); - } + if ( Threads.use_sleeping_threads() + && this != sp->master + && !sp->slavesMask) + { + assert(!sp->master->is_searching); + sp->master->wake_up(); + } - // 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. - if (sp && Threads.split_point_finished(sp)) - { - // Because sp->is_slave[] is reset under lock protection, - // be sure sp->lock has been released before to return. - lock_grab(&(sp->lock)); - lock_release(&(sp->lock)); - return; + // After releasing the lock we cannot access anymore any SplitPoint + // related data in a safe way becuase it could have been released under + // our feet by the sp master. Also accessing other Thread objects is + // unsafe because if we are exiting there is a chance are already freed. + sp->mutex.unlock(); } } } -// do_timer_event() is called by the timer thread when the timer triggers +/// check_time() is called by the timer thread when the timer triggers. It is +/// used to print debug info and, more important, to detect when we are out of +/// available time and so stop the search. -void do_timer_event() { +void check_time() { - static int lastInfoTime; - int e = elapsed_time(); + static Time::point lastInfoTime = Time::now(); + int64_t nodes = 0; // Workaround silly 'uninitialized' gcc warning - // Print debug information every one second - if (!lastInfoTime || get_system_time() - lastInfoTime >= 1000) + if (Time::now() - lastInfoTime >= 1000) { - lastInfoTime = get_system_time(); - - dbg_print_mean(); - dbg_print_hit_rate(); + lastInfoTime = Time::now(); + dbg_print(); } - // Should we stop the search? if (Limits.ponder) return; + if (Limits.nodes) + { + Threads.mutex.lock(); + + nodes = RootPosition.nodes_searched(); + + // Loop across all split points and sum accumulated SplitPoint nodes plus + // all the currently active slaves positions. + for (size_t i = 0; i < Threads.size(); i++) + for (int j = 0; j < Threads[i].splitPointsCnt; j++) + { + SplitPoint& sp = Threads[i].splitPoints[j]; + + sp.mutex.lock(); + + nodes += sp.nodes; + Bitboard sm = sp.slavesMask; + while (sm) + { + Position* pos = sp.activePositions[pop_lsb(&sm)]; + nodes += pos ? pos->nodes_searched() : 0; + } + + sp.mutex.unlock(); + } + + Threads.mutex.unlock(); + } + + Time::point elapsed = Time::now() - SearchTime; bool stillAtFirstMove = Signals.firstRootMove && !Signals.failedLowAtRoot - && e > TimeMgr.available_time(); + && elapsed > TimeMgr.available_time(); - bool noMoreTime = e > TimeMgr.maximum_time() + bool noMoreTime = elapsed > TimeMgr.maximum_time() - 2 * TimerResolution || stillAtFirstMove; - if ( (Limits.useTimeManagement() && noMoreTime) - || (Limits.maxTime && e >= Limits.maxTime) - /* missing nodes limit */ ) // FIXME + if ( (Limits.use_time_management() && noMoreTime) + || (Limits.movetime && elapsed >= Limits.movetime) + || (Limits.nodes && nodes >= Limits.nodes)) Signals.stop = true; }