X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=dfe5efa922840b8cc398152495c292045b2e5993;hp=3e74ddc2168af68d20774a46402fcbdadc1748ec;hb=81ae7cad2d5f1bdce7e065699bf680da8b5487b8;hpb=a093f33154cdd7b1d82e41f67fc673d3a22545bc diff --git a/src/search.cpp b/src/search.cpp index 3e74ddc2..dfe5efa9 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) 2008-2009 Marco Costalba + Copyright (C) 2008-2010 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 @@ -70,39 +70,36 @@ namespace { int active_threads() const { return ActiveThreads; } void set_active_threads(int newActiveThreads) { ActiveThreads = newActiveThreads; } - void set_stop_request(int threadID) { threads[threadID].stopRequest = true; } void incrementNodeCounter(int threadID) { threads[threadID].nodes++; } void incrementBetaCounter(Color us, Depth d, int threadID) { threads[threadID].betaCutOffs[us] += unsigned(d); } - void print_current_line(SearchStack ss[], int ply, int threadID); void resetNodeCounters(); void resetBetaCounters(); int64_t nodes_searched() const; void get_beta_counters(Color us, int64_t& our, int64_t& their) const; - bool idle_thread_exists(int master) const; + bool available_thread_exists(int master) const; bool thread_is_available(int slave, int master) const; bool thread_should_stop(int threadID) const; void wake_sleeping_threads(); void put_threads_to_sleep(); void idle_loop(int threadID, SplitPoint* waitSp); - bool split(const Position& pos, SearchStack* ss, int ply, Value* alpha, Value* beta, Value* bestValue, - const Value futilityValue, Depth depth, int* moves, MovePicker* mp, int master, bool pvNode); + bool split(const Position& pos, SearchStack* ss, int ply, Value* alpha, const Value beta, Value* bestValue, + Depth depth, bool mateThreat, int* moves, MovePicker* mp, int master, bool pvNode); private: friend void poll(); int ActiveThreads; - bool AllThreadsShouldExit, AllThreadsShouldSleep; - Thread threads[THREAD_MAX]; - SplitPoint SplitPointStack[THREAD_MAX][ACTIVE_SPLIT_POINTS_MAX]; + volatile bool AllThreadsShouldExit, AllThreadsShouldSleep; + Thread threads[MAX_THREADS]; + SplitPoint SplitPointStack[MAX_THREADS][ACTIVE_SPLIT_POINTS_MAX]; - Lock MPLock, IOLock; + Lock MPLock, WaitLock; #if !defined(_MSC_VER) pthread_cond_t WaitCond; - pthread_mutex_t WaitLock; #else - HANDLE SitIdleEvent[THREAD_MAX]; + HANDLE SitIdleEvent[MAX_THREADS]; #endif }; @@ -160,56 +157,79 @@ namespace { }; - /// Constants + /// Adjustments - // Search depth at iteration 1 - const Depth InitialDepth = OnePly; + // Step 6. Razoring - // Use internal iterative deepening? - const bool UseIIDAtPVNodes = true; - const bool UseIIDAtNonPVNodes = true; + // Maximum depth for razoring + const Depth RazorDepth = 4 * OnePly; - // Internal iterative deepening margin. At Non-PV moves, when - // UseIIDAtNonPVNodes is true, we do an internal iterative deepening - // search when the static evaluation is at most IIDMargin below beta. - const Value IIDMargin = Value(0x100); + // Dynamic razoring margin based on depth + inline Value razor_margin(Depth d) { return Value(0x200 + 0x10 * int(d)); } - // Easy move margin. An easy move candidate must be at least this much - // better than the second best move. - const Value EasyMoveMargin = Value(0x200); + // Step 8. Null move search with verification search // Null move margin. A null move search will not be done if the static // evaluation of the position is more than NullMoveMargin below beta. const Value NullMoveMargin = Value(0x200); - // If the TT move is at least SingleReplyMargin better then the + // Maximum depth for use of dynamic threat detection when null move fails low + const Depth ThreatDepth = 5 * OnePly; + + // Step 9. Internal iterative deepening + + // Minimum depth for use of internal iterative deepening + const Depth IIDDepthAtPVNodes = 5 * OnePly; + const Depth IIDDepthAtNonPVNodes = 8 * OnePly; + + // At Non-PV nodes we do an internal iterative deepening search + // when the static evaluation is at most IIDMargin below beta. + const Value IIDMargin = Value(0x100); + + // Step 11. Decide the new search depth + + // Extensions. Configurable UCI options + // Array index 0 is used at non-PV nodes, index 1 at PV nodes. + Depth CheckExtension[2], SingleEvasionExtension[2], PawnPushTo7thExtension[2]; + Depth PassedPawnExtension[2], PawnEndgameExtension[2], MateThreatExtension[2]; + + // Minimum depth for use of singular extension + const Depth SingularExtensionDepthAtPVNodes = 6 * OnePly; + const Depth SingularExtensionDepthAtNonPVNodes = 8 * OnePly; + + // If the TT move is at least SingularExtensionMargin better then the // remaining ones we will extend it. - const Value SingleReplyMargin = Value(0x20); + const Value SingularExtensionMargin = Value(0x20); - // Depth limit for razoring - const Depth RazorDepth = 4 * OnePly; + // Step 12. Futility pruning + + // Futility margin for quiescence search + const Value FutilityMarginQS = Value(0x80); - /// Lookup tables initialized at startup + // Futility lookup tables (initialized at startup) and their getter functions + int32_t FutilityMarginsMatrix[16][64]; // [depth][moveNumber] + int FutilityMoveCountArray[32]; // [depth] + + inline Value futility_margin(Depth d, int mn) { return Value(d < 7 * OnePly ? FutilityMarginsMatrix[Max(d, 0)][Min(mn, 63)] : 2 * VALUE_INFINITE); } + inline int futility_move_count(Depth d) { return d < 16 * OnePly ? FutilityMoveCountArray[d] : 512; } + + // Step 14. Reduced search - // Reduction lookup tables and their getter functions + // Reduction lookup tables (initialized at startup) and their getter functions int8_t PVReductionMatrix[64][64]; // [depth][moveNumber] int8_t NonPVReductionMatrix[64][64]; // [depth][moveNumber] inline Depth pv_reduction(Depth d, int mn) { return (Depth) PVReductionMatrix[Min(d / 2, 63)][Min(mn, 63)]; } inline Depth nonpv_reduction(Depth d, int mn) { return (Depth) NonPVReductionMatrix[Min(d / 2, 63)][Min(mn, 63)]; } - // Futility lookup tables and their getter functions - const Value FutilityMarginQS = Value(0x80); - int32_t FutilityMarginsMatrix[14][64]; // [depth][moveNumber] - int FutilityMoveCountArray[32]; // [depth] - - inline Value futility_margin(Depth d, int mn) { return Value(d < 7*OnePly ? FutilityMarginsMatrix[Max(d, 0)][Min(mn, 63)] : 2 * VALUE_INFINITE); } - inline int futility_move_count(Depth d) { return d < 16*OnePly ? FutilityMoveCountArray[d] : 512; } + // Common adjustments - /// Variables initialized by UCI options + // Search depth at iteration 1 + const Depth InitialDepth = OnePly; - // Depth limit for use of dynamic threat detection - Depth ThreatDepth; + // Easy move margin. An easy move candidate must be at least this much + // better than the second best move. + const Value EasyMoveMargin = Value(0x200); // Last seconds noise filtering (LSN) const bool UseLSNFiltering = true; @@ -217,11 +237,10 @@ namespace { const Value LSNValue = value_from_centipawns(200); bool loseOnTime = false; - // Extensions. Array index 0 is used at non-PV nodes, index 1 at PV nodes. - Depth CheckExtension[2], SingleEvasionExtension[2], PawnPushTo7thExtension[2]; - Depth PassedPawnExtension[2], PawnEndgameExtension[2], MateThreatExtension[2]; - // Iteration counters + /// Global variables + + // Iteration counter int Iteration; // Scores and number of times the best move changed for each iteration @@ -235,38 +254,32 @@ namespace { int MultiPV; // Time managment variables - int RootMoveNumber; - int SearchStartTime; - int MaxNodes, MaxDepth; - int MaxSearchTime, AbsoluteMaxSearchTime, ExtraSearchTime, ExactMaxTime; + int SearchStartTime, MaxNodes, MaxDepth, MaxSearchTime; + int AbsoluteMaxSearchTime, ExtraSearchTime, ExactMaxTime; bool UseTimeManagement, InfiniteSearch, PonderSearch, StopOnPonderhit; - bool AbortSearch, Quit; - bool AspirationFailLow; - - // Show current line? - bool ShowCurrentLine; + bool FirstRootMove, AbortSearch, Quit, AspirationFailLow; // Log file bool UseLogFile; std::ofstream LogFile; - // MP related variables + // Multi-threads related variables Depth MinimumSplitDepth; int MaxThreadsPerSplitPoint; ThreadsManager TM; - // Node counters, used only by thread[0] but try to keep in different - // cache lines (64 bytes each) from the heavy SMP read accessed variables. + // Node counters, used only by thread[0] but try to keep in different cache + // lines (64 bytes each) from the heavy multi-thread read accessed variables. int NodesSincePoll; int NodesBetweenPolls = 30000; // History table History H; - /// Functions + /// Local functions Value id_loop(const Position& pos, Move searchMoves[]); - Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value& oldAlpha, Value& beta); + Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value* alphaPtr, Value* betaPtr); Value search_pv(Position& pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID); Value search(Position& pos, SearchStack ss[], Value beta, Depth depth, int ply, bool allowNullmove, int threadID, Move excludedMove = MOVE_NONE); Value qsearch(Position& pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID); @@ -281,7 +294,7 @@ namespace { Depth extension(const Position&, Move, bool, bool, bool, bool, bool, bool*); bool ok_to_do_nullmove(const Position& pos); bool ok_to_prune(const Position& pos, Move m, Move threat); - bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply); + bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply, bool allowNullmove); 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 update_killers(Move m, SearchStack& ss); @@ -293,6 +306,7 @@ namespace { void ponderhit(); void wait_for_stop_or_ponderhit(); void init_ss_array(SearchStack ss[]); + void print_pv_info(const Position& pos, SearchStack ss[], Value alpha, Value beta, Value value); #if !defined(_MSC_VER) void *init_thread(void *threadID); @@ -320,9 +334,10 @@ int64_t nodes_searched() { return TM.nodes_searched(); } int perft(Position& pos, Depth depth) { + StateInfo st; Move move; int sum = 0; - MovePicker mp = MovePicker(pos, MOVE_NONE, depth, H); + MovePicker mp(pos, MOVE_NONE, depth, H); // If we are at the last ply we don't need to do and undo // the moves, just to count them. @@ -336,7 +351,6 @@ int perft(Position& pos, Depth depth) CheckInfo ci(pos); while ((move = mp.get_next_move()) != MOVE_NONE) { - StateInfo st; pos.do_move(move, st, ci, pos.move_is_check(move, ci)); sum += perft(pos, depth - OnePly); pos.undo_move(move); @@ -355,9 +369,10 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move, int maxNodes, int maxTime, Move searchMoves[]) { // Initialize global search variables - StopOnPonderhit = AbortSearch = Quit = false; - AspirationFailLow = false; + StopOnPonderhit = AbortSearch = Quit = AspirationFailLow = false; + MaxSearchTime = AbsoluteMaxSearchTime = ExtraSearchTime = 0; NodesSincePoll = 0; + TM.resetNodeCounters(); SearchStartTime = get_system_time(); ExactMaxTime = maxTime; MaxDepth = maxDepth; @@ -369,11 +384,10 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move, // Look for a book move, only during games, not tests if (UseTimeManagement && get_option_value_bool("OwnBook")) { - Move bookMove; if (get_option_value_string("Book File") != OpeningBook.file_name()) OpeningBook.open(get_option_value_string("Book File")); - bookMove = OpeningBook.get_move(pos); + Move bookMove = OpeningBook.get_move(pos, get_option_value_bool("Best Book Move")); if (bookMove != MOVE_NONE) { if (PonderSearch) @@ -384,48 +398,37 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move, } } - TM.resetNodeCounters(); - + // Reset loseOnTime flag at the beginning of a new game if (button_was_pressed("New Game")) - loseOnTime = false; // Reset at the beginning of a new game + loseOnTime = false; // Read UCI option values TT.set_size(get_option_value_int("Hash")); if (button_was_pressed("Clear Hash")) TT.clear(); - bool PonderingEnabled = get_option_value_bool("Ponder"); - MultiPV = get_option_value_int("MultiPV"); - - CheckExtension[1] = Depth(get_option_value_int("Check Extension (PV nodes)")); - CheckExtension[0] = Depth(get_option_value_int("Check Extension (non-PV nodes)")); - + CheckExtension[1] = Depth(get_option_value_int("Check Extension (PV nodes)")); + CheckExtension[0] = Depth(get_option_value_int("Check Extension (non-PV nodes)")); SingleEvasionExtension[1] = Depth(get_option_value_int("Single Evasion Extension (PV nodes)")); SingleEvasionExtension[0] = Depth(get_option_value_int("Single Evasion Extension (non-PV nodes)")); - PawnPushTo7thExtension[1] = Depth(get_option_value_int("Pawn Push to 7th Extension (PV nodes)")); PawnPushTo7thExtension[0] = Depth(get_option_value_int("Pawn Push to 7th Extension (non-PV nodes)")); + PassedPawnExtension[1] = Depth(get_option_value_int("Passed Pawn Extension (PV nodes)")); + PassedPawnExtension[0] = Depth(get_option_value_int("Passed Pawn Extension (non-PV nodes)")); + PawnEndgameExtension[1] = Depth(get_option_value_int("Pawn Endgame Extension (PV nodes)")); + PawnEndgameExtension[0] = Depth(get_option_value_int("Pawn Endgame Extension (non-PV nodes)")); + MateThreatExtension[1] = Depth(get_option_value_int("Mate Threat Extension (PV nodes)")); + MateThreatExtension[0] = Depth(get_option_value_int("Mate Threat Extension (non-PV nodes)")); + + MinimumSplitDepth = get_option_value_int("Minimum Split Depth") * OnePly; + MaxThreadsPerSplitPoint = get_option_value_int("Maximum Number of Threads per Split Point"); + MultiPV = get_option_value_int("MultiPV"); + Chess960 = get_option_value_bool("UCI_Chess960"); + UseLogFile = get_option_value_bool("Use Search Log"); - PassedPawnExtension[1] = Depth(get_option_value_int("Passed Pawn Extension (PV nodes)")); - PassedPawnExtension[0] = Depth(get_option_value_int("Passed Pawn Extension (non-PV nodes)")); - - PawnEndgameExtension[1] = Depth(get_option_value_int("Pawn Endgame Extension (PV nodes)")); - PawnEndgameExtension[0] = Depth(get_option_value_int("Pawn Endgame Extension (non-PV nodes)")); - - MateThreatExtension[1] = Depth(get_option_value_int("Mate Threat Extension (PV nodes)")); - MateThreatExtension[0] = Depth(get_option_value_int("Mate Threat Extension (non-PV nodes)")); - - ThreatDepth = get_option_value_int("Threat Depth") * OnePly; - - Chess960 = get_option_value_bool("UCI_Chess960"); - ShowCurrentLine = get_option_value_bool("UCI_ShowCurrLine"); - UseLogFile = get_option_value_bool("Use Search Log"); if (UseLogFile) LogFile.open(get_option_value_string("Search Log Filename").c_str(), std::ios::out | std::ios::app); - MinimumSplitDepth = get_option_value_int("Minimum Split Depth") * OnePly; - MaxThreadsPerSplitPoint = get_option_value_int("Maximum Number of Threads per Split Point"); - read_weights(pos.side_to_move()); // Set the number of active threads @@ -434,18 +437,11 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move, { TM.set_active_threads(newActiveThreads); init_eval(TM.active_threads()); - // HACK: init_eval() destroys the static castleRightsMask[] array in the - // Position class. The below line repairs the damage. - Position p(pos.to_fen()); - assert(pos.is_ok()); } // Wake up sleeping threads TM.wake_sleeping_threads(); - for (int i = 1; i < TM.active_threads(); i++) - assert(TM.thread_is_available(i, 0)); - // Set thinking time int myTime = time[side_to_move]; int myIncrement = increment[side_to_move]; @@ -478,14 +474,15 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move, } } - if (PonderingEnabled) + if (get_option_value_bool("Ponder")) { MaxSearchTime += MaxSearchTime / 4; MaxSearchTime = Min(MaxSearchTime, AbsoluteMaxSearchTime); } } - // Set best NodesBetweenPolls interval + // Set best NodesBetweenPolls interval to avoid lagging under + // heavy time pressure. if (MaxNodes) NodesBetweenPolls = Min(MaxNodes, 30000); else if (myTime && myTime < 1000) @@ -495,7 +492,7 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move, else NodesBetweenPolls = 30000; - // Write information to search log file + // Write search information to log file if (UseLogFile) LogFile << "Searching: " << pos.to_fen() << endl << "infinite: " << infinite @@ -504,7 +501,7 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move, << " increment: " << myIncrement << " moves to go: " << movesToGo << endl; - // LSN filtering. Used only for developing purpose. Disabled by default. + // LSN filtering. Used only for developing purposes, disabled by default if ( UseLSNFiltering && loseOnTime) { @@ -559,10 +556,11 @@ void init_search() { } // Init futility margins array - for (int i = 0; i < 14; i++) // i == depth (OnePly = 2) + for (int i = 0; i < 16; i++) // i == depth (OnePly = 2) for (int j = 0; j < 64; j++) // j == moveNumber { - FutilityMarginsMatrix[i][j] = (i < 2 ? 0 : 112 * bitScanReverse32(i * i / 2)) - 8 * j; // FIXME: test using log instead of BSR + // FIXME: test using log instead of BSR + FutilityMarginsMatrix[i][j] = (i < 2 ? 0 : 112 * bitScanReverse32(i * i / 2)) - 8 * j; } // Init futility move count array @@ -599,8 +597,10 @@ namespace { Position p(pos); SearchStack ss[PLY_MAX_PLUS_2]; + Move EasyMove = MOVE_NONE; + Value value, alpha = -VALUE_INFINITE, beta = VALUE_INFINITE; - // searchMoves are verified, copied, scored and sorted + // Moves to search are verified, copied, scored and sorted RootMoveList rml(p, searchMoves); // Handle special case of searching on a mate/stale position @@ -609,12 +609,13 @@ namespace { if (PonderSearch) wait_for_stop_or_ponderhit(); - return pos.is_check()? -VALUE_MATE : VALUE_DRAW; + return pos.is_check() ? -VALUE_MATE : VALUE_DRAW; } - // Print RootMoveList c'tor startup scoring to the standard output, - // so that we print information also for iteration 1. - cout << "info depth " << 1 << "\ninfo depth " << 1 + // Print RootMoveList startup scoring to the standard output, + // so to output information also for iteration 1. + cout << "info depth " << 1 + << "\ninfo depth " << 1 << " score " << value_to_string(rml.get_move_score(0)) << " time " << current_search_time() << " nodes " << TM.nodes_searched() @@ -629,7 +630,6 @@ namespace { Iteration = 1; // Is one move significantly better than others after initial scoring ? - Move EasyMove = MOVE_NONE; if ( rml.move_count() == 1 || rml.get_move_score(0) > rml.get_move_score(1) + EasyMoveMargin) EasyMove = rml.get_move(0); @@ -638,17 +638,12 @@ namespace { while (Iteration < PLY_MAX) { // Initialize iteration - rml.sort(); Iteration++; BestMoveChangesByIteration[Iteration] = 0; - if (Iteration <= 5) - ExtraSearchTime = 0; cout << "info depth " << Iteration << endl; - // Calculate dynamic search window based on previous iterations - Value alpha, beta; - + // Calculate dynamic aspiration window based on previous iterations if (MultiPV == 1 && Iteration >= 6 && abs(ValueByIteration[Iteration - 1]) < VALUE_KNOWN_WIN) { int prevDelta1 = ValueByIteration[Iteration - 1] - ValueByIteration[Iteration - 2]; @@ -660,14 +655,9 @@ namespace { alpha = Max(ValueByIteration[Iteration - 1] - AspirationDelta, -VALUE_INFINITE); beta = Min(ValueByIteration[Iteration - 1] + AspirationDelta, VALUE_INFINITE); } - else - { - alpha = - VALUE_INFINITE; - beta = VALUE_INFINITE; - } - // Search to the current depth - Value value = root_search(p, ss, rml, alpha, beta); + // Search to the current depth, rml is updated and sorted, alpha and beta could change + value = root_search(p, ss, rml, &alpha, &beta); // Write PV to transposition table, in case the relevant entries have // been overwritten during the search. @@ -679,7 +669,7 @@ namespace { //Save info about search result ValueByIteration[Iteration] = value; - // Drop the easy move if it differs from the new best move + // Drop the easy move if differs from the new best move if (ss[0].pv[0] != EasyMove) EasyMove = MOVE_NONE; @@ -699,7 +689,7 @@ namespace { && abs(ValueByIteration[Iteration-1]) >= abs(VALUE_MATE) - 100) stopSearch = true; - // Stop search early if one move seems to be much better than the rest + // Stop search early if one move seems to be much better than the others int64_t nodes = TM.nodes_searched(); if ( Iteration >= 8 && EasyMove == ss[0].pv[0] @@ -722,10 +712,10 @@ namespace { if (stopSearch) { - if (!PonderSearch) - break; - else + if (PonderSearch) StopOnPonderhit = true; + else + break; } } @@ -733,8 +723,6 @@ namespace { break; } - rml.sort(); - // If we are pondering or in infinite search, we shouldn't print the // best move before we are told to do so. if (!AbortSearch && (PonderSearch || InfiniteSearch)) @@ -752,7 +740,11 @@ namespace { ss[0].pv[0] = rml.get_move(0); ss[0].pv[1] = MOVE_NONE; } + + assert(ss[0].pv[0] != MOVE_NONE); + cout << "bestmove " << ss[0].pv[0]; + if (ss[0].pv[1] != MOVE_NONE) cout << " ponder " << ss[0].pv[1]; @@ -772,7 +764,9 @@ namespace { StateInfo st; p.do_move(ss[0].pv[0], st); - LogFile << "\nPonder move: " << move_to_san(p, ss[0].pv[1]) << endl; + LogFile << "\nPonder move: " + << move_to_san(p, ss[0].pv[1]) // Works also with MOVE_NONE + << endl; } return rml.get_move_score(0); } @@ -780,41 +774,56 @@ namespace { // root_search() is the function which searches the root node. It is // similar to search_pv except that it uses a different move ordering - // scheme and prints some information to the standard output. + // scheme, prints some information to the standard output and handles + // the fail low/high loops. - Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value& oldAlpha, Value& beta) { + Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value* alphaPtr, Value* betaPtr) { + EvalInfo ei; + StateInfo st; + CheckInfo ci(pos); int64_t nodes; Move move; - StateInfo st; Depth depth, ext, newDepth; - Value value; - CheckInfo ci(pos); - int researchCount = 0; - bool moveIsCheck, captureOrPromotion, dangerous; - Value alpha = oldAlpha; - bool isCheck = pos.is_check(); + Value value, alpha, beta; + bool isCheck, moveIsCheck, captureOrPromotion, dangerous; + int researchCountFH, researchCountFL; - // Evaluate the position statically - EvalInfo ei; - ss[0].eval = !isCheck ? evaluate(pos, ei, 0) : VALUE_NONE; + researchCountFH = researchCountFL = 0; + alpha = *alphaPtr; + beta = *betaPtr; + isCheck = pos.is_check(); - while (1) // Fail low loop + // Step 1. Initialize node and poll (omitted at root, but I can see no good reason for this, FIXME) + // Step 2. Check for aborted search (omitted at root, because we do not initialize root node) + // Step 3. Mate distance pruning (omitted at root) + // Step 4. Transposition table lookup (omitted at root) + + // Step 5. Evaluate the position statically + // At root we do this only to get reference value for child nodes + if (!isCheck) + ss[0].eval = evaluate(pos, ei, 0); + else + ss[0].eval = VALUE_NONE; // HACK because we do not initialize root node + + // Step 6. Razoring (omitted at root) + // Step 7. Static null move pruning (omitted at root) + // Step 8. Null move search with verification search (omitted at root) + // Step 9. Internal iterative deepening (omitted at root) + + // Step extra. Fail low loop + // We start with small aspiration window and in case of fail low, we research + // with bigger window until we are not failing low anymore. + while (1) { + // Sort the moves before to (re)search + rml.sort(); - // Loop through all the moves in the root move list + // Step 10. Loop through all moves in the root move list for (int i = 0; i < rml.move_count() && !AbortSearch; i++) { - if (alpha >= beta) - { - // We failed high, invalidate and skip next moves, leave node-counters - // and beta-counters as they are and quickly return, we will try to do - // a research at the next iteration with a bigger aspiration window. - rml.set_move_score(i, -VALUE_INFINITE); - continue; - } - - RootMoveNumber = i + 1; + // This is used by time management + FirstRootMove = (i == 0); // Save the current node count before the move is searched nodes = TM.nodes_searched(); @@ -828,100 +837,94 @@ namespace { if (current_search_time() >= 1000) cout << "info currmove " << move - << " currmovenumber " << RootMoveNumber << endl; + << " currmovenumber " << i + 1 << endl; - // Decide search depth for this move moveIsCheck = pos.move_is_check(move); captureOrPromotion = pos.move_is_capture_or_promotion(move); + + // Step 11. Decide the new search depth depth = (Iteration - 2) * OnePly + InitialDepth; ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, false, false, &dangerous); newDepth = depth + ext; + // Step 12. Futility pruning (omitted at root) + + // Step extra. Fail high loop + // If move fails high, we research with bigger window until we are not failing + // high anymore. value = - VALUE_INFINITE; - while (1) // Fail high loop + while (1) { - - // Make the move, and search it + // Step 13. Make the move pos.do_move(move, st, ci, moveIsCheck); + // Step extra. pv search + // We do pv search for first moves (i < MultiPV) + // and for fail high research (value > alpha) if (i < MultiPV || value > alpha) { // Aspiration window is disabled in multi-pv case if (MultiPV > 1) alpha = -VALUE_INFINITE; + // Full depth PV search, done on first move or after a fail high value = -search_pv(pos, ss, -beta, -alpha, newDepth, 1, 0); } else { - // Try to reduce non-pv search depth by one ply if move seems not problematic, - // if the move fails high will be re-searched at full depth. + // Step 14. Reduced search + // if the move fails high will be re-searched at full depth bool doFullDepthSearch = true; - if ( depth >= 3*OnePly // FIXME was newDepth + if ( depth >= 3 * OnePly && !dangerous && !captureOrPromotion && !move_is_castle(move)) { - ss[0].reduction = pv_reduction(depth, RootMoveNumber - MultiPV + 1); + ss[0].reduction = pv_reduction(depth, i - MultiPV + 2); if (ss[0].reduction) { + // Reduced depth non-pv search using alpha as upperbound value = -search(pos, ss, -alpha, newDepth-ss[0].reduction, 1, true, 0); doFullDepthSearch = (value > alpha); } } + // Step 15. Full depth search if (doFullDepthSearch) { + // Full depth non-pv search using alpha as upperbound ss[0].reduction = Depth(0); value = -search(pos, ss, -alpha, newDepth, 1, true, 0); + // If we are above alpha then research at same depth but as PV + // to get a correct score or eventually a fail high above beta. if (value > alpha) value = -search_pv(pos, ss, -beta, -alpha, newDepth, 1, 0); } } + // Step 16. Undo move pos.undo_move(move); // Can we exit fail high loop ? if (AbortSearch || value < beta) break; - // We are failing high and going to do a research. It's important to update score - // before research in case we run out of time while researching. + // We are failing high and going to do a research. It's important to update + // the score before research in case we run out of time while researching. rml.set_move_score(i, value); update_pv(ss, 0); TT.extract_pv(pos, ss[0].pv, PLY_MAX); rml.set_move_pv(i, ss[0].pv); - // Print search information to the standard output - cout << "info depth " << Iteration - << " score " << value_to_string(value) - << ((value >= beta) ? " lowerbound" : - ((value <= alpha)? " upperbound" : "")) - << " time " << current_search_time() - << " nodes " << TM.nodes_searched() - << " nps " << nps() - << " pv "; - - for (int j = 0; ss[0].pv[j] != MOVE_NONE && j < PLY_MAX; j++) - cout << ss[0].pv[j] << " "; - - cout << endl; - - if (UseLogFile) - { - ValueType type = (value >= beta ? VALUE_TYPE_LOWER - : (value <= alpha ? VALUE_TYPE_UPPER : VALUE_TYPE_EXACT)); - - LogFile << pretty_pv(pos, current_search_time(), Iteration, - TM.nodes_searched(), value, type, ss[0].pv) << endl; - } + // Print information to the standard output + print_pv_info(pos, ss, alpha, beta, value); // Prepare for a research after a fail high, each time with a wider window - researchCount++; - beta = Min(beta + AspirationDelta * (1 << researchCount), VALUE_INFINITE); + *betaPtr = beta = Min(beta + AspirationDelta * (1 << researchCountFH), VALUE_INFINITE); + researchCountFH++; } // End of fail high loop @@ -934,14 +937,16 @@ namespace { break; // Remember beta-cutoff and searched nodes counts for this move. The - // info is used to sort the root moves at the next iteration. + // info is used to sort the root moves for the next iteration. int64_t our, their; TM.get_beta_counters(pos.side_to_move(), our, their); rml.set_beta_counters(i, our, their); rml.set_move_nodes(i, TM.nodes_searched() - nodes); assert(value >= -VALUE_INFINITE && value <= VALUE_INFINITE); + assert(value < beta); + // Step 17. Check for new best move if (value <= alpha && i >= MultiPV) rml.set_move_score(i, -VALUE_INFINITE); else @@ -962,29 +967,10 @@ namespace { if (i > 0) BestMoveChangesByIteration[Iteration]++; - // Print search information to the standard output - cout << "info depth " << Iteration - << " score " << value_to_string(value) - << ((value >= beta) ? " lowerbound" : - ((value <= alpha)? " upperbound" : "")) - << " time " << current_search_time() - << " nodes " << TM.nodes_searched() - << " nps " << nps() - << " pv "; - - for (int j = 0; ss[0].pv[j] != MOVE_NONE && j < PLY_MAX; j++) - cout << ss[0].pv[j] << " "; + // Print information to the standard output + print_pv_info(pos, ss, alpha, beta, value); - cout << endl; - - if (UseLogFile) - { - ValueType type = (value >= beta ? VALUE_TYPE_LOWER - : (value <= alpha ? VALUE_TYPE_UPPER : VALUE_TYPE_EXACT)); - - LogFile << pretty_pv(pos, current_search_time(), Iteration, - TM.nodes_searched(), value, type, ss[0].pv) << endl; - } + // Raise alpha to setup proper non-pv search upper bound if (value > alpha) alpha = value; } @@ -995,7 +981,7 @@ namespace { { cout << "info multipv " << j + 1 << " score " << value_to_string(rml.get_move_score(j)) - << " depth " << ((j <= i)? Iteration : Iteration - 1) + << " depth " << (j <= i ? Iteration : Iteration - 1) << " time " << current_search_time() << " nodes " << TM.nodes_searched() << " nps " << nps() @@ -1006,29 +992,31 @@ namespace { cout << endl; } - alpha = rml.get_move_score(Min(i, MultiPV-1)); + alpha = rml.get_move_score(Min(i, MultiPV - 1)); } } // PV move or new best move - assert(alpha >= oldAlpha); + assert(alpha >= *alphaPtr); - AspirationFailLow = (alpha == oldAlpha); + AspirationFailLow = (alpha == *alphaPtr); if (AspirationFailLow && StopOnPonderhit) StopOnPonderhit = false; } // Can we exit fail low loop ? - if (AbortSearch || alpha > oldAlpha) + if (AbortSearch || !AspirationFailLow) break; // Prepare for a research after a fail low, each time with a wider window - researchCount++; - alpha = Max(alpha - AspirationDelta * (1 << researchCount), -VALUE_INFINITE); - oldAlpha = alpha; + *alphaPtr = alpha = Max(alpha - AspirationDelta * (1 << researchCountFL), -VALUE_INFINITE); + researchCountFL++; } // Fail low loop + // Sort the moves before to return + rml.sort(); + return alpha; } @@ -1044,76 +1032,78 @@ namespace { assert(threadID >= 0 && threadID < TM.active_threads()); Move movesSearched[256]; + EvalInfo ei; StateInfo st; const TTEntry* tte; Move ttMove, move; Depth ext, newDepth; - Value oldAlpha, value; - bool isCheck, mateThreat, singleEvasion, moveIsCheck, captureOrPromotion, dangerous; + Value bestValue, value, oldAlpha; + bool isCheck, singleEvasion, moveIsCheck, captureOrPromotion, dangerous; + bool mateThreat = false; int moveCount = 0; - Value bestValue = value = -VALUE_INFINITE; + bestValue = value = -VALUE_INFINITE; if (depth < OnePly) return qsearch(pos, ss, alpha, beta, Depth(0), ply, threadID); - // Initialize, and make an early exit in case of an aborted search, - // an instant draw, maximum ply reached, etc. + // Step 1. Initialize node and poll + // Polling can abort search. init_node(ss, ply, threadID); - // After init_node() that calls poll() + // Step 2. Check for aborted search and immediate draw if (AbortSearch || TM.thread_should_stop(threadID)) return Value(0); if (pos.is_draw() || ply >= PLY_MAX - 1) return VALUE_DRAW; - // Mate distance pruning + // Step 3. Mate distance pruning oldAlpha = alpha; alpha = Max(value_mated_in(ply), alpha); beta = Min(value_mate_in(ply+1), beta); if (alpha >= beta) return alpha; - // Transposition table lookup. At PV nodes, we don't use the TT for - // pruning, but only for move ordering. This is to avoid problems in - // the following areas: + // Step 4. Transposition table lookup + // At PV nodes, we don't use the TT for pruning, but only for move ordering. + // This is to avoid problems in the following areas: // // * Repetition draw detection // * Fifty move rule detection // * Searching for a mate // * Printing of full PV line - // tte = TT.retrieve(pos.get_key()); ttMove = (tte ? tte->move() : MOVE_NONE); - // Go with internal iterative deepening if we don't have a TT move - if ( UseIIDAtPVNodes - && depth >= 5*OnePly - && ttMove == MOVE_NONE) - { - search_pv(pos, ss, alpha, beta, depth-2*OnePly, ply, threadID); - ttMove = ss[ply].pv[ply]; - tte = TT.retrieve(pos.get_key()); - } - + // Step 5. Evaluate the position statically + // At PV nodes we do this only to update gain statistics isCheck = pos.is_check(); if (!isCheck) { - // Update gain statistics of the previous move that lead - // us in this position. - EvalInfo ei; ss[ply].eval = evaluate(pos, ei, threadID); update_gains(pos, ss[ply - 1].currentMove, ss[ply - 1].eval, ss[ply].eval); } - // Initialize a MovePicker object for the current position, and prepare - // to search all moves + // Step 6. Razoring (is omitted in PV nodes) + // Step 7. Static null move pruning (is omitted in PV nodes) + // Step 8. Null move search with verification search (is omitted in PV nodes) + + // Step 9. Internal iterative deepening + if ( depth >= IIDDepthAtPVNodes + && ttMove == MOVE_NONE) + { + search_pv(pos, ss, alpha, beta, depth-2*OnePly, ply, threadID); + ttMove = ss[ply].pv[ply]; + tte = TT.retrieve(pos.get_key()); + } + + // Initialize a MovePicker object for the current position mateThreat = pos.has_mate_threat(opposite_color(pos.side_to_move())); - CheckInfo ci(pos); MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply]); + CheckInfo ci(pos); - // Loop through all legal moves until no moves remain or a beta cutoff - // occurs. + // Step 10. Loop through moves + // Loop through all legal moves until no moves remain or a beta cutoff occurs while ( alpha < beta && (move = mp.get_next_move()) != MOVE_NONE && !TM.thread_should_stop(threadID)) @@ -1124,13 +1114,13 @@ namespace { moveIsCheck = pos.move_is_check(move, ci); captureOrPromotion = pos.move_is_capture_or_promotion(move); - // Decide the new search depth + // Step 11. Decide the new search depth ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, singleEvasion, mateThreat, &dangerous); // Singular extension search. We extend the TT move if its value is much better than // its siblings. To verify this we do a reduced search on all the other moves but the // ttMove, if result is lower then ttValue minus a margin then we extend ttMove. - if ( depth >= 6 * OnePly + if ( depth >= SingularExtensionDepthAtPVNodes && tte && move == tte->move() && ext < OnePly @@ -1141,30 +1131,34 @@ namespace { if (abs(ttValue) < VALUE_KNOWN_WIN) { - Value excValue = search(pos, ss, ttValue - SingleReplyMargin, depth / 2, ply, false, threadID, move); + Value excValue = search(pos, ss, ttValue - SingularExtensionMargin, depth / 2, ply, false, threadID, move); - if (excValue < ttValue - SingleReplyMargin) + if (excValue < ttValue - SingularExtensionMargin) ext = OnePly; } } newDepth = depth - OnePly + ext; - // Update current move + // Update current move (this must be done after singular extension search) movesSearched[moveCount++] = ss[ply].currentMove = move; - // Make and search the move + // Step 12. Futility pruning (is omitted in PV nodes) + + // Step 13. Make the move pos.do_move(move, st, ci, moveIsCheck); - if (moveCount == 1) // The first move in list is the PV + // Step extra. pv search (only in PV nodes) + // The first move in list is the expected PV + if (moveCount == 1) value = -search_pv(pos, ss, -beta, -alpha, newDepth, ply+1, threadID); else { - // Try to reduce non-pv search depth by one ply if move seems not problematic, + // Step 14. Reduced search // if the move fails high will be re-searched at full depth. bool doFullDepthSearch = true; - if ( depth >= 3*OnePly + if ( depth >= 3 * OnePly && !dangerous && !captureOrPromotion && !move_is_castle(move) @@ -1178,19 +1172,24 @@ namespace { } } - if (doFullDepthSearch) // Go with full depth non-pv search + // Step 15. Full depth search + if (doFullDepthSearch) { ss[ply].reduction = Depth(0); value = -search(pos, ss, -alpha, newDepth, ply+1, true, threadID); + + // Step extra. pv search (only in PV nodes) if (value > alpha && value < beta) value = -search_pv(pos, ss, -beta, -alpha, newDepth, ply+1, threadID); } } + + // Step 16. Undo move pos.undo_move(move); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); - // New best move? + // Step 17. Check for new best move if (value > bestValue) { bestValue = value; @@ -1203,24 +1202,26 @@ namespace { } } - // Split? + // Step 18. Check for split if ( TM.active_threads() > 1 && bestValue < beta && depth >= MinimumSplitDepth && Iteration <= 99 - && TM.idle_thread_exists(threadID) + && TM.available_thread_exists(threadID) && !AbortSearch && !TM.thread_should_stop(threadID) - && TM.split(pos, ss, ply, &alpha, &beta, &bestValue, VALUE_NONE, - depth, &moveCount, &mp, threadID, true)) + && TM.split(pos, ss, ply, &alpha, beta, &bestValue, + depth, mateThreat, &moveCount, &mp, threadID, true)) break; } - // All legal moves have been searched. A special case: If there were + // Step 19. Check for mate and stalemate + // All legal moves have been searched and if there were // no legal moves, it must be mate or stalemate. if (moveCount == 0) return (isCheck ? value_mated_in(ply) : VALUE_DRAW); + // Step 20. Update tables // If the search is not aborted, update the transposition table, // history counters, and killer moves. if (AbortSearch || TM.thread_should_stop(threadID)) @@ -1262,104 +1263,134 @@ namespace { const TTEntry* tte; Move ttMove, move; Depth ext, newDepth; - Value bestValue, staticValue, nullValue, value, futilityValue, futilityValueScaled; + Value bestValue, refinedValue, nullValue, value, futilityValueScaled; bool isCheck, singleEvasion, moveIsCheck, captureOrPromotion, dangerous; bool mateThreat = false; int moveCount = 0; - futilityValue = staticValue = bestValue = value = -VALUE_INFINITE; + refinedValue = bestValue = value = -VALUE_INFINITE; if (depth < OnePly) return qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID); - // Initialize, and make an early exit in case of an aborted search, - // an instant draw, maximum ply reached, etc. + // Step 1. Initialize node and poll + // Polling can abort search. init_node(ss, ply, threadID); - // After init_node() that calls poll() + // Step 2. Check for aborted search and immediate draw if (AbortSearch || TM.thread_should_stop(threadID)) return Value(0); if (pos.is_draw() || ply >= PLY_MAX - 1) return VALUE_DRAW; - // Mate distance pruning + // Step 3. Mate distance pruning if (value_mated_in(ply) >= beta) return beta; if (value_mate_in(ply + 1) < beta) return beta - 1; + // 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 exsists. + // TT value, so we use a different position key in case of an excluded move exists. Key posKey = excludedMove ? pos.get_exclusion_key() : pos.get_key(); - // Transposition table lookup tte = TT.retrieve(posKey); ttMove = (tte ? tte->move() : MOVE_NONE); - if (tte && ok_to_use_TT(tte, depth, beta, ply)) + if (tte && ok_to_use_TT(tte, depth, beta, ply, allowNullmove)) { ss[ply].currentMove = ttMove; // Can be MOVE_NONE return value_from_tt(tte->value(), ply); } + // Step 5. Evaluate the position statically isCheck = pos.is_check(); - // Evaluate the position statically if (!isCheck) { if (tte && (tte->type() & VALUE_TYPE_EVAL)) - staticValue = value_from_tt(tte->value(), ply); + ss[ply].eval = value_from_tt(tte->value(), ply); else - staticValue = evaluate(pos, ei, threadID); + ss[ply].eval = evaluate(pos, ei, threadID); - ss[ply].eval = staticValue; - futilityValue = staticValue + futility_margin(depth, 0); //FIXME: Remove me, only for split - staticValue = refine_eval(tte, staticValue, ply); // Enhance accuracy with TT value if possible + refinedValue = refine_eval(tte, ss[ply].eval, ply); // Enhance accuracy with TT value if possible update_gains(pos, ss[ply - 1].currentMove, ss[ply - 1].eval, ss[ply].eval); } - // Static null move pruning. We're betting that the opponent doesn't have - // a move that will reduce the score by more than FutilityMargins[int(depth)] - // if we do a null move. - if ( !isCheck - && allowNullmove - && depth < RazorDepth - && staticValue - futility_margin(depth, 0) >= beta) - return staticValue - futility_margin(depth, 0); + // Step 6. Razoring + if ( refinedValue < beta - razor_margin(depth) + && ttMove == MOVE_NONE + && ss[ply - 1].currentMove != MOVE_NULL + && depth < RazorDepth + && !isCheck + && !value_is_mate(beta) + && !pos.has_pawn_on_7th(pos.side_to_move())) + { + Value rbeta = beta - razor_margin(depth); + Value v = qsearch(pos, ss, rbeta-1, rbeta, Depth(0), ply, threadID); + if (v < rbeta) + // Logically we should return (v + razor_margin(depth)), but + // surprisingly this did slightly weaker in tests. + return v; + } - // Null move search + // Step 7. Static null move pruning + // We're betting that the opponent doesn't have a move that will reduce + // the score by more than futility_margin(depth) if we do a null move. + if ( allowNullmove + && depth < RazorDepth + && !isCheck + && !value_is_mate(beta) + && ok_to_do_nullmove(pos) + && refinedValue >= beta + futility_margin(depth, 0)) + return refinedValue - futility_margin(depth, 0); + + // Step 8. Null move search with verification search + // When we jump directly to qsearch() we do a null move only if static value is + // at least beta. Otherwise we do a null move if static value is not more than + // NullMoveMargin under beta. if ( allowNullmove && depth > OnePly && !isCheck && !value_is_mate(beta) && ok_to_do_nullmove(pos) - && staticValue >= beta - (depth >= 4 * OnePly ? NullMoveMargin : 0)) + && refinedValue >= beta - (depth >= 4 * OnePly ? NullMoveMargin : 0)) { ss[ply].currentMove = MOVE_NULL; - pos.do_null_move(st); - // Null move dynamic reduction based on depth int R = 3 + (depth >= 5 * OnePly ? depth / 8 : 0); // Null move dynamic reduction based on value - if (staticValue - beta > PawnValueMidgame) + if (refinedValue - beta > PawnValueMidgame) R++; + pos.do_null_move(st); + nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID); pos.undo_null_move(); if (nullValue >= beta) { - if (depth < 6 * OnePly) - return beta; + // Do not return unproven mate scores + if (nullValue >= value_mate_in(PLY_MAX)) + nullValue = beta; + + // Do zugzwang verification search for high depths, don't store in TT + // if search was stopped. + if ( ( depth < 6 * OnePly + || search(pos, ss, beta, depth-5*OnePly, ply, false, threadID) >= beta) + && !AbortSearch + && !TM.thread_should_stop(threadID)) + { + assert(value_to_tt(nullValue, ply) == nullValue); - // Do zugzwang verification search - Value v = search(pos, ss, beta, depth-5*OnePly, ply, false, threadID); - if (v >= beta) - return beta; + TT.store(posKey, nullValue, VALUE_TYPE_NS_LO, depth, MOVE_NONE); + return nullValue; + } } else { // The null move failed low, which means that we may be faced with // some kind of threat. If the previous move was reduced, check if @@ -1377,35 +1408,23 @@ namespace { return beta - 1; } } - // Null move search not allowed, try razoring - else if ( !value_is_mate(beta) - && !isCheck - && depth < RazorDepth - && staticValue < beta - (NullMoveMargin + 16 * depth) - && ss[ply - 1].currentMove != MOVE_NULL - && ttMove == MOVE_NONE - && !pos.has_pawn_on_7th(pos.side_to_move())) - { - Value rbeta = beta - (NullMoveMargin + 16 * depth); - Value v = qsearch(pos, ss, rbeta-1, rbeta, Depth(0), ply, threadID); - if (v < rbeta) - return v; - } - // Go with internal iterative deepening if we don't have a TT move - if (UseIIDAtNonPVNodes && ttMove == MOVE_NONE && depth >= 8*OnePly && - !isCheck && ss[ply].eval >= beta - IIDMargin) + // Step 9. Internal iterative deepening + if ( depth >= IIDDepthAtNonPVNodes + && ttMove == MOVE_NONE + && !isCheck + && ss[ply].eval >= beta - IIDMargin) { - search(pos, ss, beta, Min(depth/2, depth-2*OnePly), ply, false, threadID); + search(pos, ss, beta, depth/2, ply, false, threadID); ttMove = ss[ply].pv[ply]; tte = TT.retrieve(posKey); } - // Initialize a MovePicker object for the current position, and prepare - // to search all moves. - MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply]); + // Initialize a MovePicker object for the current position + MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply], beta); CheckInfo ci(pos); + // Step 10. Loop through moves // Loop through all legal moves until no moves remain or a beta cutoff occurs while ( bestValue < beta && (move = mp.get_next_move()) != MOVE_NONE @@ -1420,16 +1439,16 @@ namespace { singleEvasion = (isCheck && mp.number_of_evasions() == 1); captureOrPromotion = pos.move_is_capture_or_promotion(move); - // Decide the new search depth + // Step 11. Decide the new search depth ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, singleEvasion, mateThreat, &dangerous); // Singular extension search. We extend the TT move if its value is much better than // its siblings. To verify this we do a reduced search on all the other moves but the // ttMove, if result is lower then ttValue minus a margin then we extend ttMove. - if ( depth >= 8 * OnePly + if ( depth >= SingularExtensionDepthAtNonPVNodes && tte && move == tte->move() - && !excludedMove // Do not allow recursive single-reply search + && !excludedMove // Do not allow recursive singular extension search && ext < OnePly && is_lower_bound(tte->type()) && tte->depth() >= depth - 3 * OnePly) @@ -1438,19 +1457,19 @@ namespace { if (abs(ttValue) < VALUE_KNOWN_WIN) { - Value excValue = search(pos, ss, ttValue - SingleReplyMargin, depth / 2, ply, false, threadID, move); + Value excValue = search(pos, ss, ttValue - SingularExtensionMargin, depth / 2, ply, false, threadID, move); - if (excValue < ttValue - SingleReplyMargin) + if (excValue < ttValue - SingularExtensionMargin) ext = OnePly; } } newDepth = depth - OnePly + ext; - // Update current move + // Update current move (this must be done after singular extension search) movesSearched[moveCount++] = ss[ply].currentMove = move; - // Futility pruning + // Step 12. Futility pruning if ( !isCheck && !dangerous && !captureOrPromotion @@ -1464,7 +1483,7 @@ namespace { continue; // Value based pruning - Depth predictedDepth = newDepth - nonpv_reduction(depth, moveCount); //FIXME: We are ignoring condition: depth >= 3*OnePly, BUG?? + Depth predictedDepth = newDepth - nonpv_reduction(depth, moveCount); // We illogically ignore reduction condition depth >= 3*OnePly futilityValueScaled = ss[ply].eval + futility_margin(predictedDepth, moveCount) + H.gain(pos.piece_on(move_from(move)), move_to(move)) + 45; @@ -1476,11 +1495,11 @@ namespace { } } - // Make and search the move + // Step 13. Make the move pos.do_move(move, st, ci, moveIsCheck); - // Try to reduce non-pv search depth by one ply if move seems not problematic, - // if the move fails high will be re-searched at full depth. + // Step 14. Reduced search, if the move fails high + // will be re-searched at full depth. bool doFullDepthSearch = true; if ( depth >= 3*OnePly @@ -1497,16 +1516,19 @@ namespace { } } - if (doFullDepthSearch) // Go with full depth non-pv search + // Step 15. Full depth search + if (doFullDepthSearch) { ss[ply].reduction = Depth(0); value = -search(pos, ss, -(beta-1), newDepth, ply+1, true, threadID); } + + // Step 16. Undo move pos.undo_move(move); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); - // New best move? + // Step 17. Check for new best move if (value > bestValue) { bestValue = value; @@ -1517,24 +1539,27 @@ namespace { ss[ply].mateKiller = move; } - // Split? + // Step 18. Check for split if ( TM.active_threads() > 1 && bestValue < beta && depth >= MinimumSplitDepth && Iteration <= 99 - && TM.idle_thread_exists(threadID) + && TM.available_thread_exists(threadID) && !AbortSearch && !TM.thread_should_stop(threadID) - && TM.split(pos, ss, ply, &beta, &beta, &bestValue, futilityValue, //FIXME: SMP & futilityValue - depth, &moveCount, &mp, threadID, false)) + && TM.split(pos, ss, ply, NULL, beta, &bestValue, + depth, mateThreat, &moveCount, &mp, threadID, false)) break; } - // All legal moves have been searched. A special case: If there were + // Step 19. Check for mate and stalemate + // All legal moves have been searched and if there are // no legal moves, it must be mate or stalemate. + // If one move was excluded return fail low score. if (!moveCount) - return excludedMove ? beta - 1 : (pos.is_check() ? value_mated_in(ply) : VALUE_DRAW); + return excludedMove ? beta - 1 : (isCheck ? value_mated_in(ply) : VALUE_DRAW); + // Step 20. Update tables // If the search is not aborted, update the transposition table, // history counters, and killer moves. if (AbortSearch || TM.thread_should_stop(threadID)) @@ -1600,7 +1625,7 @@ namespace { tte = TT.retrieve(pos.get_key()); ttMove = (tte ? tte->move() : MOVE_NONE); - if (!pvNode && tte && ok_to_use_TT(tte, depth, beta, ply)) + if (!pvNode && tte && ok_to_use_TT(tte, depth, beta, ply, true)) { assert(tte->type() != VALUE_TYPE_EVAL); @@ -1641,7 +1666,7 @@ namespace { alpha = bestValue; // If we are near beta then try to get a cutoff pushing checks a bit further - bool deepChecks = depth == -OnePly && staticValue >= beta - PawnValueMidgame / 8; + bool deepChecks = (depth == -OnePly && staticValue >= beta - PawnValueMidgame / 8); // Initialize a MovePicker object for the current position, and prepare // to search the moves. Because the depth is <= 0 here, only captures, @@ -1652,8 +1677,7 @@ namespace { enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame; futilityBase = staticValue + FutilityMarginQS + ei.futilityMargin[pos.side_to_move()]; - // Loop through the moves until no moves remain or a beta cutoff - // occurs. + // Loop through the moves until no moves remain or a beta cutoff occurs while ( alpha < beta && (move = mp.get_next_move()) != MOVE_NONE) { @@ -1688,13 +1712,14 @@ namespace { // Detect blocking evasions that are candidate to be pruned evasionPrunable = isCheck - && bestValue != -VALUE_INFINITE + && bestValue > value_mated_in(PLY_MAX) && !pos.move_is_capture(move) && pos.type_of_piece_on(move_from(move)) != KING && !pos.can_castle(pos.side_to_move()); // Don't search moves with negative SEE values if ( (!isCheck || evasionPrunable) + && !pvNode && move != ttMove && !move_is_promotion(move) && pos.see_sign(move) < 0) @@ -1721,7 +1746,7 @@ namespace { // All legal moves have been searched. A special case: If we're in check // and no legal moves were found, it is checkmate. - if (!moveCount && pos.is_check()) // Mate! + if (!moveCount && isCheck) // Mate! return value_mated_in(ply); // Update transposition table @@ -1764,18 +1789,24 @@ namespace { assert(threadID >= 0 && threadID < TM.active_threads()); assert(TM.active_threads() > 1); + StateInfo st; + Move move; + Depth ext, newDepth; + Value value, futilityValueScaled; + bool isCheck, moveIsCheck, captureOrPromotion, dangerous; + int moveCount; + value = -VALUE_INFINITE; + Position pos(*sp->pos); CheckInfo ci(pos); SearchStack* ss = sp->sstack[threadID]; - Value value = -VALUE_INFINITE; - Move move; - int moveCount; - bool isCheck = pos.is_check(); - bool useFutilityPruning = sp->depth < 7 * OnePly //FIXME: sync with search - && !isCheck; + isCheck = pos.is_check(); - while ( lock_grab_bool(&(sp->lock)) - && sp->bestValue < sp->beta + // Step 10. Loop through moves + // Loop through all legal moves until no moves remain or a beta cutoff occurs + lock_grab(&(sp->lock)); + + while ( sp->bestValue < sp->beta && !TM.thread_should_stop(threadID) && (move = sp->mp->get_next_move()) != MOVE_NONE) { @@ -1784,48 +1815,50 @@ namespace { assert(move_is_ok(move)); - bool moveIsCheck = pos.move_is_check(move, ci); - bool captureOrPromotion = pos.move_is_capture_or_promotion(move); + moveIsCheck = pos.move_is_check(move, ci); + captureOrPromotion = pos.move_is_capture_or_promotion(move); - ss[sp->ply].currentMove = move; + // Step 11. Decide the new search depth + ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, false, sp->mateThreat, &dangerous); + newDepth = sp->depth - OnePly + ext; - // Decide the new search depth - bool dangerous; - Depth ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, false, false, &dangerous); - Depth newDepth = sp->depth - OnePly + ext; + // Update current move + ss[sp->ply].currentMove = move; - // Prune? - if ( useFutilityPruning + // Step 12. Futility pruning + if ( !isCheck && !dangerous - && !captureOrPromotion) + && !captureOrPromotion + && !move_is_castle(move)) { // Move count based pruning if ( moveCount >= futility_move_count(sp->depth) && ok_to_prune(pos, move, ss[sp->ply].threatMove) && sp->bestValue > value_mated_in(PLY_MAX)) + { + lock_grab(&(sp->lock)); continue; + } // Value based pruning - Value futilityValueScaled = sp->futilityValue - moveCount * 8; //FIXME: sync with search + Depth predictedDepth = newDepth - nonpv_reduction(sp->depth, moveCount); + futilityValueScaled = ss[sp->ply].eval + futility_margin(predictedDepth, moveCount) + + H.gain(pos.piece_on(move_from(move)), move_to(move)) + 45; if (futilityValueScaled < sp->beta) { - if (futilityValueScaled > sp->bestValue) // Less then 1% of cases - { - lock_grab(&(sp->lock)); - if (futilityValueScaled > sp->bestValue) - sp->bestValue = futilityValueScaled; - lock_release(&(sp->lock)); - } + lock_grab(&(sp->lock)); + + if (futilityValueScaled > sp->bestValue) + sp->bestValue = futilityValueScaled; continue; } } - // Make and search the move. - StateInfo st; + // Step 13. Make the move pos.do_move(move, st, ci, moveIsCheck); - // Try to reduce non-pv search depth by one ply if move seems not problematic, + // Step 14. Reduced search // if the move fails high will be re-searched at full depth. bool doFullDepthSearch = true; @@ -1838,59 +1871,40 @@ namespace { if (ss[sp->ply].reduction) { value = -search(pos, ss, -(sp->beta-1), newDepth-ss[sp->ply].reduction, sp->ply+1, true, threadID); - doFullDepthSearch = (value >= sp->beta); + doFullDepthSearch = (value >= sp->beta && !TM.thread_should_stop(threadID)); } } - if (doFullDepthSearch) // Go with full depth non-pv search + // Step 15. Full depth search + if (doFullDepthSearch) { ss[sp->ply].reduction = Depth(0); value = -search(pos, ss, -(sp->beta - 1), newDepth, sp->ply+1, true, threadID); } + + // Step 16. Undo move pos.undo_move(move); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); - if (TM.thread_should_stop(threadID)) - { - lock_grab(&(sp->lock)); - break; - } + // Step 17. Check for new best move + lock_grab(&(sp->lock)); - // New best move? - if (value > sp->bestValue) // Less then 2% of cases + if (value > sp->bestValue && !TM.thread_should_stop(threadID)) { - lock_grab(&(sp->lock)); - if (value > sp->bestValue && !TM.thread_should_stop(threadID)) + sp->bestValue = value; + if (sp->bestValue >= sp->beta) { - sp->bestValue = value; - if (sp->bestValue >= sp->beta) - { - sp_update_pv(sp->parentSstack, ss, sp->ply); - for (int i = 0; i < TM.active_threads(); i++) - if (i != threadID && (i == sp->master || sp->slaves[i])) - TM.set_stop_request(i); - - sp->finished = true; - } + sp->stopRequest = true; + sp_update_pv(sp->parentSstack, ss, sp->ply); } - lock_release(&(sp->lock)); } } /* Here we have the lock still grabbed */ - // If this is the master thread and we have been asked to stop because of - // a beta cutoff higher up in the tree, stop all slave threads. Note that - // thread_should_stop(threadID) does not imply that 'stop' flag is set, so - // do this explicitly now, under lock protection. - if (sp->master == threadID && TM.thread_should_stop(threadID)) - for (int i = 0; i < TM.active_threads(); i++) - if (sp->slaves[i] || i == threadID) - TM.set_stop_request(i); - - sp->cpus--; sp->slaves[threadID] = 0; + sp->cpus--; lock_release(&(sp->lock)); } @@ -1909,15 +1923,23 @@ namespace { assert(threadID >= 0 && threadID < TM.active_threads()); assert(TM.active_threads() > 1); + StateInfo st; + Move move; + Depth ext, newDepth; + Value value; + bool moveIsCheck, captureOrPromotion, dangerous; + int moveCount; + value = -VALUE_INFINITE; + Position pos(*sp->pos); CheckInfo ci(pos); SearchStack* ss = sp->sstack[threadID]; - Value value = -VALUE_INFINITE; - int moveCount; - Move move; - while ( lock_grab_bool(&(sp->lock)) - && sp->alpha < sp->beta + // Step 10. Loop through moves + // Loop through all legal moves until no moves remain or a beta cutoff occurs + lock_grab(&(sp->lock)); + + while ( sp->alpha < sp->beta && !TM.thread_should_stop(threadID) && (move = sp->mp->get_next_move()) != MOVE_NONE) { @@ -1926,21 +1948,22 @@ namespace { assert(move_is_ok(move)); - bool moveIsCheck = pos.move_is_check(move, ci); - bool captureOrPromotion = pos.move_is_capture_or_promotion(move); + moveIsCheck = pos.move_is_check(move, ci); + captureOrPromotion = pos.move_is_capture_or_promotion(move); + // Step 11. Decide the new search depth + ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, false, sp->mateThreat, &dangerous); + newDepth = sp->depth - OnePly + ext; + + // Update current move ss[sp->ply].currentMove = move; - // Decide the new search depth - bool dangerous; - Depth ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, false, false, &dangerous); - Depth newDepth = sp->depth - OnePly + ext; + // Step 12. Futility pruning (is omitted in PV nodes) - // Make and search the move. - StateInfo st; + // Step 13. Make the move pos.do_move(move, st, ci, moveIsCheck); - // Try to reduce non-pv search depth by one ply if move seems not problematic, + // Step 14. Reduced search // if the move fails high will be re-searched at full depth. bool doFullDepthSearch = true; @@ -1954,80 +1977,57 @@ namespace { { Value localAlpha = sp->alpha; value = -search(pos, ss, -localAlpha, newDepth-ss[sp->ply].reduction, sp->ply+1, true, threadID); - doFullDepthSearch = (value > localAlpha); + doFullDepthSearch = (value > localAlpha && !TM.thread_should_stop(threadID)); } } - if (doFullDepthSearch) // Go with full depth non-pv search + // Step 15. Full depth search + if (doFullDepthSearch) { Value localAlpha = sp->alpha; ss[sp->ply].reduction = Depth(0); value = -search(pos, ss, -localAlpha, newDepth, sp->ply+1, true, threadID); - if (value > localAlpha && value < sp->beta) + if (value > localAlpha && value < sp->beta && !TM.thread_should_stop(threadID)) { // If another thread has failed high then sp->alpha has been increased // to be higher or equal then beta, if so, avoid to start a PV search. localAlpha = sp->alpha; if (localAlpha < sp->beta) value = -search_pv(pos, ss, -sp->beta, -localAlpha, newDepth, sp->ply+1, threadID); - else - assert(TM.thread_should_stop(threadID)); - } + } } + + // Step 16. Undo move pos.undo_move(move); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); - if (TM.thread_should_stop(threadID)) - { - lock_grab(&(sp->lock)); - break; - } + // Step 17. Check for new best move + lock_grab(&(sp->lock)); - // New best move? - if (value > sp->bestValue) // Less then 2% of cases + if (value > sp->bestValue && !TM.thread_should_stop(threadID)) { - lock_grab(&(sp->lock)); - if (value > sp->bestValue && !TM.thread_should_stop(threadID)) + sp->bestValue = value; + if (value > sp->alpha) { - sp->bestValue = value; - if (value > sp->alpha) - { - // Ask threads to stop before to modify sp->alpha - if (value >= sp->beta) - { - for (int i = 0; i < TM.active_threads(); i++) - if (i != threadID && (i == sp->master || sp->slaves[i])) - TM.set_stop_request(i); - - sp->finished = true; - } - - sp->alpha = value; - - sp_update_pv(sp->parentSstack, ss, sp->ply); - if (value == value_mate_in(sp->ply + 1)) - ss[sp->ply].mateKiller = move; - } + // Ask threads to stop before to modify sp->alpha + if (value >= sp->beta) + sp->stopRequest = true; + + sp->alpha = value; + + sp_update_pv(sp->parentSstack, ss, sp->ply); + if (value == value_mate_in(sp->ply + 1)) + ss[sp->ply].mateKiller = move; } - lock_release(&(sp->lock)); } } /* Here we have the lock still grabbed */ - // If this is the master thread and we have been asked to stop because of - // a beta cutoff higher up in the tree, stop all slave threads. Note that - // thread_should_stop(threadID) does not imply that 'stop' flag is set, so - // do this explicitly now, under lock protection. - if (sp->master == threadID && TM.thread_should_stop(threadID)) - for (int i = 0; i < TM.active_threads(); i++) - if (sp->slaves[i] || i == threadID) - TM.set_stop_request(i); - - sp->cpus--; sp->slaves[threadID] = 0; + sp->cpus--; lock_release(&(sp->lock)); } @@ -2057,7 +2057,6 @@ namespace { } ss[ply].init(ply); ss[ply + 2].initKillers(); - TM.print_current_line(ss, ply, threadID); } @@ -2307,14 +2306,18 @@ namespace { } - // ok_to_use_TT() returns true if a transposition table score - // can be used at a given point in search. + // ok_to_use_TT() returns true if a transposition table score can be used at a + // given point in search. To avoid zugzwang issues TT cutoffs at the root node + // of a null move verification search are not allowed if the TT value was found + // by a null search, this is implemented testing allowNullmove and TT entry type. - bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply) { + bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply, bool allowNullmove) { Value v = value_from_tt(tte->value(), ply); - return ( tte->depth() >= depth + return (allowNullmove || !(tte->type() & VALUE_TYPE_NULL)) + + && ( tte->depth() >= depth || v >= Max(value_mate_in(PLY_MAX), beta) || v < Min(value_mated_in(PLY_MAX), beta)) @@ -2457,7 +2460,6 @@ namespace { else if (t - lastInfoTime >= 1000) { lastInfoTime = t; - lock_grab(&TM.IOLock); if (dbg_show_mean) dbg_print_mean(); @@ -2467,18 +2469,13 @@ namespace { cout << "info nodes " << TM.nodes_searched() << " nps " << nps() << " time " << t << " hashfull " << TT.full() << endl; - - lock_release(&TM.IOLock); - - if (ShowCurrentLine) - TM.threads[0].printCurrentLineRequest = true; } // Should we stop the search? if (PonderSearch) return; - bool stillAtFirstMove = RootMoveNumber == 1 + bool stillAtFirstMove = FirstRootMove && !AspirationFailLow && t > MaxSearchTime + ExtraSearchTime; @@ -2501,7 +2498,7 @@ namespace { int t = current_search_time(); PonderSearch = false; - bool stillAtFirstMove = RootMoveNumber == 1 + bool stillAtFirstMove = FirstRootMove && !AspirationFailLow && t > MaxSearchTime + ExtraSearchTime; @@ -2552,6 +2549,36 @@ namespace { } + // print_pv_info() prints to standard output and eventually to log file information on + // the current PV line. It is called at each iteration or after a new pv is found. + + void print_pv_info(const Position& pos, SearchStack ss[], Value alpha, Value beta, Value value) { + + cout << "info depth " << Iteration + << " score " << value_to_string(value) + << ((value >= beta) ? " lowerbound" : + ((value <= alpha)? " upperbound" : "")) + << " time " << current_search_time() + << " nodes " << TM.nodes_searched() + << " nps " << nps() + << " pv "; + + for (int j = 0; ss[0].pv[j] != MOVE_NONE && j < PLY_MAX; j++) + cout << ss[0].pv[j] << " "; + + cout << endl; + + if (UseLogFile) + { + ValueType type = (value >= beta ? VALUE_TYPE_LOWER + : (value <= alpha ? VALUE_TYPE_UPPER : VALUE_TYPE_EXACT)); + + LogFile << pretty_pv(pos, current_search_time(), Iteration, + TM.nodes_searched(), value, type, ss[0].pv) << endl; + } + } + + // init_thread() is the function which is called when a new thread is // launched. It simply calls the idle_loop() function with the supplied // threadID. There are two versions of this function; one for POSIX @@ -2570,7 +2597,7 @@ namespace { DWORD WINAPI init_thread(LPVOID threadID) { TM.idle_loop(*(int*)threadID, NULL); - return NULL; + return 0; } #endif @@ -2584,13 +2611,13 @@ namespace { void ThreadsManager::resetNodeCounters() { - for (int i = 0; i < THREAD_MAX; i++) + for (int i = 0; i < MAX_THREADS; i++) threads[i].nodes = 0ULL; } void ThreadsManager::resetBetaCounters() { - for (int i = 0; i < THREAD_MAX; i++) + for (int i = 0; i < MAX_THREADS; i++) threads[i].betaCutOffs[WHITE] = threads[i].betaCutOffs[BLACK] = 0ULL; } @@ -2606,7 +2633,7 @@ namespace { void ThreadsManager::get_beta_counters(Color us, int64_t& our, int64_t& their) const { our = their = 0UL; - for (int i = 0; i < THREAD_MAX; i++) + for (int i = 0; i < MAX_THREADS; i++) { our += threads[i].betaCutOffs[us]; their += threads[i].betaCutOffs[opposite_color(us)]; @@ -2620,57 +2647,68 @@ namespace { void ThreadsManager::idle_loop(int threadID, SplitPoint* waitSp) { - assert(threadID >= 0 && threadID < THREAD_MAX); - - threads[threadID].running = true; + assert(threadID >= 0 && threadID < MAX_THREADS); - while (!AllThreadsShouldExit || threadID == 0) + while (true) { + // Slave threads can exit as soon as AllThreadsShouldExit raises, + // master should exit as last one. + if (AllThreadsShouldExit) + { + assert(!waitSp); + threads[threadID].state = THREAD_TERMINATED; + return; + } + // If we are not thinking, wait for a condition to be signaled // instead of wasting CPU time polling for work. - while ( threadID != 0 - && !AllThreadsShouldExit - && (AllThreadsShouldSleep || threadID >= ActiveThreads)) + while (AllThreadsShouldSleep || threadID >= ActiveThreads) { - - threads[threadID].sleeping = true; + assert(!waitSp); + assert(threadID != 0); + threads[threadID].state = THREAD_SLEEPING; #if !defined(_MSC_VER) - pthread_mutex_lock(&WaitLock); + lock_grab(&WaitLock); if (AllThreadsShouldSleep || threadID >= ActiveThreads) pthread_cond_wait(&WaitCond, &WaitLock); - - pthread_mutex_unlock(&WaitLock); + lock_release(&WaitLock); #else WaitForSingleObject(SitIdleEvent[threadID], INFINITE); #endif } - // Out of the while loop to avoid races in case thread is woken up but - // while condition still holds true so that is put to sleep again. - threads[threadID].sleeping = false; + // If thread has just woken up, mark it as available + if (threads[threadID].state == THREAD_SLEEPING) + threads[threadID].state = THREAD_AVAILABLE; // If this thread has been assigned work, launch a search - if (threads[threadID].workIsWaiting) + if (threads[threadID].state == THREAD_WORKISWAITING) { - assert(!threads[threadID].idle); + assert(!AllThreadsShouldExit && !AllThreadsShouldSleep); + + threads[threadID].state = THREAD_SEARCHING; - threads[threadID].workIsWaiting = false; if (threads[threadID].splitPoint->pvNode) sp_search_pv(threads[threadID].splitPoint, threadID); else sp_search(threads[threadID].splitPoint, threadID); - threads[threadID].idle = true; + assert(threads[threadID].state == THREAD_SEARCHING); + + threads[threadID].state = THREAD_AVAILABLE; } // If this thread is the master of a split point and all threads have // finished their work at this split point, return from the idle loop. if (waitSp != NULL && waitSp->cpus == 0) + { + assert(threads[threadID].state == THREAD_AVAILABLE); + + threads[threadID].state = THREAD_SEARCHING; return; + } } - - threads[threadID].running = false; } @@ -2689,44 +2727,43 @@ namespace { // Initialize global locks lock_init(&MPLock, NULL); - lock_init(&IOLock, NULL); + lock_init(&WaitLock, NULL); + +#if !defined(_MSC_VER) + pthread_cond_init(&WaitCond, NULL); +#else + for (i = 0; i < MAX_THREADS; i++) + SitIdleEvent[i] = CreateEvent(0, FALSE, FALSE, 0); +#endif // Initialize SplitPointStack locks - for (int i = 0; i < THREAD_MAX; i++) + for (i = 0; i < MAX_THREADS; i++) for (int j = 0; j < ACTIVE_SPLIT_POINTS_MAX; j++) { SplitPointStack[i][j].parent = NULL; lock_init(&(SplitPointStack[i][j].lock), NULL); } -#if !defined(_MSC_VER) - pthread_mutex_init(&WaitLock, NULL); - pthread_cond_init(&WaitCond, NULL); -#else - for (i = 0; i < THREAD_MAX; i++) - SitIdleEvent[i] = CreateEvent(0, FALSE, FALSE, 0); -#endif - // Will be set just before program exits to properly end the threads AllThreadsShouldExit = false; // Threads will be put to sleep as soon as created AllThreadsShouldSleep = true; - // All threads except the main thread should be initialized to idle state + // All threads except the main thread should be initialized to THREAD_AVAILABLE ActiveThreads = 1; - for (i = 1; i < THREAD_MAX; i++) - threads[i].idle = true; + threads[0].state = THREAD_SEARCHING; + for (i = 1; i < MAX_THREADS; i++) + threads[i].state = THREAD_AVAILABLE; // Launch the helper threads - for (i = 1; i < THREAD_MAX; i++) + for (i = 1; i < MAX_THREADS; i++) { #if !defined(_MSC_VER) ok = (pthread_create(pthread, NULL, init_thread, (void*)(&i)) == 0); #else - DWORD iID[1]; - ok = (CreateThread(NULL, 0, init_thread, (LPVOID)(&i), 0, iID) != NULL); + ok = (CreateThread(NULL, 0, init_thread, (LPVOID)(&i), 0, NULL) != NULL); #endif if (!ok) @@ -2736,7 +2773,7 @@ namespace { } // Wait until the thread has finished launching and is gone to sleep - while (!threads[i].running || !threads[i].sleeping); + while (threads[i].state != THREAD_SLEEPING) {} } } @@ -2746,27 +2783,30 @@ namespace { void ThreadsManager::exit_threads() { - ActiveThreads = THREAD_MAX; // HACK + ActiveThreads = MAX_THREADS; // HACK AllThreadsShouldSleep = true; // HACK wake_sleeping_threads(); + + // This makes the threads to exit idle_loop() AllThreadsShouldExit = true; - for (int i = 1; i < THREAD_MAX; i++) - { - threads[i].stopRequest = true; - while (threads[i].running); - } + + // Wait for thread termination + for (int i = 1; i < MAX_THREADS; i++) + while (threads[i].state != THREAD_TERMINATED); // Now we can safely destroy the locks - for (int i = 0; i < THREAD_MAX; i++) + for (int i = 0; i < MAX_THREADS; i++) for (int j = 0; j < ACTIVE_SPLIT_POINTS_MAX; j++) lock_destroy(&(SplitPointStack[i][j].lock)); + + lock_destroy(&WaitLock); + lock_destroy(&MPLock); } - // thread_should_stop() checks whether the thread with a given threadID has - // been asked to stop, directly or indirectly. This can happen if a beta - // cutoff has occurred in the thread's currently active split point, or in - // some ancestor of the current split point. + // thread_should_stop() checks whether the thread should stop its search. + // This can happen if a beta cutoff has occurred in the thread's currently + // active split point, or in some ancestor of the current split point. bool ThreadsManager::thread_should_stop(int threadID) const { @@ -2774,17 +2814,8 @@ namespace { SplitPoint* sp; - if (threads[threadID].stopRequest) - return true; - - if (ActiveThreads <= 2) - return false; - - for (sp = threads[threadID].splitPoint; sp != NULL; sp = sp->parent) - if (sp->finished) - return true; - - return false; + for (sp = threads[threadID].splitPoint; sp && !sp->stopRequest; sp = sp->parent) {} + return sp != NULL; } @@ -2802,7 +2833,7 @@ namespace { assert(master >= 0 && master < ActiveThreads); assert(ActiveThreads > 1); - if (!threads[slave].idle || slave == master) + if (threads[slave].state != THREAD_AVAILABLE || slave == master) return false; // Make a local copy to be sure doesn't change under our feet @@ -2826,10 +2857,10 @@ namespace { } - // idle_thread_exists() tries to find an idle thread which is available as + // available_thread_exists() tries to find an idle thread which is available as // a slave for the thread with threadID "master". - bool ThreadsManager::idle_thread_exists(int master) const { + bool ThreadsManager::available_thread_exists(int master) const { assert(master >= 0 && master < ActiveThreads); assert(ActiveThreads > 1); @@ -2855,15 +2886,17 @@ namespace { // splitPoint->cpus becomes 0), split() returns true. bool ThreadsManager::split(const Position& p, SearchStack* sstck, int ply, - Value* alpha, Value* beta, Value* bestValue, const Value futilityValue, - Depth depth, int* moves, MovePicker* mp, int master, bool pvNode) { + Value* alpha, const Value beta, Value* bestValue, + Depth depth, bool mateThreat, int* moves, MovePicker* mp, int master, bool pvNode) { assert(p.is_ok()); assert(sstck != NULL); assert(ply >= 0 && ply < PLY_MAX); - assert(*bestValue >= -VALUE_INFINITE && *bestValue <= *alpha); - assert(!pvNode || *alpha < *beta); - assert(*beta <= VALUE_INFINITE); + assert(*bestValue >= -VALUE_INFINITE); + assert( ( pvNode && *bestValue <= *alpha) + || (!pvNode && *bestValue < beta )); + assert(!pvNode || *alpha < beta); + assert(beta <= VALUE_INFINITE); assert(depth > Depth(0)); assert(master >= 0 && master < ActiveThreads); assert(ActiveThreads > 1); @@ -2874,7 +2907,7 @@ namespace { // If no other thread is available to help us, or if we have too many // active split points, don't split. - if ( !idle_thread_exists(master) + if ( !available_thread_exists(master) || threads[master].activeSplitPoints >= ACTIVE_SPLIT_POINTS_MAX) { lock_release(&MPLock); @@ -2882,19 +2915,18 @@ namespace { } // Pick the next available split point object from the split point stack - splitPoint = SplitPointStack[master] + threads[master].activeSplitPoints; - threads[master].activeSplitPoints++; + splitPoint = &SplitPointStack[master][threads[master].activeSplitPoints]; // Initialize the split point object splitPoint->parent = threads[master].splitPoint; - splitPoint->finished = false; + splitPoint->stopRequest = false; splitPoint->ply = ply; splitPoint->depth = depth; - splitPoint->alpha = pvNode ? *alpha : (*beta - 1); - splitPoint->beta = *beta; + splitPoint->mateThreat = mateThreat; + splitPoint->alpha = pvNode ? *alpha : beta - 1; + splitPoint->beta = beta; splitPoint->pvNode = pvNode; splitPoint->bestValue = *bestValue; - splitPoint->futilityValue = futilityValue; splitPoint->master = master; splitPoint->mp = mp; splitPoint->moves = *moves; @@ -2905,21 +2937,16 @@ namespace { splitPoint->slaves[i] = 0; threads[master].splitPoint = splitPoint; + threads[master].activeSplitPoints++; - // If we are here it means we are not idle - assert(!threads[master].idle); - - // Following assert could fail because we could be slave of a master - // thread that has just raised a stop request. Note that stopRequest - // can be changed with only splitPoint::lock held, not with MPLock. - /* assert(!threads[master].stopRequest); */ + // If we are here it means we are not available + assert(threads[master].state != THREAD_AVAILABLE); - // Allocate available threads setting idle flag to false + // Allocate available threads setting state to THREAD_BOOKED for (int i = 0; i < ActiveThreads && splitPoint->cpus < MaxThreadsPerSplitPoint; i++) if (thread_is_available(i, master)) { - threads[i].idle = false; - threads[i].stopRequest = false; + threads[i].state = THREAD_BOOKED; threads[i].splitPoint = splitPoint; splitPoint->slaves[i] = 1; splitPoint->cpus++; @@ -2927,7 +2954,7 @@ namespace { assert(splitPoint->cpus > 1); - // We can release the lock because master and slave threads are already booked + // We can release the lock because slave threads are already booked and master is not available lock_release(&MPLock); // Tell the threads that they have work to do. This will make them leave @@ -2936,12 +2963,15 @@ namespace { if (i == master || splitPoint->slaves[i]) { memcpy(splitPoint->sstack[i] + ply - 1, sstck + ply - 1, 4 * sizeof(SearchStack)); - threads[i].workIsWaiting = true; // This makes the slave to exit from idle_loop() + + assert(i == master || threads[i].state == THREAD_BOOKED); + + threads[i].state = THREAD_WORKISWAITING; // This makes the slave to exit from idle_loop() } // Everything is set up. The master thread enters the idle loop, from - // which it will instantly launch a search, because its workIsWaiting - // slot is 'true'. We send the split point as a second parameter to the + // which it will instantly launch a search, because its state is + // THREAD_WORKISWAITING. We send the split point as a second parameter to the // idle loop, which means that the main thread will return from the idle // loop when all threads have finished their work at this split point // (i.e. when splitPoint->cpus == 0). @@ -2954,10 +2984,7 @@ namespace { if (pvNode) *alpha = splitPoint->alpha; - *beta = splitPoint->beta; *bestValue = splitPoint->bestValue; - threads[master].stopRequest = false; - threads[master].idle = false; threads[master].activeSplitPoints--; threads[master].splitPoint = splitPoint->parent; @@ -2979,86 +3006,30 @@ namespace { if (ActiveThreads == 1) return; - for (int i = 1; i < ActiveThreads; i++) - { - assert(threads[i].sleeping == true); - - threads[i].idle = true; - threads[i].workIsWaiting = false; - } - #if !defined(_MSC_VER) pthread_mutex_lock(&WaitLock); pthread_cond_broadcast(&WaitCond); pthread_mutex_unlock(&WaitLock); #else - for (int i = 1; i < THREAD_MAX; i++) + for (int i = 1; i < MAX_THREADS; i++) SetEvent(SitIdleEvent[i]); #endif - // Wait for the threads to be all woken up - for (int i = 1; i < ActiveThreads; i++) - while (threads[i].sleeping); } // put_threads_to_sleep() makes all the threads go to sleep just before - // to leave think(), at the end of the search. threads should have already + // to leave think(), at the end of the search. Threads should have already // finished the job and should be idle. void ThreadsManager::put_threads_to_sleep() { assert(!AllThreadsShouldSleep); + // This makes the threads to go to sleep AllThreadsShouldSleep = true; - - // Wait for the threads to be all sleeping and reset flags - // to a known state. - for (int i = 1; i < ActiveThreads; i++) - { - while (!threads[i].sleeping); - - assert(threads[i].idle); - assert(threads[i].running); - assert(!threads[i].workIsWaiting); - - // These two flags can be in a random state - threads[i].stopRequest = threads[i].printCurrentLineRequest = false; - } } - // print_current_line() prints _once_ the current line of search for a - // given thread and then setup the print request for the next thread. - // Called when the UCI option UCI_ShowCurrLine is 'true'. - - void ThreadsManager::print_current_line(SearchStack ss[], int ply, int threadID) { - - assert(ply >= 0 && ply < PLY_MAX); - assert(threadID >= 0 && threadID < ActiveThreads); - - if (!threads[threadID].printCurrentLineRequest) - return; - - // One shot only - threads[threadID].printCurrentLineRequest = false; - - if (!threads[threadID].idle) - { - lock_grab(&IOLock); - cout << "info currline " << (threadID + 1); - for (int p = 0; p < ply; p++) - cout << " " << ss[p].currentMove; - - cout << endl; - lock_release(&IOLock); - } - - // Setup print request for the next thread ID - if (threadID + 1 < ActiveThreads) - threads[threadID + 1].printCurrentLineRequest = true; - } - - /// The RootMoveList class // RootMoveList c'tor