X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fsearch.cpp;h=45e91e591ad768e213d7b003dd7dad5f4ffc3137;hb=62c68c2d2174ee5158cf3282c7429b15483f3d51;hp=b6029e0c71f4dcd3506092a0695b22a0c0446d4c;hpb=c52da3b806b74ba5ab5249784d39da8fec3c7465;p=stockfish diff --git a/src/search.cpp b/src/search.cpp index b6029e0c..8ea1b718 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 @@ -23,6 +23,7 @@ //// #include +#include #include #include #include @@ -41,6 +42,8 @@ #include "tt.h" #include "ucioption.h" +using std::cout; +using std::endl; //// //// Local definitions @@ -49,57 +52,86 @@ namespace { /// Types + enum NodeType { NonPV, PV }; + + // Set to true to force running with one thread. + // Used for debugging SMP code. + const bool FakeSplit = false; + + // ThreadsManager class is used to handle all the threads related stuff in search, + // init, starting, parking and, the most important, launching a slave thread at a + // split point are what this class does. All the access to shared thread data is + // done through this class, so that we avoid using global variables instead. + + class ThreadsManager { + /* As long as the single ThreadsManager object is defined as a global we don't + need to explicitly initialize to zero its data members because variables with + static storage duration are automatically set to zero before enter main() + */ + public: + void init_threads(); + void exit_threads(); + + int active_threads() const { return ActiveThreads; } + void set_active_threads(int newActiveThreads) { ActiveThreads = newActiveThreads; } + void incrementNodeCounter(int threadID) { threads[threadID].nodes++; } + void incrementBetaCounter(Color us, Depth d, int threadID) { threads[threadID].betaCutOffs[us] += unsigned(d); } + + void resetNodeCounters(); + void resetBetaCounters(); + int64_t nodes_searched() const; + void get_beta_counters(Color us, int64_t& our, int64_t& their) 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* sp); + + template + void split(const Position& pos, SearchStack* ss, int ply, Value* alpha, const Value beta, Value* bestValue, + Depth depth, bool mateThreat, int* moveCount, MovePicker* mp, bool pvNode); - // IterationInfoType stores search results for each iteration - // - // Because we use relatively small (dynamic) aspiration window, - // there happens many fail highs and fail lows in root. And - // because we don't do researches in those cases, "value" stored - // here is not necessarily exact. Instead in case of fail high/low - // we guess what the right value might be and store our guess - // as a "speculated value" and then move on. Speculated values are - // used just to calculate aspiration window width, so also if are - // not exact is not big a problem. - - struct IterationInfoType { - - IterationInfoType(Value v = Value(0), Value sv = Value(0)) - : value(v), speculatedValue(sv) {} - - Value value, speculatedValue; - }; + private: + friend void poll(); + int ActiveThreads; + volatile bool AllThreadsShouldExit, AllThreadsShouldSleep; + Thread threads[MAX_THREADS]; + SplitPoint SplitPointStack[MAX_THREADS][ACTIVE_SPLIT_POINTS_MAX]; - // The BetaCounterType class is used to order moves at ply one. - // Apart for the first one that has its score, following moves - // normally have score -VALUE_INFINITE, so are ordered according - // to the number of beta cutoffs occurred under their subtree during - // the last iteration. The counters are per thread variables to avoid - // concurrent accessing under SMP case. + Lock MPLock, WaitLock; - struct BetaCounterType { +#if !defined(_MSC_VER) + pthread_cond_t WaitCond; +#else + HANDLE SitIdleEvent[MAX_THREADS]; +#endif - BetaCounterType(); - void clear(); - void add(Color us, Depth d, int threadID); - void read(Color us, int64_t& our, int64_t& their); }; - // The RootMove class is used for moves at the root at the tree. For each + // RootMove struct is used for moves at the root at 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). struct RootMove { - RootMove(); - bool operator<(const RootMove&); // used to sort + RootMove() { nodes = cumulativeNodes = ourBeta = theirBeta = 0ULL; } + + // 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 a higher score, or if the moves + // have equal score but m1 has the higher beta cut-off count. + bool operator<(const RootMove& m) const { + + return score != m.score ? score < m.score : theirBeta <= m.theirBeta; + } Move move; Value score; - int64_t nodes, cumulativeNodes; + int64_t nodes, cumulativeNodes, ourBeta, theirBeta; Move pv[PLY_MAX_PLUS_2]; - int64_t ourBeta, theirBeta; }; @@ -110,17 +142,18 @@ namespace { public: RootMoveList(Position& pos, Move searchMoves[]); - inline Move get_move(int moveNum) const; - inline Value get_move_score(int moveNum) const; - inline void set_move_score(int moveNum, Value score); - inline void set_move_nodes(int moveNum, int64_t nodes); - inline void set_beta_counters(int moveNum, int64_t our, int64_t their); + + int move_count() const { return count; } + Move get_move(int moveNum) const { return moves[moveNum].move; } + Value get_move_score(int moveNum) const { return moves[moveNum].score; } + void set_move_score(int moveNum, Value score) { moves[moveNum].score = score; } + Move get_move_pv(int moveNum, int i) const { return moves[moveNum].pv[i]; } + int64_t get_move_cumulative_nodes(int moveNum) const { return moves[moveNum].cumulativeNodes; } + + void set_move_nodes(int moveNum, int64_t nodes); + void set_beta_counters(int moveNum, int64_t our, int64_t their); void set_move_pv(int moveNum, const Move pv[]); - inline Move get_move_pv(int moveNum, int i) const; - inline int64_t get_move_cumulative_nodes(int moveNum) const; - inline int move_count() const; - Move scan_for_easy_move() const; - inline void sort(); + void sort(); void sort_multipv(int n); private: @@ -130,191 +163,156 @@ namespace { }; - /// Constants + /// Adjustments - // Search depth at iteration 1 - const Depth InitialDepth = OnePly /*+ OnePly/2*/; + // Step 6. Razoring + + // Maximum depth for razoring + const Depth RazorDepth = 4 * OnePly; - // Depth limit for selective search - const Depth SelectiveDepth = 7 * OnePly; + // Dynamic razoring margin based on depth + inline Value razor_margin(Depth d) { return Value(0x200 + 0x10 * int(d)); } - // Use internal iterative deepening? - const bool UseIIDAtPVNodes = true; - const bool UseIIDAtNonPVNodes = false; + // Step 8. Null move search with verification search - // 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. + // 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); + + // 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 IIDDepth[2] = { 8 * OnePly /* non-PV */, 5 * OnePly /* PV */}; + + // 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); - // 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 11. Decide the new search depth - // Problem margin. If the score of the first move at iteration N+1 has - // dropped by more than this since iteration N, the boolean variable - // "Problem" is set to true, which will make the program spend some extra - // time looking for a better move. - const Value ProblemMargin = Value(0x28); + // 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]; - // No problem margin. If the boolean "Problem" is true, and a new move - // is found at the root which is less than NoProblemMargin worse than the - // best move from the previous iteration, Problem is set back to false. - const Value NoProblemMargin = Value(0x14); + // Minimum depth for use of singular extension + const Depth SingularExtensionDepth[2] = { 8 * OnePly /* non-PV */, 6 * OnePly /* PV */}; - // Null move margin. A null move search will not be done if the approximate - // evaluation of the position is more than NullMoveMargin below beta. - const Value NullMoveMargin = Value(0x300); + // If the TT move is at least SingularExtensionMargin better then the + // remaining ones we will extend it. + const Value SingularExtensionMargin = Value(0x20); - // Pruning criterions. See the code and comments in ok_to_prune() to - // understand their precise meaning. - const bool PruneEscapeMoves = false; - const bool PruneDefendingMoves = false; - const bool PruneBlockingMoves = false; + // Step 12. Futility pruning - // Margins for futility pruning in the quiescence search, and at frontier - // and near frontier nodes. + // Futility margin for quiescence search const Value FutilityMarginQS = Value(0x80); - // Each move futility margin is decreased - const Value IncrementalFutilityMargin = Value(0xA); + // Futility lookup tables (initialized at startup) and their getter functions + int32_t FutilityMarginsMatrix[16][64]; // [depth][moveNumber] + int FutilityMoveCountArray[32]; // [depth] - // Remaining depth: 1 ply 1.5 ply 2 ply 2.5 ply 3 ply 3.5 ply - const Value FutilityMargins[12] = { Value(0x100), Value(0x120), Value(0x200), Value(0x220), Value(0x250), Value(0x270), - // 4 ply 4.5 ply 5 ply 5.5 ply 6 ply 6.5 ply - Value(0x2A0), Value(0x2C0), Value(0x340), Value(0x360), Value(0x3A0), Value(0x3C0) }; - // Razoring - const Depth RazorDepth = 4*OnePly; + 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; } - // Remaining depth: 1 ply 1.5 ply 2 ply 2.5 ply 3 ply 3.5 ply - const Value RazorMargins[6] = { Value(0x180), Value(0x300), Value(0x300), Value(0x3C0), Value(0x3C0), Value(0x3C0) }; + // Step 14. Reduced search - // Remaining depth: 1 ply 1.5 ply 2 ply 2.5 ply 3 ply 3.5 ply - const Value RazorApprMargins[6] = { Value(0x520), Value(0x300), Value(0x300), Value(0x300), Value(0x300), Value(0x300) }; + // Reduction lookup tables (initialized at startup) and their getter functions + int8_t ReductionMatrix[2][64][64]; // [pv][depth][moveNumber] + template + inline Depth reduction(Depth d, int mn) { return (Depth) ReductionMatrix[PV][Min(d / 2, 63)][Min(mn, 63)]; } - /// Variables initialized by UCI options + // Common adjustments - // Minimum number of full depth (i.e. non-reduced) moves at PV and non-PV nodes - int LMRPVMoves, LMRNonPVMoves; // heavy SMP read access for the latter + // Search depth at iteration 1 + const Depth InitialDepth = OnePly; - // Depth limit for use of dynamic threat detection - Depth ThreatDepth; // heavy SMP read access + // 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; - const int LSNTime = 4000; // In milliseconds + const bool UseLSNFiltering = false; + const int LSNTime = 100; // In milliseconds 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. - // There is heavy SMP read access on these arrays - Depth CheckExtension[2], SingleReplyExtension[2], PawnPushTo7thExtension[2]; - Depth PassedPawnExtension[2], PawnEndgameExtension[2], MateThreatExtension[2]; - // Iteration counters + /// Global variables + + // Iteration counter int Iteration; - BetaCounterType BetaCounter; // has per-thread internal data // Scores and number of times the best move changed for each iteration - IterationInfoType IterationInfo[PLY_MAX_PLUS_2]; + Value ValueByIteration[PLY_MAX_PLUS_2]; int BestMoveChangesByIteration[PLY_MAX_PLUS_2]; + // Search window management + int AspirationDelta; + // MultiPV mode int MultiPV; // Time managment variables - int SearchStartTime; - int MaxNodes, MaxDepth; - int MaxSearchTime, AbsoluteMaxSearchTime, ExtraSearchTime, ExactMaxTime; - int RootMoveNumber; - bool InfiniteSearch; - bool PonderSearch; - bool StopOnPonderhit; - bool AbortSearch; // heavy SMP read access - bool Quit; - bool FailHigh; - bool FailLow; - bool Problem; - - // Show current line? - bool ShowCurrentLine; + int SearchStartTime, MaxNodes, MaxDepth, MaxSearchTime; + int AbsoluteMaxSearchTime, ExtraSearchTime, ExactMaxTime; + bool UseTimeManagement, InfiniteSearch, PonderSearch, StopOnPonderhit; + bool FirstRootMove, AbortSearch, Quit, AspirationFailLow; // Log file bool UseLogFile; std::ofstream LogFile; - // MP related variables - int ActiveThreads = 1; + // Multi-threads related variables Depth MinimumSplitDepth; int MaxThreadsPerSplitPoint; - Thread Threads[THREAD_MAX]; - Lock MPLock; - Lock IOLock; - bool AllThreadsShouldExit = false; - const int MaxActiveSplitPoints = 8; - SplitPoint SplitPointStack[THREAD_MAX][MaxActiveSplitPoints]; - bool Idle = true; - -#if !defined(_MSC_VER) - pthread_cond_t WaitCond; - pthread_mutex_t WaitLock; -#else - HANDLE SitIdleEvent[THREAD_MAX]; -#endif + 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 alpha, Value beta); - 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); - Value qsearch(Position& pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID); + Value root_search(Position& pos, SearchStack* ss, Move* pv, RootMoveList& rml, Value* alphaPtr, Value* betaPtr); + + template + Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int ply); + + template + Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int ply); + + template void sp_search(SplitPoint* sp, int threadID); - void sp_search_pv(SplitPoint* sp, int threadID); - void init_node(SearchStack ss[], int ply, int threadID); - void update_pv(SearchStack ss[], int ply); - void sp_update_pv(SearchStack* pss, SearchStack ss[], int ply); + + template + Depth extension(const Position& pos, Move m, bool captureOrPromotion, bool moveIsCheck, bool singleEvasion, bool mateThreat, bool* dangerous); + bool connected_moves(const Position& pos, Move m1, Move m2); bool value_is_mate(Value value); - bool move_is_killer(Move m, const SearchStack& ss); - Depth extension(const Position& pos, Move m, bool pvNode, bool capture, bool check, bool singleReply, bool mateThreat, bool* dangerous); - bool ok_to_do_nullmove(const Position& pos); - bool ok_to_prune(const Position& pos, Move m, Move threat, Depth d); + bool move_is_killer(Move m, SearchStack* ss); bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply); - void update_history(const Position& pos, Move m, Depth depth, Move movesSearched[], int moveCount); - void update_killers(Move m, SearchStack& ss); + 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 update_killers(Move m, SearchStack* ss); + void update_gains(const Position& pos, Move move, Value before, Value after); - bool fail_high_ply_1(); int current_search_time(); int nps(); void poll(); void ponderhit(); - void print_current_line(SearchStack ss[], int ply, int threadID); void wait_for_stop_or_ponderhit(); - void init_ss_array(SearchStack ss[]); - - void idle_loop(int threadID, SplitPoint* waitSp); - void init_split_point_stack(); - void destroy_split_point_stack(); - bool thread_should_stop(int threadID); - bool thread_is_available(int slave, int master); - bool idle_thread_exists(int master); - bool split(const Position& pos, SearchStack* ss, int ply, - Value *alpha, Value *beta, Value *bestValue, - const Value futilityValue, const Value approximateValue, - Depth depth, int *moves, - MovePicker *mp, int master, bool pvNode); - void wake_sleeping_threads(); + void init_ss_array(SearchStack* ss, int size); + void print_pv_info(const Position& pos, Move* ss, Value alpha, Value beta, Value value); #if !defined(_MSC_VER) void *init_thread(void *threadID); @@ -329,15 +327,68 @@ namespace { //// Functions //// +/// init_threads(), exit_threads() and nodes_searched() are helpers to +/// give accessibility to some TM methods from outside of current file. + +void init_threads() { TM.init_threads(); } +void exit_threads() { TM.exit_threads(); } +int64_t nodes_searched() { return TM.nodes_searched(); } + + +/// init_search() is called during startup. It initializes various lookup tables + +void init_search() { + + int d; // depth (OnePly == 2) + int hd; // half depth (OnePly == 1) + int mc; // moveCount + + // Init reductions array + for (hd = 1; hd < 64; hd++) for (mc = 1; mc < 64; mc++) + { + double pvRed = log(double(hd)) * log(double(mc)) / 3.0; + double nonPVRed = log(double(hd)) * log(double(mc)) / 1.5; + ReductionMatrix[PV][hd][mc] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(OnePly)) : 0); + ReductionMatrix[NonPV][hd][mc] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(OnePly)) : 0); + } + + // Init futility margins array + for (d = 0; d < 16; d++) for (mc = 0; mc < 64; mc++) + FutilityMarginsMatrix[d][mc] = 112 * int(log(double(d * d) / 2) / log(2.0) + 1.001) - 8 * mc + 45; + + // Init futility move count array + for (d = 0; d < 32; d++) + FutilityMoveCountArray[d] = 3 + (1 << (3 * d / 8)); +} + + +// SearchStack::init() initializes a search stack entry. +// Called at the beginning of search() when starting to examine a new node. +void SearchStack::init() { + + currentMove = threatMove = bestMove = MOVE_NONE; + reduction = Depth(0); + eval = VALUE_NONE; +} + +// SearchStack::initKillers() initializes killers for a search stack entry +void SearchStack::initKillers() { + + mateKiller = MOVE_NONE; + for (int i = 0; i < KILLER_MAX; i++) + killers[i] = MOVE_NONE; +} + -/// perft() is our utility to verify move generation is bug free. All the -/// legal moves up to given depth are generated and counted and the sum returned. +/// perft() is our utility to verify move generation is bug free. All the legal +/// moves up to given depth are generated and counted and the sum returned. 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. @@ -351,7 +402,6 @@ 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); @@ -369,143 +419,123 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move, int time[], int increment[], int movesToGo, int maxDepth, int maxNodes, int maxTime, Move searchMoves[]) { - // Look for a book move - if (!infinite && !ponder && get_option_value_bool("OwnBook")) + // Initialize global search variables + StopOnPonderhit = AbortSearch = Quit = AspirationFailLow = false; + MaxSearchTime = AbsoluteMaxSearchTime = ExtraSearchTime = 0; + NodesSincePoll = 0; + TM.resetNodeCounters(); + SearchStartTime = get_system_time(); + ExactMaxTime = maxTime; + MaxDepth = maxDepth; + MaxNodes = maxNodes; + InfiniteSearch = infinite; + PonderSearch = ponder; + UseTimeManagement = !ExactMaxTime && !MaxDepth && !MaxNodes && !InfiniteSearch; + + // 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("book.bin"); + 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) { - std::cout << "bestmove " << bookMove << std::endl; + if (PonderSearch) + wait_for_stop_or_ponderhit(); + + cout << "bestmove " << bookMove << endl; return true; } } - // Initialize global search variables - Idle = false; - SearchStartTime = get_system_time(); - for (int i = 0; i < THREAD_MAX; i++) - { - Threads[i].nodes = 0ULL; - Threads[i].failHighPly1 = false; - } - NodesSincePoll = 0; - InfiniteSearch = infinite; - PonderSearch = ponder; - StopOnPonderhit = false; - AbortSearch = false; - Quit = false; - FailHigh = false; - FailLow = false; - Problem = false; - ExactMaxTime = maxTime; + // Reset loseOnTime flag at the beginning of a new game + if (button_was_pressed("New Game")) + loseOnTime = false; // Read UCI option values TT.set_size(get_option_value_int("Hash")); if (button_was_pressed("Clear Hash")) - { TT.clear(); - loseOnTime = false; // reset at the beginning of a new game - } - - 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)")); - - SingleReplyExtension[1] = Depth(get_option_value_int("Single Reply Extension (PV nodes)")); - SingleReplyExtension[0] = Depth(get_option_value_int("Single Reply 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)")); - - LMRPVMoves = get_option_value_int("Full Depth Moves (PV nodes)") + 1; - LMRNonPVMoves = get_option_value_int("Full Depth Moves (non-PV nodes)") + 1; - 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 int newActiveThreads = get_option_value_int("Threads"); - if (newActiveThreads != ActiveThreads) + if (newActiveThreads != TM.active_threads()) { - ActiveThreads = newActiveThreads; - init_eval(ActiveThreads); + TM.set_active_threads(newActiveThreads); + init_eval(TM.active_threads()); } // Wake up sleeping threads - wake_sleeping_threads(); - - for (int i = 1; i < ActiveThreads; i++) - assert(thread_is_available(i, 0)); + TM.wake_sleeping_threads(); // Set thinking time int myTime = time[side_to_move]; int myIncrement = increment[side_to_move]; - - if (!movesToGo) // Sudden death time control + if (UseTimeManagement) { - if (myIncrement) + if (!movesToGo) // Sudden death time control { - MaxSearchTime = myTime / 30 + myIncrement; - AbsoluteMaxSearchTime = Max(myTime / 4, myIncrement - 100); - } else { // Blitz game without increment - MaxSearchTime = myTime / 30; - AbsoluteMaxSearchTime = myTime / 8; + if (myIncrement) + { + MaxSearchTime = myTime / 30 + myIncrement; + AbsoluteMaxSearchTime = Max(myTime / 4, myIncrement - 100); + } + else // Blitz game without increment + { + MaxSearchTime = myTime / 30; + AbsoluteMaxSearchTime = myTime / 8; + } } - } - else // (x moves) / (y minutes) - { - if (movesToGo == 1) + else // (x moves) / (y minutes) { - MaxSearchTime = myTime / 2; - AbsoluteMaxSearchTime = - (myTime > 3000)? (myTime - 500) : ((myTime * 3) / 4); - } else { - MaxSearchTime = myTime / Min(movesToGo, 20); - AbsoluteMaxSearchTime = Min((4 * myTime) / movesToGo, myTime / 3); + if (movesToGo == 1) + { + MaxSearchTime = myTime / 2; + AbsoluteMaxSearchTime = (myTime > 3000)? (myTime - 500) : ((myTime * 3) / 4); + } + else + { + MaxSearchTime = myTime / Min(movesToGo, 20); + AbsoluteMaxSearchTime = Min((4 * myTime) / movesToGo, myTime / 3); + } } - } - if (PonderingEnabled) - { - MaxSearchTime += MaxSearchTime / 4; - MaxSearchTime = Min(MaxSearchTime, AbsoluteMaxSearchTime); + if (get_option_value_bool("Ponder")) + { + MaxSearchTime += MaxSearchTime / 4; + MaxSearchTime = Min(MaxSearchTime, AbsoluteMaxSearchTime); + } } - // Fixed depth or fixed number of nodes? - MaxDepth = maxDepth; - if (MaxDepth) - InfiniteSearch = true; // HACK - - MaxNodes = maxNodes; + // Set best NodesBetweenPolls interval to avoid lagging under + // heavy time pressure. if (MaxNodes) - { NodesBetweenPolls = Min(MaxNodes, 30000); - InfiniteSearch = true; // HACK - } else if (myTime && myTime < 1000) NodesBetweenPolls = 1000; else if (myTime && myTime < 5000) @@ -513,272 +543,164 @@ 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() << std::endl + LogFile << "Searching: " << pos.to_fen() << endl << "infinite: " << infinite << " ponder: " << ponder << " time: " << myTime << " increment: " << myIncrement - << " moves to go: " << movesToGo << std::endl; - - - // We're ready to start thinking. Call the iterative deepening loop function - // - // FIXME we really need to cleanup all this LSN ugliness - if (!loseOnTime) - { - Value v = id_loop(pos, searchMoves); - loseOnTime = ( UseLSNFiltering - && myTime < LSNTime - && myIncrement == 0 - && v < -LSNValue); - } - else - { - loseOnTime = false; // reset for next match - while (SearchStartTime + myTime + 1000 > get_system_time()) - ; // wait here - id_loop(pos, searchMoves); // to fail gracefully - } + << " moves to go: " << movesToGo << endl; - if (UseLogFile) - LogFile.close(); - - Idle = true; - return !Quit; -} - - -/// init_threads() is called during startup. It launches all helper threads, -/// and initializes the split point stack and the global locks and condition -/// objects. - -void init_threads() { - - volatile int i; - -#if !defined(_MSC_VER) - pthread_t pthread[1]; -#endif - - for (i = 0; i < THREAD_MAX; i++) - Threads[i].activeSplitPoints = 0; - - // Initialize global locks - lock_init(&MPLock, NULL); - lock_init(&IOLock, NULL); - - init_split_point_stack(); - -#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 - - // All threads except the main thread should be initialized to idle state - for (i = 1; i < THREAD_MAX; i++) + // LSN filtering. Used only for developing purposes, disabled by default + if ( UseLSNFiltering + && loseOnTime) { - Threads[i].stop = false; - Threads[i].workIsWaiting = false; - Threads[i].idle = true; - Threads[i].running = false; - } - - // Launch the helper threads - for(i = 1; i < THREAD_MAX; i++) - { -#if !defined(_MSC_VER) - pthread_create(pthread, NULL, init_thread, (void*)(&i)); -#else - DWORD iID[1]; - CreateThread(NULL, 0, init_thread, (LPVOID)(&i), 0, iID); -#endif - - // Wait until the thread has finished launching - while (!Threads[i].running); + // Step 2. If after last move we decided to lose on time, do it now! + while (SearchStartTime + myTime + 1000 > get_system_time()) + /* wait here */; } -} + // We're ready to start thinking. Call the iterative deepening loop function + Value v = id_loop(pos, searchMoves); -/// stop_threads() is called when the program exits. It makes all the -/// helper threads exit cleanly. - -void stop_threads() { - - ActiveThreads = THREAD_MAX; // HACK - Idle = false; // HACK - wake_sleeping_threads(); - AllThreadsShouldExit = true; - for (int i = 1; i < THREAD_MAX; i++) + if (UseLSNFiltering) { - Threads[i].stop = true; - while(Threads[i].running); + // Step 1. If this is sudden death game and our position is hopeless, + // decide to lose on time. + if ( !loseOnTime // If we already lost on time, go to step 3. + && myTime < LSNTime + && myIncrement == 0 + && movesToGo == 0 + && v < -LSNValue) + { + loseOnTime = true; + } + else if (loseOnTime) + { + // Step 3. Now after stepping over the time limit, reset flag for next match. + loseOnTime = false; + } } - destroy_split_point_stack(); -} - - -/// nodes_searched() returns the total number of nodes searched so far in -/// the current search. - -int64_t nodes_searched() { - - int64_t result = 0ULL; - for (int i = 0; i < ActiveThreads; i++) - result += Threads[i].nodes; - return result; -} + if (UseLogFile) + LogFile.close(); -// SearchStack::init() initializes a search stack. Used at the beginning of a -// new search from the root. -void SearchStack::init(int ply) { + TM.put_threads_to_sleep(); - pv[ply] = pv[ply + 1] = MOVE_NONE; - currentMove = threatMove = MOVE_NONE; - reduction = Depth(0); + return !Quit; } -void SearchStack::initKillers() { - - mateKiller = MOVE_NONE; - for (int i = 0; i < KILLER_MAX; i++) - killers[i] = MOVE_NONE; -} namespace { - // id_loop() is the main iterative deepening loop. It calls root_search + // id_loop() is the main iterative deepening loop. It calls root_search // repeatedly with increasing depth until the allocated thinking time has // been consumed, the user stops the search, or the maximum search depth is // reached. Value id_loop(const Position& pos, Move searchMoves[]) { - Position p(pos); + Position p(pos, pos.thread()); SearchStack ss[PLY_MAX_PLUS_2]; + Move pv[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); - // Print RootMoveList c'tor startup scoring to the standard output, - // so that we print information also for iteration 1. - std::cout << "info depth " << 1 << "\ninfo depth " << 1 - << " score " << value_to_string(rml.get_move_score(0)) - << " time " << current_search_time() - << " nodes " << nodes_searched() - << " nps " << nps() - << " pv " << rml.get_move(0) << "\n"; + // Handle special case of searching on a mate/stale position + if (rml.move_count() == 0) + { + if (PonderSearch) + wait_for_stop_or_ponderhit(); + + return pos.is_check() ? -VALUE_MATE : VALUE_DRAW; + } + + // 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() + << " nps " << nps() + << " pv " << rml.get_move(0) << "\n"; // Initialize TT.new_search(); H.clear(); - init_ss_array(ss); - IterationInfo[1] = IterationInfoType(rml.get_move_score(0), rml.get_move_score(0)); + init_ss_array(ss, PLY_MAX_PLUS_2); + pv[0] = pv[1] = MOVE_NONE; + ValueByIteration[1] = rml.get_move_score(0); Iteration = 1; - Move EasyMove = rml.scan_for_easy_move(); + // Is one move significantly better than others after initial scoring ? + if ( rml.move_count() == 1 + || rml.get_move_score(0) > rml.get_move_score(1) + EasyMoveMargin) + EasyMove = rml.get_move(0); // Iterative deepening loop while (Iteration < PLY_MAX) { // Initialize iteration - rml.sort(); Iteration++; BestMoveChangesByIteration[Iteration] = 0; - if (Iteration <= 5) - ExtraSearchTime = 0; - - std::cout << "info depth " << Iteration << std::endl; - // Calculate dynamic search window based on previous iterations - Value alpha, beta; + cout << "info depth " << Iteration << endl; - if (MultiPV == 1 && Iteration >= 6 && abs(IterationInfo[Iteration - 1].value) < VALUE_KNOWN_WIN) + // Calculate dynamic aspiration window based on previous iterations + if (MultiPV == 1 && Iteration >= 6 && abs(ValueByIteration[Iteration - 1]) < VALUE_KNOWN_WIN) { - int prevDelta1 = IterationInfo[Iteration - 1].speculatedValue - IterationInfo[Iteration - 2].speculatedValue; - int prevDelta2 = IterationInfo[Iteration - 2].speculatedValue - IterationInfo[Iteration - 3].speculatedValue; + int prevDelta1 = ValueByIteration[Iteration - 1] - ValueByIteration[Iteration - 2]; + int prevDelta2 = ValueByIteration[Iteration - 2] - ValueByIteration[Iteration - 3]; - int delta = Max(2 * abs(prevDelta1) + abs(prevDelta2), ProblemMargin); + AspirationDelta = Max(abs(prevDelta1) + abs(prevDelta2) / 2, 16); + AspirationDelta = (AspirationDelta + 7) / 8 * 8; // Round to match grainSize - alpha = Max(IterationInfo[Iteration - 1].value - delta, -VALUE_INFINITE); - beta = Min(IterationInfo[Iteration - 1].value + delta, VALUE_INFINITE); - } - else - { - alpha = - VALUE_INFINITE; - beta = VALUE_INFINITE; + alpha = Max(ValueByIteration[Iteration - 1] - AspirationDelta, -VALUE_INFINITE); + beta = Min(ValueByIteration[Iteration - 1] + AspirationDelta, 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, pv, rml, &alpha, &beta); // Write PV to transposition table, in case the relevant entries have // been overwritten during the search. - TT.insert_pv(p, ss[0].pv); + TT.insert_pv(p, pv); if (AbortSearch) break; // Value cannot be trusted. Break out immediately! //Save info about search result - Value speculatedValue; - bool fHigh = false; - bool fLow = false; - Value delta = value - IterationInfo[Iteration - 1].value; - - if (value >= beta) - { - assert(delta > 0); - - fHigh = true; - speculatedValue = value + delta; - BestMoveChangesByIteration[Iteration] += 2; // Allocate more time - } - else if (value <= alpha) - { - assert(value == alpha); - assert(delta < 0); - - fLow = true; - speculatedValue = value + delta; - BestMoveChangesByIteration[Iteration] += 3; // Allocate more time - } else - speculatedValue = value; - - speculatedValue = Min(Max(speculatedValue, -VALUE_INFINITE), VALUE_INFINITE); - IterationInfo[Iteration] = IterationInfoType(value, speculatedValue); + ValueByIteration[Iteration] = value; - // Erase the easy move if it differs from the new best move - if (ss[0].pv[0] != EasyMove) + // Drop the easy move if differs from the new best move + if (pv[0] != EasyMove) EasyMove = MOVE_NONE; - Problem = false; - - if (!InfiniteSearch) + if (UseTimeManagement) { // Time to stop? bool stopSearch = false; - // Stop search early if there is only a single legal move + // Stop search early if there is only a single legal move, + // we search up to Iteration 6 anyway to get a proper score. if (Iteration >= 6 && rml.move_count() == 1) stopSearch = true; // Stop search early when the last two iterations returned a mate score if ( Iteration >= 6 - && abs(IterationInfo[Iteration].value) >= abs(VALUE_MATE) - 100 - && abs(IterationInfo[Iteration-1].value) >= abs(VALUE_MATE) - 100) + && abs(ValueByIteration[Iteration]) >= abs(VALUE_MATE) - 100 + && abs(ValueByIteration[Iteration-1]) >= abs(VALUE_MATE) - 100) stopSearch = true; - // Stop search early if one move seems to be much better than the rest - int64_t nodes = nodes_searched(); + // Stop search early if one move seems to be much better than the others + int64_t nodes = TM.nodes_searched(); if ( Iteration >= 8 - && !fLow - && !fHigh - && EasyMove == ss[0].pv[0] + && EasyMove == pv[0] && ( ( rml.get_move_cumulative_nodes(0) > (nodes * 85) / 100 && current_search_time() > MaxSearchTime / 16) ||( rml.get_move_cumulative_nodes(0) > (nodes * 98) / 100 @@ -791,18 +713,17 @@ namespace { + BestMoveChangesByIteration[Iteration-1] * (MaxSearchTime / 3); // Stop search if most of MaxSearchTime is consumed at the end of the - // iteration. We probably don't have enough time to search the first + // iteration. We probably don't have enough time to search the first // move at the next iteration anyway. - if (current_search_time() > ((MaxSearchTime + ExtraSearchTime)*80) / 128) + if (current_search_time() > ((MaxSearchTime + ExtraSearchTime) * 80) / 128) stopSearch = true; if (stopSearch) { - //FIXME: Implement fail-low emergency measures - if (!PonderSearch) - break; - else + if (PonderSearch) StopOnPonderhit = true; + else + break; } } @@ -810,30 +731,32 @@ namespace { break; } - rml.sort(); - - // If we are pondering, we shouldn't print the best move before we - // are told to do so - if (PonderSearch) + // 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)) wait_for_stop_or_ponderhit(); else // Print final search statistics - std::cout << "info nodes " << nodes_searched() - << " nps " << nps() - << " time " << current_search_time() - << " hashfull " << TT.full() << std::endl; + cout << "info nodes " << TM.nodes_searched() + << " nps " << nps() + << " time " << current_search_time() + << " hashfull " << TT.full() << endl; // Print the best move and the ponder move to the standard output - if (ss[0].pv[0] == MOVE_NONE) + if (pv[0] == MOVE_NONE) { - ss[0].pv[0] = rml.get_move(0); - ss[0].pv[1] = MOVE_NONE; + pv[0] = rml.get_move(0); + pv[1] = MOVE_NONE; } - std::cout << "bestmove " << ss[0].pv[0]; - if (ss[0].pv[1] != MOVE_NONE) - std::cout << " ponder " << ss[0].pv[1]; - std::cout << std::endl; + assert(pv[0] != MOVE_NONE); + + cout << "bestmove " << pv[0]; + + if (pv[1] != MOVE_NONE) + cout << " ponder " << pv[1]; + + cout << endl; if (UseLogFile) { @@ -843,502 +766,458 @@ namespace { if (dbg_show_hit_rate) dbg_print_hit_rate(LogFile); - StateInfo st; - LogFile << "Nodes: " << nodes_searched() << std::endl - << "Nodes/second: " << nps() << std::endl - << "Best move: " << move_to_san(p, ss[0].pv[0]) << std::endl; + LogFile << "\nNodes: " << TM.nodes_searched() + << "\nNodes/second: " << nps() + << "\nBest move: " << move_to_san(p, pv[0]); - p.do_move(ss[0].pv[0], st); - LogFile << "Ponder move: " << move_to_san(p, ss[0].pv[1]) - << std::endl << std::endl; + StateInfo st; + p.do_move(pv[0], st); + LogFile << "\nPonder move: " + << move_to_san(p, pv[1]) // Works also with MOVE_NONE + << endl; } return rml.get_move_score(0); } - // root_search() is the function which searches the root node. It is + // 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 (perhaps we should try to use this at internal PV nodes, too?) - // 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 alpha, Value beta) { + Value root_search(Position& pos, SearchStack* ss, Move* pv, RootMoveList& rml, Value* alphaPtr, Value* betaPtr) { - Value oldAlpha = alpha; - Value value; + EvalInfo ei; + StateInfo st; CheckInfo ci(pos); + int64_t nodes; + Move move; + Depth depth, ext, newDepth; + Value value, alpha, beta; + bool isCheck, moveIsCheck, captureOrPromotion, dangerous; + int researchCountFH, researchCountFL; + + researchCountFH = researchCountFL = 0; + alpha = *alphaPtr; + beta = *betaPtr; + isCheck = pos.is_check(); - // Loop through all the moves in the root move list - for (int i = 0; i < rml.move_count() && !AbortSearch; i++) + // Step 1. Initialize node and poll (omitted at root, init_ss_array() has already initialized root node) + // Step 2. Check for aborted search (omitted at root) + // 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->eval = evaluate(pos, ei); + + // 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) { - if (alpha >= beta) + // Sort the moves before to (re)search + rml.sort(); + + // Step 10. Loop through all moves in the root move list + for (int i = 0; i < rml.move_count() && !AbortSearch; i++) { - // 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; - } - int64_t nodes; - Move move; - StateInfo st; - Depth ext, newDepth; + // This is used by time management + FirstRootMove = (i == 0); - RootMoveNumber = i + 1; - FailHigh = false; + // Save the current node count before the move is searched + nodes = TM.nodes_searched(); - // Remember the node count before the move is searched. The node counts - // are used to sort the root moves at the next iteration. - nodes = nodes_searched(); + // Reset beta cut-off counters + TM.resetBetaCounters(); - // Reset beta cut-off counters - BetaCounter.clear(); + // Pick the next root move, and print the move and the move number to + // the standard output. + move = ss->currentMove = rml.get_move(i); - // Pick the next root move, and print the move and the move number to - // the standard output. - move = ss[0].currentMove = rml.get_move(i); - if (current_search_time() >= 1000) - std::cout << "info currmove " << move - << " currmovenumber " << i + 1 << std::endl; + if (current_search_time() >= 1000) + cout << "info currmove " << move + << " currmovenumber " << i + 1 << endl; - // Decide search depth for this move - bool moveIsCheck = pos.move_is_check(move); - bool captureOrPromotion = pos.move_is_capture_or_promotion(move); - bool dangerous; - ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, false, false, &dangerous); - newDepth = (Iteration - 2) * OnePly + ext + InitialDepth; + moveIsCheck = pos.move_is_check(move); + captureOrPromotion = pos.move_is_capture_or_promotion(move); - // Make the move, and search it - pos.do_move(move, st, ci, moveIsCheck); + // Step 11. Decide the new search depth + depth = (Iteration - 2) * OnePly + InitialDepth; + ext = extension(pos, move, captureOrPromotion, moveIsCheck, false, false, &dangerous); + newDepth = depth + ext; - if (i < MultiPV) - { - // Aspiration window is disabled in multi-pv case - if (MultiPV > 1) - alpha = -VALUE_INFINITE; - - value = -search_pv(pos, ss, -beta, -alpha, newDepth, 1, 0); - // If the value has dropped a lot compared to the last iteration, - // set the boolean variable Problem to true. This variable is used - // for time managment: When Problem is true, we try to complete the - // current iteration before playing a move. - Problem = (Iteration >= 2 && value <= IterationInfo[Iteration-1].value - ProblemMargin); - - if (Problem && StopOnPonderhit) - StopOnPonderhit = false; - } - else - { - if ( newDepth >= 3*OnePly - && i >= MultiPV + LMRPVMoves - && !dangerous - && !captureOrPromotion - && !move_is_castle(move)) - { - ss[0].reduction = OnePly; - value = -search(pos, ss, -alpha, newDepth-OnePly, 1, true, 0); - } else - value = alpha + 1; // Just to trigger next condition + // Step 12. Futility pruning (omitted at root) - if (value > alpha) - { - value = -search(pos, ss, -alpha, newDepth, 1, true, 0); - if (value > alpha) - { - // Fail high! Set the boolean variable FailHigh to true, and - // re-search the move with a big window. The variable FailHigh is - // used for time managment: We try to avoid aborting the search - // prematurely during a fail high research. - FailHigh = true; - value = -search_pv(pos, ss, -beta, -alpha, newDepth, 1, 0); - } - } - } + // Step extra. Fail high loop + // If move fails high, we research with bigger window until we are not failing + // high anymore. + value = - VALUE_INFINITE; - pos.undo_move(move); + while (1) + { + // Step 13. Make the move + pos.do_move(move, st, ci, moveIsCheck); - // Finished searching the move. If AbortSearch 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 break out of the loop without updating the best - // move and/or PV. - if (AbortSearch) - break; + // 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; - // Remember the node count for this move. The node counts are used to - // sort the root moves at the next iteration. - rml.set_move_nodes(i, nodes_searched() - nodes); + // Full depth PV search, done on first move or after a fail high + value = -search(pos, ss+1, -beta, -alpha, newDepth, 1); + } + else + { + // Step 14. Reduced search + // if the move fails high will be re-searched at full depth + bool doFullDepthSearch = true; + + if ( depth >= 3 * OnePly + && !dangerous + && !captureOrPromotion + && !move_is_castle(move)) + { + ss->reduction = reduction(depth, i - MultiPV + 2); + if (ss->reduction) + { + assert(newDepth-ss->reduction >= OnePly); + + // Reduced depth non-pv search using alpha as upperbound + value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, 1); + doFullDepthSearch = (value > alpha); + } + + // The move failed high, but if reduction is very big we could + // face a false positive, retry with a less aggressive reduction, + // if the move fails high again then go with full depth search. + if (doFullDepthSearch && ss->reduction > 2 * OnePly) + { + assert(newDepth - OnePly >= OnePly); + + ss->reduction = OnePly; + value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, 1); + doFullDepthSearch = (value > alpha); + } + ss->reduction = Depth(0); // Restore original reduction + } + + // Step 15. Full depth search + if (doFullDepthSearch) + { + // Full depth non-pv search using alpha as upperbound + value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth, 1); + + // 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(pos, ss+1, -beta, -alpha, newDepth, 1); + } + } - // Remember the beta-cutoff statistics - int64_t our, their; - BetaCounter.read(pos.side_to_move(), our, their); - rml.set_beta_counters(i, our, their); + // Step 16. Undo move + pos.undo_move(move); - assert(value >= -VALUE_INFINITE && value <= VALUE_INFINITE); + // Can we exit fail high loop ? + if (AbortSearch || value < beta) + break; - if (value <= alpha && i >= MultiPV) - rml.set_move_score(i, -VALUE_INFINITE); - else - { - // PV move or new best move! + // 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); + ss->bestMove = move; + TT.extract_pv(pos, move, pv, PLY_MAX); + rml.set_move_pv(i, pv); + + // Print information to the standard output + print_pv_info(pos, pv, alpha, beta, value); + + // Prepare for a research after a fail high, each time with a wider window + *betaPtr = beta = Min(beta + AspirationDelta * (1 << researchCountFH), VALUE_INFINITE); + researchCountFH++; + + } // End of fail high loop + + // Finished searching the move. If AbortSearch 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 break out of the loop without updating the best + // move and/or PV. + if (AbortSearch) + break; + + // Remember beta-cutoff and searched nodes counts for this move. The + // 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 + { + // PV move or new best move! - // Update PV - 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); + // Update PV + rml.set_move_score(i, value); + ss->bestMove = move; + TT.extract_pv(pos, move, pv, PLY_MAX); + rml.set_move_pv(i, pv); - if (MultiPV == 1) - { - // We record how often the best move has been changed in each - // iteration. This information is used for time managment: When - // the best move changes frequently, we allocate some more time. - if (i > 0) - BestMoveChangesByIteration[Iteration]++; - - // Print search information to the standard output - std::cout << "info depth " << Iteration - << " score " << value_to_string(value) - << ((value >= beta)? - " lowerbound" : ((value <= alpha)? " upperbound" : "")) - << " time " << current_search_time() - << " nodes " << nodes_searched() - << " nps " << nps() - << " pv "; - - for (int j = 0; ss[0].pv[j] != MOVE_NONE && j < PLY_MAX; j++) - std::cout << ss[0].pv[j] << " "; - - std::cout << std::endl; - - if (UseLogFile) - LogFile << pretty_pv(pos, current_search_time(), Iteration, nodes_searched(), value, - ((value >= beta)? VALUE_TYPE_LOWER - : ((value <= alpha)? VALUE_TYPE_UPPER : VALUE_TYPE_EXACT)), - ss[0].pv) - << std::endl; - - if (value > alpha) - alpha = value; - - // Reset the global variable Problem to false if the value isn't too - // far below the final value from the last iteration. - if (value > IterationInfo[Iteration - 1].value - NoProblemMargin) - Problem = false; - } - else // MultiPV > 1 - { - rml.sort_multipv(i); - for (int j = 0; j < Min(MultiPV, rml.move_count()); j++) + if (MultiPV == 1) { - int k; - std::cout << "info multipv " << j + 1 - << " score " << value_to_string(rml.get_move_score(j)) - << " depth " << ((j <= i)? Iteration : Iteration - 1) - << " time " << current_search_time() - << " nodes " << nodes_searched() - << " nps " << nps() - << " pv "; - - for (k = 0; rml.get_move_pv(j, k) != MOVE_NONE && k < PLY_MAX; k++) - std::cout << rml.get_move_pv(j, k) << " "; - - std::cout << std::endl; + // We record how often the best move has been changed in each + // iteration. This information is used for time managment: When + // the best move changes frequently, we allocate some more time. + if (i > 0) + BestMoveChangesByIteration[Iteration]++; + + // Print information to the standard output + print_pv_info(pos, pv, alpha, beta, value); + + // Raise alpha to setup proper non-pv search upper bound + if (value > alpha) + alpha = value; } - alpha = rml.get_move_score(Min(i, MultiPV-1)); - } - } // New best move case + else // MultiPV > 1 + { + rml.sort_multipv(i); + for (int j = 0; j < Min(MultiPV, rml.move_count()); j++) + { + cout << "info multipv " << j + 1 + << " score " << value_to_string(rml.get_move_score(j)) + << " depth " << (j <= i ? Iteration : Iteration - 1) + << " time " << current_search_time() + << " nodes " << TM.nodes_searched() + << " nps " << nps() + << " pv "; + + for (int k = 0; rml.get_move_pv(j, k) != MOVE_NONE && k < PLY_MAX; k++) + cout << rml.get_move_pv(j, k) << " "; + + cout << endl; + } + alpha = rml.get_move_score(Min(i, MultiPV - 1)); + } + } // PV move or new best move - assert(alpha >= oldAlpha); + assert(alpha >= *alphaPtr); - FailLow = (alpha == oldAlpha); - } - return alpha; - } + AspirationFailLow = (alpha == *alphaPtr); + if (AspirationFailLow && StopOnPonderhit) + StopOnPonderhit = false; + } - // search_pv() is the main search function for PV nodes. + // Can we exit fail low loop ? + if (AbortSearch || !AspirationFailLow) + break; - Value search_pv(Position& pos, SearchStack ss[], Value alpha, Value beta, - Depth depth, int ply, int threadID) { + // Prepare for a research after a fail low, each time with a wider window + *alphaPtr = alpha = Max(alpha - AspirationDelta * (1 << researchCountFL), -VALUE_INFINITE); + researchCountFL++; + + } // Fail low loop + + // Sort the moves before to return + rml.sort(); + + return alpha; + } + + + // search<>() is the main search function for both PV and non-PV nodes + + template + Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int ply) { assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE); assert(beta > alpha && beta <= VALUE_INFINITE); - assert(ply >= 0 && ply < PLY_MAX); - assert(threadID >= 0 && threadID < ActiveThreads); + assert(PvNode || alpha == beta - 1); + assert(ply > 0 && ply < PLY_MAX); + assert(pos.thread() >= 0 && pos.thread() < TM.active_threads()); Move movesSearched[256]; EvalInfo ei; StateInfo st; const TTEntry* tte; - Move ttMove, move; + Key posKey; + Move ttMove, move, excludedMove; Depth ext, newDepth; - Value oldAlpha, value; - bool isCheck, mateThreat, singleReply, moveIsCheck, captureOrPromotion, dangerous; + Value bestValue, value, oldAlpha; + Value refinedValue, nullValue, futilityValueScaled; // Non-PV specific + bool isCheck, singleEvasion, moveIsCheck, captureOrPromotion, dangerous; + bool mateThreat = false; int moveCount = 0; - Value bestValue = -VALUE_INFINITE; + int threadID = pos.thread(); + refinedValue = bestValue = value = -VALUE_INFINITE; + oldAlpha = alpha; - if (depth < OnePly) - return qsearch(pos, ss, alpha, beta, Depth(0), ply, threadID); + // Step 1. Initialize node and poll. Polling can abort search + TM.incrementNodeCounter(threadID); + ss->init(); + (ss+2)->initKillers(); - // Initialize, and make an early exit in case of an aborted search, - // an instant draw, maximum ply reached, etc. - init_node(ss, ply, threadID); + if (threadID == 0 && ++NodesSincePoll > NodesBetweenPolls) + { + NodesSincePoll = 0; + poll(); + } - // After init_node() that calls poll() - if (AbortSearch || thread_should_stop(threadID)) + // Step 2. Check for aborted search and immediate draw + if (AbortSearch || TM.thread_should_stop(threadID)) return Value(0); - if (pos.is_draw()) + if (pos.is_draw() || ply >= PLY_MAX - 1) return VALUE_DRAW; - if (ply >= PLY_MAX - 1) - return pos.is_check() ? quick_evaluate(pos) : evaluate(pos, ei, threadID); - - // Mate distance pruning - oldAlpha = alpha; + // Step 3. Mate distance pruning 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. - tte = TT.retrieve(pos.get_key()); + // 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 exists. + excludedMove = ss->excludedMove; + posKey = excludedMove ? pos.get_exclusion_key() : pos.get_key(); + + tte = TT.retrieve(posKey); ttMove = (tte ? tte->move() : MOVE_NONE); - // Go with internal iterative deepening if we don't have a TT move - if (UseIIDAtPVNodes && ttMove == MOVE_NONE && depth >= 5*OnePly) + // 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 + + if (!PvNode && tte && ok_to_use_TT(tte, depth, beta, ply)) { - search_pv(pos, ss, alpha, beta, depth-2*OnePly, ply, threadID); - ttMove = ss[ply].pv[ply]; + // Refresh tte entry to avoid aging + TT.store(posKey, tte->value(), tte->type(), tte->depth(), ttMove, tte->static_value(), tte->king_danger()); + + ss->currentMove = ttMove; // Can be MOVE_NONE + return value_from_tt(tte->value(), ply); } - // Initialize a MovePicker object for the current position, and prepare - // to search all moves + // Step 5. Evaluate the position statically + // At PV nodes we do this only to update gain statistics isCheck = pos.is_check(); - mateThreat = pos.has_mate_threat(opposite_color(pos.side_to_move())); - CheckInfo ci(pos); - MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply]); - - // Loop through all legal moves until no moves remain or a beta cutoff - // occurs. - while ( alpha < beta - && (move = mp.get_next_move()) != MOVE_NONE - && !thread_should_stop(threadID)) + if (!isCheck) { - assert(move_is_ok(move)); - - singleReply = (isCheck && mp.number_of_evasions() == 1); - moveIsCheck = pos.move_is_check(move, ci); - captureOrPromotion = pos.move_is_capture_or_promotion(move); - - movesSearched[moveCount++] = ss[ply].currentMove = move; - - // Decide the new search depth - ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, singleReply, mateThreat, &dangerous); - newDepth = depth - OnePly + ext; - - // Make and search the move - pos.do_move(move, st, ci, moveIsCheck); - - if (moveCount == 1) // The first move in list is the PV - 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, - // if the move fails high will be re-searched at full depth. - if ( depth >= 3*OnePly - && moveCount >= LMRPVMoves - && !dangerous - && !captureOrPromotion - && !move_is_castle(move) - && !move_is_killer(move, ss[ply])) + if (tte && tte->static_value() != VALUE_NONE) { - ss[ply].reduction = OnePly; - value = -search(pos, ss, -alpha, newDepth-OnePly, ply+1, true, threadID); + ss->eval = tte->static_value(); + ei.kingDanger[pos.side_to_move()] = tte->king_danger(); } else - value = alpha + 1; // Just to trigger next condition + ss->eval = evaluate(pos, ei); - if (value > alpha) // Go with full depth non-pv search - { - ss[ply].reduction = Depth(0); - value = -search(pos, ss, -alpha, newDepth, ply+1, true, threadID); - if (value > alpha && value < beta) - { - // When the search fails high at ply 1 while searching the first - // move at the root, set the flag failHighPly1. This is used for - // time managment: We don't want to stop the search early in - // such cases, because resolving the fail high at ply 1 could - // result in a big drop in score at the root. - if (ply == 1 && RootMoveNumber == 1) - Threads[threadID].failHighPly1 = true; - - // A fail high occurred. Re-search at full window (pv search) - value = -search_pv(pos, ss, -beta, -alpha, newDepth, ply+1, threadID); - Threads[threadID].failHighPly1 = false; - } - } - } - pos.undo_move(move); - - assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); - - // New best move? - if (value > bestValue) - { - bestValue = value; - if (value > alpha) - { - alpha = value; - update_pv(ss, ply); - if (value == value_mate_in(ply + 1)) - ss[ply].mateKiller = move; - } - // If we are at ply 1, and we are searching the first root move at - // ply 0, set the 'Problem' variable if the score has dropped a lot - // (from the computer's point of view) since the previous iteration. - if ( ply == 1 - && Iteration >= 2 - && -value <= IterationInfo[Iteration-1].value - ProblemMargin) - Problem = true; - } - - // Split? - if ( ActiveThreads > 1 - && bestValue < beta - && depth >= MinimumSplitDepth - && Iteration <= 99 - && idle_thread_exists(threadID) - && !AbortSearch - && !thread_should_stop(threadID) - && split(pos, ss, ply, &alpha, &beta, &bestValue, VALUE_NONE, VALUE_NONE, - depth, &moveCount, &mp, threadID, true)) - break; + refinedValue = refine_eval(tte, ss->eval, ply); // Enhance accuracy with TT value if possible + update_gains(pos, (ss-1)->currentMove, (ss-1)->eval, ss->eval); } - // All legal moves have been searched. A special case: If there were - // no legal moves, it must be mate or stalemate. - if (moveCount == 0) - return (isCheck ? value_mated_in(ply) : VALUE_DRAW); - - // If the search is not aborted, update the transposition table, - // history counters, and killer moves. - if (AbortSearch || thread_should_stop(threadID)) - return bestValue; - - if (bestValue <= oldAlpha) - TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_UPPER, depth, MOVE_NONE); - - else if (bestValue >= beta) + // Step 6. Razoring (is omitted in PV nodes) + if ( !PvNode + && depth < RazorDepth + && !isCheck + && refinedValue < beta - razor_margin(depth) + && ttMove == MOVE_NONE + && (ss-1)->currentMove != MOVE_NULL + && !value_is_mate(beta) + && !pos.has_pawn_on_7th(pos.side_to_move())) { - BetaCounter.add(pos.side_to_move(), depth, threadID); - move = ss[ply].pv[ply]; - if (!pos.move_is_capture_or_promotion(move)) - { - update_history(pos, move, depth, movesSearched, moveCount); - update_killers(move, ss[ply]); - } - TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, move); - } - else - TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EXACT, depth, ss[ply].pv[ply]); - - return bestValue; - } - - - // search() is the search function for zero-width nodes. - - Value search(Position& pos, SearchStack ss[], Value beta, Depth depth, - int ply, bool allowNullmove, int threadID) { + // Pass ss->eval to qsearch() and avoid an evaluate call + if (!tte || tte->static_value() == VALUE_NONE) + TT.store(posKey, ss->eval, VALUE_TYPE_EXACT, Depth(-127*OnePly), MOVE_NONE, ss->eval, ei.kingDanger[pos.side_to_move()]); - assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE); - assert(ply >= 0 && ply < PLY_MAX); - assert(threadID >= 0 && threadID < ActiveThreads); - - Move movesSearched[256]; - EvalInfo ei; - StateInfo st; - const TTEntry* tte; - Move ttMove, move; - Depth ext, newDepth; - Value approximateEval, nullValue, value, futilityValue, futilityValueScaled; - bool isCheck, useFutilityPruning, singleReply, moveIsCheck, captureOrPromotion, dangerous; - bool mateThreat = false; - int moveCount = 0; - Value bestValue = -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. - init_node(ss, ply, threadID); - - // After init_node() that calls poll() - if (AbortSearch || thread_should_stop(threadID)) - return Value(0); - - if (pos.is_draw()) - return VALUE_DRAW; - - if (ply >= PLY_MAX - 1) - return pos.is_check() ? quick_evaluate(pos) : evaluate(pos, ei, threadID); - - // Mate distance pruning - if (value_mated_in(ply) >= beta) - return beta; - - if (value_mate_in(ply + 1) < beta) - return beta - 1; - - // Transposition table lookup - tte = TT.retrieve(pos.get_key()); - ttMove = (tte ? tte->move() : MOVE_NONE); - - if (tte && ok_to_use_TT(tte, depth, beta, ply)) - { - ss[ply].currentMove = ttMove; // can be MOVE_NONE - return value_from_tt(tte->value(), ply); + Value rbeta = beta - razor_margin(depth); + Value v = qsearch(pos, ss, rbeta-1, rbeta, Depth(0), ply); + if (v < rbeta) + // Logically we should return (v + razor_margin(depth)), but + // surprisingly this did slightly weaker in tests. + return v; } - approximateEval = quick_evaluate(pos); - isCheck = pos.is_check(); - - // Null move search - if ( allowNullmove + // Step 7. Static null move pruning (is omitted in PV nodes) + // 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 ( !PvNode + && !ss->skipNullMove + && depth < RazorDepth + && refinedValue >= beta + futility_margin(depth, 0) + && !isCheck + && !value_is_mate(beta) + && pos.non_pawn_material(pos.side_to_move())) + return refinedValue - futility_margin(depth, 0); + + // Step 8. Null move search with verification search (is omitted in PV nodes) + // 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 ( !PvNode + && !ss->skipNullMove && depth > OnePly + && refinedValue >= beta - (depth >= 4 * OnePly ? NullMoveMargin : 0) && !isCheck && !value_is_mate(beta) - && ok_to_do_nullmove(pos) - && approximateEval >= beta - NullMoveMargin) + && pos.non_pawn_material(pos.side_to_move())) { - ss[ply].currentMove = MOVE_NULL; - - pos.do_null_move(st); + ss->currentMove = MOVE_NULL; // Null move dynamic reduction based on depth - int R = (depth >= 5 * OnePly ? 4 : 3); + int R = 3 + (depth >= 5 * OnePly ? depth / 8 : 0); // Null move dynamic reduction based on value - if (approximateEval - beta > PawnValueMidgame) + if (refinedValue - beta > PawnValueMidgame) R++; - nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID); + pos.do_null_move(st); + (ss+1)->skipNullMove = true; + nullValue = depth-R*OnePly < OnePly ? -qsearch(pos, ss+1, -beta, -alpha, Depth(0), ply+1) + : - search(pos, ss+1, -beta, -alpha, depth-R*OnePly, ply+1); + (ss+1)->skipNullMove = false; pos.undo_null_move(); if (nullValue >= beta) { + // Do not return unproven mate scores + if (nullValue >= value_mate_in(PLY_MAX)) + nullValue = beta; + + // Do zugzwang verification search at high depths if (depth < 6 * OnePly) - return beta; + return nullValue; + + ss->skipNullMove = true; + Value v = search(pos, ss, alpha, beta, depth-5*OnePly, ply); + ss->skipNullMove = false; - // Do zugzwang verification search - Value v = search(pos, ss, beta, depth-5*OnePly, ply, false, threadID); if (v >= beta) - return beta; - } else { + 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 // the move that refuted the null move was somehow connected to the @@ -1348,218 +1227,234 @@ namespace { if (nullValue == value_mated_in(ply + 2)) mateThreat = true; - ss[ply].threatMove = ss[ply + 1].currentMove; + ss->threatMove = (ss+1)->currentMove; if ( depth < ThreatDepth - && ss[ply - 1].reduction - && connected_moves(pos, ss[ply - 1].currentMove, ss[ply].threatMove)) + && (ss-1)->reduction + && connected_moves(pos, (ss-1)->currentMove, ss->threatMove)) return beta - 1; } } - // Null move search not allowed, try razoring - else if ( !value_is_mate(beta) - && depth < RazorDepth - && approximateEval < beta - RazorApprMargins[int(depth) - 2] - && ss[ply - 1].currentMove != MOVE_NULL - && ttMove == MOVE_NONE - && !pos.has_pawn_on_7th(pos.side_to_move())) - { - Value rbeta = beta - RazorMargins[int(depth) - 2]; - 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 && - evaluate(pos, ei, threadID) >= beta - IIDMargin) + // Step 9. Internal iterative deepening + if ( depth >= IIDDepth[PvNode] + && ttMove == MOVE_NONE + && (PvNode || (!isCheck && ss->eval >= beta - IIDMargin))) { - search(pos, ss, beta, Min(depth/2, depth-2*OnePly), ply, false, threadID); - ttMove = ss[ply].pv[ply]; - } + Depth d = (PvNode ? depth - 2 * OnePly : depth / 2); - // Initialize a MovePicker object for the current position, and prepare - // to search all moves. - MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply]); - CheckInfo ci(pos); - futilityValue = VALUE_NONE; - useFutilityPruning = depth < SelectiveDepth && !isCheck; + ss->skipNullMove = true; + search(pos, ss, alpha, beta, d, ply); + ss->skipNullMove = false; - // Avoid calling evaluate() if we already have the score in TT - if (tte && (tte->type() & VALUE_TYPE_EVAL)) - futilityValue = value_from_tt(tte->value(), ply) + FutilityMargins[int(depth) - 2]; + ttMove = ss->bestMove; + tte = TT.retrieve(posKey); + } - // Move count pruning limit - const int MCLimit = 3 + (1 << (3*int(depth)/8)); + // Expensive mate threat detection (only for PV nodes) + if (PvNode) + mateThreat = pos.has_mate_threat(opposite_color(pos.side_to_move())); - // Loop through all legal moves until no moves remain or a beta cutoff - // occurs. + // Initialize a MovePicker object for the current position + MovePicker mp = MovePicker(pos, ttMove, depth, H, ss, (PvNode ? -VALUE_INFINITE : beta)); + CheckInfo ci(pos); + bool singularExtensionNode = depth >= SingularExtensionDepth[PvNode] + && tte && tte->move() + && !excludedMove // Do not allow recursive singular extension search + && is_lower_bound(tte->type()) + && tte->depth() >= depth - 3 * OnePly; + + // 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 - && !thread_should_stop(threadID)) + && !TM.thread_should_stop(threadID)) { assert(move_is_ok(move)); - singleReply = (isCheck && mp.number_of_evasions() == 1); + if (move == excludedMove) + continue; + + singleEvasion = (isCheck && mp.number_of_evasions() == 1); moveIsCheck = pos.move_is_check(move, ci); captureOrPromotion = pos.move_is_capture_or_promotion(move); - movesSearched[moveCount++] = ss[ply].currentMove = move; + // Step 11. Decide the new search depth + ext = extension(pos, move, 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 ( singularExtensionNode + && move == tte->move() + && ext < OnePly) + { + Value ttValue = value_from_tt(tte->value(), ply); + + if (abs(ttValue) < VALUE_KNOWN_WIN) + { + Value b = ttValue - SingularExtensionMargin; + ss->excludedMove = move; + ss->skipNullMove = true; + Value v = search(pos, ss, b - 1, b, depth / 2, ply); + ss->skipNullMove = false; + ss->excludedMove = MOVE_NONE; + if (v < ttValue - SingularExtensionMargin) + ext = OnePly; + } + } - // Decide the new search depth - ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, singleReply, mateThreat, &dangerous); newDepth = depth - OnePly + ext; - // Futility pruning - if ( useFutilityPruning - && !dangerous + // Update current move (this must be done after singular extension search) + movesSearched[moveCount++] = ss->currentMove = move; + + // Step 12. Futility pruning (is omitted in PV nodes) + if ( !PvNode && !captureOrPromotion - && move != ttMove) + && !isCheck + && !dangerous + && move != ttMove + && !move_is_castle(move)) { - //std::cout << std::endl; - //for (int d = 2; d < 14; d++) - // std::cout << d << ", " << 64*(1+bitScanReverse32(d*d)) << std::endl; - - //std::cout << std::endl; -/* - 64*(1+bitScanReverse32(d*d)) - - 2 -> 256 - 256 - 3 -> 288 - 320 - 4 -> 512 - 384 - 5 -> 544 - 384 - 6 -> 592 - 448 - 7 -> 624 - 448 - 8 -> 672 - 512 - 9 -> 704 - 512 - 10 -> 832 - 512 - 11 -> 864 - 512 - 12 -> 928 - 576 - 13 -> 960 - 576 - - 300 + 2*(1 << (3*d/4)) - - 2 -> 256 - 304 - 3 -> 288 - 308 - 4 -> 512 - 316 - 5 -> 544 - 316 - 6 -> 592 - 332 - 7 -> 624 - 364 - 8 -> 672 - 428 - 9 -> 704 - 428 - 10 -> 832 - 556 - 11 -> 864 - 812 - 12 -> 928 - 1324 - 13 -> 960 - 1324 - - - 3 + (1 << (3*int(depth)/8)) - - 1 * onePly - > moveCount >= 4 - 2 * onePly - > moveCount >= 5 - 3 * onePly - > moveCount >= 7 - 4 * onePly - > moveCount >= 11 - 5 * onePly - > moveCount >= 11 - 6 * onePly - > moveCount >= 19 - 7 * onePly - > moveCount >= 35 -*/ - // History pruning. See ok_to_prune() definition - if ( moveCount >= MCLimit - && ok_to_prune(pos, move, ss[ply].threatMove, depth) + // Move count based pruning + if ( moveCount >= futility_move_count(depth) + && !(ss->threatMove && connected_threat(pos, move, ss->threatMove)) && bestValue > value_mated_in(PLY_MAX)) continue; // Value based pruning - if (approximateEval < beta) - { - if (futilityValue == VALUE_NONE) - futilityValue = evaluate(pos, ei, threadID) - + 64*(1+bitScanReverse32(int(depth) * int(depth))) - + 4*IncrementalFutilityMargin; - - futilityValueScaled = futilityValue - moveCount * IncrementalFutilityMargin; + // We illogically ignore reduction condition depth >= 3*OnePly for predicted depth, + // but fixing this made program slightly weaker. + Depth predictedDepth = newDepth - reduction(depth, moveCount); + futilityValueScaled = ss->eval + futility_margin(predictedDepth, moveCount) + + H.gain(pos.piece_on(move_from(move)), move_to(move)); - if (futilityValueScaled < beta) - { - if (futilityValueScaled > bestValue) - bestValue = futilityValueScaled; - continue; - } + if (futilityValueScaled < beta) + { + if (futilityValueScaled > bestValue) + bestValue = futilityValueScaled; + continue; } } - // 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. - if ( depth >= 3*OnePly - && moveCount >= LMRNonPVMoves - && !dangerous - && !captureOrPromotion - && !move_is_castle(move) - && !move_is_killer(move, ss[ply])) - { - ss[ply].reduction = OnePly; - value = -search(pos, ss, -(beta-1), newDepth-OnePly, ply+1, true, threadID); - } + // Step extra. pv search (only in PV nodes) + // The first move in list is the expected PV + if (PvNode && moveCount == 1) + value = newDepth < OnePly ? -qsearch(pos, ss+1, -beta, -alpha, Depth(0), ply+1) + : - search(pos, ss+1, -beta, -alpha, newDepth, ply+1); else - value = beta; // Just to trigger next condition - - if (value >= beta) // Go with full depth non-pv search { - ss[ply].reduction = Depth(0); - value = -search(pos, ss, -(beta-1), newDepth, ply+1, true, threadID); + // Step 14. Reduced depth search + // If the move fails high will be re-searched at full depth. + bool doFullDepthSearch = true; + + if ( depth >= 3 * OnePly + && !captureOrPromotion + && !dangerous + && !move_is_castle(move) + && !move_is_killer(move, ss)) + { + ss->reduction = reduction(depth, moveCount); + if (ss->reduction) + { + Depth d = newDepth - ss->reduction; + value = d < OnePly ? -qsearch(pos, ss+1, -(alpha+1), -alpha, Depth(0), ply+1) + : - search(pos, ss+1, -(alpha+1), -alpha, d, ply+1); + + doFullDepthSearch = (value > alpha); + } + + // The move failed high, but if reduction is very big we could + // face a false positive, retry with a less aggressive reduction, + // if the move fails high again then go with full depth search. + if (doFullDepthSearch && ss->reduction > 2 * OnePly) + { + assert(newDepth - OnePly >= OnePly); + + ss->reduction = OnePly; + value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, ply+1); + doFullDepthSearch = (value > alpha); + } + ss->reduction = Depth(0); // Restore original reduction + } + + // Step 15. Full depth search + if (doFullDepthSearch) + { + value = newDepth < OnePly ? -qsearch(pos, ss+1, -(alpha+1), -alpha, Depth(0), ply+1) + : - search(pos, ss+1, -(alpha+1), -alpha, newDepth, ply+1); + + // Step extra. pv search (only in PV nodes) + // Search only for possible new PV nodes, if instead value >= beta then + // parent node fails low with value <= alpha and tries another move. + if (PvNode && value > alpha && value < beta) + value = newDepth < OnePly ? -qsearch(pos, ss+1, -beta, -alpha, Depth(0), ply+1) + : - search(pos, ss+1, -beta, -alpha, newDepth, ply+1); + } } + + // 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; - if (value >= beta) - update_pv(ss, ply); + bestValue = value; + if (value > alpha) + { + if (PvNode && value < beta) // This guarantees that always: alpha < beta + alpha = value; - if (value == value_mate_in(ply + 1)) - ss[ply].mateKiller = move; + if (value == value_mate_in(ply + 1)) + ss->mateKiller = move; + + ss->bestMove = move; + } } - // Split? - if ( ActiveThreads > 1 + // Step 18. Check for split + if ( depth >= MinimumSplitDepth + && TM.active_threads() > 1 && bestValue < beta - && depth >= MinimumSplitDepth - && Iteration <= 99 - && idle_thread_exists(threadID) + && TM.available_thread_exists(threadID) && !AbortSearch - && !thread_should_stop(threadID) - && split(pos, ss, ply, &beta, &beta, &bestValue, futilityValue, approximateEval, - depth, &moveCount, &mp, threadID, false)) - break; + && !TM.thread_should_stop(threadID) + && Iteration <= 99) + TM.split(pos, ss, ply, &alpha, beta, &bestValue, depth, + mateThreat, &moveCount, &mp, PvNode); } - // 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 (moveCount == 0) - return (pos.is_check() ? value_mated_in(ply) : VALUE_DRAW); + // If one move was excluded return fail low score. + if (!moveCount) + return excludedMove ? oldAlpha : (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 || thread_should_stop(threadID)) + if (AbortSearch || TM.thread_should_stop(threadID)) return bestValue; - if (bestValue < beta) - TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_UPPER, depth, MOVE_NONE); - else + ValueType f = (bestValue <= oldAlpha ? VALUE_TYPE_UPPER : bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT); + move = (bestValue <= oldAlpha ? MOVE_NONE : ss->bestMove); + TT.store(posKey, value_to_tt(bestValue, ply), f, depth, move, ss->eval, ei.kingDanger[pos.side_to_move()]); + + // Update killers and history only for non capture moves that fails high + if (bestValue >= beta) { - BetaCounter.add(pos.side_to_move(), depth, threadID); - move = ss[ply].pv[ply]; + TM.incrementBetaCounter(pos.side_to_move(), depth, threadID); if (!pos.move_is_capture_or_promotion(move)) { update_history(pos, move, depth, movesSearched, moveCount); - update_killers(move, ss[ply]); + update_killers(move, ss); } - TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, move); } assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); @@ -1572,118 +1467,111 @@ namespace { // search function when the remaining depth is zero (or, to be more precise, // less than OnePly). - Value qsearch(Position& pos, SearchStack ss[], Value alpha, Value beta, - Depth depth, int ply, int threadID) { + template + Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int ply) { assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE); assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE); + assert(PvNode || alpha == beta - 1); assert(depth <= 0); - assert(ply >= 0 && ply < PLY_MAX); - assert(threadID >= 0 && threadID < ActiveThreads); + assert(ply > 0 && ply < PLY_MAX); + assert(pos.thread() >= 0 && pos.thread() < TM.active_threads()); EvalInfo ei; StateInfo st; Move ttMove, move; - Value staticValue, bestValue, value, futilityValue; - bool isCheck, enoughMaterial, moveIsCheck; - const TTEntry* tte = NULL; - int moveCount = 0; - bool pvNode = (beta - alpha != 1); - - // Initialize, and make an early exit in case of an aborted search, - // an instant draw, maximum ply reached, etc. - init_node(ss, ply, threadID); + Value bestValue, value, futilityValue, futilityBase; + bool isCheck, deepChecks, enoughMaterial, moveIsCheck, evasionPrunable; + const TTEntry* tte; + Value oldAlpha = alpha; - // After init_node() that calls poll() - if (AbortSearch || thread_should_stop(threadID)) - return Value(0); + TM.incrementNodeCounter(pos.thread()); + ss->bestMove = ss->currentMove = MOVE_NONE; + ss->eval = VALUE_NONE; - if (pos.is_draw()) + // Check for an instant draw or maximum ply reached + if (pos.is_draw() || ply >= PLY_MAX - 1) return VALUE_DRAW; - // Transposition table lookup, only when not in PV - if (!pvNode) - { - tte = TT.retrieve(pos.get_key()); - if (tte && ok_to_use_TT(tte, depth, beta, ply)) - { - assert(tte->type() != VALUE_TYPE_EVAL); + // Transposition table lookup. At PV nodes, we don't use the TT for + // pruning, but only for move ordering. + tte = TT.retrieve(pos.get_key()); + ttMove = (tte ? tte->move() : MOVE_NONE); - return value_from_tt(tte->value(), ply); - } + if (!PvNode && tte && ok_to_use_TT(tte, depth, beta, ply)) + { + ss->currentMove = ttMove; // Can be MOVE_NONE + return value_from_tt(tte->value(), ply); } - ttMove = (tte ? tte->move() : MOVE_NONE); - // Evaluate the position statically isCheck = pos.is_check(); - ei.futilityMargin = Value(0); // Manually initialize futilityMargin + // Evaluate the position statically if (isCheck) - staticValue = -VALUE_INFINITE; - - else if (tte && (tte->type() & VALUE_TYPE_EVAL)) { - // Use the cached evaluation score if possible - assert(ei.futilityMargin == Value(0)); - - staticValue = tte->value(); + bestValue = futilityBase = -VALUE_INFINITE; + deepChecks = enoughMaterial = false; } else - staticValue = evaluate(pos, ei, threadID); + { + if (tte && tte->static_value() != VALUE_NONE) + { + ei.kingDanger[pos.side_to_move()] = tte->king_danger(); + bestValue = tte->static_value(); + } + else + bestValue = evaluate(pos, ei); - if (ply >= PLY_MAX - 1) - return pos.is_check() ? quick_evaluate(pos) : evaluate(pos, ei, threadID); + ss->eval = bestValue; + update_gains(pos, (ss-1)->currentMove, (ss-1)->eval, ss->eval); - // Initialize "stand pat score", and return it immediately if it is - // at least beta. - bestValue = staticValue; + // 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, ply), VALUE_TYPE_LOWER, Depth(-127*OnePly), MOVE_NONE, ss->eval, ei.kingDanger[pos.side_to_move()]); - if (bestValue >= beta) - { - // Store the score to avoid a future costly evaluation() call - if (!isCheck && !tte && ei.futilityMargin == 0) - TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EV_LO, Depth(-127*OnePly), MOVE_NONE); + return bestValue; + } - return bestValue; - } + if (PvNode && bestValue > alpha) + alpha = bestValue; + + // If we are near beta then try to get a cutoff pushing checks a bit further + deepChecks = (depth == -OnePly && bestValue >= beta - PawnValueMidgame / 8); - if (bestValue > alpha) - alpha = bestValue; + // Futility pruning parameters, not needed when in check + futilityBase = bestValue + FutilityMarginQS + ei.kingDanger[pos.side_to_move()]; + enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame; + } // 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 == 0) will be generated. - MovePicker mp = MovePicker(pos, ttMove, depth, H); + // to search the moves. Because the depth is <= 0 here, only captures, + // queen promotions and checks (only if depth == 0 or depth == -OnePly + // and we are near beta) will be generated. + MovePicker mp = MovePicker(pos, ttMove, deepChecks ? Depth(0) : depth, H); CheckInfo ci(pos); - enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame; - // 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) { assert(move_is_ok(move)); - moveCount++; - ss[ply].currentMove = move; - moveIsCheck = pos.move_is_check(move, ci); // Futility pruning - if ( enoughMaterial + if ( !PvNode && !isCheck - && !pvNode && !moveIsCheck && move != ttMove + && enoughMaterial && !move_is_promotion(move) && !pos.move_is_passed_pawn_push(move)) { - futilityValue = staticValue - + Max(pos.midgame_value_of_piece_on(move_to(move)), - pos.endgame_value_of_piece_on(move_to(move))) - + (move_is_ep(move) ? PawnValueEndgame : Value(0)) - + FutilityMarginQS - + ei.futilityMargin; + futilityValue = futilityBase + + pos.endgame_value_of_piece_on(move_to(move)) + + (move_is_ep(move) ? PawnValueEndgame : Value(0)); if (futilityValue < alpha) { @@ -1693,16 +1581,27 @@ namespace { } } - // Don't search captures and checks with negative SEE values - if ( !isCheck + // Detect blocking evasions that are candidate to be pruned + evasionPrunable = isCheck + && 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 ( !PvNode + && (!isCheck || evasionPrunable) && move != ttMove && !move_is_promotion(move) && pos.see_sign(move) < 0) continue; + // Update current move + ss->currentMove = move; + // Make and search the move pos.do_move(move, st, ci, moveIsCheck); - value = -qsearch(pos, ss, -beta, -alpha, depth-OnePly, ply+1, threadID); + value = -qsearch(pos, ss+1, -beta, -alpha, depth-OnePly, ply+1); pos.undo_move(move); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); @@ -1714,36 +1613,27 @@ namespace { if (value > alpha) { alpha = value; - update_pv(ss, ply); + ss->bestMove = move; } } } - // All legal moves have been searched. A special case: If we're in check + // 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 (isCheck && bestValue == -VALUE_INFINITE) return value_mated_in(ply); - assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); - // Update transposition table - move = ss[ply].pv[ply]; - if (!pvNode) - { - // If bestValue isn't changed it means it is still the static evaluation of - // the node, so keep this info to avoid a future costly evaluation() call. - ValueType type = (bestValue == staticValue && !ei.futilityMargin ? VALUE_TYPE_EV_UP : VALUE_TYPE_UPPER); - Depth d = (depth == Depth(0) ? Depth(0) : Depth(-1)); + Depth d = (depth == Depth(0) ? Depth(0) : Depth(-1)); + ValueType f = (bestValue <= oldAlpha ? VALUE_TYPE_UPPER : bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT); + TT.store(pos.get_key(), value_to_tt(bestValue, ply), f, d, ss->bestMove, ss->eval, ei.kingDanger[pos.side_to_move()]); - if (bestValue < beta) - TT.store(pos.get_key(), value_to_tt(bestValue, ply), type, d, MOVE_NONE); - else - TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, d, move); - } + // Update killers only for checking moves that fails high + if ( bestValue >= beta + && !pos.move_is_capture_or_promotion(ss->bestMove)) + update_killers(ss->bestMove, ss); - // Update killers only for good check moves - if (alpha >= beta && !pos.move_is_capture_or_promotion(move)) - update_killers(move, ss[ply]); + assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); return bestValue; } @@ -1757,517 +1647,171 @@ namespace { // also don't need to store anything to the hash table here: This is taken // care of after we return from the split point. + template void sp_search(SplitPoint* sp, int threadID) { - assert(threadID >= 0 && threadID < ActiveThreads); - assert(ActiveThreads > 1); + assert(threadID >= 0 && threadID < TM.active_threads()); + assert(TM.active_threads() > 1); - Position pos = Position(sp->pos); - CheckInfo ci(pos); - SearchStack* ss = sp->sstack[threadID]; - Value value; + StateInfo st; Move move; - bool isCheck = pos.is_check(); - bool useFutilityPruning = sp->depth < SelectiveDepth - && !isCheck; + Depth ext, newDepth; + Value value; + Value futilityValueScaled; // NonPV specific + bool isCheck, moveIsCheck, captureOrPromotion, dangerous; + int moveCount; + value = -VALUE_INFINITE; + + Position pos(*sp->pos, threadID); + CheckInfo ci(pos); + SearchStack* ss = sp->sstack[threadID] + 1; + isCheck = pos.is_check(); + + // 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 - && !thread_should_stop(threadID) - && (move = sp->mp->get_next_move(sp->lock)) != MOVE_NONE) + && (move = sp->mp->get_next_move()) != MOVE_NONE + && !TM.thread_should_stop(threadID)) { - assert(move_is_ok(move)); + moveCount = ++sp->moveCount; + lock_release(&(sp->lock)); - bool moveIsCheck = pos.move_is_check(move, ci); - bool captureOrPromotion = pos.move_is_capture_or_promotion(move); + assert(move_is_ok(move)); - lock_grab(&(sp->lock)); - int moveCount = ++sp->moves; - lock_release(&(sp->lock)); + 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, 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->currentMove = move; - // Prune? - if ( useFutilityPruning + // Step 12. Futility pruning (is omitted in PV nodes) + if ( !PvNode + && !captureOrPromotion + && !isCheck && !dangerous - && !captureOrPromotion) + && !move_is_castle(move)) { - // History pruning. See ok_to_prune() definition - if ( moveCount >= 2 + int(sp->depth) - && ok_to_prune(pos, move, ss[sp->ply].threatMove, sp->depth) + // Move count based pruning + if ( moveCount >= futility_move_count(sp->depth) + && !(ss->threatMove && connected_threat(pos, move, ss->threatMove)) && sp->bestValue > value_mated_in(PLY_MAX)) + { + lock_grab(&(sp->lock)); continue; + } // Value based pruning - if (sp->approximateEval < sp->beta) + Depth predictedDepth = newDepth - reduction(sp->depth, moveCount); + futilityValueScaled = ss->eval + futility_margin(predictedDepth, moveCount) + + H.gain(pos.piece_on(move_from(move)), move_to(move)); + + if (futilityValueScaled < sp->beta) { - if (sp->futilityValue == VALUE_NONE) - { - EvalInfo ei; - sp->futilityValue = evaluate(pos, ei, threadID) - + FutilityMargins[int(sp->depth) - 2]; - } + lock_grab(&(sp->lock)); - if (sp->futilityValue < sp->beta) - { - if (sp->futilityValue > sp->bestValue) // Less then 1% of cases - { - lock_grab(&(sp->lock)); - if (sp->futilityValue > sp->bestValue) - sp->bestValue = sp->futilityValue; - lock_release(&(sp->lock)); - } - continue; - } + 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, - // if the move fails high will be re-searched at full depth. - if ( !dangerous - && moveCount >= LMRNonPVMoves - && !captureOrPromotion - && !move_is_castle(move) - && !move_is_killer(move, ss[sp->ply])) - { - ss[sp->ply].reduction = OnePly; - value = -search(pos, ss, -(sp->beta-1), newDepth - OnePly, sp->ply+1, true, threadID); - } - else - value = sp->beta; // Just to trigger next condition + // Step 14. Reduced search + // If the move fails high will be re-searched at full depth. + bool doFullDepthSearch = true; - if (value >= sp->beta) // Go with full depth non-pv search + if ( !captureOrPromotion + && !dangerous + && !move_is_castle(move) + && !move_is_killer(move, ss)) { - ss[sp->ply].reduction = Depth(0); - value = -search(pos, ss, -(sp->beta - 1), newDepth, sp->ply+1, true, threadID); - } - pos.undo_move(move); - - assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); + ss->reduction = reduction(sp->depth, moveCount); + if (ss->reduction) + { + Value localAlpha = sp->alpha; + Depth d = newDepth - ss->reduction; + value = d < OnePly ? -qsearch(pos, ss+1, -(localAlpha+1), -localAlpha, Depth(0), sp->ply+1) + : - search(pos, ss+1, -(localAlpha+1), -localAlpha, d, sp->ply+1); - if (thread_should_stop(threadID)) - break; + doFullDepthSearch = (value > localAlpha); + } - // New best move? - if (value > sp->bestValue) // Less then 2% of cases - { - lock_grab(&(sp->lock)); - if (value > sp->bestValue && !thread_should_stop(threadID)) + // The move failed high, but if reduction is very big we could + // face a false positive, retry with a less aggressive reduction, + // if the move fails high again then go with full depth search. + if (doFullDepthSearch && ss->reduction > 2 * OnePly) { - sp->bestValue = value; - if (sp->bestValue >= sp->beta) - { - sp_update_pv(sp->parentSstack, ss, sp->ply); - for (int i = 0; i < ActiveThreads; i++) - if (i != threadID && (i == sp->master || sp->slaves[i])) - Threads[i].stop = true; + assert(newDepth - OnePly >= OnePly); - sp->finished = true; - } + ss->reduction = OnePly; + Value localAlpha = sp->alpha; + value = -search(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth-ss->reduction, sp->ply+1); + doFullDepthSearch = (value > localAlpha); } - lock_release(&(sp->lock)); + ss->reduction = Depth(0); // Restore original reduction } - } - - lock_grab(&(sp->lock)); - // 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. - if (sp->master == threadID && thread_should_stop(threadID)) - for (int i = 0; i < ActiveThreads; i++) - if (sp->slaves[i]) - Threads[i].stop = true; - - sp->cpus--; - sp->slaves[threadID] = 0; - - lock_release(&(sp->lock)); - } - - - // sp_search_pv() is used to search from a PV split point. This function - // is called by each thread working at the split point. It is similar to - // the normal search_pv() function, but simpler. Because we have already - // probed the hash table and searched the first move before splitting, we - // don't have to repeat all this work in sp_search_pv(). We also don't - // need to store anything to the hash table here: This is taken care of - // after we return from the split point. - - void sp_search_pv(SplitPoint* sp, int threadID) { - - assert(threadID >= 0 && threadID < ActiveThreads); - assert(ActiveThreads > 1); - - Position pos = Position(sp->pos); - CheckInfo ci(pos); - SearchStack* ss = sp->sstack[threadID]; - Value value; - Move move; - - while ( sp->alpha < sp->beta - && !thread_should_stop(threadID) - && (move = sp->mp->get_next_move(sp->lock)) != MOVE_NONE) - { - bool moveIsCheck = pos.move_is_check(move, ci); - bool captureOrPromotion = pos.move_is_capture_or_promotion(move); - - assert(move_is_ok(move)); - - lock_grab(&(sp->lock)); - int moveCount = ++sp->moves; - lock_release(&(sp->lock)); - - 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; - - // Make and search the move. - StateInfo st; - 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. - if ( !dangerous - && moveCount >= LMRPVMoves - && !captureOrPromotion - && !move_is_castle(move) - && !move_is_killer(move, ss[sp->ply])) + // Step 15. Full depth search + if (doFullDepthSearch) { - ss[sp->ply].reduction = OnePly; - value = -search(pos, ss, -sp->alpha, newDepth - OnePly, sp->ply+1, true, threadID); + Value localAlpha = sp->alpha; + value = newDepth < OnePly ? -qsearch(pos, ss+1, -(localAlpha+1), -localAlpha, Depth(0), sp->ply+1) + : - search(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth, sp->ply+1); + + // Step extra. pv search (only in PV nodes) + // Search only for possible new PV nodes, if instead value >= beta then + // parent node fails low with value <= alpha and tries another move. + if (PvNode && value > localAlpha && value < sp->beta) + value = newDepth < OnePly ? -qsearch(pos, ss+1, -sp->beta, -sp->alpha, Depth(0), sp->ply+1) + : - search(pos, ss+1, -sp->beta, -sp->alpha, newDepth, sp->ply+1); } - else - value = sp->alpha + 1; // Just to trigger next condition - if (value > sp->alpha) // Go with full depth non-pv search - { - ss[sp->ply].reduction = Depth(0); - value = -search(pos, ss, -sp->alpha, newDepth, sp->ply+1, true, threadID); - - if (value > sp->alpha && value < sp->beta) - { - // When the search fails high at ply 1 while searching the first - // move at the root, set the flag failHighPly1. This is used for - // time managment: We don't want to stop the search early in - // such cases, because resolving the fail high at ply 1 could - // result in a big drop in score at the root. - if (sp->ply == 1 && RootMoveNumber == 1) - Threads[threadID].failHighPly1 = true; - - value = -search_pv(pos, ss, -sp->beta, -sp->alpha, newDepth, sp->ply+1, threadID); - Threads[threadID].failHighPly1 = false; - } - } + // Step 16. Undo move pos.undo_move(move); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); - if (thread_should_stop(threadID)) - break; - - // New best move? + // Step 17. Check for new best move lock_grab(&(sp->lock)); - if (value > sp->bestValue && !thread_should_stop(threadID)) + + if (value > sp->bestValue && !TM.thread_should_stop(threadID)) { sp->bestValue = value; - if (value > sp->alpha) + + if (sp->bestValue > sp->alpha) { - sp->alpha = value; - sp_update_pv(sp->parentSstack, ss, sp->ply); - if (value == value_mate_in(sp->ply + 1)) - ss[sp->ply].mateKiller = move; + if (!PvNode || value >= sp->beta) + sp->stopRequest = true; - if (value >= sp->beta) - { - for (int i = 0; i < ActiveThreads; i++) - if (i != threadID && (i == sp->master || sp->slaves[i])) - Threads[i].stop = true; + if (PvNode && value < sp->beta) // This guarantees that always: sp->alpha < sp->beta + sp->alpha = value; - sp->finished = true; - } - } - // If we are at ply 1, and we are searching the first root move at - // ply 0, set the 'Problem' variable if the score has dropped a lot - // (from the computer's point of view) since the previous iteration. - if ( sp->ply == 1 - && Iteration >= 2 - && -value <= IterationInfo[Iteration-1].value - ProblemMargin) - Problem = true; + sp->parentSstack->bestMove = ss->bestMove = move; + } } - lock_release(&(sp->lock)); } - lock_grab(&(sp->lock)); - - // 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. - if (sp->master == threadID && thread_should_stop(threadID)) - for (int i = 0; i < ActiveThreads; i++) - if (sp->slaves[i]) - Threads[i].stop = true; + /* Here we have the lock still grabbed */ - sp->cpus--; sp->slaves[threadID] = 0; lock_release(&(sp->lock)); } - /// The BetaCounterType class - - BetaCounterType::BetaCounterType() { clear(); } - - void BetaCounterType::clear() { - - for (int i = 0; i < THREAD_MAX; i++) - Threads[i].betaCutOffs[WHITE] = Threads[i].betaCutOffs[BLACK] = 0ULL; - } - - void BetaCounterType::add(Color us, Depth d, int threadID) { - - // Weighted count based on depth - Threads[threadID].betaCutOffs[us] += unsigned(d); - } - - void BetaCounterType::read(Color us, int64_t& our, int64_t& their) { - - our = their = 0UL; - for (int i = 0; i < THREAD_MAX; i++) - { - our += Threads[i].betaCutOffs[us]; - their += Threads[i].betaCutOffs[opposite_color(us)]; - } - } - - - /// The RootMove class - - // Constructor - - RootMove::RootMove() { - nodes = cumulativeNodes = ourBeta = theirBeta = 0ULL; - } - - // 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 a higher score, or if the moves - // have equal score but m1 has the higher node count. - - bool RootMove::operator<(const RootMove& m) { - - if (score != m.score) - return (score < m.score); - - return theirBeta <= m.theirBeta; - } - - /// The RootMoveList class - - // Constructor - - RootMoveList::RootMoveList(Position& pos, Move searchMoves[]) : count(0) { - - MoveStack mlist[MaxRootMoves]; - bool includeAllMoves = (searchMoves[0] == MOVE_NONE); - - // Generate all legal moves - MoveStack* last = generate_moves(pos, mlist); - - // Add each move to the moves[] array - for (MoveStack* cur = mlist; cur != last; cur++) - { - bool includeMove = includeAllMoves; - - for (int k = 0; !includeMove && searchMoves[k] != MOVE_NONE; k++) - includeMove = (searchMoves[k] == cur->move); - - if (!includeMove) - continue; - - // Find a quick score for the move - StateInfo st; - SearchStack ss[PLY_MAX_PLUS_2]; - init_ss_array(ss); - - moves[count].move = cur->move; - pos.do_move(moves[count].move, st); - moves[count].score = -qsearch(pos, ss, -VALUE_INFINITE, VALUE_INFINITE, Depth(0), 1, 0); - pos.undo_move(moves[count].move); - moves[count].pv[0] = moves[count].move; - moves[count].pv[1] = MOVE_NONE; // FIXME - count++; - } - sort(); - } - - - // Simple accessor methods for the RootMoveList class - - inline Move RootMoveList::get_move(int moveNum) const { - return moves[moveNum].move; - } - - inline Value RootMoveList::get_move_score(int moveNum) const { - return moves[moveNum].score; - } - - inline void RootMoveList::set_move_score(int moveNum, Value score) { - moves[moveNum].score = score; - } - - inline void RootMoveList::set_move_nodes(int moveNum, int64_t nodes) { - moves[moveNum].nodes = nodes; - moves[moveNum].cumulativeNodes += nodes; - } - - inline void RootMoveList::set_beta_counters(int moveNum, int64_t our, int64_t their) { - moves[moveNum].ourBeta = our; - moves[moveNum].theirBeta = their; - } - - void RootMoveList::set_move_pv(int moveNum, const Move pv[]) { - int j; - for(j = 0; pv[j] != MOVE_NONE; j++) - moves[moveNum].pv[j] = pv[j]; - moves[moveNum].pv[j] = MOVE_NONE; - } - - inline Move RootMoveList::get_move_pv(int moveNum, int i) const { - return moves[moveNum].pv[i]; - } - - inline int64_t RootMoveList::get_move_cumulative_nodes(int moveNum) const { - return moves[moveNum].cumulativeNodes; - } - - inline int RootMoveList::move_count() const { - return count; - } - - - // RootMoveList::scan_for_easy_move() is called at the end of the first - // iteration, and is used to detect an "easy move", i.e. a move which appears - // to be much bester than all the rest. If an easy move is found, the move - // is returned, otherwise the function returns MOVE_NONE. It is very - // important that this function is called at the right moment: The code - // assumes that the first iteration has been completed and the moves have - // been sorted. This is done in RootMoveList c'tor. - - Move RootMoveList::scan_for_easy_move() const { - - assert(count); - - if (count == 1) - return get_move(0); - - // moves are sorted so just consider the best and the second one - if (get_move_score(0) > get_move_score(1) + EasyMoveMargin) - return get_move(0); - - return MOVE_NONE; - } - - // RootMoveList::sort() sorts the root move list at the beginning of a new - // iteration. - - inline void RootMoveList::sort() { - - sort_multipv(count - 1); // all items - } - - - // RootMoveList::sort_multipv() sorts the first few moves in the root move - // list by their scores and depths. It is used to order the different PVs - // correctly in MultiPV mode. - - void RootMoveList::sort_multipv(int n) { - - for (int i = 1; i <= n; i++) - { - RootMove rm = moves[i]; - int j; - for (j = i; j > 0 && moves[j-1] < rm; j--) - moves[j] = moves[j-1]; - moves[j] = rm; - } - } - - - // init_node() is called at the beginning of all the search functions - // (search(), search_pv(), qsearch(), and so on) and initializes the search - // stack object corresponding to the current node. Once every - // NodesBetweenPolls nodes, init_node() also calls poll(), which polls - // for user input and checks whether it is time to stop the search. - - void init_node(SearchStack ss[], int ply, int threadID) { - - assert(ply >= 0 && ply < PLY_MAX); - assert(threadID >= 0 && threadID < ActiveThreads); - - Threads[threadID].nodes++; - - if (threadID == 0) - { - NodesSincePoll++; - if (NodesSincePoll >= NodesBetweenPolls) - { - poll(); - NodesSincePoll = 0; - } - } - ss[ply].init(ply); - ss[ply+2].initKillers(); - - if (Threads[threadID].printCurrentLine) - print_current_line(ss, ply, threadID); - } - - - // update_pv() is called whenever a search returns a value > alpha. It - // updates the PV in the SearchStack object corresponding to the current - // node. - - void update_pv(SearchStack ss[], int ply) { - assert(ply >= 0 && ply < PLY_MAX); - - ss[ply].pv[ply] = ss[ply].currentMove; - int p; - for(p = ply + 1; ss[ply+1].pv[p] != MOVE_NONE; p++) - ss[ply].pv[p] = ss[ply+1].pv[p]; - ss[ply].pv[p] = MOVE_NONE; - } - - - // sp_update_pv() is a variant of update_pv for use at split points. The - // difference between the two functions is that sp_update_pv also updates - // the PV at the parent node. - - void sp_update_pv(SearchStack* pss, SearchStack ss[], int ply) { - assert(ply >= 0 && ply < PLY_MAX); - - ss[ply].pv[ply] = pss[ply].pv[ply] = ss[ply].currentMove; - int p; - for(p = ply + 1; ss[ply+1].pv[p] != MOVE_NONE; p++) - ss[ply].pv[p] = pss[ply].pv[p] = ss[ply+1].pv[p]; - ss[ply].pv[p] = pss[ply].pv[p] = MOVE_NONE; - } - // connected_moves() tests whether two moves are 'connected' in the sense // that the first move somehow made the second move possible (for instance - // if the moving piece is the same in both moves). The first move is - // assumed to be the move that was made to reach the current position, while - // the second move is assumed to be a move from the current position. + // if the moving piece is the same in both moves). The first move is assumed + // to be the move that was made to reach the current position, while the + // second move is assumed to be a move from the current position. bool connected_moves(const Position& pos, Move m1, Move m2) { @@ -2297,36 +1841,23 @@ namespace { && bit_is_set(squares_between(f2, t2), f1)) return true; - // Case 4: The destination square for m2 is attacked by the moving piece in m1 + // Case 4: The destination square for m2 is defended by the moving piece in m1 p = pos.piece_on(t1); if (bit_is_set(pos.attacks_from(p, t1), t2)) return true; // Case 5: Discovered check, checking piece is the piece moved in m1 - if ( piece_is_slider(p) - && bit_is_set(squares_between(t1, pos.king_square(pos.side_to_move())), f2) + if ( piece_is_slider(p) + && bit_is_set(squares_between(t1, pos.king_square(pos.side_to_move())), f2) && !bit_is_set(squares_between(t1, pos.king_square(pos.side_to_move())), t2)) { - Bitboard occ = pos.occupied_squares(); - Color us = pos.side_to_move(); - Square ksq = pos.king_square(us); - clear_bit(&occ, f2); - if (type_of_piece(p) == BISHOP) - { - if (bit_is_set(bishop_attacks_bb(ksq, occ), t1)) - return true; - } - else if (type_of_piece(p) == ROOK) - { - if (bit_is_set(rook_attacks_bb(ksq, occ), t1)) - return true; - } - else - { - assert(type_of_piece(p) == QUEEN); - if (bit_is_set(queen_attacks_bb(ksq, occ), t1)) - return true; - } + // discovered_check_candidates() works also if the Position's side to + // move is the opposite of the checking piece. + Color them = opposite_color(pos.side_to_move()); + Bitboard dcCandidates = pos.discovered_check_candidates(them); + + if (bit_is_set(dcCandidates, f2)) + return true; } return false; } @@ -2347,9 +1878,9 @@ namespace { // move_is_killer() checks if the given move is among the // killer moves of that ply. - bool move_is_killer(Move m, const SearchStack& ss) { + bool move_is_killer(Move m, SearchStack* ss) { - const Move* k = ss.killers; + const Move* k = ss->killers; for (int i = 0; i < KILLER_MAX; i++, k++) if (*k == m) return true; @@ -2359,30 +1890,30 @@ namespace { // extension() decides whether a move should be searched with normal depth, - // or with extended depth. Certain classes of moves (checking moves, in + // or with extended depth. Certain classes of moves (checking moves, in // particular) are searched with bigger depth than ordinary moves and in // any case are marked as 'dangerous'. Note that also if a move is not // extended, as example because the corresponding UCI option is set to zero, // the move is marked as 'dangerous' so, at least, we avoid to prune it. - - Depth extension(const Position& pos, Move m, bool pvNode, bool captureOrPromotion, - bool check, bool singleReply, bool mateThreat, bool* dangerous) { + template + Depth extension(const Position& pos, Move m, bool captureOrPromotion, bool moveIsCheck, + bool singleEvasion, bool mateThreat, bool* dangerous) { assert(m != MOVE_NONE); Depth result = Depth(0); - *dangerous = check | singleReply | mateThreat; + *dangerous = moveIsCheck | singleEvasion | mateThreat; if (*dangerous) { - if (check) - result += CheckExtension[pvNode]; + if (moveIsCheck && pos.see_sign(m) >= 0) + result += CheckExtension[PvNode]; - if (singleReply) - result += SingleReplyExtension[pvNode]; + if (singleEvasion) + result += SingleEvasionExtension[PvNode]; if (mateThreat) - result += MateThreatExtension[pvNode]; + result += MateThreatExtension[PvNode]; } if (pos.type_of_piece_on(move_from(m)) == PAWN) @@ -2390,12 +1921,12 @@ namespace { Color c = pos.side_to_move(); if (relative_rank(c, move_to(m)) == RANK_7) { - result += PawnPushTo7thExtension[pvNode]; + result += PawnPushTo7thExtension[PvNode]; *dangerous = true; } if (pos.pawn_is_passed(c, move_to(m))) { - result += PassedPawnExtension[pvNode]; + result += PassedPawnExtension[PvNode]; *dangerous = true; } } @@ -2407,11 +1938,11 @@ namespace { && !move_is_promotion(m) && !move_is_ep(m)) { - result += PawnEndgameExtension[pvNode]; + result += PawnEndgameExtension[PvNode]; *dangerous = true; } - if ( pvNode + if ( PvNode && captureOrPromotion && pos.type_of_piece_on(move_to(m)) != PAWN && pos.see_sign(m) >= 0) @@ -2424,32 +1955,16 @@ namespace { } - // ok_to_do_nullmove() looks at the current position and decides whether - // doing a 'null move' should be allowed. In order to avoid zugzwang - // problems, null moves are not allowed when the side to move has very - // little material left. Currently, the test is a bit too simple: Null - // moves are avoided only when the side to move has only pawns left. It's - // probably a good idea to avoid null moves in at least some more - // complicated endgames, e.g. KQ vs KR. FIXME - - bool ok_to_do_nullmove(const Position& pos) { - - return pos.non_pawn_material(pos.side_to_move()) != Value(0); - } - - - // ok_to_prune() tests whether it is safe to forward prune a move. Only - // non-tactical moves late in the move list close to the leaves are - // candidates for pruning. + // connected_threat() tests whether it is safe to forward prune a move or if + // is somehow coonected to the threat move returned by null search. - bool ok_to_prune(const Position& pos, Move m, Move threat, Depth d) { + bool connected_threat(const Position& pos, Move m, Move threat) { assert(move_is_ok(m)); - assert(threat == MOVE_NONE || move_is_ok(threat)); + assert(threat && move_is_ok(threat)); assert(!pos.move_is_check(m)); assert(!pos.move_is_capture_or_promotion(m)); assert(!pos.move_is_passed_pawn_push(m)); - assert(d >= OnePly); Square mfrom, mto, tfrom, tto; @@ -2458,38 +1973,26 @@ namespace { tfrom = move_from(threat); tto = move_to(threat); - // Case 1: Castling moves are never pruned - if (move_is_castle(m)) - return false; - - // Case 2: Don't prune moves which move the threatened piece - if (!PruneEscapeMoves && threat != MOVE_NONE && mfrom == tto) - return false; + // Case 1: Don't prune moves which move the threatened piece + if (mfrom == tto) + return true; - // Case 3: If the threatened piece has value less than or equal to the + // Case 2: If the threatened piece has value less than or equal to the // value of the threatening piece, don't prune move which defend it. - if ( !PruneDefendingMoves - && threat != MOVE_NONE - && pos.move_is_capture(threat) + if ( pos.move_is_capture(threat) && ( pos.midgame_value_of_piece_on(tfrom) >= pos.midgame_value_of_piece_on(tto) || pos.type_of_piece_on(tfrom) == KING) && pos.move_attacks_square(m, tto)) - return false; - - // Case 4: Don't prune moves with good history - if (!H.ok_to_prune(pos.piece_on(mfrom), mto, d)) - return false; + return true; - // Case 5: If the moving piece in the threatened move is a slider, don't + // Case 3: If the moving piece in the threatened move is a slider, don't // prune safe moves which block its ray. - if ( !PruneBlockingMoves - && threat != MOVE_NONE - && piece_is_slider(pos.piece_on(tfrom)) + if ( piece_is_slider(pos.piece_on(tfrom)) && bit_is_set(squares_between(tfrom, tto), mto) && pos.see_sign(m) >= 0) - return false; + return true; - return true; + return false; } @@ -2498,30 +2001,53 @@ namespace { bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply) { - Value v = value_from_tt(tte->value(), ply); + Value v = value_from_tt(tte->value(), ply); + + return ( tte->depth() >= depth + || v >= Max(value_mate_in(PLY_MAX), beta) + || v < Min(value_mated_in(PLY_MAX), beta)) + + && ( (is_lower_bound(tte->type()) && v >= beta) + || (is_upper_bound(tte->type()) && v < beta)); + } + + + // 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) { + + if (!tte) + return defaultEval; + + Value v = value_from_tt(tte->value(), ply); - return ( tte->depth() >= depth - || v >= Max(value_mate_in(100), beta) - || v < Min(value_mated_in(100), beta)) + if ( (is_lower_bound(tte->type()) && v >= defaultEval) + || (is_upper_bound(tte->type()) && v < defaultEval)) + return v; - && ( (is_lower_bound(tte->type()) && v >= beta) - || (is_upper_bound(tte->type()) && v < beta)); + 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 m, Depth depth, + void update_history(const Position& pos, Move move, Depth depth, Move movesSearched[], int moveCount) { - H.success(pos.piece_on(move_from(m)), move_to(m), depth); + Move m; + + H.success(pos.piece_on(move_from(move)), move_to(move), depth); for (int i = 0; i < moveCount - 1; i++) { - assert(m != movesSearched[i]); - if (!pos.move_is_capture_or_promotion(movesSearched[i])) - H.failure(pos.piece_on(move_from(movesSearched[i])), move_to(movesSearched[i])); + m = movesSearched[i]; + + assert(m != move); + + if (!pos.move_is_capture_or_promotion(m)) + H.failure(pos.piece_on(move_from(m)), move_to(m), depth); } } @@ -2529,29 +2055,30 @@ namespace { // update_killers() add a good move that produced a beta-cutoff // among the killer moves of that ply. - void update_killers(Move m, SearchStack& ss) { + void update_killers(Move m, SearchStack* ss) { - if (m == ss.killers[0]) + if (m == ss->killers[0]) return; for (int i = KILLER_MAX - 1; i > 0; i--) - ss.killers[i] = ss.killers[i - 1]; + ss->killers[i] = ss->killers[i - 1]; - ss.killers[0] = m; + ss->killers[0] = m; } - // fail_high_ply_1() checks if some thread is currently resolving a fail - // high at ply 1 at the node below the first root node. This information - // is used for time managment. + // update_gains() updates the gains table of a non-capture move given + // the static position evaluation before and after the move. - bool fail_high_ply_1() { + void update_gains(const Position& pos, Move m, Value before, Value after) { - for(int i = 0; i < ActiveThreads; i++) - if (Threads[i].failHighPly1) - return true; - - return false; + if ( m != MOVE_NULL + && before != VALUE_NONE + && after != VALUE_NONE + && pos.captured_piece() == NO_PIECE_TYPE + && !move_is_castle(m) + && !move_is_promotion(m)) + H.set_gain(pos.piece_on(move_to(m)), move_to(m), -(before + after)); } @@ -2559,6 +2086,7 @@ namespace { // since the beginning of the current search. int current_search_time() { + return get_system_time() - SearchStartTime; } @@ -2566,12 +2094,13 @@ namespace { // nps() computes the current nodes/second count. int nps() { + int t = current_search_time(); - return (t > 0)? int((nodes_searched() * 1000) / t) : 0; + return (t > 0 ? int((TM.nodes_searched() * 1000) / t) : 0); } - // poll() performs two different functions: It polls for user input, and it + // poll() performs two different functions: It polls for user input, and it // looks at the time consumed so far and decides if it's time to abort the // search. @@ -2585,6 +2114,7 @@ namespace { { // We are line oriented, don't read single chars std::string command; + if (!std::getline(std::cin, command)) command = "quit"; @@ -2603,6 +2133,7 @@ namespace { else if (command == "ponderhit") ponderhit(); } + // Print search information if (t < 1000) lastInfoTime = 0; @@ -2615,31 +2146,31 @@ namespace { else if (t - lastInfoTime >= 1000) { lastInfoTime = t; - lock_grab(&IOLock); + if (dbg_show_mean) dbg_print_mean(); if (dbg_show_hit_rate) dbg_print_hit_rate(); - std::cout << "info nodes " << nodes_searched() << " nps " << nps() - << " time " << t << " hashfull " << TT.full() << std::endl; - lock_release(&IOLock); - if (ShowCurrentLine) - Threads[0].printCurrentLine = true; + cout << "info nodes " << TM.nodes_searched() << " nps " << nps() + << " time " << t << " hashfull " << TT.full() << endl; } + // Should we stop the search? if (PonderSearch) return; - bool overTime = t > AbsoluteMaxSearchTime - || (RootMoveNumber == 1 && t > MaxSearchTime + ExtraSearchTime && !FailLow) //FIXME: We are not checking any problem flags, BUG? - || ( !FailHigh && !FailLow && !fail_high_ply_1() && !Problem - && t > 6*(MaxSearchTime + ExtraSearchTime)); + bool stillAtFirstMove = FirstRootMove + && !AspirationFailLow + && t > MaxSearchTime + ExtraSearchTime; + + bool noMoreTime = t > AbsoluteMaxSearchTime + || stillAtFirstMove; - if ( (Iteration >= 3 && (!InfiniteSearch && overTime)) + if ( (Iteration >= 3 && UseTimeManagement && noMoreTime) || (ExactMaxTime && t >= ExactMaxTime) - || (Iteration >= 3 && MaxNodes && nodes_searched() >= MaxNodes)) + || (Iteration >= 3 && MaxNodes && TM.nodes_searched() >= MaxNodes)) AbortSearch = true; } @@ -2652,56 +2183,41 @@ namespace { int t = current_search_time(); PonderSearch = false; - if (Iteration >= 3 && - (!InfiniteSearch && (StopOnPonderhit || - t > AbsoluteMaxSearchTime || - (RootMoveNumber == 1 && - t > MaxSearchTime + ExtraSearchTime && !FailLow) || - (!FailHigh && !FailLow && !fail_high_ply_1() && !Problem && - t > 6*(MaxSearchTime + ExtraSearchTime))))) - AbortSearch = true; - } - - // print_current_line() prints the current line of search for a given - // thread. Called when the UCI option UCI_ShowCurrLine is 'true'. + bool stillAtFirstMove = FirstRootMove + && !AspirationFailLow + && t > MaxSearchTime + ExtraSearchTime; - void print_current_line(SearchStack ss[], int ply, int threadID) { - - assert(ply >= 0 && ply < PLY_MAX); - assert(threadID >= 0 && threadID < ActiveThreads); - - if (!Threads[threadID].idle) - { - lock_grab(&IOLock); - std::cout << "info currline " << (threadID + 1); - for (int p = 0; p < ply; p++) - std::cout << " " << ss[p].currentMove; + bool noMoreTime = t > AbsoluteMaxSearchTime + || stillAtFirstMove; - std::cout << std::endl; - lock_release(&IOLock); - } - Threads[threadID].printCurrentLine = false; - if (threadID + 1 < ActiveThreads) - Threads[threadID + 1].printCurrentLine = true; + if (Iteration >= 3 && UseTimeManagement && (noMoreTime || StopOnPonderhit)) + AbortSearch = true; } - // init_ss_array() does a fast reset of the first entries of a SearchStack array + // init_ss_array() does a fast reset of the first entries of a SearchStack + // array and of all the excludedMove and skipNullMove entries. - void init_ss_array(SearchStack ss[]) { + void init_ss_array(SearchStack* ss, int size) { - for (int i = 0; i < 3; i++) + for (int i = 0; i < size; i++, ss++) { - ss[i].init(i); - ss[i].initKillers(); + ss->excludedMove = MOVE_NONE; + ss->skipNullMove = false; + + if (i < 3) + { + ss->init(); + ss->initKillers(); + } } } // wait_for_stop_or_ponderhit() is called when the maximum depth is reached - // while the program is pondering. The point is to work around a wrinkle in - // the UCI protocol: When pondering, the engine is not allowed to give a + // while the program is pondering. The point is to work around a wrinkle in + // the UCI protocol: When pondering, the engine is not allowed to give a // "bestmove" before the GUI sends it a "stop" or "ponderhit" command. // We simply wait here until one of these commands is sent, and return, // after which the bestmove and pondermove will be printed (in id_loop()). @@ -2726,296 +2242,573 @@ 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, Move* pv, 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; pv[j] != MOVE_NONE && j < PLY_MAX; j++) + cout << 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, 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 + // threads and one for Windows threads. + +#if !defined(_MSC_VER) + + void* init_thread(void *threadID) { + + TM.idle_loop(*(int*)threadID, NULL); + return NULL; + } + +#else + + DWORD WINAPI init_thread(LPVOID threadID) { + + TM.idle_loop(*(int*)threadID, NULL); + return 0; + } + +#endif + + + /// The ThreadsManager class + + // resetNodeCounters(), resetBetaCounters(), searched_nodes() and + // get_beta_counters() are getters/setters for the per thread + // counters used to sort the moves at root. + + void ThreadsManager::resetNodeCounters() { + + for (int i = 0; i < MAX_THREADS; i++) + threads[i].nodes = 0ULL; + } + + void ThreadsManager::resetBetaCounters() { + + for (int i = 0; i < MAX_THREADS; i++) + threads[i].betaCutOffs[WHITE] = threads[i].betaCutOffs[BLACK] = 0ULL; + } + + int64_t ThreadsManager::nodes_searched() const { + + int64_t result = 0ULL; + for (int i = 0; i < ActiveThreads; i++) + result += threads[i].nodes; + + return result; + } + + void ThreadsManager::get_beta_counters(Color us, int64_t& our, int64_t& their) const { + + our = their = 0UL; + for (int i = 0; i < MAX_THREADS; i++) + { + our += threads[i].betaCutOffs[us]; + their += threads[i].betaCutOffs[opposite_color(us)]; + } + } + + // idle_loop() is where the threads are parked when they have no work to do. - // The parameter "waitSp", if non-NULL, is a pointer to an active SplitPoint + // The parameter 'sp', if non-NULL, is a pointer to an active SplitPoint // object for which the current thread is the master. - void idle_loop(int threadID, SplitPoint* waitSp) { - assert(threadID >= 0 && threadID < THREAD_MAX); + void ThreadsManager::idle_loop(int threadID, SplitPoint* sp) { + + assert(threadID >= 0 && threadID < MAX_THREADS); - Threads[threadID].running = true; + while (true) + { + // Slave threads can exit as soon as AllThreadsShouldExit raises, + // master should exit as last one. + if (AllThreadsShouldExit) + { + assert(!sp); + threads[threadID].state = THREAD_TERMINATED; + return; + } - while(true) { - if(AllThreadsShouldExit && threadID != 0) - break; + // If we are not thinking, wait for a condition to be signaled + // instead of wasting CPU time polling for work. + while (AllThreadsShouldSleep || threadID >= ActiveThreads) + { + assert(!sp); + assert(threadID != 0); + threads[threadID].state = THREAD_SLEEPING; - // If we are not thinking, wait for a condition to be signaled instead - // of wasting CPU time polling for work: - while(threadID != 0 && (Idle || threadID >= ActiveThreads)) { #if !defined(_MSC_VER) - pthread_mutex_lock(&WaitLock); - if(Idle || threadID >= ActiveThreads) - pthread_cond_wait(&WaitCond, &WaitLock); - pthread_mutex_unlock(&WaitLock); + lock_grab(&WaitLock); + if (AllThreadsShouldSleep || threadID >= ActiveThreads) + pthread_cond_wait(&WaitCond, &WaitLock); + lock_release(&WaitLock); #else - WaitForSingleObject(SitIdleEvent[threadID], INFINITE); + WaitForSingleObject(SitIdleEvent[threadID], INFINITE); #endif - } + } - // If this thread has been assigned work, launch a search - if(Threads[threadID].workIsWaiting) { - 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; - } + // If thread has just woken up, mark it as available + if (threads[threadID].state == THREAD_SLEEPING) + 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) - return; - } + // If this thread has been assigned work, launch a search + if (threads[threadID].state == THREAD_WORKISWAITING) + { + assert(!AllThreadsShouldExit && !AllThreadsShouldSleep); + + threads[threadID].state = THREAD_SEARCHING; + + if (threads[threadID].splitPoint->pvNode) + sp_search(threads[threadID].splitPoint, threadID); + else + sp_search(threads[threadID].splitPoint, threadID); + + assert(threads[threadID].state == THREAD_SEARCHING); + + threads[threadID].state = THREAD_AVAILABLE; + } - Threads[threadID].running = false; + // 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. + int i = 0; + for ( ; sp && i < ActiveThreads && !sp->slaves[i]; i++) {} + + if (i == ActiveThreads) + { + // Because sp->slaves[] is reset under lock protection, + // be sure sp->lock has been released before to return. + lock_grab(&(sp->lock)); + lock_release(&(sp->lock)); + + assert(threads[threadID].state == THREAD_AVAILABLE); + + threads[threadID].state = THREAD_SEARCHING; + return; + } + } } - // init_split_point_stack() is called during program initialization, and - // initializes all split point objects. + // init_threads() is called during startup. It launches all helper threads, + // and initializes the split point stack and the global locks and condition + // objects. - void init_split_point_stack() { - for(int i = 0; i < THREAD_MAX; i++) - for(int j = 0; j < MaxActiveSplitPoints; j++) { - SplitPointStack[i][j].parent = NULL; - lock_init(&(SplitPointStack[i][j].lock), NULL); - } + void ThreadsManager::init_threads() { + + volatile int i; + bool ok; + +#if !defined(_MSC_VER) + pthread_t pthread[1]; +#endif + + // Initialize global locks + lock_init(&MPLock, 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 (i = 0; i < MAX_THREADS; i++) + for (int j = 0; j < ACTIVE_SPLIT_POINTS_MAX; j++) + lock_init(&(SplitPointStack[i][j].lock), NULL); + + // 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 THREAD_AVAILABLE + ActiveThreads = 1; + 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 < MAX_THREADS; i++) + { + +#if !defined(_MSC_VER) + ok = (pthread_create(pthread, NULL, init_thread, (void*)(&i)) == 0); +#else + ok = (CreateThread(NULL, 0, init_thread, (LPVOID)(&i), 0, NULL) != NULL); +#endif + + if (!ok) + { + cout << "Failed to create thread number " << i << endl; + Application::exit_with_failure(); + } + + // Wait until the thread has finished launching and is gone to sleep + while (threads[i].state != THREAD_SLEEPING) {} + } } - // destroy_split_point_stack() is called when the program exits, and - // destroys all locks in the precomputed split point objects. + // exit_threads() is called when the program exits. It makes all the + // helper threads exit cleanly. - void destroy_split_point_stack() { - for(int i = 0; i < THREAD_MAX; i++) - for(int j = 0; j < MaxActiveSplitPoints; j++) - lock_destroy(&(SplitPointStack[i][j].lock)); + void ThreadsManager::exit_threads() { + + ActiveThreads = MAX_THREADS; // HACK + AllThreadsShouldSleep = true; // HACK + wake_sleeping_threads(); + + // This makes the threads to exit idle_loop() + AllThreadsShouldExit = true; + + // 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 < 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 occured in thre 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 { - bool thread_should_stop(int threadID) { assert(threadID >= 0 && threadID < ActiveThreads); SplitPoint* sp; - if(Threads[threadID].stop) - return true; - if(ActiveThreads <= 2) - return false; - for(sp = Threads[threadID].splitPoint; sp != NULL; sp = sp->parent) - if(sp->finished) { - Threads[threadID].stop = true; - return true; - } - return false; + for (sp = threads[threadID].splitPoint; sp && !sp->stopRequest; sp = sp->parent) {} + return sp != NULL; } // thread_is_available() checks whether the thread with threadID "slave" is - // available to help the thread with threadID "master" at a split point. An - // obvious requirement is that "slave" must be idle. With more than two + // available to help the thread with threadID "master" at a split point. An + // obvious requirement is that "slave" must be idle. With more than two // threads, this is not by itself sufficient: If "slave" is the master of // some active split point, it is only available as a slave to the other // threads which are busy searching the split point at the top of "slave"'s // split point stack (the "helpful master concept" in YBWC terminology). - bool thread_is_available(int slave, int master) { + bool ThreadsManager::thread_is_available(int slave, int master) const { + assert(slave >= 0 && slave < ActiveThreads); assert(master >= 0 && master < ActiveThreads); assert(ActiveThreads > 1); - if(!Threads[slave].idle || slave == master) - return false; + if (threads[slave].state != THREAD_AVAILABLE || slave == master) + return false; - if(Threads[slave].activeSplitPoints == 0) - // No active split points means that the thread is available as a slave - // for any other thread. - return true; + // Make a local copy to be sure doesn't change under our feet + int localActiveSplitPoints = threads[slave].activeSplitPoints; - if(ActiveThreads == 2) - return true; + if (localActiveSplitPoints == 0) + // No active split points means that the thread is available as + // a slave for any other thread. + return true; - // Apply the "helpful master" concept if possible. - if(SplitPointStack[slave][Threads[slave].activeSplitPoints-1].slaves[master]) - return true; + if (ActiveThreads == 2) + return true; + + // Apply the "helpful master" concept if possible. Use localActiveSplitPoints + // that is known to be > 0, instead of threads[slave].activeSplitPoints that + // could have been set to 0 by another thread leading to an out of bound access. + if (SplitPointStack[slave][localActiveSplitPoints - 1].slaves[master]) + return true; return false; } - // 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 idle_thread_exists(int master) { + bool ThreadsManager::available_thread_exists(int master) const { + assert(master >= 0 && master < ActiveThreads); assert(ActiveThreads > 1); - for(int i = 0; i < ActiveThreads; i++) - if(thread_is_available(i, master)) - return true; + for (int i = 0; i < ActiveThreads; i++) + if (thread_is_available(i, master)) + return true; + return false; } // split() does the actual work of distributing the work at a node between - // several threads at PV nodes. If it does not succeed in splitting the + // several available threads. If it does not succeed in splitting the // node (because no idle threads are available, or because we have no unused - // split point objects), the function immediately returns false. If - // splitting is possible, a SplitPoint object is initialized with all the - // data that must be copied to the helper threads (the current position and - // search stack, alpha, beta, the search depth, etc.), and we tell our - // helper threads that they have been assigned work. This will cause them - // to instantly leave their idle loops and call sp_search_pv(). When all - // threads have returned from sp_search_pv (or, equivalently, when - // splitPoint->cpus becomes 0), split() returns true. - - bool split(const Position& p, SearchStack* sstck, int ply, - Value* alpha, Value* beta, Value* bestValue, const Value futilityValue, - const Value approximateEval, Depth depth, int* moves, - MovePicker* mp, int master, bool pvNode) { - + // split point objects), the function immediately returns. If splitting is + // possible, a SplitPoint object is initialized with all the data that must be + // copied to the helper threads and we tell our helper threads that they have + // been assigned work. This will cause them to instantly leave their idle loops + // and call sp_search(). When all threads have returned from sp_search() then + // split() returns. + + template + void ThreadsManager::split(const Position& p, SearchStack* ss, int ply, Value* alpha, + const Value beta, Value* bestValue, Depth depth, bool mateThreat, + int* moveCount, MovePicker* mp, 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(ply > 0 && ply < PLY_MAX); + assert(*bestValue >= -VALUE_INFINITE); + assert(*bestValue <= *alpha); + assert(*alpha < beta); + assert(beta <= VALUE_INFINITE); assert(depth > Depth(0)); - assert(master >= 0 && master < ActiveThreads); + assert(p.thread() >= 0 && p.thread() < ActiveThreads); assert(ActiveThreads > 1); - SplitPoint* splitPoint; - int i; + int master = p.thread(); lock_grab(&MPLock); // 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) || - Threads[master].activeSplitPoints >= MaxActiveSplitPoints) { - lock_release(&MPLock); - return false; + if ( !available_thread_exists(master) + || threads[master].activeSplitPoints >= ACTIVE_SPLIT_POINTS_MAX) + { + lock_release(&MPLock); + return; } // Pick the next available split point object from the split point stack - splitPoint = SplitPointStack[master] + Threads[master].activeSplitPoints; - Threads[master].activeSplitPoints++; + SplitPoint* splitPoint = &SplitPointStack[master][threads[master].activeSplitPoints]; // Initialize the split point object - splitPoint->parent = Threads[master].splitPoint; - splitPoint->finished = false; + splitPoint->parent = threads[master].splitPoint; + splitPoint->stopRequest = false; splitPoint->ply = ply; splitPoint->depth = depth; - splitPoint->alpha = pvNode? *alpha : (*beta - 1); - splitPoint->beta = *beta; + splitPoint->mateThreat = mateThreat; + splitPoint->alpha = *alpha; + splitPoint->beta = beta; splitPoint->pvNode = pvNode; splitPoint->bestValue = *bestValue; - splitPoint->futilityValue = futilityValue; - splitPoint->approximateEval = approximateEval; - splitPoint->master = master; splitPoint->mp = mp; - splitPoint->moves = *moves; - splitPoint->cpus = 1; - splitPoint->pos.copy(p); - splitPoint->parentSstack = sstck; - for(i = 0; i < ActiveThreads; i++) - splitPoint->slaves[i] = 0; - - // Copy the current position and the search stack to the master thread - memcpy(splitPoint->sstack[master], sstck, (ply+1)*sizeof(SearchStack)); - Threads[master].splitPoint = splitPoint; - - // Make copies of the current position and search stack for each thread - for(i = 0; i < ActiveThreads && splitPoint->cpus < MaxThreadsPerSplitPoint; - i++) - if(thread_is_available(i, master)) { - memcpy(splitPoint->sstack[i], sstck, (ply+1)*sizeof(SearchStack)); - Threads[i].splitPoint = splitPoint; - splitPoint->slaves[i] = 1; - splitPoint->cpus++; - } + splitPoint->moveCount = *moveCount; + splitPoint->pos = &p; + splitPoint->parentSstack = ss; + for (int i = 0; i < ActiveThreads; i++) + splitPoint->slaves[i] = 0; - // Tell the threads that they have work to do. This will make them leave - // their idle loop. - for(i = 0; i < ActiveThreads; i++) - if(i == master || splitPoint->slaves[i]) { - Threads[i].workIsWaiting = true; - Threads[i].idle = false; - Threads[i].stop = false; - } + threads[master].splitPoint = splitPoint; + threads[master].activeSplitPoints++; + // If we are here it means we are not available + assert(threads[master].state != THREAD_AVAILABLE); + + int workersCnt = 1; // At least the master is included + + // Allocate available threads setting state to THREAD_BOOKED + for (int i = 0; !Fake && i < ActiveThreads && workersCnt < MaxThreadsPerSplitPoint; i++) + if (thread_is_available(i, master)) + { + threads[i].state = THREAD_BOOKED; + threads[i].splitPoint = splitPoint; + splitPoint->slaves[i] = 1; + workersCnt++; + } + + assert(Fake || workersCnt > 1); + + // We can release the lock because slave threads are already booked and master is not available lock_release(&MPLock); - // 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 + // Tell the threads that they have work to do. This will make them leave + // their idle loop. But before copy search stack tail for each thread. + for (int i = 0; i < ActiveThreads; i++) + if (i == master || splitPoint->slaves[i]) + { + memcpy(splitPoint->sstack[i], ss - 1, 4 * sizeof(SearchStack)); + + 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 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). + // loop when all threads have finished their work at this split point. idle_loop(master, splitPoint); // We have returned from the idle loop, which means that all threads are - // finished. Update alpha, beta and bestvalue, and return. + // finished. Update alpha and bestValue, and return. lock_grab(&MPLock); - if(pvNode) *alpha = splitPoint->alpha; - *beta = splitPoint->beta; + + *alpha = splitPoint->alpha; *bestValue = splitPoint->bestValue; - Threads[master].stop = false; - Threads[master].idle = false; - Threads[master].activeSplitPoints--; - Threads[master].splitPoint = splitPoint->parent; - lock_release(&MPLock); + threads[master].activeSplitPoints--; + threads[master].splitPoint = splitPoint->parent; - return true; + lock_release(&MPLock); } // wake_sleeping_threads() wakes up all sleeping threads when it is time // to start a new search from the root. - void wake_sleeping_threads() { - if(ActiveThreads > 1) { - for(int i = 1; i < ActiveThreads; i++) { - Threads[i].idle = true; - Threads[i].workIsWaiting = false; - } + void ThreadsManager::wake_sleeping_threads() { + + assert(AllThreadsShouldSleep); + assert(ActiveThreads > 0); + + AllThreadsShouldSleep = false; + + if (ActiveThreads == 1) + return; + #if !defined(_MSC_VER) - pthread_mutex_lock(&WaitLock); - pthread_cond_broadcast(&WaitCond); - pthread_mutex_unlock(&WaitLock); + 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 + + } + + + // 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 + // 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; + } + + /// The RootMoveList class + + // RootMoveList c'tor + + RootMoveList::RootMoveList(Position& pos, Move searchMoves[]) : count(0) { + + SearchStack ss[PLY_MAX_PLUS_2]; + MoveStack mlist[MaxRootMoves]; + StateInfo st; + bool includeAllMoves = (searchMoves[0] == MOVE_NONE); + + // Generate all legal moves + MoveStack* last = generate_moves(pos, mlist); + + // Add each move to the moves[] array + for (MoveStack* cur = mlist; cur != last; cur++) + { + bool includeMove = includeAllMoves; + + for (int k = 0; !includeMove && searchMoves[k] != MOVE_NONE; k++) + includeMove = (searchMoves[k] == cur->move); + + if (!includeMove) + continue; + + // Find a quick score for the move + init_ss_array(ss, PLY_MAX_PLUS_2); + pos.do_move(cur->move, st); + moves[count].move = cur->move; + moves[count].score = -qsearch(pos, ss+1, -VALUE_INFINITE, VALUE_INFINITE, Depth(0), 1); + moves[count].pv[0] = cur->move; + moves[count].pv[1] = MOVE_NONE; + pos.undo_move(cur->move); + count++; } + sort(); } - // 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 threads - // and one for Windows threads. + // RootMoveList simple methods definitions -#if !defined(_MSC_VER) + void RootMoveList::set_move_nodes(int moveNum, int64_t nodes) { - void *init_thread(void *threadID) { - idle_loop(*(int *)threadID, NULL); - return NULL; + moves[moveNum].nodes = nodes; + moves[moveNum].cumulativeNodes += nodes; } -#else + void RootMoveList::set_beta_counters(int moveNum, int64_t our, int64_t their) { - DWORD WINAPI init_thread(LPVOID threadID) { - idle_loop(*(int *)threadID, NULL); - return NULL; + moves[moveNum].ourBeta = our; + moves[moveNum].theirBeta = their; } -#endif + void RootMoveList::set_move_pv(int moveNum, const Move pv[]) { -} + int j; + + for (j = 0; pv[j] != MOVE_NONE; j++) + moves[moveNum].pv[j] = pv[j]; + + moves[moveNum].pv[j] = MOVE_NONE; + } + + + // RootMoveList::sort() sorts the root move list at the beginning of a new + // iteration. + + void RootMoveList::sort() { + + sort_multipv(count - 1); // Sort all items + } + + + // RootMoveList::sort_multipv() sorts the first few moves in the root move + // list by their scores and depths. It is used to order the different PVs + // correctly in MultiPV mode. + + void RootMoveList::sort_multipv(int n) { + + int i,j; + + for (i = 1; i <= n; i++) + { + RootMove rm = moves[i]; + for (j = i; j > 0 && moves[j - 1] < rm; j--) + moves[j] = moves[j - 1]; + + moves[j] = rm; + } + } + +} // namspace