X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fsearch.cpp;h=6f9c8b2bdd14f8e7736288b06f532c3fc934c731;hb=339e1b49f619ceffa75019e196adf4de74b32cce;hp=4f8401bbb651ea62cbc5761d8a0b91614f31f3bd;hpb=726df58131dd6e6c54a53fa9e0fe0756bcfc203b;p=stockfish diff --git a/src/search.cpp b/src/search.cpp index 4f8401bb..751049cd 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -17,27 +17,23 @@ along with this program. If not, see . */ - -//// -//// Includes -//// - #include #include #include #include #include #include +#include #include "book.h" #include "evaluate.h" #include "history.h" #include "misc.h" +#include "move.h" #include "movegen.h" #include "movepick.h" -#include "lock.h" -#include "san.h" #include "search.h" +#include "timeman.h" #include "thread.h" #include "tt.h" #include "ucioption.h" @@ -45,147 +41,107 @@ using std::cout; using std::endl; -//// -//// Local definitions -//// - namespace { - /// Types + // Different node types, used as template parameter enum NodeType { NonPV, PV }; - // Set to true to force running with one thread. - // Used for debugging SMP code. + // Set to true to force running with one thread. Used for debugging. 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); - - private: - friend void poll(); - - int ActiveThreads; - volatile bool AllThreadsShouldExit, AllThreadsShouldSleep; - Thread threads[MAX_THREADS]; - SplitPoint SplitPointStack[MAX_THREADS][ACTIVE_SPLIT_POINTS_MAX]; - - Lock MPLock, WaitLock; - -#if !defined(_MSC_VER) - pthread_cond_t WaitCond; -#else - HANDLE SitIdleEvent[MAX_THREADS]; -#endif - - }; - + // Lookup table to check if a Piece is a slider and its access function + const bool Slidings[18] = { 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1 }; + inline bool piece_is_slider(Piece p) { return Slidings[p]; } - // 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). + // RootMove struct is used for moves at the root of the tree. For each root + // move, we store two scores, a node count, and a PV (really a refutation + // in the case of moves which fail low). Value pv_score is normally set at + // -VALUE_INFINITE for all non-pv moves, while non_pv_score is computed + // according to the order in which moves are returned by MovePicker. struct RootMove { - RootMove() { nodes = cumulativeNodes = ourBeta = theirBeta = 0ULL; } + RootMove(); + RootMove(const RootMove& rm) { *this = rm; } + RootMove& operator=(const RootMove& rm); // 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. + // than a move m2 if it has an higher pv_score, or if it has + // equal pv_score but m1 has the higher non_pv_score. In this way + // we are guaranteed that PV moves are always sorted as first. bool operator<(const RootMove& m) const { - - return score != m.score ? score < m.score : theirBeta <= m.theirBeta; + return pv_score != m.pv_score ? pv_score < m.pv_score + : non_pv_score < m.non_pv_score; } - Move move; - Value score; - int64_t nodes, cumulativeNodes, ourBeta, theirBeta; + void extract_pv_from_tt(Position& pos); + void insert_pv_in_tt(Position& pos); + std::string pv_info_to_uci(Position& pos, int depth, int selDepth, + Value alpha, Value beta, int pvIdx); + int64_t nodes; + Value pv_score; + Value non_pv_score; Move pv[PLY_MAX_PLUS_2]; }; - // The RootMoveList class is essentially an array of RootMove objects, with - // a handful of methods for accessing the data in the individual moves. + // RootMoveList struct is just a vector of RootMove objects, + // with an handful of methods above the standard ones. - class RootMoveList { + struct RootMoveList : public std::vector { - public: - RootMoveList(Position& pos, Move searchMoves[]); + typedef std::vector Base; - 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 init(Position& pos, Move searchMoves[]); + void sort() { insertion_sort(begin(), end()); } + void sort_multipv(int n) { insertion_sort(begin(), begin() + n); } - 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[]); - void sort(); - void sort_multipv(int n); - - private: - static const int MaxRootMoves = 500; - RootMove moves[MaxRootMoves]; - int count; + int bestMoveChanges; }; + // Overload operator<<() to make it easier to print moves in a coordinate + // notation compatible with UCI protocol. + std::ostream& operator<<(std::ostream& os, Move m) { + + bool chess960 = (os.iword(0) != 0); // See set960() + return os << move_to_uci(m, chess960); + } + + + // When formatting a move for std::cout we must know if we are in Chess960 + // or not. To keep using the handy operator<<() on the move the trick is to + // embed this flag in the stream itself. Function-like named enum set960 is + // used as a custom manipulator and the stream internal general-purpose array, + // accessed through ios_base::iword(), is used to pass the flag to the move's + // operator<<() that will read it to properly format castling moves. + enum set960 {}; + + std::ostream& operator<< (std::ostream& os, const set960& f) { + + os.iword(0) = int(f); + return os; + } + + /// Adjustments // Step 6. Razoring // Maximum depth for razoring - const Depth RazorDepth = 4 * OnePly; + const Depth RazorDepth = 4 * ONE_PLY; // Dynamic razoring margin based on depth inline Value razor_margin(Depth d) { return Value(0x200 + 0x10 * int(d)); } - // Step 8. Null move search with verification search - - // Null move margin. A null move search will not be done if the static - // evaluation of the position is more than NullMoveMargin below beta. - const Value NullMoveMargin = Value(0x200); - // Maximum depth for use of dynamic threat detection when null move fails low - const Depth ThreatDepth = 5 * OnePly; + const Depth ThreatDepth = 5 * ONE_PLY; // Step 9. Internal iterative deepening // Minimum depth for use of internal iterative deepening - const Depth IIDDepth[2] = { 8 * OnePly /* non-PV */, 5 * OnePly /* PV */}; + const Depth IIDDepth[] = { 8 * ONE_PLY, 5 * ONE_PLY }; // At Non-PV nodes we do an internal iterative deepening search // when the static evaluation is bigger then beta - IIDMargin. @@ -193,965 +149,679 @@ namespace { // Step 11. Decide the new search depth - // Extensions. Configurable UCI options - // Array index 0 is used at non-PV nodes, index 1 at PV nodes. - Depth CheckExtension[2], SingleEvasionExtension[2], PawnPushTo7thExtension[2]; - Depth PassedPawnExtension[2], PawnEndgameExtension[2], MateThreatExtension[2]; + // Extensions. Array index 0 is used for non-PV nodes, index 1 for PV nodes + const Depth CheckExtension[] = { ONE_PLY / 2, ONE_PLY / 1 }; + const Depth PawnEndgameExtension[] = { ONE_PLY / 1, ONE_PLY / 1 }; + const Depth PawnPushTo7thExtension[] = { ONE_PLY / 2, ONE_PLY / 2 }; + const Depth PassedPawnExtension[] = { DEPTH_ZERO, ONE_PLY / 2 }; // Minimum depth for use of singular extension - const Depth SingularExtensionDepth[2] = { 8 * OnePly /* non-PV */, 6 * OnePly /* PV */}; - - // If the TT move is at least SingularExtensionMargin better then the - // remaining ones we will extend it. - const Value SingularExtensionMargin = Value(0x20); + const Depth SingularExtensionDepth[] = { 8 * ONE_PLY, 6 * ONE_PLY }; // Step 12. Futility pruning // Futility margin for quiescence search const Value FutilityMarginQS = Value(0x80); - // Futility lookup tables (initialized at startup) and their getter functions - int32_t FutilityMarginsMatrix[16][64]; // [depth][moveNumber] - int FutilityMoveCountArray[32]; // [depth] + // Futility lookup tables (initialized at startup) and their access functions + Value FutilityMargins[16][64]; // [depth][moveNumber] + int FutilityMoveCounts[32]; // [depth] - inline Value futility_margin(Depth d, int mn) { return Value(d < 7 * OnePly ? FutilityMarginsMatrix[Max(d, 0)][Min(mn, 63)] : 2 * VALUE_INFINITE); } - inline int futility_move_count(Depth d) { return d < 16 * OnePly ? FutilityMoveCountArray[d] : 512; } + inline Value futility_margin(Depth d, int mn) { - // Step 14. Reduced search + return d < 7 * ONE_PLY ? FutilityMargins[Max(d, 1)][Min(mn, 63)] + : 2 * VALUE_INFINITE; + } + + inline int futility_move_count(Depth d) { - // Reduction lookup tables (initialized at startup) and their getter functions - int8_t ReductionMatrix[2][64][64]; // [pv][depth][moveNumber] + return d < 16 * ONE_PLY ? FutilityMoveCounts[d] : MAX_MOVES; + } + + // Step 14. Reduced search - template - inline Depth reduction(Depth d, int mn) { return (Depth) ReductionMatrix[PV][Min(d / 2, 63)][Min(mn, 63)]; } + // Reduction lookup tables (initialized at startup) and their access function + int8_t Reductions[2][64][64]; // [pv][depth][moveNumber] - // Common adjustments + template inline Depth reduction(Depth d, int mn) { - // Search depth at iteration 1 - const Depth InitialDepth = OnePly; + return (Depth) Reductions[PV][Min(d / ONE_PLY, 63)][Min(mn, 63)]; + } // Easy move margin. An easy move candidate must be at least this much // better than the second best move. const Value EasyMoveMargin = Value(0x200); - // Last seconds noise filtering (LSN) - const bool UseLSNFiltering = false; - const int LSNTime = 100; // In milliseconds - const Value LSNValue = value_from_centipawns(200); - bool loseOnTime = false; + /// Namespace variables - /// Global variables + // Book + Book OpeningBook; - // Iteration counter - int Iteration; - - // Scores and number of times the best move changed for each iteration - Value ValueByIteration[PLY_MAX_PLUS_2]; - int BestMoveChangesByIteration[PLY_MAX_PLUS_2]; - - // Search window management - int AspirationDelta; + // Root move list + RootMoveList Rml; // MultiPV mode - int MultiPV; + int MultiPV, UCIMultiPV; - // Time managment variables - int SearchStartTime, MaxNodes, MaxDepth, MaxSearchTime; - int AbsoluteMaxSearchTime, ExtraSearchTime, ExactMaxTime; - bool UseTimeManagement, InfiniteSearch, PonderSearch, StopOnPonderhit; - bool FirstRootMove, AbortSearch, Quit, AspirationFailLow; + // Time management variables + bool StopOnPonderhit, FirstRootMove, StopRequest, QuitRequest, AspirationFailLow; + TimeManager TimeMgr; + SearchLimits Limits; // Log file - bool UseLogFile; std::ofstream LogFile; - // Multi-threads related variables - Depth MinimumSplitDepth; - int MaxThreadsPerSplitPoint; - ThreadsManager TM; + // Skill level adjustment + int SkillLevel; + bool SkillLevelEnabled; + RKISS RK; // 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. + bool SendSearchedNodes; int NodesSincePoll; int NodesBetweenPolls = 30000; // History table History H; + /// Local functions - Value id_loop(const Position& pos, Move searchMoves[]); - Value root_search(Position& pos, SearchStack* ss, RootMoveList& rml, Value* alphaPtr, Value* betaPtr); + Move id_loop(Position& pos, Move searchMoves[], Move* ponderMove); - template - Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int ply); + template + Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth); template - Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int ply); + Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth); template - void sp_search(SplitPoint* sp, int threadID); + inline Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth) { + + return depth < ONE_PLY ? qsearch(pos, ss, alpha, beta, DEPTH_ZERO) + : search(pos, ss, alpha, beta, depth); + } template - Depth extension(const Position& pos, Move m, bool captureOrPromotion, bool moveIsCheck, bool singleEvasion, bool mateThreat, bool* dangerous); + Depth extension(const Position& pos, Move m, bool captureOrPromotion, bool moveIsCheck, bool* dangerous); - void update_pv(SearchStack* ss); - void sp_update_pv(SearchStack* pss, SearchStack* ss); + bool check_is_dangerous(Position &pos, Move move, Value futilityBase, Value beta, Value *bValue); bool connected_moves(const Position& pos, Move m1, Move m2); - bool value_is_mate(Value value); - bool move_is_killer(Move m, SearchStack* ss); + Value value_to_tt(Value v, int ply); + Value value_from_tt(Value v, int ply); bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply); bool connected_threat(const Position& pos, Move m, Move threat); Value refine_eval(const TTEntry* tte, Value defaultEval, int ply); void update_history(const Position& pos, Move move, Depth depth, Move movesSearched[], int moveCount); - void update_killers(Move m, SearchStack* ss); void update_gains(const Position& pos, Move move, Value before, Value after); + void do_skill_level(Move* best, Move* ponder); - int current_search_time(); - int nps(); - void poll(); - void ponderhit(); + int current_search_time(int set = 0); + std::string value_to_uci(Value v); + std::string speed_to_uci(int64_t nodes); + void poll(const Position& pos); void wait_for_stop_or_ponderhit(); - void init_ss_array(SearchStack* ss, int size); - void print_pv_info(const Position& pos, SearchStack* ss, Value alpha, Value beta, Value value); -#if !defined(_MSC_VER) - void *init_thread(void *threadID); -#else - DWORD WINAPI init_thread(LPVOID threadID); -#endif -} + // MovePickerExt is an extended MovePicker class used to choose at compile time + // the proper move source according to the type of node. + template struct MovePickerExt; + + // In Root nodes use RootMoveList as source. Score and sort the root moves + // before to search them. + template<> struct MovePickerExt : public MovePicker { + + MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b) + : MovePicker(p, ttm, d, h, ss, b), firstCall(true) { + Move move; + Value score = VALUE_ZERO; + + // Score root moves using standard ordering used in main search, the moves + // are scored according to the order in which they are returned by MovePicker. + // This is the second order score that is used to compare the moves when + // the first orders pv_score of both moves are equal. + while ((move = MovePicker::get_next_move()) != MOVE_NONE) + for (rm = Rml.begin(); rm != Rml.end(); ++rm) + if (rm->pv[0] == move) + { + rm->non_pv_score = score--; + break; + } + + Rml.sort(); + rm = Rml.begin(); + } + + Move get_next_move() { + + if (!firstCall) + ++rm; + else + firstCall = false; + + return rm != Rml.end() ? rm->pv[0] : MOVE_NONE; + } + + RootMoveList::iterator rm; + bool firstCall; + }; + + // In SpNodes use split point's shared MovePicker object as move source + template<> struct MovePickerExt : public MovePicker { + + MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b) + : MovePicker(p, ttm, d, h, ss, b), mp(ss->sp->mp) {} + + Move get_next_move() { return mp->get_next_move(); } + RootMoveList::iterator rm; // Dummy, needed to compile + MovePicker* mp; + }; + + // Default case, create and use a MovePicker object as source + template<> struct MovePickerExt : public MovePicker { -//// -//// Functions -//// + MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b) + : MovePicker(p, ttm, d, h, ss, b) {} -/// init_threads(), exit_threads() and nodes_searched() are helpers to -/// give accessibility to some TM methods from outside of current file. + RootMoveList::iterator rm; // Dummy, needed to compile + }; -void init_threads() { TM.init_threads(); } -void exit_threads() { TM.exit_threads(); } -int64_t nodes_searched() { return TM.nodes_searched(); } +} // namespace -/// init_search() is called during startup. It initializes various lookup tables +/// init_search() is called during startup to initialize various lookup tables void init_search() { - int d; // depth (OnePly == 2) - int hd; // half depth (OnePly == 1) + int d; // depth (ONE_PLY == 2) + int hd; // half depth (ONE_PLY == 1) int mc; // moveCount // Init reductions array for (hd = 1; hd < 64; hd++) for (mc = 1; mc < 64; mc++) { double pvRed = 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); + double nonPVRed = 0.33 + log(double(hd)) * log(double(mc)) / 2.25; + Reductions[PV][hd][mc] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(ONE_PLY)) : 0); + Reductions[NonPV][hd][mc] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(ONE_PLY)) : 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) - 8 * mc + 45; + for (d = 1; d < 16; d++) for (mc = 0; mc < 64; mc++) + FutilityMargins[d][mc] = Value(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. Used at the beginning of a -// new search from the root. -void SearchStack::init() { - - pv[0] = pv[1] = MOVE_NONE; - currentMove = threatMove = MOVE_NONE; - reduction = Depth(0); - eval = VALUE_NONE; + FutilityMoveCounts[d] = int(3.001 + 0.25 * pow(d, 2.0)); } -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. All the legal moves up to +/// given depth are generated and counted and the sum returned. +int64_t perft(Position& pos, Depth depth) { -/// 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. + MoveStack mlist[MAX_MOVES]; + StateInfo st; + Move m; + int64_t sum = 0; -int perft(Position& pos, Depth depth) -{ - StateInfo st; - Move move; - int sum = 0; - MovePicker mp(pos, MOVE_NONE, depth, H); + // Generate all legal moves + MoveStack* last = generate(pos, mlist); - // If we are at the last ply we don't need to do and undo - // the moves, just to count them. - if (depth <= OnePly) // Replace with '<' to test also qsearch - { - while (mp.get_next_move()) sum++; - return sum; - } + // If we are at the last ply we don't need to do and undo + // the moves, just to count them. + if (depth <= ONE_PLY) + return int(last - mlist); - // Loop through all legal moves - CheckInfo ci(pos); - while ((move = mp.get_next_move()) != MOVE_NONE) - { - pos.do_move(move, st, ci, pos.move_is_check(move, ci)); - sum += perft(pos, depth - OnePly); - pos.undo_move(move); - } - return sum; + // Loop through all legal moves + CheckInfo ci(pos); + for (MoveStack* cur = mlist; cur != last; cur++) + { + m = cur->move; + pos.do_move(m, st, ci, pos.move_is_check(m, ci)); + sum += perft(pos, depth - ONE_PLY); + pos.undo_move(m); + } + return sum; } /// think() is the external interface to Stockfish's search, and is called when -/// the program receives the UCI 'go' command. It initializes various -/// search-related global variables, and calls root_search(). It returns false -/// when a quit command is received during the search. +/// the program receives the UCI 'go' command. It initializes various global +/// variables, and calls id_loop(). It returns false when a "quit" command is +/// received during the search. -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[]) { +bool think(Position& pos, const SearchLimits& limits, Move searchMoves[]) { - // Initialize global search variables - StopOnPonderhit = AbortSearch = Quit = AspirationFailLow = false; - MaxSearchTime = AbsoluteMaxSearchTime = ExtraSearchTime = 0; + // Initialize global search-related variables + StopOnPonderhit = StopRequest = QuitRequest = AspirationFailLow = SendSearchedNodes = false; NodesSincePoll = 0; - TM.resetNodeCounters(); - SearchStartTime = get_system_time(); - ExactMaxTime = maxTime; - MaxDepth = maxDepth; - MaxNodes = maxNodes; - InfiniteSearch = infinite; - PonderSearch = ponder; - UseTimeManagement = !ExactMaxTime && !MaxDepth && !MaxNodes && !InfiniteSearch; + current_search_time(get_system_time()); + Limits = limits; + TimeMgr.init(Limits, pos.startpos_ply_counter()); + + // Set best NodesBetweenPolls interval to avoid lagging under time pressure + if (Limits.maxNodes) + NodesBetweenPolls = Min(Limits.maxNodes, 30000); + else if (Limits.time && Limits.time < 1000) + NodesBetweenPolls = 1000; + else if (Limits.time && Limits.time < 5000) + NodesBetweenPolls = 5000; + else + NodesBetweenPolls = 30000; // Look for a book move, only during games, not tests - if (UseTimeManagement && get_option_value_bool("OwnBook")) + if (Limits.useTimeManagement() && Options["OwnBook"].value()) { - if (get_option_value_string("Book File") != OpeningBook.file_name()) - OpeningBook.open(get_option_value_string("Book File")); + if (Options["Book File"].value() != OpeningBook.name()) + OpeningBook.open(Options["Book File"].value()); - Move bookMove = OpeningBook.get_move(pos, get_option_value_bool("Best Book Move")); + Move bookMove = OpeningBook.get_move(pos, Options["Best Book Move"].value()); if (bookMove != MOVE_NONE) { - if (PonderSearch) + if (Limits.ponder) wait_for_stop_or_ponderhit(); cout << "bestmove " << bookMove << endl; - return true; + return !QuitRequest; } } - // Reset loseOnTime flag at the beginning of a new game - if (button_was_pressed("New Game")) - loseOnTime = false; + // Read UCI options + UCIMultiPV = Options["MultiPV"].value(); + SkillLevel = Options["Skill level"].value(); - // Read UCI option values - TT.set_size(get_option_value_int("Hash")); - if (button_was_pressed("Clear Hash")) - TT.clear(); + read_evaluation_uci_options(pos.side_to_move()); + ThreadsMgr.read_uci_options(); + + // If needed allocate pawn and material hash tables and adjust TT size + ThreadsMgr.init_hash_tables(); + TT.set_size(Options["Hash"].value()); - 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"); - - if (UseLogFile) - LogFile.open(get_option_value_string("Search Log Filename").c_str(), std::ios::out | std::ios::app); - - read_weights(pos.side_to_move()); - - // Set the number of active threads - int newActiveThreads = get_option_value_int("Threads"); - if (newActiveThreads != TM.active_threads()) + if (Options["Clear Hash"].value()) { - TM.set_active_threads(newActiveThreads); - init_eval(TM.active_threads()); + Options["Clear Hash"].set_value("false"); + TT.clear(); } - // Wake up sleeping threads - TM.wake_sleeping_threads(); + // Do we have to play with skill handicap? In this case enable MultiPV that + // we will use behind the scenes to retrieve a set of possible moves. + SkillLevelEnabled = (SkillLevel < 20); + MultiPV = (SkillLevelEnabled ? Max(UCIMultiPV, 4) : UCIMultiPV); - // Set thinking time - int myTime = time[side_to_move]; - int myIncrement = increment[side_to_move]; - if (UseTimeManagement) + // Wake up needed threads and reset maxPly counter + for (int i = 0; i < ThreadsMgr.active_threads(); i++) { - if (!movesToGo) // Sudden death time control - { - 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) - { - 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 (get_option_value_bool("Ponder")) - { - MaxSearchTime += MaxSearchTime / 4; - MaxSearchTime = Min(MaxSearchTime, AbsoluteMaxSearchTime); - } + ThreadsMgr[i].wake_up(); + ThreadsMgr[i].maxPly = 0; } - // Set best NodesBetweenPolls interval to avoid lagging under - // heavy time pressure. - if (MaxNodes) - NodesBetweenPolls = Min(MaxNodes, 30000); - else if (myTime && myTime < 1000) - NodesBetweenPolls = 1000; - else if (myTime && myTime < 5000) - NodesBetweenPolls = 5000; - else - NodesBetweenPolls = 30000; - - // Write search information to log file - if (UseLogFile) - LogFile << "Searching: " << pos.to_fen() << endl - << "infinite: " << infinite - << " ponder: " << ponder - << " time: " << myTime - << " increment: " << myIncrement - << " moves to go: " << movesToGo << endl; - - // LSN filtering. Used only for developing purposes, disabled by default - if ( UseLSNFiltering - && loseOnTime) + // Write to log file and keep it open to be accessed during the search + if (Options["Use Search Log"].value()) { - // Step 2. If after last move we decided to lose on time, do it now! - while (SearchStartTime + myTime + 1000 > get_system_time()) - /* wait here */; + std::string name = Options["Search Log Filename"].value(); + LogFile.open(name.c_str(), std::ios::out | std::ios::app); + + if (LogFile.is_open()) + LogFile << "\nSearching: " << pos.to_fen() + << "\ninfinite: " << Limits.infinite + << " ponder: " << Limits.ponder + << " time: " << Limits.time + << " increment: " << Limits.increment + << " moves to go: " << Limits.movesToGo + << endl; } // We're ready to start thinking. Call the iterative deepening loop function - Value v = id_loop(pos, searchMoves); + Move ponderMove = MOVE_NONE; + Move bestMove = id_loop(pos, searchMoves, &ponderMove); - if (UseLSNFiltering) + cout << "info" << speed_to_uci(pos.nodes_searched()) << endl; + + // Write final search statistics and close log file + if (LogFile.is_open()) { - // 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; - } - } + int t = current_search_time(); - if (UseLogFile) + LogFile << "Nodes: " << pos.nodes_searched() + << "\nNodes/second: " << (t > 0 ? pos.nodes_searched() * 1000 / t : 0) + << "\nBest move: " << move_to_san(pos, bestMove); + + StateInfo st; + pos.do_move(bestMove, st); + LogFile << "\nPonder move: " << move_to_san(pos, ponderMove) << endl; + pos.undo_move(bestMove); // Return from think() with unchanged position LogFile.close(); + } - TM.put_threads_to_sleep(); + // This makes all the threads to go to sleep + ThreadsMgr.set_active_threads(1); - return !Quit; -} + // If we are pondering or in infinite search, we shouldn't print the + // best move before we are told to do so. + if (!StopRequest && (Limits.ponder || Limits.infinite)) + wait_for_stop_or_ponderhit(); + // Could be MOVE_NONE when searching on a stalemate position + cout << "bestmove " << bestMove; -namespace { + // UCI protol is not clear on allowing sending an empty ponder move, instead + // it is clear that ponder move is optional. So skip it if empty. + if (ponderMove != MOVE_NONE) + cout << " ponder " << ponderMove; - // 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. + cout << endl; - Value id_loop(const Position& pos, Move searchMoves[]) { + return !QuitRequest; +} - Position p(pos, pos.thread()); - SearchStack ss[PLY_MAX_PLUS_2]; - Move EasyMove = MOVE_NONE; - Value value, alpha = -VALUE_INFINITE, beta = VALUE_INFINITE; - // Moves to search are verified, copied, scored and sorted - RootMoveList rml(p, searchMoves); +namespace { - // Handle special case of searching on a mate/stale position - if (rml.move_count() == 0) - { - if (PonderSearch) - wait_for_stop_or_ponderhit(); + // id_loop() is the main iterative deepening loop. It calls search() repeatedly + // with increasing depth until the allocated thinking time has been consumed, + // user stops the search, or the maximum search depth is reached. - return pos.is_check() ? -VALUE_MATE : VALUE_DRAW; - } + Move id_loop(Position& pos, Move searchMoves[], Move* ponderMove) { + + SearchStack ss[PLY_MAX_PLUS_2]; + Value bestValues[PLY_MAX_PLUS_2]; + int bestMoveChanges[PLY_MAX_PLUS_2]; + int depth, selDepth, aspirationDelta; + Value value, alpha, beta; + Move bestMove, easyMove, skillBest, skillPonder; - // 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 + // Initialize stuff before a new search + memset(ss, 0, 4 * sizeof(SearchStack)); TT.new_search(); H.clear(); - init_ss_array(ss, PLY_MAX_PLUS_2); - ValueByIteration[1] = rml.get_move_score(0); - Iteration = 1; + *ponderMove = bestMove = easyMove = skillBest = skillPonder = MOVE_NONE; + depth = aspirationDelta = 0; + alpha = -VALUE_INFINITE, beta = VALUE_INFINITE; + ss->currentMove = MOVE_NULL; // Hack to skip update_gains() - // 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); + // Moves to search are verified and copied + Rml.init(pos, searchMoves); - // Iterative deepening loop - while (Iteration < PLY_MAX) + // Handle special case of searching on a mate/stalemate position + if (Rml.size() == 0) { - // Initialize iteration - Iteration++; - BestMoveChangesByIteration[Iteration] = 0; + cout << "info depth 0 score " + << value_to_uci(pos.is_check() ? -VALUE_MATE : VALUE_DRAW) + << endl; + + return MOVE_NONE; + } - cout << "info depth " << Iteration << endl; + // Iterative deepening loop until requested to stop or target depth reached + while (!StopRequest && ++depth <= PLY_MAX && (!Limits.maxDepth || depth <= Limits.maxDepth)) + { + Rml.bestMoveChanges = 0; + cout << set960(pos.is_chess960()) << "info depth " << depth << endl; // Calculate dynamic aspiration window based on previous iterations - if (MultiPV == 1 && Iteration >= 6 && abs(ValueByIteration[Iteration - 1]) < VALUE_KNOWN_WIN) + if (MultiPV == 1 && depth >= 5 && abs(bestValues[depth - 1]) < VALUE_KNOWN_WIN) { - int prevDelta1 = ValueByIteration[Iteration - 1] - ValueByIteration[Iteration - 2]; - int prevDelta2 = ValueByIteration[Iteration - 2] - ValueByIteration[Iteration - 3]; + int prevDelta1 = bestValues[depth - 1] - bestValues[depth - 2]; + int prevDelta2 = bestValues[depth - 2] - bestValues[depth - 3]; - AspirationDelta = Max(abs(prevDelta1) + abs(prevDelta2) / 2, 16); - AspirationDelta = (AspirationDelta + 7) / 8 * 8; // Round to match grainSize + aspirationDelta = Min(Max(abs(prevDelta1) + abs(prevDelta2) / 2, 16), 24); + aspirationDelta = (aspirationDelta + 7) / 8 * 8; // Round to match grainSize - alpha = Max(ValueByIteration[Iteration - 1] - AspirationDelta, -VALUE_INFINITE); - beta = Min(ValueByIteration[Iteration - 1] + AspirationDelta, VALUE_INFINITE); + alpha = Max(bestValues[depth - 1] - aspirationDelta, -VALUE_INFINITE); + beta = Min(bestValues[depth - 1] + aspirationDelta, VALUE_INFINITE); } - // Search to the current depth, rml is updated and sorted, alpha and beta could change - value = root_search(p, ss, rml, &alpha, &beta); - - // Write PV to transposition table, in case the relevant entries have - // been overwritten during the search. - TT.insert_pv(p, ss->pv); - - if (AbortSearch) - break; // Value cannot be trusted. Break out immediately! - - //Save info about search result - ValueByIteration[Iteration] = value; + // Start with a small aspiration window and, in case of fail high/low, + // research with bigger window until not failing high/low anymore. + do { + // Search starting from ss+1 to allow calling update_gains() + value = search(pos, ss+1, alpha, beta, depth * ONE_PLY); - // Drop the easy move if differs from the new best move - if (ss->pv[0] != EasyMove) - EasyMove = MOVE_NONE; + // Write PV back to transposition table in case the relevant entries + // have been overwritten during the search. + for (int i = 0; i < Min(MultiPV, (int)Rml.size()); i++) + Rml[i].insert_pv_in_tt(pos); - if (UseTimeManagement) - { - // Time to stop? - bool stopSearch = false; + // Value cannot be trusted. Break out immediately! + if (StopRequest) + break; - // 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; + assert(value >= alpha); - // Stop search early when the last two iterations returned a mate score - if ( Iteration >= 6 - && 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 others - int64_t nodes = TM.nodes_searched(); - if ( Iteration >= 8 - && EasyMove == ss->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 - && current_search_time() > MaxSearchTime / 32))) - stopSearch = true; - - // Add some extra time if the best move has changed during the last two iterations - if (Iteration > 5 && Iteration <= 50) - ExtraSearchTime = BestMoveChangesByIteration[Iteration] * (MaxSearchTime / 2) - + 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 - // move at the next iteration anyway. - if (current_search_time() > ((MaxSearchTime + ExtraSearchTime) * 80) / 128) - stopSearch = true; - - if (stopSearch) + // In case of failing high/low increase aspiration window and research, + // otherwise exit the fail high/low loop. + if (value >= beta) { - if (PonderSearch) - StopOnPonderhit = true; - else - break; + beta = Min(beta + aspirationDelta, VALUE_INFINITE); + aspirationDelta += aspirationDelta / 2; } - } - - if (MaxDepth && Iteration >= MaxDepth) - break; - } - - // 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 - 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->pv[0] == MOVE_NONE) - { - ss->pv[0] = rml.get_move(0); - ss->pv[1] = MOVE_NONE; - } - - assert(ss->pv[0] != MOVE_NONE); - - cout << "bestmove " << ss->pv[0]; - - if (ss->pv[1] != MOVE_NONE) - cout << " ponder " << ss->pv[1]; - - cout << endl; - - if (UseLogFile) - { - if (dbg_show_mean) - dbg_print_mean(LogFile); - - if (dbg_show_hit_rate) - dbg_print_hit_rate(LogFile); + else if (value <= alpha) + { + AspirationFailLow = true; + StopOnPonderhit = false; - LogFile << "\nNodes: " << TM.nodes_searched() - << "\nNodes/second: " << nps() - << "\nBest move: " << move_to_san(p, ss->pv[0]); + alpha = Max(alpha - aspirationDelta, -VALUE_INFINITE); + aspirationDelta += aspirationDelta / 2; + } + else + break; - StateInfo st; - p.do_move(ss->pv[0], st); - LogFile << "\nPonder move: " - << move_to_san(p, ss->pv[1]) // Works also with MOVE_NONE - << endl; - } - return rml.get_move_score(0); - } + } while (abs(value) < VALUE_KNOWN_WIN); + // Collect info about search result + bestMove = Rml[0].pv[0]; + *ponderMove = Rml[0].pv[1]; + bestValues[depth] = value; + bestMoveChanges[depth] = Rml.bestMoveChanges; - // 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, prints some information to the standard output and handles - // the fail low/high loops. + // Do we need to pick now the best and the ponder moves ? + if (SkillLevelEnabled && depth == 1 + SkillLevel) + do_skill_level(&skillBest, &skillPonder); - Value root_search(Position& pos, SearchStack* ss, RootMoveList& rml, Value* alphaPtr, Value* betaPtr) { + // Retrieve max searched depth among threads + selDepth = 0; + for (int i = 0; i < ThreadsMgr.active_threads(); i++) + if (ThreadsMgr[i].maxPly > selDepth) + selDepth = ThreadsMgr[i].maxPly; - 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; + // Send PV line to GUI and to log file + for (int i = 0; i < Min(UCIMultiPV, (int)Rml.size()); i++) + cout << Rml[i].pv_info_to_uci(pos, depth, selDepth, alpha, beta, i) << endl; - researchCountFH = researchCountFL = 0; - alpha = *alphaPtr; - beta = *betaPtr; - isCheck = pos.is_check(); + if (LogFile.is_open()) + LogFile << pretty_pv(pos, depth, value, current_search_time(), Rml[0].pv) << endl; - // 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) - { - // Sort the moves before to (re)search - rml.sort(); + // Init easyMove after first iteration or drop if differs from the best move + if (depth == 1 && (Rml.size() == 1 || Rml[0].pv_score > Rml[1].pv_score + EasyMoveMargin)) + easyMove = bestMove; + else if (bestMove != easyMove) + easyMove = MOVE_NONE; - // Step 10. Loop through all moves in the root move list - for (int i = 0; i < rml.move_count() && !AbortSearch; i++) + // Check for some early stop condition + if (!StopRequest && Limits.useTimeManagement()) { - // This is used by time management - FirstRootMove = (i == 0); - - // Save the current node count before the move is searched - nodes = TM.nodes_searched(); - - // Reset beta cut-off counters - TM.resetBetaCounters(); - - // Pick the next root move, and print the move and the move number to - // the standard output. - move = ss->currentMove = rml.get_move(i); - - if (current_search_time() >= 1000) - cout << "info currmove " << move - << " currmovenumber " << i + 1 << endl; - - moveIsCheck = pos.move_is_check(move); - captureOrPromotion = pos.move_is_capture_or_promotion(move); - - // Step 11. Decide the new search depth - depth = (Iteration - 2) * OnePly + InitialDepth; - ext = extension(pos, move, captureOrPromotion, moveIsCheck, false, false, &dangerous); - newDepth = depth + ext; - - // Step 12. Futility pruning (omitted at root) - - // Step extra. Fail high loop - // If move fails high, we research with bigger window until we are not failing - // high anymore. - value = - VALUE_INFINITE; - - while (1) - { - // Step 13. Make the move - pos.do_move(move, st, ci, moveIsCheck); - - // Step extra. pv search - // We do pv search for first moves (i < MultiPV) - // and for fail high research (value > alpha) - if (i < MultiPV || value > alpha) - { - // Aspiration window is disabled in multi-pv case - if (MultiPV > 1) - alpha = -VALUE_INFINITE; - - // Full depth PV search, done on first move or after a fail high - value = -search(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); - } - } - - // Step 16. Undo move - pos.undo_move(move); - - // Can we exit fail high loop ? - if (AbortSearch || value < beta) - break; - - // We are failing high and going to do a research. It's important to update - // the score before research in case we run out of time while researching. - rml.set_move_score(i, value); - update_pv(ss); - TT.extract_pv(pos, ss->pv, PLY_MAX); - rml.set_move_pv(i, ss->pv); - - // Print information to the standard output - print_pv_info(pos, ss, alpha, beta, value); - - // Prepare for a research after a fail high, each time with a wider window - *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 + // Stop search early when the last two iterations returned a mate score + if ( depth >= 5 + && abs(bestValues[depth]) >= VALUE_MATE_IN_PLY_MAX + && abs(bestValues[depth - 1]) >= VALUE_MATE_IN_PLY_MAX) + StopRequest = true; + + // Stop search early if one move seems to be much better than the + // others or if there is only a single legal move. Also in the latter + // case we search up to some depth anyway to get a proper score. + if ( depth >= 7 + && easyMove == bestMove + && ( Rml.size() == 1 + ||( Rml[0].nodes > (pos.nodes_searched() * 85) / 100 + && current_search_time() > TimeMgr.available_time() / 16) + ||( Rml[0].nodes > (pos.nodes_searched() * 98) / 100 + && current_search_time() > TimeMgr.available_time() / 32))) + StopRequest = true; + + // Take in account some extra time if the best move has changed + if (depth > 4 && depth < 50) + TimeMgr.pv_instability(bestMoveChanges[depth], bestMoveChanges[depth - 1]); + + // Stop search if most of available time is already consumed. We probably don't + // have enough time to search the first move at the next iteration anyway. + if (current_search_time() > (TimeMgr.available_time() * 62) / 100) + StopRequest = true; + + // If we are allowed to ponder do not stop the search now but keep pondering + if (StopRequest && Limits.ponder) { - // PV move or new best move! - - // Update PV - rml.set_move_score(i, value); - update_pv(ss); - TT.extract_pv(pos, ss->pv, PLY_MAX); - rml.set_move_pv(i, ss->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 information to the standard output - print_pv_info(pos, ss, alpha, beta, value); - - // Raise alpha to setup proper non-pv search upper bound - if (value > alpha) - alpha = value; - } - 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 >= *alphaPtr); - - AspirationFailLow = (alpha == *alphaPtr); - - if (AspirationFailLow && StopOnPonderhit) - StopOnPonderhit = false; + StopRequest = false; + StopOnPonderhit = true; + } } + } - // Can we exit fail low loop ? - if (AbortSearch || !AspirationFailLow) - break; - - // 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 + // When using skills overwrite best and ponder moves with the sub-optimal ones + if (SkillLevelEnabled) + { + if (skillBest == MOVE_NONE) // Still unassigned ? + do_skill_level(&skillBest, &skillPonder); - // Sort the moves before to return - rml.sort(); + bestMove = skillBest; + *ponderMove = skillPonder; + } - return alpha; + return bestMove; } - // search<>() is the main search function for both PV and non-PV nodes + // search<>() is the main search function for both PV and non-PV nodes and for + // normal and SplitPoint nodes. When called just after a split point the search + // is simpler because we have already probed the hash table, done a null move + // search, and searched the first move before splitting, we don't have to repeat + // all this work again. 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. - template - Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int ply) { + template + Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth) { assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE); assert(beta > alpha && beta <= VALUE_INFINITE); assert(PvNode || alpha == beta - 1); - assert(ply > 0 && ply < PLY_MAX); - assert(pos.thread() >= 0 && pos.thread() < TM.active_threads()); + assert(pos.thread() >= 0 && pos.thread() < ThreadsMgr.active_threads()); - Move movesSearched[256]; - EvalInfo ei; + Move movesSearched[MAX_MOVES]; + int64_t nodes; StateInfo st; - const TTEntry* tte; + const TTEntry *tte; Key posKey; - Move ttMove, move, excludedMove; + Move ttMove, move, excludedMove, threatMove; Depth ext, newDepth; + ValueType vt; Value bestValue, value, oldAlpha; - Value refinedValue, nullValue, futilityValueScaled; // Non-PV specific - bool isCheck, singleEvasion, moveIsCheck, captureOrPromotion, dangerous; - bool mateThreat = false; - int moveCount = 0; + Value refinedValue, nullValue, futilityBase, futilityValueScaled; // Non-PV specific + bool isPvMove, isCheck, singularExtensionNode, moveIsCheck, captureOrPromotion, dangerous, isBadCap; + int moveCount = 0, playedMoveCount = 0; int threadID = pos.thread(); + SplitPoint* sp = NULL; + refinedValue = bestValue = value = -VALUE_INFINITE; oldAlpha = alpha; + isCheck = pos.is_check(); + ss->ply = (ss-1)->ply + 1; + + // Used to send selDepth info to GUI + if (PvNode && ThreadsMgr[threadID].maxPly < ss->ply) + ThreadsMgr[threadID].maxPly = ss->ply; + + if (SpNode) + { + sp = ss->sp; + tte = NULL; + ttMove = excludedMove = MOVE_NONE; + threatMove = sp->threatMove; + goto split_point_start; + } + else if (Root) + bestValue = alpha; // Step 1. Initialize node and poll. Polling can abort search - TM.incrementNodeCounter(threadID); - ss->init(); - (ss+2)->initKillers(); + ss->currentMove = ss->bestMove = threatMove = (ss+1)->excludedMove = MOVE_NONE; + (ss+1)->skipNullMove = false; (ss+1)->reduction = DEPTH_ZERO; + (ss+2)->killers[0] = (ss+2)->killers[1] = (ss+2)->mateKiller = MOVE_NONE; if (threadID == 0 && ++NodesSincePoll > NodesBetweenPolls) { NodesSincePoll = 0; - poll(); + poll(pos); } // Step 2. Check for aborted search and immediate draw - if (AbortSearch || TM.thread_should_stop(threadID)) - return Value(0); - - if (pos.is_draw() || ply >= PLY_MAX - 1) + if (( StopRequest + || ThreadsMgr.cutoff_at_splitpoint(threadID) + || pos.is_draw() + || ss->ply > PLY_MAX) && !Root) return VALUE_DRAW; // Step 3. Mate distance pruning - alpha = Max(value_mated_in(ply), alpha); - beta = Min(value_mate_in(ply+1), beta); + alpha = Max(value_mated_in(ss->ply), alpha); + beta = Min(value_mate_in(ss->ply+1), beta); if (alpha >= beta) return alpha; // 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. + // TT value, so we use a different position key in case of an excluded move. excludedMove = ss->excludedMove; posKey = excludedMove ? pos.get_exclusion_key() : pos.get_key(); tte = TT.retrieve(posKey); - ttMove = (tte ? tte->move() : MOVE_NONE); - - // 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)) + ttMove = tte ? tte->move() : MOVE_NONE; + + // At PV nodes we check for exact scores, while at non-PV nodes we check for + // a fail high/low. Biggest advantage at probing at PV nodes is to have a + // smooth experience in analysis mode. + if ( !Root + && tte + && (PvNode ? tte->depth() >= depth && tte->type() == VALUE_TYPE_EXACT + : ok_to_use_TT(tte, depth, beta, ss->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); + TT.refresh(tte); + ss->bestMove = ttMove; // Can be MOVE_NONE + return value_from_tt(tte->value(), ss->ply); } - // Step 5. Evaluate the position statically - // At PV nodes we do this only to update gain statistics - isCheck = pos.is_check(); - if (!isCheck) + // Step 5. Evaluate the position statically and update parent's gain statistics + if (isCheck) + ss->eval = ss->evalMargin = VALUE_NONE; + else if (tte) { - if (tte && tte->static_value() != VALUE_NONE) - { - ss->eval = tte->static_value(); - ei.kingDanger[pos.side_to_move()] = tte->king_danger(); - } - else - ss->eval = evaluate(pos, ei); + assert(tte->static_value() != VALUE_NONE); - 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); + ss->eval = tte->static_value(); + ss->evalMargin = tte->static_value_margin(); + refinedValue = refine_eval(tte, ss->eval, ss->ply); } + else + { + refinedValue = ss->eval = evaluate(pos, ss->evalMargin); + TT.store(posKey, VALUE_NONE, VALUE_TYPE_NONE, DEPTH_NONE, MOVE_NONE, ss->eval, ss->evalMargin); + } + + // Save gain for the parent non-capture move + update_gains(pos, (ss-1)->currentMove, (ss-1)->eval, ss->eval); // Step 6. Razoring (is omitted in PV nodes) if ( !PvNode && depth < RazorDepth && !isCheck - && refinedValue < beta - razor_margin(depth) + && refinedValue + razor_margin(depth) < beta && ttMove == MOVE_NONE - && (ss-1)->currentMove != MOVE_NULL - && !value_is_mate(beta) + && abs(beta) < VALUE_MATE_IN_PLY_MAX && !pos.has_pawn_on_7th(pos.side_to_move())) { - // 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()]); - Value rbeta = beta - razor_margin(depth); - Value v = qsearch(pos, ss, rbeta-1, rbeta, Depth(0), ply); + Value v = qsearch(pos, ss, rbeta-1, rbeta, DEPTH_ZERO); if (v < rbeta) // Logically we should return (v + razor_margin(depth)), but // surprisingly this did slightly weaker in tests. @@ -1164,53 +834,48 @@ namespace { if ( !PvNode && !ss->skipNullMove && depth < RazorDepth - && refinedValue >= beta + futility_margin(depth, 0) && !isCheck - && !value_is_mate(beta) + && refinedValue - futility_margin(depth, 0) >= beta + && abs(beta) < VALUE_MATE_IN_PLY_MAX && 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) + && depth > ONE_PLY && !isCheck - && !value_is_mate(beta) + && refinedValue >= beta + && abs(beta) < VALUE_MATE_IN_PLY_MAX && pos.non_pawn_material(pos.side_to_move())) { ss->currentMove = MOVE_NULL; // Null move dynamic reduction based on depth - int R = 3 + (depth >= 5 * OnePly ? depth / 8 : 0); + int R = 3 + (depth >= 5 * ONE_PLY ? depth / 8 : 0); // Null move dynamic reduction based on value - if (refinedValue - beta > PawnValueMidgame) + if (refinedValue - PawnValueMidgame > beta) R++; 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); + nullValue = -search(pos, ss+1, -beta, -alpha, depth-R*ONE_PLY); (ss+1)->skipNullMove = false; pos.undo_null_move(); if (nullValue >= beta) { // Do not return unproven mate scores - if (nullValue >= value_mate_in(PLY_MAX)) + if (nullValue >= VALUE_MATE_IN_PLY_MAX) nullValue = beta; - // Do zugzwang verification search at high depths - if (depth < 6 * OnePly) + if (depth < 6 * ONE_PLY) return nullValue; + // Do verification search at high depths ss->skipNullMove = true; - Value v = search(pos, ss, alpha, beta, depth-5*OnePly, ply); + Value v = search(pos, ss, alpha, beta, depth-R*ONE_PLY); ss->skipNullMove = false; if (v >= beta) @@ -1224,89 +889,127 @@ namespace { // move which was reduced. If a connection is found, return a fail // low score (which will cause the reduced move to fail high in the // parent node, which will trigger a re-search with full depth). - if (nullValue == value_mated_in(ply + 2)) - mateThreat = true; + threatMove = (ss+1)->bestMove; - ss->threatMove = (ss+1)->currentMove; if ( depth < ThreatDepth && (ss-1)->reduction - && connected_moves(pos, (ss-1)->currentMove, ss->threatMove)) + && threatMove != MOVE_NONE + && connected_moves(pos, (ss-1)->currentMove, threatMove)) return beta - 1; } } // Step 9. Internal iterative deepening - if ( depth >= IIDDepth[PvNode] - && ttMove == MOVE_NONE - && (PvNode || (!isCheck && ss->eval >= beta - IIDMargin))) + if ( depth >= IIDDepth[PvNode] + && ttMove == MOVE_NONE + && (PvNode || (!isCheck && ss->eval + IIDMargin >= beta))) { - Depth d = (PvNode ? depth - 2 * OnePly : depth / 2); + Depth d = (PvNode ? depth - 2 * ONE_PLY : depth / 2); ss->skipNullMove = true; - search(pos, ss, alpha, beta, d, ply); + search(pos, ss, alpha, beta, d); ss->skipNullMove = false; - ttMove = ss->pv[0]; + ttMove = ss->bestMove; tte = TT.retrieve(posKey); } - // Expensive mate threat detection (only for PV nodes) - if (PvNode) - mateThreat = pos.has_mate_threat(opposite_color(pos.side_to_move())); +split_point_start: // At split points actual search starts from here // Initialize a MovePicker object for the current position - MovePicker mp = MovePicker(pos, ttMove, depth, H, ss, (PvNode ? -VALUE_INFINITE : beta)); + MovePickerExt mp(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; + ss->bestMove = MOVE_NONE; + futilityBase = ss->eval + ss->evalMargin; + singularExtensionNode = !Root + && !SpNode + && depth >= SingularExtensionDepth[PvNode] + && tte + && tte->move() + && !excludedMove // Do not allow recursive singular extension search + && (tte->type() & VALUE_TYPE_LOWER) + && tte->depth() >= depth - 3 * ONE_PLY; + if (SpNode) + { + lock_grab(&(sp->lock)); + bestValue = sp->bestValue; + } // 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 - && !TM.thread_should_stop(threadID)) + && !ThreadsMgr.cutoff_at_splitpoint(threadID)) { assert(move_is_ok(move)); - if (move == excludedMove) + if (SpNode) + { + moveCount = ++sp->moveCount; + lock_release(&(sp->lock)); + } + else if (move == excludedMove) continue; + else + moveCount++; - singleEvasion = (isCheck && mp.number_of_evasions() == 1); + if (Root) + { + // This is used by time management + FirstRootMove = (moveCount == 1); + + // Save the current node count before the move is searched + nodes = pos.nodes_searched(); + + // If it's time to send nodes info, do it here where we have the + // correct accumulated node counts searched by each thread. + if (SendSearchedNodes) + { + SendSearchedNodes = false; + cout << "info" << speed_to_uci(pos.nodes_searched()) << endl; + } + + if (current_search_time() > 2000) + cout << "info currmove " << move + << " currmovenumber " << moveCount << endl; + } + + // At Root and at first iteration do a PV search on all the moves to score root moves + isPvMove = (PvNode && moveCount <= (Root ? depth <= ONE_PLY ? 1000 : MultiPV : 1)); moveIsCheck = pos.move_is_check(move, ci); captureOrPromotion = pos.move_is_capture_or_promotion(move); // Step 11. Decide the new search depth - ext = extension(pos, move, captureOrPromotion, moveIsCheck, singleEvasion, mateThreat, &dangerous); + ext = extension(pos, move, captureOrPromotion, moveIsCheck, &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. + // Singular extension search. If all moves but one fail low on a search of + // (alpha-s, beta-s), and just one fails high on (alpha, beta), then that move + // is singular and should be extended. To verify this we do a reduced search + // on all the other moves but the ttMove, if result is lower than ttValue minus + // a margin then we extend ttMove. if ( singularExtensionNode && move == tte->move() - && ext < OnePly) + && ext < ONE_PLY) { - Value ttValue = value_from_tt(tte->value(), ply); + Value ttValue = value_from_tt(tte->value(), ss->ply); if (abs(ttValue) < VALUE_KNOWN_WIN) { - Value b = ttValue - SingularExtensionMargin; + Value rBeta = ttValue - int(depth); ss->excludedMove = move; ss->skipNullMove = true; - Value v = search(pos, ss, b - 1, b, depth / 2, ply); + Value v = search(pos, ss, rBeta - 1, rBeta, depth / 2); ss->skipNullMove = false; ss->excludedMove = MOVE_NONE; - if (v < ttValue - SingularExtensionMargin) - ext = OnePly; + ss->bestMove = MOVE_NONE; + if (v < rBeta) + ext = ONE_PLY; } } - newDepth = depth - OnePly + ext; - // Update current move (this must be done after singular extension search) - movesSearched[moveCount++] = ss->currentMove = move; + ss->currentMove = move; + newDepth = depth - ONE_PLY + ext; // Step 12. Futility pruning (is omitted in PV nodes) if ( !PvNode @@ -1318,81 +1021,123 @@ namespace { { // Move count based pruning if ( moveCount >= futility_move_count(depth) - && !(ss->threatMove && connected_threat(pos, move, ss->threatMove)) - && bestValue > value_mated_in(PLY_MAX)) + && (!threatMove || !connected_threat(pos, move, threatMove)) + && bestValue > VALUE_MATED_IN_PLY_MAX) // FIXME bestValue is racy + { + if (SpNode) + lock_grab(&(sp->lock)); + continue; + } // Value based pruning - // We illogically ignore reduction condition depth >= 3*OnePly for predicted depth, + // We illogically ignore reduction condition depth >= 3*ONE_PLY for predicted depth, // but fixing this made program slightly weaker. Depth predictedDepth = newDepth - reduction(depth, moveCount); - futilityValueScaled = ss->eval + futility_margin(predictedDepth, moveCount) + futilityValueScaled = futilityBase + futility_margin(predictedDepth, moveCount) + H.gain(pos.piece_on(move_from(move)), move_to(move)); if (futilityValueScaled < beta) { - if (futilityValueScaled > bestValue) + if (SpNode) + { + lock_grab(&(sp->lock)); + if (futilityValueScaled > sp->bestValue) + sp->bestValue = bestValue = futilityValueScaled; + } + else if (futilityValueScaled > bestValue) bestValue = futilityValueScaled; + + continue; + } + + // Prune moves with negative SEE at low depths + if ( predictedDepth < 2 * ONE_PLY + && bestValue > VALUE_MATED_IN_PLY_MAX + && pos.see_sign(move) < 0) + { + if (SpNode) + lock_grab(&(sp->lock)); + continue; } } + // Bad capture detection. Will be used by prob-cut search + isBadCap = depth >= 3 * ONE_PLY + && depth < 8 * ONE_PLY + && captureOrPromotion + && move != ttMove + && !dangerous + && !move_is_promotion(move) + && abs(alpha) < VALUE_MATE_IN_PLY_MAX + && pos.see_sign(move) < 0; + // Step 13. Make the move pos.do_move(move, st, ci, moveIsCheck); + if (!SpNode && !captureOrPromotion) + movesSearched[playedMoveCount++] = move; + // 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); + if (isPvMove) + { + // Aspiration window is disabled in multi-pv case + if (Root && MultiPV > 1) + alpha = -VALUE_INFINITE; + + value = -search(pos, ss+1, -beta, -alpha, newDepth); + } else { // Step 14. Reduced depth search // If the move fails high will be re-searched at full depth. bool doFullDepthSearch = true; + alpha = SpNode ? sp->alpha : alpha; - if ( depth >= 3 * OnePly + if ( depth >= 3 * ONE_PLY && !captureOrPromotion && !dangerous && !move_is_castle(move) - && !move_is_killer(move, ss)) + && ss->killers[0] != move + && ss->killers[1] != move) { ss->reduction = reduction(depth, moveCount); if (ss->reduction) { + alpha = SpNode ? sp->alpha : alpha; 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); + value = -search(pos, ss+1, -(alpha+1), -alpha, d); doFullDepthSearch = (value > alpha); } + ss->reduction = DEPTH_ZERO; // Restore original reduction + } - // 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 + // Probcut search for bad captures. If a reduced search returns a value + // very below beta then we can (almost) safely prune the bad capture. + if (isBadCap) + { + ss->reduction = 3 * ONE_PLY; + Value rAlpha = alpha - 300; + Depth d = newDepth - ss->reduction; + value = -search(pos, ss+1, -(rAlpha+1), -rAlpha, d); + doFullDepthSearch = (value > rAlpha); + ss->reduction = DEPTH_ZERO; // 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); + alpha = SpNode ? sp->alpha : alpha; + value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth); // 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); + if (PvNode && value > alpha && (Root || value < beta)) + value = -search(pos, ss+1, -beta, -alpha, newDepth); } } @@ -1402,136 +1147,211 @@ namespace { assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); // Step 17. Check for new best move - if (value > bestValue) + if (SpNode) + { + lock_grab(&(sp->lock)); + bestValue = sp->bestValue; + alpha = sp->alpha; + } + + if (value > bestValue && !(SpNode && ThreadsMgr.cutoff_at_splitpoint(threadID))) { bestValue = value; - if (value > alpha) + + if (SpNode) + sp->bestValue = value; + + if (!Root && value > alpha) { - if (PvNode && value < beta) // This guarantees that always: alpha < beta + if (PvNode && value < beta) // We want always alpha < beta + { alpha = value; - update_pv(ss); + if (SpNode) + sp->alpha = value; + } + else if (SpNode) + sp->betaCutoff = true; - if (value == value_mate_in(ply + 1)) + if (value == value_mate_in(ss->ply + 1)) ss->mateKiller = move; + + ss->bestMove = move; + + if (SpNode) + sp->ss->bestMove = move; } } - // Step 18. Check for split - if ( depth >= MinimumSplitDepth - && TM.active_threads() > 1 - && bestValue < beta - && TM.available_thread_exists(threadID) - && !AbortSearch - && !TM.thread_should_stop(threadID) - && Iteration <= 99) - TM.split(pos, ss, ply, &alpha, beta, &bestValue, depth, - mateThreat, &moveCount, &mp, PvNode); - } - + if (Root) + { + // Finished searching the move. If StopRequest 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 (StopRequest) + break; + + // Remember searched nodes counts for this move + mp.rm->nodes += pos.nodes_searched() - nodes; + + // PV move or new best move ? + if (isPvMove || value > alpha) + { + // Update PV + ss->bestMove = move; + mp.rm->pv_score = value; + mp.rm->extract_pv_from_tt(pos); + + // We record how often the best move has been changed in each + // iteration. This information is used for time management: When + // the best move changes frequently, we allocate some more time. + if (!isPvMove && MultiPV == 1) + Rml.bestMoveChanges++; + + Rml.sort_multipv(moveCount); + + // Update alpha. In multi-pv we don't use aspiration window, so + // set alpha equal to minimum score among the PV lines. + if (MultiPV > 1) + alpha = Rml[Min(moveCount, MultiPV) - 1].pv_score; // FIXME why moveCount? + else if (value > alpha) + alpha = value; + } + else + mp.rm->pv_score = -VALUE_INFINITE; + + } // Root + + // Step 18. Check for split + if ( !Root + && !SpNode + && depth >= ThreadsMgr.min_split_depth() + && ThreadsMgr.active_threads() > 1 + && bestValue < beta + && ThreadsMgr.available_thread_exists(threadID) + && !StopRequest + && !ThreadsMgr.cutoff_at_splitpoint(threadID)) + ThreadsMgr.split(pos, ss, &alpha, beta, &bestValue, depth, + threatMove, moveCount, &mp, PvNode); + } + // Step 19. Check for mate and stalemate // All legal moves have been searched and if there are // no legal moves, it must be mate or stalemate. // If one move was excluded return fail low score. - if (!moveCount) - return excludedMove ? oldAlpha : (isCheck ? value_mated_in(ply) : VALUE_DRAW); + if (!SpNode && !moveCount) + return excludedMove ? oldAlpha : isCheck ? value_mated_in(ss->ply) : VALUE_DRAW; // Step 20. Update tables // If the search is not aborted, update the transposition table, // history counters, and killer moves. - if (AbortSearch || TM.thread_should_stop(threadID)) - return bestValue; + if (!SpNode && !StopRequest && !ThreadsMgr.cutoff_at_splitpoint(threadID)) + { + move = bestValue <= oldAlpha ? MOVE_NONE : ss->bestMove; + vt = bestValue <= oldAlpha ? VALUE_TYPE_UPPER + : bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT; - if (bestValue <= oldAlpha) - TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_UPPER, depth, MOVE_NONE, ss->eval, ei.kingDanger[pos.side_to_move()]); + TT.store(posKey, value_to_tt(bestValue, ss->ply), vt, depth, move, ss->eval, ss->evalMargin); - else if (bestValue >= beta) - { - TM.incrementBetaCounter(pos.side_to_move(), depth, threadID); - move = ss->pv[0]; - TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, move, ss->eval, ei.kingDanger[pos.side_to_move()]); - if (!pos.move_is_capture_or_promotion(move)) + // Update killers and history only for non capture moves that fails high + if ( bestValue >= beta + && !pos.move_is_capture_or_promotion(move)) { - update_history(pos, move, depth, movesSearched, moveCount); - update_killers(move, ss); + if (move != ss->killers[0]) + { + ss->killers[1] = ss->killers[0]; + ss->killers[0] = move; + } + update_history(pos, move, depth, movesSearched, playedMoveCount); } } - else - TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_EXACT, depth, ss->pv[0], ss->eval, ei.kingDanger[pos.side_to_move()]); + + if (SpNode) + { + // Here we have the lock still grabbed + sp->slaves[threadID] = 0; + sp->nodes += pos.nodes_searched(); + lock_release(&(sp->lock)); + } assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); return bestValue; } - // qsearch() is the quiescence search function, which is called by the main // search function when the remaining depth is zero (or, to be more precise, - // less than OnePly). + // less than ONE_PLY). template - Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int ply) { + Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth) { 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(pos.thread() >= 0 && pos.thread() < TM.active_threads()); + assert(pos.thread() >= 0 && pos.thread() < ThreadsMgr.active_threads()); - EvalInfo ei; StateInfo st; Move ttMove, move; - Value bestValue, value, futilityValue, futilityBase; - bool isCheck, deepChecks, enoughMaterial, moveIsCheck, evasionPrunable; + Value bestValue, value, evalMargin, futilityValue, futilityBase; + bool isCheck, enoughMaterial, moveIsCheck, evasionPrunable; const TTEntry* tte; + Depth ttDepth; Value oldAlpha = alpha; - TM.incrementNodeCounter(pos.thread()); - ss->pv[0] = ss->pv[1] = ss->currentMove = MOVE_NONE; - ss->eval = VALUE_NONE; + ss->bestMove = ss->currentMove = MOVE_NONE; + ss->ply = (ss-1)->ply + 1; // Check for an instant draw or maximum ply reached - if (pos.is_draw() || ply >= PLY_MAX - 1) + if (ss->ply > PLY_MAX || pos.is_draw()) return VALUE_DRAW; + // Decide whether or not to include checks, this fixes also the type of + // TT entry depth that we are going to use. Note that in qsearch we use + // only two types of depth in TT: DEPTH_QS_CHECKS or DEPTH_QS_NO_CHECKS. + isCheck = pos.is_check(); + ttDepth = (isCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS : DEPTH_QS_NO_CHECKS); + // Transposition table lookup. At PV nodes, we don't use the TT for // pruning, but only for move ordering. tte = TT.retrieve(pos.get_key()); ttMove = (tte ? tte->move() : MOVE_NONE); - if (!PvNode && tte && ok_to_use_TT(tte, depth, beta, ply)) + if (!PvNode && tte && ok_to_use_TT(tte, ttDepth, beta, ss->ply)) { - ss->currentMove = ttMove; // Can be MOVE_NONE - return value_from_tt(tte->value(), ply); + ss->bestMove = ttMove; // Can be MOVE_NONE + return value_from_tt(tte->value(), ss->ply); } - isCheck = pos.is_check(); - // Evaluate the position statically if (isCheck) { bestValue = futilityBase = -VALUE_INFINITE; - deepChecks = enoughMaterial = false; + ss->eval = evalMargin = VALUE_NONE; + enoughMaterial = false; } else { - if (tte && tte->static_value() != VALUE_NONE) + if (tte) { - ei.kingDanger[pos.side_to_move()] = tte->king_danger(); - bestValue = tte->static_value(); + assert(tte->static_value() != VALUE_NONE); + + evalMargin = tte->static_value_margin(); + ss->eval = bestValue = tte->static_value(); } else - bestValue = evaluate(pos, ei); + ss->eval = bestValue = evaluate(pos, evalMargin); - ss->eval = bestValue; update_gains(pos, (ss-1)->currentMove, (ss-1)->eval, ss->eval); // 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()]); + TT.store(pos.get_key(), value_to_tt(bestValue, ss->ply), VALUE_TYPE_LOWER, DEPTH_NONE, MOVE_NONE, ss->eval, evalMargin); return bestValue; } @@ -1539,19 +1359,16 @@ namespace { 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); - // Futility pruning parameters, not needed when in check - futilityBase = bestValue + FutilityMarginQS + ei.kingDanger[pos.side_to_move()]; + futilityBase = ss->eval + evalMargin + FutilityMarginQS; 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 or depth == -OnePly - // and we are near beta) will be generated. - MovePicker mp = MovePicker(pos, ttMove, deepChecks ? Depth(0) : depth, H); + // queen promotions and checks (only if depth >= DEPTH_QS_CHECKS) will + // be generated. + MovePicker mp(pos, ttMove, depth, H); CheckInfo ci(pos); // Loop through the moves until no moves remain or a beta cutoff occurs @@ -1573,7 +1390,7 @@ namespace { { futilityValue = futilityBase + pos.endgame_value_of_piece_on(move_to(move)) - + (move_is_ep(move) ? PawnValueEndgame : Value(0)); + + (move_is_ep(move) ? PawnValueEndgame : VALUE_ZERO); if (futilityValue < alpha) { @@ -1581,13 +1398,18 @@ namespace { bestValue = futilityValue; continue; } + + // Prune moves with negative or equal SEE + if ( futilityBase < beta + && depth < DEPTH_ZERO + && pos.see(move) <= 0) + continue; } - // Detect blocking evasions that are candidate to be pruned + // Detect non-capture evasions that are candidate to be pruned evasionPrunable = isCheck - && bestValue > value_mated_in(PLY_MAX) + && 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 @@ -1598,12 +1420,27 @@ namespace { && pos.see_sign(move) < 0) continue; + // Don't search useless checks + if ( !PvNode + && !isCheck + && moveIsCheck + && move != ttMove + && !pos.move_is_capture_or_promotion(move) + && ss->eval + PawnValueMidgame / 4 < beta + && !check_is_dangerous(pos, move, futilityBase, beta, &bestValue)) + { + if (ss->eval + PawnValueMidgame / 4 > bestValue) + bestValue = ss->eval + PawnValueMidgame / 4; + + continue; + } + // Update current move ss->currentMove = move; // Make and search the move pos.do_move(move, st, ci, moveIsCheck); - value = -qsearch(pos, ss+1, -beta, -alpha, depth-OnePly, ply+1); + value = -qsearch(pos, ss+1, -beta, -alpha, depth-ONE_PLY); pos.undo_move(move); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); @@ -1615,7 +1452,7 @@ namespace { if (value > alpha) { alpha = value; - update_pv(ss); + ss->bestMove = move; } } } @@ -1623,23 +1460,11 @@ namespace { // All legal moves have been searched. A special case: If we're in check // and no legal moves were found, it is checkmate. if (isCheck && bestValue == -VALUE_INFINITE) - return value_mated_in(ply); + return value_mated_in(ss->ply); // Update transposition table - Depth d = (depth == Depth(0) ? Depth(0) : Depth(-1)); - if (bestValue <= oldAlpha) - TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_UPPER, d, MOVE_NONE, ss->eval, ei.kingDanger[pos.side_to_move()]); - else if (bestValue >= beta) - { - move = ss->pv[0]; - TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, d, move, ss->eval, ei.kingDanger[pos.side_to_move()]); - - // Update killers only for good checking moves - if (!pos.move_is_capture_or_promotion(move)) - update_killers(move, ss); - } - else - TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EXACT, d, ss->pv[0], ss->eval, ei.kingDanger[pos.side_to_move()]); + ValueType vt = (bestValue <= oldAlpha ? VALUE_TYPE_UPPER : bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT); + TT.store(pos.get_key(), value_to_tt(bestValue, ss->ply), vt, ttDepth, ss->bestMove, ss->eval, evalMargin); assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); @@ -1647,205 +1472,60 @@ namespace { } - // sp_search() is used to search from a split point. This function is called - // by each thread working at the split point. It is similar to the normal - // search() function, but simpler. Because we have already probed the hash - // table, done a null move search, and searched the first move before - // splitting, we don't have to repeat all this work in sp_search(). 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. - - template - void sp_search(SplitPoint* sp, int threadID) { + // check_is_dangerous() tests if a checking move can be pruned in qsearch(). + // bestValue is updated only when returning false because in that case move + // will be pruned. - assert(threadID >= 0 && threadID < TM.active_threads()); - assert(TM.active_threads() > 1); - - StateInfo st; - Move move; - Depth ext, newDepth; - Value value; - Value futilityValueScaled; // NonPV specific - bool isCheck, moveIsCheck, captureOrPromotion, dangerous; - int moveCount; - value = -VALUE_INFINITE; + bool check_is_dangerous(Position &pos, Move move, Value futilityBase, Value beta, Value *bestValue) + { + Bitboard b, occ, oldAtt, newAtt, kingAtt; + Square from, to, ksq, victimSq; + Piece pc; + Color them; + Value futilityValue, bv = *bestValue; + + from = move_from(move); + to = move_to(move); + them = opposite_color(pos.side_to_move()); + ksq = pos.king_square(them); + kingAtt = pos.attacks_from(ksq); + pc = pos.piece_on(from); + + occ = pos.occupied_squares() & ~(1ULL << from) & ~(1ULL << ksq); + oldAtt = pos.attacks_from(pc, from, occ); + newAtt = pos.attacks_from(pc, to, occ); + + // Rule 1. Checks which give opponent's king at most one escape square are dangerous + b = kingAtt & ~pos.pieces_of_color(them) & ~newAtt & ~(1ULL << to); + + if (!(b && (b & (b - 1)))) + return true; - Position pos(*sp->pos, threadID); - CheckInfo ci(pos); - SearchStack* ss = sp->sstack[threadID] + 1; - isCheck = pos.is_check(); + // Rule 2. Queen contact check is very dangerous + if ( type_of_piece(pc) == QUEEN + && bit_is_set(kingAtt, to)) + return true; - // Step 10. Loop through moves - // Loop through all legal moves until no moves remain or a beta cutoff occurs - lock_grab(&(sp->lock)); + // Rule 3. Creating new double threats with checks + b = pos.pieces_of_color(them) & newAtt & ~oldAtt & ~(1ULL << ksq); - while ( sp->bestValue < sp->beta - && (move = sp->mp->get_next_move()) != MOVE_NONE - && !TM.thread_should_stop(threadID)) + while (b) { - moveCount = ++sp->moveCount; - lock_release(&(sp->lock)); - - assert(move_is_ok(move)); - - moveIsCheck = pos.move_is_check(move, ci); - captureOrPromotion = pos.move_is_capture_or_promotion(move); - - // Step 11. Decide the new search depth - ext = extension(pos, move, captureOrPromotion, moveIsCheck, false, sp->mateThreat, &dangerous); - newDepth = sp->depth - OnePly + ext; - - // Update current move - ss->currentMove = move; - - // Step 12. Futility pruning (is omitted in PV nodes) - if ( !PvNode - && !captureOrPromotion - && !isCheck - && !dangerous - && !move_is_castle(move)) - { - // 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 - 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) - { - lock_grab(&(sp->lock)); - - if (futilityValueScaled > sp->bestValue) - sp->bestValue = futilityValueScaled; - continue; - } - } - - // Step 13. Make the move - pos.do_move(move, st, ci, moveIsCheck); - - // Step 14. Reduced search - // If the move fails high will be re-searched at full depth. - bool doFullDepthSearch = true; + victimSq = pop_1st_bit(&b); + futilityValue = futilityBase + pos.endgame_value_of_piece_on(victimSq); - if ( !captureOrPromotion - && !dangerous - && !move_is_castle(move) - && !move_is_killer(move, ss)) - { - 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); - - doFullDepthSearch = (value > localAlpha); - } - - // 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 localAlpha = sp->alpha; - value = -search(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth-ss->reduction, sp->ply+1); - doFullDepthSearch = (value > localAlpha); - } - ss->reduction = Depth(0); // Restore original reduction - } - - // Step 15. Full depth search - if (doFullDepthSearch) - { - 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); - } - - // Step 16. Undo move - pos.undo_move(move); - - assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); - - // Step 17. Check for new best move - lock_grab(&(sp->lock)); - - if (value > sp->bestValue && !TM.thread_should_stop(threadID)) - { - sp->bestValue = value; - - if (sp->bestValue > sp->alpha) - { - if (!PvNode || value >= sp->beta) - sp->stopRequest = true; - - if (PvNode && value < sp->beta) // This guarantees that always: sp->alpha < sp->beta - sp->alpha = value; + // Note that here we generate illegal "double move"! + if ( futilityValue >= beta + && pos.see_sign(make_move(from, victimSq)) >= 0) + return true; - sp_update_pv(sp->parentSstack, ss); - } - } + if (futilityValue > bv) + bv = futilityValue; } - /* Here we have the lock still grabbed */ - - sp->slaves[threadID] = 0; - - lock_release(&(sp->lock)); - } - - // 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) { - - Move* src = (ss+1)->pv; - Move* dst = ss->pv; - - *dst = ss->currentMove; - - do - *++dst = *src; - while (*src++ != 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) { - - Move* src = (ss+1)->pv; - Move* dst = ss->pv; - Move* pdst = pss->pv; - - *dst = *pdst = ss->currentMove; - - do - *++dst = *++pdst = *src; - while (*src++ != MOVE_NONE); + // Update bestValue only if check is not dangerous (because we will prune the move) + *bestValue = bv; + return false; } @@ -1860,11 +1540,8 @@ namespace { Square f1, t1, f2, t2; Piece p; - assert(move_is_ok(m1)); - assert(move_is_ok(m2)); - - if (m2 == MOVE_NONE) - return false; + assert(m1 && move_is_ok(m1)); + assert(m2 && move_is_ok(m2)); // Case 1: The moving piece is the same in both moves f2 = move_from(m2); @@ -1905,29 +1582,34 @@ namespace { } - // value_is_mate() checks if the given value is a mate one - // eventually compensated for the ply. + // value_to_tt() adjusts a mate score from "plies to mate from the root" to + // "plies to mate from the current ply". Non-mate scores are unchanged. + // The function is called before storing a value to the transposition table. - bool value_is_mate(Value value) { + Value value_to_tt(Value v, int ply) { - assert(abs(value) <= VALUE_INFINITE); + if (v >= VALUE_MATE_IN_PLY_MAX) + return v + ply; - return value <= value_mated_in(PLY_MAX) - || value >= value_mate_in(PLY_MAX); + if (v <= VALUE_MATED_IN_PLY_MAX) + return v - ply; + + return v; } - // move_is_killer() checks if the given move is among the - // killer moves of that ply. + // value_from_tt() is the inverse of value_to_tt(): It adjusts a mate score from + // the transposition table to a mate score corrected for the current ply. + + Value value_from_tt(Value v, int ply) { - bool move_is_killer(Move m, SearchStack* ss) { + if (v >= VALUE_MATE_IN_PLY_MAX) + return v - ply; - const Move* k = ss->killers; - for (int i = 0; i < KILLER_MAX; i++, k++) - if (*k == m) - return true; + if (v <= VALUE_MATED_IN_PLY_MAX) + return v + ply; - return false; + return v; } @@ -1938,25 +1620,16 @@ namespace { // 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. template - Depth extension(const Position& pos, Move m, bool captureOrPromotion, bool moveIsCheck, - bool singleEvasion, bool mateThreat, bool* dangerous) { + Depth extension(const Position& pos, Move m, bool captureOrPromotion, + bool moveIsCheck, bool* dangerous) { assert(m != MOVE_NONE); - Depth result = Depth(0); - *dangerous = moveIsCheck | singleEvasion | mateThreat; + Depth result = DEPTH_ZERO; + *dangerous = moveIsCheck; - if (*dangerous) - { - if (moveIsCheck && pos.see_sign(m)>= 0) - result += CheckExtension[PvNode]; - - if (singleEvasion) - result += SingleEvasionExtension[PvNode]; - - if (mateThreat) - result += MateThreatExtension[PvNode]; - } + if (moveIsCheck && pos.see_sign(m) >= 0) + result += CheckExtension[PvNode]; if (pos.type_of_piece_on(move_from(m)) == PAWN) { @@ -1976,29 +1649,19 @@ namespace { if ( captureOrPromotion && pos.type_of_piece_on(move_to(m)) != PAWN && ( pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) - - pos.midgame_value_of_piece_on(move_to(m)) == Value(0)) - && !move_is_promotion(m) - && !move_is_ep(m)) + - pos.midgame_value_of_piece_on(move_to(m)) == VALUE_ZERO) + && !move_is_special(m)) { result += PawnEndgameExtension[PvNode]; *dangerous = true; } - if ( PvNode - && captureOrPromotion - && pos.type_of_piece_on(move_to(m)) != PAWN - && pos.see_sign(m) >= 0) - { - result += OnePly/2; - *dangerous = true; - } - - return Min(result, OnePly); + return Min(result, ONE_PLY); } // 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. + // is somehow connected to the threat move returned by null search. bool connected_threat(const Position& pos, Move m, Move threat) { @@ -2020,7 +1683,7 @@ namespace { return true; // 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. + // value of the threatening piece, don't prune moves which defend it. 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) @@ -2046,11 +1709,11 @@ namespace { 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)) + || 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)); + && ( ((tte->type() & VALUE_TYPE_LOWER) && v >= beta) + || ((tte->type() & VALUE_TYPE_UPPER) && v < beta)); } @@ -2059,13 +1722,12 @@ namespace { Value refine_eval(const TTEntry* tte, Value defaultEval, int ply) { - if (!tte) - return defaultEval; + assert(tte); Value v = value_from_tt(tte->value(), ply); - if ( (is_lower_bound(tte->type()) && v >= defaultEval) - || (is_upper_bound(tte->type()) && v < defaultEval)) + if ( ((tte->type() & VALUE_TYPE_LOWER) && v >= defaultEval) + || ((tte->type() & VALUE_TYPE_UPPER) && v < defaultEval)) return v; return defaultEval; @@ -2077,10 +1739,10 @@ namespace { void update_history(const Position& pos, Move move, Depth depth, Move movesSearched[], int moveCount) { - Move m; + Value bonus = Value(int(depth) * int(depth)); - H.success(pos.piece_on(move_from(move)), move_to(move), depth); + H.update(pos.piece_on(move_from(move)), move_to(move), bonus); for (int i = 0; i < moveCount - 1; i++) { @@ -2088,27 +1750,11 @@ namespace { assert(m != move); - if (!pos.move_is_capture_or_promotion(m)) - H.failure(pos.piece_on(move_from(m)), move_to(m), depth); + H.update(pos.piece_on(move_from(m)), move_to(m), -bonus); } } - // 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) { - - if (m == ss->killers[0]) - return; - - for (int i = KILLER_MAX - 1; i > 0; i--) - ss->killers[i] = ss->killers[i - 1]; - - ss->killers[0] = m; - } - - // update_gains() updates the gains table of a non-capture move given // the static position evaluation before and after the move. @@ -2117,28 +1763,59 @@ namespace { 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)); + && pos.captured_piece_type() == PIECE_TYPE_NONE + && !move_is_special(m)) + H.update_gain(pos.piece_on(move_to(m)), move_to(m), -(before + after)); } // current_search_time() returns the number of milliseconds which have passed // since the beginning of the current search. - int current_search_time() { + int current_search_time(int set) { + + static int searchStartTime; - return get_system_time() - SearchStartTime; + if (set) + searchStartTime = set; + + return get_system_time() - searchStartTime; } - // nps() computes the current nodes/second count. + // value_to_uci() converts a value to a string suitable for use with the UCI + // protocol specifications: + // + // cp The score from the engine's point of view in centipawns. + // mate Mate in y moves, not plies. If the engine is getting mated + // use negative values for y. + + std::string value_to_uci(Value v) { + + std::stringstream s; + + if (abs(v) < VALUE_MATE - PLY_MAX * ONE_PLY) + s << "cp " << int(v) * 100 / int(PawnValueMidgame); // Scale to centipawns + else + s << "mate " << (v > 0 ? VALUE_MATE - v + 1 : -VALUE_MATE - v) / 2; + + return s.str(); + } + - int nps() { + // speed_to_uci() returns a string with time stats of current search suitable + // to be sent to UCI gui. + std::string speed_to_uci(int64_t nodes) { + + std::stringstream s; int t = current_search_time(); - return (t > 0 ? int((TM.nodes_searched() * 1000) / t) : 0); + + s << " nodes " << nodes + << " nps " << (t > 0 ? int(nodes * 1000 / t) : 0) + << " time " << t; + + return s.str(); } @@ -2146,34 +1823,41 @@ namespace { // looks at the time consumed so far and decides if it's time to abort the // search. - void poll() { + void poll(const Position& pos) { static int lastInfoTime; int t = current_search_time(); // Poll for input - if (Bioskey()) + if (input_available()) { // We are line oriented, don't read single chars std::string command; - if (!std::getline(std::cin, command)) - command = "quit"; - - if (command == "quit") + if (!std::getline(std::cin, command) || command == "quit") { - AbortSearch = true; - PonderSearch = false; - Quit = true; + // Quit the program as soon as possible + Limits.ponder = false; + QuitRequest = StopRequest = true; return; } else if (command == "stop") { - AbortSearch = true; - PonderSearch = false; + // Stop calculating as soon as possible, but still send the "bestmove" + // and possibly the "ponder" token when finishing the search. + Limits.ponder = false; + StopRequest = true; } else if (command == "ponderhit") - ponderhit(); + { + // The opponent has played the expected move. GUI sends "ponderhit" if + // we were told to ponder on the same move the opponent has played. We + // should continue searching but switching from pondering to normal search. + Limits.ponder = false; + + if (StopOnPonderhit) + StopRequest = true; + } } // Print search information @@ -2189,71 +1873,28 @@ namespace { { lastInfoTime = t; - if (dbg_show_mean) - dbg_print_mean(); - - if (dbg_show_hit_rate) - dbg_print_hit_rate(); + dbg_print_mean(); + dbg_print_hit_rate(); - cout << "info nodes " << TM.nodes_searched() << " nps " << nps() - << " time " << t << " hashfull " << TT.full() << endl; + // Send info on searched nodes as soon as we return to root + SendSearchedNodes = true; } // Should we stop the search? - if (PonderSearch) + if (Limits.ponder) return; bool stillAtFirstMove = FirstRootMove && !AspirationFailLow - && t > MaxSearchTime + ExtraSearchTime; + && t > TimeMgr.available_time(); - bool noMoreTime = t > AbsoluteMaxSearchTime + bool noMoreTime = t > TimeMgr.maximum_time() || stillAtFirstMove; - if ( (Iteration >= 3 && UseTimeManagement && noMoreTime) - || (ExactMaxTime && t >= ExactMaxTime) - || (Iteration >= 3 && MaxNodes && TM.nodes_searched() >= MaxNodes)) - AbortSearch = true; - } - - - // ponderhit() is called when the program is pondering (i.e. thinking while - // it's the opponent's turn to move) in order to let the engine know that - // it correctly predicted the opponent's move. - - void ponderhit() { - - int t = current_search_time(); - PonderSearch = false; - - bool stillAtFirstMove = FirstRootMove - && !AspirationFailLow - && t > MaxSearchTime + ExtraSearchTime; - - bool noMoreTime = t > AbsoluteMaxSearchTime - || stillAtFirstMove; - - if (Iteration >= 3 && UseTimeManagement && (noMoreTime || StopOnPonderhit)) - AbortSearch = true; - } - - - // 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, int size) { - - for (int i = 0; i < size; i++, ss++) - { - ss->excludedMove = MOVE_NONE; - ss->skipNullMove = false; - - if (i < 3) - { - ss->init(); - ss->initKillers(); - } - } + if ( (Limits.useTimeManagement() && noMoreTime) + || (Limits.maxTime && t >= Limits.maxTime) + || (Limits.maxNodes && pos.nodes_searched() >= Limits.maxNodes)) // FIXME + StopRequest = true; } @@ -2262,595 +1903,302 @@ namespace { // 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()). + // after which the bestmove and pondermove will be printed. void wait_for_stop_or_ponderhit() { std::string command; - while (true) - { - if (!std::getline(std::cin, command)) - command = "quit"; + // Wait for a command from stdin + while ( std::getline(std::cin, command) + && command != "ponderhit" && command != "stop" && command != "quit") {}; - if (command == "quit") - { - Quit = true; - break; - } - else if (command == "ponderhit" || command == "stop") - break; - } + if (command != "ponderhit" && command != "stop") + QuitRequest = true; // Must be "quit" or getline() returned false } - // print_pv_info() prints to standard output and eventually to log file information on - // the current PV line. It is called at each iteration or after a new pv is found. - - void print_pv_info(const Position& pos, SearchStack* ss, Value alpha, Value beta, Value value) { + // When playing with strength handicap choose best move among the MultiPV set + // using a statistical rule dependent on SkillLevel. Idea by Heinz van Saanen. + void do_skill_level(Move* best, Move* ponder) { - 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 "; + assert(MultiPV > 1); - for (int j = 0; ss->pv[j] != MOVE_NONE && j < PLY_MAX; j++) - cout << ss->pv[j] << " "; + // Rml list is already sorted by pv_score in descending order + int s; + int max_s = -VALUE_INFINITE; + int size = Min(MultiPV, (int)Rml.size()); + int max = Rml[0].pv_score; + int var = Min(max - Rml[size - 1].pv_score, PawnValueMidgame); + int wk = 120 - 2 * SkillLevel; - cout << endl; + // PRNG sequence should be non deterministic + for (int i = abs(get_system_time() % 50); i > 0; i--) + RK.rand(); - if (UseLogFile) + // Choose best move. For each move's score we add two terms both dependent + // on wk, one deterministic and bigger for weaker moves, and one random, + // then we choose the move with the resulting highest score. + for (int i = 0; i < size; i++) { - ValueType type = (value >= beta ? VALUE_TYPE_LOWER - : (value <= alpha ? VALUE_TYPE_UPPER : VALUE_TYPE_EXACT)); - - LogFile << pretty_pv(pos, current_search_time(), Iteration, - TM.nodes_searched(), value, type, ss->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. + s = Rml[i].pv_score; -#if !defined(_MSC_VER) - - void* init_thread(void *threadID) { - - TM.idle_loop(*(int*)threadID, NULL); - return NULL; - } - -#else + // Don't allow crazy blunders even at very low skills + if (i > 0 && Rml[i-1].pv_score > s + EasyMoveMargin) + break; - DWORD WINAPI init_thread(LPVOID threadID) { + // This is our magical formula + s += ((max - s) * wk + var * (RK.rand() % wk)) / 128; - TM.idle_loop(*(int*)threadID, NULL); - return 0; + if (s > max_s) + { + max_s = s; + *best = Rml[i].pv[0]; + *ponder = Rml[i].pv[1]; + } + } } -#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. + /// RootMove and RootMoveList method's definitions - void ThreadsManager::resetNodeCounters() { + RootMove::RootMove() { - for (int i = 0; i < MAX_THREADS; i++) - threads[i].nodes = 0ULL; + nodes = 0; + pv_score = non_pv_score = -VALUE_INFINITE; + pv[0] = MOVE_NONE; } - void ThreadsManager::resetBetaCounters() { + RootMove& RootMove::operator=(const RootMove& rm) { - for (int i = 0; i < MAX_THREADS; i++) - threads[i].betaCutOffs[WHITE] = threads[i].betaCutOffs[BLACK] = 0ULL; - } - - int64_t ThreadsManager::nodes_searched() const { + const Move* src = rm.pv; + Move* dst = pv; - int64_t result = 0ULL; - for (int i = 0; i < ActiveThreads; i++) - result += threads[i].nodes; + // Avoid a costly full rm.pv[] copy + do *dst++ = *src; while (*src++ != MOVE_NONE); - return result; + nodes = rm.nodes; + pv_score = rm.pv_score; + non_pv_score = rm.non_pv_score; + return *this; } - 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)]; - } - } + void RootMoveList::init(Position& pos, Move searchMoves[]) { + MoveStack mlist[MAX_MOVES]; + Move* sm; - // idle_loop() is where the threads are parked when they have no work to do. - // The parameter 'sp', if non-NULL, is a pointer to an active SplitPoint - // object for which the current thread is the master. + clear(); + bestMoveChanges = 0; - void ThreadsManager::idle_loop(int threadID, SplitPoint* sp) { - - assert(threadID >= 0 && threadID < MAX_THREADS); - - while (true) + // Generate all legal moves and add them to RootMoveList + MoveStack* last = generate(pos, mlist); + for (MoveStack* cur = mlist; cur != last; cur++) { - // 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; - } - - // 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 !defined(_MSC_VER) - lock_grab(&WaitLock); - if (AllThreadsShouldSleep || threadID >= ActiveThreads) - pthread_cond_wait(&WaitCond, &WaitLock); - lock_release(&WaitLock); -#else - WaitForSingleObject(SitIdleEvent[threadID], INFINITE); -#endif - } - - // If thread has just woken up, mark it as available - if (threads[threadID].state == THREAD_SLEEPING) - threads[threadID].state = THREAD_AVAILABLE; - - // If this thread has been assigned work, launch a search - if (threads[threadID].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); + // If we have a searchMoves[] list then verify cur->move + // is in the list before to add it. + for (sm = searchMoves; *sm && *sm != cur->move; sm++) {} - threads[threadID].state = THREAD_AVAILABLE; - } - - // 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); + if (searchMoves[0] && *sm != cur->move) + continue; - threads[threadID].state = THREAD_SEARCHING; - return; - } + RootMove rm; + rm.pv[0] = cur->move; + rm.pv[1] = MOVE_NONE; + rm.pv_score = -VALUE_INFINITE; + push_back(rm); } } + // extract_pv_from_tt() builds a PV by adding moves from the transposition table. + // We consider also failing high nodes and not only VALUE_TYPE_EXACT nodes. This + // allow to always have a ponder move even when we fail high at root and also a + // long PV to print that is important for position analysis. - // 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 ThreadsManager::init_threads() { - - volatile int i; - bool ok; - -#if !defined(_MSC_VER) - pthread_t pthread[1]; -#endif + void RootMove::extract_pv_from_tt(Position& pos) { - // Initialize global locks - lock_init(&MPLock, NULL); - lock_init(&WaitLock, NULL); + StateInfo state[PLY_MAX_PLUS_2], *st = state; + TTEntry* tte; + int ply = 1; -#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 + assert(pv[0] != MOVE_NONE && pos.move_is_legal(pv[0])); - // 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); + pos.do_move(pv[0], *st++); - // 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++) + while ( (tte = TT.retrieve(pos.get_key())) != NULL + && tte->move() != MOVE_NONE + && pos.move_is_legal(tte->move()) + && ply < PLY_MAX + && (!pos.is_draw() || ply < 2)) { - -#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) {} + pv[ply] = tte->move(); + pos.do_move(pv[ply++], *st++); } - } - + pv[ply] = MOVE_NONE; - // exit_threads() is called when the program exits. It makes all the - // helper threads exit cleanly. - - 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 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 { - - assert(threadID >= 0 && threadID < ActiveThreads); - - SplitPoint* sp; - - for (sp = threads[threadID].splitPoint; sp && !sp->stopRequest; sp = sp->parent) {} - return sp != NULL; + do pos.undo_move(pv[--ply]); while (ply); } + // insert_pv_in_tt() is called at the end of a search iteration, and inserts + // the PV back into the TT. This makes sure the old PV moves are searched + // first, even if the old TT entries have been overwritten. - // 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 - // 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 ThreadsManager::thread_is_available(int slave, int master) const { + void RootMove::insert_pv_in_tt(Position& pos) { - assert(slave >= 0 && slave < ActiveThreads); - assert(master >= 0 && master < ActiveThreads); - assert(ActiveThreads > 1); + StateInfo state[PLY_MAX_PLUS_2], *st = state; + TTEntry* tte; + Key k; + Value v, m = VALUE_NONE; + int ply = 0; - if (threads[slave].state != THREAD_AVAILABLE || slave == master) - return false; + assert(pv[0] != MOVE_NONE && pos.move_is_legal(pv[0])); - // Make a local copy to be sure doesn't change under our feet - int localActiveSplitPoints = threads[slave].activeSplitPoints; + do { + k = pos.get_key(); + tte = TT.retrieve(k); - if (localActiveSplitPoints == 0) - // No active split points means that the thread is available as - // a slave for any other thread. - 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; - } - - - // available_thread_exists() tries to find an idle thread which is available as - // a slave for the thread with threadID "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; - - return false; - } - - - // split() does the actual work of distributing the work at a node between - // 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. 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(ply > 0 && ply < PLY_MAX); - assert(*bestValue >= -VALUE_INFINITE); - assert(*bestValue <= *alpha); - assert(*alpha < beta); - assert(beta <= VALUE_INFINITE); - assert(depth > Depth(0)); - assert(p.thread() >= 0 && p.thread() < ActiveThreads); - assert(ActiveThreads > 1); - - 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 ( !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* splitPoint = &SplitPointStack[master][threads[master].activeSplitPoints]; - - // Initialize the split point object - splitPoint->parent = threads[master].splitPoint; - splitPoint->stopRequest = false; - splitPoint->ply = ply; - splitPoint->depth = depth; - splitPoint->mateThreat = mateThreat; - splitPoint->alpha = *alpha; - splitPoint->beta = beta; - splitPoint->pvNode = pvNode; - splitPoint->bestValue = *bestValue; - splitPoint->mp = mp; - splitPoint->moveCount = *moveCount; - splitPoint->pos = &p; - splitPoint->parentSstack = ss; - for (int i = 0; i < ActiveThreads; i++) - splitPoint->slaves[i] = 0; - - 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); - - // 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]) + // Don't overwrite existing correct entries + if (!tte || tte->move() != pv[ply]) { - 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() + v = (pos.is_check() ? VALUE_NONE : evaluate(pos, m)); + TT.store(k, VALUE_NONE, VALUE_TYPE_NONE, DEPTH_NONE, pv[ply], v, m); } + pos.do_move(pv[ply], *st++); - // 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. - idle_loop(master, splitPoint); - - // We have returned from the idle loop, which means that all threads are - // finished. Update alpha and bestValue, and return. - lock_grab(&MPLock); - - *alpha = splitPoint->alpha; - *bestValue = splitPoint->bestValue; - threads[master].activeSplitPoints--; - threads[master].splitPoint = splitPoint->parent; - - lock_release(&MPLock); - } - - - // wake_sleeping_threads() wakes up all sleeping threads when it is time - // to start a new search from the root. - - 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); -#else - for (int i = 1; i < MAX_THREADS; i++) - SetEvent(SitIdleEvent[i]); -#endif + } while (pv[++ply] != MOVE_NONE); + do pos.undo_move(pv[--ply]); while (ply); } + // pv_info_to_uci() returns a string with information on the current PV line + // formatted according to UCI specification. - // 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. + std::string RootMove::pv_info_to_uci(Position& pos, int depth, int selDepth, Value alpha, + Value beta, int pvIdx) { + std::stringstream s; - void ThreadsManager::put_threads_to_sleep() { + s << "info depth " << depth + << " seldepth " << selDepth + << " multipv " << pvIdx + 1 + << " score " << value_to_uci(pv_score) + << (pv_score >= beta ? " lowerbound" : pv_score <= alpha ? " upperbound" : "") + << speed_to_uci(pos.nodes_searched()) + << " pv "; - assert(!AllThreadsShouldSleep); + for (Move* m = pv; *m != MOVE_NONE; m++) + s << *m << " "; - // This makes the threads to go to sleep - AllThreadsShouldSleep = true; + return s.str(); } - /// The RootMoveList class +} // namespace - // RootMoveList c'tor - RootMoveList::RootMoveList(Position& pos, Move searchMoves[]) : count(0) { +// ThreadsManager::idle_loop() is where the threads are parked when they have no work +// to do. The parameter 'sp', if non-NULL, is a pointer to an active SplitPoint +// object for which the current thread is the master. - SearchStack ss[PLY_MAX_PLUS_2]; - MoveStack mlist[MaxRootMoves]; - StateInfo st; - bool includeAllMoves = (searchMoves[0] == MOVE_NONE); +void ThreadsManager::idle_loop(int threadID, SplitPoint* sp) { - // Generate all legal moves - MoveStack* last = generate_moves(pos, mlist); + assert(threadID >= 0 && threadID < MAX_THREADS); - // Add each move to the moves[] array - for (MoveStack* cur = mlist; cur != last; cur++) - { - bool includeMove = includeAllMoves; + int i; + bool allFinished; - 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(); - } + 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; + } + // If we are not thinking, wait for a condition to be signaled + // instead of wasting CPU time polling for work. + while ( threadID >= activeThreads + || threads[threadID].state == THREAD_INITIALIZING + || (useSleepingThreads && threads[threadID].state == THREAD_AVAILABLE)) + { + assert(!sp || useSleepingThreads); + assert(threadID != 0 || useSleepingThreads); - // RootMoveList simple methods definitions + if (threads[threadID].state == THREAD_INITIALIZING) + threads[threadID].state = THREAD_AVAILABLE; - void RootMoveList::set_move_nodes(int moveNum, int64_t nodes) { + // Grab the lock to avoid races with Thread::wake_up() + lock_grab(&threads[threadID].sleepLock); - moves[moveNum].nodes = nodes; - moves[moveNum].cumulativeNodes += nodes; - } + // If we are master and all slaves have finished do not go to sleep + for (i = 0; sp && i < activeThreads && !sp->slaves[i]; i++) {} + allFinished = (i == activeThreads); - void RootMoveList::set_beta_counters(int moveNum, int64_t our, int64_t their) { + if (allFinished || allThreadsShouldExit) + { + lock_release(&threads[threadID].sleepLock); + break; + } - moves[moveNum].ourBeta = our; - moves[moveNum].theirBeta = their; - } + // Do sleep here after retesting sleep conditions + if (threadID >= activeThreads || threads[threadID].state == THREAD_AVAILABLE) + cond_wait(&threads[threadID].sleepCond, &threads[threadID].sleepLock); - void RootMoveList::set_move_pv(int moveNum, const Move pv[]) { + lock_release(&threads[threadID].sleepLock); + } - int j; + // If this thread has been assigned work, launch a search + if (threads[threadID].state == THREAD_WORKISWAITING) + { + assert(!allThreadsShouldExit); - for (j = 0; pv[j] != MOVE_NONE; j++) - moves[moveNum].pv[j] = pv[j]; + threads[threadID].state = THREAD_SEARCHING; - moves[moveNum].pv[j] = MOVE_NONE; - } + // Copy split point position and search stack and call search() + // with SplitPoint template parameter set to true. + SearchStack ss[PLY_MAX_PLUS_2]; + SplitPoint* tsp = threads[threadID].splitPoint; + Position pos(*tsp->pos, threadID); + memcpy(ss, tsp->ss - 1, 4 * sizeof(SearchStack)); + (ss+1)->sp = tsp; - // RootMoveList::sort() sorts the root move list at the beginning of a new - // iteration. - - void RootMoveList::sort() { + if (tsp->pvNode) + search(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth); + else + search(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth); - sort_multipv(count - 1); // Sort all items - } + assert(threads[threadID].state == THREAD_SEARCHING); + threads[threadID].state = THREAD_AVAILABLE; - // 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. + // Wake up master thread so to allow it to return from the idle loop in + // case we are the last slave of the split point. + if ( useSleepingThreads + && threadID != tsp->master + && threads[tsp->master].state == THREAD_AVAILABLE) + threads[tsp->master].wake_up(); + } - void RootMoveList::sort_multipv(int n) { + // 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. + for (i = 0; sp && i < activeThreads && !sp->slaves[i]; i++) {} + allFinished = (i == activeThreads); - int i,j; + if (allFinished) + { + // 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)); - 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]; + // In helpful master concept a master can help only a sub-tree, and + // because here is all finished is not possible master is booked. + assert(threads[threadID].state == THREAD_AVAILABLE); - moves[j] = rm; - } + threads[threadID].state = THREAD_SEARCHING; + return; + } } - -} // namspace +}