X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=4cce6a9171de9139d8e51e717d966af819912492;hp=df1c9b506d7c8e79f957bf90e1d9dcfe3f5c0aa4;hb=e5ffe9959c40a5ec6c4bca83a5a48070cae7fa5b;hpb=c9d7e99de682516c560009b550c41da9ae2008b8 diff --git a/src/search.cpp b/src/search.cpp index df1c9b50..4cce6a91 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -21,6 +21,7 @@ #include #include #include +#include #include #include #include @@ -32,7 +33,6 @@ #include "move.h" #include "movegen.h" #include "movepick.h" -#include "lock.h" #include "search.h" #include "timeman.h" #include "thread.h" @@ -41,130 +41,51 @@ using std::cout; using std::endl; +using std::string; namespace { - // Different node types, used as template parameter - enum NodeType { NonPV, PV }; - - // Set to true to force running with one thread. Used for debugging. + // Set to true to force running with one thread. Used for debugging const bool FakeSplit = false; - // 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]; } - - // ThreadsManager class is used to handle all the threads related stuff like init, - // starting, parking and, the most important, launching a slave thread at a split - // point. All the access to shared thread data is done through this class. - - 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: - Thread& operator[](int threadID) { return threads[threadID]; } - void init_threads(); - void exit_threads(); - - int min_split_depth() const { return minimumSplitDepth; } - int active_threads() const { return activeThreads; } - void set_active_threads(int cnt) { activeThreads = cnt; } - - void read_uci_options(); - bool available_thread_exists(int master) const; - bool thread_is_available(int slave, int master) const; - bool cutoff_at_splitpoint(int threadID) const; - void idle_loop(int threadID, SplitPoint* sp); - - template - void split(Position& pos, SearchStack* ss, Value* alpha, const Value beta, Value* bestValue, - Depth depth, Move threatMove, int moveCount, MovePicker* mp, bool pvNode); - private: - Lock mpLock; - Depth minimumSplitDepth; - int maxThreadsPerSplitPoint; - bool useSleepingThreads; - int activeThreads; - volatile bool allThreadsShouldExit; - Thread threads[MAX_THREADS]; - }; - + // Different node types, used as template parameter + enum NodeType { Root, PV, NonPV, SplitPointRoot, SplitPointPV, SplitPointNonPV }; // RootMove struct is used for moves at the root of the tree. For each root - // move, we store 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. - + // move, we store a score, a node count, and a PV (really a refutation + // in the case of moves which fail low). Score is normally set at + // -VALUE_INFINITE for all non-pv moves. struct RootMove { - RootMove(); - 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 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 pv_score != m.pv_score ? pv_score < m.pv_score - : non_pv_score < m.non_pv_score; - } + // than a move m2 if it has an higher score + bool operator<(const RootMove& m) const { return score < m.score; } void extract_pv_from_tt(Position& pos); void insert_pv_in_tt(Position& pos); - 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]; + Value score; + Value prevScore; + std::vector pv; }; - - // RootMoveList struct is just a vector of RootMove objects, - // with an handful of methods above the standard ones. - + // RootMoveList struct is mainly a std::vector of RootMove objects struct RootMoveList : public std::vector { - typedef std::vector Base; - void init(Position& pos, Move searchMoves[]); - void sort() { insertion_sort(begin(), end()); } - void sort_multipv(int n) { insertion_sort(begin(), begin() + n); } + RootMove* find(const Move& m, int startIndex = 0); 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; - } - + /// Constants - /// Adjustments + // 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]; } // Step 6. Razoring @@ -203,27 +124,29 @@ namespace { const Value FutilityMarginQS = Value(0x80); // Futility lookup tables (initialized at startup) and their access functions - Value FutilityMarginsMatrix[16][64]; // [depth][moveNumber] - int FutilityMoveCountArray[32]; // [depth] + Value FutilityMargins[16][64]; // [depth][moveNumber] + int FutilityMoveCounts[32]; // [depth] inline Value futility_margin(Depth d, int mn) { - return d < 7 * ONE_PLY ? FutilityMarginsMatrix[Max(d, 1)][Min(mn, 63)] - : 2 * VALUE_INFINITE; + return d < 7 * ONE_PLY ? FutilityMargins[Max(d, 1)][Min(mn, 63)] + : 2 * VALUE_INFINITE; } inline int futility_move_count(Depth d) { - return d < 16 * ONE_PLY ? FutilityMoveCountArray[d] : MAX_MOVES; + return d < 16 * ONE_PLY ? FutilityMoveCounts[d] : MAX_MOVES; } // Step 14. Reduced search // Reduction lookup tables (initialized at startup) and their access function - int8_t ReductionMatrix[2][64][64]; // [pv][depth][moveNumber] + int8_t Reductions[2][64][64]; // [pv][depth][moveNumber] - template - inline Depth reduction(Depth d, int mn) { return (Depth) ReductionMatrix[PV][Min(d / ONE_PLY, 63)][Min(mn, 63)]; } + template inline Depth reduction(Depth d, int mn) { + + return (Depth) Reductions[PvNode][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. @@ -232,14 +155,11 @@ namespace { /// Namespace variables - // Book - Book OpeningBook; - // Root move list RootMoveList Rml; // MultiPV mode - int MultiPV, UCIMultiPV; + int MultiPV, UCIMultiPV, MultiPVIteration; // Time management variables bool StopOnPonderhit, FirstRootMove, StopRequest, QuitRequest, AspirationFailLow; @@ -252,14 +172,9 @@ namespace { // Skill level adjustment int SkillLevel; bool SkillLevelEnabled; - RKISS RK; - - // Multi-threads manager - ThreadsManager ThreadsMgr; // 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; @@ -271,27 +186,17 @@ namespace { Move id_loop(Position& pos, Move searchMoves[], Move* ponderMove); - template + template Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth); - template + template Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth); - template - 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* dangerous); - bool check_is_dangerous(Position &pos, Move move, Value futilityBase, Value beta, Value *bValue); bool connected_moves(const Position& pos, Move m1, Move m2); Value value_to_tt(Value v, int ply); Value value_from_tt(Value v, int ply); - bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply); + bool can_return_tt(const TTEntry* tte, Depth depth, Value beta, int ply); bool connected_threat(const Position& pos, Move m, Move threat); Value refine_eval(const TTEntry* tte, Value defaultEval, int ply); void update_history(const Position& pos, Move move, Depth depth, Move movesSearched[], int moveCount); @@ -299,89 +204,106 @@ namespace { void do_skill_level(Move* best, Move* ponder); int current_search_time(int set = 0); - std::string value_to_uci(Value v); - std::string speed_to_uci(int64_t nodes); + string score_to_uci(Value v, Value alpha = -VALUE_INFINITE, Value beta = VALUE_INFINITE); + string speed_to_uci(int64_t nodes); + string pv_to_uci(const Move pv[], int pvNum, bool chess960); + string pretty_pv(Position& pos, int depth, Value score, int time, Move pv[]); + string depth_to_uci(Depth depth); void poll(const Position& pos); void wait_for_stop_or_ponderhit(); -#if !defined(_MSC_VER) - void* init_thread(void* threadID); -#else - DWORD WINAPI init_thread(LPVOID threadID); -#endif + // MovePickerExt template class extends MovePicker and allows to choose at compile + // time the proper moves source according to the type of node. In the default case + // we simply create and use a standard MovePicker object. + template struct MovePickerExt : public MovePicker { + MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b) + : MovePicker(p, ttm, d, h, ss, b) {} + }; - // 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 { + // In case of a SpNode we use split point's shared MovePicker object as moves source + template<> struct MovePickerExt : public MovePicker { MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, 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; - } + : MovePicker(p, ttm, d, h, ss, b), mp(ss->sp->mp) {} - Rml.sort(); - rm = Rml.begin(); - } + Move get_next_move() { return mp->get_next_move(); } + MovePicker* mp; + }; - Move get_next_move() { + // 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) { - if (!firstCall) - ++rm; - else - firstCall = false; + bool chess960 = (os.iword(0) != 0); // See set960() + return os << move_to_uci(m, chess960); + } - return rm != Rml.end() ? rm->pv[0] : MOVE_NONE; - } + // 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 {}; - RootMoveList::iterator rm; - bool firstCall; - }; + std::ostream& operator<< (std::ostream& os, const set960& f) { - // In SpNodes use split point's shared MovePicker object as move source - template<> struct MovePickerExt : public MovePicker { + os.iword(0) = int(f); + return os; + } - 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) {} + // extension() decides whether a move should be searched with normal depth, + // or with extended depth. Certain classes of moves (checking moves, in + // particular) are searched with bigger depth than ordinary moves and in + // any case are marked as 'dangerous'. Note that also if a move is not + // extended, as example because the corresponding UCI option is set to zero, + // the move is marked as 'dangerous' so, at least, we avoid to prune it. + template + FORCE_INLINE Depth extension(const Position& pos, Move m, bool captureOrPromotion, + bool moveIsCheck, bool* dangerous) { + assert(m != MOVE_NONE); - Move get_next_move() { return mp->get_next_move(); } + Depth result = DEPTH_ZERO; + *dangerous = moveIsCheck; - RootMoveList::iterator rm; // Dummy, needed to compile - MovePicker* mp; - }; + if (moveIsCheck && pos.see_sign(m) >= 0) + result += CheckExtension[PvNode]; - // Default case, create and use a MovePicker object as source - template<> struct MovePickerExt : public MovePicker { + if (piece_type(pos.piece_on(move_from(m))) == PAWN) + { + Color c = pos.side_to_move(); + if (relative_rank(c, move_to(m)) == RANK_7) + { + result += PawnPushTo7thExtension[PvNode]; + *dangerous = true; + } + if (pos.pawn_is_passed(c, move_to(m))) + { + result += PassedPawnExtension[PvNode]; + *dangerous = true; + } + } - MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b) - : MovePicker(p, ttm, d, h, ss, b) {} + if ( captureOrPromotion + && piece_type(pos.piece_on(move_to(m))) != PAWN + && ( pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) + - piece_value_midgame(pos.piece_on(move_to(m))) == VALUE_ZERO) + && !move_is_special(m)) + { + result += PawnEndgameExtension[PvNode]; + *dangerous = true; + } - RootMoveList::iterator rm; // Dummy, needed to compile - }; + return Min(result, ONE_PLY); + } } // namespace -/// init_threads() is called during startup. It initializes various lookup tables -/// and creates and launches search threads. +/// init_search() is called during startup to initialize various lookup tables -void init_threads() { +void init_search() { int d; // depth (ONE_PLY == 2) int hd; // half depth (ONE_PLY == 1) @@ -392,53 +314,43 @@ void init_threads() { { double pvRed = log(double(hd)) * log(double(mc)) / 3.0; double nonPVRed = 0.33 + log(double(hd)) * log(double(mc)) / 2.25; - ReductionMatrix[PV][hd][mc] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(ONE_PLY)) : 0); - ReductionMatrix[NonPV][hd][mc] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(ONE_PLY)) : 0); + Reductions[1][hd][mc] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(ONE_PLY)) : 0); + Reductions[0][hd][mc] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(ONE_PLY)) : 0); } // Init futility margins array for (d = 1; d < 16; d++) for (mc = 0; mc < 64; mc++) - FutilityMarginsMatrix[d][mc] = Value(112 * int(log(double(d * d) / 2) / log(2.0) + 1.001) - 8 * mc + 45); + 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] = int(3.001 + 0.25 * pow(d, 2.0)); - - // Create and startup threads - ThreadsMgr.init_threads(); + FutilityMoveCounts[d] = int(3.001 + 0.25 * pow(d, 2.0)); } -/// exit_threads() is a trampoline to access ThreadsMgr from outside of current file -void exit_threads() { ThreadsMgr.exit_threads(); } - - -/// perft() is our utility to verify move generation. All the legal moves up to -/// given depth are generated and counted and the sum returned. +/// perft() is our utility to verify move generation. All the leaf nodes up to +/// the given depth are generated and counted and the sum returned. int64_t perft(Position& pos, Depth depth) { - MoveStack mlist[MAX_MOVES]; StateInfo st; - Move m; int64_t sum = 0; // Generate all legal moves - MoveStack* last = generate(pos, mlist); + MoveList ml(pos); // 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); + return ml.size(); // Loop through all legal moves CheckInfo ci(pos); - for (MoveStack* cur = mlist; cur != last; cur++) + for ( ; !ml.end(); ++ml) { - m = cur->move; - pos.do_move(m, st, ci, pos.move_is_check(m, ci)); + pos.do_move(ml.move(), st, ci, pos.move_gives_check(ml.move(), ci)); sum += perft(pos, depth - ONE_PLY); - pos.undo_move(m); + pos.undo_move(ml.move()); } return sum; } @@ -451,13 +363,18 @@ int64_t perft(Position& pos, Depth depth) { bool think(Position& pos, const SearchLimits& limits, Move searchMoves[]) { + static Book book; + // Initialize global search-related variables - StopOnPonderhit = StopRequest = QuitRequest = AspirationFailLow = SendSearchedNodes = false; + StopOnPonderhit = StopRequest = QuitRequest = AspirationFailLow = false; NodesSincePoll = 0; current_search_time(get_system_time()); Limits = limits; TimeMgr.init(Limits, pos.startpos_ply_counter()); + // Set output steram in normal or chess960 mode + cout << set960(pos.is_chess960()); + // Set best NodesBetweenPolls interval to avoid lagging under time pressure if (Limits.maxNodes) NodesBetweenPolls = Min(Limits.maxNodes, 30000); @@ -468,13 +385,13 @@ bool think(Position& pos, const SearchLimits& limits, Move searchMoves[]) { else NodesBetweenPolls = 30000; - // Look for a book move, only during games, not tests - if (Limits.useTimeManagement() && Options["OwnBook"].value()) + // Look for a book move + if (Options["OwnBook"].value()) { - if (Options["Book File"].value() != OpeningBook.name()) - OpeningBook.open(Options["Book File"].value()); + if (Options["Book File"].value() != book.name()) + book.open(Options["Book File"].value()); - Move bookMove = OpeningBook.get_move(pos, Options["Best Book Move"].value()); + Move bookMove = book.get_move(pos, Options["Best Book Move"].value()); if (bookMove != MOVE_NONE) { if (Limits.ponder) @@ -487,37 +404,36 @@ bool think(Position& pos, const SearchLimits& limits, Move searchMoves[]) { // Read UCI options UCIMultiPV = Options["MultiPV"].value(); - SkillLevel = Options["Skill level"].value(); + SkillLevel = Options["Skill Level"].value(); read_evaluation_uci_options(pos.side_to_move()); + Threads.read_uci_options(); + + // Set a new TT size if changed + TT.set_size(Options["Hash"].value()); if (Options["Clear Hash"].value()) { Options["Clear Hash"].set_value("false"); TT.clear(); } - TT.set_size(Options["Hash"].value()); // 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 the number of active threads - ThreadsMgr.read_uci_options(); - init_eval(ThreadsMgr.active_threads()); - // Wake up needed threads and reset maxPly counter - for (int i = 0; i < ThreadsMgr.active_threads(); i++) + for (int i = 0; i < Threads.size(); i++) { - ThreadsMgr[i].wake_up(); - ThreadsMgr[i].maxPly = 0; + Threads[i].wake_up(); + Threads[i].maxPly = 0; } // Write to log file and keep it open to be accessed during the search if (Options["Use Search Log"].value()) { - std::string name = Options["Search Log Filename"].value(); + string name = Options["Search Log Filename"].value(); LogFile.open(name.c_str(), std::ios::out | std::ios::app); if (LogFile.is_open()) @@ -534,8 +450,6 @@ bool think(Position& pos, const SearchLimits& limits, Move searchMoves[]) { Move ponderMove = MOVE_NONE; Move bestMove = id_loop(pos, searchMoves, &ponderMove); - cout << "info" << speed_to_uci(pos.nodes_searched()) << endl; - // Write final search statistics and close log file if (LogFile.is_open()) { @@ -553,7 +467,7 @@ bool think(Position& pos, const SearchLimits& limits, Move searchMoves[]) { } // This makes all the threads to go to sleep - ThreadsMgr.set_active_threads(1); + Threads.set_size(1); // If we are pondering or in infinite search, we shouldn't print the // best move before we are told to do so. @@ -585,7 +499,7 @@ namespace { SearchStack ss[PLY_MAX_PLUS_2]; Value bestValues[PLY_MAX_PLUS_2]; int bestMoveChanges[PLY_MAX_PLUS_2]; - int depth, selDepth, aspirationDelta; + int depth, aspirationDelta; Value value, alpha, beta; Move bestMove, easyMove, skillBest, skillPonder; @@ -595,18 +509,17 @@ namespace { H.clear(); *ponderMove = bestMove = easyMove = skillBest = skillPonder = MOVE_NONE; depth = aspirationDelta = 0; - alpha = -VALUE_INFINITE, beta = VALUE_INFINITE; + value = alpha = -VALUE_INFINITE, beta = VALUE_INFINITE; ss->currentMove = MOVE_NULL; // Hack to skip update_gains() // Moves to search are verified and copied Rml.init(pos, searchMoves); // Handle special case of searching on a mate/stalemate position - if (Rml.size() == 0) + if (!Rml.size()) { - cout << "info depth 0 score " - << value_to_uci(pos.is_check() ? -VALUE_MATE : VALUE_DRAW) - << endl; + cout << "info" << depth_to_uci(DEPTH_ZERO) + << score_to_uci(pos.in_check() ? -VALUE_MATE : VALUE_DRAW, alpha, beta) << endl; return MOVE_NONE; } @@ -614,58 +527,94 @@ namespace { // Iterative deepening loop until requested to stop or target depth reached while (!StopRequest && ++depth <= PLY_MAX && (!Limits.maxDepth || depth <= Limits.maxDepth)) { + // Save last iteration's scores, this needs to be done now, because in + // the following MultiPV loop Rml moves could be reordered. + for (size_t i = 0; i < Rml.size(); i++) + Rml[i].prevScore = Rml[i].score; + Rml.bestMoveChanges = 0; - cout << set960(pos.is_chess960()) << "info depth " << depth << endl; - // Calculate dynamic aspiration window based on previous iterations - if (MultiPV == 1 && depth >= 5 && abs(bestValues[depth - 1]) < VALUE_KNOWN_WIN) + // MultiPV iteration loop + for (MultiPVIteration = 0; MultiPVIteration < Min(MultiPV, (int)Rml.size()); MultiPVIteration++) { - int prevDelta1 = bestValues[depth - 1] - bestValues[depth - 2]; - int prevDelta2 = bestValues[depth - 2] - bestValues[depth - 3]; - - aspirationDelta = Min(Max(abs(prevDelta1) + abs(prevDelta2) / 2, 16), 24); - aspirationDelta = (aspirationDelta + 7) / 8 * 8; // Round to match grainSize - - alpha = Max(bestValues[depth - 1] - aspirationDelta, -VALUE_INFINITE); - beta = Min(bestValues[depth - 1] + aspirationDelta, VALUE_INFINITE); - } - - // 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); - - // 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); - - // Value cannot be trusted. Break out immediately! - if (StopRequest) - break; + // Calculate dynamic aspiration window based on previous iterations + if (depth >= 5 && abs(Rml[MultiPVIteration].prevScore) < VALUE_KNOWN_WIN) + { + int prevDelta1 = bestValues[depth - 1] - bestValues[depth - 2]; + int prevDelta2 = bestValues[depth - 2] - bestValues[depth - 3]; - assert(value >= alpha); + aspirationDelta = Min(Max(abs(prevDelta1) + abs(prevDelta2) / 2, 16), 24); + aspirationDelta = (aspirationDelta + 7) / 8 * 8; // Round to match grainSize - // In case of failing high/low increase aspiration window and research, - // otherwise exit the fail high/low loop. - if (value >= beta) - { - beta = Min(beta + aspirationDelta, VALUE_INFINITE); - aspirationDelta += aspirationDelta / 2; + alpha = Max(Rml[MultiPVIteration].prevScore - aspirationDelta, -VALUE_INFINITE); + beta = Min(Rml[MultiPVIteration].prevScore + aspirationDelta, VALUE_INFINITE); } - else if (value <= alpha) + else { - AspirationFailLow = true; - StopOnPonderhit = false; - - alpha = Max(alpha - aspirationDelta, -VALUE_INFINITE); - aspirationDelta += aspirationDelta / 2; + alpha = -VALUE_INFINITE; + beta = VALUE_INFINITE; } - else - break; - } while (abs(value) < VALUE_KNOWN_WIN); + // 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 referencing (ss-1). This is + // needed by update_gains() and ss copy when splitting at Root. + value = search(pos, ss+1, alpha, beta, depth * ONE_PLY); + + // It is critical that sorting is done with a stable algorithm + // because all the values but the first are usually set to + // -VALUE_INFINITE and we want to keep the same order for all + // the moves but the new PV that goes to head. + sort(Rml.begin() + MultiPVIteration, Rml.end()); + + // In case we have found an exact score reorder the PV moves + // before leaving the fail high/low loop, otherwise leave the + // last PV move in its position so to be searched again. + if (value > alpha && value < beta) + sort(Rml.begin(), Rml.begin() + MultiPVIteration); + + // Write PV back to transposition table in case the relevant entries + // have been overwritten during the search. + for (int i = 0; i <= MultiPVIteration; i++) + Rml[i].insert_pv_in_tt(pos); + + // Value cannot be trusted. Break out immediately! + if (StopRequest) + break; + + // Send full PV info to GUI if we are going to leave the loop or + // if we have a fail high/low and we are deep in the search. + if ((value > alpha && value < beta) || current_search_time() > 2000) + for (int i = 0; i < Min(UCIMultiPV, MultiPVIteration + 1); i++) + cout << "info" + << depth_to_uci(depth * ONE_PLY) + << (i == MultiPVIteration ? score_to_uci(Rml[i].score, alpha, beta) : + score_to_uci(Rml[i].score)) + << speed_to_uci(pos.nodes_searched()) + << pv_to_uci(&Rml[i].pv[0], i + 1, pos.is_chess960()) + << endl; + + // In case of failing high/low increase aspiration window and research, + // otherwise exit the fail high/low loop. + if (value >= beta) + { + beta = Min(beta + aspirationDelta, VALUE_INFINITE); + aspirationDelta += aspirationDelta / 2; + } + else if (value <= alpha) + { + AspirationFailLow = true; + StopOnPonderhit = false; + + alpha = Max(alpha - aspirationDelta, -VALUE_INFINITE); + aspirationDelta += aspirationDelta / 2; + } + else + break; + + } while (abs(value) < VALUE_KNOWN_WIN); + } // Collect info about search result bestMove = Rml[0].pv[0]; @@ -677,21 +626,11 @@ namespace { if (SkillLevelEnabled && depth == 1 + SkillLevel) do_skill_level(&skillBest, &skillPonder); - // 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; - - // 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; - if (LogFile.is_open()) - LogFile << pretty_pv(pos, depth, value, current_search_time(), Rml[0].pv) << endl; + LogFile << pretty_pv(pos, depth, value, current_search_time(), &Rml[0].pv[0]) << endl; // 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)) + if (depth == 1 && (Rml.size() == 1 || Rml[0].score > Rml[1].score + EasyMoveMargin)) easyMove = bestMove; else if (bestMove != easyMove) easyMove = MOVE_NONE; @@ -699,12 +638,6 @@ namespace { // Check for some early stop condition if (!StopRequest && Limits.useTimeManagement()) { - // 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. @@ -756,13 +689,17 @@ namespace { // 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 + template Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth) { + const bool PvNode = (NT == PV || NT == Root || NT == SplitPointPV || NT == SplitPointRoot); + const bool SpNode = (NT == SplitPointPV || NT == SplitPointNonPV || NT == SplitPointRoot); + const bool RootNode = (NT == Root || NT == SplitPointRoot); + assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE); assert(beta > alpha && beta <= VALUE_INFINITE); assert(PvNode || alpha == beta - 1); - assert(pos.thread() >= 0 && pos.thread() < ThreadsMgr.active_threads()); + assert(pos.thread() >= 0 && pos.thread() < Threads.size()); Move movesSearched[MAX_MOVES]; int64_t nodes; @@ -773,22 +710,29 @@ namespace { Depth ext, newDepth; ValueType vt; Value bestValue, value, oldAlpha; - Value refinedValue, nullValue, futilityBase, futilityValueScaled; // Non-PV specific - bool isPvMove, isCheck, singularExtensionNode, moveIsCheck, captureOrPromotion, dangerous, isBadCap; + Value refinedValue, nullValue, futilityBase, futilityValue; + bool isPvMove, inCheck, singularExtensionNode, givesCheck, captureOrPromotion, dangerous; int moveCount = 0, playedMoveCount = 0; - int threadID = pos.thread(); + Thread& thread = Threads[pos.thread()]; SplitPoint* sp = NULL; refinedValue = bestValue = value = -VALUE_INFINITE; oldAlpha = alpha; - isCheck = pos.is_check(); + inCheck = pos.in_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 (PvNode && thread.maxPly < ss->ply) + thread.maxPly = ss->ply; - if (SpNode) + // Step 1. Initialize node and poll. Polling can abort search + if (!SpNode) + { + ss->currentMove = ss->bestMove = threatMove = (ss+1)->excludedMove = MOVE_NONE; + (ss+1)->skipNullMove = false; (ss+1)->reduction = DEPTH_ZERO; + (ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE; + } + else { sp = ss->sp; tte = NULL; @@ -796,15 +740,8 @@ namespace { threatMove = sp->threatMove; goto split_point_start; } - else if (Root) - bestValue = alpha; - - // Step 1. Initialize node and poll. Polling can abort search - 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) + if (pos.thread() == 0 && ++NodesSincePoll > NodesBetweenPolls) { NodesSincePoll = 0; poll(pos); @@ -812,33 +749,33 @@ namespace { // Step 2. Check for aborted search and immediate draw if (( StopRequest - || ThreadsMgr.cutoff_at_splitpoint(threadID) - || pos.is_draw() - || ss->ply > PLY_MAX) && !Root) + || pos.is_draw() + || ss->ply > PLY_MAX) && !RootNode) return VALUE_DRAW; // Step 3. Mate distance pruning - alpha = Max(value_mated_in(ss->ply), alpha); - beta = Min(value_mate_in(ss->ply+1), beta); - if (alpha >= beta) - return alpha; + if (!RootNode) + { + 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. excludedMove = ss->excludedMove; posKey = excludedMove ? pos.get_exclusion_key() : pos.get_key(); - - tte = TT.retrieve(posKey); - ttMove = tte ? tte->move() : MOVE_NONE; + tte = TT.probe(posKey); + ttMove = RootNode ? Rml[MultiPVIteration].pv[0] : 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))) + // smooth experience in analysis mode. We don't probe at Root nodes otherwise + // we should also update RootMoveList to avoid bogus output. + if (!RootNode && tte && (PvNode ? tte->depth() >= depth && tte->type() == VALUE_TYPE_EXACT + : can_return_tt(tte, depth, beta, ss->ply))) { TT.refresh(tte); ss->bestMove = ttMove; // Can be MOVE_NONE @@ -846,7 +783,7 @@ namespace { } // Step 5. Evaluate the position statically and update parent's gain statistics - if (isCheck) + if (inCheck) ss->eval = ss->evalMargin = VALUE_NONE; else if (tte) { @@ -868,7 +805,7 @@ namespace { // Step 6. Razoring (is omitted in PV nodes) if ( !PvNode && depth < RazorDepth - && !isCheck + && !inCheck && refinedValue + razor_margin(depth) < beta && ttMove == MOVE_NONE && abs(beta) < VALUE_MATE_IN_PLY_MAX @@ -888,7 +825,7 @@ namespace { if ( !PvNode && !ss->skipNullMove && depth < RazorDepth - && !isCheck + && !inCheck && refinedValue - futility_margin(depth, 0) >= beta && abs(beta) < VALUE_MATE_IN_PLY_MAX && pos.non_pawn_material(pos.side_to_move())) @@ -898,7 +835,7 @@ namespace { if ( !PvNode && !ss->skipNullMove && depth > ONE_PLY - && !isCheck + && !inCheck && refinedValue >= beta && abs(beta) < VALUE_MATE_IN_PLY_MAX && pos.non_pawn_material(pos.side_to_move())) @@ -914,7 +851,8 @@ namespace { pos.do_null_move(st); (ss+1)->skipNullMove = true; - nullValue = -search(pos, ss+1, -beta, -alpha, depth-R*ONE_PLY); + nullValue = depth-R*ONE_PLY < ONE_PLY ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) + : - search(pos, ss+1, -beta, -alpha, depth-R*ONE_PLY); (ss+1)->skipNullMove = false; pos.undo_null_move(); @@ -953,33 +891,62 @@ namespace { } } - // Step 9. Internal iterative deepening + // Step 9. ProbCut (is omitted in PV nodes) + // If we have a very good capture (i.e. SEE > seeValues[captured_piece_type]) + // and a reduced search returns a value much above beta, we can (almost) safely + // prune the previous move. + if ( !PvNode + && depth >= RazorDepth + ONE_PLY + && !inCheck + && !ss->skipNullMove + && excludedMove == MOVE_NONE + && abs(beta) < VALUE_MATE_IN_PLY_MAX) + { + Value rbeta = beta + 200; + Depth rdepth = depth - ONE_PLY - 3 * ONE_PLY; + + assert(rdepth >= ONE_PLY); + + MovePicker mp(pos, ttMove, H, pos.captured_piece_type()); + CheckInfo ci(pos); + + while ((move = mp.get_next_move()) != MOVE_NONE) + if (pos.pl_move_is_legal(move, ci.pinned)) + { + pos.do_move(move, st, ci, pos.move_gives_check(move, ci)); + value = -search(pos, ss+1, -rbeta, -rbeta+1, rdepth); + pos.undo_move(move); + if (value >= rbeta) + return value; + } + } + + // Step 10. Internal iterative deepening if ( depth >= IIDDepth[PvNode] && ttMove == MOVE_NONE - && (PvNode || (!isCheck && ss->eval + IIDMargin >= beta))) + && (PvNode || (!inCheck && ss->eval + IIDMargin >= beta))) { Depth d = (PvNode ? depth - 2 * ONE_PLY : depth / 2); ss->skipNullMove = true; - search(pos, ss, alpha, beta, d); + search(pos, ss, alpha, beta, d); ss->skipNullMove = false; - ttMove = ss->bestMove; - tte = TT.retrieve(posKey); + tte = TT.probe(posKey); + ttMove = tte ? tte->move() : MOVE_NONE; } split_point_start: // At split points actual search starts from here // Initialize a MovePicker object for the current position - MovePickerExt mp(pos, ttMove, depth, H, ss, (PvNode ? -VALUE_INFINITE : beta)); + MovePickerExt mp(pos, ttMove, depth, H, ss, PvNode ? -VALUE_INFINITE : beta); CheckInfo ci(pos); ss->bestMove = MOVE_NONE; futilityBase = ss->eval + ss->evalMargin; - singularExtensionNode = !Root + singularExtensionNode = !RootNode && !SpNode && depth >= SingularExtensionDepth[PvNode] - && tte - && tte->move() + && ttMove != MOVE_NONE && !excludedMove // Do not allow recursive singular extension search && (tte->type() & VALUE_TYPE_LOWER) && tte->depth() >= depth - 3 * ONE_PLY; @@ -989,25 +956,36 @@ split_point_start: // At split points actual search starts from here bestValue = sp->bestValue; } - // Step 10. Loop through moves - // Loop through all legal moves until no moves remain or a beta cutoff occurs + // Step 11. Loop through moves + // Loop through all pseudo-legal moves until no moves remain or a beta cutoff occurs while ( bestValue < beta && (move = mp.get_next_move()) != MOVE_NONE - && !ThreadsMgr.cutoff_at_splitpoint(threadID)) + && !thread.cutoff_occurred()) { assert(move_is_ok(move)); + if (move == excludedMove) + continue; + + // At root obey the "searchmoves" option and skip moves not listed in Root Move List. + // Also in MultiPV mode we skip moves which already have got an exact score + // in previous MultiPV Iteration. Finally any illegal move is skipped here. + if (RootNode && !Rml.find(move, MultiPVIteration)) + continue; + + // At PV and SpNode nodes we want all moves to be legal since the beginning + if ((PvNode || SpNode) && !pos.pl_move_is_legal(move, ci.pinned)) + continue; + if (SpNode) { moveCount = ++sp->moveCount; lock_release(&(sp->lock)); } - else if (move == excludedMove) - continue; else moveCount++; - if (Root) + if (RootNode) { // This is used by time management FirstRootMove = (moveCount == 1); @@ -1015,26 +993,20 @@ split_point_start: // At split points actual search starts from here // 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; + // For long searches send current move info to GUI + if (pos.thread() == 0 && current_search_time() > 2000) + cout << "info" << depth_to_uci(depth) + << " currmove " << move + << " currmovenumber " << moveCount + MultiPVIteration << 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); + isPvMove = (PvNode && moveCount <= (RootNode && depth <= ONE_PLY ? MAX_MOVES : 1)); + givesCheck = pos.move_gives_check(move, ci); captureOrPromotion = pos.move_is_capture_or_promotion(move); - // Step 11. Decide the new search depth - ext = extension(pos, move, captureOrPromotion, moveIsCheck, &dangerous); + // Step 12. Decide the new search depth + ext = extension(pos, move, captureOrPromotion, givesCheck, &dangerous); // 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 @@ -1042,7 +1014,8 @@ split_point_start: // At split points actual search starts from here // 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() + && move == ttMove + && pos.pl_move_is_legal(move, ci.pinned) && ext < ONE_PLY) { Value ttValue = value_from_tt(tte->value(), ss->ply); @@ -1062,13 +1035,12 @@ split_point_start: // At split points actual search starts from here } // Update current move (this must be done after singular extension search) - ss->currentMove = move; newDepth = depth - ONE_PLY + ext; - // Step 12. Futility pruning (is omitted in PV nodes) + // Step 13. Futility pruning (is omitted in PV nodes) if ( !PvNode && !captureOrPromotion - && !isCheck + && !inCheck && !dangerous && move != ttMove && !move_is_castle(move)) @@ -1087,20 +1059,20 @@ split_point_start: // At split points actual search starts from here // Value based pruning // 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 = futilityBase + futility_margin(predictedDepth, moveCount) - + H.gain(pos.piece_on(move_from(move)), move_to(move)); + Depth predictedDepth = newDepth - reduction(depth, moveCount); + futilityValue = futilityBase + futility_margin(predictedDepth, moveCount) + + H.gain(pos.piece_on(move_from(move)), move_to(move)); - if (futilityValueScaled < beta) + if (futilityValue < beta) { if (SpNode) { lock_grab(&(sp->lock)); - if (futilityValueScaled > sp->bestValue) - sp->bestValue = bestValue = futilityValueScaled; + if (futilityValue > sp->bestValue) + sp->bestValue = bestValue = futilityValue; } - else if (futilityValueScaled > bestValue) - bestValue = futilityValueScaled; + else if (futilityValue > bestValue) + bestValue = futilityValue; continue; } @@ -1117,90 +1089,71 @@ split_point_start: // At split points actual search starts from here } } - // 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); + // Check for legality only before to do the move + if (!pos.pl_move_is_legal(move, ci.pinned)) + { + moveCount--; + continue; + } + ss->currentMove = move; if (!SpNode && !captureOrPromotion) movesSearched[playedMoveCount++] = move; + // Step 14. Make the move + pos.do_move(move, st, ci, givesCheck); + // Step extra. pv search (only in PV nodes) // The first move in list is the expected PV 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); - } + value = newDepth < ONE_PLY ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) + : - search(pos, ss+1, -beta, -alpha, newDepth); else { - // Step 14. Reduced depth search + // Step 15. 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 * ONE_PLY + if ( depth > 3 * ONE_PLY && !captureOrPromotion && !dangerous && !move_is_castle(move) && ss->killers[0] != move - && ss->killers[1] != move) + && ss->killers[1] != move + && (ss->reduction = reduction(depth, moveCount)) != DEPTH_ZERO) { - ss->reduction = reduction(depth, moveCount); - if (ss->reduction) - { - alpha = SpNode ? sp->alpha : alpha; - Depth d = newDepth - ss->reduction; - value = -search(pos, ss+1, -(alpha+1), -alpha, d); + Depth d = newDepth - ss->reduction; + alpha = SpNode ? sp->alpha : alpha; - doFullDepthSearch = (value > alpha); - } - ss->reduction = DEPTH_ZERO; // Restore original reduction - } + value = d < ONE_PLY ? -qsearch(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO) + : - search(pos, ss+1, -(alpha+1), -alpha, d); - // 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 + ss->reduction = DEPTH_ZERO; + doFullDepthSearch = (value > alpha); } - // Step 15. Full depth search + // Step 16. Full depth search if (doFullDepthSearch) { alpha = SpNode ? sp->alpha : alpha; - value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth); + value = newDepth < ONE_PLY ? -qsearch(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO) + : - 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 && (Root || value < beta)) - value = -search(pos, ss+1, -beta, -alpha, newDepth); + if (PvNode && value > alpha && (RootNode || value < beta)) + value = newDepth < ONE_PLY ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) + : - search(pos, ss+1, -beta, -alpha, newDepth); } } - // Step 16. Undo move + // Step 17. Undo move pos.undo_move(move); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); - // Step 17. Check for new best move + // Step 18. Check for new best move if (SpNode) { lock_grab(&(sp->lock)); @@ -1208,100 +1161,78 @@ split_point_start: // At split points actual search starts from here alpha = sp->alpha; } - if (value > bestValue && !(SpNode && ThreadsMgr.cutoff_at_splitpoint(threadID))) - { - bestValue = value; - - if (SpNode) - sp->bestValue = value; - - if (!Root && value > alpha) - { - if (PvNode && value < beta) // We want always alpha < beta - { - alpha = value; - - if (SpNode) - sp->alpha = value; - } - else if (SpNode) - sp->betaCutoff = true; - - if (value == value_mate_in(ss->ply + 1)) - ss->mateKiller = move; - - ss->bestMove = move; - - if (SpNode) - sp->ss->bestMove = move; - } - } - - 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 don't update the best move and/or PV. + if (RootNode && !StopRequest) { - // 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; + RootMove* rm = Rml.find(move); + 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); + rm->score = value; + rm->extract_pv_from_tt(pos); // We record how often the best move has been changed in each // iteration. This information is used for time management: When // the best move changes frequently, we allocate some more time. if (!isPvMove && MultiPV == 1) Rml.bestMoveChanges++; - - 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; + // All other moves but the PV are set to the lowest value, this + // is not a problem when sorting becuase sort is stable and move + // position in the list is preserved, just the PV is pushed up. + rm->score = -VALUE_INFINITE; + + } // RootNode + + if (value > bestValue) + { + bestValue = value; + ss->bestMove = move; + + if ( PvNode + && value > alpha + && value < beta) // We want always alpha < beta + alpha = value; - } // Root + if (SpNode && !thread.cutoff_occurred()) + { + sp->bestValue = value; + sp->ss->bestMove = move; + sp->alpha = alpha; + sp->is_betaCutoff = (value >= beta); + } + } - // Step 18. Check for split - if ( !Root - && !SpNode - && depth >= ThreadsMgr.min_split_depth() - && ThreadsMgr.active_threads() > 1 + // Step 19. Check for split + if ( !SpNode + && depth >= Threads.min_split_depth() && bestValue < beta - && ThreadsMgr.available_thread_exists(threadID) + && Threads.available_slave_exists(pos.thread()) && !StopRequest - && !ThreadsMgr.cutoff_at_splitpoint(threadID)) - ThreadsMgr.split(pos, ss, &alpha, beta, &bestValue, depth, - threatMove, moveCount, &mp, PvNode); + && !thread.cutoff_occurred()) + bestValue = Threads.split(pos, ss, alpha, beta, bestValue, depth, + threatMove, moveCount, &mp, NT); } - // Step 19. Check for mate and stalemate + // Step 20. Check for mate and stalemate // All legal moves have been searched and if there are // no legal moves, it must be mate or stalemate. // If one move was excluded return fail low score. if (!SpNode && !moveCount) - return excludedMove ? oldAlpha : isCheck ? value_mated_in(ss->ply) : VALUE_DRAW; + return excludedMove ? oldAlpha : inCheck ? value_mated_in(ss->ply) : VALUE_DRAW; - // Step 20. Update tables + // Step 21. Update tables // If the search is not aborted, update the transposition table, // history counters, and killer moves. - if (!SpNode && !StopRequest && !ThreadsMgr.cutoff_at_splitpoint(threadID)) + if (!SpNode && !StopRequest && !thread.cutoff_occurred()) { move = bestValue <= oldAlpha ? MOVE_NONE : ss->bestMove; vt = bestValue <= oldAlpha ? VALUE_TYPE_UPPER @@ -1325,7 +1256,7 @@ split_point_start: // At split points actual search starts from here if (SpNode) { // Here we have the lock still grabbed - sp->slaves[threadID] = 0; + sp->is_slave[pos.thread()] = false; sp->nodes += pos.nodes_searched(); lock_release(&(sp->lock)); } @@ -1339,49 +1270,53 @@ split_point_start: // At split points actual search starts from here // search function when the remaining depth is zero (or, to be more precise, // less than ONE_PLY). - template + template Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth) { + const bool PvNode = (NT == PV); + + assert(NT == PV || NT == NonPV); assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE); assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE); assert(PvNode || alpha == beta - 1); assert(depth <= 0); - assert(pos.thread() >= 0 && pos.thread() < ThreadsMgr.active_threads()); + assert(pos.thread() >= 0 && pos.thread() < Threads.size()); StateInfo st; Move ttMove, move; Value bestValue, value, evalMargin, futilityValue, futilityBase; - bool isCheck, enoughMaterial, moveIsCheck, evasionPrunable; + bool inCheck, enoughMaterial, givesCheck, evasionPrunable; const TTEntry* tte; Depth ttDepth; + ValueType vt; Value oldAlpha = alpha; ss->bestMove = ss->currentMove = MOVE_NONE; ss->ply = (ss-1)->ply + 1; // Check for an instant draw or maximum ply reached - if (ss->ply > PLY_MAX || pos.is_draw()) + if (pos.is_draw() || ss->ply > PLY_MAX) 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); + inCheck = pos.in_check(); + ttDepth = (inCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS : DEPTH_QS_NO_CHECKS); // Transposition table lookup. At PV nodes, we don't use the TT for // pruning, but only for move ordering. - tte = TT.retrieve(pos.get_key()); + tte = TT.probe(pos.get_key()); ttMove = (tte ? tte->move() : MOVE_NONE); - if (!PvNode && tte && ok_to_use_TT(tte, ttDepth, beta, ss->ply)) + if (!PvNode && tte && can_return_tt(tte, ttDepth, beta, ss->ply)) { ss->bestMove = ttMove; // Can be MOVE_NONE return value_from_tt(tte->value(), ss->ply); } // Evaluate the position statically - if (isCheck) + if (inCheck) { bestValue = futilityBase = -VALUE_INFINITE; ss->eval = evalMargin = VALUE_NONE; @@ -1399,8 +1334,6 @@ split_point_start: // At split points actual search starts from here else ss->eval = bestValue = evaluate(pos, evalMargin); - 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) { @@ -1422,34 +1355,35 @@ split_point_start: // At split points actual search starts from here // to search the moves. Because the depth is <= 0 here, only captures, // queen promotions and checks (only if depth >= DEPTH_QS_CHECKS) will // be generated. - MovePicker mp(pos, ttMove, depth, H); + MovePicker mp(pos, ttMove, depth, H, move_to((ss-1)->currentMove)); CheckInfo ci(pos); // Loop through the moves until no moves remain or a beta cutoff occurs - while ( alpha < beta + while ( bestValue < beta && (move = mp.get_next_move()) != MOVE_NONE) { assert(move_is_ok(move)); - moveIsCheck = pos.move_is_check(move, ci); + givesCheck = pos.move_gives_check(move, ci); // Futility pruning if ( !PvNode - && !isCheck - && !moveIsCheck + && !inCheck + && !givesCheck && move != ttMove && enoughMaterial && !move_is_promotion(move) && !pos.move_is_passed_pawn_push(move)) { futilityValue = futilityBase - + pos.endgame_value_of_piece_on(move_to(move)) + + piece_value_endgame(pos.piece_on(move_to(move))) + (move_is_ep(move) ? PawnValueEndgame : VALUE_ZERO); - if (futilityValue < alpha) + if (futilityValue < beta) { if (futilityValue > bestValue) bestValue = futilityValue; + continue; } @@ -1461,14 +1395,15 @@ split_point_start: // At split points actual search starts from here } // Detect non-capture evasions that are candidate to be pruned - evasionPrunable = isCheck + evasionPrunable = !PvNode + && inCheck && bestValue > VALUE_MATED_IN_PLY_MAX && !pos.move_is_capture(move) && !pos.can_castle(pos.side_to_move()); // Don't search moves with negative SEE values if ( !PvNode - && (!isCheck || evasionPrunable) + && (!inCheck || evasionPrunable) && move != ttMove && !move_is_promotion(move) && pos.see_sign(move) < 0) @@ -1476,8 +1411,8 @@ split_point_start: // At split points actual search starts from here // Don't search useless checks if ( !PvNode - && !isCheck - && moveIsCheck + && !inCheck + && givesCheck && move != ttMove && !pos.move_is_capture_or_promotion(move) && ss->eval + PawnValueMidgame / 4 < beta @@ -1489,12 +1424,16 @@ split_point_start: // At split points actual search starts from here continue; } + // Check for legality only before to do the move + if (!pos.pl_move_is_legal(move, ci.pinned)) + continue; + // Update current move ss->currentMove = move; // Make and search the move - pos.do_move(move, st, ci, moveIsCheck); - value = -qsearch(pos, ss+1, -beta, -alpha, depth-ONE_PLY); + pos.do_move(move, st, ci, givesCheck); + value = -qsearch(pos, ss+1, -beta, -alpha, depth-ONE_PLY); pos.undo_move(move); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); @@ -1503,22 +1442,26 @@ split_point_start: // At split points actual search starts from here if (value > bestValue) { bestValue = value; - if (value > alpha) - { + ss->bestMove = move; + + if ( PvNode + && value > alpha + && value < beta) // We want always alpha < beta alpha = value; - ss->bestMove = move; - } } } // 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) + if (inCheck && bestValue == -VALUE_INFINITE) return value_mated_in(ss->ply); // Update transposition table - 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); + move = bestValue <= oldAlpha ? MOVE_NONE : ss->bestMove; + 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, move, ss->eval, evalMargin); assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); @@ -1550,23 +1493,23 @@ split_point_start: // At split points actual search starts from here 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); + b = kingAtt & ~pos.pieces(them) & ~newAtt & ~(1ULL << to); if (!(b && (b & (b - 1)))) return true; // Rule 2. Queen contact check is very dangerous - if ( type_of_piece(pc) == QUEEN + if ( piece_type(pc) == QUEEN && bit_is_set(kingAtt, to)) return true; // Rule 3. Creating new double threats with checks - b = pos.pieces_of_color(them) & newAtt & ~oldAtt & ~(1ULL << ksq); + b = pos.pieces(them) & newAtt & ~oldAtt & ~(1ULL << ksq); while (b) { victimSq = pop_1st_bit(&b); - futilityValue = futilityBase + pos.endgame_value_of_piece_on(victimSq); + futilityValue = futilityBase + piece_value_endgame(pos.piece_on(victimSq)); // Note that here we generate illegal "double move"! if ( futilityValue >= beta @@ -1592,7 +1535,8 @@ split_point_start: // At split points actual search starts from here bool connected_moves(const Position& pos, Move m1, Move m2) { Square f1, t1, f2, t2; - Piece p; + Piece p1, p2; + Square ksq; assert(m1 && move_is_ok(m1)); assert(m2 && move_is_ok(m2)); @@ -1610,26 +1554,24 @@ split_point_start: // At split points actual search starts from here return true; // Case 3: Moving through the vacated square - if ( piece_is_slider(pos.piece_on(f2)) + p2 = pos.piece_on(f2); + if ( piece_is_slider(p2) && bit_is_set(squares_between(f2, t2), f1)) return true; // Case 4: The destination square for m2 is defended by the moving piece in m1 - p = pos.piece_on(t1); - if (bit_is_set(pos.attacks_from(p, t1), t2)) + p1 = pos.piece_on(t1); + if (bit_is_set(pos.attacks_from(p1, t1), t2)) return true; // Case 5: Discovered check, checking piece is the piece moved in m1 - if ( piece_is_slider(p) - && bit_is_set(squares_between(t1, pos.king_square(pos.side_to_move())), f2) - && !bit_is_set(squares_between(t1, pos.king_square(pos.side_to_move())), t2)) + ksq = pos.king_square(pos.side_to_move()); + if ( piece_is_slider(p1) + && bit_is_set(squares_between(t1, ksq), f2)) { - // discovered_check_candidates() works also if the Position's side to - // move is the opposite of the checking piece. - Color them = opposite_color(pos.side_to_move()); - Bitboard dcCandidates = pos.discovered_check_candidates(them); - - if (bit_is_set(dcCandidates, f2)) + Bitboard occ = pos.occupied_squares(); + clear_bit(&occ, f2); + if (bit_is_set(pos.attacks_from(p1, t1, occ), ksq)) return true; } return false; @@ -1667,61 +1609,13 @@ split_point_start: // At split points actual search starts from here } - // extension() decides whether a move should be searched with normal depth, - // or with extended depth. Certain classes of moves (checking moves, in - // particular) are searched with bigger depth than ordinary moves and in - // any case are marked as 'dangerous'. Note that also if a move is not - // extended, as example because the corresponding UCI option is set to zero, - // the move is marked as 'dangerous' so, at least, we avoid to prune it. - template - Depth extension(const Position& pos, Move m, bool captureOrPromotion, - bool moveIsCheck, bool* dangerous) { - - assert(m != MOVE_NONE); + // connected_threat() tests whether it is safe to forward prune a move or if + // is somehow connected to the threat move returned by null search. - Depth result = DEPTH_ZERO; - *dangerous = moveIsCheck; - - if (moveIsCheck && pos.see_sign(m) >= 0) - result += CheckExtension[PvNode]; - - if (pos.type_of_piece_on(move_from(m)) == PAWN) - { - Color c = pos.side_to_move(); - if (relative_rank(c, move_to(m)) == RANK_7) - { - result += PawnPushTo7thExtension[PvNode]; - *dangerous = true; - } - if (pos.pawn_is_passed(c, move_to(m))) - { - result += PassedPawnExtension[PvNode]; - *dangerous = true; - } - } - - 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_ZERO) - && !move_is_special(m)) - { - result += PawnEndgameExtension[PvNode]; - *dangerous = true; - } - - return Min(result, ONE_PLY); - } - - - // connected_threat() tests whether it is safe to forward prune a move or if - // is somehow connected to the threat move returned by null search. - - bool connected_threat(const Position& pos, Move m, Move threat) { + bool connected_threat(const Position& pos, Move m, Move threat) { assert(move_is_ok(m)); assert(threat && move_is_ok(threat)); - assert(!pos.move_is_check(m)); assert(!pos.move_is_capture_or_promotion(m)); assert(!pos.move_is_passed_pawn_push(m)); @@ -1739,8 +1633,8 @@ split_point_start: // At split points actual search starts from here // Case 2: If the threatened piece has value less than or equal to the // value of the threatening piece, don't prune moves which defend it. if ( pos.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) + && ( piece_value_midgame(pos.piece_on(tfrom)) >= piece_value_midgame(pos.piece_on(tto)) + || piece_type(pos.piece_on(tfrom)) == KING) && pos.move_attacks_square(m, tto)) return true; @@ -1755,10 +1649,10 @@ split_point_start: // At split points actual search starts from here } - // ok_to_use_TT() returns true if a transposition table score - // can be used at a given point in search. + // can_return_tt() returns true if a transposition table score + // can be used to cut-off at a given point in search. - bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply) { + bool can_return_tt(const TTEntry* tte, Depth depth, Value beta, int ply) { Value v = value_from_tt(tte->value(), ply); @@ -1837,21 +1731,23 @@ split_point_start: // At split points actual search starts from here } - // value_to_uci() converts a value to a string suitable for use with the UCI + // score_to_uci() converts a value to a string suitable for use with the UCI // protocol specifications: // // cp The score from the engine's point of view in centipawns. // mate Mate in y moves, not plies. If the engine is getting mated // use negative values for y. - std::string value_to_uci(Value v) { + string score_to_uci(Value v, Value alpha, Value beta) { std::stringstream s; if (abs(v) < VALUE_MATE - PLY_MAX * ONE_PLY) - s << "cp " << int(v) * 100 / int(PawnValueMidgame); // Scale to centipawns + s << " score cp " << int(v) * 100 / int(PawnValueMidgame); // Scale to centipawns else - s << "mate " << (v > 0 ? VALUE_MATE - v + 1 : -VALUE_MATE - v) / 2; + s << " score mate " << (v > 0 ? VALUE_MATE - v + 1 : -VALUE_MATE - v) / 2; + + s << (v >= beta ? " lowerbound" : v <= alpha ? " upperbound" : ""); return s.str(); } @@ -1860,18 +1756,134 @@ split_point_start: // At split points actual search starts from here // 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) { + string speed_to_uci(int64_t nodes) { std::stringstream s; int t = current_search_time(); s << " nodes " << nodes - << " nps " << (t > 0 ? int(nodes * 1000 / t) : 0) + << " nps " << (t > 0 ? int(nodes * 1000 / t) : 0) << " time " << t; return s.str(); } + // pv_to_uci() returns a string with information on the current PV line + // formatted according to UCI specification. + + string pv_to_uci(const Move pv[], int pvNum, bool chess960) { + + std::stringstream s; + + s << " multipv " << pvNum << " pv " << set960(chess960); + + for ( ; *pv != MOVE_NONE; pv++) + s << *pv << " "; + + return s.str(); + } + + // depth_to_uci() returns a string with information on the current depth and + // seldepth formatted according to UCI specification. + + string depth_to_uci(Depth depth) { + + std::stringstream s; + + // Retrieve max searched depth among threads + int selDepth = 0; + for (int i = 0; i < Threads.size(); i++) + if (Threads[i].maxPly > selDepth) + selDepth = Threads[i].maxPly; + + s << " depth " << depth / ONE_PLY << " seldepth " << selDepth; + + return s.str(); + } + + string time_to_string(int millisecs) { + + const int MSecMinute = 1000 * 60; + const int MSecHour = 1000 * 60 * 60; + + int hours = millisecs / MSecHour; + int minutes = (millisecs % MSecHour) / MSecMinute; + int seconds = ((millisecs % MSecHour) % MSecMinute) / 1000; + + std::stringstream s; + + if (hours) + s << hours << ':'; + + s << std::setfill('0') << std::setw(2) << minutes << ':' << std::setw(2) << seconds; + return s.str(); + } + + string score_to_string(Value v) { + + std::stringstream s; + + if (v >= VALUE_MATE_IN_PLY_MAX) + s << "#" << (VALUE_MATE - v + 1) / 2; + else if (v <= VALUE_MATED_IN_PLY_MAX) + s << "-#" << (VALUE_MATE + v) / 2; + else + s << std::setprecision(2) << std::fixed << std::showpos << float(v) / PawnValueMidgame; + + return s.str(); + } + + // pretty_pv() creates a human-readable string from a position and a PV. + // It is used to write search information to the log file (which is created + // when the UCI parameter "Use Search Log" is "true"). + + string pretty_pv(Position& pos, int depth, Value value, int time, Move pv[]) { + + const int64_t K = 1000; + const int64_t M = 1000000; + const int startColumn = 28; + const size_t maxLength = 80 - startColumn; + + StateInfo state[PLY_MAX_PLUS_2], *st = state; + Move* m = pv; + string san; + std::stringstream s; + size_t length = 0; + + // First print depth, score, time and searched nodes... + s << set960(pos.is_chess960()) + << std::setw(2) << depth + << std::setw(8) << score_to_string(value) + << std::setw(8) << time_to_string(time); + + if (pos.nodes_searched() < M) + s << std::setw(8) << pos.nodes_searched() / 1 << " "; + else if (pos.nodes_searched() < K * M) + s << std::setw(7) << pos.nodes_searched() / K << "K "; + else + s << std::setw(7) << pos.nodes_searched() / M << "M "; + + // ...then print the full PV line in short algebraic notation + while (*m != MOVE_NONE) + { + san = move_to_san(pos, *m); + length += san.length() + 1; + + if (length > maxLength) + { + length = san.length() + 1; + s << "\n" + string(startColumn, ' '); + } + s << san << ' '; + + pos.do_move(*m++, *st++); + } + + // Restore original position before to leave + while (m != pv) pos.undo_move(*--m); + + return s.str(); + } // poll() performs two different functions: It polls for user input, and it // looks at the time consumed so far and decides if it's time to abort the @@ -1886,7 +1898,7 @@ split_point_start: // At split points actual search starts from here if (input_available()) { // We are line oriented, don't read single chars - std::string command; + string command; if (!std::getline(std::cin, command) || command == "quit") { @@ -1929,9 +1941,6 @@ split_point_start: // At split points actual search starts from here dbg_print_mean(); dbg_print_hit_rate(); - - // Send info on searched nodes as soon as we return to root - SendSearchedNodes = true; } // Should we stop the search? @@ -1961,7 +1970,7 @@ split_point_start: // At split points actual search starts from here void wait_for_stop_or_ponderhit() { - std::string command; + string command; // Wait for a command from stdin while ( std::getline(std::cin, command) @@ -1972,438 +1981,84 @@ split_point_start: // At split points actual search starts from here } - // init_thread() is the function which is called when a new thread is - // launched. It simply calls the idle_loop() function with the supplied - // threadID. There are two versions of this function; one for POSIX - // threads and one for Windows threads. - -#if !defined(_MSC_VER) - - void* init_thread(void* threadID) { - - ThreadsMgr.idle_loop(*(int*)threadID, NULL); - return NULL; - } - -#else - - DWORD WINAPI init_thread(LPVOID threadID) { - - ThreadsMgr.idle_loop(*(int*)threadID, NULL); - return 0; - } - -#endif - - - /// The ThreadsManager class - - - // read_uci_options() updates number of active threads and other internal - // parameters according to the UCI options values. It is called before - // to start a new search. - - void ThreadsManager::read_uci_options() { - - maxThreadsPerSplitPoint = Options["Maximum Number of Threads per Split Point"].value(); - minimumSplitDepth = Options["Minimum Split Depth"].value() * ONE_PLY; - useSleepingThreads = Options["Use Sleeping Threads"].value(); - activeThreads = Options["Threads"].value(); - } - - - // 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. - - void ThreadsManager::idle_loop(int threadID, SplitPoint* sp) { - - assert(threadID >= 0 && threadID < MAX_THREADS); - - int i; - bool allFinished; - - 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); - - if (threads[threadID].state == THREAD_INITIALIZING) - threads[threadID].state = THREAD_AVAILABLE; - - // Grab the lock to avoid races with Thread::wake_up() - lock_grab(&threads[threadID].sleepLock); - - // 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); - - if (allFinished || allThreadsShouldExit) - { - lock_release(&threads[threadID].sleepLock); - break; - } - - // Do sleep here after retesting sleep conditions - if (threadID >= activeThreads || threads[threadID].state == THREAD_AVAILABLE) - cond_wait(&threads[threadID].sleepCond, &threads[threadID].sleepLock); - - lock_release(&threads[threadID].sleepLock); - } - - // If this thread has been assigned work, launch a search - if (threads[threadID].state == THREAD_WORKISWAITING) - { - assert(!allThreadsShouldExit); - - threads[threadID].state = THREAD_SEARCHING; - - // 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; - - if (tsp->pvNode) - search(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth); - else - search(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth); - - assert(threads[threadID].state == THREAD_SEARCHING); - - threads[threadID].state = THREAD_AVAILABLE; - - // 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(); - } - - // 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); - - 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)); - - // 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); - - threads[threadID].state = THREAD_SEARCHING; - return; - } - } - } - - - // init_threads() is called during startup. Initializes locks and condition - // variables and launches all threads sending them immediately to sleep. - - void ThreadsManager::init_threads() { + // 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) { - int i, arg[MAX_THREADS]; - bool ok; + assert(MultiPV > 1); - // This flag is needed to properly end the threads when program exits - allThreadsShouldExit = false; + static RKISS rk; - // Threads will sent to sleep as soon as created, only main thread is kept alive - activeThreads = 1; + // Rml list is already sorted by score in descending order + int s; + int max_s = -VALUE_INFINITE; + int size = Min(MultiPV, (int)Rml.size()); + int max = Rml[0].score; + int var = Min(max - Rml[size - 1].score, PawnValueMidgame); + int wk = 120 - 2 * SkillLevel; - lock_init(&mpLock); + // PRNG sequence should be non deterministic + for (int i = abs(get_system_time() % 50); i > 0; i--) + rk.rand(); - for (i = 0; i < MAX_THREADS; i++) + // 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++) { - // Initialize thread and split point locks - lock_init(&threads[i].sleepLock); - cond_init(&threads[i].sleepCond); + s = Rml[i].score; - for (int j = 0; j < MAX_ACTIVE_SPLIT_POINTS; j++) - lock_init(&(threads[i].splitPoints[j].lock)); + // Don't allow crazy blunders even at very low skills + if (i > 0 && Rml[i-1].score > s + EasyMoveMargin) + break; - // All threads but first should be set to THREAD_INITIALIZING - threads[i].state = (i == 0 ? THREAD_SEARCHING : THREAD_INITIALIZING); - } + // This is our magical formula + s += ((max - s) * wk + var * (rk.rand() % wk)) / 128; - // Create and startup the threads - for (i = 1; i < MAX_THREADS; i++) - { - arg[i] = i; - -#if !defined(_MSC_VER) - pthread_t pthread[1]; - ok = (pthread_create(pthread, NULL, init_thread, (void*)(&arg[i])) == 0); - pthread_detach(pthread[0]); -#else - ok = (CreateThread(NULL, 0, init_thread, (LPVOID)(&arg[i]), 0, NULL) != NULL); -#endif - if (!ok) + if (s > max_s) { - cout << "Failed to create thread number " << i << endl; - exit(EXIT_FAILURE); + max_s = s; + *best = Rml[i].pv[0]; + *ponder = Rml[i].pv[1]; } - - // Wait until the thread has finished launching and is gone to sleep - while (threads[i].state == THREAD_INITIALIZING) {} } } - // exit_threads() is called when the program exits. It makes all the - // helper threads exit cleanly. + /// RootMove and RootMoveList method's definitions - void ThreadsManager::exit_threads() { + void RootMoveList::init(Position& pos, Move searchMoves[]) { - // Force the woken up threads to exit idle_loop() and hence terminate - allThreadsShouldExit = true; + Move* sm; + bestMoveChanges = 0; + clear(); - for (int i = 0; i < MAX_THREADS; i++) + // Generate all legal moves and add them to RootMoveList + for (MoveList ml(pos); !ml.end(); ++ml) { - // Wake up all the threads and waits for termination - if (i != 0) - { - threads[i].wake_up(); - while (threads[i].state != THREAD_TERMINATED) {} - } + // If we have a searchMoves[] list then verify the move + // is in the list before to add it. + for (sm = searchMoves; *sm && *sm != ml.move(); sm++) {} - // Now we can safely destroy the locks and wait conditions - lock_destroy(&threads[i].sleepLock); - cond_destroy(&threads[i].sleepCond); + if (sm != searchMoves && *sm != ml.move()) + continue; - for (int j = 0; j < MAX_ACTIVE_SPLIT_POINTS; j++) - lock_destroy(&(threads[i].splitPoints[j].lock)); + RootMove rm; + rm.pv.push_back(ml.move()); + rm.pv.push_back(MOVE_NONE); + rm.score = rm.prevScore = -VALUE_INFINITE; + rm.nodes = 0; + push_back(rm); } - - lock_destroy(&mpLock); - } - - - // cutoff_at_splitpoint() checks whether a beta cutoff has occurred in - // the thread's currently active split point, or in some ancestor of - // the current split point. - - bool ThreadsManager::cutoff_at_splitpoint(int threadID) const { - - assert(threadID >= 0 && threadID < activeThreads); - - SplitPoint* sp = threads[threadID].splitPoint; - - for ( ; sp && !sp->betaCutoff; sp = sp->parent) {} - return sp != NULL; } + RootMove* RootMoveList::find(const Move& m, int startIndex) { - // 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 { - - assert(slave >= 0 && slave < activeThreads); - assert(master >= 0 && master < activeThreads); - assert(activeThreads > 1); - - if (threads[slave].state != THREAD_AVAILABLE || slave == master) - return false; - - // Make a local copy to be sure doesn't change under our feet - int localActiveSplitPoints = threads[slave].activeSplitPoints; - - // No active split points means that the thread is available as - // a slave for any other thread. - if (localActiveSplitPoints == 0 || 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 (threads[slave].splitPoints[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 search().When all threads have returned from search() then split() returns. - - template - void ThreadsManager::split(Position& pos, SearchStack* ss, Value* alpha, const Value beta, - Value* bestValue, Depth depth, Move threatMove, - int moveCount, MovePicker* mp, bool pvNode) { - assert(pos.is_ok()); - assert(*bestValue >= -VALUE_INFINITE); - assert(*bestValue <= *alpha); - assert(*alpha < beta); - assert(beta <= VALUE_INFINITE); - assert(depth > DEPTH_ZERO); - assert(pos.thread() >= 0 && pos.thread() < activeThreads); - assert(activeThreads > 1); - - int i, master = pos.thread(); - Thread& masterThread = threads[master]; - - 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) - || masterThread.activeSplitPoints >= MAX_ACTIVE_SPLIT_POINTS) - { - lock_release(&mpLock); - return; - } - - // Pick the next available split point object from the split point stack - SplitPoint& splitPoint = masterThread.splitPoints[masterThread.activeSplitPoints++]; - - // Initialize the split point object - splitPoint.parent = masterThread.splitPoint; - splitPoint.master = master; - splitPoint.betaCutoff = false; - splitPoint.depth = depth; - splitPoint.threatMove = threatMove; - splitPoint.alpha = *alpha; - splitPoint.beta = beta; - splitPoint.pvNode = pvNode; - splitPoint.bestValue = *bestValue; - splitPoint.mp = mp; - splitPoint.moveCount = moveCount; - splitPoint.pos = &pos; - splitPoint.nodes = 0; - splitPoint.ss = ss; - for (i = 0; i < activeThreads; i++) - splitPoint.slaves[i] = 0; - - masterThread.splitPoint = &splitPoint; - - // If we are here it means we are not available - assert(masterThread.state != THREAD_AVAILABLE); - - int workersCnt = 1; // At least the master is included - - // Allocate available threads setting state to THREAD_BOOKED - for (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. - for (i = 0; i < activeThreads; i++) - if (i == master || splitPoint.slaves[i]) - { - assert(i == master || threads[i].state == THREAD_BOOKED); - - threads[i].state = THREAD_WORKISWAITING; // This makes the slave to exit from idle_loop() - - if (useSleepingThreads && i != master) - threads[i].wake_up(); - } - - // 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; - masterThread.activeSplitPoints--; - masterThread.splitPoint = splitPoint.parent; - pos.set_nodes_searched(pos.nodes_searched() + splitPoint.nodes); + for (size_t i = startIndex; i < size(); i++) + if ((*this)[i].pv[0] == m) + return &(*this)[i]; - lock_release(&mpLock); - } - - - /// RootMove and RootMoveList method's definitions - - RootMove::RootMove() { - - nodes = 0; - pv_score = non_pv_score = -VALUE_INFINITE; - pv[0] = MOVE_NONE; - } - - RootMove& RootMove::operator=(const RootMove& rm) { - - const Move* src = rm.pv; - Move* dst = pv; - - // Avoid a costly full rm.pv[] copy - do *dst++ = *src; while (*src++ != MOVE_NONE); - - nodes = rm.nodes; - pv_score = rm.pv_score; - non_pv_score = rm.non_pv_score; - return *this; + return NULL; } // extract_pv_from_tt() builds a PV by adding moves from the transposition table. @@ -2416,21 +2071,26 @@ split_point_start: // At split points actual search starts from here StateInfo state[PLY_MAX_PLUS_2], *st = state; TTEntry* tte; int ply = 1; + Move m = pv[0]; - assert(pv[0] != MOVE_NONE && pos.move_is_legal(pv[0])); + assert(m != MOVE_NONE && pos.move_is_pl(m)); - pos.do_move(pv[0], *st++); + pv.clear(); + pv.push_back(m); + pos.do_move(m, *st++); - while ( (tte = TT.retrieve(pos.get_key())) != NULL + while ( (tte = TT.probe(pos.get_key())) != NULL && tte->move() != MOVE_NONE - && pos.move_is_legal(tte->move()) + && pos.move_is_pl(tte->move()) + && pos.pl_move_is_legal(tte->move(), pos.pinned_pieces()) && ply < PLY_MAX - && (!pos.is_draw() || ply < 2)) + && (!pos.is_draw() || ply < 2)) { - pv[ply] = tte->move(); - pos.do_move(pv[ply++], *st++); + pv.push_back(tte->move()); + pos.do_move(tte->move(), *st++); + ply++; } - pv[ply] = MOVE_NONE; + pv.push_back(MOVE_NONE); do pos.undo_move(pv[--ply]); while (ply); } @@ -2447,16 +2107,16 @@ split_point_start: // At split points actual search starts from here Value v, m = VALUE_NONE; int ply = 0; - assert(pv[0] != MOVE_NONE && pos.move_is_legal(pv[0])); + assert(pv[0] != MOVE_NONE && pos.move_is_pl(pv[0])); do { k = pos.get_key(); - tte = TT.retrieve(k); + tte = TT.probe(k); // Don't overwrite existing correct entries if (!tte || tte->move() != pv[ply]) { - v = (pos.is_check() ? VALUE_NONE : evaluate(pos, m)); + v = (pos.in_check() ? VALUE_NONE : evaluate(pos, m)); TT.store(k, VALUE_NONE, VALUE_TYPE_NONE, DEPTH_NONE, pv[ply], v, m); } pos.do_move(pv[ply], *st++); @@ -2465,96 +2125,113 @@ split_point_start: // At split points actual search starts from here do pos.undo_move(pv[--ply]); while (ply); } +} // namespace - // pv_info_to_uci() returns a string with information on the current PV line - // formatted according to UCI specification. - std::string RootMove::pv_info_to_uci(Position& pos, int depth, int selDepth, Value alpha, - Value beta, int pvIdx) { - std::stringstream s; +// Little helper used by idle_loop() to check that all the slaves of a +// master thread have finished searching. - 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 "; +static bool all_slaves_finished(SplitPoint* sp) { - for (Move* m = pv; *m != MOVE_NONE; m++) - s << *m << " "; + assert(sp); - return s.str(); - } + for (int i = 0; i < Threads.size(); i++) + if (sp->is_slave[i]) + return false; + return true; +} - void RootMoveList::init(Position& pos, Move searchMoves[]) { - MoveStack mlist[MAX_MOVES]; - Move* sm; +// Thread::idle_loop() is where the thread is parked when it has no work to do. +// The parameter 'sp', if non-NULL, is a pointer to an active SplitPoint object +// for which the thread is the master. - clear(); - bestMoveChanges = 0; +void Thread::idle_loop(SplitPoint* sp) { - // Generate all legal moves and add them to RootMoveList - MoveStack* last = generate(pos, mlist); - for (MoveStack* cur = mlist; cur != last; cur++) - { - // 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++) {} + while (true) + { + // If we are not searching, wait for a condition to be signaled + // instead of wasting CPU time polling for work. + while ( do_sleep + || do_terminate + || (Threads.use_sleeping_threads() && state == Thread::AVAILABLE)) + { + assert((!sp && threadID) || Threads.use_sleeping_threads()); - if (searchMoves[0] && *sm != cur->move) - continue; + // Grab the lock to avoid races with Thread::wake_up() + lock_grab(&sleepLock); - RootMove rm; - rm.pv[0] = cur->move; - rm.pv[1] = MOVE_NONE; - rm.pv_score = -VALUE_INFINITE; - push_back(rm); - } - } + // Slave thread should exit as soon as do_terminate flag raises + if (do_terminate) + { + assert(!sp); + lock_release(&sleepLock); + return; + } + // If we are master and all slaves have finished don't go to sleep + if (sp && all_slaves_finished(sp)) + { + lock_release(&sleepLock); + break; + } - // 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) { + // Do sleep after retesting sleep conditions under lock protection, in + // particular we need to avoid a deadlock in case a master thread has, + // in the meanwhile, allocated us and sent the wake_up() call before we + // had the chance to grab the lock. + if (do_sleep || state == Thread::AVAILABLE) + cond_wait(&sleepCond, &sleepLock); - assert(MultiPV > 1); + lock_release(&sleepLock); + } - // 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; + // If this thread has been assigned work, launch a search + if (state == Thread::WORKISWAITING) + { + assert(!do_terminate); - // PRNG sequence should be non deterministic - for (int i = abs(get_system_time() % 50); i > 0; i--) - RK.rand(); + state = Thread::SEARCHING; - // 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++) - { - s = Rml[i].pv_score; + // Copy split point position and search stack and call search() + SearchStack ss[PLY_MAX_PLUS_2]; + SplitPoint* tsp = splitPoint; + Position pos(*tsp->pos, threadID); - // Don't allow crazy blunders even at very low skills - if (i > 0 && Rml[i-1].pv_score > s + EasyMoveMargin) - break; + memcpy(ss, tsp->ss - 1, 4 * sizeof(SearchStack)); + (ss+1)->sp = tsp; - // This is our magical formula - s += ((max - s) * wk + var * (RK.rand() % wk)) / 128; + if (tsp->nodeType == Root) + search(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth); + else if (tsp->nodeType == PV) + search(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth); + else if (tsp->nodeType == NonPV) + search(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth); + else + assert(false); - if (s > max_s) - { - max_s = s; - *best = Rml[i].pv[0]; - *ponder = Rml[i].pv[1]; - } - } - } + assert(state == Thread::SEARCHING); -} // namespace + state = Thread::AVAILABLE; + + // Wake up master thread so to allow it to return from the idle loop in + // case we are the last slave of the split point. + if ( Threads.use_sleeping_threads() + && threadID != tsp->master + && Threads[tsp->master].state == Thread::AVAILABLE) + Threads[tsp->master].wake_up(); + } + + // If this thread is the master of a split point and all slaves have + // finished their work at this split point, return from the idle loop. + if (sp && all_slaves_finished(sp)) + { + // Because sp->is_slave[] is reset under lock protection, + // be sure sp->lock has been released before to return. + lock_grab(&(sp->lock)); + lock_release(&(sp->lock)); + return; + } + } +}