X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=27a67a639401e3d18e48a3416a1ea4592ce1f072;hp=bd24b0f8837914d4fdcb632869b85e915eb5983a;hb=927f1b0bd30a5b2cfdcdf163f26f528738509064;hpb=df73af30dddfb635dd8e3a56b2f9879dfc436617 diff --git a/src/search.cpp b/src/search.cpp index bd24b0f8..27a67a63 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -17,11 +17,6 @@ along with this program. If not, see . */ - -//// -//// Includes -//// - #include #include #include @@ -34,10 +29,10 @@ #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" @@ -47,27 +42,21 @@ 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; - // Fast lookup table of sliding pieces indexed by Piece + // 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 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. + // 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 @@ -105,7 +94,7 @@ namespace { }; - // RootMove struct is used for moves at the root at the tree. For each root + // 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 @@ -120,8 +109,8 @@ namespace { // 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. + // 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; @@ -129,7 +118,7 @@ namespace { void extract_pv_from_tt(Position& pos); void insert_pv_in_tt(Position& pos); - std::string pv_info_to_uci(const Position& pos, Value alpha, Value beta, int pvLine = 0); + std::string pv_info_to_uci(Position& pos, int depth, Value alpha, Value beta, int pvIdx); int64_t nodes; Value pv_score; @@ -138,32 +127,41 @@ namespace { }; - // RootMoveList struct is essentially a std::vector<> of RootMove objects, + // RootMoveList struct is just a std::vector<> of RootMove objects, // with an handful of methods above the standard ones. struct RootMoveList : public std::vector { typedef std::vector Base; - RootMoveList(Position& pos, Move searchMoves[]); - void set_non_pv_scores(const Position& pos); - + void init(Position& pos, Move searchMoves[]); void sort() { insertion_sort(begin(), end()); } void sort_multipv(int n) { insertion_sort(begin(), begin() + n); } + + 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 use it to properly format castling moves. + // operator<<() that will read it to properly format castling moves. enum set960 {}; - std::ostream& operator<< (std::ostream& os, const set960& m) { + std::ostream& operator<< (std::ostream& os, const set960& f) { - os.iword(0) = int(m); + os.iword(0) = int(f); return os; } @@ -194,22 +192,18 @@ namespace { // 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]; + Depth CheckExtension[2], PawnPushTo7thExtension[2], PassedPawnExtension[2]; + Depth PawnEndgameExtension[2], MateThreatExtension[2]; // Minimum depth for use of singular extension const Depth SingularExtensionDepth[2] = { 8 * ONE_PLY /* non-PV */, 6 * ONE_PLY /* PV */}; - // If the TT move is at least SingularExtensionMargin better then the - // remaining ones we will extend it. - const Value SingularExtensionMargin = Value(0x20); - // Step 12. Futility pruning // Futility margin for quiescence search const Value FutilityMarginQS = Value(0x80); - // Futility lookup tables (initialized at startup) and their getter functions + // Futility lookup tables (initialized at startup) and their access functions Value FutilityMarginsMatrix[16][64]; // [depth][moveNumber] int FutilityMoveCountArray[32]; // [depth] @@ -224,11 +218,6 @@ namespace { template inline Depth reduction(Depth d, int mn) { return (Depth) ReductionMatrix[PV][Min(d / 2, 63)][Min(mn, 63)]; } - // Common adjustments - - // Search depth at iteration 1 - const Depth InitialDepth = ONE_PLY; - // Easy move margin. An easy move candidate must be at least this much // better than the second best move. const Value EasyMoveMargin = Value(0x200); @@ -236,33 +225,31 @@ namespace { /// Namespace variables - // Book object + // 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 + // Time management variables int SearchStartTime, MaxNodes, MaxDepth, ExactMaxTime; - bool UseTimeManagement, InfiniteSearch, PonderSearch, StopOnPonderhit; - bool FirstRootMove, AbortSearch, Quit, AspirationFailLow; + bool UseTimeManagement, InfiniteSearch, Pondering, StopOnPonderhit; + bool FirstRootMove, StopRequest, QuitRequest, AspirationFailLow; TimeManager TimeMgr; // Log file bool UseLogFile; std::ofstream LogFile; - // Multi-threads manager object + // 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 @@ -274,12 +261,12 @@ namespace { // History table History H; + /// Local functions Move id_loop(Position& pos, Move searchMoves[], Move* ponderMove); - Value root_search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, RootMoveList& rml); - template + template Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int ply); template @@ -288,32 +275,29 @@ namespace { template inline Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int ply) { - return depth < ONE_PLY ? qsearch(pos, ss, alpha, beta, DEPTH_ZERO, ply) - : search(pos, ss, alpha, beta, depth, ply); + return depth < ONE_PLY ? qsearch(pos, ss, alpha, beta, DEPTH_ZERO, ply) + : search(pos, ss, alpha, beta, depth, ply); } 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 mateThreat, 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); - bool value_is_mate(Value value); 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(); std::string value_to_uci(Value v); - int nps(const Position& pos); + std::string speed_to_uci(int64_t nodes); void poll(const Position& pos); - void ponderhit(); void wait_for_stop_or_ponderhit(); - void init_ss_array(SearchStack* ss, int size); #if !defined(_MSC_VER) void* init_thread(void* threadID); @@ -321,23 +305,78 @@ namespace { DWORD WINAPI init_thread(LPVOID threadID); #endif -} + // MovePickerExt is an extended MovePicker 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 { -//// -//// Functions -//// + 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; -/// init_threads(), exit_threads() and nodes_searched() are helpers to -/// give accessibility to some TM methods from outside of current file. + // 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; + } -void init_threads() { ThreadsMgr.init_threads(); } -void exit_threads() { ThreadsMgr.exit_threads(); } + 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 { + MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b) + : MovePicker(p, ttm, d, h, ss, b) {} -/// init_search() is called during startup. It initializes various lookup tables + RootMoveList::iterator rm; // Dummy, needed to compile + }; + +} // namespace -void init_search() { + +/// init_threads() is called during startup. It initializes various lookup tables +/// and creates and launches search threads. + +void init_threads() { int d; // depth (ONE_PLY == 2) int hd; // half depth (ONE_PLY == 1) @@ -359,88 +398,86 @@ void init_search() { // 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(); } -/// 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. +/// exit_threads() is a trampoline to access ThreadsMgr from outside of current file +void exit_threads() { ThreadsMgr.exit_threads(); } + -int perft(Position& pos, Depth depth) -{ - MoveStack mlist[MOVES_MAX]; - StateInfo st; - Move m; - int sum = 0; +/// perft() is our utility to verify move generation. All the legal moves up to +/// given depth are generated and counted and the sum returned. - // Generate all legal moves - MoveStack* last = generate_moves(pos, mlist); +int64_t perft(Position& pos, Depth depth) { - // 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); + MoveStack mlist[MOVES_MAX]; + StateInfo st; + Move m; + int64_t sum = 0; - // 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; + // 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 <= ONE_PLY) + return int(last - mlist); + + // 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(Position& pos, bool infinite, bool ponder, int time[], int increment[], int movesToGo, int maxDepth, int maxNodes, int maxTime, Move searchMoves[]) { - // Initialize global search variables - StopOnPonderhit = AbortSearch = Quit = AspirationFailLow = SendSearchedNodes = false; + // Initialize global search-related variables + StopOnPonderhit = StopRequest = QuitRequest = AspirationFailLow = SendSearchedNodes = false; NodesSincePoll = 0; SearchStartTime = get_system_time(); ExactMaxTime = maxTime; MaxDepth = maxDepth; MaxNodes = maxNodes; InfiniteSearch = infinite; - PonderSearch = ponder; + Pondering = ponder; UseTimeManagement = !ExactMaxTime && !MaxDepth && !MaxNodes && !InfiniteSearch; // Look for a book move, only during games, not tests if (UseTimeManagement && Options["OwnBook"].value()) { - if (Options["Book File"].value() != OpeningBook.file_name()) + if (Options["Book File"].value() != OpeningBook.name()) OpeningBook.open(Options["Book File"].value()); Move bookMove = OpeningBook.get_move(pos, Options["Best Book Move"].value()); if (bookMove != MOVE_NONE) { - if (PonderSearch) + if (Pondering) wait_for_stop_or_ponderhit(); cout << "bestmove " << bookMove << endl; - return true; + return !QuitRequest; } } - // Read UCI option values - TT.set_size(Options["Hash"].value()); - if (Options["Clear Hash"].value()) - { - Options["Clear Hash"].set_value("false"); - TT.clear(); - } - + // Read UCI options CheckExtension[1] = Options["Check Extension (PV nodes)"].value(); CheckExtension[0] = Options["Check Extension (non-PV nodes)"].value(); - SingleEvasionExtension[1] = Options["Single Evasion Extension (PV nodes)"].value(); - SingleEvasionExtension[0] = Options["Single Evasion Extension (non-PV nodes)"].value(); PawnPushTo7thExtension[1] = Options["Pawn Push to 7th Extension (PV nodes)"].value(); PawnPushTo7thExtension[0] = Options["Pawn Push to 7th Extension (non-PV nodes)"].value(); PassedPawnExtension[1] = Options["Passed Pawn Extension (PV nodes)"].value(); @@ -449,16 +486,29 @@ bool think(Position& pos, bool infinite, bool ponder, int time[], int increment[ PawnEndgameExtension[0] = Options["Pawn Endgame Extension (non-PV nodes)"].value(); MateThreatExtension[1] = Options["Mate Threat Extension (PV nodes)"].value(); MateThreatExtension[0] = Options["Mate Threat Extension (non-PV nodes)"].value(); - MultiPV = Options["MultiPV"].value(); + UCIMultiPV = Options["MultiPV"].value(); + SkillLevel = Options["Skill level"].value(); UseLogFile = Options["Use Search Log"].value(); read_evaluation_uci_options(pos.side_to_move()); + 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 + // Wake up needed threads. Main thread, with threadID == 0, is always active for (int i = 1; i < ThreadsMgr.active_threads(); i++) ThreadsMgr.wake_sleeping_thread(i); @@ -468,8 +518,7 @@ bool think(Position& pos, bool infinite, bool ponder, int time[], int increment[ if (UseTimeManagement) TimeMgr.init(myTime, myIncrement, movesToGo, pos.startpos_ply_counter()); - // Set best NodesBetweenPolls interval to avoid lagging under - // heavy time pressure. + // Set best NodesBetweenPolls interval to avoid lagging under time pressure if (MaxNodes) NodesBetweenPolls = Min(MaxNodes, 30000); else if (myTime && myTime < 1000) @@ -485,12 +534,13 @@ bool think(Position& pos, bool infinite, bool ponder, int time[], int increment[ std::string name = Options["Search Log Filename"].value(); LogFile.open(name.c_str(), std::ios::out | std::ios::app); - LogFile << "Searching: " << pos.to_fen() - << "\ninfinite: " << infinite - << " ponder: " << ponder - << " time: " << myTime - << " increment: " << myIncrement - << " moves to go: " << movesToGo << endl; + LogFile << "\nSearching: " << pos.to_fen() + << "\ninfinite: " << infinite + << " ponder: " << ponder + << " time: " << myTime + << " increment: " << myIncrement + << " moves to go: " << movesToGo + << endl; } // We're ready to start thinking. Call the iterative deepening loop function @@ -498,22 +548,20 @@ bool think(Position& pos, bool infinite, bool ponder, int time[], int increment[ Move bestMove = id_loop(pos, searchMoves, &ponderMove); // Print final search statistics - cout << "info nodes " << pos.nodes_searched() - << " nps " << nps(pos) - << " time " << current_search_time() << endl; + cout << "info" << speed_to_uci(pos.nodes_searched()) << endl; if (UseLogFile) { - LogFile << "\nNodes: " << pos.nodes_searched() - << "\nNodes/second: " << nps(pos) - << "\nBest move: " << move_to_san(pos, bestMove); + int t = current_search_time(); + + LogFile << "Nodes: " << pos.nodes_searched() + << "\nNodes/second: " << (t > 0 ? int(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) // Works also with MOVE_NONE - << endl; - + LogFile << "\nPonder move: " << move_to_san(pos, ponderMove) << endl; + pos.undo_move(bestMove); // Return from think() with unchanged position LogFile.close(); } @@ -522,392 +570,198 @@ bool think(Position& pos, bool infinite, bool ponder, int time[], int increment[ // 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)) + if (!StopRequest && (Pondering || InfiniteSearch)) wait_for_stop_or_ponderhit(); - // Could be both MOVE_NONE when searching on a stalemate position - cout << "bestmove " << bestMove << " ponder " << ponderMove << endl; + // Could be MOVE_NONE when searching on a stalemate position + cout << "bestmove " << bestMove; + + // UCI protol is not clear on allowing sending an empty ponder move, instead + // it is clear that ponder move is optional. So skip it if empty. + if (ponderMove != MOVE_NONE) + cout << " ponder " << ponderMove; - return !Quit; + cout << endl; + + return !QuitRequest; } namespace { - // 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. + // 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. Move id_loop(Position& pos, Move searchMoves[], Move* ponderMove) { SearchStack ss[PLY_MAX_PLUS_2]; - Depth depth; - Move EasyMove = MOVE_NONE; - Value value, alpha = -VALUE_INFINITE, beta = VALUE_INFINITE; + Value bestValues[PLY_MAX_PLUS_2]; + int bestMoveChanges[PLY_MAX_PLUS_2]; + int depth, aspirationDelta, skillSamplingDepth; + Value value, alpha, beta; + Move bestMove, easyMove, skillBest, skillPonder; + + // Initialize stuff before a new search + memset(ss, 0, 4 * sizeof(SearchStack)); + TT.new_search(); + H.clear(); + *ponderMove = bestMove = easyMove = skillBest = skillPonder = MOVE_NONE; + depth = aspirationDelta = skillSamplingDepth = 0; + alpha = -VALUE_INFINITE, beta = VALUE_INFINITE; + ss->currentMove = MOVE_NULL; // Hack to skip update_gains() - // Moves to search are verified, scored and sorted - RootMoveList rml(pos, searchMoves); + // Moves to search are verified and copied + Rml.init(pos, searchMoves); - // Handle special case of searching on a mate/stale position - if (rml.size() == 0) + // Handle special case of searching on a mate/stalemate position + if (Rml.size() == 0) { - Value s = (pos.is_check() ? -VALUE_MATE : VALUE_DRAW); - - cout << "info depth " << 1 - << " score " << value_to_uci(s) << endl; + cout << "info depth 0 score " + << value_to_uci(pos.is_check() ? -VALUE_MATE : VALUE_DRAW) + << endl; return MOVE_NONE; } - // Initialize - TT.new_search(); - H.clear(); - init_ss_array(ss, PLY_MAX_PLUS_2); - ValueByIteration[1] = rml[0].pv_score; - Iteration = 1; - - // Send initial RootMoveList scoring (iteration 1) - cout << set960(pos.is_chess960()) // Is enough to set once at the beginning - << "info depth " << Iteration - << "\n" << rml[0].pv_info_to_uci(pos, alpha, beta) << endl; - - // Is one move significantly better than others after initial scoring ? - if ( rml.size() == 1 - || rml[0].pv_score > rml[1].pv_score + EasyMoveMargin) - EasyMove = rml[0].pv[0]; + // Choose a random sampling depth according to SkillLevel so that at low + // skills there is an higher risk to pick up a blunder. + if (SkillLevelEnabled) + skillSamplingDepth = 4 + SkillLevel + (RK.rand() % 4); // Iterative deepening loop - while (Iteration < PLY_MAX) + while (++depth <= PLY_MAX && (!MaxDepth || depth <= MaxDepth) && !StopRequest) { - // Initialize iteration - Iteration++; - BestMoveChangesByIteration[Iteration] = 0; - - cout << "info depth " << Iteration << endl; + 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); } - depth = (Iteration - 2) * ONE_PLY + InitialDepth; + // 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, 0); + + // 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; + + assert(value >= alpha); - // Search to the current depth, rml is updated and sorted - value = root_search(pos, ss, alpha, beta, depth, rml); + // 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); - if (AbortSearch) - break; // Value cannot be trusted. Break out immediately! + // Collect info about search result + bestMove = Rml[0].pv[0]; + *ponderMove = Rml[0].pv[1]; + bestValues[depth] = value; + bestMoveChanges[depth] = Rml.bestMoveChanges; - //Save info about search result - ValueByIteration[Iteration] = value; + // Do we need to pick now the best and the ponder moves ? + if (SkillLevelEnabled && depth == skillSamplingDepth) + do_skill_level(&skillBest, &skillPonder); - // Drop the easy move if differs from the new best move - if (rml[0].pv[0] != EasyMove) - EasyMove = MOVE_NONE; + // 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, alpha, beta, i) << endl; - if (UseTimeManagement) + if (UseLogFile) + LogFile << pretty_pv(pos, depth, value, current_search_time(), Rml[0].pv) << 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)) + easyMove = bestMove; + else if (bestMove != easyMove) + easyMove = MOVE_NONE; + + if (UseTimeManagement && !StopRequest) { // Time to stop? - bool stopSearch = false; - - // 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.size() == 1) - stopSearch = true; + bool noMoreTime = false; // 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 - if ( Iteration >= 8 - && EasyMove == rml[0].pv[0] - && ( ( rml[0].nodes > (pos.nodes_searched() * 85) / 100 + if ( depth >= 5 + && abs(bestValues[depth]) >= abs(VALUE_MATE) - 100 + && abs(bestValues[depth - 1]) >= abs(VALUE_MATE) - 100) + noMoreTime = true; + + // Stop search early if one move seems to be much better than the + // others or if there is only a single legal move. In this latter + // case we search up to Iteration 8 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 + ||( Rml[0].nodes > (pos.nodes_searched() * 98) / 100 && current_search_time() > TimeMgr.available_time() / 32))) - stopSearch = true; + noMoreTime = true; // Add some extra time if the best move has changed during the last two iterations - if (Iteration > 5 && Iteration <= 50) - TimeMgr.pv_instability(BestMoveChangesByIteration[Iteration], - BestMoveChangesByIteration[Iteration-1]); + if (depth > 4 && depth < 50) + TimeMgr.pv_instability(bestMoveChanges[depth], bestMoveChanges[depth-1]); // 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() > (TimeMgr.available_time() * 80) / 128) - stopSearch = true; + noMoreTime = true; - if (stopSearch) + if (noMoreTime) { - if (PonderSearch) + if (Pondering) StopOnPonderhit = true; else break; } } - - if (MaxDepth && Iteration >= MaxDepth) - break; } - *ponderMove = rml[0].pv[1]; - return rml[0].pv[0]; - } - - - // root_search() is the function which searches the root node. It is - // similar to search_pv except that it prints some information to the - // standard output and handles the fail low/high loops. - - Value root_search(Position& pos, SearchStack* ss, Value alpha, - Value beta, Depth depth, RootMoveList& rml) { - StateInfo st; - CheckInfo ci(pos); - int64_t nodes; - Move move; - Depth ext, newDepth; - Value value, oldAlpha; - bool isCheck, moveIsCheck, captureOrPromotion, dangerous; - int researchCountFH, researchCountFL; - - researchCountFH = researchCountFL = 0; - oldAlpha = alpha; - isCheck = pos.is_check(); - - // Step 1. Initialize node (polling is omitted at root) - ss->currentMove = ss->bestMove = MOVE_NONE; - - // 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 - ss->evalMargin = VALUE_NONE; - ss->eval = isCheck ? VALUE_NONE : evaluate(pos, ss->evalMargin); - - // 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) + // When using skills fake best and ponder moves with the sub-optimal ones + if (SkillLevelEnabled) { - // Sort the moves before to (re)search - rml.set_non_pv_scores(pos); - rml.sort(); - - // Step 10. Loop through all moves in the root move list - for (int i = 0; i < (int)rml.size() && !AbortSearch; i++) - { - // This is used by time management - FirstRootMove = (i == 0); - - // 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 nodes " << nodes - << " nps " << nps(pos) - << " time " << current_search_time() << endl; - } - - // Pick the next root move, and print the move and the move number to - // the standard output. - move = ss->currentMove = rml[i].pv[0]; - - 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 - 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 * ONE_PLY - && !dangerous - && !captureOrPromotion - && !move_is_castle(move)) - { - ss->reduction = reduction(depth, i - MultiPV + 2); - if (ss->reduction) - { - assert(newDepth-ss->reduction >= ONE_PLY); - - // Reduced depth non-pv search using alpha as upperbound - value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, 1); - doFullDepthSearch = (value > alpha); - } - ss->reduction = DEPTH_ZERO; // 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. - ss->bestMove = move; - rml[i].pv_score = value; - rml[i].extract_pv_from_tt(pos); - - // Inform GUI that PV has changed - cout << rml[i].pv_info_to_uci(pos, alpha, beta) << endl; - - // Prepare for a research after a fail high, each time with a wider window - 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 searched nodes counts for this move - rml[i].nodes += pos.nodes_searched() - nodes; - - assert(value >= -VALUE_INFINITE && value <= VALUE_INFINITE); - assert(value < beta); + if (skillBest == MOVE_NONE) // Still unassigned ? + do_skill_level(&skillBest, &skillPonder); - // Step 17. Check for new best move - if (value <= alpha && i >= MultiPV) - rml[i].pv_score = -VALUE_INFINITE; - else - { - // PV move or new best move! - - // Update PV - ss->bestMove = move; - rml[i].pv_score = value; - rml[i].extract_pv_from_tt(pos); - - // 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 (MultiPV == 1 && i > 0) - BestMoveChangesByIteration[Iteration]++; - - // Inform GUI that PV has changed, in case of multi-pv UCI protocol - // requires we send all the PV lines properly sorted. - rml.sort_multipv(i); - - for (int j = 0; j < Min(MultiPV, (int)rml.size()); j++) - cout << rml[j].pv_info_to_uci(pos, alpha, beta, j) << endl; - - // Update alpha. In multi-pv we don't use aspiration window - if (MultiPV == 1) - { - // Raise alpha to setup proper non-pv search upper bound - if (value > alpha) - alpha = value; - } - else // Set alpha equal to minimum score among the PV lines - alpha = rml[Min(i, MultiPV - 1)].pv_score; - - } // PV move or new best move - - assert(alpha >= oldAlpha); - - AspirationFailLow = (alpha == oldAlpha); - - if (AspirationFailLow && StopOnPonderhit) - StopOnPonderhit = false; - - } // Root moves loop - - // Can we exit fail low loop ? - if (AbortSearch || !AspirationFailLow) - break; - - // Prepare for a research after a fail low, each time with a wider window - oldAlpha = alpha = Max(alpha - AspirationDelta * (1 << researchCountFL), -VALUE_INFINITE); - researchCountFL++; - - } // Fail low loop - - // Sort the moves before to return - rml.sort(); - - // Write PV lines to transposition table, in case the relevant entries - // have been overwritten during the search. - for (int i = 0; i < MultiPV; i++) - rml[i].insert_pv_in_tt(pos); + bestMove = skillBest; + *ponderMove = skillPonder; + } - return alpha; + return bestMove; } @@ -918,16 +772,17 @@ 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, int ply) { 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((Root || ply > 0) && ply < PLY_MAX); assert(pos.thread() >= 0 && pos.thread() < ThreadsMgr.active_threads()); Move movesSearched[MOVES_MAX]; + int64_t nodes; StateInfo st; const TTEntry *tte; Key posKey; @@ -936,11 +791,12 @@ namespace { ValueType vt; Value bestValue, value, oldAlpha; Value refinedValue, nullValue, futilityBase, futilityValueScaled; // Non-PV specific - bool isCheck, singleEvasion, singularExtensionNode, moveIsCheck, captureOrPromotion, dangerous; + bool isPvMove, isCheck, singularExtensionNode, moveIsCheck, captureOrPromotion, dangerous, isBadCap; bool mateThreat = false; - int moveCount = 0; + int moveCount = 0, playedMoveCount = 0; int threadID = pos.thread(); SplitPoint* sp = NULL; + refinedValue = bestValue = value = -VALUE_INFINITE; oldAlpha = alpha; isCheck = pos.is_check(); @@ -954,10 +810,12 @@ namespace { mateThreat = sp->mateThreat; goto split_point_start; } - else {} // Hack to fix icc's "statement is unreachable" warning + else if (Root) + bestValue = alpha; // Step 1. Initialize node and poll. Polling can abort search - ss->currentMove = ss->bestMove = threatMove = MOVE_NONE; + 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) @@ -967,10 +825,10 @@ namespace { } // Step 2. Check for aborted search and immediate draw - if ( AbortSearch - || ThreadsMgr.cutoff_at_splitpoint(threadID) - || pos.is_draw() - || ply >= PLY_MAX - 1) + if (( StopRequest + || ThreadsMgr.cutoff_at_splitpoint(threadID) + || pos.is_draw() + || ply >= PLY_MAX - 1) && !Root) return VALUE_DRAW; // Step 3. Mate distance pruning @@ -980,31 +838,28 @@ namespace { 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)) + // 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, ply))) { TT.refresh(tte); ss->bestMove = ttMove; // Can be MOVE_NONE return value_from_tt(tte->value(), ply); } - // Step 5. Evaluate the position statically and - // update gain statistics of parent move. + // Step 5. Evaluate the position statically and update parent's gain statistics if (isCheck) ss->eval = ss->evalMargin = VALUE_NONE; else if (tte) @@ -1028,9 +883,9 @@ namespace { if ( !PvNode && depth < RazorDepth && !isCheck - && refinedValue < beta - razor_margin(depth) + && refinedValue + razor_margin(depth) < beta && ttMove == MOVE_NONE - && !value_is_mate(beta) + && abs(beta) < VALUE_MATE_IN_PLY_MAX && !pos.has_pawn_on_7th(pos.side_to_move())) { Value rbeta = beta - razor_margin(depth); @@ -1048,8 +903,8 @@ namespace { && !ss->skipNullMove && depth < RazorDepth && !isCheck - && refinedValue >= beta + futility_margin(depth, 0) - && !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); @@ -1059,7 +914,7 @@ namespace { && depth > ONE_PLY && !isCheck && refinedValue >= beta - && !value_is_mate(beta) + && abs(beta) < VALUE_MATE_IN_PLY_MAX && pos.non_pawn_material(pos.side_to_move())) { ss->currentMove = MOVE_NULL; @@ -1068,7 +923,7 @@ namespace { 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); @@ -1080,7 +935,7 @@ namespace { 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; if (depth < 6 * ONE_PLY) @@ -1106,6 +961,7 @@ namespace { mateThreat = true; threatMove = (ss+1)->bestMove; + if ( depth < ThreatDepth && (ss-1)->reduction && threatMove != MOVE_NONE @@ -1115,9 +971,9 @@ namespace { } // 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 * ONE_PLY : depth / 2); @@ -1129,21 +985,19 @@ namespace { tte = TT.retrieve(posKey); } - // Expensive mate threat detection (only for PV nodes) + // Mate threat detection for PV nodes, otherwise we use null move search if (PvNode) mateThreat = pos.has_mate_threat(); split_point_start: // At split points actual search starts from here // Initialize a MovePicker object for the current position - // FIXME currently MovePicker() c'tor is needless called also in SplitPoint - MovePicker mpBase(pos, ttMove, depth, H, ss, (PvNode ? -VALUE_INFINITE : beta)); - MovePicker& mp = SpNode ? *sp->mp : mpBase; + MovePickerExt mp(pos, ttMove, depth, H, ss, (PvNode ? -VALUE_INFINITE : beta)); CheckInfo ci(pos); ss->bestMove = MOVE_NONE; - singleEvasion = !SpNode && isCheck && mp.number_of_evasions() == 1; futilityBase = ss->eval + ss->evalMargin; - singularExtensionNode = !SpNode + singularExtensionNode = !Root + && !SpNode && depth >= SingularExtensionDepth[PvNode] && tte && tte->move() @@ -1172,18 +1026,42 @@ split_point_start: // At split points actual search starts from here else if (move == excludedMove) continue; else - movesSearched[moveCount++] = move; + moveCount++; + + 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, mateThreat, &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 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 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 < ONE_PLY) @@ -1192,14 +1070,14 @@ split_point_start: // At split points actual search starts from here 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, ply); ss->skipNullMove = false; ss->excludedMove = MOVE_NONE; ss->bestMove = MOVE_NONE; - if (v < b) + if (v < rBeta) ext = ONE_PLY; } } @@ -1218,8 +1096,8 @@ split_point_start: // At split points actual search starts from here { // Move count based pruning if ( moveCount >= futility_move_count(depth) - && !(threatMove && connected_threat(pos, move, threatMove)) - && bestValue > value_mated_in(PLY_MAX)) // FIXME bestValue is racy + && (!threatMove || !connected_threat(pos, move, threatMove)) + && bestValue > VALUE_MATED_IN_PLY_MAX) // FIXME bestValue is racy { if (SpNode) lock_grab(&(sp->lock)); @@ -1250,7 +1128,7 @@ split_point_start: // At split points actual search starts from here // Prune moves with negative SEE at low depths if ( predictedDepth < 2 * ONE_PLY - && bestValue > value_mated_in(PLY_MAX) + && bestValue > VALUE_MATED_IN_PLY_MAX && pos.see_sign(move) < 0) { if (SpNode) @@ -1260,18 +1138,38 @@ 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); + 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) + 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, ply+1); + } 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 * ONE_PLY && !captureOrPromotion @@ -1281,7 +1179,6 @@ split_point_start: // At split points actual search starts from here && ss->killers[1] != move) { ss->reduction = reduction(depth, moveCount); - if (ss->reduction) { alpha = SpNode ? sp->alpha : alpha; @@ -1293,6 +1190,18 @@ split_point_start: // At split points actual search starts from here ss->reduction = DEPTH_ZERO; // 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, ply+1); + doFullDepthSearch = (value > rAlpha); + ss->reduction = DEPTH_ZERO; // Restore original reduction + } + // Step 15. Full depth search if (doFullDepthSearch) { @@ -1302,7 +1211,7 @@ split_point_start: // At split points actual search starts from here // 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) + if (PvNode && value > alpha && (Root || value < beta)) value = -search(pos, ss+1, -beta, -alpha, newDepth, ply+1); } } @@ -1327,7 +1236,7 @@ split_point_start: // At split points actual search starts from here if (SpNode) sp->bestValue = value; - if (value > alpha) + if (!Root && value > alpha) { if (PvNode && value < beta) // We want always alpha < beta { @@ -1345,19 +1254,60 @@ split_point_start: // At split points actual search starts from here ss->bestMove = move; if (SpNode) - sp->parentSstack->bestMove = move; + 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 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 ( !SpNode + if ( !Root + && !SpNode && depth >= ThreadsMgr.min_split_depth() && ThreadsMgr.active_threads() > 1 && bestValue < beta && ThreadsMgr.available_thread_exists(threadID) - && !AbortSearch - && !ThreadsMgr.cutoff_at_splitpoint(threadID) - && Iteration <= 99) + && !StopRequest + && !ThreadsMgr.cutoff_at_splitpoint(threadID)) ThreadsMgr.split(pos, ss, ply, &alpha, beta, &bestValue, depth, threatMove, mateThreat, moveCount, &mp, PvNode); } @@ -1372,7 +1322,7 @@ split_point_start: // At split points actual search starts from here // Step 20. Update tables // If the search is not aborted, update the transposition table, // history counters, and killer moves. - if (!SpNode && !AbortSearch && !ThreadsMgr.cutoff_at_splitpoint(threadID)) + if (!SpNode && !StopRequest && !ThreadsMgr.cutoff_at_splitpoint(threadID)) { move = bestValue <= oldAlpha ? MOVE_NONE : ss->bestMove; vt = bestValue <= oldAlpha ? VALUE_TYPE_UPPER @@ -1384,8 +1334,12 @@ split_point_start: // At split points actual search starts from here 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); } } @@ -1519,11 +1473,17 @@ split_point_start: // At split points actual search starts from here bestValue = futilityValue; continue; } + + // Prune moves with negative or equal SEE + if ( futilityBase < beta + && depth < DEPTH_ZERO + && pos.see(move) <= 0) + continue; } // 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.can_castle(pos.side_to_move()); @@ -1697,28 +1657,16 @@ split_point_start: // At split points actual search starts from here } - // value_is_mate() checks if the given value is a mate one eventually - // compensated for the ply. - - bool value_is_mate(Value value) { - - assert(abs(value) <= VALUE_INFINITE); - - return value <= value_mated_in(PLY_MAX) - || value >= value_mate_in(PLY_MAX); - } - - // 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. Value value_to_tt(Value v, int ply) { - if (v >= value_mate_in(PLY_MAX)) + if (v >= VALUE_MATE_IN_PLY_MAX) return v + ply; - if (v <= value_mated_in(PLY_MAX)) + if (v <= VALUE_MATED_IN_PLY_MAX) return v - ply; return v; @@ -1730,10 +1678,10 @@ split_point_start: // At split points actual search starts from here Value value_from_tt(Value v, int ply) { - if (v >= value_mate_in(PLY_MAX)) + if (v >= VALUE_MATE_IN_PLY_MAX) return v - ply; - if (v <= value_mated_in(PLY_MAX)) + if (v <= VALUE_MATED_IN_PLY_MAX) return v + ply; return v; @@ -1747,22 +1695,19 @@ split_point_start: // At split points actual search starts from here // 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 mateThreat, bool* dangerous) { assert(m != MOVE_NONE); Depth result = DEPTH_ZERO; - *dangerous = moveIsCheck | singleEvasion | mateThreat; + *dangerous = moveIsCheck | mateThreat; if (*dangerous) { if (moveIsCheck && pos.see_sign(m) >= 0) result += CheckExtension[PvNode]; - if (singleEvasion) - result += SingleEvasionExtension[PvNode]; - if (mateThreat) result += MateThreatExtension[PvNode]; } @@ -1793,21 +1738,12 @@ split_point_start: // At split points actual search starts from here *dangerous = true; } - if ( PvNode - && captureOrPromotion - && pos.type_of_piece_on(move_to(m)) != PAWN - && pos.see_sign(m) >= 0) - { - result += ONE_PLY / 2; - *dangerous = true; - } - 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) { @@ -1829,7 +1765,7 @@ split_point_start: // At split points actual search starts from here 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) @@ -1855,8 +1791,8 @@ split_point_start: // At split points actual search starts from here 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)) && ( ((tte->type() & VALUE_TYPE_LOWER) && v >= beta) || ((tte->type() & VALUE_TYPE_UPPER) && v < beta)); @@ -1886,8 +1822,9 @@ split_point_start: // At split points actual search starts from here 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++) { @@ -1895,25 +1832,11 @@ split_point_start: // At split points actual search starts from here 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; - - ss->killers[1] = ss->killers[0]; - 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. @@ -1924,7 +1847,7 @@ split_point_start: // At split points actual search starts from here && after != VALUE_NONE && pos.captured_piece_type() == PIECE_TYPE_NONE && !move_is_special(m)) - H.set_gain(pos.piece_on(move_to(m)), move_to(m), -(before + after)); + H.update_gain(pos.piece_on(move_to(m)), move_to(m), -(before + after)); } @@ -1951,17 +1874,25 @@ split_point_start: // At split points actual search starts from here 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) / 2 : -(VALUE_MATE + v) / 2 ); + s << "mate " << (v > 0 ? VALUE_MATE - v + 1 : -VALUE_MATE - v) / 2; return s.str(); } - // nps() computes the current nodes/second count. - int nps(const Position& pos) { + // 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((pos.nodes_searched() * 1000) / t) : 0); + + s << " nodes " << nodes + << " nps " << (t > 0 ? int(nodes * 1000 / t) : 0) + << " time " << t; + + return s.str(); } @@ -1975,28 +1906,35 @@ split_point_start: // At split points actual search starts from here int t = current_search_time(); // Poll for input - if (data_available()) + 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 + Pondering = 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. + Pondering = 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. + Pondering = false; + + if (StopOnPonderhit) + StopRequest = true; + } } // Print search information @@ -2023,7 +1961,7 @@ split_point_start: // At split points actual search starts from here } // Should we stop the search? - if (PonderSearch) + if (Pondering) return; bool stillAtFirstMove = FirstRootMove @@ -2033,49 +1971,10 @@ split_point_start: // At split points actual search starts from here bool noMoreTime = t > TimeMgr.maximum_time() || stillAtFirstMove; - if ( (Iteration >= 3 && UseTimeManagement && noMoreTime) + if ( (UseTimeManagement && noMoreTime) || (ExactMaxTime && t >= ExactMaxTime) - || (Iteration >= 3 && MaxNodes && pos.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 > TimeMgr.available_time(); - - bool noMoreTime = t > TimeMgr.maximum_time() - || 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; - ss->reduction = DEPTH_ZERO; - ss->sp = NULL; - - if (i < 3) - ss->killers[0] = ss->killers[1] = ss->mateKiller = MOVE_NONE; - } + || (MaxNodes && pos.nodes_searched() >= MaxNodes)) // FIXME + StopRequest = true; } @@ -2084,25 +1983,18 @@ split_point_start: // At split points actual search starts from here // 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 } @@ -2206,16 +2098,19 @@ split_point_start: // At split points actual search starts from here threads[threadID].state = THREAD_SEARCHING; - // Here we call search() with SplitPoint template parameter set to true + // Copy SplitPoint 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); - SearchStack* ss = tsp->sstack[threadID] + 1; - ss->sp = tsp; + + memcpy(ss, tsp->ss - 1, 4 * sizeof(SearchStack)); + (ss+1)->sp = tsp; if (tsp->pvNode) - search(pos, ss, tsp->alpha, tsp->beta, tsp->depth, tsp->ply); + search(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth, tsp->ply); else - search(pos, ss, tsp->alpha, tsp->beta, tsp->depth, tsp->ply); + search(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth, tsp->ply); assert(threads[threadID].state == THREAD_SEARCHING); @@ -2460,7 +2355,7 @@ split_point_start: // At split points actual search starts from here splitPoint.moveCount = moveCount; splitPoint.pos = &pos; splitPoint.nodes = 0; - splitPoint.parentSstack = ss; + splitPoint.ss = ss; for (i = 0; i < activeThreads; i++) splitPoint.slaves[i] = 0; @@ -2487,12 +2382,10 @@ split_point_start: // At split points actual search starts from here 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. + // their idle loop. for (i = 0; i < activeThreads; i++) if (i == master || splitPoint.slaves[i]) { - memcpy(splitPoint.sstack[i], ss - 1, 4 * sizeof(SearchStack)); - assert(i == master || threads[i].state == THREAD_BOOKED); threads[i].state = THREAD_WORKISWAITING; // This makes the slave to exit from idle_loop() @@ -2603,7 +2496,7 @@ split_point_start: // At split points actual search starts from here k = pos.get_key(); tte = TT.retrieve(k); - // Don't overwrite exsisting correct entries + // Don't overwrite existing correct entries if (!tte || tte->move() != pv[ply]) { v = (pos.is_check() ? VALUE_NONE : evaluate(pos, m)); @@ -2617,53 +2510,38 @@ split_point_start: // At split points actual search starts from here } // pv_info_to_uci() returns a string with information on the current PV line - // formatted according to UCI specification and eventually writes the info - // to a log file. It is called at each iteration or after a new pv is found. - - std::string RootMove::pv_info_to_uci(const Position& pos, Value alpha, Value beta, int pvLine) { + // formatted according to UCI specification. + std::string RootMove::pv_info_to_uci(Position& pos, int depth, Value alpha, + Value beta, int pvIdx) { std::stringstream s, l; Move* m = pv; while (*m != MOVE_NONE) l << *m++ << " "; - s << "info depth " << Iteration // FIXME + s << "info depth " << depth << " seldepth " << int(m - pv) - << " multipv " << pvLine + 1 + << " multipv " << pvIdx + 1 << " score " << value_to_uci(pv_score) << (pv_score >= beta ? " lowerbound" : pv_score <= alpha ? " upperbound" : "") - << " time " << current_search_time() - << " nodes " << pos.nodes_searched() - << " nps " << nps(pos) + << speed_to_uci(pos.nodes_searched()) << " pv " << l.str(); - if (UseLogFile && pvLine == 0) - { - ValueType t = pv_score >= beta ? VALUE_TYPE_LOWER : - pv_score <= alpha ? VALUE_TYPE_UPPER : VALUE_TYPE_EXACT; - - LogFile << pretty_pv(pos, current_search_time(), Iteration, pv_score, t, pv) << endl; - } return s.str(); } - RootMoveList::RootMoveList(Position& pos, Move searchMoves[]) { + void RootMoveList::init(Position& pos, Move searchMoves[]) { - SearchStack ss[PLY_MAX_PLUS_2]; MoveStack mlist[MOVES_MAX]; - StateInfo st; Move* sm; - // Initialize search stack - init_ss_array(ss, PLY_MAX_PLUS_2); - ss[0].eval = ss[0].evalMargin = VALUE_NONE; - - // Generate all legal moves - MoveStack* last = generate_moves(pos, mlist); + clear(); + bestMoveChanges = 0; - // Add each move to the RootMoveList's vector + // 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 @@ -2673,38 +2551,54 @@ split_point_start: // At split points actual search starts from here if (searchMoves[0] && *sm != cur->move) continue; - // Find a quick score for the move and add to the list - pos.do_move(cur->move, st); - RootMove rm; - rm.pv[0] = ss[0].currentMove = cur->move; + rm.pv[0] = cur->move; rm.pv[1] = MOVE_NONE; - rm.pv_score = -qsearch(pos, ss+1, -VALUE_INFINITE, VALUE_INFINITE, DEPTH_ZERO, 1); + rm.pv_score = -VALUE_INFINITE; push_back(rm); - - pos.undo_move(cur->move); } - sort(); } - // Score root moves using the standard way used in main search, the moves - // are scored according to the order in which are returned by MovePicker. - // This is the second order score that is used to compare the moves when - // the first order pv scores of both moves are equal. - void RootMoveList::set_non_pv_scores(const Position& pos) - { - Move move; - Value score = VALUE_ZERO; - MovePicker mp(pos, MOVE_NONE, ONE_PLY, H); + // 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) { - while ((move = mp.get_next_move()) != MOVE_NONE) - for (Base::iterator it = begin(); it != end(); ++it) - if (it->pv[0] == move) - { - it->non_pv_score = score--; - break; - } + assert(MultiPV > 1); + + // 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; + + // PRNG sequence should be non deterministic + for (int i = abs(get_system_time() % 50); i > 0; i--) + RK.rand(); + + // Choose best move. For each move's score we add two terms both dependent + // on wk, one deterministic and bigger for weaker moves, and one random, + // then we choose the move with the resulting highest score. + for (int i = 0; i < size; i++) + { + s = Rml[i].pv_score; + + // Don't allow crazy blunders even at very low skills + if (i > 0 && Rml[i-1].pv_score > s + EasyMoveMargin) + break; + + // This is our magical formula + s += ((max - s) * wk + var * (RK.rand() % wk)) / 128; + + if (s > max_s) + { + max_s = s; + *best = Rml[i].pv[0]; + *ponder = Rml[i].pv[1]; + } + } } } // namespace