X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=36ed82f2771a9c595c70c8835b2f7e9611fada31;hp=45c040f7fba80676459123d71012eee0032b6f17;hb=427dc2a82c82c69e964a3f7a2030f9417d0beee9;hpb=cc2a249952a93b134e67834b47000e455135e28f diff --git a/src/search.cpp b/src/search.cpp index 45c040f7..9fc1bd42 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -1,7 +1,7 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008-2009 Marco Costalba + Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -38,6 +38,7 @@ #include "lock.h" #include "san.h" #include "search.h" +#include "timeman.h" #include "thread.h" #include "tt.h" #include "ucioption.h" @@ -52,7 +53,11 @@ using std::endl; namespace { /// Types + enum NodeType { NonPV, PV }; + // Set to true to force running with one thread. + // Used for debugging SMP code. + const bool FakeSplit = false; // ThreadsManager class is used to handle all the threads related stuff in search, // init, starting, parking and, the most important, launching a slave thread at a @@ -71,28 +76,26 @@ namespace { int active_threads() const { return ActiveThreads; } void set_active_threads(int newActiveThreads) { ActiveThreads = newActiveThreads; } void incrementNodeCounter(int threadID) { threads[threadID].nodes++; } - void incrementBetaCounter(Color us, Depth d, int threadID) { threads[threadID].betaCutOffs[us] += unsigned(d); } void resetNodeCounters(); - void resetBetaCounters(); int64_t nodes_searched() const; - void get_beta_counters(Color us, int64_t& our, int64_t& their) const; bool available_thread_exists(int master) const; bool thread_is_available(int slave, int master) const; bool thread_should_stop(int threadID) const; void wake_sleeping_threads(); void put_threads_to_sleep(); - void idle_loop(int threadID, SplitPoint* waitSp); - bool split(const Position& pos, SearchStack* ss, int ply, Value* alpha, const Value beta, Value* bestValue, - Depth depth, bool mateThreat, int* moves, MovePicker* mp, int master, bool pvNode); + void idle_loop(int threadID, SplitPoint* sp); + + template + void split(const Position& pos, SearchStack* ss, int ply, Value* alpha, const Value beta, Value* bestValue, + Depth depth, Move threatMove, bool mateThreat, int* moveCount, MovePicker* mp, bool pvNode); private: - friend void poll(SearchStack ss[], int ply); + friend void poll(); int ActiveThreads; volatile bool AllThreadsShouldExit, AllThreadsShouldSleep; Thread threads[MAX_THREADS]; - SplitPoint SplitPointStack[MAX_THREADS][ACTIVE_SPLIT_POINTS_MAX]; Lock MPLock, WaitLock; @@ -111,20 +114,21 @@ namespace { struct RootMove { - RootMove() { nodes = cumulativeNodes = ourBeta = theirBeta = 0ULL; } + RootMove() : mp_score(0), nodes(0) {} // RootMove::operator<() is the comparison function used when // sorting the moves. A move m1 is considered to be better // than a move m2 if it has a higher score, or if the moves - // have equal score but m1 has the higher node count. + // have equal score but m1 has the higher beta cut-off count. bool operator<(const RootMove& m) const { - return score != m.score ? score < m.score : theirBeta <= m.theirBeta; + return score != m.score ? score < m.score : mp_score <= m.mp_score; } Move move; Value score; - int64_t nodes, cumulativeNodes, ourBeta, theirBeta; + int mp_score; + int64_t nodes; Move pv[PLY_MAX_PLUS_2]; }; @@ -142,10 +146,10 @@ namespace { Value get_move_score(int moveNum) const { return moves[moveNum].score; } void set_move_score(int moveNum, Value score) { moves[moveNum].score = score; } Move get_move_pv(int moveNum, int i) const { return moves[moveNum].pv[i]; } - int64_t get_move_cumulative_nodes(int moveNum) const { return moves[moveNum].cumulativeNodes; } + int64_t get_move_nodes(int moveNum) const { return moves[moveNum].nodes; } + void score_moves(const Position& pos); - void set_move_nodes(int moveNum, int64_t nodes); - void set_beta_counters(int moveNum, int64_t our, int64_t their); + void add_move_nodes(int moveNum, int64_t nodes) { moves[moveNum].nodes += nodes; } void set_move_pv(int moveNum, const Move pv[]); void sort(); void sort_multipv(int n); @@ -157,12 +161,27 @@ namespace { }; + // 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. + enum set960 {}; + + std::ostream& operator<< (std::ostream& os, const set960& m) { + + os.iword(0) = int(m); + return os; + } + + /// Adjustments // Step 6. Razoring // Maximum depth for razoring - const Depth RazorDepth = 4 * OnePly; + const Depth RazorDepth = 4 * ONE_PLY; // Dynamic razoring margin based on depth inline Value razor_margin(Depth d) { return Value(0x200 + 0x10 * int(d)); } @@ -174,16 +193,15 @@ namespace { const Value NullMoveMargin = Value(0x200); // Maximum depth for use of dynamic threat detection when null move fails low - const Depth ThreatDepth = 5 * OnePly; + const Depth ThreatDepth = 5 * ONE_PLY; // Step 9. Internal iterative deepening // Minimum depth for use of internal iterative deepening - const Depth IIDDepthAtPVNodes = 5 * OnePly; - const Depth IIDDepthAtNonPVNodes = 8 * OnePly; + const Depth IIDDepth[2] = { 8 * ONE_PLY /* non-PV */, 5 * ONE_PLY /* PV */}; // At Non-PV nodes we do an internal iterative deepening search - // when the static evaluation is at most IIDMargin below beta. + // when the static evaluation is bigger then beta - IIDMargin. const Value IIDMargin = Value(0x100); // Step 11. Decide the new search depth @@ -194,8 +212,7 @@ namespace { Depth PassedPawnExtension[2], PawnEndgameExtension[2], MateThreatExtension[2]; // Minimum depth for use of singular extension - const Depth SingularExtensionDepthAtPVNodes = 6 * OnePly; - const Depth SingularExtensionDepthAtNonPVNodes = 8 * OnePly; + 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. @@ -210,33 +227,26 @@ namespace { int32_t FutilityMarginsMatrix[16][64]; // [depth][moveNumber] int FutilityMoveCountArray[32]; // [depth] - inline Value futility_margin(Depth d, int mn) { return Value(d < 7 * OnePly ? FutilityMarginsMatrix[Max(d, 0)][Min(mn, 63)] : 2 * VALUE_INFINITE); } - inline int futility_move_count(Depth d) { return d < 16 * OnePly ? FutilityMoveCountArray[d] : 512; } + inline Value futility_margin(Depth d, int mn) { return Value(d < 7 * ONE_PLY ? FutilityMarginsMatrix[Max(d, 1)][Min(mn, 63)] : 2 * VALUE_INFINITE); } + inline int futility_move_count(Depth d) { return d < 16 * ONE_PLY ? FutilityMoveCountArray[d] : 512; } // Step 14. Reduced search // Reduction lookup tables (initialized at startup) and their getter functions - int8_t PVReductionMatrix[64][64]; // [depth][moveNumber] - int8_t NonPVReductionMatrix[64][64]; // [depth][moveNumber] + int8_t ReductionMatrix[2][64][64]; // [pv][depth][moveNumber] - inline Depth pv_reduction(Depth d, int mn) { return (Depth) PVReductionMatrix[Min(d / 2, 63)][Min(mn, 63)]; } - inline Depth nonpv_reduction(Depth d, int mn) { return (Depth) NonPVReductionMatrix[Min(d / 2, 63)][Min(mn, 63)]; } + 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 = OnePly; + 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); - // Last seconds noise filtering (LSN) - const bool UseLSNFiltering = true; - const int LSNTime = 4000; // In milliseconds - const Value LSNValue = value_from_centipawns(200); - bool loseOnTime = false; - /// Global variables @@ -254,13 +264,10 @@ namespace { int MultiPV; // Time managment variables - int SearchStartTime, MaxNodes, MaxDepth, MaxSearchTime; - int AbsoluteMaxSearchTime, ExtraSearchTime, ExactMaxTime; + int SearchStartTime, MaxNodes, MaxDepth, ExactMaxTime; bool UseTimeManagement, InfiniteSearch, PonderSearch, StopOnPonderhit; bool FirstRootMove, AbortSearch, Quit, AspirationFailLow; - - // Show current line? - bool ShowCurrentLine; + TimeManager TimeMgr; // Log file bool UseLogFile; @@ -269,7 +276,7 @@ namespace { // Multi-threads related variables Depth MinimumSplitDepth; int MaxThreadsPerSplitPoint; - ThreadsManager TM; + 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. @@ -282,34 +289,42 @@ namespace { /// Local functions Value id_loop(const Position& pos, Move searchMoves[]); - Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value& oldAlpha, Value& beta); - Value search_pv(Position& pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID); - Value search(Position& pos, SearchStack ss[], Value beta, Depth depth, int ply, bool allowNullmove, int threadID, Move excludedMove = MOVE_NONE); - Value qsearch(Position& pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID); + Value root_search(Position& pos, SearchStack* ss, Move* pv, RootMoveList& rml, Value* alphaPtr, Value* betaPtr); + + template + Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int ply); + + template + Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int ply); + + template void sp_search(SplitPoint* sp, int threadID); - void sp_search_pv(SplitPoint* sp, int threadID); - void init_node(SearchStack ss[], int ply, int threadID); - void update_pv(SearchStack ss[], int ply); - void sp_update_pv(SearchStack* pss, SearchStack ss[], int ply); + + template + Depth extension(const Position& pos, Move m, bool captureOrPromotion, bool moveIsCheck, bool singleEvasion, bool mateThreat, bool* dangerous); + bool connected_moves(const Position& pos, Move m1, Move m2); bool value_is_mate(Value value); - bool move_is_killer(Move m, const SearchStack& ss); - Depth extension(const Position&, Move, bool, bool, bool, bool, bool, bool*); - bool ok_to_do_nullmove(const Position& pos); - bool ok_to_prune(const Position& pos, Move m, Move threat); + Value value_to_tt(Value v, int ply); + Value value_from_tt(Value v, int ply); + bool move_is_killer(Move m, SearchStack* ss); 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_killers(Move m, SearchStack* ss); void update_gains(const Position& pos, Move move, Value before, Value after); int current_search_time(); + std::string value_to_uci(Value v); int nps(); - void poll(SearchStack ss[], int ply); + void poll(); void ponderhit(); void wait_for_stop_or_ponderhit(); - void init_ss_array(SearchStack ss[]); - void print_pv_info(const Position& pos, SearchStack ss[], Value alpha, Value beta, Value value); + void init_ss_array(SearchStack* ss, int size); + void print_pv_info(const Position& pos, Move pv[], Value alpha, Value beta, Value value); + void insert_pv_in_tt(const Position& pos, Move pv[]); + void extract_pv_from_tt(const Position& pos, Move bestMove, Move pv[]); #if !defined(_MSC_VER) void *init_thread(void *threadID); @@ -327,9 +342,36 @@ namespace { /// init_threads(), exit_threads() and nodes_searched() are helpers to /// give accessibility to some TM methods from outside of current file. -void init_threads() { TM.init_threads(); } -void exit_threads() { TM.exit_threads(); } -int64_t nodes_searched() { return TM.nodes_searched(); } +void init_threads() { ThreadsMgr.init_threads(); } +void exit_threads() { ThreadsMgr.exit_threads(); } +int64_t nodes_searched() { return ThreadsMgr.nodes_searched(); } + + +/// init_search() is called during startup. It initializes various lookup tables + +void init_search() { + + int d; // depth (ONE_PLY == 2) + int hd; // half depth (ONE_PLY == 1) + int mc; // moveCount + + // Init reductions array + for (hd = 1; hd < 64; hd++) for (mc = 1; mc < 64; mc++) + { + double pvRed = 0.33 + log(double(hd)) * log(double(mc)) / 4.5; + 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); + } + + // Init futility margins array + for (d = 1; d < 16; d++) for (mc = 0; mc < 64; mc++) + FutilityMarginsMatrix[d][mc] = 112 * int(log(double(d * d) / 2) / log(2.0) + 1.001) - 8 * mc + 45; + + // Init futility move count array + for (d = 0; d < 32; d++) + FutilityMoveCountArray[d] = 3 + (1 << (3 * d / 8)); +} /// perft() is our utility to verify move generation is bug free. All the legal @@ -337,26 +379,27 @@ int64_t nodes_searched() { return TM.nodes_searched(); } int perft(Position& pos, Depth depth) { + MoveStack mlist[256]; StateInfo st; - Move move; + Move m; int sum = 0; - MovePicker mp(pos, MOVE_NONE, depth, H); + + // Generate all legal moves + MoveStack* last = generate_moves(pos, mlist); // If we are at the last ply we don't need to do and undo // the moves, just to count them. - if (depth <= OnePly) // Replace with '<' to test also qsearch - { - while (mp.get_next_move()) sum++; - return sum; - } + if (depth <= ONE_PLY) + return int(last - mlist); // Loop through all legal moves CheckInfo ci(pos); - while ((move = mp.get_next_move()) != MOVE_NONE) + for (MoveStack* cur = mlist; cur != last; cur++) { - pos.do_move(move, st, ci, pos.move_is_check(move, ci)); - sum += perft(pos, depth - OnePly); - pos.undo_move(move); + 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; } @@ -367,14 +410,13 @@ int perft(Position& pos, Depth depth) /// search-related global variables, and calls root_search(). It returns false /// when a quit command is received during the search. -bool think(const Position& pos, bool infinite, bool ponder, int side_to_move, - int time[], int increment[], int movesToGo, int maxDepth, - int maxNodes, int maxTime, Move searchMoves[]) { +bool think(const 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 = false; NodesSincePoll = 0; - TM.resetNodeCounters(); + ThreadsMgr.resetNodeCounters(); SearchStartTime = get_system_time(); ExactMaxTime = maxTime; MaxDepth = maxDepth; @@ -389,7 +431,7 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move, if (get_option_value_string("Book File") != OpeningBook.file_name()) OpeningBook.open(get_option_value_string("Book File")); - Move bookMove = OpeningBook.get_move(pos); + Move bookMove = OpeningBook.get_move(pos, get_option_value_bool("Best Book Move")); if (bookMove != MOVE_NONE) { if (PonderSearch) @@ -400,10 +442,6 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move, } } - // Reset loseOnTime flag at the beginning of a new game - if (button_was_pressed("New Game")) - loseOnTime = false; - // Read UCI option values TT.set_size(get_option_value_int("Hash")); if (button_was_pressed("Clear Hash")) @@ -422,11 +460,9 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move, MateThreatExtension[1] = Depth(get_option_value_int("Mate Threat Extension (PV nodes)")); MateThreatExtension[0] = Depth(get_option_value_int("Mate Threat Extension (non-PV nodes)")); - MinimumSplitDepth = get_option_value_int("Minimum Split Depth") * OnePly; + MinimumSplitDepth = get_option_value_int("Minimum Split Depth") * ONE_PLY; MaxThreadsPerSplitPoint = get_option_value_int("Maximum Number of Threads per Split Point"); - ShowCurrentLine = get_option_value_bool("UCI_ShowCurrLine"); MultiPV = get_option_value_int("MultiPV"); - Chess960 = get_option_value_bool("UCI_Chess960"); UseLogFile = get_option_value_bool("Use Search Log"); if (UseLogFile) @@ -436,57 +472,20 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move, // Set the number of active threads int newActiveThreads = get_option_value_int("Threads"); - if (newActiveThreads != TM.active_threads()) + if (newActiveThreads != ThreadsMgr.active_threads()) { - TM.set_active_threads(newActiveThreads); - init_eval(TM.active_threads()); - // HACK: init_eval() destroys the static castleRightsMask[] array in the - // Position class. The below line repairs the damage. - Position p(pos.to_fen()); - assert(pos.is_ok()); + ThreadsMgr.set_active_threads(newActiveThreads); + init_eval(ThreadsMgr.active_threads()); } // Wake up sleeping threads - TM.wake_sleeping_threads(); + ThreadsMgr.wake_sleeping_threads(); // Set thinking time - int myTime = time[side_to_move]; - int myIncrement = increment[side_to_move]; + int myTime = time[pos.side_to_move()]; + int myIncrement = increment[pos.side_to_move()]; if (UseTimeManagement) - { - if (!movesToGo) // Sudden death time control - { - if (myIncrement) - { - MaxSearchTime = myTime / 30 + myIncrement; - AbsoluteMaxSearchTime = Max(myTime / 4, myIncrement - 100); - } - else // Blitz game without increment - { - MaxSearchTime = myTime / 30; - AbsoluteMaxSearchTime = myTime / 8; - } - } - else // (x moves) / (y minutes) - { - if (movesToGo == 1) - { - MaxSearchTime = myTime / 2; - AbsoluteMaxSearchTime = (myTime > 3000)? (myTime - 500) : ((myTime * 3) / 4); - } - else - { - MaxSearchTime = myTime / Min(movesToGo, 20); - AbsoluteMaxSearchTime = Min((4 * myTime) / movesToGo, myTime / 3); - } - } - - if (get_option_value_bool("Ponder")) - { - MaxSearchTime += MaxSearchTime / 4; - MaxSearchTime = Min(MaxSearchTime, AbsoluteMaxSearchTime); - } - } + TimeMgr.init(myTime, myIncrement, movesToGo, pos.startpos_ply_counter()); // Set best NodesBetweenPolls interval to avoid lagging under // heavy time pressure. @@ -508,91 +507,18 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move, << " increment: " << myIncrement << " moves to go: " << movesToGo << endl; - // LSN filtering. Used only for developing purposes, disabled by default - if ( UseLSNFiltering - && loseOnTime) - { - // Step 2. If after last move we decided to lose on time, do it now! - while (SearchStartTime + myTime + 1000 > get_system_time()) - /* wait here */; - } - // We're ready to start thinking. Call the iterative deepening loop function - Value v = id_loop(pos, searchMoves); - - if (UseLSNFiltering) - { - // Step 1. If this is sudden death game and our position is hopeless, - // decide to lose on time. - if ( !loseOnTime // If we already lost on time, go to step 3. - && myTime < LSNTime - && myIncrement == 0 - && movesToGo == 0 - && v < -LSNValue) - { - loseOnTime = true; - } - else if (loseOnTime) - { - // Step 3. Now after stepping over the time limit, reset flag for next match. - loseOnTime = false; - } - } + id_loop(pos, searchMoves); if (UseLogFile) LogFile.close(); - TM.put_threads_to_sleep(); + ThreadsMgr.put_threads_to_sleep(); return !Quit; } -/// init_search() is called during startup. It initializes various lookup tables - -void init_search() { - - // Init our reduction lookup tables - for (int i = 1; i < 64; i++) // i == depth (OnePly = 1) - for (int j = 1; j < 64; j++) // j == moveNumber - { - double pvRed = 0.5 + log(double(i)) * log(double(j)) / 6.0; - double nonPVRed = 0.5 + log(double(i)) * log(double(j)) / 3.0; - PVReductionMatrix[i][j] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(OnePly)) : 0); - NonPVReductionMatrix[i][j] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(OnePly)) : 0); - } - - // Init futility margins array - for (int i = 0; i < 16; i++) // i == depth (OnePly = 2) - for (int j = 0; j < 64; j++) // j == moveNumber - { - // FIXME: test using log instead of BSR - FutilityMarginsMatrix[i][j] = (i < 2 ? 0 : 112 * bitScanReverse32(i * i / 2)) - 8 * j; - } - - // Init futility move count array - for (int i = 0; i < 32; i++) // i == depth (OnePly = 2) - FutilityMoveCountArray[i] = 3 + (1 << (3 * i / 8)); -} - - -// SearchStack::init() initializes a search stack. Used at the beginning of a -// new search from the root. -void SearchStack::init(int ply) { - - pv[ply] = pv[ply + 1] = MOVE_NONE; - currentMove = threatMove = MOVE_NONE; - reduction = Depth(0); - eval = VALUE_NONE; -} - -void SearchStack::initKillers() { - - mateKiller = MOVE_NONE; - for (int i = 0; i < KILLER_MAX; i++) - killers[i] = MOVE_NONE; -} - namespace { // id_loop() is the main iterative deepening loop. It calls root_search @@ -602,8 +528,9 @@ namespace { Value id_loop(const Position& pos, Move searchMoves[]) { - Position p(pos); + Position p(pos, pos.thread()); SearchStack ss[PLY_MAX_PLUS_2]; + Move pv[PLY_MAX_PLUS_2]; Move EasyMove = MOVE_NONE; Value value, alpha = -VALUE_INFINITE, beta = VALUE_INFINITE; @@ -621,18 +548,20 @@ namespace { // Print RootMoveList startup scoring to the standard output, // so to output information also for iteration 1. - cout << "info depth " << 1 + cout << set960(p.is_chess960()) // Is enough to set once at the beginning + << "info depth " << 1 << "\ninfo depth " << 1 - << " score " << value_to_string(rml.get_move_score(0)) + << " score " << value_to_uci(rml.get_move_score(0)) << " time " << current_search_time() - << " nodes " << TM.nodes_searched() + << " nodes " << ThreadsMgr.nodes_searched() << " nps " << nps() << " pv " << rml.get_move(0) << "\n"; // Initialize TT.new_search(); H.clear(); - init_ss_array(ss); + init_ss_array(ss, PLY_MAX_PLUS_2); + pv[0] = pv[1] = MOVE_NONE; ValueByIteration[1] = rml.get_move_score(0); Iteration = 1; @@ -647,8 +576,6 @@ namespace { // Initialize iteration Iteration++; BestMoveChangesByIteration[Iteration] = 0; - if (Iteration <= 5) - ExtraSearchTime = 0; cout << "info depth " << Iteration << endl; @@ -665,12 +592,12 @@ namespace { beta = Min(ValueByIteration[Iteration - 1] + AspirationDelta, VALUE_INFINITE); } - // Search to the current depth, rml is updated and sorted - value = root_search(p, ss, rml, alpha, beta); + // Search to the current depth, rml is updated and sorted, alpha and beta could change + value = root_search(p, ss, pv, rml, &alpha, &beta); // Write PV to transposition table, in case the relevant entries have // been overwritten during the search. - TT.insert_pv(p, ss[0].pv); + insert_pv_in_tt(p, pv); if (AbortSearch) break; // Value cannot be trusted. Break out immediately! @@ -679,7 +606,7 @@ namespace { ValueByIteration[Iteration] = value; // Drop the easy move if differs from the new best move - if (ss[0].pv[0] != EasyMove) + if (pv[0] != EasyMove) EasyMove = MOVE_NONE; if (UseTimeManagement) @@ -699,24 +626,24 @@ namespace { stopSearch = true; // Stop search early if one move seems to be much better than the others - int64_t nodes = TM.nodes_searched(); + int64_t nodes = ThreadsMgr.nodes_searched(); if ( Iteration >= 8 - && EasyMove == ss[0].pv[0] - && ( ( rml.get_move_cumulative_nodes(0) > (nodes * 85) / 100 - && current_search_time() > MaxSearchTime / 16) - ||( rml.get_move_cumulative_nodes(0) > (nodes * 98) / 100 - && current_search_time() > MaxSearchTime / 32))) + && EasyMove == pv[0] + && ( ( rml.get_move_nodes(0) > (nodes * 85) / 100 + && current_search_time() > TimeMgr.available_time() / 16) + ||( rml.get_move_nodes(0) > (nodes * 98) / 100 + && current_search_time() > TimeMgr.available_time() / 32))) stopSearch = true; // Add some extra time if the best move has changed during the last two iterations if (Iteration > 5 && Iteration <= 50) - ExtraSearchTime = BestMoveChangesByIteration[Iteration] * (MaxSearchTime / 2) - + BestMoveChangesByIteration[Iteration-1] * (MaxSearchTime / 3); + TimeMgr.pv_unstability(BestMoveChangesByIteration[Iteration], + BestMoveChangesByIteration[Iteration-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() > ((MaxSearchTime + ExtraSearchTime) * 80) / 128) + if (current_search_time() > (TimeMgr.available_time() * 80) / 128) stopSearch = true; if (stopSearch) @@ -738,24 +665,23 @@ namespace { wait_for_stop_or_ponderhit(); else // Print final search statistics - cout << "info nodes " << TM.nodes_searched() + cout << "info nodes " << ThreadsMgr.nodes_searched() << " nps " << nps() - << " time " << current_search_time() - << " hashfull " << TT.full() << endl; + << " time " << current_search_time() << endl; // Print the best move and the ponder move to the standard output - if (ss[0].pv[0] == MOVE_NONE) + if (pv[0] == MOVE_NONE) { - ss[0].pv[0] = rml.get_move(0); - ss[0].pv[1] = MOVE_NONE; + pv[0] = rml.get_move(0); + pv[1] = MOVE_NONE; } - assert(ss[0].pv[0] != MOVE_NONE); + assert(pv[0] != MOVE_NONE); - cout << "bestmove " << ss[0].pv[0]; + cout << "bestmove " << pv[0]; - if (ss[0].pv[1] != MOVE_NONE) - cout << " ponder " << ss[0].pv[1]; + if (pv[1] != MOVE_NONE) + cout << " ponder " << pv[1]; cout << endl; @@ -767,14 +693,14 @@ namespace { if (dbg_show_hit_rate) dbg_print_hit_rate(LogFile); - LogFile << "\nNodes: " << TM.nodes_searched() + LogFile << "\nNodes: " << ThreadsMgr.nodes_searched() << "\nNodes/second: " << nps() - << "\nBest move: " << move_to_san(p, ss[0].pv[0]); + << "\nBest move: " << move_to_san(p, pv[0]); StateInfo st; - p.do_move(ss[0].pv[0], st); + p.do_move(pv[0], st); LogFile << "\nPonder move: " - << move_to_san(p, ss[0].pv[1]) // Works also with MOVE_NONE + << move_to_san(p, pv[1]) // Works also with MOVE_NONE << endl; } return rml.get_move_score(0); @@ -786,31 +712,34 @@ namespace { // scheme, prints some information to the standard output and handles // the fail low/high loops. - Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value& oldAlpha, Value& beta) { + Value root_search(Position& pos, SearchStack* ss, Move* pv, RootMoveList& rml, Value* alphaPtr, Value* betaPtr) { - EvalInfo ei; + Value margins[2]; StateInfo st; + CheckInfo ci(pos); int64_t nodes; Move move; Depth depth, ext, newDepth; - Value value, alpha; + Value value, alpha, beta; bool isCheck, moveIsCheck, captureOrPromotion, dangerous; - int researchCount = 0; - CheckInfo ci(pos); - alpha = oldAlpha; + int researchCountFH, researchCountFL; + + researchCountFH = researchCountFL = 0; + alpha = *alphaPtr; + beta = *betaPtr; isCheck = pos.is_check(); + depth = (Iteration - 2) * ONE_PLY + InitialDepth; - // Step 1. Initialize node and poll (omitted at root, but I can see no good reason for this, FIXME) - // Step 2. Check for aborted search (omitted at root, because we do not initialize root node) + // Step 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 - if (!isCheck) - ss[0].eval = evaluate(pos, ei, 0); - else - ss[0].eval = VALUE_NONE; // HACK because we do not initialize root node + ss->eval = isCheck ? VALUE_NONE : evaluate(pos, margins); // Step 6. Razoring (omitted at root) // Step 7. Static null move pruning (omitted at root) @@ -823,6 +752,7 @@ namespace { while (1) { // Sort the moves before to (re)search + rml.score_moves(pos); rml.sort(); // Step 10. Loop through all moves in the root move list @@ -832,14 +762,11 @@ namespace { FirstRootMove = (i == 0); // Save the current node count before the move is searched - nodes = TM.nodes_searched(); - - // Reset beta cut-off counters - TM.resetBetaCounters(); + nodes = ThreadsMgr.nodes_searched(); // Pick the next root move, and print the move and the move number to // the standard output. - move = ss[0].currentMove = rml.get_move(i); + move = ss->currentMove = rml.get_move(i); if (current_search_time() >= 1000) cout << "info currmove " << move @@ -849,8 +776,7 @@ namespace { captureOrPromotion = pos.move_is_capture_or_promotion(move); // Step 11. Decide the new search depth - depth = (Iteration - 2) * OnePly + InitialDepth; - ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, false, false, &dangerous); + ext = extension(pos, move, captureOrPromotion, moveIsCheck, false, false, &dangerous); newDepth = depth + ext; // Step 12. Futility pruning (omitted at root) @@ -875,7 +801,7 @@ namespace { alpha = -VALUE_INFINITE; // Full depth PV search, done on first move or after a fail high - value = -search_pv(pos, ss, -beta, -alpha, newDepth, 1, 0); + value = -search(pos, ss+1, -beta, -alpha, newDepth, 1); } else { @@ -883,31 +809,45 @@ namespace { // if the move fails high will be re-searched at full depth bool doFullDepthSearch = true; - if ( depth >= 3 * OnePly + if ( depth >= 3 * ONE_PLY && !dangerous && !captureOrPromotion && !move_is_castle(move)) { - ss[0].reduction = pv_reduction(depth, i - MultiPV + 2); - if (ss[0].reduction) + 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, -alpha, newDepth-ss[0].reduction, 1, true, 0); + value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, 1); + doFullDepthSearch = (value > alpha); + } + + // The move failed high, but if reduction is very big we could + // face a false positive, retry with a less aggressive reduction, + // if the move fails high again then go with full depth search. + if (doFullDepthSearch && ss->reduction > 2 * ONE_PLY) + { + assert(newDepth - ONE_PLY >= ONE_PLY); + + ss->reduction = ONE_PLY; + 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 - ss[0].reduction = Depth(0); - value = -search(pos, ss, -alpha, newDepth, 1, true, 0); + 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_pv(pos, ss, -beta, -alpha, newDepth, 1, 0); + value = -search(pos, ss+1, -beta, -alpha, newDepth, 1); } } @@ -921,16 +861,16 @@ namespace { // We are failing high and going to do a research. It's important to update // the score before research in case we run out of time while researching. rml.set_move_score(i, value); - update_pv(ss, 0); - TT.extract_pv(pos, ss[0].pv, PLY_MAX); - rml.set_move_pv(i, ss[0].pv); + ss->bestMove = move; + extract_pv_from_tt(pos, move, pv); + rml.set_move_pv(i, pv); // Print information to the standard output - print_pv_info(pos, ss, alpha, beta, value); + print_pv_info(pos, pv, alpha, beta, value); // Prepare for a research after a fail high, each time with a wider window - researchCount++; - beta = Min(beta + AspirationDelta * (1 << researchCount), VALUE_INFINITE); + *betaPtr = beta = Min(beta + AspirationDelta * (1 << researchCountFH), VALUE_INFINITE); + researchCountFH++; } // End of fail high loop @@ -942,14 +882,11 @@ namespace { if (AbortSearch) break; - // Remember beta-cutoff and searched nodes counts for this move. The - // info is used to sort the root moves for the next iteration. - int64_t our, their; - TM.get_beta_counters(pos.side_to_move(), our, their); - rml.set_beta_counters(i, our, their); - rml.set_move_nodes(i, TM.nodes_searched() - nodes); + // Remember searched nodes counts for this move + rml.add_move_nodes(i, ThreadsMgr.nodes_searched() - nodes); assert(value >= -VALUE_INFINITE && value <= VALUE_INFINITE); + assert(value < beta); // Step 17. Check for new best move if (value <= alpha && i >= MultiPV) @@ -960,9 +897,9 @@ namespace { // Update PV rml.set_move_score(i, value); - update_pv(ss, 0); - TT.extract_pv(pos, ss[0].pv, PLY_MAX); - rml.set_move_pv(i, ss[0].pv); + ss->bestMove = move; + extract_pv_from_tt(pos, move, pv); + rml.set_move_pv(i, pv); if (MultiPV == 1) { @@ -973,10 +910,9 @@ namespace { BestMoveChangesByIteration[Iteration]++; // Print information to the standard output - print_pv_info(pos, ss, alpha, beta, value); + print_pv_info(pos, pv, alpha, beta, value); - // Raise alpha to setup proper non-pv search upper bound, note - // that we can end up with alpha >= beta and so get a fail high. + // Raise alpha to setup proper non-pv search upper bound if (value > alpha) alpha = value; } @@ -986,10 +922,10 @@ namespace { for (int j = 0; j < Min(MultiPV, rml.move_count()); j++) { cout << "info multipv " << j + 1 - << " score " << value_to_string(rml.get_move_score(j)) + << " score " << value_to_uci(rml.get_move_score(j)) << " depth " << (j <= i ? Iteration : Iteration - 1) << " time " << current_search_time() - << " nodes " << TM.nodes_searched() + << " nodes " << ThreadsMgr.nodes_searched() << " nps " << nps() << " pv "; @@ -1002,22 +938,21 @@ namespace { } } // PV move or new best move - assert(alpha >= oldAlpha); + assert(alpha >= *alphaPtr); - AspirationFailLow = (alpha == oldAlpha); + AspirationFailLow = (alpha == *alphaPtr); if (AspirationFailLow && StopOnPonderhit) StopOnPonderhit = false; } // Can we exit fail low loop ? - if (AbortSearch || alpha > oldAlpha) + if (AbortSearch || !AspirationFailLow) break; // Prepare for a research after a fail low, each time with a wider window - researchCount++; - alpha = Max(alpha - AspirationDelta * (1 << researchCount), -VALUE_INFINITE); - oldAlpha = alpha; + *alphaPtr = alpha = Max(alpha - AspirationDelta * (1 << researchCountFL), -VALUE_INFINITE); + researchCountFL++; } // Fail low loop @@ -1028,50 +963,67 @@ namespace { } - // search_pv() is the main search function for PV nodes. + // search<>() is the main search function for both PV and non-PV nodes - Value search_pv(Position& pos, SearchStack ss[], Value alpha, Value beta, - Depth depth, int ply, int threadID) { + template + Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int ply) { assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE); assert(beta > alpha && beta <= VALUE_INFINITE); - assert(ply >= 0 && ply < PLY_MAX); - assert(threadID >= 0 && threadID < TM.active_threads()); + assert(PvNode || alpha == beta - 1); + assert(ply > 0 && ply < PLY_MAX); + assert(pos.thread() >= 0 && pos.thread() < ThreadsMgr.active_threads()); Move movesSearched[256]; - EvalInfo ei; + Value margins[2]; StateInfo st; - const TTEntry* tte; - Move ttMove, move; + const TTEntry *tte; + Key posKey; + Move ttMove, move, excludedMove, threatMove; Depth ext, newDepth; Value bestValue, value, oldAlpha; - bool isCheck, singleEvasion, moveIsCheck, captureOrPromotion, dangerous; + Value refinedValue, nullValue, futilityBase, futilityValueScaled; // Non-PV specific + bool isCheck, singleEvasion, singularExtensionNode, moveIsCheck, captureOrPromotion, dangerous; bool mateThreat = false; int moveCount = 0; - bestValue = value = -VALUE_INFINITE; + int threadID = pos.thread(); + refinedValue = bestValue = value = -VALUE_INFINITE; + oldAlpha = alpha; - if (depth < OnePly) - return qsearch(pos, ss, alpha, beta, Depth(0), ply, threadID); + // Step 1. Initialize node and poll. Polling can abort search + ThreadsMgr.incrementNodeCounter(threadID); + ss->currentMove = ss->bestMove = threatMove = MOVE_NONE; + (ss+2)->killers[0] = (ss+2)->killers[1] = (ss+2)->mateKiller = MOVE_NONE; - // Step 1. Initialize node and poll - // Polling can abort search. - init_node(ss, ply, threadID); + if (threadID == 0 && ++NodesSincePoll > NodesBetweenPolls) + { + NodesSincePoll = 0; + poll(); + } // Step 2. Check for aborted search and immediate draw - if (AbortSearch || TM.thread_should_stop(threadID)) - return Value(0); + if (AbortSearch || ThreadsMgr.thread_should_stop(threadID)) + return VALUE_ZERO; if (pos.is_draw() || ply >= PLY_MAX - 1) return VALUE_DRAW; // Step 3. Mate distance pruning - oldAlpha = alpha; alpha = Max(value_mated_in(ply), alpha); beta = Min(value_mate_in(ply+1), beta); if (alpha >= beta) return alpha; // Step 4. Transposition table lookup + + // We don't want the score of a partial search to overwrite a previous full search + // TT value, so we use a different position key in case of an excluded move exists. + excludedMove = ss->excludedMove; + posKey = excludedMove ? pos.get_exclusion_key() : pos.get_key(); + + tte = TT.retrieve(posKey); + ttMove = (tte ? tte->move() : MOVE_NONE); + // 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: // @@ -1079,316 +1031,116 @@ namespace { // * Fifty move rule detection // * Searching for a mate // * Printing of full PV line - tte = TT.retrieve(pos.get_key()); - ttMove = (tte ? tte->move() : MOVE_NONE); - // Step 5. Evaluate the position statically - // At PV nodes we do this only to update gain statistics - isCheck = pos.is_check(); - if (!isCheck) + if (!PvNode && tte && ok_to_use_TT(tte, depth, beta, ply)) { - ss[ply].eval = evaluate(pos, ei, threadID); - update_gains(pos, ss[ply - 1].currentMove, ss[ply - 1].eval, ss[ply].eval); - } - - // Step 6. Razoring (is omitted in PV nodes) - // Step 7. Static null move pruning (is omitted in PV nodes) - // Step 8. Null move search with verification search (is omitted in PV nodes) + // Refresh tte entry to avoid aging + TT.store(posKey, tte->value(), tte->type(), tte->depth(), ttMove, tte->static_value(), tte->static_value_margin()); - // Step 9. Internal iterative deepening - if ( depth >= IIDDepthAtPVNodes - && ttMove == MOVE_NONE) - { - search_pv(pos, ss, alpha, beta, depth-2*OnePly, ply, threadID); - ttMove = ss[ply].pv[ply]; - tte = TT.retrieve(pos.get_key()); + ss->bestMove = ttMove; // Can be MOVE_NONE + return value_from_tt(tte->value(), ply); } - // Step 10. Loop through moves - // Loop through all legal moves until no moves remain or a beta cutoff occurs - - // Initialize a MovePicker object for the current position - mateThreat = pos.has_mate_threat(opposite_color(pos.side_to_move())); - MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply]); - CheckInfo ci(pos); - - while ( alpha < beta - && (move = mp.get_next_move()) != MOVE_NONE - && !TM.thread_should_stop(threadID)) + // Step 5. Evaluate the position statically and + // update gain statistics of parent move. + isCheck = pos.is_check(); + if (isCheck) + ss->eval = VALUE_NONE; + else if (tte) { - assert(move_is_ok(move)); - - singleEvasion = (isCheck && mp.number_of_evasions() == 1); - moveIsCheck = pos.move_is_check(move, ci); - captureOrPromotion = pos.move_is_capture_or_promotion(move); + assert(tte->static_value() != VALUE_NONE); - // Step 11. Decide the new search depth - ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, singleEvasion, mateThreat, &dangerous); - - // Singular extension search. We extend the TT move if its value is much better than - // its siblings. To verify this we do a reduced search on all the other moves but the - // ttMove, if result is lower then ttValue minus a margin then we extend ttMove. - if ( depth >= SingularExtensionDepthAtPVNodes - && tte - && move == tte->move() - && ext < OnePly - && is_lower_bound(tte->type()) - && tte->depth() >= depth - 3 * OnePly) - { - Value ttValue = value_from_tt(tte->value(), ply); - - if (abs(ttValue) < VALUE_KNOWN_WIN) - { - Value excValue = search(pos, ss, ttValue - SingularExtensionMargin, depth / 2, ply, false, threadID, move); - - if (excValue < ttValue - SingularExtensionMargin) - ext = OnePly; - } - } - - newDepth = depth - OnePly + ext; - - // Update current move (this must be done after singular extension search) - movesSearched[moveCount++] = ss[ply].currentMove = move; - - // Step 12. Futility pruning (is omitted in PV nodes) - - // Step 13. Make the move - pos.do_move(move, st, ci, moveIsCheck); - - // Step extra. pv search (only in PV nodes) - // The first move in list is the expected PV - if (moveCount == 1) - value = -search_pv(pos, ss, -beta, -alpha, newDepth, ply+1, threadID); - else - { - // Step 14. Reduced search - // if the move fails high will be re-searched at full depth. - bool doFullDepthSearch = true; - - if ( depth >= 3 * OnePly - && !dangerous - && !captureOrPromotion - && !move_is_castle(move) - && !move_is_killer(move, ss[ply])) - { - ss[ply].reduction = pv_reduction(depth, moveCount); - if (ss[ply].reduction) - { - value = -search(pos, ss, -alpha, newDepth-ss[ply].reduction, ply+1, true, threadID); - doFullDepthSearch = (value > alpha); - } - } - - // Step 15. Full depth search - if (doFullDepthSearch) - { - ss[ply].reduction = Depth(0); - value = -search(pos, ss, -alpha, newDepth, ply+1, true, threadID); - - // Step extra. pv search (only in PV nodes) - if (value > alpha && value < beta) - value = -search_pv(pos, ss, -beta, -alpha, newDepth, ply+1, threadID); - } - } - - // Step 16. Undo move - pos.undo_move(move); - - assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); - - // Step 17. Check for new best move - if (value > bestValue) - { - bestValue = value; - if (value > alpha) - { - alpha = value; - update_pv(ss, ply); - if (value == value_mate_in(ply + 1)) - ss[ply].mateKiller = move; - } - } - - // Step 18. Check for split - if ( TM.active_threads() > 1 - && bestValue < beta - && depth >= MinimumSplitDepth - && Iteration <= 99 - && TM.available_thread_exists(threadID) - && !AbortSearch - && !TM.thread_should_stop(threadID) - && TM.split(pos, ss, ply, &alpha, beta, &bestValue, - depth, mateThreat, &moveCount, &mp, threadID, true)) - break; - } - - // Step 19. Check for mate and stalemate - // All legal moves have been searched and if there were - // no legal moves, it must be mate or stalemate. - if (moveCount == 0) - return (isCheck ? value_mated_in(ply) : VALUE_DRAW); - - // Step 20. Update tables - // If the search is not aborted, update the transposition table, - // history counters, and killer moves. - if (AbortSearch || TM.thread_should_stop(threadID)) - return bestValue; - - if (bestValue <= oldAlpha) - TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_UPPER, depth, MOVE_NONE); - - else if (bestValue >= beta) - { - TM.incrementBetaCounter(pos.side_to_move(), depth, threadID); - move = ss[ply].pv[ply]; - if (!pos.move_is_capture_or_promotion(move)) - { - update_history(pos, move, depth, movesSearched, moveCount); - update_killers(move, ss[ply]); - } - TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, move); + ss->eval = tte->static_value(); + margins[pos.side_to_move()] = tte->static_value_margin(); + refinedValue = refine_eval(tte, ss->eval, ply); } else - TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EXACT, depth, ss[ply].pv[ply]); - - return bestValue; - } - - - // search() is the search function for zero-width nodes. - - Value search(Position& pos, SearchStack ss[], Value beta, Depth depth, - int ply, bool allowNullmove, int threadID, Move excludedMove) { - - assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE); - assert(ply >= 0 && ply < PLY_MAX); - assert(threadID >= 0 && threadID < TM.active_threads()); - - Move movesSearched[256]; - EvalInfo ei; - StateInfo st; - const TTEntry* tte; - Move ttMove, move; - Depth ext, newDepth; - Value bestValue, refinedValue, nullValue, value, futilityValueScaled; - bool isCheck, singleEvasion, moveIsCheck, captureOrPromotion, dangerous; - bool mateThreat = false; - int moveCount = 0; - refinedValue = bestValue = value = -VALUE_INFINITE; - - if (depth < OnePly) - return qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID); - - // Step 1. Initialize node and poll - // Polling can abort search. - init_node(ss, ply, threadID); - - // Step 2. Check for aborted search and immediate draw - if (AbortSearch || TM.thread_should_stop(threadID)) - return Value(0); - - if (pos.is_draw() || ply >= PLY_MAX - 1) - return VALUE_DRAW; - - // Step 3. Mate distance pruning - if (value_mated_in(ply) >= beta) - return beta; - - if (value_mate_in(ply + 1) < beta) - return beta - 1; - - // Step 4. Transposition table lookup - - // We don't want the score of a partial search to overwrite a previous full search - // TT value, so we use a different position key in case of an excluded move exists. - Key posKey = excludedMove ? pos.get_exclusion_key() : pos.get_key(); - - tte = TT.retrieve(posKey); - ttMove = (tte ? tte->move() : MOVE_NONE); - - if (tte && ok_to_use_TT(tte, depth, beta, ply)) { - ss[ply].currentMove = ttMove; // Can be MOVE_NONE - return value_from_tt(tte->value(), ply); + refinedValue = ss->eval = evaluate(pos, margins); + TT.store(posKey, VALUE_NONE, VALUE_TYPE_NONE, DEPTH_NONE, MOVE_NONE, ss->eval, margins[pos.side_to_move()]); } - // Step 5. Evaluate the position statically - isCheck = pos.is_check(); - - if (!isCheck) - { - if (tte && (tte->type() & VALUE_TYPE_EVAL)) - ss[ply].eval = value_from_tt(tte->value(), ply); - else - ss[ply].eval = evaluate(pos, ei, threadID); - - refinedValue = refine_eval(tte, ss[ply].eval, ply); // Enhance accuracy with TT value if possible - update_gains(pos, ss[ply - 1].currentMove, ss[ply - 1].eval, ss[ply].eval); - } + // Save gain for the parent non-capture move + update_gains(pos, (ss-1)->currentMove, (ss-1)->eval, ss->eval); - // Step 6. Razoring - if ( !value_is_mate(beta) + // Step 6. Razoring (is omitted in PV nodes) + if ( !PvNode + && depth < RazorDepth && !isCheck - && depth < RazorDepth - && refinedValue < beta - razor_margin(depth) - && ss[ply - 1].currentMove != MOVE_NULL - && ttMove == MOVE_NONE + && refinedValue < beta - razor_margin(depth) + && ttMove == MOVE_NONE + && (ss-1)->currentMove != MOVE_NULL + && !value_is_mate(beta) && !pos.has_pawn_on_7th(pos.side_to_move())) { Value rbeta = beta - razor_margin(depth); - Value v = qsearch(pos, ss, rbeta-1, rbeta, Depth(0), ply, threadID); + Value v = qsearch(pos, ss, rbeta-1, rbeta, DEPTH_ZERO, ply); if (v < rbeta) // Logically we should return (v + razor_margin(depth)), but // surprisingly this did slightly weaker in tests. return v; } - // Step 7. Static null move pruning + // Step 7. Static null move pruning (is omitted in PV nodes) // We're betting that the opponent doesn't have a move that will reduce - // the score by more than fuility_margin(depth) if we do a null move. - if ( !isCheck - && allowNullmove - && depth < RazorDepth - && refinedValue - futility_margin(depth, 0) >= beta) + // the score by more than futility_margin(depth) if we do a null move. + if ( !PvNode + && !ss->skipNullMove + && depth < RazorDepth + && !isCheck + && refinedValue >= beta + futility_margin(depth, 0) + && !value_is_mate(beta) + && pos.non_pawn_material(pos.side_to_move())) return refinedValue - futility_margin(depth, 0); - // Step 8. Null move search with verification search + // Step 8. Null move search with verification search (is omitted in PV nodes) // When we jump directly to qsearch() we do a null move only if static value is // at least beta. Otherwise we do a null move if static value is not more than // NullMoveMargin under beta. - if ( allowNullmove - && depth > OnePly + if ( !PvNode + && !ss->skipNullMove + && depth > ONE_PLY && !isCheck + && refinedValue >= beta - (depth >= 4 * ONE_PLY ? NullMoveMargin : 0) && !value_is_mate(beta) - && ok_to_do_nullmove(pos) - && refinedValue >= beta - (depth >= 4 * OnePly ? NullMoveMargin : 0)) + && pos.non_pawn_material(pos.side_to_move())) { - ss[ply].currentMove = MOVE_NULL; - - pos.do_null_move(st); + ss->currentMove = MOVE_NULL; // Null move dynamic reduction based on depth - int R = 3 + (depth >= 5 * OnePly ? depth / 8 : 0); + int R = 3 + (depth >= 5 * ONE_PLY ? depth / 8 : 0); // Null move dynamic reduction based on value if (refinedValue - beta > PawnValueMidgame) R++; - nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID); + pos.do_null_move(st); + (ss+1)->skipNullMove = true; + nullValue = depth-R*ONE_PLY < ONE_PLY ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO, ply+1) + : - search(pos, ss+1, -beta, -alpha, depth-R*ONE_PLY, ply+1); + (ss+1)->skipNullMove = false; pos.undo_null_move(); if (nullValue >= beta) { - if (depth < 6 * OnePly) - return beta; + // Do not return unproven mate scores + if (nullValue >= value_mate_in(PLY_MAX)) + nullValue = beta; + + if (depth < 6 * ONE_PLY) + return nullValue; + + // Do verification search at high depths + ss->skipNullMove = true; + Value v = search(pos, ss, alpha, beta, depth-R*ONE_PLY, ply); + ss->skipNullMove = false; - // Do zugzwang verification search - Value v = search(pos, ss, beta, depth-5*OnePly, ply, false, threadID); if (v >= beta) - return beta; - } else { + return nullValue; + } + else + { // The null move failed low, which means that we may be faced with // some kind of threat. If the previous move was reduced, check if // the move that refuted the null move was somehow connected to the @@ -1398,35 +1150,51 @@ namespace { if (nullValue == value_mated_in(ply + 2)) mateThreat = true; - ss[ply].threatMove = ss[ply + 1].currentMove; + threatMove = (ss+1)->bestMove; if ( depth < ThreatDepth - && ss[ply - 1].reduction - && connected_moves(pos, ss[ply - 1].currentMove, ss[ply].threatMove)) + && (ss-1)->reduction + && connected_moves(pos, (ss-1)->currentMove, threatMove)) return beta - 1; } } // Step 9. Internal iterative deepening - if ( depth >= IIDDepthAtNonPVNodes - && ttMove == MOVE_NONE - && !isCheck - && ss[ply].eval >= beta - IIDMargin) + if ( depth >= IIDDepth[PvNode] + && ttMove == MOVE_NONE + && (PvNode || (!isCheck && ss->eval >= beta - IIDMargin))) { - search(pos, ss, beta, depth/2, ply, false, threadID); - ttMove = ss[ply].pv[ply]; + Depth d = (PvNode ? depth - 2 * ONE_PLY : depth / 2); + + ss->skipNullMove = true; + search(pos, ss, alpha, beta, d, ply); + ss->skipNullMove = false; + + ttMove = ss->bestMove; tte = TT.retrieve(posKey); } - // Step 10. Loop through moves - // Loop through all legal moves until no moves remain or a beta cutoff occurs + // Expensive mate threat detection (only for PV nodes) + if (PvNode) + mateThreat = pos.has_mate_threat(); // Initialize a MovePicker object for the current position - MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply], beta); + MovePicker mp = MovePicker(pos, ttMove, depth, H, ss, (PvNode ? -VALUE_INFINITE : beta)); CheckInfo ci(pos); + ss->bestMove = MOVE_NONE; + singleEvasion = isCheck && mp.number_of_evasions() == 1; + futilityBase = ss->eval + margins[pos.side_to_move()]; + singularExtensionNode = depth >= SingularExtensionDepth[PvNode] + && tte + && tte->move() + && !excludedMove // Do not allow recursive singular extension search + && (tte->type() & VALUE_TYPE_LOWER) + && tte->depth() >= depth - 3 * ONE_PLY; + // Step 10. Loop through moves + // Loop through all legal moves until no moves remain or a beta cutoff occurs while ( bestValue < beta && (move = mp.get_next_move()) != MOVE_NONE - && !TM.thread_should_stop(threadID)) + && !ThreadsMgr.thread_should_stop(threadID)) { assert(move_is_ok(move)); @@ -1434,56 +1202,60 @@ namespace { continue; moveIsCheck = pos.move_is_check(move, ci); - singleEvasion = (isCheck && mp.number_of_evasions() == 1); captureOrPromotion = pos.move_is_capture_or_promotion(move); // Step 11. Decide the new search depth - ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, singleEvasion, mateThreat, &dangerous); + ext = extension(pos, move, captureOrPromotion, moveIsCheck, singleEvasion, mateThreat, &dangerous); - // Singular extension search. We extend the TT move if its value is much better than - // its siblings. To verify this we do a reduced search on all the other moves but the - // ttMove, if result is lower then ttValue minus a margin then we extend ttMove. - if ( depth >= SingularExtensionDepthAtNonPVNodes - && tte + // 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. + if ( singularExtensionNode && move == tte->move() - && !excludedMove // Do not allow recursive single-reply search - && ext < OnePly - && is_lower_bound(tte->type()) - && tte->depth() >= depth - 3 * OnePly) + && ext < ONE_PLY) { Value ttValue = value_from_tt(tte->value(), ply); if (abs(ttValue) < VALUE_KNOWN_WIN) { - Value excValue = search(pos, ss, ttValue - SingularExtensionMargin, depth / 2, ply, false, threadID, move); - - if (excValue < ttValue - SingularExtensionMargin) - ext = OnePly; + Value b = ttValue - SingularExtensionMargin; + ss->excludedMove = move; + ss->skipNullMove = true; + Value v = search(pos, ss, b - 1, b, depth / 2, ply); + ss->skipNullMove = false; + ss->excludedMove = MOVE_NONE; + ss->bestMove = MOVE_NONE; + if (v < b) + ext = ONE_PLY; } } - newDepth = depth - OnePly + ext; + newDepth = depth - ONE_PLY + ext; // Update current move (this must be done after singular extension search) - movesSearched[moveCount++] = ss[ply].currentMove = move; + movesSearched[moveCount++] = ss->currentMove = move; - // Step 12. Futility pruning - if ( !isCheck - && !dangerous + // Step 12. Futility pruning (is omitted in PV nodes) + if ( !PvNode && !captureOrPromotion - && !move_is_castle(move) - && move != ttMove) + && !isCheck + && !dangerous + && move != ttMove + && !move_is_castle(move)) { // Move count based pruning if ( moveCount >= futility_move_count(depth) - && ok_to_prune(pos, move, ss[ply].threatMove) + && !(threatMove && connected_threat(pos, move, threatMove)) && bestValue > value_mated_in(PLY_MAX)) continue; // Value based pruning - Depth predictedDepth = newDepth - nonpv_reduction(depth, moveCount); // We illogically ignore reduction condition depth >= 3*OnePly - futilityValueScaled = ss[ply].eval + futility_margin(predictedDepth, moveCount) - + H.gain(pos.piece_on(move_from(move)), move_to(move)) + 45; + // 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)); if (futilityValueScaled < beta) { @@ -1494,31 +1266,62 @@ namespace { } // Step 13. Make the move - pos.do_move(move, st, ci, moveIsCheck); - - // Step 14. Reduced search - // if the move fails high will be re-searched at full depth. - bool doFullDepthSearch = true; + pos.do_move(move, st, ci, moveIsCheck); - if ( depth >= 3*OnePly - && !dangerous - && !captureOrPromotion - && !move_is_castle(move) - && !move_is_killer(move, ss[ply])) + // Step extra. pv search (only in PV nodes) + // The first move in list is the expected PV + if (PvNode && moveCount == 1) + value = newDepth < ONE_PLY ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO, ply+1) + : - search(pos, ss+1, -beta, -alpha, newDepth, ply+1); + else { - ss[ply].reduction = nonpv_reduction(depth, moveCount); - if (ss[ply].reduction) + // Step 14. Reduced depth search + // If the move fails high will be re-searched at full depth. + bool doFullDepthSearch = true; + + if ( depth >= 3 * ONE_PLY + && !captureOrPromotion + && !dangerous + && !move_is_castle(move) + && !move_is_killer(move, ss)) { - value = -search(pos, ss, -(beta-1), newDepth-ss[ply].reduction, ply+1, true, threadID); - doFullDepthSearch = (value >= beta); + ss->reduction = reduction(depth, moveCount); + if (ss->reduction) + { + Depth d = newDepth - ss->reduction; + value = d < ONE_PLY ? -qsearch(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO, ply+1) + : - search(pos, ss+1, -(alpha+1), -alpha, d, ply+1); + + doFullDepthSearch = (value > alpha); + } + + // The move failed high, but if reduction is very big we could + // face a false positive, retry with a less aggressive reduction, + // if the move fails high again then go with full depth search. + if (doFullDepthSearch && ss->reduction > 2 * ONE_PLY) + { + assert(newDepth - ONE_PLY >= ONE_PLY); + + ss->reduction = ONE_PLY; + value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, ply+1); + doFullDepthSearch = (value > alpha); + } + ss->reduction = DEPTH_ZERO; // Restore original reduction } - } - // Step 15. Full depth search - if (doFullDepthSearch) - { - ss[ply].reduction = Depth(0); - value = -search(pos, ss, -(beta-1), newDepth, ply+1, true, threadID); + // Step 15. Full depth search + if (doFullDepthSearch) + { + value = newDepth < ONE_PLY ? -qsearch(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO, ply+1) + : - search(pos, ss+1, -(alpha+1), -alpha, newDepth, ply+1); + + // Step extra. pv search (only in PV nodes) + // Search only for possible new PV nodes, if instead value >= beta then + // parent node fails low with value <= alpha and tries another move. + if (PvNode && value > alpha && value < beta) + value = newDepth < ONE_PLY ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO, ply+1) + : - search(pos, ss+1, -beta, -alpha, newDepth, ply+1); + } } // Step 16. Undo move @@ -1530,52 +1333,53 @@ namespace { if (value > bestValue) { bestValue = value; - if (value >= beta) - update_pv(ss, ply); + if (value > alpha) + { + if (PvNode && value < beta) // We want always alpha < beta + alpha = value; + + if (value == value_mate_in(ply + 1)) + ss->mateKiller = move; - if (value == value_mate_in(ply + 1)) - ss[ply].mateKiller = move; + ss->bestMove = move; + } } // Step 18. Check for split - if ( TM.active_threads() > 1 + if ( depth >= MinimumSplitDepth + && ThreadsMgr.active_threads() > 1 && bestValue < beta - && depth >= MinimumSplitDepth - && Iteration <= 99 - && TM.available_thread_exists(threadID) + && ThreadsMgr.available_thread_exists(threadID) && !AbortSearch - && !TM.thread_should_stop(threadID) - && TM.split(pos, ss, ply, NULL, beta, &bestValue, - depth, mateThreat, &moveCount, &mp, threadID, false)) - break; + && !ThreadsMgr.thread_should_stop(threadID) + && Iteration <= 99) + ThreadsMgr.split(pos, ss, ply, &alpha, beta, &bestValue, depth, + threatMove, mateThreat, &moveCount, &mp, PvNode); } // Step 19. Check for mate and stalemate - // All legal moves have been searched and if there were + // 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. + // If one move was excluded return fail low score. if (!moveCount) - return excludedMove ? beta - 1 : (pos.is_check() ? value_mated_in(ply) : VALUE_DRAW); + return excludedMove ? oldAlpha : isCheck ? value_mated_in(ply) : VALUE_DRAW; // Step 20. Update tables // If the search is not aborted, update the transposition table, // history counters, and killer moves. - if (AbortSearch || TM.thread_should_stop(threadID)) + if (AbortSearch || ThreadsMgr.thread_should_stop(threadID)) return bestValue; - if (bestValue < beta) - TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_UPPER, depth, MOVE_NONE); - else + ValueType vt = (bestValue <= oldAlpha ? VALUE_TYPE_UPPER : bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT); + move = (bestValue <= oldAlpha ? MOVE_NONE : ss->bestMove); + TT.store(posKey, value_to_tt(bestValue, ply), vt, depth, move, ss->eval, margins[pos.side_to_move()]); + + // Update killers and history only for non capture moves that fails high + if ( bestValue >= beta + && !pos.move_is_capture_or_promotion(move)) { - TM.incrementBetaCounter(pos.side_to_move(), depth, threadID); - move = ss[ply].pv[ply]; - TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, move); - if (!pos.move_is_capture_or_promotion(move)) - { update_history(pos, move, depth, movesSearched, moveCount); - update_killers(move, ss[ply]); - } - + update_killers(move, ss); } assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); @@ -1586,35 +1390,30 @@ namespace { // qsearch() is the quiescence search function, which is called by the main // search function when the remaining depth is zero (or, to be more precise, - // less than OnePly). + // less than ONE_PLY). - Value qsearch(Position& pos, SearchStack ss[], Value alpha, Value beta, - Depth depth, int ply, int threadID) { + template + Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int ply) { assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE); assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE); + assert(PvNode || alpha == beta - 1); assert(depth <= 0); - assert(ply >= 0 && ply < PLY_MAX); - assert(threadID >= 0 && threadID < TM.active_threads()); + assert(ply > 0 && ply < PLY_MAX); + assert(pos.thread() >= 0 && pos.thread() < ThreadsMgr.active_threads()); - EvalInfo ei; + Value margins[2]; StateInfo st; Move ttMove, move; - Value staticValue, bestValue, value, futilityBase, futilityValue; - bool isCheck, enoughMaterial, moveIsCheck, evasionPrunable; - const TTEntry* tte = NULL; - int moveCount = 0; - bool pvNode = (beta - alpha != 1); + Value bestValue, value, futilityValue, futilityBase; + bool isCheck, deepChecks, enoughMaterial, moveIsCheck, evasionPrunable; + const TTEntry* tte; Value oldAlpha = alpha; - // Initialize, and make an early exit in case of an aborted search, - // an instant draw, maximum ply reached, etc. - init_node(ss, ply, threadID); - - // After init_node() that calls poll() - if (AbortSearch || TM.thread_should_stop(threadID)) - return Value(0); + ThreadsMgr.incrementNodeCounter(pos.thread()); + ss->bestMove = ss->currentMove = MOVE_NONE; + // Check for an instant draw or maximum ply reached if (pos.is_draw() || ply >= PLY_MAX - 1) return VALUE_DRAW; @@ -1623,11 +1422,9 @@ namespace { tte = TT.retrieve(pos.get_key()); ttMove = (tte ? tte->move() : MOVE_NONE); - if (!pvNode && tte && ok_to_use_TT(tte, depth, beta, ply)) + if (!PvNode && tte && ok_to_use_TT(tte, depth, beta, ply)) { - assert(tte->type() != VALUE_TYPE_EVAL); - - ss[ply].currentMove = ttMove; // Can be MOVE_NONE + ss->bestMove = ttMove; // Can be MOVE_NONE return value_from_tt(tte->value(), ply); } @@ -1635,48 +1432,54 @@ namespace { // Evaluate the position statically if (isCheck) - staticValue = -VALUE_INFINITE; - else if (tte && (tte->type() & VALUE_TYPE_EVAL)) - staticValue = value_from_tt(tte->value(), ply); - else - staticValue = evaluate(pos, ei, threadID); - - if (!isCheck) { - ss[ply].eval = staticValue; - update_gains(pos, ss[ply - 1].currentMove, ss[ply - 1].eval, ss[ply].eval); + bestValue = futilityBase = -VALUE_INFINITE; + ss->eval = VALUE_NONE; + deepChecks = enoughMaterial = false; } + else + { + if (tte) + { + assert(tte->static_value() != VALUE_NONE); - // Initialize "stand pat score", and return it immediately if it is - // at least beta. - bestValue = staticValue; + margins[pos.side_to_move()] = tte->static_value_margin(); + bestValue = tte->static_value(); + } + else + bestValue = evaluate(pos, margins); - if (bestValue >= beta) - { - // Store the score to avoid a future costly evaluation() call - if (!isCheck && !tte && ei.futilityMargin[pos.side_to_move()] == 0) - TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EV_LO, Depth(-127*OnePly), MOVE_NONE); + ss->eval = bestValue; + update_gains(pos, (ss-1)->currentMove, (ss-1)->eval, ss->eval); - return bestValue; - } + // Stand pat. Return immediately if static value is at least beta + if (bestValue >= beta) + { + if (!tte) + TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, DEPTH_NONE, MOVE_NONE, ss->eval, margins[pos.side_to_move()]); + + return bestValue; + } - if (bestValue > alpha) - alpha = bestValue; + if (PvNode && bestValue > alpha) + alpha = bestValue; - // If we are near beta then try to get a cutoff pushing checks a bit further - bool deepChecks = depth == -OnePly && staticValue >= beta - PawnValueMidgame / 8; + // If we are near beta then try to get a cutoff pushing checks a bit further + deepChecks = (depth == -ONE_PLY && bestValue >= beta - PawnValueMidgame / 8); + + // Futility pruning parameters, not needed when in check + futilityBase = bestValue + FutilityMarginQS + margins[pos.side_to_move()]; + enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame; + } // Initialize a MovePicker object for the current position, and prepare // to search the moves. Because the depth is <= 0 here, only captures, - // queen promotions and checks (only if depth == 0 or depth == -OnePly + // queen promotions and checks (only if depth == 0 or depth == -ONE_PLY // and we are near beta) will be generated. - MovePicker mp = MovePicker(pos, ttMove, deepChecks ? Depth(0) : depth, H); + MovePicker mp = MovePicker(pos, ttMove, deepChecks ? DEPTH_ZERO : depth, H); CheckInfo ci(pos); - enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame; - futilityBase = staticValue + FutilityMarginQS + ei.futilityMargin[pos.side_to_move()]; - // Loop through the moves until no moves remain or a beta cutoff - // occurs. + // Loop through the moves until no moves remain or a beta cutoff occurs while ( alpha < beta && (move = mp.get_next_move()) != MOVE_NONE) { @@ -1684,22 +1487,18 @@ namespace { moveIsCheck = pos.move_is_check(move, ci); - // Update current move - moveCount++; - ss[ply].currentMove = move; - // Futility pruning - if ( enoughMaterial + if ( !PvNode && !isCheck - && !pvNode && !moveIsCheck && 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)) - + (move_is_ep(move) ? PawnValueEndgame : Value(0)); + + (move_is_ep(move) ? PawnValueEndgame : VALUE_ZERO); if (futilityValue < alpha) { @@ -1711,22 +1510,25 @@ namespace { // Detect blocking evasions that are candidate to be pruned evasionPrunable = isCheck - && bestValue != -VALUE_INFINITE + && bestValue > value_mated_in(PLY_MAX) && !pos.move_is_capture(move) && pos.type_of_piece_on(move_from(move)) != KING && !pos.can_castle(pos.side_to_move()); // Don't search moves with negative SEE values - if ( (!isCheck || evasionPrunable) - && !pvNode + if ( !PvNode + && (!isCheck || evasionPrunable) && move != ttMove && !move_is_promotion(move) && pos.see_sign(move) < 0) continue; + // Update current move + ss->currentMove = move; + // Make and search the move pos.do_move(move, st, ci, moveIsCheck); - value = -qsearch(pos, ss, -beta, -alpha, depth-OnePly, ply+1, threadID); + value = -qsearch(pos, ss+1, -beta, -alpha, depth-ONE_PLY, ply+1); pos.undo_move(move); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); @@ -1738,36 +1540,25 @@ namespace { if (value > alpha) { alpha = value; - update_pv(ss, ply); + ss->bestMove = move; } } } // All legal moves have been searched. A special case: If we're in check // and no legal moves were found, it is checkmate. - if (!moveCount && pos.is_check()) // Mate! + if (isCheck && bestValue == -VALUE_INFINITE) return value_mated_in(ply); // Update transposition table - Depth d = (depth == Depth(0) ? Depth(0) : Depth(-1)); - if (bestValue <= oldAlpha) - { - // If bestValue isn't changed it means it is still the static evaluation - // of the node, so keep this info to avoid a future evaluation() call. - ValueType type = (bestValue == staticValue && !ei.futilityMargin[pos.side_to_move()] ? VALUE_TYPE_EV_UP : VALUE_TYPE_UPPER); - TT.store(pos.get_key(), value_to_tt(bestValue, ply), type, d, MOVE_NONE); - } - else if (bestValue >= beta) - { - move = ss[ply].pv[ply]; - TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, d, move); + Depth d = (depth == DEPTH_ZERO ? DEPTH_ZERO : DEPTH_ZERO - ONE_PLY); + ValueType vt = (bestValue <= oldAlpha ? VALUE_TYPE_UPPER : bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT); + TT.store(pos.get_key(), value_to_tt(bestValue, ply), vt, d, ss->bestMove, ss->eval, margins[pos.side_to_move()]); - // Update killers only for good checking moves - if (!pos.move_is_capture_or_promotion(move)) - update_killers(move, ss[ply]); - } - else - TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EXACT, d, ss[ply].pv[ply]); + // Update killers only for checking moves that fails high + if ( bestValue >= beta + && !pos.move_is_capture_or_promotion(ss->bestMove)) + update_killers(ss->bestMove, ss); assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); @@ -1783,22 +1574,24 @@ namespace { // also don't need to store anything to the hash table here: This is taken // care of after we return from the split point. + template void sp_search(SplitPoint* sp, int threadID) { - assert(threadID >= 0 && threadID < TM.active_threads()); - assert(TM.active_threads() > 1); + assert(threadID >= 0 && threadID < ThreadsMgr.active_threads()); + assert(ThreadsMgr.active_threads() > 1); StateInfo st; Move move; Depth ext, newDepth; - Value value, futilityValueScaled; + Value value; + Value futilityValueScaled; // NonPV specific bool isCheck, moveIsCheck, captureOrPromotion, dangerous; int moveCount; value = -VALUE_INFINITE; - Position pos(*sp->pos); + Position pos(*sp->pos, threadID); CheckInfo ci(pos); - SearchStack* ss = sp->sstack[threadID]; + SearchStack* ss = sp->sstack[threadID] + 1; isCheck = pos.is_check(); // Step 10. Loop through moves @@ -1806,10 +1599,10 @@ namespace { lock_grab(&(sp->lock)); while ( sp->bestValue < sp->beta - && !TM.thread_should_stop(threadID) - && (move = sp->mp->get_next_move()) != MOVE_NONE) + && (move = sp->mp->get_next_move()) != MOVE_NONE + && !ThreadsMgr.thread_should_stop(threadID)) { - moveCount = ++sp->moves; + moveCount = ++sp->moveCount; lock_release(&(sp->lock)); assert(move_is_ok(move)); @@ -1818,21 +1611,22 @@ namespace { captureOrPromotion = pos.move_is_capture_or_promotion(move); // Step 11. Decide the new search depth - ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, false, sp->mateThreat, &dangerous); - newDepth = sp->depth - OnePly + ext; + ext = extension(pos, move, captureOrPromotion, moveIsCheck, false, sp->mateThreat, &dangerous); + newDepth = sp->depth - ONE_PLY + ext; // Update current move - ss[sp->ply].currentMove = move; + ss->currentMove = move; - // Step 12. Futility pruning - if ( !isCheck - && !dangerous + // Step 12. Futility pruning (is omitted in PV nodes) + if ( !PvNode && !captureOrPromotion + && !isCheck + && !dangerous && !move_is_castle(move)) { // Move count based pruning if ( moveCount >= futility_move_count(sp->depth) - && ok_to_prune(pos, move, ss[sp->ply].threatMove) + && !(sp->threatMove && connected_threat(pos, move, sp->threatMove)) && sp->bestValue > value_mated_in(PLY_MAX)) { lock_grab(&(sp->lock)); @@ -1840,9 +1634,9 @@ namespace { } // Value based pruning - Depth predictedDepth = newDepth - nonpv_reduction(sp->depth, moveCount); - futilityValueScaled = ss[sp->ply].eval + futility_margin(predictedDepth, moveCount) - + H.gain(pos.piece_on(move_from(move)), move_to(move)) + 45; + Depth predictedDepth = newDepth - reduction(sp->depth, moveCount); + futilityValueScaled = ss->eval + futility_margin(predictedDepth, moveCount) + + H.gain(pos.piece_on(move_from(move)), move_to(move)); if (futilityValueScaled < sp->beta) { @@ -1858,143 +1652,53 @@ namespace { pos.do_move(move, st, ci, moveIsCheck); // Step 14. Reduced search - // if the move fails high will be re-searched at full depth. + // If the move fails high will be re-searched at full depth. bool doFullDepthSearch = true; - if ( !dangerous - && !captureOrPromotion + if ( !captureOrPromotion + && !dangerous && !move_is_castle(move) - && !move_is_killer(move, ss[sp->ply])) + && !move_is_killer(move, ss)) { - ss[sp->ply].reduction = nonpv_reduction(sp->depth, moveCount); - if (ss[sp->ply].reduction) + ss->reduction = reduction(sp->depth, moveCount); + if (ss->reduction) { - value = -search(pos, ss, -(sp->beta-1), newDepth-ss[sp->ply].reduction, sp->ply+1, true, threadID); - doFullDepthSearch = (value >= sp->beta && !TM.thread_should_stop(threadID)); - } - } - - // Step 15. Full depth search - if (doFullDepthSearch) - { - ss[sp->ply].reduction = Depth(0); - value = -search(pos, ss, -(sp->beta - 1), newDepth, sp->ply+1, true, threadID); - } - - // Step 16. Undo move - pos.undo_move(move); - - assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); - - // Step 17. Check for new best move - lock_grab(&(sp->lock)); + Value localAlpha = sp->alpha; + Depth d = newDepth - ss->reduction; + value = d < ONE_PLY ? -qsearch(pos, ss+1, -(localAlpha+1), -localAlpha, DEPTH_ZERO, sp->ply+1) + : - search(pos, ss+1, -(localAlpha+1), -localAlpha, d, sp->ply+1); - if (value > sp->bestValue && !TM.thread_should_stop(threadID)) - { - sp->bestValue = value; - if (sp->bestValue >= sp->beta) - { - sp->stopRequest = true; - sp_update_pv(sp->parentSstack, ss, sp->ply); + doFullDepthSearch = (value > localAlpha); } - } - } - - /* Here we have the lock still grabbed */ - - sp->slaves[threadID] = 0; - sp->cpus--; - - lock_release(&(sp->lock)); - } - - - // sp_search_pv() is used to search from a PV split point. This function - // is called by each thread working at the split point. It is similar to - // the normal search_pv() function, but simpler. Because we have already - // probed the hash table and searched the first move before splitting, we - // don't have to repeat all this work in sp_search_pv(). We also don't - // need to store anything to the hash table here: This is taken care of - // after we return from the split point. - - void sp_search_pv(SplitPoint* sp, int threadID) { - - assert(threadID >= 0 && threadID < TM.active_threads()); - assert(TM.active_threads() > 1); - - StateInfo st; - Move move; - Depth ext, newDepth; - Value value; - bool moveIsCheck, captureOrPromotion, dangerous; - int moveCount; - value = -VALUE_INFINITE; - - Position pos(*sp->pos); - CheckInfo ci(pos); - SearchStack* ss = sp->sstack[threadID]; - - // Step 10. Loop through moves - // Loop through all legal moves until no moves remain or a beta cutoff occurs - lock_grab(&(sp->lock)); - - while ( sp->alpha < sp->beta - && !TM.thread_should_stop(threadID) - && (move = sp->mp->get_next_move()) != MOVE_NONE) - { - moveCount = ++sp->moves; - lock_release(&(sp->lock)); - - assert(move_is_ok(move)); - - moveIsCheck = pos.move_is_check(move, ci); - captureOrPromotion = pos.move_is_capture_or_promotion(move); - - // Step 11. Decide the new search depth - ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, false, sp->mateThreat, &dangerous); - newDepth = sp->depth - OnePly + ext; - - // Update current move - ss[sp->ply].currentMove = move; - - // Step 12. Futility pruning (is omitted in PV nodes) - - // Step 13. Make the move - pos.do_move(move, st, ci, moveIsCheck); - // Step 14. Reduced search - // if the move fails high will be re-searched at full depth. - bool doFullDepthSearch = true; - - if ( !dangerous - && !captureOrPromotion - && !move_is_castle(move) - && !move_is_killer(move, ss[sp->ply])) - { - ss[sp->ply].reduction = pv_reduction(sp->depth, moveCount); - if (ss[sp->ply].reduction) + // The move failed high, but if reduction is very big we could + // face a false positive, retry with a less aggressive reduction, + // if the move fails high again then go with full depth search. + if (doFullDepthSearch && ss->reduction > 2 * ONE_PLY) { + assert(newDepth - ONE_PLY >= ONE_PLY); + + ss->reduction = ONE_PLY; Value localAlpha = sp->alpha; - value = -search(pos, ss, -localAlpha, newDepth-ss[sp->ply].reduction, sp->ply+1, true, threadID); - doFullDepthSearch = (value > localAlpha && !TM.thread_should_stop(threadID)); + value = -search(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth-ss->reduction, sp->ply+1); + doFullDepthSearch = (value > localAlpha); } + ss->reduction = DEPTH_ZERO; // Restore original reduction } // Step 15. Full depth search if (doFullDepthSearch) { Value localAlpha = sp->alpha; - ss[sp->ply].reduction = Depth(0); - value = -search(pos, ss, -localAlpha, newDepth, sp->ply+1, true, threadID); - - if (value > localAlpha && value < sp->beta && !TM.thread_should_stop(threadID)) - { - // If another thread has failed high then sp->alpha has been increased - // to be higher or equal then beta, if so, avoid to start a PV search. - localAlpha = sp->alpha; - if (localAlpha < sp->beta) - value = -search_pv(pos, ss, -sp->beta, -localAlpha, newDepth, sp->ply+1, threadID); - } + value = newDepth < ONE_PLY ? -qsearch(pos, ss+1, -(localAlpha+1), -localAlpha, DEPTH_ZERO, sp->ply+1) + : - search(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth, sp->ply+1); + + // Step extra. pv search (only in PV nodes) + // Search only for possible new PV nodes, if instead value >= beta then + // parent node fails low with value <= alpha and tries another move. + if (PvNode && value > localAlpha && value < sp->beta) + value = newDepth < ONE_PLY ? -qsearch(pos, ss+1, -sp->beta, -sp->alpha, DEPTH_ZERO, sp->ply+1) + : - search(pos, ss+1, -sp->beta, -sp->alpha, newDepth, sp->ply+1); } // Step 16. Undo move @@ -2005,20 +1709,19 @@ namespace { // Step 17. Check for new best move lock_grab(&(sp->lock)); - if (value > sp->bestValue && !TM.thread_should_stop(threadID)) + if (value > sp->bestValue && !ThreadsMgr.thread_should_stop(threadID)) { sp->bestValue = value; - if (value > sp->alpha) + + if (sp->bestValue > sp->alpha) { - // Ask threads to stop before to modify sp->alpha - if (value >= sp->beta) + if (!PvNode || value >= sp->beta) sp->stopRequest = true; - sp->alpha = value; + if (PvNode && value < sp->beta) // This guarantees that always: sp->alpha < sp->beta + sp->alpha = value; - sp_update_pv(sp->parentSstack, ss, sp->ply); - if (value == value_mate_in(sp->ply + 1)) - ss[sp->ply].mateKiller = move; + sp->parentSstack->bestMove = ss->bestMove = move; } } } @@ -2026,77 +1729,11 @@ namespace { /* Here we have the lock still grabbed */ sp->slaves[threadID] = 0; - sp->cpus--; lock_release(&(sp->lock)); } - // init_node() is called at the beginning of all the search functions - // (search(), search_pv(), qsearch(), and so on) and initializes the - // search stack object corresponding to the current node. Once every - // NodesBetweenPolls nodes, init_node() also calls poll(), which polls - // for user input and checks whether it is time to stop the search. - - void init_node(SearchStack ss[], int ply, int threadID) { - - assert(ply >= 0 && ply < PLY_MAX); - assert(threadID >= 0 && threadID < TM.active_threads()); - - TM.incrementNodeCounter(threadID); - - if (threadID == 0) - { - NodesSincePoll++; - if (NodesSincePoll >= NodesBetweenPolls) - { - poll(ss, ply); - NodesSincePoll = 0; - } - } - ss[ply].init(ply); - ss[ply + 2].initKillers(); - } - - - // update_pv() is called whenever a search returns a value > alpha. - // It updates the PV in the SearchStack object corresponding to the - // current node. - - void update_pv(SearchStack ss[], int ply) { - - assert(ply >= 0 && ply < PLY_MAX); - - int p; - - ss[ply].pv[ply] = ss[ply].currentMove; - - for (p = ply + 1; ss[ply + 1].pv[p] != MOVE_NONE; p++) - ss[ply].pv[p] = ss[ply + 1].pv[p]; - - ss[ply].pv[p] = MOVE_NONE; - } - - - // sp_update_pv() is a variant of update_pv for use at split points. The - // difference between the two functions is that sp_update_pv also updates - // the PV at the parent node. - - void sp_update_pv(SearchStack* pss, SearchStack ss[], int ply) { - - assert(ply >= 0 && ply < PLY_MAX); - - int p; - - ss[ply].pv[ply] = pss[ply].pv[ply] = ss[ply].currentMove; - - for (p = ply + 1; ss[ply + 1].pv[p] != MOVE_NONE; p++) - ss[ply].pv[p] = pss[ply].pv[p] = ss[ply + 1].pv[p]; - - ss[ply].pv[p] = pss[ply].pv[p] = MOVE_NONE; - } - - // connected_moves() tests whether two moves are 'connected' in the sense // that the first move somehow made the second move possible (for instance // if the moving piece is the same in both moves). The first move is assumed @@ -2153,8 +1790,8 @@ namespace { } - // value_is_mate() checks if the given value is a mate one - // eventually compensated for the ply. + // value_is_mate() checks if the given value is a mate one eventually + // compensated for the ply. bool value_is_mate(Value value) { @@ -2165,15 +1802,43 @@ namespace { } - // move_is_killer() checks if the given move is among the - // killer moves of that ply. + // value_to_tt() adjusts a mate score from "plies to mate from the root" to + // "plies to mate from the current ply". Non-mate scores are unchanged. + // The function is called before storing a value to the transposition table. - bool move_is_killer(Move m, const SearchStack& ss) { + Value value_to_tt(Value v, int ply) { - const Move* k = ss.killers; - for (int i = 0; i < KILLER_MAX; i++, k++) - if (*k == m) - return true; + if (v >= value_mate_in(PLY_MAX)) + return v + ply; + + if (v <= value_mated_in(PLY_MAX)) + return v - ply; + + return v; + } + + + // value_from_tt() is the inverse of value_to_tt(): It adjusts a mate score from + // the transposition table to a mate score corrected for the current ply. + + Value value_from_tt(Value v, int ply) { + + if (v >= value_mate_in(PLY_MAX)) + return v - ply; + + if (v <= value_mated_in(PLY_MAX)) + return v + ply; + + return v; + } + + + // move_is_killer() checks if the given move is among the killer moves + + bool move_is_killer(Move m, SearchStack* ss) { + + if (ss->killers[0] == m || ss->killers[1] == m) + return true; return false; } @@ -2185,25 +1850,25 @@ namespace { // any case are marked as 'dangerous'. Note that also if a move is not // extended, as example because the corresponding UCI option is set to zero, // the move is marked as 'dangerous' so, at least, we avoid to prune it. - - Depth extension(const Position& pos, Move m, bool pvNode, bool captureOrPromotion, - bool moveIsCheck, bool singleEvasion, bool mateThreat, bool* dangerous) { + template + Depth extension(const Position& pos, Move m, bool captureOrPromotion, bool moveIsCheck, + bool singleEvasion, bool mateThreat, bool* dangerous) { assert(m != MOVE_NONE); - Depth result = Depth(0); + Depth result = DEPTH_ZERO; *dangerous = moveIsCheck | singleEvasion | mateThreat; if (*dangerous) { - if (moveIsCheck) - result += CheckExtension[pvNode]; + if (moveIsCheck && pos.see_sign(m) >= 0) + result += CheckExtension[PvNode]; if (singleEvasion) - result += SingleEvasionExtension[pvNode]; + result += SingleEvasionExtension[PvNode]; if (mateThreat) - result += MateThreatExtension[pvNode]; + result += MateThreatExtension[PvNode]; } if (pos.type_of_piece_on(move_from(m)) == PAWN) @@ -2211,12 +1876,12 @@ namespace { Color c = pos.side_to_move(); if (relative_rank(c, move_to(m)) == RANK_7) { - result += PawnPushTo7thExtension[pvNode]; + result += PawnPushTo7thExtension[PvNode]; *dangerous = true; } if (pos.pawn_is_passed(c, move_to(m))) { - result += PassedPawnExtension[pvNode]; + result += PassedPawnExtension[PvNode]; *dangerous = true; } } @@ -2224,59 +1889,40 @@ namespace { if ( captureOrPromotion && pos.type_of_piece_on(move_to(m)) != PAWN && ( pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) - - pos.midgame_value_of_piece_on(move_to(m)) == Value(0)) + - pos.midgame_value_of_piece_on(move_to(m)) == VALUE_ZERO) && !move_is_promotion(m) && !move_is_ep(m)) { - result += PawnEndgameExtension[pvNode]; + result += PawnEndgameExtension[PvNode]; *dangerous = true; } - if ( pvNode + if ( PvNode && captureOrPromotion && pos.type_of_piece_on(move_to(m)) != PAWN && pos.see_sign(m) >= 0) { - result += OnePly/2; + result += ONE_PLY / 2; *dangerous = true; } - return Min(result, OnePly); + return Min(result, ONE_PLY); } - // ok_to_do_nullmove() looks at the current position and decides whether - // doing a 'null move' should be allowed. In order to avoid zugzwang - // problems, null moves are not allowed when the side to move has very - // little material left. Currently, the test is a bit too simple: Null - // moves are avoided only when the side to move has only pawns left. - // It's probably a good idea to avoid null moves in at least some more - // complicated endgames, e.g. KQ vs KR. FIXME + // connected_threat() tests whether it is safe to forward prune a move or if + // is somehow coonected to the threat move returned by null search. - bool ok_to_do_nullmove(const Position& pos) { - - return pos.non_pawn_material(pos.side_to_move()) != Value(0); - } - - - // ok_to_prune() tests whether it is safe to forward prune a move. Only - // non-tactical moves late in the move list close to the leaves are - // candidates for pruning. - - bool ok_to_prune(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_NONE || move_is_ok(threat)); + assert(threat && move_is_ok(threat)); assert(!pos.move_is_check(m)); assert(!pos.move_is_capture_or_promotion(m)); assert(!pos.move_is_passed_pawn_push(m)); Square mfrom, mto, tfrom, tto; - // Prune if there isn't any threat move - if (threat == MOVE_NONE) - return true; - mfrom = move_from(m); mto = move_to(m); tfrom = move_from(threat); @@ -2284,7 +1930,7 @@ namespace { // Case 1: Don't prune moves which move the threatened piece if (mfrom == tto) - return false; + 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. @@ -2292,16 +1938,16 @@ namespace { && ( pos.midgame_value_of_piece_on(tfrom) >= pos.midgame_value_of_piece_on(tto) || pos.type_of_piece_on(tfrom) == KING) && pos.move_attacks_square(m, tto)) - return false; + return true; // Case 3: If the moving piece in the threatened move is a slider, don't // prune safe moves which block its ray. if ( piece_is_slider(pos.piece_on(tfrom)) && bit_is_set(squares_between(tfrom, tto), mto) && pos.see_sign(m) >= 0) - return false; + return true; - return true; + return false; } @@ -2316,8 +1962,8 @@ namespace { || v >= Max(value_mate_in(PLY_MAX), beta) || v < Min(value_mated_in(PLY_MAX), beta)) - && ( (is_lower_bound(tte->type()) && v >= beta) - || (is_upper_bound(tte->type()) && v < beta)); + && ( ((tte->type() & VALUE_TYPE_LOWER) && v >= beta) + || ((tte->type() & VALUE_TYPE_UPPER) && v < beta)); } @@ -2326,13 +1972,12 @@ namespace { Value refine_eval(const TTEntry* tte, Value defaultEval, int ply) { - if (!tte) - return defaultEval; + assert(tte); Value v = value_from_tt(tte->value(), ply); - if ( (is_lower_bound(tte->type()) && v >= defaultEval) - || (is_upper_bound(tte->type()) && v < defaultEval)) + if ( ((tte->type() & VALUE_TYPE_LOWER) && v >= defaultEval) + || ((tte->type() & VALUE_TYPE_UPPER) && v < defaultEval)) return v; return defaultEval; @@ -2364,15 +2009,13 @@ namespace { // update_killers() add a good move that produced a beta-cutoff // among the killer moves of that ply. - void update_killers(Move m, SearchStack& ss) { + void update_killers(Move m, SearchStack* ss) { - if (m == ss.killers[0]) + if (m == ss->killers[0]) return; - for (int i = KILLER_MAX - 1; i > 0; i--) - ss.killers[i] = ss.killers[i - 1]; - - ss.killers[0] = m; + ss->killers[1] = ss->killers[0]; + ss->killers[0] = m; } @@ -2384,9 +2027,8 @@ namespace { if ( m != MOVE_NULL && before != VALUE_NONE && after != VALUE_NONE - && pos.captured_piece() == NO_PIECE_TYPE - && !move_is_castle(m) - && !move_is_promotion(m)) + && 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)); } @@ -2400,12 +2042,26 @@ namespace { } + // value_to_uci() converts a value to a string suitable for use with the UCI protocol + + std::string value_to_uci(Value v) { + + std::stringstream s; + + if (abs(v) < VALUE_MATE - PLY_MAX * ONE_PLY) + s << "cp " << int(v) * 100 / int(PawnValueMidgame); // Scale to pawn = 100 + else + s << "mate " << (v > 0 ? (VALUE_MATE - v + 1) / 2 : -(VALUE_MATE + v) / 2 ); + + return s.str(); + } + // nps() computes the current nodes/second count. int nps() { int t = current_search_time(); - return (t > 0 ? int((TM.nodes_searched() * 1000) / t) : 0); + return (t > 0 ? int((ThreadsMgr.nodes_searched() * 1000) / t) : 0); } @@ -2413,7 +2069,7 @@ namespace { // looks at the time consumed so far and decides if it's time to abort the // search. - void poll(SearchStack ss[], int ply) { + void poll() { static int lastInfoTime; int t = current_search_time(); @@ -2462,18 +2118,8 @@ namespace { if (dbg_show_hit_rate) dbg_print_hit_rate(); - cout << "info nodes " << TM.nodes_searched() << " nps " << nps() - << " time " << t << " hashfull " << TT.full() << endl; - - // We only support current line printing in single thread mode - if (ShowCurrentLine && TM.active_threads() == 1) - { - cout << "info currline"; - for (int p = 0; p < ply; p++) - cout << " " << ss[p].currentMove; - - cout << endl; - } + cout << "info nodes " << ThreadsMgr.nodes_searched() << " nps " << nps() + << " time " << t << endl; } // Should we stop the search? @@ -2482,14 +2128,14 @@ namespace { bool stillAtFirstMove = FirstRootMove && !AspirationFailLow - && t > MaxSearchTime + ExtraSearchTime; + && t > TimeMgr.available_time(); - bool noMoreTime = t > AbsoluteMaxSearchTime + bool noMoreTime = t > TimeMgr.maximum_time() || stillAtFirstMove; if ( (Iteration >= 3 && UseTimeManagement && noMoreTime) || (ExactMaxTime && t >= ExactMaxTime) - || (Iteration >= 3 && MaxNodes && TM.nodes_searched() >= MaxNodes)) + || (Iteration >= 3 && MaxNodes && ThreadsMgr.nodes_searched() >= MaxNodes)) AbortSearch = true; } @@ -2505,9 +2151,9 @@ namespace { bool stillAtFirstMove = FirstRootMove && !AspirationFailLow - && t > MaxSearchTime + ExtraSearchTime; + && t > TimeMgr.available_time(); - bool noMoreTime = t > AbsoluteMaxSearchTime + bool noMoreTime = t > TimeMgr.maximum_time() || stillAtFirstMove; if (Iteration >= 3 && UseTimeManagement && (noMoreTime || StopOnPonderhit)) @@ -2515,14 +2161,19 @@ namespace { } - // init_ss_array() does a fast reset of the first entries of a SearchStack array + // init_ss_array() does a fast reset of the first entries of a SearchStack + // array and of all the excludedMove and skipNullMove entries. - void init_ss_array(SearchStack ss[]) { + void init_ss_array(SearchStack* ss, int size) { - for (int i = 0; i < 3; i++) + for (int i = 0; i < size; i++, ss++) { - ss[i].init(i); - ss[i].initKillers(); + ss->excludedMove = MOVE_NONE; + ss->skipNullMove = false; + ss->reduction = DEPTH_ZERO; + + if (i < 3) + ss->killers[0] = ss->killers[1] = ss->mateKiller = MOVE_NONE; } } @@ -2557,30 +2208,84 @@ namespace { // print_pv_info() prints to standard output and eventually to log file information on // the current PV line. It is called at each iteration or after a new pv is found. - void print_pv_info(const Position& pos, SearchStack ss[], Value alpha, Value beta, Value value) { + void print_pv_info(const Position& pos, Move pv[], Value alpha, Value beta, Value value) { cout << "info depth " << Iteration - << " score " << value_to_string(value) - << ((value >= beta) ? " lowerbound" : - ((value <= alpha)? " upperbound" : "")) + << " score " << value_to_uci(value) + << (value >= beta ? " lowerbound" : value <= alpha ? " upperbound" : "") << " time " << current_search_time() - << " nodes " << TM.nodes_searched() + << " nodes " << ThreadsMgr.nodes_searched() << " nps " << nps() << " pv "; - for (int j = 0; ss[0].pv[j] != MOVE_NONE && j < PLY_MAX; j++) - cout << ss[0].pv[j] << " "; + for (Move* m = pv; *m != MOVE_NONE; m++) + cout << *m << " "; cout << endl; if (UseLogFile) { - ValueType type = (value >= beta ? VALUE_TYPE_LOWER - : (value <= alpha ? VALUE_TYPE_UPPER : VALUE_TYPE_EXACT)); + ValueType t = value >= beta ? VALUE_TYPE_LOWER : + value <= alpha ? VALUE_TYPE_UPPER : VALUE_TYPE_EXACT; LogFile << pretty_pv(pos, current_search_time(), Iteration, - TM.nodes_searched(), value, type, ss[0].pv) << endl; + ThreadsMgr.nodes_searched(), value, t, pv) << endl; + } + } + + + // insert_pv_in_tt() is called at the end of a search iteration, and inserts + // the PV back into the TT. This makes sure the old PV moves are searched + // first, even if the old TT entries have been overwritten. + + void insert_pv_in_tt(const Position& pos, Move pv[]) { + + StateInfo st; + TTEntry* tte; + Position p(pos, pos.thread()); + Value margins[2]; + Value v; + + for (int i = 0; pv[i] != MOVE_NONE; i++) + { + tte = TT.retrieve(p.get_key()); + if (!tte || tte->move() != pv[i]) + { + v = (p.is_check() ? VALUE_NONE : evaluate(p, margins)); + TT.store(p.get_key(), VALUE_NONE, VALUE_TYPE_NONE, DEPTH_NONE, pv[i], v, margins[pos.side_to_move()]); + } + p.do_move(pv[i], st); + } + } + + + // extract_pv_from_tt() builds a PV by adding moves from the transposition table. + // We consider also failing high nodes and not only VALUE_TYPE_EXACT nodes. This + // allow to always have a ponder move even when we fail high at root and also a + // long PV to print that is important for position analysis. + + void extract_pv_from_tt(const Position& pos, Move bestMove, Move pv[]) { + + StateInfo st; + TTEntry* tte; + Position p(pos, pos.thread()); + int ply = 0; + + assert(bestMove != MOVE_NONE); + + pv[ply] = bestMove; + p.do_move(pv[ply++], st); + + while ( (tte = TT.retrieve(p.get_key())) != NULL + && tte->move() != MOVE_NONE + && move_is_legal(p, tte->move()) + && ply < PLY_MAX + && (!p.is_draw() || ply < 2)) + { + pv[ply] = tte->move(); + p.do_move(pv[ply++], st); } + pv[ply] = MOVE_NONE; } @@ -2593,7 +2298,7 @@ namespace { void* init_thread(void *threadID) { - TM.idle_loop(*(int*)threadID, NULL); + ThreadsMgr.idle_loop(*(int*)threadID, NULL); return NULL; } @@ -2601,7 +2306,7 @@ namespace { DWORD WINAPI init_thread(LPVOID threadID) { - TM.idle_loop(*(int*)threadID, NULL); + ThreadsMgr.idle_loop(*(int*)threadID, NULL); return 0; } @@ -2620,12 +2325,6 @@ namespace { threads[i].nodes = 0ULL; } - void ThreadsManager::resetBetaCounters() { - - for (int i = 0; i < MAX_THREADS; i++) - threads[i].betaCutOffs[WHITE] = threads[i].betaCutOffs[BLACK] = 0ULL; - } - int64_t ThreadsManager::nodes_searched() const { int64_t result = 0ULL; @@ -2635,22 +2334,12 @@ namespace { return result; } - void ThreadsManager::get_beta_counters(Color us, int64_t& our, int64_t& their) const { - - our = their = 0UL; - for (int i = 0; i < MAX_THREADS; i++) - { - our += threads[i].betaCutOffs[us]; - their += threads[i].betaCutOffs[opposite_color(us)]; - } - } - // idle_loop() is where the threads are parked when they have no work to do. - // The parameter "waitSp", if non-NULL, is a pointer to an active SplitPoint + // The parameter 'sp', if non-NULL, is a pointer to an active SplitPoint // object for which the current thread is the master. - void ThreadsManager::idle_loop(int threadID, SplitPoint* waitSp) { + void ThreadsManager::idle_loop(int threadID, SplitPoint* sp) { assert(threadID >= 0 && threadID < MAX_THREADS); @@ -2660,7 +2349,7 @@ namespace { // master should exit as last one. if (AllThreadsShouldExit) { - assert(!waitSp); + assert(!sp); threads[threadID].state = THREAD_TERMINATED; return; } @@ -2669,7 +2358,7 @@ namespace { // instead of wasting CPU time polling for work. while (AllThreadsShouldSleep || threadID >= ActiveThreads) { - assert(!waitSp); + assert(!sp); assert(threadID != 0); threads[threadID].state = THREAD_SLEEPING; @@ -2695,19 +2384,27 @@ namespace { threads[threadID].state = THREAD_SEARCHING; if (threads[threadID].splitPoint->pvNode) - sp_search_pv(threads[threadID].splitPoint, threadID); + sp_search(threads[threadID].splitPoint, threadID); else - sp_search(threads[threadID].splitPoint, threadID); + sp_search(threads[threadID].splitPoint, threadID); assert(threads[threadID].state == THREAD_SEARCHING); threads[threadID].state = THREAD_AVAILABLE; } - // If this thread is the master of a split point and all threads have + // 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 (waitSp != NULL && waitSp->cpus == 0) + int i = 0; + for ( ; sp && i < ActiveThreads && !sp->slaves[i]; i++) {} + + if (i == ActiveThreads) { + // Because sp->slaves[] is reset under lock protection, + // be sure sp->lock has been released before to return. + lock_grab(&(sp->lock)); + lock_release(&(sp->lock)); + assert(threads[threadID].state == THREAD_AVAILABLE); threads[threadID].state = THREAD_SEARCHING; @@ -2731,8 +2428,8 @@ namespace { #endif // Initialize global locks - lock_init(&MPLock, NULL); - lock_init(&WaitLock, NULL); + lock_init(&MPLock); + lock_init(&WaitLock); #if !defined(_MSC_VER) pthread_cond_init(&WaitCond, NULL); @@ -2741,13 +2438,10 @@ namespace { SitIdleEvent[i] = CreateEvent(0, FALSE, FALSE, 0); #endif - // Initialize SplitPointStack locks + // Initialize splitPoints[] locks for (i = 0; i < MAX_THREADS; i++) - for (int j = 0; j < ACTIVE_SPLIT_POINTS_MAX; j++) - { - SplitPointStack[i][j].parent = NULL; - lock_init(&(SplitPointStack[i][j].lock), NULL); - } + for (int j = 0; j < MAX_ACTIVE_SPLIT_POINTS; j++) + lock_init(&(threads[i].splitPoints[j].lock)); // Will be set just before program exits to properly end the threads AllThreadsShouldExit = false; @@ -2778,7 +2472,7 @@ namespace { } // Wait until the thread has finished launching and is gone to sleep - while (threads[i].state != THREAD_SLEEPING); + while (threads[i].state != THREAD_SLEEPING) {} } } @@ -2797,12 +2491,12 @@ namespace { // Wait for thread termination for (int i = 1; i < MAX_THREADS; i++) - while (threads[i].state != THREAD_TERMINATED); + while (threads[i].state != THREAD_TERMINATED) {} // Now we can safely destroy the locks for (int i = 0; i < MAX_THREADS; i++) - for (int j = 0; j < ACTIVE_SPLIT_POINTS_MAX; j++) - lock_destroy(&(SplitPointStack[i][j].lock)); + for (int j = 0; j < MAX_ACTIVE_SPLIT_POINTS; j++) + lock_destroy(&(threads[i].splitPoints[j].lock)); lock_destroy(&WaitLock); lock_destroy(&MPLock); @@ -2819,7 +2513,7 @@ namespace { SplitPoint* sp; - for (sp = threads[threadID].splitPoint; sp && !sp->stopRequest; sp = sp->parent); + for (sp = threads[threadID].splitPoint; sp && !sp->stopRequest; sp = sp->parent) {} return sp != NULL; } @@ -2855,7 +2549,7 @@ namespace { // Apply the "helpful master" concept if possible. Use localActiveSplitPoints // that is known to be > 0, instead of threads[slave].activeSplitPoints that // could have been set to 0 by another thread leading to an out of bound access. - if (SplitPointStack[slave][localActiveSplitPoints - 1].slaves[master]) + if (threads[slave].splitPoints[localActiveSplitPoints - 1].slaves[master]) return true; return false; @@ -2879,95 +2573,92 @@ namespace { // split() does the actual work of distributing the work at a node between - // several threads at PV nodes. If it does not succeed in splitting the + // several available threads. If it does not succeed in splitting the // node (because no idle threads are available, or because we have no unused - // split point objects), the function immediately returns false. If - // splitting is possible, a SplitPoint object is initialized with all the - // data that must be copied to the helper threads (the current position and - // search stack, alpha, beta, the search depth, etc.), and we tell our - // helper threads that they have been assigned work. This will cause them - // to instantly leave their idle loops and call sp_search_pv(). When all - // threads have returned from sp_search_pv (or, equivalently, when - // splitPoint->cpus becomes 0), split() returns true. - - bool ThreadsManager::split(const Position& p, SearchStack* sstck, int ply, - Value* alpha, const Value beta, Value* bestValue, - Depth depth, bool mateThreat, int* moves, MovePicker* mp, int master, bool pvNode) { - + // split point objects), the function immediately returns. If splitting is + // possible, a SplitPoint object is initialized with all the data that must be + // copied to the helper threads and we tell our helper threads that they have + // been assigned work. This will cause them to instantly leave their idle loops + // and call sp_search(). When all threads have returned from sp_search() then + // split() returns. + + template + void ThreadsManager::split(const Position& p, SearchStack* ss, int ply, Value* alpha, + const Value beta, Value* bestValue, Depth depth, Move threatMove, + bool mateThreat, int* moveCount, MovePicker* mp, bool pvNode) { assert(p.is_ok()); - assert(sstck != NULL); - assert(ply >= 0 && ply < PLY_MAX); + assert(ply > 0 && ply < PLY_MAX); assert(*bestValue >= -VALUE_INFINITE); - assert( ( pvNode && *bestValue <= *alpha) - || (!pvNode && *bestValue < beta )); - assert(!pvNode || *alpha < beta); + assert(*bestValue <= *alpha); + assert(*alpha < beta); assert(beta <= VALUE_INFINITE); - assert(depth > Depth(0)); - assert(master >= 0 && master < ActiveThreads); + assert(depth > DEPTH_ZERO); + assert(p.thread() >= 0 && p.thread() < ActiveThreads); assert(ActiveThreads > 1); - SplitPoint* splitPoint; + int i, master = p.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) - || threads[master].activeSplitPoints >= ACTIVE_SPLIT_POINTS_MAX) + || masterThread.activeSplitPoints >= MAX_ACTIVE_SPLIT_POINTS) { lock_release(&MPLock); - return false; + return; } // Pick the next available split point object from the split point stack - splitPoint = &SplitPointStack[master][threads[master].activeSplitPoints]; + SplitPoint& splitPoint = masterThread.splitPoints[masterThread.activeSplitPoints++]; // Initialize the split point object - splitPoint->parent = threads[master].splitPoint; - splitPoint->stopRequest = false; - splitPoint->ply = ply; - splitPoint->depth = depth; - splitPoint->mateThreat = mateThreat; - splitPoint->alpha = pvNode ? *alpha : beta - 1; - splitPoint->beta = beta; - splitPoint->pvNode = pvNode; - splitPoint->bestValue = *bestValue; - splitPoint->master = master; - splitPoint->mp = mp; - splitPoint->moves = *moves; - splitPoint->cpus = 1; - splitPoint->pos = &p; - splitPoint->parentSstack = sstck; - for (int i = 0; i < ActiveThreads; i++) - splitPoint->slaves[i] = 0; - - threads[master].splitPoint = splitPoint; - threads[master].activeSplitPoints++; + splitPoint.parent = masterThread.splitPoint; + splitPoint.stopRequest = false; + splitPoint.ply = ply; + splitPoint.depth = depth; + splitPoint.threatMove = threatMove; + splitPoint.mateThreat = mateThreat; + splitPoint.alpha = *alpha; + splitPoint.beta = beta; + splitPoint.pvNode = pvNode; + splitPoint.bestValue = *bestValue; + splitPoint.mp = mp; + splitPoint.moveCount = *moveCount; + splitPoint.pos = &p; + splitPoint.parentSstack = ss; + for (i = 0; i < ActiveThreads; i++) + splitPoint.slaves[i] = 0; + + masterThread.splitPoint = &splitPoint; // If we are here it means we are not available - assert(threads[master].state != THREAD_AVAILABLE); + assert(masterThread.state != THREAD_AVAILABLE); + + int workersCnt = 1; // At least the master is included // Allocate available threads setting state to THREAD_BOOKED - for (int i = 0; i < ActiveThreads && splitPoint->cpus < MaxThreadsPerSplitPoint; i++) + 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; - splitPoint->cpus++; + threads[i].splitPoint = &splitPoint; + splitPoint.slaves[i] = 1; + workersCnt++; } - assert(splitPoint->cpus > 1); + assert(Fake || workersCnt > 1); // We can release the lock because slave threads are already booked and master is not available lock_release(&MPLock); // Tell the threads that they have work to do. This will make them leave // their idle loop. But before copy search stack tail for each thread. - for (int i = 0; i < ActiveThreads; i++) - if (i == master || splitPoint->slaves[i]) + for (i = 0; i < ActiveThreads; i++) + if (i == master || splitPoint.slaves[i]) { - memcpy(splitPoint->sstack[i] + ply - 1, sstck + ply - 1, 4 * sizeof(SearchStack)); + memcpy(splitPoint.sstack[i], ss - 1, 4 * sizeof(SearchStack)); assert(i == master || threads[i].state == THREAD_BOOKED); @@ -2978,23 +2669,19 @@ namespace { // which it will instantly launch a search, because its state is // THREAD_WORKISWAITING. We send the split point as a second parameter to the // idle loop, which means that the main thread will return from the idle - // loop when all threads have finished their work at this split point - // (i.e. when splitPoint->cpus == 0). - idle_loop(master, splitPoint); + // loop when all threads have finished their work at this split point. + idle_loop(master, &splitPoint); // We have returned from the idle loop, which means that all threads are - // finished. Update alpha, beta and bestValue, and return. + // finished. Update alpha and bestValue, and return. lock_grab(&MPLock); - if (pvNode) - *alpha = splitPoint->alpha; - - *bestValue = splitPoint->bestValue; - threads[master].activeSplitPoints--; - threads[master].splitPoint = splitPoint->parent; + *alpha = splitPoint.alpha; + *bestValue = splitPoint.bestValue; + masterThread.activeSplitPoints--; + masterThread.splitPoint = splitPoint.parent; lock_release(&MPLock); - return true; } @@ -3046,6 +2733,11 @@ namespace { StateInfo st; bool includeAllMoves = (searchMoves[0] == MOVE_NONE); + // Initialize search stack + init_ss_array(ss, PLY_MAX_PLUS_2); + ss[0].currentMove = ss[0].bestMove = MOVE_NONE; + ss[0].eval = VALUE_NONE; + // Generate all legal moves MoveStack* last = generate_moves(pos, mlist); @@ -3061,10 +2753,10 @@ namespace { continue; // Find a quick score for the move - init_ss_array(ss); pos.do_move(cur->move, st); + ss[0].currentMove = cur->move; moves[count].move = cur->move; - moves[count].score = -qsearch(pos, ss, -VALUE_INFINITE, VALUE_INFINITE, Depth(0), 1, 0); + moves[count].score = -qsearch(pos, ss+1, -VALUE_INFINITE, VALUE_INFINITE, DEPTH_ZERO, 1); moves[count].pv[0] = cur->move; moves[count].pv[1] = MOVE_NONE; pos.undo_move(cur->move); @@ -3073,20 +2765,25 @@ namespace { 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. - // RootMoveList simple methods definitions - - void RootMoveList::set_move_nodes(int moveNum, int64_t nodes) { - - moves[moveNum].nodes = nodes; - moves[moveNum].cumulativeNodes += nodes; + void RootMoveList::score_moves(const Position& pos) + { + Move move; + int score = 1000; + MovePicker mp = MovePicker(pos, MOVE_NONE, ONE_PLY, H); + + while ((move = mp.get_next_move()) != MOVE_NONE) + for (int i = 0; i < count; i++) + if (moves[i].move == move) + { + moves[i].mp_score = score--; + break; + } } - void RootMoveList::set_beta_counters(int moveNum, int64_t our, int64_t their) { - - moves[moveNum].ourBeta = our; - moves[moveNum].theirBeta = their; - } + // RootMoveList simple methods definitions void RootMoveList::set_move_pv(int moveNum, const Move pv[]) {