X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=2a2e32f943fae435ef69719364504b7b2f58fedc;hp=b76ad946652a1d7c0ad76148510eec7f51291fec;hb=c172af1b6181b39288870689f912143c04a4040a;hpb=b7781e8faa1716491e11ca98269863417e0e4a14 diff --git a/src/search.cpp b/src/search.cpp index b76ad946..2a2e32f9 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -1,13 +1,14 @@ /* - Glaurung, a UCI chess playing engine. - Copyright (C) 2004-2008 Tord Romstad + Stockfish, a UCI chess playing engine derived from Glaurung 2.1 + Copyright (C) 2004-2008 Tord Romstad (Glaurung author) + Copyright (C) 2008 Marco Costalba - Glaurung is free software: you can redistribute it and/or modify + Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. - Glaurung is distributed in the hope that it will be useful, + Stockfish is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. @@ -22,7 +23,6 @@ //// #include -#include #include #include #include @@ -70,16 +70,16 @@ namespace { public: RootMoveList(Position &pos, Move searchMoves[]); - Move get_move(int moveNum) const; - Value get_move_score(int moveNum) const; - void set_move_score(int moveNum, Value score); - void set_move_nodes(int moveNum, int64_t nodes); + inline Move get_move(int moveNum) const; + inline Value get_move_score(int moveNum) const; + inline void set_move_score(int moveNum, Value score); + inline void set_move_nodes(int moveNum, int64_t nodes); void set_move_pv(int moveNum, const Move pv[]); - Move get_move_pv(int moveNum, int i) const; - int64_t get_move_cumulative_nodes(int moveNum) const; - int move_count() const; + inline Move get_move_pv(int moveNum, int i) const; + inline int64_t get_move_cumulative_nodes(int moveNum) const; + inline int move_count() const; Move scan_for_easy_move() const; - void sort(); + inline void sort(); void sort_multipv(int n); private: @@ -106,6 +106,9 @@ namespace { const bool UseIIDAtPVNodes = true; const bool UseIIDAtNonPVNodes = false; + // Use null move driven internal iterative deepening? + bool UseNullDrivenIID = true; + // Internal iterative deepening margin. At Non-PV moves, when // UseIIDAtNonPVNodes is true, we do an internal iterative deepening search // when the static evaluation is at most IIDMargin below beta. @@ -144,7 +147,7 @@ namespace { bool UseFutilityPruning = true; // Margins for futility pruning in the quiescence search, at frontier - // nodes, and at pre-frontier nodes: + // nodes, and at pre-frontier nodes Value FutilityMargin0 = Value(0x80); Value FutilityMargin1 = Value(0x100); Value FutilityMargin2 = Value(0x300); @@ -153,6 +156,12 @@ namespace { Depth RazorDepth = 4*OnePly; Value RazorMargin = Value(0x300); + // Last seconds noise filtering (LSN) + bool UseLSNFiltering = false; + bool looseOnTime = false; + int LSNTime = 4 * 1000; // In milliseconds + Value LSNValue = Value(0x200); + // Extensions. Array index 0 is used at non-PV nodes, index 1 at PV nodes. Depth CheckExtension[2] = {OnePly, OnePly}; Depth SingleReplyExtension[2] = {OnePly / 2, OnePly / 2}; @@ -161,21 +170,22 @@ namespace { Depth PawnEndgameExtension[2] = {OnePly, OnePly}; Depth MateThreatExtension[2] = {Depth(0), Depth(0)}; - // Search depth at iteration 1: + // Search depth at iteration 1 const Depth InitialDepth = OnePly /*+ OnePly/2*/; // Node counters int NodesSincePoll; int NodesBetweenPolls = 30000; - // Iteration counter: + // Iteration counter int Iteration; + bool LastIterations; // Scores and number of times the best move changed for each iteration: Value ValueByIteration[PLY_MAX_PLUS_2]; int BestMoveChangesByIteration[PLY_MAX_PLUS_2]; - // MultiPV mode: + // MultiPV mode int MultiPV = 1; // Time managment variables @@ -221,7 +231,7 @@ namespace { /// Functions - void id_loop(const Position &pos, Move searchMoves[]); + Value id_loop(const Position &pos, Move searchMoves[]); Value root_search(Position &pos, SearchStack ss[], RootMoveList &rml); Value search_pv(Position &pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID); @@ -231,16 +241,20 @@ namespace { Depth depth, int ply, int threadID); void sp_search(SplitPoint *sp, int threadID); void sp_search_pv(SplitPoint *sp, int threadID); + void init_search_stack(SearchStack& ss); void init_search_stack(SearchStack ss[]); void init_node(const Position &pos, SearchStack ss[], int ply, int threadID); void update_pv(SearchStack ss[], int ply); void sp_update_pv(SearchStack *pss, SearchStack ss[], int ply); bool connected_moves(const Position &pos, Move m1, Move m2); - Depth extension(const Position &pos, Move m, bool pvNode, bool check, - bool singleReply, bool mateThreat); + bool move_is_killer(Move m, const SearchStack& ss); + Depth extension(const Position &pos, Move m, bool pvNode, bool check, bool singleReply, bool mateThreat, bool* dangerous); bool ok_to_do_nullmove(const Position &pos); bool ok_to_prune(const Position &pos, Move m, Move threat, Depth d); bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply); + bool ok_to_history(const Position &pos, Move m); + void update_history(const Position& pos, Move m, Depth depth, Move movesSearched[], int moveCount); + void update_killers(Move m, SearchStack& ss); bool fail_high_ply_1(); int current_search_time(); @@ -288,42 +302,49 @@ Lock IOLock; History H; // Should be made local? +// The empty search stack +SearchStack EmptySearchStack; + //// //// Functions //// -/// think() is the external interface to Glaurung's search, and is called when +/// think() is the external interface to Stockfish's search, and is called when /// the program receives the UCI 'go' command. It initializes various /// search-related global variables, and calls root_search() -void think(const Position &pos, bool infinite, bool ponder, int time, - int increment, int movesToGo, int maxDepth, int maxNodes, - int maxTime, Move searchMoves[]) { +void think(const Position &pos, bool infinite, bool ponder, int side_to_move, + int time[], int increment[], int movesToGo, int maxDepth, + int maxNodes, int maxTime, Move searchMoves[]) { - // Look for a book move: - if(!infinite && !ponder && get_option_value_bool("OwnBook")) { - Move bookMove; - if(get_option_value_string("Book File") != OpeningBook.file_name()) { - OpeningBook.close(); - OpeningBook.open("book.bin"); - } - bookMove = OpeningBook.get_move(pos); - if(bookMove != MOVE_NONE) { - std::cout << "bestmove " << bookMove << std::endl; - return; - } + // Look for a book move + if (!infinite && !ponder && get_option_value_bool("OwnBook")) + { + Move bookMove; + if (get_option_value_string("Book File") != OpeningBook.file_name()) + { + OpeningBook.close(); + OpeningBook.open("book.bin"); + } + bookMove = OpeningBook.get_move(pos); + if (bookMove != MOVE_NONE) + { + std::cout << "bestmove " << bookMove << std::endl; + return; + } } - // Initialize global search variables: + // Initialize global search variables Idle = false; SearchStartTime = get_system_time(); BestRootMove = MOVE_NONE; PonderMove = MOVE_NONE; EasyMove = MOVE_NONE; - for(int i = 0; i < THREAD_MAX; i++) { - Threads[i].nodes = 0ULL; - Threads[i].failHighPly1 = false; + for (int i = 0; i < THREAD_MAX; i++) + { + Threads[i].nodes = 0ULL; + Threads[i].failHighPly1 = false; } NodesSincePoll = 0; InfiniteSearch = infinite; @@ -335,142 +356,162 @@ void think(const Position &pos, bool infinite, bool ponder, int time, Problem = false; ExactMaxTime = maxTime; - // Read UCI option values: + // Read UCI option values TT.set_size(get_option_value_int("Hash")); - if(button_was_pressed("Clear Hash")) - TT.clear(); - PonderingEnabled = get_option_value_int("Ponder"); + if (button_was_pressed("Clear Hash")) + TT.clear(); + + PonderingEnabled = get_option_value_bool("Ponder"); MultiPV = get_option_value_int("MultiPV"); CheckExtension[1] = Depth(get_option_value_int("Check Extension (PV nodes)")); - CheckExtension[0] = - Depth(get_option_value_int("Check Extension (non-PV nodes)")); + CheckExtension[0] = Depth(get_option_value_int("Check Extension (non-PV nodes)")); + SingleReplyExtension[1] = Depth(get_option_value_int("Single Reply Extension (PV nodes)")); - SingleReplyExtension[0] = - Depth(get_option_value_int("Single Reply Extension (non-PV nodes)")); - PawnPushTo7thExtension[1] = - Depth(get_option_value_int("Pawn Push to 7th Extension (PV nodes)")); - PawnPushTo7thExtension[0] = - Depth(get_option_value_int("Pawn Push to 7th Extension (non-PV nodes)")); - PassedPawnExtension[1] = - Depth(get_option_value_int("Passed Pawn Extension (PV nodes)")); - PassedPawnExtension[0] = - Depth(get_option_value_int("Passed Pawn Extension (non-PV nodes)")); - PawnEndgameExtension[1] = - Depth(get_option_value_int("Pawn Endgame Extension (PV nodes)")); - PawnEndgameExtension[0] = - Depth(get_option_value_int("Pawn Endgame Extension (non-PV nodes)")); - MateThreatExtension[1] = - Depth(get_option_value_int("Mate Threat Extension (PV nodes)")); - MateThreatExtension[0] = - Depth(get_option_value_int("Mate Threat Extension (non-PV nodes)")); - - LMRPVMoves = get_option_value_int("Full Depth Moves (PV nodes)") + 1; - LMRNonPVMoves = get_option_value_int("Full Depth Moves (non-PV nodes)") + 1; - ThreatDepth = get_option_value_int("Threat Depth") * OnePly; + SingleReplyExtension[0] = Depth(get_option_value_int("Single Reply Extension (non-PV nodes)")); + + PawnPushTo7thExtension[1] = Depth(get_option_value_int("Pawn Push to 7th Extension (PV nodes)")); + PawnPushTo7thExtension[0] = Depth(get_option_value_int("Pawn Push to 7th Extension (non-PV nodes)")); + + PassedPawnExtension[1] = Depth(get_option_value_int("Passed Pawn Extension (PV nodes)")); + PassedPawnExtension[0] = Depth(get_option_value_int("Passed Pawn Extension (non-PV nodes)")); + + PawnEndgameExtension[1] = Depth(get_option_value_int("Pawn Endgame Extension (PV nodes)")); + PawnEndgameExtension[0] = Depth(get_option_value_int("Pawn Endgame Extension (non-PV nodes)")); + + MateThreatExtension[1] = Depth(get_option_value_int("Mate Threat Extension (PV nodes)")); + MateThreatExtension[0] = Depth(get_option_value_int("Mate Threat Extension (non-PV nodes)")); + + LMRPVMoves = get_option_value_int("Full Depth Moves (PV nodes)") + 1; + LMRNonPVMoves = get_option_value_int("Full Depth Moves (non-PV nodes)") + 1; + ThreatDepth = get_option_value_int("Threat Depth") * OnePly; SelectiveDepth = get_option_value_int("Selective Plies") * OnePly; Chess960 = get_option_value_bool("UCI_Chess960"); ShowCurrentLine = get_option_value_bool("UCI_ShowCurrLine"); UseLogFile = get_option_value_bool("Use Search Log"); - if(UseLogFile) - LogFile.open(get_option_value_string("Search Log Filename").c_str(), - std::ios::out | std::ios::app); - - UseQSearchFutilityPruning = - get_option_value_bool("Futility Pruning (Quiescence Search)"); - UseFutilityPruning = - get_option_value_bool("Futility Pruning (Main Search)"); - - FutilityMargin0 = - value_from_centipawns(get_option_value_int("Futility Margin 0")); - FutilityMargin1 = - value_from_centipawns(get_option_value_int("Futility Margin 1")); - FutilityMargin2 = - value_from_centipawns(get_option_value_int("Futility Margin 2")); + if (UseLogFile) + LogFile.open(get_option_value_string("Search Log Filename").c_str(), std::ios::out | std::ios::app); + + UseQSearchFutilityPruning = get_option_value_bool("Futility Pruning (Quiescence Search)"); + UseFutilityPruning = get_option_value_bool("Futility Pruning (Main Search)"); + + FutilityMargin0 = value_from_centipawns(get_option_value_int("Futility Margin 0")); + FutilityMargin1 = value_from_centipawns(get_option_value_int("Futility Margin 1")); + FutilityMargin2 = value_from_centipawns(get_option_value_int("Futility Margin 2")); RazorDepth = (get_option_value_int("Maximum Razoring Depth") + 1) * OnePly; RazorMargin = value_from_centipawns(get_option_value_int("Razoring Margin")); + UseLSNFiltering = get_option_value_bool("LSN filtering"); + LSNTime = get_option_value_int("LSN Time Margin (sec)") * 1000; + LSNValue = value_from_centipawns(get_option_value_int("LSN Value Margin")); + MinimumSplitDepth = get_option_value_int("Minimum Split Depth") * OnePly; - MaxThreadsPerSplitPoint = - get_option_value_int("Maximum Number of Threads per Split Point"); + MaxThreadsPerSplitPoint = get_option_value_int("Maximum Number of Threads per Split Point"); read_weights(pos.side_to_move()); int newActiveThreads = get_option_value_int("Threads"); - if(newActiveThreads != ActiveThreads) { - ActiveThreads = newActiveThreads; - init_eval(ActiveThreads); - } - - // Write information to search log file: - if(UseLogFile) { - LogFile << "Searching: " << pos.to_fen() << '\n'; - LogFile << "infinite: " << infinite << " ponder: " << ponder - << " time: " << time << " increment: " << increment - << " moves to go: " << movesToGo << '\n'; + if (newActiveThreads != ActiveThreads) + { + ActiveThreads = newActiveThreads; + init_eval(ActiveThreads); } // Wake up sleeping threads: wake_sleeping_threads(); - for(int i = 1; i < ActiveThreads; i++) - assert(thread_is_available(i, 0)); + for (int i = 1; i < ActiveThreads; i++) + assert(thread_is_available(i, 0)); // Set thinking time: - if(!movesToGo) { // Sudden death time control - if(increment) { - MaxSearchTime = time / 30 + increment; - AbsoluteMaxSearchTime = Max(time / 4, increment - 100); - } - else { // Blitz game without increment - MaxSearchTime = time / 40; - AbsoluteMaxSearchTime = time / 8; - } + int myTime = time[side_to_move]; + int myIncrement = increment[side_to_move]; + int oppTime = time[1 - side_to_move]; + + 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 = time / 2; - AbsoluteMaxSearchTime = Min(time / 2, time - 500); - } - else { - MaxSearchTime = time / Min(movesToGo, 20); - AbsoluteMaxSearchTime = Min((4 * time) / movesToGo, time / 3); - } + else // (x moves) / (y minutes) + { + if (movesToGo == 1) + { + MaxSearchTime = myTime / 2; + AbsoluteMaxSearchTime = Min(myTime / 2, myTime - 500); + } else { + MaxSearchTime = myTime / Min(movesToGo, 20); + AbsoluteMaxSearchTime = Min((4 * myTime) / movesToGo, myTime / 3); + } } - if(PonderingEnabled) { - MaxSearchTime += MaxSearchTime / 4; - MaxSearchTime = Min(MaxSearchTime, AbsoluteMaxSearchTime); + + if (PonderingEnabled) + { + MaxSearchTime += MaxSearchTime / 4; + MaxSearchTime = Min(MaxSearchTime, AbsoluteMaxSearchTime); } // Fixed depth or fixed number of nodes? MaxDepth = maxDepth; - if(MaxDepth) - InfiniteSearch = true; // HACK + if (MaxDepth) + InfiniteSearch = true; // HACK MaxNodes = maxNodes; - if(MaxNodes) { - NodesBetweenPolls = Min(MaxNodes, 30000); - InfiniteSearch = true; // HACK + if (MaxNodes) + { + NodesBetweenPolls = Min(MaxNodes, 30000); + InfiniteSearch = true; // HACK } else - NodesBetweenPolls = 30000; + NodesBetweenPolls = 30000; + + + // Write information to search log file: + if (UseLogFile) + LogFile << "Searching: " << pos.to_fen() << std::endl + << "infinite: " << infinite + << " ponder: " << ponder + << " time: " << myTime + << " increment: " << myIncrement + << " moves to go: " << movesToGo << std::endl; + // We're ready to start thinking. Call the iterative deepening loop // function: - id_loop(pos, searchMoves); + if (!looseOnTime) + { + Value v = id_loop(pos, searchMoves); + looseOnTime = ( UseLSNFiltering + && myTime < LSNTime + && myIncrement == 0 + && v < -LSNValue); + } + else + { + looseOnTime = false; // reset for next match + while (SearchStartTime + myTime + 1000 > get_system_time()) + ; // wait here + id_loop(pos, searchMoves); // to fail gracefully + } - if(UseLogFile) - LogFile.close(); + if (UseLogFile) + LogFile.close(); - if(Quit) { - OpeningBook.close(); - stop_threads(); - quit_eval(); - exit(0); + if (Quit) + { + OpeningBook.close(); + stop_threads(); + quit_eval(); + exit(0); } - Idle = true; } @@ -480,13 +521,15 @@ void think(const Position &pos, bool infinite, bool ponder, int time, /// objects. void init_threads() { + volatile int i; + #if !defined(_MSC_VER) pthread_t pthread[1]; #endif - for(i = 0; i < THREAD_MAX; i++) - Threads[i].activeSplitPoints = 0; + for (i = 0; i < THREAD_MAX; i++) + Threads[i].activeSplitPoints = 0; // Initialize global locks: lock_init(&MPLock, NULL); @@ -498,32 +541,35 @@ void init_threads() { pthread_mutex_init(&WaitLock, NULL); pthread_cond_init(&WaitCond, NULL); #else - for(i = 0; i < THREAD_MAX; i++) - SitIdleEvent[i] = CreateEvent(0, FALSE, FALSE, 0); + for (i = 0; i < THREAD_MAX; i++) + SitIdleEvent[i] = CreateEvent(0, FALSE, FALSE, 0); #endif - // All threads except the main thread should be initialized to idle state: - for(i = 1; i < THREAD_MAX; i++) { - Threads[i].stop = false; - Threads[i].workIsWaiting = false; - Threads[i].idle = true; - Threads[i].running = false; + // All threads except the main thread should be initialized to idle state + for (i = 1; i < THREAD_MAX; i++) + { + Threads[i].stop = false; + Threads[i].workIsWaiting = false; + Threads[i].idle = true; + Threads[i].running = false; } - // Launch the helper threads: - for(i = 1; i < THREAD_MAX; i++) { + // Launch the helper threads + for(i = 1; i < THREAD_MAX; i++) + { #if !defined(_MSC_VER) - pthread_create(pthread, NULL, init_thread, (void*)(&i)); + pthread_create(pthread, NULL, init_thread, (void*)(&i)); #else - { DWORD iID[1]; CreateThread(NULL, 0, init_thread, (LPVOID)(&i), 0, iID); - } #endif - // Wait until the thread has finished launching: - while(!Threads[i].running); + // Wait until the thread has finished launching: + while (!Threads[i].running); } + + // Init also the empty search stack + init_search_stack(EmptySearchStack); } @@ -531,13 +577,15 @@ void init_threads() { /// helper threads exit cleanly. void stop_threads() { + ActiveThreads = THREAD_MAX; // HACK Idle = false; // HACK wake_sleeping_threads(); AllThreadsShouldExit = true; - for(int i = 1; i < THREAD_MAX; i++) { - Threads[i].stop = true; - while(Threads[i].running); + for (int i = 1; i < THREAD_MAX; i++) + { + Threads[i].stop = true; + while(Threads[i].running); } destroy_split_point_stack(); } @@ -547,9 +595,10 @@ void stop_threads() { /// the current search. int64_t nodes_searched() { + int64_t result = 0ULL; - for(int i = 0; i < ActiveThreads; i++) - result += Threads[i].nodes; + for (int i = 0; i < ActiveThreads; i++) + result += Threads[i].nodes; return result; } @@ -561,7 +610,8 @@ namespace { // been consumed, the user stops the search, or the maximum search depth is // reached. - void id_loop(const Position &pos, Move searchMoves[]) { + Value id_loop(const Position &pos, Move searchMoves[]) { + Position p(pos); SearchStack ss[PLY_MAX_PLUS_2]; @@ -576,111 +626,118 @@ namespace { ValueByIteration[0] = Value(0); ValueByIteration[1] = rml.get_move_score(0); Iteration = 1; + LastIterations = false; EasyMove = rml.scan_for_easy_move(); // Iterative deepening loop - while(!AbortSearch && Iteration < PLY_MAX) { - - // Initialize iteration - rml.sort(); - Iteration++; - BestMoveChangesByIteration[Iteration] = 0; - if(Iteration <= 5) - ExtraSearchTime = 0; - - std::cout << "info depth " << Iteration << std::endl; - - // Search to the current depth - ValueByIteration[Iteration] = root_search(p, ss, rml); - - // Erase the easy move if it differs from the new best move - if(ss[0].pv[0] != EasyMove) - EasyMove = MOVE_NONE; - - Problem = false; - - if(!InfiniteSearch) { - // Time to stop? - bool stopSearch = false; - - // Stop search early if there is only a single legal move: - if(Iteration >= 6 && rml.move_count() == 1) - stopSearch = true; - - // Stop search early when the last two iterations returned a mate - // score: - if(Iteration >= 6 - && abs(ValueByIteration[Iteration]) >= abs(VALUE_MATE) - 100 - && abs(ValueByIteration[Iteration-1]) >= abs(VALUE_MATE) - 100) - stopSearch = true; - - // Stop search early if one move seems to be much better than the - // rest: - int64_t nodes = nodes_searched(); - 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))) - stopSearch = true; - - // Add some extra time if the best move has changed during the last - // two iterations: - if(Iteration > 5 && Iteration <= 50) - ExtraSearchTime = - BestMoveChangesByIteration[Iteration] * (MaxSearchTime / 2) + - BestMoveChangesByIteration[Iteration-1] * (MaxSearchTime / 3); - - // Stop search if most of MaxSearchTime is consumed at the end of the - // iteration. We probably don't have enough time to search the first - // move at the next iteration anyway. - if(current_search_time() > ((MaxSearchTime + ExtraSearchTime)*80) / 128) - stopSearch = true; - - if(stopSearch) { - if(!PonderSearch) - break; - else - StopOnPonderhit = true; - } - } + while (!AbortSearch && Iteration < PLY_MAX) + { + // Initialize iteration + rml.sort(); + Iteration++; + BestMoveChangesByIteration[Iteration] = 0; + if (Iteration <= 5) + ExtraSearchTime = 0; - // Write PV to transposition table, in case the relevant entries have - // been overwritten during the search: - TT.insert_pv(p, ss[0].pv); + std::cout << "info depth " << Iteration << std::endl; - if(MaxDepth && Iteration >= MaxDepth) - break; + // Search to the current depth + ValueByIteration[Iteration] = root_search(p, ss, rml); + + // Erase the easy move if it differs from the new best move + if (ss[0].pv[0] != EasyMove) + EasyMove = MOVE_NONE; + + Problem = false; + + if (!InfiniteSearch) + { + // Time to stop? + bool stopSearch = false; + + // Stop search early if there is only a single legal move: + if (Iteration >= 6 && rml.move_count() == 1) + stopSearch = true; + + // Stop search early when the last two iterations returned a mate score + if ( Iteration >= 6 + && abs(ValueByIteration[Iteration]) >= abs(VALUE_MATE) - 100 + && abs(ValueByIteration[Iteration-1]) >= abs(VALUE_MATE) - 100) + stopSearch = true; + + // Stop search early if one move seems to be much better than the rest + int64_t nodes = nodes_searched(); + 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))) + 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); + + // Try to guess if the current iteration is the last one or the last two + LastIterations = (current_search_time() > ((MaxSearchTime + ExtraSearchTime)*58) / 128); + + // Stop search if most of MaxSearchTime is consumed at the end of the + // iteration. We probably don't have enough time to search the first + // move at the next iteration anyway. + if (current_search_time() > ((MaxSearchTime + ExtraSearchTime)*80) / 128) + stopSearch = true; + + if (stopSearch) + { + if (!PonderSearch) + break; + else + StopOnPonderhit = true; + } + } + // Write PV to transposition table, in case the relevant entries have + // been overwritten during the search: + TT.insert_pv(p, ss[0].pv); + + if (MaxDepth && Iteration >= MaxDepth) + break; } rml.sort(); // If we are pondering, we shouldn't print the best move before we // are told to do so - if(PonderSearch) - wait_for_stop_or_ponderhit(); + if (PonderSearch) + wait_for_stop_or_ponderhit(); else - // Print final search statistics - std::cout << "info nodes " << nodes_searched() << " nps " << nps() - << " time " << current_search_time() - << " hashfull " << TT.full() << std::endl; + // Print final search statistics + std::cout << "info nodes " << nodes_searched() + << " nps " << nps() + << " time " << current_search_time() + << " hashfull " << TT.full() << std::endl; - // Print the best move and the ponder move to the standard output: + // Print the best move and the ponder move to the standard output std::cout << "bestmove " << ss[0].pv[0]; - if(ss[0].pv[1] != MOVE_NONE) - std::cout << " ponder " << ss[0].pv[1]; + if (ss[0].pv[1] != MOVE_NONE) + std::cout << " ponder " << ss[0].pv[1]; + std::cout << std::endl; - if(UseLogFile) { - UndoInfo u; - LogFile << "Nodes: " << nodes_searched() << '\n'; - LogFile << "Nodes/second: " << nps() << '\n'; - LogFile << "Best move: " << move_to_san(p, ss[0].pv[0]) << '\n'; - p.do_move(ss[0].pv[0], u); - LogFile << "Ponder move: " << move_to_san(p, ss[0].pv[1]) << '\n'; - LogFile << std::endl; + if (UseLogFile) + { + UndoInfo u; + LogFile << "Nodes: " << nodes_searched() << std::endl + << "Nodes/second: " << nps() << std::endl + << "Best move: " << move_to_san(p, ss[0].pv[0]) << std::endl; + + p.do_move(ss[0].pv[0], u); + LogFile << "Ponder move: " << move_to_san(p, ss[0].pv[1]) + << std::endl << std::endl; } + return rml.get_move_score(0); } @@ -690,134 +747,148 @@ namespace { // and prints some information to the standard output. Value root_search(Position &pos, SearchStack ss[], RootMoveList &rml) { - Value alpha = -VALUE_INFINITE, beta = VALUE_INFINITE, value; - Bitboard dcCandidates = pos.discovered_check_candidates(pos.side_to_move()); - - // Loop through all the moves in the root move list: - for(int i = 0; i < rml.move_count() && !AbortSearch; i++) { - int64_t nodes; - Move move; - UndoInfo u; - Depth ext, newDepth; - - RootMoveNumber = i + 1; - FailHigh = false; - - // Remember the node count before the move is searched. The node counts - // are used to sort the root moves at the next iteration. - nodes = nodes_searched(); - // Pick the next root move, and print the move and the move number to - // the standard output: - move = ss[0].currentMove = rml.get_move(i); - if(current_search_time() >= 1000) - std::cout << "info currmove " << move - << " currmovenumber " << i + 1 << std::endl; + Value alpha = -VALUE_INFINITE; + Value beta = VALUE_INFINITE, value; + Bitboard dcCandidates = pos.discovered_check_candidates(pos.side_to_move()); - // Decide search depth for this move: - ext = extension(pos, move, true, pos.move_is_check(move), false, false); - newDepth = (Iteration-2)*OnePly + ext + InitialDepth; + // Loop through all the moves in the root move list + for (int i = 0; i < rml.move_count() && !AbortSearch; i++) + { + int64_t nodes; + Move move; + UndoInfo u; + Depth ext, newDepth; + + RootMoveNumber = i + 1; + FailHigh = false; + + // Remember the node count before the move is searched. The node counts + // are used to sort the root moves at the next iteration. + nodes = nodes_searched(); + + // Pick the next root move, and print the move and the move number to + // the standard output. + move = ss[0].currentMove = rml.get_move(i); + if (current_search_time() >= 1000) + std::cout << "info currmove " << move + << " currmovenumber " << i + 1 << std::endl; + + // Decide search depth for this move + bool dangerous; + ext = extension(pos, move, true, pos.move_is_check(move), false, false, &dangerous); + newDepth = (Iteration - 2) * OnePly + ext + InitialDepth; + + // Make the move, and search it + pos.do_move(move, u, dcCandidates); + + if (i < MultiPV) + { + value = -search_pv(pos, ss, -beta, VALUE_INFINITE, newDepth, 1, 0); + // If the value has dropped a lot compared to the last iteration, + // set the boolean variable Problem to true. This variable is used + // for time managment: When Problem is true, we try to complete the + // current iteration before playing a move. + Problem = (Iteration >= 2 && value <= ValueByIteration[Iteration-1] - ProblemMargin); + + if (Problem && StopOnPonderhit) + StopOnPonderhit = false; + } + else + { + value = -search(pos, ss, -alpha, newDepth, 1, true, 0); + if (value > alpha) + { + // Fail high! Set the boolean variable FailHigh to true, and + // re-search the move with a big window. The variable FailHigh is + // used for time managment: We try to avoid aborting the search + // prematurely during a fail high research. + FailHigh = true; + value = -search_pv(pos, ss, -beta, -alpha, newDepth, 1, 0); + } + } - // Make the move, and search it. - pos.do_move(move, u, dcCandidates); + pos.undo_move(move, u); - if(i < MultiPV) { - value = -search_pv(pos, ss, -beta, VALUE_INFINITE, newDepth, 1, 0); - // If the value has dropped a lot compared to the last iteration, - // set the boolean variable Problem to true. This variable is used - // for time managment: When Problem is true, we try to complete the - // current iteration before playing a move. - Problem = (Iteration >= 2 && - value <= ValueByIteration[Iteration-1] - ProblemMargin); - if(Problem && StopOnPonderhit) - StopOnPonderhit = false; - } - else { - value = -search(pos, ss, -alpha, newDepth, 1, true, 0); - if(value > alpha) { - // Fail high! Set the boolean variable FailHigh to true, and - // re-search the move with a big window. The variable FailHigh is - // used for time managment: We try to avoid aborting the search - // prematurely during a fail high research. - FailHigh = true; - value = -search_pv(pos, ss, -beta, -alpha, newDepth, 1, 0); - } - } + // Finished searching the move. If AbortSearch is true, the search + // was aborted because the user interrupted the search or because we + // ran out of time. In this case, the return value of the search cannot + // be trusted, and we break out of the loop without updating the best + // move and/or PV: + if (AbortSearch) + break; - pos.undo_move(move, u); + // Remember the node count for this move. The node counts are used to + // sort the root moves at the next iteration. + rml.set_move_nodes(i, nodes_searched() - nodes); - // Finished searching the move. If AbortSearch is true, the search - // was aborted because the user interrupted the search or because we - // ran out of time. In this case, the return value of the search cannot - // be trusted, and we break out of the loop without updating the best - // move and/or PV: - if(AbortSearch) - break; + assert(value >= -VALUE_INFINITE && value <= VALUE_INFINITE); - // Remember the node count for this move. The node counts are used to - // sort the root moves at the next iteration. - rml.set_move_nodes(i, nodes_searched() - nodes); + if (value <= alpha && i >= MultiPV) + rml.set_move_score(i, -VALUE_INFINITE); + else + { + // New best move! - assert(value >= -VALUE_INFINITE && value <= VALUE_INFINITE); + // Update PV + rml.set_move_score(i, value); + update_pv(ss, 0); + rml.set_move_pv(i, ss[0].pv); - if(value <= alpha && i >= MultiPV) - rml.set_move_score(i, -VALUE_INFINITE); - else { - // New best move! - - // Update PV: - rml.set_move_score(i, value); - update_pv(ss, 0); - rml.set_move_pv(i, ss[0].pv); - - if(MultiPV == 1) { - // We record how often the best move has been changed in each - // iteration. This information is used for time managment: When - // the best move changes frequently, we allocate some more time. - if(i > 0) - BestMoveChangesByIteration[Iteration]++; - - // Print search information to the standard output: - std::cout << "info depth " << Iteration - << " score " << value_to_string(value) - << " time " << current_search_time() - << " nodes " << nodes_searched() - << " nps " << nps() - << " pv "; - for(int j = 0; ss[0].pv[j] != MOVE_NONE && j < PLY_MAX; j++) - std::cout << ss[0].pv[j] << " "; - std::cout << std::endl; - - if(UseLogFile) - LogFile << pretty_pv(pos, current_search_time(), Iteration, - nodes_searched(), value, ss[0].pv) - << std::endl; - - alpha = value; - - // Reset the global variable Problem to false if the value isn't too - // far below the final value from the last iteration. - if(value > ValueByIteration[Iteration - 1] - NoProblemMargin) - Problem = false; - } - else { // MultiPV > 1 - rml.sort_multipv(i); - for(int j = 0; j < Min(MultiPV, rml.move_count()); j++) { - int k; - std::cout << "info multipv " << j + 1 - << " score " << value_to_string(rml.get_move_score(j)) - << " depth " << ((j <= i)? Iteration : Iteration - 1) - << " time " << current_search_time() - << " nodes " << nodes_searched() - << " nps " << nps() - << " pv "; - for(k = 0; rml.get_move_pv(j, k) != MOVE_NONE && k < PLY_MAX; k++) - std::cout << rml.get_move_pv(j, k) << " "; - std::cout << std::endl; - } - alpha = rml.get_move_score(Min(i, MultiPV-1)); + if (MultiPV == 1) + { + // We record how often the best move has been changed in each + // iteration. This information is used for time managment: When + // the best move changes frequently, we allocate some more time. + if (i > 0) + BestMoveChangesByIteration[Iteration]++; + + // Print search information to the standard output: + std::cout << "info depth " << Iteration + << " score " << value_to_string(value) + << " time " << current_search_time() + << " nodes " << nodes_searched() + << " nps " << nps() + << " pv "; + + for (int j = 0; ss[0].pv[j] != MOVE_NONE && j < PLY_MAX; j++) + std::cout << ss[0].pv[j] << " "; + + std::cout << std::endl; + + if (UseLogFile) + LogFile << pretty_pv(pos, current_search_time(), Iteration, nodes_searched(), value, ss[0].pv) + << std::endl; + + alpha = value; + + // Reset the global variable Problem to false if the value isn't too + // far below the final value from the last iteration. + if (value > ValueByIteration[Iteration - 1] - NoProblemMargin) + Problem = false; + } + else // MultiPV > 1 + { + rml.sort_multipv(i); + for (int j = 0; j < Min(MultiPV, rml.move_count()); j++) + { + int k; + std::cout << "info multipv " << j + 1 + << " score " << value_to_string(rml.get_move_score(j)) + << " depth " << ((j <= i)? Iteration : Iteration - 1) + << " time " << current_search_time() + << " nodes " << nodes_searched() + << " nps " << nps() + << " pv "; + + for (k = 0; rml.get_move_pv(j, k) != MOVE_NONE && k < PLY_MAX; k++) + std::cout << rml.get_move_pv(j, k) << " "; + + std::cout << std::endl; + } + alpha = rml.get_move_score(Min(i, MultiPV-1)); + } } - } } return alpha; } @@ -833,12 +904,8 @@ namespace { assert(ply >= 0 && ply < PLY_MAX); assert(threadID >= 0 && threadID < ActiveThreads); - EvalInfo ei; - // Initialize, and make an early exit in case of an aborted search, // an instant draw, maximum ply reached, etc. - Value oldAlpha = alpha; - if (AbortSearch || thread_should_stop(threadID)) return Value(0); @@ -850,22 +917,24 @@ namespace { if (pos.is_draw()) return VALUE_DRAW; + EvalInfo ei; + if (ply >= PLY_MAX - 1) return evaluate(pos, ei, threadID); // Mate distance pruning + Value oldAlpha = alpha; alpha = Max(value_mated_in(ply), alpha); beta = Min(value_mate_in(ply+1), beta); if (alpha >= beta) return alpha; - // Transposition table lookup. At PV nodes, we don't use the TT for + // Transposition table lookup. At PV nodes, we don't use the TT for // pruning, but only for move ordering. const TTEntry* tte = TT.retrieve(pos); - Move ttMove = (tte ? tte->move() : MOVE_NONE); - // Go with internal iterative deepening if we don't have a TT move. + // Go with internal iterative deepening if we don't have a TT move if (UseIIDAtPVNodes && ttMove == MOVE_NONE && depth >= 5*OnePly) { search_pv(pos, ss, alpha, beta, depth-2*OnePly, ply, threadID); @@ -873,16 +942,15 @@ namespace { } // Initialize a MovePicker object for the current position, and prepare - // to search all moves: - MovePicker mp = MovePicker(pos, true, ttMove, ss[ply].mateKiller, - ss[ply].killer1, ss[ply].killer2, depth); + // to search all moves + MovePicker mp = MovePicker(pos, true, ttMove, ss[ply], depth); Move move, movesSearched[256]; int moveCount = 0; Value value, bestValue = -VALUE_INFINITE; Bitboard dcCandidates = mp.discovered_check_candidates(); - bool mateThreat = MateThreatExtension[1] > Depth(0) - && pos.has_mate_threat(opposite_color(pos.side_to_move())); + bool isCheck = pos.is_check(); + bool mateThreat = pos.has_mate_threat(opposite_color(pos.side_to_move())); // Loop through all legal moves until no moves remain or a beta cutoff // occurs. @@ -892,21 +960,25 @@ namespace { { assert(move_is_ok(move)); - bool singleReply = (pos.is_check() && mp.number_of_moves() == 1); + bool singleReply = (isCheck && mp.number_of_moves() == 1); bool moveIsCheck = pos.move_is_check(move, dcCandidates); bool moveIsCapture = pos.move_is_capture(move); - bool moveIsPassedPawnPush = pos.move_is_passed_pawn_push(move); movesSearched[moveCount++] = ss[ply].currentMove = move; - ss[ply].currentMoveCaptureValue = move_is_ep(move) ? - PawnValueMidgame : pos.midgame_value_of_piece_on(move_to(move)); + if (moveIsCapture) + ss[ply].currentMoveCaptureValue = pos.midgame_value_of_piece_on(move_to(move)); + else if (move_is_ep(move)) + ss[ply].currentMoveCaptureValue = PawnValueMidgame; + else + ss[ply].currentMoveCaptureValue = Value(0); - // Decide the new search depth. - Depth ext = extension(pos, move, true, moveIsCheck, singleReply, mateThreat); + // Decide the new search depth + bool dangerous; + Depth ext = extension(pos, move, true, moveIsCheck, singleReply, mateThreat, &dangerous); Depth newDepth = depth - OnePly + ext; - // Make and search the move. + // Make and search the move UndoInfo u; pos.do_move(move, u, dcCandidates); @@ -917,14 +989,12 @@ namespace { // Try to reduce non-pv search depth by one ply if move seems not problematic, // if the move fails high will be re-searched at full depth. if ( depth >= 2*OnePly - && ext == Depth(0) && moveCount >= LMRPVMoves + && !dangerous && !moveIsCapture && !move_promotion(move) - && !moveIsPassedPawnPush && !move_is_castle(move) - && move != ss[ply].killer1 - && move != ss[ply].killer2) + && !move_is_killer(move, ss[ply])) { ss[ply].reduction = OnePly; value = -search(pos, ss, -alpha, newDepth-OnePly, ply+1, true, threadID); @@ -932,7 +1002,7 @@ namespace { else value = alpha + 1; // Just to trigger next condition - if (value > alpha) // Go with full depth non-pv search + if (value > alpha) // Go with full depth pv search { ss[ply].reduction = Depth(0); value = -search(pos, ss, -alpha, newDepth, ply+1, true, threadID); @@ -976,9 +1046,12 @@ namespace { // Split? if ( ActiveThreads > 1 - && bestValue < beta && depth >= MinimumSplitDepth - && Iteration <= 99 && idle_thread_exists(threadID) - && !AbortSearch && !thread_should_stop(threadID) + && bestValue < beta + && depth >= MinimumSplitDepth + && Iteration <= 99 + && idle_thread_exists(threadID) + && !AbortSearch + && !thread_should_stop(threadID) && split(pos, ss, ply, &alpha, &beta, &bestValue, depth, &moveCount, &mp, dcCandidates, threadID, true)) break; @@ -987,11 +1060,10 @@ namespace { // All legal moves have been searched. A special case: If there were // no legal moves, it must be mate or stalemate: if (moveCount == 0) - return (pos.is_check() ? value_mated_in(ply) : VALUE_DRAW); + return (isCheck ? value_mated_in(ply) : VALUE_DRAW); // If the search is not aborted, update the transposition table, - // history counters, and killer moves. This code is somewhat messy, - // and definitely needs to be cleaned up. FIXME + // history counters, and killer moves. if (AbortSearch || thread_should_stop(threadID)) return bestValue; @@ -1001,21 +1073,10 @@ namespace { else if (bestValue >= beta) { Move m = ss[ply].pv[ply]; - if (pos.square_is_empty(move_to(m)) && !move_promotion(m) && !move_is_ep(m)) + if (ok_to_history(pos, m)) // Only non capture moves are considered { - for(int i = 0; i < moveCount - 1; i++) - if( pos.square_is_empty(move_to(movesSearched[i])) - && !move_promotion(movesSearched[i]) - && !move_is_ep(movesSearched[i])) - H.failure(pos.piece_on(move_from(movesSearched[i])), movesSearched[i]); - - H.success(pos.piece_on(move_from(m)), m, depth); - - if (m != ss[ply].killer1) - { - ss[ply].killer2 = ss[ply].killer1; - ss[ply].killer1 = m; - } + update_history(pos, m, depth, movesSearched, moveCount); + update_killers(m, ss[ply]); } TT.store(pos, value_to_tt(bestValue, ply), depth, m, VALUE_TYPE_LOWER); } @@ -1030,6 +1091,7 @@ namespace { Value search(Position &pos, SearchStack ss[], Value beta, Depth depth, int ply, bool allowNullmove, int threadID) { + assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE); assert(ply >= 0 && ply < PLY_MAX); assert(threadID >= 0 && threadID < ActiveThreads); @@ -1038,218 +1100,260 @@ namespace { // Initialize, and make an early exit in case of an aborted search, // an instant draw, maximum ply reached, etc. - if(AbortSearch || thread_should_stop(threadID)) - return Value(0); + if (AbortSearch || thread_should_stop(threadID)) + return Value(0); - if(depth < OnePly) - return qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID); + if (depth < OnePly) + return qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID); init_node(pos, ss, ply, threadID); - if(pos.is_draw()) - return VALUE_DRAW; + if (pos.is_draw()) + return VALUE_DRAW; - if(ply >= PLY_MAX - 1) - return evaluate(pos, ei, threadID); + if (ply >= PLY_MAX - 1) + return evaluate(pos, ei, threadID); // Mate distance pruning - if(value_mated_in(ply) >= beta) - return beta; - if(value_mate_in(ply+1) < beta) - return beta-1; + if (value_mated_in(ply) >= beta) + return beta; + + if (value_mate_in(ply + 1) < beta) + return beta - 1; // Transposition table lookup const TTEntry* tte = TT.retrieve(pos); - Move ttMove = (tte ? tte->move() : MOVE_NONE); if (tte && ok_to_use_TT(tte, depth, beta, ply)) { - ss[ply].currentMove = ttMove; // can be MOVE_NONE ? + ss[ply].currentMove = ttMove; // can be MOVE_NONE return value_from_tt(tte->value(), ply); } Value approximateEval = quick_evaluate(pos); bool mateThreat = false; + bool nullDrivenIID = false; + bool isCheck = pos.is_check(); // Null move search - if(!pos.is_check() && allowNullmove && ok_to_do_nullmove(pos) - && approximateEval >= beta - NullMoveMargin) { - UndoInfo u; - Value nullValue; - - ss[ply].currentMove = MOVE_NULL; - pos.do_null_move(u); - nullValue = -search(pos, ss, -(beta-1), depth-4*OnePly, ply+1, false, - threadID); - pos.undo_null_move(u); - - if(nullValue >= beta) { - if(depth >= 6 * OnePly) { // Do zugzwang verification search - Value v = search(pos, ss, beta, depth-5*OnePly, ply, false, threadID); - if(v >= beta) - return beta; + if ( allowNullmove + && !isCheck + && ok_to_do_nullmove(pos) + && approximateEval >= beta - NullMoveMargin) + { + ss[ply].currentMove = MOVE_NULL; + + UndoInfo u; + pos.do_null_move(u); + int R = (depth > 7 ? 4 : 3); + + Value nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID); + + // Check for a null capture artifact, if the value without the null capture + // is above beta then there is a good possibility that this is a cut-node. + // We will do an IID later to find a ttMove. + if ( UseNullDrivenIID + && nullValue < beta + && depth > 6 * OnePly + && ttMove == MOVE_NONE + && ss[ply + 1].currentMove != MOVE_NONE + && pos.move_is_capture(ss[ply + 1].currentMove) + && pos.see(ss[ply + 1].currentMove) * PawnValueMidgame + nullValue > beta - IIDMargin) + nullDrivenIID = true; + + pos.undo_null_move(u); + + if (nullValue >= beta) + { + if (depth < 6 * OnePly) + return beta; + + // Do zugzwang verification search + Value v = search(pos, ss, beta, depth-5*OnePly, ply, false, threadID); + if (v >= beta) + return beta; + } 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 + // move which was reduced. If a connection is found, return a fail + // low score (which will cause the reduced move to fail high in the + // parent node, which will trigger a re-search with full depth). + if (nullValue == value_mated_in(ply + 2)) + { + mateThreat = true; + nullDrivenIID = false; + } + ss[ply].threatMove = ss[ply + 1].currentMove; + if ( depth < ThreatDepth + && ss[ply - 1].reduction + && connected_moves(pos, ss[ply - 1].currentMove, ss[ply].threatMove)) + return beta - 1; } - else - return beta; - } - 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 - // move which was reduced. If a connection is found, return a fail - // low score (which will cause the reduced move to fail high in the - // parent node, which will trigger a re-search with full depth). - if(nullValue == value_mated_in(ply+2)) - mateThreat = true; - ss[ply].threatMove = ss[ply+1].currentMove; - if(depth < ThreatDepth && ss[ply-1].reduction && - connected_moves(pos, ss[ply-1].currentMove, ss[ply].threatMove)) - return beta - 1; - } } - // Razoring: - else if(depth < RazorDepth && approximateEval < beta - RazorMargin && - evaluate(pos, ei, threadID) < beta - RazorMargin) { - Value v = qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID); - if(v < beta) - return v; + // Null move search not allowed, try razoring + else if ( (approximateEval < beta - RazorMargin && depth < RazorDepth) + ||(approximateEval < beta - PawnValueMidgame && depth <= OnePly)) + { + Value v = qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID); + if (v < beta) + return v; + } + + // Go with internal iterative deepening if we don't have a TT move + if (UseIIDAtNonPVNodes && ttMove == MOVE_NONE && depth >= 8*OnePly && + evaluate(pos, ei, threadID) >= beta - IIDMargin) + { + search(pos, ss, beta, Min(depth/2, depth-2*OnePly), ply, false, threadID); + ttMove = ss[ply].pv[ply]; } + else if (nullDrivenIID) + { + // The null move failed low due to a suspicious capture. Perhaps we + // are facing a null capture artifact due to the side to move change + // and this is a cut-node. So it's a good time to search for a ttMove. + Move tm = ss[ply].threatMove; + + assert(tm != MOVE_NONE); - // Internal iterative deepening - if(UseIIDAtNonPVNodes && ttMove == MOVE_NONE && depth >= 8*OnePly && - evaluate(pos, ei, threadID) >= beta - IIDMargin) { - search(pos, ss, beta, Min(depth/2, depth-2*OnePly), ply, false, threadID); - ttMove = ss[ply].pv[ply]; + search(pos, ss, beta, Min(depth/2, depth-3*OnePly), ply, false, threadID); + ttMove = ss[ply].pv[ply]; + ss[ply].threatMove = tm; } // Initialize a MovePicker object for the current position, and prepare // to search all moves: - MovePicker mp = MovePicker(pos, false, ttMove, ss[ply].mateKiller, - ss[ply].killer1, ss[ply].killer2, depth); + MovePicker mp = MovePicker(pos, false, ttMove, ss[ply], depth); + Move move, movesSearched[256]; int moveCount = 0; - Value value, bestValue = -VALUE_INFINITE, futilityValue = VALUE_NONE; + Value value, bestValue = -VALUE_INFINITE; Bitboard dcCandidates = mp.discovered_check_candidates(); - bool isCheck = pos.is_check(); - bool useFutilityPruning = - UseFutilityPruning && depth < SelectiveDepth && !isCheck; + Value futilityValue = VALUE_NONE; + bool useFutilityPruning = UseFutilityPruning + && depth < SelectiveDepth + && !isCheck; // Loop through all legal moves until no moves remain or a beta cutoff // occurs. - while(bestValue < beta && !thread_should_stop(threadID) - && (move = mp.get_next_move()) != MOVE_NONE) { - UndoInfo u; - Depth ext, newDepth; + while ( bestValue < beta + && (move = mp.get_next_move()) != MOVE_NONE + && !thread_should_stop(threadID)) + { + assert(move_is_ok(move)); + bool singleReply = (isCheck && mp.number_of_moves() == 1); bool moveIsCheck = pos.move_is_check(move, dcCandidates); bool moveIsCapture = pos.move_is_capture(move); - bool moveIsPassedPawnPush = pos.move_is_passed_pawn_push(move); - assert(move_is_ok(move)); movesSearched[moveCount++] = ss[ply].currentMove = move; - // Decide the new search depth. - ext = extension(pos, move, false, moveIsCheck, singleReply, mateThreat); - newDepth = depth - OnePly + ext; + // Decide the new search depth + bool dangerous; + Depth ext = extension(pos, move, false, moveIsCheck, singleReply, mateThreat, &dangerous); + Depth newDepth = depth - OnePly + ext; // Futility pruning - if(useFutilityPruning && ext == Depth(0) && !moveIsCapture && - !moveIsPassedPawnPush && !move_promotion(move)) { - - if(moveCount >= 2 + int(depth) - && ok_to_prune(pos, move, ss[ply].threatMove, depth)) - continue; + if ( useFutilityPruning + && !dangerous + && !moveIsCapture + && !move_promotion(move)) + { + if ( moveCount >= 2 + int(depth) + && ok_to_prune(pos, move, ss[ply].threatMove, depth)) + continue; - if(depth < 3 * OnePly && approximateEval < beta) { - if(futilityValue == VALUE_NONE) - futilityValue = evaluate(pos, ei, threadID) - + ((depth < 2 * OnePly)? FutilityMargin1 : FutilityMargin2); - if(futilityValue < beta) { - if(futilityValue > bestValue) - bestValue = futilityValue; - continue; + if (depth < 3 * OnePly && approximateEval < beta) + { + if (futilityValue == VALUE_NONE) + futilityValue = evaluate(pos, ei, threadID) + + (depth < 2 * OnePly ? FutilityMargin1 : FutilityMargin2); + + if (futilityValue < beta) + { + if (futilityValue > bestValue) + bestValue = futilityValue; + continue; + } } - } } - // Make and search the move. + // Make and search the move + UndoInfo u; pos.do_move(move, u, dcCandidates); - if(depth >= 2*OnePly && ext == Depth(0) && moveCount >= LMRNonPVMoves - && !moveIsCapture && !move_promotion(move) && !moveIsPassedPawnPush - && !move_is_castle(move) - && move != ss[ply].killer1 && move != ss[ply].killer2) { - ss[ply].reduction = OnePly; - value = -search(pos, ss, -(beta-1), newDepth-OnePly, ply+1, true, - threadID); + // Try to reduce non-pv search depth by one ply if move seems not problematic, + // if the move fails high will be re-searched at full depth. + if ( depth >= 2*OnePly + && moveCount >= LMRNonPVMoves + && !dangerous + && !moveIsCapture + && !move_promotion(move) + && !move_is_castle(move) + && !move_is_killer(move, ss[ply])) + { + ss[ply].reduction = OnePly; + value = -search(pos, ss, -(beta-1), newDepth-OnePly, ply+1, true, threadID); } else - value = beta; - if(value >= beta) { - ss[ply].reduction = Depth(0); - value = -search(pos, ss, -(beta-1), newDepth, ply+1, true, threadID); + value = beta; // Just to trigger next condition + + if (value >= beta) // Go with full depth non-pv search + { + ss[ply].reduction = Depth(0); + value = -search(pos, ss, -(beta-1), newDepth, ply+1, true, threadID); } pos.undo_move(move, u); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); // New best move? - if(value > bestValue) { + if (value > bestValue) + { bestValue = value; - if(value >= beta) - update_pv(ss, ply); - if(value == value_mate_in(ply + 1)) - ss[ply].mateKiller = move; + if (value >= beta) + update_pv(ss, ply); + + if (value == value_mate_in(ply + 1)) + ss[ply].mateKiller = move; } // Split? - if(ActiveThreads > 1 && bestValue < beta && depth >= MinimumSplitDepth - && Iteration <= 99 && idle_thread_exists(threadID) - && !AbortSearch && !thread_should_stop(threadID) - && split(pos, ss, ply, &beta, &beta, &bestValue, depth, &moveCount, - &mp, dcCandidates, threadID, false)) + if ( ActiveThreads > 1 + && bestValue < beta + && depth >= MinimumSplitDepth + && Iteration <= 99 + && idle_thread_exists(threadID) + && !AbortSearch + && !thread_should_stop(threadID) + && split(pos, ss, ply, &beta, &beta, &bestValue, depth, &moveCount, + &mp, dcCandidates, threadID, false)) break; } // All legal moves have been searched. A special case: If there were - // no legal moves, it must be mate or stalemate: - if(moveCount == 0) { - if(pos.is_check()) - return value_mated_in(ply); - else - return VALUE_DRAW; - } + // no legal moves, it must be mate or stalemate. + if (moveCount == 0) + return (pos.is_check() ? value_mated_in(ply) : VALUE_DRAW); // If the search is not aborted, update the transposition table, - // history counters, and killer moves. This code is somewhat messy, - // and definitely needs to be cleaned up. FIXME - if(!AbortSearch && !thread_should_stop(threadID)) { - if(bestValue < beta) - TT.store(pos, value_to_tt(bestValue, ply), depth, MOVE_NONE, - VALUE_TYPE_UPPER); - else { - Move m = ss[ply].pv[ply]; + // history counters, and killer moves. + if (AbortSearch || thread_should_stop(threadID)) + return bestValue; - if(pos.square_is_empty(move_to(m)) && !move_promotion(m) && - !move_is_ep(m)) { - for(int i = 0; i < moveCount - 1; i++) - if(pos.square_is_empty(move_to(movesSearched[i])) - && !move_promotion(movesSearched[i]) - && !move_is_ep(movesSearched[i])) - H.failure(pos.piece_on(move_from(movesSearched[i])), - movesSearched[i]); - H.success(pos.piece_on(move_from(m)), m, depth); - - if(m != ss[ply].killer1) { - ss[ply].killer2 = ss[ply].killer1; - ss[ply].killer1 = m; - } + if (bestValue < beta) + TT.store(pos, value_to_tt(bestValue, ply), depth, MOVE_NONE, VALUE_TYPE_UPPER); + else + { + Move m = ss[ply].pv[ply]; + if (ok_to_history(pos, m)) // Only non capture moves are considered + { + update_history(pos, m, depth, movesSearched, moveCount); + update_killers(m, ss[ply]); } TT.store(pos, value_to_tt(bestValue, ply), depth, m, VALUE_TYPE_LOWER); - } } - return bestValue; } @@ -1260,8 +1364,6 @@ namespace { Value qsearch(Position &pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID) { - Value staticValue, bestValue, value; - EvalInfo ei; assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE); assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE); @@ -1269,104 +1371,128 @@ namespace { assert(ply >= 0 && ply < PLY_MAX); assert(threadID >= 0 && threadID < ActiveThreads); + EvalInfo ei; + // Initialize, and make an early exit in case of an aborted search, // an instant draw, maximum ply reached, etc. - if(AbortSearch || thread_should_stop(threadID)) - return Value(0); + if (AbortSearch || thread_should_stop(threadID)) + return Value(0); init_node(pos, ss, ply, threadID); - if(pos.is_draw()) - return VALUE_DRAW; + if (pos.is_draw()) + return VALUE_DRAW; + + // Transposition table lookup + const TTEntry* tte = TT.retrieve(pos); + if (tte && ok_to_use_TT(tte, depth, beta, ply)) + return value_from_tt(tte->value(), ply); - // Evaluate the position statically: - staticValue = evaluate(pos, ei, threadID); + // Evaluate the position statically + Value staticValue = evaluate(pos, ei, threadID); - if(ply == PLY_MAX - 1) return staticValue; + if (ply == PLY_MAX - 1) + return staticValue; // Initialize "stand pat score", and return it immediately if it is // at least beta. - if(pos.is_check()) - bestValue = -VALUE_INFINITE; - else { - bestValue = staticValue; - if(bestValue >= beta) + Value bestValue = (pos.is_check() ? -VALUE_INFINITE : staticValue); + + if (bestValue >= beta) return bestValue; - if(bestValue > alpha) + + if (bestValue > alpha) alpha = bestValue; - } // Initialize a MovePicker object for the current position, and prepare // to search the moves. Because the depth is <= 0 here, only captures, // queen promotions and checks (only if depth == 0) will be generated. - MovePicker mp = MovePicker(pos, false, MOVE_NONE, MOVE_NONE, MOVE_NONE, - MOVE_NONE, depth); + MovePicker mp = MovePicker(pos, false, MOVE_NONE, EmptySearchStack, depth, &ei); Move move; int moveCount = 0; Bitboard dcCandidates = mp.discovered_check_candidates(); bool isCheck = pos.is_check(); + bool pvNode = (beta - alpha != 1); + bool enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame; // Loop through the moves until no moves remain or a beta cutoff // occurs. - while(alpha < beta && ((move = mp.get_next_move()) != MOVE_NONE)) { - UndoInfo u; - bool moveIsCheck = pos.move_is_check(move, dcCandidates); - bool moveIsPassedPawnPush = pos.move_is_passed_pawn_push(move); - + while ( alpha < beta + && (move = mp.get_next_move()) != MOVE_NONE) + { assert(move_is_ok(move)); moveCount++; ss[ply].currentMove = move; // Futility pruning - if(UseQSearchFutilityPruning && !isCheck && !moveIsCheck && - !move_promotion(move) && !moveIsPassedPawnPush && - beta - alpha == 1 && - pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame) { - Value futilityValue = - staticValue - + Max(pos.midgame_value_of_piece_on(move_to(move)), - pos.endgame_value_of_piece_on(move_to(move))) - + FutilityMargin0 - + ei.futilityMargin; - if(futilityValue < alpha) { - if(futilityValue > bestValue) - bestValue = futilityValue; - continue; - } + if ( UseQSearchFutilityPruning + && enoughMaterial + && !isCheck + && !pvNode + && !move_promotion(move) + && !pos.move_is_check(move, dcCandidates) + && !pos.move_is_passed_pawn_push(move)) + { + Value futilityValue = staticValue + + Max(pos.midgame_value_of_piece_on(move_to(move)), + pos.endgame_value_of_piece_on(move_to(move))) + + FutilityMargin0 + + ei.futilityMargin; + + if (futilityValue < alpha) + { + if (futilityValue > bestValue) + bestValue = futilityValue; + continue; + } } - // Don't search captures and checks with negative SEE values. - if(!isCheck && !move_promotion(move) && - pos.midgame_value_of_piece_on(move_from(move)) > - pos.midgame_value_of_piece_on(move_to(move)) && - pos.see(move) < 0) - continue; + // Don't search captures and checks with negative SEE values + if ( !isCheck + && !move_promotion(move) + && (pos.midgame_value_of_piece_on(move_from(move)) > + pos.midgame_value_of_piece_on(move_to(move))) + && pos.see(move) < 0) + continue; // Make and search the move. + UndoInfo u; pos.do_move(move, u, dcCandidates); - value = -qsearch(pos, ss, -beta, -alpha, depth-OnePly, ply+1, threadID); + Value value = -qsearch(pos, ss, -beta, -alpha, depth-OnePly, ply+1, threadID); pos.undo_move(move, u); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); // New best move? - if(value > bestValue) { - bestValue = value; - if(value > alpha) { - alpha = value; - update_pv(ss, ply); - } - } + if (value > bestValue) + { + bestValue = value; + if (value > alpha) + { + alpha = value; + update_pv(ss, ply); + } + } } // All legal moves have been searched. A special case: If we're in check // and no legal moves were found, it is checkmate: - if(pos.is_check() && moveCount == 0) // Mate! - return value_mated_in(ply); + if (pos.is_check() && moveCount == 0) // Mate! + return value_mated_in(ply); assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); + // Update transposition table + TT.store(pos, value_to_tt(bestValue, ply), depth, MOVE_NONE, VALUE_TYPE_EXACT); + + // Update killers only for good check moves + Move m = ss[ply].currentMove; + if (alpha >= beta && ok_to_history(pos, m)) // Only non capture moves are considered + { + // Wrong to update history when depth is <= 0 + update_killers(m, ss[ply]); + } return bestValue; } @@ -1380,6 +1506,7 @@ namespace { // care of after we return from the split point. void sp_search(SplitPoint *sp, int threadID) { + assert(threadID >= 0 && threadID < ActiveThreads); assert(ActiveThreads > 1); @@ -1387,73 +1514,84 @@ namespace { SearchStack *ss = sp->sstack[threadID]; Value value; Move move; - int moveCount = sp->moves; bool isCheck = pos.is_check(); - bool useFutilityPruning = - UseFutilityPruning && sp->depth < SelectiveDepth && !isCheck; + bool useFutilityPruning = UseFutilityPruning + && sp->depth < SelectiveDepth + && !isCheck; + + while ( sp->bestValue < sp->beta + && !thread_should_stop(threadID) + && (move = sp->mp->get_next_move(sp->lock)) != MOVE_NONE) + { + assert(move_is_ok(move)); - while(sp->bestValue < sp->beta && !thread_should_stop(threadID) - && (move = sp->mp->get_next_move(sp->lock)) != MOVE_NONE) { - UndoInfo u; - Depth ext, newDepth; bool moveIsCheck = pos.move_is_check(move, sp->dcCandidates); bool moveIsCapture = pos.move_is_capture(move); - bool moveIsPassedPawnPush = pos.move_is_passed_pawn_push(move); - - assert(move_is_ok(move)); lock_grab(&(sp->lock)); - sp->moves++; - moveCount = sp->moves; + int moveCount = ++sp->moves; lock_release(&(sp->lock)); ss[sp->ply].currentMove = move; // Decide the new search depth. - ext = extension(pos, move, false, moveIsCheck, false, false); - newDepth = sp->depth - OnePly + ext; + bool dangerous; + Depth ext = extension(pos, move, false, moveIsCheck, false, false, &dangerous); + Depth newDepth = sp->depth - OnePly + ext; // Prune? - if(useFutilityPruning && ext == Depth(0) && !moveIsCapture - && !moveIsPassedPawnPush && !move_promotion(move) - && moveCount >= 2 + int(sp->depth) - && ok_to_prune(pos, move, ss[sp->ply].threatMove, sp->depth)) + if ( useFutilityPruning + && !dangerous + && !moveIsCapture + && !move_promotion(move) + && moveCount >= 2 + int(sp->depth) + && ok_to_prune(pos, move, ss[sp->ply].threatMove, sp->depth)) continue; // Make and search the move. + UndoInfo u; pos.do_move(move, u, sp->dcCandidates); - if(ext == Depth(0) && moveCount >= LMRNonPVMoves - && !moveIsCapture && !move_promotion(move) && !moveIsPassedPawnPush - && !move_is_castle(move) - && move != ss[sp->ply].killer1 && move != ss[sp->ply].killer2) { - ss[sp->ply].reduction = OnePly; - value = -search(pos, ss, -(sp->beta-1), newDepth - OnePly, sp->ply+1, - true, threadID); + + // Try to reduce non-pv search depth by one ply if move seems not problematic, + // if the move fails high will be re-searched at full depth. + if ( !dangerous + && moveCount >= LMRNonPVMoves + && !moveIsCapture + && !move_promotion(move) + && !move_is_castle(move) + && !move_is_killer(move, ss[sp->ply])) + { + ss[sp->ply].reduction = OnePly; + value = -search(pos, ss, -(sp->beta-1), newDepth - OnePly, sp->ply+1, true, threadID); } else - value = sp->beta; - if(value >= sp->beta) { - ss[sp->ply].reduction = Depth(0); - value = -search(pos, ss, -(sp->beta - 1), newDepth, sp->ply+1, true, - threadID); + value = sp->beta; // Just to trigger next condition + + if (value >= sp->beta) // Go with full depth non-pv search + { + ss[sp->ply].reduction = Depth(0); + value = -search(pos, ss, -(sp->beta - 1), newDepth, sp->ply+1, true, threadID); } pos.undo_move(move, u); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); - if(thread_should_stop(threadID)) - break; + if (thread_should_stop(threadID)) + break; // New best move? lock_grab(&(sp->lock)); - if(value > sp->bestValue && !thread_should_stop(threadID)) { - sp->bestValue = value; - if(sp->bestValue >= sp->beta) { - sp_update_pv(sp->parentSstack, ss, sp->ply); - for(int i = 0; i < ActiveThreads; i++) - if(i != threadID && (i == sp->master || sp->slaves[i])) - Threads[i].stop = true; - sp->finished = true; + if (value > sp->bestValue && !thread_should_stop(threadID)) + { + sp->bestValue = value; + if (sp->bestValue >= sp->beta) + { + sp_update_pv(sp->parentSstack, ss, sp->ply); + for (int i = 0; i < ActiveThreads; i++) + if (i != threadID && (i == sp->master || sp->slaves[i])) + Threads[i].stop = true; + + sp->finished = true; } } lock_release(&(sp->lock)); @@ -1463,10 +1601,10 @@ namespace { // If this is the master thread and we have been asked to stop because of // a beta cutoff higher up in the tree, stop all slave threads: - if(sp->master == threadID && thread_should_stop(threadID)) - for(int i = 0; i < ActiveThreads; i++) - if(sp->slaves[i]) - Threads[i].stop = true; + if (sp->master == threadID && thread_should_stop(threadID)) + for (int i = 0; i < ActiveThreads; i++) + if (sp->slaves[i]) + Threads[i].stop = true; sp->cpus--; sp->slaves[threadID] = 0; @@ -1484,6 +1622,7 @@ namespace { // after we return from the split point. void sp_search_pv(SplitPoint *sp, int threadID) { + assert(threadID >= 0 && threadID < ActiveThreads); assert(ActiveThreads > 1); @@ -1491,15 +1630,13 @@ namespace { SearchStack *ss = sp->sstack[threadID]; Value value; Move move; - int moveCount = sp->moves; - while(sp->alpha < sp->beta && !thread_should_stop(threadID) - && (move = sp->mp->get_next_move(sp->lock)) != MOVE_NONE) { - UndoInfo u; - Depth ext, newDepth; + while ( sp->alpha < sp->beta + && !thread_should_stop(threadID) + && (move = sp->mp->get_next_move(sp->lock)) != MOVE_NONE) + { bool moveIsCheck = pos.move_is_check(move, sp->dcCandidates); bool moveIsCapture = pos.move_is_capture(move); - bool moveIsPassedPawnPush = pos.move_is_passed_pawn_push(move); assert(move_is_ok(move)); @@ -1507,74 +1644,87 @@ namespace { PawnValueMidgame : pos.midgame_value_of_piece_on(move_to(move)); lock_grab(&(sp->lock)); - sp->moves++; - moveCount = sp->moves; + int moveCount = ++sp->moves; lock_release(&(sp->lock)); ss[sp->ply].currentMove = move; // Decide the new search depth. - ext = extension(pos, move, true, moveIsCheck, false, false); - newDepth = sp->depth - OnePly + ext; + bool dangerous; + Depth ext = extension(pos, move, true, moveIsCheck, false, false, &dangerous); + Depth newDepth = sp->depth - OnePly + ext; // Make and search the move. + UndoInfo u; pos.do_move(move, u, sp->dcCandidates); - if(ext == Depth(0) && moveCount >= LMRPVMoves && !moveIsCapture - && !move_promotion(move) && !moveIsPassedPawnPush - && !move_is_castle(move) - && move != ss[sp->ply].killer1 && move != ss[sp->ply].killer2) { - ss[sp->ply].reduction = OnePly; - value = -search(pos, ss, -sp->alpha, newDepth - OnePly, sp->ply+1, - true, threadID); + + // Try to reduce non-pv search depth by one ply if move seems not problematic, + // if the move fails high will be re-searched at full depth. + if ( !dangerous + && moveCount >= LMRPVMoves + && !moveIsCapture + && !move_promotion(move) + && !move_is_castle(move) + && !move_is_killer(move, ss[sp->ply])) + { + ss[sp->ply].reduction = OnePly; + value = -search(pos, ss, -sp->alpha, newDepth - OnePly, sp->ply+1, true, threadID); } else - value = sp->alpha + 1; - if(value > sp->alpha) { - ss[sp->ply].reduction = Depth(0); - value = -search(pos, ss, -sp->alpha, newDepth, sp->ply+1, true, - threadID); - if(value > sp->alpha && value < sp->beta) { - if(sp->ply == 1 && RootMoveNumber == 1) - // When the search fails high at ply 1 while searching the first - // move at the root, set the flag failHighPly1. This is used for - // time managment: We don't want to stop the search early in - // such cases, because resolving the fail high at ply 1 could - // result in a big drop in score at the root. - Threads[threadID].failHighPly1 = true; - value = -search_pv(pos, ss, -sp->beta, -sp->alpha, newDepth, - sp->ply+1, threadID); - Threads[threadID].failHighPly1 = false; + value = sp->alpha + 1; // Just to trigger next condition + + if (value > sp->alpha) // Go with full depth non-pv search + { + ss[sp->ply].reduction = Depth(0); + value = -search(pos, ss, -sp->alpha, newDepth, sp->ply+1, true, threadID); + + if (value > sp->alpha && value < sp->beta) + { + // When the search fails high at ply 1 while searching the first + // move at the root, set the flag failHighPly1. This is used for + // time managment: We don't want to stop the search early in + // such cases, because resolving the fail high at ply 1 could + // result in a big drop in score at the root. + if (sp->ply == 1 && RootMoveNumber == 1) + Threads[threadID].failHighPly1 = true; + + value = -search_pv(pos, ss, -sp->beta, -sp->alpha, newDepth, sp->ply+1, threadID); + Threads[threadID].failHighPly1 = false; } } pos.undo_move(move, u); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); - if(thread_should_stop(threadID)) - break; + if (thread_should_stop(threadID)) + break; // New best move? lock_grab(&(sp->lock)); - if(value > sp->bestValue && !thread_should_stop(threadID)) { - sp->bestValue = value; - if(value > sp->alpha) { - sp->alpha = value; - sp_update_pv(sp->parentSstack, ss, sp->ply); - if(value == value_mate_in(sp->ply + 1)) - ss[sp->ply].mateKiller = move; - if(value >= sp->beta) { - for(int i = 0; i < ActiveThreads; i++) - if(i != threadID && (i == sp->master || sp->slaves[i])) - Threads[i].stop = true; - sp->finished = true; - } + if (value > sp->bestValue && !thread_should_stop(threadID)) + { + sp->bestValue = value; + if (value > sp->alpha) + { + sp->alpha = value; + sp_update_pv(sp->parentSstack, ss, sp->ply); + if (value == value_mate_in(sp->ply + 1)) + ss[sp->ply].mateKiller = move; + + if(value >= sp->beta) + { + for(int i = 0; i < ActiveThreads; i++) + if(i != threadID && (i == sp->master || sp->slaves[i])) + Threads[i].stop = true; + + sp->finished = true; + } } // If we are at ply 1, and we are searching the first root move at // ply 0, set the 'Problem' variable if the score has dropped a lot // (from the computer's point of view) since the previous iteration: - if(Iteration >= 2 && - -value <= ValueByIteration[Iteration-1] - ProblemMargin) - Problem = true; + if (Iteration >= 2 && -value <= ValueByIteration[Iteration-1] - ProblemMargin) + Problem = true; } lock_release(&(sp->lock)); } @@ -1583,10 +1733,10 @@ namespace { // If this is the master thread and we have been asked to stop because of // a beta cutoff higher up in the tree, stop all slave threads: - if(sp->master == threadID && thread_should_stop(threadID)) - for(int i = 0; i < ActiveThreads; i++) - if(sp->slaves[i]) - Threads[i].stop = true; + if (sp->master == threadID && thread_should_stop(threadID)) + for (int i = 0; i < ActiveThreads; i++) + if (sp->slaves[i]) + Threads[i].stop = true; sp->cpus--; sp->slaves[threadID] = 0; @@ -1594,20 +1744,6 @@ namespace { lock_release(&(sp->lock)); } - // ok_to_use_TT() returns true if a transposition table score - // can be used at a given point in search. - - bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply) { - - Value v = value_from_tt(tte->value(), ply); - - return ( tte->depth() >= depth - || v >= Max(value_mate_in(100), beta) - || v < Min(value_mated_in(100), beta)) - - && ( (is_lower_bound(tte->type()) && v >= beta) - || (is_upper_bound(tte->type()) && v < beta)); - } /// The RootMove class @@ -1760,17 +1896,28 @@ namespace { // init_search_stack() initializes a search stack at the beginning of a // new search from the root. + void init_search_stack(SearchStack& ss) { + + ss.pv[0] = MOVE_NONE; + ss.pv[1] = MOVE_NONE; + ss.currentMove = MOVE_NONE; + ss.threatMove = MOVE_NONE; + ss.reduction = Depth(0); + for (int j = 0; j < KILLER_MAX; j++) + ss.killers[j] = MOVE_NONE; + } void init_search_stack(SearchStack ss[]) { - for(int i = 0; i < 3; i++) { - ss[i].pv[i] = MOVE_NONE; - ss[i].pv[i+1] = MOVE_NONE; - ss[i].currentMove = MOVE_NONE; - ss[i].mateKiller = MOVE_NONE; - ss[i].killer1 = MOVE_NONE; - ss[i].killer2 = MOVE_NONE; - ss[i].threatMove = MOVE_NONE; - ss[i].reduction = Depth(0); + + for (int i = 0; i < 3; i++) + { + ss[i].pv[i] = MOVE_NONE; + ss[i].pv[i+1] = MOVE_NONE; + ss[i].currentMove = MOVE_NONE; + ss[i].threatMove = MOVE_NONE; + ss[i].reduction = Depth(0); + for (int j = 0; j < KILLER_MAX; j++) + ss[i].killers[j] = MOVE_NONE; } } @@ -1794,13 +1941,13 @@ namespace { NodesSincePoll = 0; } } - ss[ply].pv[ply] = ss[ply].pv[ply+1] = ss[ply].currentMove = MOVE_NONE; ss[ply+2].mateKiller = MOVE_NONE; - ss[ply+2].killer1 = ss[ply+2].killer2 = MOVE_NONE; ss[ply].threatMove = MOVE_NONE; ss[ply].reduction = Depth(0); ss[ply].currentMoveCaptureValue = Value(0); + for (int j = 0; j < KILLER_MAX; j++) + ss[ply+2].killers[j] = MOVE_NONE; if(Threads[threadID].printCurrentLine) print_current_line(ss, ply, threadID); @@ -1903,32 +2050,70 @@ namespace { } + // move_is_killer() checks if the given move is among the + // killer moves of that ply. + + bool move_is_killer(Move m, const SearchStack& ss) { + + const Move* k = ss.killers; + for (int i = 0; i < KILLER_MAX; i++, k++) + if (*k == m) + return true; + + return false; + } + + // extension() decides whether a move should be searched with normal depth, // or with extended depth. Certain classes of moves (checking moves, in - // particular) are searched with bigger depth than ordinary moves. + // particular) are searched with bigger depth than ordinary moves and in + // any case are marked as 'dangerous'. Note that also if a move is not + // extended, as example because the corresponding UCI option is set to zero, + // the move is marked as 'dangerous' so, at least, we avoid to prune it. + + Depth extension(const Position &pos, Move m, bool pvNode, bool check, + bool singleReply, bool mateThreat, bool* dangerous) { - Depth extension(const Position &pos, Move m, bool pvNode, - bool check, bool singleReply, bool mateThreat) { Depth result = Depth(0); + *dangerous = check || singleReply || mateThreat; + + if (check) + result += CheckExtension[pvNode]; + + if (singleReply) + result += SingleReplyExtension[pvNode]; - if(check) - result += CheckExtension[pvNode]; - if(singleReply) - result += SingleReplyExtension[pvNode]; - if(pos.move_is_pawn_push_to_7th(m)) - result += PawnPushTo7thExtension[pvNode]; - if(pos.move_is_passed_pawn_push(m)) - result += PassedPawnExtension[pvNode]; - if(mateThreat) - result += MateThreatExtension[pvNode]; - if(pos.midgame_value_of_piece_on(move_to(m)) >= RookValueMidgame - && (pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) - - pos.midgame_value_of_piece_on(move_to(m)) == Value(0)) - && !move_promotion(m)) - result += PawnEndgameExtension[pvNode]; - if(pvNode && pos.move_is_capture(m) - && pos.type_of_piece_on(move_to(m)) != PAWN && pos.see(m) >= 0) - result += OnePly/2; + if (mateThreat) + result += MateThreatExtension[pvNode]; + + if (pos.move_is_pawn_push_to_7th(m)) + { + result += PawnPushTo7thExtension[pvNode]; + *dangerous = true; + } + if (pos.move_is_passed_pawn_push(m)) + { + result += PassedPawnExtension[pvNode]; + *dangerous = true; + } + + if ( pos.midgame_value_of_piece_on(move_to(m)) >= RookValueMidgame + && ( pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) + - pos.midgame_value_of_piece_on(move_to(m)) == Value(0)) + && !move_promotion(m)) + { + result += PawnEndgameExtension[pvNode]; + *dangerous = true; + } + + if ( pvNode + && pos.move_is_capture(m) + && pos.type_of_piece_on(move_to(m)) != PAWN + && pos.see(m) >= 0) + { + result += OnePly/2; + *dangerous = true; + } return Min(result, OnePly); } @@ -2000,6 +2185,62 @@ namespace { } + // ok_to_use_TT() returns true if a transposition table score + // can be used at a given point in search. + + bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply) { + + Value v = value_from_tt(tte->value(), ply); + + return ( tte->depth() >= depth + || v >= Max(value_mate_in(100), beta) + || v < Min(value_mated_in(100), beta)) + + && ( (is_lower_bound(tte->type()) && v >= beta) + || (is_upper_bound(tte->type()) && v < beta)); + } + + + // ok_to_history() returns true if a move m can be stored + // in history. Should be a non capturing move nor a promotion. + + bool ok_to_history(const Position& pos, Move m) { + + return !pos.move_is_capture(m) && !move_promotion(m); + } + + + // update_history() registers a good move that produced a beta-cutoff + // in history and marks as failures all the other moves of that ply. + + void update_history(const Position& pos, Move m, Depth depth, + Move movesSearched[], int moveCount) { + + H.success(pos.piece_on(move_from(m)), m, depth); + + for (int i = 0; i < moveCount - 1; i++) + { + assert(m != movesSearched[i]); + if (ok_to_history(pos, movesSearched[i])) + H.failure(pos.piece_on(move_from(movesSearched[i])), movesSearched[i]); + } + } + + + // update_killers() add a good move that produced a beta-cutoff + // among the killer moves of that ply. + + void update_killers(Move m, SearchStack& ss) { + + if (m == ss.killers[0]) + return; + + for (int i = KILLER_MAX - 1; i > 0; i--) + ss.killers[i] = ss.killers[i - 1]; + + ss.killers[0] = m; + } + // fail_high_ply_1() checks if some thread is currently resolving a fail // high at ply 1 at the node below the first root node. This information // is used for time managment. @@ -2033,62 +2274,70 @@ namespace { // search. void poll() { - int t, data; - static int lastInfoTime; - t = current_search_time(); + static int lastInfoTime; + int t = current_search_time(); // Poll for input - data = Bioskey(); - if(data) { - char input[256]; - if(fgets(input, 255, stdin) == NULL) - strcpy(input, "quit\n"); - if(strncmp(input, "quit", 4) == 0) { - AbortSearch = true; - PonderSearch = false; - Quit = true; - } - else if(strncmp(input, "stop", 4) == 0) { - AbortSearch = true; - PonderSearch = false; - } - else if(strncmp(input, "ponderhit", 9) == 0) - ponderhit(); - } + if (Bioskey()) + { + // We are line oriented, don't read single chars + std::string command; + if (!std::getline(std::cin, command)) + command = "quit"; - // Print search information - if(t < 1000) - lastInfoTime = 0; - else if(lastInfoTime > t) - // HACK: Must be a new search where we searched less than - // NodesBetweenPolls nodes during the first second of search. - lastInfoTime = 0; - else if(t - lastInfoTime >= 1000) { - lastInfoTime = t; - lock_grab(&IOLock); - std::cout << "info nodes " << nodes_searched() << " nps " << nps() - << " time " << t << " hashfull " << TT.full() << std::endl; - lock_release(&IOLock); - if(ShowCurrentLine) - Threads[0].printCurrentLine = true; + if (command == "quit") + { + AbortSearch = true; + PonderSearch = false; + Quit = true; + } + else if(command == "stop") + { + AbortSearch = true; + PonderSearch = false; + } + else if(command == "ponderhit") + ponderhit(); } + // Print search information + if (t < 1000) + lastInfoTime = 0; + + else if (lastInfoTime > t) + // HACK: Must be a new search where we searched less than + // NodesBetweenPolls nodes during the first second of search. + lastInfoTime = 0; + else if (t - lastInfoTime >= 1000) + { + lastInfoTime = t; + lock_grab(&IOLock); + if (dbg_show_mean) + dbg_print_mean(); + + if (dbg_show_hit_rate) + dbg_print_hit_rate(); + + std::cout << "info nodes " << nodes_searched() << " nps " << nps() + << " time " << t << " hashfull " << TT.full() << std::endl; + lock_release(&IOLock); + if (ShowCurrentLine) + Threads[0].printCurrentLine = true; + } // Should we stop the search? - if(!PonderSearch && Iteration >= 2 && - (!InfiniteSearch && (t > AbsoluteMaxSearchTime || - (RootMoveNumber == 1 && - t > MaxSearchTime + ExtraSearchTime) || - (!FailHigh && !fail_high_ply_1() && !Problem && - t > 6*(MaxSearchTime + ExtraSearchTime))))) - AbortSearch = true; + if (PonderSearch) + return; - if(!PonderSearch && ExactMaxTime && t >= ExactMaxTime) - AbortSearch = true; + bool overTime = t > AbsoluteMaxSearchTime + || (RootMoveNumber == 1 && t > MaxSearchTime + ExtraSearchTime) + || ( !FailHigh && !fail_high_ply_1() && !Problem + && t > 6*(MaxSearchTime + ExtraSearchTime)); - if(!PonderSearch && Iteration >= 3 && MaxNodes - && nodes_searched() >= MaxNodes) - AbortSearch = true; + if ( (Iteration >= 2 && (!InfiniteSearch && overTime)) + || (ExactMaxTime && t >= ExactMaxTime) + || (Iteration >= 3 && MaxNodes && nodes_searched() >= MaxNodes)) + AbortSearch = true; }