X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=679ebbbd1e457a8c111bfdde2aa3b75ed1202af6;hp=4408475341ac9deea60df927609c4bfd61e79ae0;hb=0af3af5d253b7be6c4358b148b768472a75b5d99;hpb=be9aba2fa0b9c9fa1d55a3c9bc87def967fa5911 diff --git a/src/search.cpp b/src/search.cpp index 44084753..679ebbbd 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -17,10 +17,10 @@ along with this program. If not, see . */ +#include #include #include #include -#include #include #include #include @@ -30,7 +30,6 @@ #include "evaluate.h" #include "history.h" #include "misc.h" -#include "move.h" #include "movegen.h" #include "movepick.h" #include "search.h" @@ -39,9 +38,18 @@ #include "tt.h" #include "ucioption.h" +namespace Search { + + volatile SignalsType Signals; + LimitsType Limits; + std::vector SearchMoves; + Position RootPosition; +} + using std::cout; using std::endl; using std::string; +using namespace Search; namespace { @@ -52,15 +60,21 @@ namespace { enum NodeType { Root, PV, NonPV, SplitPointRoot, SplitPointPV, SplitPointNonPV }; // RootMove struct is used for moves at the root of the tree. For each root - // move, we store a score, a node count, and a PV (really a refutation - // in the case of moves which fail low). Score is normally set at - // -VALUE_INFINITE for all non-pv moves. + // move we store a score, a node count, and a PV (really a refutation in the + // case of moves which fail low). Score is normally set at -VALUE_INFINITE for + // all non-pv moves. struct RootMove { - // RootMove::operator<() is the comparison function used when - // sorting the moves. A move m1 is considered to be better - // than a move m2 if it has an higher score + RootMove(){} + RootMove(Move m) { + nodes = 0; + score = prevScore = -VALUE_INFINITE; + pv.push_back(m); + pv.push_back(MOVE_NONE); + } + bool operator<(const RootMove& m) const { return score < m.score; } + bool operator==(const Move& m) const { return pv[0] == m; } void extract_pv_from_tt(Position& pos); void insert_pv_in_tt(Position& pos); @@ -71,15 +85,6 @@ namespace { std::vector pv; }; - // RootMoveList struct is mainly a std::vector of RootMove objects - struct RootMoveList : public std::vector { - - void init(Position& pos, Move searchMoves[]); - RootMove* find(const Move& m, int startIndex = 0); - - int bestMoveChanges; - }; - /// Constants @@ -87,8 +92,6 @@ namespace { const bool Slidings[18] = { 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1 }; inline bool piece_is_slider(Piece p) { return Slidings[p]; } - // Step 6. Razoring - // Maximum depth for razoring const Depth RazorDepth = 4 * ONE_PLY; @@ -98,8 +101,6 @@ namespace { // Maximum depth for use of dynamic threat detection when null move fails low const Depth ThreatDepth = 5 * ONE_PLY; - // Step 9. Internal iterative deepening - // Minimum depth for use of internal iterative deepening const Depth IIDDepth[] = { 8 * ONE_PLY, 5 * ONE_PLY }; @@ -107,19 +108,9 @@ namespace { // when the static evaluation is bigger then beta - IIDMargin. const Value IIDMargin = Value(0x100); - // Step 11. Decide the new search depth - - // Extensions. Array index 0 is used for non-PV nodes, index 1 for PV nodes - const Depth CheckExtension[] = { ONE_PLY / 2, ONE_PLY / 1 }; - const Depth PawnEndgameExtension[] = { ONE_PLY / 1, ONE_PLY / 1 }; - const Depth PawnPushTo7thExtension[] = { ONE_PLY / 2, ONE_PLY / 2 }; - const Depth PassedPawnExtension[] = { DEPTH_ZERO, ONE_PLY / 2 }; - // Minimum depth for use of singular extension const Depth SingularExtensionDepth[] = { 8 * ONE_PLY, 6 * ONE_PLY }; - // Step 12. Futility pruning - // Futility margin for quiescence search const Value FutilityMarginQS = Value(0x80); @@ -129,7 +120,7 @@ namespace { inline Value futility_margin(Depth d, int mn) { - return d < 7 * ONE_PLY ? FutilityMargins[Max(d, 1)][Min(mn, 63)] + return d < 7 * ONE_PLY ? FutilityMargins[std::max(int(d), 1)][std::min(mn, 63)] : 2 * VALUE_INFINITE; } @@ -138,59 +129,39 @@ namespace { return d < 16 * ONE_PLY ? FutilityMoveCounts[d] : MAX_MOVES; } - // Step 14. Reduced search - // Reduction lookup tables (initialized at startup) and their access function int8_t Reductions[2][64][64]; // [pv][depth][moveNumber] template inline Depth reduction(Depth d, int mn) { - return (Depth) Reductions[PvNode][Min(d / ONE_PLY, 63)][Min(mn, 63)]; + return (Depth) Reductions[PvNode][std::min(int(d) / ONE_PLY, 63)][std::min(mn, 63)]; } // Easy move margin. An easy move candidate must be at least this much // better than the second best move. - const Value EasyMoveMargin = Value(0x200); + const Value EasyMoveMargin = Value(0x150); /// Namespace variables - // Root move list - RootMoveList Rml; - - // MultiPV mode - int MultiPV, UCIMultiPV, MultiPVIteration; - - // Time management variables - bool StopOnPonderhit, FirstRootMove, StopRequest, QuitRequest, AspirationFailLow; + std::vector RootMoves; + size_t MultiPV, UCIMultiPV, MultiPVIdx; TimeManager TimeMgr; - SearchLimits Limits; - - // Log file - std::ofstream LogFile; - - // Skill level adjustment + int BestMoveChanges; int SkillLevel; bool SkillLevelEnabled; - - // 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. - int NodesSincePoll; - int NodesBetweenPolls = 30000; - - // History table History H; /// Local functions - Move id_loop(Position& pos, Move searchMoves[], Move* ponderMove); + Move id_loop(Position& pos, Move* ponderMove); template - Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth); + Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth); template - Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth); + Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth); bool check_is_dangerous(Position &pos, Move move, Value futilityBase, Value beta, Value *bValue); bool connected_moves(const Position& pos, Move m1, Move m2); @@ -200,31 +171,25 @@ namespace { 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_gains(const Position& pos, Move move, Value before, Value after); void do_skill_level(Move* best, Move* ponder); - - int current_search_time(int set = 0); + int elapsed_time(bool reset = false); string score_to_uci(Value v, Value alpha = -VALUE_INFINITE, Value beta = VALUE_INFINITE); - string speed_to_uci(int64_t nodes); - string pv_to_uci(const Move pv[], int pvNum, bool chess960); - string pretty_pv(Position& pos, int depth, Value score, int time, Move pv[]); - string depth_to_uci(Depth depth); - void poll(const Position& pos); - void wait_for_stop_or_ponderhit(); - - // MovePickerExt template class extends MovePicker and allows to choose at compile - // time the proper moves source according to the type of node. In the default case - // we simply create and use a standard MovePicker object. + void pv_info_to_log(Position& pos, int depth, Value score, int time, Move pv[]); + void pv_info_to_uci(const Position& pos, int depth, Value alpha, Value beta); + + // MovePickerExt class template extends MovePicker and allows to choose at + // compile time the proper moves source according to the type of node. In the + // default case we simply create and use a standard MovePicker object. template struct MovePickerExt : public MovePicker { - MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b) + MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, Stack* ss, Value b) : MovePicker(p, ttm, d, h, ss, b) {} }; // In case of a SpNode we use split point's shared MovePicker object as moves source template<> struct MovePickerExt : public MovePicker { - MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b) + MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, Stack* ss, Value b) : MovePicker(p, ttm, d, h, ss, b), mp(ss->sp->mp) {} Move get_next_move() { return mp->get_next_move(); } @@ -239,63 +204,42 @@ namespace { return os << move_to_uci(m, chess960); } - // When formatting a move for std::cout we must know if we are in Chess960 - // or not. To keep using the handy operator<<() on the move the trick is to - // embed this flag in the stream itself. Function-like named enum set960 is - // used as a custom manipulator and the stream internal general-purpose array, - // accessed through ios_base::iword(), is used to pass the flag to the move's - // operator<<() that will read it to properly format castling moves. + // When formatting a move for std::cout we must know if we are in Chess960 or + // not. To keep using the handy operator<<() on the move the trick is to embed + // this flag in the stream itself. Function-like named enum set960 is used as + // a custom manipulator and the stream internal general-purpose array, accessed + // through ios_base::iword(), is used to pass the flag to the move's operator<< + // that will read it to properly format castling moves. enum set960 {}; - std::ostream& operator<< (std::ostream& os, const set960& f) { + std::ostream& operator<<(std::ostream& os, const set960& f) { - os.iword(0) = int(f); + os.iword(0) = f; return os; } - // extension() decides whether a move should be searched with normal depth, - // or with extended depth. Certain classes of moves (checking moves, in - // particular) are searched with bigger depth than ordinary moves and in - // any case are marked as 'dangerous'. Note that also if a move is not - // extended, as example because the corresponding UCI option is set to zero, - // the move is marked as 'dangerous' so, at least, we avoid to prune it. - template - FORCE_INLINE Depth extension(const Position& pos, Move m, bool captureOrPromotion, - bool moveIsCheck, bool* dangerous) { - assert(m != MOVE_NONE); - - Depth result = DEPTH_ZERO; - *dangerous = moveIsCheck; + // is_dangerous() checks whether a move belongs to some classes of known + // 'dangerous' moves so that we avoid to prune it. + FORCE_INLINE bool is_dangerous(const Position& pos, Move m, bool captureOrPromotion) { - if (moveIsCheck && pos.see_sign(m) >= 0) - result += CheckExtension[PvNode]; - - if (piece_type(pos.piece_on(move_from(m))) == PAWN) + // Test for a pawn pushed to 7th or a passed pawn move + if (type_of(pos.piece_on(move_from(m))) == PAWN) { Color c = pos.side_to_move(); - if (relative_rank(c, move_to(m)) == RANK_7) - { - result += PawnPushTo7thExtension[PvNode]; - *dangerous = true; - } - if (pos.pawn_is_passed(c, move_to(m))) - { - result += PassedPawnExtension[PvNode]; - *dangerous = true; - } + if ( relative_rank(c, move_to(m)) == RANK_7 + || pos.pawn_is_passed(c, move_to(m))) + return true; } + // Test for a capture that triggers a pawn endgame if ( captureOrPromotion - && piece_type(pos.piece_on(move_to(m))) != PAWN + && type_of(pos.piece_on(move_to(m))) != PAWN && ( pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) - - piece_value_midgame(pos.piece_on(move_to(m))) == VALUE_ZERO) - && !move_is_special(m)) - { - result += PawnEndgameExtension[PvNode]; - *dangerous = true; - } + - PieceValueMidgame[pos.piece_on(move_to(m))] == VALUE_ZERO) + && !is_special(m)) + return true; - return Min(result, ONE_PLY); + return false; } } // namespace @@ -303,7 +247,7 @@ namespace { /// init_search() is called during startup to initialize various lookup tables -void init_search() { +void Search::init() { int d; // depth (ONE_PLY == 2) int hd; // half depth (ONE_PLY == 1) @@ -331,20 +275,17 @@ void init_search() { /// perft() is our utility to verify move generation. All the leaf nodes up to /// the given depth are generated and counted and the sum returned. -int64_t perft(Position& pos, Depth depth) { +int64_t Search::perft(Position& pos, Depth depth) { StateInfo st; int64_t sum = 0; - // Generate all legal moves MoveList ml(pos); - // If we are at the last ply we don't need to do and undo - // the moves, just to count them. + // At the last ply just return the number of moves (leaf nodes) if (depth <= ONE_PLY) return ml.size(); - // Loop through all legal moves CheckInfo ci(pos); for ( ; !ml.end(); ++ml) { @@ -356,123 +297,110 @@ int64_t perft(Position& pos, Depth depth) { } -/// think() is the external interface to Stockfish's search, and is called when -/// the program receives the UCI 'go' command. It initializes various global -/// variables, and calls id_loop(). It returns false when a "quit" command is -/// received during the search. +/// think() is the external interface to Stockfish's search, and is called by the +/// main thread when the program receives the UCI 'go' command. It searches from +/// RootPosition and at the end prints the "bestmove" to output. -bool think(Position& pos, const SearchLimits& limits, Move searchMoves[]) { +void Search::think() { - static Book book; + static Book book; // Defined static to initialize the PRNG only once - // Initialize global search-related variables - StopOnPonderhit = StopRequest = QuitRequest = AspirationFailLow = false; - NodesSincePoll = 0; - current_search_time(get_system_time()); - Limits = limits; + Position& pos = RootPosition; + elapsed_time(true); TimeMgr.init(Limits, pos.startpos_ply_counter()); - // Set output steram in normal or chess960 mode + // Set output stream mode: normal or chess960. Castling notation is different cout << set960(pos.is_chess960()); - // Set best NodesBetweenPolls interval to avoid lagging under time pressure - if (Limits.maxNodes) - NodesBetweenPolls = Min(Limits.maxNodes, 30000); - else if (Limits.time && Limits.time < 1000) - NodesBetweenPolls = 1000; - else if (Limits.time && Limits.time < 5000) - NodesBetweenPolls = 5000; - else - NodesBetweenPolls = 30000; - - // Look for a book move if (Options["OwnBook"].value()) { if (Options["Book File"].value() != book.name()) book.open(Options["Book File"].value()); - Move bookMove = book.get_move(pos, Options["Best Book Move"].value()); + Move bookMove = book.probe(pos, Options["Best Book Move"].value()); if (bookMove != MOVE_NONE) { - if (Limits.ponder) - wait_for_stop_or_ponderhit(); + if (!Signals.stop && (Limits.ponder || Limits.infinite)) + Threads.wait_for_stop_or_ponderhit(); cout << "bestmove " << bookMove << endl; - return !QuitRequest; + return; } } - // Read UCI options - UCIMultiPV = Options["MultiPV"].value(); - SkillLevel = Options["Skill Level"].value(); - + // Read UCI options: GUI could change UCI parameters during the game read_evaluation_uci_options(pos.side_to_move()); Threads.read_uci_options(); - // Set a new TT size if changed TT.set_size(Options["Hash"].value()); - if (Options["Clear Hash"].value()) { Options["Clear Hash"].set_value("false"); TT.clear(); } + UCIMultiPV = Options["MultiPV"].value(); + SkillLevel = Options["Skill Level"].value(); + // Do we have to play with skill handicap? In this case enable MultiPV that // we will use behind the scenes to retrieve a set of possible moves. SkillLevelEnabled = (SkillLevel < 20); - MultiPV = (SkillLevelEnabled ? Max(UCIMultiPV, 4) : UCIMultiPV); + MultiPV = (SkillLevelEnabled ? std::max(UCIMultiPV, (size_t)4) : UCIMultiPV); + + if (Options["Use Search Log"].value()) + { + Log log(Options["Search Log Filename"].value()); + log << "\nSearching: " << pos.to_fen() + << "\ninfinite: " << Limits.infinite + << " ponder: " << Limits.ponder + << " time: " << Limits.time + << " increment: " << Limits.increment + << " moves to go: " << Limits.movesToGo + << endl; + } // Wake up needed threads and reset maxPly counter for (int i = 0; i < Threads.size(); i++) { - Threads[i].wake_up(); Threads[i].maxPly = 0; + Threads[i].wake_up(); } - // Write to log file and keep it open to be accessed during the search - if (Options["Use Search Log"].value()) - { - string name = Options["Search Log Filename"].value(); - LogFile.open(name.c_str(), std::ios::out | std::ios::app); - - if (LogFile.is_open()) - LogFile << "\nSearching: " << pos.to_fen() - << "\ninfinite: " << Limits.infinite - << " ponder: " << Limits.ponder - << " time: " << Limits.time - << " increment: " << Limits.increment - << " moves to go: " << Limits.movesToGo - << endl; - } + // Set best timer interval to avoid lagging under time pressure. Timer is + // used to check for remaining available thinking time. + if (TimeMgr.available_time()) + Threads.set_timer(std::min(100, std::max(TimeMgr.available_time() / 8, 20))); + else + Threads.set_timer(100); // We're ready to start thinking. Call the iterative deepening loop function Move ponderMove = MOVE_NONE; - Move bestMove = id_loop(pos, searchMoves, &ponderMove); + Move bestMove = id_loop(pos, &ponderMove); + + // Stop timer and send all the slaves to sleep, if not already sleeping + Threads.set_timer(0); + Threads.set_size(1); - // Write final search statistics and close log file - if (LogFile.is_open()) + if (Options["Use Search Log"].value()) { - int t = current_search_time(); + int e = elapsed_time(); - LogFile << "Nodes: " << pos.nodes_searched() - << "\nNodes/second: " << (t > 0 ? pos.nodes_searched() * 1000 / t : 0) - << "\nBest move: " << move_to_san(pos, bestMove); + Log log(Options["Search Log Filename"].value()); + log << "Nodes: " << pos.nodes_searched() + << "\nNodes/second: " << (e > 0 ? pos.nodes_searched() * 1000 / e : 0) + << "\nBest move: " << move_to_san(pos, bestMove); StateInfo st; pos.do_move(bestMove, st); - LogFile << "\nPonder move: " << move_to_san(pos, ponderMove) << endl; + log << "\nPonder move: " << move_to_san(pos, ponderMove) << endl; pos.undo_move(bestMove); // Return from think() with unchanged position - LogFile.close(); } - // This makes all the threads to go to sleep - Threads.set_size(1); - - // If we are pondering or in infinite search, we shouldn't print the - // best move before we are told to do so. - if (!StopRequest && (Limits.ponder || Limits.infinite)) - wait_for_stop_or_ponderhit(); + // When we reach max depth we arrive here even without a StopRequest, but if + // we are pondering or in infinite search, we shouldn't print the best move + // before we are told to do so. + if (!Signals.stop && (Limits.ponder || Limits.infinite)) + Threads.wait_for_stop_or_ponderhit(); // Could be MOVE_NONE when searching on a stalemate position cout << "bestmove " << bestMove; @@ -483,8 +411,6 @@ bool think(Position& pos, const SearchLimits& limits, Move searchMoves[]) { cout << " ponder " << ponderMove; cout << endl; - - return !QuitRequest; } @@ -494,62 +420,56 @@ namespace { // with increasing depth until the allocated thinking time has been consumed, // user stops the search, or the maximum search depth is reached. - Move id_loop(Position& pos, Move searchMoves[], Move* ponderMove) { + Move id_loop(Position& pos, Move* ponderMove) { - SearchStack ss[PLY_MAX_PLUS_2]; - Value bestValues[PLY_MAX_PLUS_2]; + Stack ss[PLY_MAX_PLUS_2]; int bestMoveChanges[PLY_MAX_PLUS_2]; - int depth, aspirationDelta; - Value value, alpha, beta; - Move bestMove, easyMove, skillBest, skillPonder; + int depth; + Value bestValue, alpha, beta, delta; + Move bestMove, skillBest, skillPonder; + bool bestMoveNeverChanged = true; - // Initialize stuff before a new search - memset(ss, 0, 4 * sizeof(SearchStack)); + memset(ss, 0, 4 * sizeof(Stack)); TT.new_search(); H.clear(); - *ponderMove = bestMove = easyMove = skillBest = skillPonder = MOVE_NONE; - depth = aspirationDelta = 0; - value = alpha = -VALUE_INFINITE, beta = VALUE_INFINITE; - ss->currentMove = MOVE_NULL; // Hack to skip update_gains() + RootMoves.clear(); + *ponderMove = bestMove = skillBest = skillPonder = MOVE_NONE; + depth = 0; + bestValue = alpha = -VALUE_INFINITE, beta = delta = VALUE_INFINITE; + ss->currentMove = MOVE_NULL; // Hack to skip update gains - // Moves to search are verified and copied - Rml.init(pos, searchMoves); + for (MoveList ml(pos); !ml.end(); ++ml) + if ( SearchMoves.empty() + || std::count(SearchMoves.begin(), SearchMoves.end(), ml.move())) + RootMoves.push_back(RootMove(ml.move())); // Handle special case of searching on a mate/stalemate position - if (!Rml.size()) + if (RootMoves.empty()) { - cout << "info" << depth_to_uci(DEPTH_ZERO) + cout << "info depth 0" << score_to_uci(pos.in_check() ? -VALUE_MATE : VALUE_DRAW, alpha, beta) << endl; return MOVE_NONE; } // Iterative deepening loop until requested to stop or target depth reached - while (!StopRequest && ++depth <= PLY_MAX && (!Limits.maxDepth || depth <= Limits.maxDepth)) + while (!Signals.stop && ++depth <= PLY_MAX && (!Limits.maxDepth || depth <= Limits.maxDepth)) { - // Save last iteration's scores, this needs to be done now, because in - // the following MultiPV loop Rml moves could be reordered. - for (size_t i = 0; i < Rml.size(); i++) - Rml[i].prevScore = Rml[i].score; + // Save now last iteration's scores, before Rml moves are reordered + for (size_t i = 0; i < RootMoves.size(); i++) + RootMoves[i].prevScore = RootMoves[i].score; - Rml.bestMoveChanges = 0; + BestMoveChanges = 0; - // MultiPV iteration loop. At depth 1 perform at least 2 iterations to - // get a score of the second best move for easy move detection. - int e = Min(Max(MultiPV, 2 * int(depth == 1)), (int)Rml.size()); - for (MultiPVIteration = 0; MultiPVIteration < e; MultiPVIteration++) + // MultiPV loop. We perform a full root search for each PV line + for (MultiPVIdx = 0; MultiPVIdx < std::min(MultiPV, RootMoves.size()); MultiPVIdx++) { - // Calculate dynamic aspiration window based on previous iterations - if (depth >= 5 && abs(Rml[MultiPVIteration].prevScore) < VALUE_KNOWN_WIN) + // Aspiration window + if (depth >= 5 && abs(RootMoves[MultiPVIdx].prevScore) < VALUE_KNOWN_WIN) { - int prevDelta1 = bestValues[depth - 1] - bestValues[depth - 2]; - int prevDelta2 = bestValues[depth - 2] - bestValues[depth - 3]; - - aspirationDelta = Min(Max(abs(prevDelta1) + abs(prevDelta2) / 2, 16), 24); - aspirationDelta = (aspirationDelta + 7) / 8 * 8; // Round to match grainSize - - alpha = Max(Rml[MultiPVIteration].prevScore - aspirationDelta, -VALUE_INFINITE); - beta = Min(Rml[MultiPVIteration].prevScore + aspirationDelta, VALUE_INFINITE); + delta = Value(16); + alpha = RootMoves[MultiPVIdx].prevScore - delta; + beta = RootMoves[MultiPVIdx].prevScore + delta; } else { @@ -560,97 +480,83 @@ namespace { // Start with a small aspiration window and, in case of fail high/low, // research with bigger window until not failing high/low anymore. do { - // Search starting from ss+1 to allow referencing (ss-1). This is - // needed by update_gains() and ss copy when splitting at Root. - value = search(pos, ss+1, alpha, beta, depth * ONE_PLY); - - // It is critical that sorting is done with a stable algorithm - // because all the values but the first are usually set to - // -VALUE_INFINITE and we want to keep the same order for all - // the moves but the new PV that goes to head. - sort(Rml.begin() + MultiPVIteration, Rml.end()); - - // In case we have found an exact score reorder the PV moves - // before leaving the fail high/low loop, otherwise leave the - // last PV move in its position so to be searched again. - if (value > alpha && value < beta) - sort(Rml.begin(), Rml.begin() + MultiPVIteration); + // Search starts from ss+1 to allow referencing (ss-1). This is + // needed by update gains and ss copy when splitting at Root. + bestValue = search(pos, ss+1, alpha, beta, depth * ONE_PLY); + + // Bring to front the best move. It is critical that sorting is + // done with a stable algorithm because all the values but the first + // and eventually the new best one are set to -VALUE_INFINITE and + // we want to keep the same order for all the moves but the new + // PV that goes to the front. Note that in case of MultiPV search + // the already searched PV lines are preserved. + sort(RootMoves.begin() + MultiPVIdx, RootMoves.end()); + + // In case we have found an exact score and we are going to leave + // the fail high/low loop then reorder the PV moves, otherwise + // leave the last PV move in its position so to be searched again. + // Of course this is needed only in MultiPV search. + if (MultiPVIdx && bestValue > alpha && bestValue < beta) + sort(RootMoves.begin(), RootMoves.begin() + MultiPVIdx); // Write PV back to transposition table in case the relevant entries // have been overwritten during the search. - for (int i = 0; i <= MultiPVIteration; i++) - Rml[i].insert_pv_in_tt(pos); + for (size_t i = 0; i <= MultiPVIdx; i++) + RootMoves[i].insert_pv_in_tt(pos); - // Value cannot be trusted. Break out immediately! - if (StopRequest) + // If search has been stopped exit the aspiration window loop, + // note that sorting and writing PV back to TT is safe becuase + // Rml is still valid, although refers to the previous iteration. + if (Signals.stop) break; // Send full PV info to GUI if we are going to leave the loop or // if we have a fail high/low and we are deep in the search. - if ((value > alpha && value < beta) || current_search_time() > 2000) - for (int i = 0; i < Min(UCIMultiPV, MultiPVIteration + 1); i++) - cout << "info" - << depth_to_uci(depth * ONE_PLY) - << (i == MultiPVIteration ? score_to_uci(Rml[i].score, alpha, beta) : - score_to_uci(Rml[i].score)) - << speed_to_uci(pos.nodes_searched()) - << pv_to_uci(&Rml[i].pv[0], i + 1, pos.is_chess960()) - << endl; - - // In case of failing high/low increase aspiration window and research, - // otherwise exit the fail high/low loop. - if (value >= beta) + if ((bestValue > alpha && bestValue < beta) || elapsed_time() > 2000) + pv_info_to_uci(pos, depth, alpha, beta); + + // In case of failing high/low increase aspiration window and + // research, otherwise exit the fail high/low loop. + if (bestValue >= beta) { - beta = Min(beta + aspirationDelta, VALUE_INFINITE); - aspirationDelta += aspirationDelta / 2; + beta += delta; + delta += delta / 2; } - else if (value <= alpha) + else if (bestValue <= alpha) { - AspirationFailLow = true; - StopOnPonderhit = false; + Signals.failedLowAtRoot = true; + Signals.stopOnPonderhit = false; - alpha = Max(alpha - aspirationDelta, -VALUE_INFINITE); - aspirationDelta += aspirationDelta / 2; + alpha -= delta; + delta += delta / 2; } else break; - } while (abs(value) < VALUE_KNOWN_WIN); + assert(alpha >= -VALUE_INFINITE && beta <= VALUE_INFINITE); + + } while (abs(bestValue) < VALUE_KNOWN_WIN); } - // Collect info about search result - bestMove = Rml[0].pv[0]; - *ponderMove = Rml[0].pv[1]; - bestValues[depth] = value; - bestMoveChanges[depth] = Rml.bestMoveChanges; + bestMove = RootMoves[0].pv[0]; + *ponderMove = RootMoves[0].pv[1]; + bestMoveChanges[depth] = BestMoveChanges; - // Do we need to pick now the best and the ponder moves ? + // Skills: Do we need to pick now the best and the ponder moves ? if (SkillLevelEnabled && depth == 1 + SkillLevel) do_skill_level(&skillBest, &skillPonder); - if (LogFile.is_open()) - LogFile << pretty_pv(pos, depth, value, current_search_time(), &Rml[0].pv[0]) << endl; + if (Options["Use Search Log"].value()) + pv_info_to_log(pos, depth, bestValue, elapsed_time(), &RootMoves[0].pv[0]); - // Init easyMove after first iteration or drop if differs from the best move - if (depth == 1 && (Rml.size() == 1 || Rml[0].score > Rml[1].score + EasyMoveMargin)) - easyMove = bestMove; - else if (bestMove != easyMove) - easyMove = MOVE_NONE; + // Filter out startup noise when monitoring best move stability + if (depth > 2 && bestMoveChanges[depth]) + bestMoveNeverChanged = false; - // Check for some early stop condition - if (!StopRequest && Limits.useTimeManagement()) + // Do we have time for the next iteration? Can we stop searching now? + if (!Signals.stop && !Signals.stopOnPonderhit && Limits.useTimeManagement()) { - // Stop search early if one move seems to be much better than the - // others or if there is only a single legal move. Also in the latter - // case we search up to some depth anyway to get a proper score. - if ( depth >= 7 - && easyMove == bestMove - && ( Rml.size() == 1 - ||( Rml[0].nodes > (pos.nodes_searched() * 85) / 100 - && current_search_time() > TimeMgr.available_time() / 16) - ||( Rml[0].nodes > (pos.nodes_searched() * 98) / 100 - && current_search_time() > TimeMgr.available_time() / 32))) - StopRequest = true; + bool stop = false; // Local variable instead of the volatile Signals.stop // Take in account some extra time if the best move has changed if (depth > 4 && depth < 50) @@ -658,14 +564,34 @@ namespace { // Stop search if most of available time is already consumed. We probably don't // have enough time to search the first move at the next iteration anyway. - if (current_search_time() > (TimeMgr.available_time() * 62) / 100) - StopRequest = true; + if (elapsed_time() > (TimeMgr.available_time() * 62) / 100) + stop = true; + + // Stop search early if one move seems to be much better than others + if ( depth >= 10 + && !stop + && ( bestMoveNeverChanged + || elapsed_time() > (TimeMgr.available_time() * 40) / 100)) + { + Value rBeta = bestValue - EasyMoveMargin; + (ss+1)->excludedMove = bestMove; + (ss+1)->skipNullMove = true; + Value v = search(pos, ss+1, rBeta - 1, rBeta, (depth * ONE_PLY) / 2); + (ss+1)->skipNullMove = false; + (ss+1)->excludedMove = MOVE_NONE; + + if (v < rBeta) + stop = true; + } - // If we are allowed to ponder do not stop the search now but keep pondering - if (StopRequest && Limits.ponder) + if (stop) { - StopRequest = false; - StopOnPonderhit = true; + // If we are allowed to ponder do not stop the search now but + // keep pondering until GUI sends "ponderhit" or "stop". + if (Limits.ponder) + Signals.stopOnPonderhit = true; + else + Signals.stop = true; } } } @@ -692,7 +618,7 @@ namespace { // here: This is taken care of after we return from the split point. template - Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth) { + Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) { const bool PvNode = (NT == PV || NT == Root || NT == SplitPointPV || NT == SplitPointRoot); const bool SpNode = (NT == SplitPointPV || NT == SplitPointNonPV || NT == SplitPointRoot); @@ -713,7 +639,8 @@ namespace { ValueType vt; Value bestValue, value, oldAlpha; Value refinedValue, nullValue, futilityBase, futilityValue; - bool isPvMove, inCheck, singularExtensionNode, givesCheck, captureOrPromotion, dangerous; + bool isPvMove, inCheck, singularExtensionNode, givesCheck; + bool captureOrPromotion, dangerous, doFullDepthSearch; int moveCount = 0, playedMoveCount = 0; Thread& thread = Threads[pos.thread()]; SplitPoint* sp = NULL; @@ -727,7 +654,7 @@ namespace { if (PvNode && thread.maxPly < ss->ply) thread.maxPly = ss->ply; - // Step 1. Initialize node and poll. Polling can abort search + // Step 1. Initialize node if (!SpNode) { ss->currentMove = ss->bestMove = threatMove = (ss+1)->excludedMove = MOVE_NONE; @@ -743,14 +670,8 @@ namespace { goto split_point_start; } - if (pos.thread() == 0 && ++NodesSincePoll > NodesBetweenPolls) - { - NodesSincePoll = 0; - poll(pos); - } - // Step 2. Check for aborted search and immediate draw - if (( StopRequest + if (( Signals.stop || pos.is_draw() || ss->ply > PLY_MAX) && !RootNode) return VALUE_DRAW; @@ -758,8 +679,8 @@ namespace { // Step 3. Mate distance pruning if (!RootNode) { - alpha = Max(value_mated_in(ss->ply), alpha); - beta = Min(value_mate_in(ss->ply+1), beta); + alpha = std::max(value_mated_in(ss->ply), alpha); + beta = std::min(value_mate_in(ss->ply+1), beta); if (alpha >= beta) return alpha; } @@ -770,7 +691,7 @@ namespace { excludedMove = ss->excludedMove; posKey = excludedMove ? pos.get_exclusion_key() : pos.get_key(); tte = TT.probe(posKey); - ttMove = RootNode ? Rml[MultiPVIteration].pv[0] : tte ? tte->move() : MOVE_NONE; + ttMove = RootNode ? RootMoves[MultiPVIdx].pv[0] : tte ? tte->move() : MOVE_NONE; // At PV nodes we check for exact scores, while at non-PV nodes we check for // a fail high/low. Biggest advantage at probing at PV nodes is to have a @@ -780,8 +701,18 @@ namespace { : can_return_tt(tte, depth, beta, ss->ply))) { TT.refresh(tte); - ss->bestMove = ttMove; // Can be MOVE_NONE - return value_from_tt(tte->value(), ss->ply); + ss->bestMove = move = ttMove; // Can be MOVE_NONE + value = value_from_tt(tte->value(), ss->ply); + + if ( value >= beta + && move + && !pos.is_capture_or_promotion(move) + && move != ss->killers[0]) + { + ss->killers[1] = ss->killers[0]; + ss->killers[0] = move; + } + return value; } // Step 5. Evaluate the position statically and update parent's gain statistics @@ -801,8 +732,17 @@ namespace { TT.store(posKey, VALUE_NONE, VALUE_TYPE_NONE, DEPTH_NONE, MOVE_NONE, ss->eval, ss->evalMargin); } - // Save gain for the parent non-capture move - update_gains(pos, (ss-1)->currentMove, (ss-1)->eval, ss->eval); + // Update gain for the parent non-capture move given the static position + // evaluation before and after the move. + if ( (move = (ss-1)->currentMove) != MOVE_NULL + && (ss-1)->eval != VALUE_NONE + && ss->eval != VALUE_NONE + && pos.captured_piece_type() == PIECE_TYPE_NONE + && !is_special(move)) + { + Square to = move_to(move); + H.update_gain(pos.piece_on(to), to, -(ss-1)->eval - ss->eval); + } // Step 6. Razoring (is omitted in PV nodes) if ( !PvNode @@ -851,12 +791,12 @@ namespace { if (refinedValue - PawnValueMidgame > beta) R++; - pos.do_null_move(st); + pos.do_null_move(st); (ss+1)->skipNullMove = true; nullValue = depth-R*ONE_PLY < ONE_PLY ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) : - search(pos, ss+1, -beta, -alpha, depth-R*ONE_PLY); (ss+1)->skipNullMove = false; - pos.undo_null_move(); + pos.do_null_move(st); if (nullValue >= beta) { @@ -940,7 +880,6 @@ namespace { split_point_start: // At split points actual search starts from here - // Initialize a MovePicker object for the current position MovePickerExt mp(pos, ttMove, depth, H, ss, PvNode ? -VALUE_INFINITE : beta); CheckInfo ci(pos); ss->bestMove = MOVE_NONE; @@ -949,13 +888,16 @@ split_point_start: // At split points actual search starts from here && !SpNode && depth >= SingularExtensionDepth[PvNode] && ttMove != MOVE_NONE - && !excludedMove // Do not allow recursive singular extension search + && !excludedMove // Recursive singular search is not allowed && (tte->type() & VALUE_TYPE_LOWER) && tte->depth() >= depth - 3 * ONE_PLY; if (SpNode) { lock_grab(&(sp->lock)); bestValue = sp->bestValue; + moveCount = sp->moveCount; + + assert(bestValue > -VALUE_INFINITE && moveCount > 0); } // Step 11. Loop through moves @@ -964,15 +906,15 @@ split_point_start: // At split points actual search starts from here && (move = mp.get_next_move()) != MOVE_NONE && !thread.cutoff_occurred()) { - assert(move_is_ok(move)); + assert(is_ok(move)); if (move == excludedMove) continue; - // At root obey the "searchmoves" option and skip moves not listed in Root Move List. - // Also in MultiPV mode we skip moves which already have got an exact score - // in previous MultiPV Iteration. Finally any illegal move is skipped here. - if (RootNode && !Rml.find(move, MultiPVIteration)) + // At root obey the "searchmoves" option and skip moves not listed in Root + // Move List, as a consequence any illegal move is also skipped. In MultiPV + // mode we also skip PV moves which have been already searched. + if (RootNode && !std::count(RootMoves.begin() + MultiPVIdx, RootMoves.end(), move)) continue; // At PV and SpNode nodes we want all moves to be legal since the beginning @@ -990,24 +932,28 @@ split_point_start: // At split points actual search starts from here if (RootNode) { // This is used by time management - FirstRootMove = (moveCount == 1); + Signals.firstRootMove = (moveCount == 1); - // Save the current node count before the move is searched nodes = pos.nodes_searched(); - // For long searches send current move info to GUI - if (pos.thread() == 0 && current_search_time() > 2000) - cout << "info" << depth_to_uci(depth) + if (pos.thread() == 0 && elapsed_time() > 2000) + cout << "info depth " << depth / ONE_PLY << " currmove " << move - << " currmovenumber " << moveCount + MultiPVIteration << endl; + << " currmovenumber " << moveCount + MultiPVIdx << endl; } - isPvMove = (PvNode && moveCount == 1); + isPvMove = (PvNode && moveCount <= 1); + captureOrPromotion = pos.is_capture_or_promotion(move); givesCheck = pos.move_gives_check(move, ci); - captureOrPromotion = pos.move_is_capture_or_promotion(move); + dangerous = givesCheck || is_dangerous(pos, move, captureOrPromotion); + ext = DEPTH_ZERO; - // Step 12. Decide the new search depth - ext = extension(pos, move, captureOrPromotion, givesCheck, &dangerous); + // Step 12. Extend checks and, in PV nodes, also dangerous moves + if (PvNode && dangerous) + ext = ONE_PLY; + + else if (givesCheck && pos.see_sign(move) >= 0) + ext = PvNode ? ONE_PLY : ONE_PLY / 2; // 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 @@ -1015,9 +961,9 @@ split_point_start: // At split points actual search starts from here // on all the other moves but the ttMove, if result is lower than ttValue minus // a margin then we extend ttMove. if ( singularExtensionNode + && !ext && move == ttMove - && pos.pl_move_is_legal(move, ci.pinned) - && ext < ONE_PLY) + && pos.pl_move_is_legal(move, ci.pinned)) { Value ttValue = value_from_tt(tte->value(), ss->ply); @@ -1026,11 +972,11 @@ split_point_start: // At split points actual search starts from here Value rBeta = ttValue - int(depth); ss->excludedMove = move; ss->skipNullMove = true; - Value v = search(pos, ss, rBeta - 1, rBeta, depth / 2); + value = search(pos, ss, rBeta - 1, rBeta, depth / 2); ss->skipNullMove = false; ss->excludedMove = MOVE_NONE; ss->bestMove = MOVE_NONE; - if (v < rBeta) + if (value < rBeta) ext = ONE_PLY; } } @@ -1044,12 +990,12 @@ split_point_start: // At split points actual search starts from here && !inCheck && !dangerous && move != ttMove - && !move_is_castle(move)) + && !is_castle(move) + && (bestValue > VALUE_MATED_IN_PLY_MAX || bestValue == -VALUE_INFINITE)) { // Move count based pruning if ( moveCount >= futility_move_count(depth) - && (!threatMove || !connected_threat(pos, move, threatMove)) - && bestValue > VALUE_MATED_IN_PLY_MAX) // FIXME bestValue is racy + && (!threatMove || !connected_threat(pos, move, threatMove))) { if (SpNode) lock_grab(&(sp->lock)); @@ -1067,20 +1013,13 @@ split_point_start: // At split points actual search starts from here if (futilityValue < beta) { if (SpNode) - { lock_grab(&(sp->lock)); - if (futilityValue > sp->bestValue) - sp->bestValue = bestValue = futilityValue; - } - else if (futilityValue > bestValue) - bestValue = futilityValue; continue; } // Prune moves with negative SEE at low depths if ( predictedDepth < 2 * ONE_PLY - && bestValue > VALUE_MATED_IN_PLY_MAX && pos.see_sign(move) < 0) { if (SpNode) @@ -1104,51 +1043,44 @@ split_point_start: // At split points actual search starts from here // Step 14. Make the move pos.do_move(move, st, ci, givesCheck); - // Step extra. pv search (only in PV nodes) - // The first move in list is the expected PV - if (isPvMove) - value = newDepth < ONE_PLY ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) - : - search(pos, ss+1, -beta, -alpha, newDepth); - else + // Step 15. Reduced depth search (LMR). If the move fails high will be + // re-searched at full depth. + if ( depth > 3 * ONE_PLY + && !isPvMove + && !captureOrPromotion + && !dangerous + && !is_castle(move) + && ss->killers[0] != move + && ss->killers[1] != move) { - // Step 15. 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) - && ss->killers[0] != move - && ss->killers[1] != move - && (ss->reduction = reduction(depth, moveCount)) != DEPTH_ZERO) - { - Depth d = newDepth - ss->reduction; - alpha = SpNode ? sp->alpha : alpha; + ss->reduction = reduction(depth, moveCount); + Depth d = newDepth - ss->reduction; + alpha = SpNode ? sp->alpha : alpha; - value = d < ONE_PLY ? -qsearch(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO) - : - search(pos, ss+1, -(alpha+1), -alpha, d); + value = d < ONE_PLY ? -qsearch(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO) + : - search(pos, ss+1, -(alpha+1), -alpha, d); - ss->reduction = DEPTH_ZERO; - doFullDepthSearch = (value > alpha); - } + doFullDepthSearch = (value > alpha && ss->reduction != DEPTH_ZERO); + ss->reduction = DEPTH_ZERO; + } + else + doFullDepthSearch = !isPvMove; - // Step 16. Full depth search - if (doFullDepthSearch) - { - alpha = SpNode ? sp->alpha : alpha; - value = newDepth < ONE_PLY ? -qsearch(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO) - : - search(pos, ss+1, -(alpha+1), -alpha, newDepth); - - // Step extra. pv search (only in PV nodes) - // Search only for possible new PV nodes, if instead value >= beta then - // parent node fails low with value <= alpha and tries another move. - if (PvNode && value > alpha && (RootNode || value < beta)) - value = newDepth < ONE_PLY ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) - : - search(pos, ss+1, -beta, -alpha, newDepth); - } + // Step 16. Full depth search, when LMR is skipped or fails high + if (doFullDepthSearch) + { + alpha = SpNode ? sp->alpha : alpha; + value = newDepth < ONE_PLY ? -qsearch(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO) + : - search(pos, ss+1, -(alpha+1), -alpha, newDepth); } + // Only for PV nodes do a full PV search on the first move or after a fail + // high, in the latter case search only if value < beta, otherwise let the + // parent node to fail low with value <= alpha and to try another move. + if (PvNode && (isPvMove || (value > alpha && (RootNode || value < beta)))) + value = newDepth < ONE_PLY ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) + : - search(pos, ss+1, -beta, -alpha, newDepth); + // Step 17. Undo move pos.undo_move(move); @@ -1166,32 +1098,30 @@ split_point_start: // At split points actual search starts from here // was aborted because the user interrupted the search or because we // ran out of time. In this case, the return value of the search cannot // be trusted, and we don't update the best move and/or PV. - if (RootNode && !StopRequest) + if (RootNode && !Signals.stop) { - // Remember searched nodes counts for this move - RootMove* rm = Rml.find(move); - rm->nodes += pos.nodes_searched() - nodes; + RootMove& rm = *std::find(RootMoves.begin(), RootMoves.end(), move); + rm.nodes += pos.nodes_searched() - nodes; // PV move or new best move ? if (isPvMove || value > alpha) { - // Update PV - rm->score = value; - rm->extract_pv_from_tt(pos); + rm.score = value; + rm.extract_pv_from_tt(pos); // We record how often the best move has been changed in each // iteration. This information is used for time management: When // the best move changes frequently, we allocate some more time. if (!isPvMove && MultiPV == 1) - Rml.bestMoveChanges++; + BestMoveChanges++; } else // All other moves but the PV are set to the lowest value, this // is not a problem when sorting becuase sort is stable and move // position in the list is preserved, just the PV is pushed up. - rm->score = -VALUE_INFINITE; + rm.score = -VALUE_INFINITE; - } // RootNode + } if (value > bestValue) { @@ -1217,23 +1147,32 @@ split_point_start: // At split points actual search starts from here && depth >= Threads.min_split_depth() && bestValue < beta && Threads.available_slave_exists(pos.thread()) - && !StopRequest + && !Signals.stop && !thread.cutoff_occurred()) bestValue = Threads.split(pos, ss, alpha, beta, bestValue, depth, threatMove, moveCount, &mp, NT); } // Step 20. Check for mate and stalemate - // All legal moves have been searched and if there are - // no legal moves, it must be mate or stalemate. - // If one move was excluded return fail low score. - if (!SpNode && !moveCount) + // All legal moves have been searched and if there are no legal moves, it + // must be mate or stalemate. Note that we can have a false positive in + // case of StopRequest or thread.cutoff_occurred() are set, but this is + // harmless because return value is discarded anyhow in the parent nodes. + // If we are in a singular extension search then return a fail low score. + if (!moveCount) return excludedMove ? oldAlpha : inCheck ? value_mated_in(ss->ply) : VALUE_DRAW; + // If we have pruned all the moves without searching return a fail-low score + if (bestValue == -VALUE_INFINITE) + { + assert(!playedMoveCount); + + bestValue = alpha; + } + // Step 21. Update tables - // If the search is not aborted, update the transposition table, - // history counters, and killer moves. - if (!SpNode && !StopRequest && !thread.cutoff_occurred()) + // Update transposition table entry, history and killers + if (!SpNode && !Signals.stop && !thread.cutoff_occurred()) { move = bestValue <= oldAlpha ? MOVE_NONE : ss->bestMove; vt = bestValue <= oldAlpha ? VALUE_TYPE_UPPER @@ -1243,7 +1182,7 @@ split_point_start: // At split points actual search starts from here // Update killers and history only for non capture moves that fails high if ( bestValue >= beta - && !pos.move_is_capture_or_promotion(move)) + && !pos.is_capture_or_promotion(move)) { if (move != ss->killers[0]) { @@ -1267,12 +1206,13 @@ split_point_start: // At split points actual search starts from here return bestValue; } + // qsearch() is the quiescence search function, which is called by the main // search function when the remaining depth is zero (or, to be more precise, // less than ONE_PLY). template - Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth) { + Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) { const bool PvNode = (NT == PV); @@ -1347,7 +1287,6 @@ split_point_start: // At split points actual search starts from here if (PvNode && bestValue > alpha) alpha = bestValue; - // Futility pruning parameters, not needed when in check futilityBase = ss->eval + evalMargin + FutilityMarginQS; enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame; } @@ -1363,7 +1302,7 @@ split_point_start: // At split points actual search starts from here while ( bestValue < beta && (move = mp.get_next_move()) != MOVE_NONE) { - assert(move_is_ok(move)); + assert(is_ok(move)); givesCheck = pos.move_gives_check(move, ci); @@ -1373,12 +1312,12 @@ split_point_start: // At split points actual search starts from here && !givesCheck && move != ttMove && enoughMaterial - && !move_is_promotion(move) - && !pos.move_is_passed_pawn_push(move)) + && !is_promotion(move) + && !pos.is_passed_pawn_push(move)) { futilityValue = futilityBase - + piece_value_endgame(pos.piece_on(move_to(move))) - + (move_is_ep(move) ? PawnValueEndgame : VALUE_ZERO); + + PieceValueEndgame[pos.piece_on(move_to(move))] + + (is_enpassant(move) ? PawnValueEndgame : VALUE_ZERO); if (futilityValue < beta) { @@ -1399,14 +1338,14 @@ split_point_start: // At split points actual search starts from here evasionPrunable = !PvNode && inCheck && bestValue > VALUE_MATED_IN_PLY_MAX - && !pos.move_is_capture(move) + && !pos.is_capture(move) && !pos.can_castle(pos.side_to_move()); // Don't search moves with negative SEE values if ( !PvNode && (!inCheck || evasionPrunable) && move != ttMove - && !move_is_promotion(move) + && !is_promotion(move) && pos.see_sign(move) < 0) continue; @@ -1415,7 +1354,7 @@ split_point_start: // At split points actual search starts from here && !inCheck && givesCheck && move != ttMove - && !pos.move_is_capture_or_promotion(move) + && !pos.is_capture_or_promotion(move) && ss->eval + PawnValueMidgame / 4 < beta && !check_is_dangerous(pos, move, futilityBase, beta, &bestValue)) { @@ -1429,7 +1368,6 @@ split_point_start: // At split points actual search starts from here if (!pos.pl_move_is_legal(move, ci.pinned)) continue; - // Update current move ss->currentMove = move; // Make and search the move @@ -1484,7 +1422,7 @@ split_point_start: // At split points actual search starts from here from = move_from(move); to = move_to(move); - them = opposite_color(pos.side_to_move()); + them = flip(pos.side_to_move()); ksq = pos.king_square(them); kingAtt = pos.attacks_from(ksq); pc = pos.piece_on(from); @@ -1500,7 +1438,7 @@ split_point_start: // At split points actual search starts from here return true; // Rule 2. Queen contact check is very dangerous - if ( piece_type(pc) == QUEEN + if ( type_of(pc) == QUEEN && bit_is_set(kingAtt, to)) return true; @@ -1510,7 +1448,7 @@ split_point_start: // At split points actual search starts from here while (b) { victimSq = pop_1st_bit(&b); - futilityValue = futilityBase + piece_value_endgame(pos.piece_on(victimSq)); + futilityValue = futilityBase + PieceValueEndgame[pos.piece_on(victimSq)]; // Note that here we generate illegal "double move"! if ( futilityValue >= beta @@ -1539,8 +1477,8 @@ split_point_start: // At split points actual search starts from here Piece p1, p2; Square ksq; - assert(m1 && move_is_ok(m1)); - assert(m2 && move_is_ok(m2)); + assert(is_ok(m1)); + assert(is_ok(m2)); // Case 1: The moving piece is the same in both moves f2 = move_from(m2); @@ -1615,10 +1553,10 @@ split_point_start: // At split points actual search starts from here bool connected_threat(const Position& pos, Move m, Move threat) { - assert(move_is_ok(m)); - assert(threat && move_is_ok(threat)); - assert(!pos.move_is_capture_or_promotion(m)); - assert(!pos.move_is_passed_pawn_push(m)); + assert(is_ok(m)); + assert(is_ok(threat)); + assert(!pos.is_capture_or_promotion(m)); + assert(!pos.is_passed_pawn_push(m)); Square mfrom, mto, tfrom, tto; @@ -1633,9 +1571,9 @@ split_point_start: // At split points actual search starts from here // Case 2: If the threatened piece has value less than or equal to the // value of the threatening piece, don't prune moves which defend it. - if ( pos.move_is_capture(threat) - && ( piece_value_midgame(pos.piece_on(tfrom)) >= piece_value_midgame(pos.piece_on(tto)) - || piece_type(pos.piece_on(tfrom)) == KING) + if ( pos.is_capture(threat) + && ( PieceValueMidgame[pos.piece_on(tfrom)] >= PieceValueMidgame[pos.piece_on(tto)] + || type_of(pos.piece_on(tfrom)) == KING) && pos.move_attacks_square(m, tto)) return true; @@ -1650,24 +1588,24 @@ split_point_start: // At split points actual search starts from here } - // can_return_tt() returns true if a transposition table score - // can be used to cut-off at a given point in search. + // can_return_tt() returns true if a transposition table score can be used to + // cut-off at a given point in search. bool can_return_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_PLY_MAX, beta) - || v < Min(VALUE_MATED_IN_PLY_MAX, beta)) + || v >= std::max(VALUE_MATE_IN_PLY_MAX, beta) + || v < std::min(VALUE_MATED_IN_PLY_MAX, beta)) && ( ((tte->type() & VALUE_TYPE_LOWER) && v >= beta) || ((tte->type() & VALUE_TYPE_UPPER) && v < beta)); } - // refine_eval() returns the transposition table score if - // possible otherwise falls back on static position evaluation. + // refine_eval() returns the transposition table score if possible, otherwise + // falls back on static position evaluation. Value refine_eval(const TTEntry* tte, Value defaultEval, int ply) { @@ -1683,8 +1621,8 @@ split_point_start: // At split points actual search starts from here } - // update_history() registers a good move that produced a beta-cutoff - // in history and marks as failures all the other moves of that ply. + // 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 move, Depth depth, Move movesSearched[], int moveCount) { @@ -1704,29 +1642,15 @@ split_point_start: // At split points actual search starts from here } - // update_gains() updates the gains table of a non-capture move given - // the static position evaluation before and after the move. - - void update_gains(const Position& pos, Move m, Value before, Value after) { - - if ( m != MOVE_NULL - && before != VALUE_NONE - && after != VALUE_NONE - && pos.captured_piece_type() == PIECE_TYPE_NONE - && !move_is_special(m)) - H.update_gain(pos.piece_on(move_to(m)), move_to(m), -(before + after)); - } - - // current_search_time() returns the number of milliseconds which have passed // since the beginning of the current search. - int current_search_time(int set) { + int elapsed_time(bool reset) { static int searchStartTime; - if (set) - searchStartTime = set; + if (reset) + searchStartTime = get_system_time(); return get_system_time() - searchStartTime; } @@ -1754,53 +1678,49 @@ split_point_start: // At split points actual search starts from here } - // speed_to_uci() returns a string with time stats of current search suitable - // to be sent to UCI gui. + // pv_info_to_uci() sends search info to GUI. UCI protocol requires to send all + // the PV lines also if are still to be searched and so refer to the previous + // search score. - string speed_to_uci(int64_t nodes) { + void pv_info_to_uci(const Position& pos, int depth, Value alpha, Value beta) { - std::stringstream s; - int t = current_search_time(); - - s << " nodes " << nodes - << " nps " << (t > 0 ? int(nodes * 1000 / t) : 0) - << " time " << t; + int t = elapsed_time(); + int selDepth = 0; - return s.str(); - } + for (int i = 0; i < Threads.size(); i++) + if (Threads[i].maxPly > selDepth) + selDepth = Threads[i].maxPly; - // pv_to_uci() returns a string with information on the current PV line - // formatted according to UCI specification. + for (size_t i = 0; i < std::min(UCIMultiPV, RootMoves.size()); i++) + { + bool updated = (i <= MultiPVIdx); - string pv_to_uci(const Move pv[], int pvNum, bool chess960) { + if (depth == 1 && !updated) + continue; - std::stringstream s; + int d = (updated ? depth : depth - 1); + Value s = (updated ? RootMoves[i].score : RootMoves[i].prevScore); - s << " multipv " << pvNum << " pv " << set960(chess960); + cout << "info" + << " depth " << d + << " seldepth " << selDepth + << (i == MultiPVIdx ? score_to_uci(s, alpha, beta) : score_to_uci(s)) + << " nodes " << pos.nodes_searched() + << " nps " << (t > 0 ? pos.nodes_searched() * 1000 / t : 0) + << " time " << t + << " multipv " << i + 1 << " pv"; - for ( ; *pv != MOVE_NONE; pv++) - s << *pv << " "; + for (int j = 0; RootMoves[i].pv[j] != MOVE_NONE; j++) + cout << " " << RootMoves[i].pv[j]; - return s.str(); + cout << endl; + } } - // depth_to_uci() returns a string with information on the current depth and - // seldepth formatted according to UCI specification. - - string depth_to_uci(Depth depth) { - std::stringstream s; - - // Retrieve max searched depth among threads - int selDepth = 0; - for (int i = 0; i < Threads.size(); i++) - if (Threads[i].maxPly > selDepth) - selDepth = Threads[i].maxPly; - - s << " depth " << depth / ONE_PLY << " seldepth " << selDepth; - - return s.str(); - } + // pv_info_to_log() writes human-readable search information to the log file + // (which is created when the UCI parameter "Use Search Log" is "true"). It + // uses the two below helpers to pretty format time and score respectively. string time_to_string(int millisecs) { @@ -1816,7 +1736,8 @@ split_point_start: // At split points actual search starts from here if (hours) s << hours << ':'; - s << std::setfill('0') << std::setw(2) << minutes << ':' << std::setw(2) << seconds; + s << std::setfill('0') << std::setw(2) << minutes << ':' + << std::setw(2) << seconds; return s.str(); } @@ -1829,29 +1750,23 @@ split_point_start: // At split points actual search starts from here else if (v <= VALUE_MATED_IN_PLY_MAX) s << "-#" << (VALUE_MATE + v) / 2; else - s << std::setprecision(2) << std::fixed << std::showpos << float(v) / PawnValueMidgame; + s << std::setprecision(2) << std::fixed << std::showpos + << float(v) / PawnValueMidgame; return s.str(); } - // pretty_pv() creates a human-readable string from a position and a PV. - // It is used to write search information to the log file (which is created - // when the UCI parameter "Use Search Log" is "true"). - - string pretty_pv(Position& pos, int depth, Value value, int time, Move pv[]) { + void pv_info_to_log(Position& pos, int depth, Value value, int time, Move pv[]) { const int64_t K = 1000; const int64_t M = 1000000; - const int startColumn = 28; - const size_t maxLength = 80 - startColumn; StateInfo state[PLY_MAX_PLUS_2], *st = state; Move* m = pv; - string san; + string san, padding; + size_t length; std::stringstream s; - size_t length = 0; - // First print depth, score, time and searched nodes... s << set960(pos.is_chess960()) << std::setw(2) << depth << std::setw(8) << score_to_string(value) @@ -1859,209 +1774,84 @@ split_point_start: // At split points actual search starts from here if (pos.nodes_searched() < M) s << std::setw(8) << pos.nodes_searched() / 1 << " "; + else if (pos.nodes_searched() < K * M) s << std::setw(7) << pos.nodes_searched() / K << "K "; + else s << std::setw(7) << pos.nodes_searched() / M << "M "; - // ...then print the full PV line in short algebraic notation + padding = string(s.str().length(), ' '); + length = padding.length(); + while (*m != MOVE_NONE) { san = move_to_san(pos, *m); - length += san.length() + 1; - if (length > maxLength) + if (length + san.length() > 80) { - length = san.length() + 1; - s << "\n" + string(startColumn, ' '); + s << "\n" + padding; + length = padding.length(); } + s << san << ' '; + length += san.length() + 1; pos.do_move(*m++, *st++); } - // Restore original position before to leave - while (m != pv) pos.undo_move(*--m); + while (m != pv) + pos.undo_move(*--m); - return s.str(); - } - - // poll() performs two different functions: It polls for user input, and it - // looks at the time consumed so far and decides if it's time to abort the - // search. - - void poll(const Position& pos) { - - static int lastInfoTime; - int t = current_search_time(); - - // Poll for input - if (input_available()) - { - // We are line oriented, don't read single chars - string command; - - if (!std::getline(std::cin, command) || command == "quit") - { - // Quit the program as soon as possible - Limits.ponder = false; - QuitRequest = StopRequest = true; - return; - } - else if (command == "stop") - { - // Stop calculating as soon as possible, but still send the "bestmove" - // and possibly the "ponder" token when finishing the search. - Limits.ponder = false; - StopRequest = true; - } - else if (command == "ponderhit") - { - // The opponent has played the expected move. GUI sends "ponderhit" if - // we were told to ponder on the same move the opponent has played. We - // should continue searching but switching from pondering to normal search. - Limits.ponder = false; - - if (StopOnPonderhit) - StopRequest = true; - } - } - - // Print search information - 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; - - dbg_print_mean(); - dbg_print_hit_rate(); - } - - // Should we stop the search? - if (Limits.ponder) - return; - - bool stillAtFirstMove = FirstRootMove - && !AspirationFailLow - && t > TimeMgr.available_time(); - - bool noMoreTime = t > TimeMgr.maximum_time() - || stillAtFirstMove; - - if ( (Limits.useTimeManagement() && noMoreTime) - || (Limits.maxTime && t >= Limits.maxTime) - || (Limits.maxNodes && pos.nodes_searched() >= Limits.maxNodes)) // FIXME - StopRequest = true; - } - - - // wait_for_stop_or_ponderhit() is called when the maximum depth is reached - // while the program is pondering. The point is to work around a wrinkle in - // the UCI protocol: When pondering, the engine is not allowed to give a - // "bestmove" before the GUI sends it a "stop" or "ponderhit" command. - // We simply wait here until one of these commands is sent, and return, - // after which the bestmove and pondermove will be printed. - - void wait_for_stop_or_ponderhit() { - - string command; - - // Wait for a command from stdin - while ( std::getline(std::cin, command) - && command != "ponderhit" && command != "stop" && command != "quit") {}; - - if (command != "ponderhit" && command != "stop") - QuitRequest = true; // Must be "quit" or getline() returned false + Log l(Options["Search Log Filename"].value()); + l << s.str() << endl; } // When playing with strength handicap choose best move among the MultiPV set // using a statistical rule dependent on SkillLevel. Idea by Heinz van Saanen. + void do_skill_level(Move* best, Move* ponder) { assert(MultiPV > 1); static RKISS rk; - // Rml list is already sorted by score in descending order - int s; - int max_s = -VALUE_INFINITE; - int size = Min(MultiPV, (int)Rml.size()); - int max = Rml[0].score; - int var = Min(max - Rml[size - 1].score, PawnValueMidgame); - int wk = 120 - 2 * SkillLevel; - - // PRNG sequence should be non deterministic + // PRNG sequence should be not deterministic for (int i = abs(get_system_time() % 50); i > 0; i--) rk.rand(); - // Choose best move. For each move's score we add two terms both dependent - // on wk, one deterministic and bigger for weaker moves, and one random, + // Rml list is already sorted by score in descending order + size_t size = std::min(MultiPV, RootMoves.size()); + int variance = std::min(RootMoves[0].score - RootMoves[size - 1].score, PawnValueMidgame); + int weakness = 120 - 2 * SkillLevel; + int max_s = -VALUE_INFINITE; + + // Choose best move. For each move score we add two terms both dependent on + // weakness, one deterministic and bigger for weaker moves, and one random, // then we choose the move with the resulting highest score. - for (int i = 0; i < size; i++) + for (size_t i = 0; i < size; i++) { - s = Rml[i].score; + int s = RootMoves[i].score; // Don't allow crazy blunders even at very low skills - if (i > 0 && Rml[i-1].score > s + EasyMoveMargin) + if (i > 0 && RootMoves[i-1].score > s + EasyMoveMargin) break; - // This is our magical formula - s += ((max - s) * wk + var * (rk.rand() % wk)) / 128; + // This is our magic formula + s += ( weakness * int(RootMoves[0].score - s) + + variance * (rk.rand() % weakness)) / 128; if (s > max_s) { max_s = s; - *best = Rml[i].pv[0]; - *ponder = Rml[i].pv[1]; + *best = RootMoves[i].pv[0]; + *ponder = RootMoves[i].pv[1]; } } } - /// RootMove and RootMoveList method's definitions - - void RootMoveList::init(Position& pos, Move searchMoves[]) { - - Move* sm; - bestMoveChanges = 0; - clear(); - - // Generate all legal moves and add them to RootMoveList - for (MoveList ml(pos); !ml.end(); ++ml) - { - // If we have a searchMoves[] list then verify the move - // is in the list before to add it. - for (sm = searchMoves; *sm && *sm != ml.move(); sm++) {} - - if (sm != searchMoves && *sm != ml.move()) - continue; - - RootMove rm; - rm.pv.push_back(ml.move()); - rm.pv.push_back(MOVE_NONE); - rm.score = rm.prevScore = -VALUE_INFINITE; - rm.nodes = 0; - push_back(rm); - } - } - - RootMove* RootMoveList::find(const Move& m, int startIndex) { - - for (size_t i = startIndex; i < size(); i++) - if ((*this)[i].pv[0] == m) - return &(*this)[i]; - - return NULL; - } - // 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 @@ -2074,7 +1864,7 @@ split_point_start: // At split points actual search starts from here int ply = 1; Move m = pv[0]; - assert(m != MOVE_NONE && pos.move_is_pl(m)); + assert(m != MOVE_NONE && pos.is_pseudo_legal(m)); pv.clear(); pv.push_back(m); @@ -2082,7 +1872,7 @@ split_point_start: // At split points actual search starts from here while ( (tte = TT.probe(pos.get_key())) != NULL && tte->move() != MOVE_NONE - && pos.move_is_pl(tte->move()) + && pos.is_pseudo_legal(tte->move()) && pos.pl_move_is_legal(tte->move(), pos.pinned_pieces()) && ply < PLY_MAX && (!pos.is_draw() || ply < 2)) @@ -2096,6 +1886,7 @@ split_point_start: // At split points actual search starts from here do pos.undo_move(pv[--ply]); while (ply); } + // insert_pv_in_tt() is called at the end of a search iteration, and inserts // the PV back into the TT. This makes sure the old PV moves are searched // first, even if the old TT entries have been overwritten. @@ -2108,7 +1899,7 @@ split_point_start: // At split points actual search starts from here Value v, m = VALUE_NONE; int ply = 0; - assert(pv[0] != MOVE_NONE && pos.move_is_pl(pv[0])); + assert(pv[ply] != MOVE_NONE && pos.is_pseudo_legal(pv[ply])); do { k = pos.get_key(); @@ -2126,25 +1917,13 @@ split_point_start: // At split points actual search starts from here do pos.undo_move(pv[--ply]); while (ply); } -} // namespace - -// Little helper used by idle_loop() to check that all the slave threads of a -// split point have finished searching. - -static bool all_slaves_finished(SplitPoint* sp) { - - for (int i = 0; i < Threads.size(); i++) - if (sp->is_slave[i]) - return false; - - return true; -} +} // namespace -// Thread::idle_loop() is where the thread is parked when it has no work to do. -// The parameter 'sp', if non-NULL, is a pointer to an active SplitPoint object -// for which the thread is the master. +/// Thread::idle_loop() is where the thread is parked when it has no work to do. +/// The parameter 'sp', if non-NULL, is a pointer to an active SplitPoint object +/// for which the thread is the master. void Thread::idle_loop(SplitPoint* sp) { @@ -2158,7 +1937,6 @@ void Thread::idle_loop(SplitPoint* sp) { { assert((!sp && threadID) || Threads.use_sleeping_threads()); - // Slave thread should exit as soon as do_terminate flag raises if (do_terminate) { assert(!sp); @@ -2169,7 +1947,7 @@ void Thread::idle_loop(SplitPoint* sp) { lock_grab(&sleepLock); // If we are master and all slaves have finished don't go to sleep - if (sp && all_slaves_finished(sp)) + if (sp && Threads.split_point_finished(sp)) { lock_release(&sleepLock); break; @@ -2191,11 +1969,11 @@ void Thread::idle_loop(SplitPoint* sp) { assert(!do_terminate); // Copy split point position and search stack and call search() - SearchStack ss[PLY_MAX_PLUS_2]; + Stack ss[PLY_MAX_PLUS_2]; SplitPoint* tsp = splitPoint; Position pos(*tsp->pos, threadID); - memcpy(ss, tsp->ss - 1, 4 * sizeof(SearchStack)); + memcpy(ss, tsp->ss - 1, 4 * sizeof(Stack)); (ss+1)->sp = tsp; if (tsp->nodeType == Root) @@ -2221,7 +1999,7 @@ void Thread::idle_loop(SplitPoint* sp) { // If this thread is the master of a split point and all slaves have // finished their work at this split point, return from the idle loop. - if (sp && all_slaves_finished(sp)) + if (sp && Threads.split_point_finished(sp)) { // Because sp->is_slave[] is reset under lock protection, // be sure sp->lock has been released before to return. @@ -2231,3 +2009,37 @@ void Thread::idle_loop(SplitPoint* sp) { } } } + + +/// do_timer_event() is called by the timer thread when the timer triggers. It +/// is used to print debug info and, more important, to detect when we are out of +/// available time and so stop the search. + +void do_timer_event() { + + static int lastInfoTime; + int e = elapsed_time(); + + if (get_system_time() - lastInfoTime >= 1000 || !lastInfoTime) + { + lastInfoTime = get_system_time(); + + dbg_print_mean(); + dbg_print_hit_rate(); + } + + if (Limits.ponder) + return; + + bool stillAtFirstMove = Signals.firstRootMove + && !Signals.failedLowAtRoot + && e > TimeMgr.available_time(); + + bool noMoreTime = e > TimeMgr.maximum_time() + || stillAtFirstMove; + + if ( (Limits.useTimeManagement() && noMoreTime) + || (Limits.maxTime && e >= Limits.maxTime) + /* missing nodes limit */ ) // FIXME + Signals.stop = true; +}