X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=f11388c595a162a1d77ddddb046d192bfd01945e;hp=1eddff5813f2d5afc45f106f53dd8c1278b4b7a2;hb=50e094ef8db36ba1c1020b12594506f62532df17;hpb=c835ee88535e138a4a5870f18a1cebab96476cf7 diff --git a/src/search.cpp b/src/search.cpp index 1eddff58..f11388c5 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -1,7 +1,7 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008-2009 Marco Costalba + Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -52,7 +52,11 @@ using std::endl; namespace { /// Types + enum NodeType { NonPV, PV }; + // Set to true to force running with one thread. + // Used for debugging SMP code. + const bool FakeSplit = false; // ThreadsManager class is used to handle all the threads related stuff in search, // init, starting, parking and, the most important, launching a slave thread at a @@ -82,12 +86,14 @@ namespace { bool thread_should_stop(int threadID) const; void wake_sleeping_threads(); void put_threads_to_sleep(); - void idle_loop(int threadID, SplitPoint* waitSp); - bool split(const Position& pos, SearchStack* ss, int ply, Value* alpha, const Value beta, Value* bestValue, - Depth depth, bool mateThreat, int* moves, MovePicker* mp, int master, bool pvNode); + void idle_loop(int threadID, SplitPoint* sp); + + template + void split(const Position& pos, SearchStack* ss, Value* alpha, const Value beta, Value* bestValue, + Depth depth, bool mateThreat, int* moveCount, MovePicker* mp, int master, bool pvNode); private: - friend void poll(SearchStack ss[], int ply); + friend void poll(); int ActiveThreads; volatile bool AllThreadsShouldExit, AllThreadsShouldSleep; @@ -116,7 +122,7 @@ namespace { // RootMove::operator<() is the comparison function used when // sorting the moves. A move m1 is considered to be better // than a move m2 if it has a higher score, or if the moves - // have equal score but m1 has the higher node count. + // have equal score but m1 has the higher beta cut-off count. bool operator<(const RootMove& m) const { return score != m.score ? score < m.score : theirBeta <= m.theirBeta; @@ -179,11 +185,10 @@ namespace { // Step 9. Internal iterative deepening // Minimum depth for use of internal iterative deepening - const Depth IIDDepthAtPVNodes = 5 * OnePly; - const Depth IIDDepthAtNonPVNodes = 8 * OnePly; + const Depth IIDDepth[2] = { 8 * OnePly /* non-PV */, 5 * OnePly /* PV */}; // At Non-PV nodes we do an internal iterative deepening search - // when the static evaluation is at most IIDMargin below beta. + // when the static evaluation is bigger then beta - IIDMargin. const Value IIDMargin = Value(0x100); // Step 11. Decide the new search depth @@ -194,8 +199,7 @@ namespace { Depth PassedPawnExtension[2], PawnEndgameExtension[2], MateThreatExtension[2]; // Minimum depth for use of singular extension - const Depth SingularExtensionDepthAtPVNodes = 6 * OnePly; - const Depth SingularExtensionDepthAtNonPVNodes = 8 * OnePly; + const Depth SingularExtensionDepth[2] = { 8 * OnePly /* non-PV */, 6 * OnePly /* PV */}; // If the TT move is at least SingularExtensionMargin better then the // remaining ones we will extend it. @@ -216,11 +220,10 @@ namespace { // Step 14. Reduced search // Reduction lookup tables (initialized at startup) and their getter functions - int8_t PVReductionMatrix[64][64]; // [depth][moveNumber] - int8_t NonPVReductionMatrix[64][64]; // [depth][moveNumber] + int8_t ReductionMatrix[2][64][64]; // [pv][depth][moveNumber] - inline Depth pv_reduction(Depth d, int mn) { return (Depth) PVReductionMatrix[Min(d / 2, 63)][Min(mn, 63)]; } - inline Depth nonpv_reduction(Depth d, int mn) { return (Depth) NonPVReductionMatrix[Min(d / 2, 63)][Min(mn, 63)]; } + template + inline Depth reduction(Depth d, int mn) { return (Depth) ReductionMatrix[PV][Min(d / 2, 63)][Min(mn, 63)]; } // Common adjustments @@ -259,9 +262,6 @@ namespace { bool UseTimeManagement, InfiniteSearch, PonderSearch, StopOnPonderhit; bool FirstRootMove, AbortSearch, Quit, AspirationFailLow; - // Show current line? - bool ShowCurrentLine; - // Log file bool UseLogFile; std::ofstream LogFile; @@ -282,34 +282,39 @@ namespace { /// Local functions Value id_loop(const Position& pos, Move searchMoves[]); - Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value* alphaPtr, Value* betaPtr); - Value search_pv(Position& pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID); - Value search(Position& pos, SearchStack ss[], Value beta, Depth depth, int ply, bool allowNullmove, int threadID, Move excludedMove = MOVE_NONE); - Value qsearch(Position& pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID); + Value root_search(Position& pos, SearchStack* ss, RootMoveList& rml, Value* alphaPtr, Value* betaPtr); + + template + Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, bool allowNullmove, int threadID, Move excludedMove = MOVE_NONE); + + template + Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int threadID); + + template void sp_search(SplitPoint* sp, int threadID); - void sp_search_pv(SplitPoint* sp, int threadID); - void init_node(SearchStack ss[], int ply, int threadID); - void update_pv(SearchStack ss[], int ply); - void sp_update_pv(SearchStack* pss, SearchStack ss[], int ply); + + template + Depth extension(const Position& pos, Move m, bool captureOrPromotion, bool moveIsCheck, bool singleEvasion, bool mateThreat, bool* dangerous); + + 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); bool value_is_mate(Value value); - bool move_is_killer(Move m, const SearchStack& ss); - Depth extension(const Position&, Move, bool, bool, bool, bool, bool, bool*); - bool ok_to_do_nullmove(const Position& pos); - bool ok_to_prune(const Position& pos, Move m, Move threat); + bool move_is_killer(Move m, SearchStack* ss); bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply); + bool connected_threat(const Position& pos, Move m, Move threat); Value refine_eval(const TTEntry* tte, Value defaultEval, int ply); void update_history(const Position& pos, Move move, Depth depth, Move movesSearched[], int moveCount); - void update_killers(Move m, SearchStack& ss); + void update_killers(Move m, SearchStack* ss); void update_gains(const Position& pos, Move move, Value before, Value after); int current_search_time(); int nps(); - void poll(SearchStack ss[], int ply); + void poll(); void ponderhit(); void wait_for_stop_or_ponderhit(); - void init_ss_array(SearchStack ss[]); - void print_pv_info(const Position& pos, SearchStack ss[], Value alpha, Value beta, Value value); + void init_ss_array(SearchStack* ss); + void print_pv_info(const Position& pos, SearchStack* ss, Value alpha, Value beta, Value value); #if !defined(_MSC_VER) void *init_thread(void *threadID); @@ -390,7 +395,7 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move, if (get_option_value_string("Book File") != OpeningBook.file_name()) OpeningBook.open(get_option_value_string("Book File")); - Move bookMove = OpeningBook.get_move(pos); + Move bookMove = OpeningBook.get_move(pos, get_option_value_bool("Best Book Move")); if (bookMove != MOVE_NONE) { if (PonderSearch) @@ -425,7 +430,6 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move, MinimumSplitDepth = get_option_value_int("Minimum Split Depth") * OnePly; MaxThreadsPerSplitPoint = get_option_value_int("Maximum Number of Threads per Split Point"); - ShowCurrentLine = get_option_value_bool("UCI_ShowCurrLine"); MultiPV = get_option_value_int("MultiPV"); Chess960 = get_option_value_bool("UCI_Chess960"); UseLogFile = get_option_value_bool("Use Search Log"); @@ -441,10 +445,6 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move, { TM.set_active_threads(newActiveThreads); init_eval(TM.active_threads()); - // HACK: init_eval() destroys the static castleRightsMask[] array in the - // Position class. The below line repairs the damage. - Position p(pos.to_fen()); - assert(pos.is_ok()); } // Wake up sleeping threads @@ -557,10 +557,10 @@ void init_search() { for (int i = 1; i < 64; i++) // i == depth (OnePly = 1) for (int j = 1; j < 64; j++) // j == moveNumber { - double pvRed = 0.5 + log(double(i)) * log(double(j)) / 6.0; - double nonPVRed = 0.5 + log(double(i)) * log(double(j)) / 3.0; - PVReductionMatrix[i][j] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(OnePly)) : 0); - NonPVReductionMatrix[i][j] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(OnePly)) : 0); + double pvRed = log(double(i)) * log(double(j)) / 3.0; + double nonPVRed = log(double(i)) * log(double(j)) / 1.5; + ReductionMatrix[PV][i][j] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(OnePly)) : 0); + ReductionMatrix[NonPV][i][j] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(OnePly)) : 0); } // Init futility margins array @@ -568,7 +568,7 @@ void init_search() { for (int j = 0; j < 64; j++) // j == moveNumber { // FIXME: test using log instead of BSR - FutilityMarginsMatrix[i][j] = (i < 2 ? 0 : 112 * bitScanReverse32(i * i / 2)) - 8 * j; + FutilityMarginsMatrix[i][j] = (i < 2 ? 0 : 112 * bitScanReverse32(i * i / 2)) - 8 * j + 45; } // Init futility move count array @@ -635,6 +635,7 @@ namespace { H.clear(); init_ss_array(ss); ValueByIteration[1] = rml.get_move_score(0); + p.reset_ply(); Iteration = 1; // Is one move significantly better than others after initial scoring ? @@ -669,7 +670,7 @@ namespace { // Write PV to transposition table, in case the relevant entries have // been overwritten during the search. - TT.insert_pv(p, ss[0].pv); + TT.insert_pv(p, ss->pv); if (AbortSearch) break; // Value cannot be trusted. Break out immediately! @@ -678,7 +679,7 @@ namespace { ValueByIteration[Iteration] = value; // Drop the easy move if differs from the new best move - if (ss[0].pv[0] != EasyMove) + if (ss->pv[0] != EasyMove) EasyMove = MOVE_NONE; if (UseTimeManagement) @@ -700,7 +701,7 @@ namespace { // Stop search early if one move seems to be much better than the others int64_t nodes = TM.nodes_searched(); if ( Iteration >= 8 - && EasyMove == ss[0].pv[0] + && EasyMove == ss->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 @@ -743,18 +744,18 @@ namespace { << " hashfull " << TT.full() << endl; // Print the best move and the ponder move to the standard output - if (ss[0].pv[0] == MOVE_NONE) + if (ss->pv[0] == MOVE_NONE) { - ss[0].pv[0] = rml.get_move(0); - ss[0].pv[1] = MOVE_NONE; + ss->pv[0] = rml.get_move(0); + ss->pv[1] = MOVE_NONE; } - assert(ss[0].pv[0] != MOVE_NONE); + assert(ss->pv[0] != MOVE_NONE); - cout << "bestmove " << ss[0].pv[0]; + cout << "bestmove " << ss->pv[0]; - if (ss[0].pv[1] != MOVE_NONE) - cout << " ponder " << ss[0].pv[1]; + if (ss->pv[1] != MOVE_NONE) + cout << " ponder " << ss->pv[1]; cout << endl; @@ -768,12 +769,12 @@ namespace { LogFile << "\nNodes: " << TM.nodes_searched() << "\nNodes/second: " << nps() - << "\nBest move: " << move_to_san(p, ss[0].pv[0]); + << "\nBest move: " << move_to_san(p, ss->pv[0]); StateInfo st; - p.do_move(ss[0].pv[0], st); + p.do_move(ss->pv[0], st); LogFile << "\nPonder move: " - << move_to_san(p, ss[0].pv[1]) // Works also with MOVE_NONE + << move_to_san(p, ss->pv[1]) // Works also with MOVE_NONE << endl; } return rml.get_move_score(0); @@ -785,7 +786,7 @@ namespace { // scheme, prints some information to the standard output and handles // the fail low/high loops. - Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value* alphaPtr, Value* betaPtr) { + Value root_search(Position& pos, SearchStack* ss, RootMoveList& rml, Value* alphaPtr, Value* betaPtr) { EvalInfo ei; StateInfo st; @@ -802,17 +803,15 @@ namespace { beta = *betaPtr; isCheck = pos.is_check(); - // Step 1. Initialize node and poll (omitted at root, but I can see no good reason for this, FIXME) - // Step 2. Check for aborted search (omitted at root, because we do not initialize root node) + // Step 1. Initialize node and poll (omitted at root, init_ss_array() has already initialized root node) + // Step 2. Check for aborted search (omitted at root) // Step 3. Mate distance pruning (omitted at root) // Step 4. Transposition table lookup (omitted at root) // Step 5. Evaluate the position statically // At root we do this only to get reference value for child nodes if (!isCheck) - ss[0].eval = evaluate(pos, ei, 0); - else - ss[0].eval = VALUE_NONE; // HACK because we do not initialize root node + ss->eval = evaluate(pos, ei, 0); // Step 6. Razoring (omitted at root) // Step 7. Static null move pruning (omitted at root) @@ -841,7 +840,7 @@ namespace { // Pick the next root move, and print the move and the move number to // the standard output. - move = ss[0].currentMove = rml.get_move(i); + move = ss->currentMove = rml.get_move(i); if (current_search_time() >= 1000) cout << "info currmove " << move @@ -852,7 +851,7 @@ namespace { // Step 11. Decide the new search depth depth = (Iteration - 2) * OnePly + InitialDepth; - ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, false, false, &dangerous); + ext = extension(pos, move, captureOrPromotion, moveIsCheck, false, false, &dangerous); newDepth = depth + ext; // Step 12. Futility pruning (omitted at root) @@ -877,7 +876,7 @@ namespace { alpha = -VALUE_INFINITE; // Full depth PV search, done on first move or after a fail high - value = -search_pv(pos, ss, -beta, -alpha, newDepth, 1, 0); + value = -search(pos, ss+1, -beta, -alpha, newDepth, false, 0); } else { @@ -890,11 +889,11 @@ namespace { && !captureOrPromotion && !move_is_castle(move)) { - ss[0].reduction = pv_reduction(depth, i - MultiPV + 2); - if (ss[0].reduction) + ss->reduction = reduction(depth, i - MultiPV + 2); + if (ss->reduction) { // Reduced depth non-pv search using alpha as upperbound - value = -search(pos, ss, -alpha, newDepth-ss[0].reduction, 1, true, 0); + value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, true, 0); doFullDepthSearch = (value > alpha); } } @@ -903,13 +902,13 @@ namespace { if (doFullDepthSearch) { // Full depth non-pv search using alpha as upperbound - ss[0].reduction = Depth(0); - value = -search(pos, ss, -alpha, newDepth, 1, true, 0); + ss->reduction = Depth(0); + value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth, true, 0); // If we are above alpha then research at same depth but as PV // to get a correct score or eventually a fail high above beta. if (value > alpha) - value = -search_pv(pos, ss, -beta, -alpha, newDepth, 1, 0); + value = -search(pos, ss+1, -beta, -alpha, newDepth, false, 0); } } @@ -924,15 +923,15 @@ namespace { // the score before research in case we run out of time while researching. rml.set_move_score(i, value); update_pv(ss, 0); - TT.extract_pv(pos, ss[0].pv, PLY_MAX); - rml.set_move_pv(i, ss[0].pv); + TT.extract_pv(pos, ss->pv, PLY_MAX); + rml.set_move_pv(i, ss->pv); // Print information to the standard output print_pv_info(pos, ss, alpha, beta, value); // Prepare for a research after a fail high, each time with a wider window - researchCountFH++; *betaPtr = beta = Min(beta + AspirationDelta * (1 << researchCountFH), VALUE_INFINITE); + researchCountFH++; } // End of fail high loop @@ -964,8 +963,8 @@ namespace { // Update PV rml.set_move_score(i, value); update_pv(ss, 0); - TT.extract_pv(pos, ss[0].pv, PLY_MAX); - rml.set_move_pv(i, ss[0].pv); + TT.extract_pv(pos, ss->pv, PLY_MAX); + rml.set_move_pv(i, ss->pv); if (MultiPV == 1) { @@ -1017,8 +1016,8 @@ namespace { break; // Prepare for a research after a fail low, each time with a wider window - researchCountFL++; *alphaPtr = alpha = Max(alpha - AspirationDelta * (1 << researchCountFL), -VALUE_INFINITE); + researchCountFL++; } // Fail low loop @@ -1029,14 +1028,16 @@ namespace { } - // search_pv() is the main search function for PV nodes. + // search<>() is the main search function for both PV and non-PV nodes - Value search_pv(Position& pos, SearchStack ss[], Value alpha, Value beta, - Depth depth, int ply, int threadID) { + template + Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, + bool allowNullmove, int threadID, Move excludedMove) { assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE); assert(beta > alpha && beta <= VALUE_INFINITE); - assert(ply >= 0 && ply < PLY_MAX); + assert(PvNode || alpha == beta - 1); + assert(pos.ply() > 0 && pos.ply() < PLY_MAX); assert(threadID >= 0 && threadID < TM.active_threads()); Move movesSearched[256]; @@ -1046,17 +1047,24 @@ namespace { Move ttMove, move; Depth ext, newDepth; Value bestValue, value, oldAlpha; + Value refinedValue, nullValue, futilityValueScaled; // Non-PV specific bool isCheck, singleEvasion, moveIsCheck, captureOrPromotion, dangerous; bool mateThreat = false; int moveCount = 0; - bestValue = value = -VALUE_INFINITE; + int ply = pos.ply(); + refinedValue = bestValue = value = -VALUE_INFINITE; + oldAlpha = alpha; - if (depth < OnePly) - return qsearch(pos, ss, alpha, beta, Depth(0), ply, threadID); + // Step 1. Initialize node and poll. Polling can abort search + TM.incrementNodeCounter(threadID); + ss->init(ply); + (ss + 2)->initKillers(); - // Step 1. Initialize node and poll - // Polling can abort search. - init_node(ss, ply, threadID); + if (threadID == 0 && ++NodesSincePoll > NodesBetweenPolls) + { + NodesSincePoll = 0; + poll(); + } // Step 2. Check for aborted search and immediate draw if (AbortSearch || TM.thread_should_stop(threadID)) @@ -1066,13 +1074,20 @@ namespace { return VALUE_DRAW; // Step 3. Mate distance pruning - oldAlpha = alpha; alpha = Max(value_mated_in(ply), alpha); beta = Min(value_mate_in(ply+1), beta); if (alpha >= beta) return alpha; // Step 4. Transposition table lookup + + // We don't want the score of a partial search to overwrite a previous full search + // TT value, so we use a different position key in case of an excluded move exists. + Key posKey = excludedMove ? pos.get_exclusion_key() : pos.get_key(); + + tte = TT.retrieve(posKey); + ttMove = (tte ? tte->move() : MOVE_NONE); + // At PV nodes, we don't use the TT for pruning, but only for move ordering. // This is to avoid problems in the following areas: // @@ -1080,294 +1095,76 @@ namespace { // * Fifty move rule detection // * Searching for a mate // * Printing of full PV line - tte = TT.retrieve(pos.get_key()); - ttMove = (tte ? tte->move() : MOVE_NONE); - - // Step 5. Evaluate the position statically - // At PV nodes we do this only to update gain statistics - isCheck = pos.is_check(); - if (!isCheck) - { - ss[ply].eval = evaluate(pos, ei, threadID); - update_gains(pos, ss[ply - 1].currentMove, ss[ply - 1].eval, ss[ply].eval); - } - - // Step 6. Razoring (is omitted in PV nodes) - // Step 7. Static null move pruning (is omitted in PV nodes) - // Step 8. Null move search with verification search (is omitted in PV nodes) - - // Step 9. Internal iterative deepening - if ( depth >= IIDDepthAtPVNodes - && ttMove == MOVE_NONE) - { - search_pv(pos, ss, alpha, beta, depth-2*OnePly, ply, threadID); - ttMove = ss[ply].pv[ply]; - tte = TT.retrieve(pos.get_key()); - } - - // Step 10. Loop through moves - // Loop through all legal moves until no moves remain or a beta cutoff occurs - - // Initialize a MovePicker object for the current position - mateThreat = pos.has_mate_threat(opposite_color(pos.side_to_move())); - MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply]); - CheckInfo ci(pos); - - while ( alpha < beta - && (move = mp.get_next_move()) != MOVE_NONE - && !TM.thread_should_stop(threadID)) - { - assert(move_is_ok(move)); - - singleEvasion = (isCheck && mp.number_of_evasions() == 1); - moveIsCheck = pos.move_is_check(move, ci); - captureOrPromotion = pos.move_is_capture_or_promotion(move); - - // Step 11. Decide the new search depth - ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, singleEvasion, mateThreat, &dangerous); - - // Singular extension search. We extend the TT move if its value is much better than - // its siblings. To verify this we do a reduced search on all the other moves but the - // ttMove, if result is lower then ttValue minus a margin then we extend ttMove. - if ( depth >= SingularExtensionDepthAtPVNodes - && tte - && move == tte->move() - && ext < OnePly - && is_lower_bound(tte->type()) - && tte->depth() >= depth - 3 * OnePly) - { - Value ttValue = value_from_tt(tte->value(), ply); - - if (abs(ttValue) < VALUE_KNOWN_WIN) - { - Value excValue = search(pos, ss, ttValue - SingularExtensionMargin, depth / 2, ply, false, threadID, move); - - if (excValue < ttValue - SingularExtensionMargin) - ext = OnePly; - } - } - - newDepth = depth - OnePly + ext; - - // Update current move (this must be done after singular extension search) - movesSearched[moveCount++] = ss[ply].currentMove = move; - - // Step 12. Futility pruning (is omitted in PV nodes) - - // Step 13. Make the move - pos.do_move(move, st, ci, moveIsCheck); - - // Step extra. pv search (only in PV nodes) - // The first move in list is the expected PV - if (moveCount == 1) - value = -search_pv(pos, ss, -beta, -alpha, newDepth, ply+1, threadID); - else - { - // Step 14. Reduced search - // if the move fails high will be re-searched at full depth. - bool doFullDepthSearch = true; - - if ( depth >= 3 * OnePly - && !dangerous - && !captureOrPromotion - && !move_is_castle(move) - && !move_is_killer(move, ss[ply])) - { - ss[ply].reduction = pv_reduction(depth, moveCount); - if (ss[ply].reduction) - { - value = -search(pos, ss, -alpha, newDepth-ss[ply].reduction, ply+1, true, threadID); - doFullDepthSearch = (value > alpha); - } - } - // Step 15. Full depth search - if (doFullDepthSearch) - { - ss[ply].reduction = Depth(0); - value = -search(pos, ss, -alpha, newDepth, ply+1, true, threadID); - - // Step extra. pv search (only in PV nodes) - if (value > alpha && value < beta) - value = -search_pv(pos, ss, -beta, -alpha, newDepth, ply+1, threadID); - } - } - - // Step 16. Undo move - pos.undo_move(move); - - assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); - - // Step 17. Check for new best move - if (value > bestValue) - { - bestValue = value; - if (value > alpha) - { - alpha = value; - update_pv(ss, ply); - if (value == value_mate_in(ply + 1)) - ss[ply].mateKiller = move; - } - } - - // Step 18. Check for split - if ( TM.active_threads() > 1 - && bestValue < beta - && depth >= MinimumSplitDepth - && Iteration <= 99 - && TM.available_thread_exists(threadID) - && !AbortSearch - && !TM.thread_should_stop(threadID) - && TM.split(pos, ss, ply, &alpha, beta, &bestValue, - depth, mateThreat, &moveCount, &mp, threadID, true)) - break; - } - - // Step 19. Check for mate and stalemate - // All legal moves have been searched and if there were - // no legal moves, it must be mate or stalemate. - if (moveCount == 0) - return (isCheck ? value_mated_in(ply) : VALUE_DRAW); - - // Step 20. Update tables - // If the search is not aborted, update the transposition table, - // history counters, and killer moves. - if (AbortSearch || TM.thread_should_stop(threadID)) - return bestValue; - - if (bestValue <= oldAlpha) - TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_UPPER, depth, MOVE_NONE); - - else if (bestValue >= beta) + if (!PvNode && tte && ok_to_use_TT(tte, depth, beta, ply)) { - TM.incrementBetaCounter(pos.side_to_move(), depth, threadID); - move = ss[ply].pv[ply]; - if (!pos.move_is_capture_or_promotion(move)) - { - update_history(pos, move, depth, movesSearched, moveCount); - update_killers(move, ss[ply]); - } - TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, move); - } - else - TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EXACT, depth, ss[ply].pv[ply]); - - return bestValue; - } - - - // search() is the search function for zero-width nodes. - - Value search(Position& pos, SearchStack ss[], Value beta, Depth depth, - int ply, bool allowNullmove, int threadID, Move excludedMove) { - - assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE); - assert(ply >= 0 && ply < PLY_MAX); - assert(threadID >= 0 && threadID < TM.active_threads()); - - Move movesSearched[256]; - EvalInfo ei; - StateInfo st; - const TTEntry* tte; - Move ttMove, move; - Depth ext, newDepth; - Value bestValue, refinedValue, nullValue, value, futilityValueScaled; - bool isCheck, singleEvasion, moveIsCheck, captureOrPromotion, dangerous; - bool mateThreat = false; - int moveCount = 0; - refinedValue = bestValue = value = -VALUE_INFINITE; - - if (depth < OnePly) - return qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID); - - // Step 1. Initialize node and poll - // Polling can abort search. - init_node(ss, ply, threadID); + // Refresh tte entry to avoid aging + TT.store(posKey, tte->value(), tte->type(), tte->depth(), ttMove, tte->static_value(), tte->king_danger()); - // Step 2. Check for aborted search and immediate draw - if (AbortSearch || TM.thread_should_stop(threadID)) - return Value(0); - - if (pos.is_draw() || ply >= PLY_MAX - 1) - return VALUE_DRAW; - - // Step 3. Mate distance pruning - if (value_mated_in(ply) >= beta) - return beta; - - if (value_mate_in(ply + 1) < beta) - return beta - 1; - - // Step 4. Transposition table lookup - - // We don't want the score of a partial search to overwrite a previous full search - // TT value, so we use a different position key in case of an excluded move exists. - Key posKey = excludedMove ? pos.get_exclusion_key() : pos.get_key(); - - tte = TT.retrieve(posKey); - ttMove = (tte ? tte->move() : MOVE_NONE); - - if (tte && ok_to_use_TT(tte, depth, beta, ply)) - { - ss[ply].currentMove = ttMove; // Can be MOVE_NONE + ss->currentMove = ttMove; // Can be MOVE_NONE return value_from_tt(tte->value(), ply); } // Step 5. Evaluate the position statically + // At PV nodes we do this only to update gain statistics isCheck = pos.is_check(); - if (!isCheck) { - if (tte && (tte->type() & VALUE_TYPE_EVAL)) - ss[ply].eval = value_from_tt(tte->value(), ply); + if (tte && tte->static_value() != VALUE_NONE) + { + ss->eval = tte->static_value(); + ei.kingDanger[pos.side_to_move()] = tte->king_danger(); + } else - ss[ply].eval = evaluate(pos, ei, threadID); + ss->eval = evaluate(pos, ei, threadID); - refinedValue = refine_eval(tte, ss[ply].eval, ply); // Enhance accuracy with TT value if possible - update_gains(pos, ss[ply - 1].currentMove, ss[ply - 1].eval, ss[ply].eval); + refinedValue = refine_eval(tte, ss->eval, ply); // Enhance accuracy with TT value if possible + update_gains(pos, (ss-1)->currentMove, (ss-1)->eval, ss->eval); } - // Step 6. Razoring - if ( !value_is_mate(beta) + // Step 6. Razoring (is omitted in PV nodes) + if ( !PvNode + && depth < RazorDepth && !isCheck - && depth < RazorDepth - && refinedValue < beta - razor_margin(depth) - && ss[ply - 1].currentMove != MOVE_NULL - && ttMove == MOVE_NONE + && refinedValue < beta - razor_margin(depth) + && ttMove == MOVE_NONE + && (ss-1)->currentMove != MOVE_NULL + && !value_is_mate(beta) && !pos.has_pawn_on_7th(pos.side_to_move())) { Value rbeta = beta - razor_margin(depth); - Value v = qsearch(pos, ss, rbeta-1, rbeta, Depth(0), ply, threadID); + Value v = qsearch(pos, ss, rbeta-1, rbeta, Depth(0), threadID); if (v < rbeta) // Logically we should return (v + razor_margin(depth)), but // surprisingly this did slightly weaker in tests. return v; } - // Step 7. Static null move pruning + // Step 7. Static null move pruning (is omitted in PV nodes) // We're betting that the opponent doesn't have a move that will reduce - // the score by more than fuility_margin(depth) if we do a null move. - if ( !isCheck - && allowNullmove - && depth < RazorDepth - && refinedValue - futility_margin(depth, 0) >= beta) + // the score by more than futility_margin(depth) if we do a null move. + if ( !PvNode + && allowNullmove + && depth < RazorDepth + && refinedValue >= beta + futility_margin(depth, 0) + && !isCheck + && !value_is_mate(beta) + && pos.non_pawn_material(pos.side_to_move())) return refinedValue - futility_margin(depth, 0); - // Step 8. Null move search with verification search + // Step 8. Null move search with verification search (is omitted in PV nodes) // When we jump directly to qsearch() we do a null move only if static value is // at least beta. Otherwise we do a null move if static value is not more than // NullMoveMargin under beta. - if ( allowNullmove + if ( !PvNode + && allowNullmove && depth > OnePly + && refinedValue >= beta - (depth >= 4 * OnePly ? NullMoveMargin : 0) && !isCheck && !value_is_mate(beta) - && ok_to_do_nullmove(pos) - && refinedValue >= beta - (depth >= 4 * OnePly ? NullMoveMargin : 0)) + && pos.non_pawn_material(pos.side_to_move())) { - ss[ply].currentMove = MOVE_NULL; - - pos.do_null_move(st); + ss->currentMove = MOVE_NULL; // Null move dynamic reduction based on depth int R = 3 + (depth >= 5 * OnePly ? depth / 8 : 0); @@ -1376,20 +1173,25 @@ namespace { if (refinedValue - beta > PawnValueMidgame) R++; - nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID); + pos.do_null_move(st); + nullValue = depth-R*OnePly < OnePly ? -qsearch(pos, ss+1, -beta, -alpha, Depth(0), threadID) + : - search(pos, ss+1, -beta, -alpha, depth-R*OnePly, false, threadID); pos.undo_null_move(); 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 { + // Do not return unproven mate scores + if (nullValue >= value_mate_in(PLY_MAX)) + nullValue = beta; + + // Do zugzwang verification search at high depths + if ( depth < 6 * OnePly + || search(pos, ss, alpha, beta, depth-5*OnePly, false, threadID) >= beta) + return nullValue; + } + else + { // The null move failed low, which means that we may be faced with // some kind of threat. If the previous move was reduced, check if // the move that refuted the null move was somehow connected to the @@ -1399,32 +1201,40 @@ namespace { if (nullValue == value_mated_in(ply + 2)) mateThreat = true; - ss[ply].threatMove = ss[ply + 1].currentMove; + ss->threatMove = (ss+1)->currentMove; if ( depth < ThreatDepth - && ss[ply - 1].reduction - && connected_moves(pos, ss[ply - 1].currentMove, ss[ply].threatMove)) + && (ss-1)->reduction + && connected_moves(pos, (ss-1)->currentMove, ss->threatMove)) return beta - 1; } } // Step 9. Internal iterative deepening - if ( depth >= IIDDepthAtNonPVNodes - && ttMove == MOVE_NONE - && !isCheck - && ss[ply].eval >= beta - IIDMargin) + if ( depth >= IIDDepth[PvNode] + && (ttMove == MOVE_NONE || (PvNode && tte->depth() <= depth - 4 * OnePly)) + && (PvNode || (!isCheck && ss->eval >= beta - IIDMargin))) { - search(pos, ss, beta, depth/2, ply, false, threadID); - ttMove = ss[ply].pv[ply]; + Depth d = (PvNode ? depth - 2 * OnePly : depth / 2); + search(pos, ss, alpha, beta, d, false, threadID); + ttMove = ss->pv[ply]; tte = TT.retrieve(posKey); } - // Step 10. Loop through moves - // Loop through all legal moves until no moves remain or a beta cutoff occurs + // Expensive mate threat detection (only for PV nodes) + if (PvNode) + mateThreat = pos.has_mate_threat(opposite_color(pos.side_to_move())); // Initialize a MovePicker object for the current position - MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply], beta); + MovePicker mp = MovePicker(pos, ttMove, depth, H, ss, (PvNode ? -VALUE_INFINITE : beta)); CheckInfo ci(pos); + bool singularExtensionNode = depth >= SingularExtensionDepth[PvNode] + && tte && tte->move() + && !excludedMove // Do not allow recursive singular extension search + && is_lower_bound(tte->type()) + && tte->depth() >= depth - 3 * OnePly; + // Step 10. Loop through moves + // Loop through all legal moves until no moves remain or a beta cutoff occurs while ( bestValue < beta && (move = mp.get_next_move()) != MOVE_NONE && !TM.thread_should_stop(threadID)) @@ -1434,31 +1244,28 @@ namespace { if (move == excludedMove) continue; - moveIsCheck = pos.move_is_check(move, ci); singleEvasion = (isCheck && mp.number_of_evasions() == 1); + moveIsCheck = pos.move_is_check(move, ci); captureOrPromotion = pos.move_is_capture_or_promotion(move); // Step 11. Decide the new search depth - ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, singleEvasion, mateThreat, &dangerous); + ext = extension(pos, move, captureOrPromotion, moveIsCheck, singleEvasion, mateThreat, &dangerous); // Singular extension search. We extend the TT move if its value is much better than // its siblings. To verify this we do a reduced search on all the other moves but the // ttMove, if result is lower then ttValue minus a margin then we extend ttMove. - if ( depth >= SingularExtensionDepthAtNonPVNodes - && tte + if ( singularExtensionNode && move == tte->move() - && !excludedMove // Do not allow recursive single-reply search - && ext < OnePly - && is_lower_bound(tte->type()) - && tte->depth() >= depth - 3 * OnePly) + && ext < OnePly) { Value ttValue = value_from_tt(tte->value(), ply); if (abs(ttValue) < VALUE_KNOWN_WIN) { - Value excValue = search(pos, ss, ttValue - SingularExtensionMargin, depth / 2, ply, false, threadID, move); + Value b = ttValue - SingularExtensionMargin; + Value v = search(pos, ss, b - 1, b, depth / 2, false, threadID, move); - if (excValue < ttValue - SingularExtensionMargin) + if (v < ttValue - SingularExtensionMargin) ext = OnePly; } } @@ -1466,25 +1273,28 @@ namespace { newDepth = depth - OnePly + ext; // Update current move (this must be done after singular extension search) - movesSearched[moveCount++] = ss[ply].currentMove = move; + movesSearched[moveCount++] = ss->currentMove = move; - // Step 12. Futility pruning - if ( !isCheck - && !dangerous + // Step 12. Futility pruning (is omitted in PV nodes) + if ( !PvNode && !captureOrPromotion - && !move_is_castle(move) - && move != ttMove) + && !isCheck + && !dangerous + && move != ttMove + && !move_is_castle(move)) { // Move count based pruning if ( moveCount >= futility_move_count(depth) - && ok_to_prune(pos, move, ss[ply].threatMove) + && !(ss->threatMove && connected_threat(pos, move, ss->threatMove)) && bestValue > value_mated_in(PLY_MAX)) continue; // Value based pruning - Depth predictedDepth = newDepth - nonpv_reduction(depth, moveCount); // We illogically ignore reduction condition depth >= 3*OnePly - futilityValueScaled = ss[ply].eval + futility_margin(predictedDepth, moveCount) - + H.gain(pos.piece_on(move_from(move)), move_to(move)) + 45; + // We illogically ignore reduction condition depth >= 3*OnePly for predicted depth, + // but fixing this made program slightly weaker. + Depth predictedDepth = newDepth - reduction(depth, moveCount); + futilityValueScaled = ss->eval + futility_margin(predictedDepth, moveCount) + + H.gain(pos.piece_on(move_from(move)), move_to(move)); if (futilityValueScaled < beta) { @@ -1497,29 +1307,60 @@ namespace { // Step 13. Make the move pos.do_move(move, st, ci, moveIsCheck); - // Step 14. Reduced search - // if the move fails high will be re-searched at full depth. - bool doFullDepthSearch = true; - - if ( depth >= 3*OnePly - && !dangerous - && !captureOrPromotion - && !move_is_castle(move) - && !move_is_killer(move, ss[ply])) + // Step extra. pv search (only in PV nodes) + // The first move in list is the expected PV + if (PvNode && moveCount == 1) + value = newDepth < OnePly ? -qsearch(pos, ss+1, -beta, -alpha, Depth(0), threadID) + : - search(pos, ss+1, -beta, -alpha, newDepth, false, threadID); + else { - ss[ply].reduction = nonpv_reduction(depth, moveCount); - if (ss[ply].reduction) + // Step 14. Reduced depth search + // If the move fails high will be re-searched at full depth. + bool doFullDepthSearch = true; + + if ( depth >= 3 * OnePly + && !captureOrPromotion + && !dangerous + && !move_is_castle(move) + && !move_is_killer(move, ss)) { - value = -search(pos, ss, -(beta-1), newDepth-ss[ply].reduction, ply+1, true, threadID); - doFullDepthSearch = (value >= beta); + ss->reduction = reduction(depth, moveCount); + if (ss->reduction) + { + Depth d = newDepth - ss->reduction; + value = d < OnePly ? -qsearch(pos, ss+1, -(alpha+1), -alpha, Depth(0), threadID) + : - search(pos, ss+1, -(alpha+1), -alpha, d, true, threadID); + + doFullDepthSearch = (value > alpha); + } + + // The move failed high, but if reduction is very big we could + // face a false positive, retry with a less aggressive reduction, + // if the move fails high again then go with full depth search. + if (doFullDepthSearch && ss->reduction > 2 * OnePly) + { + assert(newDepth - OnePly >= OnePly); + + ss->reduction = OnePly; + value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, true, threadID); + doFullDepthSearch = (value > alpha); + } + ss->reduction = Depth(0); // Restore original reduction } - } - // Step 15. Full depth search - if (doFullDepthSearch) - { - ss[ply].reduction = Depth(0); - value = -search(pos, ss, -(beta-1), newDepth, ply+1, true, threadID); + // Step 15. Full depth search + if (doFullDepthSearch) + { + value = newDepth < OnePly ? -qsearch(pos, ss+1, -(alpha+1), -alpha, Depth(0), threadID) + : - search(pos, ss+1, -(alpha+1), -alpha, newDepth, true, threadID); + + // Step extra. pv search (only in PV nodes) + // Search only for possible new PV nodes, if instead value >= beta then + // parent node fails low with value <= alpha and tries another move. + if (PvNode && value > alpha && value < beta) + value = newDepth < OnePly ? -qsearch(pos, ss+1, -beta, -alpha, Depth(0), threadID) + : - search(pos, ss+1, -beta, -alpha, newDepth, false, threadID); + } } // Step 16. Undo move @@ -1531,32 +1372,36 @@ namespace { if (value > bestValue) { bestValue = value; - if (value >= beta) + if (value > alpha) + { + if (PvNode && value < beta) // This guarantees that always: alpha < beta + alpha = value; + update_pv(ss, ply); - if (value == value_mate_in(ply + 1)) - ss[ply].mateKiller = move; + if (value == value_mate_in(ply + 1)) + ss->mateKiller = move; + } } // Step 18. Check for split - if ( TM.active_threads() > 1 + if ( depth >= MinimumSplitDepth + && TM.active_threads() > 1 && bestValue < beta - && depth >= MinimumSplitDepth - && Iteration <= 99 && TM.available_thread_exists(threadID) && !AbortSearch && !TM.thread_should_stop(threadID) - && TM.split(pos, ss, ply, NULL, beta, &bestValue, - depth, mateThreat, &moveCount, &mp, threadID, false)) - break; + && Iteration <= 99) + TM.split(pos, ss, &alpha, beta, &bestValue, depth, + mateThreat, &moveCount, &mp, threadID, PvNode); } // Step 19. Check for mate and stalemate - // All legal moves have been searched and if there were + // All legal moves have been searched and if there are // no legal moves, it must be mate or stalemate. - // If one move was excluded return fail low. + // If one move was excluded return fail low score. if (!moveCount) - return excludedMove ? beta - 1 : (pos.is_check() ? value_mated_in(ply) : VALUE_DRAW); + return excludedMove ? oldAlpha : (isCheck ? value_mated_in(ply) : VALUE_DRAW); // Step 20. Update tables // If the search is not aborted, update the transposition table, @@ -1564,20 +1409,22 @@ namespace { if (AbortSearch || TM.thread_should_stop(threadID)) return bestValue; - if (bestValue < beta) - TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_UPPER, depth, MOVE_NONE); - else + if (bestValue <= oldAlpha) + TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_UPPER, depth, MOVE_NONE, ss->eval, ei.kingDanger[pos.side_to_move()]); + + else if (bestValue >= beta) { TM.incrementBetaCounter(pos.side_to_move(), depth, threadID); - move = ss[ply].pv[ply]; - TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, move); + move = ss->pv[ply]; + TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, move, ss->eval, ei.kingDanger[pos.side_to_move()]); if (!pos.move_is_capture_or_promotion(move)) { update_history(pos, move, depth, movesSearched, moveCount); - update_killers(move, ss[ply]); + update_killers(move, ss); } - } + else + TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_EXACT, depth, ss->pv[ply], ss->eval, ei.kingDanger[pos.side_to_move()]); assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); @@ -1589,13 +1436,14 @@ namespace { // search function when the remaining depth is zero (or, to be more precise, // less than OnePly). - Value qsearch(Position& pos, SearchStack ss[], Value alpha, Value beta, - Depth depth, int ply, int threadID) { + template + Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int threadID) { assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE); assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE); + assert(PvNode || alpha == beta - 1); assert(depth <= 0); - assert(ply >= 0 && ply < PLY_MAX); + assert(pos.ply() > 0 && pos.ply() < PLY_MAX); assert(threadID >= 0 && threadID < TM.active_threads()); EvalInfo ei; @@ -1605,17 +1453,13 @@ namespace { bool isCheck, enoughMaterial, moveIsCheck, evasionPrunable; const TTEntry* tte = NULL; int moveCount = 0; - bool pvNode = (beta - alpha != 1); + int ply = pos.ply(); Value oldAlpha = alpha; - // Initialize, and make an early exit in case of an aborted search, - // an instant draw, maximum ply reached, etc. - init_node(ss, ply, threadID); - - // After init_node() that calls poll() - if (AbortSearch || TM.thread_should_stop(threadID)) - return Value(0); + TM.incrementNodeCounter(threadID); + ss->init(ply); + // Check for an instant draw or maximum ply reached if (pos.is_draw() || ply >= PLY_MAX - 1) return VALUE_DRAW; @@ -1624,11 +1468,9 @@ namespace { tte = TT.retrieve(pos.get_key()); ttMove = (tte ? tte->move() : MOVE_NONE); - if (!pvNode && tte && ok_to_use_TT(tte, depth, beta, ply)) + if (!PvNode && tte && ok_to_use_TT(tte, depth, beta, ply)) { - assert(tte->type() != VALUE_TYPE_EVAL); - - ss[ply].currentMove = ttMove; // Can be MOVE_NONE + ss->currentMove = ttMove; // Can be MOVE_NONE return value_from_tt(tte->value(), ply); } @@ -1637,15 +1479,18 @@ namespace { // Evaluate the position statically if (isCheck) staticValue = -VALUE_INFINITE; - else if (tte && (tte->type() & VALUE_TYPE_EVAL)) - staticValue = value_from_tt(tte->value(), ply); + else if (tte && tte->static_value() != VALUE_NONE) + { + staticValue = tte->static_value(); + ei.kingDanger[pos.side_to_move()] = tte->king_danger(); + } else staticValue = evaluate(pos, ei, threadID); if (!isCheck) { - ss[ply].eval = staticValue; - update_gains(pos, ss[ply - 1].currentMove, ss[ply - 1].eval, ss[ply].eval); + ss->eval = staticValue; + update_gains(pos, (ss-1)->currentMove, (ss-1)->eval, ss->eval); } // Initialize "stand pat score", and return it immediately if it is @@ -1655,8 +1500,8 @@ namespace { if (bestValue >= beta) { // Store the score to avoid a future costly evaluation() call - if (!isCheck && !tte && ei.futilityMargin[pos.side_to_move()] == 0) - TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EV_LO, Depth(-127*OnePly), MOVE_NONE); + if (!isCheck && !tte) + TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, Depth(-127*OnePly), MOVE_NONE, ss->eval, ei.kingDanger[pos.side_to_move()]); return bestValue; } @@ -1665,7 +1510,7 @@ namespace { alpha = bestValue; // If we are near beta then try to get a cutoff pushing checks a bit further - bool deepChecks = depth == -OnePly && staticValue >= beta - PawnValueMidgame / 8; + bool deepChecks = (depth == -OnePly && staticValue >= beta - PawnValueMidgame / 8); // Initialize a MovePicker object for the current position, and prepare // to search the moves. Because the depth is <= 0 here, only captures, @@ -1674,10 +1519,9 @@ namespace { MovePicker mp = MovePicker(pos, ttMove, deepChecks ? Depth(0) : depth, H); CheckInfo ci(pos); enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame; - futilityBase = staticValue + FutilityMarginQS + ei.futilityMargin[pos.side_to_move()]; + futilityBase = staticValue + FutilityMarginQS + ei.kingDanger[pos.side_to_move()]; - // Loop through the moves until no moves remain or a beta cutoff - // occurs. + // Loop through the moves until no moves remain or a beta cutoff occurs while ( alpha < beta && (move = mp.get_next_move()) != MOVE_NONE) { @@ -1687,12 +1531,12 @@ namespace { // Update current move moveCount++; - ss[ply].currentMove = move; + ss->currentMove = move; // Futility pruning - if ( enoughMaterial + if ( !PvNode + && enoughMaterial && !isCheck - && !pvNode && !moveIsCheck && move != ttMove && !move_is_promotion(move) @@ -1712,14 +1556,14 @@ namespace { // Detect blocking evasions that are candidate to be pruned evasionPrunable = isCheck - && bestValue != -VALUE_INFINITE + && bestValue > value_mated_in(PLY_MAX) && !pos.move_is_capture(move) && pos.type_of_piece_on(move_from(move)) != KING && !pos.can_castle(pos.side_to_move()); // Don't search moves with negative SEE values - if ( (!isCheck || evasionPrunable) - && !pvNode + if ( !PvNode + && (!isCheck || evasionPrunable) && move != ttMove && !move_is_promotion(move) && pos.see_sign(move) < 0) @@ -1727,7 +1571,7 @@ namespace { // Make and search the move pos.do_move(move, st, ci, moveIsCheck); - value = -qsearch(pos, ss, -beta, -alpha, depth-OnePly, ply+1, threadID); + value = -qsearch(pos, ss+1, -beta, -alpha, depth-OnePly, threadID); pos.undo_move(move); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); @@ -1746,7 +1590,7 @@ namespace { // All legal moves have been searched. A special case: If we're in check // and no legal moves were found, it is checkmate. - if (!moveCount && pos.is_check()) // Mate! + if (!moveCount && isCheck) // Mate! return value_mated_in(ply); // Update transposition table @@ -1755,20 +1599,19 @@ namespace { { // If bestValue isn't changed it means it is still the static evaluation // of the node, so keep this info to avoid a future evaluation() call. - ValueType type = (bestValue == staticValue && !ei.futilityMargin[pos.side_to_move()] ? VALUE_TYPE_EV_UP : VALUE_TYPE_UPPER); - TT.store(pos.get_key(), value_to_tt(bestValue, ply), type, d, MOVE_NONE); + TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_UPPER, d, MOVE_NONE, ss->eval, ei.kingDanger[pos.side_to_move()]); } else if (bestValue >= beta) { - move = ss[ply].pv[ply]; - TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, d, move); + move = ss->pv[ply]; + TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, d, move, ss->eval, ei.kingDanger[pos.side_to_move()]); // Update killers only for good checking moves if (!pos.move_is_capture_or_promotion(move)) - update_killers(move, ss[ply]); + update_killers(move, ss); } else - TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EXACT, d, ss[ply].pv[ply]); + TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EXACT, d, ss->pv[ply], ss->eval, ei.kingDanger[pos.side_to_move()]); assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); @@ -1784,6 +1627,7 @@ namespace { // also don't need to store anything to the hash table here: This is taken // care of after we return from the split point. + template void sp_search(SplitPoint* sp, int threadID) { assert(threadID >= 0 && threadID < TM.active_threads()); @@ -1792,14 +1636,16 @@ namespace { StateInfo st; Move move; Depth ext, newDepth; - Value value, futilityValueScaled; + Value value; + Value futilityValueScaled; // NonPV specific bool isCheck, moveIsCheck, captureOrPromotion, dangerous; int moveCount; value = -VALUE_INFINITE; Position pos(*sp->pos); CheckInfo ci(pos); - SearchStack* ss = sp->sstack[threadID]; + int ply = pos.ply(); + SearchStack* ss = sp->sstack[threadID] + 1; isCheck = pos.is_check(); // Step 10. Loop through moves @@ -1807,10 +1653,10 @@ namespace { lock_grab(&(sp->lock)); while ( sp->bestValue < sp->beta - && !TM.thread_should_stop(threadID) - && (move = sp->mp->get_next_move()) != MOVE_NONE) + && (move = sp->mp->get_next_move()) != MOVE_NONE + && !TM.thread_should_stop(threadID)) { - moveCount = ++sp->moves; + moveCount = ++sp->moveCount; lock_release(&(sp->lock)); assert(move_is_ok(move)); @@ -1819,21 +1665,22 @@ namespace { captureOrPromotion = pos.move_is_capture_or_promotion(move); // Step 11. Decide the new search depth - ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, false, sp->mateThreat, &dangerous); + ext = extension(pos, move, captureOrPromotion, moveIsCheck, false, sp->mateThreat, &dangerous); newDepth = sp->depth - OnePly + ext; // Update current move - ss[sp->ply].currentMove = move; + ss->currentMove = move; - // Step 12. Futility pruning - if ( !isCheck + // Step 12. Futility pruning (is omitted in PV nodes) + if ( !PvNode + && !isCheck && !dangerous && !captureOrPromotion && !move_is_castle(move)) { // Move count based pruning if ( moveCount >= futility_move_count(sp->depth) - && ok_to_prune(pos, move, ss[sp->ply].threatMove) + && !(ss->threatMove && connected_threat(pos, move, ss->threatMove)) && sp->bestValue > value_mated_in(PLY_MAX)) { lock_grab(&(sp->lock)); @@ -1841,9 +1688,9 @@ namespace { } // Value based pruning - Depth predictedDepth = newDepth - nonpv_reduction(sp->depth, moveCount); - futilityValueScaled = ss[sp->ply].eval + futility_margin(predictedDepth, moveCount) - + H.gain(pos.piece_on(move_from(move)), move_to(move)) + 45; + Depth predictedDepth = newDepth - reduction(sp->depth, moveCount); + futilityValueScaled = ss->eval + futility_margin(predictedDepth, moveCount) + + H.gain(pos.piece_on(move_from(move)), move_to(move)); if (futilityValueScaled < sp->beta) { @@ -1859,143 +1706,43 @@ namespace { pos.do_move(move, st, ci, moveIsCheck); // Step 14. Reduced search - // if the move fails high will be re-searched at full depth. + // If the move fails high will be re-searched at full depth. bool doFullDepthSearch = true; if ( !dangerous && !captureOrPromotion && !move_is_castle(move) - && !move_is_killer(move, ss[sp->ply])) + && !move_is_killer(move, ss)) { - ss[sp->ply].reduction = nonpv_reduction(sp->depth, moveCount); - if (ss[sp->ply].reduction) + ss->reduction = reduction(sp->depth, moveCount); + if (ss->reduction) { - value = -search(pos, ss, -(sp->beta-1), newDepth-ss[sp->ply].reduction, sp->ply+1, true, threadID); - doFullDepthSearch = (value >= sp->beta && !TM.thread_should_stop(threadID)); - } - } - - // Step 15. Full depth search - if (doFullDepthSearch) - { - ss[sp->ply].reduction = Depth(0); - value = -search(pos, ss, -(sp->beta - 1), newDepth, sp->ply+1, true, threadID); - } - - // Step 16. Undo move - pos.undo_move(move); - - assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); - - // Step 17. Check for new best move - lock_grab(&(sp->lock)); - - if (value > sp->bestValue && !TM.thread_should_stop(threadID)) - { - sp->bestValue = value; - if (sp->bestValue >= sp->beta) - { - sp->stopRequest = true; - sp_update_pv(sp->parentSstack, ss, sp->ply); + Value localAlpha = sp->alpha; + value = -search(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth-ss->reduction, true, threadID); + doFullDepthSearch = (value > localAlpha); } - } - } - - /* Here we have the lock still grabbed */ - - sp->slaves[threadID] = 0; - sp->cpus--; - - lock_release(&(sp->lock)); - } - - - // sp_search_pv() is used to search from a PV split point. This function - // is called by each thread working at the split point. It is similar to - // the normal search_pv() function, but simpler. Because we have already - // probed the hash table and searched the first move before splitting, we - // don't have to repeat all this work in sp_search_pv(). We also don't - // need to store anything to the hash table here: This is taken care of - // after we return from the split point. - - void sp_search_pv(SplitPoint* sp, int threadID) { - - assert(threadID >= 0 && threadID < TM.active_threads()); - assert(TM.active_threads() > 1); - - StateInfo st; - Move move; - Depth ext, newDepth; - Value value; - bool moveIsCheck, captureOrPromotion, dangerous; - int moveCount; - value = -VALUE_INFINITE; - - Position pos(*sp->pos); - CheckInfo ci(pos); - SearchStack* ss = sp->sstack[threadID]; - - // Step 10. Loop through moves - // Loop through all legal moves until no moves remain or a beta cutoff occurs - lock_grab(&(sp->lock)); - - while ( sp->alpha < sp->beta - && !TM.thread_should_stop(threadID) - && (move = sp->mp->get_next_move()) != MOVE_NONE) - { - moveCount = ++sp->moves; - lock_release(&(sp->lock)); - assert(move_is_ok(move)); - - moveIsCheck = pos.move_is_check(move, ci); - captureOrPromotion = pos.move_is_capture_or_promotion(move); - - // Step 11. Decide the new search depth - ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, false, sp->mateThreat, &dangerous); - newDepth = sp->depth - OnePly + ext; - - // Update current move - ss[sp->ply].currentMove = move; - - // Step 12. Futility pruning (is omitted in PV nodes) - - // Step 13. Make the move - pos.do_move(move, st, ci, moveIsCheck); - - // Step 14. Reduced search - // if the move fails high will be re-searched at full depth. - bool doFullDepthSearch = true; - - if ( !dangerous - && !captureOrPromotion - && !move_is_castle(move) - && !move_is_killer(move, ss[sp->ply])) - { - ss[sp->ply].reduction = pv_reduction(sp->depth, moveCount); - if (ss[sp->ply].reduction) + // The move failed high, but if reduction is very big we could + // face a false positive, retry with a less aggressive reduction, + // if the move fails high again then go with full depth search. + if (doFullDepthSearch && ss->reduction > 2 * OnePly) { + ss->reduction = OnePly; Value localAlpha = sp->alpha; - value = -search(pos, ss, -localAlpha, newDepth-ss[sp->ply].reduction, sp->ply+1, true, threadID); - doFullDepthSearch = (value > localAlpha && !TM.thread_should_stop(threadID)); + value = -search(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth-ss->reduction, true, threadID); + doFullDepthSearch = (value > localAlpha); } } // Step 15. Full depth search if (doFullDepthSearch) { + ss->reduction = Depth(0); Value localAlpha = sp->alpha; - ss[sp->ply].reduction = Depth(0); - value = -search(pos, ss, -localAlpha, newDepth, sp->ply+1, true, threadID); + value = -search(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth, true, threadID); - if (value > localAlpha && value < sp->beta && !TM.thread_should_stop(threadID)) - { - // If another thread has failed high then sp->alpha has been increased - // to be higher or equal then beta, if so, avoid to start a PV search. - localAlpha = sp->alpha; - if (localAlpha < sp->beta) - value = -search_pv(pos, ss, -sp->beta, -localAlpha, newDepth, sp->ply+1, threadID); - } + if (PvNode && value > localAlpha && value < sp->beta) + value = -search(pos, ss+1, -sp->beta, -sp->alpha, newDepth, false, threadID); } // Step 16. Undo move @@ -2009,17 +1756,16 @@ namespace { if (value > sp->bestValue && !TM.thread_should_stop(threadID)) { sp->bestValue = value; - if (value > sp->alpha) + + if (sp->bestValue > sp->alpha) { - // Ask threads to stop before to modify sp->alpha - if (value >= sp->beta) + if (!PvNode || value >= sp->beta) sp->stopRequest = true; - sp->alpha = value; + if (PvNode && value < sp->beta) // This guarantees that always: sp->alpha < sp->beta + sp->alpha = value; - sp_update_pv(sp->parentSstack, ss, sp->ply); - if (value == value_mate_in(sp->ply + 1)) - ss[sp->ply].mateKiller = move; + sp_update_pv(sp->parentSstack, ss, ply); } } } @@ -2027,55 +1773,26 @@ namespace { /* Here we have the lock still grabbed */ sp->slaves[threadID] = 0; - sp->cpus--; lock_release(&(sp->lock)); } - - // init_node() is called at the beginning of all the search functions - // (search(), search_pv(), qsearch(), and so on) and initializes the - // search stack object corresponding to the current node. Once every - // NodesBetweenPolls nodes, init_node() also calls poll(), which polls - // for user input and checks whether it is time to stop the search. - - void init_node(SearchStack ss[], int ply, int threadID) { - - assert(ply >= 0 && ply < PLY_MAX); - assert(threadID >= 0 && threadID < TM.active_threads()); - - TM.incrementNodeCounter(threadID); - - if (threadID == 0) - { - NodesSincePoll++; - if (NodesSincePoll >= NodesBetweenPolls) - { - poll(ss, ply); - NodesSincePoll = 0; - } - } - ss[ply].init(ply); - ss[ply + 2].initKillers(); - } - - // update_pv() is called whenever a search returns a value > alpha. // It updates the PV in the SearchStack object corresponding to the // current node. - void update_pv(SearchStack ss[], int ply) { + void update_pv(SearchStack* ss, int ply) { assert(ply >= 0 && ply < PLY_MAX); int p; - ss[ply].pv[ply] = ss[ply].currentMove; + ss->pv[ply] = ss->currentMove; - for (p = ply + 1; ss[ply + 1].pv[p] != MOVE_NONE; p++) - ss[ply].pv[p] = ss[ply + 1].pv[p]; + for (p = ply + 1; (ss+1)->pv[p] != MOVE_NONE; p++) + ss->pv[p] = (ss+1)->pv[p]; - ss[ply].pv[p] = MOVE_NONE; + ss->pv[p] = MOVE_NONE; } @@ -2083,18 +1800,18 @@ namespace { // difference between the two functions is that sp_update_pv also updates // the PV at the parent node. - void sp_update_pv(SearchStack* pss, SearchStack ss[], int ply) { + void sp_update_pv(SearchStack* pss, SearchStack* ss, int ply) { assert(ply >= 0 && ply < PLY_MAX); int p; - ss[ply].pv[ply] = pss[ply].pv[ply] = ss[ply].currentMove; + ss->pv[ply] = pss->pv[ply] = ss->currentMove; - for (p = ply + 1; ss[ply + 1].pv[p] != MOVE_NONE; p++) - ss[ply].pv[p] = pss[ply].pv[p] = ss[ply + 1].pv[p]; + for (p = ply + 1; (ss+1)->pv[p] != MOVE_NONE; p++) + ss->pv[p] = pss->pv[p] = (ss+1)->pv[p]; - ss[ply].pv[p] = pss[ply].pv[p] = MOVE_NONE; + ss->pv[p] = pss->pv[p] = MOVE_NONE; } @@ -2169,9 +1886,9 @@ 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) { + bool move_is_killer(Move m, SearchStack* ss) { - const Move* k = ss.killers; + const Move* k = ss->killers; for (int i = 0; i < KILLER_MAX; i++, k++) if (*k == m) return true; @@ -2186,9 +1903,9 @@ namespace { // any case are marked as 'dangerous'. Note that also if a move is not // extended, as example because the corresponding UCI option is set to zero, // the move is marked as 'dangerous' so, at least, we avoid to prune it. - - Depth extension(const Position& pos, Move m, bool pvNode, bool captureOrPromotion, - bool moveIsCheck, bool singleEvasion, bool mateThreat, bool* dangerous) { + template + Depth extension(const Position& pos, Move m, bool captureOrPromotion, bool moveIsCheck, + bool singleEvasion, bool mateThreat, bool* dangerous) { assert(m != MOVE_NONE); @@ -2198,13 +1915,13 @@ namespace { if (*dangerous) { if (moveIsCheck) - result += CheckExtension[pvNode]; + result += CheckExtension[PvNode]; if (singleEvasion) - result += SingleEvasionExtension[pvNode]; + result += SingleEvasionExtension[PvNode]; if (mateThreat) - result += MateThreatExtension[pvNode]; + result += MateThreatExtension[PvNode]; } if (pos.type_of_piece_on(move_from(m)) == PAWN) @@ -2212,12 +1929,12 @@ namespace { Color c = pos.side_to_move(); if (relative_rank(c, move_to(m)) == RANK_7) { - result += PawnPushTo7thExtension[pvNode]; + result += PawnPushTo7thExtension[PvNode]; *dangerous = true; } if (pos.pawn_is_passed(c, move_to(m))) { - result += PassedPawnExtension[pvNode]; + result += PassedPawnExtension[PvNode]; *dangerous = true; } } @@ -2229,11 +1946,11 @@ namespace { && !move_is_promotion(m) && !move_is_ep(m)) { - result += PawnEndgameExtension[pvNode]; + result += PawnEndgameExtension[PvNode]; *dangerous = true; } - if ( pvNode + if ( PvNode && captureOrPromotion && pos.type_of_piece_on(move_to(m)) != PAWN && pos.see_sign(m) >= 0) @@ -2246,38 +1963,19 @@ namespace { } - // ok_to_do_nullmove() looks at the current position and decides whether - // doing a 'null move' should be allowed. In order to avoid zugzwang - // problems, null moves are not allowed when the side to move has very - // little material left. Currently, the test is a bit too simple: Null - // moves are avoided only when the side to move has only pawns left. - // It's probably a good idea to avoid null moves in at least some more - // complicated endgames, e.g. KQ vs KR. FIXME + // connected_threat() tests whether it is safe to forward prune a move or if + // is somehow coonected to the threat move returned by null search. - bool ok_to_do_nullmove(const Position& pos) { - - return pos.non_pawn_material(pos.side_to_move()) != Value(0); - } - - - // ok_to_prune() tests whether it is safe to forward prune a move. Only - // non-tactical moves late in the move list close to the leaves are - // candidates for pruning. - - bool ok_to_prune(const Position& pos, Move m, Move threat) { + bool connected_threat(const Position& pos, Move m, Move threat) { assert(move_is_ok(m)); - assert(threat == MOVE_NONE || move_is_ok(threat)); + assert(threat && move_is_ok(threat)); assert(!pos.move_is_check(m)); assert(!pos.move_is_capture_or_promotion(m)); assert(!pos.move_is_passed_pawn_push(m)); Square mfrom, mto, tfrom, tto; - // Prune if there isn't any threat move - if (threat == MOVE_NONE) - return true; - mfrom = move_from(m); mto = move_to(m); tfrom = move_from(threat); @@ -2285,7 +1983,7 @@ namespace { // Case 1: Don't prune moves which move the threatened piece if (mfrom == tto) - return false; + return true; // Case 2: If the threatened piece has value less than or equal to the // value of the threatening piece, don't prune move which defend it. @@ -2293,16 +1991,16 @@ namespace { && ( pos.midgame_value_of_piece_on(tfrom) >= pos.midgame_value_of_piece_on(tto) || pos.type_of_piece_on(tfrom) == KING) && pos.move_attacks_square(m, tto)) - return false; + return true; // Case 3: If the moving piece in the threatened move is a slider, don't // prune safe moves which block its ray. if ( piece_is_slider(pos.piece_on(tfrom)) && bit_is_set(squares_between(tfrom, tto), mto) && pos.see_sign(m) >= 0) - return false; + return true; - return true; + return false; } @@ -2365,15 +2063,15 @@ namespace { // update_killers() add a good move that produced a beta-cutoff // among the killer moves of that ply. - void update_killers(Move m, SearchStack& ss) { + void update_killers(Move m, SearchStack* ss) { - if (m == ss.killers[0]) + if (m == ss->killers[0]) return; for (int i = KILLER_MAX - 1; i > 0; i--) - ss.killers[i] = ss.killers[i - 1]; + ss->killers[i] = ss->killers[i - 1]; - ss.killers[0] = m; + ss->killers[0] = m; } @@ -2414,7 +2112,7 @@ namespace { // looks at the time consumed so far and decides if it's time to abort the // search. - void poll(SearchStack ss[], int ply) { + void poll() { static int lastInfoTime; int t = current_search_time(); @@ -2465,16 +2163,6 @@ namespace { cout << "info nodes " << TM.nodes_searched() << " nps " << nps() << " time " << t << " hashfull " << TT.full() << endl; - - // We only support current line printing in single thread mode - if (ShowCurrentLine && TM.active_threads() == 1) - { - cout << "info currline"; - for (int p = 0; p < ply; p++) - cout << " " << ss[p].currentMove; - - cout << endl; - } } // Should we stop the search? @@ -2518,12 +2206,12 @@ namespace { // init_ss_array() does a fast reset of the first entries of a SearchStack array - void init_ss_array(SearchStack ss[]) { + void init_ss_array(SearchStack* ss) { - for (int i = 0; i < 3; i++) + for (int i = 0; i < 3; i++, ss++) { - ss[i].init(i); - ss[i].initKillers(); + ss->init(i); + ss->initKillers(); } } @@ -2558,7 +2246,7 @@ namespace { // print_pv_info() prints to standard output and eventually to log file information on // the current PV line. It is called at each iteration or after a new pv is found. - void print_pv_info(const Position& pos, SearchStack ss[], Value alpha, Value beta, Value value) { + void print_pv_info(const Position& pos, SearchStack* ss, Value alpha, Value beta, Value value) { cout << "info depth " << Iteration << " score " << value_to_string(value) @@ -2569,8 +2257,8 @@ namespace { << " nps " << nps() << " pv "; - for (int j = 0; ss[0].pv[j] != MOVE_NONE && j < PLY_MAX; j++) - cout << ss[0].pv[j] << " "; + for (int j = 0; ss->pv[j] != MOVE_NONE && j < PLY_MAX; j++) + cout << ss->pv[j] << " "; cout << endl; @@ -2580,7 +2268,7 @@ namespace { : (value <= alpha ? VALUE_TYPE_UPPER : VALUE_TYPE_EXACT)); LogFile << pretty_pv(pos, current_search_time(), Iteration, - TM.nodes_searched(), value, type, ss[0].pv) << endl; + TM.nodes_searched(), value, type, ss->pv) << endl; } } @@ -2648,10 +2336,10 @@ namespace { // idle_loop() is where the threads are parked when they have no work to do. - // The parameter "waitSp", if non-NULL, is a pointer to an active SplitPoint + // The parameter 'sp', if non-NULL, is a pointer to an active SplitPoint // object for which the current thread is the master. - void ThreadsManager::idle_loop(int threadID, SplitPoint* waitSp) { + void ThreadsManager::idle_loop(int threadID, SplitPoint* sp) { assert(threadID >= 0 && threadID < MAX_THREADS); @@ -2661,7 +2349,7 @@ namespace { // master should exit as last one. if (AllThreadsShouldExit) { - assert(!waitSp); + assert(!sp); threads[threadID].state = THREAD_TERMINATED; return; } @@ -2670,7 +2358,7 @@ namespace { // instead of wasting CPU time polling for work. while (AllThreadsShouldSleep || threadID >= ActiveThreads) { - assert(!waitSp); + assert(!sp); assert(threadID != 0); threads[threadID].state = THREAD_SLEEPING; @@ -2696,19 +2384,27 @@ namespace { threads[threadID].state = THREAD_SEARCHING; if (threads[threadID].splitPoint->pvNode) - sp_search_pv(threads[threadID].splitPoint, threadID); + sp_search(threads[threadID].splitPoint, threadID); else - sp_search(threads[threadID].splitPoint, threadID); + sp_search(threads[threadID].splitPoint, threadID); assert(threads[threadID].state == THREAD_SEARCHING); threads[threadID].state = THREAD_AVAILABLE; } - // If this thread is the master of a split point and all threads have + // If this thread is the master of a split point and all slaves have // finished their work at this split point, return from the idle loop. - if (waitSp != NULL && waitSp->cpus == 0) + int i = 0; + for ( ; sp && i < ActiveThreads && !sp->slaves[i]; i++) {} + + if (i == ActiveThreads) { + // Because sp->slaves[] is reset under lock protection, + // be sure sp->lock has been released before to return. + lock_grab(&(sp->lock)); + lock_release(&(sp->lock)); + assert(threads[threadID].state == THREAD_AVAILABLE); threads[threadID].state = THREAD_SEARCHING; @@ -2745,10 +2441,7 @@ namespace { // Initialize SplitPointStack locks for (i = 0; i < MAX_THREADS; i++) for (int j = 0; j < ACTIVE_SPLIT_POINTS_MAX; j++) - { - SplitPointStack[i][j].parent = NULL; lock_init(&(SplitPointStack[i][j].lock), NULL); - } // Will be set just before program exits to properly end the threads AllThreadsShouldExit = false; @@ -2779,7 +2472,7 @@ namespace { } // Wait until the thread has finished launching and is gone to sleep - while (threads[i].state != THREAD_SLEEPING); + while (threads[i].state != THREAD_SLEEPING) {} } } @@ -2798,7 +2491,7 @@ namespace { // Wait for thread termination for (int i = 1; i < MAX_THREADS; i++) - while (threads[i].state != THREAD_TERMINATED); + while (threads[i].state != THREAD_TERMINATED) {} // Now we can safely destroy the locks for (int i = 0; i < MAX_THREADS; i++) @@ -2820,7 +2513,7 @@ namespace { SplitPoint* sp; - for (sp = threads[threadID].splitPoint; sp && !sp->stopRequest; sp = sp->parent); + for (sp = threads[threadID].splitPoint; sp && !sp->stopRequest; sp = sp->parent) {} return sp != NULL; } @@ -2880,35 +2573,28 @@ namespace { // split() does the actual work of distributing the work at a node between - // several threads at PV nodes. If it does not succeed in splitting the + // several available threads. If it does not succeed in splitting the // node (because no idle threads are available, or because we have no unused - // split point objects), the function immediately returns false. If - // splitting is possible, a SplitPoint object is initialized with all the - // data that must be copied to the helper threads (the current position and - // search stack, alpha, beta, the search depth, etc.), and we tell our - // helper threads that they have been assigned work. This will cause them - // to instantly leave their idle loops and call sp_search_pv(). When all - // threads have returned from sp_search_pv (or, equivalently, when - // splitPoint->cpus becomes 0), split() returns true. - - bool ThreadsManager::split(const Position& p, SearchStack* sstck, int ply, - Value* alpha, const Value beta, Value* bestValue, - Depth depth, bool mateThreat, int* moves, MovePicker* mp, int master, bool pvNode) { - + // split point objects), the function immediately returns. If splitting is + // possible, a SplitPoint object is initialized with all the data that must be + // copied to the helper threads and we tell our helper threads that they have + // been assigned work. This will cause them to instantly leave their idle loops + // and call sp_search(). When all threads have returned from sp_search() then + // split() returns. + + template + void ThreadsManager::split(const Position& p, SearchStack* ss, Value* alpha, const Value beta, + Value* bestValue, Depth depth, bool mateThreat, int* moveCount, + MovePicker* mp, int master, bool pvNode) { assert(p.is_ok()); - assert(sstck != NULL); - assert(ply >= 0 && ply < PLY_MAX); assert(*bestValue >= -VALUE_INFINITE); - assert( ( pvNode && *bestValue <= *alpha) - || (!pvNode && *bestValue < beta )); - assert(!pvNode || *alpha < beta); + assert(*bestValue <= *alpha); + assert(*alpha < beta); assert(beta <= VALUE_INFINITE); assert(depth > Depth(0)); assert(master >= 0 && master < ActiveThreads); assert(ActiveThreads > 1); - SplitPoint* splitPoint; - lock_grab(&MPLock); // If no other thread is available to help us, or if we have too many @@ -2917,28 +2603,25 @@ namespace { || threads[master].activeSplitPoints >= ACTIVE_SPLIT_POINTS_MAX) { lock_release(&MPLock); - return false; + return; } // Pick the next available split point object from the split point stack - splitPoint = &SplitPointStack[master][threads[master].activeSplitPoints]; + SplitPoint* splitPoint = &SplitPointStack[master][threads[master].activeSplitPoints]; // Initialize the split point object splitPoint->parent = threads[master].splitPoint; splitPoint->stopRequest = false; - splitPoint->ply = ply; splitPoint->depth = depth; splitPoint->mateThreat = mateThreat; - splitPoint->alpha = pvNode ? *alpha : beta - 1; + splitPoint->alpha = *alpha; splitPoint->beta = beta; splitPoint->pvNode = pvNode; splitPoint->bestValue = *bestValue; - splitPoint->master = master; splitPoint->mp = mp; - splitPoint->moves = *moves; - splitPoint->cpus = 1; + splitPoint->moveCount = *moveCount; splitPoint->pos = &p; - splitPoint->parentSstack = sstck; + splitPoint->parentSstack = ss; for (int i = 0; i < ActiveThreads; i++) splitPoint->slaves[i] = 0; @@ -2948,17 +2631,19 @@ namespace { // If we are here it means we are not available assert(threads[master].state != THREAD_AVAILABLE); + int workersCnt = 1; // At least the master is included + // Allocate available threads setting state to THREAD_BOOKED - for (int i = 0; i < ActiveThreads && splitPoint->cpus < MaxThreadsPerSplitPoint; i++) + for (int i = 0; !Fake && i < ActiveThreads && workersCnt < MaxThreadsPerSplitPoint; i++) if (thread_is_available(i, master)) { threads[i].state = THREAD_BOOKED; threads[i].splitPoint = splitPoint; splitPoint->slaves[i] = 1; - splitPoint->cpus++; + workersCnt++; } - assert(splitPoint->cpus > 1); + assert(Fake || workersCnt > 1); // We can release the lock because slave threads are already booked and master is not available lock_release(&MPLock); @@ -2968,7 +2653,7 @@ namespace { for (int i = 0; i < ActiveThreads; i++) if (i == master || splitPoint->slaves[i]) { - memcpy(splitPoint->sstack[i] + ply - 1, sstck + ply - 1, 4 * sizeof(SearchStack)); + memcpy(splitPoint->sstack[i], ss - 1, 4 * sizeof(SearchStack)); assert(i == master || threads[i].state == THREAD_BOOKED); @@ -2979,23 +2664,19 @@ namespace { // which it will instantly launch a search, because its state is // THREAD_WORKISWAITING. We send the split point as a second parameter to the // idle loop, which means that the main thread will return from the idle - // loop when all threads have finished their work at this split point - // (i.e. when splitPoint->cpus == 0). + // loop when all threads have finished their work at this split point. idle_loop(master, splitPoint); // We have returned from the idle loop, which means that all threads are - // finished. Update alpha, beta and bestValue, and return. + // finished. Update alpha and bestValue, and return. lock_grab(&MPLock); - if (pvNode) - *alpha = splitPoint->alpha; - + *alpha = splitPoint->alpha; *bestValue = splitPoint->bestValue; threads[master].activeSplitPoints--; threads[master].splitPoint = splitPoint->parent; lock_release(&MPLock); - return true; } @@ -3065,7 +2746,7 @@ namespace { init_ss_array(ss); pos.do_move(cur->move, st); moves[count].move = cur->move; - moves[count].score = -qsearch(pos, ss, -VALUE_INFINITE, VALUE_INFINITE, Depth(0), 1, 0); + moves[count].score = -qsearch(pos, ss+1, -VALUE_INFINITE, VALUE_INFINITE, Depth(0), 0); moves[count].pv[0] = cur->move; moves[count].pv[1] = MOVE_NONE; pos.undo_move(cur->move);