X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=1f848183481a573cf59710f2993a1c4fb890a1f2;hp=0fa5290616861f0f32cf8dea39d9f79e6ea9296b;hb=a90a990118fa84d1e6138654dd24d2f7f4ec3761;hpb=1036cadcecc43737a1234eec00960a5a81073971 diff --git a/src/search.cpp b/src/search.cpp index 0fa52906..1f848183 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -49,7 +49,7 @@ namespace { const bool FakeSplit = false; // Different node types, used as template parameter - enum NodeType { Root, PV, NonPV, SplitPointPV, SplitPointNonPV }; + 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 @@ -175,7 +175,6 @@ namespace { // 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. - bool SendSearchedNodes; int NodesSincePoll; int NodesBetweenPolls = 30000; @@ -197,7 +196,7 @@ namespace { bool connected_moves(const Position& pos, Move m1, Move m2); Value value_to_tt(Value v, int ply); Value value_from_tt(Value v, int ply); - bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply); + bool can_return_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); @@ -216,14 +215,14 @@ namespace { // 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. - template struct MovePickerExt : public MovePicker { + template struct MovePickerExt : public MovePicker { MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b) : MovePicker(p, ttm, d, h, ss, b) {} }; // In case of a SpNode we use split point's shared MovePicker object as moves source - template<> struct MovePickerExt : public MovePicker { + template<> struct MovePickerExt : public MovePicker { MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b) : MovePicker(p, ttm, d, h, ss, b), mp(ss->sp->mp) {} @@ -232,12 +231,6 @@ namespace { MovePicker* mp; }; - template<> struct MovePickerExt : public MovePickerExt { - - MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b) - : MovePickerExt(p, ttm, d, h, ss, b) {} - }; - // Overload operator<<() to make it easier to print moves in a coordinate // notation compatible with UCI protocol. std::ostream& operator<<(std::ostream& os, Move m) { @@ -370,10 +363,10 @@ int64_t perft(Position& pos, Depth depth) { bool think(Position& pos, const SearchLimits& limits, Move searchMoves[]) { - static Book book; + static Book book; // Define static to initialize the PRNG only once // Initialize global search-related variables - StopOnPonderhit = StopRequest = QuitRequest = AspirationFailLow = SendSearchedNodes = false; + StopOnPonderhit = StopRequest = QuitRequest = AspirationFailLow = false; NodesSincePoll = 0; current_search_time(get_system_time()); Limits = limits; @@ -416,8 +409,7 @@ bool think(Position& pos, const SearchLimits& limits, Move searchMoves[]) { read_evaluation_uci_options(pos.side_to_move()); Threads.read_uci_options(); - // If needed allocate pawn and material hash tables and adjust TT size - Threads.init_hash_tables(); + // Set a new TT size if changed TT.set_size(Options["Hash"].value()); if (Options["Clear Hash"].value()) @@ -542,8 +534,10 @@ namespace { Rml.bestMoveChanges = 0; - // MultiPV iteration loop - for (MultiPVIteration = 0; MultiPVIteration < Min(MultiPV, (int)Rml.size()); MultiPVIteration++) + // 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++) { // Calculate dynamic aspiration window based on previous iterations if (depth >= 5 && abs(Rml[MultiPVIteration].prevScore) < VALUE_KNOWN_WIN) @@ -566,7 +560,8 @@ 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 calling update_gains() + // 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 @@ -593,8 +588,7 @@ namespace { // 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); i++) - { + 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) : @@ -602,7 +596,6 @@ namespace { << 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. @@ -701,9 +694,9 @@ namespace { template Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth) { - const bool PvNode = (NT == PV || NT == Root || NT == SplitPointPV); - const bool SpNode = (NT == SplitPointPV || NT == SplitPointNonPV); - const bool RootNode = (NT == Root); + const bool PvNode = (NT == PV || NT == Root || NT == SplitPointPV || NT == SplitPointRoot); + const bool SpNode = (NT == SplitPointPV || NT == SplitPointNonPV || NT == SplitPointRoot); + const bool RootNode = (NT == Root || NT == SplitPointRoot); assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE); assert(beta > alpha && beta <= VALUE_INFINITE); @@ -719,7 +712,7 @@ namespace { Depth ext, newDepth; ValueType vt; Value bestValue, value, oldAlpha; - Value refinedValue, nullValue, futilityBase, futilityValueScaled; // Non-PV specific + Value refinedValue, nullValue, futilityBase, futilityValue; bool isPvMove, inCheck, singularExtensionNode, givesCheck, captureOrPromotion, dangerous; int moveCount = 0, playedMoveCount = 0; Thread& thread = Threads[pos.thread()]; @@ -777,18 +770,28 @@ namespace { excludedMove = ss->excludedMove; posKey = excludedMove ? pos.get_exclusion_key() : pos.get_key(); tte = TT.probe(posKey); - ttMove = tte ? tte->move() : MOVE_NONE; + ttMove = RootNode ? Rml[MultiPVIteration].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 // smooth experience in analysis mode. We don't probe at Root nodes otherwise // we should also update RootMoveList to avoid bogus output. if (!RootNode && tte && (PvNode ? tte->depth() >= depth && tte->type() == VALUE_TYPE_EXACT - : ok_to_use_TT(tte, depth, beta, ss->ply))) + : 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.move_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 @@ -948,7 +951,7 @@ namespace { split_point_start: // At split points actual search starts from here // Initialize a MovePicker object for the current position - MovePickerExt mp(pos, RootNode ? Rml[MultiPVIteration].pv[0] : ttMove, depth, H, ss, PvNode ? -VALUE_INFINITE : beta); + MovePickerExt mp(pos, ttMove, depth, H, ss, PvNode ? -VALUE_INFINITE : beta); CheckInfo ci(pos); ss->bestMove = MOVE_NONE; futilityBase = ss->eval + ss->evalMargin; @@ -978,7 +981,7 @@ split_point_start: // At split points actual search starts from here // 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. + // in previous MultiPV Iteration. Finally any illegal move is skipped here. if (RootNode && !Rml.find(move, MultiPVIteration)) continue; @@ -1002,22 +1005,14 @@ split_point_start: // At split points actual search starts from here // Save the current node count before the move is searched nodes = pos.nodes_searched(); - // If it's time to send nodes info, do it here where we have the - // correct accumulated node counts searched by each thread. - if (SendSearchedNodes) - { - SendSearchedNodes = false; - cout << "info" << speed_to_uci(pos.nodes_searched()) << endl; - } - // For long searches send current move info to GUI - if (current_search_time() > 2000) + if (pos.thread() == 0 && current_search_time() > 2000) cout << "info" << depth_to_uci(depth) - << " currmove " << move << " currmovenumber " << moveCount + MultiPVIteration << endl; + << " currmove " << move + << " currmovenumber " << moveCount + MultiPVIteration << endl; } - // At Root and at first iteration do a PV search on all the moves to score root moves - isPvMove = (PvNode && moveCount <= ((RootNode && depth <= ONE_PLY) ? MAX_MOVES : 1)); + isPvMove = (PvNode && moveCount == 1); givesCheck = pos.move_gives_check(move, ci); captureOrPromotion = pos.move_is_capture_or_promotion(move); @@ -1076,19 +1071,19 @@ split_point_start: // At split points actual search starts from here // We illogically ignore reduction condition depth >= 3*ONE_PLY for predicted depth, // but fixing this made program slightly weaker. Depth predictedDepth = newDepth - reduction(depth, moveCount); - futilityValueScaled = futilityBase + futility_margin(predictedDepth, moveCount) - + H.gain(pos.piece_on(move_from(move)), move_to(move)); + futilityValue = futilityBase + futility_margin(predictedDepth, moveCount) + + H.gain(pos.piece_on(move_from(move)), move_to(move)); - if (futilityValueScaled < beta) + if (futilityValue < beta) { if (SpNode) { lock_grab(&(sp->lock)); - if (futilityValueScaled > sp->bestValue) - sp->bestValue = bestValue = futilityValueScaled; + if (futilityValue > sp->bestValue) + sp->bestValue = bestValue = futilityValue; } - else if (futilityValueScaled > bestValue) - bestValue = futilityValueScaled; + else if (futilityValue > bestValue) + bestValue = futilityValue; continue; } @@ -1177,36 +1172,12 @@ split_point_start: // At split points actual search starts from here alpha = sp->alpha; } - if (value > bestValue) + // Finished searching the move. If StopRequest is true, the search + // was aborted because the user interrupted the search or because we + // ran out of time. In this case, the return value of the search cannot + // be trusted, and we don't update the best move and/or PV. + if (RootNode && !StopRequest) { - bestValue = value; - ss->bestMove = move; - - if ( !RootNode - && PvNode - && value > alpha - && value < beta) // We want always alpha < beta - alpha = value; - - if (SpNode && !thread.cutoff_occurred()) - { - sp->bestValue = value; - sp->ss->bestMove = move; - sp->alpha = alpha; - sp->is_betaCutoff = (value >= beta); - } - } - - if (RootNode) - { - // Finished searching the move. If StopRequest is true, the search - // was aborted because the user interrupted the search or because we - // ran out of time. In this case, the return value of the search cannot - // be trusted, and we break out of the loop without updating the best - // move and/or PV. - if (StopRequest) - break; - // Remember searched nodes counts for this move RootMove* rm = Rml.find(move); rm->nodes += pos.nodes_searched() - nodes; @@ -1223,10 +1194,6 @@ split_point_start: // At split points actual search starts from here // the best move changes frequently, we allocate some more time. if (!isPvMove && MultiPV == 1) Rml.bestMoveChanges++; - - // Update alpha. - if (value > alpha) - alpha = value; } else // All other moves but the PV are set to the lowest value, this @@ -1236,16 +1203,34 @@ split_point_start: // At split points actual search starts from here } // RootNode + if (value > bestValue) + { + bestValue = value; + ss->bestMove = move; + + if ( PvNode + && value > alpha + && value < beta) // We want always alpha < beta + alpha = value; + + if (SpNode && !thread.cutoff_occurred()) + { + sp->bestValue = value; + sp->ss->bestMove = move; + sp->alpha = alpha; + sp->is_betaCutoff = (value >= beta); + } + } + // Step 19. Check for split - if ( !RootNode - && !SpNode + if ( !SpNode && depth >= Threads.min_split_depth() && bestValue < beta && Threads.available_slave_exists(pos.thread()) && !StopRequest && !thread.cutoff_occurred()) - Threads.split(pos, ss, &alpha, beta, &bestValue, depth, - threatMove, moveCount, &mp, PvNode); + bestValue = Threads.split(pos, ss, alpha, beta, bestValue, depth, + threatMove, moveCount, &mp, NT); } // Step 20. Check for mate and stalemate @@ -1314,6 +1299,7 @@ split_point_start: // At split points actual search starts from here bool inCheck, enoughMaterial, givesCheck, evasionPrunable; const TTEntry* tte; Depth ttDepth; + ValueType vt; Value oldAlpha = alpha; ss->bestMove = ss->currentMove = MOVE_NONE; @@ -1334,7 +1320,7 @@ split_point_start: // At split points actual search starts from here tte = TT.probe(pos.get_key()); ttMove = (tte ? tte->move() : MOVE_NONE); - if (!PvNode && tte && ok_to_use_TT(tte, ttDepth, beta, ss->ply)) + if (!PvNode && tte && can_return_tt(tte, ttDepth, beta, ss->ply)) { ss->bestMove = ttMove; // Can be MOVE_NONE return value_from_tt(tte->value(), ss->ply); @@ -1384,7 +1370,7 @@ split_point_start: // At split points actual search starts from here CheckInfo ci(pos); // Loop through the moves until no moves remain or a beta cutoff occurs - while ( alpha < beta + while ( bestValue < beta && (move = mp.get_next_move()) != MOVE_NONE) { assert(move_is_ok(move)); @@ -1404,10 +1390,11 @@ split_point_start: // At split points actual search starts from here + piece_value_endgame(pos.piece_on(move_to(move))) + (move_is_ep(move) ? PawnValueEndgame : VALUE_ZERO); - if (futilityValue < alpha) + if (futilityValue < beta) { if (futilityValue > bestValue) bestValue = futilityValue; + continue; } @@ -1466,11 +1453,12 @@ split_point_start: // At split points actual search starts from here if (value > bestValue) { bestValue = value; - if (value > alpha) - { + ss->bestMove = move; + + if ( PvNode + && value > alpha + && value < beta) // We want always alpha < beta alpha = value; - ss->bestMove = move; - } } } @@ -1480,8 +1468,11 @@ split_point_start: // At split points actual search starts from here return value_mated_in(ss->ply); // Update transposition table - ValueType vt = (bestValue <= oldAlpha ? VALUE_TYPE_UPPER : bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT); - TT.store(pos.get_key(), value_to_tt(bestValue, ss->ply), vt, ttDepth, ss->bestMove, ss->eval, evalMargin); + move = bestValue <= oldAlpha ? MOVE_NONE : ss->bestMove; + vt = bestValue <= oldAlpha ? VALUE_TYPE_UPPER + : bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT; + + TT.store(pos.get_key(), value_to_tt(bestValue, ss->ply), vt, ttDepth, move, ss->eval, evalMargin); assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); @@ -1558,8 +1549,8 @@ 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(move_is_ok(m1)); + assert(move_is_ok(m2)); // Case 1: The moving piece is the same in both moves f2 = move_from(m2); @@ -1635,7 +1626,7 @@ 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(move_is_ok(threat)); assert(!pos.move_is_capture_or_promotion(m)); assert(!pos.move_is_passed_pawn_push(m)); @@ -1669,10 +1660,10 @@ split_point_start: // At split points actual search starts from here } - // ok_to_use_TT() returns true if a transposition table score - // can be used 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 ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply) { + bool can_return_tt(const TTEntry* tte, Depth depth, Value beta, int ply) { Value v = value_from_tt(tte->value(), ply); @@ -1961,9 +1952,6 @@ split_point_start: // At split points actual search starts from here dbg_print_mean(); dbg_print_hit_rate(); - - // Send info on searched nodes as soon as we return to root - SendSearchedNodes = true; } // Should we stop the search? @@ -2151,110 +2139,104 @@ split_point_start: // At split points actual search starts from here } // namespace -// ThreadsManager::idle_loop() is where the threads are parked when they have no work -// to do. The parameter 'sp', if non-NULL, is a pointer to an active SplitPoint -// object for which the current thread is the master. +// 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; +} -void ThreadsManager::idle_loop(int threadID, SplitPoint* sp) { - assert(threadID >= 0 && threadID < MAX_THREADS); +// 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. - int i; - bool allFinished; +void Thread::idle_loop(SplitPoint* sp) { while (true) { - // Slave threads can exit as soon as AllThreadsShouldExit raises, - // master should exit as last one. - if (allThreadsShouldExit) - { - assert(!sp); - threads[threadID].state = Thread::TERMINATED; - return; - } - - // If we are not thinking, wait for a condition to be signaled + // If we are not searching, wait for a condition to be signaled // instead of wasting CPU time polling for work. - while ( threadID >= activeThreads - || threads[threadID].state == Thread::INITIALIZING - || (useSleepingThreads && threads[threadID].state == Thread::AVAILABLE)) + while ( do_sleep + || do_terminate + || (Threads.use_sleeping_threads() && !is_searching)) { - assert(!sp || useSleepingThreads); - assert(threadID != 0 || useSleepingThreads); + assert((!sp && threadID) || Threads.use_sleeping_threads()); - if (threads[threadID].state == Thread::INITIALIZING) - threads[threadID].state = Thread::AVAILABLE; + // Slave thread should exit as soon as do_terminate flag raises + if (do_terminate) + { + assert(!sp); + return; + } // Grab the lock to avoid races with Thread::wake_up() - lock_grab(&threads[threadID].sleepLock); + lock_grab(&sleepLock); - // If we are master and all slaves have finished do not go to sleep - for (i = 0; sp && i < activeThreads && !sp->is_slave[i]; i++) {} - allFinished = (i == activeThreads); - - if (allFinished || allThreadsShouldExit) + // If we are master and all slaves have finished don't go to sleep + if (sp && all_slaves_finished(sp)) { - lock_release(&threads[threadID].sleepLock); + lock_release(&sleepLock); break; } - // Do sleep here after retesting sleep conditions - if (threadID >= activeThreads || threads[threadID].state == Thread::AVAILABLE) - cond_wait(&threads[threadID].sleepCond, &threads[threadID].sleepLock); + // Do sleep after retesting sleep conditions under lock protection, in + // particular we need to avoid a deadlock in case a master thread has, + // in the meanwhile, allocated us and sent the wake_up() call before we + // had the chance to grab the lock. + if (do_sleep || !is_searching) + cond_wait(&sleepCond, &sleepLock); - lock_release(&threads[threadID].sleepLock); + lock_release(&sleepLock); } // If this thread has been assigned work, launch a search - if (threads[threadID].state == Thread::WORKISWAITING) + if (is_searching) { - assert(!allThreadsShouldExit); - - threads[threadID].state = Thread::SEARCHING; + assert(!do_terminate); // Copy split point position and search stack and call search() - // with SplitPoint template parameter set to true. SearchStack ss[PLY_MAX_PLUS_2]; - SplitPoint* tsp = threads[threadID].splitPoint; + SplitPoint* tsp = splitPoint; Position pos(*tsp->pos, threadID); memcpy(ss, tsp->ss - 1, 4 * sizeof(SearchStack)); (ss+1)->sp = tsp; - if (tsp->pvNode) + if (tsp->nodeType == Root) + search(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth); + else if (tsp->nodeType == PV) search(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth); - else + else if (tsp->nodeType == NonPV) search(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth); + else + assert(false); - assert(threads[threadID].state == Thread::SEARCHING); + assert(is_searching); - threads[threadID].state = Thread::AVAILABLE; + is_searching = false; // Wake up master thread so to allow it to return from the idle loop in // case we are the last slave of the split point. - if ( useSleepingThreads + if ( Threads.use_sleeping_threads() && threadID != tsp->master - && threads[tsp->master].state == Thread::AVAILABLE) - threads[tsp->master].wake_up(); + && !Threads[tsp->master].is_searching) + Threads[tsp->master].wake_up(); } // 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. - for (i = 0; sp && i < activeThreads && !sp->is_slave[i]; i++) {} - allFinished = (i == activeThreads); - - if (allFinished) + if (sp && all_slaves_finished(sp)) { - // Because sp->slaves[] is reset under lock protection, + // Because sp->is_slave[] is reset under lock protection, // be sure sp->lock has been released before to return. lock_grab(&(sp->lock)); lock_release(&(sp->lock)); - - // In helpful master concept a master can help only a sub-tree, and - // because here is all finished is not possible master is booked. - assert(threads[threadID].state == Thread::AVAILABLE); - - threads[threadID].state = Thread::SEARCHING; return; } }