X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=40561544ab00a872947d6fef00db1364de71dfaf;hp=dcd4a5ed71c9a0da313343415a471205509238a0;hb=19dd0de4ff83e682bafa56d27f302d8f00d3040d;hpb=ce063f59cd0fea215309c719ee56cbf486a5ea80 diff --git a/src/search.cpp b/src/search.cpp index dcd4a5ed..40561544 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) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2008-2013 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 @@ -26,7 +26,6 @@ #include "book.h" #include "evaluate.h" -#include "history.h" #include "movegen.h" #include "movepick.h" #include "notation.h" @@ -87,7 +86,9 @@ namespace { TimeManager TimeMgr; int BestMoveChanges; Value DrawValue[COLOR_NB]; - History H; + History Hist; + Gains Gain; + Refutations Refutation; template Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth); @@ -98,9 +99,9 @@ namespace { void id_loop(Position& pos); Value value_to_tt(Value v, int ply); Value value_from_tt(Value v, int ply); - bool check_is_dangerous(Position& pos, Move move, Value futilityBase, Value beta); - bool allows_move(const Position& pos, Move first, Move second); - bool prevents_move(const Position& pos, Move first, Move second); + bool check_is_dangerous(const Position& pos, Move move, Value futilityBase, Value beta); + bool allows(const Position& pos, Move first, Move second); + bool refutes(const Position& pos, Move first, Move second); string uci_pv(const Position& pos, int depth, Value alpha, Value beta); struct Skill { @@ -145,7 +146,7 @@ void Search::init() { // Init futility move count array for (d = 0; d < 32; d++) - FutilityMoveCounts[d] = int(3.001 + 0.25 * pow(double(d), 2.0)); + FutilityMoveCounts[d] = int(3.001 + 0.3 * pow(double(d), 1.8)); } @@ -182,7 +183,7 @@ void Search::think() { static PolyglotBook book; // Defined static to initialize the PRNG only once RootColor = RootPos.side_to_move(); - TimeMgr.init(Limits, RootPos.startpos_ply_counter(), RootColor); + TimeMgr.init(Limits, RootPos.game_ply(), RootColor); if (RootMoves.empty()) { @@ -227,22 +228,25 @@ void Search::think() { << std::endl; } - Threads.wake_up(); + // Reset the threads, still sleeping: will be wake up at split time + for (size_t i = 0; i < Threads.size(); i++) + Threads[i]->maxPly = 0; + + Threads.sleepWhileIdle = Options["Use Sleeping Threads"]; // Set best timer interval to avoid lagging under time pressure. Timer is // used to check for remaining available thinking time. - if (Limits.use_time_management()) - Threads.set_timer(std::min(100, std::max(TimeMgr.available_time() / 16, - TimerResolution))); - else if (Limits.nodes) - Threads.set_timer(2 * TimerResolution); - else - Threads.set_timer(100); + Threads.timer->msec = + Limits.use_time_management() ? std::min(100, std::max(TimeMgr.available_time() / 16, TimerResolution)) : + Limits.nodes ? 2 * TimerResolution + : 100; + + Threads.timer->notify_one(); // Wake up the recurring timer id_loop(RootPos); // Let's start searching ! - Threads.set_timer(0); // Stop timer - Threads.sleep(); + Threads.timer->msec = 0; // Stop the timer + Threads.sleepWhileIdle = true; // Send idle threads to sleep if (Options["Use Search Log"]) { @@ -261,11 +265,20 @@ void Search::think() { finalize: + // When search is stopped this info is not printed + sync_cout << "info nodes " << RootPos.nodes_searched() + << " time " << Time::now() - SearchTime + 1 << sync_endl; + // When we reach max depth we arrive here even without Signals.stop is raised, - // but if we are pondering or in infinite search, we shouldn't print the best - // move before we are told to do so. + // but if we are pondering or in infinite search, according to UCI protocol, + // we shouldn't print the best move before the GUI sends a "stop" or "ponderhit" + // command. We simply wait here until GUI sends one of those commands (that + // raise Signals.stop). if (!Signals.stop && (Limits.ponder || Limits.infinite)) - RootPos.this_thread()->wait_for_stop_or_ponderhit(); + { + Signals.stopOnPonderhit = true; + RootPos.this_thread()->wait_for(Signals.stop); + } // Best move could be MOVE_NONE when searching on a stalemate position sync_cout << "bestmove " << move_to_uci(RootMoves[0].pv[0], RootPos.is_chess960()) @@ -285,14 +298,15 @@ namespace { Stack ss[MAX_PLY_PLUS_2]; int depth, prevBestMoveChanges; Value bestValue, alpha, beta, delta; - bool bestMoveNeverChanged = true; memset(ss, 0, 4 * sizeof(Stack)); depth = BestMoveChanges = 0; bestValue = delta = -VALUE_INFINITE; ss->currentMove = MOVE_NULL; // Hack to skip update gains TT.new_search(); - H.clear(); + Hist.clear(); + Gain.clear(); + Refutation.clear(); PVSize = Options["MultiPV"]; Skill skill(Options["Skill Level"]); @@ -345,7 +359,7 @@ namespace { // we want to keep the same order for all the moves but the new // PV that goes to the front. Note that in case of MultiPV search // the already searched PV lines are preserved. - sort(RootMoves.begin() + PVIdx, RootMoves.end()); + std::stable_sort(RootMoves.begin() + PVIdx, RootMoves.end()); // Write PV back to transposition table in case the relevant // entries have been overwritten during the search. @@ -390,7 +404,8 @@ namespace { } // Sort the PV lines searched so far and update the GUI - sort(RootMoves.begin(), RootMoves.begin() + PVIdx + 1); + std::stable_sort(RootMoves.begin(), RootMoves.begin() + PVIdx + 1); + if (PVIdx + 1 == PVSize || Time::now() - SearchTime > 3000) sync_cout << uci_pv(pos, depth, alpha, beta) << sync_endl; } @@ -406,10 +421,6 @@ namespace { << std::endl; } - // Filter out startup noise when monitoring best move stability - if (depth > 2 && BestMoveChanges) - bestMoveNeverChanged = false; - // Do we have found a "mate in x"? if ( Limits.mate && bestValue >= VALUE_MATE_IN_MAX_PLY @@ -435,8 +446,9 @@ namespace { if ( depth >= 12 && !stop && PVSize == 1 - && ( (bestMoveNeverChanged && pos.captured_piece_type()) - || Time::now() - SearchTime > (TimeMgr.available_time() * 40) / 100)) + && bestValue > VALUE_MATED_IN_MAX_PLY + && ( RootMoves.size() == 1 + || Time::now() - SearchTime > (TimeMgr.available_time() * 20) / 100)) { Value rBeta = bestValue - 2 * PawnValueMg; (ss+1)->excludedMove = RootMoves[0].pv[0]; @@ -484,33 +496,32 @@ namespace { Move movesSearched[64]; StateInfo st; const TTEntry *tte; - SplitPoint* sp; + SplitPoint* splitPoint; Key posKey; Move ttMove, move, excludedMove, bestMove, threatMove; Depth ext, newDepth; Value bestValue, value, ttValue; Value eval, nullValue, futilityValue; bool inCheck, givesCheck, pvMove, singularExtensionNode; - bool captureOrPromotion, dangerous, doFullDepthSearch, threatExtension; + bool captureOrPromotion, dangerous, doFullDepthSearch; int moveCount, playedMoveCount; // Step 1. Initialize node Thread* thisThread = pos.this_thread(); moveCount = playedMoveCount = 0; - threatExtension = false; inCheck = pos.checkers(); if (SpNode) { - sp = ss->sp; - bestMove = sp->bestMove; - threatMove = sp->threatMove; - bestValue = sp->bestValue; + splitPoint = ss->splitPoint; + bestMove = splitPoint->bestMove; + threatMove = splitPoint->threatMove; + bestValue = splitPoint->bestValue; tte = NULL; ttMove = excludedMove = MOVE_NONE; ttValue = VALUE_NONE; - assert(sp->bestValue > -VALUE_INFINITE && sp->moveCount > 0); + assert(splitPoint->bestValue > -VALUE_INFINITE && splitPoint->moveCount > 0); goto split_point_start; } @@ -518,6 +529,7 @@ namespace { bestValue = -VALUE_INFINITE; ss->currentMove = threatMove = (ss+1)->excludedMove = bestMove = MOVE_NONE; ss->ply = (ss-1)->ply + 1; + ss->futilityMoveCount = 0; (ss+1)->skipNullMove = false; (ss+1)->reduction = DEPTH_ZERO; (ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE; @@ -528,7 +540,7 @@ namespace { if (!RootNode) { // Step 2. Check for aborted search and immediate draw - if (Signals.stop || pos.is_draw() || ss->ply > MAX_PLY) + if (Signals.stop || pos.is_draw() || ss->ply > MAX_PLY) return DrawValue[pos.side_to_move()]; // Step 3. Mate distance pruning. Even if we mate at the next move our score @@ -584,15 +596,9 @@ namespace { else if (tte) { - // Following asserts are valid only in single thread condition because - // TT access is always racy and its contents cannot be trusted. - assert(tte->static_value() != VALUE_NONE || Threads.size() > 1); - assert(ttValue != VALUE_NONE || tte->type() == BOUND_NONE || Threads.size() > 1); - - ss->staticEval = eval = tte->static_value(); - ss->evalMargin = tte->static_value_margin(); - - if (eval == VALUE_NONE || ss->evalMargin == VALUE_NONE) // Due to a race + // Never assume anything on values stored in TT + if ( (ss->staticEval = eval = tte->eval_value()) == VALUE_NONE + ||(ss->evalMargin = tte->eval_margin()) == VALUE_NONE) eval = ss->staticEval = evaluate(pos, ss->evalMargin); // Can ttValue be used as a better position evaluation? @@ -608,11 +614,6 @@ namespace { ss->staticEval, ss->evalMargin); } - // Handling of UCI command 'mate in x moves'. We simply return if after - // 'x' moves we still have not checkmated the opponent. - if (PvNode && !RootNode && !inCheck && Limits.mate && ss->ply > 2 * Limits.mate) - return eval; - // Update gain for the parent non-capture move given the static position // evaluation before and after the move. if ( (move = (ss-1)->currentMove) != MOVE_NULL @@ -622,7 +623,7 @@ namespace { && type_of(move) == NORMAL) { Square to = to_sq(move); - H.update_gain(pos.piece_on(to), to, -(ss-1)->staticEval - ss->staticEval); + Gain.update(pos.piece_on(to), to, -(ss-1)->staticEval - ss->staticEval); } // Step 6. Razoring (is omitted in PV nodes) @@ -649,10 +650,11 @@ namespace { && !ss->skipNullMove && depth < 4 * ONE_PLY && !inCheck - && eval - FutilityMargins[depth][0] >= beta + && eval - futility_margin(depth, (ss-1)->futilityMoveCount) >= beta && abs(beta) < VALUE_MATE_IN_MAX_PLY + && abs(eval) < VALUE_KNOWN_WIN && pos.non_pawn_material(pos.side_to_move())) - return eval - FutilityMargins[depth][0]; + return eval - futility_margin(depth, (ss-1)->futilityMoveCount); // Step 8. Null move search with verification search (is omitted in PV nodes) if ( !PvNode @@ -672,12 +674,12 @@ namespace { if (eval - PawnValueMg > beta) R += ONE_PLY; - pos.do_null_move(st); + pos.do_null_move(st); (ss+1)->skipNullMove = true; nullValue = depth-R < ONE_PLY ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) : - search(pos, ss+1, -beta, -alpha, depth-R); (ss+1)->skipNullMove = false; - pos.do_null_move(st); + pos.undo_null_move(); if (nullValue >= beta) { @@ -685,7 +687,7 @@ namespace { if (nullValue >= VALUE_MATE_IN_MAX_PLY) nullValue = beta; - if (depth < 6 * ONE_PLY) + if (depth < 12 * ONE_PLY) return nullValue; // Do verification search at high depths @@ -701,15 +703,16 @@ namespace { // The null move failed low, which means that we may be faced with // some kind of threat. If the previous move was reduced, check if // the move that refuted the null move was somehow connected to the - // move which was reduced. If a connection is found extend moves that - // defend against threat. + // move which was reduced. If a connection is found, return a fail + // low score (which will cause the reduced move to fail high in the + // parent node, which will trigger a re-search with full depth). threatMove = (ss+1)->currentMove; if ( depth < 5 * ONE_PLY && (ss-1)->reduction && threatMove != MOVE_NONE - && allows_move(pos, (ss-1)->currentMove, threatMove)) - threatExtension = true; + && allows(pos, (ss-1)->currentMove, threatMove)) + return beta - 1; } } @@ -731,7 +734,7 @@ namespace { assert((ss-1)->currentMove != MOVE_NONE); assert((ss-1)->currentMove != MOVE_NULL); - MovePicker mp(pos, ttMove, H, pos.captured_piece_type()); + MovePicker mp(pos, ttMove, Hist, pos.captured_piece_type()); CheckInfo ci(pos); while ((move = mp.next_move()) != MOVE_NONE) @@ -751,7 +754,7 @@ namespace { && ttMove == MOVE_NONE && (PvNode || (!inCheck && ss->staticEval + Value(256) >= beta))) { - Depth d = (PvNode ? depth - 2 * ONE_PLY : depth / 2); + Depth d = depth - 2 * ONE_PLY - (PvNode ? DEPTH_ZERO : depth / 4); ss->skipNullMove = true; search(pos, ss, alpha, beta, d); @@ -763,7 +766,7 @@ namespace { split_point_start: // At split points actual search starts from here - MovePicker mp(pos, ttMove, depth, H, ss, PvNode ? -VALUE_INFINITE : beta); + MovePicker mp(pos, ttMove, depth, Hist, Refutation, ss, PvNode ? -VALUE_INFINITE : beta); CheckInfo ci(pos); value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc singularExtensionNode = !RootNode @@ -795,8 +798,8 @@ split_point_start: // At split points actual search starts from here if (!pos.pl_move_is_legal(move, ci.pinned)) continue; - moveCount = ++sp->moveCount; - sp->mutex.unlock(); + moveCount = ++splitPoint->moveCount; + splitPoint->mutex.unlock(); } else moveCount++; @@ -827,9 +830,6 @@ split_point_start: // At split points actual search starts from here if (PvNode && dangerous) ext = ONE_PLY; - else if (threatExtension && prevents_move(pos, move, threatMove)) - ext = ONE_PLY; - else if (givesCheck && pos.see_sign(move) >= 0) ext = ONE_PLY / 2; @@ -854,7 +854,7 @@ split_point_start: // At split points actual search starts from here ss->excludedMove = MOVE_NONE; if (value < rBeta) - ext = rBeta >= beta ? ONE_PLY + ONE_PLY / 2 : ONE_PLY; + ext = ONE_PLY; } // Update current move (this must be done after singular extension search) @@ -865,17 +865,16 @@ split_point_start: // At split points actual search starts from here && !captureOrPromotion && !inCheck && !dangerous - && move != ttMove - && (bestValue > VALUE_MATED_IN_MAX_PLY || ( bestValue == -VALUE_INFINITE - && alpha > VALUE_MATED_IN_MAX_PLY))) + /* && move != ttMove Already implicit in the next condition */ + && bestValue > VALUE_MATED_IN_MAX_PLY) { // Move count based pruning if ( depth < 16 * ONE_PLY && moveCount >= FutilityMoveCounts[depth] - && (!threatMove || !prevents_move(pos, move, threatMove))) + && (!threatMove || !refutes(pos, move, threatMove))) { if (SpNode) - sp->mutex.lock(); + splitPoint->mutex.lock(); continue; } @@ -885,26 +884,37 @@ split_point_start: // At split points actual search starts from here // but fixing this made program slightly weaker. Depth predictedDepth = newDepth - reduction(depth, moveCount); futilityValue = ss->staticEval + ss->evalMargin + futility_margin(predictedDepth, moveCount) - + H.gain(pos.piece_moved(move), to_sq(move)); + + Gain[pos.piece_moved(move)][to_sq(move)]; if (futilityValue < beta) { - if (SpNode) - sp->mutex.lock(); + bestValue = std::max(bestValue, futilityValue); + if (SpNode) + { + splitPoint->mutex.lock(); + if (bestValue > splitPoint->bestValue) + splitPoint->bestValue = bestValue; + } continue; } // Prune moves with negative SEE at low depths - if ( predictedDepth < 2 * ONE_PLY + if ( predictedDepth < 4 * ONE_PLY && pos.see_sign(move) < 0) { if (SpNode) - sp->mutex.lock(); + splitPoint->mutex.lock(); continue; } + + // We have not pruned the move that will be searched, but remember how + // far in the move list we are to be more aggressive in the child node. + ss->futilityMoveCount = moveCount; } + else + ss->futilityMoveCount = 0; // Check for legality only before to do the move if (!RootNode && !SpNode && !pos.pl_move_is_legal(move, ci.pinned)) @@ -913,7 +923,7 @@ split_point_start: // At split points actual search starts from here continue; } - pvMove = PvNode ? moveCount == 1 : false; + pvMove = PvNode && moveCount == 1; ss->currentMove = move; if (!SpNode && !captureOrPromotion && playedMoveCount < 64) movesSearched[playedMoveCount++] = move; @@ -927,12 +937,14 @@ split_point_start: // At split points actual search starts from here && !pvMove && !captureOrPromotion && !dangerous - && ss->killers[0] != move - && ss->killers[1] != move) + && move != ttMove + && move != ss->killers[0] + && move != ss->killers[1]) { ss->reduction = reduction(depth, moveCount); Depth d = std::max(newDepth - ss->reduction, ONE_PLY); - alpha = SpNode ? sp->alpha : alpha; + if (SpNode) + alpha = splitPoint->alpha; value = -search(pos, ss+1, -(alpha+1), -alpha, d); @@ -945,7 +957,9 @@ split_point_start: // At split points actual search starts from here // Step 16. Full depth search, when LMR is skipped or fails high if (doFullDepthSearch) { - alpha = SpNode ? sp->alpha : alpha; + if (SpNode) + alpha = splitPoint->alpha; + value = newDepth < ONE_PLY ? givesCheck ? -qsearch(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO) : -qsearch(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO) @@ -968,9 +982,9 @@ split_point_start: // At split points actual search starts from here // Step 18. Check for new best move if (SpNode) { - sp->mutex.lock(); - bestValue = sp->bestValue; - alpha = sp->alpha; + splitPoint->mutex.lock(); + bestValue = splitPoint->bestValue; + alpha = splitPoint->alpha; } // Finished searching the move. If Signals.stop is true, the search @@ -1005,24 +1019,21 @@ split_point_start: // At split points actual search starts from here if (value > bestValue) { - bestValue = value; - if (SpNode) sp->bestValue = value; + bestValue = SpNode ? splitPoint->bestValue = value : value; if (value > alpha) { - bestMove = move; - if (SpNode) sp->bestMove = move; + bestMove = SpNode ? splitPoint->bestMove = move : move; - if (PvNode && value < beta) - { - alpha = value; // Update alpha here! Always alpha < beta - if (SpNode) sp->alpha = value; - } + if (PvNode && value < beta) // Update alpha! Always alpha < beta + alpha = SpNode ? splitPoint->alpha = value : value; else { assert(value >= beta); // Fail high - if (SpNode) sp->cutoff = true; + if (SpNode) + splitPoint->cutoff = true; + break; } } @@ -1030,13 +1041,14 @@ split_point_start: // At split points actual search starts from here // Step 19. Check for splitting the search if ( !SpNode - && depth >= Threads.min_split_depth() - && Threads.available_slave_exists(thisThread)) + && depth >= Threads.minimumSplitDepth + && Threads.available_slave(thisThread) + && thisThread->splitPointsSize < MAX_SPLITPOINTS_PER_THREAD) { assert(bestValue < beta); - bestValue = Threads.split(pos, ss, alpha, beta, bestValue, &bestMove, - depth, threatMove, moveCount, mp, NT); + thisThread->split(pos, ss, alpha, beta, &bestValue, &bestMove, + depth, threatMove, moveCount, &mp, NT); if (bestValue >= beta) break; } @@ -1079,13 +1091,15 @@ split_point_start: // At split points actual search starts from here // Increase history value of the cut-off move Value bonus = Value(int(depth) * int(depth)); - H.add(pos.piece_moved(bestMove), to_sq(bestMove), bonus); + Hist.update(pos.piece_moved(bestMove), to_sq(bestMove), bonus); + Square prevSq = to_sq((ss-1)->currentMove); + Refutation.update(pos.piece_on(prevSq), prevSq, bestMove); // Decrease history of all the other played non-capture moves for (int i = 0; i < playedMoveCount - 1; i++) { Move m = movesSearched[i]; - H.add(pos.piece_moved(m), to_sq(m), -bonus); + Hist.update(pos.piece_moved(m), to_sq(m), -bonus); } } } @@ -1120,7 +1134,7 @@ split_point_start: // At split points actual search starts from here Key posKey; Move ttMove, move, bestMove; Value bestValue, value, ttValue, futilityValue, futilityBase, oldAlpha; - bool givesCheck, enoughMaterial, evasionPrunable, fromNull; + bool givesCheck, enoughMaterial, evasionPrunable; Depth ttDepth; // To flag BOUND_EXACT a node with eval above alpha and no available moves @@ -1129,12 +1143,17 @@ split_point_start: // At split points actual search starts from here ss->currentMove = bestMove = MOVE_NONE; ss->ply = (ss-1)->ply + 1; - fromNull = (ss-1)->currentMove == MOVE_NULL; // Check for an instant draw or maximum ply reached - if (pos.is_draw() || ss->ply > MAX_PLY) + if (pos.is_draw() || ss->ply > MAX_PLY) return DrawValue[pos.side_to_move()]; + // Decide whether or not to include checks, this fixes also the type of + // TT entry depth that we are going to use. Note that in qsearch we use + // only two types of depth in TT: DEPTH_QS_CHECKS or DEPTH_QS_NO_CHECKS. + ttDepth = InCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS + : DEPTH_QS_NO_CHECKS; + // Transposition table lookup. At PV nodes, we don't use the TT for // pruning, but only for move ordering. posKey = pos.key(); @@ -1142,11 +1161,6 @@ split_point_start: // At split points actual search starts from here ttMove = tte ? tte->move() : MOVE_NONE; ttValue = tte ? value_from_tt(tte->value(),ss->ply) : VALUE_NONE; - // Decide whether or not to include checks, this fixes also the type of - // TT entry depth that we are going to use. Note that in qsearch we use - // only two types of depth in TT: DEPTH_QS_CHECKS or DEPTH_QS_NO_CHECKS. - ttDepth = InCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS - : DEPTH_QS_NO_CHECKS; if ( tte && tte->depth() >= ttDepth && ttValue != VALUE_NONE // Only in case of TT access race @@ -1167,20 +1181,11 @@ split_point_start: // At split points actual search starts from here } else { - if (fromNull) + if (tte) { - // Approximated score. Real one is slightly higher due to tempo - ss->staticEval = bestValue = -(ss-1)->staticEval; - ss->evalMargin = VALUE_ZERO; - } - else if (tte) - { - assert(tte->static_value() != VALUE_NONE || Threads.size() > 1); - - ss->staticEval = bestValue = tte->static_value(); - ss->evalMargin = tte->static_value_margin(); - - if (ss->staticEval == VALUE_NONE || ss->evalMargin == VALUE_NONE) // Due to a race + // Never assume anything on values stored in TT + if ( (ss->staticEval = bestValue = tte->eval_value()) == VALUE_NONE + ||(ss->evalMargin = tte->eval_margin()) == VALUE_NONE) ss->staticEval = bestValue = evaluate(pos, ss->evalMargin); } else @@ -1207,7 +1212,7 @@ split_point_start: // At split points actual search starts from here // to search the moves. Because the depth is <= 0 here, only captures, // queen promotions and checks (only if depth >= DEPTH_QS_CHECKS) will // be generated. - MovePicker mp(pos, ttMove, depth, H, to_sq((ss-1)->currentMove)); + MovePicker mp(pos, ttMove, depth, Hist, to_sq((ss-1)->currentMove)); CheckInfo ci(pos); // Loop through the moves until no moves remain or a beta cutoff occurs @@ -1220,7 +1225,6 @@ split_point_start: // At split points actual search starts from here // Futility pruning if ( !PvNode && !InCheck - && !fromNull && !givesCheck && move != ttMove && enoughMaterial @@ -1237,10 +1241,11 @@ split_point_start: // At split points actual search starts from here continue; } - // Prune moves with negative or equal SEE + // Prune moves with negative or equal SEE and also moves with positive + // SEE where capturing piece loses a tempo and SEE < beta - futilityBase. if ( futilityBase < beta && depth < DEPTH_ZERO - && pos.see(move) <= 0) + && pos.see(move, beta - futilityBase) <= 0) { bestValue = std::max(bestValue, futilityBase); continue; @@ -1351,7 +1356,7 @@ split_point_start: // At split points actual search starts from here // check_is_dangerous() tests if a checking move can be pruned in qsearch() - bool check_is_dangerous(Position& pos, Move move, Value futilityBase, Value beta) + bool check_is_dangerous(const Position& pos, Move move, Value futilityBase, Value beta) { Piece pc = pos.piece_moved(move); Square from = from_sq(move); @@ -1385,12 +1390,12 @@ split_point_start: // At split points actual search starts from here } - // allows_move() tests whether the move at previous ply (first) somehow makes a - // second move possible, for instance if the moving piece is the same in both - // moves. Normally the second move is the threat move (the best move returned + // allows() tests whether the 'first' move at previous ply somehow makes the + // 'second' move possible, for instance if the moving piece is the same in + // both moves. Normally the second move is the threat (the best move returned // from a null search that fails low). - bool allows_move(const Position& pos, Move first, Move second) { + bool allows(const Position& pos, Move first, Move second) { assert(is_ok(first)); assert(is_ok(second)); @@ -1426,12 +1431,11 @@ split_point_start: // At split points actual search starts from here } - // prevents_move() tests whether a move (first) is able to defend against an - // opponent's move (second). In this case will not be pruned. Normally the - // second move is the threat move (the best move returned from a null search - // that fails low). + // refutes() tests whether a 'first' move is able to defend against a 'second' + // opponent's move. In this case will not be pruned. Normally the second move + // is the threat (the best move returned from a null search that fails low). - bool prevents_move(const Position& pos, Move first, Move second) { + bool refutes(const Position& pos, Move first, Move second) { assert(is_ok(first)); assert(is_ok(second)); @@ -1530,8 +1534,8 @@ split_point_start: // At split points actual search starts from here int selDepth = 0; for (size_t i = 0; i < Threads.size(); i++) - if (Threads[i].maxPly > selDepth) - selDepth = Threads[i].maxPly; + if (Threads[i]->maxPly > selDepth) + selDepth = Threads[i]->maxPly; for (size_t i = 0; i < uciPVSize; i++) { @@ -1591,7 +1595,7 @@ void RootMove::extract_pv_from_tt(Position& pos) { && pos.is_pseudo_legal(m = tte->move()) // Local copy, TT could change && pos.pl_move_is_legal(m, pos.pinned_pieces()) && ply < MAX_PLY - && (!pos.is_draw() || ply < 2)); + && (!pos.is_draw() || ply < 2)); pv.push_back(MOVE_NONE); // Must be zero-terminating @@ -1629,33 +1633,29 @@ void RootMove::insert_pv_in_tt(Position& pos) { void Thread::idle_loop() { - // Pointer 'sp_master', if non-NULL, points to the active SplitPoint - // object for which the thread is the master. - const SplitPoint* sp_master = splitPointsCnt ? curSplitPoint : NULL; + // Pointer 'this_sp' is not null only if we are called from split(), and not + // at the thread creation. So it means we are the split point's master. + SplitPoint* this_sp = splitPointsSize ? activeSplitPoint : NULL; - assert(!sp_master || (sp_master->master == this && is_searching)); + assert(!this_sp || (this_sp->masterThread == this && searching)); - // 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. - while (!sp_master || sp_master->slavesMask) + while (true) { - // If we are not searching, wait for a condition to be signaled - // instead of wasting CPU time polling for work. - while ( do_sleep - || do_exit - || (!is_searching && Threads.use_sleeping_threads())) + // If we are not searching, wait for a condition to be signaled instead of + // wasting CPU time polling for work. + while ((!searching && Threads.sleepWhileIdle) || exit) { - if (do_exit) + if (exit) { - assert(!sp_master); + assert(!this_sp); return; } - // Grab the lock to avoid races with Thread::wake_up() + // Grab the lock to avoid races with Thread::notify_one() mutex.lock(); - // If we are master and all slaves have finished don't go to sleep - if (sp_master && !sp_master->slavesMask) + // If we are master and all slaves have finished then exit idle_loop + if (this_sp && !this_sp->slavesMask) { mutex.unlock(); break; @@ -1663,23 +1663,23 @@ void Thread::idle_loop() { // 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) + // in the meanwhile, allocated us and sent the notify_one() call before + // we had the chance to grab the lock. + if (!searching && !exit) sleepCondition.wait(mutex); mutex.unlock(); } // If this thread has been assigned work, launch a search - if (is_searching) + if (searching) { - assert(!do_sleep && !do_exit); + assert(!exit); Threads.mutex.lock(); - assert(is_searching); - SplitPoint* sp = curSplitPoint; + assert(searching); + SplitPoint* sp = activeSplitPoint; Threads.mutex.unlock(); @@ -1687,38 +1687,43 @@ void Thread::idle_loop() { Position pos(*sp->pos, this); memcpy(ss, sp->ss - 1, 4 * sizeof(Stack)); - (ss+1)->sp = sp; + (ss+1)->splitPoint = sp; sp->mutex.lock(); - assert(sp->activePositions[idx] == NULL); + assert(activePosition == NULL); - sp->activePositions[idx] = &pos; + activePosition = &pos; - if (sp->nodeType == Root) + switch (sp->nodeType) { + case Root: search(pos, ss+1, sp->alpha, sp->beta, sp->depth); - else if (sp->nodeType == PV) + break; + case PV: search(pos, ss+1, sp->alpha, sp->beta, sp->depth); - else if (sp->nodeType == NonPV) + break; + case NonPV: search(pos, ss+1, sp->alpha, sp->beta, sp->depth); - else + break; + default: assert(false); + } - assert(is_searching); + assert(searching); - is_searching = false; - sp->activePositions[idx] = NULL; + searching = false; + activePosition = NULL; sp->slavesMask &= ~(1ULL << idx); sp->nodes += pos.nodes_searched(); - // 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 ( Threads.use_sleeping_threads() - && this != sp->master + // 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 ( Threads.sleepWhileIdle + && this != sp->masterThread && !sp->slavesMask) { - assert(!sp->master->is_searching); - sp->master->wake_up(); + assert(!sp->masterThread->searching); + sp->masterThread->notify_one(); } // After releasing the lock we cannot access anymore any SplitPoint @@ -1727,6 +1732,17 @@ void Thread::idle_loop() { // unsafe because if we are exiting there is a chance are already freed. sp->mutex.unlock(); } + + // 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 (this_sp && !this_sp->slavesMask) + { + this_sp->mutex.lock(); + bool finished = !this_sp->slavesMask; // Retest under lock protection + this_sp->mutex.unlock(); + if (finished) + return; + } } } @@ -1756,11 +1772,11 @@ void check_time() { nodes = RootPos.nodes_searched(); // Loop across all split points and sum accumulated SplitPoint nodes plus - // all the currently active slaves positions. + // all the currently active positions nodes. for (size_t i = 0; i < Threads.size(); i++) - for (int j = 0; j < Threads[i].splitPointsCnt; j++) + for (int j = 0; j < Threads[i]->splitPointsSize; j++) { - SplitPoint& sp = Threads[i].splitPoints[j]; + SplitPoint& sp = Threads[i]->splitPoints[j]; sp.mutex.lock(); @@ -1768,8 +1784,9 @@ void check_time() { Bitboard sm = sp.slavesMask; while (sm) { - Position* pos = sp.activePositions[pop_lsb(&sm)]; - nodes += pos ? pos->nodes_searched() : 0; + Position* pos = Threads[pop_lsb(&sm)]->activePosition; + if (pos) + nodes += pos->nodes_searched(); } sp.mutex.unlock();