X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=fc94f4f79347dfc14dc6fe5e186c90ca3a1d0fac;hp=49d18b5061e7c480c5f888e6c07c7ed89fed2b0a;hb=b88bc7b7667fc6ddbfc7412fb2c0bfc13e3bf11c;hpb=91427c824280d71eaf27f39a4bfdd2188cbdb4ec diff --git a/src/search.cpp b/src/search.cpp index 49d18b50..fc94f4f7 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 @@ -86,11 +86,12 @@ namespace { TimeManager TimeMgr; int BestMoveChanges; Value DrawValue[COLOR_NB]; - History Hist; - Gains Gain; + HistoryStats History; + GainsStats Gains; + CountermovesStats Countermoves; template - Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth); + Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode); template Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth); @@ -98,7 +99,7 @@ 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 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); @@ -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)); } @@ -154,21 +155,17 @@ void Search::init() { size_t Search::perft(Position& pos, Depth depth) { - // At the last ply just return the number of legal moves (leaf nodes) - if (depth == ONE_PLY) - return MoveList(pos).size(); - StateInfo st; size_t cnt = 0; CheckInfo ci(pos); + const bool leaf = depth == 2 * ONE_PLY; - for (MoveList ml(pos); !ml.end(); ++ml) + for (MoveList it(pos); *it; ++it) { - pos.do_move(ml.move(), st, ci, pos.move_gives_check(ml.move(), ci)); - cnt += perft(pos, depth - ONE_PLY); - pos.undo_move(ml.move()); + pos.do_move(*it, st, ci, pos.move_gives_check(*it, ci)); + cnt += leaf ? MoveList(pos).size() : perft(pos, depth - ONE_PLY); + pos.undo_move(*it); } - return cnt; } @@ -182,7 +179,7 @@ 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()) { @@ -229,22 +226,22 @@ void Search::think() { // 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[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. - Threads.timer_thread()->msec = + Threads.timer->msec = Limits.use_time_management() ? std::min(100, std::max(TimeMgr.available_time() / 16, TimerResolution)) : Limits.nodes ? 2 * TimerResolution : 100; - Threads.timer_thread()->notify_one(); // Wake up the recurring timer + Threads.timer->notify_one(); // Wake up the recurring timer id_loop(RootPos); // Let's start searching ! - Threads.timer_thread()->msec = 0; // Stop the timer + Threads.timer->msec = 0; // Stop the timer Threads.sleepWhileIdle = true; // Send idle threads to sleep if (Options["Use Search Log"]) @@ -264,6 +261,10 @@ 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, according to UCI protocol, // we shouldn't print the best move before the GUI sends a "stop" or "ponderhit" @@ -290,18 +291,21 @@ namespace { void id_loop(Position& pos) { - Stack ss[MAX_PLY_PLUS_2]; + Stack stack[MAX_PLY_PLUS_2], *ss = stack+1; // To allow referencing (ss-1) int depth, prevBestMoveChanges; Value bestValue, alpha, beta, delta; - bool bestMoveNeverChanged = true; - memset(ss, 0, 4 * sizeof(Stack)); + memset(ss-1, 0, 4 * sizeof(Stack)); + (ss-1)->currentMove = MOVE_NULL; // Hack to skip update gains + depth = BestMoveChanges = 0; - bestValue = delta = -VALUE_INFINITE; - ss->currentMove = MOVE_NULL; // Hack to skip update gains + bestValue = delta = alpha = -VALUE_INFINITE; + beta = VALUE_INFINITE; + TT.new_search(); - Hist.clear(); - Gain.clear(); + History.clear(); + Gains.clear(); + Countermoves.clear(); PVSize = Options["MultiPV"]; Skill skill(Options["Skill Level"]); @@ -327,26 +331,19 @@ namespace { // MultiPV loop. We perform a full root search for each PV line for (PVIdx = 0; PVIdx < PVSize; PVIdx++) { - // Set aspiration window default width - if (depth >= 5 && abs(RootMoves[PVIdx].prevScore) < VALUE_KNOWN_WIN) + // Reset aspiration window starting size + if (depth >= 5) { delta = Value(16); - alpha = RootMoves[PVIdx].prevScore - delta; - beta = RootMoves[PVIdx].prevScore + delta; - } - else - { - alpha = -VALUE_INFINITE; - beta = VALUE_INFINITE; + alpha = std::max(RootMoves[PVIdx].prevScore - delta,-VALUE_INFINITE); + beta = std::min(RootMoves[PVIdx].prevScore + delta, VALUE_INFINITE); } // Start with a small aspiration window and, in case of fail high/low, // research with bigger window until not failing high/low anymore. while (true) { - // Search starts from ss+1 to allow referencing (ss-1). This is - // needed by update gains and ss copy when splitting at Root. - bestValue = search(pos, ss+1, alpha, beta, depth * ONE_PLY); + bestValue = search(pos, ss, alpha, beta, depth * ONE_PLY, false); // Bring to front the best move. It is critical that sorting is // done with a stable algorithm because all the values but the first @@ -354,7 +351,7 @@ 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. @@ -367,39 +364,32 @@ namespace { if (Signals.stop) return; - // In case of failing high/low increase aspiration window and - // research, otherwise exit the loop. - if (bestValue > alpha && bestValue < beta) - break; - - // Give some update (without cluttering the UI) before to research - if (Time::now() - SearchTime > 3000) - sync_cout << uci_pv(pos, depth, alpha, beta) << sync_endl; + delta += delta / 2; - if (abs(bestValue) >= VALUE_KNOWN_WIN) - { - alpha = -VALUE_INFINITE; - beta = VALUE_INFINITE; - } - else if (bestValue >= beta) - { - beta += delta; - delta += delta / 2; - } - else + // In case of failing low/high increase aspiration window and + // research, otherwise exit the loop. + if (bestValue <= alpha) { + alpha = std::max(bestValue - delta, -VALUE_INFINITE); + Signals.failedLowAtRoot = true; Signals.stopOnPonderhit = false; - - alpha -= delta; - delta += delta / 2; } + else if (bestValue >= beta) + beta = std::min(bestValue + delta, VALUE_INFINITE); + + else + break; assert(alpha >= -VALUE_INFINITE && beta <= VALUE_INFINITE); + + // Give some update (without cluttering the UI) before to research + if (Time::now() - SearchTime > 3000) + sync_cout << uci_pv(pos, depth, alpha, beta) << sync_endl; } // 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; @@ -411,15 +401,15 @@ namespace { if (Options["Use Search Log"]) { + RootMove& rm = RootMoves[0]; + if (skill.best != MOVE_NONE) + rm = *std::find(RootMoves.begin(), RootMoves.end(), skill.best); + Log log(Options["Search Log Filename"]); - log << pretty_pv(pos, depth, bestValue, Time::now() - SearchTime, &RootMoves[0].pv[0]) + log << pretty_pv(pos, depth, rm.score, Time::now() - SearchTime, &rm.pv[0]) << 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 @@ -445,15 +435,16 @@ 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]; - (ss+1)->skipNullMove = true; - Value v = search(pos, ss+1, rBeta - 1, rBeta, (depth - 3) * ONE_PLY); - (ss+1)->skipNullMove = false; - (ss+1)->excludedMove = MOVE_NONE; + ss->excludedMove = RootMoves[0].pv[0]; + ss->skipNullMove = true; + Value v = search(pos, ss, rBeta - 1, rBeta, (depth - 3) * ONE_PLY, true); + ss->skipNullMove = false; + ss->excludedMove = MOVE_NONE; if (v < rBeta) stop = true; @@ -481,7 +472,7 @@ namespace { // here: This is taken care of after we return from the split point. template - Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) { + Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode) { const bool PvNode = (NT == PV || NT == Root || NT == SplitPointPV || NT == SplitPointRoot); const bool SpNode = (NT == SplitPointPV || NT == SplitPointNonPV || NT == SplitPointRoot); @@ -491,10 +482,10 @@ namespace { assert(PvNode || (alpha == beta - 1)); assert(depth > DEPTH_ZERO); - Move movesSearched[64]; + Move quietsSearched[64]; StateInfo st; const TTEntry *tte; - SplitPoint* sp; + SplitPoint* splitPoint; Key posKey; Move ttMove, move, excludedMove, bestMove, threatMove; Depth ext, newDepth; @@ -502,24 +493,24 @@ namespace { Value eval, nullValue, futilityValue; bool inCheck, givesCheck, pvMove, singularExtensionNode; bool captureOrPromotion, dangerous, doFullDepthSearch; - int moveCount, playedMoveCount; + int moveCount, quietCount; // Step 1. Initialize node Thread* thisThread = pos.this_thread(); - moveCount = playedMoveCount = 0; + moveCount = quietCount = 0; 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; } @@ -527,6 +518,7 @@ 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; @@ -537,7 +529,7 @@ 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 @@ -569,9 +561,9 @@ namespace { && tte && tte->depth() >= depth && ttValue != VALUE_NONE // Only in case of TT access race - && ( PvNode ? tte->type() == BOUND_EXACT - : ttValue >= beta ? (tte->type() & BOUND_LOWER) - : (tte->type() & BOUND_UPPER))) + && ( PvNode ? tte->bound() == BOUND_EXACT + : ttValue >= beta ? (tte->bound() & BOUND_LOWER) + : (tte->bound() & BOUND_UPPER))) { TT.refresh(tte); ss->currentMove = ttMove; // Can be MOVE_NONE @@ -594,14 +586,14 @@ namespace { else if (tte) { // Never assume anything on values stored in TT - if ( (ss->staticEval = eval = tte->static_value()) == VALUE_NONE - ||(ss->evalMargin = tte->static_value_margin()) == VALUE_NONE) + 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? if (ttValue != VALUE_NONE) - if ( ((tte->type() & BOUND_LOWER) && ttValue > eval) - || ((tte->type() & BOUND_UPPER) && ttValue < eval)) + if ( ((tte->bound() & BOUND_LOWER) && ttValue > eval) + || ((tte->bound() & BOUND_UPPER) && ttValue < eval)) eval = ttValue; } else @@ -613,14 +605,14 @@ namespace { // Update gain for the parent non-capture move given the static position // evaluation before and after the move. - if ( (move = (ss-1)->currentMove) != MOVE_NULL - && (ss-1)->staticEval != VALUE_NONE + if ( !pos.captured_piece_type() && ss->staticEval != VALUE_NONE - && !pos.captured_piece_type() + && (ss-1)->staticEval != VALUE_NONE + && (move = (ss-1)->currentMove) != MOVE_NULL && type_of(move) == NORMAL) { Square to = to_sq(move); - Gain.update(pos.piece_on(to), to, -(ss-1)->staticEval - ss->staticEval); + Gains.update(pos.piece_on(to), to, -(ss-1)->staticEval - ss->staticEval); } // Step 6. Razoring (is omitted in PV nodes) @@ -647,10 +639,11 @@ 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 @@ -673,7 +666,7 @@ namespace { 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); + : - search(pos, ss+1, -beta, -alpha, depth-R, !cutNode); (ss+1)->skipNullMove = false; pos.undo_null_move(); @@ -683,12 +676,12 @@ 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 ss->skipNullMove = true; - Value v = search(pos, ss, alpha, beta, depth-R); + Value v = search(pos, ss, alpha, beta, depth-R, false); ss->skipNullMove = false; if (v >= beta) @@ -708,7 +701,7 @@ namespace { && (ss-1)->reduction && threatMove != MOVE_NONE && allows(pos, (ss-1)->currentMove, threatMove)) - return beta - 1; + return alpha; } } @@ -720,7 +713,6 @@ namespace { && depth >= 5 * ONE_PLY && !inCheck && !ss->skipNullMove - && excludedMove == MOVE_NONE && abs(beta) < VALUE_MATE_IN_MAX_PLY) { Value rbeta = beta + 200; @@ -730,7 +722,7 @@ namespace { assert((ss-1)->currentMove != MOVE_NONE); assert((ss-1)->currentMove != MOVE_NULL); - MovePicker mp(pos, ttMove, Hist, pos.captured_piece_type()); + MovePicker mp(pos, ttMove, History, pos.captured_piece_type()); CheckInfo ci(pos); while ((move = mp.next_move()) != MOVE_NONE) @@ -738,7 +730,7 @@ namespace { { ss->currentMove = move; pos.do_move(move, st, ci, pos.move_gives_check(move, ci)); - value = -search(pos, ss+1, -rbeta, -rbeta+1, rdepth); + value = -search(pos, ss+1, -rbeta, -rbeta+1, rdepth, !cutNode); pos.undo_move(move); if (value >= rbeta) return value; @@ -750,10 +742,10 @@ 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); + search(pos, ss, alpha, beta, d, true); ss->skipNullMove = false; tte = TT.probe(posKey); @@ -762,7 +754,11 @@ namespace { split_point_start: // At split points actual search starts from here - MovePicker mp(pos, ttMove, depth, Hist, ss, PvNode ? -VALUE_INFINITE : beta); + Square prevMoveSq = to_sq((ss-1)->currentMove); + Move countermoves[] = { Countermoves[pos.piece_on(prevMoveSq)][prevMoveSq].first, + Countermoves[pos.piece_on(prevMoveSq)][prevMoveSq].second }; + + MovePicker mp(pos, ttMove, depth, History, countermoves, ss, PvNode ? -VALUE_INFINITE : beta); CheckInfo ci(pos); value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc singularExtensionNode = !RootNode @@ -770,7 +766,7 @@ split_point_start: // At split points actual search starts from here && depth >= (PvNode ? 6 * ONE_PLY : 8 * ONE_PLY) && ttMove != MOVE_NONE && !excludedMove // Recursive singular search is not allowed - && (tte->type() & BOUND_LOWER) + && (tte->bound() & BOUND_LOWER) && tte->depth() >= depth - 3 * ONE_PLY; // Step 11. Loop through moves @@ -794,8 +790,8 @@ 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++; @@ -845,7 +841,7 @@ split_point_start: // At split points actual search starts from here Value rBeta = ttValue - int(depth); ss->excludedMove = move; ss->skipNullMove = true; - value = search(pos, ss, rBeta - 1, rBeta, depth / 2); + value = search(pos, ss, rBeta - 1, rBeta, depth / 2, cutNode); ss->skipNullMove = false; ss->excludedMove = MOVE_NONE; @@ -861,9 +857,8 @@ 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 @@ -871,7 +866,7 @@ split_point_start: // At split points actual search starts from here && (!threatMove || !refutes(pos, move, threatMove))) { if (SpNode) - sp->mutex.lock(); + splitPoint->mutex.lock(); continue; } @@ -881,26 +876,37 @@ 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) - + Gain[pos.piece_moved(move)][to_sq(move)]; + + Gains[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)) @@ -911,8 +917,8 @@ split_point_start: // At split points actual search starts from here pvMove = PvNode && moveCount == 1; ss->currentMove = move; - if (!SpNode && !captureOrPromotion && playedMoveCount < 64) - movesSearched[playedMoveCount++] = move; + if (!SpNode && !captureOrPromotion && quietCount < 64) + quietsSearched[quietCount++] = move; // Step 14. Make the move pos.do_move(move, st, ci, givesCheck); @@ -928,10 +934,18 @@ split_point_start: // At split points actual search starts from here && move != ss->killers[1]) { ss->reduction = reduction(depth, moveCount); + + if (!PvNode && cutNode) + ss->reduction += ONE_PLY; + + if (move == countermoves[0] || move == countermoves[1]) + ss->reduction = std::max(DEPTH_ZERO, ss->reduction-ONE_PLY); + 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); + value = -search(pos, ss+1, -(alpha+1), -alpha, d, true); doFullDepthSearch = (value > alpha && ss->reduction != DEPTH_ZERO); ss->reduction = DEPTH_ZERO; @@ -942,11 +956,13 @@ 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) - : - search(pos, ss+1, -(alpha+1), -alpha, newDepth); + : - search(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode); } // Only for PV nodes do a full PV search on the first move or after a fail @@ -956,7 +972,7 @@ split_point_start: // At split points actual search starts from here value = newDepth < ONE_PLY ? givesCheck ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) : -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) - : - search(pos, ss+1, -beta, -alpha, newDepth); + : - search(pos, ss+1, -beta, -alpha, newDepth, false); // Step 17. Undo move pos.undo_move(move); @@ -965,9 +981,9 @@ 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 @@ -1002,20 +1018,20 @@ split_point_start: // At split points actual search starts from here if (value > bestValue) { - bestValue = SpNode ? sp->bestValue = value : value; + bestValue = SpNode ? splitPoint->bestValue = value : value; if (value > alpha) { - bestMove = SpNode ? sp->bestMove = move : move; + bestMove = SpNode ? splitPoint->bestMove = move : move; if (PvNode && value < beta) // Update alpha! Always alpha < beta - alpha = SpNode ? sp->alpha = value : value; + alpha = SpNode ? splitPoint->alpha = value : value; else { assert(value >= beta); // Fail high if (SpNode) - sp->cutoff = true; + splitPoint->cutoff = true; break; } @@ -1025,13 +1041,13 @@ split_point_start: // At split points actual search starts from here // Step 19. Check for splitting the search if ( !SpNode && depth >= Threads.minimumSplitDepth - && Threads.slave_available(thisThread) + && Threads.available_slave(thisThread) && thisThread->splitPointsSize < MAX_SPLITPOINTS_PER_THREAD) { assert(bestValue < beta); - bestValue = thisThread->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, cutNode); if (bestValue >= beta) break; } @@ -1053,41 +1069,37 @@ split_point_start: // At split points actual search starts from here // If we have pruned all the moves without searching return a fail-low score if (bestValue == -VALUE_INFINITE) - { - assert(!playedMoveCount); - bestValue = alpha; - } - if (bestValue >= beta) // Failed high + TT.store(posKey, value_to_tt(bestValue, ss->ply), + bestValue >= beta ? BOUND_LOWER : + PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER, + depth, bestMove, ss->staticEval, ss->evalMargin); + + // Quiet best move: update killers, history and countermoves + if ( bestValue >= beta + && !pos.is_capture_or_promotion(bestMove) + && !inCheck) { - TT.store(posKey, value_to_tt(bestValue, ss->ply), BOUND_LOWER, depth, - bestMove, ss->staticEval, ss->evalMargin); - - if (!pos.is_capture_or_promotion(bestMove) && !inCheck) + if (ss->killers[0] != bestMove) { - if (bestMove != ss->killers[0]) - { - ss->killers[1] = ss->killers[0]; - ss->killers[0] = bestMove; - } - - // Increase history value of the cut-off move - Value bonus = Value(int(depth) * int(depth)); - Hist.update(pos.piece_moved(bestMove), to_sq(bestMove), bonus); + ss->killers[1] = ss->killers[0]; + ss->killers[0] = bestMove; + } - // Decrease history of all the other played non-capture moves - for (int i = 0; i < playedMoveCount - 1; i++) - { - Move m = movesSearched[i]; - Hist.update(pos.piece_moved(m), to_sq(m), -bonus); - } + // Increase history value of the cut-off move and decrease all the other + // played non-capture moves. + Value bonus = Value(int(depth) * int(depth)); + History.update(pos.piece_moved(bestMove), to_sq(bestMove), bonus); + for (int i = 0; i < quietCount - 1; i++) + { + Move m = quietsSearched[i]; + History.update(pos.piece_moved(m), to_sq(m), -bonus); } + + if (is_ok((ss-1)->currentMove)) + Countermoves.update(pos.piece_on(prevMoveSq), prevMoveSq, bestMove); } - else // Failed low or PV search - TT.store(posKey, value_to_tt(bestValue, ss->ply), - PvNode && bestMove != MOVE_NONE ? BOUND_EXACT : BOUND_UPPER, - depth, bestMove, ss->staticEval, ss->evalMargin); assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); @@ -1126,27 +1138,27 @@ split_point_start: // At split points actual search starts from here ss->ply = (ss-1)->ply + 1; // 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()]; - // Transposition table lookup. At PV nodes, we don't use the TT for - // pruning, but only for move ordering. - posKey = pos.key(); - tte = TT.probe(posKey); - 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; + + // Transposition table lookup + posKey = pos.key(); + tte = TT.probe(posKey); + ttMove = tte ? tte->move() : MOVE_NONE; + ttValue = tte ? value_from_tt(tte->value(),ss->ply) : VALUE_NONE; + if ( tte && tte->depth() >= ttDepth && ttValue != VALUE_NONE // Only in case of TT access race - && ( PvNode ? tte->type() == BOUND_EXACT - : ttValue >= beta ? (tte->type() & BOUND_LOWER) - : (tte->type() & BOUND_UPPER))) + && ( PvNode ? tte->bound() == BOUND_EXACT + : ttValue >= beta ? (tte->bound() & BOUND_LOWER) + : (tte->bound() & BOUND_UPPER))) { ss->currentMove = ttMove; // Can be MOVE_NONE return ttValue; @@ -1164,8 +1176,8 @@ split_point_start: // At split points actual search starts from here if (tte) { // Never assume anything on values stored in TT - if ( (ss->staticEval = bestValue = tte->static_value()) == VALUE_NONE - ||(ss->evalMargin = tte->static_value_margin()) == VALUE_NONE) + if ( (ss->staticEval = bestValue = tte->eval_value()) == VALUE_NONE + ||(ss->evalMargin = tte->eval_margin()) == VALUE_NONE) ss->staticEval = bestValue = evaluate(pos, ss->evalMargin); } else @@ -1192,7 +1204,7 @@ 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, Hist, to_sq((ss-1)->currentMove)); + MovePicker mp(pos, ttMove, depth, History, to_sq((ss-1)->currentMove)); CheckInfo ci(pos); // Loop through the moves until no moves remain or a beta cutoff occurs @@ -1221,10 +1233,10 @@ 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; @@ -1335,7 +1347,7 @@ 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); @@ -1436,15 +1448,15 @@ split_point_start: // At split points actual search starts from here { // Update occupancy as if the piece and the threat are moving Bitboard occ = pos.pieces() ^ m1from ^ m1to ^ m2from; - Piece piece = pos.piece_on(m1from); + Piece pc = pos.piece_on(m1from); // The moved piece attacks the square 'tto' ? - if (pos.attacks_from(piece, m1to, occ) & m2to) + if (pos.attacks_from(pc, m1to, occ) & m2to) return true; // Scan for possible X-ray attackers behind the moved piece - Bitboard xray = (attacks_bb< ROOK>(m2to, occ) & pos.pieces(color_of(piece), QUEEN, ROOK)) - | (attacks_bb(m2to, occ) & pos.pieces(color_of(piece), QUEEN, BISHOP)); + Bitboard xray = (attacks_bb< ROOK>(m2to, occ) & pos.pieces(color_of(pc), QUEEN, ROOK)) + | (attacks_bb(m2to, occ) & pos.pieces(color_of(pc), QUEEN, BISHOP)); // Verify attackers are triggered by our move and not already existing if (xray && (xray ^ (xray & pos.attacks_from(m2to)))) @@ -1508,13 +1520,13 @@ split_point_start: // At split points actual search starts from here string uci_pv(const Position& pos, int depth, Value alpha, Value beta) { std::stringstream s; - Time::point elaspsed = Time::now() - SearchTime + 1; + Time::point elapsed = Time::now() - SearchTime + 1; size_t uciPVSize = std::min((size_t)Options["MultiPV"], RootMoves.size()); 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++) { @@ -1533,8 +1545,8 @@ split_point_start: // At split points actual search starts from here << " seldepth " << selDepth << " score " << (i == PVIdx ? score_to_uci(v, alpha, beta) : score_to_uci(v)) << " nodes " << pos.nodes_searched() - << " nps " << pos.nodes_searched() * 1000 / elaspsed - << " time " << elaspsed + << " nps " << pos.nodes_searched() * 1000 / elapsed + << " time " << elapsed << " multipv " << i + 1 << " pv"; @@ -1556,7 +1568,7 @@ split_point_start: // At split points actual search starts from here void RootMove::extract_pv_from_tt(Position& pos) { StateInfo state[MAX_PLY_PLUS_2], *st = state; - TTEntry* tte; + const TTEntry* tte; int ply = 0; Move m = pv[0]; @@ -1574,7 +1586,7 @@ 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 @@ -1589,7 +1601,7 @@ void RootMove::extract_pv_from_tt(Position& pos) { void RootMove::insert_pv_in_tt(Position& pos) { StateInfo state[MAX_PLY_PLUS_2], *st = state; - TTEntry* tte; + const TTEntry* tte; int ply = 0; do { @@ -1614,13 +1626,11 @@ void Thread::idle_loop() { // 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. - const SplitPoint* this_sp = splitPointsSize ? activeSplitPoint : NULL; + SplitPoint* this_sp = splitPointsSize ? activeSplitPoint : NULL; 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 (!this_sp || this_sp->slavesMask) + while (true) { // If we are not searching, wait for a condition to be signaled instead of // wasting CPU time polling for work. @@ -1664,27 +1674,27 @@ void Thread::idle_loop() { Threads.mutex.unlock(); - Stack ss[MAX_PLY_PLUS_2]; + Stack stack[MAX_PLY_PLUS_2], *ss = stack+1; // To allow referencing (ss-1) Position pos(*sp->pos, this); - memcpy(ss, sp->ss - 1, 4 * sizeof(Stack)); - (ss+1)->sp = sp; + memcpy(ss-1, sp->ss-1, 4 * sizeof(Stack)); + ss->splitPoint = sp; sp->mutex.lock(); - assert(sp->slavesPositions[idx] == NULL); + assert(activePosition == NULL); - sp->slavesPositions[idx] = &pos; + activePosition = &pos; switch (sp->nodeType) { case Root: - search(pos, ss+1, sp->alpha, sp->beta, sp->depth); + search(pos, ss, sp->alpha, sp->beta, sp->depth, sp->cutNode); break; case PV: - search(pos, ss+1, sp->alpha, sp->beta, sp->depth); + search(pos, ss, sp->alpha, sp->beta, sp->depth, sp->cutNode); break; case NonPV: - search(pos, ss+1, sp->alpha, sp->beta, sp->depth); + search(pos, ss, sp->alpha, sp->beta, sp->depth, sp->cutNode); break; default: assert(false); @@ -1693,7 +1703,7 @@ void Thread::idle_loop() { assert(searching); searching = false; - sp->slavesPositions[idx] = NULL; + activePosition = NULL; sp->slavesMask &= ~(1ULL << idx); sp->nodes += pos.nodes_searched(); @@ -1713,6 +1723,17 @@ 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; + } } } @@ -1742,11 +1763,11 @@ 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].splitPointsSize; 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(); @@ -1754,8 +1775,9 @@ void check_time() { Bitboard sm = sp.slavesMask; while (sm) { - Position* pos = sp.slavesPositions[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();