X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=b465a5b12f7a35125d12251d0c2441fb8509f514;hp=1d81fd045d447312ad85302a4addacca087e4707;hb=343544f3f7fe780a4231b78646ab2fd61760e294;hpb=bc02cc0c8afdc9c7f6588c28a3ad859a5fc3e5a5 diff --git a/src/search.cpp b/src/search.cpp index 1d81fd04..b465a5b1 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -19,6 +19,7 @@ #include #include +#include #include #include #include @@ -55,9 +56,6 @@ namespace { // Set to true to force running with one thread. Used for debugging const bool FakeSplit = false; - // This is the minimum interval in msec between two check_time() calls - const int TimerResolution = 5; - // Different node types, used as template parameter enum NodeType { Root, PV, NonPV, SplitPointRoot, SplitPointPV, SplitPointNonPV }; @@ -66,7 +64,7 @@ namespace { // Futility lookup tables (initialized at startup) and their access functions Value FutilityMargins[16][64]; // [depth][moveNumber] - int FutilityMoveCounts[32]; // [depth] + int FutilityMoveCounts[2][32]; // [improving][depth] inline Value futility_margin(Depth d, int mn) { @@ -75,23 +73,23 @@ namespace { } // Reduction lookup tables (initialized at startup) and their access function - int8_t Reductions[2][64][64]; // [pv][depth][moveNumber] + int8_t Reductions[2][2][64][64]; // [pv][improving][depth][moveNumber] - template inline Depth reduction(Depth d, int mn) { + template inline Depth reduction(bool i, Depth d, int mn) { - return (Depth) Reductions[PvNode][std::min(int(d) / ONE_PLY, 63)][std::min(mn, 63)]; + return (Depth) Reductions[PvNode][i][std::min(int(d) / ONE_PLY, 63)][std::min(mn, 63)]; } size_t PVSize, PVIdx; TimeManager TimeMgr; - int BestMoveChanges; + double BestMoveChanges; Value DrawValue[COLOR_NB]; 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); @@ -99,7 +97,6 @@ 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(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); @@ -132,47 +129,58 @@ void Search::init() { int mc; // moveCount // Init reductions array - for (hd = 1; hd < 64; hd++) for (mc = 1; mc < 64; mc++) + for (hd = 1; hd < 64; ++hd) for (mc = 1; mc < 64; ++mc) { double pvRed = log(double(hd)) * log(double(mc)) / 3.0; double nonPVRed = 0.33 + log(double(hd)) * log(double(mc)) / 2.25; - Reductions[1][hd][mc] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(ONE_PLY)) : 0); - Reductions[0][hd][mc] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(ONE_PLY)) : 0); + Reductions[1][1][hd][mc] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(ONE_PLY)) : 0); + Reductions[0][1][hd][mc] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(ONE_PLY)) : 0); + + Reductions[1][0][hd][mc] = Reductions[1][1][hd][mc]; + Reductions[0][0][hd][mc] = Reductions[0][1][hd][mc]; + + if (Reductions[0][0][hd][mc] > 2 * ONE_PLY) + Reductions[0][0][hd][mc] += ONE_PLY; + + else if (Reductions[0][0][hd][mc] > 1 * ONE_PLY) + Reductions[0][0][hd][mc] += ONE_PLY / 2; } // Init futility margins array - for (d = 1; d < 16; d++) for (mc = 0; mc < 64; mc++) - FutilityMargins[d][mc] = Value(112 * int(log(double(d * d) / 2) / log(2.0) + 1.001) - 8 * mc + 45); + for (d = 1; d < 16; ++d) for (mc = 0; mc < 64; ++mc) + FutilityMargins[d][mc] = Value(112 * int(2.9 * log(double(d))) - 8 * mc + 45); // Init futility move count array - for (d = 0; d < 32; d++) - FutilityMoveCounts[d] = int(3.001 + 0.3 * pow(double(d), 1.8)); + for (d = 0; d < 32; ++d) + { + FutilityMoveCounts[0][d] = int(2.4 + 0.222 * pow(d + 0.0, 1.8)); + FutilityMoveCounts[1][d] = int(3.0 + 0.3 * pow(d + 0.98, 1.8)); + } } /// Search::perft() is our utility to verify move generation. All the leaf nodes /// up to the given depth are generated and counted and the sum returned. -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(); +static size_t perft(Position& pos, Depth depth) { StateInfo st; size_t cnt = 0; CheckInfo ci(pos); + const bool leaf = depth == 2 * ONE_PLY; for (MoveList it(pos); *it; ++it) { - pos.do_move(*it, st, ci, pos.move_gives_check(*it, ci)); - cnt += perft(pos, depth - ONE_PLY); + pos.do_move(*it, st, ci, pos.gives_check(*it, ci)); + cnt += leaf ? MoveList(pos).size() : ::perft(pos, depth - ONE_PLY); pos.undo_move(*it); } - return cnt; } +size_t Search::perft(Position& pos, Depth depth) { + return depth > ONE_PLY ? ::perft(pos, depth) : MoveList(pos).size(); +} /// Search::think() is the external interface to Stockfish's search, and is /// called by the main thread when the program receives the UCI 'go' command. It @@ -216,7 +224,7 @@ void Search::think() { else DrawValue[WHITE] = DrawValue[BLACK] = VALUE_DRAW; - if (Options["Use Search Log"]) + if (Options["Write Search Log"]) { Log log(Options["Search Log Filename"]); log << "\nSearching: " << RootPos.fen() @@ -229,26 +237,19 @@ void Search::think() { } // Reset the threads, still sleeping: will be wake up at split time - for (size_t i = 0; i < Threads.size(); i++) + 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. - Threads.timer->msec = - Limits.use_time_management() ? std::min(100, std::max(TimeMgr.available_time() / 16, TimerResolution)) : - Limits.nodes ? 2 * TimerResolution - : 100; - + Threads.sleepWhileIdle = Options["Idle Threads Sleep"]; + Threads.timer->run = true; Threads.timer->notify_one(); // Wake up the recurring timer id_loop(RootPos); // Let's start searching ! - Threads.timer->msec = 0; // Stop the timer + Threads.timer->run = false; // Stop the timer Threads.sleepWhileIdle = true; // Send idle threads to sleep - if (Options["Use Search Log"]) + if (Options["Write Search Log"]) { Time::point elapsed = Time::now() - SearchTime + 1; @@ -295,14 +296,18 @@ namespace { void id_loop(Position& pos) { - Stack ss[MAX_PLY_PLUS_2]; - int depth, prevBestMoveChanges; + Stack stack[MAX_PLY_PLUS_6], *ss = stack+2; // To allow referencing (ss-2) + int depth; Value bestValue, alpha, beta, delta; - memset(ss, 0, 4 * sizeof(Stack)); - depth = BestMoveChanges = 0; - bestValue = delta = -VALUE_INFINITE; - ss->currentMove = MOVE_NULL; // Hack to skip update gains + std::memset(ss-2, 0, 5 * sizeof(Stack)); + (ss-1)->currentMove = MOVE_NULL; // Hack to skip update gains + + depth = 0; + BestMoveChanges = 0; + bestValue = delta = alpha = -VALUE_INFINITE; + beta = VALUE_INFINITE; + TT.new_search(); History.clear(); Gains.clear(); @@ -321,37 +326,30 @@ namespace { // Iterative deepening loop until requested to stop or target depth reached while (++depth <= MAX_PLY && !Signals.stop && (!Limits.depth || depth <= Limits.depth)) { + // Age out PV variability metric + BestMoveChanges *= 0.8; + // Save last iteration's scores before first PV line is searched and all // the move scores but the (new) PV are set to -VALUE_INFINITE. - for (size_t i = 0; i < RootMoves.size(); i++) + for (size_t i = 0; i < RootMoves.size(); ++i) RootMoves[i].prevScore = RootMoves[i].score; - prevBestMoveChanges = BestMoveChanges; // Only sensible when PVSize == 1 - BestMoveChanges = 0; - // MultiPV loop. We perform a full root search for each PV line - for (PVIdx = 0; PVIdx < PVSize; PVIdx++) + 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 @@ -363,7 +361,7 @@ namespace { // Write PV back to transposition table in case the relevant // entries have been overwritten during the search. - for (size_t i = 0; i <= PVIdx; i++) + for (size_t i = 0; i <= PVIdx; ++i) RootMoves[i].insert_pv_in_tt(pos); // If search has been stopped return immediately. Sorting and @@ -372,33 +370,28 @@ 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) + // When failing high/low give some update (without cluttering + // the UI) before to research. + if ( (bestValue <= alpha || bestValue >= beta) + && Time::now() - SearchTime > 3000) sync_cout << uci_pv(pos, depth, alpha, beta) << sync_endl; - if (abs(bestValue) >= VALUE_KNOWN_WIN) + // In case of failing low/high increase aspiration window and + // research, otherwise exit the loop. + if (bestValue <= alpha) { - alpha = -VALUE_INFINITE; - beta = VALUE_INFINITE; + alpha = std::max(bestValue - delta, -VALUE_INFINITE); + + Signals.failedLowAtRoot = true; + Signals.stopOnPonderhit = false; } else if (bestValue >= beta) - { - beta += delta; - delta += delta / 2; - } + beta = std::min(bestValue + delta, VALUE_INFINITE); + else - { - Signals.failedLowAtRoot = true; - Signals.stopOnPonderhit = false; + break; - alpha -= delta; - delta += delta / 2; - } + delta += delta / 2; assert(alpha >= -VALUE_INFINITE && beta <= VALUE_INFINITE); } @@ -414,14 +407,14 @@ namespace { if (skill.enabled() && skill.time_to_pick(depth)) skill.pick_move(); - if (Options["Use Search Log"]) + if (Options["Write 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, rm.score, Time::now() - SearchTime, rm.pv.data()) + log << pretty_pv(pos, depth, rm.score, Time::now() - SearchTime, &rm.pv[0]) << std::endl; } @@ -438,7 +431,7 @@ namespace { // Take in account some extra time if the best move has changed if (depth > 4 && depth < 50 && PVSize == 1) - TimeMgr.pv_instability(BestMoveChanges, prevBestMoveChanges); + TimeMgr.pv_instability(BestMoveChanges); // Stop search if most of available time is already consumed. We // probably don't have enough time to search the first move at the @@ -448,6 +441,7 @@ namespace { // Stop search early if one move seems to be much better than others if ( depth >= 12 + && BestMoveChanges <= DBL_EPSILON && !stop && PVSize == 1 && bestValue > VALUE_MATED_IN_MAX_PLY @@ -455,11 +449,11 @@ namespace { || 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; @@ -487,7 +481,7 @@ 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); @@ -497,7 +491,7 @@ namespace { assert(PvNode || (alpha == beta - 1)); assert(depth > DEPTH_ZERO); - Move movesSearched[64]; + Move quietsSearched[64]; StateInfo st; const TTEntry *tte; SplitPoint* splitPoint; @@ -506,13 +500,12 @@ namespace { Depth ext, newDepth; Value bestValue, value, ttValue; Value eval, nullValue, futilityValue; - bool inCheck, givesCheck, pvMove, singularExtensionNode; + bool inCheck, givesCheck, pvMove, singularExtensionNode, improving; bool captureOrPromotion, dangerous, doFullDepthSearch; - int moveCount, playedMoveCount; + int moveCount, quietCount; // Step 1. Initialize node Thread* thisThread = pos.this_thread(); - moveCount = playedMoveCount = 0; inCheck = pos.checkers(); if (SpNode) @@ -527,9 +520,10 @@ namespace { assert(splitPoint->bestValue > -VALUE_INFINITE && splitPoint->moveCount > 0); - goto split_point_start; + goto moves_loop; } + moveCount = quietCount = 0; bestValue = -VALUE_INFINITE; ss->currentMove = threatMove = (ss+1)->excludedMove = bestMove = MOVE_NONE; ss->ply = (ss-1)->ply + 1; @@ -576,16 +570,16 @@ 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 if ( ttValue >= beta && ttMove - && !pos.is_capture_or_promotion(ttMove) + && !pos.capture_or_promotion(ttMove) && ttMove != ss->killers[0]) { ss->killers[1] = ss->killers[0]; @@ -596,7 +590,10 @@ namespace { // Step 5. Evaluate the position statically and update parent's gain statistics if (inCheck) + { ss->staticEval = ss->evalMargin = eval = VALUE_NONE; + goto moves_loop; + } else if (tte) { @@ -607,8 +604,7 @@ namespace { // 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() & (ttValue > eval ? BOUND_LOWER : BOUND_UPPER)) eval = ttValue; } else @@ -620,20 +616,19 @@ 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); Gains.update(pos.piece_on(to), to, -(ss-1)->staticEval - ss->staticEval); } - // Step 6. Razoring (is omitted in PV nodes) + // Step 6. Razoring (skipped when in check) if ( !PvNode && depth < 4 * ONE_PLY - && !inCheck && eval + razor_margin(depth) < beta && ttMove == MOVE_NONE && abs(beta) < VALUE_MATE_IN_MAX_PLY @@ -647,13 +642,12 @@ namespace { return v; } - // Step 7. Static null move pruning (is omitted in PV nodes) + // Step 7. Static null move pruning (skipped when in check) // We're betting that the opponent doesn't have a move that will reduce // the score by more than futility_margin(depth) if we do a null move. if ( !PvNode && !ss->skipNullMove && depth < 4 * ONE_PLY - && !inCheck && eval - futility_margin(depth, (ss-1)->futilityMoveCount) >= beta && abs(beta) < VALUE_MATE_IN_MAX_PLY && abs(eval) < VALUE_KNOWN_WIN @@ -663,8 +657,7 @@ namespace { // Step 8. Null move search with verification search (is omitted in PV nodes) if ( !PvNode && !ss->skipNullMove - && depth > ONE_PLY - && !inCheck + && depth >= 2 * ONE_PLY && eval >= beta && abs(beta) < VALUE_MATE_IN_MAX_PLY && pos.non_pawn_material(pos.side_to_move())) @@ -681,7 +674,7 @@ 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(); @@ -696,7 +689,7 @@ namespace { // 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) @@ -716,19 +709,17 @@ namespace { && (ss-1)->reduction && threatMove != MOVE_NONE && allows(pos, (ss-1)->currentMove, threatMove)) - return beta - 1; + return alpha; } } - // Step 9. ProbCut (is omitted in PV nodes) + // Step 9. ProbCut (skipped when in check) // If we have a very good capture (i.e. SEE > seeValues[captured_piece_type]) // and a reduced search returns a value much above beta, we can (almost) safely // prune the previous move. if ( !PvNode && depth >= 5 * ONE_PLY - && !inCheck && !ss->skipNullMove - && excludedMove == MOVE_NONE && abs(beta) < VALUE_MATE_IN_MAX_PLY) { Value rbeta = beta + 200; @@ -742,47 +733,51 @@ namespace { CheckInfo ci(pos); while ((move = mp.next_move()) != MOVE_NONE) - if (pos.pl_move_is_legal(move, ci.pinned)) + if (pos.legal(move, ci.pinned)) { ss->currentMove = move; - pos.do_move(move, st, ci, pos.move_gives_check(move, ci)); - value = -search(pos, ss+1, -rbeta, -rbeta+1, rdepth); + pos.do_move(move, st, ci, pos.gives_check(move, ci)); + value = -search(pos, ss+1, -rbeta, -rbeta+1, rdepth, !cutNode); pos.undo_move(move); if (value >= rbeta) return value; } } - // Step 10. Internal iterative deepening + // Step 10. Internal iterative deepening (skipped when in check) if ( depth >= (PvNode ? 5 * ONE_PLY : 8 * ONE_PLY) && ttMove == MOVE_NONE - && (PvNode || (!inCheck && ss->staticEval + Value(256) >= beta))) + && (PvNode || ss->staticEval + Value(256) >= beta)) { 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); ttMove = tte ? tte->move() : MOVE_NONE; } -split_point_start: // At split points actual search starts from here +moves_loop: // When in check and at SpNode search starts from here 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); + MovePicker mp(pos, ttMove, depth, History, countermoves, ss); CheckInfo ci(pos); value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc + improving = ss->staticEval >= (ss-2)->staticEval + || ss->staticEval == VALUE_NONE + ||(ss-2)->staticEval == VALUE_NONE; + singularExtensionNode = !RootNode && !SpNode - && depth >= (PvNode ? 6 * ONE_PLY : 8 * ONE_PLY) + && depth >= 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 @@ -803,43 +798,35 @@ split_point_start: // At split points actual search starts from here if (SpNode) { // Shared counter cannot be decremented later if move turns out to be illegal - if (!pos.pl_move_is_legal(move, ci.pinned)) + if (!pos.legal(move, ci.pinned)) continue; moveCount = ++splitPoint->moveCount; splitPoint->mutex.unlock(); } else - moveCount++; + ++moveCount; if (RootNode) { Signals.firstRootMove = (moveCount == 1); - if (thisThread == Threads.main_thread() && Time::now() - SearchTime > 3000) + if (thisThread == Threads.main() && Time::now() - SearchTime > 3000) sync_cout << "info depth " << depth / ONE_PLY << " currmove " << move_to_uci(move, pos.is_chess960()) << " currmovenumber " << moveCount + PVIdx << sync_endl; } ext = DEPTH_ZERO; - captureOrPromotion = pos.is_capture_or_promotion(move); - givesCheck = pos.move_gives_check(move, ci); + captureOrPromotion = pos.capture_or_promotion(move); + givesCheck = pos.gives_check(move, ci); dangerous = givesCheck - || pos.is_passed_pawn_push(move) - || type_of(move) == CASTLE - || ( captureOrPromotion // Entering a pawn endgame? - && type_of(pos.piece_on(to_sq(move))) != PAWN - && type_of(move) == NORMAL - && ( pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) - - PieceValue[MG][pos.piece_on(to_sq(move))] == VALUE_ZERO)); - - // Step 12. Extend checks and, in PV nodes, also dangerous moves - if (PvNode && dangerous) - ext = ONE_PLY; + || pos.passed_pawn_push(move) + || type_of(move) == CASTLE; - else if (givesCheck && pos.see_sign(move) >= 0) - ext = ONE_PLY / 2; + // Step 12. Extend checks + if (givesCheck && pos.see_sign(move) >= 0) + ext = ONE_PLY; // Singular extension search. If all moves but one fail low on a search of // (alpha-s, beta-s), and just one fails high on (alpha, beta), then that move @@ -849,7 +836,7 @@ split_point_start: // At split points actual search starts from here if ( singularExtensionNode && move == ttMove && !ext - && pos.pl_move_is_legal(move, ci.pinned) + && pos.legal(move, ci.pinned) && abs(ttValue) < VALUE_KNOWN_WIN) { assert(ttValue != VALUE_NONE); @@ -857,7 +844,7 @@ 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; @@ -878,7 +865,7 @@ split_point_start: // At split points actual search starts from here { // Move count based pruning if ( depth < 16 * ONE_PLY - && moveCount >= FutilityMoveCounts[depth] + && moveCount >= FutilityMoveCounts[improving][depth] && (!threatMove || !refutes(pos, move, threatMove))) { if (SpNode) @@ -890,9 +877,9 @@ split_point_start: // At split points actual search starts from here // Value based pruning // 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); + Depth predictedDepth = newDepth - reduction(improving, depth, moveCount); futilityValue = ss->staticEval + ss->evalMargin + futility_margin(predictedDepth, moveCount) - + Gains[pos.piece_moved(move)][to_sq(move)]; + + Gains[pos.moved_piece(move)][to_sq(move)]; if (futilityValue < beta) { @@ -925,39 +912,45 @@ split_point_start: // At split points actual search starts from here ss->futilityMoveCount = 0; // Check for legality only before to do the move - if (!RootNode && !SpNode && !pos.pl_move_is_legal(move, ci.pinned)) + if (!RootNode && !SpNode && !pos.legal(move, ci.pinned)) { - moveCount--; + --moveCount; continue; } 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); // Step 15. Reduced depth search (LMR). If the move fails high will be // re-searched at full depth. - if ( depth > 3 * ONE_PLY + if ( depth >= 3 * ONE_PLY && !pvMove && !captureOrPromotion - && !dangerous && move != ttMove && move != ss->killers[0] && move != ss->killers[1]) { - ss->reduction = reduction(depth, moveCount); + ss->reduction = reduction(improving, depth, moveCount); + + if (!PvNode && cutNode) + ss->reduction += ONE_PLY; + + else if (History[pos.piece_on(to_sq(move))][to_sq(move)] < 0) + ss->reduction += ONE_PLY / 2; + if (move == countermoves[0] || move == countermoves[1]) - ss->reduction = std::max(DEPTH_ZERO, ss->reduction-ONE_PLY); + ss->reduction = std::max(DEPTH_ZERO, ss->reduction - ONE_PLY); Depth d = std::max(newDepth - ss->reduction, ONE_PLY); 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; @@ -974,7 +967,7 @@ split_point_start: // At split points actual search starts from here 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 @@ -984,7 +977,7 @@ 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); @@ -1019,7 +1012,7 @@ split_point_start: // At split points actual search starts from here // iteration. This information is used for time management: When // the best move changes frequently, we allocate some more time. if (!pvMove) - BestMoveChanges++; + ++BestMoveChanges; } else // All other moves but the PV are set to the lowest value, this @@ -1059,7 +1052,7 @@ split_point_start: // At split points actual search starts from here assert(bestValue < beta); thisThread->split(pos, ss, alpha, beta, &bestValue, &bestMove, - depth, threatMove, moveCount, &mp, NT); + depth, threatMove, moveCount, &mp, NT, cutNode); if (bestValue >= beta) break; } @@ -1081,43 +1074,37 @@ 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.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)); - History.update(pos.piece_moved(bestMove), to_sq(bestMove), bonus); - if (is_ok((ss-1)->currentMove)) - Countermoves.update(pos.piece_on(prevMoveSq), prevMoveSq, bestMove); + 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]; - History.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.moved_piece(bestMove), to_sq(bestMove), bonus); + for (int i = 0; i < quietCount - 1; ++i) + { + Move m = quietsSearched[i]; + History.update(pos.moved_piece(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); @@ -1145,7 +1132,7 @@ 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; + bool givesCheck, evasionPrunable; Depth ttDepth; // To flag BOUND_EXACT a node with eval above alpha and no available moves @@ -1165,8 +1152,7 @@ split_point_start: // At split points actual search starts from here 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. + // Transposition table lookup posKey = pos.key(); tte = TT.probe(posKey); ttMove = tte ? tte->move() : MOVE_NONE; @@ -1175,9 +1161,9 @@ split_point_start: // At split points actual search starts from here 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; @@ -1188,7 +1174,6 @@ split_point_start: // At split points actual search starts from here { ss->staticEval = ss->evalMargin = VALUE_NONE; bestValue = futilityBase = -VALUE_INFINITE; - enoughMaterial = false; } else { @@ -1198,6 +1183,11 @@ split_point_start: // At split points actual search starts from here if ( (ss->staticEval = bestValue = tte->eval_value()) == VALUE_NONE ||(ss->evalMargin = tte->eval_margin()) == VALUE_NONE) ss->staticEval = bestValue = evaluate(pos, ss->evalMargin); + + // Can ttValue be used as a better position evaluation? + if (ttValue != VALUE_NONE) + if (tte->bound() & (ttValue > bestValue ? BOUND_LOWER : BOUND_UPPER)) + bestValue = ttValue; } else ss->staticEval = bestValue = evaluate(pos, ss->evalMargin); @@ -1215,8 +1205,7 @@ split_point_start: // At split points actual search starts from here if (PvNode && bestValue > alpha) alpha = bestValue; - futilityBase = ss->staticEval + ss->evalMargin + Value(128); - enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMg; + futilityBase = bestValue + ss->evalMargin + Value(128); } // Initialize a MovePicker object for the current position, and prepare @@ -1231,16 +1220,16 @@ split_point_start: // At split points actual search starts from here { assert(is_ok(move)); - givesCheck = pos.move_gives_check(move, ci); + givesCheck = pos.gives_check(move, ci); // Futility pruning if ( !PvNode && !InCheck && !givesCheck && move != ttMove - && enoughMaterial && type_of(move) != PROMOTION - && !pos.is_passed_pawn_push(move)) + && futilityBase > -VALUE_KNOWN_WIN + && !pos.passed_pawn_push(move)) { futilityValue = futilityBase + PieceValue[EG][pos.piece_on(to_sq(move))] @@ -1263,10 +1252,9 @@ split_point_start: // At split points actual search starts from here } // Detect non-capture evasions that are candidate to be pruned - evasionPrunable = !PvNode - && InCheck + evasionPrunable = InCheck && bestValue > VALUE_MATED_IN_MAX_PLY - && !pos.is_capture(move) + && !pos.capture(move) && !pos.can_castle(pos.side_to_move()); // Don't search moves with negative SEE values @@ -1277,18 +1265,8 @@ split_point_start: // At split points actual search starts from here && pos.see_sign(move) < 0) continue; - // Don't search useless checks - if ( !PvNode - && !InCheck - && givesCheck - && move != ttMove - && !pos.is_capture_or_promotion(move) - && ss->staticEval + PawnValueMg / 4 < beta - && !check_is_dangerous(pos, move, futilityBase, beta)) - continue; - // Check for legality only before to do the move - if (!pos.pl_move_is_legal(move, ci.pinned)) + if (!pos.legal(move, ci.pinned)) continue; ss->currentMove = move; @@ -1364,42 +1342,6 @@ 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(const Position& pos, Move move, Value futilityBase, Value beta) - { - Piece pc = pos.piece_moved(move); - Square from = from_sq(move); - Square to = to_sq(move); - Color them = ~pos.side_to_move(); - Square ksq = pos.king_square(them); - Bitboard enemies = pos.pieces(them); - Bitboard kingAtt = pos.attacks_from(ksq); - Bitboard occ = pos.pieces() ^ from ^ ksq; - Bitboard oldAtt = pos.attacks_from(pc, from, occ); - Bitboard newAtt = pos.attacks_from(pc, to, occ); - - // Checks which give opponent's king at most one escape square are dangerous - if (!more_than_one(kingAtt & ~(enemies | newAtt | to))) - return true; - - // Queen contact check is very dangerous - if (type_of(pc) == QUEEN && (kingAtt & to)) - return true; - - // Creating new double threats with checks is dangerous - Bitboard b = (enemies ^ ksq) & newAtt & ~oldAtt; - while (b) - { - // Note that here we generate illegal "double move"! - if (futilityBase + PieceValue[EG][pos.piece_on(pop_lsb(&b))] >= beta) - return true; - } - - return false; - } - - // 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 @@ -1410,7 +1352,7 @@ split_point_start: // At split points actual search starts from here assert(is_ok(first)); assert(is_ok(second)); assert(color_of(pos.piece_on(from_sq(second))) == ~pos.side_to_move()); - assert(color_of(pos.piece_on(to_sq(first))) == ~pos.side_to_move()); + assert(type_of(first) == CASTLE || color_of(pos.piece_on(to_sq(first))) == ~pos.side_to_move()); Square m1from = from_sq(first); Square m2from = from_sq(second); @@ -1418,7 +1360,10 @@ split_point_start: // At split points actual search starts from here Square m2to = to_sq(second); // The piece is the same or second's destination was vacated by the first move - if (m1to == m2from || m2to == m1from) + // We exclude the trivial case where a sliding piece does in two moves what + // it could do in one move: eg. Ra1a2, Ra2a3. + if ( m2to == m1from + || (m1to == m2from && !squares_aligned(m1from, m2from, m2to))) return true; // Second one moves through the square vacated by first one @@ -1461,24 +1406,24 @@ split_point_start: // At split points actual search starts from here // If the threatened piece has value less than or equal to the value of the // threat piece, don't prune moves which defend it. - if ( pos.is_capture(second) + if ( pos.capture(second) && ( PieceValue[MG][pos.piece_on(m2from)] >= PieceValue[MG][pos.piece_on(m2to)] || type_of(pos.piece_on(m2from)) == KING)) { // 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)))) + if (unlikely(xray) && (xray & ~pos.attacks_from(m2to))) return true; } @@ -1498,7 +1443,7 @@ split_point_start: // At split points actual search starts from here static RKISS rk; // PRNG sequence should be not deterministic - for (int i = Time::now() % 50; i > 0; i--) + for (int i = Time::now() % 50; i > 0; --i) rk.rand(); // RootMoves are already sorted by score in descending order @@ -1510,7 +1455,7 @@ split_point_start: // At split points actual search starts from here // Choose best move. For each move score we add two terms both dependent on // weakness, one deterministic and bigger for weaker moves, and one random, // then we choose the move with the resulting highest score. - for (size_t i = 0; i < PVSize; i++) + for (size_t i = 0; i < PVSize; ++i) { int s = RootMoves[i].score; @@ -1543,11 +1488,11 @@ split_point_start: // At split points actual search starts from here size_t uciPVSize = std::min((size_t)Options["MultiPV"], RootMoves.size()); int selDepth = 0; - for (size_t i = 0; i < Threads.size(); i++) + for (size_t i = 0; i < Threads.size(); ++i) if (Threads[i]->maxPly > selDepth) selDepth = Threads[i]->maxPly; - for (size_t i = 0; i < uciPVSize; i++) + for (size_t i = 0; i < uciPVSize; ++i) { bool updated = (i <= PVIdx); @@ -1569,7 +1514,7 @@ split_point_start: // At split points actual search starts from here << " multipv " << i + 1 << " pv"; - for (size_t j = 0; RootMoves[i].pv[j] != MOVE_NONE; j++) + for (size_t j = 0; RootMoves[i].pv[j] != MOVE_NONE; ++j) s << " " << move_to_uci(RootMoves[i].pv[j], pos.is_chess960()); } @@ -1586,8 +1531,8 @@ 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; + StateInfo state[MAX_PLY_PLUS_6], *st = state; + const TTEntry* tte; int ply = 0; Move m = pv[0]; @@ -1602,8 +1547,8 @@ void RootMove::extract_pv_from_tt(Position& pos) { tte = TT.probe(pos.key()); } while ( tte - && pos.is_pseudo_legal(m = tte->move()) // Local copy, TT could change - && pos.pl_move_is_legal(m, pos.pinned_pieces()) + && pos.pseudo_legal(m = tte->move()) // Local copy, TT could change + && pos.legal(m, pos.pinned_pieces(pos.side_to_move())) && ply < MAX_PLY && (!pos.is_draw() || ply < 2)); @@ -1619,8 +1564,8 @@ 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; + StateInfo state[MAX_PLY_PLUS_6], *st = state; + const TTEntry* tte; int ply = 0; do { @@ -1689,15 +1634,16 @@ void Thread::idle_loop() { Threads.mutex.lock(); assert(searching); + assert(activeSplitPoint); SplitPoint* sp = activeSplitPoint; Threads.mutex.unlock(); - Stack ss[MAX_PLY_PLUS_2]; + Stack stack[MAX_PLY_PLUS_6], *ss = stack+2; // To allow referencing (ss-2) Position pos(*sp->pos, this); - memcpy(ss, sp->ss - 1, 4 * sizeof(Stack)); - (ss+1)->splitPoint = sp; + std::memcpy(ss-2, sp->ss-2, 5 * sizeof(Stack)); + ss->splitPoint = sp; sp->mutex.lock(); @@ -1707,13 +1653,13 @@ void Thread::idle_loop() { 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); @@ -1783,8 +1729,8 @@ void check_time() { // Loop across all split points and sum accumulated SplitPoint nodes plus // 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 (size_t i = 0; i < Threads.size(); ++i) + for (int j = 0; j < Threads[i]->splitPointsSize; ++j) { SplitPoint& sp = Threads[i]->splitPoints[j]; @@ -1810,7 +1756,7 @@ void check_time() { && !Signals.failedLowAtRoot && elapsed > TimeMgr.available_time(); - bool noMoreTime = elapsed > TimeMgr.maximum_time() - 2 * TimerResolution + bool noMoreTime = elapsed > TimeMgr.maximum_time() - 2 * TimerThread::Resolution || stillAtFirstMove; if ( (Limits.use_time_management() && noMoreTime)