X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=94052ef5a482bacc44968c35be562c0eda4cf6e3;hp=7029ae032ef8ba2703a7fa5080f4f319628fcf46;hb=b40e45c1cc51bd228898314264d6d241478b23d8;hpb=30c583204f97da2c67b5042c30327013e70ae209 diff --git a/src/search.cpp b/src/search.cpp index 7029ae03..94052ef5 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -39,7 +39,6 @@ namespace Search { - SignalsType Signals; LimitsType Limits; } @@ -68,21 +67,25 @@ namespace { const int skipPhase[] = { 0, 1, 0, 1, 2, 3, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 5, 6, 7 }; // Razoring and futility margin based on depth - const int razor_margin[4] = { 483, 570, 603, 554 }; + // razor_margin[0] is unused as long as depth >= ONE_PLY in search + const int razor_margin[] = { 0, 570, 603, 554 }; Value futility_margin(Depth d) { return Value(150 * d / ONE_PLY); } // Futility and reductions lookup tables, initialized at startup int FutilityMoveCounts[2][16]; // [improving][depth] int Reductions[2][2][64][64]; // [pv][improving][depth][moveNumber] + // Threshold used for countermoves based pruning + const int CounterMovePruneThreshold = 0; + template Depth reduction(bool i, Depth d, int mn) { return Reductions[PvNode][i][std::min(d / ONE_PLY, 63)][std::min(mn, 63)] * ONE_PLY; } // History and stats update bonus, based on depth - Value stat_bonus(Depth depth) { - int d = depth / ONE_PLY ; - return d > 17 ? VALUE_ZERO : Value(d * d + 2 * d - 2); + int stat_bonus(Depth depth) { + int d = depth / ONE_PLY; + return d > 17 ? 0 : d * d + 2 * d - 2; } // Skill structure is used to implement strength limit @@ -97,8 +100,8 @@ namespace { Move best = MOVE_NONE; }; - // EasyMoveManager structure is used to detect an 'easy move'. When the PV is - // stable across multiple search iterations, we can quickly return the best move. + // EasyMoveManager structure is used to detect an 'easy move'. When the PV is stable + // across multiple search iterations, we can quickly return the best move. struct EasyMoveManager { void clear() { @@ -148,9 +151,8 @@ namespace { Value value_to_tt(Value v, int ply); Value value_from_tt(Value v, int ply); void update_pv(Move* pv, Move move, Move* childPv); - void update_cm_stats(Stack* ss, Piece pc, Square s, Value bonus); - void update_stats(const Position& pos, Stack* ss, Move move, Move* quiets, int quietsCnt, Value bonus); - void check_time(); + void update_continuation_histories(Stack* ss, Piece pc, Square to, int bonus); + void update_stats(const Position& pos, Stack* ss, Move move, Move* quiets, int quietsCnt, int bonus); } // namespace @@ -175,13 +177,13 @@ void Search::init() { for (int d = 0; d < 16; ++d) { - FutilityMoveCounts[0][d] = int(2.4 + 0.773 * pow(d + 0.00, 1.8)); - FutilityMoveCounts[1][d] = int(2.9 + 1.045 * pow(d + 0.49, 1.8)); + FutilityMoveCounts[0][d] = int(2.4 + 0.74 * pow(d, 1.78)); + FutilityMoveCounts[1][d] = int(5.0 + 1.00 * pow(d, 2.00)); } } -/// Search::clear() resets search state to zero, to obtain reproducible results +/// Search::clear() resets search state to its initial value, to obtain reproducible results void Search::clear() { @@ -189,12 +191,17 @@ void Search::clear() { for (Thread* th : Threads) { - th->counterMoves.clear(); - th->history.clear(); - th->counterMoveHistory.clear(); - th->resetCalls = true; + th->counterMoves.fill(MOVE_NONE); + th->mainHistory.fill(0); + + for (auto& to : th->contHistory) + for (auto& h : to) + h.fill(0); + + th->contHistory[NO_PIECE][0].fill(CounterMovePruneThreshold - 1); } + Threads.main()->callsCnt = 0; Threads.main()->previousScore = VALUE_INFINITE; } @@ -235,6 +242,7 @@ void MainThread::search() { Color us = rootPos.side_to_move(); Time.init(Limits, us, rootPos.game_ply()); + TT.new_search(); int contempt = Options["Contempt"] * PawnValueEg / 100; // From centipawns DrawValue[ us] = VALUE_DRAW - Value(contempt); @@ -262,18 +270,18 @@ void MainThread::search() { Time.availableNodes += Limits.inc[us] - Threads.nodes_searched(); // When we reach the maximum depth, we can arrive here without a raise of - // Signals.stop. However, if we are pondering or in an infinite search, + // Threads.stop. However, if we are pondering or in an infinite search, // the UCI protocol states that we shouldn't print the best move before the // GUI sends a "stop" or "ponderhit" command. We therefore simply wait here - // until the GUI sends one of those commands (which also raises Signals.stop). - if (!Signals.stop && (Limits.ponder || Limits.infinite)) + // until the GUI sends one of those commands (which also raises Threads.stop). + if (!Threads.stop && (Limits.ponder || Limits.infinite)) { - Signals.stopOnPonderhit = true; - wait(Signals.stop); + Threads.stopOnPonderhit = true; + wait(Threads.stop); } // Stop the threads if not already stopped - Signals.stop = true; + Threads.stop = true; // Wait until all threads have finished for (Thread* th : Threads) @@ -325,8 +333,8 @@ void Thread::search() { MainThread* mainThread = (this == Threads.main() ? Threads.main() : nullptr); std::memset(ss-4, 0, 7 * sizeof(Stack)); - for(int i = 4; i > 0; i--) - (ss-i)->counterMoves = &this->counterMoveHistory[NO_PIECE][0]; // Use as sentinel + for (int i = 4; i > 0; i--) + (ss-i)->contHistory = &this->contHistory[NO_PIECE][0]; // Use as sentinel bestValue = delta = alpha = -VALUE_INFINITE; beta = VALUE_INFINITE; @@ -338,7 +346,6 @@ void Thread::search() { EasyMove.clear(); mainThread->easyMovePlayed = mainThread->failedLow = false; mainThread->bestMoveChanges = 0; - TT.new_search(); } size_t multiPV = Options["MultiPV"]; @@ -353,8 +360,8 @@ void Thread::search() { // Iterative deepening loop until requested to stop or the target depth is reached while ( (rootDepth += ONE_PLY) < DEPTH_MAX - && !Signals.stop - && (!Limits.depth || Threads.main()->rootDepth / ONE_PLY <= Limits.depth)) + && !Threads.stop + && !(Limits.depth && mainThread && rootDepth / ONE_PLY > Limits.depth)) { // Distribute search depths across the threads if (idx) @@ -374,8 +381,11 @@ void Thread::search() { rm.previousScore = rm.score; // MultiPV loop. We perform a full root search for each PV line - for (PVIdx = 0; PVIdx < multiPV && !Signals.stop; ++PVIdx) + for (PVIdx = 0; PVIdx < multiPV && !Threads.stop; ++PVIdx) { + // Reset UCI info selDepth for each depth and each PV line + selDepth = 0; + // Reset aspiration window starting size if (rootDepth >= 5 * ONE_PLY) { @@ -402,7 +412,7 @@ void Thread::search() { // If search has been stopped, we break immediately. Sorting and // writing PV back to TT is safe because RootMoves is still // valid, although it refers to the previous iteration. - if (Signals.stop) + if (Threads.stop) break; // When failing high/low give some update (without cluttering @@ -423,14 +433,11 @@ void Thread::search() { if (mainThread) { mainThread->failedLow = true; - Signals.stopOnPonderhit = false; + Threads.stopOnPonderhit = false; } } else if (bestValue >= beta) - { - alpha = (alpha + beta) / 2; beta = std::min(bestValue + delta, VALUE_INFINITE); - } else break; @@ -445,11 +452,11 @@ void Thread::search() { if (!mainThread) continue; - if (Signals.stop || PVIdx + 1 == multiPV || Time.elapsed() > 3000) + if (Threads.stop || PVIdx + 1 == multiPV || Time.elapsed() > 3000) sync_cout << UCI::pv(rootPos, rootDepth, alpha, beta) << sync_endl; } - if (!Signals.stop) + if (!Threads.stop) completedDepth = rootDepth; if (!mainThread) @@ -463,12 +470,12 @@ void Thread::search() { if ( Limits.mate && bestValue >= VALUE_MATE_IN_MAX_PLY && VALUE_MATE - bestValue <= 2 * Limits.mate) - Signals.stop = true; + Threads.stop = true; // Do we have time for the next iteration? Can we stop searching now? if (Limits.use_time_management()) { - if (!Signals.stop && !Signals.stopOnPonderhit) + if (!Threads.stop && !Threads.stopOnPonderhit) { // Stop the search if only one legal move is available, or if all // of the available time has been used, or if we matched an easyMove @@ -490,9 +497,9 @@ void Thread::search() { // If we are allowed to ponder do not stop the search now but // keep pondering until the GUI sends "ponderhit" or "stop". if (Limits.ponder) - Signals.stopOnPonderhit = true; + Threads.stopOnPonderhit = true; else - Signals.stop = true; + Threads.stop = true; } } @@ -542,44 +549,30 @@ namespace { Depth extension, newDepth; Value bestValue, value, ttValue, eval; bool ttHit, inCheck, givesCheck, singularExtensionNode, improving; - bool captureOrPromotion, doFullDepthSearch, moveCountPruning, skipQuiets; + bool captureOrPromotion, doFullDepthSearch, moveCountPruning, skipQuiets, ttCapture; Piece moved_piece; int moveCount, quietCount; // Step 1. Initialize node Thread* thisThread = pos.this_thread(); inCheck = pos.checkers(); - moveCount = quietCount = ss->moveCount = 0; - ss->history = VALUE_ZERO; + moveCount = quietCount = ss->moveCount = 0; + ss->statScore = 0; bestValue = -VALUE_INFINITE; ss->ply = (ss-1)->ply + 1; // Check for the available remaining time - if (thisThread->resetCalls.load(std::memory_order_relaxed)) - { - thisThread->resetCalls = false; - // At low node count increase the checking rate to about 0.1% of nodes - // otherwise use a default value. - thisThread->callsCnt = Limits.nodes ? std::min((int64_t)4096, Limits.nodes / 1024) - : 4096; - } - - if (--thisThread->callsCnt <= 0) - { - for (Thread* th : Threads) - th->resetCalls = true; - - check_time(); - } + if (thisThread == Threads.main()) + static_cast(thisThread)->check_time(); // Used to send selDepth info to GUI - if (PvNode && thisThread->maxPly < ss->ply) - thisThread->maxPly = ss->ply; + if (PvNode && thisThread->selDepth < ss->ply) + thisThread->selDepth = ss->ply; if (!rootNode) { // Step 2. Check for aborted search and immediate draw - if (Signals.stop.load(std::memory_order_relaxed) || pos.is_draw(ss->ply) || ss->ply >= MAX_PLY) + if (Threads.stop.load(std::memory_order_relaxed) || pos.is_draw(ss->ply) || ss->ply >= MAX_PLY) return ss->ply >= MAX_PLY && !inCheck ? evaluate(pos) : DrawValue[pos.side_to_move()]; @@ -598,7 +591,7 @@ namespace { assert(0 <= ss->ply && ss->ply < MAX_PLY); ss->currentMove = (ss+1)->excludedMove = bestMove = MOVE_NONE; - ss->counterMoves = &thisThread->counterMoveHistory[NO_PIECE][0]; + ss->contHistory = &thisThread->contHistory[NO_PIECE][0]; (ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE; Square prevSq = to_sq((ss-1)->currentMove); @@ -630,14 +623,14 @@ namespace { // Extra penalty for a quiet TT move in previous ply when it gets refuted if ((ss-1)->moveCount == 1 && !pos.captured_piece()) - update_cm_stats(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY)); + update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY)); } // Penalty for a quiet ttMove that fails low else if (!pos.capture_or_promotion(ttMove)) { - Value penalty = -stat_bonus(depth + ONE_PLY); - thisThread->history.update(pos.side_to_move(), ttMove, penalty); - update_cm_stats(ss, pos.moved_piece(ttMove), to_sq(ttMove), penalty); + int penalty = -stat_bonus(depth); + thisThread->mainHistory.update(pos.side_to_move(), ttMove, penalty); + update_continuation_histories(ss, pos.moved_piece(ttMove), to_sq(ttMove), penalty); } } return ttValue; @@ -658,7 +651,7 @@ namespace { if (err != TB::ProbeState::FAIL) { - thisThread->tbHits++; + thisThread->tbHits.fetch_add(1, std::memory_order_relaxed); int drawScore = TB::UseRule50 ? 1 : 0; @@ -689,9 +682,9 @@ namespace { eval = ss->staticEval = evaluate(pos); // Can ttValue be used as a better position evaluation? - if (ttValue != VALUE_NONE) - if (tte->bound() & (ttValue > eval ? BOUND_LOWER : BOUND_UPPER)) - eval = ttValue; + if ( ttValue != VALUE_NONE + && (tte->bound() & (ttValue > eval ? BOUND_LOWER : BOUND_UPPER))) + eval = ttValue; } else { @@ -741,7 +734,7 @@ namespace { Depth R = ((823 + 67 * depth / ONE_PLY) / 256 + std::min((eval - beta) / PawnValueMg, 3)) * ONE_PLY; ss->currentMove = MOVE_NULL; - ss->counterMoves = &thisThread->counterMoveHistory[NO_PIECE][0]; + ss->contHistory = &thisThread->contHistory[NO_PIECE][0]; pos.do_null_move(st); Value nullValue = depth-R < ONE_PLY ? -qsearch(pos, ss+1, -beta, -beta+1) @@ -774,9 +767,7 @@ namespace { && abs(beta) < VALUE_MATE_IN_MAX_PLY) { Value rbeta = std::min(beta + 200, VALUE_INFINITE); - Depth rdepth = depth - 4 * ONE_PLY; - assert(rdepth >= ONE_PLY); assert(is_ok((ss-1)->currentMove)); MovePicker mp(pos, ttMove, rbeta - ss->staticEval); @@ -785,10 +776,11 @@ namespace { if (pos.legal(move)) { ss->currentMove = move; - ss->counterMoves = &thisThread->counterMoveHistory[pos.moved_piece(move)][to_sq(move)]; + ss->contHistory = &thisThread->contHistory[pos.moved_piece(move)][to_sq(move)]; + assert(depth >= 5 * ONE_PLY); pos.do_move(move, st); - value = -search(pos, ss+1, -rbeta, -rbeta+1, rdepth, !cutNode, false); + value = -search(pos, ss+1, -rbeta, -rbeta+1, depth - 4 * ONE_PLY, !cutNode, false); pos.undo_move(move); if (value >= rbeta) return value; @@ -809,14 +801,10 @@ namespace { moves_loop: // When in check search starts from here - const CounterMoveStats& cmh = *(ss-1)->counterMoves; - const CounterMoveStats& fmh = *(ss-2)->counterMoves; - const CounterMoveStats& fm2 = *(ss-4)->counterMoves; - const bool cm_ok = is_ok((ss-1)->currentMove); - const bool fm_ok = is_ok((ss-2)->currentMove); - const bool f2_ok = is_ok((ss-4)->currentMove); + const PieceToHistory* contHist[] = { (ss-1)->contHistory, (ss-2)->contHistory, nullptr, (ss-4)->contHistory }; + Move countermove = thisThread->counterMoves[pos.piece_on(prevSq)][prevSq]; - MovePicker mp(pos, ttMove, depth, ss); + MovePicker mp(pos, ttMove, depth, &thisThread->mainHistory, contHist, countermove, ss->killers); value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc improving = ss->staticEval >= (ss-2)->staticEval /* || ss->staticEval == VALUE_NONE Already implicit in the previous condition */ @@ -830,6 +818,7 @@ moves_loop: // When in check search starts from here && (tte->bound() & BOUND_LOWER) && tte->depth() >= depth - 3 * ONE_PLY; skipQuiets = false; + ttCapture = false; // Step 11. Loop through moves // Loop through all pseudo-legal moves until no moves remain or a beta cutoff occurs @@ -874,7 +863,7 @@ moves_loop: // When in check search starts from here // (alpha-s, beta-s), and just one fails high on (alpha, beta), then that move // is singular and should be extended. To verify this we do a reduced search // on all the other moves but the ttMove and if the result is lower than - // ttValue minus a margin then we extend the ttMove. + // ttValue minus a margin then we will extend the ttMove. if ( singularExtensionNode && move == ttMove && pos.legal(move)) @@ -888,9 +877,9 @@ moves_loop: // When in check search starts from here if (value < rBeta) extension = ONE_PLY; } - else if ( givesCheck + else if ( givesCheck && !moveCountPruning - && pos.see_ge(move, VALUE_ZERO)) + && pos.see_ge(move)) extension = ONE_PLY; // Calculate new depth for this move @@ -898,14 +887,16 @@ moves_loop: // When in check search starts from here // Step 13. Pruning at shallow depth if ( !rootNode + && pos.non_pawn_material(pos.side_to_move()) && bestValue > VALUE_MATED_IN_MAX_PLY) { if ( !captureOrPromotion && !givesCheck - && (!pos.advanced_pawn_push(move) || pos.non_pawn_material() >= 5000)) + && (!pos.advanced_pawn_push(move) || pos.non_pawn_material() >= Value(5000))) { // Move count based pruning - if (moveCountPruning) { + if (moveCountPruning) + { skipQuiets = true; continue; } @@ -915,9 +906,8 @@ moves_loop: // When in check search starts from here // Countermoves based pruning if ( lmrDepth < 3 - && ((cmh[moved_piece][to_sq(move)] < VALUE_ZERO) || !cm_ok) - && ((fmh[moved_piece][to_sq(move)] < VALUE_ZERO) || !fm_ok) - && ((fm2[moved_piece][to_sq(move)] < VALUE_ZERO) || !f2_ok || (cm_ok && fm_ok))) + && (*contHist[0])[moved_piece][to_sq(move)] < CounterMovePruneThreshold + && (*contHist[1])[moved_piece][to_sq(move)] < CounterMovePruneThreshold) continue; // Futility pruning: parent node @@ -947,9 +937,12 @@ moves_loop: // When in check search starts from here continue; } + if (move == ttMove && captureOrPromotion) + ttCapture = true; + // Update the current move (this must be done after singular extension search) ss->currentMove = move; - ss->counterMoves = &thisThread->counterMoveHistory[moved_piece][to_sq(move)]; + ss->contHistory = &thisThread->contHistory[moved_piece][to_sq(move)]; // Step 14. Make the move pos.do_move(move, st, givesCheck); @@ -966,6 +959,10 @@ moves_loop: // When in check search starts from here r -= r ? ONE_PLY : DEPTH_ZERO; else { + // Increase reduction if ttMove is a capture + if (ttCapture) + r += ONE_PLY; + // Increase reduction for cut nodes if (cutNode) r += 2 * ONE_PLY; @@ -973,25 +970,25 @@ moves_loop: // When in check search starts from here // Decrease reduction for moves that escape a capture. Filter out // castling moves, because they are coded as "king captures rook" and // hence break make_move(). - else if ( type_of(move) == NORMAL - && !pos.see_ge(make_move(to_sq(move), from_sq(move)), VALUE_ZERO)) + else if ( type_of(move) == NORMAL + && !pos.see_ge(make_move(to_sq(move), from_sq(move)))) r -= 2 * ONE_PLY; - ss->history = cmh[moved_piece][to_sq(move)] - + fmh[moved_piece][to_sq(move)] - + fm2[moved_piece][to_sq(move)] - + thisThread->history.get(~pos.side_to_move(), move) - - 4000; // Correction factor + ss->statScore = thisThread->mainHistory[~pos.side_to_move()][from_to(move)] + + (*contHist[0])[moved_piece][to_sq(move)] + + (*contHist[1])[moved_piece][to_sq(move)] + + (*contHist[3])[moved_piece][to_sq(move)] + - 4000; // Decrease/increase reduction by comparing opponent's stat score - if (ss->history > VALUE_ZERO && (ss-1)->history < VALUE_ZERO) + if (ss->statScore > 0 && (ss-1)->statScore < 0) r -= ONE_PLY; - else if (ss->history < VALUE_ZERO && (ss-1)->history > VALUE_ZERO) + else if (ss->statScore < 0 && (ss-1)->statScore > 0) r += ONE_PLY; // Decrease/increase reduction for moves with a good/bad history - r = std::max(DEPTH_ZERO, (r / ONE_PLY - ss->history / 20000) * ONE_PLY); + r = std::max(DEPTH_ZERO, (r / ONE_PLY - ss->statScore / 20000) * ONE_PLY); } Depth d = std::max(newDepth - r, ONE_PLY); @@ -1033,7 +1030,7 @@ moves_loop: // When in check search starts from here // Finished searching the move. If a stop occurred, the return value of // the search cannot be trusted, and we return immediately without // updating best move, PV and TT. - if (Signals.stop.load(std::memory_order_relaxed)) + if (Threads.stop.load(std::memory_order_relaxed)) return VALUE_ZERO; if (rootNode) @@ -1045,6 +1042,7 @@ moves_loop: // When in check search starts from here if (moveCount == 1 || value > alpha) { rm.score = value; + rm.selDepth = thisThread->selDepth; rm.pv.resize(1); assert((ss+1)->pv); @@ -1059,8 +1057,8 @@ moves_loop: // When in check search starts from here ++static_cast(thisThread)->bestMoveChanges; } else - // All other moves but the PV are set to the lowest value: this is - // not a problem when sorting because the sort is stable and the + // All other moves but the PV are set to the lowest value: this + // is not a problem when sorting because the sort is stable and the // move position in the list is preserved - just the PV is pushed up. rm.score = -VALUE_INFINITE; } @@ -1094,7 +1092,7 @@ moves_loop: // When in check search starts from here // completed. But in this case bestValue is valid because we have fully // searched our subtree, and we can anyhow save the result in TT. /* - if (Signals.stop) + if (Threads.stop) return VALUE_DRAW; */ @@ -1110,25 +1108,25 @@ moves_loop: // When in check search starts from here : inCheck ? mated_in(ss->ply) : DrawValue[pos.side_to_move()]; else if (bestMove) { - // Quiet best move: update move sorting heuristics if (!pos.capture_or_promotion(bestMove)) update_stats(pos, ss, bestMove, quietsSearched, quietCount, stat_bonus(depth)); // Extra penalty for a quiet TT move in previous ply when it gets refuted if ((ss-1)->moveCount == 1 && !pos.captured_piece()) - update_cm_stats(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY)); + update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY)); } // Bonus for prior countermove that caused the fail low else if ( depth >= 3 * ONE_PLY && !pos.captured_piece() - && cm_ok) - update_cm_stats(ss-1, pos.piece_on(prevSq), prevSq, stat_bonus(depth)); + && is_ok((ss-1)->currentMove)) + update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, stat_bonus(depth)); - tte->save(posKey, value_to_tt(bestValue, ss->ply), - bestValue >= beta ? BOUND_LOWER : - PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER, - depth, bestMove, ss->staticEval, TT.generation()); + if (!excludedMove) + tte->save(posKey, value_to_tt(bestValue, ss->ply), + bestValue >= beta ? BOUND_LOWER : + PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER, + depth, bestMove, ss->staticEval, TT.generation()); assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); @@ -1158,6 +1156,7 @@ moves_loop: // When in check search starts from here Value bestValue, value, ttValue, futilityValue, futilityBase, oldAlpha; bool ttHit, givesCheck, evasionPrunable; Depth ttDepth; + int moveCount; if (PvNode) { @@ -1168,6 +1167,7 @@ moves_loop: // When in check search starts from here ss->currentMove = bestMove = MOVE_NONE; ss->ply = (ss-1)->ply + 1; + moveCount = 0; // Check for an instant draw or if the maximum ply has been reached if (pos.is_draw(ss->ply) || ss->ply >= MAX_PLY) @@ -1211,9 +1211,9 @@ moves_loop: // When in check search starts from here ss->staticEval = bestValue = evaluate(pos); // Can ttValue be used as a better position evaluation? - if (ttValue != VALUE_NONE) - if (tte->bound() & (ttValue > bestValue ? BOUND_LOWER : BOUND_UPPER)) - bestValue = ttValue; + if ( ttValue != VALUE_NONE + && (tte->bound() & (ttValue > bestValue ? BOUND_LOWER : BOUND_UPPER))) + bestValue = ttValue; } else ss->staticEval = bestValue = @@ -1240,7 +1240,8 @@ moves_loop: // When in check 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, to_sq((ss-1)->currentMove)); + const PieceToHistory* contHist[4] = {}; + MovePicker mp(pos, ttMove, depth, &pos.this_thread()->mainHistory, contHist, to_sq((ss-1)->currentMove)); // Loop through the moves until no moves remain or a beta cutoff occurs while ((move = mp.next_move()) != MOVE_NONE) @@ -1251,6 +1252,8 @@ moves_loop: // When in check search starts from here ? pos.check_squares(type_of(pos.piece_on(from_sq(move)))) & to_sq(move) : pos.gives_check(move); + moveCount++; + // Futility pruning if ( !InCheck && !givesCheck @@ -1276,13 +1279,14 @@ moves_loop: // When in check search starts from here // Detect non-capture evasions that are candidates to be pruned evasionPrunable = InCheck + && (depth != DEPTH_ZERO || moveCount > 2) && bestValue > VALUE_MATED_IN_MAX_PLY && !pos.capture(move); // Don't search moves with negative SEE values if ( (!InCheck || evasionPrunable) && type_of(move) != PROMOTION - && !pos.see_ge(move, VALUE_ZERO)) + && !pos.see_ge(move)) continue; // Speculative prefetch as early as possible @@ -1290,7 +1294,10 @@ moves_loop: // When in check search starts from here // Check for legality just before making the move if (!pos.legal(move)) + { + moveCount--; continue; + } ss->currentMove = move; @@ -1378,20 +1385,21 @@ moves_loop: // When in check search starts from here } - // update_cm_stats() updates countermove and follow-up move history + // update_continuation_histories() updates histories of the move pairs formed + // by moves at ply -1, -2, and -4 with current move. - void update_cm_stats(Stack* ss, Piece pc, Square s, Value bonus) { + void update_continuation_histories(Stack* ss, Piece pc, Square to, int bonus) { for (int i : {1, 2, 4}) if (is_ok((ss-i)->currentMove)) - (ss-i)->counterMoves->update(pc, s, bonus); + (ss-i)->contHistory->update(pc, to, bonus); } // update_stats() updates move sorting heuristics when a new quiet best move is found void update_stats(const Position& pos, Stack* ss, Move move, - Move* quiets, int quietsCnt, Value bonus) { + Move* quiets, int quietsCnt, int bonus) { if (ss->killers[0] != move) { @@ -1401,20 +1409,20 @@ moves_loop: // When in check search starts from here Color c = pos.side_to_move(); Thread* thisThread = pos.this_thread(); - thisThread->history.update(c, move, bonus); - update_cm_stats(ss, pos.moved_piece(move), to_sq(move), bonus); + thisThread->mainHistory.update(c, move, bonus); + update_continuation_histories(ss, pos.moved_piece(move), to_sq(move), bonus); if (is_ok((ss-1)->currentMove)) { Square prevSq = to_sq((ss-1)->currentMove); - thisThread->counterMoves.update(pos.piece_on(prevSq), prevSq, move); + thisThread->counterMoves[pos.piece_on(prevSq)][prevSq] = move; } // Decrease all the other played quiet moves for (int i = 0; i < quietsCnt; ++i) { - thisThread->history.update(c, quiets[i], -bonus); - update_cm_stats(ss, pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus); + thisThread->mainHistory.update(c, quiets[i], -bonus); + update_continuation_histories(ss, pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus); } } @@ -1452,11 +1460,19 @@ moves_loop: // When in check search starts from here return best; } +} // namespace // check_time() is used to print debug info and, more importantly, to detect // when we are out of available time and thus stop the search. - void check_time() { + void MainThread::check_time() { + + if (--callsCnt > 0) + return; + + // At low node count increase the checking rate to about 0.1% of nodes + // otherwise use a default value. + callsCnt = Limits.nodes ? std::min(4096, int(Limits.nodes / 1024)) : 4096; static TimePoint lastInfoTime = now(); @@ -1476,11 +1492,9 @@ moves_loop: // When in check search starts from here if ( (Limits.use_time_management() && elapsed > Time.maximum() - 10) || (Limits.movetime && elapsed >= Limits.movetime) || (Limits.nodes && Threads.nodes_searched() >= (uint64_t)Limits.nodes)) - Signals.stop = true; + Threads.stop = true; } -} // namespace - /// UCI::pv() formats PV information according to the UCI protocol. UCI requires /// that all (if any) unsearched PV lines are sent using a previous search score. @@ -1497,7 +1511,7 @@ string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) { for (size_t i = 0; i < multiPV; ++i) { - bool updated = (i <= PVIdx); + bool updated = (i <= PVIdx && rootMoves[i].score != -VALUE_INFINITE); if (depth == ONE_PLY && !updated) continue; @@ -1513,7 +1527,7 @@ string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) { ss << "info" << " depth " << d / ONE_PLY - << " seldepth " << pos.this_thread()->maxPly + << " seldepth " << rootMoves[i].selDepth << " multipv " << i + 1 << " score " << UCI::value(v);