X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fsearch.cpp;h=04299dbd887e26cf721df70ef4fd39bb7d1d73e5;hb=f66c36277fe57d0ce4f10a4aeb5b41eb0cb9ebd1;hp=f11d76be715f41eecb0ab16d6d549bd95f1ed6ef;hpb=442c40b43de8ede1e424efa674c8d45322e3b43c;p=stockfish diff --git a/src/search.cpp b/src/search.cpp index f11d76be..04299dbd 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -1,6 +1,6 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 - Copyright (C) 2004-2022 The Stockfish developers (see AUTHORS file) + Copyright (C) 2004-2023 The Stockfish developers (see AUTHORS file) Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -34,6 +34,7 @@ #include "tt.h" #include "uci.h" #include "syzygy/tbprobe.h" +#include "nnue/evaluate_nnue.h" namespace Stockfish { @@ -63,7 +64,7 @@ namespace { // Futility margin Value futility_margin(Depth d, bool improving) { - return Value(168 * (d - improving)); + return Value(154 * (d - improving)); } // Reductions lookup table, initialized at startup @@ -71,7 +72,7 @@ namespace { Depth reduction(bool i, Depth d, int mn, Value delta, Value rootDelta) { int r = Reductions[d] * Reductions[mn]; - return (r + 1463 - int(delta) * 1024 / int(rootDelta)) / 1024 + (!i && r > 1010); + return (r + 1449 - int(delta) * 937 / int(rootDelta)) / 1024 + (!i && r > 941); } constexpr int futility_move_count(bool improving, Depth depth) { @@ -81,7 +82,7 @@ namespace { // History and stats update bonus, based on depth int stat_bonus(Depth d) { - return std::min((9 * d + 270) * d - 311 , 2145); + return std::min(341 * d - 470, 1710); } // Add a small random component to draw evaluations to avoid 3-fold blindness @@ -96,7 +97,10 @@ namespace { struct Skill { Skill(int skill_level, int uci_elo) { if (uci_elo) - level = std::clamp(std::pow((uci_elo - 1346.6) / 143.4, 1 / 0.806), 0.0, 20.0); + { + double e = double(uci_elo - 1320) / (3190 - 1320); + level = std::clamp((((37.2473 * e - 40.8525) * e + 22.2943) * e - 0.311438), 0.0, 19.0); + } else level = double(skill_level); } @@ -158,7 +162,7 @@ namespace { void Search::init() { for (int i = 1; i < MAX_MOVES; ++i) - Reductions[i] = int((20.81 + std::log(Threads.size()) / 2) * std::log(i)); + Reductions[i] = int((19.47 + std::log(Threads.size()) / 2) * std::log(i)); } @@ -239,12 +243,9 @@ void MainThread::search() { bestPreviousScore = bestThread->rootMoves[0].score; bestPreviousAverageScore = bestThread->rootMoves[0].averageScore; - for (Thread* th : Threads) - th->previousDepth = bestThread->completedDepth; - // Send again PV info if we have a new best thread if (bestThread != this) - sync_cout << UCI::pv(bestThread->rootPos, bestThread->completedDepth, -VALUE_INFINITE, VALUE_INFINITE) << sync_endl; + sync_cout << UCI::pv(bestThread->rootPos, bestThread->completedDepth) << sync_endl; sync_cout << "bestmove " << UCI::move(bestThread->rootMoves[0].pv[0], rootPos.is_chess960()); @@ -276,8 +277,11 @@ void Thread::search() { int iterIdx = 0; std::memset(ss-7, 0, 10 * sizeof(Stack)); - for (int i = 7; i > 0; i--) + for (int i = 7; i > 0; --i) + { (ss-i)->continuationHistory = &this->continuationHistory[0][0][NO_PIECE][0]; // Use as a sentinel + (ss-i)->staticEval = VALUE_NONE; + } for (int i = 0; i <= MAX_PLY + 2; ++i) (ss+i)->ply = i; @@ -286,9 +290,18 @@ void Thread::search() { bestValue = delta = alpha = -VALUE_INFINITE; beta = VALUE_INFINITE; + optimism[WHITE] = optimism[BLACK] = VALUE_ZERO; if (mainThread) { + + if (!rootPos.checkers()) + { + int rootComplexity; + Eval::evaluate(rootPos, &rootComplexity); + mainThread->complexity = std::min(1.03 + (rootComplexity - 241) / 1552.0, 1.45); + } + if (mainThread->bestPreviousScore == VALUE_INFINITE) for (int i = 0; i < 4; ++i) mainThread->iterValue[i] = VALUE_ZERO; @@ -307,12 +320,6 @@ void Thread::search() { multiPV = std::min(multiPV, rootMoves.size()); - complexityAverage.set(174, 1); - - trend = SCORE_ZERO; - optimism[ us] = Value(39); - optimism[~us] = -optimism[us]; - int searchAgainCounter = 0; // Iterative deepening loop until requested to stop or the target depth is reached @@ -333,7 +340,7 @@ void Thread::search() { pvLast = 0; if (!Threads.increaseDepth) - searchAgainCounter++; + searchAgainCounter++; // MultiPV loop. We perform a full root search for each PV line for (pvIdx = 0; pvIdx < multiPV && !Threads.stop; ++pvIdx) @@ -353,16 +360,12 @@ void Thread::search() { if (rootDepth >= 4) { Value prev = rootMoves[pvIdx].averageScore; - delta = Value(16) + int(prev) * prev / 19178; + delta = Value(10) + int(prev) * prev / 16502; alpha = std::max(prev - delta,-VALUE_INFINITE); beta = std::min(prev + delta, VALUE_INFINITE); - // Adjust trend and optimism based on root move's previousScore - int tr = sigmoid(prev, 3, 8, 90, 125, 1); - trend = (us == WHITE ? make_score(tr, tr / 2) - : -make_score(tr, tr / 2)); - - int opt = sigmoid(prev, 8, 17, 144, 13966, 183); + // Adjust optimism based on root move's previousScore + int opt = 120 * prev / (std::abs(prev) + 161); optimism[ us] = Value(opt); optimism[~us] = -optimism[us]; } @@ -373,7 +376,9 @@ void Thread::search() { int failedHighCnt = 0; while (true) { - Depth adjustedDepth = std::max(1, rootDepth - failedHighCnt - searchAgainCounter); + // Adjust the effective depth searched, but ensuring at least one effective increment for every + // four searchAgain steps (see issue #2717). + Depth adjustedDepth = std::max(1, rootDepth - failedHighCnt - 3 * (searchAgainCounter + 1) / 4); bestValue = Stockfish::search(rootPos, ss, alpha, beta, adjustedDepth, false); // Bring the best move to the front. It is critical that sorting @@ -396,7 +401,7 @@ void Thread::search() { && multiPV == 1 && (bestValue <= alpha || bestValue >= beta) && Time.elapsed() > 3000) - sync_cout << UCI::pv(rootPos, rootDepth, alpha, beta) << sync_endl; + sync_cout << UCI::pv(rootPos, rootDepth) << sync_endl; // In case of failing low/high increase aspiration window and // re-search, otherwise exit the loop. @@ -427,15 +432,16 @@ void Thread::search() { if ( mainThread && (Threads.stop || pvIdx + 1 == multiPV || Time.elapsed() > 3000)) - sync_cout << UCI::pv(rootPos, rootDepth, alpha, beta) << sync_endl; + sync_cout << UCI::pv(rootPos, rootDepth) << sync_endl; } if (!Threads.stop) completedDepth = rootDepth; - if (rootMoves[0].pv[0] != lastBestMove) { - lastBestMove = rootMoves[0].pv[0]; - lastBestMoveDepth = rootDepth; + if (rootMoves[0].pv[0] != lastBestMove) + { + lastBestMove = rootMoves[0].pv[0]; + lastBestMoveDepth = rootDepth; } // Have we found a "mate in x"? @@ -463,18 +469,16 @@ void Thread::search() { && !Threads.stop && !mainThread->stopOnPonderhit) { - double fallingEval = (69 + 12 * (mainThread->bestPreviousAverageScore - bestValue) - + 6 * (mainThread->iterValue[iterIdx] - bestValue)) / 781.4; + double fallingEval = (69 + 13 * (mainThread->bestPreviousAverageScore - bestValue) + + 6 * (mainThread->iterValue[iterIdx] - bestValue)) / 619.6; fallingEval = std::clamp(fallingEval, 0.5, 1.5); // If the bestMove is stable over several iterations, reduce time accordingly - timeReduction = lastBestMoveDepth + 10 < completedDepth ? 1.63 : 0.73; - double reduction = (1.56 + mainThread->previousTimeReduction) / (2.20 * timeReduction); - double bestMoveInstability = 1 + 1.7 * totBestMoveChanges / Threads.size(); - int complexity = mainThread->complexityAverage.value(); - double complexPosition = std::clamp(1.0 + (complexity - 277) / 1819, 0.5, 1.5); + timeReduction = lastBestMoveDepth + 8 < completedDepth ? 1.57 : 0.65; + double reduction = (1.4 + mainThread->previousTimeReduction) / (2.08 * timeReduction); + double bestMoveInstability = 1 + 1.8 * totBestMoveChanges / Threads.size(); - double totalTime = Time.optimum() * fallingEval * reduction * bestMoveInstability * complexPosition; + double totalTime = Time.optimum() * fallingEval * reduction * bestMoveInstability * mainThread->complexity; // Cap used time in case of a single legal move for a better viewer experience in tournaments // yielding correct scores and sufficiently fast moves. @@ -491,12 +495,11 @@ void Thread::search() { else Threads.stop = true; } - else if ( Threads.increaseDepth - && !mainThread->ponder - && Time.elapsed() > totalTime * 0.43) - Threads.increaseDepth = false; + else if ( !mainThread->ponder + && Time.elapsed() > totalTime * 0.50) + Threads.increaseDepth = false; else - Threads.increaseDepth = true; + Threads.increaseDepth = true; } mainThread->iterValue[iterIdx] = bestValue; @@ -524,7 +527,6 @@ namespace { constexpr bool PvNode = nodeType != NonPV; constexpr bool rootNode = nodeType == Root; - const Depth maxNextDepth = rootNode ? depth : depth + 1; // Check if we have an upcoming move which draws by repetition, or // if the opponent had an alternative move earlier to this position. @@ -556,14 +558,13 @@ namespace { Move ttMove, move, excludedMove, bestMove; Depth extension, newDepth; Value bestValue, value, ttValue, eval, maxValue, probCutBeta; - bool givesCheck, improving, didLMR, priorCapture; - bool capture, doFullDepthSearch, moveCountPruning, ttCapture; + bool givesCheck, improving, priorCapture, singularQuietLMR; + bool capture, moveCountPruning, ttCapture; Piece movedPiece; int moveCount, captureCount, quietCount, improvement, complexity; // Step 1. Initialize node Thread* thisThread = pos.this_thread(); - thisThread->depth = depth; ss->inCheck = pos.checkers(); priorCapture = pos.captured_piece(); Color us = pos.side_to_move(); @@ -604,52 +605,46 @@ namespace { assert(0 <= ss->ply && ss->ply < MAX_PLY); - (ss+1)->ttPv = false; (ss+1)->excludedMove = bestMove = MOVE_NONE; (ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE; (ss+2)->cutoffCnt = 0; ss->doubleExtensions = (ss-1)->doubleExtensions; - Square prevSq = to_sq((ss-1)->currentMove); + Square prevSq = is_ok((ss-1)->currentMove) ? to_sq((ss-1)->currentMove) : SQ_NONE; + ss->statScore = 0; - // Initialize statScore to zero for the grandchildren of the current position. - // So statScore is shared between all grandchildren and only the first grandchild - // starts with statScore = 0. Later grandchildren start with the last calculated - // statScore of the previous grandchild. This influences the reduction rules in - // LMR which are based on the statScore of parent position. - if (!rootNode) - (ss+2)->statScore = 0; - - // Step 4. Transposition table lookup. We don't want the score of a partial - // search to overwrite a previous full search TT value, so we use a different - // position key in case of an excluded move. + // Step 4. Transposition table lookup. excludedMove = ss->excludedMove; - posKey = excludedMove == MOVE_NONE ? pos.key() : pos.key() ^ make_key(excludedMove); + posKey = pos.key(); tte = TT.probe(posKey, ss->ttHit); ttValue = ss->ttHit ? value_from_tt(tte->value(), ss->ply, pos.rule50_count()) : VALUE_NONE; ttMove = rootNode ? thisThread->rootMoves[thisThread->pvIdx].pv[0] : ss->ttHit ? tte->move() : MOVE_NONE; - ttCapture = ttMove && pos.capture(ttMove); + ttCapture = ttMove && pos.capture_stage(ttMove); + + // At this point, if excluded, skip straight to step 6, static eval. However, + // to save indentation, we list the condition in all code between here and there. if (!excludedMove) ss->ttPv = PvNode || (ss->ttHit && tte->is_pv()); // At non-PV nodes we check for an early TT cutoff if ( !PvNode && ss->ttHit - && tte->depth() > depth - ((int)thisThread->id() & 0x1) + && !excludedMove + && tte->depth() > depth - (tte->bound() == BOUND_EXACT) && ttValue != VALUE_NONE // Possible in case of TT access race && (tte->bound() & (ttValue >= beta ? BOUND_LOWER : BOUND_UPPER))) { - // If ttMove is quiet, update move sorting heuristics on TT hit (~1 Elo) + // If ttMove is quiet, update move sorting heuristics on TT hit (~2 Elo) if (ttMove) { if (ttValue >= beta) { - // Bonus for a quiet ttMove that fails high (~3 Elo) + // Bonus for a quiet ttMove that fails high (~2 Elo) if (!ttCapture) update_quiet_stats(pos, ss, ttMove, stat_bonus(depth)); - // Extra penalty for early quiet moves of the previous ply (~0 Elo) - if ((ss-1)->moveCount <= 2 && !priorCapture) + // Extra penalty for early quiet moves of the previous ply (~0 Elo on STC, ~2 Elo on LTC) + if (prevSq != SQ_NONE && (ss-1)->moveCount <= 2 && !priorCapture) update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + 1)); } // Penalty for a quiet ttMove that fails low (~1 Elo) @@ -668,7 +663,7 @@ namespace { } // Step 5. Tablebases probe - if (!rootNode && TB::Cardinality) + if (!rootNode && !excludedMove && TB::Cardinality) { int piecesCount = pos.count(); @@ -731,6 +726,13 @@ namespace { complexity = 0; goto moves_loop; } + else if (excludedMove) + { + // Providing the hint that this node's accumulator will be used often brings significant Elo gain (13 Elo) + Eval::NNUE::hint_common_parent_position(pos); + eval = ss->staticEval; + complexity = abs(ss->staticEval - pos.psq_eg_stm()); + } else if (ss->ttHit) { // Never assume anything about values stored in TT @@ -738,13 +740,13 @@ namespace { if (eval == VALUE_NONE) ss->staticEval = eval = evaluate(pos, &complexity); else // Fall back to (semi)classical complexity for TT hits, the NNUE complexity is lost + { complexity = abs(ss->staticEval - pos.psq_eg_stm()); + if (PvNode) + Eval::NNUE::hint_common_parent_position(pos); + } - // Randomize draw evaluation - if (eval == VALUE_DRAW) - eval = value_draw(thisThread); - - // ttValue can be used as a better position evaluation (~4 Elo) + // ttValue can be used as a better position evaluation (~7 Elo) if ( ttValue != VALUE_NONE && (tte->bound() & (ttValue > eval ? BOUND_LOWER : BOUND_UPPER))) eval = ttValue; @@ -752,18 +754,14 @@ namespace { else { ss->staticEval = eval = evaluate(pos, &complexity); - // Save static evaluation into transposition table - if (!excludedMove) - tte->save(posKey, VALUE_NONE, ss->ttPv, BOUND_NONE, DEPTH_NONE, MOVE_NONE, eval); + tte->save(posKey, VALUE_NONE, ss->ttPv, BOUND_NONE, DEPTH_NONE, MOVE_NONE, eval); } - thisThread->complexityAverage.update(complexity); - - // Use static evaluation difference to improve quiet move ordering (~3 Elo) + // Use static evaluation difference to improve quiet move ordering (~4 Elo) if (is_ok((ss-1)->currentMove) && !(ss-1)->inCheck && !priorCapture) { - int bonus = std::clamp(-16 * int((ss-1)->staticEval + ss->staticEval), -2000, 2000); + int bonus = std::clamp(-19 * int((ss-1)->staticEval + ss->staticEval), -1920, 1920); thisThread->mainHistory[~us][from_to((ss-1)->currentMove)] << bonus; } @@ -773,45 +771,43 @@ namespace { // margin and the improving flag are used in various pruning heuristics. improvement = (ss-2)->staticEval != VALUE_NONE ? ss->staticEval - (ss-2)->staticEval : (ss-4)->staticEval != VALUE_NONE ? ss->staticEval - (ss-4)->staticEval - : 175; + : 156; improving = improvement > 0; - // Step 7. Razoring. + // Step 7. Razoring (~1 Elo). // If eval is really low check with qsearch if it can exceed alpha, if it can't, // return a fail low. - if ( !PvNode - && depth <= 7 - && eval < alpha - 348 - 258 * depth * depth) + if (eval < alpha - 426 - 256 * depth * depth) { value = qsearch(pos, ss, alpha - 1, alpha); if (value < alpha) return value; } - // Step 8. Futility pruning: child node (~25 Elo). + // Step 8. Futility pruning: child node (~40 Elo). // The depth condition is important for mate finding. if ( !ss->ttPv - && depth < 8 - && eval - futility_margin(depth, improving) - (ss-1)->statScore / 256 >= beta + && depth < 9 + && eval - futility_margin(depth, improving) - (ss-1)->statScore / 280 >= beta && eval >= beta - && eval < 26305) // larger than VALUE_KNOWN_WIN, but smaller than TB wins. + && eval < 25128) // larger than VALUE_KNOWN_WIN, but smaller than TB wins return eval; - // Step 9. Null move search with verification search (~22 Elo) + // Step 9. Null move search with verification search (~35 Elo) if ( !PvNode && (ss-1)->currentMove != MOVE_NULL - && (ss-1)->statScore < 14695 + && (ss-1)->statScore < 18755 && eval >= beta && eval >= ss->staticEval - && ss->staticEval >= beta - 15 * depth - improvement / 15 + 201 + complexity / 24 + && ss->staticEval >= beta - 20 * depth - improvement / 13 + 253 + complexity / 25 && !excludedMove && pos.non_pawn_material(us) - && (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor)) + && (ss->ply >= thisThread->nmpMinPly)) { assert(eval - beta >= 0); // Null move dynamic reduction based on depth, eval and complexity of position - Depth R = std::min(int(eval - beta) / 147, 5) + depth / 3 + 4 - (complexity > 650); + Depth R = std::min(int(eval - beta) / 172, 6) + depth / 3 + 4 - (complexity > 825); ss->currentMove = MOVE_NULL; ss->continuationHistory = &thisThread->continuationHistory[0][0][NO_PIECE][0]; @@ -834,9 +830,8 @@ namespace { assert(!thisThread->nmpMinPly); // Recursive verification is not allowed // Do verification search at high depths, with null move pruning disabled - // for us, until ply exceeds nmpMinPly. + // until ply exceeds nmpMinPly. thisThread->nmpMinPly = ss->ply + 3 * (depth-R) / 4; - thisThread->nmpColor = us; Value v = search(pos, ss, beta-1, beta, depth-R, false); @@ -847,10 +842,10 @@ namespace { } } - probCutBeta = beta + 179 - 46 * improving; + probCutBeta = beta + 186 - 54 * improving; - // Step 10. ProbCut (~4 Elo) - // If we have a good enough capture and a reduced search returns a value + // Step 10. ProbCut (~10 Elo) + // If we have a good enough capture (or queen promotion) and a reduced search returns a value // much above beta, we can (almost) safely prune the previous move. if ( !PvNode && depth > 4 @@ -866,12 +861,12 @@ namespace { { assert(probCutBeta < VALUE_INFINITE); - MovePicker mp(pos, ttMove, probCutBeta - ss->staticEval, depth - 3, &captureHistory); + MovePicker mp(pos, ttMove, probCutBeta - ss->staticEval, &captureHistory); while ((move = mp.next_move()) != MOVE_NONE) if (move != excludedMove && pos.legal(move)) { - assert(pos.capture(move) || promotion_type(move) == QUEEN); + assert(pos.capture_stage(move)); ss->currentMove = move; ss->continuationHistory = &thisThread->continuationHistory[ss->inCheck] @@ -897,26 +892,28 @@ namespace { return value; } } + + Eval::NNUE::hint_common_parent_position(pos); } - // Step 11. If the position is not in TT, decrease depth by 3. - // Use qsearch if depth is equal or below zero (~4 Elo) + // Step 11. If the position is not in TT, decrease depth by 2 (or by 4 if the TT entry for the current position was hit and the stored depth is greater than or equal to the current depth). + // Use qsearch if depth is equal or below zero (~9 Elo) if ( PvNode && !ttMove) - depth -= 3; + depth -= 2 + 2 * (ss->ttHit && tte->depth() >= depth); if (depth <= 0) return qsearch(pos, ss, alpha, beta); if ( cutNode - && depth >= 8 + && depth >= 7 && !ttMove) - depth--; + depth -= 2; moves_loop: // When in check, search starts here - // Step 12. A small Probcut idea, when we are in check (~0 Elo) - probCutBeta = beta + 481; + // Step 12. A small Probcut idea, when we are in check (~4 Elo) + probCutBeta = beta + 391; if ( ss->inCheck && !PvNode && depth >= 2 @@ -925,16 +922,14 @@ moves_loop: // When in check, search starts here && tte->depth() >= depth - 3 && ttValue >= probCutBeta && abs(ttValue) <= VALUE_KNOWN_WIN - && abs(beta) <= VALUE_KNOWN_WIN - ) + && abs(beta) <= VALUE_KNOWN_WIN) return probCutBeta; - const PieceToHistory* contHist[] = { (ss-1)->continuationHistory, (ss-2)->continuationHistory, nullptr , (ss-4)->continuationHistory, nullptr , (ss-6)->continuationHistory }; - Move countermove = thisThread->counterMoves[pos.piece_on(prevSq)][prevSq]; + Move countermove = prevSq != SQ_NONE ? thisThread->counterMoves[pos.piece_on(prevSq)][prevSq] : MOVE_NONE; MovePicker mp(pos, ttMove, depth, &thisThread->mainHistory, &captureHistory, @@ -943,7 +938,7 @@ moves_loop: // When in check, search starts here ss->killers); value = bestValue; - moveCountPruning = false; + moveCountPruning = singularQuietLMR = false; // Indicate PvNodes that will probably fail low if the node was searched // at a depth equal or greater than the current depth, and the result of this search was a fail low. @@ -983,7 +978,7 @@ moves_loop: // When in check, search starts here (ss+1)->pv = nullptr; extension = 0; - capture = pos.capture(move); + capture = pos.capture_stage(move); movedPiece = pos.moved_piece(move); givesCheck = pos.gives_check(move); @@ -992,33 +987,53 @@ moves_loop: // When in check, search starts here Value delta = beta - alpha; - // Step 14. Pruning at shallow depth (~98 Elo). Depth conditions are important for mate finding. + Depth r = reduction(improving, depth, moveCount, delta, thisThread->rootDelta); + + // Step 14. Pruning at shallow depth (~120 Elo). Depth conditions are important for mate finding. if ( !rootNode && pos.non_pawn_material(us) && bestValue > VALUE_TB_LOSS_IN_MAX_PLY) { - // Skip quiet moves if movecount exceeds our FutilityMoveCount threshold (~7 Elo) + // Skip quiet moves if movecount exceeds our FutilityMoveCount threshold (~8 Elo) moveCountPruning = moveCount >= futility_move_count(improving, depth); // Reduced depth of the next LMR search - int lmrDepth = std::max(newDepth - reduction(improving, depth, moveCount, delta, thisThread->rootDelta), 0); + int lmrDepth = std::max(newDepth - r, 0); if ( capture || givesCheck) { - // Futility pruning for captures (~0 Elo) - if ( !pos.empty(to_sq(move)) - && !givesCheck - && !PvNode + // Futility pruning for captures (~2 Elo) + if ( !givesCheck && lmrDepth < 6 && !ss->inCheck - && ss->staticEval + 281 + 179 * lmrDepth + PieceValue[EG][pos.piece_on(to_sq(move))] - + captureHistory[movedPiece][to_sq(move)][type_of(pos.piece_on(to_sq(move)))] / 6 < alpha) + && ss->staticEval + 182 + 230 * lmrDepth + PieceValue[EG][pos.piece_on(to_sq(move))] + + captureHistory[movedPiece][to_sq(move)][type_of(pos.piece_on(to_sq(move)))] / 7 < alpha) continue; - // SEE based pruning (~9 Elo) - if (!pos.see_ge(move, Value(-203) * depth)) - continue; + Bitboard occupied; + // SEE based pruning (~11 Elo) + if (!pos.see_ge(move, occupied, Value(-206) * depth)) + { + if (depth < 2 - capture) + continue; + // Don't prune the move if opp. King/Queen/Rook is attacked by a slider after the exchanges. + // Since in see_ge we don't update occupied when the king recaptures, we also don't prune the + // move when the opp. King gets a discovered slider attack DURING the exchanges. + Bitboard leftEnemies = pos.pieces(~us, ROOK, QUEEN, KING) & occupied; + Bitboard attacks = 0; + occupied |= to_sq(move); + while (leftEnemies && !attacks) + { + Square sq = pop_lsb(leftEnemies); + attacks = pos.attackers_to(sq, occupied) & pos.pieces(us) & occupied; + // Exclude Queen/Rook(s) which were already threatened before SEE + if (attacks && sq != pos.square(~us) && (pos.attackers_to(sq, pos.pieces()) & pos.pieces(us))) + attacks = 0; + } + if (!attacks) + continue; + } } else { @@ -1028,34 +1043,39 @@ moves_loop: // When in check, search starts here // Continuation history based pruning (~2 Elo) if ( lmrDepth < 5 - && history < -3875 * (depth - 1)) + && history < -4405 * (depth - 1)) continue; - history += thisThread->mainHistory[us][from_to(move)]; + history += 2 * thisThread->mainHistory[us][from_to(move)]; + + lmrDepth += history / 7278; + lmrDepth = std::max(lmrDepth, -2); - // Futility pruning: parent node (~9 Elo) + // Futility pruning: parent node (~13 Elo) if ( !ss->inCheck - && lmrDepth < 11 - && ss->staticEval + 122 + 138 * lmrDepth + history / 60 <= alpha) + && lmrDepth < 13 + && ss->staticEval + 103 + 138 * lmrDepth <= alpha) continue; - // Prune moves with negative SEE (~3 Elo) - if (!pos.see_ge(move, Value(-25 * lmrDepth * lmrDepth - 20 * lmrDepth))) + lmrDepth = std::max(lmrDepth, 0); + + // Prune moves with negative SEE (~4 Elo) + if (!pos.see_ge(move, Value(-24 * lmrDepth * lmrDepth - 16 * lmrDepth))) continue; } } - // Step 15. Extensions (~66 Elo) + // Step 15. Extensions (~100 Elo) // We take care to not overdo to avoid search getting stuck. if (ss->ply < thisThread->rootDepth * 2) { - // Singular extension search (~58 Elo). If all moves but one fail low on a + // Singular extension search (~94 Elo). 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 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 will extend the ttMove. if ( !rootNode - && depth >= 4 - (thisThread->previousDepth > 27) + 2 * (PvNode && tte->is_pv()) + && depth >= 4 - (thisThread->completedDepth > 21) + 2 * (PvNode && tte->is_pv()) && move == ttMove && !excludedMove // Avoid recursive singular search /* && ttValue != VALUE_NONE Already implicit in the next condition */ @@ -1063,7 +1083,7 @@ moves_loop: // When in check, search starts here && (tte->bound() & BOUND_LOWER) && tte->depth() >= depth - 3) { - Value singularBeta = ttValue - 3 * depth; + Value singularBeta = ttValue - (3 + 2 * (ss->ttPv && !PvNode)) * depth / 2; Depth singularDepth = (depth - 1) / 2; ss->excludedMove = move; @@ -1073,12 +1093,16 @@ moves_loop: // When in check, search starts here if (value < singularBeta) { extension = 1; + singularQuietLMR = !ttCapture; // Avoid search explosion by limiting the number of double extensions if ( !PvNode - && value < singularBeta - 26 - && ss->doubleExtensions <= 8) + && value < singularBeta - 25 + && ss->doubleExtensions <= 10) + { extension = 2; + depth += depth < 13; + } } // Multi-cut pruning @@ -1089,26 +1113,30 @@ moves_loop: // When in check, search starts here else if (singularBeta >= beta) return singularBeta; - // If the eval of ttMove is greater than beta, we reduce it (negative extension) + // If the eval of ttMove is greater than beta, we reduce it (negative extension) (~7 Elo) else if (ttValue >= beta) - extension = -2; + extension = -2 - !PvNode; + + // If the eval of ttMove is less than value, we reduce it (negative extension) (~1 Elo) + else if (ttValue <= value) + extension = -1; - // If the eval of ttMove is less than alpha and value, we reduce it (negative extension) - else if (ttValue <= alpha && ttValue <= value) + // If the eval of ttMove is less than alpha, we reduce it (negative extension) (~1 Elo) + else if (ttValue <= alpha) extension = -1; } // Check extensions (~1 Elo) else if ( givesCheck - && depth > 9 - && abs(ss->staticEval) > 71) + && depth > 10 + && abs(ss->staticEval) > 88) extension = 1; - // Quiet ttMove extensions (~0 Elo) + // Quiet ttMove extensions (~1 Elo) else if ( PvNode && move == ttMove && move == ss->killers[0] - && (*contHist[0])[movedPiece][to_sq(move)] >= 5491) + && (*contHist[0])[movedPiece][to_sq(move)] >= 5705) extension = 1; } @@ -1129,55 +1157,60 @@ moves_loop: // When in check, search starts here // Step 16. Make the move pos.do_move(move, st, givesCheck); - bool doDeeperSearch = false; + // Decrease reduction if position is or has been on the PV + // and node is not likely to fail low. (~3 Elo) + if ( ss->ttPv + && !likelyFailLow) + r -= 2; - // Step 17. Late moves reduction / extension (LMR, ~98 Elo) - // We use various heuristics for the sons of a node after the first son has - // been searched. In general we would like to reduce them, but there are many - // cases where we extend a son if it has good chances to be "interesting". - if ( depth >= 2 - && moveCount > 1 + (PvNode && ss->ply <= 1) - && ( !ss->ttPv - || !capture - || (cutNode && (ss-1)->moveCount > 1))) - { - Depth r = reduction(improving, depth, moveCount, delta, thisThread->rootDelta); + // Decrease reduction if opponent's move count is high (~1 Elo) + if ((ss-1)->moveCount > 7) + r--; - // Decrease reduction if position is or has been on the PV - // and node is not likely to fail low. (~3 Elo) - if ( ss->ttPv - && !likelyFailLow) - r -= 2; + // Increase reduction for cut nodes (~3 Elo) + if (cutNode) + r += 2; - // Decrease reduction if opponent's move count is high (~1 Elo) - if ((ss-1)->moveCount > 7) - r--; + // Increase reduction if ttMove is a capture (~3 Elo) + if (ttCapture) + r++; - // Increase reduction for cut nodes (~3 Elo) - if (cutNode && move != ss->killers[0]) - r += 2; + // Decrease reduction for PvNodes based on depth (~2 Elo) + if (PvNode) + r -= 1 + 12 / (3 + depth); - // Increase reduction if ttMove is a capture (~3 Elo) - if (ttCapture) - r++; + // Decrease reduction if ttMove has been singularly extended (~1 Elo) + if (singularQuietLMR) + r--; - // Decrease reduction for PvNodes based on depth - if (PvNode) - r -= 1 + 15 / (3 + depth); + // Increase reduction if next ply has a lot of fail high (~5 Elo) + if ((ss+1)->cutoffCnt > 3) + r++; - // Increase reduction if next ply has a lot of fail high else reset count to 0 - if ((ss+1)->cutoffCnt > 3 && !PvNode) - r++; + // Decrease reduction if move is a killer and we have a good history (~1 Elo) + if (move == ss->killers[0] + && (*contHist[0])[movedPiece][to_sq(move)] >= 3722) + r--; - ss->statScore = thisThread->mainHistory[us][from_to(move)] - + (*contHist[0])[movedPiece][to_sq(move)] - + (*contHist[1])[movedPiece][to_sq(move)] - + (*contHist[3])[movedPiece][to_sq(move)] - - 4334; + ss->statScore = 2 * thisThread->mainHistory[us][from_to(move)] + + (*contHist[0])[movedPiece][to_sq(move)] + + (*contHist[1])[movedPiece][to_sq(move)] + + (*contHist[3])[movedPiece][to_sq(move)] + - 4082; - // Decrease/increase reduction for moves with a good/bad history (~30 Elo) - r -= ss->statScore / 15914; + // Decrease/increase reduction for moves with a good/bad history (~25 Elo) + r -= ss->statScore / (11079 + 4626 * (depth > 6 && depth < 19)); + // Step 17. Late moves reduction / extension (LMR, ~117 Elo) + // We use various heuristics for the sons of a node after the first son has + // been searched. In general we would like to reduce them, but there are many + // cases where we extend a son if it has good chances to be "interesting". + if ( depth >= 2 + && moveCount > 1 + (PvNode && ss->ply <= 1) + && ( !ss->ttPv + || !capture + || (cutNode && (ss-1)->moveCount > 1))) + { // In general we want to cap the LMR depth search at newDepth, but when // reduction is negative, we allow this move a limited search extension // beyond the first move depth. This may lead to hidden double extensions. @@ -1185,35 +1218,39 @@ moves_loop: // When in check, search starts here value = -search(pos, ss+1, -(alpha+1), -alpha, d, true); - // If the son is reduced and fails high it will be re-searched at full depth - doFullDepthSearch = value > alpha && d < newDepth; - doDeeperSearch = value > (alpha + 78 + 11 * (newDepth - d)); - didLMR = true; - } - else - { - doFullDepthSearch = !PvNode || moveCount > 1; - didLMR = false; - } + // Do full depth search when reduced LMR search fails high + if (value > alpha && d < newDepth) + { + // Adjust full depth search based on LMR results - if result + // was good enough search deeper, if it was bad enough search shallower + const bool doDeeperSearch = value > (alpha + 58 + 12 * (newDepth - d)); + const bool doEvenDeeperSearch = value > alpha + 588 && ss->doubleExtensions <= 5; + const bool doShallowerSearch = value < bestValue + newDepth; - // Step 18. Full depth search when LMR is skipped or fails high - if (doFullDepthSearch) - { - value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth + doDeeperSearch, !cutNode); + ss->doubleExtensions = ss->doubleExtensions + doEvenDeeperSearch; + + newDepth += doDeeperSearch - doShallowerSearch + doEvenDeeperSearch; + + if (newDepth > d) + value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode); - // If the move passed LMR update its stats - if (didLMR) - { int bonus = value > alpha ? stat_bonus(newDepth) : -stat_bonus(newDepth); - if (capture) - bonus /= 6; - update_continuation_histories(ss, movedPiece, to_sq(move), bonus); } } + // Step 18. Full depth search when LMR is skipped. If expected reduction is high, reduce its depth by 1. + else if (!PvNode || moveCount > 1) + { + // Increase reduction for cut nodes and not ttMove (~1 Elo) + if (!ttMove && cutNode) + r += 2; + + value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth - (r > 4), !cutNode); + } + // For PV nodes only, do a full PV search on the first move or after a fail // high (in the latter case search only if value < beta), otherwise let the // parent node fail low with value <= alpha and try another move. @@ -1222,8 +1259,10 @@ moves_loop: // When in check, search starts here (ss+1)->pv = pv; (ss+1)->pv[0] = MOVE_NONE; - value = -search(pos, ss+1, -beta, -alpha, - std::min(maxNextDepth, newDepth), false); + value = -search(pos, ss+1, -beta, -alpha, newDepth, false); + + if (moveCount > 1 && newDepth >= depth && !capture) + update_continuation_histories(ss, movedPiece, to_sq(move), -stat_bonus(newDepth)); } // Step 19. Undo move @@ -1248,8 +1287,21 @@ moves_loop: // When in check, search starts here // PV move or new best move? if (moveCount == 1 || value > alpha) { - rm.score = value; + rm.score = rm.uciScore = value; rm.selDepth = thisThread->selDepth; + rm.scoreLowerbound = rm.scoreUpperbound = false; + + if (value >= beta) + { + rm.scoreLowerbound = true; + rm.uciScore = beta; + } + else if (value <= alpha) + { + rm.scoreUpperbound = true; + rm.uciScore = alpha; + } + rm.pv.resize(1); assert((ss+1)->pv); @@ -1284,16 +1336,17 @@ moves_loop: // When in check, search starts here if (PvNode && value < beta) // Update alpha! Always alpha < beta { - alpha = value; - - // Reduce other moves if we have found at least one score improvement - if ( depth > 2 - && depth < 7 - && beta < VALUE_KNOWN_WIN - && alpha > -VALUE_KNOWN_WIN) - depth -= 1; + // Reduce other moves if we have found at least one score improvement (~1 Elo) + if ( depth > 1 + && ( (improving && complexity > 971) + || value < (5 * alpha + 75 * beta) / 87 + || depth < 6) + && beta < 12535 + && value > -12535) + depth -= 1; assert(depth > 0); + alpha = value; } else { @@ -1303,8 +1356,6 @@ moves_loop: // When in check, search starts here } } } - else - ss->cutoffCnt = 0; // If the move is worse than some previously searched move, remember it to update its stats later @@ -1344,23 +1395,17 @@ moves_loop: // When in check, search starts here quietsSearched, quietCount, capturesSearched, captureCount, depth); // Bonus for prior countermove that caused the fail low - else if ( (depth >= 4 || PvNode) - && !priorCapture) + else if (!priorCapture && prevSq != SQ_NONE) { - //Assign extra bonus if current node is PvNode or cutNode - //or fail low was really bad - bool extraBonus = PvNode - || cutNode - || bestValue < alpha - 70 * depth; - - update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, stat_bonus(depth) * (1 + extraBonus)); + int bonus = (depth > 5) + (PvNode || cutNode) + (bestValue < alpha - 97 * depth) + ((ss-1)->moveCount > 10); + update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, stat_bonus(depth) * bonus); } if (PvNode) bestValue = std::min(bestValue, maxValue); // If no good move is found and the previous position was ttPv, then the previous - // opponent move is probably good and the new position is added to the search tree. + // opponent move is probably good and the new position is added to the search tree. (~7 Elo) if (bestValue <= alpha) ss->ttPv = ss->ttPv || ((ss-1)->ttPv && depth > 3); @@ -1379,7 +1424,7 @@ moves_loop: // When in check, search starts here // qsearch() is the quiescence search function, which is called by the main search // function with zero depth, or recursively with further decreasing depth per call. - // (~155 elo) + // (~155 Elo) template Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) { @@ -1402,6 +1447,7 @@ moves_loop: // When in check, search starts here bool pvHit, givesCheck, capture; int moveCount; + // Step 1. Initialize node if (PvNode) { (ss+1)->pv = pv; @@ -1413,7 +1459,7 @@ moves_loop: // When in check, search starts here ss->inCheck = pos.checkers(); moveCount = 0; - // Check for an immediate draw or maximum ply reached + // Step 2. Check for an immediate draw or maximum ply reached if ( pos.is_draw(ss->ply) || ss->ply >= MAX_PLY) return (ss->ply >= MAX_PLY && !ss->inCheck) ? evaluate(pos) : VALUE_DRAW; @@ -1424,14 +1470,16 @@ moves_loop: // When in check, search starts here // 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 = ss->inCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS - : DEPTH_QS_NO_CHECKS; - // Transposition table lookup + : DEPTH_QS_NO_CHECKS; + + // Step 3. Transposition table lookup posKey = pos.key(); tte = TT.probe(posKey, ss->ttHit); ttValue = ss->ttHit ? value_from_tt(tte->value(), ss->ply, pos.rule50_count()) : VALUE_NONE; ttMove = ss->ttHit ? tte->move() : MOVE_NONE; pvHit = ss->ttHit && tte->is_pv(); + // At non-PV nodes we check for an early TT cutoff if ( !PvNode && ss->ttHit && tte->depth() >= ttDepth @@ -1439,7 +1487,7 @@ moves_loop: // When in check, search starts here && (tte->bound() & (ttValue >= beta ? BOUND_LOWER : BOUND_UPPER))) return ttValue; - // Evaluate the position statically + // Step 4. Static evaluation of the position if (ss->inCheck) { ss->staticEval = VALUE_NONE; @@ -1453,7 +1501,7 @@ moves_loop: // When in check, search starts here if ((ss->staticEval = bestValue = tte->eval()) == VALUE_NONE) ss->staticEval = bestValue = evaluate(pos); - // ttValue can be used as a better position evaluation (~7 Elo) + // ttValue can be used as a better position evaluation (~13 Elo) if ( ttValue != VALUE_NONE && (tte->bound() & (ttValue > bestValue ? BOUND_LOWER : BOUND_UPPER))) bestValue = ttValue; @@ -1478,7 +1526,7 @@ moves_loop: // When in check, search starts here if (PvNode && bestValue > alpha) alpha = bestValue; - futilityBase = bestValue + 118; + futilityBase = bestValue + 168; } const PieceToHistory* contHist[] = { (ss-1)->continuationHistory, (ss-2)->continuationHistory, @@ -1489,7 +1537,7 @@ moves_loop: // When in check, search starts here // to search the moves. Because the depth is <= 0 here, only captures, // queen promotions, and other checks (only if depth >= DEPTH_QS_CHECKS) // will be generated. - Square prevSq = to_sq((ss-1)->currentMove); + Square prevSq = (ss-1)->currentMove != MOVE_NULL ? to_sq((ss-1)->currentMove) : SQ_NONE; MovePicker mp(pos, ttMove, depth, &thisThread->mainHistory, &thisThread->captureHistory, contHist, @@ -1497,7 +1545,8 @@ moves_loop: // When in check, search starts here int quietCheckEvasions = 0; - // Loop through the moves until no moves remain or a beta cutoff occurs + // Step 5. Loop through all pseudo-legal moves until no moves remain + // or a beta cutoff occurs. while ((move = mp.next_move()) != MOVE_NONE) { assert(is_ok(move)); @@ -1507,18 +1556,19 @@ moves_loop: // When in check, search starts here continue; givesCheck = pos.gives_check(move); - capture = pos.capture(move); + capture = pos.capture_stage(move); moveCount++; - // Futility pruning and moveCount pruning (~5 Elo) - if ( bestValue > VALUE_TB_LOSS_IN_MAX_PLY - && !givesCheck + // Step 6. Pruning. + if (bestValue > VALUE_TB_LOSS_IN_MAX_PLY) + { + // Futility pruning and moveCount pruning (~10 Elo) + if ( !givesCheck && to_sq(move) != prevSq && futilityBase > -VALUE_KNOWN_WIN && type_of(move) != PROMOTION) { - if (moveCount > 2) continue; @@ -1537,44 +1587,42 @@ moves_loop: // When in check, search starts here } } - // Do not search moves with negative SEE values (~5 Elo) - if ( bestValue > VALUE_TB_LOSS_IN_MAX_PLY - && !pos.see_ge(move)) + // We prune after 2nd quiet check evasion where being 'in check' is implicitly checked through the counter + // and being a 'quiet' apart from being a tt move is assumed after an increment because captures are pushed ahead. + if (quietCheckEvasions > 1) + break; + + // Continuation history based pruning (~3 Elo) + if ( !capture + && (*contHist[0])[pos.moved_piece(move)][to_sq(move)] < 0 + && (*contHist[1])[pos.moved_piece(move)][to_sq(move)] < 0) + continue; + + // Do not search moves with bad enough SEE values (~5 Elo) + if (!pos.see_ge(move, Value(-110))) continue; + } // Speculative prefetch as early as possible prefetch(TT.first_entry(pos.key_after(move))); + // Update the current move ss->currentMove = move; ss->continuationHistory = &thisThread->continuationHistory[ss->inCheck] [capture] [pos.moved_piece(move)] [to_sq(move)]; - // Continuation history based pruning (~2 Elo) - if ( !capture - && bestValue > VALUE_TB_LOSS_IN_MAX_PLY - && (*contHist[0])[pos.moved_piece(move)][to_sq(move)] < CounterMovePruneThreshold - && (*contHist[1])[pos.moved_piece(move)][to_sq(move)] < CounterMovePruneThreshold) - continue; - - // movecount pruning for quiet check evasions - if ( bestValue > VALUE_TB_LOSS_IN_MAX_PLY - && quietCheckEvasions > 1 - && !capture - && ss->inCheck) - continue; - quietCheckEvasions += !capture && ss->inCheck; - // Make and search the move + // Step 7. Make and search the move pos.do_move(move, st, givesCheck); value = -qsearch(pos, ss+1, -beta, -alpha, depth - 1); pos.undo_move(move); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); - // Check for a new best move + // Step 8. Check for a new best move if (value > bestValue) { bestValue = value; @@ -1594,6 +1642,7 @@ moves_loop: // When in check, search starts here } } + // Step 9. Check for mate // All legal moves have been searched. A special case: if we're in check // and no legal moves were found, it is checkmate. if (ss->inCheck && bestValue == -VALUE_INFINITE) @@ -1677,13 +1726,14 @@ moves_loop: // When in check, search starts here Thread* thisThread = pos.this_thread(); CapturePieceToHistory& captureHistory = thisThread->captureHistory; Piece moved_piece = pos.moved_piece(bestMove); - PieceType captured = type_of(pos.piece_on(to_sq(bestMove))); + PieceType captured; + int bonus1 = stat_bonus(depth + 1); - if (!pos.capture(bestMove)) + if (!pos.capture_stage(bestMove)) { - int bonus2 = bestValue > beta + PawnValueMg ? bonus1 // larger bonus - : stat_bonus(depth); // smaller bonus + int bonus2 = bestValue > beta + 153 ? bonus1 // larger bonus + : stat_bonus(depth); // smaller bonus // Increase stats for the best move in case it was a quiet move update_quiet_stats(pos, ss, bestMove, bonus2); @@ -1696,12 +1746,16 @@ moves_loop: // When in check, search starts here } } else + { // Increase stats for the best move in case it was a capture move + captured = type_of(pos.piece_on(to_sq(bestMove))); captureHistory[moved_piece][to_sq(bestMove)][captured] << bonus1; + } // Extra penalty for a quiet early move that was not a TT move or // main killer move in previous ply when it gets refuted. - if ( ((ss-1)->moveCount == 1 + (ss-1)->ttHit || ((ss-1)->currentMove == (ss-1)->killers[0])) + if ( prevSq != SQ_NONE + && ((ss-1)->moveCount == 1 + (ss-1)->ttHit || ((ss-1)->currentMove == (ss-1)->killers[0])) && !pos.captured_piece()) update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -bonus1); @@ -1827,7 +1881,7 @@ void MainThread::check_time() { /// 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. -string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) { +string UCI::pv(const Position& pos, Depth depth) { std::stringstream ss; TimePoint elapsed = Time.elapsed() + 1; @@ -1845,7 +1899,7 @@ string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) { continue; Depth d = updated ? depth : std::max(1, depth - 1); - Value v = updated ? rootMoves[i].score : rootMoves[i].previousScore; + Value v = updated ? rootMoves[i].uciScore : rootMoves[i].previousScore; if (v == -VALUE_INFINITE) v = VALUE_ZERO; @@ -1865,16 +1919,13 @@ string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) { if (Options["UCI_ShowWDL"]) ss << UCI::wdl(v, pos.game_ply()); - if (!tb && i == pvIdx) - ss << (v >= beta ? " lowerbound" : v <= alpha ? " upperbound" : ""); + if (i == pvIdx && !tb && updated) // tablebase- and previous-scores are exact + ss << (rootMoves[i].scoreLowerbound ? " lowerbound" : (rootMoves[i].scoreUpperbound ? " upperbound" : "")); ss << " nodes " << nodesSearched - << " nps " << nodesSearched * 1000 / elapsed; - - if (elapsed > 1000) // Earlier makes little sense - ss << " hashfull " << TT.hashfull(); - - ss << " tbhits " << tbHits + << " nps " << nodesSearched * 1000 / elapsed + << " hashfull " << TT.hashfull() + << " tbhits " << tbHits << " time " << elapsed << " pv";