X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fsearch.cpp;h=c748f1ff4251424b91fb1b8f8b6db5a87057502b;hb=d4d1cec29631f041adeec98adc5893b5c6a54969;hp=7f2f5284728dca81095814ac34052462864bd747;hpb=c2d507005c51145211a7963af7c41026bd759d08;p=stockfish diff --git a/src/search.cpp b/src/search.cpp index 7f2f5284..c748f1ff 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 @@ -63,7 +63,7 @@ namespace { // Futility margin Value futility_margin(Depth d, bool improving) { - return Value(165 * (d - improving)); + return Value(158 * (d - improving)); } // Reductions lookup table, initialized at startup @@ -71,7 +71,7 @@ namespace { Depth reduction(bool i, Depth d, int mn, Value delta, Value rootDelta) { int r = Reductions[d] * Reductions[mn]; - return (r + 1642 - int(delta) * 1024 / int(rootDelta)) / 1024 + (!i && r > 916); + return (r + 1460 - int(delta) * 1024 / int(rootDelta)) / 1024 + (!i && r > 937); } constexpr int futility_move_count(bool improving, Depth depth) { @@ -81,7 +81,7 @@ namespace { // History and stats update bonus, based on depth int stat_bonus(Depth d) { - return std::min((12 * d + 282) * d - 349 , 1480); + return std::min(350 * d - 400, 1650); } // Add a small random component to draw evaluations to avoid 3-fold blindness @@ -96,7 +96,10 @@ 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); } @@ -239,9 +242,6 @@ 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) << sync_endl; @@ -276,8 +276,11 @@ 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; @@ -307,7 +310,7 @@ void Thread::search() { multiPV = std::min(multiPV, rootMoves.size()); - complexityAverage.set(155, 1); + complexityAverage.set(153, 1); optimism[us] = optimism[~us] = VALUE_ZERO; @@ -351,12 +354,12 @@ void Thread::search() { if (rootDepth >= 4) { Value prev = rootMoves[pvIdx].averageScore; - delta = Value(10) + int(prev) * prev / 15620; + delta = Value(10) + int(prev) * prev / 15400; alpha = std::max(prev - delta,-VALUE_INFINITE); beta = std::min(prev + delta, VALUE_INFINITE); // Adjust optimism based on root move's previousScore - int opt = 118 * prev / (std::abs(prev) + 169); + int opt = 116 * prev / (std::abs(prev) + 170); optimism[ us] = Value(opt); optimism[~us] = -optimism[us]; } @@ -633,16 +636,16 @@ namespace { && 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) + // Extra penalty for early quiet moves of the previous ply (~0 Elo on STC, ~2 Elo on LTC) if ((ss-1)->moveCount <= 2 && !priorCapture) update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + 1)); } @@ -734,7 +737,7 @@ namespace { else // Fall back to (semi)classical complexity for TT hits, the NNUE complexity is lost complexity = abs(ss->staticEval - pos.psq_eg_stm()); - // 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; @@ -750,10 +753,10 @@ namespace { 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(-19 * int((ss-1)->staticEval + ss->staticEval), -1914, 1914); + int bonus = std::clamp(-19 * int((ss-1)->staticEval + ss->staticEval), -1940, 1940); thisThread->mainHistory[~us][from_to((ss-1)->currentMove)] << bonus; } @@ -763,35 +766,35 @@ 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 - : 168; + : 172; 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 (eval < alpha - 369 - 254 * depth * depth) + if (eval < alpha - 394 - 255 * 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 / 303 >= beta + && eval - futility_margin(depth, improving) - (ss-1)->statScore / 304 >= beta && eval >= beta - && eval < 28031) // larger than VALUE_KNOWN_WIN, but smaller than TB wins + && eval < 28580) // 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 < 17139 + && (ss-1)->statScore < 18200 && eval >= beta && eval >= ss->staticEval - && ss->staticEval >= beta - 20 * depth - improvement / 13 + 233 + complexity / 25 + && ss->staticEval >= beta - 20 * depth - improvement / 14 + 235 + complexity / 24 && !excludedMove && pos.non_pawn_material(us) && (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor)) @@ -799,7 +802,7 @@ namespace { assert(eval - beta >= 0); // Null move dynamic reduction based on depth, eval and complexity of position - Depth R = std::min(int(eval - beta) / 168, 7) + depth / 3 + 4 - (complexity > 861); + Depth R = std::min(int(eval - beta) / 165, 6) + depth / 3 + 4 - (complexity > 800); ss->currentMove = MOVE_NULL; ss->continuationHistory = &thisThread->continuationHistory[0][0][NO_PIECE][0]; @@ -835,9 +838,9 @@ namespace { } } - probCutBeta = beta + 191 - 54 * improving; + probCutBeta = beta + 180 - 54 * improving; - // Step 10. ProbCut (~4 Elo) + // Step 10. ProbCut (~10 Elo) // If we have a good enough capture and a reduced search returns a value // much above beta, we can (almost) safely prune the previous move. if ( !PvNode @@ -888,7 +891,7 @@ namespace { } // Step 11. If the position is not in TT, decrease depth by 3. - // Use qsearch if depth is equal or below zero (~4 Elo) + // Use qsearch if depth is equal or below zero (~9 Elo) if ( PvNode && !ttMove) depth -= 3; @@ -903,8 +906,8 @@ namespace { moves_loop: // When in check, search starts here - // Step 12. A small Probcut idea, when we are in check (~0 Elo) - probCutBeta = beta + 417; + // Step 12. A small Probcut idea, when we are in check (~4 Elo) + probCutBeta = beta + 402; if ( ss->inCheck && !PvNode && depth >= 2 @@ -980,12 +983,12 @@ 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. + // 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 @@ -994,17 +997,17 @@ moves_loop: // When in check, search starts here if ( capture || givesCheck) { - // Futility pruning for captures (~0 Elo) + // Futility pruning for captures (~2 Elo) if ( !givesCheck && !PvNode && lmrDepth < 7 && !ss->inCheck - && ss->staticEval + 180 + 201 * lmrDepth + PieceValue[EG][pos.piece_on(to_sq(move))] + && ss->staticEval + 185 + 203 * lmrDepth + PieceValue[EG][pos.piece_on(to_sq(move))] + captureHistory[movedPiece][to_sq(move)][type_of(pos.piece_on(to_sq(move)))] / 6 < alpha) continue; - // SEE based pruning (~9 Elo) - if (!pos.see_ge(move, Value(-222) * depth)) + // SEE based pruning (~11 Elo) + if (!pos.see_ge(move, Value(-220) * depth)) continue; } else @@ -1015,34 +1018,39 @@ moves_loop: // When in check, search starts here // Continuation history based pruning (~2 Elo) if ( lmrDepth < 5 - && history < -3875 * (depth - 1)) + && history < -4180 * (depth - 1)) continue; history += 2 * thisThread->mainHistory[us][from_to(move)]; - // Futility pruning: parent node (~9 Elo) + lmrDepth += history / 7208; + lmrDepth = std::max(lmrDepth, -2); + + // Futility pruning: parent node (~13 Elo) if ( !ss->inCheck && lmrDepth < 13 - && ss->staticEval + 106 + 145 * lmrDepth + history / 52 <= alpha) + && ss->staticEval + 103 + 136 * lmrDepth <= alpha) continue; - // Prune moves with negative SEE (~3 Elo) - if (!pos.see_ge(move, Value(-24 * lmrDepth * lmrDepth - 15 * lmrDepth))) + lmrDepth = std::max(lmrDepth, 0); + + // Prune moves with negative SEE (~4 Elo) + if (!pos.see_ge(move, Value(-25 * 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 > 24) + 2 * (PvNode && tte->is_pv()) + && depth >= 4 - (thisThread->completedDepth > 22) + 2 * (PvNode && tte->is_pv()) && move == ttMove && !excludedMove // Avoid recursive singular search /* && ttValue != VALUE_NONE Already implicit in the next condition */ @@ -1092,14 +1100,14 @@ moves_loop: // When in check, search starts here // Check extensions (~1 Elo) else if ( givesCheck && depth > 9 - && abs(ss->staticEval) > 82) + && abs(ss->staticEval) > 78) 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)] >= 5177) + && (*contHist[0])[movedPiece][to_sq(move)] >= 5600) extension = 1; } @@ -1161,12 +1169,12 @@ moves_loop: // When in check, search starts here + (*contHist[0])[movedPiece][to_sq(move)] + (*contHist[1])[movedPiece][to_sq(move)] + (*contHist[3])[movedPiece][to_sq(move)] - - 4433; + - 4467; // Decrease/increase reduction for moves with a good/bad history (~30 Elo) - r -= ss->statScore / (13000 + 4152 * (depth > 7 && depth < 19)); + r -= ss->statScore / (12800 + 4410 * (depth > 7 && depth < 19)); - // Step 17. Late moves reduction / extension (LMR, ~98 Elo) + // 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". @@ -1188,7 +1196,7 @@ moves_loop: // When in check, search starts here { // 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 + 64 + 11 * (newDepth - d)); + const bool doDeeperSearch = value > (alpha + 66 + 11 * (newDepth - d)); const bool doEvenDeeperSearch = value > alpha + 582 && ss->doubleExtensions <= 5; const bool doShallowerSearch = value < bestValue + newDepth; @@ -1212,6 +1220,10 @@ moves_loop: // When in check, search starts here // 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); } @@ -1353,16 +1365,12 @@ 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 >= 5 || PvNode) + else if ( (depth >= 5 || PvNode || bestValue < alpha - 65 * depth) && !priorCapture) { - //Assign extra bonus if current node is PvNode or cutNode - //or fail low was really bad - bool extraBonus = PvNode - || cutNode - || bestValue < alpha - 62 * depth; - - update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, stat_bonus(depth) * (1 + extraBonus)); + // Extra bonuses for PV/Cut nodes or bad fail lows + int bonus = 1 + (PvNode || cutNode) + (bestValue < alpha - 88 * depth); + update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, stat_bonus(depth) * bonus); } if (PvNode) @@ -1462,7 +1470,7 @@ 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; @@ -1487,7 +1495,7 @@ moves_loop: // When in check, search starts here if (PvNode && bestValue > alpha) alpha = bestValue; - futilityBase = bestValue + 153; + futilityBase = bestValue + 158; } const PieceToHistory* contHist[] = { (ss-1)->continuationHistory, (ss-2)->continuationHistory, @@ -1520,7 +1528,7 @@ moves_loop: // When in check, search starts here moveCount++; - // Futility pruning and moveCount pruning (~5 Elo) + // Futility pruning and moveCount pruning (~10 Elo) if ( bestValue > VALUE_TB_LOSS_IN_MAX_PLY && !givesCheck && to_sq(move) != prevSq @@ -1559,7 +1567,7 @@ moves_loop: // When in check, search starts here [pos.moved_piece(move)] [to_sq(move)]; - // Continuation history based pruning (~2 Elo) + // Continuation history based pruning (~3 Elo) if ( !capture && bestValue > VALUE_TB_LOSS_IN_MAX_PLY && (*contHist[0])[pos.moved_piece(move)][to_sq(move)] < 0 @@ -1689,7 +1697,7 @@ moves_loop: // When in check, search starts here if (!pos.capture(bestMove)) { - int bonus2 = bestValue > beta + 137 ? bonus1 // larger bonus + int bonus2 = bestValue > beta + 146 ? bonus1 // larger bonus : stat_bonus(depth); // smaller bonus // Increase stats for the best move in case it was a quiet move