X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=7c839dfc89f52ec62d33b0ae98ac8654688e4759;hp=17ccab9251abb052a12c7e1b6a41ef8db75f5e4f;hb=1c0b7bdf4f77b8160cebe8af96b28230e870a136;hpb=d89730d5c8dcf10eb9e1d91a81f903d9fc3c949a diff --git a/src/search.cpp b/src/search.cpp index 17ccab92..7c839dfc 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -1,8 +1,6 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 - Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad - Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad + Copyright (C) 2004-2020 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 @@ -65,9 +63,9 @@ namespace { constexpr uint64_t TtHitAverageResolution = 1024; // Razor and futility margins - constexpr int RazorMargin = 527; + constexpr int RazorMargin = 510; Value futility_margin(Depth d, bool improving) { - return Value(227 * (d - improving)); + return Value(223 * (d - improving)); } // Reductions lookup table, initialized at startup @@ -75,7 +73,7 @@ namespace { Depth reduction(bool i, Depth d, int mn) { int r = Reductions[d] * Reductions[mn]; - return (r + 570) / 1024 + (!i && r > 1018); + return (r + 509) / 1024 + (!i && r > 894); } constexpr int futility_move_count(bool improving, Depth depth) { @@ -84,7 +82,7 @@ namespace { // History and stats update bonus, based on depth int stat_bonus(Depth d) { - return d > 15 ? 27 : 17 * d * d + 133 * d - 134; + return d > 13 ? 29 : 17 * d * d + 134 * d - 134; } // Add a small random component to draw evaluations to avoid 3fold-blindness @@ -194,7 +192,7 @@ namespace { void Search::init() { for (int i = 1; i < MAX_MOVES; ++i) - Reductions[i] = int((24.8 + std::log(Threads.size())) * std::log(i)); + Reductions[i] = int((22.0 + std::log(Threads.size())) * std::log(i)); } @@ -227,6 +225,8 @@ void MainThread::search() { Time.init(Limits, us, rootPos.game_ply()); TT.new_search(); + Eval::verify_NNUE(); + if (rootMoves.empty()) { rootMoves.emplace_back(MOVE_NONE); @@ -403,12 +403,12 @@ void Thread::search() { if (rootDepth >= 4) { Value prev = rootMoves[pvIdx].previousScore; - delta = Value(19); + delta = Value(17); alpha = std::max(prev - delta,-VALUE_INFINITE); beta = std::min(prev + delta, VALUE_INFINITE); // Adjust contempt based on root move's previousScore (dynamic contempt) - int dct = ct + (110 - ct / 2) * prev / (abs(prev) + 140); + int dct = ct + (105 - ct / 2) * prev / (abs(prev) + 149); contempt = (us == WHITE ? make_score(dct, dct / 2) : -make_score(dct, dct / 2)); @@ -506,13 +506,13 @@ void Thread::search() { && !Threads.stop && !mainThread->stopOnPonderhit) { - double fallingEval = (296 + 6 * (mainThread->bestPreviousScore - bestValue) - + 6 * (mainThread->iterValue[iterIdx] - bestValue)) / 725.0; + double fallingEval = (318 + 6 * (mainThread->bestPreviousScore - bestValue) + + 6 * (mainThread->iterValue[iterIdx] - bestValue)) / 825.0; fallingEval = Utility::clamp(fallingEval, 0.5, 1.5); // If the bestMove is stable over several iterations, reduce time accordingly - timeReduction = lastBestMoveDepth + 10 < completedDepth ? 1.92 : 0.95; - double reduction = (1.47 + mainThread->previousTimeReduction) / (2.22 * timeReduction); + timeReduction = lastBestMoveDepth + 9 < completedDepth ? 1.92 : 0.95; + double reduction = (1.47 + mainThread->previousTimeReduction) / (2.32 * timeReduction); // Use part of the gained time from a previous stable move for the current move for (Thread* th : Threads) @@ -537,7 +537,7 @@ void Thread::search() { } else if ( Threads.increaseDepth && !mainThread->ponder - && Time.elapsed() > totalTime * 0.56) + && Time.elapsed() > totalTime * 0.58) Threads.increaseDepth = false; else Threads.increaseDepth = true; @@ -596,7 +596,7 @@ namespace { Key posKey; Move ttMove, move, excludedMove, bestMove; Depth extension, newDepth; - Value bestValue, value, ttValue, eval, maxValue, probcutBeta; + Value bestValue, value, ttValue, eval, maxValue, probCutBeta; bool ttHit, ttPv, formerPv, givesCheck, improving, didLMR, priorCapture; bool captureOrPromotion, doFullDepthSearch, moveCountPruning, ttCapture, singularQuietLMR; @@ -794,11 +794,7 @@ namespace { else { if ((ss-1)->currentMove != MOVE_NULL) - { - int bonus = -(ss-1)->statScore / 512; - - ss->staticEval = eval = evaluate(pos) + bonus; - } + ss->staticEval = eval = evaluate(pos); else ss->staticEval = eval = -(ss-1)->staticEval + 2 * Tempo; @@ -816,7 +812,7 @@ namespace { // Step 8. Futility pruning: child node (~50 Elo) if ( !PvNode - && depth < 6 + && depth < 8 && eval - futility_margin(depth, improving) >= beta && eval < VALUE_KNOWN_WIN) // Do not return unproven wins return eval; @@ -824,10 +820,10 @@ namespace { // Step 9. Null move search with verification search (~40 Elo) if ( !PvNode && (ss-1)->currentMove != MOVE_NULL - && (ss-1)->statScore < 23824 + && (ss-1)->statScore < 22977 && eval >= beta && eval >= ss->staticEval - && ss->staticEval >= beta - 33 * depth - 33 * improving + 112 * ttPv + 311 + && ss->staticEval >= beta - 30 * depth - 28 * improving + 84 * ttPv + 182 && !excludedMove && pos.non_pawn_material(us) && (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor)) @@ -835,7 +831,7 @@ namespace { assert(eval - beta >= 0); // Null move dynamic reduction based on depth and value - Depth R = (737 + 77 * depth) / 246 + std::min(int(eval - beta) / 192, 3); + Depth R = (817 + 71 * depth) / 213 + std::min(int(eval - beta) / 192, 3); ss->currentMove = MOVE_NULL; ss->continuationHistory = &thisThread->continuationHistory[0][0][NO_PIECE][0]; @@ -871,7 +867,7 @@ namespace { } } - probcutBeta = beta + 176 - 49 * improving; + probCutBeta = beta + 176 - 49 * improving; // Step 10. ProbCut (~10 Elo) // If we have a good enough capture and a reduced search returns a value @@ -879,21 +875,27 @@ namespace { if ( !PvNode && depth > 4 && abs(beta) < VALUE_TB_WIN_IN_MAX_PLY - && !( ttHit - && tte->depth() >= depth - 3 + // if value from transposition table is lower than probCutBeta, don't attempt probCut + // there and in further interactions with transposition table cutoff depth is set to depth - 3 + // because probCut search has depth set to depth - 4 but we also do a move before it + // so effective depth is equal to depth - 3 + && !( ttHit + && tte->depth() >= depth - 3 && ttValue != VALUE_NONE - && ttValue < probcutBeta)) + && ttValue < probCutBeta)) { + // if ttMove is a capture and value from transposition table is good enough produce probCut + // cutoff without digging into actual probCut search if ( ttHit && tte->depth() >= depth - 3 && ttValue != VALUE_NONE - && ttValue >= probcutBeta + && ttValue >= probCutBeta && ttMove && pos.capture_or_promotion(ttMove)) - return probcutBeta; + return probCutBeta; - assert(probcutBeta < VALUE_INFINITE); - MovePicker mp(pos, ttMove, probcutBeta - ss->staticEval, &captureHistory); + assert(probCutBeta < VALUE_INFINITE); + MovePicker mp(pos, ttMove, probCutBeta - ss->staticEval, &captureHistory); int probCutCount = 0; while ( (move = mp.next_move()) != MOVE_NONE @@ -915,16 +917,17 @@ namespace { pos.do_move(move, st); // Perform a preliminary qsearch to verify that the move holds - value = -qsearch(pos, ss+1, -probcutBeta, -probcutBeta+1); + value = -qsearch(pos, ss+1, -probCutBeta, -probCutBeta+1); // If the qsearch held, perform the regular search - if (value >= probcutBeta) - value = -search(pos, ss+1, -probcutBeta, -probcutBeta+1, depth - 4, !cutNode); + if (value >= probCutBeta) + value = -search(pos, ss+1, -probCutBeta, -probCutBeta+1, depth - 4, !cutNode); pos.undo_move(move); - if (value >= probcutBeta) + if (value >= probCutBeta) { + // if transposition table doesn't have equal or more deep info write probCut data into it if ( !(ttHit && tte->depth() >= depth - 3 && ttValue != VALUE_NONE)) @@ -986,6 +989,10 @@ moves_loop: // When in check, search starts from here thisThread->rootMoves.begin() + thisThread->pvLast, move)) continue; + // Check for legality + if (!rootNode && !pos.legal(move)) + continue; + ss->moveCount = ++moveCount; if (rootNode && thisThread == Threads.main() && Time.elapsed() > 3000) @@ -1024,17 +1031,17 @@ moves_loop: // When in check, search starts from here continue; // Futility pruning: parent node (~5 Elo) - if ( lmrDepth < 6 + if ( lmrDepth < 7 && !ss->inCheck - && ss->staticEval + 284 + 188 * lmrDepth <= alpha + && ss->staticEval + 283 + 170 * lmrDepth <= alpha && (*contHist[0])[movedPiece][to_sq(move)] + (*contHist[1])[movedPiece][to_sq(move)] + (*contHist[3])[movedPiece][to_sq(move)] - + (*contHist[5])[movedPiece][to_sq(move)] / 2 < 28388) + + (*contHist[5])[movedPiece][to_sq(move)] / 2 < 27376) continue; // Prune moves with negative SEE (~20 Elo) - if (!pos.see_ge(move, Value(-(29 - std::min(lmrDepth, 17)) * lmrDepth * lmrDepth))) + if (!pos.see_ge(move, Value(-(29 - std::min(lmrDepth, 18)) * lmrDepth * lmrDepth))) continue; } else @@ -1051,12 +1058,12 @@ moves_loop: // When in check, search starts from here && !(PvNode && abs(bestValue) < 2) && PieceValue[MG][type_of(movedPiece)] >= PieceValue[MG][type_of(pos.piece_on(to_sq(move)))] && !ss->inCheck - && ss->staticEval + 267 + 391 * lmrDepth + && ss->staticEval + 169 + 244 * lmrDepth + PieceValue[MG][type_of(pos.piece_on(to_sq(move)))] <= alpha) continue; // See based pruning - if (!pos.see_ge(move, Value(-202) * depth)) // (~25 Elo) + if (!pos.see_ge(move, Value(-221) * depth)) // (~25 Elo) continue; } } @@ -1067,16 +1074,15 @@ moves_loop: // When in check, search starts from here // 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 ( depth >= 6 + // result is lower than ttValue minus a margin, then we will extend the ttMove. + if ( depth >= 7 && move == ttMove && !rootNode && !excludedMove // Avoid recursive singular search /* && ttValue != VALUE_NONE Already implicit in the next condition */ && abs(ttValue) < VALUE_KNOWN_WIN && (tte->bound() & BOUND_LOWER) - && tte->depth() >= depth - 3 - && pos.legal(move)) + && tte->depth() >= depth - 3) { Value singularBeta = ttValue - ((formerPv + 4) * depth) / 2; Depth singularDepth = (depth - 1 + 3 * formerPv) / 2; @@ -1116,19 +1122,14 @@ moves_loop: // When in check, search starts from here && (pos.is_discovery_check_on_king(~us, move) || pos.see_ge(move))) extension = 1; - // Passed pawn extension - else if ( move == ss->killers[0] - && pos.advanced_pawn_push(move) - && pos.pawn_passed(us, to_sq(move))) - extension = 1; - // Last captures extension else if ( PieceValue[EG][pos.captured_piece()] > PawnValueEg && pos.non_pawn_material() <= 2 * RookValueMg) extension = 1; // Castling extension - if (type_of(move) == CASTLING) + if ( type_of(move) == CASTLING + && popcount(pos.pieces(us) & ~pos.pieces(PAWN) & (to_sq(move) & KingSide ? KingSide : QueenSide)) <= 2) extension = 1; // Late irreversible move extension @@ -1143,13 +1144,6 @@ moves_loop: // When in check, search starts from here // Speculative prefetch as early as possible prefetch(TT.first_entry(pos.key_after(move))); - // Check for legality just before making the move - if (!rootNode && !pos.legal(move)) - { - ss->moveCount = --moveCount; - continue; - } - // Update the current move (this must be done after singular extension search) ss->currentMove = move; ss->continuationHistory = &thisThread->continuationHistory[ss->inCheck] @@ -1163,18 +1157,25 @@ moves_loop: // When in check, search starts from here // Step 16. Reduced depth search (LMR, ~200 Elo). If the move fails high it will be // re-searched at full depth. if ( depth >= 3 - && moveCount > 1 + 2 * rootNode + && moveCount > 1 + 2 * rootNode + 2 * (PvNode && abs(bestValue) < 2) && (!rootNode || thisThread->best_move_count(move) == 0) && ( !captureOrPromotion || moveCountPruning || ss->staticEval + PieceValue[EG][pos.captured_piece()] <= alpha || cutNode - || thisThread->ttHitAverage < 415 * TtHitAverageResolution * TtHitAverageWindow / 1024)) + || thisThread->ttHitAverage < 427 * TtHitAverageResolution * TtHitAverageWindow / 1024)) { Depth r = reduction(improving, depth, moveCount); + // Decrease reduction at non-check cut nodes for second move at low depths + if ( cutNode + && depth <= 10 + && moveCount <= 2 + && !ss->inCheck) + r--; + // Decrease reduction if the ttHit running average is large - if (thisThread->ttHitAverage > 473 * TtHitAverageResolution * TtHitAverageWindow / 1024) + if (thisThread->ttHitAverage > 509 * TtHitAverageResolution * TtHitAverageWindow / 1024) r--; // Reduction if other threads are searching this position @@ -1217,17 +1218,17 @@ moves_loop: // When in check, search starts from here + (*contHist[0])[movedPiece][to_sq(move)] + (*contHist[1])[movedPiece][to_sq(move)] + (*contHist[3])[movedPiece][to_sq(move)] - - 4826; + - 5287; // Decrease/increase reduction by comparing opponent's stat score (~10 Elo) - if (ss->statScore >= -100 && (ss-1)->statScore < -112) + if (ss->statScore >= -106 && (ss-1)->statScore < -104) r--; - else if ((ss-1)->statScore >= -125 && ss->statScore < -138) + else if ((ss-1)->statScore >= -119 && ss->statScore < -140) r++; // Decrease/increase reduction for moves with a good/bad history (~30 Elo) - r -= ss->statScore / 14615; + r -= ss->statScore / 14884; } else { @@ -1237,7 +1238,7 @@ moves_loop: // When in check, search starts from here // Unless giving check, this capture is likely bad if ( !givesCheck - && ss->staticEval + PieceValue[EG][pos.captured_piece()] + 211 * depth <= alpha) + && ss->staticEval + PieceValue[EG][pos.captured_piece()] + 213 * depth <= alpha) r++; } @@ -1499,7 +1500,7 @@ moves_loop: // When in check, search starts from here if (PvNode && bestValue > alpha) alpha = bestValue; - futilityBase = bestValue + 141; + futilityBase = bestValue + 145; } const PieceToHistory* contHist[] = { (ss-1)->continuationHistory, (ss-2)->continuationHistory, @@ -1750,7 +1751,7 @@ moves_loop: // When in check, search starts from here } if (depth > 11 && ss->ply < MAX_LPH) - thisThread->lowPlyHistory[ss->ply][from_to(move)] << stat_bonus(depth - 6); + thisThread->lowPlyHistory[ss->ply][from_to(move)] << stat_bonus(depth - 7); } // When playing with strength handicap, choose best move among a set of RootMoves