X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fsearch.cpp;h=8ce9c56e42d0849e2caf9b2528d463faf524fe21;hb=21d6b69f7c8d0c0a71fe627714913a59d39a3b57;hp=d6571a140f36b1e9ab5293895aff192df271a785;hpb=f0556dcbe3ba2fc804ab26d4552446602a75f064;p=stockfish diff --git a/src/search.cpp b/src/search.cpp index d6571a14..8ce9c56e 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -34,6 +34,7 @@ #include "tt.h" #include "uci.h" #include "syzygy/tbprobe.h" +#include "nnue/evaluate_nnue.h" namespace Stockfish { @@ -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 + 1449 - int(delta) * 1032 / int(rootDelta)) / 1024 + (!i && r > 941); + 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(340 * d - 470, 1855); + return std::min(341 * d - 470, 1710); } // Add a small random component to draw evaluations to avoid 3-fold blindness @@ -287,8 +288,7 @@ void Thread::search() { ss->pv = pv; - bestValue = delta = alpha = -VALUE_INFINITE; - beta = VALUE_INFINITE; + bestValue = -VALUE_INFINITE; if (mainThread) { @@ -310,10 +310,6 @@ void Thread::search() { multiPV = std::min(multiPV, rootMoves.size()); - complexityAverage.set(153, 1); - - optimism[us] = optimism[~us] = VALUE_ZERO; - int searchAgainCounter = 0; // Iterative deepening loop until requested to stop or the target depth is reached @@ -351,18 +347,15 @@ void Thread::search() { selDepth = 0; // Reset aspiration window starting size - if (rootDepth >= 4) - { - Value prev = rootMoves[pvIdx].averageScore; - delta = Value(10) + int(prev) * prev / 16502; - alpha = std::max(prev - delta,-VALUE_INFINITE); - beta = std::min(prev + delta, VALUE_INFINITE); - - // Adjust optimism based on root move's previousScore - int opt = 120 * prev / (std::abs(prev) + 161); - optimism[ us] = Value(opt); - optimism[~us] = -optimism[us]; - } + Value prev = rootMoves[pvIdx].averageScore; + delta = Value(10) + int(prev) * prev / 16502; + alpha = std::max(prev - delta,-VALUE_INFINITE); + beta = std::min(prev + delta, VALUE_INFINITE); + + // Adjust optimism based on root move's previousScore + int opt = 102 * prev / (std::abs(prev) + 147); + optimism[ us] = Value(opt); + optimism[~us] = -optimism[us]; // Start with a small aspiration window and, in the case of a fail // high/low, re-search with a bigger window until we don't fail @@ -471,10 +464,8 @@ void Thread::search() { 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(); - int complexity = mainThread->complexityAverage.value(); - double complexPosition = std::min(1.03 + (complexity - 241) / 1552.0, 1.45); - double totalTime = Time.optimum() * fallingEval * reduction * bestMoveInstability * complexPosition; + double totalTime = Time.optimum() * fallingEval * reduction * bestMoveInstability; // Cap used time in case of a single legal move for a better viewer experience in tournaments // yielding correct scores and sufficiently fast moves. @@ -557,7 +548,7 @@ namespace { bool givesCheck, improving, priorCapture, singularQuietLMR; bool capture, moveCountPruning, ttCapture; Piece movedPiece; - int moveCount, captureCount, quietCount, improvement, complexity; + int moveCount, captureCount, quietCount, improvement; // Step 1. Initialize node Thread* thisThread = pos.this_thread(); @@ -605,15 +596,8 @@ namespace { (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); - - // 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; + Square prevSq = is_ok((ss-1)->currentMove) ? to_sq((ss-1)->currentMove) : SQ_NONE; + ss->statScore = 0; // Step 4. Transposition table lookup. excludedMove = ss->excludedMove; @@ -647,7 +631,7 @@ namespace { update_quiet_stats(pos, ss, ttMove, stat_bonus(depth)); // Extra penalty for early quiet moves of the previous ply (~0 Elo on STC, ~2 Elo on LTC) - if ((ss-1)->moveCount <= 2 && !priorCapture) + 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) @@ -726,25 +710,22 @@ namespace { ss->staticEval = eval = VALUE_NONE; improving = false; improvement = 0; - 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) + // 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 ss->staticEval = eval = tte->eval(); 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 + ss->staticEval = eval = evaluate(pos); + else { - complexity = abs(ss->staticEval - pos.psq_eg_stm()); if (PvNode) Eval::NNUE::hint_common_parent_position(pos); } @@ -756,13 +737,11 @@ namespace { } else { - ss->staticEval = eval = evaluate(pos, &complexity); + ss->staticEval = eval = evaluate(pos); // Save static evaluation into transposition table 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 (~4 Elo) if (is_ok((ss-1)->currentMove) && !(ss-1)->inCheck && !priorCapture) { @@ -782,7 +761,7 @@ namespace { // 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 - 426 - 252 * depth * depth) + if (eval < alpha - 426 - 256 * depth * depth) { value = qsearch(pos, ss, alpha - 1, alpha); if (value < alpha) @@ -804,15 +783,15 @@ namespace { && (ss-1)->statScore < 18755 && eval >= beta && eval >= ss->staticEval - && ss->staticEval >= beta - 19 * depth - improvement / 13 + 253 + complexity / 25 + && ss->staticEval >= beta - 20 * depth - improvement / 13 + 253 && !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) / 168, 6) + depth / 3 + 4 - (complexity > 825); + // Null move dynamic reduction based on depth and eval + Depth R = std::min(int(eval - beta) / 172, 6) + depth / 3 + 4; ss->currentMove = MOVE_NULL; ss->continuationHistory = &thisThread->continuationHistory[0][0][NO_PIECE][0]; @@ -835,9 +814,8 @@ 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); @@ -902,11 +880,11 @@ namespace { Eval::NNUE::hint_common_parent_position(pos); } - // Step 11. If the position is not in TT, decrease depth by 3. + // 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); @@ -935,7 +913,7 @@ moves_loop: // When in check, search starts here 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, @@ -1011,16 +989,33 @@ moves_loop: // When in check, search starts here { // Futility pruning for captures (~2 Elo) if ( !givesCheck - && !PvNode && lmrDepth < 6 && !ss->inCheck && 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; + Bitboard occupied; // SEE based pruning (~11 Elo) - if (!pos.see_ge(move, Value(-206) * depth)) - continue; + if (!pos.see_ge(move, occupied, Value(-206) * depth)) + { + if (depth < 2 - capture) + continue; + // Don't prune the move if opp. King/Queen/Rook gets a discovered attack during or after the exchanges + Bitboard leftEnemies = pos.pieces(~us, KING, QUEEN, ROOK); + 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 (opp King can't be in check when it's our turn) + if (attacks && sq != pos.square(~us) && (pos.attackers_to(sq, pos.pieces()) & pos.pieces(us))) + attacks = 0; + } + if (!attacks) + continue; + } } else { @@ -1047,7 +1042,7 @@ moves_loop: // When in check, search starts here lmrDepth = std::max(lmrDepth, 0); // Prune moves with negative SEE (~4 Elo) - if (!pos.see_ge(move, Value(-24 * lmrDepth * lmrDepth - 15 * lmrDepth))) + if (!pos.see_ge(move, Value(-24 * lmrDepth * lmrDepth - 16 * lmrDepth))) continue; } } @@ -1100,15 +1095,15 @@ 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 - !PvNode; - // If the eval of ttMove is less than value, we reduce it (negative extension) + // 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, we reduce it (negative extension) + // If the eval of ttMove is less than alpha, we reduce it (negative extension) (~1 Elo) else if (ttValue <= alpha) extension = -1; } @@ -1162,7 +1157,7 @@ moves_loop: // When in check, search starts here if (ttCapture) r++; - // Decrease reduction for PvNodes based on depth + // Decrease reduction for PvNodes based on depth (~2 Elo) if (PvNode) r -= 1 + 12 / (3 + depth); @@ -1170,28 +1165,21 @@ moves_loop: // When in check, search starts here if (singularQuietLMR) r--; - // Decrease reduction if we move a threatened piece (~1 Elo) - if ( depth > 9 - && (mp.threatenedPieces & from_sq(move))) - r--; - - // Increase reduction if next ply has a lot of fail high + // Increase reduction if next ply has a lot of fail high (~5 Elo) if ((ss+1)->cutoffCnt > 3) r++; - // Decrease reduction if move is a killer and we have a good history - if (move == ss->killers[0] - && (*contHist[0])[movedPiece][to_sq(move)] >= 3722) + else if (move == ttMove) r--; 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)] - - 4182; + - 4082; - // Decrease/increase reduction for moves with a good/bad history (~30 Elo) - r -= ss->statScore / (11791 + 3992 * (depth > 6 && depth < 19)); + // 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 @@ -1226,8 +1214,9 @@ moves_loop: // When in check, search starts here if (newDepth > d) value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode); - int bonus = value > alpha ? stat_bonus(newDepth) - : -stat_bonus(newDepth); + int bonus = value <= alpha ? -stat_bonus(newDepth) + : value >= beta ? stat_bonus(newDepth) + : 0; update_continuation_histories(ss, movedPiece, to_sq(move), bonus); } @@ -1325,16 +1314,14 @@ 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 + // Reduce other moves if we have found at least one score improvement (~1 Elo) if ( depth > 1 - && depth < 6 - && beta < 10534 - && alpha > -10534) + && beta < 12535 + && value > -12535) depth -= 1; assert(depth > 0); + alpha = value; } else { @@ -1383,7 +1370,7 @@ moves_loop: // When in check, search starts here quietsSearched, quietCount, capturesSearched, captureCount, depth); // Bonus for prior countermove that caused the fail low - else if (!priorCapture) + else if (!priorCapture && prevSq != SQ_NONE) { 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); @@ -1393,7 +1380,7 @@ moves_loop: // When in check, search starts here 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); @@ -1412,7 +1399,7 @@ 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) { @@ -1525,7 +1512,7 @@ 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, @@ -1714,7 +1701,8 @@ 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_stage(bestMove)) @@ -1733,12 +1721,16 @@ 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);