X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=60a002a908842da0221b0cb42db7df686b24cd8e;hp=07c491b69f487faae35f5aa07469c864a3263ebb;hb=51deae899814bbbfd9db5686b824f23105ca8a39;hpb=35ab8254b70f62a4e0138c475fad0c77dcc0af2d diff --git a/src/search.cpp b/src/search.cpp index 07c491b6..60a002a9 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -65,7 +65,7 @@ namespace { // Razor and futility margins constexpr int RazorMargin = 510; Value futility_margin(Depth d, bool improving) { - return Value(223 * (d - improving)); + return Value(234 * (d - improving)); } // Reductions lookup table, initialized at startup @@ -73,7 +73,7 @@ namespace { Depth reduction(bool i, Depth d, int mn) { int r = Reductions[d] * Reductions[mn]; - return (r + 509) / 1024 + (!i && r > 894); + return (r + 503) / 1024 + (!i && r > 915); } constexpr int futility_move_count(bool improving, Depth depth) { @@ -164,6 +164,8 @@ namespace { uint64_t perft(Position& pos, Depth depth) { StateInfo st; + ASSERT_ALIGNED(&st, Eval::NNUE::kCacheLineSize); + uint64_t cnt, nodes = 0; const bool leaf = (depth == 2); @@ -192,7 +194,7 @@ namespace { void Search::init() { for (int i = 1; i < MAX_MOVES; ++i) - Reductions[i] = int((22.0 + std::log(Threads.size())) * std::log(i)); + Reductions[i] = int((21.3 + 2 * std::log(Threads.size())) * std::log(i + 0.25 * std::log(i))); } @@ -225,7 +227,7 @@ void MainThread::search() { Time.init(Limits, us, rootPos.game_ply()); TT.new_search(); - Eval::verify_NNUE(); + Eval::NNUE::verify(); if (rootMoves.empty()) { @@ -408,7 +410,7 @@ void Thread::search() { beta = std::min(prev + delta, VALUE_INFINITE); // Adjust contempt based on root move's previousScore (dynamic contempt) - int dct = ct + (105 - ct / 2) * prev / (abs(prev) + 149); + int dct = ct + (113 - ct / 2) * prev / (abs(prev) + 147); contempt = (us == WHITE ? make_score(dct, dct / 2) : -make_score(dct, dct / 2)); @@ -417,7 +419,7 @@ void Thread::search() { // 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 // high/low anymore. - int failedHighCnt = 0; + failedHighCnt = 0; while (true) { Depth adjustedDepth = std::max(1, rootDepth - failedHighCnt - searchAgainCounter); @@ -462,10 +464,7 @@ void Thread::search() { ++failedHighCnt; } else - { - ++rootMoves[pvIdx].bestMoveCount; break; - } delta += delta / 4 + 5; @@ -520,12 +519,16 @@ void Thread::search() { totBestMoveChanges += th->bestMoveChanges; th->bestMoveChanges = 0; } - double bestMoveInstability = 1 + totBestMoveChanges / Threads.size(); + double bestMoveInstability = 1 + 2 * totBestMoveChanges / Threads.size(); + + double totalTime = Time.optimum() * fallingEval * reduction * bestMoveInstability; - double totalTime = rootMoves.size() == 1 ? 0 : - 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. + if (rootMoves.size() == 1) + totalTime = std::min(500.0, totalTime); - // Stop the search if we have exceeded the totalTime, at least 1ms search + // Stop the search if we have exceeded the totalTime if (Time.elapsed() > totalTime) { // If we are allowed to ponder do not stop the search now but @@ -568,6 +571,7 @@ namespace { constexpr bool PvNode = NT == PV; const bool rootNode = PvNode && ss->ply == 0; + 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. @@ -592,6 +596,8 @@ namespace { Move pv[MAX_PLY+1], capturesSearched[32], quietsSearched[64]; StateInfo st; + ASSERT_ALIGNED(&st, Eval::NNUE::kCacheLineSize); + TTEntry* tte; Key posKey; Move ttMove, move, excludedMove, bestMove; @@ -670,6 +676,7 @@ namespace { ss->ttPv = PvNode || (ss->ttHit && tte->is_pv()); formerPv = ss->ttPv && !PvNode; + // Update low ply history for previous move if we are near root and position is or has been in PV if ( ss->ttPv && depth > 12 && ss->ply - 1 < MAX_LPH @@ -694,6 +701,7 @@ namespace { { if (ttValue >= beta) { + // Bonus for a quiet ttMove that fails high if (!pos.capture_or_promotion(ttMove)) update_quiet_stats(pos, ss, ttMove, stat_bonus(depth), depth); @@ -710,6 +718,8 @@ namespace { } } + // Partial workaround for the graph history interaction problem + // For high rule50 counts don't produce transposition table cutoffs. if (pos.rule50_count() < 90) return ttValue; } @@ -783,6 +793,7 @@ namespace { if (eval == VALUE_NONE) ss->staticEval = eval = evaluate(pos); + // Randomize draw evaluation if (eval == VALUE_DRAW) eval = value_draw(thisThread); @@ -793,20 +804,34 @@ namespace { } else { + // In case of null move search use previous static eval with a different sign + // and addition of two tempos if ((ss-1)->currentMove != MOVE_NULL) ss->staticEval = eval = evaluate(pos); else ss->staticEval = eval = -(ss-1)->staticEval + 2 * Tempo; + // Save static evaluation into transposition table tte->save(posKey, VALUE_NONE, ss->ttPv, BOUND_NONE, DEPTH_NONE, MOVE_NONE, eval); } + // Use static evaluation difference to improve quiet move ordering + if (is_ok((ss-1)->currentMove) && !(ss-1)->inCheck && !priorCapture) + { + int bonus = std::clamp(-depth * 4 * int((ss-1)->staticEval + ss->staticEval - 2 * Tempo), -1000, 1000); + thisThread->mainHistory[~us][from_to((ss-1)->currentMove)] << bonus; + } + // Step 7. Razoring (~1 Elo) if ( !rootNode // The required rootNode PV handling is not available in qsearch && depth == 1 && eval <= alpha - RazorMargin) return qsearch(pos, ss, alpha, beta); + // Set up improving flag that is used in various pruning heuristics + // We define position as improving if static evaluation of position is better + // Than the previous static evaluation at our turn + // In case of us being in check at our previous move we look at move prior to it improving = (ss-2)->staticEval == VALUE_NONE ? ss->staticEval > (ss-4)->staticEval || (ss-4)->staticEval == VALUE_NONE : ss->staticEval > (ss-2)->staticEval; @@ -824,7 +849,7 @@ namespace { && (ss-1)->statScore < 22977 && eval >= beta && eval >= ss->staticEval - && ss->staticEval >= beta - 30 * depth - 28 * improving + 84 * ss->ttPv + 182 + && ss->staticEval >= beta - 30 * depth - 28 * improving + 84 * ss->ttPv + 168 && !excludedMove && pos.non_pawn_material(us) && (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor)) @@ -832,7 +857,7 @@ namespace { assert(eval - beta >= 0); // Null move dynamic reduction based on depth and value - Depth R = (817 + 71 * depth) / 213 + std::min(int(eval - beta) / 192, 3); + Depth R = (1015 + 85 * depth) / 256 + std::min(int(eval - beta) / 191, 3); ss->currentMove = MOVE_NULL; ss->continuationHistory = &thisThread->continuationHistory[0][0][NO_PIECE][0]; @@ -849,7 +874,7 @@ namespace { if (nullValue >= VALUE_TB_WIN_IN_MAX_PLY) nullValue = beta; - if (thisThread->nmpMinPly || (abs(beta) < VALUE_KNOWN_WIN && depth < 13)) + if (thisThread->nmpMinPly || (abs(beta) < VALUE_KNOWN_WIN && depth < 14)) return nullValue; assert(!thisThread->nmpMinPly); // Recursive verification is not allowed @@ -868,7 +893,7 @@ namespace { } } - probCutBeta = beta + 176 - 49 * improving; + probCutBeta = beta + 183 - 49 * improving; // Step 10. ProbCut (~10 Elo) // If we have a good enough capture and a reduced search returns a value @@ -1033,7 +1058,7 @@ moves_loop: // When in check, search starts from here // Futility pruning: parent node (~5 Elo) if ( lmrDepth < 7 && !ss->inCheck - && ss->staticEval + 283 + 170 * lmrDepth <= alpha + && ss->staticEval + 266 + 170 * lmrDepth <= alpha && (*contHist[0])[movedPiece][to_sq(move)] + (*contHist[1])[movedPiece][to_sq(move)] + (*contHist[3])[movedPiece][to_sq(move)] @@ -1041,7 +1066,7 @@ moves_loop: // When in check, search starts from here continue; // Prune moves with negative SEE (~20 Elo) - if (!pos.see_ge(move, Value(-(29 - std::min(lmrDepth, 18)) * lmrDepth * lmrDepth))) + if (!pos.see_ge(move, Value(-(30 - std::min(lmrDepth, 18)) * lmrDepth * lmrDepth))) continue; } else @@ -1052,18 +1077,8 @@ moves_loop: // When in check, search starts from here && captureHistory[movedPiece][to_sq(move)][type_of(pos.piece_on(to_sq(move)))] < 0) continue; - // Futility pruning for captures - if ( !givesCheck - && lmrDepth < 6 - && !(PvNode && abs(bestValue) < 2) - && PieceValue[MG][type_of(movedPiece)] >= PieceValue[MG][type_of(pos.piece_on(to_sq(move)))] - && !ss->inCheck - && 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(-221) * depth)) // (~25 Elo) + // SEE based pruning + if (!pos.see_ge(move, Value(-213) * depth)) // (~25 Elo) continue; } } @@ -1127,11 +1142,6 @@ moves_loop: // When in check, search starts from here && pos.non_pawn_material() <= 2 * RookValueMg) extension = 1; - // Castling extension - 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 if ( move == ttMove && pos.rule50_count() > 80 @@ -1157,20 +1167,21 @@ 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 + 2 * (PvNode && abs(bestValue) < 2) + && moveCount > 1 + 2 * rootNode && ( !captureOrPromotion || moveCountPruning || ss->staticEval + PieceValue[EG][pos.captured_piece()] <= alpha || cutNode - || thisThread->ttHitAverage < 427 * TtHitAverageResolution * TtHitAverageWindow / 1024)) + || (!PvNode && !formerPv) + || thisThread->ttHitAverage < 432 * TtHitAverageResolution * TtHitAverageWindow / 1024)) { Depth r = reduction(improving, depth, moveCount); // Decrease reduction if the ttHit running average is large - if (thisThread->ttHitAverage > 509 * TtHitAverageResolution * TtHitAverageWindow / 1024) + if (thisThread->ttHitAverage > 537 * TtHitAverageResolution * TtHitAverageWindow / 1024) r--; - // Reduction if other threads are searching this position + // Increase reduction if other threads are searching this position if (th.marked()) r++; @@ -1178,6 +1189,11 @@ moves_loop: // When in check, search starts from here if (ss->ttPv) r -= 2; + // Increase reduction at root and non-PV nodes when the best move does not change frequently + if ((rootNode || !PvNode) && thisThread->rootDepth > 10 && thisThread->bestMoveChanges <= 2) + r++; + + // More reductions for late moves if position was not in previous PV if (moveCountPruning && !formerPv) r++; @@ -1195,6 +1211,9 @@ moves_loop: // When in check, search starts from here if (ttCapture) r++; + // Increase reduction at root if failing high + r += rootNode ? thisThread->failedHighCnt * thisThread->failedHighCnt * moveCount / 512 : 0; + // Increase reduction for cut nodes (~10 Elo) if (cutNode) r += 2; @@ -1213,10 +1232,10 @@ moves_loop: // When in check, search starts from here - 5287; // Decrease/increase reduction by comparing opponent's stat score (~10 Elo) - if (ss->statScore >= -106 && (ss-1)->statScore < -104) + if (ss->statScore >= -105 && (ss-1)->statScore < -103) r--; - else if ((ss-1)->statScore >= -119 && ss->statScore < -140) + else if ((ss-1)->statScore >= -122 && ss->statScore < -129) r++; // Decrease/increase reduction for moves with a good/bad history (~30 Elo) @@ -1224,14 +1243,10 @@ moves_loop: // When in check, search starts from here } else { - // Increase reduction for captures/promotions if late move and at low depth - if (depth < 8 && moveCount > 2) - r++; - - // Unless giving check, this capture is likely bad - if ( !givesCheck - && ss->staticEval + PieceValue[EG][pos.captured_piece()] + 213 * depth <= alpha) - r++; + // Unless giving check, this capture is likely bad + if ( !givesCheck + && ss->staticEval + PieceValue[EG][pos.captured_piece()] + 210 * depth <= alpha) + r++; } Depth d = std::clamp(newDepth - r, 1, newDepth); @@ -1254,14 +1269,12 @@ moves_loop: // When in check, search starts from here { value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode); + // If the move passed LMR update its stats if (didLMR && !captureOrPromotion) { int bonus = value > alpha ? stat_bonus(newDepth) : -stat_bonus(newDepth); - if (move == ss->killers[0]) - bonus += bonus / 4; - update_continuation_histories(ss, movedPiece, to_sq(move), bonus); } } @@ -1274,7 +1287,8 @@ moves_loop: // When in check, search starts from here (ss+1)->pv = pv; (ss+1)->pv[0] = MOVE_NONE; - value = -search(pos, ss+1, -beta, -alpha, newDepth, false); + value = -search(pos, ss+1, -beta, -alpha, + std::min(maxNextDepth, newDepth), false); } // Step 18. Undo move @@ -1307,8 +1321,7 @@ moves_loop: // When in check, search starts from here rm.pv.push_back(*m); // We record how often the best move has been changed in each - // iteration. This information is used for time management: when - // the best move changes frequently, we allocate some more time. + // iteration. This information is used for time management and LMR if (moveCount > 1) ++thisThread->bestMoveChanges; } @@ -1341,6 +1354,7 @@ moves_loop: // When in check, search starts from here } } + // If the move is worse than some previously searched move, remember it to update its stats later if (move != bestMove) { if (captureOrPromotion && captureCount < 32) @@ -1370,6 +1384,7 @@ moves_loop: // When in check, search starts from here bestValue = excludedMove ? alpha : ss->inCheck ? mated_in(ss->ply) : VALUE_DRAW; + // If there is a move which produces search value greater than alpha we update stats of searched moves else if (bestMove) update_all_stats(pos, ss, bestMove, bestValue, beta, prevSq, quietsSearched, quietCount, capturesSearched, captureCount, depth); @@ -1391,6 +1406,7 @@ moves_loop: // When in check, search starts from here else if (depth > 3) ss->ttPv = ss->ttPv && (ss+1)->ttPv; + // Write gathered information in transposition table if (!excludedMove && !(rootNode && thisThread->pvIdx)) tte->save(posKey, value_to_tt(bestValue, ss->ply), ss->ttPv, bestValue >= beta ? BOUND_LOWER : @@ -1416,6 +1432,8 @@ moves_loop: // When in check, search starts from here Move pv[MAX_PLY+1]; StateInfo st; + ASSERT_ALIGNED(&st, Eval::NNUE::kCacheLineSize); + TTEntry* tte; Key posKey; Move ttMove, move, bestMove; @@ -1484,6 +1502,8 @@ moves_loop: // When in check, search starts from here bestValue = ttValue; } else + // In case of null move search use previous static eval with a different sign + // and addition of two tempos ss->staticEval = bestValue = (ss-1)->currentMove != MOVE_NULL ? evaluate(pos) : -(ss-1)->staticEval + 2 * Tempo; @@ -1491,6 +1511,7 @@ moves_loop: // When in check, search starts from here // Stand pat. Return immediately if static value is at least beta if (bestValue >= beta) { + // Save gathered info in transposition table if (!ss->ttHit) tte->save(posKey, value_to_tt(bestValue, ss->ply), false, BOUND_LOWER, DEPTH_NONE, MOVE_NONE, ss->staticEval); @@ -1501,7 +1522,7 @@ moves_loop: // When in check, search starts from here if (PvNode && bestValue > alpha) alpha = bestValue; - futilityBase = bestValue + 145; + futilityBase = bestValue + 155; } const PieceToHistory* contHist[] = { (ss-1)->continuationHistory, (ss-2)->continuationHistory, @@ -1528,7 +1549,7 @@ moves_loop: // When in check, search starts from here moveCount++; // Futility pruning - if ( !ss->inCheck + if ( bestValue > VALUE_TB_LOSS_IN_MAX_PLY && !givesCheck && futilityBase > -VALUE_KNOWN_WIN && !pos.advanced_pawn_push(move)) @@ -1555,8 +1576,7 @@ moves_loop: // When in check, search starts from here } // Do not search moves with negative SEE values - if ( !ss->inCheck - && !(givesCheck && pos.is_discovery_check_on_king(~pos.side_to_move(), move)) + if ( bestValue > VALUE_TB_LOSS_IN_MAX_PLY && !pos.see_ge(move)) continue; @@ -1576,8 +1596,9 @@ moves_loop: // When in check, search starts from here [pos.moved_piece(move)] [to_sq(move)]; + // CounterMove based pruning if ( !captureOrPromotion - && moveCount + && 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; @@ -1612,8 +1633,13 @@ moves_loop: // When in check, search starts from here // 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) + { + assert(!MoveList(pos).size()); + return mated_in(ss->ply); // Plies to mate from the root + } + // Save gathered info in transposition table tte->save(posKey, value_to_tt(bestValue, ss->ply), pvHit, bestValue >= beta ? BOUND_LOWER : PvNode && bestValue > oldAlpha ? BOUND_EXACT : BOUND_UPPER, @@ -1697,9 +1723,10 @@ moves_loop: // When in check, search starts from here if (!pos.capture_or_promotion(bestMove)) { + // Increase stats for the best move in case it was a quiet move update_quiet_stats(pos, ss, bestMove, bonus2, depth); - // Decrease all the non-best quiet moves + // Decrease stats for all non-best quiet moves for (int i = 0; i < quietCount; ++i) { thisThread->mainHistory[us][from_to(quietsSearched[i])] << -bonus2; @@ -1707,14 +1734,16 @@ moves_loop: // When in check, search starts from here } } else + // Increase stats for the best move in case it was a capture move 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 + // 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])) && !pos.captured_piece()) update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -bonus1); - // Decrease all the non-best capture moves + // Decrease stats for all non-best capture moves for (int i = 0; i < captureCount; ++i) { moved_piece = pos.moved_piece(capturesSearched[i]); @@ -1731,6 +1760,7 @@ moves_loop: // When in check, search starts from here for (int i : {1, 2, 4, 6}) { + // Only update first 2 continuation histories if we are in check if (ss->inCheck && i > 2) break; if (is_ok((ss-i)->currentMove)) @@ -1743,6 +1773,7 @@ moves_loop: // When in check, search starts from here void update_quiet_stats(const Position& pos, Stack* ss, Move move, int bonus, int depth) { + // Update killers if (ss->killers[0] != move) { ss->killers[1] = ss->killers[0]; @@ -1754,15 +1785,18 @@ moves_loop: // When in check, search starts from here thisThread->mainHistory[us][from_to(move)] << bonus; update_continuation_histories(ss, pos.moved_piece(move), to_sq(move), bonus); + // Penalty for reversed move in case of moved piece not being a pawn if (type_of(pos.moved_piece(move)) != PAWN) thisThread->mainHistory[us][from_to(reverse_move(move))] << -bonus; + // Update countermove history if (is_ok((ss-1)->currentMove)) { Square prevSq = to_sq((ss-1)->currentMove); thisThread->counterMoves[pos.piece_on(prevSq)][prevSq] = move; } + // Update low ply history if (depth > 11 && ss->ply < MAX_LPH) thisThread->lowPlyHistory[ss->ply][from_to(move)] << stat_bonus(depth - 7); } @@ -1906,6 +1940,8 @@ string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) { bool RootMove::extract_ponder_from_tt(Position& pos) { StateInfo st; + ASSERT_ALIGNED(&st, Eval::NNUE::kCacheLineSize); + bool ttHit; assert(pv.size() == 1);