X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=dae1e23c0339b6daa0b1fff438d4079b25ee21ff;hp=f866afe5ce7b887747e80da04e79c6593a8713f2;hb=0e51ff1074d5a66495a21990bd1826a8d06447e8;hpb=8c73339a3639f1753b2270b569532daffa7d93f5 diff --git a/src/search.cpp b/src/search.cpp index f866afe5..dae1e23c 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -194,7 +194,7 @@ namespace { void Search::init() { for (int i = 1; i < MAX_MOVES; ++i) - Reductions[i] = int((24.8 + std::log(Threads.size()) / 2) * std::log(i)); + Reductions[i] = int((24.8 + std::log(Threads.size())) * std::log(i)); } @@ -280,7 +280,7 @@ void MainThread::search() { std::map votes; Value minScore = this->rootMoves[0].score; - // Find out minimum score + // Find minimum score for (Thread* th: Threads) minScore = std::min(minScore, th->rootMoves[0].score); @@ -290,19 +290,20 @@ void MainThread::search() { votes[th->rootMoves[0].pv[0]] += (th->rootMoves[0].score - minScore + 14) * int(th->completedDepth); - if (bestThread->rootMoves[0].score >= VALUE_TB_WIN_IN_MAX_PLY) + if (abs(bestThread->rootMoves[0].score) >= VALUE_TB_WIN_IN_MAX_PLY) { - // Make sure we pick the shortest mate + // Make sure we pick the shortest mate / TB conversion or stave off mate the longest if (th->rootMoves[0].score > bestThread->rootMoves[0].score) bestThread = th; } else if ( th->rootMoves[0].score >= VALUE_TB_WIN_IN_MAX_PLY - || votes[th->rootMoves[0].pv[0]] > votes[bestThread->rootMoves[0].pv[0]]) + || ( th->rootMoves[0].score > VALUE_TB_LOSS_IN_MAX_PLY + && votes[th->rootMoves[0].pv[0]] > votes[bestThread->rootMoves[0].pv[0]])) bestThread = th; } } - previousScore = bestThread->rootMoves[0].score; + bestPreviousScore = bestThread->rootMoves[0].score; // Send again PV info if we have a new best thread if (bestThread != this) @@ -348,12 +349,12 @@ void Thread::search() { if (mainThread) { - if (mainThread->previousScore == VALUE_INFINITE) + if (mainThread->bestPreviousScore == VALUE_INFINITE) for (int i=0; i<4; ++i) mainThread->iterValue[i] = VALUE_ZERO; else for (int i=0; i<4; ++i) - mainThread->iterValue[i] = mainThread->previousScore; + mainThread->iterValue[i] = mainThread->bestPreviousScore; } size_t multiPV = Options["MultiPV"]; @@ -432,13 +433,13 @@ void Thread::search() { // Reset aspiration window starting size if (rootDepth >= 4) { - Value previousScore = rootMoves[pvIdx].previousScore; + Value prev = rootMoves[pvIdx].previousScore; delta = Value(21); - alpha = std::max(previousScore - delta,-VALUE_INFINITE); - beta = std::min(previousScore + delta, VALUE_INFINITE); + 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 + (102 - ct / 2) * previousScore / (abs(previousScore) + 157); + int dct = ct + (102 - ct / 2) * prev / (abs(prev) + 157); contempt = (us == WHITE ? make_score(dct, dct / 2) : -make_score(dct, dct / 2)); @@ -536,7 +537,7 @@ void Thread::search() { && !Threads.stop && !mainThread->stopOnPonderhit) { - double fallingEval = (332 + 6 * (mainThread->previousScore - bestValue) + double fallingEval = (332 + 6 * (mainThread->bestPreviousScore - bestValue) + 6 * (mainThread->iterValue[iterIdx] - bestValue)) / 704.0; fallingEval = Utility::clamp(fallingEval, 0.5, 1.5); @@ -625,7 +626,7 @@ namespace { Move ttMove, move, excludedMove, bestMove; Depth extension, newDepth; Value bestValue, value, ttValue, eval, maxValue; - bool ttHit, ttPv, inCheck, givesCheck, improving, didLMR, priorCapture; + bool ttHit, ttPv, formerPv, inCheck, givesCheck, improving, didLMR, priorCapture; bool captureOrPromotion, doFullDepthSearch, moveCountPruning, ttCapture, singularLMR; Piece movedPiece; int moveCount, captureCount, quietCount; @@ -695,6 +696,7 @@ namespace { ttMove = rootNode ? thisThread->rootMoves[thisThread->pvIdx].pv[0] : ttHit ? tte->move() : MOVE_NONE; ttPv = PvNode || (ttHit && tte->is_pv()); + formerPv = ttPv && !PvNode; if (ttPv && depth > 12 && ss->ply - 1 < MAX_LPH && !pos.captured_piece() && is_ok((ss-1)->currentMove)) thisThread->lowPlyHistory[ss->ply - 1][from_to((ss-1)->currentMove)] << stat_bonus(depth - 5); @@ -788,6 +790,8 @@ namespace { } } + CapturePieceToHistory& captureHistory = thisThread->captureHistory; + // Step 6. Static evaluation of the position if (inCheck) { @@ -867,7 +871,7 @@ namespace { if (nullValue >= beta) { - // Do not return unproven mate scores + // Do not return unproven mate or TB scores if (nullValue >= VALUE_TB_WIN_IN_MAX_PLY) nullValue = beta; @@ -897,12 +901,17 @@ namespace { && depth >= 5 && abs(beta) < VALUE_TB_WIN_IN_MAX_PLY) { - Value raisedBeta = std::min(beta + 189 - 45 * improving, VALUE_INFINITE); - MovePicker mp(pos, ttMove, raisedBeta - ss->staticEval, &thisThread->captureHistory); + Value raisedBeta = beta + 189 - 45 * improving; + assert(raisedBeta < VALUE_INFINITE); + MovePicker mp(pos, ttMove, raisedBeta - ss->staticEval, &captureHistory); int probCutCount = 0; - while ( (move = mp.next_move()) != MOVE_NONE - && probCutCount < 2 + 2 * cutNode) + while ( (move = mp.next_move()) != MOVE_NONE + && probCutCount < 2 + 2 * cutNode + && !( move == ttMove + && (tte->bound() & BOUND_LOWER) + && tte->depth() >= depth - 4 + && ttValue < raisedBeta)) if (move != excludedMove && pos.legal(move)) { assert(pos.capture_or_promotion(move)); @@ -953,7 +962,7 @@ moves_loop: // When in check, search starts from here MovePicker mp(pos, ttMove, depth, &thisThread->mainHistory, &thisThread->lowPlyHistory, - &thisThread->captureHistory, + &captureHistory, contHist, countermove, ss->killers, @@ -1008,12 +1017,12 @@ moves_loop: // When in check, search starts from here // Skip quiet moves if movecount exceeds our FutilityMoveCount threshold moveCountPruning = moveCount >= futility_move_count(improving, depth); + // Reduced depth of the next LMR search + int lmrDepth = std::max(newDepth - reduction(improving, depth, moveCount), 0); + if ( !captureOrPromotion && !givesCheck) { - // Reduced depth of the next LMR search - int lmrDepth = std::max(newDepth - reduction(improving, depth, moveCount), 0); - // Countermoves based pruning (~20 Elo) if ( lmrDepth < 4 + ((ss-1)->statScore > 0 || (ss-1)->moveCount == 1) && (*contHist[0])[movedPiece][to_sq(move)] < CounterMovePruneThreshold @@ -1033,8 +1042,18 @@ moves_loop: // When in check, search starts from here if (!pos.see_ge(move, Value(-(32 - std::min(lmrDepth, 18)) * lmrDepth * lmrDepth))) continue; } - else if (!pos.see_ge(move, Value(-194) * depth)) // (~25 Elo) - continue; + else + { + // Capture history based pruning when the move doesn't give check + if ( !givesCheck + && lmrDepth < 1 + && captureHistory[movedPiece][to_sq(move)][type_of(pos.piece_on(to_sq(move)))] < 0) + continue; + + // See based pruning + if (!pos.see_ge(move, Value(-194) * depth)) // (~25 Elo) + continue; + } } // Step 14. Extensions (~75 Elo) @@ -1054,8 +1073,8 @@ moves_loop: // When in check, search starts from here && tte->depth() >= depth - 3 && pos.legal(move)) { - Value singularBeta = ttValue - (((ttPv && !PvNode) + 4) * depth) / 2; - Depth singularDepth = (depth - 1 + 3 * (ttPv && !PvNode)) / 2; + Value singularBeta = ttValue - ((formerPv + 4) * depth) / 2; + Depth singularDepth = (depth - 1 + 3 * formerPv) / 2; ss->excludedMove = move; value = search(pos, ss, singularBeta - 1, singularBeta, singularDepth, cutNode); ss->excludedMove = MOVE_NONE; @@ -1095,6 +1114,12 @@ moves_loop: // When in check, search starts from here if (type_of(move) == CASTLING) extension = 1; + // Late irreversible move extension + if ( move == ttMove + && pos.rule50_count() > 80 + && (captureOrPromotion || type_of(movedPiece) == PAWN)) + extension = 2; + // Add extension to new depth newDepth += extension; @@ -1143,13 +1168,16 @@ moves_loop: // When in check, search starts from here if (ttPv) r -= 2; + if (moveCountPruning && !formerPv) + r++; + // Decrease reduction if opponent's move count is high (~5 Elo) if ((ss-1)->moveCount > 14) r--; // Decrease reduction if ttMove has been singularly extended (~3 Elo) if (singularLMR) - r -= 1 + (ttPv && !PvNode); + r -= 1 + formerPv; if (!captureOrPromotion) { @@ -1184,10 +1212,17 @@ moves_loop: // When in check, search starts from here // Decrease/increase reduction for moves with a good/bad history (~30 Elo) r -= ss->statScore / 16434; } - - // Increase reduction for captures/promotions if late move and at low depth - else if (depth < 8 && moveCount > 2) - r++; + 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()] + 200 * depth <= alpha) + r++; + } Depth d = Utility::clamp(newDepth - r, 1, newDepth); @@ -1367,7 +1402,7 @@ moves_loop: // When in check, search starts from here Move ttMove, move, bestMove; Depth ttDepth; Value bestValue, value, ttValue, futilityValue, futilityBase, oldAlpha; - bool ttHit, pvHit, inCheck, givesCheck, captureOrPromotion, evasionPrunable; + bool ttHit, pvHit, inCheck, givesCheck, captureOrPromotion; int moveCount; if (PvNode) @@ -1496,14 +1531,8 @@ moves_loop: // When in check, search starts from here } } - // Detect non-capture evasions that are candidates to be pruned - evasionPrunable = inCheck - && (depth != 0 || moveCount > 2) - && bestValue > VALUE_TB_LOSS_IN_MAX_PLY - && !pos.capture(move); - // Don't search moves with negative SEE values - if ( (!inCheck || evasionPrunable) && !pos.see_ge(move)) + if ( !inCheck && !pos.see_ge(move)) continue; // Speculative prefetch as early as possible