X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fsearch.cpp;h=8a4db35185921776e4288e02e83c8744c2c35db7;hb=0a318cdddf8b6bdd05c2e0ee9b3b61a031d398ed;hp=28e16609203a7f8262d405ca9cabc6b3434dbf56;hpb=a6a9d828ab4cc35ca0f64207e2ff818a391d1939;p=stockfish diff --git a/src/search.cpp b/src/search.cpp index 28e16609..8a4db351 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -69,9 +69,9 @@ namespace { // Reductions lookup table, initialized at startup int Reductions[MAX_MOVES]; // [depth or moveNumber] - Depth reduction(bool i, Depth d, int mn, bool rangeReduction) { + Depth reduction(bool i, Depth d, int mn, bool rangeReduction, Value delta, Value rootDelta) { int r = Reductions[d] * Reductions[mn]; - return (r + 534) / 1024 + (!i && r > 904) + rangeReduction; + return (r + 1358 - int(delta) * 1024 / int(rootDelta)) / 1024 + (!i && r > 904) + rangeReduction; } constexpr int futility_move_count(bool improving, Depth depth) { @@ -141,7 +141,7 @@ namespace { Value value_from_tt(Value v, int ply, int r50c); void update_pv(Move* pv, Move move, Move* childPv); void update_continuation_histories(Stack* ss, Piece pc, Square to, int bonus); - void update_quiet_stats(const Position& pos, Stack* ss, Move move, int bonus, int depth); + void update_quiet_stats(const Position& pos, Stack* ss, Move move, int bonus); void update_all_stats(const Position& pos, Stack* ss, Move bestMove, Value bestValue, Value beta, Square prevSq, Move* quietsSearched, int quietCount, Move* capturesSearched, int captureCount, Depth depth); @@ -260,6 +260,7 @@ void MainThread::search() { bestThread = Threads.get_best_thread(); bestPreviousScore = bestThread->rootMoves[0].score; + bestPreviousAverageScore = bestThread->rootMoves[0].averageScore; // Send again PV info if we have a new best thread if (bestThread != this) @@ -316,9 +317,6 @@ void Thread::search() { mainThread->iterValue[i] = mainThread->bestPreviousScore; } - std::copy(&lowPlyHistory[2][0], &lowPlyHistory.back().back() + 1, &lowPlyHistory[0][0]); - std::fill(&lowPlyHistory[MAX_LPH - 2][0], &lowPlyHistory.back().back() + 1, 0); - size_t multiPV = size_t(Options["MultiPV"]); Skill skill(Options["Skill Level"], Options["UCI_LimitStrength"] ? int(Options["UCI_Elo"]) : 0); @@ -489,8 +487,8 @@ void Thread::search() { && !Threads.stop && !mainThread->stopOnPonderhit) { - double fallingEval = (318 + 6 * (mainThread->bestPreviousScore - bestValue) - + 6 * (mainThread->iterValue[iterIdx] - bestValue)) / 825.0; + double fallingEval = (142 + 12 * (mainThread->bestPreviousAverageScore - bestValue) + + 6 * (mainThread->iterValue[iterIdx] - bestValue)) / 825.0; fallingEval = std::clamp(fallingEval, 0.5, 1.5); // If the bestMove is stable over several iterations, reduce time accordingly @@ -589,8 +587,7 @@ namespace { Depth extension, newDepth; Value bestValue, value, ttValue, eval, maxValue, probCutBeta; bool givesCheck, improving, didLMR, priorCapture; - bool captureOrPromotion, doFullDepthSearch, moveCountPruning, - ttCapture, singularQuietLMR; + bool captureOrPromotion, doFullDepthSearch, moveCountPruning, ttCapture; Piece movedPiece; int moveCount, captureCount, quietCount, bestMoveCount, improvement; @@ -666,14 +663,6 @@ namespace { if (!excludedMove) ss->ttPv = PvNode || (ss->ttHit && tte->is_pv()); - // 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 - && !priorCapture - && is_ok((ss-1)->currentMove)) - thisThread->lowPlyHistory[ss->ply - 1][from_to((ss-1)->currentMove)] << stat_bonus(depth - 5); - // At non-PV nodes we check for an early TT cutoff if ( !PvNode && ss->ttHit @@ -689,7 +678,7 @@ namespace { { // Bonus for a quiet ttMove that fails high if (!ttCapture) - update_quiet_stats(pos, ss, ttMove, stat_bonus(depth), depth); + update_quiet_stats(pos, ss, ttMove, stat_bonus(depth)); // Extra penalty for early quiet moves of the previous ply if ((ss-1)->moveCount <= 2 && !priorCapture) @@ -973,15 +962,13 @@ moves_loop: // When in check, search starts here Move countermove = thisThread->counterMoves[pos.piece_on(prevSq)][prevSq]; MovePicker mp(pos, ttMove, depth, &thisThread->mainHistory, - &thisThread->lowPlyHistory, &captureHistory, contHist, countermove, - ss->killers, - ss->ply); + ss->killers); value = bestValue; - singularQuietLMR = moveCountPruning = false; + moveCountPruning = false; // Indicate PvNodes that will probably fail low if the node was searched // at a depth equal or greater than the current depth, and the result of this search was a fail low. @@ -1028,6 +1015,8 @@ moves_loop: // When in check, search starts here // Calculate new depth for this move newDepth = depth - 1; + Value delta = beta - alpha; + // Step 13. Pruning at shallow depth (~200 Elo). Depth conditions are important for mate finding. if ( !rootNode && pos.non_pawn_material(us) @@ -1037,7 +1026,7 @@ moves_loop: // When in check, search starts here moveCountPruning = moveCount >= futility_move_count(improving, depth); // Reduced depth of the next LMR search - int lmrDepth = std::max(newDepth - reduction(improving, depth, moveCount, rangeReduction > 2), 0); + int lmrDepth = std::max(newDepth - reduction(improving, depth, moveCount, rangeReduction > 2, delta, thisThread->rootDelta), 0); if ( captureOrPromotion || givesCheck) @@ -1065,8 +1054,6 @@ moves_loop: // When in check, search starts here history += thisThread->mainHistory[us][from_to(move)]; - lmrDepth = std::max(0, lmrDepth - (beta - alpha < thisThread->rootDelta / 4)); - // Futility pruning: parent node (~5 Elo) if ( !ss->inCheck && lmrDepth < 8 @@ -1087,7 +1074,7 @@ moves_loop: // When in check, search starts here // 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 >= 7 + && depth >= 6 + 2 * (PvNode && tte->is_pv()) && move == ttMove && !excludedMove // Avoid recursive singular search /* && ttValue != VALUE_NONE Already implicit in the next condition */ @@ -1105,7 +1092,6 @@ moves_loop: // When in check, search starts here if (value < singularBeta) { extension = 1; - singularQuietLMR = !ttCapture; // Avoid search explosion by limiting the number of double extensions if ( !PvNode @@ -1163,6 +1149,8 @@ moves_loop: // When in check, search starts here // Step 15. Make the move pos.do_move(move, st, givesCheck); + bool doDeeperSearch = false; + // Step 16. Late moves reduction / extension (LMR, ~200 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 @@ -1173,12 +1161,11 @@ moves_loop: // When in check, search starts here || !captureOrPromotion || (cutNode && (ss-1)->moveCount > 1))) { - Depth r = reduction(improving, depth, moveCount, rangeReduction > 2); + Depth r = reduction(improving, depth, moveCount, rangeReduction > 2, delta, thisThread->rootDelta); // Decrease reduction at some PvNodes (~2 Elo) if ( PvNode - && bestMoveCount <= 3 - && beta - alpha >= thisThread->rootDelta / 4) + && bestMoveCount <= 3) r--; // Decrease reduction if position is or has been on the PV @@ -1187,18 +1174,10 @@ moves_loop: // When in check, search starts here && !likelyFailLow) r -= 2; - // Increase reduction at non-PV nodes - if (!PvNode) - r++; - // Decrease reduction if opponent's move count is high (~1 Elo) if ((ss-1)->moveCount > 13) r--; - // Decrease reduction if ttMove has been singularly extended (~1 Elo) - if (singularQuietLMR) - r--; - // Increase reduction for cut nodes (~3 Elo) if (cutNode && move != ss->killers[0]) r += 2; @@ -1235,6 +1214,7 @@ moves_loop: // When in check, search starts here // If the son is reduced and fails high it will be re-searched at full depth doFullDepthSearch = value > alpha && d < newDepth; + doDeeperSearch = value > alpha + 88; didLMR = true; } else @@ -1246,7 +1226,7 @@ moves_loop: // When in check, search starts here // Step 17. Full depth search when LMR is skipped or fails high if (doFullDepthSearch) { - value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode); + value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth + doDeeperSearch, !cutNode); // If the move passed LMR update its stats if (didLMR && !captureOrPromotion) @@ -1378,7 +1358,15 @@ moves_loop: // When in check, search starts here // Bonus for prior countermove that caused the fail low else if ( (depth >= 3 || PvNode) && !priorCapture) - update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, stat_bonus(depth) * (1 + (PvNode || cutNode))); + { + //Assign extra bonus if current node is PvNode or cutNode + //or fail low was really bad + bool extraBonus = PvNode + || cutNode + || bestValue < alpha - 94 * depth; + + update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, stat_bonus(depth) * (1 + extraBonus)); + } if (PvNode) bestValue = std::min(bestValue, maxValue); @@ -1702,7 +1690,7 @@ moves_loop: // When in check, search starts 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); + update_quiet_stats(pos, ss, bestMove, bonus2); // Decrease stats for all non-best quiet moves for (int i = 0; i < quietCount; ++i) @@ -1749,7 +1737,7 @@ moves_loop: // When in check, search starts here // update_quiet_stats() updates move sorting heuristics - void update_quiet_stats(const Position& pos, Stack* ss, Move move, int bonus, int depth) { + void update_quiet_stats(const Position& pos, Stack* ss, Move move, int bonus) { // Update killers if (ss->killers[0] != move) @@ -1769,10 +1757,6 @@ moves_loop: // When in check, search starts here 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); } // When playing with strength handicap, choose best move among a set of RootMoves