X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fsearch.cpp;h=ed5dd6c2c7ad5aab3e39b26cb038833c3a6b58d2;hb=b7b6b4ba18bc9d291c2c2fd300c22a3e008dcbb2;hp=fef1b518160abf00e7e6e4ac14a7e656d2ed4046;hpb=36f8d3806bb1c6e498ac8fd1a746c1714d1485a3;p=stockfish diff --git a/src/search.cpp b/src/search.cpp index fef1b518..ed5dd6c2 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -779,8 +779,10 @@ namespace { ? ss->staticEval > (ss-4)->staticEval || (ss-4)->staticEval == VALUE_NONE : ss->staticEval > (ss-2)->staticEval; - // Step 7. Futility pruning: child node (~50 Elo) + // Step 7. Futility pruning: child node (~50 Elo). + // The depth condition is important for mate finding. if ( !PvNode + && depth < 9 && eval - futility_margin(depth, improving) >= beta && eval < VALUE_KNOWN_WIN) // Do not return unproven wins return eval; @@ -799,7 +801,7 @@ namespace { assert(eval - beta >= 0); // Null move dynamic reduction based on depth and value - Depth R = (1090 + 81 * depth) / 256 + std::min(int(eval - beta) / 205, 3); + Depth R = std::min(int(eval - beta) / 205, 3) + depth / 3 + 4; ss->currentMove = MOVE_NULL; ss->continuationHistory = &thisThread->continuationHistory[0][0][NO_PIECE][0]; @@ -907,7 +909,7 @@ namespace { && !ttMove) depth -= 2; -moves_loop: // When in check, search starts from here +moves_loop: // When in check, search starts here ttCapture = ttMove && pos.capture_or_promotion(ttMove); @@ -989,7 +991,7 @@ moves_loop: // When in check, search starts from here // Calculate new depth for this move newDepth = depth - 1; - // Step 13. Pruning at shallow depth (~200 Elo) + // Step 13. Pruning at shallow depth (~200 Elo). Depth conditions are important for mate finding. if ( !rootNode && pos.non_pawn_material(us) && bestValue > VALUE_TB_LOSS_IN_MAX_PLY) @@ -1016,22 +1018,20 @@ moves_loop: // When in check, search starts from here else { // Continuation history based pruning (~20 Elo) - if ( lmrDepth < 5 - && (*contHist[0])[movedPiece][to_sq(move)] < CounterMovePruneThreshold - && (*contHist[1])[movedPiece][to_sq(move)] < CounterMovePruneThreshold) + if (lmrDepth < 5 + && (*contHist[0])[movedPiece][to_sq(move)] + + (*contHist[1])[movedPiece][to_sq(move)] + + (*contHist[3])[movedPiece][to_sq(move)] < -3000 * depth + 3000) continue; // Futility pruning: parent node (~5 Elo) if ( !ss->inCheck - && ss->staticEval + 174 + 157 * 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)] / 3 < 28255) + && lmrDepth < 7 + && ss->staticEval + 174 + 157 * lmrDepth <= alpha) continue; // Prune moves with negative SEE (~20 Elo) - if (!pos.see_ge(move, Value(-(30 - std::min(lmrDepth, 18)) * lmrDepth * lmrDepth))) + if (!pos.see_ge(move, Value(-21 * lmrDepth * lmrDepth - 21 * lmrDepth))) continue; } } @@ -1094,6 +1094,14 @@ moves_loop: // When in check, search starts from here return beta; } } + + // Capture extensions for PvNodes and cutNodes + else if ( (PvNode || cutNode) + && captureOrPromotion + && moveCount != 1) + extension = 1; + + // Check extensions else if ( givesCheck && depth > 6 && abs(ss->staticEval) > Value(100)) @@ -1159,27 +1167,23 @@ moves_loop: // When in check, search starts from here if (cutNode && move != ss->killers[0]) r += 2; - if (!captureOrPromotion) - { - // Increase reduction if ttMove is a capture (~3 Elo) - if (ttCapture) - r++; - - ss->statScore = thisThread->mainHistory[us][from_to(move)] - + (*contHist[0])[movedPiece][to_sq(move)] - + (*contHist[1])[movedPiece][to_sq(move)] - + (*contHist[3])[movedPiece][to_sq(move)] - - 4923; - - // Decrease/increase reduction for moves with a good/bad history (~30 Elo) - if (!ss->inCheck) - r -= ss->statScore / 14721; - } + // Increase reduction if ttMove is a capture (~3 Elo) + if (ttCapture) + r++; + + ss->statScore = thisThread->mainHistory[us][from_to(move)] + + (*contHist[0])[movedPiece][to_sq(move)] + + (*contHist[1])[movedPiece][to_sq(move)] + + (*contHist[3])[movedPiece][to_sq(move)] + - 4923; + + // Decrease/increase reduction for moves with a good/bad history (~30 Elo) + r -= ss->statScore / 14721; // In general we want to cap the LMR depth search at newDepth. But if // reductions are really negative and movecount is low, we allow this move - // to be searched deeper than the first move, unless ttMove was extended by 2. - Depth d = std::clamp(newDepth - r, 1, newDepth + (r < -1 && moveCount <= 5 && !doubleExtension)); + // to be searched deeper than the first move in specific cases. + Depth d = std::clamp(newDepth - r, 1, newDepth + (r < -1 && (moveCount <= 5 || (depth > 6 && PvNode)) && !doubleExtension)); value = -search(pos, ss+1, -(alpha+1), -alpha, d, true); @@ -1321,7 +1325,7 @@ moves_loop: // When in check, search starts from 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)); + update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, stat_bonus(depth) * (1 + (PvNode || cutNode))); if (PvNode) bestValue = std::min(bestValue, maxValue); @@ -1472,6 +1476,10 @@ moves_loop: // When in check, search starts from here { assert(is_ok(move)); + // Check for legality + if (!pos.legal(move)) + continue; + givesCheck = pos.gives_check(move); captureOrPromotion = pos.capture_or_promotion(move); @@ -1510,13 +1518,6 @@ 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 (!pos.legal(move)) - { - moveCount--; - continue; - } - ss->currentMove = move; ss->continuationHistory = &thisThread->continuationHistory[ss->inCheck] [captureOrPromotion]