Key posKey;
Move ttMove, move, excludedMove, bestMove;
Depth extension, newDepth, predictedDepth;
- Value bestValue, value, ttValue, eval, nullValue, futilityValue;
+ Value bestValue, value, ttValue, eval, nullValue;
bool ttHit, inCheck, givesCheck, singularExtensionNode, improving;
- bool captureOrPromotion, doFullDepthSearch;
+ bool captureOrPromotion, doFullDepthSearch, moveCountPruning;
Piece moved_piece;
int moveCount, quietCount;
? ci.checkSquares[type_of(pos.piece_on(from_sq(move)))] & to_sq(move)
: pos.gives_check(move, ci);
+ moveCountPruning = depth < 16 * ONE_PLY
+ && moveCount >= FutilityMoveCounts[improving][depth];
+
// Step 12. Extend checks
- if (givesCheck && pos.see_sign(move) >= VALUE_ZERO)
+ if ( givesCheck
+ && ( moveCount == 1
+ || (!moveCountPruning && pos.see_sign(move) >= VALUE_ZERO)))
extension = ONE_PLY;
// Singular extension search. If all moves but one fail low on a search of
&& bestValue > VALUE_MATED_IN_MAX_PLY)
{
// Move count based pruning
- if ( depth < 16 * ONE_PLY
- && moveCount >= FutilityMoveCounts[improving][depth])
+ if (moveCountPruning)
continue;
// Countermoves based pruning
predictedDepth = std::max(newDepth - reduction<PvNode>(improving, depth, moveCount), DEPTH_ZERO);
// Futility pruning: parent node
- if (predictedDepth < 7 * ONE_PLY)
- {
- futilityValue = ss->staticEval + futility_margin(predictedDepth) + 256;
-
- if (futilityValue <= alpha)
- {
- bestValue = std::max(bestValue, futilityValue);
- continue;
- }
- }
+ if ( predictedDepth < 7 * ONE_PLY
+ && ss->staticEval + futility_margin(predictedDepth) + 256 <= alpha)
+ continue;
// Prune moves with negative SEE at low depths
if (predictedDepth < 4 * ONE_PLY && pos.see_sign(move) < VALUE_ZERO)
// Increase reduction for cut nodes
if (!PvNode && cutNode)
- r += ONE_PLY;
+ r += 2 * ONE_PLY;
// Decrease reduction for moves that escape a capture. Filter out
// castling moves, because they are coded as "king captures rook" and
else if ( type_of(move) == NORMAL
&& type_of(pos.piece_on(to_sq(move))) != PAWN
&& pos.see(make_move(to_sq(move), from_sq(move))) < VALUE_ZERO)
- r -= ONE_PLY;
+ r -= 2 * ONE_PLY;
// Decrease/increase reduction for moves with a good/bad history
int rHist = (val - 10000) / 20000;