- // 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));
+ 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)]
+ - 4334;
+
+ // Decrease/increase reduction for moves with a good/bad history (~30 Elo)
+ r -= ss->statScore / 15914;
+
+ // 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 (this may lead to hidden double extensions).
+ int deeper = r >= -1 ? 0
+ : moveCount <= 4 ? 2
+ : PvNode && depth > 4 ? 1
+ : cutNode && moveCount <= 8 ? 1
+ : 0;
+
+ Depth d = std::clamp(newDepth - r, 1, newDepth + deeper);