If move is a main killer and we have a good history, decrease reduction.
STC: https://tests.stockfishchess.org/tests/view/
63d38b37721fe2bff693069a
LLR: 2.95 (-2.94,2.94) <0.00,2.00>
Total: 46688 W: 12542 L: 12222 D: 21924
Ptnml(0-2): 126, 5013, 12769, 5287, 149
LTC: https://tests.stockfishchess.org/tests/view/
63d471e2bde6e5f3cb4be5d3
LLR: 2.93 (-2.94,2.94) <0.50,2.50>
Total: 130976 W: 35033 L: 34555 D: 61388
Ptnml(0-2): 38, 12551, 39833, 13027, 39
closes https://github.com/official-stockfish/Stockfish/pull/4369
Bench:
4069938
if ((ss+1)->cutoffCnt > 3)
r++;
+ // Decrease reduction if move is a killer and we have a good history
+ if (move == ss->killers[0]
+ && (*contHist[0])[movedPiece][to_sq(move)] >= 3600)
+ r--;
+
ss->statScore = 2 * thisThread->mainHistory[us][from_to(move)]
+ (*contHist[0])[movedPiece][to_sq(move)]
+ (*contHist[1])[movedPiece][to_sq(move)]