Use CounterMoveHistory when calculating LMR for cut nodes

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index b0e2c950fe7354c784cd14689ab7c3cbb7bed6b4..c5da0d4f7473d512ef582b89f438296317faa54c 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -964,7 +964,9 @@ moves_loop: // When in check and at SpNode search starts from here
           ss->reduction = reduction<PvNode>(improving, depth, moveCount);
 
           if (   (!PvNode && cutNode)
-              ||  History[pos.piece_on(to_sq(move))][to_sq(move)] < VALUE_ZERO)
+              ||  History[pos.piece_on(to_sq(move))][to_sq(move)] < VALUE_ZERO
+              ||  CounterMovesHistory[pos.piece_on(prevMoveSq)][prevMoveSq][pos.piece_on(to_sq(move))][to_sq(move)]
+                + History[pos.piece_on(to_sq(move))][to_sq(move)] < VALUE_ZERO)
               ss->reduction += ONE_PLY;
 
           if (move == countermoves[0] || move == countermoves[1])
@@ -1437,16 +1439,12 @@ moves_loop: // When in check and at SpNode search starts from here
 
     if (is_ok((ss-2)->currentMove) && (ss-1)->currentMove == (ss-1)->ttMove)
     {
-        Value bonus2 = Value(((depth+1) / ONE_PLY) * ((depth+1) / ONE_PLY));
-
         Square prevPrevSq = to_sq((ss-2)->currentMove);
         Followupmoves.update(pos.piece_on(prevPrevSq), prevPrevSq, move);
 
-        Square prevMoveSq = to_sq((ss-1)->currentMove);
-        Piece prevMovePiece = pos.piece_on(prevMoveSq);
-
-        HistoryStats& cmh2 = CounterMovesHistory[pos.piece_on(prevPrevSq)][prevPrevSq];
-        cmh2.update(prevMovePiece, prevMoveSq, -bonus2);
+        // Extra penalty for TT move in previous ply when it gets refuted
+        HistoryStats& ttMoveCmh = CounterMovesHistory[pos.piece_on(prevPrevSq)][prevPrevSq];
+        ttMoveCmh.update(pos.piece_on(prevSq), prevSq, -bonus - 2 * depth / ONE_PLY - 1);
     }
   }