Use CounterMoveHistory when calculating LMR for cut nodes

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index cae89c6a929014ce9364c60a444f188a396341c7..c5da0d4f7473d512ef582b89f438296317faa54c 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -585,7 +585,7 @@ namespace {
     ss->ttMove = ttMove = RootNode ? RootMoves[PVIdx].pv[0] : ttHit ? tte->move() : MOVE_NONE;
     ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE;
 
-    // At non-PV nodes we check for a fail high/low. We don't probe at PV nodes
+    // At non-PV nodes we check for a fail high/low. We don't prune at PV nodes
     if (  !PvNode
         && ttHit
         && tte->depth() >= depth
@@ -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])
@@ -1439,6 +1441,10 @@ moves_loop: // When in check and at SpNode search starts from here
     {
         Square prevPrevSq = to_sq((ss-2)->currentMove);
         Followupmoves.update(pos.piece_on(prevPrevSq), prevPrevSq, move);
+
+        // 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);
     }
   }