Improve transposition table remplacement strategy

[stockfish] / src / tt.cpp

diff --git a/src/tt.cpp b/src/tt.cpp
index 1f495ca9d12be229aaef9a8171690c5ae5d3ad73..4af6c9f11a53d19212b1b7124ae215b4b47bd811 100644 (file)
--- a/src/tt.cpp
+++ b/src/tt.cpp
@@ -40,9 +40,9 @@ void TTEntry::save(Key k, Value v, bool pv, Bound b, Depth d, Move m, Value ev)
       move16 = (uint16_t)m;
 
   // Overwrite less valuable entries (cheapest checks first)
-  if (b == BOUND_EXACT
+  if (   b == BOUND_EXACT
       || (uint16_t)k != key16
-      || d - DEPTH_OFFSET > depth8 - 4)
+      || d - DEPTH_OFFSET + 2 * pv > depth8 - 4)
   {
       assert(d > DEPTH_OFFSET);
       assert(d < 256 + DEPTH_OFFSET);