X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Ftt.cpp;h=8c5f3e347a5353756868e8a2c0877774015647f6;hp=d7b3b7d5b099a7dd91b39808c780067c56baf86f;hb=72c7595f8ac72c7831ee319b8b0bc46404c5fc27;hpb=6a8e46d53efca6dd56a396b32f43bef9f95127d6

diff --git a/src/tt.cpp b/src/tt.cpp
index d7b3b7d5..8c5f3e34 100644
--- a/src/tt.cpp
+++ b/src/tt.cpp
@@ -101,9 +101,10 @@ void TranspositionTable::clear() {
 /// the least valuable of the four entries in a cluster.  A TTEntry t1 is
 /// considered to be more valuable than a TTEntry t2 if t1 is from the
 /// current search and t2 is from a previous search, or if the depth of t1
-/// is bigger than the depth of t2.
+/// is bigger than the depth of t2. A TTEntry of type VALUE_TYPE_EVAL
+/// never replaces another entry for the same position.
 
-TTEntry* TranspositionTable::store(const Position &pos, Value v, Depth d,
+void TranspositionTable::store(const Position &pos, Value v, Depth d,
                                Move m, ValueType type) {
   TTEntry *tte, *replace;
 
@@ -112,11 +113,16 @@ TTEntry* TranspositionTable::store(const Position &pos, Value v, Depth d,
   {
     if (!tte->key() || tte->key() == pos.get_key()) // empty or overwrite old
     {
+        // Do not overwrite position entry when VALUE_TYPE_EVAL
+        if (   tte->key()
+            && type == VALUE_TYPE_EVAL)
+            return;
+
         if (m == MOVE_NONE)
             m = tte->move();
 
         *tte = TTEntry(pos.get_key(), v, type, d, m, generation);
-        return tte;
+        return;
     }
     else if (i == 0)  // replace would be a no-op in this common case
         continue;
@@ -130,7 +136,6 @@ TTEntry* TranspositionTable::store(const Position &pos, Value v, Depth d,
   }
   *replace = TTEntry(pos.get_key(), v, type, d, m, generation);
   writes++;
-  return replace;
 }