Added EnableTranspositionTable UCI option to enable/disable transposition table.

src/tt.cpp

@@ -28,6 +28,10 @@
 
 TranspositionTable TT; // Our global transposition table
 
+#ifdef EVAL_LEARN
+bool TranspositionTable::enable_transposition_table = true;
+#endif
+
 /// TTEntry::save() populates the TTEntry with a new node's data, possibly
 /// overwriting an old position. Update is not atomic and can be racy.
 
@@ -116,6 +120,13 @@ void TranspositionTable::clear() {
 
 TTEntry* TranspositionTable::probe(const Key key, bool& found) const {
 
+#ifdef EVAL_LEARN
+  if (!enable_transposition_table) {
+      found = false;
+      return first_entry(0);
+  }
+#endif
+
   TTEntry* const tte = first_entry(key);
   const uint16_t key16 = (uint16_t)key;  // Use the low 16 bits as key inside the cluster