Do more futility pruning for cutNodes that are not in TT

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 61c75d7dd9fc82d07598a4a328c7b59fdb1c2fb7..8fdaca7cff046089eefc13365dd97ebf99c3d4b3 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -63,8 +63,8 @@ namespace {
   enum NodeType { NonPV, PV, Root };
 
   // Futility margin
-  Value futility_margin(Depth d, bool improving) {
-    return Value(140 * (d - improving));
+  Value futility_margin(Depth d, bool noTtCutNode, bool improving) {
+    return Value((140 - 40 * noTtCutNode) * (d - improving));
   }
 
   // Reductions lookup table initialized at startup
@@ -767,7 +767,7 @@ namespace {
     // The depth condition is important for mate finding.
     if (   !ss->ttPv
         &&  depth < 9
-        &&  eval - futility_margin(depth, improving) - (ss-1)->statScore / 306 >= beta
+        &&  eval - futility_margin(depth, cutNode && !ss->ttHit, improving) - (ss-1)->statScore / 306 >= beta
         &&  eval >= beta
         &&  eval < 24923) // larger than VALUE_KNOWN_WIN, but smaller than TB wins
         return eval;