do more LMR extensions for PV nodes

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 83ed2aebcd43eec239056671b373579ebb2fbf8e..a487ed1305b1ccdc8aabe5b42858ec71799b5895 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1173,8 +1173,8 @@ moves_loop: // When in check, search starts here
 
           // In general we want to cap the LMR depth search at newDepth. But if
           // reductions are really negative and movecount is low, we allow this move
 
           // In general we want to cap the LMR depth search at newDepth. But if
           // reductions are really negative and movecount is low, we allow this move

-          // to be searched deeper than the first move, unless ttMove was extended by 2.
-          Depth d = std::clamp(newDepth - r, 1, newDepth + (r < -1 && moveCount <= 5 && !doubleExtension));
+          // to be searched deeper than the first move in specific cases.
+          Depth d = std::clamp(newDepth - r, 1, newDepth + (r < -1 && (moveCount <= 5 || (depth > 6 && PvNode)) && !doubleExtension));

 
           value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, true);
 
 
           value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, true);