Extend checks more when below alpha

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 4b0a9fe8b60676b96c7c5dcc9bda19f9d5bcd6b8..4384b58dd5c89a21ab10d40ccb0de6c88525fc82 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -837,7 +837,7 @@ moves_loop: // When in check and at SpNode search starts from here
           ext = ONE_PLY;
 
       else if (givesCheck && pos.see_sign(move) >= 0)
-          ext = ONE_PLY / 2;
+          ext = inCheck || ss->staticEval <= alpha ? ONE_PLY : ONE_PLY / 2;
 
       // Singular extension search. If all moves but one fail low on a search of
       // (alpha-s, beta-s), and just one fails high on (alpha, beta), then that move