Extend irreversible moves

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 4abc60692e628ef258e3d12d58bf6f67a7c2f435..4073f21d828cf060561b6106435c092d4e9aeaf2 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1110,6 +1110,12 @@ moves_loop: // When in check, search starts from here
       if (type_of(move) == CASTLING)
           extension = 1;
 
+      // Late irreversible move extension
+      if (   move == ttMove
+          && pos.rule50_count() > 80
+          && (captureOrPromotion || type_of(movedPiece) == PAWN))
+          extension = 2;
+
       // Add extension to new depth
       newDepth += extension;