Reintroduce doEvenDeeperSearch

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index b2a5b9401bef1dc6b92786eca7b615cdc00810bd..4507460a5b639e40573e6af83e35b6f70eaa6767 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1066,7 +1066,7 @@ moves_loop: // When in check, search starts here
                   // Avoid search explosion by limiting the number of double extensions
                   if (  !PvNode
                       && value < singularBeta - 25
-                      && ss->doubleExtensions <= 9)
+                      && ss->doubleExtensions <= 10)
                   {
                       extension = 2;
                       depth += depth < 12;
@@ -1190,9 +1190,11 @@ moves_loop: // When in check, search starts here
               // Adjust full depth search based on LMR results - if result
               // was good enough search deeper, if it was bad enough search shallower
               const bool doDeeperSearch = value > (alpha + 64 + 11 * (newDepth - d));
-              const bool doEvenDeeperSearch = value > alpha + 582;
+              const bool doEvenDeeperSearch = value > alpha + 582 && ss->doubleExtensions <= 5;
               const bool doShallowerSearch = value < bestValue + newDepth;
 
+              ss->doubleExtensions = ss->doubleExtensions + doEvenDeeperSearch;
+
               newDepth += doDeeperSearch - doShallowerSearch + doEvenDeeperSearch;
 
               if (newDepth > d)