Remove castling extension

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 4aeadc28a7802c506309091f8371ad92715d7bf9..17cd0a73b61d596897b5e13e704490f85bef8d48 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -520,7 +520,7 @@ void Thread::search() {
               totBestMoveChanges += th->bestMoveChanges;
               th->bestMoveChanges = 0;
           }
-          double bestMoveInstability = 1 + totBestMoveChanges / Threads.size();
+          double bestMoveInstability = 1 + 2 * totBestMoveChanges / Threads.size();
 
           double totalTime = rootMoves.size() == 1 ? 0 :
                              Time.optimum() * fallingEval * reduction * bestMoveInstability;
@@ -654,9 +654,7 @@ namespace {
     // starts with statScore = 0. Later grandchildren start with the last calculated
     // statScore of the previous grandchild. This influences the reduction rules in
     // LMR which are based on the statScore of parent position.
-    if (rootNode)
-        (ss+4)->statScore = 0;
-    else
+    if (!rootNode)
         (ss+2)->statScore = 0;
 
     // Step 4. Transposition table lookup. We don't want the score of a partial
@@ -1129,11 +1127,6 @@ moves_loop: // When in check, search starts from here
                && pos.non_pawn_material() <= 2 * RookValueMg)
           extension = 1;
 
-      // Castling extension
-      if (   type_of(move) == CASTLING
-          && popcount(pos.pieces(us) & ~pos.pieces(PAWN) & (to_sq(move) & KingSide ? KingSide : QueenSide)) <= 2)
-          extension = 1;
-
       // Late irreversible move extension
       if (   move == ttMove
           && pos.rule50_count() > 80