Simplify Castle Extension

Remove depth condition in castle extension, also don't extend if Singular Extension and Check Extansion fail to extend. STC: LLR: 2.96 (-2.94,2.94) [-3.00,1.00] Total: 42070 W: 9118 L: 9036 D: 23916 http://tests.stockfishchess.org/tests/view/5be899cc0ebc595e0ae32f07 LTC: LLR: 2.96 (-2.94,2.94) [-3.00,1.00] Total: 78278 W: 12490 L: 12458 D: 53330 http://tests.stockfishchess.org/tests/view/5be8ac420ebc595e0ae33010 Bench: 3611041
official-stockfish · Nov 19, 2018 · 4111f36 · 4111f36
1 parent 0e508f3
commit 4111f36
Show file tree

Hide file tree

Showing 2 changed files with 3 additions and 4 deletions.
diff --git a/src/evaluate.cpp b/src/evaluate.cpp
@@ -257,6 +257,7 @@ namespace {
     attackedBy[Us][PAWN] = pe->pawn_attacks(Us);
     attackedBy[Us][ALL_PIECES] = attackedBy[Us][KING] | attackedBy[Us][PAWN];
     attackedBy2[Us]            = attackedBy[Us][KING] & attackedBy[Us][PAWN];
+
     kingRing[Us] = kingAttackersCount[Them] = 0;
 
     // Init our king safety tables only if we are going to use them

diff --git a/src/search.cpp b/src/search.cpp
@@ -944,10 +944,8 @@ namespace {
                &&  pos.see_ge(move))
           extension = ONE_PLY;
 
-      // Extension for king moves that change castling rights
-      if (   pos.can_castle(us)
-          && type_of(movedPiece) == KING
-          && depth < 12 * ONE_PLY)
+      else if (   pos.can_castle(us) // Extension for king moves that change castling rights
+               && type_of(movedPiece) == KING)
           extension = ONE_PLY;
 
       // Calculate new depth for this move