Exclude blockers for king from mobility area

This patch excludes blockers for king from mobility area. It was tried a couple
of times by now but now it passed. Performance is not enormously good but this
patch makes a lot of sence - blockers for king can't really move until king moves
(in most cases) so logic behind it is the same as behind excluding king square
from mobility area.

STC
http://tests.stockfishchess.org/tests/view/5dec388651219d7befdc76be
LLR: 2.95 (-2.94,2.94) [-1.50,4.50]
Total: 6155 W: 1428 L: 1300 D: 3427

LTC
http://tests.stockfishchess.org/tests/view/5dec4a3151219d7befdc76d3
LLR: 2.95 (-2.94,2.94) [0.00,3.50]
Total: 120800 W: 19636 L: 19134 D: 82030

Bench: 5173081

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 1988e20ec50ce117fc72fcdc7aa9691ef5d2694e..20d1059e56857283714e10ebd6eedd588d30e4b5 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -225,9 +225,9 @@ namespace {
     // Find our pawns that are blocked or on the first two ranks
     Bitboard b = pos.pieces(Us, PAWN) & (shift<Down>(pos.pieces()) | LowRanks);
 
-    // Squares occupied by those pawns, by our king or queen or controlled by
-    // enemy pawns are excluded from the mobility area.
-    mobilityArea[Us] = ~(b | pos.pieces(Us, KING, QUEEN) | pe->pawn_attacks(Them));
+    // Squares occupied by those pawns, by our king or queen, by blockers to attacks on our king
+    // or controlled by enemy pawns are excluded from the mobility area.
+    mobilityArea[Us] = ~(b | pos.pieces(Us, KING, QUEEN) | pos.blockers_for_king(Us) | pe->pawn_attacks(Them));
 
     // Initialize attackedBy[] for king and pawns
     attackedBy[Us][KING] = pos.attacks_from<KING>(ksq);