From: Reuven Peleg <reuvenpe2005@gmail.com>
Date: Fri, 19 Jul 2013 15:01:07 +0000 (+0200)
Subject: Microptimize gives_check() for castling case
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=1a8f63a8963fa9c3afd043f4c611df8a5afcf038

Microptimize gives_check() for castling case

Without patch we have 333198 nps, with patch 334249.

A very small +0.3%, not a lot manily becuase this is a
side path that is taken very few times.

Anyhow idea is correct becuase first 'quick' condition
has an hit rate of about 95%.

No functional change.
---

diff --git a/src/position.cpp b/src/position.cpp
index 1273a62f..ad7ed3d9 100644
--- a/src/position.cpp
+++ b/src/position.cpp
@@ -690,9 +690,9 @@ bool Position::move_gives_check(Move m, const CheckInfo& ci) const {
       Square rfrom = to; // 'King captures the rook' notation
       Square kto = relative_square(us, rfrom > kfrom ? SQ_G1 : SQ_C1);
       Square rto = relative_square(us, rfrom > kfrom ? SQ_F1 : SQ_D1);
-      Bitboard b = (pieces() ^ kfrom ^ rfrom) | rto | kto;
 
-      return attacks_bb<ROOK>(rto, b) & ksq;
+      return   (PseudoAttacks[ROOK][rto] & ksq)
+            && (attacks_bb<ROOK>(rto, (pieces() ^ kfrom ^ rfrom) | rto | kto) & ksq);
   }
   default:
       assert(false);