From: Alain SAVARD <support@multicim.com>
Date: Sat, 18 Apr 2015 21:12:56 +0000 (+0100)
Subject: Exclude queen from Rook Contact Check computation
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=078625e33389536addc9f94b7fc197230ef2f0fb;hp=6c040c821a50475840607ef5f11c270ee21d61da;ds=sidebyside

Exclude queen from Rook Contact Check computation

In ei.attackedBy, Queen does not x-ray through Rook, but the Rook does
X-ray through the Queen.

So most of the rook contact checks supported by queen are, in fact,
Queen Contact Checks and they are already scored separately.

Bench: 7762189

Resolves #338
---

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index b50792da..563e707f 100644
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -438,7 +438,7 @@ namespace {
         {
             // ...and then remove squares not supported by another enemy piece
             b &= (  ei.attackedBy[Them][PAWN]   | ei.attackedBy[Them][KNIGHT]
-                  | ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][QUEEN]);
+                  | ei.attackedBy[Them][BISHOP]);
 
             if (b)
                 attackUnits += RookContactCheck * popcount<Max15>(b);