From: Marco Costalba <mcostalba@gmail.com>
Date: Wed, 20 Feb 2013 11:19:19 +0000 (+0100)
Subject: Merge Gary's bishop_pin patch
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=9a1d5f0f1d8a12a85b198688d4f1d636a146eb7a

Merge Gary's bishop_pin patch

Give a bonus if a bishop can pin a piece or can
give a discovered check through an x-ray attack.

Seems good after 24000 games at 15"+0.05 (single thread):

ELO: 12.30 +- 99%: 5.79 95%: 4.40 LOS: 100.00%
Total: 24000 W: 4931 L: 4082 D: 14987

bench: 4917064
---

9a1d5f0f1d8a12a85b198688d4f1d636a146eb7a
diff --cc src/evaluate.cpp
index 5140c493,02810b78..3ba405cc
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@@ -593,7 -583,12 +583,14 @@@ Value do_evaluate(const Position& pos, 
          // of threat evaluation must be done later when we have full attack info.
          if (ei.attackedBy[Them][PAWN] & s)
              score -= ThreatenedByPawnPenalty[Piece];
 -        else if (Piece == BISHOP && (PseudoAttacks[Piece][pos.king_square(Them)] & s)) {
 -             const Bitboard between = BetweenBB[s][pos.king_square(Them)] & pos.pieces();
 -             if (!more_than_one(between))
 +
++        // Otherwise give a bonus if we are a bishop and can pin a piece or
++        // can give a discovered check through an x-ray attack.
++        else if (    Piece == BISHOP
++                 && (PseudoAttacks[Piece][pos.king_square(Them)] & s)
++                 && !more_than_one(BetweenBB[s][pos.king_square(Them)] & pos.pieces()))
+                  score += BishopPinBonus;
 -        }
+ 
          // Bishop and knight outposts squares
          if (    (Piece == BISHOP || Piece == KNIGHT)
              && !(pos.pieces(Them, PAWN) & attack_span_mask(Us, s)))