From: mcostalba <mcostalba@gmail.com>
Date: Thu, 22 Mar 2012 06:39:53 +0000 (-0700)
Subject: Merge pull request #8 from glinscott/master
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=d4c9abb9675586c680433f498f12551fec4e4ecd;hp=-c

Merge pull request #8 from glinscott/master

Optimize undefended minor check. Little editing by
me, no change even at assembly level.

No regression after 8K games at fast TC on a 64bit CPU.
---

d4c9abb9675586c680433f498f12551fec4e4ecd
diff --combined src/evaluate.cpp
index 2193eb6b,9bd403e1..2903c4b3
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@@ -167,6 -167,9 +167,9 @@@ namespace 
    // happen in Chess960 games.
    const Score TrappedBishopA1H1Penalty = make_score(100, 100);
  
+   // Penalty for a minor piece that is not defended by anything
+   const Score UndefendedMinorPenalty = make_score(25, 10);
+ 
    // The SpaceMask[Color] contains the area of the board which is considered
    // by the space evaluation. In the middle game, each side is given a bonus
    // based on how many squares inside this area are safe and available for
@@@ -680,16 -683,19 +683,17 @@@ Value do_evaluate(const Position& pos, 
      Score score = SCORE_ZERO;
  
      // Undefended minors get penalized even if not under attack
 -    const Bitboard undefended =  pos.pieces(Them)
 -                              & (pos.pieces(BISHOP) | pos.pieces(KNIGHT))
 -                              & ~ei.attackedBy[Them][0];
 -    if (undefended) {
 -        score += UndefendedMinorPenalty;
 -        if (!single_bit(undefended))
 -            score += UndefendedMinorPenalty;
 -    }
 +    Bitboard undefended =  pos.pieces(Them)
 +                         & (pos.pieces(BISHOP) | pos.pieces(KNIGHT))
 +                         & ~ei.attackedBy[Them][0];
 +    if (undefended)
-         score += make_score(25, 10) * popcount<Max15>(undefended);
++        score += single_bit(undefended) ? UndefendedMinorPenalty
++                                        : UndefendedMinorPenalty * 2;
  
      // Enemy pieces not defended by a pawn and under our attack
 -    const Bitboard weakEnemies =  pos.pieces(Them)
 -                               & ~ei.attackedBy[Them][PAWN]
 -                               & ei.attackedBy[Us][0];
 +    Bitboard weakEnemies =  pos.pieces(Them)
 +                          & ~ei.attackedBy[Them][PAWN]
 +                          & ei.attackedBy[Us][0];
      if (!weakEnemies)
          return score;