Merge pull request #8 from glinscott/master
authormcostalba <mcostalba@gmail.com>
Thu, 22 Mar 2012 06:39:53 +0000 (23:39 -0700)
committerMarco Costalba <mcostalba@gmail.com>
Thu, 22 Mar 2012 06:49:11 +0000 (07:49 +0100)
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.

1  2 
src/evaluate.cpp

index 2193eb6be797805b6aa46a4f510bbc9c14c4a38c,9bd403e1bf8ab1100284eec6d27f791f5b3b6bcc..2903c4b375da81736478ee3fb6439e6f2f749c08
@@@ -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;