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Speedup and simplify pinners and blockers

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To compute dicovered check or pinned pieces we use some bitwise
operators that are not really needed because already accounted for
at the caller site.

For instance in evaluation we compute:

     pos.pinned_pieces(Us) & s

Where pinned_pieces() is:

     st->blockersForKing[c] & pieces(c)

So in this case the & operator with pieces(c) is useless,
given the outer '& s'.

There are many places where we can use the naked blockersForKing[]
instead of the full pinned_pieces() or discovered_check_candidates().

This path is simpler than original and gives around 1% speed up for me.
Also tested for speed by mstembera and snicolet (neutral in both cases).

No functional change.
This commit is contained in:
Marco Costalba
2018-02-27 01:18:33 +01:00
committed by Stéphane Nicolet
parent d438720a1c
commit ad2a0e356e
5 changed files with 30 additions and 31 deletions
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11
src/position.h
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@@ -105,8 +105,7 @@ public:
// Checking
Bitboard checkers() const;
Bitboard discovered_check_candidates() const;
Bitboard pinned_pieces(Color c) const;
Bitboard blockers_for_king(Color c) const;
Bitboard check_squares(PieceType pt) const;
// Attacks to/from a given square
@@ -296,12 +295,8 @@ inline Bitboard Position::checkers() const {
return st->checkersBB;
}
inline Bitboard Position::discovered_check_candidates() const {
return st->blockersForKing[~sideToMove] & pieces(sideToMove);
}
inline Bitboard Position::pinned_pieces(Color c) const {
return st->blockersForKing[c] & pieces(c);
inline Bitboard Position::blockers_for_king(Color c) const {
return st->blockersForKing[c];
}
inline Bitboard Position::check_squares(PieceType pt) const {