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Micro-optimize pl_move_is_legal()

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This L1/L2 optimization has an incredible +4.7% speedup
in perft test where this function is the most time consumer.

Verified a speed up also in normal bench, although smaller.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2010-11-21 12:43:16 +01:00
parent f57d51b7f3
commit df6ba1fa5c
1 changed files with 9 additions and 7 deletions
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16
src/position.cpp
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@ -588,22 +588,18 @@ bool Position::pl_move_is_legal(Move m, Bitboard pinned) const {
if (move_is_castle(m))
return true;
Color us = side_to_move();
Square from = move_from(m);
assert(color_of_piece_on(from) == us);
assert(piece_on(king_square(us)) == piece_of_color_and_type(us, KING));
// En passant captures are a tricky special case. Because they are
// rather uncommon, we do it simply by testing whether the king is attacked
// after the move is made
if (move_is_ep(m))
{
Color us = side_to_move();
Color them = opposite_color(us);
Square from = move_from(m);
Square to = move_to(m);
Square capsq = make_square(square_file(to), square_rank(from));
Bitboard b = occupied_squares();
Square ksq = king_square(us);
Bitboard b = occupied_squares();
assert(to == ep_square());
assert(piece_on(from) == piece_of_color_and_type(us, PAWN));
@ -618,6 +614,12 @@ bool Position::pl_move_is_legal(Move m, Bitboard pinned) const {
&& !(bishop_attacks_bb(ksq, b) & pieces(BISHOP, QUEEN, them));
}
Color us = side_to_move();
Square from = move_from(m);
assert(color_of_piece_on(from) == us);
assert(piece_on(king_square(us)) == piece_of_color_and_type(us, KING));
// If the moving piece is a king, check whether the destination
// square is attacked by the opponent.
if (type_of_piece_on(from) == KING)