One of the most time critical functions is move_is_check()
and in particular the call to type_of_piece_on(from) in the
switch statement.
This call lookups in board[] array and can be slow if board[from]
is not already cached. Few instructions before in the execution stream,
we check the move for legality with pl_move_is_legal().
This patch changes pl_move_is_legal() to use type_of_piece_on(from)
for checking for a king move so that board[from] is automatically
cached in L1 and ready to be used by the near follower move_is_check()
Another advantage is that the call to king_square(us) in pl_move_is_legal()
is avoided most of the times.
Speed up of this nice and tricky patch is 0.7% !
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Color us = side_to_move();
Square from = move_from(m);
Color us = side_to_move();
Square from = move_from(m);
- Square ksq = king_square(us);
assert(color_of_piece_on(from) == us);
assert(color_of_piece_on(from) == us);
- assert(piece_on(ksq) == piece_of_color_and_type(us, KING));
+ 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
// En passant captures are a tricky special case. Because they are
// rather uncommon, we do it simply by testing whether the king is attacked
Square to = move_to(m);
Square capsq = make_square(square_file(to), square_rank(from));
Bitboard b = occupied_squares();
Square to = move_to(m);
Square capsq = make_square(square_file(to), square_rank(from));
Bitboard b = occupied_squares();
+ Square ksq = king_square(us);
assert(to == ep_square());
assert(piece_on(from) == piece_of_color_and_type(us, PAWN));
assert(to == ep_square());
assert(piece_on(from) == piece_of_color_and_type(us, PAWN));
// If the moving piece is a king, check whether the destination
// square is attacked by the opponent.
// If the moving piece is a king, check whether the destination
// square is attacked by the opponent.
+ if (type_of_piece_on(from) == KING)
return !(square_is_attacked(move_to(m), opposite_color(us)));
// A non-king move is legal if and only if it is not pinned or it
// is moving along the ray towards or away from the king.
return ( !pinned
|| !bit_is_set(pinned, from)
return !(square_is_attacked(move_to(m), opposite_color(us)));
// A non-king move is legal if and only if it is not pinned or it
// is moving along the ray towards or away from the king.
return ( !pinned
|| !bit_is_set(pinned, from)
- || (direction_between_squares(from, ksq) == direction_between_squares(move_to(m), ksq)));
+ || (direction_between_squares(from, king_square(us)) == direction_between_squares(move_to(m), king_square(us))));