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Remove castling moves in check generation

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Check generation is used only in qsearch and
only at Depth(0), castling moves that give check
are very rare overall and even almost not exsistent
at Depth(0).

So retire this almost never used code that adds
a small but consistent slow down in the normal path.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba
2009-11-01 17:19:04 +01:00
parent 8ebe5075eb
commit 23de3e16f1
1 changed files with 1 additions and 30 deletions
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31
src/movegen.cpp
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@@ -52,9 +52,6 @@ namespace {
EVASION EVASION
}; };
// Functions
bool castling_is_check(const Position&, CastlingSide);
// Helper templates // Helper templates
template<CastlingSide Side> template<CastlingSide Side>
MoveStack* generate_castle_moves(const Position&, MoveStack*); MoveStack* generate_castle_moves(const Position&, MoveStack*);
@@ -190,20 +187,7 @@ MoveStack* generate_non_capture_checks(const Position& pos, MoveStack* mlist, Bi
mlist = generate_direct_checks<KNIGHT>(pos, mlist, us, dc, ksq); mlist = generate_direct_checks<KNIGHT>(pos, mlist, us, dc, ksq);
mlist = generate_direct_checks<BISHOP>(pos, mlist, us, dc, ksq); mlist = generate_direct_checks<BISHOP>(pos, mlist, us, dc, ksq);
mlist = generate_direct_checks<ROOK>(pos, mlist, us, dc, ksq); mlist = generate_direct_checks<ROOK>(pos, mlist, us, dc, ksq);
mlist = generate_direct_checks<QUEEN>(pos, mlist, us, dc, ksq); return generate_direct_checks<QUEEN>(pos, mlist, us, dc, ksq);
// Castling moves that give check. Very rare but nice to have!
if ( pos.can_castle_queenside(us)
&& (square_rank(ksq) == square_rank(pos.king_square(us)) || square_file(ksq) == FILE_D)
&& castling_is_check(pos, QUEEN_SIDE))
mlist = generate_castle_moves<QUEEN_SIDE>(pos, mlist);
if ( pos.can_castle_kingside(us)
&& (square_rank(ksq) == square_rank(pos.king_square(us)) || square_file(ksq) == FILE_F)
&& castling_is_check(pos, KING_SIDE))
mlist = generate_castle_moves<KING_SIDE>(pos, mlist);
return mlist;
} }
@@ -787,17 +771,4 @@ namespace {
} }
return mlist; return mlist;
} }
bool castling_is_check(const Position& pos, CastlingSide side) {
// After castling opponent king is attacked by the castled rook?
File rookFile = (side == QUEEN_SIDE ? FILE_D : FILE_F);
Color us = pos.side_to_move();
Square ksq = pos.king_square(us);
Bitboard occ = pos.occupied_squares();
clear_bit(&occ, ksq); // Remove our king from the board
Square rsq = make_square(rookFile, square_rank(ksq));
return bit_is_set(rook_attacks_bb(rsq, occ), pos.king_square(opposite_color(us)));
}
} }