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Optimize generate_piece_blocking_evasions()

Rewrite as in generate_piece_moves() using a for
loop instead of the slower serializing of the
bitboard with pop_1st_bit()

This will allow also to merge with generate_piece_moves()
when we will drop legality constrain on generate_evasions()

Generated moves are not changed, but are generated in a
different order, this changes the number of nodes at fixed
depth test.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
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1 parent 6753571 commit 1dc1cecf01352a39bc1b80c83f6e8e4e97d859e1 @mcostalba committed Feb 11, 2009
Showing with 24 additions and 21 deletions.
  1. +24 −21 src/movegen.cpp
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@@ -102,11 +102,11 @@ namespace {
template<>
inline MoveStack* generate_piece_blocking_evasions<PAWN>(const Position& p, MoveStack* m, Color us,
- Bitboard np, Bitboard bs) {
+ Bitboard pnd, Bitboard bs) {
if (us == WHITE)
- return generate_pawn_blocking_evasions<WHITE, RANK_8, Rank3BB, DELTA_N>(p, np, bs, m);
+ return generate_pawn_blocking_evasions<WHITE, RANK_8, Rank3BB, DELTA_N>(p, pnd, bs, m);
else
- return generate_pawn_blocking_evasions<BLACK, RANK_1, Rank6BB, DELTA_S>(p, np, bs, m);
+ return generate_pawn_blocking_evasions<BLACK, RANK_1, Rank6BB, DELTA_S>(p, pnd, bs, m);
}
}
@@ -265,14 +265,13 @@ int generate_evasions(const Position& pos, MoveStack* mlist, Bitboard pinned) {
if (!(checkers & (checkers - 1))) // Only one bit set?
{
Square checksq = first_1(checkers);
- Bitboard not_pinned = ~pinned;
assert(pos.color_of_piece_on(checksq) == them);
// Generate captures of the checking piece
// Pawn captures
- b1 = pos.pawn_attacks(them, checksq) & pos.pawns(us) & not_pinned;
+ b1 = pos.pawn_attacks(them, checksq) & pos.pawns(us) & ~pinned;
while (b1)
{
from = pop_1st_bit(&b1);
@@ -289,7 +288,7 @@ int generate_evasions(const Position& pos, MoveStack* mlist, Bitboard pinned) {
// Pieces captures
b1 = ( (pos.piece_attacks<KNIGHT>(checksq) & pos.knights(us))
| (pos.piece_attacks<BISHOP>(checksq) & pos.bishops_and_queens(us))
- | (pos.piece_attacks<ROOK>(checksq) & pos.rooks_and_queens(us)) ) & not_pinned;
+ | (pos.piece_attacks<ROOK>(checksq) & pos.rooks_and_queens(us)) ) & ~pinned;
while (b1)
{
@@ -298,19 +297,19 @@ int generate_evasions(const Position& pos, MoveStack* mlist, Bitboard pinned) {
}
// Blocking check evasions are possible only if the checking piece is
- // a slider
+ // a slider.
if (checkers & pos.sliders())
{
Bitboard blockSquares = squares_between(checksq, ksq);
assert((pos.occupied_squares() & blockSquares) == EmptyBoardBB);
// Pieces moves
- mlist = generate_piece_blocking_evasions<PAWN>(pos, mlist, us, not_pinned, blockSquares);
- mlist = generate_piece_blocking_evasions<KNIGHT>(pos, mlist, us, not_pinned, blockSquares);
- mlist = generate_piece_blocking_evasions<BISHOP>(pos, mlist, us, not_pinned, blockSquares);
- mlist = generate_piece_blocking_evasions<ROOK>(pos, mlist, us, not_pinned, blockSquares);
- mlist = generate_piece_blocking_evasions<QUEEN>(pos, mlist, us, not_pinned, blockSquares);
+ mlist = generate_piece_blocking_evasions<PAWN>(pos, mlist, us, pinned, blockSquares);
+ mlist = generate_piece_blocking_evasions<KNIGHT>(pos, mlist, us, pinned, blockSquares);
+ mlist = generate_piece_blocking_evasions<BISHOP>(pos, mlist, us, pinned, blockSquares);
+ mlist = generate_piece_blocking_evasions<ROOK>(pos, mlist, us, pinned, blockSquares);
+ mlist = generate_piece_blocking_evasions<QUEEN>(pos, mlist, us, pinned, blockSquares);
}
// Finally, the ugly special case of en passant captures. An en passant
@@ -325,7 +324,7 @@ int generate_evasions(const Position& pos, MoveStack* mlist, Bitboard pinned) {
assert(b1 != EmptyBoardBB);
- b1 &= not_pinned;
+ b1 &= ~pinned;
while (b1)
{
from = pop_1st_bit(&b1);
@@ -587,14 +586,18 @@ namespace {
template<PieceType Piece>
MoveStack* generate_piece_blocking_evasions(const Position& pos, MoveStack* mlist, Color us,
- Bitboard not_pinned, Bitboard blockSquares) {
+ Bitboard pinned, Bitboard blockSquares) {
+ Square from;
+ Bitboard b;
- Bitboard b = pos.pieces_of_color_and_type(us, Piece) & not_pinned;
- while (b)
+ for (int i = 0, e = pos.piece_count(us, Piece); i < e; i++)
{
- Square from = pop_1st_bit(&b);
- Bitboard bb = pos.piece_attacks<Piece>(from) & blockSquares;
- SERIALIZE_MOVES(bb);
+ from = pos.piece_list(us, Piece, i);
+ if (pinned && bit_is_set(pinned, from))
+ continue;
+
+ b = pos.piece_attacks<Piece>(from) & blockSquares;
+ SERIALIZE_MOVES(b);
}
return mlist;
}
@@ -821,12 +824,12 @@ namespace {
}
template<Color Us, Rank TRANK_8, Bitboard TRank3BB, SquareDelta TDELTA_N>
- MoveStack* generate_pawn_blocking_evasions(const Position& pos, Bitboard not_pinned,
+ MoveStack* generate_pawn_blocking_evasions(const Position& pos, Bitboard pinned,
Bitboard blockSquares, MoveStack* mlist) {
Square to;
// Find non-pinned pawns
- Bitboard b1 = pos.pawns(Us) & not_pinned;
+ Bitboard b1 = pos.pawns(Us) & ~pinned;
// Single pawn pushes. We don't have to AND with empty squares here,
// because the blocking squares will always be empty.

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