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Micro optimize SEE

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Use pieces_of_type() instead of pieces_of_color_and_type()
in an hot loop and cut of almost 10% SEE execution time.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2009-05-04 11:18:24 +02:00
parent 9144e48eb6
commit 412d68fe4f
1 changed files with 8 additions and 7 deletions
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15
src/position.cpp
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@ -1511,7 +1511,7 @@ int Position::see(Square from, Square to) const {
0, 0
};
Bitboard attackers, occ, b;
Bitboard attackers, stmAttackers, occ, b;
assert(square_is_ok(from) || from == SQ_NONE);
assert(square_is_ok(to));
@ -1535,7 +1535,6 @@ int Position::see(Square from, Square to) const {
Square capQq = (side_to_move() == WHITE)? (to - DELTA_N) : (to - DELTA_S);
capture = piece_on(capQq);
assert(type_of_piece_on(capQq) == PAWN);
// Remove the captured pawn
@ -1570,7 +1569,8 @@ int Position::see(Square from, Square to) const {
}
// If the opponent has no attackers we are finished
if ((attackers & pieces_of_color(them)) == EmptyBoardBB)
stmAttackers = attackers & pieces_of_color(them);
if (!stmAttackers)
return seeValues[capture];
attackers &= occ; // Remove the moving piece
@ -1592,12 +1592,12 @@ int Position::see(Square from, Square to) const {
// Locate the least valuable attacker for the side to move. The loop
// below looks like it is potentially infinite, but it isn't. We know
// that the side to move still has at least one attacker left.
for (pt = PAWN; !(attackers & pieces_of_color_and_type(c, pt)); pt++)
for (pt = PAWN; !(stmAttackers & pieces_of_type(pt)); pt++)
assert(pt < KING);
// Remove the attacker we just found from the 'attackers' bitboard,
// and scan for new X-ray attacks behind the attacker.
b = attackers & pieces_of_color_and_type(c, pt);
b = stmAttackers & pieces_of_type(pt);
occ ^= (b & (~b + 1));
attackers |= (rook_attacks_bb(to, occ) & rooks_and_queens())
| (bishop_attacks_bb(to, occ) & bishops_and_queens());
@ -1613,15 +1613,16 @@ int Position::see(Square from, Square to) const {
// before beginning the next iteration
lastCapturingPieceValue = seeValues[pt];
c = opposite_color(c);
stmAttackers = attackers & pieces_of_color(c);
// Stop after a king capture
if (pt == KING && (attackers & pieces_of_color(c)))
if (pt == KING && stmAttackers)
{
assert(n < 32);
swapList[n++] = 100;
break;
}
} while (attackers & pieces_of_color(c));
} while (stmAttackers);
// Having built the swap list, we negamax through it to find the best
// achievable score from the point of view of the side to move