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Simplify FullThreats::append_active_indices()

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Also add an else to FullThreats::append_changed_indices() because dp2removed
can't be equal to both from and to simultaneously.

passed STC
https://tests.stockfishchess.org/tests/view/69e71a490e9667dd5a76549f
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 210688 W: 54362 L: 54335 D: 101991
Ptnml(0-2): 613, 23246, 57593, 23285, 607

Thanks to ces42 for an improvement suggestion.

closes https://github.com/official-stockfish/Stockfish/pull/6770

No functional change
This commit is contained in:
mstembera
2026-04-26 09:37:18 +02:00
committed by Joost VandeVondele
parent c787509663
commit 692d90bd74
1 changed files with 41 additions and 58 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/nnue/features/full_threats.cpp
+41 -58
View File
@@ -207,76 +207,60 @@ inline sf_always_inline IndexType FullThreats::make_index(
// Get a list of indices for active features in ascending order
void FullThreats::append_active_indices(Color perspective, const Position& pos, IndexList& active) {
Square ksq = pos.square<KING>(perspective);
Bitboard occupied = pos.pieces();
Bitboard pawns = pos.pieces(PAWN);
const Square ksq = pos.square<KING>(perspective);
const Bitboard occupied = pos.pieces();
const Bitboard pawns = pos.pieces(PAWN);
for (Color color : {WHITE, BLACK})
{
for (PieceType pt = PAWN; pt < KING; ++pt)
const Color c = Color(perspective ^ color);
{
Color c = Color(perspective ^ color);
Piece attacker = make_piece(c, pt);
Bitboard bb = pos.pieces(c, pt);
const Piece attacker = make_piece(c, PAWN);
const Bitboard cPawns = pos.pieces(c, PAWN);
// Set of pawns which are prevented from movement by a pawn in front of them
const Bitboard pushers = pawn_single_push_bb(~c, pawns) & cPawns;
if (pt == PAWN)
{
auto right = (c == WHITE) ? NORTH_EAST : SOUTH_WEST;
auto left = (c == WHITE) ? NORTH_WEST : SOUTH_EAST;
auto attacks_left =
((c == WHITE) ? shift<NORTH_EAST>(bb) : shift<SOUTH_WEST>(bb)) & occupied;
auto attacks_right =
((c == WHITE) ? shift<NORTH_WEST>(bb) : shift<SOUTH_EAST>(bb)) & occupied;
while (attacks_left)
auto process_pawn_attacks = [&](Bitboard attacks, Direction attkDir) {
while (attacks)
{
Square to = pop_lsb(attacks_left);
Square from = to - right;
Piece attacked = pos.piece_on(to);
IndexType index = make_index(perspective, attacker, from, to, attacked, ksq);
active.push_back_if_lt(index, Dimensions);
}
while (attacks_right)
{
Square to = pop_lsb(attacks_right);
Square from = to - left;
Piece attacked = pos.piece_on(to);
IndexType index = make_index(perspective, attacker, from, to, attacked, ksq);
active.push_back_if_lt(index, Dimensions);
}
// Set of pawns which are prevented from movement by a pawn in front of them
Bitboard pushers = pawn_single_push_bb(~c, pawns) & pos.pieces(c, PAWN);
while (pushers)
{
Square from = pop_lsb(pushers);
Square to = from + pawn_push(c);
Square to = pop_lsb(attacks);
Square from = to - attkDir;
Piece attacked = pos.piece_on(to);
assert(type_of(attacked) == PAWN);
assert(file_of(from) != file_of(to) || type_of(attacked) == PAWN);
IndexType index = make_index(perspective, attacker, from, to, attacked, ksq);
active.push_back_if_lt(index, Dimensions);
}
};
if (c == WHITE)
{
process_pawn_attacks(shift<NORTH_EAST>(cPawns) & occupied, NORTH_EAST);
process_pawn_attacks(shift<NORTH_WEST>(cPawns) & occupied, NORTH_WEST);
process_pawn_attacks(shift<NORTH>(pushers), NORTH);
}
else
{
while (bb)
process_pawn_attacks(shift<SOUTH_WEST>(cPawns) & occupied, SOUTH_WEST);
process_pawn_attacks(shift<SOUTH_EAST>(cPawns) & occupied, SOUTH_EAST);
process_pawn_attacks(shift<SOUTH>(pushers), SOUTH);
}
}
for (PieceType pt = KNIGHT; pt < KING; ++pt)
{
Piece attacker = make_piece(c, pt);
Bitboard bb = pos.pieces(c, pt);
while (bb)
{
Square from = pop_lsb(bb);
Bitboard attacks = attacks_bb(pt, from, occupied) & occupied;
while (attacks)
{
Square from = pop_lsb(bb);
Bitboard attacks = (attacks_bb(pt, from, occupied)) & occupied;
while (attacks)
{
Square to = pop_lsb(attacks);
Piece attacked = pos.piece_on(to);
IndexType index =
make_index(perspective, attacker, from, to, attacked, ksq);
active.push_back_if_lt(index, Dimensions);
}
Square to = pop_lsb(attacks);
Piece attacked = pos.piece_on(to);
IndexType index = make_index(perspective, attacker, from, to, attacked, ksq);
active.push_back_if_lt(index, Dimensions);
}
}
}
@@ -318,8 +302,7 @@ void FullThreats::append_changed_indices(Color perspective,
else if (fusedData->dp2removedOriginBoard & to)
continue;
}
if (to != SQ_NONE && to == fusedData->dp2removed)
else if (to != SQ_NONE && to == fusedData->dp2removed)
{
if (add)
{