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Some more work on FullThreats::make_index

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[Passed STC](https://tests.stockfishchess.org/tests/live_elo/691fc321acb6dbdf23d07e4b):

```
LLR: 2.95 (-2.94,2.94) <0.00,2.00>
Total: 215360 W: 55651 L: 55108 D: 104601
Ptnml(0-2): 520, 22399, 61290, 22960, 511
```

This PR is on top of ces42's work so I'll rebase if that PR changes.
Essentially, it comprises my adjustments to `make_index` that remained
unmerged before threat inputs was finalized.

The unsigned intermediate variables let us skip a bunch of useless sign
extensions (because Square and Piece inherit from `int8_t`, and C/C++
semantics require narrow integers to be promoted to `int` before doing
arithmetic on them). Additionally, by removing the special usage of
`offsets[][64]` and `[65]` the indexing becomes more efficient. (This
usage was a temporary hack from sscg anyway, so I think he'll like that
it's gone.) Finally, the `sf_assume` condition was fixed so that it
actually makes a difference to the compiler.

The speedup is fairly nice locally (combining both ces42's and these changes):

```
Result of 100 runs
==================
base (...kfish.master) =    1691982  +/- 1907
test (./stockfish    ) =    1714349  +/- 1789
diff                   =     +22367  +/- 2465

speedup        = +0.0132
P(speedup > 0) =  1.0000
```

closes https://github.com/official-stockfish/Stockfish/pull/6445

No functional change
This commit is contained in:
Carlos Esparza
2025-11-30 21:45:14 +01:00
committed by Disservin
parent 93f2d14d95
commit f4244e13e4
3 changed files with 31 additions and 42 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/nnue/features/full_threats.cpp
+26 -24
View File
@@ -32,7 +32,12 @@
namespace Stockfish::Eval::NNUE::Features {
// Lookup array for indexing threats
IndexType offsets[PIECE_NB][SQUARE_NB + 2];
IndexType offsets[PIECE_NB][SQUARE_NB];
struct HelperOffsets {
int cumulativePieceOffset, cumulativeOffset;
};
std::array<HelperOffsets, PIECE_NB> helper_offsets;
// Information on a particular pair of pieces and whether they should be excluded
struct PiecePairData {
@@ -69,9 +74,9 @@ static void init_index_luts() {
int map = FullThreats::map[attackerType - 1][attackedType - 1];
bool semi_excluded = attackerType == attackedType && (enemy || attackerType != PAWN);
IndexType feature = offsets[attacker][65]
IndexType feature = helper_offsets[attacker].cumulativeOffset
+ (color_of(attacked) * (numValidTargets[attacker] / 2) + map)
* offsets[attacker][64];
* helper_offsets[attacker].cumulativePieceOffset;
bool excluded = map < 0;
index_lut1[attacker][attacked] = PiecePairData(excluded, semi_excluded, feature);
@@ -116,8 +121,7 @@ void init_threat_offsets() {
}
}
offsets[pieceIdx][64] = cumulativePieceOffset;
offsets[pieceIdx][65] = cumulativeOffset;
helper_offsets[pieceIdx] = {cumulativePieceOffset, cumulativeOffset};
cumulativeOffset += numValidTargets[pieceIdx] * cumulativePieceOffset;
}
@@ -128,32 +132,30 @@ void init_threat_offsets() {
// Index of a feature for a given king position and another piece on some square
inline sf_always_inline IndexType FullThreats::make_index(
Color perspective, Piece attacker, Square from, Square to, Piece attacked, Square ksq) {
const int orientation = OrientTBL[perspective][ksq];
from = Square(int(from) ^ orientation);
to = Square(int(to) ^ orientation);
const std::int8_t orientation = OrientTBL[ksq] ^ (56 * perspective);
unsigned from_oriented = uint8_t(from) ^ orientation;
unsigned to_oriented = uint8_t(to) ^ orientation;
std::int8_t swap = 8 * perspective;
attacker = Piece(attacker ^ swap);
attacked = Piece(attacked ^ swap);
std::int8_t swap = 8 * perspective;
unsigned attacker_oriented = attacker ^ swap;
unsigned attacked_oriented = attacked ^ swap;
const auto piecePairData = index_lut1[attacker][attacked];
const auto piecePairData = index_lut1[attacker_oriented][attacked_oriented];
const bool less_than = static_cast<unsigned>(from) < static_cast<unsigned>(to);
const bool less_than = from_oriented < to_oriented;
if ((piecePairData.excluded_pair_info() + less_than) & 2)
return FullThreats::Dimensions;
const IndexType index =
piecePairData.feature_index_base() + offsets[attacker][from] + index_lut2[attacker][from][to];
sf_assume(index != FullThreats::Dimensions);
const IndexType index = piecePairData.feature_index_base()
+ offsets[attacker_oriented][from_oriented]
+ index_lut2[attacker_oriented][from_oriented][to_oriented];
sf_assume(index < Dimensions);
return index;
}
// Get a list of indices for active features in ascending order
void FullThreats::append_active_indices(Color perspective, const Position& pos, IndexList& active) {
static constexpr Color order[2][2] = {{WHITE, BLACK}, {BLACK, WHITE}};
Square ksq = pos.square<KING>(perspective);
Bitboard occupied = pos.pieces();
@@ -161,7 +163,7 @@ void FullThreats::append_active_indices(Color perspective, const Position& pos,
{
for (PieceType pt = PAWN; pt <= KING; ++pt)
{
Color c = order[perspective][color];
Color c = Color(perspective ^ color);
Piece attacker = make_piece(c, pt);
Bitboard bb = pos.pieces(c, pt);
@@ -268,16 +270,16 @@ void FullThreats::append_changed_indices(Color perspective,
}
}
const IndexType index = make_index(perspective, attacker, from, to, attacked, ksq);
auto& insert = add ? added : removed;
const IndexType index = make_index(perspective, attacker, from, to, attacked, ksq);
if (index < Dimensions)
(add ? added : removed).push_back(index);
insert.push_back(index);
}
}
bool FullThreats::requires_refresh(const DiffType& diff, Color perspective) {
return perspective == diff.us
&& OrientTBL[diff.us][diff.ksq] != OrientTBL[diff.us][diff.prevKsq];
return perspective == diff.us && (int8_t(diff.ksq) & 0b100) != (int8_t(diff.prevKsq) & 0b100);
}
} // namespace Stockfish::Eval::NNUE::Features
src/nnue/features/full_threats.h
+3 -12
View File
@@ -32,7 +32,6 @@ namespace Stockfish::Eval::NNUE::Features {
static constexpr int numValidTargets[PIECE_NB] = {0, 6, 12, 10, 10, 12, 8, 0,
0, 6, 12, 10, 10, 12, 8, 0};
extern IndexType offsets[PIECE_NB][SQUARE_NB + 2];
void init_threat_offsets();
class FullThreats {
@@ -48,23 +47,15 @@ class FullThreats {
// clang-format off
// Orient a square according to perspective (rotates by 180 for black)
static constexpr int OrientTBL[COLOR_NB][SQUARE_NB] = {
{ SQ_A1, SQ_A1, SQ_A1, SQ_A1, SQ_H1, SQ_H1, SQ_H1, SQ_H1,
static constexpr std::int8_t OrientTBL[SQUARE_NB] = {
SQ_A1, SQ_A1, SQ_A1, SQ_A1, SQ_H1, SQ_H1, SQ_H1, SQ_H1,
SQ_A1, SQ_A1, SQ_A1, SQ_A1, SQ_H1, SQ_H1, SQ_H1, SQ_H1,
SQ_A1, SQ_A1, SQ_A1, SQ_A1, SQ_H1, SQ_H1, SQ_H1, SQ_H1,
SQ_A1, SQ_A1, SQ_A1, SQ_A1, SQ_H1, SQ_H1, SQ_H1, SQ_H1,
SQ_A1, SQ_A1, SQ_A1, SQ_A1, SQ_H1, SQ_H1, SQ_H1, SQ_H1,
SQ_A1, SQ_A1, SQ_A1, SQ_A1, SQ_H1, SQ_H1, SQ_H1, SQ_H1,
SQ_A1, SQ_A1, SQ_A1, SQ_A1, SQ_H1, SQ_H1, SQ_H1, SQ_H1,
SQ_A1, SQ_A1, SQ_A1, SQ_A1, SQ_H1, SQ_H1, SQ_H1, SQ_H1,
SQ_A1, SQ_A1, SQ_A1, SQ_A1, SQ_H1, SQ_H1, SQ_H1, SQ_H1 },
{ SQ_A8, SQ_A8, SQ_A8, SQ_A8, SQ_H8, SQ_H8, SQ_H8, SQ_H8,
SQ_A8, SQ_A8, SQ_A8, SQ_A8, SQ_H8, SQ_H8, SQ_H8, SQ_H8,
SQ_A8, SQ_A8, SQ_A8, SQ_A8, SQ_H8, SQ_H8, SQ_H8, SQ_H8,
SQ_A8, SQ_A8, SQ_A8, SQ_A8, SQ_H8, SQ_H8, SQ_H8, SQ_H8,
SQ_A8, SQ_A8, SQ_A8, SQ_A8, SQ_H8, SQ_H8, SQ_H8, SQ_H8,
SQ_A8, SQ_A8, SQ_A8, SQ_A8, SQ_H8, SQ_H8, SQ_H8, SQ_H8,
SQ_A8, SQ_A8, SQ_A8, SQ_A8, SQ_H8, SQ_H8, SQ_H8, SQ_H8,
SQ_A8, SQ_A8, SQ_A8, SQ_A8, SQ_H8, SQ_H8, SQ_H8, SQ_H8 }
};
static constexpr int map[PIECE_TYPE_NB-2][PIECE_TYPE_NB-2] = {
src/types.h
+2 -6
View File
@@ -295,18 +295,14 @@ struct DirtyPiece {
struct DirtyThreat {
DirtyThreat() { /* don't initialize data */ }
DirtyThreat(Piece pc, Piece threatened_pc, Square pc_sq, Square threatened_sq, bool add) {
data = (add << 28) | (pc << 20) | (threatened_pc << 16) | (threatened_sq << 8) | (pc_sq);
data = (add << 31) | (pc << 20) | (threatened_pc << 16) | (threatened_sq << 8) | (pc_sq);
}
Piece pc() const { return static_cast<Piece>(data >> 20 & 0xf); }
Piece threatened_pc() const { return static_cast<Piece>(data >> 16 & 0xf); }
Square threatened_sq() const { return static_cast<Square>(data >> 8 & 0xff); }
Square pc_sq() const { return static_cast<Square>(data & 0xff); }
bool add() const {
uint32_t b = data >> 28;
sf_assume(b == 0 || b == 1);
return b;
}
bool add() const { return data >> 31; }
private:
uint32_t data;