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Remove EvalList

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This patch removes the EvalList structure from the Position object and generally simplifies the interface between do_move() and the NNUE code.

The NNUE evaluation function first calculates the "accumulator". The accumulator consists of two halves: one for white's perspective, one for black's perspective.

If the "friendly king" has moved or the accumulator for the parent position is not available, the accumulator for this half has to be calculated from scratch. To do this, the NNUE node needs to know the positions and types of all non-king pieces and the position of the friendly king. This information can easily be obtained from the Position object.

If the "friendly king" has not moved, its half of the accumulator can be calculated by incrementally updating the accumulator for the previous position. For this, the NNUE code needs to know which pieces have been added to which squares and which pieces have been removed from which squares. In principle this information can be derived from the Position object and StateInfo struct (in the same way as undo_move() does this). However, it is probably a bit faster to prepare this information in do_move(), so I have kept the DirtyPiece struct. Since the DirtyPiece struct now stores the squares rather than "PieceSquare" indices, there are now at most three "dirty pieces" (previously two). A promotion move that captures a piece removes the capturing pawn and the captured piece from the board (to SQ_NONE) and moves the promoted piece to the promotion square (from SQ_NONE).

An STC test has confirmed a small speedup:

https://tests.stockfishchess.org/tests/view/5f43f06b5089a564a10d850a
LLR: 2.94 (-2.94,2.94) {-0.25,1.25}
Total: 87704 W: 9763 L: 9500 D: 68441
Ptnml(0-2): 426, 6950, 28845, 7197, 434

closes https://github.com/official-stockfish/Stockfish/pull/3068

No functional change
This commit is contained in:
syzygy1
2020-08-24 02:29:38 +02:00
committed by Joost VandeVondele
parent b0b4ca17db
commit 9b4967071e
8 changed files with 96 additions and 273 deletions
Download Patch File Download Diff File Expand all files Collapse all files

116
src/types.h
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@@ -201,22 +201,6 @@ enum Piece {
PIECE_NB = 16
};
// An ID used to track the pieces. Max. 32 pieces on board.
enum PieceId {
PIECE_ID_ZERO = 0,
PIECE_ID_KING = 30,
PIECE_ID_WKING = 30,
PIECE_ID_BKING = 31,
PIECE_ID_NONE = 32
};
inline PieceId operator++(PieceId& d, int) {
PieceId x = d;
d = PieceId(int(d) + 1);
return x;
}
constexpr Value PieceValue[PHASE_NB][PIECE_NB] = {
{ VALUE_ZERO, PawnValueMg, KnightValueMg, BishopValueMg, RookValueMg, QueenValueMg, VALUE_ZERO, VALUE_ZERO,
VALUE_ZERO, PawnValueMg, KnightValueMg, BishopValueMg, RookValueMg, QueenValueMg, VALUE_ZERO, VALUE_ZERO },
@@ -271,93 +255,20 @@ enum Rank : int {
RANK_1, RANK_2, RANK_3, RANK_4, RANK_5, RANK_6, RANK_7, RANK_8, RANK_NB
};
// unique number for each piece type on each square
enum PieceSquare : uint32_t {
PS_NONE = 0,
PS_W_PAWN = 1,
PS_B_PAWN = 1 * SQUARE_NB + 1,
PS_W_KNIGHT = 2 * SQUARE_NB + 1,
PS_B_KNIGHT = 3 * SQUARE_NB + 1,
PS_W_BISHOP = 4 * SQUARE_NB + 1,
PS_B_BISHOP = 5 * SQUARE_NB + 1,
PS_W_ROOK = 6 * SQUARE_NB + 1,
PS_B_ROOK = 7 * SQUARE_NB + 1,
PS_W_QUEEN = 8 * SQUARE_NB + 1,
PS_B_QUEEN = 9 * SQUARE_NB + 1,
PS_W_KING = 10 * SQUARE_NB + 1,
PS_END = PS_W_KING, // pieces without kings (pawns included)
PS_B_KING = 11 * SQUARE_NB + 1,
PS_END2 = 12 * SQUARE_NB + 1
};
struct ExtPieceSquare {
PieceSquare from[COLOR_NB];
};
// Array for finding the PieceSquare corresponding to the piece on the board
extern ExtPieceSquare kpp_board_index[PIECE_NB];
constexpr bool is_ok(PieceId pid);
constexpr Square rotate180(Square sq);
// Structure holding which tracked piece (PieceId) is where (PieceSquare)
class EvalList {
public:
// Max. number of pieces without kings is 30 but must be a multiple of 4 in AVX2
static const int MAX_LENGTH = 32;
// Array that holds the piece id for the pieces on the board
PieceId piece_id_list[SQUARE_NB];
// List of pieces, separate from White and Black POV
PieceSquare* piece_list_fw() const { return const_cast<PieceSquare*>(pieceListFw); }
PieceSquare* piece_list_fb() const { return const_cast<PieceSquare*>(pieceListFb); }
// Place the piece pc with piece_id on the square sq on the board
void put_piece(PieceId piece_id, Square sq, Piece pc)
{
assert(is_ok(piece_id));
if (pc != NO_PIECE)
{
pieceListFw[piece_id] = PieceSquare(kpp_board_index[pc].from[WHITE] + sq);
pieceListFb[piece_id] = PieceSquare(kpp_board_index[pc].from[BLACK] + rotate180(sq));
piece_id_list[sq] = piece_id;
}
else
{
pieceListFw[piece_id] = PS_NONE;
pieceListFb[piece_id] = PS_NONE;
piece_id_list[sq] = piece_id;
}
}
// Convert the specified piece_id piece to ExtPieceSquare type and return it
ExtPieceSquare piece_with_id(PieceId piece_id) const
{
ExtPieceSquare eps;
eps.from[WHITE] = pieceListFw[piece_id];
eps.from[BLACK] = pieceListFb[piece_id];
return eps;
}
private:
PieceSquare pieceListFw[MAX_LENGTH];
PieceSquare pieceListFb[MAX_LENGTH];
};
// For differential evaluation of pieces that changed since last turn
// Keep track of what a move changes on the board (used by NNUE)
struct DirtyPiece {
// Number of changed pieces
int dirty_num;
// The ids of changed pieces, max. 2 pieces can change in one move
PieceId pieceId[2];
// Max 3 pieces can change in one move. A promotion with capture moves
// both the pawn and the captured piece to SQ_NONE and the piece promoted
// to from SQ_NONE to the capture square.
Piece piece[3];
// What changed from the piece with that piece number
ExtPieceSquare old_piece[2];
ExtPieceSquare new_piece[2];
// From and to squares, which may be SQ_NONE
Square from[3];
Square to[3];
};
/// Score enum stores a middlegame and an endgame value in a single integer (enum).
@@ -407,8 +318,6 @@ ENABLE_FULL_OPERATORS_ON(Value)
ENABLE_FULL_OPERATORS_ON(Direction)
ENABLE_INCR_OPERATORS_ON(Piece)
ENABLE_INCR_OPERATORS_ON(PieceSquare)
ENABLE_INCR_OPERATORS_ON(PieceId)
ENABLE_INCR_OPERATORS_ON(PieceType)
ENABLE_INCR_OPERATORS_ON(Square)
ENABLE_INCR_OPERATORS_ON(File)
@@ -497,10 +406,6 @@ inline Color color_of(Piece pc) {
return Color(pc >> 3);
}
constexpr bool is_ok(PieceId pid) {
return pid < PIECE_ID_NONE;
}
constexpr bool is_ok(Square s) {
return s >= SQ_A1 && s <= SQ_H8;
}
@@ -537,11 +442,6 @@ constexpr Square to_sq(Move m) {
return Square(m & 0x3F);
}
// Return relative square when turning the board 180 degrees
constexpr Square rotate180(Square sq) {
return (Square)(sq ^ 0x3F);
}
constexpr int from_to(Move m) {
return m & 0xFFF;
}