Remove the special value we used for the file of the king in the
evaluate_shelter() function, and compensate by tweaking some of
the ShelterStrength[] array values.
STC
LLR: 2.94 (-2.94,2.94) [-3.00,1.00]
Total: 17069 W: 3782 L: 3652 D: 9635
http://tests.stockfishchess.org/tests/view/
5b75eb0d0ebc5902bdba8f3d
LTC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 42639 W: 6973 L: 6887 D: 28779
http://tests.stockfishchess.org/tests/view/
5b75fd7f0ebc5902bdba906b
Closes https://github.com/official-stockfish/Stockfish/pull/1739
Bench:
4639508
// Strength of pawn shelter for our king by [distance from edge][rank].
// RANK_1 = 0 is used for files where we have no pawn, or pawn is behind our king.
constexpr Value ShelterStrength[int(FILE_NB) / 2][RANK_NB] = {
// Strength of pawn shelter for our king by [distance from edge][rank].
// RANK_1 = 0 is used for files where we have no pawn, or pawn is behind our king.
constexpr Value ShelterStrength[int(FILE_NB) / 2][RANK_NB] = {
- { V( -3), V( 81), V( 93), V( 58), V( 39), V( 18), V( 25) },
- { V(-40), V( 61), V( 35), V(-49), V(-29), V(-11), V( -63) },
- { V( -7), V( 75), V( 23), V( -2), V( 32), V( 3), V( -45) },
- { V(-36), V(-13), V(-29), V(-52), V(-48), V(-67), V(-166) }
+ { V( -6), V( 81), V( 93), V( 58), V( 39), V( 18), V( 25) },
+ { V(-43), V( 61), V( 35), V(-49), V(-29), V(-11), V( -63) },
+ { V(-10), V( 75), V( 23), V( -2), V( 32), V( 3), V( -45) },
+ { V(-39), V(-13), V(-29), V(-52), V(-48), V(-67), V(-166) }
};
// Danger of enemy pawns moving toward our king by [distance from edge][rank].
};
// Danger of enemy pawns moving toward our king by [distance from edge][rank].
Bitboard ourPawns = b & pos.pieces(Us);
Bitboard theirPawns = b & pos.pieces(Them);
Bitboard ourPawns = b & pos.pieces(Us);
Bitboard theirPawns = b & pos.pieces(Them);
- Value safety = (ourPawns & file_bb(ksq)) ? Value(5) : Value(-5);
-
- if (shift<Down>(theirPawns) & (FileABB | FileHBB) & BlockRanks & ksq)
- safety += Value(374);
+ Value safety = (shift<Down>(theirPawns) & (FileABB | FileHBB) & BlockRanks & ksq) ?
+ Value(374) : Value(5);
File center = std::max(FILE_B, std::min(FILE_G, file_of(ksq)));
for (File f = File(center - 1); f <= File(center + 1); ++f)
File center = std::max(FILE_B, std::min(FILE_G, file_of(ksq)));
for (File f = File(center - 1); f <= File(center + 1); ++f)