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Remove Some Bitboard Arrays (#1963)

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This is non-functional. These 5 arrays are simple enough to calculate real-time and maintaining an array for them does not help. Decreases the memory footprint.

This seems a tiny bit slower on my machine, but passed STC well enough. Could someone verify speed?

STC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 44745 W: 9780 L: 9704 D: 25261
http://tests.stockfishchess.org/tests/view/5c47aa2d0ebc5902bca13fc4

The slowdown is minimal even in 32 bit case (thanks to @mstembera for testing):

Compiled using make build ARCH=x86-32 CXX=i686-w64-mingw32-c++ and benched
This patch only:

```
Results for 40 tests for each version:

            Base      Test      Diff      
    Mean    1455204   1450033   5171      
    StDev   49452     34533     59621     

p-value: 0.465
speedup: -0.004
```

No functional change.
This commit is contained in:
protonspring
2019-02-08 01:54:38 -07:00
committed by Marco Costalba
parent 6514500236
commit dd4796fcd5
2 changed files with 9 additions and 36 deletions
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21
src/bitboard.cpp
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@@ -27,15 +27,10 @@ uint8_t PopCnt16[1 << 16];
int8_t SquareDistance[SQUARE_NB][SQUARE_NB];
Bitboard SquareBB[SQUARE_NB];
Bitboard FileBB[FILE_NB];
Bitboard RankBB[RANK_NB];
Bitboard ForwardRanksBB[COLOR_NB][RANK_NB];
Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
Bitboard LineBB[SQUARE_NB][SQUARE_NB];
Bitboard DistanceRingBB[SQUARE_NB][8];
Bitboard ForwardFileBB[COLOR_NB][SQUARE_NB];
Bitboard PassedPawnMask[COLOR_NB][SQUARE_NB];
Bitboard PawnAttackSpan[COLOR_NB][SQUARE_NB];
Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
Bitboard PawnAttacks[COLOR_NB][SQUARE_NB];
@@ -90,22 +85,8 @@ void Bitboards::init() {
for (Square s = SQ_A1; s <= SQ_H8; ++s)
SquareBB[s] = (1ULL << s);
for (File f = FILE_A; f <= FILE_H; ++f)
FileBB[f] = f > FILE_A ? FileBB[f - 1] << 1 : FileABB;
for (Rank r = RANK_1; r <= RANK_8; ++r)
RankBB[r] = r > RANK_1 ? RankBB[r - 1] << 8 : Rank1BB;
for (Rank r = RANK_1; r < RANK_8; ++r)
ForwardRanksBB[WHITE][r] = ~(ForwardRanksBB[BLACK][r + 1] = ForwardRanksBB[BLACK][r] | RankBB[r]);
for (Color c = WHITE; c <= BLACK; ++c)
for (Square s = SQ_A1; s <= SQ_H8; ++s)
{
ForwardFileBB [c][s] = ForwardRanksBB[c][rank_of(s)] & FileBB[file_of(s)];
PawnAttackSpan[c][s] = ForwardRanksBB[c][rank_of(s)] & adjacent_files_bb(file_of(s));
PassedPawnMask[c][s] = ForwardFileBB [c][s] | PawnAttackSpan[c][s];
}
ForwardRanksBB[WHITE][r] = ~(ForwardRanksBB[BLACK][r + 1] = ForwardRanksBB[BLACK][r] | rank_bb(r));
for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1)
for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2)