Generate lookup indices at compile time.

Credit to @Disservin: the constexpr lsb is just the De Bruijn bitscan with the xor from the cpw https://www.chessprogramming.org/BitScan

closes https://github.com/official-stockfish/Stockfish/pull/5801

No functional change
This commit is contained in:
mstembera
2025-01-18 14:26:41 -08:00
committed by Joost VandeVondele
parent 62ecdfe82c
commit 18b3465a86

View File

@@ -38,99 +38,41 @@
namespace Stockfish::Eval::NNUE::Layers {
#if (USE_SSSE3 | (USE_NEON >= 8))
static constexpr int lsb_index64[64] = {
0, 47, 1, 56, 48, 27, 2, 60, 57, 49, 41, 37, 28, 16, 3, 61, 54, 58, 35, 52, 50, 42,
21, 44, 38, 32, 29, 23, 17, 11, 4, 62, 46, 55, 26, 59, 40, 36, 15, 53, 34, 51, 20, 43,
31, 22, 10, 45, 25, 39, 14, 33, 19, 30, 9, 24, 13, 18, 8, 12, 7, 6, 5, 63};
constexpr int constexpr_lsb(uint64_t bb) {
assert(bb != 0);
constexpr uint64_t debruijn64 = 0x03F79D71B4CB0A89ULL;
return lsb_index64[((bb ^ (bb - 1)) * debruijn64) >> 58];
}
alignas(CacheLineSize) static constexpr struct OffsetIndices {
#if (USE_SSE41)
alignas(CacheLineSize) static constexpr std::uint8_t
std::uint8_t offset_indices[256][8];
#else
alignas(CacheLineSize) static constexpr std::uint16_t
std::uint16_t offset_indices[256][8];
#endif
lookup_indices[256][8] = {
{0, 0, 0, 0, 0, 0, 0, 0}, {0, 0, 0, 0, 0, 0, 0, 0}, {1, 0, 0, 0, 0, 0, 0, 0},
{0, 1, 0, 0, 0, 0, 0, 0}, {2, 0, 0, 0, 0, 0, 0, 0}, {0, 2, 0, 0, 0, 0, 0, 0},
{1, 2, 0, 0, 0, 0, 0, 0}, {0, 1, 2, 0, 0, 0, 0, 0}, {3, 0, 0, 0, 0, 0, 0, 0},
{0, 3, 0, 0, 0, 0, 0, 0}, {1, 3, 0, 0, 0, 0, 0, 0}, {0, 1, 3, 0, 0, 0, 0, 0},
{2, 3, 0, 0, 0, 0, 0, 0}, {0, 2, 3, 0, 0, 0, 0, 0}, {1, 2, 3, 0, 0, 0, 0, 0},
{0, 1, 2, 3, 0, 0, 0, 0}, {4, 0, 0, 0, 0, 0, 0, 0}, {0, 4, 0, 0, 0, 0, 0, 0},
{1, 4, 0, 0, 0, 0, 0, 0}, {0, 1, 4, 0, 0, 0, 0, 0}, {2, 4, 0, 0, 0, 0, 0, 0},
{0, 2, 4, 0, 0, 0, 0, 0}, {1, 2, 4, 0, 0, 0, 0, 0}, {0, 1, 2, 4, 0, 0, 0, 0},
{3, 4, 0, 0, 0, 0, 0, 0}, {0, 3, 4, 0, 0, 0, 0, 0}, {1, 3, 4, 0, 0, 0, 0, 0},
{0, 1, 3, 4, 0, 0, 0, 0}, {2, 3, 4, 0, 0, 0, 0, 0}, {0, 2, 3, 4, 0, 0, 0, 0},
{1, 2, 3, 4, 0, 0, 0, 0}, {0, 1, 2, 3, 4, 0, 0, 0}, {5, 0, 0, 0, 0, 0, 0, 0},
{0, 5, 0, 0, 0, 0, 0, 0}, {1, 5, 0, 0, 0, 0, 0, 0}, {0, 1, 5, 0, 0, 0, 0, 0},
{2, 5, 0, 0, 0, 0, 0, 0}, {0, 2, 5, 0, 0, 0, 0, 0}, {1, 2, 5, 0, 0, 0, 0, 0},
{0, 1, 2, 5, 0, 0, 0, 0}, {3, 5, 0, 0, 0, 0, 0, 0}, {0, 3, 5, 0, 0, 0, 0, 0},
{1, 3, 5, 0, 0, 0, 0, 0}, {0, 1, 3, 5, 0, 0, 0, 0}, {2, 3, 5, 0, 0, 0, 0, 0},
{0, 2, 3, 5, 0, 0, 0, 0}, {1, 2, 3, 5, 0, 0, 0, 0}, {0, 1, 2, 3, 5, 0, 0, 0},
{4, 5, 0, 0, 0, 0, 0, 0}, {0, 4, 5, 0, 0, 0, 0, 0}, {1, 4, 5, 0, 0, 0, 0, 0},
{0, 1, 4, 5, 0, 0, 0, 0}, {2, 4, 5, 0, 0, 0, 0, 0}, {0, 2, 4, 5, 0, 0, 0, 0},
{1, 2, 4, 5, 0, 0, 0, 0}, {0, 1, 2, 4, 5, 0, 0, 0}, {3, 4, 5, 0, 0, 0, 0, 0},
{0, 3, 4, 5, 0, 0, 0, 0}, {1, 3, 4, 5, 0, 0, 0, 0}, {0, 1, 3, 4, 5, 0, 0, 0},
{2, 3, 4, 5, 0, 0, 0, 0}, {0, 2, 3, 4, 5, 0, 0, 0}, {1, 2, 3, 4, 5, 0, 0, 0},
{0, 1, 2, 3, 4, 5, 0, 0}, {6, 0, 0, 0, 0, 0, 0, 0}, {0, 6, 0, 0, 0, 0, 0, 0},
{1, 6, 0, 0, 0, 0, 0, 0}, {0, 1, 6, 0, 0, 0, 0, 0}, {2, 6, 0, 0, 0, 0, 0, 0},
{0, 2, 6, 0, 0, 0, 0, 0}, {1, 2, 6, 0, 0, 0, 0, 0}, {0, 1, 2, 6, 0, 0, 0, 0},
{3, 6, 0, 0, 0, 0, 0, 0}, {0, 3, 6, 0, 0, 0, 0, 0}, {1, 3, 6, 0, 0, 0, 0, 0},
{0, 1, 3, 6, 0, 0, 0, 0}, {2, 3, 6, 0, 0, 0, 0, 0}, {0, 2, 3, 6, 0, 0, 0, 0},
{1, 2, 3, 6, 0, 0, 0, 0}, {0, 1, 2, 3, 6, 0, 0, 0}, {4, 6, 0, 0, 0, 0, 0, 0},
{0, 4, 6, 0, 0, 0, 0, 0}, {1, 4, 6, 0, 0, 0, 0, 0}, {0, 1, 4, 6, 0, 0, 0, 0},
{2, 4, 6, 0, 0, 0, 0, 0}, {0, 2, 4, 6, 0, 0, 0, 0}, {1, 2, 4, 6, 0, 0, 0, 0},
{0, 1, 2, 4, 6, 0, 0, 0}, {3, 4, 6, 0, 0, 0, 0, 0}, {0, 3, 4, 6, 0, 0, 0, 0},
{1, 3, 4, 6, 0, 0, 0, 0}, {0, 1, 3, 4, 6, 0, 0, 0}, {2, 3, 4, 6, 0, 0, 0, 0},
{0, 2, 3, 4, 6, 0, 0, 0}, {1, 2, 3, 4, 6, 0, 0, 0}, {0, 1, 2, 3, 4, 6, 0, 0},
{5, 6, 0, 0, 0, 0, 0, 0}, {0, 5, 6, 0, 0, 0, 0, 0}, {1, 5, 6, 0, 0, 0, 0, 0},
{0, 1, 5, 6, 0, 0, 0, 0}, {2, 5, 6, 0, 0, 0, 0, 0}, {0, 2, 5, 6, 0, 0, 0, 0},
{1, 2, 5, 6, 0, 0, 0, 0}, {0, 1, 2, 5, 6, 0, 0, 0}, {3, 5, 6, 0, 0, 0, 0, 0},
{0, 3, 5, 6, 0, 0, 0, 0}, {1, 3, 5, 6, 0, 0, 0, 0}, {0, 1, 3, 5, 6, 0, 0, 0},
{2, 3, 5, 6, 0, 0, 0, 0}, {0, 2, 3, 5, 6, 0, 0, 0}, {1, 2, 3, 5, 6, 0, 0, 0},
{0, 1, 2, 3, 5, 6, 0, 0}, {4, 5, 6, 0, 0, 0, 0, 0}, {0, 4, 5, 6, 0, 0, 0, 0},
{1, 4, 5, 6, 0, 0, 0, 0}, {0, 1, 4, 5, 6, 0, 0, 0}, {2, 4, 5, 6, 0, 0, 0, 0},
{0, 2, 4, 5, 6, 0, 0, 0}, {1, 2, 4, 5, 6, 0, 0, 0}, {0, 1, 2, 4, 5, 6, 0, 0},
{3, 4, 5, 6, 0, 0, 0, 0}, {0, 3, 4, 5, 6, 0, 0, 0}, {1, 3, 4, 5, 6, 0, 0, 0},
{0, 1, 3, 4, 5, 6, 0, 0}, {2, 3, 4, 5, 6, 0, 0, 0}, {0, 2, 3, 4, 5, 6, 0, 0},
{1, 2, 3, 4, 5, 6, 0, 0}, {0, 1, 2, 3, 4, 5, 6, 0}, {7, 0, 0, 0, 0, 0, 0, 0},
{0, 7, 0, 0, 0, 0, 0, 0}, {1, 7, 0, 0, 0, 0, 0, 0}, {0, 1, 7, 0, 0, 0, 0, 0},
{2, 7, 0, 0, 0, 0, 0, 0}, {0, 2, 7, 0, 0, 0, 0, 0}, {1, 2, 7, 0, 0, 0, 0, 0},
{0, 1, 2, 7, 0, 0, 0, 0}, {3, 7, 0, 0, 0, 0, 0, 0}, {0, 3, 7, 0, 0, 0, 0, 0},
{1, 3, 7, 0, 0, 0, 0, 0}, {0, 1, 3, 7, 0, 0, 0, 0}, {2, 3, 7, 0, 0, 0, 0, 0},
{0, 2, 3, 7, 0, 0, 0, 0}, {1, 2, 3, 7, 0, 0, 0, 0}, {0, 1, 2, 3, 7, 0, 0, 0},
{4, 7, 0, 0, 0, 0, 0, 0}, {0, 4, 7, 0, 0, 0, 0, 0}, {1, 4, 7, 0, 0, 0, 0, 0},
{0, 1, 4, 7, 0, 0, 0, 0}, {2, 4, 7, 0, 0, 0, 0, 0}, {0, 2, 4, 7, 0, 0, 0, 0},
{1, 2, 4, 7, 0, 0, 0, 0}, {0, 1, 2, 4, 7, 0, 0, 0}, {3, 4, 7, 0, 0, 0, 0, 0},
{0, 3, 4, 7, 0, 0, 0, 0}, {1, 3, 4, 7, 0, 0, 0, 0}, {0, 1, 3, 4, 7, 0, 0, 0},
{2, 3, 4, 7, 0, 0, 0, 0}, {0, 2, 3, 4, 7, 0, 0, 0}, {1, 2, 3, 4, 7, 0, 0, 0},
{0, 1, 2, 3, 4, 7, 0, 0}, {5, 7, 0, 0, 0, 0, 0, 0}, {0, 5, 7, 0, 0, 0, 0, 0},
{1, 5, 7, 0, 0, 0, 0, 0}, {0, 1, 5, 7, 0, 0, 0, 0}, {2, 5, 7, 0, 0, 0, 0, 0},
{0, 2, 5, 7, 0, 0, 0, 0}, {1, 2, 5, 7, 0, 0, 0, 0}, {0, 1, 2, 5, 7, 0, 0, 0},
{3, 5, 7, 0, 0, 0, 0, 0}, {0, 3, 5, 7, 0, 0, 0, 0}, {1, 3, 5, 7, 0, 0, 0, 0},
{0, 1, 3, 5, 7, 0, 0, 0}, {2, 3, 5, 7, 0, 0, 0, 0}, {0, 2, 3, 5, 7, 0, 0, 0},
{1, 2, 3, 5, 7, 0, 0, 0}, {0, 1, 2, 3, 5, 7, 0, 0}, {4, 5, 7, 0, 0, 0, 0, 0},
{0, 4, 5, 7, 0, 0, 0, 0}, {1, 4, 5, 7, 0, 0, 0, 0}, {0, 1, 4, 5, 7, 0, 0, 0},
{2, 4, 5, 7, 0, 0, 0, 0}, {0, 2, 4, 5, 7, 0, 0, 0}, {1, 2, 4, 5, 7, 0, 0, 0},
{0, 1, 2, 4, 5, 7, 0, 0}, {3, 4, 5, 7, 0, 0, 0, 0}, {0, 3, 4, 5, 7, 0, 0, 0},
{1, 3, 4, 5, 7, 0, 0, 0}, {0, 1, 3, 4, 5, 7, 0, 0}, {2, 3, 4, 5, 7, 0, 0, 0},
{0, 2, 3, 4, 5, 7, 0, 0}, {1, 2, 3, 4, 5, 7, 0, 0}, {0, 1, 2, 3, 4, 5, 7, 0},
{6, 7, 0, 0, 0, 0, 0, 0}, {0, 6, 7, 0, 0, 0, 0, 0}, {1, 6, 7, 0, 0, 0, 0, 0},
{0, 1, 6, 7, 0, 0, 0, 0}, {2, 6, 7, 0, 0, 0, 0, 0}, {0, 2, 6, 7, 0, 0, 0, 0},
{1, 2, 6, 7, 0, 0, 0, 0}, {0, 1, 2, 6, 7, 0, 0, 0}, {3, 6, 7, 0, 0, 0, 0, 0},
{0, 3, 6, 7, 0, 0, 0, 0}, {1, 3, 6, 7, 0, 0, 0, 0}, {0, 1, 3, 6, 7, 0, 0, 0},
{2, 3, 6, 7, 0, 0, 0, 0}, {0, 2, 3, 6, 7, 0, 0, 0}, {1, 2, 3, 6, 7, 0, 0, 0},
{0, 1, 2, 3, 6, 7, 0, 0}, {4, 6, 7, 0, 0, 0, 0, 0}, {0, 4, 6, 7, 0, 0, 0, 0},
{1, 4, 6, 7, 0, 0, 0, 0}, {0, 1, 4, 6, 7, 0, 0, 0}, {2, 4, 6, 7, 0, 0, 0, 0},
{0, 2, 4, 6, 7, 0, 0, 0}, {1, 2, 4, 6, 7, 0, 0, 0}, {0, 1, 2, 4, 6, 7, 0, 0},
{3, 4, 6, 7, 0, 0, 0, 0}, {0, 3, 4, 6, 7, 0, 0, 0}, {1, 3, 4, 6, 7, 0, 0, 0},
{0, 1, 3, 4, 6, 7, 0, 0}, {2, 3, 4, 6, 7, 0, 0, 0}, {0, 2, 3, 4, 6, 7, 0, 0},
{1, 2, 3, 4, 6, 7, 0, 0}, {0, 1, 2, 3, 4, 6, 7, 0}, {5, 6, 7, 0, 0, 0, 0, 0},
{0, 5, 6, 7, 0, 0, 0, 0}, {1, 5, 6, 7, 0, 0, 0, 0}, {0, 1, 5, 6, 7, 0, 0, 0},
{2, 5, 6, 7, 0, 0, 0, 0}, {0, 2, 5, 6, 7, 0, 0, 0}, {1, 2, 5, 6, 7, 0, 0, 0},
{0, 1, 2, 5, 6, 7, 0, 0}, {3, 5, 6, 7, 0, 0, 0, 0}, {0, 3, 5, 6, 7, 0, 0, 0},
{1, 3, 5, 6, 7, 0, 0, 0}, {0, 1, 3, 5, 6, 7, 0, 0}, {2, 3, 5, 6, 7, 0, 0, 0},
{0, 2, 3, 5, 6, 7, 0, 0}, {1, 2, 3, 5, 6, 7, 0, 0}, {0, 1, 2, 3, 5, 6, 7, 0},
{4, 5, 6, 7, 0, 0, 0, 0}, {0, 4, 5, 6, 7, 0, 0, 0}, {1, 4, 5, 6, 7, 0, 0, 0},
{0, 1, 4, 5, 6, 7, 0, 0}, {2, 4, 5, 6, 7, 0, 0, 0}, {0, 2, 4, 5, 6, 7, 0, 0},
{1, 2, 4, 5, 6, 7, 0, 0}, {0, 1, 2, 4, 5, 6, 7, 0}, {3, 4, 5, 6, 7, 0, 0, 0},
{0, 3, 4, 5, 6, 7, 0, 0}, {1, 3, 4, 5, 6, 7, 0, 0}, {0, 1, 3, 4, 5, 6, 7, 0},
{2, 3, 4, 5, 6, 7, 0, 0}, {0, 2, 3, 4, 5, 6, 7, 0}, {1, 2, 3, 4, 5, 6, 7, 0},
{0, 1, 2, 3, 4, 5, 6, 7}};
constexpr OffsetIndices() :
offset_indices() {
for (int i = 0; i < 256; ++i)
{
std::uint64_t j = i, k = 0;
while (j)
{
offset_indices[i][k++] = constexpr_lsb(j);
j &= j - 1;
}
while (k < 8)
offset_indices[i][k++] = 0;
}
}
} Lookup;
// Find indices of nonzero numbers in an int32_t array
template<const IndexType InputDimensions>
@@ -196,9 +138,9 @@ void find_nnz(const std::int32_t* input, std::uint16_t* out, IndexType& count_ou
}
for (IndexType j = 0; j < OutputsPerChunk; ++j)
{
const auto lookup = (nnz >> (j * 8)) & 0xFF;
const auto offsets =
vec128_load(reinterpret_cast<const vec128_t*>(&lookup_indices[lookup]));
const unsigned lookup = (nnz >> (j * 8)) & 0xFF;
const vec128_t offsets =
vec128_load(reinterpret_cast<const vec128_t*>(&Lookup.offset_indices[lookup]));
vec128_storeu(reinterpret_cast<vec128_t*>(out + count), vec128_add(base, offsets));
count += popcount(lookup);
base = vec128_add(base, increment);