weaselab/conflict-set
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Add an avx512bw longestCommonPrefix

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This commit is contained in:
Andrew Noyes
2024-08-02 16:43:58 -07:00
parent 9b3e1b219b
commit 857b402fe2
1 changed files with 27 additions and 0 deletions
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27
ConflictSet.cpp
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@@ -1673,6 +1673,33 @@ int firstNeqStride(const uint8_t *ap, const uint8_t *bp) {
#endif
}
#if defined(__x86_64__) && !defined(__SANITIZE_THREAD__)
__attribute__((target("avx512bw"))) int
longestCommonPrefix(const uint8_t *ap, const uint8_t *bp, int cl) {
int i = 0;
int end = cl & ~63;
while (i < end) {
const uint64_t eq =
_mm512_cmpeq_epi8_mask(_mm512_loadu_epi8(ap), _mm512_loadu_epi8(bp));
if (eq != uint64_t(-1)) {
return i + std::countr_one(eq);
}
i += 64;
ap += 64;
bp += 64;
}
if (i < cl) {
const uint64_t mask = (uint64_t(1) << (cl - i)) - 1;
const uint64_t eq = _mm512_cmpeq_epi8_mask(
_mm512_maskz_loadu_epi8(mask, ap), _mm512_maskz_loadu_epi8(mask, bp));
return i + std::countr_one(eq & mask);
}
assert(i == cl);
return i;
}
__attribute__((target("default")))
#endif
int longestCommonPrefix(const uint8_t *ap, const uint8_t *bp, int cl) {
assume(cl >= 0);
int i = 0;