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Introducing a fallback for clmul.

This commit is contained in:
Daniel Lemire 2019-06-03 15:10:14 -04:00
parent 06461a465b
commit e27a46973c
1 changed files with 25 additions and 9 deletions
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34
src/stage1_find_marks.cpp
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@ -48,6 +48,30 @@ struct simd_input {
#endif
};
really_inline uint64_t compute_quote_mask(uint64_t quote_bits) {
// In practice, if you have NEON or __PCLMUL__, you would
// always want to use them, but it might be useful, for research
// purposes, to disable it willingly, that's what SIMDJSON_AVOID_CLMUL
// does.
// Also: we don't know of an instance where AVX2 is supported but
// where clmul is not supported, so check for both, to be sure.
#if (defined(__PCLMUL__) || defined(__AVX2__)) && !defined(SIMDJSON_AVOID_CLMUL)
uint64_t quote_mask = _mm_cvtsi128_si64(_mm_clmulepi64_si128(
_mm_set_epi64x(0ULL, quote_bits), _mm_set1_epi8(0xFF), 0));
#elif defined(__ARM_NEON) && !defined(SIMDJSON_AVOID_CLMUL)
uint64_t quote_mask = vmull_p64( -1ULL, quote_bits);
#else
// this code should always be used if SIMDJSON_AVOID_CLMUL is defined.
uint64_t quote_mask = quote_bits ^ (quote_bits << 1);
quote_mask = quote_mask ^ (quote_mask << 2);
quote_mask = quote_mask ^ (quote_mask << 4);
quote_mask = quote_mask ^ (quote_mask << 8);
quote_mask = quote_mask ^ (quote_mask << 16);
quote_mask = quote_mask ^ (quote_mask << 32);
#endif
return quote_mask;
}
really_inline simd_input fill_input(const uint8_t * ptr) {
struct simd_input in;
#ifdef __AVX2__
@ -243,15 +267,7 @@ really_inline uint64_t find_quote_mask_and_bits(simd_input in, uint64_t odd_ends
uint64_t &prev_iter_inside_quote, uint64_t &quote_bits, uint64_t &error_mask) {
quote_bits = cmp_mask_against_input(in, '"');
quote_bits = quote_bits & ~odd_ends;
// remove from the valid quoted region the unescapted characters.
#ifdef __AVX2__
uint64_t quote_mask = _mm_cvtsi128_si64(_mm_clmulepi64_si128(
_mm_set_epi64x(0ULL, quote_bits), _mm_set1_epi8(0xFF), 0));
#elif defined(__ARM_NEON)
uint64_t quote_mask = vmull_p64( -1ULL, quote_bits);
#else
#warning It appears that neither ARM NEON nor AVX2 are detected.
#endif
uint64_t quote_mask = compute_quote_mask(quote_bits);
quote_mask ^= prev_iter_inside_quote;
// All Unicode characters may be placed within the
// quotation marks, except for the characters that MUST be escaped: