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SIMD: Match control char and double quote in one pass #793

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Merged
byroot merged 1 commit into from
Apr 28, 2025
Merged

SIMD: Match control char and double quote in one pass #793

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25 changes: 10 additions & 15 deletions ext/json/ext/generator/generator.c
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Original file line number Diff line number Diff line change
Expand Up @@ -320,14 +320,12 @@ static inline FORCE_INLINE uint64_t neon_rules_update(const char *ptr)
{
uint8x16_t chunk = vld1q_u8((const unsigned char *)ptr);

const uint8x16_t lower_bound = vdupq_n_u8(' ');
const uint8x16_t backslash = vdupq_n_u8('\\');
const uint8x16_t dblquote = vdupq_n_u8('\"');
// Trick: c < 32 || c == 34 can be factored as c ^ 2 < 33
// https://lemire.me/blog/2025/04/13/detect-control-characters-quotes-and-backslashes-efficiently-using-swar/
const uint8x16_t too_low_or_dbl_quote = vcltq_u8(veorq_u8(chunk, vdupq_n_u8(2)), vdupq_n_u8(33));

uint8x16_t too_low = vcltq_u8(chunk, lower_bound);
uint8x16_t has_backslash = vceqq_u8(chunk, backslash);
uint8x16_t has_dblquote = vceqq_u8(chunk, dblquote);
uint8x16_t needs_escape = vorrq_u8(too_low, vorrq_u8(has_backslash, has_dblquote));
uint8x16_t has_backslash = vceqq_u8(chunk, vdupq_n_u8('\\'));
uint8x16_t needs_escape = vorrq_u8(too_low_or_dbl_quote, has_backslash);

return neon_match_mask(needs_escape);
}
Expand Down Expand Up @@ -467,14 +465,11 @@ static inline TARGET_SSE2 FORCE_INLINE int sse2_update(const char *ptr)
{
__m128i chunk = _mm_loadu_si128((__m128i const*)ptr);

const __m128i lower_bound = _mm_set1_epi8(' ');
const __m128i backslash = _mm_set1_epi8('\\');
const __m128i dblquote = _mm_set1_epi8('\"');

__m128i too_low = _mm_cmplt_epu8(chunk, lower_bound);
__m128i has_backslash = _mm_cmpeq_epi8(chunk, backslash);
__m128i has_dblquote = _mm_cmpeq_epi8(chunk, dblquote);
__m128i needs_escape = _mm_or_si128(too_low, _mm_or_si128(has_backslash, has_dblquote));
// Trick: c < 32 || c == 34 can be factored as c ^ 2 < 33
// https://lemire.me/blog/2025/04/13/detect-control-characters-quotes-and-backslashes-efficiently-using-swar/
__m128i too_low_or_dbl_quote = _mm_cmplt_epu8(_mm_xor_si128(chunk, _mm_set1_epi8(2)), _mm_set1_epi8(33));
__m128i has_backslash = _mm_cmpeq_epi8(chunk, _mm_set1_epi8('\\'));
__m128i needs_escape = _mm_or_si128(too_low_or_dbl_quote, has_backslash);
return _mm_movemask_epi8(needs_escape);
}

Expand Down
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