From 82e13b6bebd85a152ededcfd75495c0c0f642354 Mon Sep 17 00:00:00 2001 From: John Naylor Date: Wed, 6 Jul 2022 15:50:09 +0700 Subject: [PATCH v4 4/4] Use vectorized lookahead in json_lex_string on x86 --- src/common/jsonapi.c | 48 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) diff --git a/src/common/jsonapi.c b/src/common/jsonapi.c index 81e176ad8d..44e8ed2b2f 100644 --- a/src/common/jsonapi.c +++ b/src/common/jsonapi.c @@ -24,6 +24,12 @@ #include "miscadmin.h" #endif +/* WIP: put somewhere sensible and consider removing CRC from the names */ +#if (defined (__x86_64__) || defined(_M_AMD64)) && (defined(USE_SSE42_CRC32C) || defined(USE_SSE42_CRC32C_WITH_RUNTIME_CHECK)) +#include +#define USE_SSE2 +#endif + /* * The context of the parser is maintained by the recursive descent * mechanism, but is passed explicitly to the error reporting routine @@ -842,12 +848,54 @@ json_lex_string(JsonLexContext *lex) } else { +#ifdef USE_SSE2 + __m128i block, + has_backslash, + has_doublequote, + control, + has_control, + error_cum = _mm_setzero_si128(); + const __m128i backslash = _mm_set1_epi8('\\'); + const __m128i doublequote = _mm_set1_epi8('"'); + const __m128i max_control = _mm_set1_epi8(0x1F); +#endif /* start lookahead at current byte */ char *p = s; if (hi_surrogate != -1) return JSON_UNICODE_LOW_SURROGATE; +#ifdef USE_SSE2 + while (p < end - sizeof(__m128i)) + { + block = _mm_loadu_si128((const __m128i *) p); + + /* direct comparison to quotes and backslashes */ + has_backslash = _mm_cmpeq_epi8(block, backslash); + has_doublequote = _mm_cmpeq_epi8(block, doublequote); + + /* + * use saturation arithmetic to check for <= highest control + * char + */ + control = _mm_subs_epu8(block, max_control); + has_control = _mm_cmpeq_epi8(control, _mm_setzero_si128()); + + /* + * set bits in error_cum where the corresponding lanes in has_* + * are set + */ + error_cum = _mm_or_si128(error_cum, has_backslash); + error_cum = _mm_or_si128(error_cum, has_doublequote); + error_cum = _mm_or_si128(error_cum, has_control); + + if (_mm_movemask_epi8(error_cum)) + break; + + p += sizeof(__m128i); + } +#endif /* USE_SSE2 */ + while (p < end) { if (*p == '\\' || *p == '"') -- 2.36.1