simdjson is one of those libraries where every architecture is hand-tuned
and every intrinsic chosen on purpose. Adding a LoongArch LSX backend for
find_next_json_quotable_character wasn't really new code. It
was translating an idea that already lived, fluently, in NEON and SSE2.
The function
The string builder needs to know where the next "quotable" byte is: a
backslash, a quote, or a control byte below 0x20. Done one
byte at a time, that is a slow loop. Done with SIMD, it is one masked
compare across sixteen bytes at a time.
Full write-up coming. This is a stub.