is-valid-utf8.c tweaks #449
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sjakobi
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@kozross could you possibly give this a quick look? |
…s because of GHC make build issues
…out vectorised instructions
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* Cabal check does not recognise arch(arm64) * is-valid-utf8: use __get_cpuid_count instead of __builtin_cpu_supports because of GHC make build issues * Check SSE2 support in runtime instead of compile time * Avoid code duplication: use bytestring_is_valid_utf8 on any arch without vectorised instructions * Further deduplication * Mark has_foo as static inline
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* Cabal check does not recognise arch(arm64) * is-valid-utf8: use __get_cpuid_count instead of __builtin_cpu_supports because of GHC make build issues * Check SSE2 support in runtime instead of compile time * Avoid code duplication: use bytestring_is_valid_utf8 on any arch without vectorised instructions * Further deduplication * Mark has_foo as static inline
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This branch was triggered into existence by GHC CI failures, but I used the opportunity to deduplicate some code as well.
The precise issue is that some GHC builds (https://gitlab.haskell.org/ghc/ghc/-/jobs/876320#L4200) are unhappy with our usage of
__cpu_indicator_init. It's more likely GHCmakewho is at fault here, but fighting it is so difficult. We use__get_cpuidfor CPU capabilities detection in SIMD code forcount:bytestring/cbits/fpstring.c
Lines 237 to 243 in 12303b8
and I also have good experience with
__get_cpuidintext(https://github.com/haskell/text/blob/master/cbits/measure_off.c).This PR replaces
__cpu_indicator_initwith__get_cpuid. Then we make SSE2 detection a runtime dispatch as well, similar to existing SSSE3 and AVX2 checks. This allows us to use fallback function on any platform, not only x86. Finally, I deduplicated fallback functions - there seems to be no measurable impact except extremely short strings, and I think that code clarity is more important here.