Add SVE implementations of bitset_meow_string - #6420
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Stephan T. Lavavej (StephanTLavavej) merged 18 commits intoSep 16, 2026
Merged
Stephan T. Lavavej (StephanTLavavej) merged 18 commits into
Stephan T. Lavavej (StephanTLavavej) merged 18 commits into
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Stephan T. Lavavej (StephanTLavavej)
added
performance
This computation was identical.
This isn't needed to guard against a do-nothing for-loop.
…`[_Size_convert, _Size_chars)`. `_Size_convert` is defined as `(_Size_chars <= _Size_bits) ? _Size_chars : _Size_bits`. That's equivalent to: `(_Size_bits < _Size_chars) ? _Size_bits : _Size_chars` `_Size_bits < _Size_chars` is the condition when this for-loop is going to do anything. When it's going to do something, `_Size_convert` is `_Size_bits`, so the behavior is unchanged. When it's going to be a no-op, `_Size_convert` is `_Size_chars`, so `_Ix < _Size_chars` is immediately false, so the no-op is unchanged.
…e_chars, _Size_convert` without confusing variation.
This matches how `_Size_convert` is used as the SVE threshold and makes much more sense. When `_Size_chars <= _Size_bits`, we set `_Size_convert` to `_Size_chars` and vectorize that much. The remaining bits are memset.
…lidate_extra`, equivalent to the first part of `_Finish_sve`.
This makes more sense given how it's used.
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Thanks! 😻 I pushed fairly significant refactorings to avoid code duplication, reusing the old I kept the old |
Stephan T. Lavavej (StephanTLavavej)
approved these changes
Sep 15, 2026
Stephan T. Lavavej (StephanTLavavej)
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I'm mirroring this to the MSVC-internal repo. Please notify me if any further changes are pushed, otherwise no action is required. |
Stephan T. Lavavej (StephanTLavavej)
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Stephan T. Lavavej (StephanTLavavej)
merged commit Sep 16, 2026
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This PR adds SVE implementations of
bitset_meow_string.As discussed on the STL discord, the ACLE does not expose explicit predicate load/store intrinsics, so this implementation uses explicit casts to/from
svbool_t*.Benchmark Results ⏲️
Neoverse N2 (Cobalt 100)
BM_bitset_to_string_large_single<512, char>BM_bitset_to_string_large_single<2048, char>BM_bitset_to_string_large_single<512, wchar_t>BM_bitset_to_string_large_single<2048, wchar_t>bitset_from_string<length_type::char_count, 16, char>bitset_from_string<length_type::char_count, 36, char>bitset_from_string<length_type::char_count, 64, char>bitset_from_string<length_type::char_count, 512, char>bitset_from_string<length_type::char_count, 2048, char>bitset_from_string<length_type::char_count, 16, wchar_t>bitset_from_string<length_type::char_count, 36, wchar_t>bitset_from_string<length_type::char_count, 64, wchar_t>bitset_from_string<length_type::char_count, 512, wchar_t>bitset_from_string<length_type::char_count, 2048, wchar_t>bitset_from_string<length_type::null_term, 16, char>bitset_from_string<length_type::null_term, 36, char>bitset_from_string<length_type::null_term, 64, char>bitset_from_string<length_type::null_term, 512, char>bitset_from_string<length_type::null_term, 2048, char>bitset_from_string<length_type::null_term, 16, wchar_t>bitset_from_string<length_type::null_term, 36, wchar_t>bitset_from_string<length_type::null_term, 64, wchar_t>bitset_from_string<length_type::null_term, 512, wchar_t>bitset_from_string<length_type::null_term, 2048, wchar_t>bitset_from_stream<16, char>bitset_from_stream<36, char>bitset_from_stream<64, char>bitset_from_stream<512, char>bitset_from_stream<2048, char>bitset_from_stream<16, wchar_t>bitset_from_stream<36, wchar_t>bitset_from_stream<64, wchar_t>bitset_from_stream<512, wchar_t>bitset_from_stream<2048, wchar_t>