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[libc++] Optimize std::has_single_bit #133063

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[libc++] Optimize std::has_single_bit #133063

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549d11d
[libc++] Optimize std::has_single_bit
Alcaro Mar 26, 2025
144f83e
[libc++] Optimize std::has_single_bit v2.0
Alcaro Nov 5, 2025
dbfb289
Merge branch 'main' into patch-6
Alcaro Nov 5, 2025
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2 changes: 1 addition & 1 deletion libcxx/include/__bit/has_single_bit.h
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Expand Up @@ -25,7 +25,7 @@ _LIBCPP_BEGIN_NAMESPACE_STD

template <__libcpp_unsigned_integer _Tp>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr bool has_single_bit(_Tp __t) noexcept {
return __t != 0 && (((__t & (__t - 1)) == 0));
return __builtin_popcountg(__t) == 1;
}

_LIBCPP_END_NAMESPACE_STD
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