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Ensure that logb is constexpr #5901

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Merged
miscco merged 1 commit into from
Sep 17, 2025
Merged

Ensure that logb is constexpr #5901

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22 changes: 21 additions & 1 deletion libcudacxx/include/cuda/std/__cmath/logarithms.h
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Original file line number Diff line number Diff line change
Expand Up @@ -478,8 +478,28 @@ template <class _Tp>
case FP_INFINITE:
return ::cuda::std::__fp_inf<_Tp>();
default:
return static_cast<_Tp>(::cuda::std::__fp_get_exp(__x));
break;
}
#if _CCCL_HAS_CONSTEXPR_BIT_CAST()
return static_cast<_Tp>(::cuda::std::__fp_get_exp(__x));
#else // ^^^ _CCCL_HAS_CONSTEXPR_BIT_CAST() ^^^ / vvv !_CCCL_HAS_CONSTEXPR_BIT_CAST() vvv
// We need to go through the slow emulation for old GCC
if constexpr (__fp_is_native_type_v<_Tp>)
{
__x = ::cuda::std::fabs(__x);
unsigned long long __exp = 0;
while (__x >= _Tp(numeric_limits<_Tp>::radix))
{
__x /= numeric_limits<_Tp>::radix;
__exp += 1;
}
return static_cast<_Tp>(__exp);
}
else
{
return static_cast<_Tp>(::cuda::std::__fp_get_exp(__x));
}
#endif // !_CCCL_HAS_CONSTEXPR_BIT_CAST()
}

[[nodiscard]] _CCCL_API inline constexpr float logbf(float __x) noexcept
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