On Thu, 24 Jun 2021 at 15:08, Jakub Jelinek wrote:
>
> On Thu, Jun 24, 2021 at 04:01:34PM +0200, Matthias Kretz wrote:
> > --- a/libstdc++-v3/include/experimental/bits/simd.h
> > +++ b/libstdc++-v3/include/experimental/bits/simd.h
> > @@ -1598,7 +1598,9 @@ template <typename _To, typename _From>
> > _GLIBCXX_SIMD_INTRINSIC constexpr _To
> > __bit_cast(const _From __x)
> > {
> > - // TODO: implement with / replace by __builtin_bit_cast ASAP
> > +#if __has_builtin(__builtin_bit_cast)
>
> Shouldn't that use #if _GLIBCXX_HAS_BUILTIN(__builtin_bit_cast) in
> c++config to define a new macro and use that macro here?
> Though it is true that c++config already uses
> #if __has_builtin(__builtin_is_constant_evaluated)
> and so would fail miserably for compilers that don't support __has_builtin
GCC was the last of our supported compilers to implement
__has_builtin, so for GCC trunk we can assume that it's always
supported.
The code in c++config.h still has some value for built-ins that aren't
called __builtin_xxx because older versions of Clang need different
handling for those. But for __builtin_bit_cast and
__builtin_is_constant_evaluted we can just use __is_builtin directly.
