On Wed, May 31, 2023 at 03:04:03PM +0100, Jonathan Wakely via Gcc-patches wrote:
> On Wed, 31 May 2023 at 13:23, Jonathan Wakely via Libstdc++ <
> libstd...@gcc.gnu.org> wrote:
>
> > Tested powerpc64le-linux. Pushed to trunk.
> >
> > -- >8 --
> >
> > As suggested by Jakub in the PR, this just hardcodes the constants with
> > a Q suffix, since the properties of __float128 are not going to change.
> >
> > We can only define it for non-strict modes because the suffix gives an
> > error otherwise, even in system headers:
> >
> > limits:2085: error: unable to find numeric literal operator 'operator""Q'
> >
> > libstdc++-v3/ChangeLog:
> >
> > PR libstdc++/104772
> > * include/std/limits (numeric_limits<__float128>): Define.
> > * testsuite/18_support/numeric_limits/128bit.cc: New test.
> >
>
> I should have tested this with clang before pushing:
>
> /home/jwakely/gcc/latest/lib/gcc/x86_64-pc-linux-gnu/14.0.0/../../../../include/c++/14.0.0/limits:2125:
> 16: error: use of undeclared identifier '__builtin_huge_valq'
> { return __builtin_huge_valq(); }
> ^
> /home/jwakely/gcc/latest/lib/gcc/x86_64-pc-linux-gnu/14.0.0/../../../../include/c++/14.0.0/limits:2129:
> 16: error: use of undeclared identifier '__builtin_nanq'
> { return __builtin_nanq(""); }
> ^
> /home/jwakely/gcc/latest/lib/gcc/x86_64-pc-linux-gnu/14.0.0/../../../../include/c++/14.0.0/limits:2133:
> 16: error: use of undeclared identifier '__builtin_nansq'
> { return __builtin_nansq(""); }
> ^
See my comments in bugzilla how to support this stuff even without
being able to use Q suffixes.
As for the builtins, no reason not to use __float128(__builtin_huge_val())
for the first case or __float128(__builtin_nan("")) for the second case.
I'm afraid there is nothing that can be done about signalling NaN
of neither __builtin_nansq nor __builtin_nansf128 is supported.
Jakub
