[PATCH v2] x86: Define __HAVE_FLOAT128 for Clang and use __builtin_*f128 code path

[Joseph Myers]

On Thu, 19 Dec 2024, H.J. Lu wrote:

> From: Fangrui Song <i@maskray.me>
> 
> Clang supports __builtin_fabsf128 (despite not supporting _Float128) but
> it does not support __builtin_fabsq.  Fallback to back to
> `typedef __float128 _Float128;` it clang is used.

Did you check that every released Clang version supporting any of the 
glibc x86 targets also supports __float128?  Otherwise a version 
conditional would be needed.

-- 
Joseph S. Myers
josmyers@redhat.com