[Bug middle-end/96200] Implement __builtin_thread_pointer() and __builtin_set_thread_pointer() if TLS is supported

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96200

--- Comment #9 from H.J. Lu <hjl.tools at gmail dot com> ---
(In reply to Florian Weimer from comment #8)
> (In reply to H.J. Lu from comment #7)
> > Give that the tcb field is setup by the C run-time on Linux/x86, should
> > it be provided by a run-time header file?
> 
> Yes, it seems reasonable to me. Ideally, it would be documented in the ABI
> manual as well.

https://gitlab.com/x86-psABIs/x86-64-ABI/-/merge_requests/14