[Bug target/93177] PPC: Missing many useful platform intrinsics

[memmerto at ca dot ibm.com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93177

--- Comment #8 from Matt Emmerton <memmerto at ca dot ibm.com> ---
(In reply to Andrew Pinski from comment #5)
> > __lwarx()
> > __ldarx()
> > __stwcx()
> > __stdcx()
> 
> Is there a reason why the __atomic_* builtins don't work?

There are places in our code where we do manipulations of the lockword that
cannot be emulated by the __atomic_* builtins, and thus require us to emit
discrete larx/stcx instructions (with other goodness in between.)