[Bug target/97250] Implement -march=x86-64-v2, -march=x86-64-v3, -march=x86-64-v4 for x86-64

[fw at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97250

--- Comment #7 from Florian Weimer <fw at gcc dot gnu.org> ---
(In reply to H.J. Lu from comment #6)
> (In reply to Florian Weimer from comment #5)
> > (In reply to H.J. Lu from comment #4)
> > > x86-64-v2 includes CMPXCHG16B, aka CX16. But -mcx16 doesn't define 
> > > __CX16__.
> > 
> > It's called __GCC_HAVE_SYNC_COMPARE_AND_SWAP_16, I think. Is this good
> > enough?
> 
> Yes. But a test is missing.

Fair enough.  Are you going to send a patch?