[Bug target/80878] -mcx16 (enable 128 bit CAS) on x86_64 seems not to work on 7.1.0

s_gccbugzilla at nedprod dot com gcc-bugzilla@gcc.gnu.org
Fri May 7 14:44:30 GMT 2021


https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80878

--- Comment #35 from Niall Douglas <s_gccbugzilla at nedprod dot com> ---
(In reply to Jonathan Wakely from comment #34)

> > Perhaps I ought to open a separate issue here, as my specific problem is
> > that std::atomic<__int128>::compare_exchange_weak() is not using cmpxchg16b?
> 
> Isn't that covered by PR 94649?

That issue is definitely closer to mine, but still not the same. Still, I'll
relocate this report from here to there. Thanks for pointing me at it.


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