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From: "fw at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/80878] -mcx16 (enable 128 bit CAS) on x86_64 seems not
 to work on 7.1.0
Date: Sat, 18 Apr 2020 17:23:50 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D80878

--- Comment #21 from Florian Weimer <fw at gcc dot gnu.org> ---
(In reply to Avi Kivity from comment #20)
> Note that clang generates cmpxchg16b when the conditions are ripe:
>=20
> https://godbolt.org/z/j9Whgh

I believe this is a different, C++-specific issue. The C front end already
emits cmpxchgq in this situation.=