[Bug target/94649] 16-byte aligned atomic_compare_exchange doesn not generate cmpxcg16b on x86_64

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94649

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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             Target|                            |x86_64-*-*

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
It's also an ABI issue when code compiled with -mcx16 and without -mcx16 has to
inter-operate.  So it might be a deliberate choice and not a missed
optimization.