https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80878
LIU Hao <lh_mouse at 126 dot com> changed:
What |Removed |Added
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CC| |lh_mouse at 126 dot com
--- Comment #36 from LIU Hao <lh_mouse at 126 dot com> ---
(In reply to Andrew Pinski from comment #1)
> IIRC this was removed as the instruction cannot be used for read only memory.
That's not a valid argument. The first argument is a pointer to non-const type,
and whoever passes a read-only object bears the risk on their own.
As mention in previous posts, the double-word compare-and-swap operation is
invaluable for many algorithms. The fact that GCC does not generate it, even
when requested explicitly with `-mcx16`, is silly and unacceptable.
--- Comment #37 from LIU Hao <lh_mouse at 126 dot com> ---
(In reply to Andrew Pinski from comment #31)
> Again the problem is stuff like:
> static const _Atomic __int128_t t = 2000;
>
> __int128_t g(void)
> {
> return t;
> }
>
> DOES NOT WORK if you use CAS (or ldaxp/stlxp).
>
Can this be made using MOVDQA instead? I haven't tested this though, just out
of curiosity.
