https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96159
Gabriel Ravier <gabravier at gmail dot com> changed:
What |Removed |Added
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CC| |gabravier at gmail dot com
--- Comment #8 from Gabriel Ravier <gabravier at gmail dot com> ---
I do agree that either:
- GCC's behavior should be aligned with Clang's and that it should provide some
kind of "known-aligned load" function (along with the corresponding ones for
store/exchange/compare_exchange)
- or there should at least be some kind of "safe load" function (along with the
corresponding ones) for the cases where the alignment is unknown.
I personally do prefer the first solution, personally, unless the Clang devs
can be convinced to change their builtin, as I think it would be better to have
the same behavior on both compilers.
In any case, though, I do think there is a documentation bug here, and I would
also say it would be quite nice to have a warning when using the built-in in a
way that makes it much slower/invalid, like what Clang does:
<source>:240:5: warning: misaligned atomic operation may incur significant
performance penalty; the expected alignment (8 bytes) exceeds the actual
alignment (4 bytes) [-Watomic-alignment]
__atomic_load(x, &r, __ATOMIC_SEQ_CST);
^
