On 6/22/23 15:53, Olivier Dion wrote:
On Thu, 22 Jun 2023, "Paul E. McKenney" <paul...@kernel.org> wrote:
I suggest C11 volatile atomic load/store. Load/store fusing is permitted
for non-volatile atomic loads and stores, and such fusing can ruin your
code's entire day. ;-)
Good catch. Seems like not a problem on GCC (yet), but Clang is extremely
aggressive and seems to do store fusing on some corner cases [0].
I don't think this is an example of store fusing, but rather just that
the compiler can eliminate stores to static variables which are
otherwise unused, making the entire variable useless.
Thanks,
Mathieu
However, I do not find any simple reproducer of load/store fusing. Do
you have example of such fusing, or is this a precaution? In the
meantime, back to reading the standard to be certain :-)
[0] https://godbolt.org/z/odKG9a75a
--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com
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