[lttng-dev] [PATCH 02/11] urcu/uatomic: Use atomic builtins if configured

[Olivier Dion]

On Thu, 22 Jun 2023, "Paul E. McKenney" <paulmck at 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].

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

-- 
Olivier Dion
EfficiOS Inc.
https://www.efficios.com