On Sat, 10 Oct 2020 at 20:43, David Brown <david.brown@xxxxxxxxxxxx> wrote: > Is this strategy guaranteed to work in gcc, or is it a case of "it works > in a simple test, but might fail in a complicated program or with > different flags" ? I think it works by design. My understanding is that users providing their own implementation of those calls is fully supported. I think that's partly why libatomic.so is a distinct library, and not just part of libgcc_s.so. The docs aren't entirely clear about this, they just say that if the compiler can't emit lock-free instructions for the atomic operation "a call is made to an external routine with the same parameters to be resolved at run time." But I think that "to be resolved at run time" means that you can choose how those calls will be resolved.
