Am Sonntag, den 07.11.2021, 10:08 +0100 schrieb Martin Uecker: > It would be great if somebody could take a look at > PR96159. > > It seems we do not do atomic accesses correctly > when the alignment is insufficient for a lockfree > access, but I think we should fall back to a > library call in this case (as clang does). > > This is very unfortunate as it is an important > functionality to be able to do atomic accesses > on non-atomic types and it seems there is no way > to achieve this. > > Also documentation and various descriptions of > the atomic functions imply that this is expected > to work. > > But maybe I am missing something and the generated > code is indeed safe. > > Martin >
Could this bug be confirmed please? This is a silent and dangerous incorrect code generation issue. If these functions are not meant to be used to exising data, then at least the documentation needs to be changed and include a big warning that this only happens to work corectly if the data has sufficient alignment for the specific architecture (which of course makes it impossible to use this in a portable way). I would then propose to add atomic_load_safe, so that it is possible to use such functionality safely on existing data structures which is an important use case. Martin
