On Wed, 10 May 2023 13:33:02 GMT, Richard Reingruber <rr...@openjdk.org> wrote:
>> GC barriers are used when loading or storing an oop. No GC we currently have >> (not even the generational ones) use barriers for loading a plain address >> from an oop. The PPC64 implementation of the BarrierSetAssembler currently >> has `Unimplemented()` for non-oop types and all GCs are implemented. >> Maybe it was intended for some future GC or other feature which has not yet >> reached the official repo. > > You are reasoning about implementation details. By using the provided > abstraction you and other maintainers (who might be unfamiliar with them) > would not have to do that. Also the assumptions you make introduce a hidden > dependency. I just figured it out. It was introduced by https://bugs.openjdk.org/browse/JDK-8203172 (on aarch64) which mentions Shenandoah and future GCs. However, the Shenandoah comment says "non-reference load, no additional barrier is needed" and it doesn't use barriers in such a case. So, for the time being, I'll keep the normal load (because `access_load_at` is not ready for non-oop types). But I should add the `NONZERO` check. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/12708#discussion_r1189934352
