[jdk17u-dev] RFR: 8351997: AArch64: Interpreter volatile reference stores with G1 are not sequentially consistent

[Aleksey Shipilev]

On Wed, 2 Jul 2025 12:19:05 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> Fixes AArch64 memory ordering problem. Readily manifests in new jcstress tests; there are sightings of related problems in JSR 133 tests. 
> 
> The patch is not clean, because [JDK-8301996](https://bugs.openjdk.org/browse/JDK-8301996) is in the way, and it is IMO too risky to backport. I picked up the JDK 21u backport version (https://git.openjdk.org/jdk21u-dev/commit/729f10053eab4b8fe8a857e14ce0f96a82c721b8), where I resolved some hunks to match the intended behavior, after checking `do_oop_store` clobbers the same `r3` as in mainline.
> 
> Additional testing:
>  - [x] Linux AArch64 server release, jcstress `RefDekker` test now passes
>  - [x] Linux AArch64 server release, jcstress `seqcst.volatiles.ref` tests now pass
>  - [x] Linux AArch64 server release, jcstress `all` tests now pass
>  - [x] Linux AArch64 server fastdebug, `all`

Thanks, here we go.

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PR Comment: https://git.openjdk.org/jdk17u-dev/pull/3697#issuecomment-3036275952