[jdk17u-dev] RFR: 8357968: RISC-V: Interpreter volatile reference stores with G1 are not sequentially consistent

[Robbin Ehn]

On Wed, 25 Jun 2025 15:07:07 GMT, Feilong Jiang <fjiang at openjdk.org> wrote:

> Fixes RISC-V memory ordering problem.
> This patch is not clean because [JDK-8293290](https://bugs.openjdk.org/browse/JDK-8293290) adds a third temporary register to `store_heap_oop`, which is introduced in JDK20. 
> In JDK17, `do_oop_store` also clobbers the same `x13` as in mailine. The current fix is similar to aarch64 in mainline, but puts the flags in `x15` instead, to avoid the clobber of the volatile bits.
> 
> Additional testing:
> - [x] linux-riscv64 server release, jcstress `RefDekker` test now passes
> - [x] linux-riscv64 server release, Tier1-3

Looks good!

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Marked as reviewed by rehn (Committer).

PR Review: https://git.openjdk.org/jdk17u-dev/pull/3678#pullrequestreview-2961023266