RFR: 8347422: Crash during safepoint handler execution with -XX:+UseAPX

[Tobias Hartmann]

On Fri, 10 Jan 2025 13:24:21 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

> This bug fix patch fixes an internal error seen during safepoint handler execution.
> The problem occurs due to missing handling for REX2 prefixed polling test instruction.
> 
> Manually verified the patch with the -XX:+SafepointALot runtime flag.
> 
> Best Regards,
> Jatin
> PS: Patch will be opened for review after some validation.

Thanks Jatin. In this case I would suggest that we should add a VM stress flag to give preference to EGPRs, or maybe [JDK-8343294](https://bugs.openjdk.org/browse/JDK-8343294) is good enough?

Do the existing tests trigger this even without `-XX:+SafepointALot`?

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PR Comment: https://git.openjdk.org/jdk/pull/23035#issuecomment-2586861370