RFR: 8352251: Implement JEP 518: JFR Cooperative Sampling [v23]

[Markus Grönlund]

On Thu, 15 May 2025 22:29:48 GMT, Markus Grönlund <mgronlun at openjdk.org> wrote:

>> The description might not be detailed enough: we are updating one of the physical registers in a staged leave, but this is only visible to anyone directly inspecting the CPU context, such as a cpu sampler.  Anything logical, working in the JVM, especially ljfs, will work just as before.
>
> The JVMTI things should have already been done before we start to manipulate the rbp, just like before.

"this_fp" means "this frame's fp", before it moved.

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PR Review Comment: https://git.openjdk.org/jdk/pull/24296#discussion_r2092054957