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

[Markus Grönlund]

On Fri, 16 May 2025 08:47:27 GMT, Markus Grönlund <mgronlun at openjdk.org> wrote:

> Thanks. So if we create the request as mentioned before I’m not sure that check will do it. I see it’s checking for enterSpecial instead of its caller. Also I see we only get there in the interpreted case, but the caller of enterSpecial could be compiled. I was thinking of an early check where if we are in a vthread and the sample request is not within the continuation just do a bias sampling.

Its only the interpreter that needs special handling for this case, because of the rbp thingy. The JIT should just work as normal. Thats why I stop iff the sampled interpreter frame is enterSpecial and is a termination point for the virtual thread.

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PR Review Comment: https://git.openjdk.org/jdk/pull/24296#discussion_r2092651895