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

[Patricio Chilano Mateo]

On Thu, 15 May 2025 21:49:59 GMT, Patricio Chilano Mateo <pchilanomate at openjdk.org> wrote:

>> If I recall, which I don't, as it has been too long, the issue here is that since the IP is still in the interpreter, the rbp referenced in the enterSpecial frame links to an EntryFrame, which is not interpreter code. At least, what is linked in the Continuation is Java code, which can also be compiled; in this case, we can handle it. However, the challenge is to move the rbp, knowing that your IP is still in interpreter code. Can I handle that situation? That becomes the question.
>
> So we would just need to check when creating the request if the fp points to the ContinuationEntry, which is easy to do, and if so create the request with the sender (as I see you already do in one of the cases). This will also cover the case where the return pc is the return_barrier, which should in fact be more common than this case.

Also, thinking more about it if we are in the return_barrier case it’s the vthread that will continue executing. So one option could be to still create the request with the sender of the ContinuationEntry and just add a condition when processing it to check if the frame in the request is within the continuation.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/24296#discussion_r2092054094