RFR: 8290892: C2: Intrinsify Reference.reachabilityFence [v11]

[Emanuel Peter]

On Thu, 18 Sep 2025 11:59:52 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> It's solely an implementation limitation. As of now, the only structure imposed on safepoint inputs relates to debug info (represented as JVMState). The rest is adhoc and there are many conflicting use cases introduced over time. The proper way to address it is to introduce proper structure for non-debug inputs, but it requires significant engineering effort to properly handle it across the whole compilation pipeline. For now, I just work-around it by performing additional transformation to avoid conflicts with existing functionality.
>
> Maybe we should do that effort soon, otherwise we just keep heaping up tech dept :/

And who knows, maybe conflicts are only avoided by accident, and maybe just because we did not encounter cases where the different features actually overlap and conflict. Or are we confident that we generated sufficient cases with overlaps of the different features that use the safepoint inputs?

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PR Review Comment: https://git.openjdk.org/jdk/pull/25315#discussion_r2358857194