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

[Emanuel Peter]

On Tue, 16 Sep 2025 01:24:35 GMT, Dean Long <dlong at openjdk.org> wrote:

>> Could we also bail out here? Or what would happen now in production if there is a RF edge?
>
> We also use this area past endoff() for storing the "ex_oop" (see for example GraphKit::has_saved_ex_oop()).  Are ex_oop and reachability edges mutually exclusive?

@dean-long @iwanowww Ok, but probably there will at some point be a conflict. And if RF are rather rare, we will not notice so fast. Or would your stress flag catch the conflict?

Is there not a way to make it clear/explicit which edges are there for what reason?

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PR Review Comment: https://git.openjdk.org/jdk/pull/25315#discussion_r2358840330