RFR: 8290892: C2: Intrinsify Reference.reachabilityFence [v3]

[Aleksey Shipilev]

On Thu, 22 May 2025 22:23:48 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

>> Now that I read the next hunk, should `is_DecodeN` be `is_DecodeNarrowPtr` to capture class loads (however unlikely that one is)?
>
> `ReachabilityFence` accepts only OOPs as a referent and `DecodeNKlass` produces `Klass` pointer.
> 
> I suspect it may be the case for safepoints as well (and `is_DecodeNarrowPtr()` is a a leftover from PermGen world), but I didn't check.

Right, nevermind about `DecodeNKlass` then. My question on heap loads still stands: do we actually get `reachabilityFence(someField)` from anywhere?

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

PR Review Comment: https://git.openjdk.org/jdk/pull/25315#discussion_r2107155845