RFR: 8256011: Shenandoah: Don't resurrect finalizably reachable objects [v3]

[Roman Kennke]

On Tue, 10 Nov 2020 11:02:11 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> Dunno. Could do that. Within one instance of JVM, we would never see both narrow/non-narrow versions, though.
>
> I would be more straight-forward looking, AFAICS. Is there any code that actually matches those strings?

I don't think any code matches those strings. I will change them to be more specific.

>> It is the same, but in my testing I found that ON_STRONG_OOP_REF is not always set (it is the default when no other ON_XYZ_OOP_REF is specified).
>
> Ouch. That means we should never trust `ON_STRONG_OOP_REF`, and instead go for `SBS::is_strong_access`?

Presumably, the Access machinery is supposed to fill it in when none of the others is set. In practice, it did not work for me. We could fix the access machinery too, but life's too short?

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PR: https://git.openjdk.java.net/jdk/pull/1109