RFR: 8367142: Avoid InstanceKlass::cast when converting java mirror to InstanceKlass [v3]

[Ioi Lam]

On Wed, 10 Sep 2025 07:28:42 GMT, David Holmes <dholmes at openjdk.org> wrote:

>>> > So I am not sure if we really have that separation anymore.
>>> 
>>> I think it is more that there are many bits of code that actually form the "boundary" (prims, services, some runtime, jvmci, interpreter-related). But I guess it is hard to argue this makes it markedly worse.
>> 
>> Arguably the translation of Java mirrors to Klasses is also a boundary (from Java representation to VM representation) :-)
>> 
>> In reality I think because jobjects are easy to use and are just another kind of handle (like Handle and OopHandle), the leakage from JNI code to other parts of VM just happened naturally.
>> 
>>> > The code already assumes that it has an InstanceKlass, and I am not changing that.
>>> 
>>> Okay.
>> 
>> BTW I removed the JVMTI changes from this PR.
>
>> Arguably the translation of Java mirrors to Klasses is also a boundary (from Java representation to VM representation) :-)
> 
> The mirror is an oop, both oop and klass are internal VM representations.

Thanks @dholmes-ora @coleenp for the review

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PR Comment: https://git.openjdk.org/jdk/pull/27158#issuecomment-3294479460