RFR: 8354897: Support Soft/Weak Reference in AOT cache [v4]

[Dan Heidinga]

On Mon, 28 Apr 2025 21:08:10 GMT, Ioi Lam <iklam at openjdk.org> wrote:

>> We're creating a set of hooks - right now, there is one in MT - that are called by the VM at the appropriate time during the assembly phase to massage the class's state before we write the AOTCache out.
>> 
>> Conceptually any class could have a `prepareForAOTCache` method that would act as a front door for the VM to know how to set up its state.  
>> 
>> Right now we have a hard coded list of one class - MT - that we call `prepareForAOTCache` on.  Another way to implement this would be to loop through all classes that AOTCache candidates and call their `prepareForAOTCache` method (fi they have one).
>> 
>> If we expand this beyond MT, how does a reader of the code know which classes have VM call-in points and which don't?
>> 
>> (I'll mention here I missed the static modifier was only on MT which changes the argument a little but I still think different names would be clearer to diffierntiate between what the VM is expected to call and what may happen to the instances)
>
> How about `MethodType::assemblySetup()` for the entry point? This kind of mirrors the `runtimeSetup()` entry points that are called after the AOT cache is loaded. In the future, we can use annotation to mark such entry points to avoid explicit calls from the JVM.

That's a great choice!  It makes it clear when the method is run, parallels `runtimeSetup`, and differentiates it from the instance method helpers.  Thanks Ioi for working thru this with me!

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PR Review Comment: https://git.openjdk.org/jdk/pull/24757#discussion_r2066407185