RFR: 8366584: Add an InstanceKlass::super() method that returns InstanceKlass*

[Coleen Phillimore]

On Tue, 2 Sep 2025 04:59:09 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> By adding an `InstanceKlass* InstanceKlass::super()` method to shadow `Klass* Klass:super()`, this PR makes it possible to simplify the following code
>> 
>> 
>> InstanceKlass* ik;
>> InstanceKlass* s;
>> s = InstanceKlass::cast(ik->super()); // before JDK-8366024 
>> s = ik->java_super(); // after JDK-8366024 
>> 
>> 
>> to
>> 
>> 
>> s = k->super();
>> 
>> 
>> So you no longer need to do casting or need to understand what `java_super()` is.
>
> src/hotspot/share/oops/instanceKlass.hpp line 924:
> 
>> 922:   // always an InstanceKlass (or nullptr)
>> 923:   InstanceKlass* super() const {
>> 924:     return (Klass::super() == nullptr) ? nullptr : InstanceKlass::cast(Klass::super());
> 
> Is it better/simpler/cleaner to just do:
> 
> return static_cast<InstanceKlass*>(Klass::super());
> 
> ?

I think the term is "hides" not "shadows".  InstanceKlass::cast() is better - one additional check that super is always another InstanceKlass.

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PR Review Comment: https://git.openjdk.org/jdk/pull/27037#discussion_r2315826675