RFR: 8338526: Don't store abstract and interface Klasses in class metaspace [v4]

[Markus Grönlund]

On Thu, 29 Aug 2024 17:30:26 GMT, Markus Grönlund <mgronlun at openjdk.org> wrote:

>> // Return TRUE only if UseCompressedClassPointers is True.
>>   static bool using_class_space() {
>>     return NOT_LP64(false) LP64_ONLY(UseCompressedClassPointers);
>>   }
>>   
>>   I see now that was wrong for 32-bit.
>
> In summary, we are agnostic about which space the Klass* is located in; we only care if a valid means exists to perform an encode() and decode() operation to compress the Klass* (for 64-bit to be clear). This may now become a function of what space the Klass resides in?

Its very rare, if at all, that an abstract or an interface would be tagged in JFR. Tags are for concrete implementations, mostly InstanceKlass*.

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PR Review Comment: https://git.openjdk.org/jdk/pull/19157#discussion_r1736795292