RFR: 8338939: Simplify processing of hidden class names [v2]

[Erik Gahlin]

On Mon, 26 Aug 2024 10:02:32 GMT, Markus Grönlund <mgronlun at openjdk.org> wrote:

>> Greetings,
>> 
>> The name symbol for hidden (anonymous) classes has evolved. Initially, it consisted of only a base class name, e.g., "java/lang/invoke/LambdaForm$BMH", so JFR had to introduce a scheme for disambiguating one anonymous class from another.
>> 
>> The scheme (which still exists in JFR) appends the Java class mirror's hashcode to the base class name, e.g., "java/lang/invoke/LambdaForm$BMH/22626602".
>> 
>> With [JDK-8238358](https://bugs.openjdk.org/browse/JDK-8238358), the disambiguation of hidden class names is now intrinsic to the processing by the ClassFileParser. This is done by appending the InstanceKlass address to the base class name, e.g., "java/lang/invoke/LambdaForm$BMH+0x000000001d190000".
>> 
>> An argument can be made that JFR specialization for hidden (anonymous) classes may no longer be necessary. Indeed, the result now involves a "double" disambiguation: e.g., "java/lang/invoke/LambdaForm$BMH+0x000000001d190000/231202600".
>> 
>> It is now possible to simplify the handling of hidden (anonymous) class names, which avoids using the Java mirror oop. We might want to keep the "/" construct as that might be an implicit invariant on users' expectations (quickly done by replacing "+" with "/").
>> 
>> Testing: jdk_jfr
>> 
>> Thanks
>> Markus
>
> Markus Grönlund has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - cleanup
>  - use existing k->external_name

Marked as reviewed by egahlin (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/20708#pullrequestreview-2263568386