RFR: 8339642: Reduce overheads in InvokerBytecodeGenerator

[Claes Redestad]

On Fri, 6 Sep 2024 10:01:39 GMT, Claes Redestad <redestad at openjdk.org> wrote:

> - A small portion (~5%) of the instrumented overhead when spinning MH/LF classes in `InvokeBytecodeGenerator` comes from creating the exact same `RuntimeVisibleAnnotationsAttribute` for every method. Introducing a couple of constants has a small but measurable impact.
> - `classDesc(MemberName.class)` is called ~8000 times during an OpenJDK build, `classDesc(MethodType.class)` ~900 - special casing looks profitable
> - Class name validation narrowed down, use ReferenceClassDescImpl.ofValidated
> - Various minor optimizations helping reduce bytecode size and speed up interpreter execution

(This is part of a series of mitigations for regressions caused by the migration to the classfile API, see https://bugs.openjdk.org/browse/JDK-8338542)

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PR Comment: https://git.openjdk.org/jdk/pull/20887#issuecomment-2333866592