RFR: Update nmethod caching and clean up unused/duplicate methods [v3]

[Ashutosh Mehra]

On Thu, 5 Jun 2025 00:31:41 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> I would suggest to use old `_code_ofset` for now. As we discussed on meeting we will need separate _metadata_offset to move all data describing code so we can map whole section of codes directly into CodeCache.
>
> Or we can compromise: `_codeblob_offset, _codeblob_size`
> Stubs are also using CodeBlob. I don't get why you treat stubs differently.

StubGenerator Stubs used CodeBlob, but in AOT CodeCache we don't store their CodeBlobs as we do for adapters/runtime blobs. We instead only copy the assembly code for each stub.

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PR Review Comment: https://git.openjdk.org/leyden/pull/71#discussion_r2127804951