RFR: 8329629: GC interfaces should work directly against nmethod instead of CodeBlob

[Stefan Karlsson]

On Fri, 5 Apr 2024 12:32:30 GMT, Stefan Karlsson <stefank at openjdk.org> wrote:

> The GCs scan and handles nmethods and ignores CodeBlobs of other kinds. The I propose that we stop sending in CodeBlobs to the GCs and make sure to only give them nmethods.
> 
> I removed `void CodeCache::blobs_do(CodeBlobClosure* f)` since there's no more usage of that function. Is this OK?
> 
> I also opted to skipped calling the GC verification code from the iterator code:
> 
> Universe::heap()->verify_nmethod((nmethod*)cb);
> 
> IMHO, I think it is up to the GCs to decide if they want to perform extra nmethod verification. If someone wants to keep this verification in their favorite GC I can add calls to this function where we used to call CodeCache::blobs_do.
> 
> I've only done limited testing and will run extensive testing concurrent with the review.

Thanks for the reviews! I'll let GHA complete before integrating.

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PR Comment: https://git.openjdk.org/jdk/pull/18653#issuecomment-2044313453