RFR: 8341168: Cleanup dead code after JDK-8322630

[Stefan Karlsson]

On Mon, 30 Sep 2024 07:39:11 GMT, Axel Boldt-Christmas <aboldtch at openjdk.org> wrote:

> [JDK-8322630](https://bugs.openjdk.org/browse/JDK-8322630) / #17495 removed the the concept of ICStubs, InlineCache buffers and related safepoints.
> 
> There are a handfull of references and auxiliary constructs still in the code, I propose we clean these out.
> 
> This removes the unused:
>  * Experimental `InlineCacheBufferSize` option
>  * `InlineCacheBuffer_lock` mutex
>  * `Thread::_missed_ic_stub_refill_verifier` field
>  * `VM_ICBufferFull` VM operation

Looks good, but one small nit.

src/hotspot/share/runtime/thread.hpp line 246:

> 244:   HandleMark* last_handle_mark() const          { return _last_handle_mark; }
> 245:  private:
> 246: 

I think one of the blank lines should be left to retain the separation between `_last_handle_mark` and `_skip_gcalot`

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/code/StubQueue.java line 56:

> 54: 
> 55:   // The type of the contained stubs (i.e., InterpreterCodelet).
> 56:   // Must be a subclass of type Stub.

This is interesting. The StubQueue seems to work against an interface and that interface used to have two implementing classes. Now that one of the is gone, we might want to reconsider if we need this interface. There seems to be a lot of code that could be remove in this area. See `DEF_STUB_INTERFACE` and how it is being used.

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Marked as reviewed by stefank (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/21255#pullrequestreview-2336663437
PR Review Comment: https://git.openjdk.org/jdk/pull/21255#discussion_r1780601023
PR Review Comment: https://git.openjdk.org/jdk/pull/21255#discussion_r1780616803