7902944: JMH: Avoid weak references in Blackhole.consume(Object)

[shipilev]

See the bug for rationale. This avoids WeakReference-s completely through the aliased box trick. Not only this solves the original problem with inline types, it also allows for prompt reclamation of the objects, without relying on the specifics of VM reference processing.

I looked at jmh-core-benchmarks results, and they suggest this still works reliably without compiler blackholes. Compiler blackholes make all of this irrelevant.

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Issue

• CODETOOLS-7902944: JMH: Avoid weak references in Blackhole.consume(Object) (Enhancement - P4)

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