RFR: 8292059: Do not inline InstanceKlass::allocate_instance() [v3]

[Stefan Karlsson]

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On Thu, 9 Mar 2023 10:36:36 GMT, Afshin Zafari <duke at openjdk.org> wrote:

>> The inline and not-inline versions of the method is stress tested to compare the performance difference. 
>> The `oop java_class` input parameter is changed to `InstanceKlass *` to gain more performance.
>> The statistics are drawn in the following charts. The vertical axis is in milliseconds.
>> 
>> ![chart (2)](https://user-images.githubusercontent.com/4697012/221848555-2884313e-9d26-41c9-a265-3f1ce295b17b.png)
>> 
>> ![chart (3)](https://user-images.githubusercontent.com/4697012/221863810-94118677-b4af-468f-90c6-5ea365ae3588.png)
>
> Afshin Zafari has updated the pull request incrementally with one additional commit since the last revision:
> 
>   8292059: Do not inline InstanceKlass::allocate_instance()

That's really surprising. I also don't see how any of the proposed changes could affect the GC so much. This makes me suspicious of the performance claims.

Could you redo the benchmarking and give us more information about:
1) What benchmarks were run
2) What was the benchmarks scores and GC metrics
3) What was the run-to-run variance in the scores and metrics

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PR: https://git.openjdk.org/jdk/pull/12782