RFR: 8322768: Optimize non-subword vector compress and expand APIs for AVX2 target. [v2]

[Jatin Bhateja]

On Fri, 5 Jan 2024 07:03:26 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> And what about some result verification? Or is there another test that does that?
>
> We do have extensive functional tests for compress/expand APIs in [test/jdk/jdk/incubator/vector](https://github.com/openjdk/jdk/tree/master/test/jdk/jdk/incubator/vector)

> Could there be equivalent `expand` tests?

Here are the performance number for existing [VectorAPI JMH micros.](https://github.com/openjdk/panama-vector/tree/vectorIntrinsics/test/micro/org/openjdk/bench/jdk/incubator/vector/operation)

![image](https://github.com/openjdk/jdk/assets/59989778/4b260814-3d3c-4e9b-b81a-61492ea48cce)
![image](https://github.com/openjdk/jdk/assets/59989778/50048281-ad50-44f6-a875-308e02537be2)

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PR Review Comment: https://git.openjdk.org/jdk/pull/17261#discussion_r1442556253