[vectorIntrinsics+compress] RFR: 8274975: Add micro benchmark: ALIBABA selective store use case

[Joshua Zhu]

On Fri, 8 Oct 2021 12:22:33 GMT, Joshua Zhu <jzhu at openjdk.org> wrote:

> I separate my implementation of "compress" API into several patches for easy review.
> This micro benchmark is extracted from the real use case inside in-memory databases: selectiveStore.
> Test scenario: UseAVX=3; thread number = 8; conflict data percentage: 20% (that means 20% of mask bits are true)

Using vector-to-vector compress, the benchmark performance result:
![image](https://user-images.githubusercontent.com/70769035/136651101-1d6450a8-1095-41c9-aa91-c207ee63360f.png)

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PR: https://git.openjdk.java.net/panama-vector/pull/149