[vectorIntrinsics+compress] RFR: 8274889: Intrinsify Vector.expand/compress APIs for X86 [v4]

[Jatin Bhateja]

On Mon, 11 Oct 2021 08:33:07 GMT, Joshua Zhu <jzhu at openjdk.org> wrote:

> Jatin, your change will bring around 15% performance degradation for SelectiveStore benchmark using compress VectorAPI.
Hi @JoshuaZhuwj ,

A special check for m.allTrue() has been added which returns original vector argument without any compress/expansion, it favors targets which do not support compress/expand operation.

But I think its better to leave this to user to make this check directly from source instead of making it a part of API implementation since it will effect the performance of fast path.

Will update the patch.

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PR: https://git.openjdk.java.net/panama-vector/pull/146