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

[Emanuel Peter]

On Fri, 5 Jan 2024 09:37:55 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> This computes the byte offset from start of the table, both integer and long permute table have same row sizes, 8 int elements vs 4 long elements.
>
> Ah, I understand now. Maybe leave a comment for that?

I would say something like this:
Given a `mask`, we compute the index into the permutation table, and load the corresponding `permutation` (4 long elements).

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/17261#discussion_r1442688495