RFR: 8322768: Optimize non-subword vector compress and expand APIs for AVX2 target. [v5]

[Emanuel Peter]

On Thu, 18 Jan 2024 17:06:55 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> @jatin-bhateja so why do you shift by 5? I thought 4 longs are 32 bit?
>
> For long/double each permute row is 32 byte in size, so a shift by 5 to compute row address.

Ah right. Maybe we could say `32byte = 4 long = 4 * 64bit`.
Because "64bit row" sounds like the whole row is only 64 bit long. It is actually the cells that are 64bits, not the rows!

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PR Review Comment: https://git.openjdk.org/jdk/pull/17261#discussion_r1458509886