RFR: 8318650: Optimized subword gather for x86 targets. [v7]

[Emanuel Peter]

On Sun, 17 Dec 2023 17:51:37 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Fix incorrect comment
>
> Refined implementation using integral gather operation for AVX512 targets. As per Intel Optimization manual section 4.8.1.6 gather are micro coded atom with 50+ cycles latency, existing hybrid algorithm is performant for Intel Atom family CPUs and with runtime flag UseAVX=2.

@jatin-bhateja I'm not sure I can review the Vector API (java) code changes. It would be better if someone more familiar had a look as well.

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PR Comment: https://git.openjdk.org/jdk/pull/16354#issuecomment-1953741437