RFR: 8310691: [REDO] [vectorapi] Refactor VectorShuffle implementation [v9]

[Quan Anh Mai]

On Tue, 10 Dec 2024 08:34:30 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> Quan Anh Mai has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Change wording on VectorLoadShuffleNode
>>   
>>   Co-authored-by: Jatin Bhateja <jatin.bhateja at intel.com>
>
> I am observing some performance drops in slice / unslice benchmarks,  I have just completed this run and not got a chance to root cause.
> ![image](https://github.com/user-attachments/assets/ecb686b6-c3b0-47e9-9325-40341c19ff9d)
> 
> Can you kindly verify once at your end.

@jatin-bhateja Thanks for the performance notice, it was due to the failure to inline `VectorSupport::convert` which I believe is similar to [JDK-8302459](https://bugs.openjdk.org/browse/JDK-8302459) because the `convert` sequence is pretty complex. For now, I refactor the `slice/unslice` routines to take advantage of `toBitsVector`, could you verify if the change fixes the regression on your side?

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PR Comment: https://git.openjdk.org/jdk/pull/21042#issuecomment-2532158271