RFR: 8286941: Add mask IR for partial vector operations for ARM SVE [v3]

[Xiaohong Gong]

On Thu, 16 Jun 2022 09:34:17 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> It was added specifically for #302
>> It used for ArrayCopyPartialInlineSize code [macroArrayCopy.cpp#L250](https://urldefense.com/v3/__https://github.com/openjdk/jdk/blob/master/src/hotspot/share/opto/macroArrayCopy.cpp*L250__;Iw!!ACWV5N9M2RV99hQ!PDE6W6C4GzlQyZkPThLWxRNsLj_oACvbHEvPJS6-aH_WB6cCRjTfkWC3bP5VuVlpu04GvTI-AUn8B-3YTI6O1vHeFpa5$ )
>> Yes, it is strange that it is forced to be in register always. The instruction in x86.ad should be enough to put it into register.
>
>> @jatin-bhateja, could you please help to check the influence about removing this? Kindly know your feedback about this. Thanks so much!
> 
> I think, this can be modified, GVN based sharing should be sufficient here.

Thanks a lot for looking at this part!

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PR: https://git.openjdk.org/jdk/pull/9037