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

[Jatin Bhateja]

On Mon, 13 Jun 2022 18:09:48 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> @jatin-bhateja, could you please help to check the influence about removing this? Kindly know your feedback about this. Thanks so much!
>
> 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!Odyhi2OwwxGNICZz-RHExh3govoHMIvxlXEyVrC0VEbLRquy5EgQxqR2Mf_mbcfz9sZ72KEvjzA6Lz8hYW1uxdbL-DtMmODR$ )
> 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.

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