[vectorIntrinsics] RFR: 8265916: Add StoreVectorScatter nodes implementation for Arm SVE [v3]

[Xiaohong Gong]

On Thu, 29 Apr 2021 07:00:12 GMT, Wang Huang <whuang at openjdk.org> wrote:

>> * add `sve_st1w_scatter` and `sve_st1w_scatter`
>> * implement `scatterI` and `scatterL`
>> * `load gather partial` and `store scatter partial` are not contained in this patch, and they will be in next patches
>
> Wang Huang has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - add m4 file
>  - add case for partial

src/hotspot/cpu/aarch64/aarch64_sve.ad line 232:

> 230:       // Currently the implementation for partial vectors are not implemented yet.
> 231:       // Will add them in a separate patch.
> 232:         return vlen * type2aelembytes(bt) == MaxVectorSize;

Identity? Please align the comments with return statement?

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PR: https://git.openjdk.java.net/panama-vector/pull/73