[vectorIntrinsics] RFR: 8259604: Change the implementation of loadV_partial and storeV_partial in Aarch64-SVE backend

[Ningsheng Jian]

On Mon, 18 Jan 2021 06:55:48 GMT, Wang Huang <whuang at openjdk.org> wrote:

> Now, the implementation of `loadV_partial` is :
> mov $tmp1, 0
> mov $tmp2, vector_length
> sve_whilelo $pTmp, $tmp1, $tmp2
> sve_ldr $dst, $pTmp, $mem
> However, we can encode register `zr` in instruction `sve_whilelo` instead of getting from the first mov instruction.
> 
> The new implementation is :
> mov $tmp, vector_length
> sve_whilelo $pTmp, zr, $tmp
> sve_ldr $dst, $pTmp, $mem
> From this changing, we reduce a mov instruction and a temporary variable($tmp2 ).

Marked as reviewed by njian (Committer).

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PR: https://git.openjdk.java.net/panama-vector/pull/32