[vectorIntrinsics] RFR: 8263424: Extend vector size support for SVE

[Xiaohong Gong]

On Fri, 12 Mar 2021 06:15:33 GMT, Ningsheng Jian <njian at openjdk.org> wrote:

> This patch adds support of vector operations with size less than MaxVectorSize for SVE. Basically, for general vector operations, we simply keep original operations, i.e. doing a full vector length operations, but for load/store and reduction operations, we use
> predicate operations to make sure only vector elements in the size limit are loaded/stored/calculated.
> 
> This patch also fixes an SVE load/store addressing mode usage issue. For SVE load/store scalar plus immediate, the immediate displacements are calculated by both vector element size and memory element size. As the existing vmemA_immIOffset4 and vmemA_immLOffset4 does not take into account of the vector and memory element size difference, we should not use them for extend/narrow forms.
> 
> Tested with tier1 and jdk:tier3. jdk/incubator/vector cases have also been verified with different MaxVectorSize options.

Marked as reviewed by xgong (no project role).

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PR: https://git.openjdk.java.net/panama-vector/pull/49