[vectorIntrinsics] RFR: 8263417: Add Extract integer nodes implementation for Arm SVE

[Ningsheng Jian]

On Fri, 12 Mar 2021 02:23:18 GMT, Wang Huang <whuang at openjdk.org> wrote:

> * Add Extract integer nodes implementation for Arm SVE, like ExtractB/ExtractS/ExtractI/ExtractL
> * add `sve_lasta(Register, SIMD_RegVariant, PRegister,  FloatRegister)` & `sve_lastb`

src/hotspot/cpu/aarch64/aarch64_sve.ad line 3004:

> 3002:   ins_encode %{
> 3003:     __ movzw(as_Register($tmp$$reg), (int)($idx$$constant));
> 3004:     __ sve_whilele(as_PRegister($pTmp$$reg), __ B, zr, as_Register($tmp$$reg));

I think we can use rscratch1 here to save one register. See https://github.com/openjdk/panama-vector/pull/49

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PR: https://git.openjdk.java.net/panama-vector/pull/48