[vectorIntrinsics] RFR: 8258072: Add Reinterpret nodes implementation for Arm SVE [v3]

[Wang Huang]

On Wed, 6 Jan 2021 07:08:12 GMT, Xiaohong Gong <xgong at openjdk.org> wrote:

>> src/hotspot/cpu/aarch64/aarch64_sve.ad line 384:
>> 
>>> 382:                      zr, as_Register($tmp$$reg));
>>> 383:       __ sve_cpy(as_FloatRegister($dst$$reg), __ B,
>>> 384:                  as_PRegister($pTmp$$reg), as_FloatRegister($src$$reg));
>> 
>> It seems using `cpy` is not right here, which usually accept a `imm, scalar or SIMD&FP scalar register`. This instruction is expected to copy the scalar value to each active element. So use `"mov"` instead ? BTW, the normal `MOV <Zd>.<T>, <Pg>/M, <Zn>.<T>`  instruction uses the `merging` feature of predicate while not `zeroing`. To make sure the non active elements are zero, do you think it's better to use `MOVS <Pd>.B, <Pg>/Z, <Pn>.B` here?
>
> I'm sorry that I didn't notice this is an instruction for predicate `MOVS <Pd>.B, <Pg>/Z, <Pn>.B`. So please ignore this suggestion. Thanks！

OK. We change our algorithm and use other instructions instead of these.

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PR: https://git.openjdk.java.net/panama-vector/pull/30