[vectorIntrinsics] RFR: 8266775: Add VectorLoadConst node implementation for Arm SVE [v2]

[Xiaohong Gong]

On Sat, 8 May 2021 09:14:13 GMT, Wang Huang <whuang at openjdk.org> wrote:

>> * add VectorLoadConst node implementation for Arm SVE by
>>    * add new data in `generate_iota_indices`
>>    * `sve_ld1b` these data
>>   
>> Thank you for your review. Any suggestion is welcome.
>
> Wang Huang has updated the pull request incrementally with one additional commit since the last revision:
> 
>   fix cost

src/hotspot/cpu/aarch64/aarch64_sve.ad line 4233:

> 4231:   ins_encode %{
> 4232:     __ lea(rscratch1, ExternalAddress(StubRoutines::aarch64::vector_iota_indices()));
> 4233:     __ sve_ld1b(as_FloatRegister($dst$$reg), __ B, ptrue, Address(rscratch1, 0));

Could it use `INDEX <Zd>.<T>, #<imm1>, #<imm2>`  (Create index starting from and incremented by immediate) here?

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PR: https://git.openjdk.java.net/panama-vector/pull/79