RFR: 8259948: Aarch64: Add cast nodes for Aarch64 Neon backend [v2]

[Wu Yan]

On Thu, 12 Aug 2021 01:31:54 GMT, Xiaohong Gong <xgong at openjdk.org> wrote:

>> Wang Huang has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   fix code style
>
> src/hotspot/cpu/aarch64/aarch64_neon.ad line 229:
> 
>> 227:   format %{ " # reinterpret $dst,$src\t# X to S" %}
>> 228:   ins_encode %{
>> 229:     // Resize the vector from 128-bits or 64-bits to 32-bits. The higher bits
> 
> Resize the vector from 128 bits to 32 bits?

This is generated by aarch64_neon_ad.m4, So it is not clearly specified at first. I'll change it to "16 bytes to 4 bytes" and "8 bytes to 4 bytes" in the next commit.

> src/hotspot/cpu/aarch64/aarch64_neon.ad line 244:
> 
>> 242:   format %{ " # reinterpret $dst,$src\t# D to S" %}
>> 243:   ins_encode %{
>> 244:     // Resize the vector from 128-bits or 64-bits to 32-bits. The higher bits
> 
> Resize the vector from 64 bits to 32 bits?

ditto

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PR: https://git.openjdk.java.net/jdk/pull/4839