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

[Andrew Haley]

On Thu, 12 Aug 2021 09:41:07 GMT, Wu Yan <wuyan at openjdk.org> wrote:

>> 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.

Sorry, my mistake. I got confused.

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