RFR: 8259948: Aarch64: Add cast nodes for Aarch64 Neon backend [v4]

[Ningsheng Jian]

On Thu, 19 Aug 2021 08:57:47 GMT, Wang Huang <whuang at openjdk.org> wrote:

>> * In this issue, we plan to complete all missing implementation for aarch64 neon backend. For example, cast from Byte to Long, cast from Long to Byte, and so on.
>> * It may be a solver of JDK-8269866, or part of it.
>
> Wang Huang has updated the pull request incrementally with one additional commit since the last revision:
> 
>   fix codes

src/hotspot/cpu/aarch64/aarch64_neon.ad line 274:

> 272: %}
> 273: 
> 274: instruct vcvt4Bto4I(vecX dst, vecD src)

4BtoX should be supported as the min_vector_size() for byte type is 4.

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