RFR: 8259948: Aarch64: Add cast nodes for Aarch64 Neon backend

[Wu Yan]

On Wed, 21 Jul 2021 03:35:01 GMT, Ningsheng Jian <njian 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.
>
> Thanks for the work! Some general comments:
> 
>> It may be a solver of JDK-8269866, or part of it.
> 
> I would suggest not to have a partial fix of JDK-8269866. I think you can still keep 8259948 as duplicate while targeting this to JDK-8269866 and have a fully proper fix. @theRealELiu may have some thoughts on how to have a clean fix: e.g. there may be some dependency on mid-end part, like JDK-8265244?
> 
> @theRealELiu has marked those missing rules opcode (with specific types/sizes) as unsupported in JDK-8268966, but I don't see you have unmarked them in your patch. So your newly added rules are not able to be tested. And there are some test cases included in JDK-8268966, could you please merge your test case into existing tests, if existing tests cannot cover some cases.
> 
> P.S. could you please fix the jcheck error?

Thanks @nsjian @theRealELiu for reviewing this.

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