RFR: 8266317: Vector API enhancements

[Paul Sandoz]

On Thu, 29 Apr 2021 21:13:38 GMT, Paul Sandoz <psandoz at openjdk.org> wrote:

> This PR contains API and implementation changes for [JEP-414 Vector API (Second Incubator)](https://openjdk.java.net/jeps/414), in preparation for when targeted.
> 
> Enhancements are made to the API for the support of operations on characters, such as for UTF-8 character decoding. Specifically, methods for loading/storing a `short` vector from/to a `char[]` array, and new vector comparison operators for unsigned comparisons with integral vectors. The x64 implementation is enhanced to supported unsigned comparisons.
> 
> Enhancements are made to the API for loading/storing a `byte` vector from/to a `boolean[]` array.
> 
> The testing of loads/stores can be expanded for scatter/gather, but before doing that i think some refactoring of the tests is required to reposition tests in the right classes. I would like to do that work after integration of the PR.

All tests pass for tier1,tier2,tier3 for build profiles linux-x64, linux-aarch64, macosx-x64, and windows-x64.

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PR: https://git.openjdk.java.net/jdk/pull/3803