RFR: 8292898: [vectorapi] Unify vector mask cast operation [v4]

[Xiaohong Gong]

On Fri, 23 Sep 2022 11:38:45 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> I believe the intention is to simplify the mid-end as well as to achieve better code gen on x86
>
> Hi @merykitty , Can you please post the benchmark results with the new changes.

Right, the unification can simplify the the mid-end codes especially when we need to check whether the ops are supported for different vector types.

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PR: https://git.openjdk.org/jdk/pull/10192