RFR: 8291600: [vectorapi] vector cast op check is not always needed for vector mask cast [v7]

[Jatin Bhateja]

On Thu, 15 Sep 2022 07:57:37 GMT, Xiaohong Gong <xgong at openjdk.org> wrote:

>> src/hotspot/share/opto/vectorIntrinsics.cpp line 2486:
>> 
>>> 2484:       ((src_type->isa_vectmask() == NULL && dst_type->isa_vectmask()) ||
>>> 2485:        (dst_type->isa_vectmask() == NULL && src_type->isa_vectmask()) ||
>>> 2486:        num_elem_from != num_elem_to)) {
>> 
>> This check is already done on [java side](https://github.com/openjdk/jdk/blob/master/src/jdk.incubator.vector/share/classes/jdk/incubator/vector/Double512Vector.java#L643).
>
> Yes, it is. Just want to double check in the compiler side, or it maybe confusing if someone is not familiar with the vector api java codes.

I see, may be we can just add a comment/assert instead.

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PR: https://git.openjdk.org/jdk/pull/9737