RFR: 8264104: Eliminate unnecessary vector mask conversion during VectorUnbox for floating point VectorMask [v4]

[Vladimir Ivanov]

On Wed, 14 Apr 2021 01:53:15 GMT, Xiaohong Gong <xgong at openjdk.org> wrote:

>> I agree.
>
> I'v added the type assertion in the constructor of the `"VectorMaskCastNode"`. See :
> 
> assert(in_vt->length() == vt->length(), "vector length must match");
> assert(type2aelembytes(in_vt->element_basic_type()) == type2aelembytes(vt->element_basic_type()), "element size must match");
> 
> That's why I didn't add the check in predicate. So do you think it's enough?

IMO AD instructions should also be accompanied either by predicates or asserts which stress the conditions for the no-op implementation.

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PR: https://git.openjdk.java.net/jdk/pull/3238