RFR: 8262355: Support for AVX-512 opmask register allocation. [v14]

[Jatin Bhateja]

On Tue, 23 Mar 2021 22:11:25 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

>> Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   8262355: Extending Type::isa_vect and Type::is_vect routines to TypeVectMask since its a valid vector type.
>
> As a summary: in general, the patch looks good to me.
> 
> I'm still not convinced that mask representation choice is the optimal one (`Matcher::predicate_reg_type()`/`TypeVect::makemask()`: specializing `TypeVect*` vs `ideal_reg`), but I think it's better to revisit it later when masks become extensively used across the platforms. (The same applies to `TypeVect` vs `TypeVectMask`.)
> 
> But I want to see `k0`/`k1` vs `opmask_reg` cleaned before the integration.

Hi @iwanowww , I have resolved your outstanding comments.

-------------

PR: https://git.openjdk.java.net/jdk/pull/2768