RFR: 8277426: Optimize mask reduction operations on x86 [v3]

[Sandhya Viswanathan]

On Wed, 24 Nov 2021 14:05:34 GMT, Mai Đặng Quân Anh <duke at openjdk.java.net> wrote:

>> Hi,
>> 
>> This patch improves the performance of mask reduction operations on AVX by matching the pattern `VectorMaskReduction (VectorStoreMask mask)` to eliminate the extra `VectorStoreMaskNode`. I have also done some refactoring to unify the logic of `toLong` with the other reduction operations.
>> 
>> The patch has been discussed partially in [panama-vector repository](https://github.com/openjdk/panama-vector/pull/158).
>> 
>> Thank you very much.
>
> Mai Đặng Quân Anh has updated the pull request incrementally with one additional commit since the last revision:
> 
>   add check bmi

Looks good to me.

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Marked as reviewed by sviswanathan (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/6447