[jdk18] RFR: 8278508: Enable X86 maskAll instruction pattern for 32 bit JVM. [v2]

[Jatin Bhateja]

On Thu, 16 Dec 2021 17:46:35 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> - Vector.maskAll was accelerated for AVX-512 target, but  x86 existing backend implementation does not enable maskAll instruction patterns for 32 bit JVM, due to which operations fall backs over replicateB operation which broadcasts the mask value in a vector.
>> - In some cases after unboxing-boxing optimization this vector eventually reaches to XorVMask which has different operands one held in opmask register and other in vector.
>> 
>> Kindly review and share your feedback.
>> 
>> Best Regards,
>> Jatin
>
> Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:
> 
>   8278508: Review comments resolution.

@svisva7 can you kindly be second reviewer.

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PR: https://git.openjdk.java.net/jdk18/pull/24