RFR: 8277997: Intrinsic creation for VectorMask.fromLong API [v2]

[Jatin Bhateja]

On Wed, 1 Dec 2021 23:06:01 GMT, Paul Sandoz <psandoz at openjdk.org> wrote:

>> Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   8277997: Review comments resolved.
>
> Arguably broadcasting is not the correct term to associate with conversion of a long value to a mask, but it is very convenient to reuse `VectorSupport.broadcastCoerced` and i don't have a better solution in that regard. The addition of a new intrinsic seems overly heavy.
> 
> We could rename to `fromBitsCoerced` then the `bitwise` parameter can be renamed `mode`.
> 
> Can we define named constants on the Java and HotSpot side: `0`, for broadcasting; and `1` for mask conversion e.g. `BITS_COERCED_BROADCAST = 0`, `BITS_COERCED_MASK_TO_LONG=1`.
> 
> This potentially allows for future modes such as broadcast only to the first lane.

@PaulSandoz , your comments have been addressed.

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PR: https://git.openjdk.java.net/jdk/pull/6646