[vectorIntrinsics] RFR: 8281562:[vectorapi] Add support for popcount operation

[Smita Kamath]

On Thu, 10 Feb 2022 01:19:31 GMT, Quan Anh Mai <duke at openjdk.java.net> wrote:

>> It is also wrong, you can't use the scalar `PopCountI` on byte and short
>
> Also, are you sure this will work? Since PopCountVL takes a long vector and returns an int vector, I think you need to adjust the C2 compiler before trying to intrinsify this.

@merykitty Thanks for your comment. There will be a follow up patch for C2 compiler related changes.

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PR: https://git.openjdk.java.net/panama-vector/pull/173