[VectorAPI] Expose direct move mask operation?

[Zhu, Yifan]

Sorry if this was previously discussed. I am new to the list.

With current API, it seems that if one want to get the lanes with highest bit set, one can use Vector::compare(LT, 0). In the backend, this seems to be translated to something like vpcmpgtb followed by vpmovmskb. However, Gather the highest bit on x86 only need a movemask operation.


  *   I wonder if such operations can be optimized if the given constant is special (such as 0)
  *   Or if we can finally have a gatherBits()​ operation. I know that movemask operations are not available on platforms like aarch64, but libraries like SIMDE has given some examples on how to emulate these operations on other platforms.

[cid:825d375d-909d-4f47-b90f-c786e3c116ab]
Schrodinger ZHU Yifan, Ph.D. Student
Computer Science Department, University of Rochester

Personal Email: i at zhuyi.fan
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