[llvm-dev] [RFC] Vector Predication

Bruce Hoult via llvm-dev llvm-dev at lists.llvm.org
Thu Jan 31 17:12:44 PST 2019


On Thu, Jan 31, 2019 at 4:31 PM Saito, Hideki via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

>
>
> >when we have a mask loaded from an external source (memory, function call
> boundary, etc...) and a short sequence of vector ops
>
>
>
> Mask value from function call parameter is common. OpenMP declare simd
> function does exactly that for the masked cases.
>

Such a mask is at the application level, not at the vector strip-mining
loop level.

As well as possibly being many times longer than the masks the hardware
works with, it's likely to not even in the the format the hardware uses:
different library APIs might pack a mask into bits, or one mask element per
byte, short, or int.
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