3a3377579f
The current implementation of `convertPowfOp` requires a calculation of `a * a` but, max\<fp16\> ~= 65,504, and if `a` is about 16, it will overflow so get INF in fp8 or fp16 easily. Remove support when `a < 0`. Overhead of handling negative value of `a` is large and easy to overflow; - related issue in iree: https://github.com/iree-org/iree/issues/15936