We actually do use ternlog in several places in Highway :) Whenever we want to use a new immediate arg, we add new ops such as Not, Xor3, Or3, OrAnd, IfVecThenElse that also do something reasonable on other platforms.

BTW this reminds me of a colleague grumbling that what should have been a 20-minute patch to ffmpeg took a day, because it was written in assembly.

It is also quite possible to have large slowdowns due to assembly - all it takes is to forget a v prefix (VEX encoding), whereas intrinsics take care of that.