This could be due to inlining (at least when AVX is detected).
Most of the action w.r.t. using AVX is going on in ATen’s native/cpu 46 directory. This also uses the TensorIterator mechanism a lot. This is defined in the ATen native directory 17 and provides a common infrastructure for plain+SIMD CPU and GPU ops and does most pointwise things and also reductions.
I would not look at the (Torch legacy) aten/src/TH* too much, as we’re working on moving things over to the fancy new way.
Best regards
Thomas