New CUDA Fuser: Unrolling support, interface refactor (#36435)
Summary:
Unrolling support has been added in a way that we get good performing code on GPUs. Not sure how long this link will last but an example of a generated unrolled kernel is:
https://godbolt.org/z/i0uAv3
What can be seen from there is multiple calls of "ld.global.f32" without "ld.store.f32" in between them (and vice versa). This means that we are launching multiple loads that can be run in parallel, as well as multiple stores that can be run in parallel. This can be a crucial optimization for memory bound kernels. This was generally a point of concern in TVM as an attempt of a similar kernel from TVM produces: https://godbolt.org/z/Vu97vG which surrounds load - store pairs in conditional branches preventing the benefits of unrolling.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/36435
Reviewed By: ZolotukhinM
Differential Revision: D21024011
Pulled By: soumith
fbshipit-source-id: e852e282fa7a304aba962e1926f756098c011fe0
