Revert "apply constexpr and if constexpr when possible (#102471)"
This reverts commit 461c03a93c0ac85837c1ef11afc0ec1dc8900d0c.
Reverted https://github.com/pytorch/pytorch/pull/102471 on behalf of https://github.com/huydhn due to Sorry for reverting your PR. I think it breaks Windows CUDA build with a landrace https://hud.pytorch.org/pytorch/pytorch/commit/461c03a93c0ac85837c1ef11afc0ec1dc8900d0c ([comment](https://github.com/pytorch/pytorch/pull/102471#issuecomment-1567653793))
