Make default codegen behavior skip Lower function (#75267)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/75267
- clean up arguments relating to ts backend generation
- make entire lowering function rather than just body be a part of
backend-IR class
Test Plan: Imported from OSS
Reviewed By: bdhirsh
Differential Revision: D35411212
Pulled By: wconstab
fbshipit-source-id: 44419e42f706afeb967f704649c2b44e9f66d969
(cherry picked from commit 80a6fa715db97deb056db31e28689dd86a50a4bb)
