[llvm-branch-commits] [llvm] [AMDGPU] start using new pass manager for backend codegen (PR #210251)

[Christudasan Devadasan via llvm-branch-commits]

https://github.com/cdevadas approved this pull request.

LGTM.
The test churn should have been submitted separately, but that's okay.

https://github.com/llvm/llvm-project/pull/210251