[clang] [compiler-rt] [llvm] [PGO][AMDGPU] Add offload profiling with uniformity-aware optimization (PR #177665)

[Matt Arsenault via llvm-commits]

https://github.com/arsenm commented:

Missing codegen tests.

This PR is also large enough that GitHub is unusable. This should still be broken up, the codegen pieces should be done separately from anything else 

https://github.com/llvm/llvm-project/pull/177665