[llvm] [llvm-profgen] Add pgo accuracy metrics (PR #93975)

[Aiden Grossman via llvm-commits]

https://github.com/boomanaiden154 commented:

I'll go through this more throughly later.

1. Can we not check in a binary? We should be able to generate one with the appropriate data using `yaml2obj` I'm thinking?
2. I'm also not really sure what this feature lets you test given that you're using a sampling based profile as the reference along with all the classical profile infrastructure within LLVM, and thus won't catch any profile propagation issues in the compiler. Can you give more details on how you plan to integrate this into a workflow?

https://github.com/llvm/llvm-project/pull/93975