[llvm] [PGO] Add option to always instrumenting loop entries (PR #116789)

[Ellis Hoag via llvm-commits]

https://github.com/ellishg commented:

I think we also need to add a new variant mask for instrumenting loop entries. Otherwise we won't be able to match the profiles they generate correctly

https://github.com/llvm/llvm-project/blob/dd78d7c7be5b8948cf5841e8033e59adebf230ad/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp#L439-L441

https://github.com/llvm/llvm-project/pull/116789