[clang] [llvm] [PGOVerify] Add end-to-end IPGOVerifier infrastructure, validations, and function filtering (PR #196295)

[Alok Kumar Sharma via cfe-commits]

alokkrsharma wrote:

> I can't speak for the PGOVerify code itself, because PGO isn't my strong suit, but the code in StandardInstrumentations.h looks good to me. However, with so much of the patch left unreviewed by me, I don't feel like I can approve it either. Please note the merge conflicts that need to be fixed up

Thanks for taking a look, I really appreciate the review.

It's helpful to know that the pass-instrumentation integration looks reasonable, even if the PGO-specific parts are outside your area of expertise.

Just to clarify, I'm not proposing this PR for immediate landing. The branch is primarily intended as a proof-of-concept to support the RFC discussion, validate the design on real pipelines, and evaluate the signal/noise characteristics of the verifier.

I'll fix up the merge conflicts as well.

Once the RFC direction becomes clearer, I expect the work would be split into smaller reviewable pieces rather than upstreamed as a single large change.

https://github.com/llvm/llvm-project/pull/196295