[clang] [llvm] [LLVM] Add IRNormalizer Pass (PR #68176)

[Justin Fargnoli via llvm-commits]

justinfargnoli wrote:

Hi @dtcxzyw, thanks for reaching out! 

This MR is blocked because I cannot reproduce the failures @nikic found [here](https://github.com/llvm/llvm-project/pull/68176#issuecomment-1836365664). (See [this comment](https://github.com/llvm/llvm-project/pull/68176#issuecomment-1818308163) to understand the problem I'm running into.)  

The other things that I've mentioned should be easy to fix. 

If you (or anyone else who's interested in helping) can reproduce/debug the failure @nikic found, that'd be a big help toward getting this PR over the line. 

https://github.com/llvm/llvm-project/pull/68176