[llvm] Add flags to dump IR to a file before and after LLVM passes (PR #65179)

[Nuri Amari via llvm-commits]

NuriAmari wrote:

> I like this feature, though I feel like in many cases `-print-changed` is good enough. 

I've never experienced it myself, but my teammate has said another reason to want this is that when using thinLTO, multiple modules are processed concurrently on different threads, and the printed output can end up interleaved and be hard to read.

> Also slightly tangent: I think LLVM's interim github PR policy is to discourage force push on PR branch in favor of amending commits: https://discourse.llvm.org/t/update-on-github-pull-requests/71540/53

Ah ok sorry I didn't know, will make new commits moving forward.



https://github.com/llvm/llvm-project/pull/65179