[llvm] [utils][UpdateLLCTestChecks] Add MIR support to update_llc_test_checks.py. (PR #164965)

[Mircea Trofin via llvm-commits]

mtrofin wrote:

Maybe naive question, but for your scenario, can you run just the passes you need, on MIR? I.e you could start with the pattern that you expect to be undone, and not rely on the earlier pass producing it. You'd also not need this change then.

... which would avoid teasing the sentiments in this thread:

https://discourse.llvm.org/t/rfc-llvm-ai-tool-policy-start-small-no-slop/88476

(I'm assuming @arichardson's lgtm means at least one person is ok with maintaining Claude's output here)

https://github.com/llvm/llvm-project/pull/164965