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

[Valery Pykhtin via llvm-commits]

vpykhtin 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

I definitely can do this, and also I can add manually created checks in my scenario (like grepping for a specific instruction presence), we already have similar test in our code base. 

Ok, let it sit here for a while. Probably the main question for me here if such functionality is desired at all.

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