[llvm] [SCEV] Add initial matchers for SCEV expressions. (NFC) (PR #119390)

[Nikita Popov via llvm-commits]

https://github.com/nikic commented:

This looks reasonable, but I can't claim to understand the template magic going on here. I do wonder if it wouldn't be better to just have separate unary and binary implementations and not try to be overly generic.

https://github.com/llvm/llvm-project/pull/119390