[llvm] [SCEV] Add dedicated AffineAddRec matcher + loop matchers (NFC). (PR #141141)

[Nikita Popov via llvm-commits]

https://github.com/nikic approved this pull request.

LGTM, this does seem more in line with how PatternMatch usually works. It's nice to support both m_Loop and m_SpecificLoop.

https://github.com/llvm/llvm-project/pull/141141