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

[Ramkumar Ramachandra via llvm-commits]

https://github.com/artagnon commented:

Not terribly sure about this one, as m_Loop() and m_SpecificLoop() needs to be a specific positional argument in the m_scev_AffineAddRec() matcher: the matchers have no other utility. Besides, I'm not sure if there are widespread use-cases of m_SpecificLoop(). I'll leave @nikic to comment on the ergonomics of this one.

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