[llvm] [SCEV] Add SCEVs for scopes as users of origin SCEV. (PR #119897)

[Nikita Popov via llvm-commits]

nikic wrote:

Looking at https://llvm.godbolt.org/z/xdWvqbhaj, `%add.lcssa` has SCEV `({0,+,1}<nuw><nsw><%loop.1> + %load)` with exit value `(100 + %load)`. Invalidating `%add.lcssa` should find the invalidation roots `{0,+,1}<nuw><nsw><%loop.1>` and `%load`. Invalidating `%load` should invalidate both the exit value and the BECount using it.

https://github.com/llvm/llvm-project/pull/119897