[llvm] [indvars] Missing variables at Og: (PR #69920)

[Carlos Alberto Enciso via llvm-commits]

CarlosAlbertoEnciso wrote:

@nikic Thanks for your feedback.
I uploaded a new patch addressing:
- Moved the new logic to `rewriteLoopExitValues`.
- Removed from the test cases, the unrelated functions: `nop` and `main`.
- Use `isa<SCEVConstant>`.

https://github.com/llvm/llvm-project/pull/69920