[llvm] [ConstraintElim] Bound non-increasing header IVs by start value. (PR #217921)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

>>    it will never exceed the start value and we can add PN s>=
>>    StartValue.
> PN s<= StartValue

argh update thanks

https://github.com/llvm/llvm-project/pull/217921