[llvm] [ConstraintElim] Use ConstantRange information for ConstraintElimination (PR #180862)

[Manasij Mukherjee via llvm-commits]

manasij7479 wrote:

> This looks somewhat similar to @artagnon 's #176607. Would the current PR also allow remove `bool IsKnownNonNegative;`?
  
KnownBits is going to be slightly better for analyzing certain expressions, and ConstantRange another (overlapping) subset. Ideally we need both, but this has to be experimentally determined. 

https://github.com/llvm/llvm-project/pull/180862