[llvm] [ValueTracking] Handle range attributes (PR #85143)

[Nikita Popov via llvm-commits]

nikic wrote:

> the lit tests feels a bit fragile as multiple of the functions is called in many of the cases eg for the icmp test if the isKnownNonZero and computeConstantRange is removed the test will still pass du e to the ComputeKnownBits

If you test `x_with_range | y_unknown == 0`, then that's a way to check only isKnownNonZero() as opposed to the others.

https://github.com/llvm/llvm-project/pull/85143