[llvm] [LVI] Generalize mask not equal conditions handling (PR #92946)

[Antonio Frighetto via llvm-commits]

antoniofrighetto wrote:

@nikic Can I assume that `R = GetRangeFromKnownBits()` is always a satisfying range for pred EQ?  For the motivating example (range: `[-16, -8)`), shouldn't I expect that `makeAllowedICmpRegion(!pred, R.inverse()) == makeSatisfyingICmpRegion(!pred, R.inverse())`? Sorry if I'm still off track :(

https://github.com/llvm/llvm-project/pull/92946