[llvm] [ValueTracking] Propogate sign information out of loop (PR #175590)

[Vedant Paranjape via llvm-commits]

VedantParanjape wrote:

@kshitijvp you might want to use this testcase instead: https://godbolt.org/z/shWv73qbj

The current one will not work because you cannot prove isGuaranteedNotToBeUndef on X (based on the discussion here: https://github.com/llvm/llvm-project/issues/175166)

https://github.com/llvm/llvm-project/pull/175590