[llvm] [InstCombine] Fold `icmp samesign u{gt/ge/lt/le} (X +nsw C2), C` -> `icmp s{gt/ge/lt/le} X, (C - C2)` (PR #169960)

[Andreas Jonson via llvm-commits]

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andjo403 wrote:

this is the fold that can be adapted or at least the body of the if is similar to what you need to do

https://github.com/llvm/llvm-project/pull/169960