[llvm] [InstCombine] Propagate NUW flags for `shl (lshr X, C1), C2 -> shl X, C2-C1` (PR #72525)

[Nikita Popov via llvm-commits]

https://github.com/nikic commented:

It looks like only two out of four cases are covered by tests?

https://github.com/llvm/llvm-project/pull/72525