[llvm] [InstCombine] Propagate flags when folding consecutative shifts (PR #94872)

[Nikita Popov via llvm-commits]

https://github.com/nikic approved this pull request.

LGTM

(It looks like your alive2 link also has the proofs for flag-preservation for a related case that's not part of this PR.)

https://github.com/llvm/llvm-project/pull/94872