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

[via llvm-commits]

goldsteinn wrote:

> 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.)

Bah sorry for the confusion. Realized that case is already handled after writing the proofs.

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