[llvm] [InstCombine] Simplify further when shift is half bitwidth (PR #93677)

[Nikita Popov via llvm-commits]

nikic wrote:

If you want to create a draft pull request, please **create it as a draft**. Do not first open it as a normal pull request and then convert it into a draft. Otherwise you will still notify and subscribe everyone.

https://github.com/llvm/llvm-project/pull/93677