[llvm] [InstCombine] ptrmask of gep for dynamic pointer aligment (PR #80002)

[Nikita Popov via llvm-commits]

https://github.com/nikic commented:

I think this belongs inside demanded bits simplification. We currently don't handle GEPs there because historically that would have been useless, but now that ptrmask gives a pointer demanded bits root, it makes sense to simplify GEPs as well.

https://github.com/llvm/llvm-project/pull/80002