[llvm] AtomicExpand: Fix creating invalid ptrmask for fat pointers (PR #94955)

[James Y Knight via llvm-commits]

jyknight wrote:

I'm not familiar with the intended semantics of a fat pointer. Does llvm.ptrmask not actually work to align a fat-pointer? What does "ptrtoint" mean on one of these fat pointers?



https://github.com/llvm/llvm-project/pull/94955