[llvm] [StackSlotColoring] Ignore non-spill objects in RemoveDeadStores. (PR #80242)

[Philip Reames via llvm-commits]

preames wrote:

I think the X0 thing here is almost a red herring.  This transform would remove a volatile load/store pair in user written code which referenced a stack object.  That seems suspect.  It just doesn't run unless we happen to merge a stack slot so it's doesn't happen much in practice.  This transform running on anything which is not a stack slot is - I think - a bug. 

Worth noting is that no other target has the frame index restriction inside the isLoadFromStackSlot routine either.  

https://github.com/llvm/llvm-project/pull/80242