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

[Eli Friedman via llvm-commits]

efriedma-quic wrote:

I assume you're not actually suggesting it's correct for isLoadFromStackSlot to return x0?  I can't see any reasonable way to argue it's a useful result.  The fix here only makes it less likely for that to cause issues (since there isn't really any reason for the compiler to generate no-op load from a spill slot).

We could say more generally, that isLoadFromStackSlot/isStoreToStackSlot implementations are generally buggy, so we want to be conservative about how we actually use the results.  But that doesn't seem like it should be the first fix here.

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