The hot region of the stack is, for practical purposes, always resident in D$, so there's no prefetching to be done. I think that you're really talking about o

The hot region of the stack is, for practical purposes, always resident in D$, so there's no prefetching to be done. I think that you're really talking about out-of-order and speculative loads. You're absolutely correct that spill/fill can be catastrophic for performance, however.