[llvm] [RISCV] Allow spilling to unused Zcmp Stack (PR #125959)

[Craig Topper via llvm-commits]

topperc wrote:

@lenary I think we're seeing issues when this patch is combined with vector. Our pulldown is pretty far behind so we just started noticing.

I don't a reduce case yet.

https://github.com/llvm/llvm-project/pull/125959