[llvm] [RISCV] Stash GPR to FPR if emergency spill slot is not reachable (PR #180685)

[Min-Yih Hsu via llvm-commits]

mshockwave wrote:

> May I ask what is the expected generated code be like using frame pointer?

Because the crux of this problem is that offset is too far away from sp -- which points at the low address of the current frame -- we can instead access the far stack slots from _the other_ direction using fp, which points at the high address of the current frame.

https://github.com/llvm/llvm-project/pull/180685