[llvm] [AMDGPU] Restore SP from saved-FP or saved-BP (PR #124007)

[Sergei Barannikov via llvm-commits]

s-barannikov wrote:

> (Note: The presence of BP has been enforced in case of any
> dynamic stack realignment.)

Another optimization opportunity: BP is only really needed if you have *both* dynamic stack realignment and variable-sized objects. Otherwise there is at most one alignment gap and you can use FP/SP to access objects before/after the gap.



https://github.com/llvm/llvm-project/pull/124007