[llvm] [RISCV] fix SP recovery in varargs functions (PR #114316)

[via llvm-commits]

eaeltsin wrote:

Thanks for the fix!

PS it is extremely unfortunate that this fix doesn't cherry-pick cleanly before https://github.com/llvm/llvm-project/pull/110810 - so we'll have to cherry-pick also the new functionality to get this fix :(


https://github.com/llvm/llvm-project/pull/114316