Register spills (save/restore) in RISC-V embedded work differently because there are less registers and different stack alignment. [GCC equivalent ](https://github.com/gcc-mirror/gcc/blob/master/libgcc/config/riscv/save-restore.S#L298C16-L336) Follow up from #76777. --------- Signed-off-by: xermicus <cyrill@parity.io>