rd and rs don't have to be the same. In some cases where rs needs to be
saved for later usage, this will save us some mv instructions.
Signed-off-by: Qingfang Deng <qingfang.deng@siflower.com.cn>
Reviewed-by: Xiao Wang <xiao.w.wang@intel.com>
Link: https://lore.kernel.org/r/20240527092405.134967-1-dqfext@gmail.comSigned-off-by: Palmer Dabbelt <palmer@rivosinc.com>