Jump and Link, Jump Register
These instructions allow for the assembly programmer, or compiler, to use function calls. Since an instruction can only write to the register file during the writeback stage (stage 5), the jump and link instruction must insert the value of PC+4 onto the pipeline and it must then propagate down to stage 5 where it will finally be written. This will require an additional multiplexor. Remember, that the link address needs to be covered by data forwarding the same as any other instruction writing back to the register file
These instructions allow for the assembly programmer, or compiler, to use function calls. Since an instruction can only write to the register file during the writeback stage (stage 5), the jump and link instruction must insert the value of PC+4 onto the pipeline and it must then propagate down to stage 5 where it will finally be written. This will require an additional multiplexor. Remember, that the link address needs to be covered by data forwarding the same as any other instruction writing back to the register file