Jump: subroutine calls

main:

subroutine:

jal  offset

addi . . .

sll $0, $0, 0

ori . . .

next

blah

. . .

jr $r31

What happens if a jal call is made while in a subroutine?

return address overwritten with a new return address

must place the return address onto the stack (memory)

It turns out that the return address is PC + 8, not PC + 4

jump instructions have to be followed by a branch delay slot instruction

purpose of avoiding stalling in pipelines