Question $3(30$ points$).$ A MIPS assembly code is shown below. The assembly code is executed

using a $5-$stage MIPS processor and we can actually decide the branch a little earlier, in ID instead

of EX$.$ Answer the following questions:

Loop: sub $$19,$$$19,$$$20$

addi $$9,$$$20,5$

sw $$9,0($$$21)$

addi $$10,$$$19,2$

sll $$10,$$$10,$$$3$

add $$10,$$$10,$$$21$

addi $$11,$$$20,1$

sll $$11,$$$11,3$

add $$11,$$$11,$$$21$

Iw $$11,0($$$11)$

sub $$9,$$$9,$$$11$

sw $$9,0($$$10)$

beq $$9,$$$0,$ Loop

addi $$9,$$$12,2$

a$).$ How many clock cycles are needed to execute the code above? Assume there is no forwarding, no

branch prediction.

b$).$ How many clock cycles are needed to execute the code above? Assume there is forwarding, no

branch prediction.

c$).$ Reorder the above code to reduce the stalls $($get the smallest number of stalls$)$ without changing the

functionality. Assume there is forwarding and no branch prediction. How many clock cycles are needed

to execute the code above?