$4.$ Assume that there are no pipeline stalls and that the breakdown of executed instructions is as

follows for the processor shown in the Figure below:

add addi not beq lw sw

$17\%18\%5\%25\%25\%10\%$

$4\mathrm{.}1$ In what fraction of all cycles is the shift$-$left $1$ unit used?

The shift left$-1$ unit is used only for branch instructions: $25\%$

$4\mathrm{.}2$ In what fraction of all cycles is the input of the sign$-$extend circuit needed?

addi, beq, not, lw$,$ sw: $18+25+25+10=78\%$

$4\mathrm{.}3$ What is the utilization of the second input data port of the ALU?

The second input port of the ALU is used in all instructions except the unconditional branch

instruction $($jal for example$)$ where the ALU does not need to determine if a branch is to be

taken.

add, addi, not, beq, lw$,$ sw $=100\%$