b$)$ In the following ARM$9$ program, there are two examples of 'data forwarding' and

$6$

one further example of a 'read$-$after$-$write' hazard that results in an interlock. Identify all three.

Mnemonic

MOV $r1,$#$00004A000$

MOV r $2,$ #$0$x$00003$BC$0$

MOV ro$,1,$ LSL #$8$

SUB $r3,r2,r1$

ADDr$4,r1,r2$

RSB $r5,r4,r0$

MOV $r6,$#$0000002E4$

MOV $r7,$#$00002E400$

ADDr$2,r1,r0$

Comment

; move $0$x$0004$A$000$ into $r1$

; move $0$x$00003$BC$0$ into r$2$

; left shift $r1$ by $8$ bits

; subtract $r1$ from $r2$

; add $r1$ and $r2,$ sum in $r4$

; subtract $r4$ from $r0$

;move $0$x$000002$E$4$ into $x6$

; move $0$x$0002$E$400$ into $r7$

; add $r1$ and $r2,$ sum in $r2$

c$)$ Draw a pipeline diagram for the program given above assuming that it is executed

$8$

using the ARM$9$ microprocessor. What is the performance as measured in "clocks per instruction' $($CPI$)?($counting clock cycles from the execute stage of the first instruction to the execute stage of the last instruction$)$