Question

Rewrite the loop from Exercise 2.29 to reduce the number of MIPS instructions executed

Short answer

The reduce number of Mips instructions are:

addi $t1, $s0, 400

LOOP: lw $s1, 0($t1)

add $s2, $s2, $s1

addi $t1, $t1, -4

bne $t1, $s0 LOOP

Step-by-step solution

MIPS instructions used in Exercise 2.29

addi: It is short for add immediate

lw: It is short for load word

add: It is an arithmetic operation used to add

slti: It is short for set on less than or equal

bne: it is short for the branch on not equal it test if registers are not equal

Given MIPS instruction

addi $t1, $0, $0

LOOP: lw $s1, 0($s0)

add $t2, $s0

addi $s0. $s0, 4

addi $t1, $t1, 1

slti $t2, $t1, 100

bne $t2, $s0, LOOP

Rewrite the loop to Minimize the number of MIPS instruction

Here, we used variable only for loop control

Now, reduce the number of MIPS instruction

addi $t1, $s0, 400 # add a constant number

LOOP: lw $s1, 0($t1) # load word

add $s2, $s2, $s1 # add first element

addi $s2, $s2, $s1 # add immediate and immediate means a constant no.

bne $t1, $s0, LOOP #Loop until the pointer reaches limit