GATE CS 2024 Set 2 — Question 43

MCQ+2 / -0.67MediumThree-Address CodeIntermediate Code GenerationCompiler Design

Compiler Design → Intermediate Code Generation → Three-Address Code

Last updated 20 August 2026

Question

Consider the following expression:

x[i] = (p + r) * -s[i] + u/w

. The following sequence shows the list of triples representing the given expression, with entries missing for triples (1), (3), and (6).


(0)	+	$p$	$r$
(1)
(2)	uminus	(1)
(3)
(4)	/	$u$	$w$
(5)	+	(3)	(4)
(6)
(7)	=	(6)	(5)

Which one of the following options fills in the missing entries CORRECTLY?

(1) =[]

s

i

(3) * (0) (2) (6) []=

x

i

(1) []=

s

i

(3) – (0) (2) (6) =[]

x

(5)

(1) =[]

s

i

(3) * (0) (2) (6) []=

x

(5)

(1) []=

s

i

(3) – (0) (2) (6) =[]

x

i

Correct answer

(A) (1) =[] s i (3) (0) (2) (6) []= x i

Solution

The expression is

x[i] = (p + r) * -s[i] + u/w

.
We can break this down into three-address code (triples):

1.Compute

p+r

: (0) + p r

2.Access

s[i]

: This requires an array load operation. In triples, this is often denoted as =[] s i (load from array

s

at index

i

). This corresponds to triple (1).

3.Compute

-s[i]

: (2) uminus (1)

4.Compute

(p+r) * -s[i]

: This multiplies the result of (0) and (2). So triple (3) is * (0) (2).

5.Compute

u/w

: (4) / u w

6.Compute the sum: (5) + (3) (4)

7.Assign the result to

x[i]

: The assignment

x[i] = \dots

requires an array store operation. The LHS

x[i]

is the target. In the given table, triple (7) is = (6) (5), which means "assign the value of (5) to the location defined by (6)". Therefore, triple (6) must define the location

x[i]

. The operation for array store access (l-value) is typically []= x i.

Thus:
(1) =[] s i
(3) * (0) (2)
(6) []= x i

This matches Option (A).

GATE CS 2024 Set 2 — Question 43

Question

Correct answer

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