CD |Gate-2019| Previous Year Questions| Set-2

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CD |Gate-2019| Compiler Design

1. Consider the grammar given below:

S → Aa
A → BD
B → b | ε
D → d | ε

Let a, b, d, and $ be indexed as follows:

a	b	d	$
3	2	1	0

Compute the FOLLOW set of the non-terminal B and write the index values for the symbols in the FOLLOW set in the descending order. (For example, if the FOLLOW set is {a, b, d, $}, then the answer should be 3210). [GATE – 2019]

a. 30
b. 31
c. 12
d. 33

Answer : b)
CD |Gate-2019|

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2. Which one of the following kinds of derivation is used by LR parsers? [GATE – 2019]

a. Leftmost in reverse
b. Leftmost
c. Rightmost in reverse
d. Rightmost

Answer : c)

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3. Consider the augmented grammar given below:

    S’ → S
    S → 〈L〉 | id
L → L,S | S

Let I₀ = CLOSURE ({[S’ → ·S]}). The number of items in the set GOTO (I₀ , 〈 ) is: _____. [GATE – 2019]

a. 4
b. 5
c. 6
d. 7

Answer:  b)
CD |Gate-2019|

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4. Consider the following grammar and the semantic actions to support the inheriteatd type declaration attributes. Let X₁, X₂, X₃, X₄, X₅ and X₆ be the placeholders for the non-terminals D, T, L or L₁ in the following table:

Production Rule	Semantic action
D → T L	X1. type = X2 .type
T → int	T.type = int
T → float	T.type = float
L → L1  , id	X3. type = X4. type addType (id.entry, X5. type)
L → id	addType(id.entry, X6. type)

Which one of the following are the appropriate choices for X₁, X₂, X₃ and X₄? [GATE – 2019]

a. X₁ = L, X₂ = L, X₃ = L₁, X₄ = T
b. X₁ = L, X₂ = T, X₃ = L₁, X₄ = L
c. X₁ = T, X₂ = L, X₃ = L₁, X₄ = T
d. X₁ = T, X₂ = L, X₃ = T, X₄ = L₁

Answer : b)

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