Question 1

Which of the following grammar rules violate the requirements of an operator grammar ?
P, Q, R are nonterminals, and r, s, t are terminals.
1) P ? Q R
2) P ? Q s R
3) P ? ?
4) P ? Q t R r
A)1 only
B)1 and 3 only
C)2 and 3 only
D)3 and 4 only

Accepted Answer

An operator grammar must not have any productions of the form A → B (where A and B are nonterminals) or any productions with ε (empty string). Thus, options 1 and 3 violate these rules.

Question 2

Consider the grammar with the following translation rules and E as the start symbol. E ? E1 # T { E.value = E1.value * T.value } | T{ E.value = T.value }T ? T₁ & F { T.value = T₁.value + F.value } | F{ T.value = F.value }F ? num { F.value = num.value } Compute E.value for the root of the parse tree for the expression: 2 # 3 & 5 # 6 & 4. A)200 B)180 C)160 D)40

Accepted Answer

C

Question 3

Assume that the SLR parser for a grammar G has n₁ states and the LALR parser for G has n₂ states. The relationship between n₁ and n₂ is: A) n₁ is necessarily less than n₂ B) n₁ is necessarily equal to n₂ C) n₁ is necessarily greater than n₂ D)none of these

Accepted Answer

B

Question 4

Consider the grammar shown below S ? i E t S S' | a S' ? e S | ? E ? b In the predictive parse table. M, of this grammar, the entries M[S', e] and M[S', $] respectively are
A){S' ? e S} and {S' ? e}
B){S' ? e S} and {}
C){S' ? ?} and {S' ? ?}
D){S' ? e S, S'? ?} and {S' ? ?}

Accepted Answer

The answer of Consider the grammar shown below S ?...

Question 5

Consider the translation scheme shown below
S ? T R
R ? + T {print ('+');} R | ?
T ? num {print (num.val);}
Here num is a token that represents an integer and num.val represents thecorresponding integer value. For an input string '9 + 5 + 2', this translation scheme willprint
A)9 + 5 + 2
B)9 5 + 2 +
C)9 5 2 + +
D)+ + 9 5 2

Accepted Answer

The answer of Consider the translation scheme shown below
S ?...

Question 6

Which of the following is essential for converting an infix expression to the postfix from efficiently?
A)An operator stack
B)An operand stack
C)An operand stack and an operator stack
D)A parse tree

Accepted Answer

An operator stack is essential for converting an infix expression to postfix form efficiently because it helps manage the operators' precedence and associativity rules while processing the expression from left to right. Operand stacks are not used in this conversion process; instead, operands are directly placed in the output sequence.

Question 7

The grammar whose productions are ? if id then ? if id then else ? id := id Is ambiguous because A- the sentence if a then if b then c:= d has two parse trees B- the left most and right most derivations of the sentence if a then if b then c:= d give rise to different parse trees C- the sentence if a then if b then c:= d else c:= f has more than two parse trees D- the sentence if a then if b then c:= d else c:= f has two parse trees A)a B)b C)c D)d

Accepted Answer

The answer of The grammar whose productions are
<stmt> ? if...

Question 8

Consider the following grammars (S₁) : A --> aBCD B --> bc|c C --> d|? D -> b(S₂) : A --> aBCD B --> bc|? C --> d|c D -> b ( S₃) : A --> aBCD B --> bc|? C --> d|? D -> b ( S₄) : A --> aBCD B --> bc|c C --> d|c D -> b Which of the following grammar has same follow set for variable B? A)Only (S₁), (S₂) and ( S₃₃), ( S₄) B)Only (S₁), ( S₃₃) and (S₂), ( S₄) C)Only (S₂), ( S₃₃) and (S₁), ( S₄) D)None of the above

Accepted Answer

The answer of Consider the following grammars (S₁) : A --> aBCD B...

Question 9

Which is True about SR and RR-conflict:
A)If there is no SR-conflict in CLR(1) then definitely there will be no SR-conflict in LALR(1).
B)RR-conflict might occur if lookahead for final items(reduce-moves) is same.
C)Known that CLR(1) has no RR-conflict, still RR-conflict might occur in LALR(1).
D)All of the above.

Accepted Answer

All the statements are true regarding SR and RR-conflicts in the context of CLR(1) and LALR(1) parsers. A) is true because LALR(1) parsers are constructed by merging states of the CLR(1) automaton that have the same core, which can lead to fewer SR-conflicts than in CLR(1). B) is true because RR-conflicts occur when two rules are reducible in the same state with the same lookahead, which is a direct consequence of having the same lookahead for final items. C) is true because the process of merging states in LALR(1) can introduce RR-conflicts that were not present in CLR(1), due to the combination of lookaheads from different states.

Question 10

Which of the following statement(s) regarding a linker software is/are true ? I A function of a linker is to combine several object modules into a single load module. II A function of a linker is to replace absolute references in an object module by symbolic references to locations in other modules.
A)Only I
B)Only II
C)Both I and II
D)Neither I nor II

Accepted Answer

Linkers combine object modules into a single load module, but they replace symbolic references with absolute addresses, not the other way around.

Question 11

Shift-Reduce parsers perform the following:
A)Shift step that advances in the input stream by K(K > 1) symbols and Reduce step that applies a completed grammar rule to some recent parse trees, joining them together as one tree with a new root symbol.
B)Shift step that advances in the input stream by one symbol and Reduce step that applies a completed grammar rule to some recent parse trees, joining them together as one tree with a new root symbol.
C)Shift step that advances in the input stream by K(K = 2) symbols and Reduce step that applies a completed grammar rule to form a single tree
D)Shift step that does not advance in the input stream and Reduce step that applies a completed grammar rule to form a single tree.

Accepted Answer

Shift-Reduce parsers work by shifting the next input symbol onto the top of the stack (advancing in the input stream by one symbol) and reducing when a rule is completed, combining the items on the stack into a single node with a new root symbol.

Question 12

Incremental-Compiler is a compiler
A)which is written in a language that is different from the source language
B)compiles the whole source code to generate object code afresh
C)compiles only those portion of source code that have been modified.
D)that runs on one machine but produces object code for another machine

Accepted Answer

Incremental compilers compile only the portions of the source code that have been modified since the last compilation, rather than recompiling the entire source code. This makes the compilation process faster and more efficient, especially for large projects.

Question 13

Which one of the following is FALSE?
A)A basic block is a sequence of instructions where control enters the sequence at the beginning and exits at the end.
B)Available expression analysis can be used for common subexpression elimination.
C)Live variable analysis can be used for dead code elimination.
D)x = 4 ? 5 => x = 20 is an example of common subexpression elimination.

Accepted Answer

The statement "x = 4 ? 5 => x = 20" does not correctly represent common subexpression elimination. Common subexpression elimination is an optimization technique used in compilers to identify and eliminate expressions that are computed multiple times within a program, replacing them with a single computation and reuse. The given statement seems to be a malformed attempt to express some kind of operation or assignment, but it does not illustrate the concept of common subexpression elimination.

Question 14

Consider the following C code segment.
For (i = 0, i<n; i++)
{
For (j=0; j<n; j++)
{
If (i%2)
{
X += (4*j + 5*i);
Y += (7 + 4*j);
}
}
}
Which one of the following is false?
A)The code contains loop invariant computation
B)There is scope of common sub-expression elimination in this code
C)There is scope of strength reduction in this code
D)There is scope of dead code elimination in this code

Accepted Answer

The code does not contain any dead code since all computed values of X and Y depend on the loop variables i and j, and their values change with each iteration of the loop. Dead code elimination refers to removing parts of the code that do not affect the program's outcome, but here, all parts of the code contribute to the final values of X and Y.

Question 15

Consider the intermediate code given below: 1) i = 1 2) j = 1 3) T₁ = 5 * i 4) T₂ = T₁ + j5 ) T₃ = 4 * T₂ 6) t₄ = T₃ 7) a[ t₄] = -1 8) j = j + 1 9) if j <= 5 goto(3) 10) i = i + 1 11) if i < 5 goto(2) The number of nodes and edges in the control-flow-graph constructed for the abovecode, respectively, are A)5 and 7 B)6 and 7 C)5 and 5 D)7 and 8

Accepted Answer

The answer of Consider the intermediate code given below:
1) i...

Question 16

Consider the following code segment.
X = u - t;
Y = x * v;
X = y + w;
Y = t - z;
Y = x * y;
The minimum number of total variables required to convert the above code segment tostatic single assignment form is Note : This question was asked as Numerical AnswerType.
A)6
B)8
C)9
D)10

Accepted Answer

The answer of Consider the following code segment.
X = u...

Question 17

A linker reads four modules whose lengths are 200, 800, 600 and 500 words respectively. If they are loaded in that order, what are the relocation constants?
A)0, 200, 500, 600
B)0, 200, 1000, 1600
C)200, 500, 600, 800
D)200, 700, 1300, 2100

Accepted Answer

The relocation constant for the first module is 0 because it is the starting point. For the second module, it is 200 (the length of the first module). For the third module, it is 200 + 800 = 1000 (the sum of the lengths of the first and second modules). For the fourth module, it is 200 + 800 + 600 = 1600 (the sum of the lengths of the first, second, and third modules).

Question 18

A language L allows declaration of arrays whose sizes are not known during compilation. It is required to make efficient use of memory. Which of the following is true?
A)A compiler using static memory allocation can be written for L
B)A compiler cannot be written for L, an interpreter must be used
C)A compiler using dynamic memory allocation can be written for L
D)None of the above

Accepted Answer

A compiler using dynamic memory allocation can be written for L to handle arrays whose sizes are not known at compile time, allowing for efficient memory use by allocating memory at runtime as needed.

Question 19

The expression (a*b)* c op........ where 'op' is one of '+', '*' and '?' (exponentiation) can be evaluated on a CPU with a single register without storing the value of (a * b) if
A)'op' is '+' or '*'
B)'op' is '?' or '*'
C)'op' is '?' or '+'
D)not possible to evaluate without storing

Accepted Answer

For '+' and '*', the operations are associative, allowing the CPU to first compute 'a * b', use the result directly with 'c' without needing to store 'a * b' separately. For exponentiation, the order matters and it's not associative in the same way, requiring intermediate storage for practical computation.

Question 20

Which of the following macros can put a micro assembler into an infinite loop?
(i)
)MACRO M1 X
)IF EQ, X ;if X=0 then
M1 X + 1
)ENDC
)IF NE X ;IF X?0 then
)WORD X ;address (X) is stored
Here
)ENDC
)ENDM
(ii)
)MACRO M2X
)IF EQ XM2 X.
ENDC
)IF NE, X
)WORD X+1
)ENDC
)ENDM
A)(ii) only
B)(i) only
C)Both (i) and (ii)
D)None of the above

Accepted Answer

The macro M2 in (ii) lacks a proper increment or change in the condition that would eventually terminate the loop, leading to an infinite loop.

Quiz 4: Compilation and Programming Languages

Which of the following grammar rules violate the requirements of an operator grammar ? P, Q, R are nonterminals, and r, s, t are terminals. 1) P ? Q R 2) P ? Q s R 3) P ? ? 4) P ? Q t R r

Assume that the SLR parser for a grammar G has n₁ states and the LALR parser for G has n₂ states. The relationship between n₁ and n₂ is:

Consider the grammar shown below S ? i E t S S' | a S' ? e S | ? E ? b In the predictive parse table. M, of this grammar, the entries M[S', e] and M[S', $] respectively are

Consider the translation scheme shown below S ? T R R ? + T {print ('+') ;} R | ? T ? num {print (num.val) ;} Here num is a token that represents an integer and num.val represents thecorresponding integer value. For an input string '9 + 5 + 2', this translation scheme willprint

Which of the following is essential for converting an infix expression to the postfix from efficiently?

Consider the following grammars (S₁) : A --> aBCD B --> bc|c C --> d|? D -> b(S₂) : A --> aBCD B --> bc|? C --> d|c D -> b ( S₃) : A --> aBCD B --> bc|? C --> d|? D -> b ( S₄) : A --> aBCD B --> bc|c C --> d|c D -> b Which of the following grammar has same follow set for variable B?

Which is True about SR and RR-conflict:

Which of the following statement(s) regarding a linker software is/are true ? I A function of a linker is to combine several object modules into a single load module. II A function of a linker is to replace absolute references in an object module by symbolic references to locations in other modules.

Shift-Reduce parsers perform the following:

Incremental-Compiler is a compiler

Which one of the following is FALSE?

Consider the following C code segment. For (i = 0, i

Consider the following code segment. X = u - t; Y = x * v; X = y + w; Y = t - z; Y = x * y; The minimum number of total variables required to convert the above code segment tostatic single assignment form is Note : This question was asked as Numerical AnswerType.

A linker reads four modules whose lengths are 200, 800, 600 and 500 words respectively. If they are loaded in that order, what are the relocation constants?

A language L allows declaration of arrays whose sizes are not known during compilation. It is required to make efficient use of memory. Which of the following is true?

The expression (ab) c op........ where 'op' is one of '+', '' and '?' (exponentiation) can be evaluated on a CPU with a single register without storing the value of (a b) if

Which of the following macros can put a micro assembler into an infinite loop? (i) ) MACRO M1 X ) IF EQ, X ;if X=0 then M1 X + 1 ) ENDC ) IF NE X ;IF X?0 then ) WORD X ;address (X) is stored Here ) ENDC ) ENDM (ii) ) MACRO M2X ) IF EQ XM2 X. ENDC ) IF NE, X ) WORD X+1 ) ENDC ) ENDM