Translation and Runtime Environments - Compiler Design - Computer Science & Information Technology Previous Year Questions

Which of the following are true?
I. A programming language which does not permit global variables of any kind and has no nesting of procedures/functions, but permits recursion can be implemented with static storage allocation
II. Multi-level access link (or display) arrangement is needed to arrange activation records only if the programming language being implemented has nesting of procedures/functions
III. Recursion in programming languages cannot be implemented with dynamic storage allocation
IV. Nesting of procedures/functions and recursion require a dynamic heap allocation scheme and cannot be implemented with a stack-based allocation scheme for activation records
V. Programming languages which permit a function to return a function as its result cannot be implemented with a stack-based storage allocation scheme for activation records

Which one of the following is NOT performed during compilation?

Which of the following statements are CORRECT?
1) Static allocation of all data areas by a compiler makes it impossible to implement recursion.
2) Automatic garbage collection is essential to implement recursion.
3) Dynamic allocation of activation records is essential to implement recursion.
4) Both heap and stack are essential to implement recursion.

Consider the following Syntax Directed Translation Scheme (SDTS), with non-terminals {S, A} and terminals {a, b}.
S → aA { print 1 } S → a { print 2 } A → Sb { print 3 }Using the above SDTS, the output printed by a bottom-up parser, for the input aab is:

Consider the following Syntax Directed Translation Scheme (SDTS), with non-terminals {S, A} and terminals {a, b}.
\(S \to aA\)    { print 1 }
\(S \to a\)       { print 2 }
\(A \to Sb\)    { print 3 }
Using the above SDTS, the output printed by a bottom-up parser, for the input aab is:

Consider the following grammar and the semantic actions to support the inherited 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?

Consider the following statements.
I. Symbol table is accessed only during lexical analysis and syntax analysis.
II. Compilers for programming languages that support recursion necessarily need heap storage for memory allocation in the run-time environment.
III. Errors violating the condition ‘any variable must be declared before its use’ are detected during syntax analysis.
Which of the above statements is/are TRUE?

Consider the following statements.

\( S_1 \) : The sequence of procedure calls corresponds to a preorder traversal of the activation tree.
\( S_2 \) : The sequence of procedure returns corresponds to a postorder traversal of the activation tree.

Which one of the following options is correct?

In the context of compilers, which of the following is/are NOT an intermediate representation of the source program?

Consider the following grammar along with translation rules.
\(S \to S_1 \# T\)      \(\{S_{val} = S_{1_{val}} * T_{val}\}\)
\(S \to T\)      \(\{S_{val} = T_{val}\}\)
\(T \to T_1 \% R\)      \(\{T_{val} = T_{1_{val}} \div R_{val}\}\)
\(T \to R\)      \(\{T_{val} = R_{val}\}\)
\(R \to id\)      \(\{R_{val} = id_{val}\}\)
Here # and % are operators and \(id\) is a token that represents an integer and \(id_{val}\) represents the corresponding integer value. The set of non-terminals is \(\{S, T, R, P\}\) and a subscripted non-terminal indicates an instance of the non-terminal.
Using this translation scheme, the computed value of \(S_{val}\) for root of the parse tree for the expression \(20\#10\%5\#8\%2\%2\) is ______________.

Consider the following program:
int main() { f1(); f2(2); f3(); return(0); } int f1() { return(1); } int f2(int X) { f3(); if (X==1) return f1(); else return (X*f2(X-1)); } int f3() { return(5); }
Which one of the following options represents the activation tree corresponding to the main function?

Consider the syntax directed translation given by the following grammar and semantic rules. Here \(N, I, F\) and \(B\) are non-terminals. \(N\) is the starting non-terminal, and #, \(\mathbf{0}\) and \(\mathbf{1}\) are lexical tokens corresponding to input letters "#", "0" and "1", respectively. \(X.val\) denotes the synthesized attribute (a numeric value) associated with a non-terminal \(X\). \(I_1\) and \(F_1\) denote occurrences of \(I\) and \(F\) on the right hand side of a production, respectively. For the tokens \(\mathbf{0}\) and \(\mathbf{1}\), \(\mathbf{0}.val = 0\) and \(\mathbf{1}.val = 1\).
\[\begin{align*} N &\to I \# F & N.val = I.val + F.val \\ I &\to I_1 B & I.val = (2 \cdot I_1.val) + B.val \\ I &\to B & I.val = B.val \\ F &\to B F_1 & F.val = \frac{1}{2} (B.val + F_1.val) \\ F &\to B & F.val = \frac{1}{2} B.val \\ B &\to \mathbf{0} & B.val = \mathbf{0}.val \\ B &\to \mathbf{1} & B.val = \mathbf{1}.val \end{align*}\]
The value computed by the translation scheme for the input string
\[10\#011\]
is ______. (Rounded off to three decimal places)