GATE CS Compiler Design questions

Let $G=(V, \Sigma, S, P)$ be a context-free grammar in Chomsky Normal Form with $\Sigma=\{a, b, c\}$ and $V$ containing $10$ variable symbols including the start symbol $S$. The string $w=a^{30} b^{30} c^{30}$ is derivable from $S$. The number of steps (application of rules) in the derivation $S \rightarrow^* w$ is __________.

​​​Consider the following two sets: …

​​​​​Which of the following statements is/are FALSE?

​​​​Consider a context-free grammar $\text{G}$ with the following $3$ rules. $$S \rightarrow a S, S \rightarrow a S b S , S \rightarrow c$$ Let $w \in L(G)$. Let $n_{a}(w), n_{b}(w), n_{c}(w)$ denote the number of times $a, b, c$ occur in $w$, respectively. Which of the following statements is/are TRUE?

Consider the following augmented grammar, which is to be parsed with a $\text{SLR}$ parser. The set of terminals is $\{a, b, c, d, \#, @\}$ $$\begin{array}{l} S^{\prime} \rightarrow S \\ S \rightarrow S S|A a| b A c|B c| b B a \\ A \rightarrow d \# \\ B \rightarrow @ \end{array}$$ Let …

Consider the following statements regarding the front-end and back-end of a compiler. S1: The front-end includes phases that are independent of the target hardware. S2: The back-end includes phases that are specific to the target hardware. S3: The back-end includes phases that are specific to the programming language used in the source code. Identify the …

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 control flow graph shown. Which one of the following choices correctly lists the set of live variables at the exit point of each basic block?

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 $\text{“\#", “0" and “1"},$ respectively. $X.val$ denotes the synthesized attribute (a …

Which one of the following statements is $\text{TRUE}?$

Consider the augmented grammar with $\{ +, {\ast}, (,),\text{id} \}$ as the set of terminals. $S’ \rightarrow S$ $S \rightarrow S + R\; |\; R$ $R \rightarrow R {\ast} P \;| \;P$ $P \rightarrow (S)\; |\; \text{id}$ If $I_{0}$ is the set of two $\textit{LR}(0)$ items $\{ [S’ \rightarrow S.], [S \rightarrow S. + R] \}$, then …

Consider the following grammar along with translation rules. …

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?

Consider the following statements. $S_1:$ Every $\text{SLR(1)}$ grammar is unambiguous but there are certain unambiguous grammars that are not $\text{SLR(1)}$. $S_2:$ For any context-free grammar, there is a parser that takes at most $O(n^3)$ time to parse a string of length $n$. Which one of the following options is correct?

​​​Consider the following grammar (that admits a series of declarations, followed by expressions) and the associated syntax directed translation $\text{(SDT)}$ actions, given as pseudo-code …

Consider the following context-free grammar where the set of terminals is $\{a,b,c,d,f\}$. …

Consider the following $C$ code segment: a = b + c; e = a + 1; d = b + c; f = d + 1; g = e + f; In a compiler, this code segment is represented internally as a directed acyclic graph $\text{(DAG)}$. The number of nodes in the $\text{DAG}$ is _____________

Consider the following $\text{ANSI C}$ program: int main () { Integer x; return 0; } Which one of the following phases in a seven-phase $C$ compiler will throw an error?

In the context of compilers, which of the following is/are $\text{NOT}$ an intermediate representation of the source program?

​​​​​​Consider the following $\text{ANSI C}$ code segment: z=x + 3 + y->f1 + y->f2; for (i = 0; i < 200; i = i + 2) { if (z > i) { p = p + x + 3; q = q + y->f1; } else { p = p + y->f2; q = q + x + 3; } } Assume that the variable $y$ points to a $\textsf{struct}$ (allocated on the heap) containing two fields $\textsf{f1}$ and …