Recent questions tagged compiler-design - GATE CSE Doubts

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In Compiler Construction course While mapping the conditions for the Shift and Reduce actions in SLR table

asked 6 days ago in Theory of Computation by Arsalan Sheikh (6 points) | 11 views

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Why we need the closure of LR(0) items?
In LR(0) parser we construct the dfa and in the dfa states we enter the closure of LR(0) items. ex - S` ->.S S-> .a Here we enter all the productions of grammar where there is . before non terminal. Why we need to do that?

asked Apr 21 in Compiler Design by darshansharma_ (13 points) | 32 views

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Why we need to remove null production from grammar?

asked Apr 19 in Theory of Computation by darshansharma_ (13 points) | 9 views

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GATE2016-1-19 Video Solution
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 to static single assignment form is __________.

asked Apr 19 in Compiler Design by admin (3.6k points) | 2 views

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GATE2015-1-55 Video Solution
The least number of temporary variables required to create a three-address code in static single assignment form for the expression $q + r / 3 + s - t * 5 + u * v/w$ is__________________.

asked Apr 19 in Compiler Design by admin (3.6k points) | 3 views

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GATE2007-53 Video Solution
Consider the following two statements: P: Every regular grammar is LL(1) Q: Every regular set has a LR(1) grammar Which of the following is TRUE? Both P and Q are true P is true and Q is false P is false and Q is true Both P and Q are false

asked Apr 19 in Compiler Design by admin (3.6k points) | 2 views

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GATE2003-18 Video Solution
In a bottom-up evaluation of a syntax directed definition, inherited attributes can always be evaluated be evaluated only if the definition is L-attributed be evaluated only if the definition has synthesized attributes never be evaluated

asked Apr 19 in Compiler Design by admin (3.6k points) | 2 views

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GATE2014-3-34 Video Solution
Consider the basic block given below. a = b + c c = a + d d = b + c e = d - b a = e + b The minimum number of nodes and edges present in the DAG representation of the above basic block respectively are $6$ and $6$ $8$ and $10$ $9$ and $12$ $4$ and $4$

asked Apr 19 in Compiler Design by admin (3.6k points) | 2 views

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GATE2017-1-52 Video Solution
Consider the expression $(a-1) * (((b+c)/3)+d)$. Let $X$ be the minimum number of registers required by an optimal code generation (without any register spill) algorithm for a load/store architecture, in which only load ... instructions can have memory operands and arithmetic instructions can have only register or immediate operands. The value of $X$ is _____________ .

asked Apr 19 in Compiler Design by admin (3.6k points) | 3 views

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GATE2006-32, ISRO2016-35 Video Solution
Consider the following statements about the context free grammar $G = \left \{ S \rightarrow SS, S \rightarrow ab, S \rightarrow ba, S \rightarrow \epsilon \right \} $ $G$ is ambiguous $G$ produces all strings with equal number of $a$'s ... combination below expresses all the true statements about $G$? I only I and III only II and III only I, II and III

asked Apr 19 in Compiler Design by admin (3.6k points) | 2 views

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GATE2000-1.18, ISRO2015-25 Video Solution
The number of tokens in the following C statement is printf("i=%d, &i=%x", i, &i); $3$ $26$ $10$ $21$

asked Apr 19 in Compiler Design by admin (3.6k points) | 1 view

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GATE2005-83a Video Solution
Statement for Linked Answer Questions 83a & 83b: Consider the following expression grammar. The semantic rules for expression evaluation are stated next to each grammar production. ... a reduce action It detects shift-reduce conflict, and resolves the conflict in favor of a reduce over a shift action

asked Apr 19 in Compiler Design by admin (3.6k points) | 7 views

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GATE2014-2-34 Video Solution
For a C program accessing $\mathbf{X[i] [j] [k]}$, the following intermediate code is generated by a compiler. Assume that the size of an integer is $32$ bits and the size of a character is $8$ bits. t0 = i ∗ 1024 t1 = j ∗ 32 t2 = k ∗ 4 t3 = t1 + t0 t4 ... as "char $\mathbf{X[4] [32] [8]}$ . $\mathbf{X}$ is declared as "char $\mathbf{X[32] [16] [2]}$ .

asked Apr 19 in Compiler Design by admin (3.6k points) | 1 view

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GATE2013-9 Video Solution
What is the maximum number of reduce moves that can be taken by a bottom-up parser for a grammar with no epsilon and unit-production (i.e., of type $A \rightarrow \epsilon$ and $A \rightarrow a$) to parse a string with $n$ tokens? $n/2$ $n-1$ $2n-1$ $2^{n}$

asked Apr 19 in Compiler Design by admin (3.6k points) | 2 views

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GATE2003-16 Video Solution
Which of the following suffices to convert an arbitrary CFG to an LL(1) grammar? Removing left recursion alone Factoring the grammar alone Removing left recursion and factoring the grammar None of the above

asked Apr 19 in Compiler Design by admin (3.6k points) | 1 view

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GATE2017-1-43 Video Solution
Consider the following grammar: stmt $\rightarrow$ if expr then expr else expr; stmt | $0$ expr $\rightarrow$ term relop term | term term $\rightarrow$ id | number id $\rightarrow$ a | b | c number $\rightarrow [0-9]$ where relop is a relational ... program if $e_1$ then $e_2$ else $e_3$ has $2$ control flow paths. $e_1 \rightarrow e_2$ and $e_1 \rightarrow e_3$.

asked Apr 19 in Compiler Design by admin (3.6k points) | 2 views

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GATE1999-1.17 Video Solution
Which of the following is the most powerful parsing method? LL (1) Canonical LR SLR LALR

asked Apr 19 in Compiler Design by admin (3.6k points) | 3 views

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GATE1998-1.27 Video Solution
Type checking is normally done during lexical analysis syntax analysis syntax directed translation code optimization

asked Apr 19 in Compiler Design by admin (3.6k points) | 2 views

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GATE2015-1-1‏3 Video Solution
Which one of the following is TRUE at any valid state in shift-reduce parsing? Viable prefixes appear only at the bottom of the stack and not inside Viable prefixes appear only at the top of the stack and not inside The stack contains only a set of viable prefixes The stack never contains viable prefixes

asked Apr 19 in Compiler Design by admin (3.6k points) | 2 views

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GATE2013-42 Video Solution
What is the return value of $f(p,p)$, if the value of $p$ is initialized to $5$ before the call? Note that the first parameter is passed by reference, whereas the second parameter is passed by value. int f (int &x, int c) { c = c - 1; if (c==0) return 1; x = x + 1; return f(x,c) * x; }

asked Apr 19 in Programming by admin (3.6k points) | 2 views

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GATE2010-37 Video Solution
The program below uses six temporary variables $a, b, c, d, e, f$. a = 1 b = 10 c = 20 d = a + b e = c + d f = c + e b = c + e e = b + f d = 5 + e return d + f Assuming that all operations take their operands from registers, what is the minimum number of registers needed to execute this program without spilling? $2$ $3$ $4$ $6$

asked Apr 19 in Compiler Design by admin (3.6k points) | 3 views

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GATE2005-61 Video Solution
Consider line number $3$ of the following C-program. int main() { /*Line 1 */ int I, N; /*Line 2 */ fro (I=0, I<N, I++); /*Line 3 */ } Identify the compiler’s response about this line while creating the object-module: No compilation error Only a lexical error Only syntactic errors Both lexical and syntactic errors

asked Apr 19 in Compiler Design by admin (3.6k points) | 1 view

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GATE2014-3-11 Video Solution
The minimum number of arithmetic operations required to evaluate the polynomial $P(X) = X^5+4X^3+6X+5$ for a given value of $X$, using only one temporary variable is ______.

asked Apr 19 in Compiler Design by admin (3.6k points) | 1 view

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GATE2003-57 Video Solution
Consider the grammar shown below. $S \rightarrow C \ C$ $C \rightarrow c \ C \mid d$ This grammar is LL(1) SLR(1) but not LL(1) LALR(1) but not SLR(1) LR(I) but not LALR(1)

asked Apr 19 in Compiler Design by admin (3.6k points) | 1 view

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GATE2018-37 Video Solution
A lexical analyzer uses the following patterns to recognize three tokens $T_1$, $T_2$, and $T_3$ over the alphabet $\{a, b, c\}$. $T_1$: $a?(b \mid c)^*a$ $T_2$: $b?(a \mid c)^*b$ $T_3$: $c?(b \mid a)^*c$ ... . If the string bbaacabc is processes by the analyzer, which one of the following is the sequence of tokens it outputs? $T_1T_2T_3$ $T_1T_1T_3$ $T_2T_1T_3$ $T_3T_3$

asked Apr 19 in Compiler Design by admin (3.6k points) | 2 views

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GATE1994-1.12 Video Solution
Generation of intermediate code based on an abstract machine model is useful in compilers because it makes implementation of lexical analysis and syntax analysis easier syntax-directed translations can be written for intermediate code generation it enhances ... the compiler it is not possible to generate code for real machines directly from high level language programs

asked Apr 19 in Compiler Design by admin (3.6k points) | 3 views

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GATE2009-42 Video Solution
Which of the following statements are TRUE? There exist parsing algorithms for some programming languages whose complexities are less than $\Theta(n^3)$ A programming language which allows recursion can be implemented with static storage allocation. No L-attributed definition ... both source language and intermediate code level. I and II I and IV III and IV I, III and IV

asked Apr 19 in Compiler Design by admin (3.6k points) | 2 views

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GATE2003-76 Video Solution
Which of the following is NOT an advantage of using shared, dynamically linked libraries as opposed to using statistically linked libraries? Smaller sizes of executable files Lesser overall page fault rate in the system Faster program startup Existing programs need not be re-linked to take advantage of newer versions of libraries

asked Apr 19 in Compiler Design by admin (3.6k points) | 1 view

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GATE2015-1-8 Video Solution
For computer based on three-address instruction formats, each address field can be used to specify which of the following: (S1) A memory operand (S2) A processor register (S3) An implied accumulator register Either $S1$ or $S2$ Either $S2$ or $S3$ Only $S2$ and $S3$ All of $S1$, $S2$ and $S3$

asked Apr 19 in Compiler Design by admin (3.6k points) | 2 views

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GATE1995-1.14 Video Solution
A linker is given object modules for a set of programs that were compiled separately. What information need to be included in an object module? Object code Relocation bits Names and locations of all external symbols defined in the object module Absolute addresses of internal symbols

asked Apr 19 in Compiler Design by admin (3.6k points) | 2 views

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GATE2011-36 Video Solution
Consider evaluating the following expression tree on a machine with load-store architecture in which memory can be accessed only through load and store instructions. The variables $a, b, c, d,$ and $e$ are initially stored in memory. The binary operators used ... stored in memory, what is the minimum number of registers needed to evaluate this expression? $2$ $9$ $5$ $3$

asked Apr 19 in Compiler Design by admin (3.6k points) | 2 views

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GATE2014-1-34 Video Solution
A canonical set of items is given below $S \to L .> R $ $Q \to R.$ On input symbol $<$ the set has a shift-reduce conflict and a reduce-reduce conflict. a shift-reduce conflict but not a reduce-reduce conflict. a reduce-reduce conflict but not a shift-reduce conflict. neither a shift-reduce nor a reduce-reduce conflict.

asked Apr 19 in Compiler Design by admin (3.6k points) | 1 view

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GATE2001-1.18 Video Solution
Which of the following statements is false? An unambiguous grammar has same leftmost and rightmost derivation An LL(1) parser is a top-down parser LALR is more powerful than SLR An ambiguous grammar can never be LR(k) for any k

asked Apr 19 in Compiler Design by admin (3.6k points) | 1 view

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GATE2013-40 Video Solution
Consider the following two sets of LR(1) items of an LR(1) grammar.$\begin{array}{l|l} X \rightarrow c.X, c/d &X → c.X, \$\\ X \rightarrow .cX, c/d& X → .cX, \$\\ X \rightarrow .d, c/d & X → .d, \$ ... Cannot be merged since goto on c will lead to two different sets. $1$ only $2$ only $1$ and $4$ only $\text{1, 2, 3}$ and $4$

asked Apr 19 in Compiler Design by admin (3.6k points) | 1 view

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GATE2012-36 Video Solution
Consider the program given below, in a block-structured pseudo-language with lexical scoping and nesting of procedures permitted. Program main; Var ... Procedure A1; Var ... Call A2; End A1 Procedure A2; Var ... Procedure A21; Var ... ... The correct set of activation records along with their access links is given by:

asked Apr 19 in Compiler Design by admin (3.6k points) | 3 views

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GATE2005-32 Video Solution
Consider the following C program: double foo (double); /* Line 1 */ int main() { double da, db; //input da db = foo(da); } double foo (double a) { return a; } The above code compiled without any error ... or error some compiler-warnings not leading to unintended results some compiler-warnings due to type-mismatch eventually leading to unintended results compiler errors

asked Apr 19 in Programming by admin (3.6k points) | 1 view

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GATE1993-7.6 Video Solution
A simple two-pass assembler does the following in the first pass: It allocates space for the literals. It computes the total length of the program. It builds the symbol table for the symbols and their values. It generates code for all the load and store register instructions. None of the above.

asked Apr 19 in Compiler Design by admin (3.6k points) | 3 views

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GATE2000-2.21, ISRO2015-24 Video Solution
Given the following expression grammar: $\begin{align} E &\to E * F \mid F + E \mid F \\[1em] F &\to F - F \mid id \end{align}$ Which of the following is true? $*$ has higher precedence than $+$ $-$ has higher precedence than $*$ $+$ and $-$ have same precedence $+$ has higher precedence than $*$

asked Apr 19 in Compiler Design by admin (3.6k points) | 1 view

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GATE2005-14 Video Solution
The grammar $A \rightarrow AA \mid (A) \mid \epsilon$ is not suitable for predictive-parsing because the grammar is: ambiguous left-recursive right-recursive an operator-grammar

asked Apr 19 in Compiler Design by admin (3.6k points) | 4 views

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GATE2017-1-12 Video Solution
Consider the following intermediate program in three address code p = a - b q = p * c p = u * v q = p + q Which one of the following corresponds to a static single assignment form of the above code? p1 = a - b q1 = p1 * c p1 = u * v q1 = p1 + q1 p3 = a - b q4 = p3 * c p4 = u * ... p1 = a - b q1 = p2 * c p3 = u * v q2 = p4 + q3 p1 = a - b q1 = p * c p2 = u * v q2 = p + q

asked Apr 19 in Compiler Design by admin (3.6k points) | 2 views

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