1. What is the purpose of using Intermediate Representations (IR) in a compiler?
A) To generate machine code directly
B) To simplify the compilation process and perform optimizations
C) To provide debugging information
D) To check for syntax errors
Answer: B) To simplify the compilation process and perform optimizations
2. Which of the following is a key feature of Three-Address Code (TAC)?
A) Each instruction contains at most three operands
B) It is a high-level language representation
C) It uses more than three operands in each instruction
D) It directly represents machine instructions
Answer: A) Each instruction contains at most three operands
3. In Three-Address Code, how is a typical statement represented?
A) result = operand1 operand2
B) result = operand1 operator operand2
C) operand1 = operand2 operator operand3
D) operand1 operator operand2
Answer: B) result = operand1 operator operand2
4. Which of the following is true about Syntax Trees?
A) They represent the abstract syntactic structure of a program
B) They are used only for debugging purposes
C) They directly map to machine code
D) They are used only during lexical analysis
Answer: A) They represent the abstract syntactic structure of a program
5. What does a Directed Acyclic Graph (DAG) represent in compiler optimization?
A) The flow of control in a program
B) The dependencies between expressions, showing how values are computed
C) The sequence of machine instructions
D) The syntax structure of the program
Answer: B) The dependencies between expressions, showing how values are computed
6. What is the main difference between a Syntax Tree and a Directed Acyclic Graph (DAG)?
A) Syntax trees allow for cycles, while DAGs do not
B) A syntax tree represents the full structure of a program, while a DAG represents only expression dependencies
C) DAGs have more nodes than syntax trees
D) Syntax trees are used only in optimization, while DAGs are used in parsing
Answer: B) A syntax tree represents the full structure of a program, while a DAG represents only expression dependencies
7. Why is Three-Address Code considered an important intermediate representation?
A) It closely resembles high-level source code
B) It is easier for humans to understand than machine code
C) It allows for optimization and is platform-independent
D) It is only used for debugging
Answer: C) It allows for optimization and is platform-independent
8. What is the primary advantage of using DAGs in intermediate code representation?
A) They allow for cycle detection in the code
B) They help in reducing the number of instructions by eliminating redundant expressions
C) They are easy to translate into machine code
D) They help in debugging errors in the program
Answer: B) They help in reducing the number of instructions by eliminating redundant expressions
9. Which of the following is NOT a feature of Three-Address Code (TAC)?
A) It is used to simplify the task of machine code generation
B) Each TAC instruction can involve at most three operands
C) It is machine-specific
D) It is a low-level representation used in compilers
Answer: C) It is machine-specific
10. In a Syntax Tree, which of the following represents the root node?
A) The variable used in the program
B) The operator applied to two or more operands
C) The entire program
D) The constant values used in the program
Answer: B) The operator applied to two or more operands
11. Which intermediate representation would be most efficient for optimizing arithmetic expressions in a program?
A) Syntax tree
B) Three-address code
C) Directed Acyclic Graph (DAG)
D) Machine code
Answer: C) Directed Acyclic Graph (DAG)
12. What does a “common subexpression” refer to in a DAG?
A) An expression that appears multiple times in the code
B) A node that has only one outgoing edge
C) A redundant operation that can be eliminated for optimization
D) A cycle in the graph
Answer: A) An expression that appears multiple times in the code
13. How does the use of Three-Address Code (TAC) affect the optimization phase of a compiler?
A) It simplifies the expression evaluation and helps identify common subexpressions
B) It eliminates the need for lexical analysis
C) It directly translates to the machine code without further optimization
D) It reduces the need for semantic analysis
Answer: A) It simplifies the expression evaluation and helps identify common subexpressions
14. Which of the following best describes a Directed Acyclic Graph (DAG) used in compilers?
A) A graph where nodes represent basic operations, and edges represent control flow
B) A graph used to store all possible execution paths of a program
C) A graph that shows expression dependencies to remove redundant calculations
D) A graph that only represents the structure of the source code
Answer: C) A graph that shows expression dependencies to remove redundant calculations
15. Which of the following is a benefit of using DAGs for expression evaluation in compilers?
A) They increase the time complexity of code generation
B) They allow the compiler to perform code motion and eliminate redundant expressions
C) They reduce the readability of the code
D) They can only be used for mathematical expressions
Answer: B) They allow the compiler to perform code motion and eliminate redundant expressions