GATE CS 2024 Set 2 — Question 21

The correct mapping between the compiler phases and their associated concepts is:

• P. Lexical Analyzer: Reads the source program character by character and groups them into meaningful sequences called lexemes, producing Tokens (2).
• Q. Syntax Analyzer: Takes tokens as input and generates a Parse Tree (3) (or Concrete Syntax Tree) checking for syntax errors.
• S. Code Optimizer: Improves the intermediate code. Constant Folding (4) is a standard optimization technique where constant expressions are evaluated at compile time.
• R. Intermediate Code Generator: Generates an intermediate representation. While Syntax Analysis produces the Parse Tree, the Abstract Syntax Tree (AST) (1) is often considered a high-level intermediate representation or the output of a syntax analyzer used for intermediate code generation. Given the options, R maps to 1.

Matching:

• P $\rightarrow$ 2
• Q $\rightarrow$ 3
• R $\rightarrow$ 1
• S $\rightarrow$ 4

This corresponds to option (B).