JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III Year COMPILER DESIGN Previous Question Paper (September - 2021 - R13)

A compiler translates source code into target machine code through a series of sequential phases:

1. Lexical Analysis: Reads the source program as a stream of characters and groups them into meaningful sequences called tokens.
2. Syntax Analysis: Takes tokens and creates a hierarchical structure, typically an Abstract Syntax Tree (AST), ensuring the code follows the language's grammar rules.
3. Semantic Analysis: Checks for semantic consistency, such as type checking and scope resolution, ensuring the program makes sense beyond its structure.
4. Intermediate Code Generation: Produces a machine-independent, low-level representation of the source code, such as Three-Address Code.
5. Code Optimization: Improves the intermediate code to make the final machine code run faster or consume less memory without changing the program's behavior.
6. Code Generation: Translates the optimized intermediate code into target-specific machine or assembly language.
7. Symbol Table Management: A supporting phase that records identifiers and their attributes throughout the compilation process.
8. Error Handling: Detects and reports errors encountered during any of the above phases.

Bootstrapping is the process of using a compiler to compile itself or a newer version of itself. It is a technique used to port a compiler to a new environment or to develop a compiler for a new language.

The process is often represented using the T-diagram, where a compiler is defined by the source language it accepts, the target language it produces, and the language in which it is implemented. The steps typically involve:

• Writing a small subset of the target language compiler in an existing language.
• Compiling this subset using an existing compiler to produce a machine-executable version.
• Using this executable to compile a more complex version of the compiler written in the target language itself.
• Repeating this process until the full-featured compiler is produced.

This allows developers to move from a basic implementation to a fully functional, self-hosting compiler without needing to write the entire system in machine code.