CS606 Compiler Construction

CS606: Compiler Construction

CS606 Compiler Construction unveils the "magic" behind how high-level programming languages, like C++, Java, or Python, are translated into the low-level machine code that a computer's processor can actually execute. A compiler is a fundamental piece of software in the computer science ecosystem, and this course takes you through the entire process of building one, from source code to executable.

The course is structured around the classical phases of a modern compiler. You will learn how the compiler 'reads' your code (lexical analysis), 'understands' its grammatical structure (syntax analysis), 'interprets' its meaning (semantic analysis), improves its efficiency (optimization), and finally 'generates' the target machine code. This course is a capstone for many computer science concepts, bringing together theory of computation, data structures, and computer architecture.

Key Topics Covered:

• Phase 1: Lexical Analysis (Scanning): The first phase, where the source code is read as a stream of characters and grouped into meaningful "tokens" (like keywords, identifiers, and operators). This phase is often implemented using regular expressions and finite automata.
• Phase 2: Syntax Analysis (Parsing): The parser takes the stream of tokens and builds a data structure, typically an Abstract Syntax Tree (AST), that represents the grammatical structure of the program. This involves context-free grammars (CFGs) and parsing techniques like LR parsing (e.g., YACC) or LL parsing (e.g., recursive descent).
• Phase 3: Semantic Analysis: This phase checks the parsed code for meaning and logical consistency. It performs tasks like type checking (e.g., ensuring you don't add a string to an integer) and builds a symbol table to track variables and functions.
• Phase 4: Intermediate Code Generation: Before optimization, the AST is often translated into a lower-level, machine-independent representation (e.g., three-address code).
• Phase 5: Code Optimization: A crucial phase where the compiler attempts to improve the intermediate code to make it run faster or use less memory. Techniques include constant folding, loop optimizations, and dead code elimination.
• Phase 6: Code Generation: The final phase, where the optimized intermediate code is translated into the target machine's assembly language or machine code. This involves register allocation and instruction selection.

Course Objectives:

1. Understand the complete pipeline of a modern compiler.
2. Use formal language theory (regular expressions, CFGs) to specify and process programming languages.
3. Implement a lexical analyzer (scanner) and a syntax analyzer (parser) using standard tools (like Lex/Flex and Yacc/Bison) or by hand.
4. Perform semantic analysis, including type checking and symbol table management.
5. Appreciate the techniques for code optimization and target code generation.

By building a compiler, you gain an unparalleled, in-depth understanding of how programming languages work. This course is challenging but incredibly rewarding, providing insights that are valuable for any serious software developer.