Building a C Compiler from Scratch: A 64-Part Journey to Self-Compilation

A Compiler Writing Journey In this Github repository, I'm documenting my journey to write a self-compiling compiler for a subset of the C language. I'm also writing out the details so that, if you want to follow along, there will be an explanation of what I did, why, and with some references back to the theory of compilers. But not too much theory, I want this to be a practical journey.

Here are the steps I've taken so far:

Part 0: Introduction to the Journey Part 1: Introduction to Lexical Scanning Part 2: Introduction to Parsing Part 3: Operator Precedence Part 4: An Actual Compiler Part 5: Statements Part 6: Variables Part 7: Comparison Operators Part 8: If Statements Part 9: While Loops Part 10: For Loops Part 11: Functions, part 1 Part 12: Types, part 1 Part 13: Functions, part 2 Part 14: Generating ARM Assembly Code Part 15: Pointers, part 1 Part 16: Declaring Global Variables Properly Part 17: Better Type Checking and Pointer Offsets Part 18: Lvalues and Rvalues Revisited Part 19: Arrays, part 1 Part 20: Character and String Literals Part 21: More Operators Part 22: Design Ideas for Local Variables and Function Calls Part 23: Local Variables Part 24: Function Parameters Part 25: Function Calls and Arguments Part 26: Function Prototypes Part 27: Regression Testing and a Nice Surprise Part 28: Adding More Run-time Flags Part 29: A Bit of Refactoring Part 30: Designing Structs, Unions and Enums Part 31: Implementing Structs, Part 1 Part 32: Accessing Members in a Struct Part 33: Implementing Unions and Member Access Part 34: Enums and Typedefs Part 35: The C Pre-Processor Part 36: break and continue Part 37: Switch Statements Part 38: Dangling Else and More Part 39: Variable Initialisation, part 1 Part 40: Global Variable Initialisation Part 41: Local Variable Initialisation Part 42: Type Casting and NULL Part 43: Bugfixes and More Operators Part 44: Constant Folding Part 45: Global Variable Declarations, revisited Part 46: Void Function Parameters and Scanning Changes Part 47: A Subset of sizeof Part 48: A Subset of static Part 49: The Ternary Operator Part 50: Mopping Up, part 1 Part 51: Arrays, part 2 Part 52: Pointers, part 2 Part 53: Mopping Up, part 2 Part 54: Spilling Registers Part 55: Lazy Evaluation Part 56: Local Arrays Part 57: Mopping Up, part 3 Part 58: Fixing Pointer Increments/Decrements Part 59: Why Doesn't It Work, part 1 Part 60: Passing the Triple Test Part 61: What's Next? Part 62: Code Cleanup Part 63: A New Backend using QBE Part 64: A Backend for the 6809 CPU

I've stopped work on acwj and now I'm writing a new language called alic from scratch. Check it out!

Copyrights I have borrowed some of the code, and lots of ideas, from the SubC compiler written by Nils M Holm. His code is in the public domain. I think that my code is substantially different enough that I can apply a different license to my code. Unless otherwise noted, all source code and scripts are (c) Warren Toomey under the GPL3 license. all non-source code documents (e.g. English documents, image files) are (c) Warren Toomey under the Creative Commons BY-NC-SA 4.0 license.

Explore the repository to follow along with this comprehensive compiler-building journey.