Systems & CLI · Pro
Write a C Compiler
Build a compiler that lexes and parses a growing subset of C and emits real x86-64 assembly, stage by stage, until it compiles non-trivial programs.
You write a C compiler that takes source text, tokenizes it, parses it into an abstract syntax tree, and generates x86-64 assembly that the system assembler and linker turn into a runnable binary. Following an incremental test-driven plan, you start with a program that just returns an integer and grow the supported language stage by stage to unary and binary operators, local variables, control flow, functions, and pointers. It is worth building because code generation is where most developers' mental model goes blank, and producing working assembly proves you understand calling conventions, the stack frame, and register allocation at a level interviewers rarely see. It is resume-defining because each stage ships against a real test suite, so you can demonstrate a compiler that actually emits binaries rather than a toy that only prints tokens.
What you build
- Lexer that turns C source into a typed token stream
- Recursive-descent parser producing an abstract syntax tree
- x86-64 assembly code generation with correct stack frames
- Support for unary, binary, and short-circuit logical operators
- Local variables, scoping, and the System V calling convention
- Control flow including if/else, loops, and function calls
- Passes an external staged test suite at each milestone
What it teaches
- Lexing and recursive-descent parsing
- Abstract syntax tree design
- x86-64 assembly and the System V calling convention
- Stack frame layout and local variable storage
- Incremental, test-driven compiler construction
- Assembling and linking with the system toolchain
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Take it further
- Add a simple register allocator instead of always spilling to the stack.
- Implement basic constant folding and dead-code elimination.
- Support pointers, arrays, and struct types.
