rcc

A minimal C compiler written in C, targeting x64 assembly. This project follows the structure of Nora Sandler's "Writing a C Compiler" book.

Currently, the compiler has been implemented up to Chapter 2 (Unary Operators).

Features

• Basic function structure (int main(void))
• Integer return values
• Unary operators: - (negation) and ~ (bitwise complement)
• Nested expressions (e.g., return ~(-(~2));)
• Automatic assembly and linking via gcc

Pipeline

The compiler translates C code into an executable through four distinct stages:

1. Lexical Analysis (lexer.c): Reads the source file and converts it into a stream of tokens.
2. Parsing (parser.c): A recursive descent parser that validates the grammar and builds an Abstract Syntax Tree (AST).
3. TACKY IR Generation (tacker.c): Flattens the nested AST into Three-Address Code (TACKY), a linear intermediate representation that introduces temporary variables for complex expressions.
4. Code Generation (codegen.c):
   • Maps TACKY instructions to an Assembly AST.
   • Allocates stack memory for temporary variables.
   • Fixes illegal x64 instructions (e.g., routing memory-to-memory moves through the %r10d scratch register).
   • Emits the final AT&T syntax assembly to assembly.s.

Usage

Build the compiler:

make

Run the compiler on a C file:

./build/rcc return.c

The compiler will generate an assembly.s file and automatically call gcc to build the final executable (out_program).

To test the compiled program's output (which returns via the exit code):

./out_program
echo $?

(Note: Linux exit codes wrap at 256, so return -4 will print as 252)