cc2

Tiny C Compiler (subset of C17).

Warning

This project is experimental and not intended for production use.

Note

Currently only emits gas_x86-64_linux assembly. Other backends may be added in the future.

Language Features Supported

Types

• int

Functions

• Function definitions and declarations (supports types listed above)
• int main(void) { ... }

Declarations

• Local variables
• Global variables
• Lexical block scoping
• Shadowing
• Internal and external linkage (extern and static)
• Static/automatic storage duration (local/file-scope variables and static locals)

Statements

• return
• Expression statements
• if / else
• goto/labeled statements
• Compound statements ({ ... })
• for / do / while
• break / continue
• switch
• default / case labels
• Empty statements (;)

Expressions

• Integer constants
• Variables
• Unary operators: -, !, ~, ++ (postfix and prefix), -- (postfix and prefix)
• Binary operators: +, -, *, /, %
• Binary bitwise operators: &, |, ^
• Binary shift operators: <<, >>
• Binary logical operators: &&, ||
• Comparison operators: <, <=, >, >=, ==, !=
• Assignment operators: =, +=, -=, *=, /=, %=, &=, |=, ^=, <<=, >>=
• Conditional (ternary) operator: ? :
• Function calls

Optimizations

• Constant Folding
• Unreachable Code Elimination
• Copy Propagation
• Dead Store Elimination
• Register Allocation
• Register Coalescing

Testing

Compiler is tested using an external test suite: nlsandler/writing-a-c-compiler-tests/.

Quick Start

Clone the repository and build the project:

git clone https://github.com/hmunye/cc2.git
cd cc2
cargo build --release

Display help and available flags:

./target/release/cc2 --help

Optionally, install globally:

cargo install --path .
cc2 --help

Example: hello_world.c

# 1. Preprocess separately using `GCC` or `cpp`:
gcc -E hello_world.c -o hello_world.i
# or
cpp hello_world.c -o hello_world.i

# 2. Compile the preprocessed file to assembly:
./target/release/cc2 hello_world.i

# 3a. Use `GCC` to assemble and link to an executable:
gcc hello_world.s -o hello_world

# 3b. Or manually invoke assembler and linker:
as hello_world.s -o hello_world.o   # assemble to object file
ld hello_world.o -o hello_world     # link to produce executable

# -----------------------------
# Shortcut: Use the -p flag
# -----------------------------
#
# The `-p` flag preprocesses and compiles in a single step.
# This is just a convenience; no separate preprocessed file is needed.
./target/release/cc2 -p hello_world.c

# Assemble and link as usual:
gcc hello_world.s -o hello_world

License

This project is licensed under the MIT License.

References

• Writing a C Compiler
• C17 Standard Draft
• System V x86-64 ABI
• Intel x86-64 ISA