Getting Started

Build LCCC, compile a C program, and run the benchmark suite in under five minutes.

Prerequisites

Requirement	Notes
Rust stable (2021 edition)	Install via rustup
POSIX host	Compiler emits Linux ELF; developed on Linux and macOS
GCC installed	Needed for built-in headers (`stddef.h`, `stdarg.h`)
Python 3.9+	For the test/benchmark runners (optional)

LCCC uses a completely standalone assembler and linker — no external toolchain is needed at compile time, only for the GCC built-in headers at C preprocessing time.

Clone and Build

git clone https://github.com/levkropp/lccc.git
cd lccc
cargo build --release

This produces five binaries in target/release/:

Binary	Target architecture
`lccc`	picked by host / argv[0] name
`lccc-x86`	x86-64
`lccc-arm`	AArch64
`lccc-riscv`	RISC-V 64
`lccc-i686`	i686 (32-bit x86)

Note: The compiler also picks its target from the argv[0] name — symlinking the binary to aarch64-linux-gnu-cc (or similar) selects that target, which is how the benchmark suite drives cross-compilation.

Compile Your First Program

# LCCC needs GCC's built-in headers for stddef.h, stdarg.h, etc.
GCC_INC="-I$(gcc -print-file-name=include)"

cat > hello.c <<'EOF'
#include <stdio.h>
int main(void) {
    printf("Hello from LCCC!\n");
    return 0;
}
EOF

./target/release/lccc $GCC_INC -O2 -o hello hello.c
./hello
# Hello from LCCC!

GCC-Compatible Flags

LCCC accepts the standard GCC command-line interface:

# Compile and link
lccc -O2 -o output input.c

# Emit assembly
lccc -S -O2 input.c

# Compile to object file only
lccc -c input.c

# Preprocessor only
lccc -E input.c

# Debug info
lccc -g -O2 -o output input.c

# Macros and include paths
lccc -DFOO=1 -Iinclude/ input.c

# Cross-compile
lccc-arm   -O2 -o output-arm   input.c   # AArch64
lccc-riscv -O2 -o output-riscv input.c   # RISC-V 64

Unrecognized flags (architecture-specific -m flags, unknown -f flags) are silently ignored, so LCCC works as a drop-in in most build systems.

Use as a Make `CC`

make CC=/path/to/lccc/target/release/lccc CFLAGS="$GCC_INC -O2"

Run the Test Suites

# Unit tests (563 pass)
cargo test --release

# 18-benchmark suite (performance + correctness + size)
python3 tests/benchmark/run_benchmarks.py --reps 5

# 50-program correctness suite (vs GCC output)
python3 tests/correctness/run_correctness.py

# Progressive feature tests (levels 1–8)
python3 tests/integration/test_progressive.py

The unit suite runs optimizer passes, IR lowering, register allocation, and assemblers on synthetic inputs. The Python suites compile and execute real C programs and compare output against GCC.