I Built a Modern Compiler in Rust: Meet Lamina

Eira — Wed, 26 Nov 2025 02:49:38 +0000

Building a compiler is often seen as one of the "final bosses" of computer science. It's complex, requires deep knowledge of architecture, and usually involves wrestling with C++.

But what if we could build a simple, modern, modular compiler infrastructure using Rust?

Meet Lamina.

What is Lamina?

Lamina is a general-purpose compiler infrastructure that I've been building from scratch. Think of it as a lightweight, Rust-native alternative to LLVM. It takes a Readable Intermediate Representation (IR), optimizes it, and generates efficient machine code for multiple architectures.

I started this project to build a playground for experimenting with compiler optimizations and code-generation techniques.

Current Features

1. Multi-Target Support

Lamina is trying to support as many targets as possible(since I own a few machines with different arch and OS, it's mandatory) It currently supports code generation for:

AArch64 (Linux, macOS) - most stable
x86_64 (Linux, macOS, Windows) - close to working end-to-end
RISC-V (32-bit and 64-bit) - untested
WebAssembly (Wasm32/64) - codebase migration in progress

2. Modern IR & MIR

Lamina uses a dual-layer representation system:

Lamina Intermediate Representation: A high-level, readable intermediate representation similar to LLVM IR.
LUMIR (Lamina Unified Machine Intermediate Representation): A lower-level representation designed for machine-specific optimizations and register allocation.

3. Optimization Pipeline

The compiler includes a few experimental optimizations:

Constant Folding: Evaluating expressions at compile-time.
Dead Code Elimination: Removing unused instructions.
Strength Reduction: Replacing expensive operations with cheaper ones.
Function Inlining: Reducing call overhead.

Performance (Apple M1 8GB)

Best case scenario

Worst case scenario

Usages

Here's a simple example of Lamina IR code that calculates a factorial of 5

fn @factorial(i32 %n) -> i32 {
  entry:
    %cond = eq.i32 %n, 0
    br %cond, then, else

  then:
    ret.i32 1

  else:
    %sub = sub.i32 %n, 1
    %rec = call @factorial(%sub)
    %res = mul.i32 %n, %rec
    ret.i32 %res
}

fn @main() -> i32 {
  entry:
    %result = call @factorial(5)
    print %result
    ret.i32 0
}

or use an IR builder in Rust

fn create_factorial_function(builder: &mut IRBuilder) {
    builder
        .function_with_params(
            "factorial",
            vec![FunctionParameter {
                name: "n",
                ty: Type::Primitive(PrimitiveType::I32),
                annotations: vec![],
            }],
            Type::Primitive(PrimitiveType::I32),
        )
        // Entry block: check if n == 0
        .cmp(CmpOp::Eq, "cond", PrimitiveType::I32, var("n"), ir_i32(0))
        .branch(var("cond"), "factorial_then", "factorial_else");

    // Then block: return 1
    builder
        .block("factorial_then")
        .ret(Type::Primitive(PrimitiveType::I32), ir_i32(1));

    // Else block: recursive case
    builder
        .block("factorial_else")
        // Subtract 1 from n
        .binary(
            BinaryOp::Sub,
            "sub",
            PrimitiveType::I32,
            var("n"),
            ir_i32(1),
        )
        // Call factorial recursively
        .call(Some("rec"), "factorial", vec![var("sub")])
        // Multiply n by recursive result
        .binary(
            BinaryOp::Mul,
            "res",
            PrimitiveType::I32,
            var("n"),
            var("rec"),
        )
        // Return the result
        .ret(Type::Primitive(PrimitiveType::I32), var("res"));
}

You can compile this directly to an executable:

lamina  factorial.lamina
./factorial

or use the current experimental pipeline

soon become the default

lamina --emit-mir-asm factorial.lamina
./factorial

Status and Feedback

Lamina is still early and very much a work in progress, but it already:

Parses and lowers a custom IR
Runs a few basic optimization passes
Emits assembly/machine code for several architectures
Able to create simple compiler frontend awesome-lamina
- Brainfuck
- Umjunsik

If you’re into compilers, IR design, or codegen and want to poke at a Rust-native backend, I’d love feedback, issues, and nitpicks.

Let me know what you think in the comments below! Happy coding!

DEV Community: Eira