mitscriptc - A JIT compiler for mitscript

mitscriptc is a just-in-time compiler and runtime for executing mitscript programs.

It was developed as a course project for MIT course 6.818 in the fall of 2021 by Georgijs Vilums and Jakob Nogler.

mitscript

The mitscript language is in many ways similar to Python and JavaScript. It supports the following features, among others:

• Dynamic typing, with integers, strings, booleans and objects as fundamental types.
• Functions and closures that can capture their environment.
• Automatic memory management through garbage collection.

See the following example program:

Point = fun(x, y){
    this = {
        x: x;
        y: y;
        print: fun() {
            print("Point(" + this.x + ", " + this.y + ")");
        };
        add: fun(other) {
            return Point(this.x + other.x, this.y + other.y);
        }; 
    };
    return this;
};

p1 = Point(5,5);

// prints Point(5, 5)
p1.print();

p2 = Point(3, 2);
p3 = p1.add(p2);

// prints Point(8, 7)
p3.print();

Building and Running

Build mitscriptc (CMake and a C++ compiler are required)

mkdir build
cd build
cmake .. -DCMAKE_BUILD_TYPE=Release
make -j`nproc`

Run the game of life benchmark program:

./build/mitscriptc ./test/bench/life.mit < ./test/bench/life.mit.input

Or more generally:

mitscriptc <program.mit>

Internals

The following is a brief overview of the different moving parts in the compiler and virtual machine:

• The first step of the execution process is to translate an mitscript program into a high level intermediate representation in static single assignment form, such that it becomes suitable for further processing.
• Various optimizations such as constant propagation and type analysis are performed to specialize instructions, improving performance.
• Next, register allocation is performed to map the intermediate representation from virtual registers to machine registers.
• The intermediate representation with machine registers is translated into x86-64 assembly.
• Arguments are initialized and control is transfered to the generated code.
• The runtime system performs garbage collection and handles any I/O.

More detailed information can be found in the writeup.