Mijit

An experimental JIT compiler generator.

Mijit consists of the following components:

• A domain-specific language ("Mijit code") that is particularly amenable to optimising, and barely expressive enough for writing interpreters.
• A back-end that lowers Mijit code to machine code (in RAM) and executes it.
• A profile-guided optimizer that reads and writes Mijit code.

Use

Suppose you are writing a high-level programming language. It compiles to some kind of virtual code, which runs on an interpreter, written in C, say. You want it to go faster.

You write a Rust program that uses crate mijit. You implement trait Machine, porting the performance- critical parts of your interpreter to Mijit code. Mijit provides you with an equivalent JIT compiler. You wrap it in an ergonomic Rust API that is specific to your language. You write C bindings for your Rust API. You drop it in as a replacement for your interpreter, reusing the existing non-performance- critical parts.

Status

Early, unfinished. The specification of Mijit code is in flux. There is one example interpreter. It does not yet have C bindings. There is one back-end, for x86_64. Other 64-bit targets are planned, but the portable abstraction has not been designed yet. It can run some trivial programs, but the generated code is poor. The optimizer is still mostly a collection of ideas.

Building

$ ./compile

Running

Mijit is primarily a library. However, it does provide some executable tests.

$ cargo test $ LD_LIBRARY_PATH=target/debug ./main