Hawk

A small Scheme VM and tracing JIT compiler.

Hawk targets Scheme with a compact runtime, bytecode compiler, tracing recorder, and native code backends. The project is written in C23 and Scheme

Overview

• Tracing JIT compiler implementing R7RS Scheme.
• Native code generation for x86_64 and aarch64.
• MIT licensed under the MIT License.
• Source on GitHub.

JIT

Hawk is an experimental tracing JIT, pushing tracing to its limits on a functional language. Much inspiration was taken from LuaJIT.

Hawk supports advanced tracing JIT features like:

• unboxing flonums to registers
• promoting globals to constants
• promoting closures to constants
• Splitting of polymorphic functions.
• lazy typechecking. Types are only checked when required.
• tracing of all scheme code, including call/cc.

As well as more standard compiler features, like:

• SSA form
• constant propagation
• CSE (constant subexpression elimination)
• DCE (dead code elimination)
• turning tailcalled functions back in to loops when appropriate