<p> <img src="logo.svg" width="160" alt="gabagool logo"> </p>

gabagool

A WebAssembly interpreter written from scratch. It also contains a time travel debugger.

This project aims to build a fully spec-compliant, performant interpreter whose entire execution state can be serialized, suspended, and restored. <br>

<details open> <summary>See demo</summary> <br> <img src="demo.gif" width="80%" alt="Game of Life demo"><br> <em>Each fork snapshots the entire WebAssembly execution state, spawns a brand new process, and resumes exactly where it left off.</em> <br> </details>

Status

gabagool is tested against the WebAssembly spec test suite. 1,960 tests pass out of 2,049 (96%). gabagool passes on arithmetic, control flow, memory, tables, globals, function references, imports/exports, and exceptions. Remaining tests involve supporting SIMD and garbage collection.

# run the core test suite
uv run download-core-tests.py
cargo t --features core-tests

# run the component test suite
# you need wasm-tools installed!
cd tests/components && bash fetch_components.sh
cargo t --features component-tests

# run an example wasm program
cargo r -- ./programs/stair_climb.wasm stair_climb 20

gabagool is not optimized and no serious profiling/benchmarking has been done. That said, the goal is to make it as performant as a pure interpreter can be. The most interesting direction is a translation phase that lowers WASM instructions into a compact intermediate representation, designed for efficient dispatch and serialization.

Reading

https://webassembly.github.io/spec/core/<br> https://github.com/bytecodealliance/wasmtime/issues/3017<br> https://github.com/bytecodealliance/wasmtime/issues/4002<br>

Wasm Component Model

https://www.infoq.com/podcasts/web-assembly-component-model/<br> https://blog.sunfishcode.online/what-is-a-wasm-component/<br> https://www.fermyon.com/blog/webassembly-component-model<br> https://github.com/WebAssembly/component-model/blob/main/design/mvp/Explainer.md<br> https://github.com/WebAssembly/component-model/blob/main/design/mvp/Binary.md<br> https://github.com/WebAssembly/component-model/blob/main/design/mvp/CanonicalABI.md<br>

Copy and patch compilation

https://fredrikbk.com/publications/copy-and-patch.pdf<br> https://www.youtube.com/watch?v=HxSHIpEQRjs<br>

Time travel debugging

https://awelonblue.wordpress.com/2013/01/24/exponential-decay-of-history-improved/<br>