A project called WATaBoy demonstrates that JIT-compiling Game Boy CPU instructions to WebAssembly can achieve faster performance than native interpreters. This approach leverages the web browser's existing JIT infrastructure for WebAssembly. This is significant because it shows a novel way to overcome platform restrictions (e.g., iOS blocking JIT) by using WebAssembly as a portable, high-performance target. It could enable smoother emulation on constrained platforms and inspire similar approaches for other retro systems. The project notes that while native interpreters can have roughly 1000% overhead, WebAssembly JIT overhead is around 20%, making the JIT approach faster. However, Firefox was observed to be 25% slower than Chrome/Safari for this workload.
Background
JIT (Just-In-Time) compilation translates code at runtime to native machine code for performance. WebAssembly (WASM) is a low-level binary format designed for near-native speed in web browsers. Traditionally, Game Boy emulators use interpreters or native JIT, but these may not be allowed on some platforms like iOS due to security restrictions. WATaBoy instead generates WASM from Game Boy instructions and relies on the browser's WASM JIT engine.
References
Discussion
Commenters praised the project as impressive undergraduate work and noted the cleverness of using web browser JIT to circumvent iOS restrictions. One pointed out that Firefox's WASM JIT is slower than Chrome/Safari. Another observed that beating a native interpreter is expected given overhead differences, but having a Game Boy JIT runtime in WASM is still cool.