Debugging WASM in Chrome DevTools

When I was working on the WASM backend for my Scheme compiler, I ran into several tricky situations with debugging generated WASM code. It turned out that Chrome has a very capable WASM debugger in its DevTools, so in this brief post I want to share how it can be used. The setup and harness I'll be using an example from my wasm-wat-samples project for this post. In fact, everything is already in place in the gc-print-scheme-pairs sample. This sample shows how to construct Scheme-like s-exprs in WASM using gc references and print them out recursively. The sample supports nested pairs of integers, booleans and symbols. To see this in action, we have to first compile the WAT file to WASM, for example using watgo: $ cd gc-print-scheme-pairs $ watgo parse gc-print-scheme-pairs.wat -o gc-print-scheme-pairs.wasm The browser-loader.html file in that directory already expects to load gc-print-scheme-pairs.wasm. But we can't just open it directly from the file-system; since it loads WASM, this…