New graph layout algorithm for SpiderMonkey's SSA compiler

6 months ago

SpiderMonkey's optimizing compiler, Ion, now features interactive graphs for visualizing JavaScript and WebAssembly compilation.
Users can write JavaScript code in a test function to generate and interact with these graphs, including navigation, zooming, and scrubbing through the optimization process.
The new layout algorithm is simple, fast, and produces high-quality output, tailored specifically for SpiderMonkey's needs, implemented in less than a thousand lines of code.
Traditional tools like Graphviz produce unstable and counterintuitive layouts, making it difficult to follow the structure of the source code.
The new algorithm avoids complex optimizations, focusing instead on stability and readability, with specific steps like layering, creating dummy nodes, straightening edges, and tracking horizontal edges.
The resulting graphs are more efficient and easier to navigate, even for complex functions, with rendering inspired by railroad diagrams for clarity.
Future work includes integrating iongraph more deeply into Firefox and adding features like search and register allocation visualization, though there's no fixed roadmap.
The source code for iongraph is available on GitHub, and contributions are welcome.

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