Who needs Graphviz when you can build it yourself?

SpiderMonkey's team built a custom graph layout algorithm for visualizing compiler optimizations, replacing Graphviz with a simpler approach tailored to control flow graphs. The new tool produces stable, readable layouts in milliseconds instead of minutes by leveraging domain knowledge about reducible control flow and loop structures. The algorithm uses a modified Sugiyama approach with five steps: layering blocks by depth, creating dummy nodes for multi-layer edges, straightening edges through iterative passes, tracking horizontal edge placement, and assigning vertical positions. This human-centric design philosophy prioritizes predictability and readability over mathematical optimization, resulting in faster performance and more intuitive visualizations of JavaScript and WebAssembly compilation.