Land ahoy: leaving the Sea of Nodes

V8’s end-tier optimizing compiler, Turbofan, is famously one of the few large-scale production compilers to use Sea of Nodes (SoN). However, since almost 3 years ago, we’ve started to get rid of Sea of Nodes and fall back to a more traditional Control-Flow Graph (CFG) Intermediate Representation (IR), which we named Turboshaft. By now, the whole JavaScript backend of Turbofan uses Turboshaft instead, and WebAssembly uses Turboshaft throughout its whole pipeline. Two parts of Turbofan still use some Sea of Nodes: the builtin pipeline, which we’re slowly replacing by Turboshaft, and the frontend of the JavaScript pipeline, which we’re replacing by Maglev, another CFG-based IR. This blog post explains the reasons that led us to move away from Sea of Nodes. The birth of Turbofan and Sea of Nodes # 12 years ago, in 2013, V8 had a single optimizing compiler: Crankshaft . It was using a Control-Flow Graph based Intermediate Representation. The initial version of Crankshaft provided significan