Beyond Relooper: recursive translation of unstructured control flow to structured control flow (functional pearl)

In many compilers, control flow is represented using an arbitrary directed graph. But in some interesting target languages, including JavaScript and WebAssembly, intraprocedural can be expressed only structured ways, loops, conditionals, multilevel breaks or exits. As was shown by Peterson, Kasami, Tokura 1973, such obtained translating flow. The translation uses two standard analyses, but as published, it takes three passes—which may explain why overlooked Emscripten, a popular compiler from C to JavaScript. By tweaking the analyses applying fundamental ideas functional programming (recursive functions immutable abstract-syntax trees), translation, along with couple of code improvements, implemented single pass. This new implementation slated added Glasgow Haskell Compiler. Its single-pass its representation, use dominator trees make much easier reason about than original translation.