Skip to main content

Phase 6 Self-Hosted Compiler

Phase 6 is the real self-hosting effort. The C++ compiler remains the trusted stage0 builder and oracle while the Hydrogen-written compiler grows toward a complete stage1 compiler.

Current Foundation​

The Phase 6 workspace lives at samples/self_hosting in the compiler repo. It now includes:

  • Hydrogen.Compiler.Binding for the first Hydrogen-owned checker path.
  • Hydrogen.Compiler.IR for the first compiler IR object model.
  • Hydrogen.Compiler.RuntimeModel for the native runtime contract surface.
  • Hydrogen.Compiler.CodeGen.X64 for direct Linux x64 ELF byte writing.
  • Hydrogen.Compiler.Cli with tokens, parse, check, compile, and a reserved stage-compare interface.

The native backend is intentionally tiny today. It recognizes a System.Console.WriteLine("...") proof program, lowers it to a small IR object, and writes a Linux x64 ELF executable directly from Hydrogen code. It does not emit C and does not call a C compiler, assembler, or linker.

Commands​

./build/hy run samples/self_hosting/Hydrogen.Compiler.Cli/Hydrogen.Compiler.Cli.hyproj -- check tests/phase6/native_hello.hy
./build/hy run samples/self_hosting/Hydrogen.Compiler.Cli/Hydrogen.Compiler.Cli.hyproj -- compile tests/phase6/native_hello.hy -o build/native_hello
chmod +x build/native_hello
./build/native_hello

The generated executable prints:

Hydrogen native hello

Still To Do​

Phase 6 is complete only when Hydrogen can compile itself. The remaining work includes:

  • broad binding and type checking
  • a managed runtime clone for strings, arrays, classes, static fields, calls, and file IO
  • native codegen for compiler-shaped programs
  • stage0 building stage1
  • stage1 building stage2
  • stage1/stage2 diagnostics and runtime behavior matching on a shared corpus

The bootstrap compiler should remain in-tree as the historical seed and fallback after promotion.