Implement a Self-Hosting JIT

JIT Compiling the JIT

Self-hosting JITs compile their own optimizing tiers to native code. LuaJIT's FFI and HotSpot's C2 eventually run as generated machine code. The bootstrap compiles a minimal compiler, then uses it to compile the full compiler for speed.

Bootstrap Pattern

Stage 0: C interpreter. Stage 1: minimal JIT enough to compile stage 2. Stage 2: full optimizer emits code for itself and user programs.

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• Fixed point: compiler compiles itself correctly
• Test output against interpreter reference
• Metacircular execution proves correctness
• Build time increases during bootstrap

Connecting to real compilers

Production compilers embed this step inside a longer pipeline. GCC flows through cpp, cc1, assembly, and ld; Clang uses the driver, Sema, LLVM IR passes, and a target backend. LLVM bitcode, JVM bytecode, and WASM are other familiar IRs at the same layer. The exercise isolates one pass so you can test it alone before chaining it to the next stage.

Why for this exercise

You will implement a self-hosting JIT that compiles its own compiler logic. This exercise requires bootstrapping from a minimal emitter to a JIT that generates native code for compiler functions themselves.