The Four Phases of Compilation

First, what is meant by the term "compilation" depends on the selected injection strategy.

For bytecode rewriting, compilation means generating a new instrumented variation of the application's bytecode.

For direct engine support, compilation means compiling the .mm script to a new Wasm module that interfaces with an engine to instrument the program dynamically. The original program is not touched and not provided when using this strategy.

The first three phases of whamm! compilation are identical for both strategies. The translate and emit phases vary between injection strategy. This is because "emitting" for bytecode rewriting means using the orcs library to insert new instructions into the program. Whereas "emitting" for direct engine support means emitting a Wasm module encoding where to instrument and the callbacks to attach at the probed sites by interfacing with the engine at application runtime.

These are the four phases of compilation:

1. Parse
2. Configure the Whamm! Core Library (if needed)
3. Verify
4. Translate AST into the injection strategy's representation
5. Emit