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BUG playground

BUG is a minimal smart contract language designed for demonstrating and testing ethdebug/format. It compiles to EVM bytecode and produces rich debug information.

Use the interactive playground below to explore how BUG code compiles to intermediate representations and EVM bytecode.

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About BUG​

BUG is intentionally minimal—it provides just enough language features to demonstrate the debugging challenges that ethdebug/format addresses:

  • Storage variables with automatic slot allocation
  • Functions with parameters and return values
  • Control flow (if/else, while loops)
  • Basic types (uint256, bool, address, bytes32)
  • Complex types (arrays, mappings, structs)

Things to try​

  1. Edit the source code in the left panel and watch the outputs update. Try adding a new storage variable or changing a loop bound.
  2. Switch between views (AST, IR, CFG, Bytecode) to see how source code transforms through each compilation stage.
  3. Hover over instructions in the IR or Bytecode views to see which source code they correspond to.
  4. Inspect the Bytecode view to see ethdebug/format program annotations — each instruction shows its offset, operation, and context (source ranges, variables in scope).
  5. Look at the CFG to understand control flow structure — useful for seeing how if/while compiles to branching bytecode.

Compilation views​

The playground shows several stages of compilation:

  • AST — The abstract syntax tree after parsing
  • IR — The intermediate representation used for optimization
  • CFG — The control flow graph visualizing program structure
  • Bytecode — The final EVM bytecode with debug annotations