I had an interesting time writing a JIT for Piet some time ago. Piet is a pretty weird language in a few non-obvious ways. From what I remember: * Execution mo

I had an interesting time writing a JIT for Piet some time ago. Piet is a pretty weird language in a few non-obvious ways. From what I remember: * Execution moves between blocks of colour. Flood fill algorithms are a valid compiler optimisation! * Execution can move left/right/up/down. You can't necessarily tell what will be executed without doing it. The 'codel chooser' stuff means you can exit a colour block in two different ways depending on program state (plus left/right/up/down, so 8 ways total...). * Instructions are encoded in the difference between colour blocks. * Piet is otherwise a fairly straightforward stack machine.