2012/9/16 haael <haael@interia.pl>:

OK, I read almost all the documentation I found on the web page. But I still don't understand few things.

There are 3 layers in the whole picture. The user application written in Python, the Python interpreter written in RPython and the RPython interpreter itself.

1. Where do flow graphs are generated from? Is it the representation of the user application, or the interpreter?

The interpreter.

2. Where does the JIT fit here? I read it traces the execution of the iterpreter and indirectly the user application. Does it operate on the flow graphs or something else?

It operates on a serialized version of the flowgraphs.

3. Which component actually does the JIT? Is it just a tweak on the code generator or are the flow graphs generated differently?

The flow graphs are taken from the translator and modified by the JIT generator.

4. Is there some documentation how to write a backend (code generator)? The source code is poorly documented and the topic is not mentioned on the web page. What exactly do I need to implement to have a backend?

You mean a JIT backend or a RPython backend? You might find this useful: http://www.aosabook.org/en/pypy.html -- Regards, Benjamin