.. include:: <s5defs.txt>

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PyPy Translation - Architecture
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:Date: 4th July  2006
:Location: Geneva, CERN

PyPy/Translation architecture
============================= 

- bytecode interpreter 
- Abstract Interpretation (Flow Object Space)
- Type Inference (Annotation)
- Specialising to lltypesystem / ootypesystem 
- C and LLVM Backends to lltypesystem 

PyPy/Translation overview
=========================

- diagram & demo

Abstract Interpretation
========================

- bytecode interpreter dispatches to Flow Object Space
- Flow Object Space implements abstract operations
- produces flow graphs as a side effect
- starts from "live" byte code NOT source code

Type Inference 
===============

- performs forward propagating type inference
- is used to infer the types in flow graphs
- needs types of the entry point function's arguments
- assumes that the used types are static
- goes from very special to more general values

RTyping
===========================

- annotated flow graphs are specialized for language families
- choose runtime representations: express these with
  low-level type systems
- lltypesystem (for C like languages): C, LLVM
- ootypesystem (for OO languages): .NET CLI, Smalltal, (Java/Javascript...)
- result is specialized flow graphs
- these contain operations at target level

Translation Aspects
====================

- implementation decisions (GC, threading, CC) at translation time 
- most other language implementations do a "fixed" decision 
- translation aspects are weaved into the produced code
- independent from language semantics (python interpreter)


A Special Aspect: Just-in-time Compilation
===========================================

- transform interpreters into compilers
  (and just-in-time compilers)
- work in progress
- diagram & demo