Stefan Marr

Runtime metaprogramming enables many useful applications and is widely used in frameworks, middleware, and domain-specific languages to simplify the task of application developers. However, today’s language implementations rarely optimize even common concepts such as reflective method invocation or dynamic proxies, despite the fact that solutions for efficient implementations have been advocated since decades.

In this presentation, we demonstrate how self-optimizing interpreters can be used to implement runtime metaprogramming efficiently. For the implementation, we use SOM Smalltalk, a little Smalltalk implemented in RPython (think PyPy) as well as Truffle (with Graal on top of the JVM). We show that both platforms can remove the runtime overhead of reflection and thus open up new opportunities for metaprogramming in performance critical scenarios.

This talk shows how languages can be implemented as self-optimizing interpreters, and how Truffle or RPython go about to just-in-time compile these interpreters to efficient native code.

Programming languages are never perfect, so people start building domain-specific languages to be able to solve their problems more easily. However, custom languages are often slow, or take enormous amounts of effort to be made fast by building custom compilers or virtual machines.

With the notion of self-optimizing interpreters, researchers proposed a way to implement languages easily and generate a JIT compiler from a simple interpreter. We explore the idea and experiment with it on top of RPython (of PyPy fame) with its meta-tracing JIT compiler, as well as Truffle, the JVM framework of Oracle Labs for self-optimizing interpreters.

In this talk, we show how a simple interpreter can reach the same order of magnitude of performance as the highly optimizing JVM for Java. We discuss the implementation on top of RPython as well as on top of Java with Truffle so that you can start right away, independent of whether you prefer the Python or JVM ecosystem.

While our own experiments focus on SOM, a little Smalltalk variant to keep things simple, other people have used this approach to improve peek performance of JRuby, or build languages such as JavaScript, R, and Python 3.

SOM (Simple Object Machine) Smalltalk has Truffle-based and RPython (PyPy) based implementations. It shows modern ways of language implementations with the goal of achieving high performance.