The Common Language Infrastructure (CLI) is a virtual machine expressly designed for implementing statically typed languages such as C#, therefore programs written in dynamically typed languages are typically much slower than C# when executed on .NET.
Recent developments show that Just In Time (JIT) compilers can exploit runtime type information to generate quite efficient code. Unfortunately, writing a JIT compiler is far from being simple.
In this paper we report our positive experience with automatic generation of JIT compilers as supported by the PyPy infrastructure, by focusing on JIT compilation for .NET. Following this approach, we have in fact added a second layer of JIT compilation, by allowing dynamic generation of more efficient .NET bytecode, which in turn can be compiled to machine code by the .NET JIT compiler.
The main and novel contribution of this paper is to show that this two-layers JIT technique is effective, since programs written in dynamic languages can run on .NET as fast as (and in some cases even faster than) the equivalent C# programs.
The practicality of the approach is demonstrated by showing some promising experiments done with benchmarks written in a simple dynamic language.