Fuzzing the .NET JIT Compiler

But before we dive into ‘Fuzzlyn’ and what it does, we’re going to take a quick look at ‘compilation’ in the .NET Framework. When you write C#/VB.NET/F# code (delete as appropriate) and compile it, the compiler converts it into Intermediate Language (IL) code. The IL is then stored in a .exe or .dll, which the Common Language Runtime (CLR) reads and executes when your program is actually run. However it’s the job of the Just-in-Time (JIT) Compiler to convert the IL code into machine code.