What are some good ways to get familiar with .Net's IL?

Question

I recently accepted a job where I will be working with the IL a lot(on the team of a certain obfuscator that's included with Visual Studio).

They know I have little knowlegde of it, so I'll have some time to learn it on the job. But, I want to get a bit of a jump start on it in the interim.

For my background, I've never wrote any IL and read very little of it. I do understand what it is though and such. I know x86 assembly and such as well, so I'm not dumb as far as assembly-type code goes.

But anyway, what are some good ways of getting familiar with IL and learning the usual opcodes and such and also how it's garbage collection and such magically works at an assembly level?

Answer 1

Start with a Book

The Microsoft Press book "Inside Microsoft .NET IL Assembler" is actually excellent reference point to start with. I have read it back 3 years ago, and it was quit a bit interesting. As you may know already, .NET Framework 3.X only adds new classes and functionality. Underlying technology is still the same. So the book still stands, at least until FW3.5.

Side to side to ECMA, and some hard work, you have everything you need.

There are also couple of good articles worth to mention:

• .NET Type Internals - From a Microsoft CLR Perspective
• Rewrite MSIL Code on the Fly with the .NET Framework Profiling API
• ECMA C# and Common Language Infrastructure Standards

Answer 2

Disassembling some example code seems like a prudent start. Generators (methods that yield) in particular make interesting structures.

Expression Trees, while not directly applicable are maybe a good example step between the language and IL.

Making your own little calculator language/compiler might be a useful example since you've presumably already done a little of that in x86 assembly.

Answer 3

Write some code and decompile it with freely available tools. Keep doing this for various high level C# constructs to see how it maps to IL and you're good to go.