Viewing the IL code generated from a compiled expression

c# expression-trees il .net-reflector
Amy picture Amy · Jan 21, 2011 · Viewed 10.2k times · Source

Is it possible to view the IL code generated when you call Compile() on an Expression tree? Consider this very simple example:

class Program
{
    public int Value { get; set; }

    static void Main(string[] args)
    {
        var param = Expression.Parameter(typeof(Program));
        var con = Expression.Constant(5);
        var prop = Expression.Property(param, typeof(Program).GetProperty("Value"));
        var assign = Expression.Assign(prop, con);
        Action<Program> lambda = Expression.Lambda<Action<Program>>(assign, param).Compile();

        Program p = new Program();
        lambda(p);



        //p.Value = 5;
    }
}

Now, the expression tree does what the last line of Main says. Compile the application, then open it in Reflector. You can see the IL code of p.Value = 5; that does the assignment. But the expression tree was made and compiled at runtime. Is it possible to view the resulting IL code from the compile?

Answer

Eric Lippert picture Eric Lippert · Jan 21, 2011

Yes! Use this tool:

https://github.com/drewnoakes/il-visualizer

This was incredibly useful when I was implementing and debugging Compile, as I'm sure you can imagine.

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