sgaliamov

Int32 Foo(Int32)
          1: .ldarg.0         | 1 # we can see resulting the stack size
          2: .ldc.i4.2        | 2
          4: .ceq             | 1
          9: .brfalse Label_0 | 0 # we can see where the branching instruction is pointing
         10: .ldc.i4.1        | 1
         15: .br Label_1      | 0
    Label_0:                      # named label
         16: .ldarg.0         | 1
         17: .ldc.i4.3        | 2

sgaliamov

using static CustomExtensions.Functions;
...
var foo = new DynamicMethod("Foo", typeof(int), new[] { typeof(int) })
    .GetILGenerator()
    .UseIlluminator(
        enableTraceLogger: true,             // enable tracing (optional)
        Ret(If(Ceq(Ldarg_0(), Ldc_I4_2()),   // condition
               Ldc_I4_1(),                   // then
               Add(Ldarg_0(), Ldc_I4_3())))) // else
    .CreateDelegate<Func<int, int>>();

sgaliamov

if (condition()) {
    then();
} else {
    otherwise();
}

sgaliamov

namespace CustomExtensions
{
    public static class Functions
    {
        public static ILEmitterFunc If(
            ILEmitterFunc condition,
            ILEmitterFunc then,
            ILEmitterFunc @else) => (in ILEmitter il) =>
            il.Brfalse(condition, out var otherwise)
              .Emit(then)

sgaliamov

public static ILEmitter Beq_S(
    this ILEmitter self,
    in ILEmitterFunc func1,
    in ILEmitterFunc func2,
    in Label label) {
    func1(self);
    func2(self);
    return self.Beq_S(label);
}
...

sgaliamov

public ILEmitter Beq_S(in Label label) {
    ValidateJump(label);                // can validate that short version of a jump instruction is used correctly.
    _il.Emit(OpCodes.Beq_S, label);     // pass the right parameter that the instruction needs.
    _logger?.Log(OpCodes.Beq_S, label); // embed the logger into each method.
    return this;
}

sgaliamov

public static ILEmitter Add(this ILEmitter self, in ILEmitterFunc func1, in ILEmitterFunc func2) {
    func1(self);
    func2(self);
    return self.Add(); // and this finally does the real generator.Emit(OpCodes.Add);
}

sgaliamov

public delegate ILEmitter ILEmitterFunc(in ILEmitter emitter);
...
public static ILEmitterFunc Add(ILEmitterFunc func1, ILEmitterFunc func2) =>
    (in ILEmitter il) => il.Add(func1, func2);

sgaliamov

using static Illuminator.Functions;
...
il.Brfalse_S(Ceq(Ldarg_0(), Ldc_I4_2()), out var label)  // if (value == 2) {
  .Ret(Ldc_I4_1())                                       //   return 1;
  .MarkLabel(label)                                      // }
  .Ret(Add(Ldarg_0(), Ldc_I4_3()));                      // return value + 3;

sgaliamov

var method = new DynamicMethod("Foo", typeof(int), new[] { typeof(int) });
var generator = method.GetILGenerator();
var label = generator.DefineLabel();
var il = generator.UseIlluminator(); // Creates wrapper
il.Ldarg_0()
  .Ldc_I4_2()
  .Ceq()
  .Brfalse_S(label) // if (value == 2)
  .Ldc_I4_1()
  .Ret()            // return 1