C# 6.0 Program and IL (Null-Conditional Operators in C# 6.0 blog post)

1. Program.cs

namespace CS6
{
    class Program
    {
        static void Main(string[] args)
        {
            var car = new Car();
            int currentSpeed = GetCurrentSpeed(car);
        }

        private static int GetCurrentSpeed(Car car)
        {
            return car?.Engine?.ControlUnit?.CurrentSpeed ?? 0;
        }
    }
}

2. IL.cs

// Type: CS6.Program 
// Assembly: CS6, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null
// MVID: 4AB19F9C-A2C4-4C0B-93BF-64E92E91575A
// Location: D:\study\b-12\CS6\CS6\bin\Debug\CS6.exe
// Sequence point data from D:\study\b-12\CS6\CS6\bin\Debug\CS6.pdb

.class private auto ansi beforefieldinit 
  CS6.Program
    extends [mscorlib]System.Object
{

  .method private hidebysig static void 
    Main(
      string[] args
    ) cil managed 
  {
    .entrypoint
    .maxstack 1
    .locals init (
      [0] class CS6.Car car,
      [1] int32 currentSpeed
    )

    // [6 9 - 6 10]
    IL_0000: nop          

    // [7 13 - 7 33]
    IL_0001: newobj       instance void CS6.Car::.ctor()
    IL_0006: stloc.0      // car

    // [8 13 - 8 53]
    IL_0007: ldloc.0      // car
    IL_0008: call         int32 CS6.Program::GetCurrentSpeed(class CS6.Car)
    IL_000d: stloc.1      // currentSpeed

    // [9 9 - 9 10]
    IL_000e: ret          

  } // end of method Program::Main

  .method private hidebysig static int32 
    GetCurrentSpeed(
      class CS6.Car car
    ) cil managed 
  {
    .maxstack 2
    .locals init (
      [0] valuetype [mscorlib]System.Nullable`1<int32> V_0,
      [1] valuetype [mscorlib]System.Nullable`1<int32> V_1,
      [2] int32 V_2
    )

    // [12 9 - 12 10]
    IL_0000: nop          

    // [13 13 - 13 64]
    IL_0001: ldarg.0      // car
    IL_0002: brtrue.s     IL_000f
    IL_0004: ldloca.s     V_1
    IL_0006: initobj      valuetype [mscorlib]System.Nullable`1<int32>
    IL_000c: ldloc.1      // V_1
    IL_000d: br.s         IL_0042
    IL_000f: ldarg.0      // car
    IL_0010: call         instance class CS6.Engine CS6.Car::get_Engine()
    IL_0015: dup          
    IL_0016: brtrue.s     IL_0024
    IL_0018: pop          
    IL_0019: ldloca.s     V_1
    IL_001b: initobj      valuetype [mscorlib]System.Nullable`1<int32>
    IL_0021: ldloc.1      // V_1
    IL_0022: br.s         IL_0042
    IL_0024: call         instance class CS6.ControlUnit CS6.Engine::get_ControlUnit()
    IL_0029: dup          
    IL_002a: brtrue.s     IL_0038
    IL_002c: pop          
    IL_002d: ldloca.s     V_1
    IL_002f: initobj      valuetype [mscorlib]System.Nullable`1<int32>
    IL_0035: ldloc.1      // V_1
    IL_0036: br.s         IL_0042
    IL_0038: call         instance int32 CS6.ControlUnit::get_CurrentSpeed()
    IL_003d: newobj       instance void valuetype [mscorlib]System.Nullable`1<int32>::.ctor(!0/*int32*/)
    IL_0042: stloc.0      // V_0
    IL_0043: ldloca.s     V_0
    IL_0045: call         instance bool valuetype [mscorlib]System.Nullable`1<int32>::get_HasValue()
    IL_004a: brtrue.s     IL_004f
    IL_004c: ldc.i4.0     
    IL_004d: br.s         IL_0056
    IL_004f: ldloca.s     V_0
    IL_0051: call         instance !0/*int32*/ valuetype [mscorlib]System.Nullable`1<int32>::GetValueOrDefault()
    IL_0056: stloc.2      // V_2
    IL_0057: br.s         IL_0059

    // [14 9 - 14 10]
    IL_0059: ldloc.2      // V_2
    IL_005a: ret          

  } // end of method Program::GetCurrentSpeed

  .method public hidebysig specialname rtspecialname instance void 
    .ctor() cil managed 
  {
    .maxstack 8

    IL_0000: ldarg.0      // this
    IL_0001: call         instance void [mscorlib]System.Object::.ctor()
    IL_0006: nop          
    IL_0007: ret          

  } // end of method Program::.ctor
} // end of class CS6.Program