c# event事件编译后变成了什么？

源码：

        public delegate void wt();

        public void f1()

        {

            MessageBox.Show("a");

        }

        public event wt sj;

        public Form1()

        {

            InitializeComponent();

            sj+=new wt(f1);

            sj();

        }

或写成

            sj+=new wt(f1);

            sj.Invoke();

编译后：

        public delegate void wt();

        public void f1()

        {

            MessageBox.Show("a");

        }
        private wt sj;

        public event wt sj

        {

            add

            {

                wt wt2;

                wt sj = this.sj;

                do

                {

                    wt2 = sj;

                    wt wt3 = (wt) Delegate.Combine(wt2, value);

                    sj = Interlocked.CompareExchange<wt>(ref this.sj, wt3, wt2);

                }

                while (sj != wt2);

            }

            remove

            {

                wt wt2;

                wt sj = this.sj;

                do

                {

                    wt2 = sj;

                    wt wt3 = (wt) Delegate.Remove(wt2, value);

                    sj = Interlocked.CompareExchange<wt>(ref this.sj, wt3, wt2);

                }

                while (sj != wt2);

            }

        }

        public Form1()

        {

            this.InitializeComponent();

            this.sj += new wt(this.f1);

            this.sj();

        }