JSIL Code Sample: Struct Copy Elimination

StructCopyElimination.cs

using System;

public static class Program {
    public static CustomType ReturnArgument (CustomType arg) {
        return arg;
    }

    public static void Main (string[] args) {
        var a = new CustomType(1);
        var b = new CustomType(2);
        var c = a + b;
        Console.WriteLine("a={0}, b={1}, c={2}", a, b, c);
        c = ReturnArgument(a + b);
        Console.WriteLine("a={0}, b={1}, c={2}", a, b, c);
        Console.WriteLine("{0}", a + c);
    }
}

public struct CustomType {
    public int Value;
  
    public CustomType (int value) {
        Value = value;
    }

    public static CustomType operator + (CustomType lhs, CustomType rhs) {
        return new CustomType(lhs.Value + rhs.Value);
    }
    
    public override string ToString () {
        return String.Format("{0}", Value);
    }
}

StructCopyElimination.js

JSIL.MakeStaticClass("Program", true, [], function ($) {

  $.Method({Static:true , Public:true }, "Main", 
    $sig.make(279443, null, [$jsilcore.TypeRef("System.Array", [$.String])], []), 
    function Program_Main (args) {
      var a = new $asm00.CustomType(), b = new $asm00.CustomType();
      $asm00.CustomType.prototype._ctor.call(a, 1);
      $asm00.CustomType.prototype._ctor.call(b, 2);
      var c = $asm00.CustomType.op_Addition(a, b);
      $asm01.System.Console.WriteLine("a={0}, b={1}, c={2}", a, b, c);
      c = $asm00.Program.ReturnArgument($asm00.CustomType.op_Addition(a, b));
      $asm01.System.Console.WriteLine("a={0}, b={1}, c={2}", a, b, c);
      $asm01.System.Console.WriteLine("{0}", $asm00.CustomType.op_Addition(a, c));
    }
  );

  $.Method({Static:true , Public:true }, "ReturnArgument", 
    $sig.make(279442, $asm00.TypeRef("CustomType"), [$asm00.TypeRef("CustomType")], []), 
    function Program_ReturnArgument (arg) {
      return arg;
    }
  );

});

JSIL.MakeStruct($asm01.TypeRef("System.ValueType"), "CustomType", true, [], function ($) {

  $.Method({Static:false, Public:true }, ".ctor", 
    $sig.make(279458, null, [$.Int32], []), 
    function CustomType__ctor (value) {
      this.Value = value;
    }
  );

  $.Method({Static:true , Public:true }, "op_Addition", 
    $sig.make(279460, $.Type, [$.Type, $.Type], []), 
    function CustomType_op_Addition (lhs, rhs) {
      return new $asm00.CustomType((lhs.Value + rhs.Value));
    }
  );

  $.Method({Static:false, Public:true }, "toString", 
    $sig.make(279462, $.String, [], []), 
    function CustomType_toString () {
      return $asm01.System.String.Format("{0}", this.Value);
    }
  );

  $.Field({Static:false, Public:true }, "Value", $.Int32);

});