Build tape optimization

[arakov]

• extra temporal variables
• boxing an array, assigning to the local variable - get rid of double assigning
• dirty_ptr := dirty_ptr + int
• copy a sub array to another array - starting
• copy a sub array to another array
• tuple / array unboxing
• optimization single dispatching
• String.prop:Length[1]
• optimization sealed dispatching
• optimization xstore sp:0, 0 and xstore sp:1, 0 - should be replaced with xor operation
• comparing Handle with WindowHandle should be native
• optimize Amicable pairs
• getting / setting a prop field - should be done directly if it is trivial getter / setter
• unused allocated variable should be removed to spare stack
• BuildKey::CopyingAccField, 0

• get rid of extra assigning here:

  class A { object field;

    object Value
       = field;
  
    constructor(value)
    {
       field := value;
    }

  }

  public program() { A a := new A(2);

   var val := *a;

  }

The output is:

>@function program.function:#invoke
       xflush       sp:0
       open           :4, :0
       store        fp:1
       xstore       sp:0, intconst:2
       set       class:sandbox'$private'A
       mov        mssg:function:#constructor[1]
       call       mssg:function:#constructor[1], class:sandbox'$private'A#class
       store        fp:3  // an extra save?
       store        fp:2   
       store        sp:0
       mov        mssg:prop:Value[1]
       call         vt:0
       store        fp:3
       peek         fp:1
Lab00:     nop
       close          :0
       quit           
@end