DIP74: Reference Counted Class Objects

[Andrei Alexandrescu via Digitalmars-d]

On 3/1/15 6:55 AM, John Colvin wrote:
> On Sunday, 1 March 2015 at 03:43:24 UTC, Andrei Alexandrescu wrote:
>> It might be more productive to look into improvements of optimizations
>> related to copying objects.
>>
>>
>> Andrei
>
> Yes please. I'd be very interested in hearing any thoughts you have on
> this.

One that comes to mind is: if (a) a copy b of a struct object a is 
created, (b) b is used only with non-mutating operations, and (c) a is 
not changed before b goes out of scope, then a can be directly 
substituted for b (no actual copy is made).

Example:

struct S {
   this(this);
   ~this();
   int method() const;
}

int fun() {
   S a;
   S b = a;
   return b.method();
}

may be lowered to:

int fun() {
   S a;
   return a.method();
}


Andrei