Performance improvements for D / DMD compiler.

[Andrei Alexandrescu (See Website For Email)]

Christian Kamm wrote:
>> What's on your wish-list (let's leave the GC and other library 
>> functionality out of this for now <g>)?
> 
> I'd like to see unneccessary copies being optimized away, especially of 
> large structs passed to functions. The workaround
> 
> // use inout to pass s by reference, it is not actually modified
> void foo(inout LargeStruct s)
> 
> is just abusing inout. In my opinion it should be an in parameter and D 
> should detect whether a copy is neccessary or not.
> 
> It's not done already, is it?

No, and for a good reason:

foo(LargeStruct s1, LargeStruct s2)
{
   ...
}
...
LargeStruct s;
foo(s, s);

Nobody would enjoy hidden aliasing of s1 and s2.


Andrei