GC finalizer optimization.

[kris]

Dave wrote:
> 
> Comments? Like, how can this break things?
> 
> By changing line 129 of phobos/internal/gc/gc.d from:
> 
> _gc.setFinalizer(p, &new_finalizer);
> 
> to:
> 
> ///_gc.setFinalizer(p, &new_finalizer);
> ///
>     ClassInfo c = ci;
>     do
>     {
>         if (c.destructor)
>         {
>             _gc.setFinalizer(p, &new_finalizer);
>         }
>         c = c.base;
>     } while (c);
> ///
> 
> gives me about 3x performance in allocating class objects w/o a dtor 
> using the following code.
> 
> Before:
> D::~this
> C::~this
> C::~this
> 0.829
> 
> After:
> D::~this
> C::~this
> C::~this
> 0.258
> 


Heh heh heh ;-)

Then, to identify "leaking" resources, the collector only has to check 
if there's a finalizer set :)