Struct default constructor - need some kind of solution for C++ interop

[Ethan Watson via Digitalmars-d]

On Wednesday, 7 September 2016 at 22:52:04 UTC, Walter Bright 
wrote:
> Is:
>
>     if (resource != null)
>         resource.destroy();
>
> v.s.:
>
>     resource.destroy();
>
> so onerous? It's one TST/JNE pair for a value loaded into a 
> register anyway.

This one has performance implications for game developers. The 
branch predictor in the CPU used for the Xbox One and the PS4 
isn't the greatest. If, for example, that destructor gets inlined 
and you're iterating over a range of resources and the destroy 
method is virtual, there's a good chance you will invoke the 
wrath of the dense branch predictor. You don't want to deal with 
the dense branch predictor.

http://www.agner.org/optimize/microarchitecture.pdf section 3.13 
has a bit more info on the branch predictor. Desktop Intel CPUs 
tend to hide performance problems like this thanks to their 
far-higher-quality branch predictors. Both chips gain benefits 
from sorting to how you expect the branch predictor to work, but 
there's a lot of code in a game codebase that isn't that low 
level.