Null references redux

[Nick Sabalausky]

"Yigal Chripun" <yigal100 at gmail.com> wrote in message 
news:h9r37i$tgl$1 at digitalmars.com...
>
>>
>> These aren't just marginal performance gains, they can easily be up to
>> 15-30% improvements, sometimes 50% and more. If this is too complex or
>> the risk is too high for you then don't use a systems language :)
>
> your approach makes sense if your are implementing say a calculator.
> It doesn't scale to larger projects. Even C++ has overhead compared to 
> assembly yet you are writing performance critical code in c++, right?
>

It's *most* important on larger projects, because it's only on big systems 
where small inefficiencies actually add up to a large performance drain.

Try writing a competitive real-time graphics renderer or physics simulator 
(especially for a game console where you're severely limited in your choice 
of compiler - if you even have a choice), or something like Pixar's renderer 
without *ever* diving into asm, or at least low-level "unsafe" code. And 
when it inevitably hits some missing optimization in the compiler and runs 
like shit, try explaining to the dev lead why it's better to beg the 
compiler vender to add the optimization you want and wait around hoping they 
finally do so, instead of just throwing in that inner optimization in the 
meantime.

You can still leave the safe/portable version in there for platforms for 
which you haven't provided a hand-optimization. And unless you didn't know 
what you were doing, that inner optimization will still be small and highly 
isolated. And since it's so small and isolated, not only can you still throw 
in tests for it, but it's not as much harder as you would think to veryify 
correctness. And if/when your compiler finally does get the optimization you 
want, you can just rip out the hand-optimization and revert back to that 
"safe/portable" version that you had still left in anyway as a fallback.