Member hooks versus base hooks in intrusive data structures

Question

I'm coding an intrusive data structure and wondering whether to use base or member hooks. As the code will be called many times, my question regards performance and to what extent the compilers are able to inline such code.

Base hooks are based on inheritance while member hooks use pointers-to-members via template parameters. My design choice would be to use member hooks, but my experience says pointers are much harder to optimize than static code. On the other hand, all those pointers are known at compile time and perhaps the compiler can do some magic to analyze what's happening.

Does anyone has some experience with this? Any data, hints or references are welcome.

Answer 1

Since data and hooks are in a "has a" Relationship I'd also prefer member hooks from a design point of view. I also don't think there is a difference in optimization between putting the hooks in a base class than putting them into a class directly.

There is also some consideration about these different approaches in Boost intrusive.

Answer 2

As for most "X vs Y, what is faster?" questions there is only one proper answer for this one:

Ask your profiler.

Experience is vague. Human guesswork can not take into account all the nitty gritty details and pitfalls of compiler optimizations. Compilers differ in what they can optimize and how good they do it. Sometimes even between different versions of the same compiler. The only thing that can tell you well how your implementations can be optimized by your specific compiler(s) on your specific platform(s) is a proper measurement of performance with typical problem sizes.

Even if there is someone who tells you he knows what is faster and gives you some pretty graphs: can you trust him enough to not make those measurements? Does he know what your specific environment looks like? Does he and his graphs take into account the special corner cases of your problems? Most probably not.