Re:Under the hood of C++ lambdas and std::function
by exDM69 on Monday March 28, 2016 @09:26AM
(#11374096)
> C doesn't have templates, therefore it doesn't have compile-time polymorphism, therefore it's much harder for the compiler to inline.
A C compiler can do the same inlining and optimizing as long as the called function (e.g. qsort) and the function that's pointed-to (e.g. the comparison function) are in the same compilation unit.
C++ templates do not add any magic here, std::sort() is simply faster because it's in a header file and qsort() is not. If you pass a function pointer to a function in a different object file to std::sort, it won't have a lot of advantages over qsort in terms of optimizations/performance (it still does know sizeof(T), though).
Link-time optimization should make standard qsort-type functions perform similarly to std::sort.
A C compiler can do the same inlining and optimizing as long as the called function (e.g. qsort) and the function that's pointed-to (e.g. the comparison function) are in the same compilation unit.
C++ templates do not add any magic here, std::sort() is simply faster because it's in a header file and qsort() is not. If you pass a function pointer to a function in a different object file to std::sort, it won't have a lot of advantages over qsort in terms of optimizations/performance (it still does know sizeof(T), though).
Link-time optimization should make standard qsort-type functions perform similarly to std::sort.