Skip Montanaro
I do have one question though. Suppose you encounter a compiler that doesn't understand the inline keyword, so you choose the static declaration as Kristján suggested. The resulting Python executable should be functionally correct, but if the optimizer doesn't happen to inline a given static function you might be stuck with some bad performance across-the-board (if it never inlines, or doesn't inline where we really need it to), or only under some circumstances (as a hypothetical example, inlining in dictobject.c, but not in ceval.c). Is there a configurable way to tell if a compiler will inline functions which are declared static, and possibly under what conditions they might not? It might still be necessary to maintain macros for those platforms.
I think that all modern compilers can handle "static inline" in header files. If you have a compiler that cannot, chances are that the platform is horribly outdated and this particular performance issue will be relatively benign compared to other ones. Stefan Krah