One possible way to salvage it: Have you considered declaring long_alloc as Py_LOCAL_INLINE, or, now that I've checked #5553, a macro for long_alloc, so it gets inlined, and doesn't add the check overhead to everything (since properly inlining with a constant argument to use_calloc should make the optimizer trim the unused code path at compile time)?

Probably not very PEP7 friendly to macro-ize something that long I'm guessing...