Serhiy: Thanks for looking at this!
I think it should fall in the same category as Py_RETURN_TRUE or Py_RETURN_NONE. Sure, it's easy to reimplement, but a lot of extensions need it; why should everyone need to write the same code in a dozen different ways?
I specifically want this usable in third-party code.

The implementation of Py_RICHCOMPARE is in the first patch. The second is example use.
The signature mirrors richcmpfunc. Why would op be better as first argument?

Stefan: Which optimizer should I look at? Is it important to generate the same code? 

Sorry if I'm asking for something obvious, I'm not a regular here.