fastcall.patch combines two changes:

changeset:   103513:74abb8ddf7f2
tag:         tip
user:        Victor Stinner <victor.stinner@gmail.com>
date:        Fri Sep 09 17:40:38 2016 -0700
files:       Include/modsupport.h Python/getargs.c Tools/clinic/clinic.py
description:
Emit METH_FASTCALL code in Argument Clinic

Issue #27810:

* Modify vgetargskeywordsfast() to work on a C array of PyObject* rather than
  working on a tuple directly.
* Add _PyArg_ParseStack()
* Argument Clinic now emits code using the new METH_FASTCALL calling convention


changeset:   103512:d55abcddd194
user:        Victor Stinner <victor.stinner@gmail.com>
date:        Fri Sep 09 17:40:22 2016 -0700
files:       Include/abstract.h Include/methodobject.h Objects/abstract.c Objects/methodobject.c
description:
Add METH_FASTCALL calling convention

Issue #27810: Add a new calling convention for C functions:

    PyObject* func(PyObject *self, PyObject **args,
                   Py_ssize_t nargs, PyObject *kwnames);

Where args is a C array of positional arguments followed by values of keyword
arguments. nargs is the number of positional arguments, kwnames are keys of
keyword arguments. kwnames can be NULL.