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.

2 files changed, 20 insertions, 0 deletions

diff --git a/Include/abstract.h b/Include/abstract.h
index 3f398da..3e630b1 100644
--- a/Include/abstract.h
+++ b/Include/abstract.h
@@ -277,6 +277,22 @@ xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx*/
         PyObject *kwnames,
         PyObject *func);
 
+    /* Convert (args, nargs, kwargs) into a (stack, nargs, kwnames).
+
+       Return a new stack which should be released by PyMem_Free(), or return
+       args unchanged if kwargs is NULL or an empty dictionary.
+
+       The stack uses borrowed references.
+
+       The type of keyword keys is not checked, these checks should be done
+       later (ex: _PyArg_ParseStack). */
+    PyAPI_FUNC(PyObject **) _PyStack_UnpackDict(
+        PyObject **args,
+        Py_ssize_t nargs,
+        PyObject *kwargs,
+        PyObject **kwnames,
+        PyObject *func);
+
      /* Call the callable object func with the "fast call" calling convention:
         args is a C array for positional arguments (nargs is the number of
         positional arguments), kwargs is a dictionary for keyword arguments.
diff --git a/Include/methodobject.h b/Include/methodobject.h
index 1f4f06c..9dba58f 100644
--- a/Include/methodobject.h
+++ b/Include/methodobject.h
@@ -16,6 +16,8 @@ PyAPI_DATA(PyTypeObject) PyCFunction_Type;
 #define PyCFunction_Check(op) (Py_TYPE(op) == &PyCFunction_Type)
 
 typedef PyObject *(*PyCFunction)(PyObject *, PyObject *);
+typedef PyObject *(*_PyCFunctionFast) (PyObject *self, PyObject **args,
+                                       Py_ssize_t nargs, PyObject *kwnames);
 typedef PyObject *(*PyCFunctionWithKeywords)(PyObject *, PyObject *,
                                              PyObject *);
 typedef PyObject *(*PyNoArgsFunction)(PyObject *);
@@ -83,6 +85,8 @@ PyAPI_FUNC(PyObject *) PyCFunction_NewEx(PyMethodDef *, PyObject *,
 
 #define METH_COEXIST   0x0040
 
+#define METH_FASTCALL  0x0080
+
 #ifndef Py_LIMITED_API
 typedef struct {
     PyObject_HEAD