Add PyCMethod_* and machinery to call it

python · vstinner · May 7, 2020 · Apr 21, 2020 · Apr 21, 2020 · Apr 21, 2020
commit 856f0a31701005b29988098de79983271ed40845
diff --git a/Include/cpython/methodobject.h b/Include/cpython/methodobject.h
@@ -1,6 +1,9 @@
 #ifndef Py_CPYTHON_METHODOBJECT_H
 #  error "this header file must not be included directly"
 #endif
+
+PyAPI_DATA(PyTypeObject) PyCMethod_Type;
+
 /* Macros for direct access to these values. Type checks are *not*
    done, so use with care. */
 #define PyCFunction_GET_FUNCTION(func) \
@@ -10,6 +13,10 @@
          NULL : ((PyCFunctionObject *)func) -> m_self)
 #define PyCFunction_GET_FLAGS(func) \
         (((PyCFunctionObject *)func) -> m_ml -> ml_flags)
+#define PyCFunction_GET_CLASS(func) \
+    (((PyCFunctionObject *)func) -> m_ml -> ml_flags & METH_METHOD ? \
+         ((PyCMethodObject *)func) -> mm_class : NULL)
+
 typedef struct {
     PyObject_HEAD
     PyMethodDef *m_ml; /* Description of the C function to call */
@@ -18,3 +25,8 @@ typedef struct {
     PyObject    *m_weakreflist; /* List of weak references */
     vectorcallfunc vectorcall;
 } PyCFunctionObject;
+
+typedef struct {
+    PyCFunctionObject func;
+    PyTypeObject *mm_class; /* Class that defines this method */
+} PyCMethodObject;
diff --git a/Include/methodobject.h b/Include/methodobject.h
@@ -13,7 +13,7 @@ extern "C" {
 
 PyAPI_DATA(PyTypeObject) PyCFunction_Type;
 
-#define PyCFunction_Check(op) Py_IS_TYPE(op, &PyCFunction_Type)
+#define PyCFunction_Check(op) (Py_IS_TYPE(op, &PyCFunction_Type) || (PyType_IsSubtype(Py_TYPE(op), &PyCFunction_Type)))
 
 typedef PyObject *(*PyCFunction)(PyObject *, PyObject *);
 typedef PyObject *(*_PyCFunctionFast) (PyObject *, PyObject *const *, Py_ssize_t);
@@ -22,6 +22,9 @@ typedef PyObject *(*PyCFunctionWithKeywords)(PyObject *, PyObject *,
 typedef PyObject *(*_PyCFunctionFastWithKeywords) (PyObject *,
                                                    PyObject *const *, Py_ssize_t,
                                                    PyObject *);
+typedef PyObject *(*PyCMethod)(PyObject *, PyTypeObject *, PyObject *const *,
+                               size_t, PyObject *);
+
 PyAPI_FUNC(PyCFunction) PyCFunction_GetFunction(PyObject *);
 PyAPI_FUNC(PyObject *) PyCFunction_GetSelf(PyObject *);
 PyAPI_FUNC(int) PyCFunction_GetFlags(PyObject *);
@@ -41,6 +44,13 @@ typedef struct PyMethodDef PyMethodDef;
 PyAPI_FUNC(PyObject *) PyCFunction_NewEx(PyMethodDef *, PyObject *,
                                          PyObject *);
 
+#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x03090000
+#define PyCFunction_NewEx(ML, SELF, MOD) PyCMethod_New((ML), (SELF), (MOD), NULL)
+PyAPI_FUNC(PyObject *) PyCMethod_New(PyMethodDef *, PyObject *,
+                                     PyObject *, PyTypeObject *);
+#endif
+
+
 /* Flag passed to newmethodobject */
 /* #define METH_OLDARGS  0x0000   -- unsupported now */
 #define METH_VARARGS  0x0001
@@ -73,6 +83,18 @@ PyAPI_FUNC(PyObject *) PyCFunction_NewEx(PyMethodDef *, PyObject *,
 #define METH_STACKLESS 0x0000
 #endif
 
+/* METH_METHOD means the function stores an
+ * additional reference to the class that defines it;
+ * both self and class are passed to it.
+ * It uses PyCMethodObject instead of PyCFunctionObject.
+ * May not be combined with METH_NOARGS, METH_O, METH_CLASS or METH_STATIC.
+ */
+
+#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x03090000
+#define METH_METHOD 0x0200
+#endif
+
+
 #ifndef Py_LIMITED_API
 
 #define Py_CPYTHON_METHODOBJECT_H

diff --git a/Objects/descrobject.c b/Objects/descrobject.c
@@ -127,7 +127,11 @@ classmethod_get(PyMethodDescrObject *descr, PyObject *obj, PyObject *type)
                      ((PyTypeObject *)type)->tp_name);
         return NULL;
     }
-    return PyCFunction_NewEx(descr->d_method, type, NULL);
+    PyTypeObject *cls = NULL;
+    if (descr->d_method->ml_flags & METH_METHOD) {
+        cls = descr->d_common.d_type;
+    }
+    return PyCMethod_New(descr->d_method, type, NULL, cls);
 }
 
 static PyObject *
@@ -137,7 +141,19 @@ method_get(PyMethodDescrObject *descr, PyObject *obj, PyObject *type)
 
     if (descr_check((PyDescrObject *)descr, obj, &res))
         return res;
-    return PyCFunction_NewEx(descr->d_method, obj, NULL);
+    if (descr->d_method->ml_flags & METH_METHOD) {
+        if (PyType_Check(type)) {
+            return PyCMethod_New(descr->d_method, obj, NULL, descr->d_common.d_type);
+        } else {
+            PyErr_Format(PyExc_TypeError,
+                        "descriptor '%V' needs a type, not '%s', as arg 2",
+                        descr_name((PyDescrObject *)descr),
+                        Py_TYPE(type)->tp_name);
+            return NULL;
+        }
+    } else {
+        return PyCFunction_NewEx(descr->d_method, obj, NULL);
+    }
 }
 
 static PyObject *
@@ -335,6 +351,27 @@ method_vectorcall_VARARGS_KEYWORDS(
     return result;
 }
 
+static PyObject *
+method_vectorcall_FASTCALL_KEYWORDS_METHOD(
+    PyObject *func, PyObject *const *args, size_t nargsf, PyObject *kwnames)
+{
+    PyThreadState *tstate = _PyThreadState_GET();
+    Py_ssize_t nargs = PyVectorcall_NARGS(nargsf);
+    if (method_check_args(func, args, nargs, NULL)) {
+        return NULL;
+    }
+     NULL;
+    PyCMethod meth = (PyCMethod) method_enter_call(tstate, func);
+    if (meth == NULL) {
+        return NULL;
+    }
+    PyObject *result = meth(args[0],
+                            ((PyMethodDescrObject *)func)->d_common.d_type,
+                            args+1, nargs-1, kwnames);
+    Py_LeaveRecursiveCall();
+    return result;
+}
+
 static PyObject *
 method_vectorcall_FASTCALL(
     PyObject *func, PyObject *const *args, size_t nargsf, PyObject *kwnames)
@@ -868,7 +905,8 @@ PyDescr_NewMethod(PyTypeObject *type, PyMethodDef *method)
 {
     /* Figure out correct vectorcall function to use */
     vectorcallfunc vectorcall;
-    switch (method->ml_flags & (METH_VARARGS | METH_FASTCALL | METH_NOARGS | METH_O | METH_KEYWORDS))
+    switch (method->ml_flags & (METH_VARARGS | METH_FASTCALL | METH_NOARGS |
+                                METH_O | METH_KEYWORDS | METH_METHOD))
     {
         case METH_VARARGS:
             vectorcall = method_vectorcall_VARARGS;
@@ -888,6 +926,9 @@ PyDescr_NewMethod(PyTypeObject *type, PyMethodDef *method)
         case METH_O:
             vectorcall = method_vectorcall_O;
             break;
+        case METH_METHOD | METH_FASTCALL | METH_KEYWORDS:
+            vectorcall = method_vectorcall_FASTCALL_KEYWORDS_METHOD;
+            break;
         default:
             PyErr_Format(PyExc_SystemError,
                          "%s() method: bad call flags", method->ml_name);

diff --git a/Objects/methodobject.c b/Objects/methodobject.c
@@ -10,12 +10,16 @@
 
 /* undefine macro trampoline to PyCFunction_NewEx */
 #undef PyCFunction_New
+/* undefine macro trampoline to PyCMethod_New */
+#undef PyCFunction_NewEx
 
 /* Forward declarations */
 static PyObject * cfunction_vectorcall_FASTCALL(
     PyObject *func, PyObject *const *args, size_t nargsf, PyObject *kwnames);
 static PyObject * cfunction_vectorcall_FASTCALL_KEYWORDS(
     PyObject *func, PyObject *const *args, size_t nargsf, PyObject *kwnames);
+static PyObject * cfunction_vectorcall_FASTCALL_KEYWORDS_METHOD(
+    PyObject *func, PyObject *const *args, size_t nargsf, PyObject *kwnames);
 static PyObject * cfunction_vectorcall_NOARGS(
     PyObject *func, PyObject *const *args, size_t nargsf, PyObject *kwnames);
 static PyObject * cfunction_vectorcall_O(
@@ -32,10 +36,17 @@ PyCFunction_New(PyMethodDef *ml, PyObject *self)
 
 PyObject *
 PyCFunction_NewEx(PyMethodDef *ml, PyObject *self, PyObject *module)
+{
+    return PyCMethod_New(ml, self, module, NULL);
+}
+
+PyObject *
+PyCMethod_New(PyMethodDef *ml, PyObject *self, PyObject *module, PyTypeObject *cls)
 {
     /* Figure out correct vectorcall function to use */
     vectorcallfunc vectorcall;
-    switch (ml->ml_flags & (METH_VARARGS | METH_FASTCALL | METH_NOARGS | METH_O | METH_KEYWORDS))
+    switch (ml->ml_flags & (METH_VARARGS | METH_FASTCALL | METH_NOARGS |
+                            METH_O | METH_KEYWORDS | METH_METHOD))
     {
         case METH_VARARGS:
         case METH_VARARGS | METH_KEYWORDS:
@@ -55,17 +66,44 @@ PyCFunction_NewEx(PyMethodDef *ml, PyObject *self, PyObject *module)
         case METH_O:
             vectorcall = cfunction_vectorcall_O;
             break;
+        case METH_METHOD | METH_FASTCALL | METH_KEYWORDS:
+            vectorcall = cfunction_vectorcall_FASTCALL_KEYWORDS_METHOD;
+            break;
         default:
             PyErr_Format(PyExc_SystemError,
                          "%s() method: bad call flags", ml->ml_name);
             return NULL;
     }
 
-    PyCFunctionObject *op =
-        PyObject_GC_New(PyCFunctionObject, &PyCFunction_Type);
-    if (op == NULL) {
-        return NULL;
+    PyCFunctionObject *op = NULL;
+
+    if (ml->ml_flags & METH_METHOD) {
+        if (!cls) {
+            PyErr_SetString(PyExc_SystemError,
+                            "attempting to create PyCMethod with a METH_METHOD "
+                            "flag but no class");
+            return NULL;
+        }
+        PyCMethodObject *om = PyObject_GC_New(PyCMethodObject, &PyCMethod_Type);
+        if (om == NULL) {
+            return NULL;
+        }
+        Py_INCREF(cls);
+        om->mm_class = cls;
+        op = (PyCFunctionObject *)om;
+    } else {
+        if (cls) {
+            PyErr_SetString(PyExc_SystemError,
+                            "attempting to create PyCFunction with class "
+                            "but no METH_METHOD flag");
+            return NULL;
+        }
+        op = PyObject_GC_New(PyCFunctionObject, &PyCFunction_Type);
+        if (op == NULL) {
+            return NULL;
+        }
     }
+
     op->m_weakreflist = NULL;
     op->m_ml = ml;
     Py_XINCREF(self);
@@ -107,6 +145,16 @@ PyCFunction_GetFlags(PyObject *op)
     return PyCFunction_GET_FLAGS(op);
 }
 
+PyTypeObject *
+PyCMethod_GetClass(PyObject *op)
+{
+    if (!PyCFunction_Check(op)) {
+        PyErr_BadInternalCall();
+        return NULL;
+    }
+    return PyCFunction_GET_CLASS(op);
+}
+
 /* Methods (the standard built-in methods, that is) */
 
 static void
@@ -118,6 +166,7 @@ meth_dealloc(PyCFunctionObject *m)
     }
     Py_XDECREF(m->m_self);
     Py_XDECREF(m->m_module);
+    Py_XDECREF(PyCFunction_GET_CLASS(m));
     PyObject_GC_Del(m);
 }
 
@@ -196,6 +245,7 @@ meth_traverse(PyCFunctionObject *m, visitproc visit, void *arg)
 {
     Py_VISIT(m->m_self);
     Py_VISIT(m->m_module);
+    Py_VISIT(PyCFunction_GET_CLASS(m));
     return 0;
 }
 
@@ -314,6 +364,13 @@ PyTypeObject PyCFunction_Type = {
     0,                                          /* tp_dict */
 };
 
+PyTypeObject PyCMethod_Type = {
+    PyVarObject_HEAD_INIT(&PyType_Type, 0)
+    .tp_name = "builtin_method",
+    .tp_basicsize = sizeof(PyCMethodObject),
+    .tp_base = &PyCFunction_Type,
+};
+
 /* Vectorcall functions for each of the PyCFunction calling conventions,
  * except for METH_VARARGS (possibly combined with METH_KEYWORDS) which
  * doesn't use vectorcall.
@@ -385,6 +442,22 @@ cfunction_vectorcall_FASTCALL_KEYWORDS(
     return result;
 }
 
+static PyObject *
+cfunction_vectorcall_FASTCALL_KEYWORDS_METHOD(
+    PyObject *func, PyObject *const *args, size_t nargsf, PyObject *kwnames)
+{
+    PyThreadState *tstate = _PyThreadState_GET();
+    PyTypeObject *cls = PyCFunction_GET_CLASS(func);
+    Py_ssize_t nargs = PyVectorcall_NARGS(nargsf);
+    PyCMethod meth = (PyCMethod)cfunction_enter_call(tstate, func);
+    if (meth == NULL) {
+        return NULL;
+    }
+    PyObject *result = meth(PyCFunction_GET_SELF(func), cls, args, nargs, kwnames);
+    _Py_LeaveRecursiveCall(tstate);
+    return result;
+}
+
 static PyObject *
 cfunction_vectorcall_NOARGS(
     PyObject *func, PyObject *const *args, size_t nargsf, PyObject *kwnames)

diff --git a/Objects/object.c b/Objects/object.c
@@ -1789,6 +1789,7 @@ _PyTypes_Init(void)
     INIT_TYPE(&PyCode_Type, "code");
     INIT_TYPE(&PyFrame_Type, "frame");
     INIT_TYPE(&PyCFunction_Type, "builtin function");
+    INIT_TYPE(&PyCMethod_Type, "builtin method");
     INIT_TYPE(&PyMethod_Type, "method");
     INIT_TYPE(&PyFunction_Type, "function");
     INIT_TYPE(&PyDictProxy_Type, "dict proxy");