Use the C API for calling a method

PyObject_CallMethodNoArgs() and PyObject_CallMethodOneArg() look up the
method and call it in one step, without creating a bound method object.

Author: serhiy-storchaka

Modules/_io/bufferedio.c

@@ -2333,34 +2333,22 @@ bufferedrwpair_dealloc(PyObject *op)
     Py_DECREF(tp);
 }
 
+/* Call the method of the underlying reader or writer.  The argument is
+   only passed if it is not NULL, so that the default of that method is
+   used otherwise. */
 static PyObject *
-_forward_call(buffered *self, PyObject *name, PyObject *const *args,
-              Py_ssize_t nargs)
+_forward_call(buffered *self, PyObject *name, PyObject *arg)
 {
-    PyObject *func, *ret;
     if (self == NULL) {
         PyErr_SetString(PyExc_ValueError,
                         "I/O operation on uninitialized object");
         return NULL;
     }
 
-    func = PyObject_GetAttr((PyObject *)self, name);
-    if (func == NULL) {
-        PyErr_SetObject(PyExc_AttributeError, name);
-        return NULL;
+    if (arg == NULL) {
+        return PyObject_CallMethodNoArgs((PyObject *)self, name);
     }
-
-    ret = PyObject_Vectorcall(func, args, nargs, NULL);
-    Py_DECREF(func);
-    return ret;
-}
-
-/* The optional argument is only passed if it is specified, so that the
-   default of the underlying method is used otherwise. */
-static PyObject *
-_forward_call_opt(buffered *self, PyObject *name, PyObject *arg)
-{
-    return _forward_call(self, name, &arg, arg != NULL);
+    return PyObject_CallMethodOneArg((PyObject *)self, name, arg);
 }
 
 /*[clinic input]
@@ -2373,7 +2361,7 @@ static PyObject *
 _io_BufferedRWPair_read_impl(rwpair *self, PyObject *size)
 /*[clinic end generated code: output=0668e3c5dbd3e93d input=eddb5e52aba9ebe5]*/
 {
-    return _forward_call_opt(self->reader, &_Py_ID(read), size);
+    return _forward_call(self->reader, &_Py_ID(read), size);
 }
 
 /*[clinic input]
@@ -2386,7 +2374,7 @@ static PyObject *
 _io_BufferedRWPair_peek_impl(rwpair *self, PyObject *size)
 /*[clinic end generated code: output=190a267bd694efa0 input=36af95964bebe355]*/
 {
-    return _forward_call_opt(self->reader, &_Py_ID(peek), size);
+    return _forward_call(self->reader, &_Py_ID(peek), size);
 }
 
 /*[clinic input]
@@ -2399,7 +2387,7 @@ static PyObject *
 _io_BufferedRWPair_read1_impl(rwpair *self, PyObject *size)
 /*[clinic end generated code: output=17ec19608f2bb825 input=9e94db423e490b58]*/
 {
-    return _forward_call_opt(self->reader, &_Py_ID(read1), size);
+    return _forward_call(self->reader, &_Py_ID(read1), size);
 }
 
 /*[clinic input]
@@ -2412,7 +2400,7 @@ static PyObject *
 _io_BufferedRWPair_readinto_impl(rwpair *self, PyObject *buffer)
 /*[clinic end generated code: output=16c86b071015f7a4 input=ccd86ce2666261f7]*/
 {
-    return _forward_call(self->reader, &_Py_ID(readinto), &buffer, 1);
+    return _forward_call(self->reader, &_Py_ID(readinto), buffer);
 }
 
 /*[clinic input]
@@ -2425,7 +2413,7 @@ static PyObject *
 _io_BufferedRWPair_readinto1_impl(rwpair *self, PyObject *buffer)
 /*[clinic end generated code: output=f1577b6f54c2b02a input=613d9bf127f88a4a]*/
 {
-    return _forward_call(self->reader, &_Py_ID(readinto1), &buffer, 1);
+    return _forward_call(self->reader, &_Py_ID(readinto1), buffer);
 }
 
 /*[clinic input]
@@ -2438,7 +2426,7 @@ static PyObject *
 _io_BufferedRWPair_write_impl(rwpair *self, PyObject *buffer)
 /*[clinic end generated code: output=6f7509a747410c68 input=66c602422e3ec36f]*/
 {
-    return _forward_call(self->writer, &_Py_ID(write), &buffer, 1);
+    return _forward_call(self->writer, &_Py_ID(write), buffer);
 }
 
 /*[clinic input]
@@ -2449,7 +2437,7 @@ static PyObject *
 _io_BufferedRWPair_flush_impl(rwpair *self)
 /*[clinic end generated code: output=0b2dcbe828718d6b input=e853da796ee61df1]*/
 {
-    return _forward_call(self->writer, &_Py_ID(flush), NULL, 0);
+    return _forward_call(self->writer, &_Py_ID(flush), NULL);
 }
 
 /*[clinic input]
@@ -2460,7 +2448,7 @@ static PyObject *
 _io_BufferedRWPair_readable_impl(rwpair *self)
 /*[clinic end generated code: output=615967d4aa58f122 input=0475ed73d0a3167f]*/
 {
-    return _forward_call(self->reader, &_Py_ID(readable), NULL, 0);
+    return _forward_call(self->reader, &_Py_ID(readable), NULL);
 }
 
 /*[clinic input]
@@ -2471,7 +2459,7 @@ static PyObject *
 _io_BufferedRWPair_writable_impl(rwpair *self)
 /*[clinic end generated code: output=c5a43c84e0195c11 input=3cfd44fb4757082f]*/
 {
-    return _forward_call(self->writer, &_Py_ID(writable), NULL, 0);
+    return _forward_call(self->writer, &_Py_ID(writable), NULL);
 }
 
 /*[clinic input]
@@ -2483,14 +2471,14 @@ _io_BufferedRWPair_close_impl(rwpair *self)
 /*[clinic end generated code: output=5924ba5ecc78752a input=4087d69f2d8fc368]*/
 {
     PyObject *exc = NULL;
-    PyObject *ret = _forward_call(self->writer, &_Py_ID(close), NULL, 0);
+    PyObject *ret = _forward_call(self->writer, &_Py_ID(close), NULL);
     if (ret == NULL) {
         exc = PyErr_GetRaisedException();
     }
     else {
         Py_DECREF(ret);
     }
-    ret = _forward_call(self->reader, &_Py_ID(close), NULL, 0);
+    ret = _forward_call(self->reader, &_Py_ID(close), NULL);
     if (exc != NULL) {
         _PyErr_ChainExceptions1(exc);
         Py_CLEAR(ret);
@@ -2506,15 +2494,15 @@ static PyObject *
 _io_BufferedRWPair_isatty_impl(rwpair *self)
 /*[clinic end generated code: output=d017c621ed879cb7 input=92833e3d60586e14]*/
 {
-    PyObject *ret = _forward_call(self->writer, &_Py_ID(isatty), NULL, 0);
+    PyObject *ret = _forward_call(self->writer, &_Py_ID(isatty), NULL);
 
     if (ret != Py_False) {
         /* either True or exception */
         return ret;
     }
     Py_DECREF(ret);
 
-    return _forward_call(self->reader, &_Py_ID(isatty), NULL, 0);
+    return _forward_call(self->reader, &_Py_ID(isatty), NULL);
 }
 
 static PyObject *