Efficiency improvements for enabling/disabling gc in __Pyx_PyType_Ready().

These are more important in light of it being used ubiquitously.

Cython/Utility/ExtensionTypes.c

@@ -3,6 +3,7 @@
 static int __Pyx_PyType_Ready(PyTypeObject *t);
 
 /////////////// PyType_Ready ///////////////
+//@requires: ObjectHandling.c::PyObjectCallNoArg
 
 // Wrapper around PyType_Ready() with some runtime checks and fixes
 // to deal with multiple inheritance.
@@ -67,24 +68,35 @@ static int __Pyx_PyType_Ready(PyTypeObject *t) {
         // For details, see https://github.com/cython/cython/issues/3603
         PyObject *ret, *py_status;
         int gc_was_enabled;
-        PyObject *gc = PyImport_Import(PYUNICODE("gc"));
-        if (unlikely(!gc)) return -1;
-        py_status = PyObject_CallMethodObjArgs(gc, PYUNICODE("isenabled"), NULL);
+        static PyObject *gc = NULL;
+        static PyObject *gc_isenabled = NULL, *gc_enable = NULL, *gc_disable = NULL;
+        if (unlikely(!gc)) {
+            gc = PyImport_Import(PYUNICODE("gc"));
+            if (unlikely(!gc)) return -1;
+            gc_isenabled = PyObject_GetAttr(gc, PYUNICODE("isenabled"));
+            gc_enable = PyObject_GetAttr(gc, PYUNICODE("enable"));
+            gc_disable = PyObject_GetAttr(gc, PYUNICODE("disable"));
+            if (unlikely(!gc_isenabled || !gc_enable || !gc_disable)) {
+              Py_XDECREF(gc_isenabled);  gc_isenabled = NULL;
+              Py_XDECREF(gc_enable);  gc_enable = NULL;
+              Py_XDECREF(gc_disable);  gc_disable = NULL;
+              Py_XDECREF(gc); gc = NULL;
+              return -1;
+            }
+        }
+        py_status = __Pyx_PyObject_CallNoArg(gc_isenabled);
         if (unlikely(!py_status)) {
-            Py_DECREF(gc);
             return -1;
         }
         gc_was_enabled = __Pyx_PyObject_IsTrue(py_status);
         Py_DECREF(py_status);
         if (gc_was_enabled > 0) {
-            ret = PyObject_CallMethodObjArgs(gc, PYUNICODE("disable"), NULL);
+            ret = __Pyx_PyObject_CallNoArg(gc_disable);
             if (unlikely(!ret)) {
-                Py_DECREF(gc);
                 return -1;
             }
             Py_DECREF(ret);
         } else if (unlikely(gc_was_enabled == -1)) {
-            Py_DECREF(gc);
             return -1;
         }
 
@@ -106,7 +118,7 @@ static int __Pyx_PyType_Ready(PyTypeObject *t) {
         if (gc_was_enabled) {
             PyObject *t, *v, *tb;
             PyErr_Fetch(&t, &v, &tb);
-            ret = PyObject_CallMethodObjArgs(gc, PYUNICODE("enable"), NULL);
+            ret = __Pyx_PyObject_CallNoArg(gc_enable);
             if (likely(ret || r == -1)) {
                 Py_XDECREF(ret);
                 // do not overwrite exceptions raised by PyType_Ready() above
@@ -119,7 +131,6 @@ static int __Pyx_PyType_Ready(PyTypeObject *t) {
                 r = -1;
             }
         }
-        Py_DECREF(gc);
     }
 #endif