Variation of patch # 1624059 to speed up checking if an object is a subclass

of some of the common builtin types.

Use a bit in tp_flags for each common builtin type.  Check the bit
to determine if any instance is a subclass of these common types.
The check avoids a function call and O(n) search of the base classes.
The check is done in the various Py*_Check macros rather than calling
PyType_IsSubtype().

All the bits are set in tp_flags when the type is declared
in the Objects/*object.c files because PyType_Ready() is not called
for all the types.  Should PyType_Ready() be called for all types?
If so and the change is made, the changes to the Objects/*object.c files
can be reverted (remove setting the tp_flags).  Objects/typeobject.c
would also have to be modified to add conditions
for Py*_CheckExact() in addition to each the PyType_IsSubtype check.

1 files changed, 3 insertions, 5 deletions

diff --git a/Include/pyerrors.h b/Include/pyerrors.h
index 9532e32..9671692 100644
--- a/Include/pyerrors.h
+++ b/Include/pyerrors.h
@@ -95,14 +95,12 @@ PyAPI_FUNC(void) PyErr_NormalizeException(PyObject**, PyObject**, PyObject**);
 /* */
 
 #define PyExceptionClass_Check(x)					\
-	(PyClass_Check((x))						\
-	 || (PyType_Check((x)) && PyType_IsSubtype(			\
-		     (PyTypeObject*)(x), (PyTypeObject*)PyExc_BaseException)))
-
+	(PyClass_Check((x)) || (PyType_Check((x)) &&			\
+	  PyType_FastSubclass((PyTypeObject*)(x), Py_TPFLAGS_BASE_EXC_SUBCLASS)))
 
 #define PyExceptionInstance_Check(x)			\
 	(PyInstance_Check((x)) ||			\
-	 (PyType_IsSubtype((x)->ob_type, (PyTypeObject*)PyExc_BaseException)))
+	 PyType_FastSubclass((x)->ob_type, Py_TPFLAGS_BASE_EXC_SUBCLASS))
 
 #define PyExceptionClass_Name(x)				   \
 	(PyClass_Check((x))					   \