A modest speedup of object deallocation. call_finalizer() did rather a lot of work: it had to save and restore the current exception around a call to lookup_maybe(), because that could fail in rare cases, and most objects don't have a __del__ method, so the whole exercise was usually a waste of time. Changed this to cache the __del__ method in the type object just like all other special methods, in a new slot tp_del. So now subtype_dealloc() can test whether tp_del is NULL and skip the whole exercise if it is. The new slot doesn't need a new flag bit: subtype_dealloc() is only called if the type was dynamically allocated by type_new(), so it's guaranteed to have all current slots. Types defined in C cannot fill in tp_del with a function of their own, so there's no corresponding "wrapper". (That functionality is already available through tp_dealloc.)

--- a/Include/object.h	Thu Aug 08 20:39:30 2002 +0000
+++ b/Include/object.h	Thu Aug 08 20:55:20 2002 +0000
@@ -315,6 +315,7 @@
 	PyObject *tp_cache;
 	PyObject *tp_subclasses;
 	PyObject *tp_weaklist;
+	destructor tp_del;
 
 #ifdef COUNT_ALLOCS
 	/* these must be last and never explicitly initialized */