Restore dicts' tp_compare slot, and change dict_richcompare to say it
doesn't know how to do LE, LT, GE, GT. dict_richcompare can't do the
latter any faster than dict_compare can. More importantly, for
cmp(dict1, dict2), Python *first* tries rich compares with EQ, LT, and
GT one at a time, even if the tp_compare slot is defined, and
dict_richcompare called dict_compare for the latter two because
it couldn't do them itself. The result was a lot of wasted calls to
dict_compare. Now dict_richcompare gives up at once the times Python
calls it with LT and GT from try_rich_to_3way_compare(), and dict_compare
is called only once (when Python gets around to trying the tp_compare
slot).
Continued mystery: despite that this cut the number of calls to
dict_compare approximately in half in test_mutants.py, the latter still
runs amazingly slowly. Running under the debugger doesn't show excessive
activity in the dict comparison code anymore, so I'm guessing the culprit
is somewhere else -- but where? Perhaps in the element (key/value)
comparison code? We clearly spend a lot of time figuring out how to
compare things.
diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index b699153..9b5b9f4 100644
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -1160,20 +1160,8 @@
return NULL;
res = (cmp == (op == Py_EQ)) ? Py_True : Py_False;
}
- else {
- cmp = dict_compare((dictobject *)v, (dictobject *)w);
- if (cmp < 0 && PyErr_Occurred())
- return NULL;
- switch (op) {
- case Py_LT: cmp = cmp < 0; break;
- case Py_LE: cmp = cmp <= 0; break;
- case Py_GT: cmp = cmp > 0; break;
- case Py_GE: cmp = cmp >= 0; break;
- default:
- assert(!"op unexpected");
- }
- res = cmp ? Py_True : Py_False;
- }
+ else
+ res = Py_NotImplemented;
Py_INCREF(res);
return res;
}
@@ -1541,7 +1529,7 @@
(printfunc)dict_print, /* tp_print */
(getattrfunc)dict_getattr, /* tp_getattr */
0, /* tp_setattr */
- 0, /* tp_compare */
+ (cmpfunc)dict_compare, /* tp_compare */
(reprfunc)dict_repr, /* tp_repr */
0, /* tp_as_number */
&dict_as_sequence, /* tp_as_sequence */