diff options
Diffstat (limited to 'Modules/_collectionsmodule.c')
| -rw-r--r-- | Modules/_collectionsmodule.c | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/Modules/_collectionsmodule.c b/Modules/_collectionsmodule.c index c6c8666..b2783d2 100644 --- a/Modules/_collectionsmodule.c +++ b/Modules/_collectionsmodule.c @@ -1831,6 +1831,16 @@ _count_elements(PyObject *self, PyObject *args) if (mapping_get != NULL && mapping_get == dict_get && mapping_setitem != NULL && mapping_setitem == dict_setitem) { while (1) { + /* Fast path advantages: + 1. Eliminate double hashing + (by re-using the same hash for both the get and set) + 2. Avoid argument overhead of PyObject_CallFunctionObjArgs + (argument tuple creation and parsing) + 3. Avoid indirection through a bound method object + (creates another argument tuple) + 4. Avoid initial increment from zero + (reuse an existing one-object instead) + */ Py_hash_t hash; key = PyIter_Next(it); @@ -1848,13 +1858,13 @@ _count_elements(PyObject *self, PyObject *args) oldval = _PyDict_GetItem_KnownHash(mapping, key, hash); if (oldval == NULL) { if (_PyDict_SetItem_KnownHash(mapping, key, one, hash) == -1) - break; + goto done; } else { newval = PyNumber_Add(oldval, one); if (newval == NULL) - break; + goto done; if (_PyDict_SetItem_KnownHash(mapping, key, newval, hash) == -1) - break; + goto done; Py_CLEAR(newval); } Py_DECREF(key); |