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Issue #25557: Refactor _PyDict_LoadGlobal() 

Don't fallback to PyDict_GetItemWithError() if the hash is unknown: compute the
hash instead. Add also comments to explain the optimization a little bit.
This commit is contained in:
Victor Stinner 2015-11-20 09:24:02 +01:00
parent c50ec007ff
commit b4efc963d6
2 changed files with 38 additions and 28 deletions
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49
Objects/dictobject.c
View File

@ -1165,39 +1165,42 @@ _PyDict_GetItemIdWithError(PyObject *dp, struct _Py_Identifier *key)
return PyDict_GetItemWithError(dp, kv);
}
/* Fast version of global value lookup.
/* Fast version of global value lookup (LOAD_GLOBAL).
* Lookup in globals, then builtins.
*
* Raise an exception and return NULL if an error occurred (ex: computing the
* key hash failed, key comparison failed, ...). Return NULL if the key doesn't
* exist. Return the value if the key exists.
*/
PyObject *
_PyDict_LoadGlobal(PyDictObject *globals, PyDictObject *builtins, PyObject *key)
{
PyObject *x;
if (PyUnicode_CheckExact(key)) {
Py_hash_t hash;
PyDictKeyEntry *entry;
PyObject **value_addr;
Py_hash_t hash = ((PyASCIIObject *)key)->hash;
if (hash != -1) {
PyDictKeyEntry *e;
e = globals->ma_keys->dk_lookup(globals, key, hash, &value_addr);
if (e == NULL) {
PyObject *value;
if (!PyUnicode_CheckExact(key) ||
(hash = ((PyASCIIObject *) key)->hash) == -1)
{
hash = PyObject_Hash(key);
if (hash == -1)
return NULL;
}
x = *value_addr;
if (x != NULL)
return x;
e = builtins->ma_keys->dk_lookup(builtins, key, hash, &value_addr);
if (e == NULL) {
/* namespace 1: globals */
entry = globals->ma_keys->dk_lookup(globals, key, hash, &value_addr);
if (entry == NULL)
return NULL;
}
x = *value_addr;
return x;
}
}
x = PyDict_GetItemWithError((PyObject *)globals, key);
if (x != NULL)
return x;
if (PyErr_Occurred())
value = *value_addr;
if (value != NULL)
return value;
/* namespace 2: builtins */
entry = builtins->ma_keys->dk_lookup(builtins, key, hash, &value_addr);
if (entry == NULL)
return NULL;
return PyDict_GetItemWithError((PyObject *)builtins, key);
return *value_addr;
}
/* CAUTION: PyDict_SetItem() must guarantee that it won't resize the

11
Python/ceval.c
View File

@ -2347,26 +2347,33 @@ PyEval_EvalFrameEx(PyFrameObject *f, int throwflag)
PyObject *name = GETITEM(names, oparg);
PyObject *v;
if (PyDict_CheckExact(f->f_globals)
&& PyDict_CheckExact(f->f_builtins)) {
&& PyDict_CheckExact(f->f_builtins))
{
v = _PyDict_LoadGlobal((PyDictObject *)f->f_globals,
(PyDictObject *)f->f_builtins,
name);
if (v == NULL) {
if (!_PyErr_OCCURRED())
if (!_PyErr_OCCURRED()) {
/* _PyDict_LoadGlobal() returns NULL without raising
* an exception if the key doesn't exist */
format_exc_check_arg(PyExc_NameError,
NAME_ERROR_MSG, name);
}
goto error;
}
Py_INCREF(v);
}
else {
/* Slow-path if globals or builtins is not a dict */
/* namespace 1: globals */
v = PyObject_GetItem(f->f_globals, name);
if (v == NULL) {
if (!PyErr_ExceptionMatches(PyExc_KeyError))
goto error;
PyErr_Clear();
/* namespace 2: builtins */
v = PyObject_GetItem(f->f_builtins, name);
if (v == NULL) {
if (PyErr_ExceptionMatches(PyExc_KeyError))