https://github.com/python/cpython/commit/cbe6ebe15b3b8db00d3ca82a408cfd62b6d93b7d
commit: cbe6ebe15b3b8db00d3ca82a408cfd62b6d93b7d
branch: main
author: Kumar Aditya <kumaradi...@python.org>
committer: kumaraditya303 <kumaradi...@python.org>
date: 2025-07-28T22:04:57+05:30
summary:
gh-134043: use stackrefs for dict lookup in `_PyObject_GetMethodStackRef`
(#136412)
Co-authored-by: Sam Gross <colesb...@gmail.com>
files:
M Include/internal/pycore_dict.h
M Include/internal/pycore_stackref.h
M Objects/dictobject.c
M Objects/object.c
diff --git a/Include/internal/pycore_dict.h b/Include/internal/pycore_dict.h
index 25bb224921aa8b..6ab569393e5ce1 100644
--- a/Include/internal/pycore_dict.h
+++ b/Include/internal/pycore_dict.h
@@ -113,6 +113,8 @@ extern Py_ssize_t _Py_dict_lookup(PyDictObject *mp,
PyObject *key, Py_hash_t has
extern Py_ssize_t _Py_dict_lookup_threadsafe(PyDictObject *mp, PyObject *key,
Py_hash_t hash, PyObject **value_addr);
extern Py_ssize_t _Py_dict_lookup_threadsafe_stackref(PyDictObject *mp,
PyObject *key, Py_hash_t hash, _PyStackRef *value_addr);
+extern int _PyDict_GetMethodStackRef(PyDictObject *dict, PyObject *name,
_PyStackRef *method);
+
extern Py_ssize_t _PyDict_LookupIndex(PyDictObject *, PyObject *);
extern Py_ssize_t _PyDictKeys_StringLookup(PyDictKeysObject* dictkeys,
PyObject *key);
diff --git a/Include/internal/pycore_stackref.h
b/Include/internal/pycore_stackref.h
index 6bf82d8322f508..c4e8f10fe05276 100644
--- a/Include/internal/pycore_stackref.h
+++ b/Include/internal/pycore_stackref.h
@@ -839,6 +839,13 @@ _Py_TryXGetStackRef(PyObject **src, _PyStackRef *out)
#endif
+#define PyStackRef_XSETREF(dst, src) \
+ do { \
+ _PyStackRef _tmp_dst_ref = (dst); \
+ (dst) = (src); \
+ PyStackRef_XCLOSE(_tmp_dst_ref); \
+ } while(0)
+
// Like Py_VISIT but for _PyStackRef fields
#define _Py_VISIT_STACKREF(ref) \
do { \
diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index 0ed52ac5e87b6e..928b905aaedb1b 100644
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -1581,32 +1581,47 @@ _Py_dict_lookup_threadsafe(PyDictObject *mp, PyObject
*key, Py_hash_t hash, PyOb
return ix;
}
+static Py_ssize_t
+lookup_threadsafe_unicode(PyDictKeysObject *dk, PyObject *key, Py_hash_t hash,
_PyStackRef *value_addr)
+{
+ assert(dk->dk_kind == DICT_KEYS_UNICODE);
+ assert(PyUnicode_CheckExact(key));
+
+ Py_ssize_t ix = unicodekeys_lookup_unicode_threadsafe(dk, key, hash);
+ if (ix == DKIX_EMPTY) {
+ *value_addr = PyStackRef_NULL;
+ return ix;
+ }
+ else if (ix >= 0) {
+ PyObject **addr_of_value = &DK_UNICODE_ENTRIES(dk)[ix].me_value;
+ PyObject *value = _Py_atomic_load_ptr(addr_of_value);
+ if (value == NULL) {
+ *value_addr = PyStackRef_NULL;
+ return DKIX_EMPTY;
+ }
+ if (_PyObject_HasDeferredRefcount(value)) {
+ *value_addr = (_PyStackRef){ .bits = (uintptr_t)value |
Py_TAG_DEFERRED };
+ return ix;
+ }
+ if (_Py_TryIncrefCompare(addr_of_value, value)) {
+ *value_addr = PyStackRef_FromPyObjectSteal(value);
+ return ix;
+ }
+ return DKIX_KEY_CHANGED;
+ }
+ assert(ix == DKIX_KEY_CHANGED);
+ return ix;
+}
+
Py_ssize_t
_Py_dict_lookup_threadsafe_stackref(PyDictObject *mp, PyObject *key, Py_hash_t
hash, _PyStackRef *value_addr)
{
PyDictKeysObject *dk = _Py_atomic_load_ptr(&mp->ma_keys);
if (dk->dk_kind == DICT_KEYS_UNICODE && PyUnicode_CheckExact(key)) {
- Py_ssize_t ix = unicodekeys_lookup_unicode_threadsafe(dk, key, hash);
- if (ix == DKIX_EMPTY) {
- *value_addr = PyStackRef_NULL;
+ Py_ssize_t ix = lookup_threadsafe_unicode(dk, key, hash, value_addr);
+ if (ix != DKIX_KEY_CHANGED) {
return ix;
}
- else if (ix >= 0) {
- PyObject **addr_of_value = &DK_UNICODE_ENTRIES(dk)[ix].me_value;
- PyObject *value = _Py_atomic_load_ptr(addr_of_value);
- if (value == NULL) {
- *value_addr = PyStackRef_NULL;
- return DKIX_EMPTY;
- }
- if (_PyObject_HasDeferredRefcount(value)) {
- *value_addr = (_PyStackRef){ .bits = (uintptr_t)value |
Py_TAG_DEFERRED };
- return ix;
- }
- if (_Py_TryIncrefCompare(addr_of_value, value)) {
- *value_addr = PyStackRef_FromPyObjectSteal(value);
- return ix;
- }
- }
}
PyObject *obj;
@@ -1646,6 +1661,46 @@ _Py_dict_lookup_threadsafe_stackref(PyDictObject *mp,
PyObject *key, Py_hash_t h
#endif
+// Looks up the unicode key `key` in the dictionary. Note that `*method` may
+// already contain a valid value! See _PyObject_GetMethodStackRef().
+int
+_PyDict_GetMethodStackRef(PyDictObject *mp, PyObject *key, _PyStackRef *method)
+{
+ assert(PyUnicode_CheckExact(key));
+ Py_hash_t hash = hash_unicode_key(key);
+
+#ifdef Py_GIL_DISABLED
+ PyDictKeysObject *dk = _Py_atomic_load_ptr_acquire(&mp->ma_keys);
+ if (dk->dk_kind == DICT_KEYS_UNICODE) {
+ _PyStackRef ref;
+ Py_ssize_t ix = lookup_threadsafe_unicode(dk, key, hash, &ref);
+ if (ix >= 0) {
+ assert(!PyStackRef_IsNull(ref));
+ PyStackRef_XSETREF(*method, ref);
+ return 1;
+ }
+ else if (ix == DKIX_EMPTY) {
+ return 0;
+ }
+ assert(ix == DKIX_KEY_CHANGED);
+ }
+#endif
+
+ PyObject *obj;
+ Py_INCREF(mp);
+ Py_ssize_t ix = _Py_dict_lookup_threadsafe(mp, key, hash, &obj);
+ Py_DECREF(mp);
+ if (ix == DKIX_ERROR) {
+ PyStackRef_CLEAR(*method);
+ return -1;
+ }
+ else if (ix >= 0 && obj != NULL) {
+ PyStackRef_XSETREF(*method, PyStackRef_FromPyObjectSteal(obj));
+ return 1;
+ }
+ return 0; // not found
+}
+
int
_PyDict_HasOnlyStringKeys(PyObject *dict)
{
diff --git a/Objects/object.c b/Objects/object.c
index 3ed7d55593dffa..479f4176a46039 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -1753,20 +1753,15 @@ _PyObject_GetMethodStackRef(PyThreadState *ts, PyObject
*obj,
}
}
if (dict != NULL) {
- // TODO: use _Py_dict_lookup_threadsafe_stackref
- Py_INCREF(dict);
- PyObject *value;
- if (PyDict_GetItemRef(dict, name, &value) != 0) {
- // found or error
- Py_DECREF(dict);
- PyStackRef_CLEAR(*method);
- if (value != NULL) {
- *method = PyStackRef_FromPyObjectSteal(value);
- }
+ assert(PyUnicode_CheckExact(name));
+ int found = _PyDict_GetMethodStackRef((PyDictObject *)dict, name,
method);
+ if (found < 0) {
+ assert(PyStackRef_IsNull(*method));
+ return -1;
+ }
+ else if (found) {
return 0;
}
- // not found
- Py_DECREF(dict);
}
if (meth_found) {
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