bpo-45340: Don't create object dictionaries unless actually needed (GH-28802)

* Never change types' cached keys. It could invalidate inline attribute objects.

* Lazily create object dictionaries.

* Update specialization of LOAD/STORE_ATTR.

* Don't update shared keys version for deletion of value.

* Update gdb support to handle instance values.

* Rename SPLIT_KEYS opcodes to INSTANCE_VALUE.

5 files changed, 25 insertions, 10 deletions

diff --git a/Include/cpython/object.h b/Include/cpython/object.h
index 5ae6f36..849d5aa 100644
--- a/Include/cpython/object.h
+++ b/Include/cpython/object.h
@@ -270,6 +270,7 @@ struct _typeobject {
 
     destructor tp_finalize;
     vectorcallfunc tp_vectorcall;
+    Py_ssize_t tp_inline_values_offset;
 };
 
 /* The *real* layout of a type object when allocated on the heap */
diff --git a/Include/internal/pycore_dict.h b/Include/internal/pycore_dict.h
index d37ef71..13cb7cc 100644
--- a/Include/internal/pycore_dict.h
+++ b/Include/internal/pycore_dict.h
@@ -101,6 +101,8 @@ extern uint64_t _pydict_global_version;
 
 #define DICT_NEXT_VERSION() (++_pydict_global_version)
 
+PyObject *_PyObject_MakeDictFromInstanceAttributes(PyObject *obj, PyDictValues *values);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/Include/internal/pycore_object.h b/Include/internal/pycore_object.h
index 82dddf1..3c126aa 100644
--- a/Include/internal/pycore_object.h
+++ b/Include/internal/pycore_object.h
@@ -181,6 +181,16 @@ extern int _Py_CheckSlotResult(
 extern PyObject* _PyType_AllocNoTrack(PyTypeObject *type, Py_ssize_t nitems);
 
 extern int _PyObject_InitializeDict(PyObject *obj);
+extern int _PyObject_StoreInstanceAttribute(PyObject *obj, PyDictValues *values,
+                                          PyObject *name, PyObject *value);
+PyObject * _PyObject_GetInstanceAttribute(PyObject *obj, PyDictValues *values,
+                                        PyObject *name);
+PyDictValues ** _PyObject_ValuesPointer(PyObject *);
+PyObject ** _PyObject_DictPointer(PyObject *);
+int _PyObject_VisitInstanceAttributes(PyObject *self, visitproc visit, void *arg);
+void _PyObject_ClearInstanceAttributes(PyObject *self);
+void _PyObject_FreeInstanceAttributes(PyObject *self);
+int _PyObject_IsInstanceDictEmpty(PyObject *);
 
 #ifdef __cplusplus
 }
diff --git a/Include/object.h b/Include/object.h
index c3062cb..7f050b8 100644
--- a/Include/object.h
+++ b/Include/object.h
@@ -333,6 +333,7 @@ given type object has a specified feature.
 */
 
 #ifndef Py_LIMITED_API
+
 /* Set if instances of the type object are treated as sequences for pattern matching */
 #define Py_TPFLAGS_SEQUENCE (1 << 5)
 /* Set if instances of the type object are treated as mappings for pattern matching */
diff --git a/Include/opcode.h b/Include/opcode.h
index 8817a4d..15f7226 100644
--- a/Include/opcode.h
+++ b/Include/opcode.h
@@ -147,7 +147,7 @@ extern "C" {
 #define BINARY_SUBSCR_DICT       39
 #define JUMP_ABSOLUTE_QUICK      40
 #define LOAD_ATTR_ADAPTIVE       41
-#define LOAD_ATTR_SPLIT_KEYS     42
+#define LOAD_ATTR_INSTANCE_VALUE  42
 #define LOAD_ATTR_WITH_HINT      43
 #define LOAD_ATTR_SLOT           44
 #define LOAD_ATTR_MODULE         45
@@ -158,15 +158,16 @@ extern "C" {
 #define LOAD_METHOD_CACHED       80
 #define LOAD_METHOD_CLASS        81
 #define LOAD_METHOD_MODULE       87
-#define STORE_ATTR_ADAPTIVE      88
-#define STORE_ATTR_SPLIT_KEYS   120
-#define STORE_ATTR_SLOT         122
-#define STORE_ATTR_WITH_HINT    123
-#define LOAD_FAST__LOAD_FAST    127
-#define STORE_FAST__LOAD_FAST   128
-#define LOAD_FAST__LOAD_CONST   134
-#define LOAD_CONST__LOAD_FAST   140
-#define STORE_FAST__STORE_FAST  143
+#define LOAD_METHOD_NO_DICT      88
+#define STORE_ATTR_ADAPTIVE     120
+#define STORE_ATTR_INSTANCE_VALUE 122
+#define STORE_ATTR_SLOT         123
+#define STORE_ATTR_WITH_HINT    127
+#define LOAD_FAST__LOAD_FAST    128
+#define STORE_FAST__LOAD_FAST   134
+#define LOAD_FAST__LOAD_CONST   140
+#define LOAD_CONST__LOAD_FAST   143
+#define STORE_FAST__STORE_FAST  149
 #define DO_TRACING              255
 #ifdef NEED_OPCODE_JUMP_TABLES
 static uint32_t _PyOpcode_RelativeJump[8] = {