gh-100288: Specialise LOAD_ATTR_METHOD for managed dictionaries (GH-100289)

Author: Fidget-Spinner

Include/internal/pycore_opcode.h

@@ -336,6 +336,7 @@ def pseudo_op(name, op, real_ops):
         # These will always push [unbound method, self] onto the stack.
         "LOAD_ATTR_METHOD_LAZY_DICT",
         "LOAD_ATTR_METHOD_NO_DICT",
+        "LOAD_ATTR_METHOD_MANAGED_DICT",
         "LOAD_ATTR_METHOD_WITH_DICT",
         "LOAD_ATTR_METHOD_WITH_VALUES",
     ],

Include/opcode.h

@@ -0,0 +1 @@
+Specialize method loading for objects with ``Py_TPFLAGS_MANAGED_DICT`` set.

Lib/opcode.py

@@ -2717,6 +2717,31 @@ dummy_func(
             JUMPBY(INLINE_CACHE_ENTRIES_LOAD_ATTR);
         }
 
+        // error: LOAD_ATTR has irregular stack effect
+        inst(LOAD_ATTR_METHOD_MANAGED_DICT) {
+            assert(cframe.use_tracing == 0);
+            PyObject *self = TOP();
+            PyTypeObject *self_cls = Py_TYPE(self);
+            _PyLoadMethodCache *cache = (_PyLoadMethodCache *)next_instr;
+            uint32_t type_version = read_u32(cache->type_version);
+            assert(type_version != 0);
+            DEOPT_IF(self_cls->tp_version_tag != type_version, LOAD_ATTR)
+            assert(self_cls->tp_flags & Py_TPFLAGS_MANAGED_DICT);
+            PyDictOrValues dorv = *_PyObject_DictOrValuesPointer(self);
+            DEOPT_IF(_PyDictOrValues_IsValues(dorv), LOAD_ATTR);
+            PyObject *dict = _PyDictOrValues_GetDict(dorv);
+            PyDictKeysObject *keys = (dict == NULL) ? NULL : ((PyDictObject *)dict)->ma_keys;
+            // Note: cache->keys_version can be 0 when dict is NULL.
+            DEOPT_IF(keys != NULL && keys->dk_version != read_u32(cache->keys_version), LOAD_ATTR);
+            STAT_INC(LOAD_ATTR, hit);
+            PyObject *res = read_obj(cache->descr);
+            assert(res != NULL);
+            assert(_PyType_HasFeature(Py_TYPE(res), Py_TPFLAGS_METHOD_DESCRIPTOR));
+            SET_TOP(Py_NewRef(res));
+            PUSH(self);
+            JUMPBY(INLINE_CACHE_ENTRIES_LOAD_ATTR);
+        }
+
         // error: LOAD_ATTR has irregular stack effect
         inst(LOAD_ATTR_METHOD_WITH_DICT) {
             /* Can be either a managed dict, or a tp_dictoffset offset.*/

Misc/NEWS.d/next/Core and Builtins/2022-12-16-08-50-16.gh-issue-100288.5XCk0G.rst

@@ -335,7 +335,6 @@ _PyCode_Quicken(PyCodeObject *code)
 #define SPEC_FAIL_ATTR_BUILTIN_CLASS_METHOD 22
 #define SPEC_FAIL_ATTR_CLASS_METHOD_OBJ 23
 #define SPEC_FAIL_ATTR_OBJECT_SLOT 24
-#define SPEC_FAIL_ATTR_HAS_MANAGED_DICT 25
 #define SPEC_FAIL_ATTR_INSTANCE_ATTRIBUTE 26
 #define SPEC_FAIL_ATTR_METACLASS_ATTRIBUTE 27
 #define SPEC_FAIL_ATTR_PROPERTY_NOT_PY_FUNCTION 28
@@ -1036,11 +1035,14 @@ PyObject *descr, DescriptorClassification kind)
     PyDictKeysObject *keys;
     if (owner_cls->tp_flags & Py_TPFLAGS_MANAGED_DICT) {
         PyDictOrValues dorv = *_PyObject_DictOrValuesPointer(owner);
-        keys = ((PyHeapTypeObject *)owner_cls)->ht_cached_keys;
         if (_PyDictOrValues_IsValues(dorv)) {
+            keys = ((PyHeapTypeObject *)owner_cls)->ht_cached_keys;
             dictkind = MANAGED_VALUES;
         }
         else {
+            PyDictObject *dict = (PyDictObject *)_PyDictOrValues_GetDict(dorv);
+            keys = dict != NULL ? dict->ma_keys : NULL;
+            // User has directly accessed __dict__.
             dictkind = MANAGED_DICT;
         }
     }
@@ -1067,7 +1069,7 @@ PyObject *descr, DescriptorClassification kind)
             }
         }
     }
-    if (dictkind == MANAGED_VALUES || dictkind == OFFSET_DICT) {
+    if (dictkind == MANAGED_VALUES || dictkind == OFFSET_DICT || (dictkind == MANAGED_DICT && keys != NULL)) {
         Py_ssize_t index = _PyDictKeys_StringLookup(keys, name);
         if (index != DKIX_EMPTY) {
             SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_ATTR_SHADOWED);
@@ -1088,8 +1090,11 @@ PyObject *descr, DescriptorClassification kind)
             _py_set_opcode(instr, LOAD_ATTR_METHOD_WITH_VALUES);
             break;
         case MANAGED_DICT:
-            SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_ATTR_HAS_MANAGED_DICT);
-            goto fail;
+            if (keys == NULL) {
+                write_u32(cache->keys_version, 0);
+            }
+            _py_set_opcode(instr, LOAD_ATTR_METHOD_MANAGED_DICT);
+            break;
         case OFFSET_DICT:
             assert(owner_cls->tp_dictoffset > 0 && owner_cls->tp_dictoffset <= INT16_MAX);
             _py_set_opcode(instr, LOAD_ATTR_METHOD_WITH_DICT);