bpo-45107: Specialize LOAD_METHOD for instances with dict.

Include/internal/pycore_object.h

@@ -227,6 +227,8 @@ static inline PyObject **_PyObject_ManagedDictPointer(PyObject *obj)
     return ((PyObject **)obj)-3;
 }
 
+#define MANAGED_DICT_OFFSET (((int)sizeof(PyObject *))*-3)
+
 extern PyObject ** _PyObject_DictPointer(PyObject *);
 extern int _PyObject_VisitInstanceAttributes(PyObject *self, visitproc visit, void *arg);
 extern void _PyObject_ClearInstanceAttributes(PyObject *self);

Lib/opcode.py

@@ -260,10 +260,11 @@ def jabs_op(name, op):
     "LOAD_GLOBAL_MODULE",
     "LOAD_GLOBAL_BUILTIN",
     "LOAD_METHOD_ADAPTIVE",
-    "LOAD_METHOD_CACHED",
     "LOAD_METHOD_CLASS",
     "LOAD_METHOD_MODULE",
     "LOAD_METHOD_NO_DICT",
+    "LOAD_METHOD_WITH_DICT",
+    "LOAD_METHOD_WITH_VALUES",
     "PRECALL_ADAPTIVE",
     "PRECALL_BUILTIN_CLASS",
     "PRECALL_NO_KW_BUILTIN_O",

Misc/NEWS.d/next/Core and Builtins/2022-02-23-15-26-02.bpo-45107.axcgHn.rst

@@ -0,0 +1 @@
+Specialize ``LOAD_METHOD`` for instances with a dict.

Python/ceval.c

@@ -4424,15 +4424,15 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, InterpreterFrame *frame, int thr
             }
         }
 
-        TARGET(LOAD_METHOD_CACHED) {
+        TARGET(LOAD_METHOD_WITH_VALUES) {
             /* LOAD_METHOD, with cached method object */
             assert(cframe.use_tracing == 0);
             PyObject *self = TOP();
             PyTypeObject *self_cls = Py_TYPE(self);
             SpecializedCacheEntry *caches = GET_CACHE();
             _PyAttrCache *cache1 = &caches[-1].attr;
             _PyObjectCache *cache2 = &caches[-2].obj;
-
+            assert(cache1->tp_version != 0);
             DEOPT_IF(self_cls->tp_version_tag != cache1->tp_version, LOAD_METHOD);
             assert(self_cls->tp_flags & Py_TPFLAGS_MANAGED_DICT);
             PyDictObject *dict = *(PyDictObject**)_PyObject_ManagedDictPointer(self);
@@ -4448,6 +4448,38 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, InterpreterFrame *frame, int thr
             NOTRACE_DISPATCH();
         }
 
+        TARGET(LOAD_METHOD_WITH_DICT) {
+            /* LOAD_METHOD, with a dict
+             Can be either a managed dict, or a tp_dictoffset offset.*/
+            assert(cframe.use_tracing == 0);
+            PyObject *self = TOP();
+            PyTypeObject *self_cls = Py_TYPE(self);
+            SpecializedCacheEntry *caches = GET_CACHE();
+            _PyAdaptiveEntry *cache0 = &caches[0].adaptive;
+            _PyAttrCache *cache1 = &caches[-1].attr;
+            _PyObjectCache *cache2 = &caches[-2].obj;
+
+            DEOPT_IF(self_cls->tp_version_tag != cache1->tp_version, LOAD_METHOD);
+            /* Treat index as a signed 16 bit value */
+            int dictoffset = *(int16_t *)&cache0->index;
+            PyDictObject **dictptr = (PyDictObject**)(((char *)self)+dictoffset);
+            assert(
+                dictoffset == MANAGED_DICT_OFFSET ||
+                (dictoffset == self_cls->tp_dictoffset && dictoffset > 0)
+            );
+            PyDictObject *dict = *dictptr;
+            DEOPT_IF(dict == NULL, LOAD_METHOD);
+            DEOPT_IF(dict->ma_keys->dk_version != cache1->dk_version, LOAD_METHOD);
+            STAT_INC(LOAD_METHOD, hit);
+            PyObject *res = cache2->obj;
+            assert(res != NULL);
+            assert(_PyType_HasFeature(Py_TYPE(res), Py_TPFLAGS_METHOD_DESCRIPTOR));
+            Py_INCREF(res);
+            SET_TOP(res);
+            PUSH(self);
+            NOTRACE_DISPATCH();
+        }
+
         TARGET(LOAD_METHOD_NO_DICT) {
             assert(cframe.use_tracing == 0);
             PyObject *self = TOP();

Python/specialize.c

@@ -1062,6 +1062,13 @@ specialize_class_load_method(PyObject *owner, _Py_CODEUNIT *instr, PyObject *nam
     }
 }
 
+typedef enum {
+    MANAGED_VALUES = 1,
+    MANAGED_DICT = 2,
+    OFFSET_DICT = 3,
+    NO_DICT = 4
+} ObjectDictKind;
+
 // Please collect stats carefully before and after modifying. A subtle change
 // can cause a significant drop in cache hits. A possible test is
 // python.exe -m test_typing test_re test_dis test_zlib.
@@ -1071,8 +1078,8 @@ _Py_Specialize_LoadMethod(PyObject *owner, _Py_CODEUNIT *instr, PyObject *name,
     _PyAdaptiveEntry *cache0 = &cache->adaptive;
     _PyAttrCache *cache1 = &cache[-1].attr;
     _PyObjectCache *cache2 = &cache[-2].obj;
-
     PyTypeObject *owner_cls = Py_TYPE(owner);
+
     if (PyModule_CheckExact(owner)) {
         int err = specialize_module_load_attr(owner, instr, name, cache0,
             LOAD_METHOD, LOAD_METHOD_MODULE);
@@ -1102,13 +1109,39 @@ _Py_Specialize_LoadMethod(PyObject *owner, _Py_CODEUNIT *instr, PyObject *name,
         SPECIALIZATION_FAIL(LOAD_METHOD, load_method_fail_kind(kind));
         goto fail;
     }
+    ObjectDictKind dictkind;
+    PyDictKeysObject *keys;
     if (owner_cls->tp_flags & Py_TPFLAGS_MANAGED_DICT) {
-        PyObject **owner_dictptr = _PyObject_ManagedDictPointer(owner);
-        if (*owner_dictptr) {
-            SPECIALIZATION_FAIL(LOAD_METHOD, SPEC_FAIL_LOAD_METHOD_HAS_MANAGED_DICT);
+        PyObject *dict = *_PyObject_ManagedDictPointer(owner);
+        keys = ((PyHeapTypeObject *)owner_cls)->ht_cached_keys;
+        if (dict == NULL) {
+            dictkind = MANAGED_VALUES;
+        }
+        else {
+            dictkind = MANAGED_DICT;
+        }
+    }
+    else {
+        Py_ssize_t dictoffset = owner_cls->tp_dictoffset;
+        if (dictoffset < 0 || dictoffset > INT16_MAX) {
+            SPECIALIZATION_FAIL(LOAD_METHOD, SPEC_FAIL_OUT_OF_RANGE);
             goto fail;
         }
-        PyDictKeysObject *keys = ((PyHeapTypeObject *)owner_cls)->ht_cached_keys;
+        if (dictoffset == 0) {
+            dictkind = NO_DICT;
+            keys = NULL;
+        }
+        else {
+            PyObject *dict = *(PyObject **) ((char *)owner + dictoffset);
+            if (dict == NULL) {
+                SPECIALIZATION_FAIL(LOAD_METHOD, SPEC_FAIL_NO_DICT);
+                goto fail;
+            }
+            keys = ((PyDictObject *)dict)->ma_keys;
+            dictkind = OFFSET_DICT;
+        }
+    }
+    if (dictkind != NO_DICT) {
         Py_ssize_t index = _PyDictKeys_StringLookup(keys, name);
         if (index != DKIX_EMPTY) {
             SPECIALIZATION_FAIL(LOAD_METHOD, SPEC_FAIL_LOAD_METHOD_IS_ATTR);
@@ -1120,16 +1153,23 @@ _Py_Specialize_LoadMethod(PyObject *owner, _Py_CODEUNIT *instr, PyObject *name,
             goto fail;
         }
         cache1->dk_version = keys_version;
-        *instr = _Py_MAKECODEUNIT(LOAD_METHOD_CACHED, _Py_OPARG(*instr));
     }
-    else {
-        if (owner_cls->tp_dictoffset == 0) {
+    switch(dictkind) {
+        case NO_DICT:
             *instr = _Py_MAKECODEUNIT(LOAD_METHOD_NO_DICT, _Py_OPARG(*instr));
-        }
-        else {
-            SPECIALIZATION_FAIL(LOAD_METHOD, SPEC_FAIL_LOAD_METHOD_HAS_DICT);
-            goto fail;
-        }
+            break;
+        case MANAGED_VALUES:
+            *instr = _Py_MAKECODEUNIT(LOAD_METHOD_WITH_VALUES, _Py_OPARG(*instr));
+            break;
+        case MANAGED_DICT:
+            *(int16_t *)&cache0->index = (int16_t)MANAGED_DICT_OFFSET;
+            *instr = _Py_MAKECODEUNIT(LOAD_METHOD_WITH_DICT, _Py_OPARG(*instr));
+            break;
+        case OFFSET_DICT:
+            assert(owner_cls->tp_dictoffset > 0 && owner_cls->tp_dictoffset <= INT16_MAX);
+            cache0->index = (uint16_t)owner_cls->tp_dictoffset;
+            *instr = _Py_MAKECODEUNIT(LOAD_METHOD_WITH_DICT, _Py_OPARG(*instr));
+            break;
     }
     /* `descr` is borrowed. This is safe for methods (even inherited ones from
     *  super classes!) as long as tp_version_tag is validated for two main reasons: