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bpo-45947: Place dict and values pointer at fixed (negative) offset just before GC header. (GH-29879)

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* Place __dict__ immediately before GC header for plain Python objects.

* Fix up lazy dict creation logic to use managed dict pointers.

* Manage values pointer, placing them directly before managed dict pointers.

* Convert hint-based load/store attr specialization target managed dict classes.

* Specialize LOAD_METHOD for managed dict objects.

* Remove unsafe _PyObject_GC_Calloc function.

* Remove unsafe _PyObject_GC_Malloc() function.

* Add comment explaning use of Py_TPFLAGS_MANAGED_DICT.
This commit is contained in:
Mark Shannon 2021-12-07 16:02:53 +00:00 committed by GitHub
parent c7e7a4b969
commit 8319114fee
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
19 changed files with 260 additions and 285 deletions
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1
Include/cpython/object.h
View file

@ -270,7 +270,6 @@ 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 */

3
Include/cpython/objimpl.h
View file

@ -90,9 +90,6 @@ PyAPI_FUNC(int) PyObject_IS_GC(PyObject *obj);
# define _PyGC_FINALIZED(o) PyObject_GC_IsFinalized(o)
#endif
PyAPI_FUNC(PyObject *) _PyObject_GC_Malloc(size_t size);
PyAPI_FUNC(PyObject *) _PyObject_GC_Calloc(size_t size);
/* Test if a type supports weak references */
#define PyType_SUPPORTS_WEAKREFS(t) ((t)->tp_weaklistoffset > 0)

23
Include/internal/pycore_object.h
View file

@ -168,6 +168,15 @@ _PyObject_IS_GC(PyObject *obj)
// Fast inlined version of PyType_IS_GC()
#define _PyType_IS_GC(t) _PyType_HasFeature((t), Py_TPFLAGS_HAVE_GC)
static inline size_t
_PyType_PreHeaderSize(PyTypeObject *tp)
{
return _PyType_IS_GC(tp) * sizeof(PyGC_Head) +
_PyType_HasFeature(tp, Py_TPFLAGS_MANAGED_DICT) * 2 * sizeof(PyObject *);
}
void _PyObject_GC_Link(PyObject *op);
// Usage: assert(_Py_CheckSlotResult(obj, "__getitem__", result != NULL));
extern int _Py_CheckSlotResult(
PyObject *obj,
@ -185,7 +194,19 @@ 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 *);
static inline PyDictValues **_PyObject_ValuesPointer(PyObject *obj)
{
assert(Py_TYPE(obj)->tp_flags & Py_TPFLAGS_MANAGED_DICT);
return ((PyDictValues **)obj)-4;
}
static inline PyObject **_PyObject_ManagedDictPointer(PyObject *obj)
{
assert(Py_TYPE(obj)->tp_flags & Py_TPFLAGS_MANAGED_DICT);
return ((PyObject **)obj)-3;
}
PyObject ** _PyObject_DictPointer(PyObject *);
int _PyObject_VisitInstanceAttributes(PyObject *self, visitproc visit, void *arg);
void _PyObject_ClearInstanceAttributes(PyObject *self);

6
Include/object.h
View file

@ -334,6 +334,12 @@ given type object has a specified feature.
#ifndef Py_LIMITED_API
/* Placement of dict (and values) pointers are managed by the VM, not by the type.
* The VM will automatically set tp_dictoffset. Should not be used for variable sized
* classes, such as classes that extend tuple.
*/
#define Py_TPFLAGS_MANAGED_DICT (1 << 4)
/* 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 */

1
Lib/test/test_stable_abi_ctypes.py
View file

@ -817,7 +817,6 @@ SYMBOL_NAMES = (
"_PyErr_BadInternalCall",
"_PyObject_CallFunction_SizeT",
"_PyObject_CallMethod_SizeT",
"_PyObject_GC_Malloc",
"_PyObject_GC_New",
"_PyObject_GC_NewVar",
"_PyObject_GC_Resize",

4
Lib/test/test_sys.py
View file

@ -1421,8 +1421,8 @@ def delx(self): del self.__x
check((1,2,3), vsize('') + 3*self.P)
# type
# static type: PyTypeObject
fmt = 'P2nPI13Pl4Pn9Pn12PIPP'
s = vsize(fmt)
fmt = 'P2nPI13Pl4Pn9Pn12PIP'
s = vsize('2P' + fmt)
check(int, s)
# class
s = vsize(fmt + # PyTypeObject

3
Misc/NEWS.d/next/Core and Builtins/2021-12-01-14-06-36.bpo-45947.1XPPm_.rst Normal file
View file

@ -0,0 +1,3 @@
Place pointers to dict and values immediately before GC header. This reduces
number of dependent memory loads to access either dict or values from 3 to
1.

3
Misc/stable_abi.txt
View file

@ -1577,9 +1577,6 @@ function _PyObject_CallFunction_SizeT
function _PyObject_CallMethod_SizeT
added 3.2
abi_only
function _PyObject_GC_Malloc
added 3.2
abi_only
function _PyObject_GC_New
added 3.2
abi_only

7
Modules/_testcapimodule.c
View file

@ -5861,6 +5861,7 @@ test_tstate_capi(PyObject *self, PyObject *Py_UNUSED(args))
}
static PyObject *negative_dictoffset(PyObject *, PyObject *);
static PyObject *test_buildvalue_issue38913(PyObject *, PyObject *);
static PyObject *getargs_s_hash_int(PyObject *, PyObject *, PyObject*);
@ -5932,6 +5933,7 @@ static PyMethodDef TestMethods[] = {
{"getbuffer_with_null_view", getbuffer_with_null_view, METH_O},
{"PyBuffer_SizeFromFormat", test_PyBuffer_SizeFromFormat, METH_VARARGS},
{"test_buildvalue_N", test_buildvalue_N, METH_NOARGS},
{"negative_dictoffset", negative_dictoffset, METH_NOARGS},
{"test_buildvalue_issue38913", test_buildvalue_issue38913, METH_NOARGS},
{"get_args", get_args, METH_VARARGS},
{"test_get_statictype_slots", test_get_statictype_slots, METH_NOARGS},
@ -7629,6 +7631,11 @@ PyInit__testcapi(void)
return m;
}
static PyObject *
negative_dictoffset(PyObject *self, PyObject *Py_UNUSED(ignored))
{
return PyType_FromSpec(&HeapCTypeWithNegativeDict_spec);
}
/* Test the C API exposed when PY_SSIZE_T_CLEAN is not defined */

68
Modules/gcmodule.c
View file

@ -69,10 +69,10 @@ module gc
#define NEXT_MASK_UNREACHABLE (1)
/* Get an object's GC head */
#define AS_GC(o) ((PyGC_Head *)(o)-1)
#define AS_GC(o) ((PyGC_Head *)(((char *)(o))-sizeof(PyGC_Head)))
/* Get the object given the GC head */
#define FROM_GC(g) ((PyObject *)(((PyGC_Head *)g)+1))
#define FROM_GC(g) ((PyObject *)(((char *)(g))+sizeof(PyGC_Head)))
static inline int
gc_is_collecting(PyGC_Head *g)
@ -2231,28 +2231,14 @@ PyObject_IS_GC(PyObject *obj)
return _PyObject_IS_GC(obj);
}
static PyObject *
_PyObject_GC_Alloc(int use_calloc, size_t basicsize)
void
_PyObject_GC_Link(PyObject *op)
{
PyGC_Head *g = AS_GC(op);
assert(((uintptr_t)g & (sizeof(uintptr_t)-1)) == 0); // g must be correctly aligned
PyThreadState *tstate = _PyThreadState_GET();
GCState *gcstate = &tstate->interp->gc;
if (basicsize > PY_SSIZE_T_MAX - sizeof(PyGC_Head)) {
return _PyErr_NoMemory(tstate);
}
size_t size = sizeof(PyGC_Head) + basicsize;
PyGC_Head *g;
if (use_calloc) {
g = (PyGC_Head *)PyObject_Calloc(1, size);
}
else {
g = (PyGC_Head *)PyObject_Malloc(size);
}
if (g == NULL) {
return _PyErr_NoMemory(tstate);
}
assert(((uintptr_t)g & 3) == 0); // g must be aligned 4bytes boundary
g->_gc_next = 0;
g->_gc_prev = 0;
gcstate->generations[0].count++; /* number of allocated GC objects */
@ -2266,26 +2252,32 @@ _PyObject_GC_Alloc(int use_calloc, size_t basicsize)
gc_collect_generations(tstate);
gcstate->collecting = 0;
}
PyObject *op = FROM_GC(g);
}
static PyObject *
gc_alloc(size_t basicsize, size_t presize)
{
PyThreadState *tstate = _PyThreadState_GET();
if (basicsize > PY_SSIZE_T_MAX - presize) {
return _PyErr_NoMemory(tstate);
}
size_t size = presize + basicsize;
char *mem = PyObject_Malloc(size);
if (mem == NULL) {
return _PyErr_NoMemory(tstate);
}
((PyObject **)mem)[0] = NULL;
((PyObject **)mem)[1] = NULL;
PyObject *op = (PyObject *)(mem + presize);
_PyObject_GC_Link(op);
return op;
}
PyObject *
_PyObject_GC_Malloc(size_t basicsize)
{
return _PyObject_GC_Alloc(0, basicsize);
}
PyObject *
_PyObject_GC_Calloc(size_t basicsize)
{
return _PyObject_GC_Alloc(1, basicsize);
}
PyObject *
_PyObject_GC_New(PyTypeObject *tp)
{
PyObject *op = _PyObject_GC_Malloc(_PyObject_SIZE(tp));
size_t presize = _PyType_PreHeaderSize(tp);
PyObject *op = gc_alloc(_PyObject_SIZE(tp), presize);
if (op == NULL) {
return NULL;
}
@ -2303,8 +2295,9 @@ _PyObject_GC_NewVar(PyTypeObject *tp, Py_ssize_t nitems)
PyErr_BadInternalCall();
return NULL;
}
size_t presize = _PyType_PreHeaderSize(tp);
size = _PyObject_VAR_SIZE(tp, nitems);
op = (PyVarObject *) _PyObject_GC_Malloc(size);
op = (PyVarObject *)gc_alloc(size, presize);
if (op == NULL) {
return NULL;
}
@ -2333,6 +2326,7 @@ _PyObject_GC_Resize(PyVarObject *op, Py_ssize_t nitems)
void
PyObject_GC_Del(void *op)
{
size_t presize = _PyType_PreHeaderSize(((PyObject *)op)->ob_type);
PyGC_Head *g = AS_GC(op);
if (_PyObject_GC_IS_TRACKED(op)) {
gc_list_remove(g);
@ -2341,7 +2335,7 @@ PyObject_GC_Del(void *op)
if (gcstate->generations[0].count > 0) {
gcstate->generations[0].count--;
}
PyObject_Free(g);
PyObject_Free(((char *)op)-presize);
}
int

68
Objects/dictobject.c
View file

@ -4961,8 +4961,8 @@ static int
init_inline_values(PyObject *obj, PyTypeObject *tp)
{
assert(tp->tp_flags & Py_TPFLAGS_HEAPTYPE);
assert(tp->tp_dictoffset > 0);
assert(tp->tp_inline_values_offset > 0);
// assert(type->tp_dictoffset > 0); -- TO DO Update this assert.
assert(tp->tp_flags & Py_TPFLAGS_MANAGED_DICT);
PyDictKeysObject *keys = CACHED_KEYS(tp);
assert(keys != NULL);
if (keys->dk_usable > 1) {
@ -4979,7 +4979,7 @@ init_inline_values(PyObject *obj, PyTypeObject *tp)
for (int i = 0; i < size; i++) {
values->values[i] = NULL;
}
*((PyDictValues **)((char *)obj + tp->tp_inline_values_offset)) = values;
*_PyObject_ValuesPointer(obj) = values;
return 0;
}
@ -4990,7 +4990,7 @@ _PyObject_InitializeDict(PyObject *obj)
if (tp->tp_dictoffset == 0) {
return 0;
}
if (tp->tp_inline_values_offset) {
if (tp->tp_flags & Py_TPFLAGS_MANAGED_DICT) {
return init_inline_values(obj, tp);
}
PyObject *dict;
@ -5032,7 +5032,7 @@ make_dict_from_instance_attributes(PyDictKeysObject *keys, PyDictValues *values)
PyObject *
_PyObject_MakeDictFromInstanceAttributes(PyObject *obj, PyDictValues *values)
{
assert(Py_TYPE(obj)->tp_inline_values_offset != 0);
assert(Py_TYPE(obj)->tp_flags & Py_TPFLAGS_MANAGED_DICT);
PyDictKeysObject *keys = CACHED_KEYS(Py_TYPE(obj));
return make_dict_from_instance_attributes(keys, values);
}
@ -5042,10 +5042,10 @@ _PyObject_StoreInstanceAttribute(PyObject *obj, PyDictValues *values,
PyObject *name, PyObject *value)
{
assert(PyUnicode_CheckExact(name));
PyTypeObject *tp = Py_TYPE(obj);
PyDictKeysObject *keys = CACHED_KEYS(Py_TYPE(obj));
assert(keys != NULL);
assert(values != NULL);
assert(Py_TYPE(obj)->tp_flags & Py_TPFLAGS_MANAGED_DICT);
int ix = insert_into_dictkeys(keys, name);
if (ix == DKIX_EMPTY) {
if (value == NULL) {
@ -5056,8 +5056,8 @@ _PyObject_StoreInstanceAttribute(PyObject *obj, PyDictValues *values,
if (dict == NULL) {
return -1;
}
*((PyDictValues **)((char *)obj + tp->tp_inline_values_offset)) = NULL;
*((PyObject **) ((char *)obj + tp->tp_dictoffset)) = dict;
*_PyObject_ValuesPointer(obj) = NULL;
*_PyObject_ManagedDictPointer(obj) = dict;
return PyDict_SetItem(dict, name, value);
}
PyObject *old_value = values->values[ix];
@ -5102,17 +5102,23 @@ _PyObject_IsInstanceDictEmpty(PyObject *obj)
if (tp->tp_dictoffset == 0) {
return 1;
}
PyDictValues **values_ptr = _PyObject_ValuesPointer(obj);
if (values_ptr && *values_ptr) {
PyObject **dictptr;
if (tp->tp_flags & Py_TPFLAGS_MANAGED_DICT) {
PyDictValues *values = *_PyObject_ValuesPointer(obj);
if (values) {
PyDictKeysObject *keys = CACHED_KEYS(tp);
for (Py_ssize_t i = 0; i < keys->dk_nentries; i++) {
if ((*values_ptr)->values[i] != NULL) {
if (values->values[i] != NULL) {
return 0;
}
}
return 1;
}
PyObject **dictptr = _PyObject_DictPointer(obj);
dictptr = _PyObject_ManagedDictPointer(obj);
}
else {
dictptr = _PyObject_DictPointer(obj);
}
PyObject *dict = *dictptr;
if (dict == NULL) {
return 1;
@ -5125,7 +5131,7 @@ int
_PyObject_VisitInstanceAttributes(PyObject *self, visitproc visit, void *arg)
{
PyTypeObject *tp = Py_TYPE(self);
assert(tp->tp_inline_values_offset);
assert(Py_TYPE(self)->tp_flags & Py_TPFLAGS_MANAGED_DICT);
PyDictValues **values_ptr = _PyObject_ValuesPointer(self);
if (*values_ptr == NULL) {
return 0;
@ -5141,7 +5147,7 @@ void
_PyObject_ClearInstanceAttributes(PyObject *self)
{
PyTypeObject *tp = Py_TYPE(self);
assert(tp->tp_inline_values_offset);
assert(Py_TYPE(self)->tp_flags & Py_TPFLAGS_MANAGED_DICT);
PyDictValues **values_ptr = _PyObject_ValuesPointer(self);
if (*values_ptr == NULL) {
return;
@ -5156,7 +5162,7 @@ void
_PyObject_FreeInstanceAttributes(PyObject *self)
{
PyTypeObject *tp = Py_TYPE(self);
assert(tp->tp_inline_values_offset);
assert(Py_TYPE(self)->tp_flags & Py_TPFLAGS_MANAGED_DICT);
PyDictValues **values_ptr = _PyObject_ValuesPointer(self);
if (*values_ptr == NULL) {
return;
@ -5171,23 +5177,36 @@ _PyObject_FreeInstanceAttributes(PyObject *self)
PyObject *
PyObject_GenericGetDict(PyObject *obj, void *context)
{
PyObject *dict;
PyTypeObject *tp = Py_TYPE(obj);
if (_PyType_HasFeature(tp, Py_TPFLAGS_MANAGED_DICT)) {
PyDictValues **values_ptr = _PyObject_ValuesPointer(obj);
PyObject **dictptr = _PyObject_ManagedDictPointer(obj);
if (*values_ptr) {
assert(*dictptr == NULL);
*dictptr = dict = make_dict_from_instance_attributes(CACHED_KEYS(tp), *values_ptr);
if (dict != NULL) {
*values_ptr = NULL;
}
}
else if (*dictptr == NULL) {
*dictptr = dict = PyDict_New();
}
else {
dict = *dictptr;
}
}
else {
PyObject **dictptr = _PyObject_DictPointer(obj);
if (dictptr == NULL) {
PyErr_SetString(PyExc_AttributeError,
"This object has no __dict__");
return NULL;
}
PyObject *dict = *dictptr;
dict = *dictptr;
if (dict == NULL) {
PyTypeObject *tp = Py_TYPE(obj);
PyDictValues **values_ptr = _PyObject_ValuesPointer(obj);
if (values_ptr && *values_ptr) {
*dictptr = dict = make_dict_from_instance_attributes(CACHED_KEYS(tp), *values_ptr);
if (dict != NULL) {
*values_ptr = NULL;
}
}
else if (_PyType_HasFeature(tp, Py_TPFLAGS_HEAPTYPE) && CACHED_KEYS(tp)) {
if (_PyType_HasFeature(tp, Py_TPFLAGS_HEAPTYPE) && CACHED_KEYS(tp)) {
dictkeys_incref(CACHED_KEYS(tp));
*dictptr = dict = new_dict_with_shared_keys(CACHED_KEYS(tp));
}
@ -5195,6 +5214,7 @@ PyObject_GenericGetDict(PyObject *obj, void *context)
*dictptr = dict = PyDict_New();
}
}
}
Py_XINCREF(dict);
return dict;
}

5
Objects/exceptions.c
View file

@ -3484,7 +3484,6 @@ _PyErr_TrySetFromCause(const char *format, ...)
PyObject* msg_prefix;
PyObject *exc, *val, *tb;
PyTypeObject *caught_type;
PyObject **dictptr;
PyObject *instance_args;
Py_ssize_t num_args, caught_type_size, base_exc_size;
PyObject *new_exc, *new_val, *new_tb;
@ -3530,9 +3529,7 @@ _PyErr_TrySetFromCause(const char *format, ...)
}
/* Ensure the instance dict is also empty */
dictptr = _PyObject_GetDictPtr(val);
if (dictptr != NULL && *dictptr != NULL &&
PyDict_GET_SIZE(*dictptr) > 0) {
if (!_PyObject_IsInstanceDictEmpty(val)) {
/* While we could potentially copy a non-empty instance dictionary
* to the replacement exception, for now we take the more
* conservative path of leaving exceptions with attributes set

69
Objects/object.c
View file

@ -1073,6 +1073,9 @@ _PyObject_DictPointer(PyObject *obj)
Py_ssize_t dictoffset;
PyTypeObject *tp = Py_TYPE(obj);
if (tp->tp_flags & Py_TPFLAGS_MANAGED_DICT) {
return _PyObject_ManagedDictPointer(obj);
}
dictoffset = tp->tp_dictoffset;
if (dictoffset == 0)
return NULL;
@ -1096,24 +1099,20 @@ _PyObject_DictPointer(PyObject *obj)
PyObject **
_PyObject_GetDictPtr(PyObject *obj)
{
PyObject **dict_ptr = _PyObject_DictPointer(obj);
if (dict_ptr == NULL) {
return NULL;
}
if (*dict_ptr != NULL) {
return dict_ptr;
if ((Py_TYPE(obj)->tp_flags & Py_TPFLAGS_MANAGED_DICT) == 0) {
return _PyObject_DictPointer(obj);
}
PyObject **dict_ptr = _PyObject_ManagedDictPointer(obj);
PyDictValues **values_ptr = _PyObject_ValuesPointer(obj);
if (values_ptr == NULL || *values_ptr == NULL) {
if (*values_ptr == NULL) {
return dict_ptr;
}
assert(*dict_ptr == NULL);
PyObject *dict = _PyObject_MakeDictFromInstanceAttributes(obj, *values_ptr);
if (dict == NULL) {
PyErr_Clear();
return NULL;
}
assert(*dict_ptr == NULL);
assert(*values_ptr != NULL);
*values_ptr = NULL;
*dict_ptr = dict;
return dict_ptr;
@ -1185,10 +1184,12 @@ _PyObject_GetMethod(PyObject *obj, PyObject *name, PyObject **method)
}
}
}
PyDictValues **values_ptr = _PyObject_ValuesPointer(obj);
if (values_ptr && *values_ptr) {
PyDictValues *values;
if ((tp->tp_flags & Py_TPFLAGS_MANAGED_DICT) &&
(values = *_PyObject_ValuesPointer(obj)))
{
assert(*_PyObject_DictPointer(obj) == NULL);
PyObject *attr = _PyObject_GetInstanceAttribute(obj, *values_ptr, name);
PyObject *attr = _PyObject_GetInstanceAttribute(obj, values, name);
if (attr != NULL) {
*method = attr;
Py_XDECREF(descr);
@ -1240,17 +1241,6 @@ _PyObject_GetMethod(PyObject *obj, PyObject *name, PyObject **method)
return 0;
}
PyDictValues **
_PyObject_ValuesPointer(PyObject *obj)
{
PyTypeObject *tp = Py_TYPE(obj);
Py_ssize_t offset = tp->tp_inline_values_offset;
if (offset == 0) {
return NULL;
}
return (PyDictValues **) ((char *)obj + offset);
}
/* Generic GetAttr functions - put these in your tp_[gs]etattro slot. */
PyObject *
@ -1267,7 +1257,6 @@ _PyObject_GenericGetAttrWithDict(PyObject *obj, PyObject *name,
PyObject *descr = NULL;
PyObject *res = NULL;
descrgetfunc f;
Py_ssize_t dictoffset;
PyObject **dictptr;
if (!PyUnicode_Check(name)){
@ -1299,8 +1288,10 @@ _PyObject_GenericGetAttrWithDict(PyObject *obj, PyObject *name,
}
}
if (dict == NULL) {
if ((tp->tp_flags & Py_TPFLAGS_MANAGED_DICT) &&
*_PyObject_ValuesPointer(obj))
{
PyDictValues **values_ptr = _PyObject_ValuesPointer(obj);
if (values_ptr && *values_ptr) {
if (PyUnicode_CheckExact(name)) {
assert(*_PyObject_DictPointer(obj) == NULL);
res = _PyObject_GetInstanceAttribute(obj, *values_ptr, name);
@ -1320,22 +1311,8 @@ _PyObject_GenericGetAttrWithDict(PyObject *obj, PyObject *name,
}
}
else {
/* Inline _PyObject_DictPointer */
dictoffset = tp->tp_dictoffset;
if (dictoffset != 0) {
if (dictoffset < 0) {
Py_ssize_t tsize = Py_SIZE(obj);
if (tsize < 0) {
tsize = -tsize;
}
size_t size = _PyObject_VAR_SIZE(tp, tsize);
_PyObject_ASSERT(obj, size <= PY_SSIZE_T_MAX);
dictoffset += (Py_ssize_t)size;
_PyObject_ASSERT(obj, dictoffset > 0);
_PyObject_ASSERT(obj, dictoffset % SIZEOF_VOID_P == 0);
}
dictptr = (PyObject **) ((char *)obj + dictoffset);
dictptr = _PyObject_DictPointer(obj);
if (dictptr) {
dict = *dictptr;
}
}
@ -1426,9 +1403,8 @@ _PyObject_GenericSetAttrWithDict(PyObject *obj, PyObject *name,
}
if (dict == NULL) {
PyDictValues **values_ptr = _PyObject_ValuesPointer(obj);
if (values_ptr && *values_ptr) {
res = _PyObject_StoreInstanceAttribute(obj, *values_ptr, name, value);
if ((tp->tp_flags & Py_TPFLAGS_MANAGED_DICT) && *_PyObject_ValuesPointer(obj)) {
res = _PyObject_StoreInstanceAttribute(obj, *_PyObject_ValuesPointer(obj), name, value);
}
else {
PyObject **dictptr = _PyObject_DictPointer(obj);
@ -1478,8 +1454,9 @@ PyObject_GenericSetDict(PyObject *obj, PyObject *value, void *context)
{
PyObject **dictptr = _PyObject_GetDictPtr(obj);
if (dictptr == NULL) {
PyDictValues** values_ptr = _PyObject_ValuesPointer(obj);
if (values_ptr != NULL && *values_ptr != NULL) {
if (_PyType_HasFeature(Py_TYPE(obj), Py_TPFLAGS_MANAGED_DICT) &&
*_PyObject_ValuesPointer(obj) != NULL)
{
/* Was unable to convert to dict */
PyErr_NoMemory();
}

97
Objects/typeobject.c
View file

@ -1146,17 +1146,17 @@ _PyType_AllocNoTrack(PyTypeObject *type, Py_ssize_t nitems)
const size_t size = _PyObject_VAR_SIZE(type, nitems+1);
/* note that we need to add one, for the sentinel */
if (_PyType_IS_GC(type)) {
obj = _PyObject_GC_Malloc(size);
}
else {
obj = (PyObject *)PyObject_Malloc(size);
}
if (obj == NULL) {
const size_t presize = _PyType_PreHeaderSize(type);
char *alloc = PyObject_Malloc(size + presize);
if (alloc == NULL) {
return PyErr_NoMemory();
}
obj = (PyObject *)(alloc + presize);
if (presize) {
((PyObject **)alloc)[0] = NULL;
((PyObject **)alloc)[1] = NULL;
_PyObject_GC_Link(obj);
}
memset(obj, '\0', size);
if (type->tp_itemsize == 0) {
@ -1232,7 +1232,7 @@ subtype_traverse(PyObject *self, visitproc visit, void *arg)
assert(base);
}
if (type->tp_inline_values_offset) {
if (type->tp_flags & Py_TPFLAGS_MANAGED_DICT) {
assert(type->tp_dictoffset);
int err = _PyObject_VisitInstanceAttributes(self, visit, arg);
if (err) {
@ -1301,7 +1301,7 @@ subtype_clear(PyObject *self)
/* Clear the instance dict (if any), to break cycles involving only
__dict__ slots (as in the case 'self.__dict__ is self'). */
if (type->tp_inline_values_offset) {
if (type->tp_flags & Py_TPFLAGS_MANAGED_DICT) {
_PyObject_ClearInstanceAttributes(self);
}
if (type->tp_dictoffset != base->tp_dictoffset) {
@ -1360,6 +1360,8 @@ subtype_dealloc(PyObject *self)
int type_needs_decref = (type->tp_flags & Py_TPFLAGS_HEAPTYPE
&& !(base->tp_flags & Py_TPFLAGS_HEAPTYPE));
assert((type->tp_flags & Py_TPFLAGS_MANAGED_DICT) == 0);
/* Call the base tp_dealloc() */
assert(basedealloc);
basedealloc(self);
@ -1445,10 +1447,18 @@ subtype_dealloc(PyObject *self)
}
/* If we added a dict, DECREF it, or free inline values. */
if (type->tp_inline_values_offset) {
if (type->tp_flags & Py_TPFLAGS_MANAGED_DICT) {
PyObject **dictptr = _PyObject_ManagedDictPointer(self);
if (*dictptr != NULL) {
assert(*_PyObject_ValuesPointer(self) == NULL);
Py_DECREF(*dictptr);
*dictptr = NULL;
}
else {
_PyObject_FreeInstanceAttributes(self);
}
if (type->tp_dictoffset && !base->tp_dictoffset) {
}
else if (type->tp_dictoffset && !base->tp_dictoffset) {
PyObject **dictptr = _PyObject_DictPointer(self);
if (dictptr != NULL) {
PyObject *dict = *dictptr;
@ -2243,18 +2253,10 @@ extra_ivars(PyTypeObject *type, PyTypeObject *base)
return t_size != b_size ||
type->tp_itemsize != base->tp_itemsize;
}
if (type->tp_inline_values_offset && base->tp_inline_values_offset == 0 &&
type->tp_inline_values_offset + sizeof(PyDictValues *) == t_size &&
type->tp_flags & Py_TPFLAGS_HEAPTYPE)
t_size -= sizeof(PyDictValues *);
if (type->tp_weaklistoffset && base->tp_weaklistoffset == 0 &&
type->tp_weaklistoffset + sizeof(PyObject *) == t_size &&
type->tp_flags & Py_TPFLAGS_HEAPTYPE)
t_size -= sizeof(PyObject *);
if (type->tp_dictoffset && base->tp_dictoffset == 0 &&
type->tp_dictoffset + sizeof(PyObject *) == t_size &&
type->tp_flags & Py_TPFLAGS_HEAPTYPE)
t_size -= sizeof(PyObject *);
return t_size != b_size;
}
@ -2982,13 +2984,8 @@ type_new_descriptors(const type_new_ctx *ctx, PyTypeObject *type)
}
}
if (ctx->add_dict) {
if (ctx->base->tp_itemsize) {
if (ctx->add_dict && ctx->base->tp_itemsize) {
type->tp_dictoffset = -(long)sizeof(PyObject *);
}
else {
type->tp_dictoffset = slotoffset;
}
slotoffset += sizeof(PyObject *);
}
@ -2997,12 +2994,10 @@ type_new_descriptors(const type_new_ctx *ctx, PyTypeObject *type)
type->tp_weaklistoffset = slotoffset;
slotoffset += sizeof(PyObject *);
}
if (type->tp_dictoffset > 0) {
type->tp_inline_values_offset = slotoffset;
slotoffset += sizeof(PyDictValues *);
}
else {
type->tp_inline_values_offset = 0;
if (ctx->add_dict && ctx->base->tp_itemsize == 0) {
assert((type->tp_flags & Py_TPFLAGS_MANAGED_DICT) == 0);
type->tp_flags |= Py_TPFLAGS_MANAGED_DICT;
type->tp_dictoffset = -slotoffset - sizeof(PyObject *)*3;
}
type->tp_basicsize = slotoffset;
@ -3206,8 +3201,7 @@ type_new_impl(type_new_ctx *ctx)
// Put the proper slots in place
fixup_slot_dispatchers(type);
if (type->tp_inline_values_offset) {
assert(type->tp_dictoffset > 0);
if (type->tp_flags & Py_TPFLAGS_MANAGED_DICT) {
PyHeapTypeObject *et = (PyHeapTypeObject*)type;
et->ht_cached_keys = _PyDict_NewKeysForClass();
}
@ -3594,8 +3588,7 @@ PyType_FromModuleAndSpec(PyObject *module, PyType_Spec *spec, PyObject *bases)
if (PyType_Ready(type) < 0)
goto fail;
if (type->tp_inline_values_offset) {
assert(type->tp_dictoffset > 0);
if (type->tp_flags & Py_TPFLAGS_MANAGED_DICT) {
res->ht_cached_keys = _PyDict_NewKeysForClass();
}
@ -4658,7 +4651,6 @@ compatible_with_tp_base(PyTypeObject *child)
child->tp_itemsize == parent->tp_itemsize &&
child->tp_dictoffset == parent->tp_dictoffset &&
child->tp_weaklistoffset == parent->tp_weaklistoffset &&
child->tp_inline_values_offset == parent->tp_inline_values_offset &&
((child->tp_flags & Py_TPFLAGS_HAVE_GC) ==
(parent->tp_flags & Py_TPFLAGS_HAVE_GC)) &&
(child->tp_dealloc == subtype_dealloc ||
@ -4678,8 +4670,6 @@ same_slots_added(PyTypeObject *a, PyTypeObject *b)
size += sizeof(PyObject *);
if (a->tp_weaklistoffset == size && b->tp_weaklistoffset == size)
size += sizeof(PyObject *);
if (a->tp_inline_values_offset == size && b->tp_inline_values_offset == size)
size += sizeof(PyObject *);
/* Check slots compliance */
if (!(a->tp_flags & Py_TPFLAGS_HEAPTYPE) ||
@ -4729,6 +4719,15 @@ compatible_for_assignment(PyTypeObject* oldto, PyTypeObject* newto, const char*
if (newbase != oldbase &&
(newbase->tp_base != oldbase->tp_base ||
!same_slots_added(newbase, oldbase))) {
goto differs;
}
/* The above does not check for managed __dicts__ */
if ((oldto->tp_flags & Py_TPFLAGS_MANAGED_DICT) ==
((newto->tp_flags & Py_TPFLAGS_MANAGED_DICT)))
{
return 1;
}
differs:
PyErr_Format(PyExc_TypeError,
"%s assignment: "
"'%s' object layout differs from '%s'",
@ -4738,9 +4737,6 @@ compatible_for_assignment(PyTypeObject* oldto, PyTypeObject* newto, const char*
return 0;
}
return 1;
}
static int
object_set_class(PyObject *self, PyObject *value, void *closure)
{
@ -4826,15 +4822,13 @@ object_set_class(PyObject *self, PyObject *value, void *closure)
if (compatible_for_assignment(oldto, newto, "__class__")) {
/* Changing the class will change the implicit dict keys,
* so we must materialize the dictionary first. */
assert(oldto->tp_inline_values_offset == newto->tp_inline_values_offset);
assert((oldto->tp_flags & Py_TPFLAGS_MANAGED_DICT) == (newto->tp_flags & Py_TPFLAGS_MANAGED_DICT));
_PyObject_GetDictPtr(self);
PyDictValues** values_ptr = _PyObject_ValuesPointer(self);
if (values_ptr != NULL && *values_ptr != NULL) {
if (oldto->tp_flags & Py_TPFLAGS_MANAGED_DICT && *_PyObject_ValuesPointer(self)) {
/* Was unable to convert to dict */
PyErr_NoMemory();
return -1;
}
assert(_PyObject_ValuesPointer(self) == NULL || *_PyObject_ValuesPointer(self) == NULL);
if (newto->tp_flags & Py_TPFLAGS_HEAPTYPE) {
Py_INCREF(newto);
}
@ -4980,15 +4974,14 @@ _PyObject_GetState(PyObject *obj, int required)
assert(slotnames == Py_None || PyList_Check(slotnames));
if (required) {
Py_ssize_t basicsize = PyBaseObject_Type.tp_basicsize;
if (Py_TYPE(obj)->tp_dictoffset) {
if (Py_TYPE(obj)->tp_dictoffset &&
(Py_TYPE(obj)->tp_flags & Py_TPFLAGS_MANAGED_DICT) == 0)
{
basicsize += sizeof(PyObject *);
}
if (Py_TYPE(obj)->tp_weaklistoffset) {
basicsize += sizeof(PyObject *);
}
if (Py_TYPE(obj)->tp_inline_values_offset) {
basicsize += sizeof(PyDictValues *);
}
if (slotnames != Py_None) {
basicsize += sizeof(PyObject *) * PyList_GET_SIZE(slotnames);
}
@ -5749,6 +5742,7 @@ inherit_special(PyTypeObject *type, PyTypeObject *base)
if (type->tp_clear == NULL)
type->tp_clear = base->tp_clear;
}
type->tp_flags |= (base->tp_flags & Py_TPFLAGS_MANAGED_DICT);
if (type->tp_basicsize == 0)
type->tp_basicsize = base->tp_basicsize;
@ -5761,7 +5755,6 @@ inherit_special(PyTypeObject *type, PyTypeObject *base)
COPYVAL(tp_itemsize);
COPYVAL(tp_weaklistoffset);
COPYVAL(tp_dictoffset);
COPYVAL(tp_inline_values_offset);
#undef COPYVAL
/* Setup fast subclass flags */

1
PC/python3dll.c
View file

@ -28,7 +28,6 @@ EXPORT_FUNC(_PyArg_VaParseTupleAndKeywords_SizeT)
EXPORT_FUNC(_PyErr_BadInternalCall)
EXPORT_FUNC(_PyObject_CallFunction_SizeT)
EXPORT_FUNC(_PyObject_CallMethod_SizeT)
EXPORT_FUNC(_PyObject_GC_Malloc)
EXPORT_FUNC(_PyObject_GC_New)
EXPORT_FUNC(_PyObject_GC_NewVar)
EXPORT_FUNC(_PyObject_GC_Resize)

24
Python/ceval.c
View file

@ -3599,9 +3599,9 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, InterpreterFrame *frame, int thr
_PyAttrCache *cache1 = &caches[-1].attr;
assert(cache1->tp_version != 0);
DEOPT_IF(tp->tp_version_tag != cache1->tp_version, LOAD_ATTR);
assert(tp->tp_dictoffset > 0);
assert(tp->tp_inline_values_offset > 0);
PyDictValues *values = *(PyDictValues **)(((char *)owner) + tp->tp_inline_values_offset);
assert(tp->tp_dictoffset < 0);
assert(tp->tp_flags & Py_TPFLAGS_MANAGED_DICT);
PyDictValues *values = *_PyObject_ValuesPointer(owner);
DEOPT_IF(values == NULL, LOAD_ATTR);
res = values->values[cache0->index];
DEOPT_IF(res == NULL, LOAD_ATTR);
@ -3633,8 +3633,8 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, InterpreterFrame *frame, int thr
_PyAttrCache *cache1 = &caches[-1].attr;
assert(cache1->tp_version != 0);
DEOPT_IF(tp->tp_version_tag != cache1->tp_version, LOAD_ATTR);
assert(tp->tp_dictoffset > 0);
PyDictObject *dict = *(PyDictObject **)(((char *)owner) + tp->tp_dictoffset);
assert(tp->tp_flags & Py_TPFLAGS_MANAGED_DICT);
PyDictObject *dict = *(PyDictObject **)_PyObject_ManagedDictPointer(owner);
DEOPT_IF(dict == NULL, LOAD_ATTR);
assert(PyDict_CheckExact((PyObject *)dict));
PyObject *name = GETITEM(names, cache0->original_oparg);
@ -3701,9 +3701,8 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, InterpreterFrame *frame, int thr
_PyAttrCache *cache1 = &caches[-1].attr;
assert(cache1->tp_version != 0);
DEOPT_IF(tp->tp_version_tag != cache1->tp_version, STORE_ATTR);
assert(tp->tp_dictoffset > 0);
assert(tp->tp_inline_values_offset > 0);
PyDictValues *values = *(PyDictValues **)(((char *)owner) + tp->tp_inline_values_offset);
assert(tp->tp_flags & Py_TPFLAGS_MANAGED_DICT);
PyDictValues *values = *_PyObject_ValuesPointer(owner);
DEOPT_IF(values == NULL, STORE_ATTR);
STAT_INC(STORE_ATTR, hit);
int index = cache0->index;
@ -3731,8 +3730,8 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, InterpreterFrame *frame, int thr
_PyAttrCache *cache1 = &caches[-1].attr;
assert(cache1->tp_version != 0);
DEOPT_IF(tp->tp_version_tag != cache1->tp_version, STORE_ATTR);
assert(tp->tp_dictoffset > 0);
PyDictObject *dict = *(PyDictObject **)(((char *)owner) + tp->tp_dictoffset);
assert(tp->tp_flags & Py_TPFLAGS_MANAGED_DICT);
PyDictObject *dict = *(PyDictObject **)_PyObject_ManagedDictPointer(owner);
DEOPT_IF(dict == NULL, STORE_ATTR);
assert(PyDict_CheckExact((PyObject *)dict));
PyObject *name = GETITEM(names, cache0->original_oparg);
@ -4506,9 +4505,8 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, InterpreterFrame *frame, int thr
_PyObjectCache *cache2 = &caches[-2].obj;
DEOPT_IF(self_cls->tp_version_tag != cache1->tp_version, LOAD_METHOD);
assert(self_cls->tp_dictoffset > 0);
assert(self_cls->tp_inline_values_offset > 0);
PyDictObject *dict = *(PyDictObject **)(((char *)self) + self_cls->tp_dictoffset);
assert(self_cls->tp_flags & Py_TPFLAGS_MANAGED_DICT);
PyDictObject *dict = *(PyDictObject**)_PyObject_ManagedDictPointer(self);
DEOPT_IF(dict != NULL, LOAD_METHOD);
DEOPT_IF(((PyHeapTypeObject *)self_cls)->ht_cached_keys->dk_version != cache1->dk_version_or_hint, LOAD_METHOD);
STAT_INC(LOAD_METHOD, hit);

48
Python/specialize.c
View file

@ -451,6 +451,7 @@ initial_counter_value(void) {
#define SPEC_FAIL_NON_OBJECT_SLOT 14
#define SPEC_FAIL_READ_ONLY 15
#define SPEC_FAIL_AUDITED_SLOT 16
#define SPEC_FAIL_NOT_MANAGED_DICT 17
/* Methods */
@ -506,7 +507,7 @@ specialize_module_load_attr(
PyObject *value = NULL;
PyObject *getattr;
_Py_IDENTIFIER(__getattr__);
assert(owner->ob_type->tp_inline_values_offset == 0);
assert((owner->ob_type->tp_flags & Py_TPFLAGS_MANAGED_DICT) == 0);
PyDictObject *dict = (PyDictObject *)m->md_dict;
if (dict == NULL) {
SPECIALIZATION_FAIL(opcode, SPEC_FAIL_NO_DICT);
@ -634,17 +635,15 @@ specialize_dict_access(
assert(kind == NON_OVERRIDING || kind == NON_DESCRIPTOR || kind == ABSENT ||
kind == BUILTIN_CLASSMETHOD || kind == PYTHON_CLASSMETHOD);
// No descriptor, or non overriding.
if (type->tp_dictoffset < 0) {
SPECIALIZATION_FAIL(base_op, SPEC_FAIL_OUT_OF_RANGE);
if ((type->tp_flags & Py_TPFLAGS_MANAGED_DICT) == 0) {
SPECIALIZATION_FAIL(base_op, SPEC_FAIL_NOT_MANAGED_DICT);
return 0;
}
if (type->tp_dictoffset > 0) {
PyObject **dictptr = (PyObject **) ((char *)owner + type->tp_dictoffset);
PyObject **dictptr = _PyObject_ManagedDictPointer(owner);
PyDictObject *dict = (PyDictObject *)*dictptr;
if (type->tp_inline_values_offset && dict == NULL) {
if (dict == NULL) {
// Virtual dictionary
PyDictKeysObject *keys = ((PyHeapTypeObject *)type)->ht_cached_keys;
assert(type->tp_inline_values_offset > 0);
assert(PyUnicode_CheckExact(name));
Py_ssize_t index = _PyDictKeys_StringLookup(keys, name);
assert (index != DKIX_ERROR);
@ -655,10 +654,9 @@ specialize_dict_access(
cache1->tp_version = type->tp_version_tag;
cache0->index = (uint16_t)index;
*instr = _Py_MAKECODEUNIT(values_op, _Py_OPARG(*instr));
return 0;
}
else {
if (dict == NULL || !PyDict_CheckExact(dict)) {
if (!PyDict_CheckExact(dict)) {
SPECIALIZATION_FAIL(base_op, SPEC_FAIL_NO_DICT);
return 0;
}
@ -673,28 +671,9 @@ specialize_dict_access(
cache1->dk_version_or_hint = (uint32_t)hint;
cache1->tp_version = type->tp_version_tag;
*instr = _Py_MAKECODEUNIT(hint_op, _Py_OPARG(*instr));
}
return 1;
}
}
assert(type->tp_dictoffset == 0);
/* No attribute in instance dictionary */
switch(kind) {
case NON_OVERRIDING:
case BUILTIN_CLASSMETHOD:
case PYTHON_CLASSMETHOD:
SPECIALIZATION_FAIL(base_op, SPEC_FAIL_NON_OVERRIDING_DESCRIPTOR);
return 0;
case NON_DESCRIPTOR:
/* To do -- Optimize this case */
SPECIALIZATION_FAIL(base_op, SPEC_FAIL_NOT_DESCRIPTOR);
return 0;
case ABSENT:
SPECIALIZATION_FAIL(base_op, SPEC_FAIL_EXPECTED_ERROR);
return 0;
default:
Py_UNREACHABLE();
}
}
int
_Py_Specialize_LoadAttr(PyObject *owner, _Py_CODEUNIT *instr, PyObject *name, SpecializedCacheEntry *cache)
@ -965,12 +944,6 @@ _Py_Specialize_LoadMethod(PyObject *owner, _Py_CODEUNIT *instr, PyObject *name,
}
goto success;
}
// Technically this is fine for bound method calls, but it's uncommon and
// slightly slower at runtime to get dict.
if (owner_cls->tp_dictoffset < 0) {
SPECIALIZATION_FAIL(LOAD_METHOD, SPEC_FAIL_OUT_OF_RANGE);
goto fail;
}
PyObject *descr = NULL;
DesciptorClassification kind = 0;
@ -980,9 +953,8 @@ _Py_Specialize_LoadMethod(PyObject *owner, _Py_CODEUNIT *instr, PyObject *name,
SPECIALIZATION_FAIL(LOAD_METHOD, load_method_fail_kind(kind));
goto fail;
}
if (owner_cls->tp_inline_values_offset) {
PyObject **owner_dictptr = _PyObject_DictPointer(owner);
assert(owner_dictptr);
if (owner_cls->tp_flags & Py_TPFLAGS_MANAGED_DICT) {
PyObject **owner_dictptr = _PyObject_ManagedDictPointer(owner);
if (*owner_dictptr) {
SPECIALIZATION_FAIL(LOAD_METHOD, SPEC_FAIL_IS_ATTR);
goto fail;

5
Python/sysmodule.c
View file

@ -1681,10 +1681,7 @@ _PySys_GetSizeOf(PyObject *o)
return (size_t)-1;
}
/* add gc_head size */
if (_PyObject_IS_GC(o))
return ((size_t)size) + sizeof(PyGC_Head);
return (size_t)size;
return (size_t)size + _PyType_PreHeaderSize(Py_TYPE(o));
}
static PyObject *

9
Tools/gdb/libpython.py
View file

@ -83,6 +83,7 @@ def _sizeof_void_p():
# value computed later, see PyUnicodeObjectPtr.proxy()
_is_pep393 = None
Py_TPFLAGS_MANAGED_DICT = (1 << 4)
Py_TPFLAGS_HEAPTYPE = (1 << 9)
Py_TPFLAGS_LONG_SUBCLASS = (1 << 24)
Py_TPFLAGS_LIST_SUBCLASS = (1 << 25)
@ -507,7 +508,6 @@ def get_attr_dict(self):
tsize = -tsize
size = _PyObject_VAR_SIZE(typeobj, tsize)
dictoffset += size
assert dictoffset > 0
assert dictoffset % _sizeof_void_p() == 0
dictptr = self._gdbval.cast(_type_char_ptr()) + dictoffset
@ -523,12 +523,11 @@ def get_attr_dict(self):
def get_keys_values(self):
typeobj = self.type()
values_offset = int_from_int(typeobj.field('tp_inline_values_offset'))
if values_offset == 0:
has_values = int_from_int(typeobj.field('tp_flags')) & Py_TPFLAGS_MANAGED_DICT
if not has_values:
return None
charptr = self._gdbval.cast(_type_char_ptr()) + values_offset
PyDictValuesPtrPtr = gdb.lookup_type("PyDictValues").pointer().pointer()
valuesptr = charptr.cast(PyDictValuesPtrPtr)
valuesptr = self._gdbval.cast(PyDictValuesPtrPtr) - 4
values = valuesptr.dereference()
if long(values) == 0:
return None