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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
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GPG key ID: 4AEE18F83AFDEB23
19 changed files with 260 additions and 285 deletions
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24
Python/ceval.c
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@ -3599,9 +3599,9 @@ check_eval_breaker:
_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 @@ check_eval_breaker:
_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 @@ check_eval_breaker:
_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 @@ check_eval_breaker:
_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 @@ check_eval_breaker:
_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);