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GH-121459: Streamline PyObject* to PyStackRef conversions by disallowing NULL pointers. #124894

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Merged
merged 3 commits into from
Oct 7, 2024
Merged

GH-121459: Streamline PyObject* to PyStackRef conversions by disallowing NULL pointers. #124894

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65755d0
Change tests in PyStackRef operations for NULL-ness to asserts
markshannon Sep 24, 2024
183dc9e
Fix bytecodes.c to handle NULLs before passing to stack refs
markshannon Oct 2, 2024
16715ba
Merge branch 'main' into stackref-not-null
markshannon Oct 7, 2024
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14 changes: 9 additions & 5 deletions Include/internal/pycore_stackref.h
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Original file line number Diff line number Diff line change
Expand Up @@ -111,7 +111,8 @@ PyStackRef_AsPyObjectBorrow(_PyStackRef stackref)
static inline PyObject *
PyStackRef_AsPyObjectSteal(_PyStackRef stackref)
{
if (!PyStackRef_IsNull(stackref) && PyStackRef_IsDeferred(stackref)) {
assert(!PyStackRef_IsNull(stackref));
if (PyStackRef_IsDeferred(stackref)) {
return Py_NewRef(PyStackRef_AsPyObjectBorrow(stackref));
}
return PyStackRef_AsPyObjectBorrow(stackref);
Expand All @@ -131,9 +132,10 @@ PyStackRef_AsPyObjectSteal(_PyStackRef stackref)
static inline _PyStackRef
_PyStackRef_FromPyObjectSteal(PyObject *obj)
{
assert(obj != NULL);
// Make sure we don't take an already tagged value.
assert(((uintptr_t)obj & Py_TAG_BITS) == 0);
unsigned int tag = (obj == NULL || _Py_IsImmortal(obj)) ? (Py_TAG_DEFERRED) : Py_TAG_PTR;
unsigned int tag = _Py_IsImmortal(obj) ? (Py_TAG_DEFERRED) : Py_TAG_PTR;
return ((_PyStackRef){.bits = ((uintptr_t)(obj)) | tag});
}
# define PyStackRef_FromPyObjectSteal(obj) _PyStackRef_FromPyObjectSteal(_PyObject_CAST(obj))
Expand Down Expand Up @@ -193,6 +195,7 @@ PyStackRef_FromPyObjectImmortal(PyObject *obj)
# define PyStackRef_CLOSE(REF) \
do { \
_PyStackRef _close_tmp = (REF); \
assert(!PyStackRef_IsNull(_close_tmp)); \
if (!PyStackRef_IsDeferred(_close_tmp)) { \
Py_DECREF(PyStackRef_AsPyObjectBorrow(_close_tmp)); \
} \
Expand All @@ -214,10 +217,11 @@ PyStackRef_FromPyObjectImmortal(PyObject *obj)
static inline _PyStackRef
PyStackRef_DUP(_PyStackRef stackref)
{
assert(!PyStackRef_IsNull(stackref));
if (PyStackRef_IsDeferred(stackref)) {
assert(PyStackRef_IsNull(stackref) ||
_Py_IsImmortal(PyStackRef_AsPyObjectBorrow(stackref)) ||
_PyObject_HasDeferredRefcount(PyStackRef_AsPyObjectBorrow(stackref)));
assert(_Py_IsImmortal(PyStackRef_AsPyObjectBorrow(stackref)) ||
_PyObject_HasDeferredRefcount(PyStackRef_AsPyObjectBorrow(stackref))
);
return stackref;
}
Py_INCREF(PyStackRef_AsPyObjectBorrow(stackref));
Expand Down
32 changes: 19 additions & 13 deletions Python/bytecodes.c
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Expand Up @@ -1922,9 +1922,10 @@ dummy_func(
DECREF_INPUTS();
ERROR_IF(super == NULL, error);
PyObject *name = GETITEM(FRAME_CO_NAMES, oparg >> 2);
attr = PyStackRef_FromPyObjectSteal(PyObject_GetAttr(super, name));
PyObject *attr_o = PyObject_GetAttr(super, name);
Py_DECREF(super);
ERROR_IF(PyStackRef_IsNull(attr), error);
ERROR_IF(attr_o == NULL, error);
attr = PyStackRef_FromPyObjectSteal(attr_o);
null = PyStackRef_NULL;
}

Expand Down Expand Up @@ -2740,9 +2741,10 @@ dummy_func(

inst(GET_ITER, (iterable -- iter)) {
/* before: [obj]; after [getiter(obj)] */
iter = PyStackRef_FromPyObjectSteal(PyObject_GetIter(PyStackRef_AsPyObjectBorrow(iterable)));
PyObject *iter_o = PyObject_GetIter(PyStackRef_AsPyObjectBorrow(iterable));
DECREF_INPUTS();
ERROR_IF(PyStackRef_IsNull(iter), error);
ERROR_IF(iter_o == NULL, error);
iter = PyStackRef_FromPyObjectSteal(iter_o);
}

inst(GET_YIELD_FROM_ITER, (iterable -- iter)) {
Expand Down Expand Up @@ -3052,16 +3054,18 @@ dummy_func(
PyObject *owner_o = PyStackRef_AsPyObjectSteal(owner);
PyObject *name = _Py_SpecialMethods[oparg].name;
PyObject *self_or_null_o;
attr = PyStackRef_FromPyObjectSteal(_PyObject_LookupSpecialMethod(owner_o, name, &self_or_null_o));
if (PyStackRef_IsNull(attr)) {
PyObject *attr_o = _PyObject_LookupSpecialMethod(owner_o, name, &self_or_null_o);
if (attr_o == NULL) {
if (!_PyErr_Occurred(tstate)) {
_PyErr_Format(tstate, PyExc_TypeError,
_Py_SpecialMethods[oparg].error,
Py_TYPE(owner_o)->tp_name);
}
ERROR_IF(true, error);
}
ERROR_IF(PyStackRef_IsNull(attr), error);
self_or_null = PyStackRef_FromPyObjectSteal(self_or_null_o);
attr = PyStackRef_FromPyObjectSteal(attr_o);
self_or_null = self_or_null_o == NULL ?
PyStackRef_NULL : PyStackRef_FromPyObjectSteal(self_or_null_o);
}

inst(WITH_EXCEPT_START, (exit_func, exit_self, lasti, unused, val -- exit_func, exit_self, lasti, unused, val, res)) {
Expand Down Expand Up @@ -3092,9 +3096,10 @@ dummy_func(
(void)lasti; // Shut up compiler warning if asserts are off
PyObject *stack[5] = {NULL, PyStackRef_AsPyObjectBorrow(exit_self), exc, val_o, tb};
int has_self = !PyStackRef_IsNull(exit_self);
res = PyStackRef_FromPyObjectSteal(PyObject_Vectorcall(exit_func_o, stack + 2 - has_self,
(3 + has_self) | PY_VECTORCALL_ARGUMENTS_OFFSET, NULL));
ERROR_IF(PyStackRef_IsNull(res), error);
PyObject *res_o = PyObject_Vectorcall(exit_func_o, stack + 2 - has_self,
(3 + has_self) | PY_VECTORCALL_ARGUMENTS_OFFSET, NULL);
ERROR_IF(res_o == NULL, error);
res = PyStackRef_FromPyObjectSteal(res_o);
}

pseudo(SETUP_FINALLY, (-- unused), (HAS_ARG)) = {
Expand Down Expand Up @@ -4539,9 +4544,10 @@ dummy_func(
/* If value is a unicode object, then we know the result
* of format(value) is value itself. */
if (!PyUnicode_CheckExact(value_o)) {
res = PyStackRef_FromPyObjectSteal(PyObject_Format(value_o, NULL));
PyObject *res_o = PyObject_Format(value_o, NULL);
PyStackRef_CLOSE(value);
ERROR_IF(PyStackRef_IsNull(res), error);
ERROR_IF(res_o == NULL, error);
res = PyStackRef_FromPyObjectSteal(res_o);
}
else {
res = value;
Expand Down
32 changes: 16 additions & 16 deletions Python/executor_cases.c.h
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42 changes: 19 additions & 23 deletions Python/generated_cases.c.h
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