#include "Python.h"

#include "pycore_abstract.h" // _PyIndex_Check()

#include "pycore_ceval.h" // _PyEval_GetBuiltin()

#include "pycore_critical_section.h" // _Py_CRITICAL_SECTION_ASSERT_OBJECT_LOCKED()

#include "pycore_dict.h" // _PyDictViewObject

#include "pycore_freelist.h" // _Py_FREELIST_FREE(), _Py_FREELIST_POP()

#include "pycore_pyatomic_ft_wrappers.h"

#include "pycore_interp.h" // PyInterpreterState.list

#include "pycore_list.h" // struct _Py_list_freelist, _PyListIterObject

#include "pycore_long.h" // _PyLong_DigitCount

#include "pycore_modsupport.h" // _PyArg_NoKwnames()

#include "pycore_object.h" // _PyObject_GC_TRACK(), _PyDebugAllocatorStats()

#include "pycore_stackref.h" // _Py_TryIncrefCompareStackRef()

#include "pycore_tuple.h" // _PyTuple_FromArray()

#include "pycore_typeobject.h" // _Py_TYPE_VERSION_LIST

#include "pycore_setobject.h" // _PySet_NextEntry()

#include <stddef.h>

#include "clinic/listobject.c.h"

_Py_DECLARE_STR(list_err, "list index out of range");

#ifdef Py_GIL_DISABLED

typedef struct {

Py_ssize_t allocated;

PyObject *ob_item[];

} _PyListArray;

static _PyListArray *

list_allocate_array(size_t capacity)

{

if (capacity > PY_SSIZE_T_MAX/sizeof(PyObject*) - 1) {

return NULL;

}

_PyListArray *array = PyMem_Malloc(sizeof(_PyListArray) + capacity * sizeof(PyObject *));

if (array == NULL) {

return NULL;

}

array->allocated = capacity;

return array;

}

static Py_ssize_t

list_capacity(PyObject **items)

{

_PyListArray *array = _Py_CONTAINER_OF(items, _PyListArray, ob_item);

return array->allocated;

}

static void

free_list_items(PyObject** items, bool use_qsbr)

{

#ifdef Py_GIL_DISABLED

_PyListArray *array = _Py_CONTAINER_OF(items, _PyListArray, ob_item);

if (use_qsbr) {

size_t size = sizeof(_PyListArray) + array->allocated * sizeof(PyObject *);

_PyMem_FreeDelayed(array, size);

}

else {

PyMem_Free(array);

}

PyMem_Free(items);

}

static void

ensure_shared_on_resize(PyListObject *self)

{

#ifdef Py_GIL_DISABLED

// We can't use _Py_CRITICAL_SECTION_ASSERT_OBJECT_LOCKED here because

// the `CALL_LIST_APPEND` bytecode handler may lock the list without

// a critical section.

assert(Py_REFCNT(self) == 1 || PyMutex_IsLocked(&_PyObject_CAST(self)->ob_mutex));

// Ensure that the list array is freed using QSBR if we are not the

// owning thread.

if (!_Py_IsOwnedByCurrentThread((PyObject *)self) &&

!_PyObject_GC_IS_SHARED(self))

{

_PyObject_GC_SET_SHARED(self);

}

}

static int

list_resize(PyListObject *self, Py_ssize_t newsize)

{

size_t new_allocated, target_bytes;

Py_ssize_t allocated = self->allocated;

/* Bypass realloc() when a previous overallocation is large enough

if (allocated >= newsize && newsize >= (allocated >> 1)) {

assert(self->ob_item != NULL || newsize == 0);

Py_SET_SIZE(self, newsize);

return 0;

}

/* This over-allocates proportional to the list size, making room

new_allocated = ((size_t)newsize + (newsize >> 3) + 6) & ~(size_t)3;

/* Do not overallocate if the new size is closer to overallocated size

if (newsize - Py_SIZE(self) > (Py_ssize_t)(new_allocated - newsize))

new_allocated = ((size_t)newsize + 3) & ~(size_t)3;

if (newsize == 0)

new_allocated = 0;

ensure_shared_on_resize(self);

#ifdef Py_GIL_DISABLED

_PyListArray *array = list_allocate_array(new_allocated);

if (array == NULL) {

PyErr_NoMemory();

return -1;

}

PyObject **old_items = self->ob_item;

if (self->ob_item) {

if (new_allocated < (size_t)allocated) {

target_bytes = new_allocated * sizeof(PyObject*);

}

else {

target_bytes = allocated * sizeof(PyObject*);

}

memcpy(array->ob_item, self->ob_item, target_bytes);

}

if (new_allocated > (size_t)allocated) {

memset(array->ob_item + allocated, 0, sizeof(PyObject *) * (new_allocated - allocated));

}

_Py_atomic_store_ptr_release(&self->ob_item, &array->ob_item);

self->allocated = new_allocated;

Py_SET_SIZE(self, newsize);

if (old_items != NULL) {

free_list_items(old_items, _PyObject_GC_IS_SHARED(self));

}

PyObject **items;

if (new_allocated <= (size_t)PY_SSIZE_T_MAX / sizeof(PyObject *)) {

target_bytes = new_allocated * sizeof(PyObject *);

items = (PyObject **)PyMem_Realloc(self->ob_item, target_bytes);

}

else {

// integer overflow

items = NULL;

}

if (items == NULL) {

PyErr_NoMemory();

return -1;

}

self->ob_item = items;

Py_SET_SIZE(self, newsize);

self->allocated = new_allocated;

return 0;

}

static int

list_preallocate_exact(PyListObject *self, Py_ssize_t size)

{

PyObject **items;

assert(self->ob_item == NULL);

assert(size > 0);

/* Since the Python memory allocator has granularity of 16 bytes on 64-bit

size = (size + 1) & ~(size_t)1;

#ifdef Py_GIL_DISABLED

_PyListArray *array = list_allocate_array(size);

if (array == NULL) {

PyErr_NoMemory();

return -1;

}

items = array->ob_item;

memset(items, 0, size * sizeof(PyObject *));

items = PyMem_New(PyObject*, size);

if (items == NULL) {

PyErr_NoMemory();

return -1;

}

FT_ATOMIC_STORE_PTR_RELEASE(self->ob_item, items);

self->allocated = size;

return 0;

}

_PyList_DebugMallocStats(FILE *out)

{

_PyDebugAllocatorStats(out,

"free PyListObject",

_Py_FREELIST_SIZE(lists),

sizeof(PyListObject));

}

PyObject *

PyList_New(Py_ssize_t size)

{

if (size < 0) {

PyErr_BadInternalCall();

return NULL;

}

PyListObject *op = _Py_FREELIST_POP(PyListObject, lists);

if (op == NULL) {

op = PyObject_GC_New(PyListObject, &PyList_Type);

if (op == NULL) {

return NULL;

}

}

if (size <= 0) {

op->ob_item = NULL;

}

else {

#ifdef Py_GIL_DISABLED

_PyListArray *array = list_allocate_array(size);

if (array == NULL) {

Py_DECREF(op);

return PyErr_NoMemory();

}

memset(&array->ob_item, 0, size * sizeof(PyObject *));

op->ob_item = array->ob_item;

op->ob_item = (PyObject **) PyMem_Calloc(size, sizeof(PyObject *));

if (op->ob_item == NULL) {

Py_DECREF(op);

return PyErr_NoMemory();

}

}

Py_SET_SIZE(op, size);

op->allocated = size;

_PyObject_GC_TRACK(op);

return (PyObject *) op;

}

static PyObject *

list_new_prealloc(Py_ssize_t size)

{

assert(size > 0);

PyListObject *op = (PyListObject *) PyList_New(0);

if (op == NULL) {

return NULL;

}

assert(op->ob_item == NULL);

#ifdef Py_GIL_DISABLED

_PyListArray *array = list_allocate_array(size);

if (array == NULL) {

Py_DECREF(op);

return PyErr_NoMemory();

}

op->ob_item = array->ob_item;

op->ob_item = PyMem_New(PyObject *, size);

if (op->ob_item == NULL) {

Py_DECREF(op);

return PyErr_NoMemory();

}

op->allocated = size;

return (PyObject *) op;

}

PyList_Size(PyObject *op)

{

if (!PyList_Check(op)) {

PyErr_BadInternalCall();

return -1;

}

else {

return PyList_GET_SIZE(op);

}

}

static inline int

valid_index(Py_ssize_t i, Py_ssize_t limit)

{

/* The cast to size_t lets us use just a single comparison

return (size_t) i < (size_t) limit;

}

#ifdef Py_GIL_DISABLED

static PyObject *

list_item_impl(PyListObject *self, Py_ssize_t idx)

{

PyObject *item = NULL;

Py_BEGIN_CRITICAL_SECTION(self);

if (!_PyObject_GC_IS_SHARED(self)) {

_PyObject_GC_SET_SHARED(self);

}

Py_ssize_t size = Py_SIZE(self);

if (!valid_index(idx, size)) {

goto exit;

}

item = _Py_NewRefWithLock(self->ob_item[idx]);

exit:

Py_END_CRITICAL_SECTION();

return item;

}

static inline PyObject*

list_get_item_ref(PyListObject *op, Py_ssize_t i)

{

if (!_Py_IsOwnedByCurrentThread((PyObject *)op) && !_PyObject_GC_IS_SHARED(op)) {

return list_item_impl(op, i);

}

// Need atomic operation for the getting size.

Py_ssize_t size = PyList_GET_SIZE(op);

if (!valid_index(i, size)) {

return NULL;

}

PyObject **ob_item = _Py_atomic_load_ptr(&op->ob_item);

if (ob_item == NULL) {

return NULL;

}

Py_ssize_t cap = list_capacity(ob_item);

assert(cap != -1);

if (!valid_index(i, cap)) {

return NULL;

}

PyObject *item = _Py_TryXGetRef(&ob_item[i]);

if (item == NULL) {

return list_item_impl(op, i);

}

return item;

}

static inline PyObject*

list_get_item_ref(PyListObject *op, Py_ssize_t i)

{

if (!valid_index(i, Py_SIZE(op))) {

return NULL;

}

return Py_NewRef(PyList_GET_ITEM(op, i));

}

PyObject *

PyList_GetItem(PyObject *op, Py_ssize_t i)

{

if (!PyList_Check(op)) {

PyErr_BadInternalCall();

return NULL;

}

if (!valid_index(i, Py_SIZE(op))) {

_Py_DECLARE_STR(list_err, "list index out of range");

PyErr_SetObject(PyExc_IndexError, &_Py_STR(list_err));

return NULL;

}

return ((PyListObject *)op) -> ob_item[i];

}

PyObject *

PyList_GetItemRef(PyObject *op, Py_ssize_t i)

{

if (!PyList_Check(op)) {

PyErr_SetString(PyExc_TypeError, "expected a list");

return NULL;

}

PyObject *item = list_get_item_ref((PyListObject *)op, i);

if (item == NULL) {

_Py_DECLARE_STR(list_err, "list index out of range");

PyErr_SetObject(PyExc_IndexError, &_Py_STR(list_err));

return NULL;

}

return item;

}

PyObject *

_PyList_GetItemRef(PyListObject *list, Py_ssize_t i)

{

return list_get_item_ref(list, i);

}

#ifdef Py_GIL_DISABLED

_PyList_GetItemRefNoLock(PyListObject *list, Py_ssize_t i, _PyStackRef *result)

{

assert(_Py_IsOwnedByCurrentThread((PyObject *)list) ||

_PyObject_GC_IS_SHARED(list));

if (!valid_index(i, PyList_GET_SIZE(list))) {

return 0;

}

PyObject **ob_item = _Py_atomic_load_ptr(&list->ob_item);

if (ob_item == NULL) {

return 0;

}

Py_ssize_t cap = list_capacity(ob_item);

assert(cap != -1);

if (!valid_index(i, cap)) {

return 0;

}

PyObject *obj = _Py_atomic_load_ptr(&ob_item[i]);

if (obj == NULL || !_Py_TryIncrefCompareStackRef(&ob_item[i], obj, result)) {

return -1;

}

return 1;

}

PyList_SetItem(PyObject *op, Py_ssize_t i,

PyObject *newitem)

{

if (!PyList_Check(op)) {

Py_XDECREF(newitem);

PyErr_BadInternalCall();

return -1;

}

int ret;

PyListObject *self = ((PyListObject *)op);

Py_BEGIN_CRITICAL_SECTION(self);

if (!valid_index(i, Py_SIZE(self))) {

Py_XDECREF(newitem);

PyErr_SetString(PyExc_IndexError,

"list assignment index out of range");

ret = -1;

goto end;

}

PyObject *tmp = self->ob_item[i];

FT_ATOMIC_STORE_PTR_RELEASE(self->ob_item[i], newitem);

Py_XDECREF(tmp);

ret = 0;

end:;

Py_END_CRITICAL_SECTION();

return ret;

}

static int

ins1(PyListObject *self, Py_ssize_t where, PyObject *v)

{

Py_ssize_t i, n = Py_SIZE(self);

PyObject **items;

if (v == NULL) {

PyErr_BadInternalCall();

return -1;

}

assert((size_t)n + 1 < PY_SSIZE_T_MAX);

if (list_resize(self, n+1) < 0)

return -1;

if (where < 0) {

where += n;

if (where < 0)

where = 0;

}

if (where > n)

where = n;

items = self->ob_item;

for (i = n; --i >= where; )

FT_ATOMIC_STORE_PTR_RELAXED(items[i+1], items[i]);

FT_ATOMIC_STORE_PTR_RELEASE(items[where], Py_NewRef(v));

return 0;

}

PyList_Insert(PyObject *op, Py_ssize_t where, PyObject *newitem)

{

if (!PyList_Check(op)) {

PyErr_BadInternalCall();

return -1;

}

PyListObject *self = (PyListObject *)op;

int err;

Py_BEGIN_CRITICAL_SECTION(self);

err = ins1(self, where, newitem);

Py_END_CRITICAL_SECTION();

return err;

}

_PyList_AppendTakeRefListResize(PyListObject *self, PyObject *newitem)

{

Py_ssize_t len = Py_SIZE(self);

assert(self->allocated == -1 || self->allocated == len);

if (list_resize(self, len + 1) < 0) {

Py_DECREF(newitem);

return -1;

}

FT_ATOMIC_STORE_PTR_RELEASE(self->ob_item[len], newitem);

return 0;

}

PyList_Append(PyObject *op, PyObject *newitem)

{

if (PyList_Check(op) && (newitem != NULL)) {

int ret;

Py_BEGIN_CRITICAL_SECTION(op);

ret = _PyList_AppendTakeRef((PyListObject *)op, Py_NewRef(newitem));

Py_END_CRITICAL_SECTION();

return ret;

}

PyErr_BadInternalCall();

return -1;

}

static void

list_dealloc(PyObject *self)

{

PyListObject *op = (PyListObject *)self;

Py_ssize_t i;

PyObject_GC_UnTrack(op);

if (op->ob_item != NULL) {

/* Do it backwards, for Christian Tismer.

i = Py_SIZE(op);

while (--i >= 0) {

Py_XDECREF(op->ob_item[i]);

}

free_list_items(op->ob_item, false);

op->ob_item = NULL;

}

if (PyList_CheckExact(op)) {

_Py_FREELIST_FREE(lists, op, PyObject_GC_Del);

}

else {

PyObject_GC_Del(op);

}

}

static PyObject *

list_repr_impl(PyListObject *v)

{

int res = Py_ReprEnter((PyObject*)v);

if (res != 0) {

return (res > 0 ? PyUnicode_FromString("[...]") : NULL);

}

/* "[" + "1" + ", 2" * (len - 1) + "]" */

Py_ssize_t prealloc = 1 + 1 + (2 + 1) * (Py_SIZE(v) - 1) + 1;

PyUnicodeWriter *writer = PyUnicodeWriter_Create(prealloc);

PyObject *item = NULL;

if (writer == NULL) {

goto error;

}

if (PyUnicodeWriter_WriteChar(writer, '[') < 0) {

goto error;

}

/* Do repr() on each element. Note that this may mutate the list,

for (Py_ssize_t i = 0; i < Py_SIZE(v); ++i) {

/* Hold a strong reference since repr(item) can mutate the list */

item = Py_XNewRef(v->ob_item[i]);

if (i > 0) {

if (PyUnicodeWriter_WriteChar(writer, ',') < 0) {

goto error;

}

if (PyUnicodeWriter_WriteChar(writer, ' ') < 0) {

goto error;

}

}

if (PyUnicodeWriter_WriteRepr(writer, item) < 0) {

goto error;

}

Py_CLEAR(item);

}

if (PyUnicodeWriter_WriteChar(writer, ']') < 0) {

goto error;

}

Py_ReprLeave((PyObject *)v);

return PyUnicodeWriter_Finish(writer);

error:

Py_XDECREF(item);

PyUnicodeWriter_Discard(writer);

Py_ReprLeave((PyObject *)v);

return NULL;

}

static PyObject *

list_repr(PyObject *self)

{

if (PyList_GET_SIZE(self) == 0) {

return PyUnicode_FromString("[]");

}

PyListObject *v = (PyListObject *)self;

PyObject *ret = NULL;

Py_BEGIN_CRITICAL_SECTION(v);

ret = list_repr_impl(v);

Py_END_CRITICAL_SECTION();

return ret;

}

static Py_ssize_t

list_length(PyObject *a)

{

return PyList_GET_SIZE(a);

}

static int

list_contains(PyObject *aa, PyObject *el)

{

for (Py_ssize_t i = 0; ; i++) {

PyObject *item = list_get_item_ref((PyListObject *)aa, i);

if (item == NULL) {

// out-of-bounds

return 0;

}

int cmp = PyObject_RichCompareBool(item, el, Py_EQ);

Py_DECREF(item);

if (cmp != 0) {

return cmp;

}

}

return 0;

}

static PyObject *

list_item(PyObject *aa, Py_ssize_t i)

{

PyListObject *a = (PyListObject *)aa;

if (!valid_index(i, PyList_GET_SIZE(a))) {

PyErr_SetObject(PyExc_IndexError, &_Py_STR(list_err));

return NULL;

}

PyObject *item;

#ifdef Py_GIL_DISABLED

item = list_get_item_ref(a, i);

if (item == NULL) {

PyErr_SetObject(PyExc_IndexError, &_Py_STR(list_err));

return NULL;

}

item = Py_NewRef(a->ob_item[i]);

return item;

}

static PyObject *

list_slice_lock_held(PyListObject *a, Py_ssize_t ilow, Py_ssize_t ihigh)

{

PyListObject *np;

PyObject **src, **dest;

Py_ssize_t i, len;

len = ihigh - ilow;

if (len <= 0) {

return PyList_New(0);

}

np = (PyListObject *) list_new_prealloc(len);

if (np == NULL)

return NULL;

src = a->ob_item + ilow;

dest = np->ob_item;

for (i = 0; i < len; i++) {

PyObject *v = src[i];

dest[i] = Py_NewRef(v);

}

Py_SET_SIZE(np, len);

return (PyObject *)np;

}

PyObject *

PyList_GetSlice(PyObject *a, Py_ssize_t ilow, Py_ssize_t ihigh)

{

if (!PyList_Check(a)) {

PyErr_BadInternalCall();

return NULL;

}

PyObject *ret;

Py_BEGIN_CRITICAL_SECTION(a);

if (ilow < 0) {

ilow = 0;

}

else if (ilow > Py_SIZE(a)) {

ilow = Py_SIZE(a);

}

if (ihigh < ilow) {

ihigh = ilow;

}

else if (ihigh > Py_SIZE(a)) {

ihigh = Py_SIZE(a);

}

ret = list_slice_lock_held((PyListObject *)a, ilow, ihigh);

Py_END_CRITICAL_SECTION();

return ret;

}

static PyObject *

list_concat_lock_held(PyListObject *a, PyListObject *b)

{

Py_ssize_t size;

Py_ssize_t i;

PyObject **src, **dest;

PyListObject *np;

assert((size_t)Py_SIZE(a) + (size_t)Py_SIZE(b) < PY_SSIZE_T_MAX);

size = Py_SIZE(a) + Py_SIZE(b);

if (size == 0) {

return PyList_New(0);

}

np = (PyListObject *) list_new_prealloc(size);

if (np == NULL) {

return NULL;

}

src = a->ob_item;

dest = np->ob_item;

for (i = 0; i < Py_SIZE(a); i++) {

PyObject *v = src[i];

dest[i] = Py_NewRef(v);

}

src = b->ob_item;

dest = np->ob_item + Py_SIZE(a);

for (i = 0; i < Py_SIZE(b); i++) {

PyObject *v = src[i];

dest[i] = Py_NewRef(v);

}

Py_SET_SIZE(np, size);

return (PyObject *)np;

}

static PyObject *

list_concat(PyObject *aa, PyObject *bb)

{

if (!PyList_Check(bb)) {

PyErr_Format(PyExc_TypeError,

"can only concatenate list (not \"%.200s\") to list",

Py_TYPE(bb)->tp_name);

return NULL;

}

PyListObject *a = (PyListObject *)aa;

PyListObject *b = (PyListObject *)bb;

PyObject *ret;

Py_BEGIN_CRITICAL_SECTION2(a, b);

ret = list_concat_lock_held(a, b);

Py_END_CRITICAL_SECTION2();

return ret;

}

static PyObject *

list_repeat_lock_held(PyListObject *a, Py_ssize_t n)

{

const Py_ssize_t input_size = Py_SIZE(a);

if (input_size == 0 || n <= 0)

return PyList_New(0);

assert(n > 0);

if (input_size > PY_SSIZE_T_MAX / n)

return PyErr_NoMemory();

Py_ssize_t output_size = input_size * n;

PyListObject *np = (PyListObject *) list_new_prealloc(output_size);

if (np == NULL)

return NULL;

PyObject **dest = np->ob_item;

if (input_size == 1) {

PyObject *elem = a->ob_item[0];

_Py_RefcntAdd(elem, n);

PyObject **dest_end = dest + output_size;

while (dest < dest_end) {

*dest++ = elem;

}

}

else {

PyObject **src = a->ob_item;

PyObject **src_end = src + input_size;

while (src < src_end) {

_Py_RefcntAdd(*src, n);

*dest++ = *src++;

}

// TODO: _Py_memory_repeat calls are not safe for shared lists in

// GIL_DISABLED builds. (See issue #129069)

_Py_memory_repeat((char *)np->ob_item, sizeof(PyObject *)*output_size,

sizeof(PyObject *)*input_size);

}

Py_SET_SIZE(np, output_size);

return (PyObject *) np;

}

static PyObject *

list_repeat(PyObject *aa, Py_ssize_t n)

{

PyObject *ret;

PyListObject *a = (PyListObject *)aa;

Py_BEGIN_CRITICAL_SECTION(a);

ret = list_repeat_lock_held(a, n);

Py_END_CRITICAL_SECTION();

return ret;

}

static void

list_clear_impl(PyListObject *a, bool is_resize)

{

PyObject **items = a->ob_item;

if (items == NULL) {

return;

}

/* Because XDECREF can recursively invoke operations on

Py_ssize_t i = Py_SIZE(a);

Py_SET_SIZE(a, 0);

FT_ATOMIC_STORE_PTR_RELEASE(a->ob_item, NULL);

a->allocated = 0;

while (--i >= 0) {

Py_XDECREF(items[i]);

}

#ifdef Py_GIL_DISABLED

if (is_resize) {

ensure_shared_on_resize(a);

}

bool use_qsbr = is_resize && _PyObject_GC_IS_SHARED(a);

bool use_qsbr = false;

free_list_items(items, use_qsbr);

// Note that there is no guarantee that the list is actually empty

// at this point, because XDECREF may have populated it indirectly again!

}

static void

list_clear(PyListObject *a)

{

list_clear_impl(a, true);

}

static int

list_clear_slot(PyObject *self)

{

list_clear_impl((PyListObject *)self, false);

return 0;

}

static int

list_ass_slice_lock_held(PyListObject *a, Py_ssize_t ilow, Py_ssize_t ihigh, PyObject *v)

{

/* Because [X]DECREF can recursively invoke list operations on

PyObject *recycle_on_stack[8];

PyObject **recycle = recycle_on_stack; /* will allocate more if needed */

PyObject **item;

PyObject **vitem = NULL;

PyObject *v_as_SF = NULL; /* PySequence_Fast(v) */

Py_ssize_t n; /* # of elements in replacement list */

Py_ssize_t norig; /* # of elements in list getting replaced */

Py_ssize_t d; /* Change in size */

Py_ssize_t k;

size_t s;

int result = -1; /* guilty until proved innocent */

#define b ((PyListObject *)v)

if (v == NULL)

n = 0;

else {

v_as_SF = PySequence_Fast(v, "can only assign an iterable");

if(v_as_SF == NULL)

goto Error;

n = PySequence_Fast_GET_SIZE(v_as_SF);

vitem = PySequence_Fast_ITEMS(v_as_SF);

}

if (ilow < 0)

ilow = 0;

else if (ilow > Py_SIZE(a))

ilow = Py_SIZE(a);

if (ihigh < ilow)

ihigh = ilow;

else if (ihigh > Py_SIZE(a))

ihigh = Py_SIZE(a);

norig = ihigh - ilow;

assert(norig >= 0);

d = n - norig;

if (Py_SIZE(a) + d == 0) {

Py_XDECREF(v_as_SF);

list_clear(a);

return 0;

}

item = a->ob_item;

/* recycle the items that we are about to remove */

s = norig * sizeof(PyObject *);

/* If norig == 0, item might be NULL, in which case we may not memcpy from it. */

if (s) {

if (s > sizeof(recycle_on_stack)) {

recycle = (PyObject **)PyMem_Malloc(s);

if (recycle == NULL) {

PyErr_NoMemory();

goto Error;

}

}

memcpy(recycle, &item[ilow], s);

}

if (d < 0) { /* Delete -d items */

Py_ssize_t tail;

tail = (Py_SIZE(a) - ihigh) * sizeof(PyObject *);

// TODO: these memmove/memcpy calls are not safe for shared lists in

// GIL_DISABLED builds. (See issue #129069)

memmove(&item[ihigh+d], &item[ihigh], tail);

if (list_resize(a, Py_SIZE(a) + d) < 0) {

memmove(&item[ihigh], &item[ihigh+d], tail);

memcpy(&item[ilow], recycle, s);

goto Error;

}

item = a->ob_item;

}

else if (d > 0) { /* Insert d items */

k = Py_SIZE(a);

if (list_resize(a, k+d) < 0)

goto Error;

item = a->ob_item;

// TODO: these memmove/memcpy calls are not safe for shared lists in

// GIL_DISABLED builds. (See issue #129069)

memmove(&item[ihigh+d], &item[ihigh],

(k - ihigh)*sizeof(PyObject *));

}

for (k = 0; k < n; k++, ilow++) {

PyObject *w = vitem[k];

FT_ATOMIC_STORE_PTR_RELEASE(item[ilow], Py_XNewRef(w));

}

for (k = norig - 1; k >= 0; --k)

Py_XDECREF(recycle[k]);

result = 0;

Error:

if (recycle != recycle_on_stack)

PyMem_Free(recycle);

Py_XDECREF(v_as_SF);

return result;

#undef b

}

static int

list_ass_slice(PyListObject *a, Py_ssize_t ilow, Py_ssize_t ihigh, PyObject *v)

{

int ret;

if (a == (PyListObject *)v) {

Py_BEGIN_CRITICAL_SECTION(a);

Py_ssize_t n = PyList_GET_SIZE(a);

PyObject *copy = list_slice_lock_held(a, 0, n);

if (copy == NULL) {