pytorch/torch/csrc/autograd/python_variable_indexing.cpp
Natalia Gimelshein febfc3ec03 flip the list-as-tuple behavior for short lists (#160794)
Per title, previously we started throwing noisy warnings, but given how popular this pattern was in our test suite decided to leave it as warning, not as silent behavior change for one release.
Now `treatSequenceAsTuple` would return `true` in the only case where the sequence was indeed a tuple, so no need for a special function anymore.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/160794
Approved by: https://github.com/albanD
2025-08-20 22:40:42 +00:00

498 lines
17 KiB
C++

#include <torch/csrc/autograd/python_variable_indexing.h>
#include <torch/csrc/DynamicTypes.h>
#include <torch/csrc/Exceptions.h>
#include <torch/csrc/Export.h>
#include <torch/csrc/autograd/function.h>
#include <torch/csrc/autograd/utils/wrap_outputs.h>
#include <torch/csrc/autograd/variable.h>
#include <torch/csrc/jit/frontend/tracer.h>
#include <torch/csrc/jit/ir/ir.h>
#include <torch/csrc/utils/numpy_stub.h>
#include <torch/csrc/utils/pybind.h>
#include <torch/csrc/utils/python_arg_parser.h>
#include <torch/csrc/utils/python_compat.h>
#include <torch/csrc/utils/python_numbers.h>
#include <torch/csrc/utils/python_symnode.h>
#include <torch/csrc/utils/tensor_new.h>
#include <torch/csrc/utils/tensor_numpy.h>
#include <torch/csrc/utils/tensor_types.h>
#include <ATen/DeviceGuard.h>
#include <ATen/ExpandUtils.h>
#include <ATen/Functions.h>
#include <ATen/TensorIndexing.h>
#include <ATen/TracerMode.h>
#include <ATen/core/LegacyTypeDispatch.h>
#include <c10/core/TensorOptions.h>
#include <c10/util/Exception.h>
#include <c10/util/irange.h>
#include <c10/core/Layout.h>
#include <fmt/format.h>
using namespace at;
using namespace torch::autograd::utils;
namespace torch::autograd {
Py_ssize_t THPVariable_length(PyObject* self) {
HANDLE_TH_ERRORS
if (check_has_torch_function(self)) {
py::object ret = py::reinterpret_steal<py::object>(
handle_torch_function(self, "__len__"));
Py_ssize_t length = PyLong_AsSsize_t(ret.ptr());
if (PyErr_Occurred()) {
throw python_error();
}
return length;
}
const auto& self_ = THPVariable_Unpack(self);
if (self_.dim() == 0) {
return 0;
}
// TODO: Maybe this should return a SymInt directly?
// Add the guard to get a nice error message if/when we will hit this.
return (Py_ssize_t)self_.sym_size(0).guard_int(__FILE__, __LINE__);
END_HANDLE_TH_ERRORS_RET(-1)
}
// We allow indexing by integers, slices, ellipsis, None, Variables,
// and tuples of those types. We also handle bools as if they were a
// Variable[ByteTensor].
static int64_t count_specified_dimensions(PyObject* index) {
// Count the number of indexed dimensions (everything but ellipsis and None)
// -1 is a sentinel for __torch_function__
int64_t count = 0;
auto size = PyTuple_GET_SIZE(index);
for (Py_ssize_t i = 0; i < size; i++) {
PyObject* obj = PyTuple_GET_ITEM(index, i);
if (check_has_torch_function(obj))
return -1;
if (THPVariable_Check(obj)) {
const auto& var = THPVariable_Unpack(obj);
const auto& var_scalar_type = var.scalar_type();
if (var_scalar_type == kByte || var_scalar_type == kBool) {
count += var.dim();
} else {
count++;
}
} else if (
obj != Py_None && obj != Py_Ellipsis && obj != Py_True &&
obj != Py_False) {
count++;
}
}
return count;
}
static void invalid_index(PyObject* obj) {
TORCH_CHECK_INDEX(
false,
"only integers, slices (`:`), ellipsis (`...`), None and long or byte "
"Variables are valid indices (got ",
Py_TYPE(obj)->tp_name,
")");
}
static Variable sequenceToVariable(c10::TensorOptions options, PyObject* seq) {
return torch::utils::indexing_tensor_from_data(
options, kLong, std::nullopt, seq);
}
inline Variable valueToTensor(
c10::TensorOptions options,
PyObject* value,
const at::Device& device) {
if (THPVariable_Check(value)) {
return THPVariable_Unpack(value);
}
at::AutoDispatchBelowADInplaceOrView guard; // TODO: remove
at::tracer::impl::NoTracerDispatchMode tracer_guard;
Scalar scalar;
if (THPUtils_checkLong(value) || PyBool_Check(value)) {
scalar = Scalar(THPUtils_unpackLong(value));
} else if (PyFloat_Check(value)) {
scalar = Scalar(THPUtils_unpackDouble(value));
} else if (PyComplex_Check(value)) {
scalar = Scalar(THPUtils_unpackComplexDouble(value));
} else if (torch::is_symint(value)) {
scalar = Scalar(py::cast<c10::SymInt>(py::handle(value)));
} else if (torch::is_symfloat(value)) {
scalar = Scalar(py::cast<c10::SymFloat>(py::handle(value)));
} else if (torch::is_symbool(value)) {
scalar = Scalar(py::cast<c10::SymBool>(py::handle(value)));
} else {
TORCH_CHECK_TYPE(
false,
"can't assign a ",
Py_TYPE(value)->tp_name,
" to a ",
torch::utils::options_to_string(options));
}
// lift_fresh is supposed to be used in situations where you are guaranteed to
// get a plain Tensor which is not true for cpu device but not for non cpu
// device
if (device == at::kCPU && !scalar.isSymbolic()) {
return at::lift_fresh(
at::indexing::scalarToTensor(scalar, options, device));
} else {
return at::indexing::scalarToTensor(scalar, options, device);
}
}
static void recordSliceTrace(PyObject* obj) {
PySliceObject* sliceobj = (PySliceObject*)obj;
if (THPVariable_Check(sliceobj->start)) {
torch::jit::tracer::ArgumentStash::stashValue(
std::string("start"),
1,
THPVariable_Unpack(sliceobj->start),
torch::jit::IntType::get());
}
if (THPVariable_Check(sliceobj->stop)) {
torch::jit::tracer::ArgumentStash::stashValue(
std::string("end"),
1,
THPVariable_Unpack(sliceobj->stop),
torch::jit::IntType::get());
}
if (THPVariable_Check(sliceobj->step)) {
torch::jit::tracer::ArgumentStash::stashValue(
std::string("step"),
1,
THPVariable_Unpack(sliceobj->step),
torch::jit::IntType::get());
}
}
static void recordSelectTrace(const Tensor& index_tensor) {
torch::jit::tracer::ArgumentStash::stashValue(
std::string("index"), 1, index_tensor, torch::jit::IntType::get());
}
static Variable applySlicing(
const Variable& self,
PyObject* index,
variable_list& outIndices,
bool is_tracing,
const at::Device& self_device,
const std::optional<int64_t>& self_ndim,
int64_t specified_dims) {
int64_t size = PyTuple_GET_SIZE(index);
int64_t dim = 0;
// See NOTE [nested tensor size for indexing]
if (self_ndim.has_value()) {
TORCH_CHECK_INDEX(
specified_dims <= self_ndim.value(),
"too many indices for tensor of dimension ",
self_ndim.value());
}
Variable result = self;
for (const auto i : c10::irange(size)) {
PyObject* obj = PyTuple_GET_ITEM(index, i);
// NOTE [nested tensor size for indexing]
// nested tensor does not have a size (yet) so for now we represent its size
// as null may need to be changed after we reach a better solution for
// nested tensor size
std::optional<SymIntArrayRef> result_sizes = result.is_nested()
? std::optional<SymIntArrayRef>(std::nullopt)
: std::optional<SymIntArrayRef>(result.sym_sizes());
result = at::indexing::handleDimInMultiDimIndexing(
/*prev_dim_result=*/result,
/*original_tensor=*/self,
/*index=*/([&]() {
if (THPUtils_checkLong(obj)) {
if (is_tracing && THPVariable_Check(obj)) {
recordSelectTrace(THPVariable_Unpack(obj));
}
return at::indexing::TensorIndex(THPUtils_unpackLong(obj));
} else if (PySlice_Check(obj)) {
auto val = __PySlice_Unpack(obj);
if (is_tracing) {
recordSliceTrace(obj);
}
return at::indexing::TensorIndex(
at::indexing::Slice(val.start, val.stop, val.step));
} else if (obj == Py_Ellipsis) {
return at::indexing::TensorIndex(at::indexing::Ellipsis);
} else if (obj == Py_None) {
return at::indexing::TensorIndex(at::indexing::None);
} else if (PyBool_Check(obj)) {
return at::indexing::TensorIndex(obj == Py_True);
} else if (THPVariable_Check(obj)) {
Tensor tensor = THPVariable_Unpack(obj);
if (is_tracing) {
auto scalar_type = tensor.scalar_type();
if (tensor.dim() == 0 &&
at::isIntegralType(scalar_type, /*includeBool=*/false) &&
scalar_type != at::kByte) {
recordSelectTrace(tensor);
}
}
return at::indexing::TensorIndex(std::move(tensor));
} else if (PySequence_Check(obj)) {
return at::indexing::TensorIndex(
sequenceToVariable(self.options(), obj));
} else {
auto idx = THPObjectPtr(PyNumber_Index(obj));
if (!idx) {
PyErr_Clear();
invalid_index(obj);
}
if (is_tracing && THPVariable_Check(idx)) {
recordSelectTrace(THPVariable_Unpack(idx));
}
return at::indexing::TensorIndex(THPUtils_unpackLong(idx));
}
})(),
/*dim_ptr=*/&dim,
/*specified_dims_ptr=*/&specified_dims,
/*real_dim=*/i,
/*outIndices=*/outIndices,
// See NOTE [ Setting `disable_slice_optimization` when calling C++
// tensor indexing functions from Python ]
/*disable_slice_optimization=*/is_tracing,
/*original_tensor_device=*/self_device,
/*prev_dim_result_sizes=*/result_sizes);
}
return result;
}
static THPObjectPtr wrapTuple(PyObject* index) {
THPObjectPtr res;
if (PyTuple_Check(index)) {
res = PySequence_Tuple(index);
} else {
res = PyTuple_Pack(1, index);
}
if (!res)
throw python_error();
return res;
}
// NOTE: Here is the dispatch structure for `THPVariable_getitem`:
//
// 1. Python 1-D getter calls C++ `at::indexing::get_item` after
// converting Python index to C++ TensorIndex.
//
// 2. Python N-D getter calls C++ `at::indexing::handleDimInMultiDimIndexing`
// for each dim, after converting Python index to C++ TensorIndex. If advanced
// indexing is needed, it calls C++ `at::indexing::dispatch_index`.
PyObject* THPVariable_getitem(PyObject* self, PyObject* index) {
HANDLE_TH_ERRORS
if (check_has_torch_function(self)) {
return handle_torch_function_indexing(self, index);
}
const auto& self_ = THPVariable_Unpack(self);
OptionalDeviceGuard device_guard(device_of(self_));
// handle simple types: none, ellipsis
if (index == Py_None) {
return THPVariable_Wrap(at::indexing::get_item(
self_, {at::indexing::TensorIndex(at::indexing::None)}));
} else if (index == Py_Ellipsis) {
return THPVariable_Wrap(at::indexing::get_item(
self_, {at::indexing::TensorIndex(at::indexing::Ellipsis)}));
}
bool is_tracing = torch::jit::tracer::isTracing();
// handle simple types: integers, slices, bool
if (THPUtils_checkLong(index)) {
if (is_tracing && THPVariable_Check(index)) {
recordSelectTrace(THPVariable_Unpack(index));
}
return THPVariable_Wrap(at::indexing::get_item(
self_, {at::indexing::TensorIndex(THPUtils_unpackLong(index))}));
} else if (PySlice_Check(index)) {
auto val = __PySlice_Unpack(index);
if (is_tracing) {
recordSliceTrace(index);
}
return THPVariable_Wrap(at::indexing::get_item(
self_,
{at::indexing::TensorIndex(
at::indexing::Slice(val.start, val.stop, val.step))}));
} else if (index == Py_False || index == Py_True) {
return THPVariable_Wrap(([&]() {
pybind11::gil_scoped_release no_gil;
return at::indexing::get_item(
self_, {at::indexing::TensorIndex(index == Py_True)});
})());
}
// wrap index in a tuple if it's not already one
THPObjectPtr holder = wrapTuple(index);
variable_list variableIndices;
int64_t specified_dims = count_specified_dimensions(holder.get());
if (specified_dims == -1) {
return handle_torch_function_indexing(self, holder.get());
}
Variable sliced = applySlicing(
self_,
holder.get(),
variableIndices,
/*is_tracing=*/is_tracing,
self_.device(),
self_.ndimension(),
specified_dims);
if (variableIndices.empty()) {
if (sliced.is_same(self_)) {
// ensure we return a shallow copy for things like x[...]
sliced = at::alias(sliced);
}
return THPVariable_Wrap(sliced);
}
// indexing by tensors ("advanced" indexing)
return THPVariable_Wrap(([&]() {
pybind11::gil_scoped_release no_gil;
return at::indexing::dispatch_index(sliced, std::move(variableIndices));
})());
Py_RETURN_NONE;
END_HANDLE_TH_ERRORS
}
static void dispatch_set_item(
const Tensor& self,
ArrayRef<at::indexing::TensorIndex> indices,
const Tensor& value,
bool disable_slice_optimization = false) {
pybind11::gil_scoped_release no_gil;
at::indexing::set_item(self, indices, value, disable_slice_optimization);
}
// NOTE: Here is the dispatch structure for `THPVariable_setitem`:
//
// 1. Python 1-D setter calls C++ `at::indexing::set_item` after
// converting Python index to C++ TensorIndex.
//
// 2. Python N-D setter calls C++ `at::indexing::handleDimInMultiDimIndexing`
// for each dim, after converting Python index to C++ TensorIndex. If advanced
// indexing is needed, it calls C++ `at::indexing::dispatch_index_put_`.
int THPVariable_setitem(PyObject* self, PyObject* index, PyObject* py_value) {
HANDLE_TH_ERRORS
if (py_value == nullptr) {
TORCH_CHECK_TYPE(false, "Tensor does not support deleting items");
}
if ((check_has_torch_function(self)) ||
(check_has_torch_function(py_value))) {
py::object ret = py::reinterpret_steal<py::object>(
handle_torch_function_indexing(self, index, py_value));
return 0;
}
const auto& self_ = THPVariable_Unpack(self);
if (self_.layout() == kSparse || self_.layout() == kSparseCsr ||
self_.layout() == kSparseCsc || self_.layout() == kSparseBsr ||
self_.layout() == kSparseBsc) {
TORCH_CHECK_TYPE(false, "Cannot assign to a sparse tensor");
}
OptionalDeviceGuard device_guard(device_of(self_));
at::Device self_device = self_.device();
Variable value;
// TODO: This qint special case looks very suspicious...
if (isQIntType(self_.scalar_type())) {
value =
valueToTensor(device(kCPU).dtype(kFloat), py_value, at::Device(kCPU));
} else if (self_device.is_cuda()) {
value = valueToTensor(self_.options(), py_value, at::Device(kCPU));
} else {
value = valueToTensor(self_.options(), py_value, self_device);
}
// handle simple types: ellipsis, none, bool
if (index == Py_False) {
// do nothing for false (technically we should check the size, but we don't
// have real 0-sized shapes.
return 0;
} else if (index == Py_Ellipsis) {
dispatch_set_item(
self_, {at::indexing::TensorIndex(at::indexing::Ellipsis)}, value);
return 0;
} else if (index == Py_None) {
dispatch_set_item(
self_, {at::indexing::TensorIndex(at::indexing::None)}, value);
return 0;
} else if (index == Py_True) {
dispatch_set_item(self_, {at::indexing::TensorIndex(true)}, value);
return 0;
}
bool is_tracing = torch::jit::tracer::isTracing();
// handle simple types: integers, slices
if (THPUtils_checkLong(index) || torch::is_symint(index)) {
if (is_tracing && THPVariable_Check(index)) {
recordSelectTrace(THPVariable_Unpack(index));
}
auto symint = torch::is_symint(index) ? py::cast<SymInt>(index)
: SymInt(THPUtils_unpackLong(index));
dispatch_set_item(self_, {at::indexing::TensorIndex(symint)}, value);
return 0;
} else if (PySlice_Check(index)) {
auto val = __PySlice_Unpack(index);
if (is_tracing) {
recordSliceTrace(index);
}
// See NOTE [ Setting `disable_slice_optimization` when calling C++ tensor
// indexing functions from Python ]
dispatch_set_item(
self_,
{at::indexing::TensorIndex(
at::indexing::Slice(val.start, val.stop, val.step))},
value,
/*disable_slice_optimization=*/is_tracing);
return 0;
}
// wrap index in a tuple if it's not already one
THPObjectPtr holder = wrapTuple(index);
variable_list variableIndices;
int64_t specified_dims = count_specified_dimensions(holder.get());
if (specified_dims == -1) {
py::object val = py::reinterpret_steal<py::object>(
handle_torch_function_indexing(self, index, py_value));
return 0;
}
Variable sliced = applySlicing(
self_,
holder.get(),
variableIndices,
/*is_tracing=*/is_tracing,
self_device,
self_.ndimension(),
specified_dims);
if (variableIndices.empty()) {
pybind11::gil_scoped_release no_gil;
at::indexing::copy_to(sliced, value);
return 0;
}
{
pybind11::gil_scoped_release no_gil;
SymIntArrayRef valueSizes = value.sym_sizes();
SymIntArrayRef slicedValueSizes =
at::indexing::slicePrefix1sSize(valueSizes);
torch::autograd::Variable valuesSliced;
if (!valueSizes.equals(slicedValueSizes)) {
valuesSliced = value.view_symint(slicedValueSizes);
} else {
valuesSliced = value;
}
at::indexing::dispatch_index_put_(
sliced, std::move(variableIndices), valuesSliced);
return 0;
}
END_HANDLE_TH_ERRORS_RET(-1)
}
} // namespace torch::autograd