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python_variable_indexing.cpp
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python_variable_indexing.cpp
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#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/utils/python_compat.h>
#include <torch/csrc/utils/python_numbers.h>
#include <torch/csrc/utils/tensor_new.h>
#include <torch/csrc/utils/python_arg_parser.h>
#include <torch/csrc/jit/frontend/tracer.h>
#include <torch/csrc/jit/ir/ir.h>
#include <torch/csrc/utils/tensor_types.h>
#include <ATen/DeviceGuard.h>
#include <ATen/ExpandUtils.h>
#include <ATen/TensorIndexing.h>
#include <ATen/TracerMode.h>
#include <c10/core/TensorOptions.h>
#include <c10/util/irange.h>
#include <ATen/core/LegacyTypeDispatch.h>
#include <vector>
#include <tuple>
using namespace at;
using namespace torch::autograd::utils;
namespace torch { namespace 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;
}
return (Py_ssize_t)self_.size(0);
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 inline 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); // NOLINT(cppcoreguidelines-pro-type-cstyle-cast)
for (Py_ssize_t i = 0; i < size; i++) {
PyObject* obj = PyTuple_GET_ITEM(index, i); // NOLINT(cppcoreguidelines-pro-type-cstyle-cast)
if (!THPVariable_CheckExact(obj) && 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) { // NOLINT(cppcoreguidelines-pro-type-cstyle-cast)
count++;
}
}
return count;
}
[[noreturn]]
static inline void invalid_index(PyObject* obj) {
throw IndexError(
"only integers, slices (`:`), ellipsis (`...`), None and long or byte "
"Variables are valid indices (got %s)", Py_TYPE(obj)->tp_name);
}
static inline Variable sequenceToVariable(c10::TensorOptions options, PyObject* seq) {
return torch::utils::indexing_tensor_from_data(options, kLong, c10::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;
if (THPUtils_checkLong(value) || PyBool_Check(value)) {
return at::indexing::scalarToTensor(Scalar(THPUtils_unpackLong(value)), options, device);
}
if (PyFloat_Check(value)) {
return at::indexing::scalarToTensor(Scalar(THPUtils_unpackDouble(value)), options, device);
}
if (PyComplex_Check(value)) {
return at::indexing::scalarToTensor(Scalar(THPUtils_unpackComplexDouble(value)), options, device);
}
throw TypeError(
"can't assign a %s to a %s",
Py_TYPE(value)->tp_name,
torch::utils::options_to_string(options).c_str());
}
static inline void checkUnpackSlice(PyObject* index, Py_ssize_t* start_ptr, Py_ssize_t* stop_ptr, Py_ssize_t* step_ptr) {
if (!THPUtils_unpackSlice(index, start_ptr, stop_ptr, step_ptr)) {
throw python_error();
}
}
static inline 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 inline void recordSelectTrace(const Tensor& index_tensor) {
torch::jit::tracer::ArgumentStash::stashValue(std::string("index"), 1, index_tensor, torch::jit::IntType::get());
}
static inline Variable applySlicing(
const Variable& self,
PyObject* index,
variable_list& outIndices,
bool is_tracing,
const at::Device& self_device,
const IntArrayRef& self_sizes,
int64_t specified_dims) {
int64_t size = PyTuple_GET_SIZE(index); // NOLINT(cppcoreguidelines-pro-type-cstyle-cast)
int64_t dim = 0;
if (specified_dims > (int64_t)self_sizes.size()) {
throw IndexError("too many indices for tensor of dimension %d", (int)(self_sizes.size()));
}
Variable result = self;
for(const auto i : c10::irange(size)) {
PyObject* obj = PyTuple_GET_ITEM(index, i); // NOLINT(cppcoreguidelines-pro-type-cstyle-cast)
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)) {
// NOLINTNEXTLINE(cppcoreguidelines-init-variables)
Py_ssize_t start, stop, step;
checkUnpackSlice(obj, &start, &stop, &step);
if (is_tracing) {
recordSliceTrace(obj);
}
return at::indexing::TensorIndex(at::indexing::Slice(start, stop, 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 inline bool treatSequenceAsTuple(PyObject* index) {
if (PyTuple_Check(index)) {
return true;
}
if (THPVariable_Check(index)) {
return false;
}
if (!PySequence_Check(index)) {
return false;
}
// This uses a heuristics from NumPy for determining whether to treat
// non-tuple sequences as if they were a tuple. From the NumPy code comments:
//
// "At this point, we're left with a non-tuple, non-array, sequence:
// typically, a list. We use some somewhat-arbitrary heuristics from here
// onwards to decided whether to treat that list as a single index, or a
// list of indices. Backwards compatibility only takes effect for short
// sequences - otherwise we treat it like any other scalar."
auto n = PySequence_Size(index);
if (n < 0) {
// Negative size indicates a Python error in the PySequence_Size call.
PyErr_Clear();
return false;
}
// NOLINTNEXTLINE(cppcoreguidelines-avoid-magic-numbers)
if (n >= 32) {
return false;
}
for (Py_ssize_t i = 0; i < n; i++) {
auto obj = THPObjectPtr{PySequence_GetItem(index, i)};
if (!obj.get()) {
PyErr_Clear();
return false;
}
if (THPVariable_Check(obj.get()) || PySequence_Check(obj.get()) || PySlice_Check(obj.get())) {
return true;
}
if (obj.get() == Py_Ellipsis || obj.get() == Py_None) {
return true;
}
}
return false;
}
static inline THPObjectPtr wrapTuple(PyObject* index) {
THPObjectPtr res;
if (treatSequenceAsTuple(index)) {
res = PySequence_Tuple(index);
} else {
res = PyTuple_Pack(1, index); // NOLINT(cppcoreguidelines-pro-type-cstyle-cast)
}
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 (!THPVariable_CheckExact(self) && 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)) {
// NOLINTNEXTLINE(cppcoreguidelines-init-variables)
Py_ssize_t start, stop, step;
checkUnpackSlice(index, &start, &stop, &step);
if (is_tracing) {
recordSliceTrace(index);
}
return THPVariable_Wrap(
at::indexing::get_item(self_, {at::indexing::TensorIndex(at::indexing::Slice(start, stop, 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, index);
}
Variable sliced = applySlicing(
self_, holder.get(), variableIndices, /*is_tracing=*/is_tracing, self_.device(), self_.sizes(), 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(std::move(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
}
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) {
throw TypeError("Tensor does not support deleting items");
}
if ((!THPVariable_CheckExact(self) && check_has_torch_function(self)) ||
(!THPVariable_CheckExact(py_value) && 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_.is_sparse() || self_.is_sparse_csr())
{
throw TypeError("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) { // NOLINT(cppcoreguidelines-pro-type-cstyle-cast)
// 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)) {
if (is_tracing && THPVariable_Check(index)) {
recordSelectTrace(THPVariable_Unpack(index));
}
dispatch_set_item(self_, {at::indexing::TensorIndex(THPUtils_unpackLong(index))}, value);
return 0;
} else if (PySlice_Check(index)) {
// NOLINTNEXTLINE(cppcoreguidelines-init-variables)
Py_ssize_t start, stop, step;
checkUnpackSlice(index, &start, &stop, &step);
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(start, stop, 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_.sizes(), 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;
IntArrayRef valueSizes = value.sizes();
IntArrayRef slicedValueSizes = at::indexing::slicePrefix1sSize(valueSizes);
torch::autograd::Variable valuesSliced;
if (!valueSizes.equals(slicedValueSizes)) {
valuesSliced = value.view(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