98 lines
3.9 KiB
C++
98 lines
3.9 KiB
C++
#pragma once
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#include <ATen/core/Tensor.h>
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#include <c10/util/irange.h>
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#ifndef AT_PER_OPERATOR_HEADERS
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#include <ATen/NativeFunctions.h>
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#else
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#include <ATen/ops/view_as_real_native.h>
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#include <ATen/ops/view_as_complex_native.h>
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#include <utility>
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#endif
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// WARNING: this header contains non-inline functions and should be only
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// included from ONE cpp file
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namespace at::native {
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// View tensor with new dtype, storage offset, sizes and strides
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inline Tensor view_tensor(
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const Tensor &tensor, ScalarType dtype,
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c10::SymInt offset, SymIntArrayRef sizes, SymIntArrayRef strides) {
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Storage storage = tensor.storage();
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auto key_set = tensor.key_set().remove(DispatchKey::Conjugate);
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auto new_tensor = detail::make_tensor<TensorImpl>(
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c10::TensorImpl::VIEW, std::move(storage), key_set, scalarTypeToTypeMeta(dtype));
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auto * impl = new_tensor.unsafeGetTensorImpl();
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impl->set_sizes_and_strides(sizes, strides, offset);
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return new_tensor;
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}
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inline SymDimVector computeStrideForViewAsReal(SymIntArrayRef oldstride) {
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SymDimVector res(oldstride.size() + 1);
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for (const auto i : c10::irange(oldstride.size())) {
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res[i] = oldstride[i] * 2;
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}
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res.back() = 1;
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return res;
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}
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inline Tensor _view_as_real_physical(const Tensor& self) {
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TORCH_CHECK(self.is_complex(), "view_as_real is only supported for complex tensors");
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auto old_sizes = self.sym_sizes();
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SymDimVector new_sizes(old_sizes.size() + 1);
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std::copy(old_sizes.begin(), old_sizes.end(), new_sizes.begin());
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// last dimension will always have two elements containing the real and imag vals
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new_sizes.back() = 2;
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auto new_strides = computeStrideForViewAsReal(self.sym_strides());
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auto new_storage_offset = self.sym_storage_offset() * 2;
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const auto float_type = c10::toRealValueType(self.scalar_type());
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auto real_tensor = view_tensor(self, float_type, std::move(new_storage_offset), new_sizes, new_strides);
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return real_tensor;
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}
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// expects as input a complex tensor and returns back a tensor
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// with corresponding real dtype containing the complex values
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// in the last two dimensions
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Tensor view_as_real(const Tensor& self) {
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TORCH_CHECK(!self.is_conj(), "view_as_real doesn't work on unresolved conjugated tensors. To resolve the conjugate tensor so you can view it as real, use self.resolve_conj(); however, be warned that the resulting tensor will NOT alias the original.");
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return _view_as_real_physical(self);
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}
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inline SymDimVector computeStrideForViewAsComplex(SymIntArrayRef oldstride) {
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const int64_t dim = oldstride.size();
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TORCH_CHECK(oldstride[dim-1] == 1, "Tensor must have a last dimension with stride 1");
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SymDimVector res(dim - 1);
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for (const auto i : c10::irange(res.size())) {
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TORCH_CHECK(oldstride[i] % 2 == 0, "Tensor must have a stride divisible by 2 for all but last dimension");
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res[i] = oldstride[i] / 2;
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}
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return res;
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}
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// expects as input a float or double tensor with last dimension of size 2
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// and returns back a tensor with corresponding complex dtype
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Tensor view_as_complex(const Tensor& self) {
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TORCH_CHECK(
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self.scalar_type() == kFloat || self.scalar_type() == kDouble || self.scalar_type() == kHalf,
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"view_as_complex is only supported for half, float and double tensors, but got a tensor of scalar type: ", self.scalar_type());
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auto old_sizes = self.sym_sizes();
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TORCH_CHECK(!old_sizes.empty(), "Input tensor must have one or more dimensions");
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TORCH_CHECK(old_sizes[old_sizes.size()-1] == 2, "Tensor must have a last dimension of size 2");
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SymDimVector new_sizes(old_sizes.begin(), old_sizes.end() - 1);
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const auto new_strides = computeStrideForViewAsComplex(self.sym_strides());
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const auto complex_type = c10::toComplexType(self.scalar_type());
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TORCH_CHECK(self.sym_storage_offset() % 2 == 0, "Tensor must have a storage_offset divisible by 2");
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const auto new_storage_offset = self.sym_storage_offset() / 2;
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return view_tensor(self, complex_type, new_storage_offset, new_sizes, new_strides);
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}
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} // namespace at::native
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