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Re-implement move assignments.

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The original swap approach leads to potential undefined behavior (reading
uninitialized memory) and results in unnecessary copying of data for static
storage.

Here we pass down the move assignment to the underlying storage.  Static
storage does a one-way copy, dynamic storage does a swap.

Modified the tests to no longer read from the moved-from matrix/tensor,
since that can lead to UB. Added a test to ensure we do not access
uninitialized memory in a move.

Fixes: #2119
This commit is contained in:
Antonio Sanchez
2021-03-05 12:54:26 -08:00
committed by Rasmus Munk Larsen
parent b8d1857f0d
commit 543e34ab9d
8 changed files with 62 additions and 17 deletions
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5
unsupported/Eigen/CXX11/src/Tensor/Tensor.h
View File

@@ -402,14 +402,13 @@ class Tensor : public TensorBase<Tensor<Scalar_, NumIndices_, Options_, IndexTyp
#if EIGEN_HAS_RVALUE_REFERENCES
EIGEN_DEVICE_FUNC
EIGEN_STRONG_INLINE Tensor(Self&& other)
: Tensor()
: m_storage(std::move(other.m_storage))
{
m_storage.swap(other.m_storage);
}
EIGEN_DEVICE_FUNC
EIGEN_STRONG_INLINE Tensor& operator=(Self&& other)
{
m_storage.swap(other.m_storage);
m_storage = std::move(other.m_storage);
return *this;
}
#endif

14
unsupported/Eigen/CXX11/src/Tensor/TensorStorage.h
View File

@@ -108,6 +108,20 @@ class TensorStorage<T, DSizes<IndexType, NumIndices_>, Options_>
return *this;
}
#if EIGEN_HAS_RVALUE_REFERENCES
EIGEN_DEVICE_FUNC TensorStorage(Self&& other) : TensorStorage()
{
*this = std::move(other);
}
EIGEN_DEVICE_FUNC Self& operator=(Self&& other)
{
numext::swap(m_data, other.m_data);
numext::swap(m_dimensions, other.m_dimensions);
return *this;
}
#endif
EIGEN_DEVICE_FUNC ~TensorStorage() { internal::conditional_aligned_delete_auto<T,(Options_&DontAlign)==0>(m_data, internal::array_prod(m_dimensions)); }
EIGEN_DEVICE_FUNC void swap(Self& other)
{ numext::swap(m_data,other.m_data); numext::swap(m_dimensions,other.m_dimensions); }

5
unsupported/test/cxx11_tensor_move.cpp
View File

@@ -62,14 +62,9 @@ static void test_move()
moved_tensor3 = std::move(moved_tensor1);
moved_tensor4 = std::move(moved_tensor2);
VERIFY_IS_EQUAL(moved_tensor1.size(), 8);
VERIFY_IS_EQUAL(moved_tensor2.size(), 8);
for (int i = 0; i < 8; i++)
{
calc_indices(i, x, y, z);
VERIFY_IS_EQUAL(moved_tensor1(x,y,z), 0);
VERIFY_IS_EQUAL(moved_tensor2(x,y,z), 0);
VERIFY_IS_EQUAL(moved_tensor3(x,y,z), i);
VERIFY_IS_EQUAL(moved_tensor4(x,y,z), 2 * i);
}