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bug #795: mention allocate_shared as a condidate for aligned_allocator.

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This commit is contained in:
Gael Guennebaud 2016-02-12 22:09:16 +01:00
parent 6eff3e5185
commit c8b4c4b48a
1 changed files with 6 additions and 4 deletions
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10
doc/UnalignedArrayAssert.dox
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@ -7,8 +7,8 @@ Hello! You are seeing this webpage because your program terminated on an asserti
my_program: path/to/eigen/Eigen/src/Core/DenseStorage.h:44:
Eigen::internal::matrix_array<T, Size, MatrixOptions, Align>::internal::matrix_array()
[with T = double, int Size = 2, int MatrixOptions = 2, bool Align = true]:
Assertion `(reinterpret_cast<size_t>(array) & 0xf) == 0 && "this assertion
is explained here: http://eigen.tuxfamily.org/dox/UnalignedArrayAssert.html
Assertion `(reinterpret_cast<size_t>(array) & (sizemask)) == 0 && "this assertion
is explained here: http://eigen.tuxfamily.org/dox-devel/group__TopicUnalignedArrayAssert.html
**** READ THIS WEB PAGE !!! ****"' failed.
</pre>
@ -46,9 +46,9 @@ then you need to read this separate page: \ref TopicStructHavingEigenMembers "St
Note that here, Eigen::Vector2d is only used as an example, more generally the issue arises for all \ref TopicFixedSizeVectorizable "fixed-size vectorizable Eigen types".
\section c2 Cause 2: STL Containers
\section c2 Cause 2: STL Containers or manual memory allocation
If you use STL Containers such as std::vector, std::map, ..., with Eigen objects, or with classes containing Eigen objects, like this,
If you use STL Containers such as std::vector, std::map, ..., with %Eigen objects, or with classes containing %Eigen objects, like this,
\code
std::vector<Eigen::Matrix2f> my_vector;
@ -60,6 +60,8 @@ then you need to read this separate page: \ref TopicStlContainers "Using STL Con
Note that here, Eigen::Matrix2f is only used as an example, more generally the issue arises for all \ref TopicFixedSizeVectorizable "fixed-size vectorizable Eigen types" and \ref TopicStructHavingEigenMembers "structures having such Eigen objects as member".
The same issue will be exhibited by any classes/functions by-passing operator new to allocate memory, that is, by performing custom memory allocation followed by calls to the placement new operator. This is for instance typically the case of \c std::make_shared or \c std::allocate_shared for which is the solution is to use an \ref aligned_allocator "aligned allocator" as detailed in the \ref TopicStlContainers "solution for STL containers".
\section c3 Cause 3: Passing Eigen objects by value
If some function in your code is getting an Eigen object passed by value, like this,