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Add specialization for compile-time zero-sized dense assignment.

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In the current `dense_assignment_loop` implementations, if the
destination's inner or outer size is zero at compile time and if the kernel
involves a product, we currently get a compile error (#2080).  This is
triggered by attempting to multiply a non-existent row by a column (or
vice-versa).

To address this, we add a specialization for zero-sized assignments
(`AllAtOnceTraversal`) which evaluates to a no-op. We also add a static
check to ensure the size is in-fact zero. This now seems to be the only
existing use of `AllAtOnceTraversal`.

Fixes #2080.
This commit is contained in:
Antonio Sanchez 2020-12-07 08:27:03 -08:00
parent 5ec4907434
commit 655c3a4042
1 changed files with 55 additions and 37 deletions
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26
Eigen/src/Core/AssignEvaluator.h
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@ -99,7 +99,8 @@ private:
public:
enum {
Traversal = (int(MayLinearVectorize) && (LinearPacketSize>InnerPacketSize)) ? int(LinearVectorizedTraversal)
Traversal = int(Dst::SizeAtCompileTime) == 0 ? int(AllAtOnceTraversal) // If compile-size is zero, traversing will fail at compile-time.
: (int(MayLinearVectorize) && (LinearPacketSize>InnerPacketSize)) ? int(LinearVectorizedTraversal)
: int(MayInnerVectorize) ? int(InnerVectorizedTraversal)
: int(MayLinearVectorize) ? int(LinearVectorizedTraversal)
: int(MaySliceVectorize) ? int(SliceVectorizedTraversal)
@ -316,6 +317,22 @@ template<typename Kernel,
int Unrolling = Kernel::AssignmentTraits::Unrolling>
struct dense_assignment_loop;
/************************
***** Special Cases *****
************************/
// Zero-sized assignment is a no-op.
template<typename Kernel, int Unrolling>
struct dense_assignment_loop<Kernel, AllAtOnceTraversal, Unrolling>
{
EIGEN_DEVICE_FUNC static void EIGEN_STRONG_INLINE run(Kernel &kernel)
{
typedef typename Kernel::DstEvaluatorType::XprType DstXprType;
EIGEN_STATIC_ASSERT(int(DstXprType::SizeAtCompileTime) == 0,
EIGEN_INTERNAL_ERROR_PLEASE_FILE_A_BUG_REPORT)
}
};
/************************
*** Default traversal ***
************************/
@ -572,14 +589,15 @@ struct dense_assignment_loop<Kernel, SliceVectorizedTraversal, InnerUnrolling>
typedef typename Kernel::DstEvaluatorType::XprType DstXprType;
typedef typename Kernel::PacketType PacketType;
enum { size = DstXprType::InnerSizeAtCompileTime,
enum { innerSize = DstXprType::InnerSizeAtCompileTime,
packetSize =unpacket_traits<PacketType>::size,
vectorizableSize = (size/packetSize)*packetSize };
vectorizableSize = (innerSize/packetSize)*packetSize,
size = DstXprType::SizeAtCompileTime };
for(Index outer = 0; outer < kernel.outerSize(); ++outer)
{
copy_using_evaluator_innervec_InnerUnrolling<Kernel, 0, vectorizableSize, 0, 0>::run(kernel, outer);
copy_using_evaluator_DefaultTraversal_InnerUnrolling<Kernel, vectorizableSize, size>::run(kernel, outer);
copy_using_evaluator_DefaultTraversal_InnerUnrolling<Kernel, vectorizableSize, innerSize>::run(kernel, outer);
}
}
};