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Tensor<T> slice pinning starts at the parent array instead of the slice

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#134,691 2 comentarios 0 reacciones 0 asignados Ver en GitHub

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Evaluación

Dificultad
2/5
Tiempo estimado
1-3 horas
Aptitud para principiantes
78/100
Tipo de issue
Error
Claridad
Bien especificado
Estado de actividad
Activo
Stack tecnológico
csharp
Área
backend

Línea de trabajo

Comienza con src/libraries/System.Numerics.Tensors/src/System/Numerics/Tensors/netcore/Tensor_1.cs, centrándote en GetPinnableReference() y GetPinnedHandle() para tensores segmentados. Ejecuta primero la reproducción basada en archivo TensorSlicePinning.cs y, después, verifica que el pinning comienza en el desplazamiento lógico del segmento y devuelve [11,12,21,22] con código de salida 0.

Escrito por el modelo de indexación a partir del texto del issue.

Descripción

area-System.Numerics.Tensors untriaged

Description

A contiguous Tensor<long> slice returns different values through its pinning APIs than through its indexer or tensor span. With System.Numerics.Tensors 10.0.9, GetPinnableReference() and GetPinnedHandle() start at the parent array rather than the beginning of the slice.

Scenario

I'm prototyping a .NET ONNX text-embedding pipeline. I want to use tensors through preprocessing, inference, and postprocessing, including passing contiguous slices to native inference without another data copy.

The shape is correct, but the pointer addresses the wrong part of the data. That means a native consumer can receive different inputs without a shape error. The repro below removes ONNX and the rest of my application. It only needs System.Numerics.Tensors.

Parent [3,2]       Logical slice [2,2], starting at [1,0]
[91,92]           excluded
[11,12]           [11,12]  <- expected pointer start
[21,22]           [21,22]

Observed pointer starts at 91, not 11.

Configuration

  • Windows x64
  • .NET SDK 10.0.401
  • Runtime .NET 10.0.12
  • NuGet System.Numerics.Tensors 10.0.9
  • JIT, net10.0; NativeAOT explicitly disabled

Reproduction Steps

You can find the runnable file-based app and captured output in this gist. The complete code is also included below.

Save the following as TensorSlicePinning.cs in a new directory outside a repository. File-based apps inherit project settings from parent directories.

#:package [email protected]
#:property TargetFramework=net10.0
#:property AllowUnsafeBlocks=true
#:property PublishAot=false

using System.Numerics.Tensors;

long[] values = [91, 92, 11, 12, 21, 22];
long[] expected = [11, 12, 21, 22];
var parent = Tensor.Create(values, [3, 2]);
var slice = parent.Slice([1, 0]);
Console.WriteLine($"Runtime: {System.Runtime.InteropServices.RuntimeInformation.FrameworkDescription}");
Console.WriteLine($"Shape: [{string.Join(",", slice.Lengths.ToArray())}]; strides: [{string.Join(",", slice.Strides.ToArray())}]");
Console.WriteLine($"Expected slice: [{string.Join(",", expected)}]");
Console.WriteLine($"Indexer first: {slice[0, 0]}");
Console.WriteLine($"Tensor span: [{string.Join(",", slice.AsTensorSpan().GetSpan([0, 0], 4).ToArray())}]");
Console.WriteLine($"Flattened: [{string.Join(",", slice.ToArray())}]");
Console.WriteLine($"Parent GetPinnableReference: {parent.GetPinnableReference()} (expected 91)");
long referenceFirst = slice.GetPinnableReference();
Console.WriteLine($"Slice GetPinnableReference: {referenceFirst} (expected 11)");
unsafe
{
    using var handle = slice.GetPinnedHandle();
    long[] pinned = new ReadOnlySpan<long>(handle.Pointer, 4).ToArray();
    Console.WriteLine($"Slice GetPinnedHandle: [{string.Join(",", pinned)}] (expected [{string.Join(",", expected)}])");
    bool matches = slice[0, 0] == 11 && slice.ToArray().SequenceEqual(expected)
        && slice.AsTensorSpan().GetSpan([0, 0], 4).SequenceEqual(expected)
        && referenceFirst == 11 && pinned.SequenceEqual(expected);
    Console.WriteLine(matches ? "PASS" : "FAIL: pinning does not start at the logical slice offset.");
    return matches ? 0 : 1;
}

dotnet run --file .\TensorSlicePinning.cs

Actual behavior

Compilation succeeds. Running the app produces the following output and exits with code 1:

Runtime: .NET 10.0.12
Shape: [2,2]; strides: [2,1]
Expected slice: [11,12,21,22]
Indexer first: 11
Tensor span: [11,12,21,22]
Flattened: [11,12,21,22]
Parent GetPinnableReference: 91 (expected 91)
Slice GetPinnableReference: 91 (expected 11)
Slice GetPinnedHandle: [91,92,11,12] (expected [11,12,21,22])
FAIL: pinning does not start at the logical slice offset.

Expected behavior

The reference and pointer should start at 11, the first element of the slice. Reading four elements should return [11,12,21,22], matching the indexer and tensor span. The app should exit with code 0.

Observation Expected Actual
Slice indexer, first element 11 11
Tensor-span and enumerated values [11,12,21,22] [11,12,21,22]
Slice GetPinnableReference() 11 91
Four values through slice GetPinnedHandle() [11,12,21,22] [91,92,11,12]
Process exit code 0 1

Other information

All pointer reads happen while the MemoryHandle is alive and stay within the allocated six-element array.

In the 10.0.9 source, Slice records _start, but GetPinnableReference() appears to return the array's first element without applying that offset. GetPinnedHandle() uses that reference. This looks related to the behavior above.

I've reproduced this on the configuration listed above. I haven't checked other versions or platforms.

Lenguaje dominante
C#
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Forks
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PR fusionados (30 d)
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