delegate/src/Split.hpp

//
// Copyright © 2020 Arm Ltd and Contributors. All rights reserved.
// SPDX-License-Identifier: MIT
//

#pragma once

#include "DelegateUtils.hpp"

#include <algorithm>
#include <iterator>
#include <vector>

namespace armnnDelegate
{

constexpr unsigned int MaxNumOfTensorDimensions = 5U;

TfLiteStatus VisitSplitOperator(DelegateData& delegateData,
                                TfLiteContext* tfLiteContext,
                                TfLiteNode* tfLiteNode,
                                int nodeIndex,
                                int32_t tfLiteSplitOperatorCode)
{
    TF_LITE_ENSURE_STATUS(ValidateNumInputs(tfLiteContext, tfLiteNode, 2, nodeIndex));

    auto* splitParameters = reinterpret_cast<TfLiteSplitParams*>(tfLiteNode->builtin_data);
    const unsigned int numSplits =  NonNegative(splitParameters->num_splits, nodeIndex);

    TF_LITE_ENSURE_STATUS(ValidateNumOutputs(tfLiteContext, tfLiteNode, numSplits, nodeIndex));

    const TfLiteTensor* tfLiteTensors = tfLiteContext->tensors;
    const TfLiteTensor& tfLiteAxisTensor = tfLiteTensors[tfLiteNode->inputs->data[0]];
    if (!IsValid(tfLiteContext, tfLiteAxisTensor, tfLiteSplitOperatorCode, nodeIndex))
    {
        return kTfLiteError;
    }

    const TfLiteTensor& tfLiteInputTensor = tfLiteTensors[tfLiteNode->inputs->data[1]];
    if (!IsValid(tfLiteContext, tfLiteInputTensor, tfLiteSplitOperatorCode, nodeIndex))
    {
        return kTfLiteError;
    }

    const armnn::TensorInfo& inputTensorInfo = GetTensorInfoForTfLiteTensor(tfLiteInputTensor);

    ARMNN_ASSERT(GetTensorInfoForTfLiteTensor(tfLiteAxisTensor).GetNumElements() == 1);
    auto* axisTensorDataPtr = tflite::GetTensorData<int32_t>(&tfLiteAxisTensor);
    std::vector<int32_t> axisTensorData(axisTensorDataPtr, axisTensorDataPtr + 1);
    int32_t axis = axisTensorData[0];

    auto inputDimensions = static_cast<int32_t>(inputTensorInfo.GetNumDimensions());
    if (((axis < -inputDimensions) && (axis < 0)) || ((axis >= inputDimensions) && (axis > 0)))
    {
        // Square bracket denotes inclusive n while parenthesis denotes exclusive n
        // E.g. Rank 4 tensor can have axis in range [-4, 3)
        // -1 == 3, -2 == 2, -3 == 1, -4 == 0
        TF_LITE_MAYBE_KERNEL_LOG(
                tfLiteContext,
                "TfLiteArmnnDelegate: Operation has invalid axis: #%d. Axis must be in range [-n, n) in node #%d:",
                axis, nodeIndex);
    }
    const unsigned int splitDim = ComputeWrappedIndex(axis, inputTensorInfo.GetNumDimensions());

    std::vector<armnn::TensorInfo> outputs;
    for (unsigned int i = 0; i < numSplits; ++i)
    {
        const TfLiteTensor& tfLiteOutputTensor = tfLiteTensors[tfLiteNode->outputs->data[i]];
        if (!IsValid(tfLiteContext, tfLiteOutputTensor, tfLiteSplitOperatorCode, nodeIndex))
        {
            return kTfLiteError;
        }
        outputs.push_back(GetTensorInfoForTfLiteTensor(tfLiteOutputTensor, true));
    }
    const std::vector<std::reference_wrapper<armnn::TensorInfo>> outputTensorInfos(outputs.begin(), outputs.end());

    auto inputDimSize = inputTensorInfo.GetNumDimensions();
    if (inputDimSize > MaxNumOfTensorDimensions)
    {
        TF_LITE_MAYBE_KERNEL_LOG(
            tfLiteContext,
            "TfLiteArmnnDelegate: The number of dimensions: #%d for input tensors of the split op cannot be greater "
            "than #%d in node #%d: ", inputDimSize, MaxNumOfTensorDimensions, nodeIndex);
        return kTfLiteError;
    }

    std::vector<unsigned int> splitterDimSizes(inputDimSize);

    // Add current input shape to splitterDimSizes
    for (unsigned int i = 0; i < inputDimSize; ++i)
    {
        splitterDimSizes[i] = inputTensorInfo.GetShape()[i];
    }

    if (splitterDimSizes[splitDim] % numSplits != 0)
    {
        TF_LITE_MAYBE_KERNEL_LOG(
            tfLiteContext,
            "TfLiteArmnnDelegate: Number of splits #%d must evenly divide the dimension #%d in node #%d: ",
            numSplits, splitterDimSizes[splitDim], nodeIndex);
        return kTfLiteError;
    }
    splitterDimSizes[splitDim] /= numSplits;

    armnn::SplitterDescriptor splitDescriptor(numSplits, inputDimSize);
    for (unsigned int j = 0; j < numSplits; ++j)
    {
        // Set the size of the views.
        for (unsigned int dimIdx = 0; dimIdx < splitterDimSizes.size(); ++dimIdx)
        {
            splitDescriptor.SetViewSize(j, dimIdx, splitterDimSizes[dimIdx]);
        }
        splitDescriptor.SetViewOriginCoord(j, splitDim, splitterDimSizes[splitDim] * j);
    }

    if (!delegateData.m_Network)
    {
        // Check if supported
        bool isSupported = false;
        FORWARD_LAYER_SUPPORT_FUNC("SPLIT",
                                   tfLiteContext,
                                   IsSplitterSupported,
                                   delegateData.m_Backends,
                                   isSupported,
                                   inputTensorInfo,
                                   outputTensorInfos,
                                   splitDescriptor);
        return isSupported ? kTfLiteOk : kTfLiteError;
    }

    armnn::IConnectableLayer* layer = delegateData.m_Network->AddSplitterLayer(splitDescriptor);
    ARMNN_ASSERT(layer != nullptr);

    for (unsigned int k = 0; k < layer->GetNumOutputSlots(); ++k)
    {
        layer->GetOutputSlot(k).SetTensorInfo(outputs[k]);
    }

    // Connect the input slots
    delegateData.m_OutputSlotForNode[tfLiteNode->inputs->data[1]]->Connect(layer->GetInputSlot(0));

    // Prepare output slots
    for (unsigned int outputIndex = 0; outputIndex < layer->GetNumOutputSlots(); ++outputIndex)
    {
        armnn::IOutputSlot& outputSlot = layer->GetOutputSlot(outputIndex);
        delegateData.m_OutputSlotForNode[
            static_cast<unsigned long>(tfLiteNode->outputs->data[outputIndex])] = &outputSlot;
    }

    return kTfLiteOk;
}

TfLiteStatus VisitSplitVOperator(DelegateData& delegateData,
                                 TfLiteContext* tfLiteContext,
                                 TfLiteNode* tfLiteNode,
                                 int nodeIndex,
                                 int32_t tfLiteSplitVOperatorCode)
{
    TF_LITE_ENSURE_STATUS(ValidateNumInputs(tfLiteContext, tfLiteNode, 3, nodeIndex));

    const TfLiteTensor* tfLiteTensors = tfLiteContext->tensors;
    const TfLiteTensor& tfLiteInputTensor = tfLiteTensors[tfLiteNode->inputs->data[0]];
    if (!IsValid(tfLiteContext, tfLiteInputTensor, tfLiteSplitVOperatorCode, nodeIndex))
    {
        return kTfLiteError;
    }

    const TfLiteTensor& tfLiteSplitsTensor = tfLiteTensors[tfLiteNode->inputs->data[1]];
    if (!IsValid(tfLiteContext, tfLiteSplitsTensor, tfLiteSplitVOperatorCode, nodeIndex))
    {
        return kTfLiteError;
    }

    const TfLiteTensor& tfLiteAxisTensor = tfLiteTensors[tfLiteNode->inputs->data[2]];
    if (!IsValid(tfLiteContext, tfLiteAxisTensor, tfLiteSplitVOperatorCode, nodeIndex))
    {
        return kTfLiteError;
    }

    const armnn::TensorInfo& inputTensorInfo = GetTensorInfoForTfLiteTensor(tfLiteInputTensor);
    const armnn::TensorInfo& splitsTensorInfo = GetTensorInfoForTfLiteTensor(tfLiteSplitsTensor);
    ARMNN_ASSERT(splitsTensorInfo.GetNumDimensions() == 1);
    ARMNN_ASSERT(GetTensorInfoForTfLiteTensor(tfLiteAxisTensor).GetNumElements() == 1);

    auto* axisTensorDataPtr = tflite::GetTensorData<int32_t>(&tfLiteAxisTensor);
    std::vector<int32_t> axisTensorData(axisTensorDataPtr, axisTensorDataPtr + 1);
    int32_t axis = axisTensorData[0];

    auto inputDimensions = static_cast<int32_t>(inputTensorInfo.GetNumDimensions());
    if (((axis < -inputDimensions) && (axis < 0)) || ((axis >= inputDimensions) && (axis > 0)))
    {
        TF_LITE_MAYBE_KERNEL_LOG(
                tfLiteContext,
                "TfLiteArmnnDelegate: Operation has invalid axis: #%d. Axis must be in range [-n, n) in node #%d:",
                axis, nodeIndex);
    }
    const unsigned int splitDim = ComputeWrappedIndex(axisTensorData[0], inputTensorInfo.GetNumDimensions());

    auto* splitVParameters = reinterpret_cast<TfLiteSplitVParams*>(tfLiteNode->builtin_data);
    unsigned int numSplits = 0;
    if (splitVParameters)
    {
        numSplits = NonNegative(splitVParameters->num_splits, nodeIndex);
    }
    else
    {
        numSplits = splitsTensorInfo.GetNumElements();
    }

    if (numSplits <= 0)
    {
        TF_LITE_MAYBE_KERNEL_LOG(
            tfLiteContext, "TfLiteArmnnDelegate: Invalid number of splits %d  in node #%d",
            numSplits, nodeIndex);
        return kTfLiteError;
    }

    TF_LITE_ENSURE_STATUS(ValidateNumOutputs(tfLiteContext, tfLiteNode, numSplits, nodeIndex));
    std::vector<armnn::TensorInfo> outputs;
    for (unsigned int i = 0; i < numSplits; ++i)
    {
        const TfLiteTensor& tfLiteOutputTensor = tfLiteTensors[tfLiteNode->outputs->data[i]];
        if (!IsValid(tfLiteContext, tfLiteOutputTensor, tfLiteSplitVOperatorCode, nodeIndex))
        {
            return kTfLiteError;
        }
        outputs.push_back(GetTensorInfoForTfLiteTensor(tfLiteOutputTensor, true));
    }
    const std::vector<std::reference_wrapper<armnn::TensorInfo>> outputTensorInfos(outputs.begin(), outputs.end());

    auto inputDimSize = inputTensorInfo.GetNumDimensions();
    if (inputDimSize > MaxNumOfTensorDimensions)
    {
        TF_LITE_MAYBE_KERNEL_LOG(
            tfLiteContext,
            "TfLiteArmnnDelegate: The number of dimensions: #%d for input tensors of the split op cannot be greater "
            "than #%d in node #%d: ", inputDimSize, MaxNumOfTensorDimensions, nodeIndex);
        return kTfLiteError;
    }

    std::vector<int32_t> splitsTensorData(numSplits);
    std::memcpy(splitsTensorData.data(), tfLiteSplitsTensor.data.data, splitsTensorInfo.GetNumBytes());


    unsigned int index         = 0;
    unsigned int inferredIndex = 0;
    int numberOfInferred       = 0;
    int splitSum = 0;

    for (auto splitData : splitsTensorData)
    {
        if (splitData < 0)
        {
            ++numberOfInferred;
            inferredIndex = index;
        }
        else
        {
            splitSum += splitData;
        }
        ++index;
    }

    // Check for inferred axis
    if (numberOfInferred == 0)
    {
        if (splitSum != armnn::numeric_cast<int>(inputTensorInfo.GetShape()[splitDim]))
        {
            TF_LITE_MAYBE_KERNEL_LOG(
                tfLiteContext, "TfLiteArmnnDelegate: SplitV split_sizes does not sum to the dimension of value along"
                               " split_dim in node #%d", nodeIndex);
            return kTfLiteError;
        }
    }
    else if (numberOfInferred == 1)
    {
        splitsTensorData[inferredIndex] = armnn::numeric_cast<int>(inputTensorInfo.GetShape()[splitDim]) - splitSum;
    }
    else
    {
        TF_LITE_MAYBE_KERNEL_LOG(
            tfLiteContext, "TfLiteArmnnDelegate: SplitV cannot infer split size for more than one split in node #%d",
            nodeIndex);
        return kTfLiteError;
    }

    armnn::SplitterDescriptor splitDescriptor(numSplits, inputDimSize);
    unsigned int accumSplit = 0;
    for (unsigned int j = 0; j < numSplits; ++j)
    {
        unsigned int splitSize = armnn::numeric_cast<unsigned int>(splitsTensorData[j]);

        // Set the size of the views.
        for (unsigned int dimIdx = 0; dimIdx < inputTensorInfo.GetNumDimensions(); ++dimIdx)
        {
            unsigned int dimSize = inputTensorInfo.GetShape()[dimIdx];
            if (dimIdx == splitDim)
            {
                dimSize = splitSize;
            }
            splitDescriptor.SetViewSize(j, dimIdx, dimSize);
        }

        splitDescriptor.SetViewOriginCoord(j, splitDim, accumSplit);
        accumSplit += splitSize;
    }

    if (!delegateData.m_Network)
    {
        // Check if supported
        bool isSupported = false;
        FORWARD_LAYER_SUPPORT_FUNC("SPLIT",
                                   tfLiteContext,
                                   IsSplitterSupported,
                                   delegateData.m_Backends,
                                   isSupported,
                                   inputTensorInfo,
                                   outputTensorInfos,
                                   splitDescriptor);
        return isSupported ? kTfLiteOk : kTfLiteError;
    }

    armnn::IConnectableLayer* layer = delegateData.m_Network->AddSplitterLayer(splitDescriptor);
    ARMNN_ASSERT(layer != nullptr);

    for (unsigned int k = 0; k < layer->GetNumOutputSlots(); ++k)
    {
        layer->GetOutputSlot(k).SetTensorInfo(outputs[k]);
    }

    // Connect
    return Connect(layer, tfLiteNode, delegateData);
}

} // namespace armnnDelegate