IVGCVSW-2848 - Add TfLite Parser support for Unpack layer

* Added ParseUnpack in TfLiteParser
* New Unpack test file with test reproducing unpack in DeepSpeechV1 model
* Added documentation for supported Unpack to TensorflorLiteSupport.md

Signed-off-by: Nina Drozd <nina.drozd@arm.com>
Change-Id: Ie920d46254ff4b4ab544407ace4c1d489af83157

1 files changed, 84 insertions, 0 deletions

diff --git a/src/armnnTfLiteParser/TfLiteParser.cpp b/src/armnnTfLiteParser/TfLiteParser.cpp
index f689deedf6..86688add9d 100644
--- a/src/armnnTfLiteParser/TfLiteParser.cpp
+++ b/src/armnnTfLiteParser/TfLiteParser.cpp
@@ -468,6 +468,7 @@ TfLiteParser::TfLiteParser()
     m_ParserFunctions[tflite::BuiltinOperator_PAD]               =  &TfLiteParser::ParsePad;
     m_ParserFunctions[tflite::BuiltinOperator_SPLIT]             =  &TfLiteParser::ParseSplit;
     m_ParserFunctions[tflite::BuiltinOperator_TANH]              =  &TfLiteParser::ParseTanH;
+    m_ParserFunctions[tflite::BuiltinOperator_UNPACK]            =  &TfLiteParser::ParseUnpack;
 }
 
 void TfLiteParser::ResetParser()
@@ -1867,6 +1868,83 @@ void TfLiteParser::ParseDetectionPostProcess(size_t subgraphIndex, size_t operat
                                                               outputTensorIndexes[3]});
 }
 
+void TfLiteParser::ParseUnpack(size_t subgraphIndex, size_t operatorIndex)
+{
+    CHECK_MODEL(m_Model, subgraphIndex, operatorIndex);
+
+    const auto & operatorPtr = m_Model->subgraphs[subgraphIndex]->operators[operatorIndex];
+    const auto * options = operatorPtr->builtin_options.AsUnpackOptions();
+
+    // This unpackAxis indicates the axis to unpack
+    const unsigned int unpackAxis = CHECKED_NON_NEGATIVE(options->axis);
+
+    auto inputs = GetInputs(m_Model, subgraphIndex, operatorIndex);
+    CHECK_VALID_SIZE(inputs.size(), 1);
+
+    armnn::TensorInfo inputTensorInfo  = ToTensorInfo(inputs[0]);
+    unsigned int unpackNum = CHECKED_NON_NEGATIVE(options->num);
+    // If num is not defined, automatically infer from the length of the dimension axis.
+    if(unpackNum == 0)
+    {
+        unpackNum = inputTensorInfo.GetShape()[unpackAxis];
+    }
+
+    // If unpack number cannot be inferred and is still zero, throw ParseException.
+    if(unpackNum == 0)
+    {
+        throw ParseException("Number to unpack must greater than zero.");
+    }
+
+    auto outputs = GetOutputs(m_Model, subgraphIndex, operatorIndex);
+    CHECK_VALID_SIZE(outputs.size(), unpackNum);
+
+    auto inputDimSize = inputTensorInfo.GetNumDimensions();
+    std::vector<unsigned int> unpackDimSizes(inputDimSize);
+
+    // Add current input shape to unpackDimSizes
+    for (unsigned int i = 0; i < inputDimSize; ++i)
+    {
+        unpackDimSizes[i] = inputTensorInfo.GetShape()[i];
+    }
+
+    if (unpackDimSizes[unpackAxis] != unpackNum)
+    {
+        throw ParseException("Number to unpack must be the same as length of the dimension to "
+                             "unpack along.");
+    }
+
+    unpackDimSizes[unpackAxis] /= unpackNum;
+
+    SplitterDescriptor splitDesc(unpackNum, static_cast<unsigned int>(unpackDimSizes.size()));
+    for (unsigned int j = 0; j < unpackNum; ++j)
+    {
+        // Set the size of the views.
+        for (unsigned int dimIdx = 0; dimIdx < unpackDimSizes.size(); ++dimIdx)
+        {
+            splitDesc.SetViewSize(j, dimIdx, unpackDimSizes[dimIdx]);
+        }
+        splitDesc.SetViewOriginCoord(j, unpackAxis, unpackDimSizes[unpackAxis] * j);
+    }
+
+    auto layerName = boost::str(boost::format("Unpack:%1%:%2%") % subgraphIndex % operatorIndex);
+    IConnectableLayer* layer = m_Network->AddSplitterLayer(splitDesc, layerName.c_str());
+
+    auto inputTensorIndexes = AsUnsignedVector(GetInputTensorIds(m_Model, subgraphIndex, operatorIndex));
+    RegisterInputSlots(subgraphIndex, operatorIndex, layer, {inputTensorIndexes[0]});
+
+    TensorShape outShape = TensorShape(static_cast<unsigned int>(unpackDimSizes.size()),
+        unpackDimSizes.data());
+
+    for (unsigned int k = 0; k < layer->GetNumOutputSlots(); ++k)
+    {
+        layer->GetOutputSlot(k).SetTensorInfo(armnn::TensorInfo(outShape,
+            inputTensorInfo.GetDataType()));
+    }
+
+    auto outputTensorIndexes = AsUnsignedVector(GetOutputTensorIds(m_Model, subgraphIndex, operatorIndex));
+    RegisterOutputSlots(subgraphIndex, operatorIndex, layer, outputTensorIndexes);
+}
+
 void TfLiteParser::ParseSplit(size_t subgraphIndex, size_t operatorIndex)
 {
     CHECK_MODEL(m_Model, subgraphIndex, operatorIndex);
@@ -1876,6 +1954,12 @@ void TfLiteParser::ParseSplit(size_t subgraphIndex, size_t operatorIndex)
 
     const unsigned int numSplits = CHECKED_NON_NEGATIVE(options->num_splits);
 
+    // If number of splits cannot be inferred and is zero, throw ParseException.
+    if(numSplits == 0)
+    {
+        throw ParseException("Number to splits must greater than zero.");
+    }
+
     auto inputs = GetInputs(m_Model, subgraphIndex, operatorIndex);
     CHECK_VALID_SIZE(inputs.size(), 2);
     auto outputs = GetOutputs(m_Model, subgraphIndex, operatorIndex);