IVGCVSW-4007 Add StandInLayer for unsupported operations in TfLiteParser

* Fixed bug in custom operator support that caused all custom operators
  to be parsed as a DetectionPostProcessLayer
* Added support for handling unsupported operators (built-in or custom)
  by replacing them with a StandInLayer in the generated network
* Added options to TfLiteParser to control whether we want to use
  StandInLayers when we encounter unsupported operators, or we prefer
  to throw a ParserException as until now

Signed-off-by: Aron Virginas-Tar <Aron.Virginas-Tar@arm.com>
Change-Id: I125a63016c7c510b1fdde6033842db4f276718c4

1 files changed, 103 insertions, 50 deletions

diff --git a/src/armnnTfLiteParser/TfLiteParser.cpp b/src/armnnTfLiteParser/TfLiteParser.cpp
index e04f9adc9f..937131ccd7 100644
--- a/src/armnnTfLiteParser/TfLiteParser.cpp
+++ b/src/armnnTfLiteParser/TfLiteParser.cpp
@@ -427,42 +427,46 @@ bool CheckShape(const armnn::TensorShape& actual, const std::vector<int32_t>& ex
 
 } // <anonymous>
 
-TfLiteParser::TfLiteParser()
-: m_Network(nullptr, nullptr)
+TfLiteParser::TfLiteParser(const Optional<ITfLiteParser::TfLiteParserOptions>& options)
+: m_Options(options)
+, m_Network(nullptr, nullptr)
 , m_ParserFunctions(tflite::BuiltinOperator_MAX+1, &TfLiteParser::ParseUnsupportedOperator)
 {
     // register supported operators
-    m_ParserFunctions[tflite::BuiltinOperator_AVERAGE_POOL_2D]   =  &TfLiteParser::ParseAveragePool2D;
-    m_ParserFunctions[tflite::BuiltinOperator_BATCH_TO_SPACE_ND] =  &TfLiteParser::ParseBatchToSpaceND;
-    m_ParserFunctions[tflite::BuiltinOperator_CONCATENATION]     =  &TfLiteParser::ParseConcatenation;
-    m_ParserFunctions[tflite::BuiltinOperator_CONV_2D]           =  &TfLiteParser::ParseConv2D;
-    m_ParserFunctions[tflite::BuiltinOperator_DEPTHWISE_CONV_2D] =  &TfLiteParser::ParseDepthwiseConv2D;
-    m_ParserFunctions[tflite::BuiltinOperator_CUSTOM]            =  &TfLiteParser::ParseDetectionPostProcess;
-    m_ParserFunctions[tflite::BuiltinOperator_FULLY_CONNECTED]   =  &TfLiteParser::ParseFullyConnected;
-    m_ParserFunctions[tflite::BuiltinOperator_LOGISTIC]          =  &TfLiteParser::ParseLogistic;
-    m_ParserFunctions[tflite::BuiltinOperator_L2_NORMALIZATION]  =  &TfLiteParser::ParseL2Normalization;
-    m_ParserFunctions[tflite::BuiltinOperator_MAX_POOL_2D]       =  &TfLiteParser::ParseMaxPool2D;
-    m_ParserFunctions[tflite::BuiltinOperator_MAXIMUM]           =  &TfLiteParser::ParseMaximum;
-    m_ParserFunctions[tflite::BuiltinOperator_MINIMUM]           =  &TfLiteParser::ParseMinimum;
-    m_ParserFunctions[tflite::BuiltinOperator_RELU]              =  &TfLiteParser::ParseRelu;
-    m_ParserFunctions[tflite::BuiltinOperator_RELU6]             =  &TfLiteParser::ParseRelu6;
-    m_ParserFunctions[tflite::BuiltinOperator_RESHAPE]           =  &TfLiteParser::ParseReshape;
-    m_ParserFunctions[tflite::BuiltinOperator_RESIZE_BILINEAR]   =  &TfLiteParser::ParseResizeBilinear;
-    m_ParserFunctions[tflite::BuiltinOperator_SOFTMAX]           =  &TfLiteParser::ParseSoftmax;
-    m_ParserFunctions[tflite::BuiltinOperator_SPACE_TO_BATCH_ND] =  &TfLiteParser::ParseSpaceToBatchND;
-    m_ParserFunctions[tflite::BuiltinOperator_SQUEEZE]           =  &TfLiteParser::ParseSqueeze;
-    m_ParserFunctions[tflite::BuiltinOperator_STRIDED_SLICE]     =  &TfLiteParser::ParseStridedSlice;
-    m_ParserFunctions[tflite::BuiltinOperator_SUB]               =  &TfLiteParser::ParseSub;
-    m_ParserFunctions[tflite::BuiltinOperator_ADD]               =  &TfLiteParser::ParseAdd;
-    m_ParserFunctions[tflite::BuiltinOperator_MUL]               =  &TfLiteParser::ParseMul;
-    m_ParserFunctions[tflite::BuiltinOperator_MEAN]              =  &TfLiteParser::ParseMean;
-    m_ParserFunctions[tflite::BuiltinOperator_PACK]              =  &TfLiteParser::ParsePack;
-    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_TRANSPOSE]         =  &TfLiteParser::ParseTranspose;
-    m_ParserFunctions[tflite::BuiltinOperator_TRANSPOSE_CONV]    =  &TfLiteParser::ParseTransposeConv;
-    m_ParserFunctions[tflite::BuiltinOperator_UNPACK]            =  &TfLiteParser::ParseUnpack;
+    m_ParserFunctions[tflite::BuiltinOperator_AVERAGE_POOL_2D]   = &TfLiteParser::ParseAveragePool2D;
+    m_ParserFunctions[tflite::BuiltinOperator_BATCH_TO_SPACE_ND] = &TfLiteParser::ParseBatchToSpaceND;
+    m_ParserFunctions[tflite::BuiltinOperator_CONCATENATION]     = &TfLiteParser::ParseConcatenation;
+    m_ParserFunctions[tflite::BuiltinOperator_CONV_2D]           = &TfLiteParser::ParseConv2D;
+    m_ParserFunctions[tflite::BuiltinOperator_DEPTHWISE_CONV_2D] = &TfLiteParser::ParseDepthwiseConv2D;
+    m_ParserFunctions[tflite::BuiltinOperator_CUSTOM]            = &TfLiteParser::ParseCustomOperator;
+    m_ParserFunctions[tflite::BuiltinOperator_FULLY_CONNECTED]   = &TfLiteParser::ParseFullyConnected;
+    m_ParserFunctions[tflite::BuiltinOperator_LOGISTIC]          = &TfLiteParser::ParseLogistic;
+    m_ParserFunctions[tflite::BuiltinOperator_L2_NORMALIZATION]  = &TfLiteParser::ParseL2Normalization;
+    m_ParserFunctions[tflite::BuiltinOperator_MAX_POOL_2D]       = &TfLiteParser::ParseMaxPool2D;
+    m_ParserFunctions[tflite::BuiltinOperator_MAXIMUM]           = &TfLiteParser::ParseMaximum;
+    m_ParserFunctions[tflite::BuiltinOperator_MINIMUM]           = &TfLiteParser::ParseMinimum;
+    m_ParserFunctions[tflite::BuiltinOperator_RELU]              = &TfLiteParser::ParseRelu;
+    m_ParserFunctions[tflite::BuiltinOperator_RELU6]             = &TfLiteParser::ParseRelu6;
+    m_ParserFunctions[tflite::BuiltinOperator_RESHAPE]           = &TfLiteParser::ParseReshape;
+    m_ParserFunctions[tflite::BuiltinOperator_RESIZE_BILINEAR]   = &TfLiteParser::ParseResizeBilinear;
+    m_ParserFunctions[tflite::BuiltinOperator_SOFTMAX]           = &TfLiteParser::ParseSoftmax;
+    m_ParserFunctions[tflite::BuiltinOperator_SPACE_TO_BATCH_ND] = &TfLiteParser::ParseSpaceToBatchND;
+    m_ParserFunctions[tflite::BuiltinOperator_SQUEEZE]           = &TfLiteParser::ParseSqueeze;
+    m_ParserFunctions[tflite::BuiltinOperator_STRIDED_SLICE]     = &TfLiteParser::ParseStridedSlice;
+    m_ParserFunctions[tflite::BuiltinOperator_SUB]               = &TfLiteParser::ParseSub;
+    m_ParserFunctions[tflite::BuiltinOperator_ADD]               = &TfLiteParser::ParseAdd;
+    m_ParserFunctions[tflite::BuiltinOperator_MUL]               = &TfLiteParser::ParseMul;
+    m_ParserFunctions[tflite::BuiltinOperator_MEAN]              = &TfLiteParser::ParseMean;
+    m_ParserFunctions[tflite::BuiltinOperator_PACK]              = &TfLiteParser::ParsePack;
+    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_TRANSPOSE]         = &TfLiteParser::ParseTranspose;
+    m_ParserFunctions[tflite::BuiltinOperator_TRANSPOSE_CONV]    = &TfLiteParser::ParseTransposeConv;
+    m_ParserFunctions[tflite::BuiltinOperator_UNPACK]            = &TfLiteParser::ParseUnpack;
+
+    // register supported custom operators
+    m_CustomParserFunctions["TFLite_Detection_PostProcess"]      = &TfLiteParser::ParseDetectionPostProcess;
 }
 
 void TfLiteParser::ResetParser()
@@ -675,25 +679,74 @@ void TfLiteParser::RegisterConsumerOfTensor(size_t subgraphIndex,
     tensorSlots.inputSlots.push_back(slot);
 }
 
+void TfLiteParser::ParseCustomOperator(size_t subgraphIndex, size_t operatorIndex)
+{
+    CHECK_MODEL(m_Model, subgraphIndex, operatorIndex);
+
+    // NOTE: By default we presume the custom operator is not supported
+    auto customParserFunction = &TfLiteParser::ParseUnsupportedOperator;
+
+    // Identify custom code defined for custom operator
+    const auto& operatorPtr = m_Model->subgraphs[subgraphIndex]->operators[operatorIndex];
+    const auto& customCode  = m_Model->operator_codes[operatorPtr->opcode_index]->custom_code;
+
+    // Find parser function that correspondes to custom code (if any)
+    auto iterator = m_CustomParserFunctions.find(customCode);
+    if (iterator != m_CustomParserFunctions.end())
+    {
+        customParserFunction = iterator->second;
+    }
+
+    // Run parser function
+    (this->*customParserFunction)(subgraphIndex, operatorIndex);
+}
+
 void TfLiteParser::ParseUnsupportedOperator(size_t subgraphIndex, size_t operatorIndex)
 {
     CHECK_MODEL(m_Model, subgraphIndex, operatorIndex);
+
     const auto & operatorPtr = m_Model->subgraphs[subgraphIndex]->operators[operatorIndex];
-    //
+
     auto opcodeIndex = operatorPtr->opcode_index;
-    auto opcode = m_Model->operator_codes[opcodeIndex]->builtin_code;
+    auto opcode      = m_Model->operator_codes[opcodeIndex]->builtin_code;
 
-    throw ParseException(
-        boost::str(
-            boost::format("Operator not supported. "
-                          "subgraph:%1% operator:%2% "
-                          "opcode_index:%3% opcode:%4% / %5% %6%") %
-                          subgraphIndex %
-                          operatorIndex %
-                          opcodeIndex %
-                          opcode %
-                          tflite::EnumNameBuiltinOperator(opcode) %
-                          CHECK_LOCATION().AsString()));
+    if (!m_Options || !m_Options.value().m_StandInLayerForUnsupported)
+    {
+        // Do not add StandInLayer, throw ParseException instead
+        throw ParseException(
+            boost::str(
+                boost::format("Operator not supported. "
+                              "subgraph:%1% operator:%2% "
+                              "opcode_index:%3% opcode:%4% / %5% %6%") %
+                              subgraphIndex %
+                              operatorIndex %
+                              opcodeIndex %
+                              opcode %
+                              tflite::EnumNameBuiltinOperator(opcode) %
+                              CHECK_LOCATION().AsString()));
+    }
+
+    auto inputs  = GetInputs(m_Model, subgraphIndex, operatorIndex);
+    auto outputs = GetOutputs(m_Model, subgraphIndex, operatorIndex);
+
+    const unsigned int numInputs  = boost::numeric_cast<unsigned int>(inputs.size());
+    const unsigned int numOutputs = boost::numeric_cast<unsigned int>(outputs.size());
+
+    StandInDescriptor descriptor(numInputs, numOutputs);
+    auto layerName = boost::str(boost::format("StandIn:%1%:%2%:%3%") % subgraphIndex % operatorIndex % opcode);
+
+    // Add a non-executable StandInLayer as a placeholder for any unsupported operator
+    IConnectableLayer* layer = m_Network->AddStandInLayer(descriptor, layerName.c_str());
+    for (unsigned int i = 0u; i < numOutputs; ++i)
+    {
+        layer->GetOutputSlot(i).SetTensorInfo(ToTensorInfo(outputs[i]));
+    }
+
+    auto inputTensorIds  = AsUnsignedVector(GetInputTensorIds(m_Model, subgraphIndex, operatorIndex));
+    auto outputTensorIds = AsUnsignedVector(GetOutputTensorIds(m_Model, subgraphIndex, operatorIndex));
+
+    RegisterInputSlots(subgraphIndex, operatorIndex, layer, inputTensorIds);
+    RegisterOutputSlots(subgraphIndex, operatorIndex, layer, outputTensorIds);
 }
 
 void TfLiteParser::ParseConv2D(size_t subgraphIndex, size_t operatorIndex)
@@ -2761,14 +2814,14 @@ std::vector<std::string> TfLiteParser::GetSubgraphOutputTensorNames(size_t subgr
     return result;
 }
 
-ITfLiteParser* ITfLiteParser::CreateRaw()
+ITfLiteParser* ITfLiteParser::CreateRaw(const Optional<ITfLiteParser::TfLiteParserOptions>& options)
 {
-    return new TfLiteParser();
+    return new TfLiteParser(options);
 }
 
-ITfLiteParserPtr ITfLiteParser::Create()
+ITfLiteParserPtr ITfLiteParser::Create(const Optional<ITfLiteParser::TfLiteParserOptions>& options)
 {
-    return ITfLiteParserPtr(CreateRaw(), &ITfLiteParser::Destroy);
+    return ITfLiteParserPtr(CreateRaw(options), &ITfLiteParser::Destroy);
 }
 
 void ITfLiteParser::Destroy(ITfLiteParser* parser)