Export custom attributes on Times node to ONNX file (#3709)

Source/CNTKv2LibraryDll/proto/onnx/CNTKToONNX.cpp

@@ -7312,6 +7312,80 @@ std::vector<int64_t> CNTKToONNXHelper::BroadcastInputs(std::vector<onnxruntime::
     return broadcast_shape;
 }
 
+// Forward declaration
+static std::string SerializeDictionaryValueToString(const DictionaryValue& val);
+
+static std::string SerializeVectorToString(const std::vector<DictionaryValue>& vals)
+{
+    bool first = true;
+    std::string str = "[";
+    for (const auto& v : vals)
+    {
+        if (first)
+        {
+            first = false;
+        }
+        else
+        {
+            str += ",";
+        }
+        str += SerializeDictionaryValueToString(v);
+    }
+    str += "]";
+    return str;
+}
+
+static std::string SerializeDictionaryToString(const Dictionary& dict)
+{
+    bool first = true;
+    std::string str = "{";
+    for (const auto& kv : dict)
+    {
+        auto key = Microsoft::MSR::CNTK::ToLegacyString(Microsoft::MSR::CNTK::ToUTF8(kv.first));
+        if (first)
+        {
+          first = false;
+        }
+        else
+        {
+          str += ",";
+        }
+        str += "\"" + key + "\":" + SerializeDictionaryValueToString(kv.second);
+    }
+    str += "}";
+    return str;
+}
+
+// Valid DictionaryValues that can be converted to string:
+// Bool, Int, SzieT, Float, Double, String, and Vector or Dictionary of aforementioned types.
+static std::string SerializeDictionaryValueToString(const DictionaryValue& val)
+{
+    auto value_type = val.ValueType();
+    switch (value_type)
+    {
+    case DictionaryValue::Type::Bool:
+        return val.Value<bool>() ? "true" : "false";
+    case DictionaryValue::Type::Int:
+        return std::to_string(val.Value<int>());
+    case DictionaryValue::Type::SizeT:
+        return std::to_string(val.Value<size_t>());
+    case DictionaryValue::Type::Float:
+        return std::to_string(val.Value<float>());
+    case DictionaryValue::Type::Double:
+        return std::to_string(val.Value<double>());
+    case DictionaryValue::Type::String:
+        return "\"" + Microsoft::MSR::CNTK::ToLegacyString(Microsoft::MSR::CNTK::ToUTF8(val.Value<std::wstring>())) + "\"";
+    case DictionaryValue::Type::Dictionary:
+        return SerializeDictionaryToString(val.Value<Dictionary>());
+    case DictionaryValue::Type::Vector:
+        return SerializeVectorToString(val.Value<std::vector<DictionaryValue>>());
+    default:
+        // skip all other cases;
+        return "";
+    }
+    return "";
+}
+
 onnxruntime::Node* CNTKToONNXHelper::AddNode(const FunctionPtr& src, onnxruntime::Graph* graph, const std::vector<onnxruntime::NodeArg *>& inputs, const std::vector<onnxruntime::NodeArg *>& outputs)
 {
     onnxruntime::Node* node = nullptr;
@@ -7348,6 +7422,12 @@ onnxruntime::Node* CNTKToONNXHelper::AddNode(const FunctionPtr& src, onnxruntime
             bool input1HasBatchAxis = (input1Rank - reductionRank) == 2;
             bool input2HasBatchAxis = (input2Rank - reductionRank) == 2;
 
+            // some Times nodes may carry custom attributes that need to be saved in ONNX as NodeProto.doc_string
+            std::string customAttrsStr =
+                src->GetCustomAttributes().Size() == 0 ?
+				"" :
+                "{\"custom_attributes\":" + SerializeDictionaryToString(src->GetCustomAttributes()) + "}";
+
             if (reductionRank > 1 || py_api_output_rank_argument > 1) // We need to insert reshape.
             {
                 onnx::TypeProto matMulInput1Reshape, matMulInput2Reshape, matMulOutputShape;
@@ -7372,17 +7452,17 @@ onnxruntime::Node* CNTKToONNXHelper::AddNode(const FunctionPtr& src, onnxruntime
                     // these dimensions were reduced in ReduceRank
                     onnxruntime::NodeArg &matMulOutputNodeArg =
                         graph->GetOrCreateNodeArg(nodeName + string("_reshape"), &matMulOutputShape);
-                    graph->AddNode(nodeName, "MatMul", "", {&inputOutput1Arg, &inputOutput2Arg}, {&matMulOutputNodeArg});
+                    graph->AddNode(nodeName, "MatMul", customAttrsStr, {&inputOutput1Arg, &inputOutput2Arg}, {&matMulOutputNodeArg});
                     // node = graph->AddNode(nodeName + "_reshape", "Reshape", "", { input, &shapeInputArg }, { output });
                     std::vector<int64_t> finalOutputShape = ToINTS(*outputs[0]->TypeAsProto());
                     node = AddReshapeNodeImpl(graph, nodeName + "_output_reshape", &matMulOutputNodeArg, outputs[0], finalOutputShape);
                 }
                 else
-                    node = &graph->AddNode(nodeName, ToOPName(src), "", {&inputOutput1Arg, &inputOutput2Arg}, outputs);
+                    node = &graph->AddNode(nodeName, ToOPName(src), customAttrsStr, {&inputOutput1Arg, &inputOutput2Arg}, outputs);
             }
             else
             {
-                node = &graph->AddNode(nodeName, ToOPName(src), "", orderedInputs, outputs);
+                node = &graph->AddNode(nodeName, ToOPName(src), customAttrsStr, orderedInputs, outputs);
             }
         }
         else if (src->OpName() == L"LayerNormalization")