IVGCVSW-6416 AddFullyConnected API crashes without connected weights/bias layers

  * Created method in Graph.cpp/hpp ConstructErrorMessageForUnconnectedInputs() to
    verify weights and bias are set for FullyConnected layers.
  * Above method called in Graph.cpp InferTensorInfos() to print a more descriptive
    message when the weights or bias for a FullyConnectedLayer is not set.
  * Added try-catch in TestUtils.cpp Connect() to ensure input slot is available
    when connecting two layers. This ensures we catch the case where bias is
    is not enabled and we try and set a bias layer.
  * Added unit tests to check for LayerValidationError when weights or
    bias is not set on a FullyConnectedLayer.
  * Added unit test to check for LayerValidationError when bias is not
    enabled and we try and connect bias to FullyConnected Layer.
  * Seperated FullyConnected EndToEnd unit test method into two methods.
    First, performs tests on EndToEnd examples asserting output value.
    Second, performs tests on error catching.
  * Added comments to created methods.

Signed-off-by: Cathal Corbett <cathal.corbett@arm.com>
Change-Id: I5207d8c5ebacfff598556742ccd4f53eef7dee0c

3 files changed, 84 insertions, 14 deletions

diff --git a/src/armnn/Graph.cpp b/src/armnn/Graph.cpp
index 60bf328c9c..95104049a2 100644
--- a/src/armnn/Graph.cpp
+++ b/src/armnn/Graph.cpp
@@ -534,7 +534,7 @@ void Graph::VerifyConstantLayerSetTensorInfo() const
 {
     for (auto&& layer : TopologicalSort())
     {
-        if(layer->GetType() == armnn::LayerType::Constant)
+        if (layer->GetType() == armnn::LayerType::Constant)
         {
             for (auto&& output: layer->GetOutputSlots())
             {
@@ -562,15 +562,9 @@ void Graph::InferTensorInfos()
             const IOutputSlot* source = input.GetConnectedOutputSlot();
             if (source == NULL)
             {
-                std::ostringstream message;
-                message << "Input slot "
-                        << input.GetSlotIndex()
-                        << " not connected to an output slot on "
-                        << GetLayerTypeAsCString(layer->GetType())
-                        << " layer \""
-                        << layer->GetName()
-                        << "\"";
-                throw LayerValidationException(message.str());
+                // Throws exception due to a layer input not being connected to an output slot.
+                // Verifies input slot weights and bias are set for FullyConnected layers.
+                ConstructErrorMessageForUnconnectedInputs(layer, input.GetSlotIndex());
             }
 
             if (!source->IsTensorInfoSet())
@@ -578,9 +572,8 @@ void Graph::InferTensorInfos()
                 std::ostringstream message;
                 message << "Output slot TensorInfo not set on "
                         << GetLayerTypeAsCString(layer->GetType())
-                        << " layer \""
-                        << layer->GetName()
-                        << "\"";
+                        << " layer "
+                        << std::quoted(layer->GetName());
                 throw LayerValidationException(message.str());
             }
         }
@@ -592,4 +585,54 @@ void Graph::InferTensorInfos()
     }
 }
 
+/// Throws exception due to a layer input not being connected to an output slot.
+/// Verifies weights and bias are set for FullyConnected layers on input slots 1
+/// and 2 respectively. Method checks if bias is enabled before ensuring it is set.
+///
+/// @param layer constant pointer to a Layer object
+/// @param slotIndex input slot index of layer
+/// @throws LayerValidationException
+void Graph::ConstructErrorMessageForUnconnectedInputs(Layer* const layer,
+                                                      unsigned int slotIndex)
+{
+    std::ostringstream message;
+    bool noWeightsAndBias = false;
+
+    if (layer->GetType() == armnn::LayerType::FullyConnected && slotIndex > 0)
+    {
+        // If weights are not set and is bias enabled, also check if bias is set
+        if (slotIndex == 1 && layer->GetNumInputSlots() == 3)
+        {
+            const IOutputSlot* biasSource = layer->GetInputSlot(2).GetConnectedOutputSlot();
+            if (biasSource == NULL)
+            {
+                message << "FullyConnected layer weights and bias not set: ";
+                noWeightsAndBias = true;
+            }
+        }
+
+        // Only weights or bias are not set
+        if (!noWeightsAndBias)
+        {
+            if (slotIndex == 1)
+            {
+                message << "FullyConnected layer weights not set: ";
+            }
+            else
+            {
+                message << "FullyConnected layer bias not set: ";
+            }
+        }
+    }
+
+    std::string slotString = noWeightsAndBias ? "1 & 2" : std::to_string(slotIndex);
+    message << "Input slot(s) "
+            << slotString
+            << " not connected to an output slot on "
+            << GetLayerTypeAsCString(layer->GetType())
+            << " layer "
+            << std::quoted(layer->GetName());
+    throw LayerValidationException(message.str());
+}
+
 } // namespace armnn
diff --git a/src/armnn/Graph.hpp b/src/armnn/Graph.hpp
index d5fbeafed0..e2321bb0e4 100644
--- a/src/armnn/Graph.hpp
+++ b/src/armnn/Graph.hpp
@@ -268,6 +268,11 @@ private:
 
     std::map<const GraphEvent, std::list<IGraphObservable*>> m_Views;
     ShapeInferenceMethod m_ShapeInferenceMethod;
+
+    // Throws exception due to a layer input not being connected to an output slot.
+    /// Also verifies weights and bias are set for FullyConnected layers.
+    void ConstructErrorMessageForUnconnectedInputs(Layer* const layer,
+                                                   unsigned int slotIndex);
 };
 
 /// Common base class for layers in the graph.
diff --git a/src/armnn/test/TestUtils.cpp b/src/armnn/test/TestUtils.cpp
index 6020c7631c..97cc80c8a2 100644
--- a/src/armnn/test/TestUtils.cpp
+++ b/src/armnn/test/TestUtils.cpp
@@ -15,7 +15,29 @@ void Connect(armnn::IConnectableLayer* from, armnn::IConnectableLayer* to, const
     ARMNN_ASSERT(from);
     ARMNN_ASSERT(to);
 
-    from->GetOutputSlot(fromIndex).Connect(to->GetInputSlot(toIndex));
+    try
+    {
+        from->GetOutputSlot(fromIndex).Connect(to->GetInputSlot(toIndex));
+    }
+    catch (const std::out_of_range& exc)
+    {
+        std::ostringstream message;
+
+        if (to->GetType() == armnn::LayerType::FullyConnected && toIndex == 2)
+        {
+            message << "Tried to connect bias to FullyConnected layer when bias is not enabled: ";
+        }
+
+        message << "Failed to connect to input slot "
+                << toIndex
+                << " on "
+                << GetLayerTypeAsCString(to->GetType())
+                << " layer "
+                << std::quoted(to->GetName())
+                << " as the slot does not exist or is unavailable";
+        throw LayerValidationException(message.str());
+    }
+
     from->GetOutputSlot(fromIndex).SetTensorInfo(tensorInfo);
 }