MLCE-1138 Issue with Delegate supporting FP16 models

 * Fixed issue where backends were asked to support FP16 layers that would
   be optimized out.
 * Fixed issue where backends were asked to support non-constant filter
   and bias tensors when those tensors would be replaced by constant
   tensors during optimization.

Signed-off-by: Mike Kelly <mike.kelly@arm.com>
Change-Id: Ib54b9cb99d5014e27172841a665daf57d1d5b23d

1 files changed, 77 insertions, 0 deletions

diff --git a/delegate/classic/src/SharedFunctions.cpp b/delegate/classic/src/SharedFunctions.cpp
index bcff3a1dd0..53136b521e 100644
--- a/delegate/classic/src/SharedFunctions.cpp
+++ b/delegate/classic/src/SharedFunctions.cpp
@@ -110,6 +110,83 @@ TfLiteStatus ValidateFusedActivationOperator(DelegateData& delegateData,
     return isSupported ? kTfLiteOk : kTfLiteError;
 }
 
+TfLiteNode* GetNodeConnectedToInput(TfLiteContext* tfLiteContext,
+                                    int32_t& connectedIndex,
+                                    int32_t inputIdx)
+{
+    TfLiteIntArray* executionPlan = nullptr;
+    if (tfLiteContext->GetExecutionPlan(tfLiteContext, &executionPlan) != kTfLiteOk)
+    {
+        TF_LITE_KERNEL_LOG(tfLiteContext, "TfLiteArmnnDelegate: Unable to get graph execution plan.");
+        return nullptr;
+    }
+
+    for (int i = 0; i < executionPlan->size; ++i)
+    {
+        connectedIndex = executionPlan->data[i];
+
+        // If TfLite nodes can be delegated to ArmNN
+        TfLiteNode* connectedNode = nullptr;
+        TfLiteRegistration* tfLiteRegistration = nullptr;
+        if (tfLiteContext->GetNodeAndRegistration(
+                tfLiteContext, connectedIndex, &connectedNode, &tfLiteRegistration) != kTfLiteOk)
+        {
+            TF_LITE_KERNEL_LOG(tfLiteContext,
+                               "TfLiteArmnnDelegate: Unable to get node and registration for node %d.",
+                               connectedIndex);
+            continue;
+        }
+        for (int j= 0; j < connectedNode->outputs->size; ++j)
+        {
+            if (connectedNode->outputs->data[j] == inputIdx)
+            {
+                return connectedNode;
+            }
+        }
+    }
+    // No node found so set connectedIndex to -1
+    connectedIndex = -1;
+    return nullptr;
+}
+
+bool WillInputBeOptimizedToConst(TfLiteContext* tfLiteContext, int32_t inputIdx)
+{
+    int32_t connectedIndex;
+    TfLiteNode* connectedNode = GetNodeConnectedToInput(tfLiteContext, connectedIndex, inputIdx);
+
+    if (connectedNode)
+    {
+        TfLiteRegistration* tfLiteRegistration = nullptr;
+
+        if (tfLiteContext->GetNodeAndRegistration(tfLiteContext, connectedIndex, &connectedNode, &tfLiteRegistration)
+            == kTfLiteOk)
+        {
+            switch (tfLiteRegistration->builtin_code)
+            {
+                case kTfLiteBuiltinDequantize:
+                {
+                    if (connectedNode->inputs->size >= 1)
+                    {
+                        const TfLiteTensor* tfLiteTensors = tfLiteContext->tensors;
+                        const TfLiteTensor& tfLiteInputTensor = tfLiteTensors[connectedNode->inputs->data[0]];
+
+                        // If the input to the Dequantize is a Constant then both that Constant layer and the Dequantize
+                        // layer will be replaced by a single Constant layer containing the dequantized values.
+                        if (tflite::IsConstantTensor(&tfLiteInputTensor))
+                        {
+                            return true;
+                        }
+                    }
+                    break;
+                }
+                default:
+                {
+                }
+            }
+        }
+    }
+    return false;
+}
 
 } // namespace armnnDelegate