[DML EP] Fix external data unpacking (#19415)

### Description
This change
55a6694
didn't take into account external data when unpacking initializer, and
therefore crashes when trying to unpack them.

Author: PatriceVignola

onnxruntime/core/providers/dml/DmlExecutionProvider/src/GraphDescBuilder.cpp

@@ -344,20 +344,25 @@ namespace Dml::GraphDescBuilder
                             dmlFusedNodeInputIndex < isConstGpuGraphInputCount &&
                             isConstGpuGraphInput[dmlFusedNodeInputIndex])
                         {
-                            // This is a highly inefficient approach to generating constant nodes.  It duplicates constant data 
-                            // across the graph input as well as every consumer's unique constant node.  However it is currently 
+                            // This is a highly inefficient approach to generating constant nodes.  It duplicates constant data
+                            // across the graph input as well as every consumer's unique constant node.  However it is currently
                             // only used for small inputs.
                             uint32_t c_maxConstNodeDataSize = 8;
 
-                            ComPtr<OnnxTensorWrapper> constantInput = constantCpuGraphInputGetter(arg->Name());
 
                             auto& operatorGraphInputNode = graphNodeCreateInfo.nodesAsOperatorDesc[operatorGraphInputEdge.ToNodeIndex];
                             std::vector<DmlBufferTensorDesc*> toNodeInputTensorDescs = operatorGraphInputNode->GetInputTensors();
                             DmlBufferTensorDesc* tensorDesc = toNodeInputTensorDescs[operatorGraphInputEdge.ToNodeInputIndex];
+                            ComPtr<OnnxTensorWrapper> constantInput;
 
-                            if (constantInput && tensorDesc->totalTensorSizeInBytes < c_maxConstNodeDataSize)
+                            if (tensorDesc->totalTensorSizeInBytes < c_maxConstNodeDataSize)
                             {
-                                // The tensor description's size should be no larger than the constant input unless it was rounded to 
+                                constantInput = constantCpuGraphInputGetter(arg->Name());
+                            }
+
+                            if (constantInput)
+                            {
+                                // The tensor description's size should be no larger than the constant input unless it was rounded to
                                 // the required alignment.
                                 assert(((constantInput->GetTensorByteSize() + 3) & ~3) >= tensorDesc->totalTensorSizeInBytes);
                                 size_t minimumConstantSize = std::min(constantInput->GetTensorByteSize(), gsl::narrow_cast<size_t>(tensorDesc->totalTensorSizeInBytes));

onnxruntime/core/providers/dml/DmlExecutionProvider/src/MLOperatorAuthorImpl.cpp

@@ -1123,7 +1123,7 @@ namespace Windows::AI::MachineLearning::Adapter
         }
         ORT_CATCH_RETURN
     }
-    
+
     template <class NodeInfoImpl_t, class Base1_t, class Base2_t>
     HRESULT STDMETHODCALLTYPE OpNodeInfoWrapper<NodeInfoImpl_t, Base1_t, Base2_t>::GetConstantInputTensor(uint32_t inputIndex, IMLOperatorTensor** tensor) const noexcept
     {
@@ -1168,7 +1168,7 @@ namespace Windows::AI::MachineLearning::Adapter
                                                  m_requiredConstantCpuInputs.begin(),
                                                  m_requiredConstantCpuInputs.end(),
                                                  inputIndex) != m_requiredConstantCpuInputs.end();
-                
+
                 // This shouldn't happen since kernel creation is deferred and repeated when required constant inputs are not present.
                 ORT_THROW_HR_IF(E_UNEXPECTED, inputRequiredAsConstant);
             }
@@ -1562,7 +1562,13 @@ namespace Windows::AI::MachineLearning::Adapter
     OnnxTensorWrapper::OnnxTensorWrapper(onnx::TensorProto* impl, const onnxruntime::Path& modelPath) : m_impl(impl)
     {
         // The tensor may be stored as raw data or in typed fields.
-        if (impl->has_raw_data())
+        if (impl->data_location() == onnx::TensorProto_DataLocation_EXTERNAL)
+        {
+            THROW_IF_NOT_OK(onnxruntime::utils::UnpackInitializerData(*impl, modelPath, m_unpackedExternalTensor));
+            m_dataPtr = reinterpret_cast<std::byte*>(m_unpackedExternalTensor.data());
+            m_tensorByteSize = m_unpackedExternalTensor.size();
+        }
+        else if (impl->has_raw_data())
         {
             m_dataPtr = reinterpret_cast<std::byte*>(impl->mutable_raw_data()->data());
             m_tensorByteSize = impl->raw_data().size();

onnxruntime/core/providers/dml/DmlExecutionProvider/src/MLOperatorAuthorImpl.h

@@ -309,6 +309,7 @@ class OnnxTensorWrapper : public WRL::Base<IMLOperatorTensor>, public Closable
  private:
     size_t m_tensorByteSize = 0;
     std::unique_ptr<std::byte[]> m_unpackedTensor;
+    std::vector<uint8_t> m_unpackedExternalTensor;
     std::byte* m_dataPtr = nullptr;
 
     // Lifetime is managed by the caller and guaranteed to outlive this class