From a7a12f5c3654da554ad6197beff0f0fc54681c92 Mon Sep 17 00:00:00 2001
From: Matthew Sloyan <matthew.sloyan@arm.com>
Date: Thu, 6 May 2021 10:05:28 +0100
Subject: IVGCVSW-5969 TfLiteDelegate: Add PACK operator Support

 * Added support for PACK which is equivalent to Arm NN STACK

Signed-off-by: Matthew Sloyan <matthew.sloyan@arm.com>
Change-Id: I9ea134d0310eeea1caba30a8b9221712e9487c75
---
 delegate/src/Pack.hpp | 109 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 109 insertions(+)
 create mode 100644 delegate/src/Pack.hpp

(limited to 'delegate/src/Pack.hpp')

diff --git a/delegate/src/Pack.hpp b/delegate/src/Pack.hpp
new file mode 100644
index 0000000000..59851cd637
--- /dev/null
+++ b/delegate/src/Pack.hpp
@@ -0,0 +1,109 @@
+//
+// Copyright © 2021 Arm Ltd and Contributors. All rights reserved.
+// SPDX-License-Identifier: MIT
+//
+
+#pragma once
+
+#include <tensorflow/lite/builtin_ops.h>
+#include <tensorflow/lite/c/builtin_op_data.h>
+#include <tensorflow/lite/c/common.h>
+#include <tensorflow/lite/minimal_logging.h>
+
+namespace armnnDelegate
+{
+
+TfLiteStatus VisitPackOperator(DelegateData& delegateData,
+                               TfLiteContext* tfLiteContext,
+                               TfLiteNode* tfLiteNode,
+                               int nodeIndex,
+                               int32_t operatorCode)
+{
+    unsigned int numInputs = tfLiteNode->inputs->size;
+    if (numInputs < 1)
+    {
+        TF_LITE_MAYBE_KERNEL_LOG(
+                tfLiteContext, "TfLiteArmnnDelegate: Must have at least one input in (%d != %d) in node #%d",
+                1, numInputs, nodeIndex);
+        return kTfLiteError;
+    }
+
+    TF_LITE_ENSURE_STATUS(ValidateNumOutputs(tfLiteContext, tfLiteNode, 1, nodeIndex));
+
+    const TfLiteTensor* tfLiteTensors = tfLiteContext->tensors;
+
+    // Validate all inputs and get TensorInfo
+    std::vector<armnn::TensorInfo> inputTensorInfos;
+    for (unsigned int i = 0; i < numInputs; ++i)
+    {
+        const TfLiteTensor& tfLiteInputTensor = tfLiteTensors[tfLiteNode->inputs->data[i]];
+        if (!IsValid(tfLiteContext, tfLiteInputTensor, operatorCode, nodeIndex))
+        {
+            return kTfLiteError;
+        }
+
+        armnn::TensorInfo inputTensorInfo = GetTensorInfoForTfLiteTensor(tfLiteInputTensor);
+        inputTensorInfos.emplace_back(inputTensorInfo);
+    }
+
+    // Convert input tensors to const armnn::TensorInfo* type for FORWARD_LAYER_SUPPORT_FUNC.
+    std::vector<const armnn::TensorInfo*> inputConstTensorInfos;
+    std::transform(inputTensorInfos.begin(),
+                   inputTensorInfos.end(),
+                   std::back_inserter(inputConstTensorInfos),
+                   [](armnn::TensorInfo& t)->const armnn::TensorInfo*{ return &t; });
+
+    // Validate output and get TensorInfo
+    const TfLiteTensor& tfLiteOutputTensor = tfLiteTensors[tfLiteNode->outputs->data[0]];
+    if (!IsValid(tfLiteContext, tfLiteOutputTensor, operatorCode, nodeIndex))
+    {
+        return kTfLiteError;
+    }
+
+    const armnn::TensorInfo& outputTensorInfo = GetTensorInfoForTfLiteTensor(tfLiteOutputTensor);
+
+    armnn::StackDescriptor desc;
+    desc.m_NumInputs = static_cast<uint32_t>(numInputs);
+
+    // Get axis from TfLite parameters
+    auto* params = reinterpret_cast<TfLitePackParams*>(tfLiteNode->builtin_data);
+    desc.m_Axis = static_cast<uint32_t>(params->axis);
+
+    // Use the tensor shape of the first input as the "correct" input shape in the descriptor
+    desc.m_InputShape = inputTensorInfos[0].GetShape();
+
+    // Check if supported
+    bool isSupported = false;
+    auto validateFunc = [&](const armnn::TensorInfo& outputTensorInfo, bool& isSupported)
+    {
+        FORWARD_LAYER_SUPPORT_FUNC(__func__,
+                                   tfLiteContext,
+                                   IsStackSupported,
+                                   delegateData.m_Backends,
+                                   isSupported,
+                                   inputConstTensorInfos,
+                                   outputTensorInfo,
+                                   desc);
+    };
+
+    // If the m_Network is a nullptr, this signals that a prerequisite TfLite callback is required to clarify the
+    // support for the operator
+    // If supported, VisitPackOperator will be called again to add the layer to the network as seen below
+    if (!delegateData.m_Network)
+    {
+        validateFunc(outputTensorInfo, isSupported);
+        return isSupported ? kTfLiteOk : kTfLiteError;
+    }
+
+    // The TfLite Pack operator is equivalent to the ArmNN Stack operator
+    armnn::IConnectableLayer* layer = delegateData.m_Network->AddStackLayer(desc);
+    ARMNN_ASSERT(layer != nullptr);
+
+    armnn::IOutputSlot& outputSlot = layer->GetOutputSlot(0);
+    outputSlot.SetTensorInfo(outputTensorInfo);
+
+    // Connect
+    return Connect(layer, tfLiteNode, delegateData);
+}
+
+} // namespace armnnDelegate
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