From 4af561666b0ce5c12164447a5f7eb9722abb85f8 Mon Sep 17 00:00:00 2001
From: Francis Murtagh <francis.murtagh@arm.com>
Date: Tue, 20 Apr 2021 16:37:55 +0100
Subject: IVGCVSW-5816 Constant memory access

 * Add new class ManagedConstTensorHandle to Unmap when out of scope
 * Integrate into existing layers that have constants
 * Add unit tests

Signed-off-by: Francis Murtagh <francis.murtagh@arm.com>
Change-Id: I0a05e14e438804b37e9862e76b5ca329483f6b45
---
 src/backends/backendsCommon/CpuTensorHandle.hpp    | 67 ++++++++++++++++++++++
 .../test/DefaultAsyncExecuteTest.cpp               |  1 -
 2 files changed, 67 insertions(+), 1 deletion(-)

(limited to 'src/backends/backendsCommon')

diff --git a/src/backends/backendsCommon/CpuTensorHandle.hpp b/src/backends/backendsCommon/CpuTensorHandle.hpp
index a300fe09c2..fdd2439b41 100644
--- a/src/backends/backendsCommon/CpuTensorHandle.hpp
+++ b/src/backends/backendsCommon/CpuTensorHandle.hpp
@@ -175,4 +175,71 @@ const void* ConstCpuTensorHandle::GetConstTensor() const;
 template <>
 void* CpuTensorHandle::GetTensor() const;
 
+class ManagedConstTensorHandle
+{
+
+public:
+    explicit ManagedConstTensorHandle(std::shared_ptr<ConstCpuTensorHandle> ptr)
+        : m_Mapped(false)
+        , m_TensorHandle(std::move(ptr)) {};
+
+    /// RAII Managed resource Unmaps MemoryArea once out of scope
+    const void* Map(bool blocking = true)
+    {
+        if (m_TensorHandle)
+        {
+            auto pRet = m_TensorHandle->Map(blocking);
+            m_Mapped = true;
+            return pRet;
+        }
+        else
+        {
+            throw armnn::Exception("Attempting to Map null TensorHandle");
+        }
+
+    }
+
+    // Delete copy constructor as it's unnecessary
+    ManagedConstTensorHandle(const ConstCpuTensorHandle& other) = delete;
+
+    // Delete copy assignment as it's unnecessary
+    ManagedConstTensorHandle& operator=(const ManagedConstTensorHandle& other) = delete;
+
+    // Delete move assignment as it's unnecessary
+    ManagedConstTensorHandle& operator=(ManagedConstTensorHandle&& other) noexcept = delete;
+
+    ~ManagedConstTensorHandle()
+    {
+        // Bias tensor handles need to be initialized empty before entering scope of if statement checking if enabled
+        if (m_TensorHandle)
+        {
+            Unmap();
+        }
+    }
+
+    void Unmap()
+    {
+        // Only unmap if mapped and TensorHandle exists.
+        if (m_Mapped && m_TensorHandle)
+        {
+            m_TensorHandle->Unmap();
+            m_Mapped = false;
+        }
+    }
+
+    const TensorInfo& GetTensorInfo() const
+    {
+        return m_TensorHandle->GetTensorInfo();
+    }
+
+    bool IsMapped() const
+    {
+        return m_Mapped;
+    }
+
+private:
+    bool m_Mapped;
+    std::shared_ptr<ConstCpuTensorHandle> m_TensorHandle;
+};
+
 } // namespace armnn
diff --git a/src/backends/backendsCommon/test/DefaultAsyncExecuteTest.cpp b/src/backends/backendsCommon/test/DefaultAsyncExecuteTest.cpp
index 0d4595210e..56a794e77c 100644
--- a/src/backends/backendsCommon/test/DefaultAsyncExecuteTest.cpp
+++ b/src/backends/backendsCommon/test/DefaultAsyncExecuteTest.cpp
@@ -243,7 +243,6 @@ BOOST_AUTO_TEST_CASE(TestDefaultAsyncExeuteWithThreads)
     ValidateTensor(workingMemDescriptor2.m_Inputs[0], expectedExecuteval2);
 }
 
-
 BOOST_AUTO_TEST_SUITE_END()
 
 }
\ No newline at end of file
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