IVGCVSW-6469 Add MirrorPad FrontEnd and Ref Support

 * Added PaddingMode enum to PaddingDescriptor to enable Symmetric and
   Reflect padding.
 * Added Symmetric and Reflect Ref implementation.
 * Added Serializer & Deserializer support.
 * Added unit tests.

Signed-off-by: Matthew Sloyan <matthew.sloyan@arm.com>
Change-Id: I4bed907b31742b32ccefe5e8ca39a6f1e5bd9dee

3 files changed, 31 insertions, 3 deletions

diff --git a/include/armnn/Descriptors.hpp b/include/armnn/Descriptors.hpp
index 39ea824045..a8ad12ff8f 100644
--- a/include/armnn/Descriptors.hpp
+++ b/include/armnn/Descriptors.hpp
@@ -1060,17 +1060,20 @@ struct MeanDescriptor : BaseDescriptor
 /// A PadDescriptor for the PadLayer.
 struct PadDescriptor : BaseDescriptor
 {
-    PadDescriptor() : m_PadValue(0)
+    PadDescriptor() : m_PadValue(0), m_PaddingMode(PaddingMode::Constant)
     {}
 
-    PadDescriptor(const std::vector<std::pair<unsigned int, unsigned int>>& padList, const float& padValue = 0)
+    PadDescriptor(const std::vector<std::pair<unsigned int, unsigned int>>& padList,
+                  const float& padValue = 0,
+                  const PaddingMode& paddingMode = PaddingMode::Constant)
         : m_PadList(padList)
         , m_PadValue(padValue)
+        , m_PaddingMode(paddingMode)
     {}
 
     bool operator ==(const PadDescriptor& rhs) const
     {
-        return m_PadList == rhs.m_PadList && m_PadValue == rhs.m_PadValue;
+        return m_PadList == rhs.m_PadList && m_PadValue == rhs.m_PadValue && m_PaddingMode == rhs.m_PaddingMode;
     }
 
     /// @brief Specifies the padding for input dimension.
@@ -1081,6 +1084,9 @@ struct PadDescriptor : BaseDescriptor
 
     /// Optional value to use for padding, defaults to 0
     float m_PadValue;
+
+    /// Specifies the Padding mode (Constant, Reflect or Symmetric)
+    PaddingMode m_PaddingMode;
 };
 
 /// A SliceDescriptor for the SliceLayer.
diff --git a/include/armnn/Types.hpp b/include/armnn/Types.hpp
index 4f39ebe16a..deaa0b3a50 100644
--- a/include/armnn/Types.hpp
+++ b/include/armnn/Types.hpp
@@ -166,6 +166,17 @@ enum class PaddingMethod
     Exclude     = 1
 };
 
+///
+/// The padding mode controls whether the padding should be filled with constant values (Constant), or
+/// reflect the input, either including the border values (Symmetric) or not (Reflect).
+///
+enum class PaddingMode
+{
+    Constant  = 0,
+    Reflect   = 1,
+    Symmetric = 2
+};
+
 enum class NormalizationAlgorithmChannel
 {
     Across = 0,
diff --git a/include/armnn/TypesUtils.hpp b/include/armnn/TypesUtils.hpp
index a1c11b74df..ccb0280457 100644
--- a/include/armnn/TypesUtils.hpp
+++ b/include/armnn/TypesUtils.hpp
@@ -125,6 +125,17 @@ constexpr char const* GetPaddingMethodAsCString(PaddingMethod method)
     }
 }
 
+constexpr char const* GetPaddingModeAsCString(PaddingMode mode)
+{
+    switch (mode)
+    {
+        case PaddingMode::Constant:   return "Exclude";
+        case PaddingMode::Symmetric:  return "Symmetric";
+        case PaddingMode::Reflect:    return "Reflect";
+        default:                      return "Unknown";
+    }
+}
+
 constexpr char const* GetReduceOperationAsCString(ReduceOperation reduce_operation)
 {
     switch (reduce_operation)