MLCE-418 Reduce layer does not support multiple axes

 * Added backend specific optimization to chain new reduces layers
   for each axis to simulate behaviour of a layer with multiple axes.
 * Added function to calculate reduced output shape.
 * Added unit tests.
 * Includes rework to fix IVGCVSW-5987.

Signed-off-by: Matthew Sloyan <matthew.sloyan@arm.com>
Change-Id: I154b3698b5e6756b05b2a0b5a3f0896184efce72
diff --git a/src/backends/neon/workloads/NeonReduceWorkload.cpp b/src/backends/neon/workloads/NeonReduceWorkload.cpp
index 0e1b46a..1436cd1 100644
--- a/src/backends/neon/workloads/NeonReduceWorkload.cpp
+++ b/src/backends/neon/workloads/NeonReduceWorkload.cpp
@@ -20,23 +20,28 @@
                                                const TensorInfo& output,
                                                const ReduceDescriptor& desc)
 {
-    const arm_compute::TensorInfo aclInputInfo  = armcomputetensorutils::BuildArmComputeTensorInfo(input);
-    const arm_compute::TensorInfo aclOutputInfo = armcomputetensorutils::BuildArmComputeTensorInfo(output);
-    if (!desc.m_vAxis.empty() && desc.m_vAxis.size() > 1)
+    if ( desc.m_vAxis.size()==1 || desc.m_vAxis.empty())
     {
-        return arm_compute::Status(arm_compute::ErrorCode::RUNTIME_ERROR,
-                                   "NeonReduceWorkload: Reduction is supported only on 1 axis.");
+        const arm_compute::TensorInfo aclInputInfo  = armcomputetensorutils::BuildArmComputeTensorInfo(input);
+        const arm_compute::TensorInfo aclOutputInfo = armcomputetensorutils::BuildArmComputeTensorInfo(output);
+
+        arm_compute::Coordinates coords = BuildArmComputeReductionCoordinates(aclInputInfo.num_dimensions(),
+                                                                              input.GetNumDimensions(),
+                                                                              desc.m_vAxis);
+
+        return arm_compute::NEReductionOperation::validate(&aclInputInfo,
+                                                           &aclOutputInfo,
+                                                           static_cast<unsigned int>(coords[0]),
+                                                           ConvertReductionOperationToAcl(desc),
+                                                           desc.m_KeepDims);
     }
-
-    arm_compute::Coordinates coords = BuildArmComputeReductionCoordinates(aclInputInfo.num_dimensions(),
-                                                                          input.GetNumDimensions(),
-                                                                          desc.m_vAxis);
-
-    return arm_compute::NEReductionOperation::validate(&aclInputInfo,
-                                                       &aclOutputInfo,
-                                                       static_cast<unsigned int>(coords[0]),
-                                                       ConvertReductionOperationToAcl(desc),
-                                                       desc.m_KeepDims);
+    else
+    {
+        // Validate layer if there are multiple axes.
+        arm_compute::Status status;
+        IS_MULTI_AXES_REDUCE_SUPPORTED(NeonReduceWorkloadValidate, input, desc, status);
+        return status;
+    }
 }
 
 NeonReduceWorkload::NeonReduceWorkload(const ReduceQueueDescriptor& descriptor, const WorkloadInfo& info)
@@ -50,6 +55,7 @@
     arm_compute::Coordinates coords = BuildArmComputeReductionCoordinates(input.info()->num_dimensions(),
                                                                           info.m_InputTensorInfos[0].GetNumDimensions(),
                                                                           m_Data.m_Parameters.m_vAxis);
+
     m_Layer.configure(&input,
                       &output,
                       static_cast<unsigned int>(coords[0]),