NNXSW-1826 Add an optimization step which combines Permute and BatchToSpace into DepthToSpace

This is only possible in some limited cases, but removes an extra
layer from the graph and so should improve performance in all cases.

Change-Id: I7b3e6ba5dacb4fdb816ad270edaecda1436ab4cf
Signed-off-by: Rob Hughes <robert.hughes@arm.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/src/armnn/optimizations/PermuteAndBatchToSpaceAsDepthToSpace.hpp b/src/armnn/optimizations/PermuteAndBatchToSpaceAsDepthToSpace.hpp
new file mode 100644
index 0000000000..4a73efca40
--- /dev/null
+++ b/src/armnn/optimizations/PermuteAndBatchToSpaceAsDepthToSpace.hpp
@@ -0,0 +1,27 @@
+//
+// Copyright © 2019 Arm Ltd. All rights reserved.
+// SPDX-License-Identifier: MIT
+//
+#pragma once
+
+#include "Optimization.hpp"
+
+namespace armnn
+{
+namespace optimizations
+{
+
+/// Replaces Permute leading into BatchToSpace with a DepthToSpace
+/// in the case where the Permute swaps the batch and channels dimensions
+/// such that the replacement is valid.
+class PermuteAndBatchToSpaceAsDepthToSpaceImpl
+{
+public:
+    void Run(Graph& graph, InputSlot& connection) const;
+};
+
+using PermuteAndBatchToSpaceAsDepthToSpace =
+    OptimizeForConnection<PermuteLayer, BatchToSpaceNdLayer, PermuteAndBatchToSpaceAsDepthToSpaceImpl>;
+
+}    // namespace optimizations
+}    // namespace armnn