From 490b7becb8029ead26423b0d62e631a929e55d6c Mon Sep 17 00:00:00 2001
From: Mike Kelly <mike.kelly@arm.com>
Date: Tue, 3 Mar 2020 12:39:09 +0000
Subject: IVGCVSW-4375 Add support for Transpose to optimizations

 * Changed some existing Permutation specific optimizations to also support Transpose
 * Added MoveTransposeUp optimization
 * Added TransposeAsReshape optimization
 * Added tests for Transpose optimizations
 * Added missing layer tests for Transpose

Signed-off-by: Mike Kelly <mike.kelly@arm.com>
Change-Id: I20d099b284861402ae94aaa5dbf34907327a485f
---
 src/armnn/optimizations/TransposeAsReshape.hpp | 81 ++++++++++++++++++++++++++
 1 file changed, 81 insertions(+)
 create mode 100644 src/armnn/optimizations/TransposeAsReshape.hpp

(limited to 'src/armnn/optimizations/TransposeAsReshape.hpp')

diff --git a/src/armnn/optimizations/TransposeAsReshape.hpp b/src/armnn/optimizations/TransposeAsReshape.hpp
new file mode 100644
index 0000000000..4bb2f192f3
--- /dev/null
+++ b/src/armnn/optimizations/TransposeAsReshape.hpp
@@ -0,0 +1,81 @@
+//
+// Copyright © 2020 Arm Ltd. All rights reserved.
+// SPDX-License-Identifier: MIT
+//
+#pragma once
+
+#include "Optimization.hpp"
+
+namespace armnn
+{
+namespace optimizations
+{
+
+class TransposeAsReshapeImpl
+{
+public:
+    /// Run for every TransposeLayer. Replaces it with a ReshapeLayer if they are equivalent.
+    void Run(Graph& graph, TransposeLayer& transpose) const
+    {
+        if (IsReshape(transpose))
+        {
+            const TensorInfo& outInfo = transpose.GetOutputHandler().GetTensorInfo();
+
+            const std::string name = std::string("as_reshape-") + transpose.GetName();
+            const ReshapeDescriptor descriptor{outInfo.GetShape()};
+            // Inserts NewLayer so layers don't need to be re-sorted.
+            auto reshape = graph.InsertNewLayer<ReshapeLayer>(transpose.GetInputSlot(0), descriptor, name.c_str());
+            reshape->GetOutputHandler().SetTensorInfo(outInfo);
+
+            // Bypass transpose. It will be deleted since it's left unconnected.
+            transpose.GetOutputSlot().MoveAllConnections(reshape->GetOutputSlot());
+        }
+    }
+
+protected:
+    TransposeAsReshapeImpl() = default;
+    ~TransposeAsReshapeImpl() = default;
+
+private:
+    static bool IsReshape(const TransposeLayer& layer)
+    {
+        const TensorShape& outShape = layer.GetOutputHandler().GetTensorInfo().GetShape();
+        const PermutationVector& permutation = layer.GetPermutation();
+
+        const unsigned int numDimensions = permutation.GetSize();
+        std::map<unsigned int, unsigned int> permuteMappings;
+        for (unsigned int i = 0; i < permutation.GetSize(); ++i)
+        {
+            permuteMappings[permutation[i]] = i;
+        }
+
+        std::vector<unsigned int> permuteVector;
+        for (unsigned int i = 0; i < permutation.GetSize(); ++i)
+        {
+            permuteVector.push_back(permuteMappings.at(i));
+        }
+
+        unsigned int lastGtOne = 0;
+        while ((lastGtOne < numDimensions) && (outShape[(permuteVector[lastGtOne])] == 1U))
+        {
+            ++lastGtOne;
+        }
+
+        bool isReshape = true;
+        for (unsigned int i = lastGtOne + 1U; isReshape && (i < numDimensions); ++i)
+        {
+            if (outShape[permuteVector[i]] > 1U)
+            {
+                isReshape = permuteVector[lastGtOne] < permuteVector[i];
+                lastGtOne = i;
+            }
+        }
+
+        return isReshape;
+    }
+};
+
+using TransposeAsReshape = OptimizeForType<TransposeLayer, TransposeAsReshapeImpl>;
+
+} // namespace optimizations
+} // namespace armnn
-- 
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