From 0ce7c33bc865948aae471e4d4f953018dc773b3b Mon Sep 17 00:00:00 2001
From: Dmitry Kurtaev <dmitry.kurtaev+github@gmail.com>
Date: Wed, 16 Aug 2017 21:11:59 +0300
Subject: [PATCH] Torch's Concat and ConcatTable doesn't use Split layer

---
 modules/dnn/src/layers/split_layer.cpp   |  5 ++---
 modules/dnn/src/torch/torch_importer.cpp | 23 +++++++----------------
 2 files changed, 9 insertions(+), 19 deletions(-)

diff --git a/modules/dnn/src/layers/split_layer.cpp b/modules/dnn/src/layers/split_layer.cpp
index bae6c87..435d4bd 100644
--- a/modules/dnn/src/layers/split_layer.cpp
+++ b/modules/dnn/src/layers/split_layer.cpp
@@ -75,7 +75,7 @@ public:
 
         Layer::getMemoryShapes(inputs, max(1, outputsCount >= 0 ? outputsCount : requiredOutputs),
                                outputs, internals);
-        return true;
+        return false;
     }
 
     void forward(std::vector<Mat*> &inputs, std::vector<Mat> &outputs, std::vector<Mat> &internals)
@@ -86,8 +86,7 @@ public:
         for (size_t i = 0; i < outputs.size(); i++)
         {
             CV_Assert(inputs[0]->total() == outputs[i].total());
-            if (outputs[i].data != inputs[0]->data)
-                inputs[0]->copyTo(outputs[i]);
+            inputs[0]->copyTo(outputs[i]);
         }
     }
 };
diff --git a/modules/dnn/src/torch/torch_importer.cpp b/modules/dnn/src/torch/torch_importer.cpp
index 44fcd8c..ecaf054 100644
--- a/modules/dnn/src/torch/torch_importer.cpp
+++ b/modules/dnn/src/torch/torch_importer.cpp
@@ -827,20 +827,18 @@ struct TorchImporter : public ::cv::dnn::Importer
             }
             else if (module->thName == "Concat")
             {
-                int newId, splitId, mergeId;
-                LayerParams mergeParams, splitParams;
+                int newId, mergeId;
+                LayerParams mergeParams;
                 mergeParams.set("axis", module->params.get<int>("dimension") - 1);
 
-                splitId = net.addLayer(generateLayerName("torchSplit"), "Split", splitParams);
-                net.connect(prevLayerId, prevOutNum, splitId, 0);
-
                 std::vector<int> branchIds;
                 for (int i = 0; i < (int)module->modules.size(); i++)
                 {
-                    newId = fill(module->modules[i], addedModules, splitId, i);
+                    newId = fill(module->modules[i], addedModules, prevLayerId, prevOutNum);
                     branchIds.push_back(newId);
                 }
 
+                moduleCounter += 1;  // Skip split layer creation. See https://github.com/opencv/opencv/pull/9384.
                 mergeId = net.addLayer(generateLayerName("torchMerge"), "Concat", mergeParams);
 
                 for (int i = 0; i < branchIds.size(); i++)
@@ -884,19 +882,12 @@ struct TorchImporter : public ::cv::dnn::Importer
                 return mergeId;
             }
             else if (module->thName == "ConcatTable") {
-                int newId = -1, splitId;
-                LayerParams splitParams;
-
-                splitId = net.addLayer(generateLayerName("torchSplit"), "Split", splitParams);
-                net.connect(prevLayerId, prevOutNum, splitId, 0);
-
-                addedModules.push_back(std::make_pair(splitId, module));
-
+                int newId = -1;
+                moduleCounter += 1;  // Skip split layer creation. See https://github.com/opencv/opencv/pull/9384.
                 for (int i = 0; i < (int)module->modules.size(); i++)
                 {
-                    newId = fill(module->modules[i], addedModules, splitId, i);
+                    newId = fill(module->modules[i], addedModules, prevLayerId, prevOutNum);
                 }
-
                 return newId;
             }
             else if (module->thName == "JoinTable") {
-- 
2.7.4