From 35373eb2801612767926c212944afe1f31fe7010 Mon Sep 17 00:00:00 2001
From: =?utf8?q?=EC=9C=A4=ED=98=84=EC=8B=9D/=EB=8F=99=EC=9E=91=EC=A0=9C?=
 =?utf8?q?=EC=96=B4Lab=28SR=29/Principal=20Engineer/=EC=82=BC=EC=84=B1?=
 =?utf8?q?=EC=A0=84=EC=9E=90?= <hyunsik.yoon@samsung.com>
Date: Wed, 21 Nov 2018 13:44:45 +0900
Subject: [PATCH] [enco/tfl/frontend] Refactoring RELU activation (#2313)

* [enco/tfl/frontend] Refactoring RELU activation

RELU activation is commonly used by many operations. So this activation is extracted as a separate method.

Signed-off-by: Hyun Sik Yoon <hyunsik.yoon@samsung.com>

* returning ifm

* ofm as param

* remove empty line

* pr fix: remove output param

* pr fix : comment, renaming vars, etc.
---
 contrib/enco/frontend/tflite/src/Frontend.cpp | 95 ++++++++++++++++-----------
 1 file changed, 58 insertions(+), 37 deletions(-)

diff --git a/contrib/enco/frontend/tflite/src/Frontend.cpp b/contrib/enco/frontend/tflite/src/Frontend.cpp
index 00574cc..0da9dad 100644
--- a/contrib/enco/frontend/tflite/src/Frontend.cpp
+++ b/contrib/enco/frontend/tflite/src/Frontend.cpp
@@ -353,6 +353,60 @@ coco::Padding2D conv2D_padding(const tflite::Conv2DOptions *options, const tenso
                      options->dilation_w_factor(), options->dilation_h_factor());
 }
 
+/**
+ * @brief Add coco::Eval for fused activation.
+ *        This method creates an ofm object, appends Eval(ofm object, RELU(...)) into block,
+ *        and returns ofm object.
+ */
+coco::FeatureObject *build_activation(tflite::ActivationFunctionType act, coco::Block *block,
+                                      coco::FeatureObject *ifm)
+{
+  assert(ifm != nullptr && ifm->asFeature() != nullptr); // support feature only in this version
+
+  coco::Module *m = block->module();
+
+  auto shape = ifm->asFeature()->shape();
+
+  // creates output object
+  auto output_obj = m->entity()->object()->create<coco::FeatureObject>();
+  auto output_bag = m->entity()->bag()->create(num_elements(shape));
+  output_obj->bag(output_bag);
+  output_obj->layout(coco::FeatureLayouts::BHWC::create(shape));
+
+  switch (act)
+  {
+  case tflite::ActivationFunctionType::ActivationFunctionType_NONE:
+  {
+    // Create Copy Instr (copying from ifm to output_obj),
+    // redundant layer but optimized by backend
+    auto copy_ins = instr_builder(m).copy(output_obj, ifm);
+
+    // Append the instruction to the block
+    block->instr()->append(copy_ins);
+    break;
+  }
+  case tflite::ActivationFunctionType::ActivationFunctionType_RELU:
+  {
+    // Create Eval(output_obj, Relu(load(ifm)))
+    auto load_op = op_builder(m).load(ifm).pop();
+    auto relu_op = m->entity()->op()->create<coco::ReLU>();
+    relu_op->arg(load_op);
+
+    auto eval_ins = instr_builder(m).eval(output_obj, relu_op);
+
+    // Append the instruction to the block
+    block->instr()->append(eval_ins);
+    break;
+  }
+  default:
+    // TODO support RELU6, TanH, etc
+    assert(false);
+    break;
+  }
+
+  return output_obj;
+}
+
 } // namespace
 
 /**
@@ -554,45 +608,12 @@ void Conv2DGraphBuilder::build(const tflite::Operator *op, GraphBuilderContext *
     last_obj = btmp_obj;
   }
 
-  // fused activation for RELU
-  switch (conv_params->fused_activation_function())
-  {
-  case tflite::ActivationFunctionType::ActivationFunctionType_NONE:
-    break;
-  case tflite::ActivationFunctionType::ActivationFunctionType_RELU:
-  {
-    // When there is a relu, use btmp_obj as relu output
-    auto *btmp_obj = m->entity()->object()->create<coco::FeatureObject>();
-    auto *btmp_bag = m->entity()->bag()->create(num_elements(ofm_shape));
-    btmp_obj->bag(btmp_bag);
-    btmp_obj->layout(coco::FeatureLayouts::BHWC::create(as_feature_shape(ofm_shape)));
-
-    // Create a Load op
-    auto coco_load = op_builder(m).load(last_obj).pop();
-
-    // Create a ReLU
-    auto coco_relu = m->entity()->op()->create<coco::ReLU>();
-
-    // Link ops
-    coco_relu->arg(coco_load);
-
-    // Create an Eval instruction
-    auto coco_eval = instr_builder(m).eval(btmp_obj, coco_relu);
-
-    // Append the instruction to the block
-    blk->instr()->append(coco_eval);
-
-    // Update last_obj to btmp_obj
-    last_obj = btmp_obj;
-    break;
-  }
-  default:
-    assert(false);
-    break;
-  }
+  // fused activation
+  coco::FeatureObject *act_output =
+      build_activation(conv_params->fused_activation_function(), blk, last_obj);
 
   // Create Copy Instr of last_obj to Output Object
-  auto copy_ins = instr_builder(m).copy(ofm_obj, last_obj);
+  auto copy_ins = instr_builder(m).copy(ofm_obj, act_output);
   blk->instr()->append(copy_ins);
 }
 
-- 
2.7.4