From 5e3c65305435ff942fad78f0e7c21df6018137ed Mon Sep 17 00:00:00 2001
From: =?utf8?q?=EB=B0=95=EC=B2=9C=EA=B5=90/On-Device=20Lab=28SR=29/Enginee?=
 =?utf8?q?r/=EC=82=BC=EC=84=B1=EC=A0=84=EC=9E=90?= <ch.bahk@samsung.com>
Date: Fri, 1 Nov 2019 14:36:01 +0900
Subject: [PATCH] [exo] Fuse Squared Difference (#8654)

This commit introduces a pass to fuse Squared Difference pattern

Signed-off-by: Cheongyo Bahk <ch.bahk@samsung.com>
---
 .../exo/src/Pass/FuseSquaredDifferencePass.cpp     | 88 ++++++++++++++++++++++
 compiler/exo/src/Pass/FuseSquaredDifferencePass.h  | 49 ++++++++++++
 2 files changed, 137 insertions(+)
 create mode 100644 compiler/exo/src/Pass/FuseSquaredDifferencePass.cpp
 create mode 100644 compiler/exo/src/Pass/FuseSquaredDifferencePass.h

diff --git a/compiler/exo/src/Pass/FuseSquaredDifferencePass.cpp b/compiler/exo/src/Pass/FuseSquaredDifferencePass.cpp
new file mode 100644
index 0000000..497c3ee
--- /dev/null
+++ b/compiler/exo/src/Pass/FuseSquaredDifferencePass.cpp
@@ -0,0 +1,88 @@
+/*
+ * Copyright (c) 2019 Samsung Electronics Co., Ltd. All Rights Reserved
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "FuseSquaredDifferencePass.h"
+
+#include "Check.h"
+
+#include "Dialect/IR/TFLNodes.h"
+
+#include <loco/IR/Nodes.h>
+
+namespace
+{
+
+/**
+ * @return  Casted TFLMul for fusable candidate, nullptr otherwise
+ *
+ * This helper checkes fusability with following conditions:
+ * - TFLMul has no activation
+ * - TFLMul's first and second arguments are equal and TFLSub
+ */
+locoex::TFLMul *as_candidate(loco::Node *node)
+{
+  auto mul = dynamic_cast<locoex::TFLMul *>(node);
+  if (not mul)
+    return nullptr;
+
+  // Cannot fuse mul with activation function
+  if (mul->fusedActivationFunction() != locoex::FusedActFunc::NONE)
+    return nullptr;
+
+  if (mul->x() != mul->y())
+    return nullptr;
+
+  if (not dynamic_cast<locoex::TFLSub *>(mul->x()))
+    return nullptr;
+
+  return mul;
+}
+
+void fuse_squared_difference(locoex::TFLMul *mul)
+{
+  auto sub = dynamic_cast<locoex::TFLSub *>(mul->x());
+  EXO_ASSERT(sub, "sub should be valid at this point");
+
+  // TFLSquaredDifference to replace
+  auto sq_diff = mul->graph()->nodes()->create<locoex::TFLSquaredDifference>();
+  sq_diff->x(sub->x());
+  sq_diff->y(sub->y());
+
+  // replace
+  loco::replace(mul).with(sq_diff);
+}
+
+} // namespace
+
+namespace exo
+{
+
+bool FuseSquaredDifferencePass::run(loco::Graph *g)
+{
+  bool changed = false;
+  for (auto node : loco::active_nodes(loco::output_nodes(g)))
+  {
+    if (auto mul = as_candidate(node))
+    {
+      fuse_squared_difference(mul);
+      changed = true;
+    }
+  }
+
+  return changed;
+}
+
+} // namespace exo
diff --git a/compiler/exo/src/Pass/FuseSquaredDifferencePass.h b/compiler/exo/src/Pass/FuseSquaredDifferencePass.h
new file mode 100644
index 0000000..dbc1514
--- /dev/null
+++ b/compiler/exo/src/Pass/FuseSquaredDifferencePass.h
@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2019 Samsung Electronics Co., Ltd. All Rights Reserved
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef __FUSE_SQUARED_DIFFERENCE_PASS_H__
+#define __FUSE_SQUARED_DIFFERENCE_PASS_H__
+
+#include <logo/Pass.h>
+
+namespace exo
+{
+
+/**
+ * @brief  Class to fuse SquaredDifference pattern
+ *
+ * <BEFORE>
+ *
+ *    A --- TFLSub --- TFLMul --- C
+ *          /    \     /
+ *    B ----      -----
+ *
+ * <AFTER>
+ *
+ *    A --- TFLSquaredDifference --- C
+ *          /
+ *    B ----
+ */
+struct FuseSquaredDifferencePass final : public logo::Pass
+{
+  const char *name(void) const final { return "exo::FuseSquaredDifferencePass"; }
+
+  bool run(loco::Graph *g) final;
+};
+
+} // namespace exo
+
+#endif // __FUSE_SQUARED_DIFFERENCE_PASS_H__
-- 
2.7.4