[enco] Introduce DuplicatedObjectReduction (#1712)

* [enco] Introduce DuplicatedObjectReduction

This commit introduces Duplicated Object Reduction pass in enco. This
pass will replace Object Hoist pass later.

Signed-off-by: Jonghyun Park <jh1302.park@samsung.com>
* Fix a typo in comment

diff --git a/contrib/enco/core/src/Backend.cpp b/contrib/enco/core/src/Backend.cpp
index 8755b31..f50c758 100644 (file)
--- a/contrib/enco/core/src/Backend.cpp
+++ b/contrib/enco/core/src/Backend.cpp
@@ -27,6 +27,7 @@
 #include "Transforms/Normalize.h"
 #include "Transforms/IndirectCopyElimination.h"
 #include "Transforms/IdenticalObjectReduction.h"
+#include "Transforms/DuplicatedObjectReduction.h"
 #include "Transforms/DeadObjectElimination.h"
 #include "Transforms/Optimizations.h"
 #include "Transforms/Split.h"
@@ -109,6 +110,7 @@ void BackendImpl::compile(coco::Module *m, coco::Data *d)
 
   eliminate_indirect_copy(&code);
   reduce_identical_object(&code);
+  reduce_duplicated_object(&code);
 
   // Eliminate dead object
   //

diff --git a/contrib/enco/core/src/Transforms/DuplicatedObjectReduction.cpp b/contrib/enco/core/src/Transforms/DuplicatedObjectReduction.cpp
new file mode 100644 (file)
index 0000000..fa84c00
--- /dev/null
+++ b/contrib/enco/core/src/Transforms/DuplicatedObjectReduction.cpp
@@ -0,0 +1,119 @@
+/*
+ * Copyright (c) 2018 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 "DuplicatedObjectReduction.h"
+
+#include "CodeIndex.h"
+#include "IRUtils.h"
+
+#include <set>
+
+namespace
+{
+
+/**
+ * @brief Collect feature objects in coco IR
+ */
+std::set<coco::FeatureObject *> features(const coco::Module *m)
+{
+  std::set<coco::FeatureObject *> res;
+
+  for (uint32_t n = 0; n < m->entity()->object()->size(); ++n)
+  {
+    if (auto feature = m->entity()->object()->at(n)->asFeature())
+    {
+      res.insert(feature);
+    }
+  }
+
+  return res;
+}
+
+std::set<coco::FeatureObject *> candidates(const coco::FeatureObject *src)
+{
+  std::set<coco::FeatureObject *> res;
+
+  for (auto consumer : coco::consumers(src))
+  {
+    if (auto copy = consumer->loc()->asCopy())
+    {
+      auto dst = copy->into()->asFeature();
+      assert(dst != nullptr);
+
+      if (dst->layout()->id() == coco::FeatureLayouts::BHWC::uid())
+      {
+        res.insert(dst);
+      }
+    }
+  }
+
+  return res;
+}
+
+CodeIndex code_index(coco::Object::Producer *p)
+{
+  if (auto ins = p->loc())
+  {
+    return ::code_index(ins);
+  }
+
+  return CodeIndex{};
+}
+
+} // namespace
+
+namespace enco
+{
+
+void reduce_duplicated_object(enco::Code *code)
+{
+  auto m = code->module();
+
+  for (const auto &src : features(m))
+  {
+    auto copied = candidates(src);
+
+    if (copied.size() <= 1)
+    {
+      continue;
+    }
+
+    // Find the dominator
+    coco::FeatureObject *dominator = nullptr;
+
+    for (auto candidate : copied)
+    {
+      if (dominator == nullptr)
+      {
+        dominator = candidate;
+      }
+      else if (code_index(coco::producer(candidate)) < code_index(coco::producer(dominator)))
+      {
+        dominator = candidate;
+      }
+    }
+
+    // Replace all the occurunce of dominated objects with its dominator
+    copied.erase(dominator);
+
+    for (auto dominatee : copied)
+    {
+      subst(dominatee, dominator);
+    }
+  }
+}
+
+} // namespace enco

diff --git a/contrib/enco/core/src/Transforms/DuplicatedObjectReduction.h b/contrib/enco/core/src/Transforms/DuplicatedObjectReduction.h
new file mode 100644 (file)
index 0000000..14d288a
--- /dev/null
+++ b/contrib/enco/core/src/Transforms/DuplicatedObjectReduction.h
@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 2018 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 __ENCO_TRANSFORM_DUPLICATED_OBJECT_REDUCTION_H__
+#define __ENCO_TRANSFORM_DUPLICATED_OBJECT_REDUCTION_H__
+
+#include "Code.h"
+
+namespace enco
+{
+
+/**
+ * @brief Reduce duplicated feature objects as its dominating feature object
+ *
+ * >>> BEFORE <<<
+ * %obj_0 = Feature(layout: ???) at ...
+ * %obj_1 = Feature(layout: BHWC) at ...
+ * %obj_2 = Feature(layout: BHWC) at ...
+ *
+ * copy(from: %obj_0, into: %obj_1)
+ * copy(from: %obj_0, into: %obj_2)
+ *
+ * ...
+ * Use(%obj_1)
+ * Use(%obj_2)
+ * ...
+ *
+ * >>> AFTER <<<
+ * %obj_0 = Feature(layout: ???) at ...
+ * %obj_1 = Feature(layout: BHWC) at ...
+ * %obj_2 = Feature(layout: BHWC) at ...
+ *
+ * copy(from: %obj_0, into: %obj_1)
+ * copy(from: %obj_0, into: %obj_2)
+ *
+ * ...
+ * Use(%obj_1)
+ * Use(%obj_1) <-- CHANGED
+ * ...
+ *
+ * NOTE Given a set of feature objects, a feature object referred to as a dominating
+ *      feature object if its producer proceeds the producer of every feature object
+ *      in the given set
+ */
+void reduce_duplicated_object(enco::Code *code);
+
+} // namespace enco
+
+#endif // __ENCO_TRANSFORM_DUPLICATED_OBJECT_REDUCTION_H__