1 files changed, 136 insertions, 0 deletions
diff --git a/compiler/mir/src/Graph.cpp b/compiler/mir/src/Graph.cpp
new file mode 100644
index 000000000..0eccdac2b
--- /dev/null
+++ b/compiler/mir/src/Graph.cpp
@@ -0,0 +1,136 @@
+/*
+ * 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 "mir/Graph.h"
+
+#include <algorithm>
+#include <deque>
+#include <unordered_map>
+
+namespace mir
+{
+
+/**
+ * @brief replace all usages of operation `op` with node `with`
+ * (i.e. all references in previous/next nodes )
+ * @param op the operation to replace
+ * @param with the operation to use as a replacement
+ */
+static void replaceUsages(Operation *op, Operation *with)
+{
+  assert(op->getNumOutputs() == with->getNumOutputs());
+  for (std::size_t i = 0; i < op->getNumOutputs(); ++i)
+  {
+    Operation::Output *output = op->getOutput(i);
+    output->replaceAllUsesWith(with->getOutput(i));
+  }
+}
+
+std::vector<Operation *> getSortedNodes(Graph *graph)
+{
+  std::deque<Operation *> ready_nodes;
+  std::unordered_map<Operation *, std::size_t> num_visited_input_edges;
+
+  for (Operation *op : graph->getNodes())
+  {
+    if (op->getNumInputs() == 0)
+    {
+      ready_nodes.push_back(op);
+    }
+  }
+
+  std::vector<Operation *> sorted_nodes;
+  while (!ready_nodes.empty())
+  {
+    Operation *src_node = ready_nodes.front();
+    ready_nodes.pop_front();
+    sorted_nodes.push_back(src_node);
+    for (Operation::Output &output : src_node->getOutputs())
+    {
+      for (const auto use : output.getUses())
+      {
+        Operation *dst_node = use.getNode();
+        if (++num_visited_input_edges[dst_node] == dst_node->getNumInputs())
+        {
+          ready_nodes.push_back(dst_node);
+        }
+      }
+    }
+  }
+
+  return sorted_nodes;
+}
+
+void Graph::accept(IVisitor *visitor)
+{
+  for (Operation *node : getSortedNodes(this))
+  {
+    node->accept(visitor);
+  }
+}
+
+Graph::~Graph()
+{
+  for (auto &node : _ops)
+  {
+    delete node;
+  }
+}
+
+void Graph::registerOp(Operation *op)
+{
+  _ops.emplace(op);
+
+  if (auto *input_op = dynamic_cast<ops::InputOp *>(op))
+    _inputs.emplace_back(input_op);
+
+  if (auto *output_op = dynamic_cast<ops::OutputOp *>(op))
+    _outputs.emplace_back(output_op);
+}
+
+void Graph::replaceNode(Operation *op, Operation *with)
+{
+  replaceUsages(op, with);
+  removeNode(op);
+}
+
+void Graph::removeNode(Operation *op)
+{
+#ifndef NDEBUG
+  for (const auto &output : op->getOutputs())
+  {
+    assert(output.getUses().empty() && "Trying to remove a node that has uses.");
+  }
+#endif
+
+  for (std::size_t i = 0; i < op->getNumInputs(); ++i)
+  {
+    op->getInput(i)->removeUse(Operation::Use(op, i));
+  }
+
+  if (op->getType() == Operation::Type::input)
+    _inputs.erase(
+        std::remove(_inputs.begin(), _inputs.end(), op)); // NOLINT(bugprone-inaccurate-erase)
+
+  if (op->getType() == Operation::Type::output)
+    _outputs.erase(
+        std::remove(_outputs.begin(), _outputs.end(), op)); // NOLINT(bugprone-inaccurate-erase)
+
+  _ops.erase(op);
+  delete op;
+}
+
+} // namespace mir