Introduce a class to implement optimization passes.

- Add art::HOptimization.
- Rename art::ConstantPropagation to art::HConstantFolding in
  compiler/optimizing/constant_folding.h to avoid name
  clashes with a class of the same name in
  compiler/dex/post_opt_passes.h.
- Rename art::DeadCodeElimination to
  art::HDeadCodeElimination for consistency reasons.
- Have art::HDeadCodeElimination and art::HConstantFolding
  derive from art::HOptimization.
- Start to use these optimizations in
  art:OptimizingCompiler::TryCompile.

Change-Id: Iaab350c122d87b2333b3760312b15c0592d7e010
diff --git a/compiler/optimizing/optimization.h b/compiler/optimizing/optimization.h
new file mode 100644
index 0000000..1ad0d30
--- /dev/null
+++ b/compiler/optimizing/optimization.h
@@ -0,0 +1,79 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * 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 ART_COMPILER_OPTIMIZING_OPTIMIZATION_H_
+#define ART_COMPILER_OPTIMIZING_OPTIMIZATION_H_
+
+#include "graph_visualizer.h"
+#include "nodes.h"
+
+namespace art {
+
+/**
+ * Abstraction to implement an optimization pass.
+ */
+class HOptimization : public ValueObject {
+ public:
+  HOptimization(HGraph* graph,
+                bool is_in_ssa_form,
+                const char* pass_name,
+                const HGraphVisualizer& visualizer)
+      : graph_(graph),
+        is_in_ssa_form_(is_in_ssa_form),
+        pass_name_(pass_name),
+        visualizer_(visualizer) {}
+
+  virtual ~HOptimization() {}
+
+  // Execute the optimization pass.
+  void Execute();
+
+  // Return the name of the pass.
+  const char* GetPassName() const { return pass_name_; }
+
+  // Peform the analysis itself.
+  virtual void Run() = 0;
+
+ private:
+  // Verify the graph; abort if it is not valid.
+  void Check();
+
+  template <typename T>
+  void CheckInternal(T* checker) {
+    checker->VisitInsertionOrder();
+    if (!checker->IsValid()) {
+      LOG(FATAL) << Dumpable<T>(*checker);
+    }
+  }
+
+ protected:
+  HGraph* const graph_;
+
+ private:
+  // Does the analyzed graph use SSA form?
+  bool is_in_ssa_form_;
+  // Optimization pass name.
+  const char* pass_name_;
+  // A graph visualiser invoked during the execution of the
+  // optimization pass if non null.
+  const HGraphVisualizer& visualizer_;
+
+  DISALLOW_COPY_AND_ASSIGN(HOptimization);
+};
+
+}  // namespace art
+
+#endif  // ART_COMPILER_OPTIMIZING_OPTIMIZATION_H_