Put in place the ARM64 instruction simplification framework.

This commit introduces and runs the empty InstructionSimplifierArm64
pass. Further commits will introduce arm64-specific transformations in
that pass.

Change-Id: I458f8a2b15470297b87fc1f7ff85bd52155d93ef
diff --git a/compiler/optimizing/instruction_simplifier_arm64.h b/compiler/optimizing/instruction_simplifier_arm64.h
new file mode 100644
index 0000000..d7f4eae
--- /dev/null
+++ b/compiler/optimizing/instruction_simplifier_arm64.h
@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2015 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_INSTRUCTION_SIMPLIFIER_ARM64_H_
+#define ART_COMPILER_OPTIMIZING_INSTRUCTION_SIMPLIFIER_ARM64_H_
+
+#include "nodes.h"
+#include "optimization.h"
+
+namespace art {
+namespace arm64 {
+
+class InstructionSimplifierArm64Visitor : public HGraphVisitor {
+ public:
+  InstructionSimplifierArm64Visitor(HGraph* graph, OptimizingCompilerStats* stats)
+      : HGraphVisitor(graph), stats_(stats) {}
+
+ private:
+  void RecordSimplification() {
+    if (stats_ != nullptr) {
+      stats_->RecordStat(kInstructionSimplificationsArch);
+    }
+  }
+
+  OptimizingCompilerStats* stats_;
+};
+
+
+class InstructionSimplifierArm64 : public HOptimization {
+ public:
+  InstructionSimplifierArm64(HGraph* graph, OptimizingCompilerStats* stats)
+    : HOptimization(graph, "instruction_simplifier_arm64", stats) {}
+
+  void Run() OVERRIDE {
+    InstructionSimplifierArm64Visitor visitor(graph_, stats_);
+    visitor.VisitReversePostOrder();
+  }
+};
+
+}  // namespace arm64
+}  // namespace art
+
+#endif  // ART_COMPILER_OPTIMIZING_INSTRUCTION_SIMPLIFIER_ARM64_H_