Optimize suspend checks in optimizing compiler.

- Remove the ones added during graph build (they were added
  for the baseline code generator).
- Emit them at loop back edges after phi moves, so that the test
  can directly jump to the loop header.
- Fix x86 and x86_64 suspend check by using cmpw instead of cmpl.

Change-Id: I6fad5795a55705d86c9e1cb85bf5d63dadfafa2a
diff --git a/compiler/optimizing/instruction_simplifier.h b/compiler/optimizing/instruction_simplifier.h
new file mode 100644
index 0000000..b2f3f52
--- /dev/null
+++ b/compiler/optimizing/instruction_simplifier.h
@@ -0,0 +1,39 @@
+/*
+ * 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_INSTRUCTION_SIMPLIFIER_H_
+#define ART_COMPILER_OPTIMIZING_INSTRUCTION_SIMPLIFIER_H_
+
+#include "nodes.h"
+
+namespace art {
+
+/**
+ * Implements optimizations specific to each instruction.
+ */
+class InstructionSimplifier : public HGraphVisitor {
+ public:
+  explicit InstructionSimplifier(HGraph* graph) : HGraphVisitor(graph) {}
+
+  void Run();
+
+ private:
+  virtual void VisitSuspendCheck(HSuspendCheck* check) OVERRIDE;
+};
+
+}  // namespace art
+
+#endif  // ART_COMPILER_OPTIMIZING_INSTRUCTION_SIMPLIFIER_H_