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/code_generator_arm.h b/compiler/optimizing/code_generator_arm.h
index 0902fb8..949d9ae 100644
--- a/compiler/optimizing/code_generator_arm.h
+++ b/compiler/optimizing/code_generator_arm.h
@@ -117,6 +117,11 @@
   void LoadCurrentMethod(Register reg);
 
  private:
+  // Generate code for the given suspend check. If not null, `successor`
+  // is the block to branch to if the suspend check is not needed, and after
+  // the suspend call.
+  void GenerateSuspendCheck(HSuspendCheck* check, HBasicBlock* successor);
+
   ArmAssembler* const assembler_;
   CodeGeneratorARM* const codegen_;