[optimizing compiler] Add support for volatile

- for backends: arm, x86, x86_64
- added necessary instructions to assemblies
- clean up code gen for field set/get
- fixed InstructionDataEquals for some instructions
- fixed comments in compiler_enums

* 003-opcode test verifies basic volatile functionality

Change-Id: I144393efa312dfb2c332cb84056b00edffee338a
diff --git a/compiler/utils/x86/assembler_x86.h b/compiler/utils/x86/assembler_x86.h
index 9fecf1e..6c3d131 100644
--- a/compiler/utils/x86/assembler_x86.h
+++ b/compiler/utils/x86/assembler_x86.h
@@ -274,6 +274,9 @@
   void movsd(const Address& dst, XmmRegister src);
   void movsd(XmmRegister dst, XmmRegister src);
 
+  void psrlq(XmmRegister reg, const Immediate& shift_count);
+  void punpckldq(XmmRegister dst, XmmRegister src);
+
   void addsd(XmmRegister dst, XmmRegister src);
   void addsd(XmmRegister dst, const Address& src);
   void subsd(XmmRegister dst, XmmRegister src);