Inline memove for small constant sizes and refactor memcpy and memset.

src/IceAssemblerX86Base.h

Index: src/IceAssemblerX86Base.h
diff --git a/src/IceAssemblerX86Base.h b/src/IceAssemblerX86Base.h
index 9d872d20eaf599b37744a1ab5adcfbba3c69d802..f6c05c02165e7abe438a6b48a11d25c19dbbb677 100644
--- a/src/IceAssemblerX86Base.h
+++ b/src/IceAssemblerX86Base.h
@@ -830,6 +830,8 @@ public:
   void cmpxchg8b(const typename Traits::Address &address, bool Locked);
   void xadd(Type Ty, const typename Traits::Address &address,
             typename Traits::GPRRegister reg, bool Locked);
+  void xchg(Type Ty, typename Traits::GPRRegister reg0,
+            typename Traits::GPRRegister reg1);
   void xchg(Type Ty, const typename Traits::Address &address,
             typename Traits::GPRRegister reg);