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 c34b776679ca4114159b8250e506d5cbf3f1f9b3..ba80fd81e87dcea4555e99a6f4532b7a40c9b2ab 100644
--- a/src/IceAssemblerX86Base.h
+++ b/src/IceAssemblerX86Base.h
@@ -845,6 +845,8 @@ 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);