Add initial integrated assembler w/ some Xmm ops.

src/IceInst.cpp

Index: src/IceInst.cpp
diff --git a/src/IceInst.cpp b/src/IceInst.cpp
index d6e0f59b15d30d1ad4236f00cfe020765310819d..f46ce4576f4605560fec99c04ffb861640fea6b5 100644
--- a/src/IceInst.cpp
+++ b/src/IceInst.cpp
@@ -474,6 +474,8 @@ void Inst::emit(const Cfg * /*Func*/) const {
   llvm_unreachable("emit() called on a non-lowered instruction");
 }
 
+void Inst::emitIAS(const Cfg *Func) const { emit(Func); }
+
 void Inst::dump(const Cfg *Func) const {
   Ostream &Str = Func->getContext()->getStrDump();
   dumpDest(Func);