Refactor Lo and Hi out of Variable.

src/IceInst.cpp

 //===- subzero/src/IceInst.cpp - High-level instruction implementation ----===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 367 matching lines @@
 }
 
 // Change "a=phi(...)" to "a_phi=phi(...)" and return a new instruction
 // "a=a_phi".
 Inst *InstPhi::lower(Cfg *Func) {
   Variable *Dest = getDest();
   assert(Dest);
   Variable *NewSrc = Func->makeVariable(Dest->getType());
   if (BuildDefs::dump())
     NewSrc->setName(Func, Dest->getName(Func) + "_phi");
+  if (auto *NewSrc64On32 = llvm::dyn_cast<Variable64On32>(NewSrc))
+    NewSrc64On32->initHiLo(Func);
   this->Dest = NewSrc;
   return InstAssign::create(Func, Dest, NewSrc);
 }
 
 InstRet::InstRet(Cfg *Func, Operand *RetValue)
     : InstHighLevel(Func, Ret, RetValue ? 1 : 0, nullptr) {
   if (RetValue)
     addSource(RetValue);
 }
 
@@ skipping 553 matching lines @@
     // upper 32 bits of rax. We need to recognize and preserve these.
     return true;
   }
   if (!Dest->hasReg() && !SrcVar->hasReg() &&
       Dest->getStackOffset() == SrcVar->getStackOffset())
     return true;
   return false;
 }
 
 } // end of namespace Ice