Subzero: Don't store std::string objects inside 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.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file implements the Inst class, primarily the various
@@ skipping 343 matching lines @@
     }
   }
   llvm_unreachable("Phi operand not found for specified target node");
 }
 
 // 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);
-  IceString PhiName = Dest->getName() + "_phi";
-  Variable *NewSrc = Func->makeVariable(Dest->getType(), PhiName);
+  Variable *NewSrc = Func->makeVariable(Dest->getType());
+  if (ALLOW_DUMP)
+    NewSrc->setName(Func, Dest->getName(Func) + "_phi");
   this->Dest = NewSrc;
   return InstAssign::create(Func, Dest, NewSrc);
 }
 
 InstRet::InstRet(Cfg *Func, Operand *RetValue)
     : InstHighLevel(Func, Ret, RetValue ? 1 : 0, NULL) {
   if (RetValue)
     addSource(RetValue);
 }
 
@@ skipping 434 matching lines @@
 
 void InstTarget::dump(const Cfg *Func) const {
   if (!ALLOW_DUMP)
     return;
   Ostream &Str = Func->getContext()->getStrDump();
   Str << "[TARGET] ";
   Inst::dump(Func);
 }
 
 } // end of namespace Ice