Subzero: Don't store std::string objects inside Variable.

src/IceRegAlloc.cpp

 //===- subzero/src/IceRegAlloc.cpp - Linear-scan 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 LinearScan class, which performs the
@@ skipping 418 matching lines @@
                     IsSingleDef && IsAssign && !overlapsDefs(Func, Cur, SrcVar);
               }
               if (AllowOverlap || Free[SrcReg]) {
                 Prefer = SrcVar;
                 PreferReg = SrcReg;
               }
             }
           }
         }
         if (Verbose && Prefer) {
-          Str << "Initial Prefer=" << *Prefer << " R=" << PreferReg
-              << " LIVE=" << Prefer->getLiveRange()
+          Str << "Initial Prefer=";
+          Prefer->dump(Func);
+          Str << " R=" << PreferReg << " LIVE=" << Prefer->getLiveRange()
               << " Overlap=" << AllowOverlap << "\n";
         }
       }
     }
 
     // Remove registers from the Free[] list where an Inactive range
     // overlaps with the current range.
     for (const Variable *Item : Inactive) {
       if (Item->rangeOverlaps(Cur)) {
         int32_t RegNum = Item->getRegNumTmp();
@@ skipping 267 matching lines @@
     Str << "\n";
   }
   Str << "++++++ Inactive:\n";
   for (const Variable *Item : Inactive) {
     dumpLiveRange(Item, Func);
     Str << "\n";
   }
 }
 
 } // end of namespace Ice