Fix a C++ violation

src/IceCfgNode.cpp

 //===- subzero/src/IceCfgNode.cpp - Basic block (node) 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 CfgNode class, including the complexities
@@ skipping 217 matching lines @@
 // incoming liveness changed from before, false if it stayed the same.
 // (If it changes, the node's predecessors need to be processed
 // again.)
 bool CfgNode::liveness(Liveness *Liveness) {
   SizeT NumVars = Liveness->getNumVarsInNode(this);
   llvm::BitVector Live(NumVars);
   // Mark the beginning and ending of each variable's live range
   // with the sentinel instruction number 0.
   std::vector<InstNumberT> &LiveBegin = Liveness->getLiveBegin(this);
   std::vector<InstNumberT> &LiveEnd = Liveness->getLiveEnd(this);
-  LiveBegin.assign(NumVars, Inst::NumberSentinel);
-  LiveEnd.assign(NumVars, Inst::NumberSentinel);
+  InstNumberT Sentinel = Inst::NumberSentinel;
+  LiveBegin.assign(NumVars, Sentinel);
+  LiveEnd.assign(NumVars, Sentinel);
   // Initialize Live to be the union of all successors' LiveIn.
   for (NodeList::const_iterator I = OutEdges.begin(), E = OutEdges.end();
        I != E; ++I) {
     CfgNode *Succ = *I;
     Live |= Liveness->getLiveIn(Succ);
     // Mark corresponding argument of phis in successor as live.
     for (PhiList::const_iterator I1 = Succ->Phis.begin(), E1 = Succ->Phis.end();
          I1 != E1; ++I1) {
       (*I1)->livenessPhiOperand(Live, this, Liveness);
     }
@@ skipping 233 matching lines @@
          I != E; ++I) {
       if (I != OutEdges.begin())
         Str << ", ";
       Str << "%" << (*I)->getName();
     }
     Str << "\n";
   }
 }
 
 } // end of namespace Ice