Fix build warnings

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 286 matching lines @@
 //
 // Once the ordering is determined, the Cfg edge is split and the
 // assignment list is lowered by the target lowering layer.  The
 // specific placement of the new node within the Cfg node list is
 // deferred until later, including after empty node contraction.
 void CfgNode::advancedPhiLowering() {
   if (getPhis().empty())
     return;
 
   // Count the number of non-deleted Phi instructions.
-  struct {
+  struct PhiDesc {
     InstPhi *Phi;
     Variable *Dest;
     Operand *Src;
     bool Processed;
     size_t NumPred; // number of entries whose Src is this Dest
     int32_t Weight; // preference for topological order
-  } Desc[getPhis().size()];
+  };
+  llvm::SmallVector<PhiDesc, 32> Desc(getPhis().size());
 
   size_t NumPhis = 0;
   for (Inst &I : Phis) {
     auto Inst = llvm::dyn_cast<InstPhi>(&I);
     if (!Inst->isDeleted()) {
       Desc[NumPhis].Phi = Inst;
       Desc[NumPhis].Dest = Inst->getDest();
       ++NumPhis;
     }
   }
@@ skipping 657 matching lines @@
       if (!First)
         Str << ", ";
       First = false;
       Str << "%" << I->getName();
     }
     Str << "\n";
   }
 }
 
 } // end of namespace Ice