Make sure that all globals are internal, except for "start" functions.

src/IceELFSection.cpp

 //===- subzero/src/IceELFSection.cpp - Representation of ELF sections -----===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 98 matching lines @@
   (void)Unique;
 }
 
 void ELFSymbolTableSection::noteUndefinedSym(const IceString &Name,
                                              ELFSection *NullSection) {
   ELFSym NewSymbol = ELFSym();
   NewSymbol.Sym.setBindingAndType(STB_GLOBAL, STT_NOTYPE);
   NewSymbol.Section = NullSection;
   NewSymbol.Number = ELFSym::UnknownNumber;
   bool Unique = GlobalSymbols.insert(std::make_pair(Name, NewSymbol)).second;
-  assert(Unique);
+  if (!Unique) {
+    std::string Buffer;
+    llvm::raw_string_ostream StrBuf(Buffer);
+    StrBuf << "Symbol external and defined: " << Name;
+    llvm::report_fatal_error(StrBuf.str());
+  }
   (void)Unique;
 }
 
 const ELFSym *ELFSymbolTableSection::findSymbol(const IceString &Name) const {
   auto I = LocalSymbols.find(Name);
   if (I != LocalSymbols.end())
     return &I->second;
   I = GlobalSymbols.find(Name);
   if (I != GlobalSymbols.end())
     return &I->second;
@@ skipping 84 matching lines @@
       continue;
     }
     StringIndex.second = StringData.size();
     std::copy(Cur.begin(), Cur.end(), back_inserter(StringData));
     StringData.push_back(0);
     Prev = Cur;
   }
 }
 
 } // end of namespace Ice