Subzero: Track protos + globals w/out initializers as undef too (not just helper funcs)

src/PNaClTranslator.cpp

 //===- subzero/src/PNaClTranslator.cpp - ICE from bitcode -----------------===//
 //
 //                        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 PNaCl bitcode file to Ice, to machine code
@@ skipping 266 matching lines @@
 
     if (isIRGenerationDisabled()) {
       ValueIDConstants[ID] = nullptr;
       return nullptr;
     }
 
     // If reached, no such constant exists, create one.
     // TODO(kschimpf) Don't get addresses of intrinsic function declarations.
     Ice::GlobalDeclaration *Decl = nullptr;
     unsigned FcnIDSize = FunctionDeclarationList.size();
+    bool IsUndefined = false;
     if (ID < FcnIDSize) {
       Decl = FunctionDeclarationList[ID];
+      const auto Func = llvm::cast<Ice::FunctionDeclaration>(Decl);
+      IsUndefined = Func->isProto();
     } else if ((ID - FcnIDSize) < VariableDeclarations.size()) {
       Decl = VariableDeclarations[ID - FcnIDSize];
+      const auto Var = llvm::cast<Ice::VariableDeclaration>(Decl);
+      IsUndefined = !Var->hasInitializer();
     }
     std::string Name;
     bool SuppressMangling;
     if (Decl) {
       Name = Decl->getName();
       SuppressMangling = Decl->getSuppressMangling();
     } else {
       std::string Buffer;
       raw_string_ostream StrBuf(Buffer);
       StrBuf << "Reference to global not defined: " << ID;
       BlockError(StrBuf.str());
       // TODO(kschimpf) Remove error recovery once implementation complete.
       Name = "??";
       SuppressMangling = false;
     }
-    const Ice::RelocOffsetT Offset = 0;
-    C = getTranslator().getContext()->getConstantSym(Offset, Name,
-                                                     SuppressMangling);
+    if (IsUndefined)
+      C = getTranslator().getContext()->getConstantExternSym(Name);
+    else {
+      const Ice::RelocOffsetT Offset = 0;
+      C = getTranslator().getContext()->getConstantSym(Offset, Name,
+                                                       SuppressMangling);
+    }
     ValueIDConstants[ID] = C;
     return C;
   }
 
   /// Returns the number of function declarations in the bitcode file.
   unsigned getNumFunctionIDs() const { return FunctionDeclarationList.size(); }
 
   /// Returns the number of global declarations (i.e. IDs) defined in
   /// the bitcode file.
   unsigned getNumGlobalIDs() const {
@@ skipping 2658 matching lines @@
 
   if (TopLevelBlocks != 1) {
     errs() << IRFilename
            << ": Contains more than one module. Found: " << TopLevelBlocks
            << "\n";
     ErrorStatus.assign(EC_Bitcode);
   }
 }
 
 } // end of namespace Ice