Bitcode: Move version and global value module code parsers to separate functions. NFCI.

[pcc]

Summary

This will make it easier to teach this code about the string table.

[tejohnson]

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

388

Why move this into BitcodeReaderBase, rather than BitcodeReader?

[pcc]

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

388

In D31838 the code that reads names is shared between the module reader and the summary reader. That code needs to know the module version, so I needed to move the module version parsing code into the base class, including the fields that it sets.

[tejohnson]

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

388

Ok, but if this field is only ever going to be relevant to the BitcodeReader derived class, why not have a virtual method that takes the parsed version and can be used to set up whatever fields are relevant for each derived class? I would imagine this won't be the last time we end up needing to guard behavior specific to only one derived reader based on the version.

[pcc]

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

388

Such a method would be called from {,ModuleSummaryIndex}BitcodeReader:;parseModule which is already specific to the derived class. If we do what you suggest we might as well inline the parser code into the parseModule methods, i.e. what we are already doing. Would you prefer that? I suppose I have no strong objections to it, but figured it may be better to keep track of the version evolution in one place.

[tejohnson]

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

388

Actually I was thinking of a pure virtual method that would be called from BitcodeReaderBase::parseVersionRecord and passed the parsed ModuleVersion number. Then each derived reader would define this method as well as the flags specific to that reader. That way this flag could be moved into BitcodeReader, whereas something like the strtab flag being added in your other patch would be defined in BitcodeReaderBase (and set in parseVersionRecord) since it applies to all.

[pcc]

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

388

That doesn't really seem like an improvement on the status quo, though (at least IMHO). I'd rather just set everything in the base class, as it's simpler than trying to delegate to the derived classes.

That said I'd be fine with either approach, so let me know if you still want to change it.

[tejohnson]

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

388

I have a preference for keeping the flags in the derived class if they are specific to it. It seems cleaner to me and avoids needing to document which flags are applicable to which class(es).

[pcc]

• Move the flag back

[tejohnson]

LGTM

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

 protected:
   BitcodeReaderBase(BitstreamCursor Stream) : Stream(std::move(Stream)) {
     this->Stream.setBlockInfo(&BlockInfo);
   }
 
   BitstreamBlockInfo BlockInfo;
   BitstreamCursor Stream;
 
+  Expected<unsigned> parseVersionRecord(ArrayRef<uint64_t> Record);
+
   bool readBlockInfo();
 
   // Contains an arbitrary and optional string identifying the bitcode producer
   std::string ProducerIdentification;
 
   Error error(const Twine &Message);
 };
 
 Error BitcodeReaderBase::error(const Twine &Message) {
   std::string FullMsg = Message.str();
   if (!ProducerIdentification.empty())
     FullMsg += " (Producer: '" + ProducerIdentification + "' Reader: 'LLVM " +
                LLVM_VERSION_STRING "')";
   return ::error(FullMsg);
 }
 
+Expected<unsigned>
+BitcodeReaderBase::parseVersionRecord(ArrayRef<uint64_t> Record) {
+  if (Record.size() < 1)
+    return error("Invalid record");
+  unsigned ModuleVersion = Record[0];
+  if (ModuleVersion > 1)
+    return error("Invalid value");
+  return ModuleVersion;
+}
+
 class BitcodeReader : public BitcodeReaderBase, public GVMaterializer {
   LLVMContext &Context;
   Module *TheModule = nullptr;
   // Next offset to start scanning for lazy parsing of function bodies.
   uint64_t NextUnreadBit = 0;
   // Last function offset found in the VST.
   uint64_t LastFunctionBlockBit = 0;
   bool SeenValueSymbolTable = false;
   uint64_t VSTOffset = 0;
 
+  std::vector<std::string> SectionTable;
+  std::vector<std::string> GCTable;
+
   std::vector<Type*> TypeList;
   BitcodeReaderValueList ValueList;
   Optional<MetadataLoader> MDLoader;
   std::vector<Comdat *> ComdatList;
   SmallVector<Instruction *, 64> InstructionList;
 
   std::vector<std::pair<GlobalVariable*, unsigned> > GlobalInits;
   std::vector<std::pair<GlobalIndirectSymbol*, unsigned> > IndirectSymbolInits;
private:
   }
 
   /// Converts alignment exponent (i.e. power of two (or zero)) to the
   /// corresponding alignment to use. If alignment is too large, returns
   /// a corresponding error code.
   Error parseAlignmentValue(uint64_t Exponent, unsigned &Alignment);
   Error parseAttrKind(uint64_t Code, Attribute::AttrKind *Kind);
   Error parseModule(uint64_t ResumeBit, bool ShouldLazyLoadMetadata = false);
+
+  Error parseComdatRecord(ArrayRef<uint64_t> Record);
+  Error parseGlobalVarRecord(ArrayRef<uint64_t> Record);
+  Error parseFunctionRecord(ArrayRef<uint64_t> Record);
+  Error parseGlobalIndirectSymbolRecord(unsigned BitCode,
+                                        ArrayRef<uint64_t> Record);
+
   Error parseAttributeBlock();
   Error parseAttributeGroupBlock();
   Error parseTypeTable();
   Error parseTypeTableBody();
   Error parseOperandBundleTags();
 
   Expected<Value *> recordValue(SmallVectorImpl<uint64_t> &Record,
                                 unsigned NameIndex, Triple &TT);

 bool BitcodeReaderBase::readBlockInfo() {
   Optional<BitstreamBlockInfo> NewBlockInfo = Stream.ReadBlockInfoBlock();
   if (!NewBlockInfo)
     return true;
   BlockInfo = std::move(*NewBlockInfo);
   return false;
 }
 
+Error BitcodeReader::parseComdatRecord(ArrayRef<uint64_t> Record) {
+  // [selection_kind, name]
+  if (Record.size() < 2)
+    return error("Invalid record");
+  Comdat::SelectionKind SK = getDecodedComdatSelectionKind(Record[0]);
+  std::string Name;
+  unsigned ComdatNameSize = Record[1];
+  Name.reserve(ComdatNameSize);
+  for (unsigned i = 0; i != ComdatNameSize; ++i)
+    Name += (char)Record[2 + i];
+  Comdat *C = TheModule->getOrInsertComdat(Name);
+  C->setSelectionKind(SK);
+  ComdatList.push_back(C);
+  return Error::success();
+}
+
+Error BitcodeReader::parseGlobalVarRecord(ArrayRef<uint64_t> Record) {
+  // [pointer type, isconst, initid, linkage, alignment, section,
+  // visibility, threadlocal, unnamed_addr, externally_initialized,
+  // dllstorageclass, comdat]
+  if (Record.size() < 6)
+    return error("Invalid record");
+  Type *Ty = getTypeByID(Record[0]);
+  if (!Ty)
+    return error("Invalid record");
+  bool isConstant = Record[1] & 1;
+  bool explicitType = Record[1] & 2;
+  unsigned AddressSpace;
+  if (explicitType) {
+    AddressSpace = Record[1] >> 2;
+  } else {
+    if (!Ty->isPointerTy())
+      return error("Invalid type for value");
+    AddressSpace = cast<PointerType>(Ty)->getAddressSpace();
+    Ty = cast<PointerType>(Ty)->getElementType();
+  }
+
+  uint64_t RawLinkage = Record[3];
+  GlobalValue::LinkageTypes Linkage = getDecodedLinkage(RawLinkage);
+  unsigned Alignment;
+  if (Error Err = parseAlignmentValue(Record[4], Alignment))
+    return Err;
+  std::string Section;
+  if (Record[5]) {
+    if (Record[5] - 1 >= SectionTable.size())
+      return error("Invalid ID");
+    Section = SectionTable[Record[5] - 1];
+  }
+  GlobalValue::VisibilityTypes Visibility = GlobalValue::DefaultVisibility;
+  // Local linkage must have default visibility.
+  if (Record.size() > 6 && !GlobalValue::isLocalLinkage(Linkage))
+    // FIXME: Change to an error if non-default in 4.0.
+    Visibility = getDecodedVisibility(Record[6]);
+
+  GlobalVariable::ThreadLocalMode TLM = GlobalVariable::NotThreadLocal;
+  if (Record.size() > 7)
+    TLM = getDecodedThreadLocalMode(Record[7]);
+
+  GlobalValue::UnnamedAddr UnnamedAddr = GlobalValue::UnnamedAddr::None;
+  if (Record.size() > 8)
+    UnnamedAddr = getDecodedUnnamedAddrType(Record[8]);
+
+  bool ExternallyInitialized = false;
+  if (Record.size() > 9)
+    ExternallyInitialized = Record[9];
+
+  GlobalVariable *NewGV =
+      new GlobalVariable(*TheModule, Ty, isConstant, Linkage, nullptr, "",
+                         nullptr, TLM, AddressSpace, ExternallyInitialized);
+  NewGV->setAlignment(Alignment);
+  if (!Section.empty())
+    NewGV->setSection(Section);
+  NewGV->setVisibility(Visibility);
+  NewGV->setUnnamedAddr(UnnamedAddr);
+
+  if (Record.size() > 10)
+    NewGV->setDLLStorageClass(getDecodedDLLStorageClass(Record[10]));
+  else
+    upgradeDLLImportExportLinkage(NewGV, RawLinkage);
+
+  ValueList.push_back(NewGV);
+
+  // Remember which value to use for the global initializer.
+  if (unsigned InitID = Record[2])
+    GlobalInits.push_back(std::make_pair(NewGV, InitID - 1));
+
+  if (Record.size() > 11) {
+    if (unsigned ComdatID = Record[11]) {
+      if (ComdatID > ComdatList.size())
+        return error("Invalid global variable comdat ID");
+      NewGV->setComdat(ComdatList[ComdatID - 1]);
+    }
+  } else if (hasImplicitComdat(RawLinkage)) {
+    NewGV->setComdat(reinterpret_cast<Comdat *>(1));
+  }
+  return Error::success();
+}
+
+Error BitcodeReader::parseFunctionRecord(ArrayRef<uint64_t> Record) {
+  // [type, callingconv, isproto, linkage, paramattr, alignment, section,
+  // visibility, gc, unnamed_addr, prologuedata, dllstorageclass, comdat,
+  // prefixdata]
+  if (Record.size() < 8)
+    return error("Invalid record");
+  Type *Ty = getTypeByID(Record[0]);
+  if (!Ty)
+    return error("Invalid record");
+  if (auto *PTy = dyn_cast<PointerType>(Ty))
+    Ty = PTy->getElementType();
+  auto *FTy = dyn_cast<FunctionType>(Ty);
+  if (!FTy)
+    return error("Invalid type for value");
+  auto CC = static_cast<CallingConv::ID>(Record[1]);
+  if (CC & ~CallingConv::MaxID)
+    return error("Invalid calling convention ID");
+
+  Function *Func =
+      Function::Create(FTy, GlobalValue::ExternalLinkage, "", TheModule);
+
+  Func->setCallingConv(CC);
+  bool isProto = Record[2];
+  uint64_t RawLinkage = Record[3];
+  Func->setLinkage(getDecodedLinkage(RawLinkage));
+  Func->setAttributes(getAttributes(Record[4]));
+
+  unsigned Alignment;
+  if (Error Err = parseAlignmentValue(Record[5], Alignment))
+    return Err;
+  Func->setAlignment(Alignment);
+  if (Record[6]) {
+    if (Record[6] - 1 >= SectionTable.size())
+      return error("Invalid ID");
+    Func->setSection(SectionTable[Record[6] - 1]);
+  }
+  // Local linkage must have default visibility.
+  if (!Func->hasLocalLinkage())
+    // FIXME: Change to an error if non-default in 4.0.
+    Func->setVisibility(getDecodedVisibility(Record[7]));
+  if (Record.size() > 8 && Record[8]) {
+    if (Record[8] - 1 >= GCTable.size())
+      return error("Invalid ID");
+    Func->setGC(GCTable[Record[8] - 1]);
+  }
+  GlobalValue::UnnamedAddr UnnamedAddr = GlobalValue::UnnamedAddr::None;
+  if (Record.size() > 9)
+    UnnamedAddr = getDecodedUnnamedAddrType(Record[9]);
+  Func->setUnnamedAddr(UnnamedAddr);
+  if (Record.size() > 10 && Record[10] != 0)
+    FunctionPrologues.push_back(std::make_pair(Func, Record[10] - 1));
+
+  if (Record.size() > 11)
+    Func->setDLLStorageClass(getDecodedDLLStorageClass(Record[11]));
+  else
+    upgradeDLLImportExportLinkage(Func, RawLinkage);
+
+  if (Record.size() > 12) {
+    if (unsigned ComdatID = Record[12]) {
+      if (ComdatID > ComdatList.size())
+        return error("Invalid function comdat ID");
+      Func->setComdat(ComdatList[ComdatID - 1]);
+    }
+  } else if (hasImplicitComdat(RawLinkage)) {
+    Func->setComdat(reinterpret_cast<Comdat *>(1));
+  }
+
+  if (Record.size() > 13 && Record[13] != 0)
+    FunctionPrefixes.push_back(std::make_pair(Func, Record[13] - 1));
+
+  if (Record.size() > 14 && Record[14] != 0)
+    FunctionPersonalityFns.push_back(std::make_pair(Func, Record[14] - 1));
+
+  ValueList.push_back(Func);
+
+  // If this is a function with a body, remember the prototype we are
+  // creating now, so that we can match up the body with them later.
+  if (!isProto) {
+    Func->setIsMaterializable(true);
+    FunctionsWithBodies.push_back(Func);
+    DeferredFunctionInfo[Func] = 0;
+  }
+  return Error::success();
+}
+
+Error BitcodeReader::parseGlobalIndirectSymbolRecord(
+    unsigned BitCode, ArrayRef<uint64_t> Record) {
+  // ALIAS_OLD: [alias type, aliasee val#, linkage]
+  // ALIAS: [alias type, addrspace, aliasee val#, linkage, visibility,
+  // dllstorageclass]
+  // IFUNC: [alias type, addrspace, aliasee val#, linkage,
+  // visibility, dllstorageclass]
+  bool NewRecord = BitCode != bitc::MODULE_CODE_ALIAS_OLD;
+  if (Record.size() < (3 + (unsigned)NewRecord))
+    return error("Invalid record");
+  unsigned OpNum = 0;
+  Type *Ty = getTypeByID(Record[OpNum++]);
+  if (!Ty)
+    return error("Invalid record");
+
+  unsigned AddrSpace;
+  if (!NewRecord) {
+    auto *PTy = dyn_cast<PointerType>(Ty);
+    if (!PTy)
+      return error("Invalid type for value");
+    Ty = PTy->getElementType();
+    AddrSpace = PTy->getAddressSpace();
+  } else {
+    AddrSpace = Record[OpNum++];
+  }
+
+  auto Val = Record[OpNum++];
+  auto Linkage = Record[OpNum++];
+  GlobalIndirectSymbol *NewGA;
+  if (BitCode == bitc::MODULE_CODE_ALIAS ||
+      BitCode == bitc::MODULE_CODE_ALIAS_OLD)
+    NewGA = GlobalAlias::create(Ty, AddrSpace, getDecodedLinkage(Linkage), "",
+                                TheModule);
+  else
+    NewGA = GlobalIFunc::create(Ty, AddrSpace, getDecodedLinkage(Linkage), "",
+                                nullptr, TheModule);
+  // Old bitcode files didn't have visibility field.
+  // Local linkage must have default visibility.
+  if (OpNum != Record.size()) {
+    auto VisInd = OpNum++;
+    if (!NewGA->hasLocalLinkage())
+      // FIXME: Change to an error if non-default in 4.0.
+      NewGA->setVisibility(getDecodedVisibility(Record[VisInd]));
+  }
+  if (OpNum != Record.size())
+    NewGA->setDLLStorageClass(getDecodedDLLStorageClass(Record[OpNum++]));
+  else
+    upgradeDLLImportExportLinkage(NewGA, Linkage);
+  if (OpNum != Record.size())
+    NewGA->setThreadLocalMode(getDecodedThreadLocalMode(Record[OpNum++]));
+  if (OpNum != Record.size())
+    NewGA->setUnnamedAddr(getDecodedUnnamedAddrType(Record[OpNum++]));
+  ValueList.push_back(NewGA);
+  IndirectSymbolInits.push_back(std::make_pair(NewGA, Val));
+  return Error::success();
+}
+
 Error BitcodeReader::parseModule(uint64_t ResumeBit,
                                  bool ShouldLazyLoadMetadata) {
   if (ResumeBit)
     Stream.JumpToBit(ResumeBit);
   else if (Stream.EnterSubBlock(bitc::MODULE_BLOCK_ID))
     return error("Invalid record");
 
   SmallVector<uint64_t, 64> Record;
-  std::vector<std::string> SectionTable;
-  std::vector<std::string> GCTable;
 
   // Read all the records for this module.
   while (true) {
     BitstreamEntry Entry = Stream.advance();
 
     switch (Entry.Kind) {
     case BitstreamEntry::Error:
       return error("Malformed block");
case BitstreamEntry::Record:
       // The interesting case.
       break;
     }
 
     // Read a record.
     auto BitCode = Stream.readRecord(Entry.ID, Record);
     switch (BitCode) {
     default: break;  // Default behavior, ignore unknown content.
-    case bitc::MODULE_CODE_VERSION: {  // VERSION: [version#]
-      if (Record.size() < 1)
-        return error("Invalid record");
-      // Only version #0 and #1 are supported so far.
-      unsigned module_version = Record[0];
-      switch (module_version) {
-        default:
-          return error("Invalid value");
-        case 0:
-          UseRelativeIDs = false;
-          break;
-        case 1:
-          UseRelativeIDs = true;
-          break;
-      }
+    case bitc::MODULE_CODE_VERSION: {
+      Expected<unsigned> VersionOrErr = parseVersionRecord(Record);
+      if (!VersionOrErr)
+        return VersionOrErr.takeError();
+      UseRelativeIDs = *VersionOrErr >= 1;
       break;
     }
     case bitc::MODULE_CODE_TRIPLE: {  // TRIPLE: [strchr x N]
       std::string S;
       if (convertToString(Record, 0, S))
         return error("Invalid record");
       TheModule->setTargetTriple(S);
       break;
while (true) {
     }
     case bitc::MODULE_CODE_GCNAME: {  // SECTIONNAME: [strchr x N]
       std::string S;
       if (convertToString(Record, 0, S))
         return error("Invalid record");
       GCTable.push_back(S);
       break;
     }
-    case bitc::MODULE_CODE_COMDAT: { // COMDAT: [selection_kind, name]
-      if (Record.size() < 2)
-        return error("Invalid record");
-      Comdat::SelectionKind SK = getDecodedComdatSelectionKind(Record[0]);
-      unsigned ComdatNameSize = Record[1];
-      std::string ComdatName;
-      ComdatName.reserve(ComdatNameSize);
-      for (unsigned i = 0; i != ComdatNameSize; ++i)
-        ComdatName += (char)Record[2 + i];
-      Comdat *C = TheModule->getOrInsertComdat(ComdatName);
-      C->setSelectionKind(SK);
-      ComdatList.push_back(C);
+    case bitc::MODULE_CODE_COMDAT: {
+      if (Error Err = parseComdatRecord(Record))
+        return Err;
       break;
     }
-    // GLOBALVAR: [pointer type, isconst, initid,
-    //             linkage, alignment, section, visibility, threadlocal,
-    //             unnamed_addr, externally_initialized, dllstorageclass,
-    //             comdat]
     case bitc::MODULE_CODE_GLOBALVAR: {
-      if (Record.size() < 6)
-        return error("Invalid record");
-      Type *Ty = getTypeByID(Record[0]);
-      if (!Ty)
-        return error("Invalid record");
-      bool isConstant = Record[1] & 1;
-      bool explicitType = Record[1] & 2;
-      unsigned AddressSpace;
-      if (explicitType) {
-        AddressSpace = Record[1] >> 2;
-      } else {
-        if (!Ty->isPointerTy())
-          return error("Invalid type for value");
-        AddressSpace = cast<PointerType>(Ty)->getAddressSpace();
-        Ty = cast<PointerType>(Ty)->getElementType();
-      }
-
-      uint64_t RawLinkage = Record[3];
-      GlobalValue::LinkageTypes Linkage = getDecodedLinkage(RawLinkage);
-      unsigned Alignment;
-      if (Error Err = parseAlignmentValue(Record[4], Alignment))
+      if (Error Err = parseGlobalVarRecord(Record))
         return Err;
-      std::string Section;
-      if (Record[5]) {
-        if (Record[5]-1 >= SectionTable.size())
-          return error("Invalid ID");
-        Section = SectionTable[Record[5]-1];
-      }
-      GlobalValue::VisibilityTypes Visibility = GlobalValue::DefaultVisibility;
-      // Local linkage must have default visibility.
-      if (Record.size() > 6 && !GlobalValue::isLocalLinkage(Linkage))
-        // FIXME: Change to an error if non-default in 4.0.
-        Visibility = getDecodedVisibility(Record[6]);
-
-      GlobalVariable::ThreadLocalMode TLM = GlobalVariable::NotThreadLocal;
-      if (Record.size() > 7)
-        TLM = getDecodedThreadLocalMode(Record[7]);
-
-      GlobalValue::UnnamedAddr UnnamedAddr = GlobalValue::UnnamedAddr::None;
-      if (Record.size() > 8)
-        UnnamedAddr = getDecodedUnnamedAddrType(Record[8]);
-
-      bool ExternallyInitialized = false;
-      if (Record.size() > 9)
-        ExternallyInitialized = Record[9];
-
-      GlobalVariable *NewGV =
-        new GlobalVariable(*TheModule, Ty, isConstant, Linkage, nullptr, "", nullptr,
-                           TLM, AddressSpace, ExternallyInitialized);
-      NewGV->setAlignment(Alignment);
-      if (!Section.empty())
-        NewGV->setSection(Section);
-      NewGV->setVisibility(Visibility);
-      NewGV->setUnnamedAddr(UnnamedAddr);
-
-      if (Record.size() > 10)
-        NewGV->setDLLStorageClass(getDecodedDLLStorageClass(Record[10]));
-      else
-        upgradeDLLImportExportLinkage(NewGV, RawLinkage);
-
-      ValueList.push_back(NewGV);
-
-      // Remember which value to use for the global initializer.
-      if (unsigned InitID = Record[2])
-        GlobalInits.push_back(std::make_pair(NewGV, InitID-1));
-
-      if (Record.size() > 11) {
-        if (unsigned ComdatID = Record[11]) {
-          if (ComdatID > ComdatList.size())
-            return error("Invalid global variable comdat ID");
-          NewGV->setComdat(ComdatList[ComdatID - 1]);
-        }
-      } else if (hasImplicitComdat(RawLinkage)) {
-        NewGV->setComdat(reinterpret_cast<Comdat *>(1));
-      }
-
       break;
     }
-    // FUNCTION:  [type, callingconv, isproto, linkage, paramattr,
-    //             alignment, section, visibility, gc, unnamed_addr,
-    //             prologuedata, dllstorageclass, comdat, prefixdata]
     case bitc::MODULE_CODE_FUNCTION: {
-      if (Record.size() < 8)
-        return error("Invalid record");
-      Type *Ty = getTypeByID(Record[0]);
-      if (!Ty)
-        return error("Invalid record");
-      if (auto *PTy = dyn_cast<PointerType>(Ty))
-        Ty = PTy->getElementType();
-      auto *FTy = dyn_cast<FunctionType>(Ty);
-      if (!FTy)
-        return error("Invalid type for value");
-      auto CC = static_cast<CallingConv::ID>(Record[1]);
-      if (CC & ~CallingConv::MaxID)
-        return error("Invalid calling convention ID");
-
-      Function *Func = Function::Create(FTy, GlobalValue::ExternalLinkage,
-                                        "", TheModule);
-
-      Func->setCallingConv(CC);
-      bool isProto = Record[2];
-      uint64_t RawLinkage = Record[3];
-      Func->setLinkage(getDecodedLinkage(RawLinkage));
-      Func->setAttributes(getAttributes(Record[4]));
-
-      unsigned Alignment;
-      if (Error Err = parseAlignmentValue(Record[5], Alignment))
+      if (Error Err = parseFunctionRecord(Record))
         return Err;
-      Func->setAlignment(Alignment);
-      if (Record[6]) {
-        if (Record[6]-1 >= SectionTable.size())
-          return error("Invalid ID");
-        Func->setSection(SectionTable[Record[6]-1]);
-      }
-      // Local linkage must have default visibility.
-      if (!Func->hasLocalLinkage())
-        // FIXME: Change to an error if non-default in 4.0.
-        Func->setVisibility(getDecodedVisibility(Record[7]));
-      if (Record.size() > 8 && Record[8]) {
-        if (Record[8]-1 >= GCTable.size())
-          return error("Invalid ID");
-        Func->setGC(GCTable[Record[8] - 1]);
-      }
-      GlobalValue::UnnamedAddr UnnamedAddr = GlobalValue::UnnamedAddr::None;
-      if (Record.size() > 9)
-        UnnamedAddr = getDecodedUnnamedAddrType(Record[9]);
-      Func->setUnnamedAddr(UnnamedAddr);
-      if (Record.size() > 10 && Record[10] != 0)
-        FunctionPrologues.push_back(std::make_pair(Func, Record[10]-1));
-
-      if (Record.size() > 11)
-        Func->setDLLStorageClass(getDecodedDLLStorageClass(Record[11]));
-      else
-        upgradeDLLImportExportLinkage(Func, RawLinkage);
-
-      if (Record.size() > 12) {
-        if (unsigned ComdatID = Record[12]) {
-          if (ComdatID > ComdatList.size())
-            return error("Invalid function comdat ID");
-          Func->setComdat(ComdatList[ComdatID - 1]);
-        }
-      } else if (hasImplicitComdat(RawLinkage)) {
-        Func->setComdat(reinterpret_cast<Comdat *>(1));
-      }
-
-      if (Record.size() > 13 && Record[13] != 0)
-        FunctionPrefixes.push_back(std::make_pair(Func, Record[13]-1));
-
-      if (Record.size() > 14 && Record[14] != 0)
-        FunctionPersonalityFns.push_back(std::make_pair(Func, Record[14] - 1));
-
-      ValueList.push_back(Func);
-
-      // If this is a function with a body, remember the prototype we are
-      // creating now, so that we can match up the body with them later.
-      if (!isProto) {
-        Func->setIsMaterializable(true);
-        FunctionsWithBodies.push_back(Func);
-        DeferredFunctionInfo[Func] = 0;
-      }
       break;
     }
-    // ALIAS: [alias type, addrspace, aliasee val#, linkage]
-    // ALIAS: [alias type, addrspace, aliasee val#, linkage, visibility, dllstorageclass]
-    // IFUNC: [alias type, addrspace, aliasee val#, linkage, visibility, dllstorageclass]
     case bitc::MODULE_CODE_IFUNC:
     case bitc::MODULE_CODE_ALIAS:
     case bitc::MODULE_CODE_ALIAS_OLD: {
-      bool NewRecord = BitCode != bitc::MODULE_CODE_ALIAS_OLD;
-      if (Record.size() < (3 + (unsigned)NewRecord))
-        return error("Invalid record");
-      unsigned OpNum = 0;
-      Type *Ty = getTypeByID(Record[OpNum++]);
-      if (!Ty)
-        return error("Invalid record");
-
-      unsigned AddrSpace;
-      if (!NewRecord) {
-        auto *PTy = dyn_cast<PointerType>(Ty);
-        if (!PTy)
-          return error("Invalid type for value");
-        Ty = PTy->getElementType();
-        AddrSpace = PTy->getAddressSpace();
-      } else {
-        AddrSpace = Record[OpNum++];
-      }
-
-      auto Val = Record[OpNum++];
-      auto Linkage = Record[OpNum++];
-      GlobalIndirectSymbol *NewGA;
-      if (BitCode == bitc::MODULE_CODE_ALIAS ||
-          BitCode == bitc::MODULE_CODE_ALIAS_OLD)
-        NewGA = GlobalAlias::create(Ty, AddrSpace, getDecodedLinkage(Linkage),
-                                    "", TheModule);
-      else
-        NewGA = GlobalIFunc::create(Ty, AddrSpace, getDecodedLinkage(Linkage),
-                                    "", nullptr, TheModule);
-      // Old bitcode files didn't have visibility field.
-      // Local linkage must have default visibility.
-      if (OpNum != Record.size()) {
-        auto VisInd = OpNum++;
-        if (!NewGA->hasLocalLinkage())
-          // FIXME: Change to an error if non-default in 4.0.
-          NewGA->setVisibility(getDecodedVisibility(Record[VisInd]));
-      }
-      if (OpNum != Record.size())
-        NewGA->setDLLStorageClass(getDecodedDLLStorageClass(Record[OpNum++]));
-      else
-        upgradeDLLImportExportLinkage(NewGA, Linkage);
-      if (OpNum != Record.size())
-        NewGA->setThreadLocalMode(getDecodedThreadLocalMode(Record[OpNum++]));
-      if (OpNum != Record.size())
-        NewGA->setUnnamedAddr(getDecodedUnnamedAddrType(Record[OpNum++]));
-      ValueList.push_back(NewGA);
-      IndirectSymbolInits.push_back(std::make_pair(NewGA, Val));
+      if (Error Err = parseGlobalIndirectSymbolRecord(BitCode, Record))
+        return Err;
       break;
     }
     /// MODULE_CODE_VSTOFFSET: [offset]
     case bitc::MODULE_CODE_VSTOFFSET:
       if (Record.size() < 1)
         return error("Invalid record");
       // Note that we subtract 1 here because the offset is relative to one word
       // before the start of the identification or module block, which was