text: //===- BitcodeReader.cpp - Internal BitcodeReader implementation ----------===//
  //
  // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  // See https://llvm.org/LICENSE.txt for license information.
  // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  //
  //===----------------------------------------------------------------------===//
  
  #include "llvm/Bitcode/BitcodeReader.h"
  #include "MetadataLoader.h"
  #include "ValueList.h"
  #include "llvm/ADT/APFloat.h"
  #include "llvm/ADT/APInt.h"
  #include "llvm/ADT/ArrayRef.h"
  #include "llvm/ADT/DenseMap.h"
  #include "llvm/ADT/Optional.h"
  #include "llvm/ADT/STLExtras.h"
  #include "llvm/ADT/SmallString.h"
  #include "llvm/ADT/SmallVector.h"
  #include "llvm/ADT/StringRef.h"
  #include "llvm/ADT/Triple.h"
  #include "llvm/ADT/Twine.h"
  #include "llvm/Bitcode/BitcodeCommon.h"
  #include "llvm/Bitcode/LLVMBitCodes.h"
  #include "llvm/Bitstream/BitstreamReader.h"
  #include "llvm/Config/llvm-config.h"
  #include "llvm/IR/Argument.h"
  #include "llvm/IR/Attributes.h"
  #include "llvm/IR/AutoUpgrade.h"
  #include "llvm/IR/BasicBlock.h"
  #include "llvm/IR/CallingConv.h"
  #include "llvm/IR/Comdat.h"
  #include "llvm/IR/Constant.h"
  #include "llvm/IR/Constants.h"
  #include "llvm/IR/DataLayout.h"
  #include "llvm/IR/DebugInfo.h"
  #include "llvm/IR/DebugInfoMetadata.h"
  #include "llvm/IR/DebugLoc.h"
  #include "llvm/IR/DerivedTypes.h"
  #include "llvm/IR/Function.h"
  #include "llvm/IR/GVMaterializer.h"
  #include "llvm/IR/GlobalAlias.h"
  #include "llvm/IR/GlobalIFunc.h"
  #include "llvm/IR/GlobalIndirectSymbol.h"
  #include "llvm/IR/GlobalObject.h"
  #include "llvm/IR/GlobalValue.h"
  #include "llvm/IR/GlobalVariable.h"
  #include "llvm/IR/InlineAsm.h"
  #include "llvm/IR/InstIterator.h"
  #include "llvm/IR/InstrTypes.h"
  #include "llvm/IR/Instruction.h"
  #include "llvm/IR/Instructions.h"
  #include "llvm/IR/Intrinsics.h"
  #include "llvm/IR/LLVMContext.h"
  #include "llvm/IR/Metadata.h"
  #include "llvm/IR/Module.h"
  #include "llvm/IR/ModuleSummaryIndex.h"
  #include "llvm/IR/Operator.h"
  #include "llvm/IR/Type.h"
  #include "llvm/IR/Value.h"
  #include "llvm/IR/Verifier.h"
  #include "llvm/Support/AtomicOrdering.h"
  #include "llvm/Support/Casting.h"
  #include "llvm/Support/CommandLine.h"
  #include "llvm/Support/Compiler.h"
  #include "llvm/Support/Debug.h"
  #include "llvm/Support/Error.h"
  #include "llvm/Support/ErrorHandling.h"
  #include "llvm/Support/ErrorOr.h"
  #include "llvm/Support/ManagedStatic.h"
  #include "llvm/Support/MathExtras.h"
  #include "llvm/Support/MemoryBuffer.h"
  #include "llvm/Support/raw_ostream.h"
  #include <algorithm>
  #include <cassert>
  #include <cstddef>
  #include <cstdint>
  #include <deque>
  #include <map>
  #include <memory>
  #include <set>
  #include <string>
  #include <system_error>
  #include <tuple>
  #include <utility>
  #include <vector>
  
  using namespace llvm;
  
  static cl::opt<bool> PrintSummaryGUIDs(
      "print-summary-global-ids", cl::init(false), cl::Hidden,
      cl::desc(
          "Print the global id for each value when reading the module summary"));
  
  namespace {
  
  enum {
    SWITCH_INST_MAGIC = 0x4B5 // May 2012 => 1205 => Hex
  };
  
  } // end anonymous namespace
  
  static Error error(const Twine &Message) {
    return make_error<StringError>(
        Message, make_error_code(BitcodeError::CorruptedBitcode));
  }
  
  static Error hasInvalidBitcodeHeader(BitstreamCursor &Stream) {
    if (!Stream.canSkipToPos(4))
      return createStringError(std::errc::illegal_byte_sequence,
                               "file too small to contain bitcode header");
    for (unsigned C : {'B', 'C'})
      if (Expected<SimpleBitstreamCursor::word_t> Res = Stream.Read(8)) {
        if (Res.get() != C)
          return createStringError(std::errc::illegal_byte_sequence,
                                   "file doesn't start with bitcode header");
      } else
        return Res.takeError();
    for (unsigned C : {0x0, 0xC, 0xE, 0xD})
      if (Expected<SimpleBitstreamCursor::word_t> Res = Stream.Read(4)) {
        if (Res.get() != C)
          return createStringError(std::errc::illegal_byte_sequence,
                                   "file doesn't start with bitcode header");
      } else
        return Res.takeError();
    return Error::success();
  }
  
  static Expected<BitstreamCursor> initStream(MemoryBufferRef Buffer) {
    const unsigned char *BufPtr = (const unsigned char *)Buffer.getBufferStart();
    const unsigned char *BufEnd = BufPtr + Buffer.getBufferSize();
  
    if (Buffer.getBufferSize() & 3)
      return error("Invalid bitcode signature");
  
    // If we have a wrapper header, parse it and ignore the non-bc file contents.
    // The magic number is 0x0B17C0DE stored in little endian.
    if (isBitcodeWrapper(BufPtr, BufEnd))
      if (SkipBitcodeWrapperHeader(BufPtr, BufEnd, true))
        return error("Invalid bitcode wrapper header");
  
    BitstreamCursor Stream(ArrayRef<uint8_t>(BufPtr, BufEnd));
    if (Error Err = hasInvalidBitcodeHeader(Stream))
      return std::move(Err);
  
    return std::move(Stream);
  }
  
  /// Convert a string from a record into an std::string, return true on failure.
  template <typename StrTy>
  static bool convertToString(ArrayRef<uint64_t> Record, unsigned Idx,
                              StrTy &Result) {
    if (Idx > Record.size())
      return true;
  
    Result.append(Record.begin() + Idx, Record.end());
    return false;
  }
  
  // Strip all the TBAA attachment for the module.
  static void stripTBAA(Module *M) {
    for (auto &F : *M) {
      if (F.isMaterializable())
        continue;
      for (auto &I : instructions(F))
        I.setMetadata(LLVMContext::MD_tbaa, nullptr);
    }
  }
  
  /// Read the "IDENTIFICATION_BLOCK_ID" block, do some basic enforcement on the
  /// "epoch" encoded in the bitcode, and return the producer name if any.
  static Expected<std::string> readIdentificationBlock(BitstreamCursor &Stream) {
    if (Error Err = Stream.EnterSubBlock(bitc::IDENTIFICATION_BLOCK_ID))
      return std::move(Err);
  
    // Read all the records.
    SmallVector<uint64_t, 64> Record;
  
    std::string ProducerIdentification;
  
    while (true) {
      BitstreamEntry Entry;
      if (Expected<BitstreamEntry> Res = Stream.advance())
        Entry = Res.get();
      else
        return Res.takeError();
  
      switch (Entry.Kind) {
      default:
      case BitstreamEntry::Error:
        return error("Malformed block");
      case BitstreamEntry::EndBlock:
        return ProducerIdentification;
      case BitstreamEntry::Record:
        // The interesting case.
        break;
      }
  
      // Read a record.
      Record.clear();
      Expected<unsigned> MaybeBitCode = Stream.readRecord(Entry.ID, Record);
      if (!MaybeBitCode)
        return MaybeBitCode.takeError();
      switch (MaybeBitCode.get()) {
      default: // Default behavior: reject
        return error("Invalid value");
      case bitc::IDENTIFICATION_CODE_STRING: // IDENTIFICATION: [strchr x N]
        convertToString(Record, 0, ProducerIdentification);
        break;
      case bitc::IDENTIFICATION_CODE_EPOCH: { // EPOCH: [epoch#]
        unsigned epoch = (unsigned)Record[0];
        if (epoch != bitc::BITCODE_CURRENT_EPOCH) {
          return error(
            Twine("Incompatible epoch: Bitcode '") + Twine(epoch) +
            "' vs current: '" + Twine(bitc::BITCODE_CURRENT_EPOCH) + "'");
        }
      }
      }
    }
  }
  
  static Expected<std::string> readIdentificationCode(BitstreamCursor &Stream) {
    // We expect a number of well-defined blocks, though we don't necessarily
    // need to understand them all.
    while (true) {
      if (Stream.AtEndOfStream())
        return "";
  
      BitstreamEntry Entry;
      if (Expected<BitstreamEntry> Res = Stream.advance())
        Entry = std::move(Res.get());
      else
        return Res.takeError();
  
      switch (Entry.Kind) {
      case BitstreamEntry::EndBlock:
      case BitstreamEntry::Error:
        return error("Malformed block");
  
      case BitstreamEntry::SubBlock:
        if (Entry.ID == bitc::IDENTIFICATION_BLOCK_ID)
          return readIdentificationBlock(Stream);
  
        // Ignore other sub-blocks.
        if (Error Err = Stream.SkipBlock())
          return std::move(Err);
        continue;
      case BitstreamEntry::Record:
        if (Expected<unsigned> Skipped = Stream.skipRecord(Entry.ID))
          continue;
        else
          return Skipped.takeError();
      }
    }
  }
  
  static Expected<bool> hasObjCCategoryInModule(BitstreamCursor &Stream) {
    if (Error Err = Stream.EnterSubBlock(bitc::MODULE_BLOCK_ID))
      return std::move(Err);
  
    SmallVector<uint64_t, 64> Record;
    // Read all the records for this module.
  
    while (true) {
      Expected<BitstreamEntry> MaybeEntry = Stream.advanceSkippingSubblocks();
      if (!MaybeEntry)
        return MaybeEntry.takeError();
      BitstreamEntry Entry = MaybeEntry.get();
  
      switch (Entry.Kind) {
      case BitstreamEntry::SubBlock: // Handled for us already.
      case BitstreamEntry::Error:
        return error("Malformed block");
      case BitstreamEntry::EndBlock:
        return false;
      case BitstreamEntry::Record:
        // The interesting case.
        break;
      }
  
      // Read a record.
      Expected<unsigned> MaybeRecord = Stream.readRecord(Entry.ID, Record);
      if (!MaybeRecord)
        return MaybeRecord.takeError();
      switch (MaybeRecord.get()) {
      default:
        break; // Default behavior, ignore unknown content.
      case bitc::MODULE_CODE_SECTIONNAME: { // SECTIONNAME: [strchr x N]
        std::string S;
        if (convertToString(Record, 0, S))
          return error("Invalid record");
        // Check for the i386 and other (x86_64, ARM) conventions
        if (S.find("__DATA,__objc_catlist") != std::string::npos ||
            S.find("__OBJC,__category") != std::string::npos)
          return true;
        break;
      }
      }
      Record.clear();
    }
    llvm_unreachable("Exit infinite loop");
  }
  
  static Expected<bool> hasObjCCategory(BitstreamCursor &Stream) {
    // We expect a number of well-defined blocks, though we don't necessarily
    // need to understand them all.
    while (true) {
      BitstreamEntry Entry;
      if (Expected<BitstreamEntry> Res = Stream.advance())
        Entry = std::move(Res.get());
      else
        return Res.takeError();
  
      switch (Entry.Kind) {
      case BitstreamEntry::Error:
        return error("Malformed block");
      case BitstreamEntry::EndBlock:
        return false;
  
      case BitstreamEntry::SubBlock:
        if (Entry.ID == bitc::MODULE_BLOCK_ID)
          return hasObjCCategoryInModule(Stream);
  
        // Ignore other sub-blocks.
        if (Error Err = Stream.SkipBlock())
          return std::move(Err);
        continue;
  
      case BitstreamEntry::Record:
        if (Expected<unsigned> Skipped = Stream.skipRecord(Entry.ID))
          continue;
        else
          return Skipped.takeError();
      }
    }
  }
  
  static Expected<std::string> readModuleTriple(BitstreamCursor &Stream) {
    if (Error Err = Stream.EnterSubBlock(bitc::MODULE_BLOCK_ID))
      return std::move(Err);
  
    SmallVector<uint64_t, 64> Record;
  
    std::string Triple;
  
    // Read all the records for this module.
    while (true) {
      Expected<BitstreamEntry> MaybeEntry = Stream.advanceSkippingSubblocks();
      if (!MaybeEntry)
        return MaybeEntry.takeError();
      BitstreamEntry Entry = MaybeEntry.get();
  
      switch (Entry.Kind) {
      case BitstreamEntry::SubBlock: // Handled for us already.
      case BitstreamEntry::Error:
        return error("Malformed block");
      case BitstreamEntry::EndBlock:
        return Triple;
      case BitstreamEntry::Record:
        // The interesting case.
        break;
      }
  
      // Read a record.
      Expected<unsigned> MaybeRecord = Stream.readRecord(Entry.ID, Record);
      if (!MaybeRecord)
        return MaybeRecord.takeError();
      switch (MaybeRecord.get()) {
      default: break;  // Default behavior, ignore unknown content.
      case bitc::MODULE_CODE_TRIPLE: {  // TRIPLE: [strchr x N]
        std::string S;
        if (convertToString(Record, 0, S))
          return error("Invalid record");
        Triple = S;
        break;
      }
      }
      Record.clear();
    }
    llvm_unreachable("Exit infinite loop");
  }
  
  static Expected<std::string> readTriple(BitstreamCursor &Stream) {
    // We expect a number of well-defined blocks, though we don't necessarily
    // need to understand them all.
    while (true) {
      Expected<BitstreamEntry> MaybeEntry = Stream.advance();
      if (!MaybeEntry)
        return MaybeEntry.takeError();
      BitstreamEntry Entry = MaybeEntry.get();
  
      switch (Entry.Kind) {
      case BitstreamEntry::Error:
        return error("Malformed block");
      case BitstreamEntry::EndBlock:
        return "";
  
      case BitstreamEntry::SubBlock:
        if (Entry.ID == bitc::MODULE_BLOCK_ID)
          return readModuleTriple(Stream);
  
        // Ignore other sub-blocks.
        if (Error Err = Stream.SkipBlock())
          return std::move(Err);
        continue;
  
      case BitstreamEntry::Record:
        if (llvm::Expected<unsigned> Skipped = Stream.skipRecord(Entry.ID))
          continue;
        else
          return Skipped.takeError();
      }
    }
  }
  
  namespace {
  
  class BitcodeReaderBase {
  protected:
    BitcodeReaderBase(BitstreamCursor Stream, StringRef Strtab)
        : Stream(std::move(Stream)), Strtab(Strtab) {
      this->Stream.setBlockInfo(&BlockInfo);
    }
  
    BitstreamBlockInfo BlockInfo;
    BitstreamCursor Stream;
    StringRef Strtab;
  
    /// In version 2 of the bitcode we store names of global values and comdats in
    /// a string table rather than in the VST.
    bool UseStrtab = false;
  
    Expected<unsigned> parseVersionRecord(ArrayRef<uint64_t> Record);
  
    /// If this module uses a string table, pop the reference to the string table
    /// and return the referenced string and the rest of the record. Otherwise
    /// just return the record itself.
    std::pair<StringRef, ArrayRef<uint64_t>>
    readNameFromStrtab(ArrayRef<uint64_t> Record);
  
    bool readBlockInfo();
  
    // Contains an arbitrary and optional string identifying the bitcode producer
    std::string ProducerIdentification;
  
    Error error(const Twine &Message);
  };
  
  } // end anonymous namespace
  
  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.empty())
      return error("Invalid record");
    unsigned ModuleVersion = Record[0];
    if (ModuleVersion > 2)
      return error("Invalid value");
    UseStrtab = ModuleVersion >= 2;
    return ModuleVersion;
  }
  
  std::pair<StringRef, ArrayRef<uint64_t>>
  BitcodeReaderBase::readNameFromStrtab(ArrayRef<uint64_t> Record) {
    if (!UseStrtab)
      return {"", Record};
    // Invalid reference. Let the caller complain about the record being empty.
    if (Record[0] + Record[1] > Strtab.size())
      return {"", {}};
    return {StringRef(Strtab.data() + Record[0], Record[1]), Record.slice(2)};
  }
  
  namespace {
  
  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;
    DenseMap<Function *, FunctionType *> FunctionTypes;
    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;
    std::vector<std::pair<Function *, unsigned>> FunctionPrefixes;
    std::vector<std::pair<Function *, unsigned>> FunctionPrologues;
    std::vector<std::pair<Function *, unsigned>> FunctionPersonalityFns;
  
    /// The set of attributes by index.  Index zero in the file is for null, and
    /// is thus not represented here.  As such all indices are off by one.
    std::vector<AttributeList> MAttributes;
  
    /// The set of attribute groups.
    std::map<unsigned, AttributeList> MAttributeGroups;
  
    /// While parsing a function body, this is a list of the basic blocks for the
    /// function.
    std::vector<BasicBlock*> FunctionBBs;
  
    // When reading the module header, this list is populated with functions that
    // have bodies later in the file.
    std::vector<Function*> FunctionsWithBodies;
  
    // When intrinsic functions are encountered which require upgrading they are
    // stored here with their replacement function.
    using UpdatedIntrinsicMap = DenseMap<Function *, Function *>;
    UpdatedIntrinsicMap UpgradedIntrinsics;
    // Intrinsics which were remangled because of types rename
    UpdatedIntrinsicMap RemangledIntrinsics;
  
    // Several operations happen after the module header has been read, but
    // before function bodies are processed. This keeps track of whether
    // we've done this yet.
    bool SeenFirstFunctionBody = false;
  
    /// When function bodies are initially scanned, this map contains info about
    /// where to find deferred function body in the stream.
    DenseMap<Function*, uint64_t> DeferredFunctionInfo;
  
    /// When Metadata block is initially scanned when parsing the module, we may
    /// choose to defer parsing of the metadata. This vector contains info about
    /// which Metadata blocks are deferred.
    std::vector<uint64_t> DeferredMetadataInfo;
  
    /// These are basic blocks forward-referenced by block addresses.  They are
    /// inserted lazily into functions when they're loaded.  The basic block ID is
    /// its index into the vector.
    DenseMap<Function *, std::vector<BasicBlock *>> BasicBlockFwdRefs;
    std::deque<Function *> BasicBlockFwdRefQueue;
  
    /// Indicates that we are using a new encoding for instruction operands where
    /// most operands in the current FUNCTION_BLOCK are encoded relative to the
    /// instruction number, for a more compact encoding.  Some instruction
    /// operands are not relative to the instruction ID: basic block numbers, and
    /// types. Once the old style function blocks have been phased out, we would
    /// not need this flag.
    bool UseRelativeIDs = false;
  
    /// True if all functions will be materialized, negating the need to process
    /// (e.g.) blockaddress forward references.
    bool WillMaterializeAllForwardRefs = false;
  
    bool StripDebugInfo = false;
    TBAAVerifier TBAAVerifyHelper;
  
    std::vector<std::string> BundleTags;
    SmallVector<SyncScope::ID, 8> SSIDs;
  
  public:
    BitcodeReader(BitstreamCursor Stream, StringRef Strtab,
                  StringRef ProducerIdentification, LLVMContext &Context);
  
    Error materializeForwardReferencedFunctions();
  
    Error materialize(GlobalValue *GV) override;
    Error materializeModule() override;
    std::vector<StructType *> getIdentifiedStructTypes() const override;
  
    /// Main interface to parsing a bitcode buffer.
    /// \returns true if an error occurred.
    Error parseBitcodeInto(
        Module *M, bool ShouldLazyLoadMetadata = false, bool IsImporting = false,
        DataLayoutCallbackTy DataLayoutCallback = [](std::string) {
          return None;
        });
  
    static uint64_t decodeSignRotatedValue(uint64_t V);
  
    /// Materialize any deferred Metadata block.
    Error materializeMetadata() override;
  
    void setStripDebugInfo() override;
  
  private:
    std::vector<StructType *> IdentifiedStructTypes;
    StructType *createIdentifiedStructType(LLVMContext &Context, StringRef Name);
    StructType *createIdentifiedStructType(LLVMContext &Context);
  
    /// Map all pointer types within \param Ty to the opaque pointer
    /// type in the same address space if opaque pointers are being
    /// used, otherwise nop. This converts a bitcode-reader internal
    /// type into one suitable for use in a Value.
    Type *flattenPointerTypes(Type *Ty) {
      return Ty;
    }
  
    /// Given a fully structured pointer type (i.e. not opaque), return
    /// the flattened form of its element, suitable for use in a Value.
    Type *getPointerElementFlatType(Type *Ty) {
      return flattenPointerTypes(cast<PointerType>(Ty)->getElementType());
    }
  
    /// Given a fully structured pointer type, get its element type in
    /// both fully structured form, and flattened form suitable for use
    /// in a Value.
    std::pair<Type *, Type *> getPointerElementTypes(Type *FullTy) {
      Type *ElTy = cast<PointerType>(FullTy)->getElementType();
      return std::make_pair(ElTy, flattenPointerTypes(ElTy));
    }
  
    /// Return the flattened type (suitable for use in a Value)
    /// specified by the given \param ID .
    Type *getTypeByID(unsigned ID) {
      return flattenPointerTypes(getFullyStructuredTypeByID(ID));
    }
  
    /// Return the fully structured (bitcode-reader internal) type
    /// corresponding to the given \param ID .
    Type *getFullyStructuredTypeByID(unsigned ID);
  
    Value *getFnValueByID(unsigned ID, Type *Ty, Type **FullTy = nullptr) {
      if (Ty && Ty->isMetadataTy())
        return MetadataAsValue::get(Ty->getContext(), getFnMetadataByID(ID));
      return ValueList.getValueFwdRef(ID, Ty, FullTy);
    }
  
    Metadata *getFnMetadataByID(unsigned ID) {
      return MDLoader->getMetadataFwdRefOrLoad(ID);
    }
  
    BasicBlock *getBasicBlock(unsigned ID) const {
      if (ID >= FunctionBBs.size()) return nullptr; // Invalid ID
      return FunctionBBs[ID];
    }
  
    AttributeList getAttributes(unsigned i) const {
      if (i-1 < MAttributes.size())
        return MAttributes[i-1];
      return AttributeList();
    }
  
    /// Read a value/type pair out of the specified record from slot 'Slot'.
    /// Increment Slot past the number of slots used in the record. Return true on
    /// failure.
    bool getValueTypePair(SmallVectorImpl<uint64_t> &Record, unsigned &Slot,
                          unsigned InstNum, Value *&ResVal,
                          Type **FullTy = nullptr) {
      if (Slot == Record.size()) return true;
      unsigned ValNo = (unsigned)Record[Slot++];
      // Adjust the ValNo, if it was encoded relative to the InstNum.
      if (UseRelativeIDs)
        ValNo = InstNum - ValNo;
      if (ValNo < InstNum) {
        // If this is not a forward reference, just return the value we already
        // have.
        ResVal = getFnValueByID(ValNo, nullptr, FullTy);
        return ResVal == nullptr;
      }
      if (Slot == Record.size())
        return true;
  
      unsigned TypeNo = (unsigned)Record[Slot++];
      ResVal = getFnValueByID(ValNo, getTypeByID(TypeNo));
      if (FullTy)
        *FullTy = getFullyStructuredTypeByID(TypeNo);
      return ResVal == nullptr;
    }
  
    /// Read a value out of the specified record from slot 'Slot'. Increment Slot
    /// past the number of slots used by the value in the record. Return true if
    /// there is an error.
    bool popValue(SmallVectorImpl<uint64_t> &Record, unsigned &Slot,
                  unsigned InstNum, Type *Ty, Value *&ResVal) {
      if (getValue(Record, Slot, InstNum, Ty, ResVal))
        return true;
      // All values currently take a single record slot.
      ++Slot;
      return false;
    }
  
    /// Like popValue, but does not increment the Slot number.
    bool getValue(SmallVectorImpl<uint64_t> &Record, unsigned Slot,
                  unsigned InstNum, Type *Ty, Value *&ResVal) {
      ResVal = getValue(Record, Slot, InstNum, Ty);
      return ResVal == nullptr;
    }
  
    /// Version of getValue that returns ResVal directly, or 0 if there is an
    /// error.
    Value *getValue(SmallVectorImpl<uint64_t> &Record, unsigned Slot,
                    unsigned InstNum, Type *Ty) {
      if (Slot == Record.size()) return nullptr;
      unsigned ValNo = (unsigned)Record[Slot];
      // Adjust the ValNo, if it was encoded relative to the InstNum.
      if (UseRelativeIDs)
        ValNo = InstNum - ValNo;
      return getFnValueByID(ValNo, Ty);
    }
  
    /// Like getValue, but decodes signed VBRs.
    Value *getValueSigned(SmallVectorImpl<uint64_t> &Record, unsigned Slot,
                          unsigned InstNum, Type *Ty) {
      if (Slot == Record.size()) return nullptr;
      unsigned ValNo = (unsigned)decodeSignRotatedValue(Record[Slot]);
      // Adjust the ValNo, if it was encoded relative to the InstNum.
      if (UseRelativeIDs)
        ValNo = InstNum - ValNo;
      return getFnValueByID(ValNo, Ty);
    }
  
    /// Upgrades old-style typeless byval attributes by adding the corresponding
    /// argument's pointee type.
    void propagateByValTypes(CallBase *CB, ArrayRef<Type *> ArgsFullTys);
  
    /// 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, MaybeAlign &Alignment);
    Error parseAttrKind(uint64_t Code, Attribute::AttrKind *Kind);
    Error parseModule(
        uint64_t ResumeBit, bool ShouldLazyLoadMetadata = false,
        DataLayoutCallbackTy DataLayoutCallback = [](StringRef) { return None; });
  
    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();
    Error parseSyncScopeNames();
  
    Expected<Value *> recordValue(SmallVectorImpl<uint64_t> &Record,
                                  unsigned NameIndex, Triple &TT);
    void setDeferredFunctionInfo(unsigned FuncBitcodeOffsetDelta, Function *F,
                                 ArrayRef<uint64_t> Record);
    Error parseValueSymbolTable(uint64_t Offset = 0);
    Error parseGlobalValueSymbolTable();
    Error parseConstants();
    Error rememberAndSkipFunctionBodies();
    Error rememberAndSkipFunctionBody();
    /// Save the positions of the Metadata blocks and skip parsing the blocks.
    Error rememberAndSkipMetadata();
    Error typeCheckLoadStoreInst(Type *ValType, Type *PtrType);
    Error parseFunctionBody(Function *F);
    Error globalCleanup();
    Error resolveGlobalAndIndirectSymbolInits();
    Error parseUseLists();
    Error findFunctionInStream(
        Function *F,
        DenseMap<Function *, uint64_t>::iterator DeferredFunctionInfoIterator);
  
    SyncScope::ID getDecodedSyncScopeID(unsigned Val);
  };
  
  /// Class to manage reading and parsing function summary index bitcode
  /// files/sections.
  class ModuleSummaryIndexBitcodeReader : public BitcodeReaderBase {
    /// The module index built during parsing.
    ModuleSummaryIndex &TheIndex;
  
    /// Indicates whether we have encountered a global value summary section
    /// yet during parsing.
    bool SeenGlobalValSummary = false;
  
    /// Indicates whether we have already parsed the VST, used for error checking.
    bool SeenValueSymbolTable = false;
  
    /// Set to the offset of the VST recorded in the MODULE_CODE_VSTOFFSET record.
    /// Used to enable on-demand parsing of the VST.
    uint64_t VSTOffset = 0;
  
    // Map to save ValueId to ValueInfo association that was recorded in the
    // ValueSymbolTable. It is used after the VST is parsed to convert
    // call graph edges read from the function summary from referencing
    // callees by their ValueId to using the ValueInfo instead, which is how
    // they are recorded in the summary index being built.
    // We save a GUID which refers to the same global as the ValueInfo, but
    // ignoring the linkage, i.e. for values other than local linkage they are
    // identical.
    DenseMap<unsigned, std::pair<ValueInfo, GlobalValue::GUID>>
        ValueIdToValueInfoMap;
  
    /// Map populated during module path string table parsing, from the
    /// module ID to a string reference owned by the index's module
    /// path string table, used to correlate with combined index
    /// summary records.
    DenseMap<uint64_t, StringRef> ModuleIdMap;
  
    /// Original source file name recorded in a bitcode record.
    std::string SourceFileName;
  
    /// The string identifier given to this module by the client, normally the
    /// path to the bitcode file.
    StringRef ModulePath;
  
    /// For per-module summary indexes, the unique numerical identifier given to
    /// this module by the client.
    unsigned ModuleId;
  
  public:
    ModuleSummaryIndexBitcodeReader(BitstreamCursor Stream, StringRef Strtab,
                                    ModuleSummaryIndex &TheIndex,
                                    StringRef ModulePath, unsigned ModuleId);
  
    Error parseModule();
  
  private:
    void setValueGUID(uint64_t ValueID, StringRef ValueName,
                      GlobalValue::LinkageTypes Linkage,
                      StringRef SourceFileName);
    Error parseValueSymbolTable(
        uint64_t Offset,
        DenseMap<unsigned, GlobalValue::LinkageTypes> &ValueIdToLinkageMap);
    std::vector<ValueInfo> makeRefList(ArrayRef<uint64_t> Record);
    std::vector<FunctionSummary::EdgeTy> makeCallList(ArrayRef<uint64_t> Record,
                                                      bool IsOldProfileFormat,
                                                      bool HasProfile,
                                                      bool HasRelBF);
    Error parseEntireSummary(unsigned ID);
    Error parseModuleStringTable();
    void parseTypeIdCompatibleVtableSummaryRecord(ArrayRef<uint64_t> Record);
    void parseTypeIdCompatibleVtableInfo(ArrayRef<uint64_t> Record, size_t &Slot,
                                         TypeIdCompatibleVtableInfo &TypeId);
  
    std::pair<ValueInfo, GlobalValue::GUID>
    getValueInfoFromValueId(unsigned ValueId);
  
    void addThisModule();
    ModuleSummaryIndex::ModuleInfo *getThisModule();
  };
  
  } // end anonymous namespace
  
  std::error_code llvm::errorToErrorCodeAndEmitErrors(LLVMContext &Ctx,
                                                      Error Err) {
    if (Err) {
      std::error_code EC;
      handleAllErrors(std::move(Err), [&](ErrorInfoBase &EIB) {
        EC = EIB.convertToErrorCode();
        Ctx.emitError(EIB.message());
      });
      return EC;
    }
    return std::error_code();
  }
  
  BitcodeReader::BitcodeReader(BitstreamCursor Stream, StringRef Strtab,
                               StringRef ProducerIdentification,
                               LLVMContext &Context)
      : BitcodeReaderBase(std::move(Stream), Strtab), Context(Context),
        ValueList(Context, Stream.SizeInBytes()) {
    this->ProducerIdentification = std::string(ProducerIdentification);
  }
  
  Error BitcodeReader::materializeForwardReferencedFunctions() {
    if (WillMaterializeAllForwardRefs)
      return Error::success();
  
    // Prevent recursion.
    WillMaterializeAllForwardRefs = true;
  
    while (!BasicBlockFwdRefQueue.empty()) {
      Function *F = BasicBlockFwdRefQueue.front();
      BasicBlockFwdRefQueue.pop_front();
      assert(F && "Expected valid function");
      if (!BasicBlockFwdRefs.count(F))
        // Already materialized.
        continue;
  
      // Check for a function that isn't materializable to prevent an infinite
      // loop.  When parsing a blockaddress stored in a global variable, there
      // isn't a trivial way to check if a function will have a body without a
      // linear search through FunctionsWithBodies, so just check it here.
      if (!F->isMaterializable())
        return error("Never resolved function from blockaddress");
  
      // Try to materialize F.
      if (Error Err = materialize(F))
        return Err;
    }
    assert(BasicBlockFwdRefs.empty() && "Function missing from queue");
  
    // Reset state.
    WillMaterializeAllForwardRefs = false;
    return Error::success();
  }
  
  //===----------------------------------------------------------------------===//
  //  Helper functions to implement forward reference resolution, etc.
  //===----------------------------------------------------------------------===//
  
  static bool hasImplicitComdat(size_t Val) {
    switch (Val) {
    default:
      return false;
    case 1:  // Old WeakAnyLinkage
    case 4:  // Old LinkOnceAnyLinkage
    case 10: // Old WeakODRLinkage
    case 11: // Old LinkOnceODRLinkage
      return true;
    }
  }
  
  static GlobalValue::LinkageTypes getDecodedLinkage(unsigned Val) {
    switch (Val) {
    default: // Map unknown/new linkages to external
    case 0:
      return GlobalValue::ExternalLinkage;
    case 2:
      return GlobalValue::AppendingLinkage;
    case 3:
      return GlobalValue::InternalLinkage;
    case 5:
      return GlobalValue::ExternalLinkage; // Obsolete DLLImportLinkage
    case 6:
      return GlobalValue::ExternalLinkage; // Obsolete DLLExportLinkage
    case 7:
      return GlobalValue::ExternalWeakLinkage;
    case 8:
      return GlobalValue::CommonLinkage;
    case 9:
      return GlobalValue::PrivateLinkage;
    case 12:
      return GlobalValue::AvailableExternallyLinkage;
    case 13:
      return GlobalValue::PrivateLinkage; // Obsolete LinkerPrivateLinkage
    case 14:
      return GlobalValue::PrivateLinkage; // Obsolete LinkerPrivateWeakLinkage
    case 15:
      return GlobalValue::ExternalLinkage; // Obsolete LinkOnceODRAutoHideLinkage
    case 1: // Old value with implicit comdat.
    case 16:
      return GlobalValue::WeakAnyLinkage;
    case 10: // Old value with implicit comdat.
    case 17:
      return GlobalValue::WeakODRLinkage;
    case 4: // Old value with implicit comdat.
    case 18:
      return GlobalValue::LinkOnceAnyLinkage;
    case 11: // Old value with implicit comdat.
    case 19:
      return GlobalValue::LinkOnceODRLinkage;
    }
  }
  
  static FunctionSummary::FFlags getDecodedFFlags(uint64_t RawFlags) {
    FunctionSummary::FFlags Flags;
    Flags.ReadNone = RawFlags & 0x1;
    Flags.ReadOnly = (RawFlags >> 1) & 0x1;
    Flags.NoRecurse = (RawFlags >> 2) & 0x1;
    Flags.ReturnDoesNotAlias = (RawFlags >> 3) & 0x1;
    Flags.NoInline = (RawFlags >> 4) & 0x1;
    Flags.AlwaysInline = (RawFlags >> 5) & 0x1;
    return Flags;
  }
  
  /// Decode the flags for GlobalValue in the summary.
  static GlobalValueSummary::GVFlags getDecodedGVSummaryFlags(uint64_t RawFlags,
                                                              uint64_t Version) {
    // Summary were not emitted before LLVM 3.9, we don't need to upgrade Linkage
    // like getDecodedLinkage() above. Any future change to the linkage enum and
    // to getDecodedLinkage() will need to be taken into account here as above.
    auto Linkage = GlobalValue::LinkageTypes(RawFlags & 0xF); // 4 bits
    RawFlags = RawFlags >> 4;
    bool NotEligibleToImport = (RawFlags & 0x1) || Version < 3;
    // The Live flag wasn't introduced until version 3. For dead stripping
    // to work correctly on earlier versions, we must conservatively treat all
    // values as live.
    bool Live = (RawFlags & 0x2) || Version < 3;
    bool Local = (RawFlags & 0x4);
    bool AutoHide = (RawFlags & 0x8);
  
    return GlobalValueSummary::GVFlags(Linkage, NotEligibleToImport, Live, Local, AutoHide);
  }
  
  // Decode the flags for GlobalVariable in the summary
  static GlobalVarSummary::GVarFlags getDecodedGVarFlags(uint64_t RawFlags) {
    return GlobalVarSummary::GVarFlags(
        (RawFlags & 0x1) ? true : false, (RawFlags & 0x2) ? true : false,
        (RawFlags & 0x4) ? true : false,
        (GlobalObject::VCallVisibility)(RawFlags >> 3));
  }
  
  static GlobalValue::VisibilityTypes getDecodedVisibility(unsigned Val) {
    switch (Val) {
    default: // Map unknown visibilities to default.
    case 0: return GlobalValue::DefaultVisibility;
    case 1: return GlobalValue::HiddenVisibility;
    case 2: return GlobalValue::ProtectedVisibility;
    }
  }
  
  static GlobalValue::DLLStorageClassTypes
  getDecodedDLLStorageClass(unsigned Val) {
    switch (Val) {
    default: // Map unknown values to default.
    case 0: return GlobalValue::DefaultStorageClass;
    case 1: return GlobalValue::DLLImportStorageClass;
    case 2: return GlobalValue::DLLExportStorageClass;
    }
  }
  
  static bool getDecodedDSOLocal(unsigned Val) {
    switch(Val) {
    default: // Map unknown values to preemptable.
    case 0:  return false;
    case 1:  return true;
    }
  }
  
  static GlobalVariable::ThreadLocalMode getDecodedThreadLocalMode(unsigned Val) {
    switch (Val) {
      case 0: return GlobalVariable::NotThreadLocal;
      default: // Map unknown non-zero value to general dynamic.
      case 1: return GlobalVariable::GeneralDynamicTLSModel;
      case 2: return GlobalVariable::LocalDynamicTLSModel;
      case 3: return GlobalVariable::InitialExecTLSModel;
      case 4: return GlobalVariable::LocalExecTLSModel;
    }
  }
  
  static GlobalVariable::UnnamedAddr getDecodedUnnamedAddrType(unsigned Val) {
    switch (Val) {
      default: // Map unknown to UnnamedAddr::None.
      case 0: return GlobalVariable::UnnamedAddr::None;
      case 1: return GlobalVariable::UnnamedAddr::Global;
      case 2: return GlobalVariable::UnnamedAddr::Local;
    }
  }
  
  static int getDecodedCastOpcode(unsigned Val) {
    switch (Val) {
    default: return -1;
    case bitc::CAST_TRUNC   : return Instruction::Trunc;
    case bitc::CAST_ZEXT    : return Instruction::ZExt;
    case bitc::CAST_SEXT    : return Instruction::SExt;
    case bitc::CAST_FPTOUI  : return Instruction::FPToUI;
    case bitc::CAST_FPTOSI  : return Instruction::FPToSI;
    case bitc::CAST_UITOFP  : return Instruction::UIToFP;
    case bitc::CAST_SITOFP  : return Instruction::SIToFP;
    case bitc::CAST_FPTRUNC : return Instruction::FPTrunc;
    case bitc::CAST_FPEXT   : return Instruction::FPExt;
    case bitc::CAST_PTRTOINT: return Instruction::PtrToInt;
    case bitc::CAST_INTTOPTR: return Instruction::IntToPtr;
    case bitc::CAST_BITCAST : return Instruction::BitCast;
    case bitc::CAST_ADDRSPACECAST: return Instruction::AddrSpaceCast;
    }
  }
  
  static int getDecodedUnaryOpcode(unsigned Val, Type *Ty) {
    bool IsFP = Ty->isFPOrFPVectorTy();
    // UnOps are only valid for int/fp or vector of int/fp types
    if (!IsFP && !Ty->isIntOrIntVectorTy())
      return -1;
  
    switch (Val) {
    default:
      return -1;
    case bitc::UNOP_FNEG:
      return IsFP ? Instruction::FNeg : -1;
    }
  }
  
  static int getDecodedBinaryOpcode(unsigned Val, Type *Ty) {
    bool IsFP = Ty->isFPOrFPVectorTy();
    // BinOps are only valid for int/fp or vector of int/fp types
    if (!IsFP && !Ty->isIntOrIntVectorTy())
      return -1;
  
    switch (Val) {
    default:
      return -1;
    case bitc::BINOP_ADD:
      return IsFP ? Instruction::FAdd : Instruction::Add;
    case bitc::BINOP_SUB:
      return IsFP ? Instruction::FSub : Instruction::Sub;
    case bitc::BINOP_MUL:
      return IsFP ? Instruction::FMul : Instruction::Mul;
    case bitc::BINOP_UDIV:
      return IsFP ? -1 : Instruction::UDiv;
    case bitc::BINOP_SDIV:
      return IsFP ? Instruction::FDiv : Instruction::SDiv;
    case bitc::BINOP_UREM:
      return IsFP ? -1 : Instruction::URem;
    case bitc::BINOP_SREM:
      return IsFP ? Instruction::FRem : Instruction::SRem;
    case bitc::BINOP_SHL:
      return IsFP ? -1 : Instruction::Shl;
    case bitc::BINOP_LSHR:
      return IsFP ? -1 : Instruction::LShr;
    case bitc::BINOP_ASHR:
      return IsFP ? -1 : Instruction::AShr;
    case bitc::BINOP_AND:
      return IsFP ? -1 : Instruction::And;
    case bitc::BINOP_OR:
      return IsFP ? -1 : Instruction::Or;
    case bitc::BINOP_XOR:
      return IsFP ? -1 : Instruction::Xor;
    }
  }
  
  static AtomicRMWInst::BinOp getDecodedRMWOperation(unsigned Val) {
    switch (Val) {
    default: return AtomicRMWInst::BAD_BINOP;
    case bitc::RMW_XCHG: return AtomicRMWInst::Xchg;
    case bitc::RMW_ADD: return AtomicRMWInst::Add;
    case bitc::RMW_SUB: return AtomicRMWInst::Sub;
    case bitc::RMW_AND: return AtomicRMWInst::And;
    case bitc::RMW_NAND: return AtomicRMWInst::Nand;
    case bitc::RMW_OR: return AtomicRMWInst::Or;
    case bitc::RMW_XOR: return AtomicRMWInst::Xor;
    case bitc::RMW_MAX: return AtomicRMWInst::Max;
    case bitc::RMW_MIN: return AtomicRMWInst::Min;
    case bitc::RMW_UMAX: return AtomicRMWInst::UMax;
    case bitc::RMW_UMIN: return AtomicRMWInst::UMin;
    case bitc::RMW_FADD: return AtomicRMWInst::FAdd;
    case bitc::RMW_FSUB: return AtomicRMWInst::FSub;
    }
  }
  
  static AtomicOrdering getDecodedOrdering(unsigned Val) {
    switch (Val) {
    case bitc::ORDERING_NOTATOMIC: return AtomicOrdering::NotAtomic;
    case bitc::ORDERING_UNORDERED: return AtomicOrdering::Unordered;
    case bitc::ORDERING_MONOTONIC: return AtomicOrdering::Monotonic;
    case bitc::ORDERING_ACQUIRE: return AtomicOrdering::Acquire;
    case bitc::ORDERING_RELEASE: return AtomicOrdering::Release;
    case bitc::ORDERING_ACQREL: return AtomicOrdering::AcquireRelease;
    default: // Map unknown orderings to sequentially-consistent.
    case bitc::ORDERING_SEQCST: return AtomicOrdering::SequentiallyConsistent;
    }
  }
  
  static Comdat::SelectionKind getDecodedComdatSelectionKind(unsigned Val) {
    switch (Val) {
    default: // Map unknown selection kinds to any.
    case bitc::COMDAT_SELECTION_KIND_ANY:
      return Comdat::Any;
    case bitc::COMDAT_SELECTION_KIND_EXACT_MATCH:
      return Comdat::ExactMatch;
    case bitc::COMDAT_SELECTION_KIND_LARGEST:
      return Comdat::Largest;
    case bitc::COMDAT_SELECTION_KIND_NO_DUPLICATES:
      return Comdat::NoDuplicates;
    case bitc::COMDAT_SELECTION_KIND_SAME_SIZE:
      return Comdat::SameSize;
    }
  }
  
  static FastMathFlags getDecodedFastMathFlags(unsigned Val) {
    FastMathFlags FMF;
    if (0 != (Val & bitc::UnsafeAlgebra))
      FMF.setFast();
    if (0 != (Val & bitc::AllowReassoc))
      FMF.setAllowReassoc();
    if (0 != (Val & bitc::NoNaNs))
      FMF.setNoNaNs();
    if (0 != (Val & bitc::NoInfs))
      FMF.setNoInfs();
    if (0 != (Val & bitc::NoSignedZeros))
      FMF.setNoSignedZeros();
    if (0 != (Val & bitc::AllowReciprocal))
      FMF.setAllowReciprocal();
    if (0 != (Val & bitc::AllowContract))
      FMF.setAllowContract(true);
    if (0 != (Val & bitc::ApproxFunc))
      FMF.setApproxFunc();
    return FMF;
  }
  
  static void upgradeDLLImportExportLinkage(GlobalValue *GV, unsigned Val) {
    switch (Val) {
    case 5: GV->setDLLStorageClass(GlobalValue::DLLImportStorageClass); break;
    case 6: GV->setDLLStorageClass(GlobalValue::DLLExportStorageClass); break;
    }
  }
  
  Type *BitcodeReader::getFullyStructuredTypeByID(unsigned ID) {
    // The type table size is always specified correctly.
    if (ID >= TypeList.size())
      return nullptr;
  
    if (Type *Ty = TypeList[ID])
      return Ty;
  
    // If we have a forward reference, the only possible case is when it is to a
    // named struct.  Just create a placeholder for now.
    return TypeList[ID] = createIdentifiedStructType(Context);
  }
  
  StructType *BitcodeReader::createIdentifiedStructType(LLVMContext &Context,
                                                        StringRef Name) {
    auto *Ret = StructType::create(Context, Name);
    IdentifiedStructTypes.push_back(Ret);
    return Ret;
  }
  
  StructType *BitcodeReader::createIdentifiedStructType(LLVMContext &Context) {
    auto *Ret = StructType::create(Context);
    IdentifiedStructTypes.push_back(Ret);
    return Ret;
  }
  
  //===----------------------------------------------------------------------===//
  //  Functions for parsing blocks from the bitcode file
  //===----------------------------------------------------------------------===//
  
  static uint64_t getRawAttributeMask(Attribute::AttrKind Val) {
    switch (Val) {
    case Attribute::EndAttrKinds:
    case Attribute::EmptyKey:
    case Attribute::TombstoneKey:
      llvm_unreachable("Synthetic enumerators which should never get here");
  
    case Attribute::None:            return 0;
    case Attribute::ZExt:            return 1 << 0;
    case Attribute::SExt:            return 1 << 1;
    case Attribute::NoReturn:        return 1 << 2;
    case Attribute::InReg:           return 1 << 3;
    case Attribute::StructRet:       return 1 << 4;
    case Attribute::NoUnwind:        return 1 << 5;
    case Attribute::NoAlias:         return 1 << 6;
    case Attribute::ByVal:           return 1 << 7;
    case Attribute::Nest:            return 1 << 8;
    case Attribute::ReadNone:        return 1 << 9;
    case Attribute::ReadOnly:        return 1 << 10;
    case Attribute::NoInline:        return 1 << 11;
    case Attribute::AlwaysInline:    return 1 << 12;
    case Attribute::OptimizeForSize: return 1 << 13;
    case Attribute::StackProtect:    return 1 << 14;
    case Attribute::StackProtectReq: return 1 << 15;
    case Attribute::Alignment:       return 31 << 16;
    case Attribute::NoCapture:       return 1 << 21;
    case Attribute::NoRedZone:       return 1 << 22;
    case Attribute::NoImplicitFloat: return 1 << 23;
    case Attribute::Naked:           return 1 << 24;
    case Attribute::InlineHint:      return 1 << 25;
    case Attribute::StackAlignment:  return 7 << 26;
    case Attribute::ReturnsTwice:    return 1 << 29;
    case Attribute::UWTable:         return 1 << 30;
    case Attribute::NonLazyBind:     return 1U << 31;
    case Attribute::SanitizeAddress: return 1ULL << 32;
    case Attribute::MinSize:         return 1ULL << 33;
    case Attribute::NoDuplicate:     return 1ULL << 34;
    case Attribute::StackProtectStrong: return 1ULL << 35;
    case Attribute::SanitizeThread:  return 1ULL << 36;
    case Attribute::SanitizeMemory:  return 1ULL << 37;
    case Attribute::NoBuiltin:       return 1ULL << 38;
    case Attribute::Returned:        return 1ULL << 39;
    case Attribute::Cold:            return 1ULL << 40;
    case Attribute::Builtin:         return 1ULL << 41;
    case Attribute::OptimizeNone:    return 1ULL << 42;
    case Attribute::InAlloca:        return 1ULL << 43;
    case Attribute::NonNull:         return 1ULL << 44;
    case Attribute::JumpTable:       return 1ULL << 45;
    case Attribute::Convergent:      return 1ULL << 46;
    case Attribute::SafeStack:       return 1ULL << 47;
    case Attribute::NoRecurse:       return 1ULL << 48;
    case Attribute::InaccessibleMemOnly:         return 1ULL << 49;
    case Attribute::InaccessibleMemOrArgMemOnly: return 1ULL << 50;
    case Attribute::SwiftSelf:       return 1ULL << 51;
    case Attribute::SwiftError:      return 1ULL << 52;
    case Attribute::WriteOnly:       return 1ULL << 53;
    case Attribute::Speculatable:    return 1ULL << 54;
    case Attribute::StrictFP:        return 1ULL << 55;
    case Attribute::SanitizeHWAddress: return 1ULL << 56;
    case Attribute::NoCfCheck:       return 1ULL << 57;
    case Attribute::OptForFuzzing:   return 1ULL << 58;
    case Attribute::ShadowCallStack: return 1ULL << 59;
    case Attribute::SpeculativeLoadHardening:
      return 1ULL << 60;
    case Attribute::ImmArg:
      return 1ULL << 61;
    case Attribute::WillReturn:
      return 1ULL << 62;
    case Attribute::NoFree:
      return 1ULL << 63;
    default:
      // Other attributes are not supported in the raw format,
      // as we ran out of space.
      return 0;
    }
    llvm_unreachable("Unsupported attribute type");
  }
  
  static void addRawAttributeValue(AttrBuilder &B, uint64_t Val) {
    if (!Val) return;
  
    for (Attribute::AttrKind I = Attribute::None; I != Attribute::EndAttrKinds;
         I = Attribute::AttrKind(I + 1)) {
      if (uint64_t A = (Val & getRawAttributeMask(I))) {
        if (I == Attribute::Alignment)
          B.addAlignmentAttr(1ULL << ((A >> 16) - 1));
        else if (I == Attribute::StackAlignment)
          B.addStackAlignmentAttr(1ULL << ((A >> 26)-1));
        else
          B.addAttribute(I);
      }
    }
  }
  
  /// This fills an AttrBuilder object with the LLVM attributes that have
  /// been decoded from the given integer. This function must stay in sync with
  /// 'encodeLLVMAttributesForBitcode'.
  static void decodeLLVMAttributesForBitcode(AttrBuilder &B,
                                             uint64_t EncodedAttrs) {
    // The alignment is stored as a 16-bit raw value from bits 31--16.  We shift
    // the bits above 31 down by 11 bits.
    unsigned Alignment = (EncodedAttrs & (0xffffULL << 16)) >> 16;
    assert((!Alignment || isPowerOf2_32(Alignment)) &&
           "Alignment must be a power of two.");
  
    if (Alignment)
      B.addAlignmentAttr(Alignment);
    addRawAttributeValue(B, ((EncodedAttrs & (0xfffffULL << 32)) >> 11) |
                            (EncodedAttrs & 0xffff));
  }
  
  Error BitcodeReader::parseAttributeBlock() {
    if (Error Err = Stream.EnterSubBlock(bitc::PARAMATTR_BLOCK_ID))
      return Err;
  
    if (!MAttributes.empty())
      return error("Invalid multiple blocks");
  
    SmallVector<uint64_t, 64> Record;
  
    SmallVector<AttributeList, 8> Attrs;
  
    // Read all the records.
    while (true) {
      Expected<BitstreamEntry> MaybeEntry = Stream.advanceSkippingSubblocks();
      if (!MaybeEntry)
        return MaybeEntry.takeError();
      BitstreamEntry Entry = MaybeEntry.get();
  
      switch (Entry.Kind) {
      case BitstreamEntry::SubBlock: // Handled for us already.
      case BitstreamEntry::Error:
        return error("Malformed block");
      case BitstreamEntry::EndBlock:
        return Error::success();
      case BitstreamEntry::Record:
        // The interesting case.
        break;
      }
  
      // Read a record.
      Record.clear();
      Expected<unsigned> MaybeRecord = Stream.readRecord(Entry.ID, Record);
      if (!MaybeRecord)
        return MaybeRecord.takeError();
      switch (MaybeRecord.get()) {
      default:  // Default behavior: ignore.
        break;
      case bitc::PARAMATTR_CODE_ENTRY_OLD: // ENTRY: [paramidx0, attr0, ...]
        // Deprecated, but still needed to read old bitcode files.
        if (Record.size() & 1)
          return error("Invalid record");
  
        for (unsigned i = 0, e = Record.size(); i != e; i += 2) {
          AttrBuilder B;
          decodeLLVMAttributesForBitcode(B, Record[i+1]);
          Attrs.push_back(AttributeList::get(Context, Record[i], B));
        }
  
        MAttributes.push_back(AttributeList::get(Context, Attrs));
        Attrs.clear();
        break;
      case bitc::PARAMATTR_CODE_ENTRY: // ENTRY: [attrgrp0, attrgrp1, ...]
        for (unsigned i = 0, e = Record.size(); i != e; ++i)
          Attrs.push_back(MAttributeGroups[Record[i]]);
  
        MAttributes.push_back(AttributeList::get(Context, Attrs));
        Attrs.clear();
        break;
      }
    }
  }
  
  // Returns Attribute::None on unrecognized codes.
  static Attribute::AttrKind getAttrFromCode(uint64_t Code) {
    switch (Code) {
    default:
      return Attribute::None;
    case bitc::ATTR_KIND_ALIGNMENT:
      return Attribute::Alignment;
    case bitc::ATTR_KIND_ALWAYS_INLINE:
      return Attribute::AlwaysInline;
    case bitc::ATTR_KIND_ARGMEMONLY:
      return Attribute::ArgMemOnly;
    case bitc::ATTR_KIND_BUILTIN:
      return Attribute::Builtin;
    case bitc::ATTR_KIND_BY_VAL:
      return Attribute::ByVal;
    case bitc::ATTR_KIND_IN_ALLOCA:
      return Attribute::InAlloca;
    case bitc::ATTR_KIND_COLD:
      return Attribute::Cold;
    case bitc::ATTR_KIND_CONVERGENT:
      return Attribute::Convergent;
    case bitc::ATTR_KIND_INACCESSIBLEMEM_ONLY:
      return Attribute::InaccessibleMemOnly;
    case bitc::ATTR_KIND_INACCESSIBLEMEM_OR_ARGMEMONLY:
      return Attribute::InaccessibleMemOrArgMemOnly;
    case bitc::ATTR_KIND_INLINE_HINT:
      return Attribute::InlineHint;
    case bitc::ATTR_KIND_IN_REG:
      return Attribute::InReg;
    case bitc::ATTR_KIND_JUMP_TABLE:
      return Attribute::JumpTable;
    case bitc::ATTR_KIND_MIN_SIZE:
      return Attribute::MinSize;
    case bitc::ATTR_KIND_NAKED:
      return Attribute::Naked;
    case bitc::ATTR_KIND_NEST:
      return Attribute::Nest;
    case bitc::ATTR_KIND_NO_ALIAS:
      return Attribute::NoAlias;
    case bitc::ATTR_KIND_NO_BUILTIN:
      return Attribute::NoBuiltin;
    case bitc::ATTR_KIND_NO_CAPTURE:
      return Attribute::NoCapture;
    case bitc::ATTR_KIND_NO_DUPLICATE:
      return Attribute::NoDuplicate;
    case bitc::ATTR_KIND_NOFREE:
      return Attribute::NoFree;
    case bitc::ATTR_KIND_NO_IMPLICIT_FLOAT:
      return Attribute::NoImplicitFloat;
    case bitc::ATTR_KIND_NO_INLINE:
      return Attribute::NoInline;
    case bitc::ATTR_KIND_NO_RECURSE:
      return Attribute::NoRecurse;
    case bitc::ATTR_KIND_NO_MERGE:
      return Attribute::NoMerge;
    case bitc::ATTR_KIND_NON_LAZY_BIND:
      return Attribute::NonLazyBind;
    case bitc::ATTR_KIND_NON_NULL:
      return Attribute::NonNull;
    case bitc::ATTR_KIND_DEREFERENCEABLE:
      return Attribute::Dereferenceable;
    case bitc::ATTR_KIND_DEREFERENCEABLE_OR_NULL:
      return Attribute::DereferenceableOrNull;
    case bitc::ATTR_KIND_ALLOC_SIZE:
      return Attribute::AllocSize;
    case bitc::ATTR_KIND_NO_RED_ZONE:
      return Attribute::NoRedZone;
    case bitc::ATTR_KIND_NO_RETURN:
      return Attribute::NoReturn;
    case bitc::ATTR_KIND_NOSYNC:
      return Attribute::NoSync;
    case bitc::ATTR_KIND_NOCF_CHECK:
      return Attribute::NoCfCheck;
    case bitc::ATTR_KIND_NO_UNWIND:
      return Attribute::NoUnwind;
    case bitc::ATTR_KIND_NULL_POINTER_IS_VALID:
      return Attribute::NullPointerIsValid;
    case bitc::ATTR_KIND_OPT_FOR_FUZZING:
      return Attribute::OptForFuzzing;
    case bitc::ATTR_KIND_OPTIMIZE_FOR_SIZE:
      return Attribute::OptimizeForSize;
    case bitc::ATTR_KIND_OPTIMIZE_NONE:
      return Attribute::OptimizeNone;
    case bitc::ATTR_KIND_READ_NONE:
      return Attribute::ReadNone;
    case bitc::ATTR_KIND_READ_ONLY:
      return Attribute::ReadOnly;
    case bitc::ATTR_KIND_RETURNED:
      return Attribute::Returned;
    case bitc::ATTR_KIND_RETURNS_TWICE:
      return Attribute::ReturnsTwice;
    case bitc::ATTR_KIND_S_EXT:
      return Attribute::SExt;
    case bitc::ATTR_KIND_SPECULATABLE:
      return Attribute::Speculatable;
    case bitc::ATTR_KIND_STACK_ALIGNMENT:
      return Attribute::StackAlignment;
    case bitc::ATTR_KIND_STACK_PROTECT:
      return Attribute::StackProtect;
    case bitc::ATTR_KIND_STACK_PROTECT_REQ:
      return Attribute::StackProtectReq;
    case bitc::ATTR_KIND_STACK_PROTECT_STRONG:
      return Attribute::StackProtectStrong;
    case bitc::ATTR_KIND_SAFESTACK:
      return Attribute::SafeStack;
    case bitc::ATTR_KIND_SHADOWCALLSTACK:
      return Attribute::ShadowCallStack;
    case bitc::ATTR_KIND_STRICT_FP:
      return Attribute::StrictFP;
    case bitc::ATTR_KIND_STRUCT_RET:
      return Attribute::StructRet;
    case bitc::ATTR_KIND_SANITIZE_ADDRESS:
      return Attribute::SanitizeAddress;
    case bitc::ATTR_KIND_SANITIZE_HWADDRESS:
      return Attribute::SanitizeHWAddress;
    case bitc::ATTR_KIND_SANITIZE_THREAD:
      return Attribute::SanitizeThread;
    case bitc::ATTR_KIND_SANITIZE_MEMORY:
      return Attribute::SanitizeMemory;
    case bitc::ATTR_KIND_SPECULATIVE_LOAD_HARDENING:
      return Attribute::SpeculativeLoadHardening;
    case bitc::ATTR_KIND_SWIFT_ERROR:
      return Attribute::SwiftError;
    case bitc::ATTR_KIND_SWIFT_SELF:
      return Attribute::SwiftSelf;
    case bitc::ATTR_KIND_UW_TABLE:
      return Attribute::UWTable;
    case bitc::ATTR_KIND_WILLRETURN:
      return Attribute::WillReturn;
    case bitc::ATTR_KIND_WRITEONLY:
      return Attribute::WriteOnly;
    case bitc::ATTR_KIND_Z_EXT:
      return Attribute::ZExt;
    case bitc::ATTR_KIND_IMMARG:
      return Attribute::ImmArg;
    case bitc::ATTR_KIND_SANITIZE_MEMTAG:
      return Attribute::SanitizeMemTag;
    case bitc::ATTR_KIND_PREALLOCATED:
      return Attribute::Preallocated;
    case bitc::ATTR_KIND_NOUNDEF:
      return Attribute::NoUndef;
    case bitc::ATTR_KIND_BYREF:
      return Attribute::ByRef;
    }
  }
  
  Error BitcodeReader::parseAlignmentValue(uint64_t Exponent,
                                           MaybeAlign &Alignment) {
    // Note: Alignment in bitcode files is incremented by 1, so that zero
    // can be used for default alignment.
    if (Exponent > Value::MaxAlignmentExponent + 1)
      return error("Invalid alignment value");
    Alignment = decodeMaybeAlign(Exponent);
    return Error::success();
  }
  
  Error BitcodeReader::parseAttrKind(uint64_t Code, Attribute::AttrKind *Kind) {
    *Kind = getAttrFromCode(Code);
    if (*Kind == Attribute::None)
      return error("Unknown attribute kind (" + Twine(Code) + ")");
    return Error::success();
  }
  
  Error BitcodeReader::parseAttributeGroupBlock() {
    if (Error Err = Stream.EnterSubBlock(bitc::PARAMATTR_GROUP_BLOCK_ID))
      return Err;
  
    if (!MAttributeGroups.empty())
      return error("Invalid multiple blocks");
  
    SmallVector<uint64_t, 64> Record;
  
    // Read all the records.
    while (true) {
      Expected<BitstreamEntry> MaybeEntry = Stream.advanceSkippingSubblocks();
      if (!MaybeEntry)
        return MaybeEntry.takeError();
      BitstreamEntry Entry = MaybeEntry.get();
  
      switch (Entry.Kind) {
      case BitstreamEntry::SubBlock: // Handled for us already.
      case BitstreamEntry::Error:
        return error("Malformed block");
      case BitstreamEntry::EndBlock:
        return Error::success();
      case BitstreamEntry::Record:
        // The interesting case.
        break;
      }
  
      // Read a record.
      Record.clear();
      Expected<unsigned> MaybeRecord = Stream.readRecord(Entry.ID, Record);
      if (!MaybeRecord)
        return MaybeRecord.takeError();
      switch (MaybeRecord.get()) {
      default:  // Default behavior: ignore.
        break;
      case bitc::PARAMATTR_GRP_CODE_ENTRY: { // ENTRY: [grpid, idx, a0, a1, ...]
        if (Record.size() < 3)
          return error("Invalid record");
  
        uint64_t GrpID = Record[0];
        uint64_t Idx = Record[1]; // Index of the object this attribute refers to.
  
        AttrBuilder B;
        for (unsigned i = 2, e = Record.size(); i != e; ++i) {
          if (Record[i] == 0) {        // Enum attribute
            Attribute::AttrKind Kind;
            if (Error Err = parseAttrKind(Record[++i], &Kind))
              return Err;
  
            // Upgrade old-style byval attribute to one with a type, even if it's
            // nullptr. We will have to insert the real type when we associate
            // this AttributeList with a function.
            if (Kind == Attribute::ByVal)
              B.addByValAttr(nullptr);
  
            B.addAttribute(Kind);
          } else if (Record[i] == 1) { // Integer attribute
            Attribute::AttrKind Kind;
            if (Error Err = parseAttrKind(Record[++i], &Kind))
              return Err;
            if (Kind == Attribute::Alignment)
              B.addAlignmentAttr(Record[++i]);
            else if (Kind == Attribute::StackAlignment)
              B.addStackAlignmentAttr(Record[++i]);
            else if (Kind == Attribute::Dereferenceable)
              B.addDereferenceableAttr(Record[++i]);
            else if (Kind == Attribute::DereferenceableOrNull)
              B.addDereferenceableOrNullAttr(Record[++i]);
            else if (Kind == Attribute::AllocSize)
              B.addAllocSizeAttrFromRawRepr(Record[++i]);
          } else if (Record[i] == 3 || Record[i] == 4) { // String attribute
            bool HasValue = (Record[i++] == 4);
            SmallString<64> KindStr;
            SmallString<64> ValStr;
  
            while (Record[i] != 0 && i != e)
              KindStr += Record[i++];
            assert(Record[i] == 0 && "Kind string not null terminated");
  
            if (HasValue) {
              // Has a value associated with it.
              ++i; // Skip the '0' that terminates the "kind" string.
              while (Record[i] != 0 && i != e)
                ValStr += Record[i++];
              assert(Record[i] == 0 && "Value string not null terminated");
            }
  
            B.addAttribute(KindStr.str(), ValStr.str());
          } else {
            assert((Record[i] == 5 || Record[i] == 6) &&
                   "Invalid attribute group entry");
            bool HasType = Record[i] == 6;
            Attribute::AttrKind Kind;
            if (Error Err = parseAttrKind(Record[++i], &Kind))
              return Err;
            if (Kind == Attribute::ByVal) {
              B.addByValAttr(HasType ? getTypeByID(Record[++i]) : nullptr);
            } else if (Kind == Attribute::ByRef) {
              B.addByRefAttr(getTypeByID(Record[++i]));
            } else if (Kind == Attribute::Preallocated) {
              B.addPreallocatedAttr(getTypeByID(Record[++i]));
            }
          }
        }
  
        UpgradeAttributes(B);
        MAttributeGroups[GrpID] = AttributeList::get(Context, Idx, B);
        break;
      }
      }
    }
  }
  
  Error BitcodeReader::parseTypeTable() {
    if (Error Err = Stream.EnterSubBlock(bitc::TYPE_BLOCK_ID_NEW))
      return Err;
  
    return parseTypeTableBody();
  }
  
  Error BitcodeReader::parseTypeTableBody() {
    if (!TypeList.empty())
      return error("Invalid multiple blocks");
  
    SmallVector<uint64_t, 64> Record;
    unsigned NumRecords = 0;
  
    SmallString<64> TypeName;
  
    // Read all the records for this type table.
    while (true) {
      Expected<BitstreamEntry> MaybeEntry = Stream.advanceSkippingSubblocks();
      if (!MaybeEntry)
        return MaybeEntry.takeError();
      BitstreamEntry Entry = MaybeEntry.get();
  
      switch (Entry.Kind) {
      case BitstreamEntry::SubBlock: // Handled for us already.
      case BitstreamEntry::Error:
        return error("Malformed block");
      case BitstreamEntry::EndBlock:
        if (NumRecords != TypeList.size())
          return error("Malformed block");
        return Error::success();
      case BitstreamEntry::Record:
        // The interesting case.
        break;
      }
  
      // Read a record.
      Record.clear();
      Type *ResultTy = nullptr;
      Expected<unsigned> MaybeRecord = Stream.readRecord(Entry.ID, Record);
      if (!MaybeRecord)
        return MaybeRecord.takeError();
      switch (MaybeRecord.get()) {
      default:
        return error("Invalid value");
      case bitc::TYPE_CODE_NUMENTRY: // TYPE_CODE_NUMENTRY: [numentries]
        // TYPE_CODE_NUMENTRY contains a count of the number of types in the
        // type list.  This allows us to reserve space.
        if (Record.empty())
          return error("Invalid record");
        TypeList.resize(Record[0]);
        continue;
      case bitc::TYPE_CODE_VOID:      // VOID
        ResultTy = Type::getVoidTy(Context);
        break;
      case bitc::TYPE_CODE_HALF:     // HALF
        ResultTy = Type::getHalfTy(Context);
        break;
      case bitc::TYPE_CODE_BFLOAT:    // BFLOAT
        ResultTy = Type::getBFloatTy(Context);
        break;
      case bitc::TYPE_CODE_FLOAT:     // FLOAT
        ResultTy = Type::getFloatTy(Context);
        break;
      case bitc::TYPE_CODE_DOUBLE:    // DOUBLE
        ResultTy = Type::getDoubleTy(Context);
        break;
      case bitc::TYPE_CODE_X86_FP80:  // X86_FP80
        ResultTy = Type::getX86_FP80Ty(Context);
        break;
      case bitc::TYPE_CODE_FP128:     // FP128
        ResultTy = Type::getFP128Ty(Context);
        break;
      case bitc::TYPE_CODE_PPC_FP128: // PPC_FP128
        ResultTy = Type::getPPC_FP128Ty(Context);
        break;
      case bitc::TYPE_CODE_LABEL:     // LABEL
        ResultTy = Type::getLabelTy(Context);
        break;
      case bitc::TYPE_CODE_METADATA:  // METADATA
        ResultTy = Type::getMetadataTy(Context);
        break;
      case bitc::TYPE_CODE_X86_MMX:   // X86_MMX
        ResultTy = Type::getX86_MMXTy(Context);
        break;
      case bitc::TYPE_CODE_TOKEN:     // TOKEN
        ResultTy = Type::getTokenTy(Context);
        break;
      case bitc::TYPE_CODE_INTEGER: { // INTEGER: [width]
        if (Record.empty())
          return error("Invalid record");
  
        uint64_t NumBits = Record[0];
        if (NumBits < IntegerType::MIN_INT_BITS ||
            NumBits > IntegerType::MAX_INT_BITS)
          return error("Bitwidth for integer type out of range");
        ResultTy = IntegerType::get(Context, NumBits);
        break;
      }
      case bitc::TYPE_CODE_POINTER: { // POINTER: [pointee type] or
                                      //          [pointee type, address space]
        if (Record.empty())
          return error("Invalid record");
        unsigned AddressSpace = 0;
        if (Record.size() == 2)
          AddressSpace = Record[1];
        ResultTy = getTypeByID(Record[0]);
        if (!ResultTy ||
            !PointerType::isValidElementType(ResultTy))
          return error("Invalid type");
        ResultTy = PointerType::get(ResultTy, AddressSpace);
        break;
      }
      case bitc::TYPE_CODE_FUNCTION_OLD: {
        // Deprecated, but still needed to read old bitcode files.
        // FUNCTION: [vararg, attrid, retty, paramty x N]
        if (Record.size() < 3)
          return error("Invalid record");
        SmallVector<Type*, 8> ArgTys;
        for (unsigned i = 3, e = Record.size(); i != e; ++i) {
          if (Type *T = getTypeByID(Record[i]))
            ArgTys.push_back(T);
          else
            break;
        }
  
        ResultTy = getTypeByID(Record[2]);
        if (!ResultTy || ArgTys.size() < Record.size()-3)
          return error("Invalid type");
  
        ResultTy = FunctionType::get(ResultTy, ArgTys, Record[0]);
        break;
      }
      case bitc::TYPE_CODE_FUNCTION: {
        // FUNCTION: [vararg, retty, paramty x N]
        if (Record.size() < 2)
          return error("Invalid record");
        SmallVector<Type*, 8> ArgTys;
        for (unsigned i = 2, e = Record.size(); i != e; ++i) {
          if (Type *T = getTypeByID(Record[i])) {
            if (!FunctionType::isValidArgumentType(T))
              return error("Invalid function argument type");
            ArgTys.push_back(T);
          }
          else
            break;
        }
  
        ResultTy = getTypeByID(Record[1]);
        if (!ResultTy || ArgTys.size() < Record.size()-2)
          return error("Invalid type");
  
        ResultTy = FunctionType::get(ResultTy, ArgTys, Record[0]);
        break;
      }
      case bitc::TYPE_CODE_STRUCT_ANON: {  // STRUCT: [ispacked, eltty x N]
        if (Record.empty())
          return error("Invalid record");
        SmallVector<Type*, 8> EltTys;
        for (unsigned i = 1, e = Record.size(); i != e; ++i) {
          if (Type *T = getTypeByID(Record[i]))
            EltTys.push_back(T);
          else
            break;
        }
        if (EltTys.size() != Record.size()-1)
          return error("Invalid type");
        ResultTy = StructType::get(Context, EltTys, Record[0]);
        break;
      }
      case bitc::TYPE_CODE_STRUCT_NAME:   // STRUCT_NAME: [strchr x N]
        if (convertToString(Record, 0, TypeName))
          return error("Invalid record");
        continue;
  
      case bitc::TYPE_CODE_STRUCT_NAMED: { // STRUCT: [ispacked, eltty x N]
        if (Record.empty())
          return error("Invalid record");
  
        if (NumRecords >= TypeList.size())
          return error("Invalid TYPE table");
  
        // Check to see if this was forward referenced, if so fill in the temp.
        StructType *Res = cast_or_null<StructType>(TypeList[NumRecords]);
        if (Res) {
          Res->setName(TypeName);
          TypeList[NumRecords] = nullptr;
        } else  // Otherwise, create a new struct.
          Res = createIdentifiedStructType(Context, TypeName);
        TypeName.clear();
  
        SmallVector<Type*, 8> EltTys;
        for (unsigned i = 1, e = Record.size(); i != e; ++i) {
          if (Type *T = getTypeByID(Record[i]))
            EltTys.push_back(T);
          else
            break;
        }
        if (EltTys.size() != Record.size()-1)
          return error("Invalid record");
        Res->setBody(EltTys, Record[0]);
        ResultTy = Res;
        break;
      }
      case bitc::TYPE_CODE_OPAQUE: {       // OPAQUE: []
        if (Record.size() != 1)
          return error("Invalid record");
  
        if (NumRecords >= TypeList.size())
          return error("Invalid TYPE table");
  
        // Check to see if this was forward referenced, if so fill in the temp.
        StructType *Res = cast_or_null<StructType>(TypeList[NumRecords]);
        if (Res) {
          Res->setName(TypeName);
          TypeList[NumRecords] = nullptr;
        } else  // Otherwise, create a new struct with no body.
          Res = createIdentifiedStructType(Context, TypeName);
        TypeName.clear();
        ResultTy = Res;
        break;
      }
      case bitc::TYPE_CODE_ARRAY:     // ARRAY: [numelts, eltty]
        if (Record.size() < 2)
          return error("Invalid record");
        ResultTy = getTypeByID(Record[1]);
        if (!ResultTy || !ArrayType::isValidElementType(ResultTy))
          return error("Invalid type");
        ResultTy = ArrayType::get(ResultTy, Record[0]);
        break;
      case bitc::TYPE_CODE_VECTOR:    // VECTOR: [numelts, eltty] or
                                      //         [numelts, eltty, scalable]
        if (Record.size() < 2)
          return error("Invalid record");
        if (Record[0] == 0)
          return error("Invalid vector length");
        ResultTy = getTypeByID(Record[1]);
        if (!ResultTy || !StructType::isValidElementType(ResultTy))
          return error("Invalid type");
        bool Scalable = Record.size() > 2 ? Record[2] : false;
        ResultTy = VectorType::get(ResultTy, Record[0], Scalable);
        break;
      }
  
      if (NumRecords >= TypeList.size())
        return error("Invalid TYPE table");
      if (TypeList[NumRecords])
        return error(
            "Invalid TYPE table: Only named structs can be forward referenced");
      assert(ResultTy && "Didn't read a type?");
      TypeList[NumRecords++] = ResultTy;
    }
  }
  
  Error BitcodeReader::parseOperandBundleTags() {
    if (Error Err = Stream.EnterSubBlock(bitc::OPERAND_BUNDLE_TAGS_BLOCK_ID))
      return Err;
  
    if (!BundleTags.empty())
      return error("Invalid multiple blocks");
  
    SmallVector<uint64_t, 64> Record;
  
    while (true) {
      Expected<BitstreamEntry> MaybeEntry = Stream.advanceSkippingSubblocks();
      if (!MaybeEntry)
        return MaybeEntry.takeError();
      BitstreamEntry Entry = MaybeEntry.get();
  
      switch (Entry.Kind) {
      case BitstreamEntry::SubBlock: // Handled for us already.
      case BitstreamEntry::Error:
        return error("Malformed block");
      case BitstreamEntry::EndBlock:
        return Error::success();
      case BitstreamEntry::Record:
        // The interesting case.
        break;
      }
  
      // Tags are implicitly mapped to integers by their order.
  
      Expected<unsigned> MaybeRecord = Stream.readRecord(Entry.ID, Record);
      if (!MaybeRecord)
        return MaybeRecord.takeError();
      if (MaybeRecord.get() != bitc::OPERAND_BUNDLE_TAG)
        return error("Invalid record");
  
      // OPERAND_BUNDLE_TAG: [strchr x N]
      BundleTags.emplace_back();
      if (convertToString(Record, 0, BundleTags.back()))
        return error("Invalid record");
      Record.clear();
    }
  }
  
  Error BitcodeReader::parseSyncScopeNames() {
    if (Error Err = Stream.EnterSubBlock(bitc::SYNC_SCOPE_NAMES_BLOCK_ID))
      return Err;
  
    if (!SSIDs.empty())
      return error("Invalid multiple synchronization scope names blocks");
  
    SmallVector<uint64_t, 64> Record;
    while (true) {
      Expected<BitstreamEntry> MaybeEntry = Stream.advanceSkippingSubblocks();
      if (!MaybeEntry)
        return MaybeEntry.takeError();
      BitstreamEntry Entry = MaybeEntry.get();
  
      switch (Entry.Kind) {
      case BitstreamEntry::SubBlock: // Handled for us already.
      case BitstreamEntry::Error:
        return error("Malformed block");
      case BitstreamEntry::EndBlock:
        if (SSIDs.empty())
          return error("Invalid empty synchronization scope names block");
        return Error::success();
      case BitstreamEntry::Record:
        // The interesting case.
        break;
      }
  
      // Synchronization scope names are implicitly mapped to synchronization
      // scope IDs by their order.
  
      Expected<unsigned> MaybeRecord = Stream.readRecord(Entry.ID, Record);
      if (!MaybeRecord)
        return MaybeRecord.takeError();
      if (MaybeRecord.get() != bitc::SYNC_SCOPE_NAME)
        return error("Invalid record");
  
      SmallString<16> SSN;
      if (convertToString(Record, 0, SSN))
        return error("Invalid record");
  
      SSIDs.push_back(Context.getOrInsertSyncScopeID(SSN));
      Record.clear();
    }
  }
  
  /// Associate a value with its name from the given index in the provided record.
  Expected<Value *> BitcodeReader::recordValue(SmallVectorImpl<uint64_t> &Record,
                                               unsigned NameIndex, Triple &TT) {
    SmallString<128> ValueName;
    if (convertToString(Record, NameIndex, ValueName))
      return error("Invalid record");
    unsigned ValueID = Record[0];
    if (ValueID >= ValueList.size() || !ValueList[ValueID])
      return error("Invalid record");
    Value *V = ValueList[ValueID];
  
    StringRef NameStr(ValueName.data(), ValueName.size());
    if (NameStr.find_first_of(0) != StringRef::npos)
      return error("Invalid value name");
    V->setName(NameStr);
    auto *GO = dyn_cast<GlobalObject>(V);
    if (GO) {
      if (GO->getComdat() == reinterpret_cast<Comdat *>(1)) {
        if (TT.supportsCOMDAT())
          GO->setComdat(TheModule->getOrInsertComdat(V->getName()));
        else
          GO->setComdat(nullptr);
      }
    }
    return V;
  }
  
  /// Helper to note and return the current location, and jump to the given
  /// offset.
  static Expected<uint64_t> jumpToValueSymbolTable(uint64_t Offset,
                                                   BitstreamCursor &Stream) {
    // Save the current parsing location so we can jump back at the end
    // of the VST read.
    uint64_t CurrentBit = Stream.GetCurrentBitNo();
    if (Error JumpFailed = Stream.JumpToBit(Offset * 32))
      return std::move(JumpFailed);
    Expected<BitstreamEntry> MaybeEntry = Stream.advance();
    if (!MaybeEntry)
      return MaybeEntry.takeError();
    assert(MaybeEntry.get().Kind == BitstreamEntry::SubBlock);
    assert(MaybeEntry.get().ID == bitc::VALUE_SYMTAB_BLOCK_ID);
    return CurrentBit;
  }
  
  void BitcodeReader::setDeferredFunctionInfo(unsigned FuncBitcodeOffsetDelta,
                                              Function *F,
                                              ArrayRef<uint64_t> 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
    // historically always the start of the regular bitcode header.
    uint64_t FuncWordOffset = Record[1] - 1;
    uint64_t FuncBitOffset = FuncWordOffset * 32;
    DeferredFunctionInfo[F] = FuncBitOffset + FuncBitcodeOffsetDelta;
    // Set the LastFunctionBlockBit to point to the last function block.
    // Later when parsing is resumed after function materialization,
    // we can simply skip that last function block.
    if (FuncBitOffset > LastFunctionBlockBit)
      LastFunctionBlockBit = FuncBitOffset;
  }
  
  /// Read a new-style GlobalValue symbol table.
  Error BitcodeReader::parseGlobalValueSymbolTable() {
    unsigned FuncBitcodeOffsetDelta =
        Stream.getAbbrevIDWidth() + bitc::BlockIDWidth;
  
    if (Error Err = Stream.EnterSubBlock(bitc::VALUE_SYMTAB_BLOCK_ID))
      return Err;
  
    SmallVector<uint64_t, 64> Record;
    while (true) {
      Expected<BitstreamEntry> MaybeEntry = Stream.advanceSkippingSubblocks();
      if (!MaybeEntry)
        return MaybeEntry.takeError();
      BitstreamEntry Entry = MaybeEntry.get();
  
      switch (Entry.Kind) {
      case BitstreamEntry::SubBlock:
      case BitstreamEntry::Error:
        return error("Malformed block");
      case BitstreamEntry::EndBlock:
        return Error::success();
      case BitstreamEntry::Record:
        break;
      }
  
      Record.clear();
      Expected<unsigned> MaybeRecord = Stream.readRecord(Entry.ID, Record);
      if (!MaybeRecord)
        return MaybeRecord.takeError();
      switch (MaybeRecord.get()) {
      case bitc::VST_CODE_FNENTRY: // [valueid, offset]
        setDeferredFunctionInfo(FuncBitcodeOffsetDelta,
                                cast<Function>(ValueList[Record[0]]), Record);
        break;
      }
    }
  }
  
  /// Parse the value symbol table at either the current parsing location or
  /// at the given bit offset if provided.
  Error BitcodeReader::parseValueSymbolTable(uint64_t Offset) {
    uint64_t CurrentBit;
    // Pass in the Offset to distinguish between calling for the module-level
    // VST (where we want to jump to the VST offset) and the function-level
    // VST (where we don't).
    if (Offset > 0) {
      Expected<uint64_t> MaybeCurrentBit = jumpToValueSymbolTable(Offset, Stream);
      if (!MaybeCurrentBit)
        return MaybeCurrentBit.takeError();
      CurrentBit = MaybeCurrentBit.get();
      // If this module uses a string table, read this as a module-level VST.
      if (UseStrtab) {
        if (Error Err = parseGlobalValueSymbolTable())
          return Err;
        if (Error JumpFailed = Stream.JumpToBit(CurrentBit))
          return JumpFailed;
        return Error::success();
      }
      // Otherwise, the VST will be in a similar format to a function-level VST,
      // and will contain symbol names.
    }
  
    // Compute the delta between the bitcode indices in the VST (the word offset
    // to the word-aligned ENTER_SUBBLOCK for the function block, and that
    // expected by the lazy reader. The reader's EnterSubBlock expects to have
    // already read the ENTER_SUBBLOCK code (size getAbbrevIDWidth) and BlockID
    // (size BlockIDWidth). Note that we access the stream's AbbrevID width here
    // just before entering the VST subblock because: 1) the EnterSubBlock
    // changes the AbbrevID width; 2) the VST block is nested within the same
    // outer MODULE_BLOCK as the FUNCTION_BLOCKs and therefore have the same
    // AbbrevID width before calling EnterSubBlock; and 3) when we want to
    // jump to the FUNCTION_BLOCK using this offset later, we don't want
    // to rely on the stream's AbbrevID width being that of the MODULE_BLOCK.
    unsigned FuncBitcodeOffsetDelta =
        Stream.getAbbrevIDWidth() + bitc::BlockIDWidth;
  
    if (Error Err = Stream.EnterSubBlock(bitc::VALUE_SYMTAB_BLOCK_ID))
      return Err;
  
    SmallVector<uint64_t, 64> Record;
  
    Triple TT(TheModule->getTargetTriple());
  
    // Read all the records for this value table.
    SmallString<128> ValueName;
  
    while (true) {
      Expected<BitstreamEntry> MaybeEntry = Stream.advanceSkippingSubblocks();
      if (!MaybeEntry)
        return MaybeEntry.takeError();
      BitstreamEntry Entry = MaybeEntry.get();
  
      switch (Entry.Kind) {
      case BitstreamEntry::SubBlock: // Handled for us already.
      case BitstreamEntry::Error:
        return error("Malformed block");
      case BitstreamEntry::EndBlock:
        if (Offset > 0)
          if (Error JumpFailed = Stream.JumpToBit(CurrentBit))
            return JumpFailed;
        return Error::success();
      case BitstreamEntry::Record:
        // The interesting case.
        break;
      }
  
      // Read a record.
      Record.clear();
      Expected<unsigned> MaybeRecord = Stream.readRecord(Entry.ID, Record);
      if (!MaybeRecord)
        return MaybeRecord.takeError();
      switch (MaybeRecord.get()) {
      default:  // Default behavior: unknown type.
        break;
      case bitc::VST_CODE_ENTRY: {  // VST_CODE_ENTRY: [valueid, namechar x N]
        Expected<Value *> ValOrErr = recordValue(Record, 1, TT);
        if (Error Err = ValOrErr.takeError())
          return Err;
        ValOrErr.get();
        break;
      }
      case bitc::VST_CODE_FNENTRY: {
        // VST_CODE_FNENTRY: [valueid, offset, namechar x N]
        Expected<Value *> ValOrErr = recordValue(Record, 2, TT);
        if (Error Err = ValOrErr.takeError())
          return Err;
        Value *V = ValOrErr.get();
  
        // Ignore function offsets emitted for aliases of functions in older
        // versions of LLVM.
        if (auto *F = dyn_cast<Function>(V))
          setDeferredFunctionInfo(FuncBitcodeOffsetDelta, F, Record);
        break;
      }
      case bitc::VST_CODE_BBENTRY: {
        if (convertToString(Record, 1, ValueName))
          return error("Invalid record");
        BasicBlock *BB = getBasicBlock(Record[0]);
        if (!BB)
          return error("Invalid record");
  
        BB->setName(StringRef(ValueName.data(), ValueName.size()));
        ValueName.clear();
        break;
      }
      }
    }
  }
  
  /// Decode a signed value stored with the sign bit in the LSB for dense VBR
  /// encoding.
  uint64_t BitcodeReader::decodeSignRotatedValue(uint64_t V) {
    if ((V & 1) == 0)
      return V >> 1;
    if (V != 1)
      return -(V >> 1);
    // There is no such thing as -0 with integers.  "-0" really means MININT.
    return 1ULL << 63;
  }
  
  /// Resolve all of the initializers for global values and aliases that we can.
  Error BitcodeReader::resolveGlobalAndIndirectSymbolInits() {
    std::vector<std::pair<GlobalVariable *, unsigned>> GlobalInitWorklist;
    std::vector<std::pair<GlobalIndirectSymbol *, unsigned>>
        IndirectSymbolInitWorklist;
    std::vector<std::pair<Function *, unsigned>> FunctionPrefixWorklist;
    std::vector<std::pair<Function *, unsigned>> FunctionPrologueWorklist;
    std::vector<std::pair<Function *, unsigned>> FunctionPersonalityFnWorklist;
  
    GlobalInitWorklist.swap(GlobalInits);
    IndirectSymbolInitWorklist.swap(IndirectSymbolInits);
    FunctionPrefixWorklist.swap(FunctionPrefixes);
    FunctionPrologueWorklist.swap(FunctionPrologues);
    FunctionPersonalityFnWorklist.swap(FunctionPersonalityFns);
  
    while (!GlobalInitWorklist.empty()) {
      unsigned ValID = GlobalInitWorklist.back().second;
      if (ValID >= ValueList.size()) {
        // Not ready to resolve this yet, it requires something later in the file.
        GlobalInits.push_back(GlobalInitWorklist.back());
      } else {
        if (Constant *C = dyn_cast_or_null<Constant>(ValueList[ValID]))
          GlobalInitWorklist.back().first->setInitializer(C);
        else
          return error("Expected a constant");
      }
      GlobalInitWorklist.pop_back();
    }
  
    while (!IndirectSymbolInitWorklist.empty()) {
      unsigned ValID = IndirectSymbolInitWorklist.back().second;
      if (ValID >= ValueList.size()) {
        IndirectSymbolInits.push_back(IndirectSymbolInitWorklist.back());
      } else {
        Constant *C = dyn_cast_or_null<Constant>(ValueList[ValID]);
        if (!C)
          return error("Expected a constant");
        GlobalIndirectSymbol *GIS = IndirectSymbolInitWorklist.back().first;
        if (isa<GlobalAlias>(GIS) && C->getType() != GIS->getType())
          return error("Alias and aliasee types don't match");
        GIS->setIndirectSymbol(C);
      }
      IndirectSymbolInitWorklist.pop_back();
    }
  
    while (!FunctionPrefixWorklist.empty()) {
      unsigned ValID = FunctionPrefixWorklist.back().second;
      if (ValID >= ValueList.size()) {
        FunctionPrefixes.push_back(FunctionPrefixWorklist.back());
      } else {
        if (Constant *C = dyn_cast_or_null<Constant>(ValueList[ValID]))
          FunctionPrefixWorklist.back().first->setPrefixData(C);
        else
          return error("Expected a constant");
      }
      FunctionPrefixWorklist.pop_back();
    }
  
    while (!FunctionPrologueWorklist.empty()) {
      unsigned ValID = FunctionPrologueWorklist.back().second;
      if (ValID >= ValueList.size()) {
        FunctionPrologues.push_back(FunctionPrologueWorklist.back());
      } else {
        if (Constant *C = dyn_cast_or_null<Constant>(ValueList[ValID]))
          FunctionPrologueWorklist.back().first->setPrologueData(C);
        else
          return error("Expected a constant");
      }
      FunctionPrologueWorklist.pop_back();
    }
  
    while (!FunctionPersonalityFnWorklist.empty()) {
      unsigned ValID = FunctionPersonalityFnWorklist.back().second;
      if (ValID >= ValueList.size()) {
        FunctionPersonalityFns.push_back(FunctionPersonalityFnWorklist.back());
      } else {
        if (Constant *C = dyn_cast_or_null<Constant>(ValueList[ValID]))
          FunctionPersonalityFnWorklist.back().first->setPersonalityFn(C);
        else
          return error("Expected a constant");
      }
      FunctionPersonalityFnWorklist.pop_back();
    }
  
    return Error::success();
  }
  
  APInt llvm::readWideAPInt(ArrayRef<uint64_t> Vals, unsigned TypeBits) {
    SmallVector<uint64_t, 8> Words(Vals.size());
    transform(Vals, Words.begin(),
                   BitcodeReader::decodeSignRotatedValue);
  
    return APInt(TypeBits, Words);
  }
  
  Error BitcodeReader::parseConstants() {
    if (Error Err = Stream.EnterSubBlock(bitc::CONSTANTS_BLOCK_ID))
      return Err;
  
    SmallVector<uint64_t, 64> Record;
  
    // Read all the records for this value table.
    Type *CurTy = Type::getInt32Ty(Context);
    Type *CurFullTy = Type::getInt32Ty(Context);
    unsigned NextCstNo = ValueList.size();
  
    struct DelayedShufTy {
      VectorType *OpTy;
      VectorType *RTy;
      Type *CurFullTy;
      uint64_t Op0Idx;
      uint64_t Op1Idx;
      uint64_t Op2Idx;
      unsigned CstNo;
    };
    std::vector<DelayedShufTy> DelayedShuffles;
    while (true) {
      Expected<BitstreamEntry> MaybeEntry = Stream.advanceSkippingSubblocks();
      if (!MaybeEntry)
        return MaybeEntry.takeError();
      BitstreamEntry Entry = MaybeEntry.get();
  
      switch (Entry.Kind) {
      case BitstreamEntry::SubBlock: // Handled for us already.
      case BitstreamEntry::Error:
        return error("Malformed block");
      case BitstreamEntry::EndBlock:
        // Once all the constants have been read, go through and resolve forward
        // references.
        //
        // We have to treat shuffles specially because they don't have three
        // operands anymore.  We need to convert the shuffle mask into an array,
        // and we can't convert a forward reference.
        for (auto &DelayedShuffle : DelayedShuffles) {
          VectorType *OpTy = DelayedShuffle.OpTy;
          VectorType *RTy = DelayedShuffle.RTy;
          uint64_t Op0Idx = DelayedShuffle.Op0Idx;
          uint64_t Op1Idx = DelayedShuffle.Op1Idx;
          uint64_t Op2Idx = DelayedShuffle.Op2Idx;
          uint64_t CstNo = DelayedShuffle.CstNo;
          Constant *Op0 = ValueList.getConstantFwdRef(Op0Idx, OpTy);
          Constant *Op1 = ValueList.getConstantFwdRef(Op1Idx, OpTy);
          Type *ShufTy =
              VectorType::get(Type::getInt32Ty(Context), RTy->getElementCount());
          Constant *Op2 = ValueList.getConstantFwdRef(Op2Idx, ShufTy);
          if (!ShuffleVectorInst::isValidOperands(Op0, Op1, Op2))
            return error("Invalid shufflevector operands");
          SmallVector<int, 16> Mask;
          ShuffleVectorInst::getShuffleMask(Op2, Mask);
          Value *V = ConstantExpr::getShuffleVector(Op0, Op1, Mask);
          ValueList.assignValue(V, CstNo, DelayedShuffle.CurFullTy);
        }
  
        if (NextCstNo != ValueList.size())
          return error("Invalid constant reference");
  
        ValueList.resolveConstantForwardRefs();
        return Error::success();
      case BitstreamEntry::Record:
        // The interesting case.
        break;
      }
  
      // Read a record.
      Record.clear();
      Type *VoidType = Type::getVoidTy(Context);
      Value *V = nullptr;
      Expected<unsigned> MaybeBitCode = Stream.readRecord(Entry.ID, Record);
      if (!MaybeBitCode)
        return MaybeBitCode.takeError();
      switch (unsigned BitCode = MaybeBitCode.get()) {
      default:  // Default behavior: unknown constant
      case bitc::CST_CODE_UNDEF:     // UNDEF
        V = UndefValue::get(CurTy);
        break;
      case bitc::CST_CODE_SETTYPE:   // SETTYPE: [typeid]
        if (Record.empty())
          return error("Invalid record");
        if (Record[0] >= TypeList.size() || !TypeList[Record[0]])
          return error("Invalid record");
        if (TypeList[Record[0]] == VoidType)
          return error("Invalid constant type");
        CurFullTy = TypeList[Record[0]];
        CurTy = flattenPointerTypes(CurFullTy);
        continue;  // Skip the ValueList manipulation.
      case bitc::CST_CODE_NULL:      // NULL
        if (CurTy->isVoidTy() || CurTy->isFunctionTy() || CurTy->isLabelTy())
          return error("Invalid type for a constant null value");
        V = Constant::getNullValue(CurTy);
        break;
      case bitc::CST_CODE_INTEGER:   // INTEGER: [intval]
        if (!CurTy->isIntegerTy() || Record.empty())
          return error("Invalid record");
        V = ConstantInt::get(CurTy, decodeSignRotatedValue(Record[0]));
        break;
      case bitc::CST_CODE_WIDE_INTEGER: {// WIDE_INTEGER: [n x intval]
        if (!CurTy->isIntegerTy() || Record.empty())
          return error("Invalid record");
  
        APInt VInt =
            readWideAPInt(Record, cast<IntegerType>(CurTy)->getBitWidth());
        V = ConstantInt::get(Context, VInt);
  
        break;
      }
      case bitc::CST_CODE_FLOAT: {    // FLOAT: [fpval]
        if (Record.empty())
          return error("Invalid record");
        if (CurTy->isHalfTy())
          V = ConstantFP::get(Context, APFloat(APFloat::IEEEhalf(),
                                               APInt(16, (uint16_t)Record[0])));
        else if (CurTy->isBFloatTy())
          V = ConstantFP::get(Context, APFloat(APFloat::BFloat(),
                                               APInt(16, (uint32_t)Record[0])));
        else if (CurTy->isFloatTy())
          V = ConstantFP::get(Context, APFloat(APFloat::IEEEsingle(),
                                               APInt(32, (uint32_t)Record[0])));
        else if (CurTy->isDoubleTy())
          V = ConstantFP::get(Context, APFloat(APFloat::IEEEdouble(),
                                               APInt(64, Record[0])));
        else if (CurTy->isX86_FP80Ty()) {
          // Bits are not stored the same way as a normal i80 APInt, compensate.
          uint64_t Rearrange[2];
          Rearrange[0] = (Record[1] & 0xffffLL) | (Record[0] << 16);
          Rearrange[1] = Record[0] >> 48;
          V = ConstantFP::get(Context, APFloat(APFloat::x87DoubleExtended(),
                                               APInt(80, Rearrange)));
        } else if (CurTy->isFP128Ty())
          V = ConstantFP::get(Context, APFloat(APFloat::IEEEquad(),
                                               APInt(128, Record)));
        else if (CurTy->isPPC_FP128Ty())
          V = ConstantFP::get(Context, APFloat(APFloat::PPCDoubleDouble(),
                                               APInt(128, Record)));
        else
          V = UndefValue::get(CurTy);
        break;
      }
  
      case bitc::CST_CODE_AGGREGATE: {// AGGREGATE: [n x value number]
        if (Record.empty())
          return error("Invalid record");
  
        unsigned Size = Record.size();
        SmallVector<Constant*, 16> Elts;
  
        if (StructType *STy = dyn_cast<StructType>(CurTy)) {
          for (unsigned i = 0; i != Size; ++i)
            Elts.push_back(ValueList.getConstantFwdRef(Record[i],
                                                       STy->getElementType(i)));
          V = ConstantStruct::get(STy, Elts);
        } else if (ArrayType *ATy = dyn_cast<ArrayType>(CurTy)) {
          Type *EltTy = ATy->getElementType();
          for (unsigned i = 0; i != Size; ++i)
            Elts.push_back(ValueList.getConstantFwdRef(Record[i], EltTy));
          V = ConstantArray::get(ATy, Elts);
        } else if (VectorType *VTy = dyn_cast<VectorType>(CurTy)) {
          Type *EltTy = VTy->getElementType();
          for (unsigned i = 0; i != Size; ++i)
            Elts.push_back(ValueList.getConstantFwdRef(Record[i], EltTy));
          V = ConstantVector::get(Elts);
        } else {
          V = UndefValue::get(CurTy);
        }
        break;
      }
      case bitc::CST_CODE_STRING:    // STRING: [values]
      case bitc::CST_CODE_CSTRING: { // CSTRING: [values]
        if (Record.empty())
          return error("Invalid record");
  
        SmallString<16> Elts(Record.begin(), Record.end());
        V = ConstantDataArray::getString(Context, Elts,
                                         BitCode == bitc::CST_CODE_CSTRING);
        break;
      }
      case bitc::CST_CODE_DATA: {// DATA: [n x value]
        if (Record.empty())
          return error("Invalid record");
  
        Type *EltTy;
        if (auto *Array = dyn_cast<ArrayType>(CurTy))
          EltTy = Array->getElementType();
        else
          EltTy = cast<VectorType>(CurTy)->getElementType();
        if (EltTy->isIntegerTy(8)) {
          SmallVector<uint8_t, 16> Elts(Record.begin(), Record.end());
          if (isa<VectorType>(CurTy))
            V = ConstantDataVector::get(Context, Elts);
          else
            V = ConstantDataArray::get(Context, Elts);
        } else if (EltTy->isIntegerTy(16)) {
          SmallVector<uint16_t, 16> Elts(Record.begin(), Record.end());
          if (isa<VectorType>(CurTy))
            V = ConstantDataVector::get(Context, Elts);
          else
            V = ConstantDataArray::get(Context, Elts);
        } else if (EltTy->isIntegerTy(32)) {
          SmallVector<uint32_t, 16> Elts(Record.begin(), Record.end());
          if (isa<VectorType>(CurTy))
            V = ConstantDataVector::get(Context, Elts);
          else
            V = ConstantDataArray::get(Context, Elts);
        } else if (EltTy->isIntegerTy(64)) {
          SmallVector<uint64_t, 16> Elts(Record.begin(), Record.end());
          if (isa<VectorType>(CurTy))
            V = ConstantDataVector::get(Context, Elts);
          else
            V = ConstantDataArray::get(Context, Elts);
        } else if (EltTy->isHalfTy()) {
          SmallVector<uint16_t, 16> Elts(Record.begin(), Record.end());
          if (isa<VectorType>(CurTy))
            V = ConstantDataVector::getFP(EltTy, Elts);
          else
            V = ConstantDataArray::getFP(EltTy, Elts);
        } else if (EltTy->isBFloatTy()) {
          SmallVector<uint16_t, 16> Elts(Record.begin(), Record.end());
          if (isa<VectorType>(CurTy))
            V = ConstantDataVector::getFP(EltTy, Elts);
          else
            V = ConstantDataArray::getFP(EltTy, Elts);
        } else if (EltTy->isFloatTy()) {
          SmallVector<uint32_t, 16> Elts(Record.begin(), Record.end());
          if (isa<VectorType>(CurTy))
            V = ConstantDataVector::getFP(EltTy, Elts);
          else
            V = ConstantDataArray::getFP(EltTy, Elts);
        } else if (EltTy->isDoubleTy()) {
          SmallVector<uint64_t, 16> Elts(Record.begin(), Record.end());
          if (isa<VectorType>(CurTy))
            V = ConstantDataVector::getFP(EltTy, Elts);
          else
            V = ConstantDataArray::getFP(EltTy, Elts);
        } else {
          return error("Invalid type for value");
        }
        break;
      }
      case bitc::CST_CODE_CE_UNOP: {  // CE_UNOP: [opcode, opval]
        if (Record.size() < 2)
          return error("Invalid record");
        int Opc = getDecodedUnaryOpcode(Record[0], CurTy);
        if (Opc < 0) {
          V = UndefValue::get(CurTy);  // Unknown unop.
        } else {
          Constant *LHS = ValueList.getConstantFwdRef(Record[1], CurTy);
          unsigned Flags = 0;
          V = ConstantExpr::get(Opc, LHS, Flags);
        }
        break;
      }
      case bitc::CST_CODE_CE_BINOP: {  // CE_BINOP: [opcode, opval, opval]
        if (Record.size() < 3)
          return error("Invalid record");
        int Opc = getDecodedBinaryOpcode(Record[0], CurTy);
        if (Opc < 0) {
          V = UndefValue::get(CurTy);  // Unknown binop.
        } else {
          Constant *LHS = ValueList.getConstantFwdRef(Record[1], CurTy);
          Constant *RHS = ValueList.getConstantFwdRef(Record[2], CurTy);
          unsigned Flags = 0;
          if (Record.size() >= 4) {
            if (Opc == Instruction::Add ||
                Opc == Instruction::Sub ||
                Opc == Instruction::Mul ||
                Opc == Instruction::Shl) {
              if (Record[3] & (1 << bitc::OBO_NO_SIGNED_WRAP))
                Flags |= OverflowingBinaryOperator::NoSignedWrap;
              if (Record[3] & (1 << bitc::OBO_NO_UNSIGNED_WRAP))
                Flags |= OverflowingBinaryOperator::NoUnsignedWrap;
            } else if (Opc == Instruction::SDiv ||
                       Opc == Instruction::UDiv ||
                       Opc == Instruction::LShr ||
                       Opc == Instruction::AShr) {
              if (Record[3] & (1 << bitc::PEO_EXACT))
                Flags |= SDivOperator::IsExact;
            }
          }
          V = ConstantExpr::get(Opc, LHS, RHS, Flags);
        }
        break;
      }
      case bitc::CST_CODE_CE_CAST: {  // CE_CAST: [opcode, opty, opval]
        if (Record.size() < 3)
          return error("Invalid record");
        int Opc = getDecodedCastOpcode(Record[0]);
        if (Opc < 0) {
          V = UndefValue::get(CurTy);  // Unknown cast.
        } else {
          Type *OpTy = getTypeByID(Record[1]);
          if (!OpTy)
            return error("Invalid record");
          Constant *Op = ValueList.getConstantFwdRef(Record[2], OpTy);
          V = UpgradeBitCastExpr(Opc, Op, CurTy);
          if (!V) V = ConstantExpr::getCast(Opc, Op, CurTy);
        }
        break;
      }
      case bitc::CST_CODE_CE_INBOUNDS_GEP: // [ty, n x operands]
      case bitc::CST_CODE_CE_GEP: // [ty, n x operands]
      case bitc::CST_CODE_CE_GEP_WITH_INRANGE_INDEX: { // [ty, flags, n x
                                                       // operands]
        unsigned OpNum = 0;
        Type *PointeeType = nullptr;
        if (BitCode == bitc::CST_CODE_CE_GEP_WITH_INRANGE_INDEX ||
            Record.size() % 2)
          PointeeType = getTypeByID(Record[OpNum++]);
  
        bool InBounds = false;
        Optional<unsigned> InRangeIndex;
        if (BitCode == bitc::CST_CODE_CE_GEP_WITH_INRANGE_INDEX) {
          uint64_t Op = Record[OpNum++];
          InBounds = Op & 1;
          InRangeIndex = Op >> 1;
        } else if (BitCode == bitc::CST_CODE_CE_INBOUNDS_GEP)
          InBounds = true;
  
        SmallVector<Constant*, 16> Elts;
        Type *Elt0FullTy = nullptr;
        while (OpNum != Record.size()) {
          if (!Elt0FullTy)
            Elt0FullTy = getFullyStructuredTypeByID(Record[OpNum]);
          Type *ElTy = getTypeByID(Record[OpNum++]);
          if (!ElTy)
            return error("Invalid record");
          Elts.push_back(ValueList.getConstantFwdRef(Record[OpNum++], ElTy));
        }
  
        if (Elts.size() < 1)
          return error("Invalid gep with no operands");
  
        Type *ImplicitPointeeType =
            getPointerElementFlatType(Elt0FullTy->getScalarType());
        if (!PointeeType)
          PointeeType = ImplicitPointeeType;
        else if (PointeeType != ImplicitPointeeType)
          return error("Explicit gep operator type does not match pointee type "
                       "of pointer operand");
  
        ArrayRef<Constant *> Indices(Elts.begin() + 1, Elts.end());
        V = ConstantExpr::getGetElementPtr(PointeeType, Elts[0], Indices,
                                           InBounds, InRangeIndex);
        break;
      }
      case bitc::CST_CODE_CE_SELECT: {  // CE_SELECT: [opval#, opval#, opval#]
        if (Record.size() < 3)
          return error("Invalid record");
  
        Type *SelectorTy = Type::getInt1Ty(Context);
  
        // The selector might be an i1, an <n x i1>, or a <vscale x n x i1>
        // Get the type from the ValueList before getting a forward ref.
        if (VectorType *VTy = dyn_cast<VectorType>(CurTy))
          if (Value *V = ValueList[Record[0]])
            if (SelectorTy != V->getType())
              SelectorTy = VectorType::get(SelectorTy,
                                           VTy->getElementCount());
  
        V = ConstantExpr::getSelect(ValueList.getConstantFwdRef(Record[0],
                                                                SelectorTy),
                                    ValueList.getConstantFwdRef(Record[1],CurTy),
                                    ValueList.getConstantFwdRef(Record[2],CurTy));
        break;
      }
      case bitc::CST_CODE_CE_EXTRACTELT
          : { // CE_EXTRACTELT: [opty, opval, opty, opval]
        if (Record.size() < 3)
          return error("Invalid record");
        VectorType *OpTy =
          dyn_cast_or_null<VectorType>(getTypeByID(Record[0]));
        if (!OpTy)
          return error("Invalid record");
        Constant *Op0 = ValueList.getConstantFwdRef(Record[1], OpTy);
        Constant *Op1 = nullptr;
        if (Record.size() == 4) {
          Type *IdxTy = getTypeByID(Record[2]);
          if (!IdxTy)
            return error("Invalid record");
          Op1 = ValueList.getConstantFwdRef(Record[3], IdxTy);
        } else {
          // Deprecated, but still needed to read old bitcode files.
          Op1 = ValueList.getConstantFwdRef(Record[2], Type::getInt32Ty(Context));
        }
        if (!Op1)
          return error("Invalid record");
        V = ConstantExpr::getExtractElement(Op0, Op1);
        break;
      }
      case bitc::CST_CODE_CE_INSERTELT
          : { // CE_INSERTELT: [opval, opval, opty, opval]
        VectorType *OpTy = dyn_cast<VectorType>(CurTy);
        if (Record.size() < 3 || !OpTy)
          return error("Invalid record");
        Constant *Op0 = ValueList.getConstantFwdRef(Record[0], OpTy);
        Constant *Op1 = ValueList.getConstantFwdRef(Record[1],
                                                    OpTy->getElementType());
        Constant *Op2 = nullptr;
        if (Record.size() == 4) {
          Type *IdxTy = getTypeByID(Record[2]);
          if (!IdxTy)
            return error("Invalid record");
          Op2 = ValueList.getConstantFwdRef(Record[3], IdxTy);
        } else {
          // Deprecated, but still needed to read old bitcode files.
          Op2 = ValueList.getConstantFwdRef(Record[2], Type::getInt32Ty(Context));
        }
        if (!Op2)
          return error("Invalid record");
        V = ConstantExpr::getInsertElement(Op0, Op1, Op2);
        break;
      }
      case bitc::CST_CODE_CE_SHUFFLEVEC: { // CE_SHUFFLEVEC: [opval, opval, opval]
        VectorType *OpTy = dyn_cast<VectorType>(CurTy);
        if (Record.size() < 3 || !OpTy)
          return error("Invalid record");
        DelayedShuffles.push_back(
            {OpTy, OpTy, CurFullTy, Record[0], Record[1], Record[2], NextCstNo});
        ++NextCstNo;
        continue;
      }
      case bitc::CST_CODE_CE_SHUFVEC_EX: { // [opty, opval, opval, opval]
        VectorType *RTy = dyn_cast<VectorType>(CurTy);
        VectorType *OpTy =
          dyn_cast_or_null<VectorType>(getTypeByID(Record[0]));
        if (Record.size() < 4 || !RTy || !OpTy)
          return error("Invalid record");
        DelayedShuffles.push_back(
            {OpTy, RTy, CurFullTy, Record[1], Record[2], Record[3], NextCstNo});
        ++NextCstNo;
        continue;
      }
      case bitc::CST_CODE_CE_CMP: {     // CE_CMP: [opty, opval, opval, pred]
        if (Record.size() < 4)
          return error("Invalid record");
        Type *OpTy = getTypeByID(Record[0]);
        if (!OpTy)
          return error("Invalid record");
        Constant *Op0 = ValueList.getConstantFwdRef(Record[1], OpTy);
        Constant *Op1 = ValueList.getConstantFwdRef(Record[2], OpTy);
  
        if (OpTy->isFPOrFPVectorTy())
          V = ConstantExpr::getFCmp(Record[3], Op0, Op1);
        else
          V = ConstantExpr::getICmp(Record[3], Op0, Op1);
        break;
      }
      // This maintains backward compatibility, pre-asm dialect keywords.
      // Deprecated, but still needed to read old bitcode files.
      case bitc::CST_CODE_INLINEASM_OLD: {
        if (Record.size() < 2)
          return error("Invalid record");
        std::string AsmStr, ConstrStr;
        bool HasSideEffects = Record[0] & 1;
        bool IsAlignStack = Record[0] >> 1;
        unsigned AsmStrSize = Record[1];
        if (2+AsmStrSize >= Record.size())
          return error("Invalid record");
        unsigned ConstStrSize = Record[2+AsmStrSize];
        if (3+AsmStrSize+ConstStrSize > Record.size())
          return error("Invalid record");
  
        for (unsigned i = 0; i != AsmStrSize; ++i)
          AsmStr += (char)Record[2+i];
        for (unsigned i = 0; i != ConstStrSize; ++i)
          ConstrStr += (char)Record[3+AsmStrSize+i];
        UpgradeInlineAsmString(&AsmStr);
        V = InlineAsm::get(
            cast<FunctionType>(getPointerElementFlatType(CurFullTy)), AsmStr,
            ConstrStr, HasSideEffects, IsAlignStack);
        break;
      }
      // This version adds support for the asm dialect keywords (e.g.,
      // inteldialect).
      case bitc::CST_CODE_INLINEASM: {
        if (Record.size() < 2)
          return error("Invalid record");
        std::string AsmStr, ConstrStr;
        bool HasSideEffects = Record[0] & 1;
        bool IsAlignStack = (Record[0] >> 1) & 1;
        unsigned AsmDialect = Record[0] >> 2;
        unsigned AsmStrSize = Record[1];
        if (2+AsmStrSize >= Record.size())
          return error("Invalid record");
        unsigned ConstStrSize = Record[2+AsmStrSize];
        if (3+AsmStrSize+ConstStrSize > Record.size())
          return error("Invalid record");
  
        for (unsigned i = 0; i != AsmStrSize; ++i)
          AsmStr += (char)Record[2+i];
        for (unsigned i = 0; i != ConstStrSize; ++i)
          ConstrStr += (char)Record[3+AsmStrSize+i];
        UpgradeInlineAsmString(&AsmStr);
        V = InlineAsm::get(
            cast<FunctionType>(getPointerElementFlatType(CurFullTy)), AsmStr,
            ConstrStr, HasSideEffects, IsAlignStack,
            InlineAsm::AsmDialect(AsmDialect));
        break;
      }
      case bitc::CST_CODE_BLOCKADDRESS:{
        if (Record.size() < 3)
          return error("Invalid record");
        Type *FnTy = getTypeByID(Record[0]);
        if (!FnTy)
          return error("Invalid record");
        Function *Fn =
          dyn_cast_or_null<Function>(ValueList.getConstantFwdRef(Record[1],FnTy));
        if (!Fn)
          return error("Invalid record");
  
        // If the function is already parsed we can insert the block address right
        // away.
        BasicBlock *BB;
        unsigned BBID = Record[2];
        if (!BBID)
          // Invalid reference to entry block.
          return error("Invalid ID");
        if (!Fn->empty()) {
          Function::iterator BBI = Fn->begin(), BBE = Fn->end();
          for (size_t I = 0, E = BBID; I != E; ++I) {
            if (BBI == BBE)
              return error("Invalid ID");
            ++BBI;
          }
          BB = &*BBI;
        } else {
          // Otherwise insert a placeholder and remember it so it can be inserted
          // when the function is parsed.
          auto &FwdBBs = BasicBlockFwdRefs[Fn];
          if (FwdBBs.empty())
            BasicBlockFwdRefQueue.push_back(Fn);
          if (FwdBBs.size() < BBID + 1)
            FwdBBs.resize(BBID + 1);
          if (!FwdBBs[BBID])
            FwdBBs[BBID] = BasicBlock::Create(Context);
          BB = FwdBBs[BBID];
        }
        V = BlockAddress::get(Fn, BB);
        break;
      }
      }
  
      assert(V->getType() == flattenPointerTypes(CurFullTy) &&
             "Incorrect fully structured type provided for Constant");
      ValueList.assignValue(V, NextCstNo, CurFullTy);
      ++NextCstNo;
    }
  }
  
  Error BitcodeReader::parseUseLists() {
    if (Error Err = Stream.EnterSubBlock(bitc::USELIST_BLOCK_ID))
      return Err;
  
    // Read all the records.
    SmallVector<uint64_t, 64> Record;
  
    while (true) {
      Expected<BitstreamEntry> MaybeEntry = Stream.advanceSkippingSubblocks();
      if (!MaybeEntry)
        return MaybeEntry.takeError();
      BitstreamEntry Entry = MaybeEntry.get();
  
      switch (Entry.Kind) {
      case BitstreamEntry::SubBlock: // Handled for us already.
      case BitstreamEntry::Error:
        return error("Malformed block");
      case BitstreamEntry::EndBlock:
        return Error::success();
      case BitstreamEntry::Record:
        // The interesting case.
        break;
      }
  
      // Read a use list record.
      Record.clear();
      bool IsBB = false;
      Expected<unsigned> MaybeRecord = Stream.readRecord(Entry.ID, Record);
      if (!MaybeRecord)
        return MaybeRecord.takeError();
      switch (MaybeRecord.get()) {
      default:  // Default behavior: unknown type.
        break;
      case bitc::USELIST_CODE_BB:
        IsBB = true;
        LLVM_FALLTHROUGH;
      case bitc::USELIST_CODE_DEFAULT: {
        unsigned RecordLength = Record.size();
        if (RecordLength < 3)
          // Records should have at least an ID and two indexes.
          return error("Invalid record");
        unsigned ID = Record.back();
        Record.pop_back();
  
        Value *V;
        if (IsBB) {
          assert(ID < FunctionBBs.size() && "Basic block not found");
          V = FunctionBBs[ID];
        } else
          V = ValueList[ID];
        unsigned NumUses = 0;
        SmallDenseMap<const Use *, unsigned, 16> Order;
        for (const Use &U : V->materialized_uses()) {
          if (++NumUses > Record.size())
            break;
          Order[&U] = Record[NumUses - 1];
        }
        if (Order.size() != Record.size() || NumUses > Record.size())
          // Mismatches can happen if the functions are being materialized lazily
          // (out-of-order), or a value has been upgraded.
          break;
  
        V->sortUseList([&](const Use &L, const Use &R) {
          return Order.lookup(&L) < Order.lookup(&R);
        });
        break;
      }
      }
    }
  }
  
  /// When we see the block for metadata, remember where it is and then skip it.
  /// This lets us lazily deserialize the metadata.
  Error BitcodeReader::rememberAndSkipMetadata() {
    // Save the current stream state.
    uint64_t CurBit = Stream.GetCurrentBitNo();
    DeferredMetadataInfo.push_back(CurBit);
  
    // Skip over the block for now.
    if (Error Err = Stream.SkipBlock())
      return Err;
    return Error::success();
  }
  
  Error BitcodeReader::materializeMetadata() {
    for (uint64_t BitPos : DeferredMetadataInfo) {
      // Move the bit stream to the saved position.
      if (Error JumpFailed = Stream.JumpToBit(BitPos))
        return JumpFailed;
      if (Error Err = MDLoader->parseModuleMetadata())
        return Err;
    }
  
    // Upgrade "Linker Options" module flag to "llvm.linker.options" module-level
    // metadata. Only upgrade if the new option doesn't exist to avoid upgrade
    // multiple times.
    if (!TheModule->getNamedMetadata("llvm.linker.options")) {
      if (Metadata *Val = TheModule->getModuleFlag("Linker Options")) {
        NamedMDNode *LinkerOpts =
            TheModule->getOrInsertNamedMetadata("llvm.linker.options");
        for (const MDOperand &MDOptions : cast<MDNode>(Val)->operands())
          LinkerOpts->addOperand(cast<MDNode>(MDOptions));
      }
    }
  
    DeferredMetadataInfo.clear();
    return Error::success();
  }
  
  void BitcodeReader::setStripDebugInfo() { StripDebugInfo = true; }
  
  /// When we see the block for a function body, remember where it is and then
  /// skip it.  This lets us lazily deserialize the functions.
  Error BitcodeReader::rememberAndSkipFunctionBody() {
    // Get the function we are talking about.
    if (FunctionsWithBodies.empty())
      return error("Insufficient function protos");
  
    Function *Fn = FunctionsWithBodies.back();
    FunctionsWithBodies.pop_back();
  
    // Save the current stream state.
    uint64_t CurBit = Stream.GetCurrentBitNo();
    assert(
        (DeferredFunctionInfo[Fn] == 0 || DeferredFunctionInfo[Fn] == CurBit) &&
        "Mismatch between VST and scanned function offsets");
    DeferredFunctionInfo[Fn] = CurBit;
  
    // Skip over the function block for now.
    if (Error Err = Stream.SkipBlock())
      return Err;
    return Error::success();
  }
  
  Error BitcodeReader::globalCleanup() {
    // Patch the initializers for globals and aliases up.
    if (Error Err = resolveGlobalAndIndirectSymbolInits())
      return Err;
    if (!GlobalInits.empty() || !IndirectSymbolInits.empty())
      return error("Malformed global initializer set");
  
    // Look for intrinsic functions which need to be upgraded at some point
    // and functions that need to have their function attributes upgraded.
    for (Function &F : *TheModule) {
      MDLoader->upgradeDebugIntrinsics(F);
      Function *NewFn;
      if (UpgradeIntrinsicFunction(&F, NewFn))
        UpgradedIntrinsics[&F] = NewFn;
      else if (auto Remangled = Intrinsic::remangleIntrinsicFunction(&F))
        // Some types could be renamed during loading if several modules are
        // loaded in the same LLVMContext (LTO scenario). In this case we should
        // remangle intrinsics names as well.
        RemangledIntrinsics[&F] = Remangled.getValue();
      // Look for functions that rely on old function attribute behavior.
      UpgradeFunctionAttributes(F);
    }
  
    // Look for global variables which need to be renamed.
    std::vector<std::pair<GlobalVariable *, GlobalVariable *>> UpgradedVariables;
    for (GlobalVariable &GV : TheModule->globals())
      if (GlobalVariable *Upgraded = UpgradeGlobalVariable(&GV))
        UpgradedVariables.emplace_back(&GV, Upgraded);
    for (auto &Pair : UpgradedVariables) {
      Pair.first->eraseFromParent();
      TheModule->getGlobalList().push_back(Pair.second);
    }
  
    // Force deallocation of memory for these vectors to favor the client that
    // want lazy deserialization.
    std::vector<std::pair<GlobalVariable *, unsigned>>().swap(GlobalInits);
    std::vector<std::pair<GlobalIndirectSymbol *, unsigned>>().swap(
        IndirectSymbolInits);
    return Error::success();
  }
  
  /// Support for lazy parsing of function bodies. This is required if we
  /// either have an old bitcode file without a VST forward declaration record,
  /// or if we have an anonymous function being materialized, since anonymous
  /// functions do not have a name and are therefore not in the VST.
  Error BitcodeReader::rememberAndSkipFunctionBodies() {
    if (Error JumpFailed = Stream.JumpToBit(NextUnreadBit))
      return JumpFailed;
  
    if (Stream.AtEndOfStream())
      return error("Could not find function in stream");
  
    if (!SeenFirstFunctionBody)
      return error("Trying to materialize functions before seeing function blocks");
  
    // An old bitcode file with the symbol table at the end would have
    // finished the parse greedily.
    assert(SeenValueSymbolTable);
  
    SmallVector<uint64_t, 64> Record;
  
    while (true) {
      Expected<llvm::BitstreamEntry> MaybeEntry = Stream.advance();
      if (!MaybeEntry)
        return MaybeEntry.takeError();
      llvm::BitstreamEntry Entry = MaybeEntry.get();
  
      switch (Entry.Kind) {
      default:
        return error("Expect SubBlock");
      case BitstreamEntry::SubBlock:
        switch (Entry.ID) {
        default:
          return error("Expect function block");
        case bitc::FUNCTION_BLOCK_ID:
          if (Error Err = rememberAndSkipFunctionBody())
            return Err;
          NextUnreadBit = Stream.GetCurrentBitNo();
          return Error::success();
        }
      }
    }
  }
  
  bool BitcodeReaderBase::readBlockInfo() {
    Expected<Optional<BitstreamBlockInfo>> MaybeNewBlockInfo =
        Stream.ReadBlockInfoBlock();
    if (!MaybeNewBlockInfo)
      return true; // FIXME Handle the error.
    Optional<BitstreamBlockInfo> NewBlockInfo =
        std::move(MaybeNewBlockInfo.get());
    if (!NewBlockInfo)
      return true;
    BlockInfo = std::move(*NewBlockInfo);
    return false;
  }
  
  Error BitcodeReader::parseComdatRecord(ArrayRef<uint64_t> Record) {
    // v1: [selection_kind, name]
    // v2: [strtab_offset, strtab_size, selection_kind]
    StringRef Name;
    std::tie(Name, Record) = readNameFromStrtab(Record);
  
    if (Record.empty())
      return error("Invalid record");
    Comdat::SelectionKind SK = getDecodedComdatSelectionKind(Record[0]);
    std::string OldFormatName;
    if (!UseStrtab) {
      if (Record.size() < 2)
        return error("Invalid record");
      unsigned ComdatNameSize = Record[1];
      OldFormatName.reserve(ComdatNameSize);
      for (unsigned i = 0; i != ComdatNameSize; ++i)
        OldFormatName += (char)Record[2 + i];
      Name = OldFormatName;
    }
    Comdat *C = TheModule->getOrInsertComdat(Name);
    C->setSelectionKind(SK);
    ComdatList.push_back(C);
    return Error::success();
  }
  
  static void inferDSOLocal(GlobalValue *GV) {
    // infer dso_local from linkage and visibility if it is not encoded.
    if (GV->hasLocalLinkage() ||
        (!GV->hasDefaultVisibility() && !GV->hasExternalWeakLinkage()))
      GV->setDSOLocal(true);
  }
  
  Error BitcodeReader::parseGlobalVarRecord(ArrayRef<uint64_t> Record) {
    // v1: [pointer type, isconst, initid, linkage, alignment, section,
    // visibility, threadlocal, unnamed_addr, externally_initialized,
    // dllstorageclass, comdat, attributes, preemption specifier,
    // partition strtab offset, partition strtab size] (name in VST)
    // v2: [strtab_offset, strtab_size, v1]
    StringRef Name;
    std::tie(Name, Record) = readNameFromStrtab(Record);
  
    if (Record.size() < 6)
      return error("Invalid record");
    Type *FullTy = getFullyStructuredTypeByID(Record[0]);
    Type *Ty = flattenPointerTypes(FullTy);
    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();
      std::tie(FullTy, Ty) = getPointerElementTypes(FullTy);
    }
  
    uint64_t RawLinkage = Record[3];
    GlobalValue::LinkageTypes Linkage = getDecodedLinkage(RawLinkage);
    MaybeAlign 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.
    // auto-upgrade `hidden` and `protected` for old bitcode.
    if (Record.size() > 6 && !GlobalValue::isLocalLinkage(Linkage))
      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, Name,
                           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);
  
    FullTy = PointerType::get(FullTy, AddressSpace);
    assert(NewGV->getType() == flattenPointerTypes(FullTy) &&
           "Incorrect fully specified type for GlobalVariable");
    ValueList.push_back(NewGV, FullTy);
  
    // 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));
    }
  
    if (Record.size() > 12) {
      auto AS = getAttributes(Record[12]).getFnAttributes();
      NewGV->setAttributes(AS);
    }
  
    if (Record.size() > 13) {
      NewGV->setDSOLocal(getDecodedDSOLocal(Record[13]));
    }
    inferDSOLocal(NewGV);
  
    // Check whether we have enough values to read a partition name.
    if (Record.size() > 15)
      NewGV->setPartition(StringRef(Strtab.data() + Record[14], Record[15]));
  
    return Error::success();
  }
  
  Error BitcodeReader::parseFunctionRecord(ArrayRef<uint64_t> Record) {
    // v1: [type, callingconv, isproto, linkage, paramattr, alignment, section,
    // visibility, gc, unnamed_addr, prologuedata, dllstorageclass, comdat,
    // prefixdata,  personalityfn, preemption specifier, addrspace] (name in VST)
    // v2: [strtab_offset, strtab_size, v1]
    StringRef Name;
    std::tie(Name, Record) = readNameFromStrtab(Record);
  
    if (Record.size() < 8)
      return error("Invalid record");
    Type *FullFTy = getFullyStructuredTypeByID(Record[0]);
    Type *FTy = flattenPointerTypes(FullFTy);
    if (!FTy)
      return error("Invalid record");
    if (isa<PointerType>(FTy))
      std::tie(FullFTy, FTy) = getPointerElementTypes(FullFTy);
  
    if (!isa<FunctionType>(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");
  
    unsigned AddrSpace = TheModule->getDataLayout().getProgramAddressSpace();
    if (Record.size() > 16)
      AddrSpace = Record[16];
  
    Function *Func =
        Function::Create(cast<FunctionType>(FTy), GlobalValue::ExternalLinkage,
                         AddrSpace, Name, TheModule);
  
    assert(Func->getFunctionType() == flattenPointerTypes(FullFTy) &&
           "Incorrect fully specified type provided for function");
    FunctionTypes[Func] = cast<FunctionType>(FullFTy);
  
    Func->setCallingConv(CC);
    bool isProto = Record[2];
    uint64_t RawLinkage = Record[3];
    Func->setLinkage(getDecodedLinkage(RawLinkage));
    Func->setAttributes(getAttributes(Record[4]));
  
    // Upgrade any old-style byval without a type by propagating the argument's
    // pointee type. There should be no opaque pointers where the byval type is
    // implicit.
    for (unsigned i = 0; i != Func->arg_size(); ++i) {
      if (!Func->hasParamAttribute(i, Attribute::ByVal))
        continue;
  
      Type *PTy = cast<FunctionType>(FullFTy)->getParamType(i);
      Func->removeParamAttr(i, Attribute::ByVal);
      Func->addParamAttr(i, Attribute::getWithByValType(
                                Context, getPointerElementFlatType(PTy)));
    }
  
    MaybeAlign 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.
    // auto-upgrade `hidden` and `protected` for old bitcode.
    if (!Func->hasLocalLinkage())
      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));
  
    if (Record.size() > 15) {
      Func->setDSOLocal(getDecodedDSOLocal(Record[15]));
    }
    inferDSOLocal(Func);
  
    // Record[16] is the address space number.
  
    // Check whether we have enough values to read a partition name.
    if (Record.size() > 18)
      Func->setPartition(StringRef(Strtab.data() + Record[17], Record[18]));
  
    Type *FullTy = PointerType::get(FullFTy, AddrSpace);
    assert(Func->getType() == flattenPointerTypes(FullTy) &&
           "Incorrect fully specified type provided for Function");
    ValueList.push_back(Func, FullTy);
  
    // 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) {
    // v1 ALIAS_OLD: [alias type, aliasee val#, linkage] (name in VST)
    // v1 ALIAS: [alias type, addrspace, aliasee val#, linkage, visibility,
    // dllstorageclass, threadlocal, unnamed_addr,
    // preemption specifier] (name in VST)
    // v1 IFUNC: [alias type, addrspace, aliasee val#, linkage,
    // visibility, dllstorageclass, threadlocal, unnamed_addr,
    // preemption specifier] (name in VST)
    // v2: [strtab_offset, strtab_size, v1]
    StringRef Name;
    std::tie(Name, Record) = readNameFromStrtab(Record);
  
    bool NewRecord = BitCode != bitc::MODULE_CODE_ALIAS_OLD;
    if (Record.size() < (3 + (unsigned)NewRecord))
      return error("Invalid record");
    unsigned OpNum = 0;
    Type *FullTy = getFullyStructuredTypeByID(Record[OpNum++]);
    Type *Ty = flattenPointerTypes(FullTy);
    if (!Ty)
      return error("Invalid record");
  
    unsigned AddrSpace;
    if (!NewRecord) {
      auto *PTy = dyn_cast<PointerType>(Ty);
      if (!PTy)
        return error("Invalid type for value");
      std::tie(FullTy, Ty) = getPointerElementTypes(FullTy);
      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), Name,
                                  TheModule);
    else
      NewGA = GlobalIFunc::create(Ty, AddrSpace, getDecodedLinkage(Linkage), Name,
                                  nullptr, TheModule);
  
    assert(NewGA->getValueType() == flattenPointerTypes(FullTy) &&
           "Incorrect fully structured type provided for GlobalIndirectSymbol");
    // Local linkage must have default visibility.
    // auto-upgrade `hidden` and `protected` for old bitcode.
    if (OpNum != Record.size()) {
      auto VisInd = OpNum++;
      if (!NewGA->hasLocalLinkage())
        NewGA->setVisibility(getDecodedVisibility(Record[VisInd]));
    }
    if (BitCode == bitc::MODULE_CODE_ALIAS ||
        BitCode == bitc::MODULE_CODE_ALIAS_OLD) {
      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++]));
    }
    if (OpNum != Record.size())
      NewGA->setDSOLocal(getDecodedDSOLocal(Record[OpNum++]));
    inferDSOLocal(NewGA);
  
    // Check whether we have enough values to read a partition name.
    if (OpNum + 1 < Record.size()) {
      NewGA->setPartition(
          StringRef(Strtab.data() + Record[OpNum], Record[OpNum + 1]));
      OpNum += 2;
    }
  
    FullTy = PointerType::get(FullTy, AddrSpace);
    assert(NewGA->getType() == flattenPointerTypes(FullTy) &&
           "Incorrect fully structured type provided for GlobalIndirectSymbol");
    ValueList.push_back(NewGA, FullTy);
    IndirectSymbolInits.push_back(std::make_pair(NewGA, Val));
    return Error::success();
  }
  
  Error BitcodeReader::parseModule(uint64_t ResumeBit,
                                   bool ShouldLazyLoadMetadata,
                                   DataLayoutCallbackTy DataLayoutCallback) {
    if (ResumeBit) {
      if (Error JumpFailed = Stream.JumpToBit(ResumeBit))
        return JumpFailed;
    } else if (Error Err = Stream.EnterSubBlock(bitc::MODULE_BLOCK_ID))
      return Err;
  
    SmallVector<uint64_t, 64> Record;
  
    // Parts of bitcode parsing depend on the datalayout.  Make sure we
    // finalize the datalayout before we run any of that code.
    bool ResolvedDataLayout = false;
    auto ResolveDataLayout = [&] {
      if (ResolvedDataLayout)
        return;
  
      // datalayout and triple can't be parsed after this point.
      ResolvedDataLayout = true;
  
      // Upgrade data layout string.
      std::string DL = llvm::UpgradeDataLayoutString(
          TheModule->getDataLayoutStr(), TheModule->getTargetTriple());
      TheModule->setDataLayout(DL);
  
      if (auto LayoutOverride =
              DataLayoutCallback(TheModule->getTargetTriple()))
        TheModule->setDataLayout(*LayoutOverride);
    };
  
    // Read all the records for this module.
    while (true) {
      Expected<llvm::BitstreamEntry> MaybeEntry = Stream.advance();
      if (!MaybeEntry)
        return MaybeEntry.takeError();
      llvm::BitstreamEntry Entry = MaybeEntry.get();
  
      switch (Entry.Kind) {
      case BitstreamEntry::Error:
        return error("Malformed block");
      case BitstreamEntry::EndBlock:
        ResolveDataLayout();
        return globalCleanup();
  
      case BitstreamEntry::SubBlock:
        switch (Entry.ID) {
        default:  // Skip unknown content.
          if (Error Err = Stream.SkipBlock())
            return Err;
          break;
        case bitc::BLOCKINFO_BLOCK_ID:
          if (readBlockInfo())
            return error("Malformed block");
          break;
        case bitc::PARAMATTR_BLOCK_ID:
          if (Error Err = parseAttributeBlock())
            return Err;
          break;
        case bitc::PARAMATTR_GROUP_BLOCK_ID:
          if (Error Err = parseAttributeGroupBlock())
            return Err;
          break;
        case bitc::TYPE_BLOCK_ID_NEW:
          if (Error Err = parseTypeTable())
            return Err;
          break;
        case bitc::VALUE_SYMTAB_BLOCK_ID:
          if (!SeenValueSymbolTable) {
            // Either this is an old form VST without function index and an
            // associated VST forward declaration record (which would have caused
            // the VST to be jumped to and parsed before it was encountered
            // normally in the stream), or there were no function blocks to
            // trigger an earlier parsing of the VST.
            assert(VSTOffset == 0 || FunctionsWithBodies.empty());
            if (Error Err = parseValueSymbolTable())
              return Err;
            SeenValueSymbolTable = true;
          } else {
            // We must have had a VST forward declaration record, which caused
            // the parser to jump to and parse the VST earlier.
            assert(VSTOffset > 0);
            if (Error Err = Stream.SkipBlock())
              return Err;
          }
          break;
        case bitc::CONSTANTS_BLOCK_ID:
          if (Error Err = parseConstants())
            return Err;
          if (Error Err = resolveGlobalAndIndirectSymbolInits())
            return Err;
          break;
        case bitc::METADATA_BLOCK_ID:
          if (ShouldLazyLoadMetadata) {
            if (Error Err = rememberAndSkipMetadata())
              return Err;
            break;
          }
          assert(DeferredMetadataInfo.empty() && "Unexpected deferred metadata");
          if (Error Err = MDLoader->parseModuleMetadata())
            return Err;
          break;
        case bitc::METADATA_KIND_BLOCK_ID:
          if (Error Err = MDLoader->parseMetadataKinds())
            return Err;
          break;
        case bitc::FUNCTION_BLOCK_ID:
          ResolveDataLayout();
  
          // If this is the first function body we've seen, reverse the
          // FunctionsWithBodies list.
          if (!SeenFirstFunctionBody) {
            std::reverse(FunctionsWithBodies.begin(), FunctionsWithBodies.end());
            if (Error Err = globalCleanup())
              return Err;
            SeenFirstFunctionBody = true;
          }
  
          if (VSTOffset > 0) {
            // If we have a VST forward declaration record, make sure we
            // parse the VST now if we haven't already. It is needed to
            // set up the DeferredFunctionInfo vector for lazy reading.
            if (!SeenValueSymbolTable) {
              if (Error Err = BitcodeReader::parseValueSymbolTable(VSTOffset))
                return Err;
              SeenValueSymbolTable = true;
              // Fall through so that we record the NextUnreadBit below.
              // This is necessary in case we have an anonymous function that
              // is later materialized. Since it will not have a VST entry we
              // need to fall back to the lazy parse to find its offset.
            } else {
              // If we have a VST forward declaration record, but have already
              // parsed the VST (just above, when the first function body was
              // encountered here), then we are resuming the parse after
              // materializing functions. The ResumeBit points to the
              // start of the last function block recorded in the
              // DeferredFunctionInfo map. Skip it.
              if (Error Err = Stream.SkipBlock())
                return Err;
              continue;
            }
          }
  
          // Support older bitcode files that did not have the function
          // index in the VST, nor a VST forward declaration record, as
          // well as anonymous functions that do not have VST entries.
          // Build the DeferredFunctionInfo vector on the fly.
          if (Error Err = rememberAndSkipFunctionBody())
            return Err;
  
          // Suspend parsing when we reach the function bodies. Subsequent
          // materialization calls will resume it when necessary. If the bitcode
          // file is old, the symbol table will be at the end instead and will not
          // have been seen yet. In this case, just finish the parse now.
          if (SeenValueSymbolTable) {
            NextUnreadBit = Stream.GetCurrentBitNo();
            // After the VST has been parsed, we need to make sure intrinsic name
            // are auto-upgraded.
            return globalCleanup();
          }
          break;
        case bitc::USELIST_BLOCK_ID:
          if (Error Err = parseUseLists())
            return Err;
          break;
        case bitc::OPERAND_BUNDLE_TAGS_BLOCK_ID:
          if (Error Err = parseOperandBundleTags())
            return Err;
          break;
        case bitc::SYNC_SCOPE_NAMES_BLOCK_ID:
          if (Error Err = parseSyncScopeNames())
            return Err;
          break;
        }
        continue;
  
      case BitstreamEntry::Record:
        // The interesting case.
        break;
      }
  
      // Read a record.
      Expected<unsigned> MaybeBitCode = Stream.readRecord(Entry.ID, Record);
      if (!MaybeBitCode)
        return MaybeBitCode.takeError();
      switch (unsigned BitCode = MaybeBitCode.get()) {
      default: break;  // Default behavior, ignore unknown content.
      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]
        if (ResolvedDataLayout)
          return error("target triple too late in module");
        std::string S;
        if (convertToString(Record, 0, S))
          return error("Invalid record");
        TheModule->setTargetTriple(S);
        break;
      }
      case bitc::MODULE_CODE_DATALAYOUT: {  // DATALAYOUT: [strchr x N]
        if (ResolvedDataLayout)
          return error("datalayout too late in module");
        std::string S;
        if (convertToString(Record, 0, S))
          return error("Invalid record");
        TheModule->setDataLayout(S);
        break;
      }
      case bitc::MODULE_CODE_ASM: {  // ASM: [strchr x N]
        std::string S;
        if (convertToString(Record, 0, S))
          return error("Invalid record");
        TheModule->setModuleInlineAsm(S);
        break;
      }
      case bitc::MODULE_CODE_DEPLIB: {  // DEPLIB: [strchr x N]
        // Deprecated, but still needed to read old bitcode files.
        std::string S;
        if (convertToString(Record, 0, S))
          return error("Invalid record");
        // Ignore value.
        break;
      }
      case bitc::MODULE_CODE_SECTIONNAME: {  // SECTIONNAME: [strchr x N]
        std::string S;
        if (convertToString(Record, 0, S))
          return error("Invalid record");
        SectionTable.push_back(S);
        break;
      }
      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:
        if (Error Err = parseComdatRecord(Record))
          return Err;
        break;
      case bitc::MODULE_CODE_GLOBALVAR:
        if (Error Err = parseGlobalVarRecord(Record))
          return Err;
        break;
      case bitc::MODULE_CODE_FUNCTION:
        ResolveDataLayout();
        if (Error Err = parseFunctionRecord(Record))
          return Err;
        break;
      case bitc::MODULE_CODE_IFUNC:
      case bitc::MODULE_CODE_ALIAS:
      case bitc::MODULE_CODE_ALIAS_OLD:
        if (Error Err = parseGlobalIndirectSymbolRecord(BitCode, Record))
          return Err;
        break;
      /// MODULE_CODE_VSTOFFSET: [offset]
      case bitc::MODULE_CODE_VSTOFFSET:
        if (Record.empty())
          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
        // historically always the start of the regular bitcode header.
        VSTOffset = Record[0] - 1;
        break;
      /// MODULE_CODE_SOURCE_FILENAME: [namechar x N]
      case bitc::MODULE_CODE_SOURCE_FILENAME:
        SmallString<128> ValueName;
        if (convertToString(Record, 0, ValueName))
          return error("Invalid record");
        TheModule->setSourceFileName(ValueName);
        break;
      }
      Record.clear();
    }
  }
  
  Error BitcodeReader::parseBitcodeInto(Module *M, bool ShouldLazyLoadMetadata,
                                        bool IsImporting,
                                        DataLayoutCallbackTy DataLayoutCallback) {
    TheModule = M;
    MDLoader = MetadataLoader(Stream, *M, ValueList, IsImporting,
                              [&](unsigned ID) { return getTypeByID(ID); });
    return parseModule(0, ShouldLazyLoadMetadata, DataLayoutCallback);
  }
  
  Error BitcodeReader::typeCheckLoadStoreInst(Type *ValType, Type *PtrType) {
    if (!isa<PointerType>(PtrType))
      return error("Load/Store operand is not a pointer type");
    Type *ElemType = cast<PointerType>(PtrType)->getElementType();
  
    if (ValType && ValType != ElemType)
      return error("Explicit load/store type does not match pointee "
                   "type of pointer operand");
    if (!PointerType::isLoadableOrStorableType(ElemType))
      return error("Cannot load/store from pointer");
    return Error::success();
  }
  
  void BitcodeReader::propagateByValTypes(CallBase *CB,
                                          ArrayRef<Type *> ArgsFullTys) {
    for (unsigned i = 0; i != CB->arg_size(); ++i) {
      if (!CB->paramHasAttr(i, Attribute::ByVal))
        continue;
  
      CB->removeParamAttr(i, Attribute::ByVal);
      CB->addParamAttr(
          i, Attribute::getWithByValType(
                 Context, getPointerElementFlatType(ArgsFullTys[i])));
    }
  }
  
  /// Lazily parse the specified function body block.
  Error BitcodeReader::parseFunctionBody(Function *F) {
    if (Error Err = Stream.EnterSubBlock(bitc::FUNCTION_BLOCK_ID))
      return Err;
  
    // Unexpected unresolved metadata when parsing function.
    if (MDLoader->hasFwdRefs())
      return error("Invalid function metadata: incoming forward references");
  
    InstructionList.clear();
    unsigned ModuleValueListSize = ValueList.size();
    unsigned ModuleMDLoaderSize = MDLoader->size();
  
    // Add all the function arguments to the value table.
    unsigned ArgNo = 0;
    FunctionType *FullFTy = FunctionTypes[F];
    for (Argument &I : F->args()) {
      assert(I.getType() == flattenPointerTypes(FullFTy->getParamType(ArgNo)) &&
             "Incorrect fully specified type for Function Argument");
      ValueList.push_back(&I, FullFTy->getParamType(ArgNo++));
    }
    unsigned NextValueNo = ValueList.size();
    BasicBlock *CurBB = nullptr;
    unsigned CurBBNo = 0;
  
    DebugLoc LastLoc;
    auto getLastInstruction = [&]() -> Instruction * {
      if (CurBB && !CurBB->empty())
        return &CurBB->back();
      else if (CurBBNo && FunctionBBs[CurBBNo - 1] &&
               !FunctionBBs[CurBBNo - 1]->empty())
        return &FunctionBBs[CurBBNo - 1]->back();
      return nullptr;
    };
  
    std::vector<OperandBundleDef> OperandBundles;
  
    // Read all the records.
    SmallVector<uint64_t, 64> Record;
  
    while (true) {
      Expected<llvm::BitstreamEntry> MaybeEntry = Stream.advance();
      if (!MaybeEntry)
        return MaybeEntry.takeError();
      llvm::BitstreamEntry Entry = MaybeEntry.get();
  
      switch (Entry.Kind) {
      case BitstreamEntry::Error:
        return error("Malformed block");
      case BitstreamEntry::EndBlock:
        goto OutOfRecordLoop;
  
      case BitstreamEntry::SubBlock:
        switch (Entry.ID) {
        default:  // Skip unknown content.
          if (Error Err = Stream.SkipBlock())
            return Err;
          break;
        case bitc::CONSTANTS_BLOCK_ID:
          if (Error Err = parseConstants())
            return Err;
          NextValueNo = ValueList.size();
          break;
        case bitc::VALUE_SYMTAB_BLOCK_ID:
          if (Error Err = parseValueSymbolTable())
            return Err;
          break;
        case bitc::METADATA_ATTACHMENT_ID:
          if (Error Err = MDLoader->parseMetadataAttachment(*F, InstructionList))
            return Err;
          break;
        case bitc::METADATA_BLOCK_ID:
          assert(DeferredMetadataInfo.empty() &&
                 "Must read all module-level metadata before function-level");
          if (Error Err = MDLoader->parseFunctionMetadata())
            return Err;
          break;
        case bitc::USELIST_BLOCK_ID:
          if (Error Err = parseUseLists())
            return Err;
          break;
        }
        continue;
  
      case BitstreamEntry::Record:
        // The interesting case.
        break;
      }
  
      // Read a record.
      Record.clear();
      Instruction *I = nullptr;
      Type *FullTy = nullptr;
      Expected<unsigned> MaybeBitCode = Stream.readRecord(Entry.ID, Record);
      if (!MaybeBitCode)
        return MaybeBitCode.takeError();
      switch (unsigned BitCode = MaybeBitCode.get()) {
      default: // Default behavior: reject
        return error("Invalid value");
      case bitc::FUNC_CODE_DECLAREBLOCKS: {   // DECLAREBLOCKS: [nblocks]
        if (Record.empty() || Record[0] == 0)
          return error("Invalid record");
        // Create all the basic blocks for the function.
        FunctionBBs.resize(Record[0]);
  
        // See if anything took the address of blocks in this function.
        auto BBFRI = BasicBlockFwdRefs.find(F);
        if (BBFRI == BasicBlockFwdRefs.end()) {
          for (unsigned i = 0, e = FunctionBBs.size(); i != e; ++i)
            FunctionBBs[i] = BasicBlock::Create(Context, "", F);
        } else {
          auto &BBRefs = BBFRI->second;
          // Check for invalid basic block references.
          if (BBRefs.size() > FunctionBBs.size())
            return error("Invalid ID");
          assert(!BBRefs.empty() && "Unexpected empty array");
          assert(!BBRefs.front() && "Invalid reference to entry block");
          for (unsigned I = 0, E = FunctionBBs.size(), RE = BBRefs.size(); I != E;
               ++I)
            if (I < RE && BBRefs[I]) {
              BBRefs[I]->insertInto(F);
              FunctionBBs[I] = BBRefs[I];
            } else {
              FunctionBBs[I] = BasicBlock::Create(Context, "", F);
            }
  
          // Erase from the table.
          BasicBlockFwdRefs.erase(BBFRI);
        }
  
        CurBB = FunctionBBs[0];
        continue;
      }
  
      case bitc::FUNC_CODE_DEBUG_LOC_AGAIN:  // DEBUG_LOC_AGAIN
        // This record indicates that the last instruction is at the same
        // location as the previous instruction with a location.
        I = getLastInstruction();
  
        if (!I)
          return error("Invalid record");
        I->setDebugLoc(LastLoc);
        I = nullptr;
        continue;
  
      case bitc::FUNC_CODE_DEBUG_LOC: {      // DEBUG_LOC: [line, col, scope, ia]
        I = getLastInstruction();
        if (!I || Record.size() < 4)
          return error("Invalid record");
  
        unsigned Line = Record[0], Col = Record[1];
        unsigned ScopeID = Record[2], IAID = Record[3];
        bool isImplicitCode = Record.size() == 5 && Record[4];
  
        MDNode *Scope = nullptr, *IA = nullptr;
        if (ScopeID) {
          Scope = dyn_cast_or_null<MDNode>(
              MDLoader->getMetadataFwdRefOrLoad(ScopeID - 1));
          if (!Scope)
            return error("Invalid record");
        }
        if (IAID) {
          IA = dyn_cast_or_null<MDNode>(
              MDLoader->getMetadataFwdRefOrLoad(IAID - 1));
          if (!IA)
            return error("Invalid record");
        }
        LastLoc = DebugLoc::get(Line, Col, Scope, IA, isImplicitCode);
        I->setDebugLoc(LastLoc);
        I = nullptr;
        continue;
      }
      case bitc::FUNC_CODE_INST_UNOP: {    // UNOP: [opval, ty, opcode]
        unsigned OpNum = 0;
        Value *LHS;
        if (getValueTypePair(Record, OpNum, NextValueNo, LHS) ||
            OpNum+1 > Record.size())
          return error("Invalid record");
  
        int Opc = getDecodedUnaryOpcode(Record[OpNum++], LHS->getType());
        if (Opc == -1)
          return error("Invalid record");
        I = UnaryOperator::Create((Instruction::UnaryOps)Opc, LHS);
        InstructionList.push_back(I);
        if (OpNum < Record.size()) {
          if (isa<FPMathOperator>(I)) {
            FastMathFlags FMF = getDecodedFastMathFlags(Record[OpNum]);
            if (FMF.any())
              I->setFastMathFlags(FMF);
          }
        }
        break;
      }
      case bitc::FUNC_CODE_INST_BINOP: {    // BINOP: [opval, ty, opval, opcode]
        unsigned OpNum = 0;
        Value *LHS, *RHS;
        if (getValueTypePair(Record, OpNum, NextValueNo, LHS) ||
            popValue(Record, OpNum, NextValueNo, LHS->getType(), RHS) ||
            OpNum+1 > Record.size())
          return error("Invalid record");
  
        int Opc = getDecodedBinaryOpcode(Record[OpNum++], LHS->getType());
        if (Opc == -1)
          return error("Invalid record");
        I = BinaryOperator::Create((Instruction::BinaryOps)Opc, LHS, RHS);
        InstructionList.push_back(I);
        if (OpNum < Record.size()) {
          if (Opc == Instruction::Add ||
              Opc == Instruction::Sub ||
              Opc == Instruction::Mul ||
              Opc == Instruction::Shl) {
            if (Record[OpNum] & (1 << bitc::OBO_NO_SIGNED_WRAP))
              cast<BinaryOperator>(I)->setHasNoSignedWrap(true);
            if (Record[OpNum] & (1 << bitc::OBO_NO_UNSIGNED_WRAP))
              cast<BinaryOperator>(I)->setHasNoUnsignedWrap(true);
          } else if (Opc == Instruction::SDiv ||
                     Opc == Instruction::UDiv ||
                     Opc == Instruction::LShr ||
                     Opc == Instruction::AShr) {
            if (Record[OpNum] & (1 << bitc::PEO_EXACT))
              cast<BinaryOperator>(I)->setIsExact(true);
          } else if (isa<FPMathOperator>(I)) {
            FastMathFlags FMF = getDecodedFastMathFlags(Record[OpNum]);
            if (FMF.any())
              I->setFastMathFlags(FMF);
          }
  
        }
        break;
      }
      case bitc::FUNC_CODE_INST_CAST: {    // CAST: [opval, opty, destty, castopc]
        unsigned OpNum = 0;
        Value *Op;
        if (getValueTypePair(Record, OpNum, NextValueNo, Op) ||
            OpNum+2 != Record.size())
          return error("Invalid record");
  
        FullTy = getFullyStructuredTypeByID(Record[OpNum]);
        Type *ResTy = flattenPointerTypes(FullTy);
        int Opc = getDecodedCastOpcode(Record[OpNum + 1]);
        if (Opc == -1 || !ResTy)
          return error("Invalid record");
        Instruction *Temp = nullptr;
        if ((I = UpgradeBitCastInst(Opc, Op, ResTy, Temp))) {
          if (Temp) {
            InstructionList.push_back(Temp);
            assert(CurBB && "No current BB?");
            CurBB->getInstList().push_back(Temp);
          }
        } else {
          auto CastOp = (Instruction::CastOps)Opc;
          if (!CastInst::castIsValid(CastOp, Op, ResTy))
            return error("Invalid cast");
          I = CastInst::Create(CastOp, Op, ResTy);
        }
        InstructionList.push_back(I);
        break;
      }
      case bitc::FUNC_CODE_INST_INBOUNDS_GEP_OLD:
      case bitc::FUNC_CODE_INST_GEP_OLD:
      case bitc::FUNC_CODE_INST_GEP: { // GEP: type, [n x operands]
        unsigned OpNum = 0;
  
        Type *Ty;
        bool InBounds;
  
        if (BitCode == bitc::FUNC_CODE_INST_GEP) {
          InBounds = Record[OpNum++];
          FullTy = getFullyStructuredTypeByID(Record[OpNum++]);
          Ty = flattenPointerTypes(FullTy);
        } else {
          InBounds = BitCode == bitc::FUNC_CODE_INST_INBOUNDS_GEP_OLD;
          Ty = nullptr;
        }
  
        Value *BasePtr;
        Type *FullBaseTy = nullptr;
        if (getValueTypePair(Record, OpNum, NextValueNo, BasePtr, &FullBaseTy))
          return error("Invalid record");
  
        if (!Ty) {
          std::tie(FullTy, Ty) =
              getPointerElementTypes(FullBaseTy->getScalarType());
        } else if (Ty != getPointerElementFlatType(FullBaseTy->getScalarType()))
          return error(
              "Explicit gep type does not match pointee type of pointer operand");
  
        SmallVector<Value*, 16> GEPIdx;
        while (OpNum != Record.size()) {
          Value *Op;
          if (getValueTypePair(Record, OpNum, NextValueNo, Op))
            return error("Invalid record");
          GEPIdx.push_back(Op);
        }
  
        I = GetElementPtrInst::Create(Ty, BasePtr, GEPIdx);
        FullTy = GetElementPtrInst::getGEPReturnType(FullTy, I, GEPIdx);
  
        InstructionList.push_back(I);
        if (InBounds)
          cast<GetElementPtrInst>(I)->setIsInBounds(true);
        break;
      }
  
      case bitc::FUNC_CODE_INST_EXTRACTVAL: {
                                         // EXTRACTVAL: [opty, opval, n x indices]
        unsigned OpNum = 0;
        Value *Agg;
        if (getValueTypePair(Record, OpNum, NextValueNo, Agg, &FullTy))
          return error("Invalid record");
  
        unsigned RecSize = Record.size();
        if (OpNum == RecSize)
          return error("EXTRACTVAL: Invalid instruction with 0 indices");
  
        SmallVector<unsigned, 4> EXTRACTVALIdx;
        for (; OpNum != RecSize; ++OpNum) {
          bool IsArray = FullTy->isArrayTy();
          bool IsStruct = FullTy->isStructTy();
          uint64_t Index = Record[OpNum];
  
          if (!IsStruct && !IsArray)
            return error("EXTRACTVAL: Invalid type");
          if ((unsigned)Index != Index)
            return error("Invalid value");
          if (IsStruct && Index >= FullTy->getStructNumElements())
            return error("EXTRACTVAL: Invalid struct index");
          if (IsArray && Index >= FullTy->getArrayNumElements())
            return error("EXTRACTVAL: Invalid array index");
          EXTRACTVALIdx.push_back((unsigned)Index);
  
          if (IsStruct)
            FullTy = FullTy->getStructElementType(Index);
          else
            FullTy = FullTy->getArrayElementType();
        }
  
        I = ExtractValueInst::Create(Agg, EXTRACTVALIdx);
        InstructionList.push_back(I);
        break;
      }
  
      case bitc::FUNC_CODE_INST_INSERTVAL: {
                             // INSERTVAL: [opty, opval, opty, opval, n x indices]
        unsigned OpNum = 0;
        Value *Agg;
        if (getValueTypePair(Record, OpNum, NextValueNo, Agg, &FullTy))
          return error("Invalid record");
        Value *Val;
        if (getValueTypePair(Record, OpNum, NextValueNo, Val))
          return error("Invalid record");
  
        unsigned RecSize = Record.size();
        if (OpNum == RecSize)
          return error("INSERTVAL: Invalid instruction with 0 indices");
  
        SmallVector<unsigned, 4> INSERTVALIdx;
        Type *CurTy = Agg->getType();
        for (; OpNum != RecSize; ++OpNum) {
          bool IsArray = CurTy->isArrayTy();
          bool IsStruct = CurTy->isStructTy();
          uint64_t Index = Record[OpNum];
  
          if (!IsStruct && !IsArray)
            return error("INSERTVAL: Invalid type");
          if ((unsigned)Index != Index)
            return error("Invalid value");
          if (IsStruct && Index >= CurTy->getStructNumElements())
            return error("INSERTVAL: Invalid struct index");
          if (IsArray && Index >= CurTy->getArrayNumElements())
            return error("INSERTVAL: Invalid array index");
  
          INSERTVALIdx.push_back((unsigned)Index);
          if (IsStruct)
            CurTy = CurTy->getStructElementType(Index);
          else
            CurTy = CurTy->getArrayElementType();
        }
  
        if (CurTy != Val->getType())
          return error("Inserted value type doesn't match aggregate type");
  
        I = InsertValueInst::Create(Agg, Val, INSERTVALIdx);
        InstructionList.push_back(I);
        break;
      }
  
      case bitc::FUNC_CODE_INST_SELECT: { // SELECT: [opval, ty, opval, opval]
        // obsolete form of select
        // handles select i1 ... in old bitcode
        unsigned OpNum = 0;
        Value *TrueVal, *FalseVal, *Cond;
        if (getValueTypePair(Record, OpNum, NextValueNo, TrueVal, &FullTy) ||
            popValue(Record, OpNum, NextValueNo, TrueVal->getType(), FalseVal) ||
            popValue(Record, OpNum, NextValueNo, Type::getInt1Ty(Context), Cond))
          return error("Invalid record");
  
        I = SelectInst::Create(Cond, TrueVal, FalseVal);
        InstructionList.push_back(I);
        break;
      }
  
      case bitc::FUNC_CODE_INST_VSELECT: {// VSELECT: [ty,opval,opval,predty,pred]
        // new form of select
        // handles select i1 or select [N x i1]
        unsigned OpNum = 0;
        Value *TrueVal, *FalseVal, *Cond;
        if (getValueTypePair(Record, OpNum, NextValueNo, TrueVal, &FullTy) ||
            popValue(Record, OpNum, NextValueNo, TrueVal->getType(), FalseVal) ||
            getValueTypePair(Record, OpNum, NextValueNo, Cond))
          return error("Invalid record");
  
        // select condition can be either i1 or [N x i1]
        if (VectorType* vector_type =
            dyn_cast<VectorType>(Cond->getType())) {
          // expect <n x i1>
          if (vector_type->getElementType() != Type::getInt1Ty(Context))
            return error("Invalid type for value");
        } else {
          // expect i1
          if (Cond->getType() != Type::getInt1Ty(Context))
            return error("Invalid type for value");
        }
  
        I = SelectInst::Create(Cond, TrueVal, FalseVal);
        InstructionList.push_back(I);
        if (OpNum < Record.size() && isa<FPMathOperator>(I)) {
          FastMathFlags FMF = getDecodedFastMathFlags(Record[OpNum]);
          if (FMF.any())
            I->setFastMathFlags(FMF);
        }
        break;
      }
  
      case bitc::FUNC_CODE_INST_EXTRACTELT: { // EXTRACTELT: [opty, opval, opval]
        unsigned OpNum = 0;
        Value *Vec, *Idx;
        if (getValueTypePair(Record, OpNum, NextValueNo, Vec, &FullTy) ||
            getValueTypePair(Record, OpNum, NextValueNo, Idx))
          return error("Invalid record");
        if (!Vec->getType()->isVectorTy())
          return error("Invalid type for value");
        I = ExtractElementInst::Create(Vec, Idx);
        FullTy = cast<VectorType>(FullTy)->getElementType();
        InstructionList.push_back(I);
        break;
      }
  
      case bitc::FUNC_CODE_INST_INSERTELT: { // INSERTELT: [ty, opval,opval,opval]
        unsigned OpNum = 0;
        Value *Vec, *Elt, *Idx;
        if (getValueTypePair(Record, OpNum, NextValueNo, Vec, &FullTy))
          return error("Invalid record");
        if (!Vec->getType()->isVectorTy())
          return error("Invalid type for value");
        if (popValue(Record, OpNum, NextValueNo,
                     cast<VectorType>(Vec->getType())->getElementType(), Elt) ||
            getValueTypePair(Record, OpNum, NextValueNo, Idx))
          return error("Invalid record");
        I = InsertElementInst::Create(Vec, Elt, Idx);
        InstructionList.push_back(I);
        break;
      }
  
      case bitc::FUNC_CODE_INST_SHUFFLEVEC: {// SHUFFLEVEC: [opval,ty,opval,opval]
        unsigned OpNum = 0;
        Value *Vec1, *Vec2, *Mask;
        if (getValueTypePair(Record, OpNum, NextValueNo, Vec1, &FullTy) ||
            popValue(Record, OpNum, NextValueNo, Vec1->getType(), Vec2))
          return error("Invalid record");
  
        if (getValueTypePair(Record, OpNum, NextValueNo, Mask))
          return error("Invalid record");
        if (!Vec1->getType()->isVectorTy() || !Vec2->getType()->isVectorTy())
          return error("Invalid type for value");
  
        I = new ShuffleVectorInst(Vec1, Vec2, Mask);
        FullTy =
            VectorType::get(cast<VectorType>(FullTy)->getElementType(),
                            cast<VectorType>(Mask->getType())->getElementCount());
        InstructionList.push_back(I);
        break;
      }
  
      case bitc::FUNC_CODE_INST_CMP:   // CMP: [opty, opval, opval, pred]
        // Old form of ICmp/FCmp returning bool
        // Existed to differentiate between icmp/fcmp and vicmp/vfcmp which were
        // both legal on vectors but had different behaviour.
      case bitc::FUNC_CODE_INST_CMP2: { // CMP2: [opty, opval, opval, pred]
        // FCmp/ICmp returning bool or vector of bool
  
        unsigned OpNum = 0;
        Value *LHS, *RHS;
        if (getValueTypePair(Record, OpNum, NextValueNo, LHS) ||
            popValue(Record, OpNum, NextValueNo, LHS->getType(), RHS))
          return error("Invalid record");
  
        if (OpNum >= Record.size())
          return error(
              "Invalid record: operand number exceeded available operands");
  
        unsigned PredVal = Record[OpNum];
        bool IsFP = LHS->getType()->isFPOrFPVectorTy();
        FastMathFlags FMF;
        if (IsFP && Record.size() > OpNum+1)
          FMF = getDecodedFastMathFlags(Record[++OpNum]);
  
        if (OpNum+1 != Record.size())
          return error("Invalid record");
  
        if (LHS->getType()->isFPOrFPVectorTy())
          I = new FCmpInst((FCmpInst::Predicate)PredVal, LHS, RHS);
        else
          I = new ICmpInst((ICmpInst::Predicate)PredVal, LHS, RHS);
  
        if (FMF.any())
          I->setFastMathFlags(FMF);
        InstructionList.push_back(I);
        break;
      }
  
      case bitc::FUNC_CODE_INST_RET: // RET: [opty,opval<optional>]
        {
          unsigned Size = Record.size();
          if (Size == 0) {
            I = ReturnInst::Create(Context);
            InstructionList.push_back(I);
            break;
          }
  
          unsigned OpNum = 0;
          Value *Op = nullptr;
          if (getValueTypePair(Record, OpNum, NextValueNo, Op))
            return error("Invalid record");
          if (OpNum != Record.size())
            return error("Invalid record");
  
          I = ReturnInst::Create(Context, Op);
          InstructionList.push_back(I);
          break;
        }
      case bitc::FUNC_CODE_INST_BR: { // BR: [bb#, bb#, opval] or [bb#]
        if (Record.size() != 1 && Record.size() != 3)
          return error("Invalid record");
        BasicBlock *TrueDest = getBasicBlock(Record[0]);
        if (!TrueDest)
          return error("Invalid record");
  
        if (Record.size() == 1) {
          I = BranchInst::Create(TrueDest);
          InstructionList.push_back(I);
        }
        else {
          BasicBlock *FalseDest = getBasicBlock(Record[1]);
          Value *Cond = getValue(Record, 2, NextValueNo,
                                 Type::getInt1Ty(Context));
          if (!FalseDest || !Cond)
            return error("Invalid record");
          I = BranchInst::Create(TrueDest, FalseDest, Cond);
          InstructionList.push_back(I);
        }
        break;
      }
      case bitc::FUNC_CODE_INST_CLEANUPRET: { // CLEANUPRET: [val] or [val,bb#]
        if (Record.size() != 1 && Record.size() != 2)
          return error("Invalid record");
        unsigned Idx = 0;
        Value *CleanupPad =
            getValue(Record, Idx++, NextValueNo, Type::getTokenTy(Context));
        if (!CleanupPad)
          return error("Invalid record");
        BasicBlock *UnwindDest = nullptr;
        if (Record.size() == 2) {
          UnwindDest = getBasicBlock(Record[Idx++]);
          if (!UnwindDest)
            return error("Invalid record");
        }
  
        I = CleanupReturnInst::Create(CleanupPad, UnwindDest);
        InstructionList.push_back(I);
        break;
      }
      case bitc::FUNC_CODE_INST_CATCHRET: { // CATCHRET: [val,bb#]
        if (Record.size() != 2)
          return error("Invalid record");
        unsigned Idx = 0;
        Value *CatchPad =
            getValue(Record, Idx++, NextValueNo, Type::getTokenTy(Context));
        if (!CatchPad)
          return error("Invalid record");
        BasicBlock *BB = getBasicBlock(Record[Idx++]);
        if (!BB)
          return error("Invalid record");
  
        I = CatchReturnInst::Create(CatchPad, BB);
        InstructionList.push_back(I);
        break;
      }
      case bitc::FUNC_CODE_INST_CATCHSWITCH: { // CATCHSWITCH: [tok,num,(bb)*,bb?]
        // We must have, at minimum, the outer scope and the number of arguments.
        if (Record.size() < 2)
          return error("Invalid record");
  
        unsigned Idx = 0;
  
        Value *ParentPad =
            getValue(Record, Idx++, NextValueNo, Type::getTokenTy(Context));
  
        unsigned NumHandlers = Record[Idx++];
  
        SmallVector<BasicBlock *, 2> Handlers;
        for (unsigned Op = 0; Op != NumHandlers; ++Op) {
          BasicBlock *BB = getBasicBlock(Record[Idx++]);
          if (!BB)
            return error("Invalid record");
          Handlers.push_back(BB);
        }
  
        BasicBlock *UnwindDest = nullptr;
        if (Idx + 1 == Record.size()) {
          UnwindDest = getBasicBlock(Record[Idx++]);
          if (!UnwindDest)
            return error("Invalid record");
        }
  
        if (Record.size() != Idx)
          return error("Invalid record");
  
        auto *CatchSwitch =
            CatchSwitchInst::Create(ParentPad, UnwindDest, NumHandlers);
        for (BasicBlock *Handler : Handlers)
          CatchSwitch->addHandler(Handler);
        I = CatchSwitch;
        InstructionList.push_back(I);
        break;
      }
      case bitc::FUNC_CODE_INST_CATCHPAD:
      case bitc::FUNC_CODE_INST_CLEANUPPAD: { // [tok,num,(ty,val)*]
        // We must have, at minimum, the outer scope and the number of arguments.
        if (Record.size() < 2)
          return error("Invalid record");
  
        unsigned Idx = 0;
  
        Value *ParentPad =
            getValue(Record, Idx++, NextValueNo, Type::getTokenTy(Context));
  
        unsigned NumArgOperands = Record[Idx++];
  
        SmallVector<Value *, 2> Args;
        for (unsigned Op = 0; Op != NumArgOperands; ++Op) {
          Value *Val;
          if (getValueTypePair(Record, Idx, NextValueNo, Val))
            return error("Invalid record");
          Args.push_back(Val);
        }
  
        if (Record.size() != Idx)
          return error("Invalid record");
  
        if (BitCode == bitc::FUNC_CODE_INST_CLEANUPPAD)
          I = CleanupPadInst::Create(ParentPad, Args);
        else
          I = CatchPadInst::Create(ParentPad, Args);
        InstructionList.push_back(I);
        break;
      }
      case bitc::FUNC_CODE_INST_SWITCH: { // SWITCH: [opty, op0, op1, ...]
        // Check magic
        if ((Record[0] >> 16) == SWITCH_INST_MAGIC) {
          // "New" SwitchInst format with case ranges. The changes to write this
          // format were reverted but we still recognize bitcode that uses it.
          // Hopefully someday we will have support for case ranges and can use
          // this format again.
  
          Type *OpTy = getTypeByID(Record[1]);
          unsigned ValueBitWidth = cast<IntegerType>(OpTy)->getBitWidth();
  
          Value *Cond = getValue(Record, 2, NextValueNo, OpTy);
          BasicBlock *Default = getBasicBlock(Record[3]);
          if (!OpTy || !Cond || !Default)
            return error("Invalid record");
  
          unsigned NumCases = Record[4];
  
          SwitchInst *SI = SwitchInst::Create(Cond, Default, NumCases);
          InstructionList.push_back(SI);
  
          unsigned CurIdx = 5;
          for (unsigned i = 0; i != NumCases; ++i) {
            SmallVector<ConstantInt*, 1> CaseVals;
            unsigned NumItems = Record[CurIdx++];
            for (unsigned ci = 0; ci != NumItems; ++ci) {
              bool isSingleNumber = Record[CurIdx++];
  
              APInt Low;
              unsigned ActiveWords = 1;
              if (ValueBitWidth > 64)
                ActiveWords = Record[CurIdx++];
              Low = readWideAPInt(makeArrayRef(&Record[CurIdx], ActiveWords),
                                  ValueBitWidth);
              CurIdx += ActiveWords;
  
              if (!isSingleNumber) {
                ActiveWords = 1;
                if (ValueBitWidth > 64)
                  ActiveWords = Record[CurIdx++];
                APInt High = readWideAPInt(
                    makeArrayRef(&Record[CurIdx], ActiveWords), ValueBitWidth);
                CurIdx += ActiveWords;
  
                // FIXME: It is not clear whether values in the range should be
                // compared as signed or unsigned values. The partially
                // implemented changes that used this format in the past used
                // unsigned comparisons.
                for ( ; Low.ule(High); ++Low)
                  CaseVals.push_back(ConstantInt::get(Context, Low));
              } else
                CaseVals.push_back(ConstantInt::get(Context, Low));
            }
            BasicBlock *DestBB = getBasicBlock(Record[CurIdx++]);
            for (SmallVector<ConstantInt*, 1>::iterator cvi = CaseVals.begin(),
                   cve = CaseVals.end(); cvi != cve; ++cvi)
              SI->addCase(*cvi, DestBB);
          }
          I = SI;
          break;
        }
  
        // Old SwitchInst format without case ranges.
  
        if (Record.size() < 3 || (Record.size() & 1) == 0)
          return error("Invalid record");
        Type *OpTy = getTypeByID(Record[0]);
        Value *Cond = getValue(Record, 1, NextValueNo, OpTy);
        BasicBlock *Default = getBasicBlock(Record[2]);
        if (!OpTy || !Cond || !Default)
          return error("Invalid record");
        unsigned NumCases = (Record.size()-3)/2;
        SwitchInst *SI = SwitchInst::Create(Cond, Default, NumCases);
        InstructionList.push_back(SI);
        for (unsigned i = 0, e = NumCases; i != e; ++i) {
          ConstantInt *CaseVal =
            dyn_cast_or_null<ConstantInt>(getFnValueByID(Record[3+i*2], OpTy));
          BasicBlock *DestBB = getBasicBlock(Record[1+3+i*2]);
          if (!CaseVal || !DestBB) {
            delete SI;
            return error("Invalid record");
          }
          SI->addCase(CaseVal, DestBB);
        }
        I = SI;
        break;
      }
      case bitc::FUNC_CODE_INST_INDIRECTBR: { // INDIRECTBR: [opty, op0, op1, ...]
        if (Record.size() < 2)
          return error("Invalid record");
        Type *OpTy = getTypeByID(Record[0]);
        Value *Address = getValue(Record, 1, NextValueNo, OpTy);
        if (!OpTy || !Address)
          return error("Invalid record");
        unsigned NumDests = Record.size()-2;
        IndirectBrInst *IBI = IndirectBrInst::Create(Address, NumDests);
        InstructionList.push_back(IBI);
        for (unsigned i = 0, e = NumDests; i != e; ++i) {
          if (BasicBlock *DestBB = getBasicBlock(Record[2+i])) {
            IBI->addDestination(DestBB);
          } else {
            delete IBI;
            return error("Invalid record");
          }
        }
        I = IBI;
        break;
      }
  
      case bitc::FUNC_CODE_INST_INVOKE: {
        // INVOKE: [attrs, cc, normBB, unwindBB, fnty, op0,op1,op2, ...]
        if (Record.size() < 4)
          return error("Invalid record");
        unsigned OpNum = 0;
        AttributeList PAL = getAttributes(Record[OpNum++]);
        unsigned CCInfo = Record[OpNum++];
        BasicBlock *NormalBB = getBasicBlock(Record[OpNum++]);
        BasicBlock *UnwindBB = getBasicBlock(Record[OpNum++]);
  
        FunctionType *FTy = nullptr;
        FunctionType *FullFTy = nullptr;
        if ((CCInfo >> 13) & 1) {
          FullFTy =
              dyn_cast<FunctionType>(getFullyStructuredTypeByID(Record[OpNum++]));
          if (!FullFTy)
            return error("Explicit invoke type is not a function type");
          FTy = cast<FunctionType>(flattenPointerTypes(FullFTy));
        }
  
        Value *Callee;
        if (getValueTypePair(Record, OpNum, NextValueNo, Callee, &FullTy))
          return error("Invalid record");
  
        PointerType *CalleeTy = dyn_cast<PointerType>(Callee->getType());
        if (!CalleeTy)
          return error("Callee is not a pointer");
        if (!FTy) {
          FullFTy =
              dyn_cast<FunctionType>(cast<PointerType>(FullTy)->getElementType());
          if (!FullFTy)
            return error("Callee is not of pointer to function type");
          FTy = cast<FunctionType>(flattenPointerTypes(FullFTy));
        } else if (getPointerElementFlatType(FullTy) != FTy)
          return error("Explicit invoke type does not match pointee type of "
                       "callee operand");
        if (Record.size() < FTy->getNumParams() + OpNum)
          return error("Insufficient operands to call");
  
        SmallVector<Value*, 16> Ops;
        SmallVector<Type *, 16> ArgsFullTys;
        for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i, ++OpNum) {
          Ops.push_back(getValue(Record, OpNum, NextValueNo,
                                 FTy->getParamType(i)));
          ArgsFullTys.push_back(FullFTy->getParamType(i));
          if (!Ops.back())
            return error("Invalid record");
        }
  
        if (!FTy->isVarArg()) {
          if (Record.size() != OpNum)
            return error("Invalid record");
        } else {
          // Read type/value pairs for varargs params.
          while (OpNum != Record.size()) {
            Value *Op;
            Type *FullTy;
            if (getValueTypePair(Record, OpNum, NextValueNo, Op, &FullTy))
              return error("Invalid record");
            Ops.push_back(Op);
            ArgsFullTys.push_back(FullTy);
          }
        }
  
        I = InvokeInst::Create(FTy, Callee, NormalBB, UnwindBB, Ops,
                               OperandBundles);
        FullTy = FullFTy->getReturnType();
        OperandBundles.clear();
        InstructionList.push_back(I);
        cast<InvokeInst>(I)->setCallingConv(
            static_cast<CallingConv::ID>(CallingConv::MaxID & CCInfo));
        cast<InvokeInst>(I)->setAttributes(PAL);
        propagateByValTypes(cast<CallBase>(I), ArgsFullTys);
  
        break;
      }
      case bitc::FUNC_CODE_INST_RESUME: { // RESUME: [opval]
        unsigned Idx = 0;
        Value *Val = nullptr;
        if (getValueTypePair(Record, Idx, NextValueNo, Val))
          return error("Invalid record");
        I = ResumeInst::Create(Val);
        InstructionList.push_back(I);
        break;
      }
      case bitc::FUNC_CODE_INST_CALLBR: {
        // CALLBR: [attr, cc, norm, transfs, fty, fnid, args]
        unsigned OpNum = 0;
        AttributeList PAL = getAttributes(Record[OpNum++]);
        unsigned CCInfo = Record[OpNum++];
  
        BasicBlock *DefaultDest = getBasicBlock(Record[OpNum++]);
        unsigned NumIndirectDests = Record[OpNum++];
        SmallVector<BasicBlock *, 16> IndirectDests;
        for (unsigned i = 0, e = NumIndirectDests; i != e; ++i)
          IndirectDests.push_back(getBasicBlock(Record[OpNum++]));
  
        FunctionType *FTy = nullptr;
        FunctionType *FullFTy = nullptr;
        if ((CCInfo >> bitc::CALL_EXPLICIT_TYPE) & 1) {
          FullFTy =
              dyn_cast<FunctionType>(getFullyStructuredTypeByID(Record[OpNum++]));
          if (!FullFTy)
            return error("Explicit call type is not a function type");
          FTy = cast<FunctionType>(flattenPointerTypes(FullFTy));
        }
  
        Value *Callee;
        if (getValueTypePair(Record, OpNum, NextValueNo, Callee, &FullTy))
          return error("Invalid record");
  
        PointerType *OpTy = dyn_cast<PointerType>(Callee->getType());
        if (!OpTy)
          return error("Callee is not a pointer type");
        if (!FTy) {
          FullFTy =
              dyn_cast<FunctionType>(cast<PointerType>(FullTy)->getElementType());
          if (!FullFTy)
            return error("Callee is not of pointer to function type");
          FTy = cast<FunctionType>(flattenPointerTypes(FullFTy));
        } else if (getPointerElementFlatType(FullTy) != FTy)
          return error("Explicit call type does not match pointee type of "
                       "callee operand");
        if (Record.size() < FTy->getNumParams() + OpNum)
          return error("Insufficient operands to call");
  
        SmallVector<Value*, 16> Args;
        // Read the fixed params.
        for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i, ++OpNum) {
          if (FTy->getParamType(i)->isLabelTy())
            Args.push_back(getBasicBlock(Record[OpNum]));
          else
            Args.push_back(getValue(Record, OpNum, NextValueNo,
                                    FTy->getParamType(i)));
          if (!Args.back())
            return error("Invalid record");
        }
  
        // Read type/value pairs for varargs params.
        if (!FTy->isVarArg()) {
          if (OpNum != Record.size())
            return error("Invalid record");
        } else {
          while (OpNum != Record.size()) {
            Value *Op;
            if (getValueTypePair(Record, OpNum, NextValueNo, Op))
              return error("Invalid record");
            Args.push_back(Op);
          }
        }
  
        I = CallBrInst::Create(FTy, Callee, DefaultDest, IndirectDests, Args,
                               OperandBundles);
        FullTy = FullFTy->getReturnType();
        OperandBundles.clear();
        InstructionList.push_back(I);
        cast<CallBrInst>(I)->setCallingConv(
            static_cast<CallingConv::ID>((0x7ff & CCInfo) >> bitc::CALL_CCONV));
        cast<CallBrInst>(I)->setAttributes(PAL);
        break;
      }
      case bitc::FUNC_CODE_INST_UNREACHABLE: // UNREACHABLE
        I = new UnreachableInst(Context);
        InstructionList.push_back(I);
        break;
      case bitc::FUNC_CODE_INST_PHI: { // PHI: [ty, val0,bb0, ...]
        if (Record.empty())
          return error("Invalid record");
        // The first record specifies the type.
        FullTy = getFullyStructuredTypeByID(Record[0]);
        Type *Ty = flattenPointerTypes(FullTy);
        if (!Ty)
          return error("Invalid record");
  
        // Phi arguments are pairs of records of [value, basic block].
        // There is an optional final record for fast-math-flags if this phi has a
        // floating-point type.
        size_t NumArgs = (Record.size() - 1) / 2;
        PHINode *PN = PHINode::Create(Ty, NumArgs);
        if ((Record.size() - 1) % 2 == 1 && !isa<FPMathOperator>(PN))
          return error("Invalid record");
        InstructionList.push_back(PN);
  
        for (unsigned i = 0; i != NumArgs; i++) {
          Value *V;
          // With the new function encoding, it is possible that operands have
          // negative IDs (for forward references).  Use a signed VBR
          // representation to keep the encoding small.
          if (UseRelativeIDs)
            V = getValueSigned(Record, i * 2 + 1, NextValueNo, Ty);
          else
            V = getValue(Record, i * 2 + 1, NextValueNo, Ty);
          BasicBlock *BB = getBasicBlock(Record[i * 2 + 2]);
          if (!V || !BB)
            return error("Invalid record");
          PN->addIncoming(V, BB);
        }
        I = PN;
  
        // If there are an even number of records, the final record must be FMF.
        if (Record.size() % 2 == 0) {
          assert(isa<FPMathOperator>(I) && "Unexpected phi type");
          FastMathFlags FMF = getDecodedFastMathFlags(Record[Record.size() - 1]);
          if (FMF.any())
            I->setFastMathFlags(FMF);
        }
  
        break;
      }
  
      case bitc::FUNC_CODE_INST_LANDINGPAD:
      case bitc::FUNC_CODE_INST_LANDINGPAD_OLD: {
        // LANDINGPAD: [ty, val, val, num, (id0,val0 ...)?]
        unsigned Idx = 0;
        if (BitCode == bitc::FUNC_CODE_INST_LANDINGPAD) {
          if (Record.size() < 3)
            return error("Invalid record");
        } else {
          assert(BitCode == bitc::FUNC_CODE_INST_LANDINGPAD_OLD);
          if (Record.size() < 4)
            return error("Invalid record");
        }
        FullTy = getFullyStructuredTypeByID(Record[Idx++]);
        Type *Ty = flattenPointerTypes(FullTy);
        if (!Ty)
          return error("Invalid record");
        if (BitCode == bitc::FUNC_CODE_INST_LANDINGPAD_OLD) {
          Value *PersFn = nullptr;
          if (getValueTypePair(Record, Idx, NextValueNo, PersFn))
            return error("Invalid record");
  
          if (!F->hasPersonalityFn())
            F->setPersonalityFn(cast<Constant>(PersFn));
          else if (F->getPersonalityFn() != cast<Constant>(PersFn))
            return error("Personality function mismatch");
        }
  
        bool IsCleanup = !!Record[Idx++];
        unsigned NumClauses = Record[Idx++];
        LandingPadInst *LP = LandingPadInst::Create(Ty, NumClauses);
        LP->setCleanup(IsCleanup);
        for (unsigned J = 0; J != NumClauses; ++J) {
          LandingPadInst::ClauseType CT =
            LandingPadInst::ClauseType(Record[Idx++]); (void)CT;
          Value *Val;
  
          if (getValueTypePair(Record, Idx, NextValueNo, Val)) {
            delete LP;
            return error("Invalid record");
          }
  
          assert((CT != LandingPadInst::Catch ||
                  !isa<ArrayType>(Val->getType())) &&
                 "Catch clause has a invalid type!");
          assert((CT != LandingPadInst::Filter ||
                  isa<ArrayType>(Val->getType())) &&
                 "Filter clause has invalid type!");
          LP->addClause(cast<Constant>(Val));
        }
  
        I = LP;
        InstructionList.push_back(I);
        break;
      }
  
      case bitc::FUNC_CODE_INST_ALLOCA: { // ALLOCA: [instty, opty, op, align]
        if (Record.size() != 4)
          return error("Invalid record");
        using APV = AllocaPackedValues;
        const uint64_t Rec = Record[3];
        const bool InAlloca = Bitfield::get<APV::UsedWithInAlloca>(Rec);
        const bool SwiftError = Bitfield::get<APV::SwiftError>(Rec);
        FullTy = getFullyStructuredTypeByID(Record[0]);
        Type *Ty = flattenPointerTypes(FullTy);
        if (!Bitfield::get<APV::ExplicitType>(Rec)) {
          auto *PTy = dyn_cast_or_null<PointerType>(Ty);
          if (!PTy)
            return error("Old-style alloca with a non-pointer type");
          std::tie(FullTy, Ty) = getPointerElementTypes(FullTy);
        }
        Type *OpTy = getTypeByID(Record[1]);
        Value *Size = getFnValueByID(Record[2], OpTy);
        MaybeAlign Align;
        if (Error Err =
                parseAlignmentValue(Bitfield::get<APV::Align>(Rec), Align)) {
          return Err;
        }
        if (!Ty || !Size)
          return error("Invalid record");
  
        // FIXME: Make this an optional field.
        const DataLayout &DL = TheModule->getDataLayout();
        unsigned AS = DL.getAllocaAddrSpace();
  
        SmallPtrSet<Type *, 4> Visited;
        if (!Align && !Ty->isSized(&Visited))
          return error("alloca of unsized type");
        if (!Align)
          Align = DL.getPrefTypeAlign(Ty);
  
        AllocaInst *AI = new AllocaInst(Ty, AS, Size, *Align);
        AI->setUsedWithInAlloca(InAlloca);
        AI->setSwiftError(SwiftError);
        I = AI;
        FullTy = PointerType::get(FullTy, AS);
        InstructionList.push_back(I);
        break;
      }
      case bitc::FUNC_CODE_INST_LOAD: { // LOAD: [opty, op, align, vol]
        unsigned OpNum = 0;
        Value *Op;
        if (getValueTypePair(Record, OpNum, NextValueNo, Op, &FullTy) ||
            (OpNum + 2 != Record.size() && OpNum + 3 != Record.size()))
          return error("Invalid record");
  
        if (!isa<PointerType>(Op->getType()))
          return error("Load operand is not a pointer type");
  
        Type *Ty = nullptr;
        if (OpNum + 3 == Record.size()) {
          FullTy = getFullyStructuredTypeByID(Record[OpNum++]);
          Ty = flattenPointerTypes(FullTy);
        } else
          std::tie(FullTy, Ty) = getPointerElementTypes(FullTy);
  
        if (Error Err = typeCheckLoadStoreInst(Ty, Op->getType()))
          return Err;
  
        MaybeAlign Align;
        if (Error Err = parseAlignmentValue(Record[OpNum], Align))
          return Err;
        SmallPtrSet<Type *, 4> Visited;
        if (!Align && !Ty->isSized(&Visited))
          return error("load of unsized type");
        if (!Align)
          Align = TheModule->getDataLayout().getABITypeAlign(Ty);
        I = new LoadInst(Ty, Op, "", Record[OpNum + 1], *Align);
        InstructionList.push_back(I);
        break;
      }
      case bitc::FUNC_CODE_INST_LOADATOMIC: {
         // LOADATOMIC: [opty, op, align, vol, ordering, ssid]
        unsigned OpNum = 0;
        Value *Op;
        if (getValueTypePair(Record, OpNum, NextValueNo, Op, &FullTy) ||
            (OpNum + 4 != Record.size() && OpNum + 5 != Record.size()))
          return error("Invalid record");
  
        if (!isa<PointerType>(Op->getType()))
          return error("Load operand is not a pointer type");
  
        Type *Ty = nullptr;
        if (OpNum + 5 == Record.size()) {
          FullTy = getFullyStructuredTypeByID(Record[OpNum++]);
          Ty = flattenPointerTypes(FullTy);
        } else
          std::tie(FullTy, Ty) = getPointerElementTypes(FullTy);
  
        if (Error Err = typeCheckLoadStoreInst(Ty, Op->getType()))
          return Err;
  
        AtomicOrdering Ordering = getDecodedOrdering(Record[OpNum + 2]);
        if (Ordering == AtomicOrdering::NotAtomic ||
            Ordering == AtomicOrdering::Release ||
            Ordering == AtomicOrdering::AcquireRelease)
          return error("Invalid record");
        if (Ordering != AtomicOrdering::NotAtomic && Record[OpNum] == 0)
          return error("Invalid record");
        SyncScope::ID SSID = getDecodedSyncScopeID(Record[OpNum + 3]);
  
        MaybeAlign Align;
        if (Error Err = parseAlignmentValue(Record[OpNum], Align))
          return Err;
        if (!Align)
          return error("Alignment missing from atomic load");
        I = new LoadInst(Ty, Op, "", Record[OpNum + 1], *Align, Ordering, SSID);
        InstructionList.push_back(I);
        break;
      }
      case bitc::FUNC_CODE_INST_STORE:
      case bitc::FUNC_CODE_INST_STORE_OLD: { // STORE2:[ptrty, ptr, val, align, vol]
        unsigned OpNum = 0;
        Value *Val, *Ptr;
        Type *FullTy;
        if (getValueTypePair(Record, OpNum, NextValueNo, Ptr, &FullTy) ||
            (BitCode == bitc::FUNC_CODE_INST_STORE
                 ? getValueTypePair(Record, OpNum, NextValueNo, Val)
                 : popValue(Record, OpNum, NextValueNo,
                            getPointerElementFlatType(FullTy), Val)) ||
            OpNum + 2 != Record.size())
          return error("Invalid record");
  
        if (Error Err = typeCheckLoadStoreInst(Val->getType(), Ptr->getType()))
          return Err;
        MaybeAlign Align;
        if (Error Err = parseAlignmentValue(Record[OpNum], Align))
          return Err;
        SmallPtrSet<Type *, 4> Visited;
        if (!Align && !Val->getType()->isSized(&Visited))
          return error("store of unsized type");
        if (!Align)
          Align = TheModule->getDataLayout().getABITypeAlign(Val->getType());
        I = new StoreInst(Val, Ptr, Record[OpNum + 1], *Align);
        InstructionList.push_back(I);
        break;
      }
      case bitc::FUNC_CODE_INST_STOREATOMIC:
      case bitc::FUNC_CODE_INST_STOREATOMIC_OLD: {
        // STOREATOMIC: [ptrty, ptr, val, align, vol, ordering, ssid]
        unsigned OpNum = 0;
        Value *Val, *Ptr;
        Type *FullTy;
        if (getValueTypePair(Record, OpNum, NextValueNo, Ptr, &FullTy) ||
            !isa<PointerType>(Ptr->getType()) ||
            (BitCode == bitc::FUNC_CODE_INST_STOREATOMIC
                 ? getValueTypePair(Record, OpNum, NextValueNo, Val)
                 : popValue(Record, OpNum, NextValueNo,
                            getPointerElementFlatType(FullTy), Val)) ||
            OpNum + 4 != Record.size())
          return error("Invalid record");
  
        if (Error Err = typeCheckLoadStoreInst(Val->getType(), Ptr->getType()))
          return Err;
        AtomicOrdering Ordering = getDecodedOrdering(Record[OpNum + 2]);
        if (Ordering == AtomicOrdering::NotAtomic ||
            Ordering == AtomicOrdering::Acquire ||
            Ordering == AtomicOrdering::AcquireRelease)
          return error("Invalid record");
        SyncScope::ID SSID = getDecodedSyncScopeID(Record[OpNum + 3]);
        if (Ordering != AtomicOrdering::NotAtomic && Record[OpNum] == 0)
          return error("Invalid record");
  
        MaybeAlign Align;
        if (Error Err = parseAlignmentValue(Record[OpNum], Align))
          return Err;
        if (!Align)
          return error("Alignment missing from atomic store");
        I = new StoreInst(Val, Ptr, Record[OpNum + 1], *Align, Ordering, SSID);
        InstructionList.push_back(I);
        break;
      }
      case bitc::FUNC_CODE_INST_CMPXCHG_OLD:
      case bitc::FUNC_CODE_INST_CMPXCHG: {
        // CMPXCHG:[ptrty, ptr, cmp, new, vol, successordering, ssid,
        //          failureordering?, isweak?]
        unsigned OpNum = 0;
        Value *Ptr, *Cmp, *New;
        if (getValueTypePair(Record, OpNum, NextValueNo, Ptr, &FullTy))
          return error("Invalid record");
  
        if (!isa<PointerType>(Ptr->getType()))
          return error("Cmpxchg operand is not a pointer type");
  
        if (BitCode == bitc::FUNC_CODE_INST_CMPXCHG) {
          if (getValueTypePair(Record, OpNum, NextValueNo, Cmp, &FullTy))
            return error("Invalid record");
        } else if (popValue(Record, OpNum, NextValueNo,
                            getPointerElementFlatType(FullTy), Cmp))
          return error("Invalid record");
        else
          FullTy = cast<PointerType>(FullTy)->getElementType();
  
        if (popValue(Record, OpNum, NextValueNo, Cmp->getType(), New) ||
            Record.size() < OpNum + 3 || Record.size() > OpNum + 5)
          return error("Invalid record");
  
        AtomicOrdering SuccessOrdering = getDecodedOrdering(Record[OpNum + 1]);
        if (SuccessOrdering == AtomicOrdering::NotAtomic ||
            SuccessOrdering == AtomicOrdering::Unordered)
          return error("Invalid record");
        SyncScope::ID SSID = getDecodedSyncScopeID(Record[OpNum + 2]);
  
        if (Error Err = typeCheckLoadStoreInst(Cmp->getType(), Ptr->getType()))
          return Err;
        AtomicOrdering FailureOrdering;
        if (Record.size() < 7)
          FailureOrdering =
              AtomicCmpXchgInst::getStrongestFailureOrdering(SuccessOrdering);
        else
          FailureOrdering = getDecodedOrdering(Record[OpNum + 3]);
  
        Align Alignment(
            TheModule->getDataLayout().getTypeStoreSize(Cmp->getType()));
        I = new AtomicCmpXchgInst(Ptr, Cmp, New, Alignment, SuccessOrdering,
                                  FailureOrdering, SSID);
        FullTy = StructType::get(Context, {FullTy, Type::getInt1Ty(Context)});
        cast<AtomicCmpXchgInst>(I)->setVolatile(Record[OpNum]);
  
        if (Record.size() < 8) {
          // Before weak cmpxchgs existed, the instruction simply returned the
          // value loaded from memory, so bitcode files from that era will be
          // expecting the first component of a modern cmpxchg.
          CurBB->getInstList().push_back(I);
          I = ExtractValueInst::Create(I, 0);
          FullTy = cast<StructType>(FullTy)->getElementType(0);
        } else {
          cast<AtomicCmpXchgInst>(I)->setWeak(Record[OpNum+4]);
        }
  
        InstructionList.push_back(I);
        break;
      }
      case bitc::FUNC_CODE_INST_ATOMICRMW: {
        // ATOMICRMW:[ptrty, ptr, val, op, vol, ordering, ssid]
        unsigned OpNum = 0;
        Value *Ptr, *Val;
        if (getValueTypePair(Record, OpNum, NextValueNo, Ptr, &FullTy) ||
            !isa<PointerType>(Ptr->getType()) ||
            popValue(Record, OpNum, NextValueNo,
                     getPointerElementFlatType(FullTy), Val) ||
            OpNum + 4 != Record.size())
          return error("Invalid record");
        AtomicRMWInst::BinOp Operation = getDecodedRMWOperation(Record[OpNum]);
        if (Operation < AtomicRMWInst::FIRST_BINOP ||
            Operation > AtomicRMWInst::LAST_BINOP)
          return error("Invalid record");
        AtomicOrdering Ordering = getDecodedOrdering(Record[OpNum + 2]);
        if (Ordering == AtomicOrdering::NotAtomic ||
            Ordering == AtomicOrdering::Unordered)
          return error("Invalid record");
        SyncScope::ID SSID = getDecodedSyncScopeID(Record[OpNum + 3]);
        Align Alignment(
            TheModule->getDataLayout().getTypeStoreSize(Val->getType()));
        I = new AtomicRMWInst(Operation, Ptr, Val, Alignment, Ordering, SSID);
        FullTy = getPointerElementFlatType(FullTy);
        cast<AtomicRMWInst>(I)->setVolatile(Record[OpNum+1]);
        InstructionList.push_back(I);
        break;
      }
      case bitc::FUNC_CODE_INST_FENCE: { // FENCE:[ordering, ssid]
        if (2 != Record.size())
          return error("Invalid record");
        AtomicOrdering Ordering = getDecodedOrdering(Record[0]);
        if (Ordering == AtomicOrdering::NotAtomic ||
            Ordering == AtomicOrdering::Unordered ||
            Ordering == AtomicOrdering::Monotonic)
          return error("Invalid record");
        SyncScope::ID SSID = getDecodedSyncScopeID(Record[1]);
        I = new FenceInst(Context, Ordering, SSID);
        InstructionList.push_back(I);
        break;
      }
      case bitc::FUNC_CODE_INST_CALL: {
        // CALL: [paramattrs, cc, fmf, fnty, fnid, arg0, arg1...]
        if (Record.size() < 3)
          return error("Invalid record");
  
        unsigned OpNum = 0;
        AttributeList PAL = getAttributes(Record[OpNum++]);
        unsigned CCInfo = Record[OpNum++];
  
        FastMathFlags FMF;
        if ((CCInfo >> bitc::CALL_FMF) & 1) {
          FMF = getDecodedFastMathFlags(Record[OpNum++]);
          if (!FMF.any())
            return error("Fast math flags indicator set for call with no FMF");
        }
  
        FunctionType *FTy = nullptr;
        FunctionType *FullFTy = nullptr;
        if ((CCInfo >> bitc::CALL_EXPLICIT_TYPE) & 1) {
          FullFTy =
              dyn_cast<FunctionType>(getFullyStructuredTypeByID(Record[OpNum++]));
          if (!FullFTy)
            return error("Explicit call type is not a function type");
          FTy = cast<FunctionType>(flattenPointerTypes(FullFTy));
        }
  
        Value *Callee;
        if (getValueTypePair(Record, OpNum, NextValueNo, Callee, &FullTy))
          return error("Invalid record");
  
        PointerType *OpTy = dyn_cast<PointerType>(Callee->getType());
        if (!OpTy)
          return error("Callee is not a pointer type");
        if (!FTy) {
          FullFTy =
              dyn_cast<FunctionType>(cast<PointerType>(FullTy)->getElementType());
          if (!FullFTy)
            return error("Callee is not of pointer to function type");
          FTy = cast<FunctionType>(flattenPointerTypes(FullFTy));
        } else if (getPointerElementFlatType(FullTy) != FTy)
          return error("Explicit call type does not match pointee type of "
                       "callee operand");
        if (Record.size() < FTy->getNumParams() + OpNum)
          return error("Insufficient operands to call");
  
        SmallVector<Value*, 16> Args;
        SmallVector<Type*, 16> ArgsFullTys;
        // Read the fixed params.
        for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i, ++OpNum) {
          if (FTy->getParamType(i)->isLabelTy())
            Args.push_back(getBasicBlock(Record[OpNum]));
          else
            Args.push_back(getValue(Record, OpNum, NextValueNo,
                                    FTy->getParamType(i)));
          ArgsFullTys.push_back(FullFTy->getParamType(i));
          if (!Args.back())
            return error("Invalid record");
        }
  
        // Read type/value pairs for varargs params.
        if (!FTy->isVarArg()) {
          if (OpNum != Record.size())
            return error("Invalid record");
        } else {
          while (OpNum != Record.size()) {
            Value *Op;
            Type *FullTy;
            if (getValueTypePair(Record, OpNum, NextValueNo, Op, &FullTy))
              return error("Invalid record");
            Args.push_back(Op);
            ArgsFullTys.push_back(FullTy);
          }
        }
  
        I = CallInst::Create(FTy, Callee, Args, OperandBundles);
        FullTy = FullFTy->getReturnType();
        OperandBundles.clear();
        InstructionList.push_back(I);
        cast<CallInst>(I)->setCallingConv(
            static_cast<CallingConv::ID>((0x7ff & CCInfo) >> bitc::CALL_CCONV));
        CallInst::TailCallKind TCK = CallInst::TCK_None;
        if (CCInfo & 1 << bitc::CALL_TAIL)
          TCK = CallInst::TCK_Tail;
        if (CCInfo & (1 << bitc::CALL_MUSTTAIL))
          TCK = CallInst::TCK_MustTail;
        if (CCInfo & (1 << bitc::CALL_NOTAIL))
          TCK = CallInst::TCK_NoTail;
        cast<CallInst>(I)->setTailCallKind(TCK);
        cast<CallInst>(I)->setAttributes(PAL);
        propagateByValTypes(cast<CallBase>(I), ArgsFullTys);
        if (FMF.any()) {
          if (!isa<FPMathOperator>(I))
            return error("Fast-math-flags specified for call without "
                         "floating-point scalar or vector return type");
          I->setFastMathFlags(FMF);
        }
        break;
      }
      case bitc::FUNC_CODE_INST_VAARG: { // VAARG: [valistty, valist, instty]
        if (Record.size() < 3)
          return error("Invalid record");
        Type *OpTy = getTypeByID(Record[0]);
        Value *Op = getValue(Record, 1, NextValueNo, OpTy);
        FullTy = getFullyStructuredTypeByID(Record[2]);
        Type *ResTy = flattenPointerTypes(FullTy);
        if (!OpTy || !Op || !ResTy)
          return error("Invalid record");
        I = new VAArgInst(Op, ResTy);
        InstructionList.push_back(I);
        break;
      }
  
      case bitc::FUNC_CODE_OPERAND_BUNDLE: {
        // A call or an invoke can be optionally prefixed with some variable
        // number of operand bundle blocks.  These blocks are read into
        // OperandBundles and consumed at the next call or invoke instruction.
  
        if (Record.empty() || Record[0] >= BundleTags.size())
          return error("Invalid record");
  
        std::vector<Value *> Inputs;
  
        unsigned OpNum = 1;
        while (OpNum != Record.size()) {
          Value *Op;
          if (getValueTypePair(Record, OpNum, NextValueNo, Op))
            return error("Invalid record");
          Inputs.push_back(Op);
        }
  
        OperandBundles.emplace_back(BundleTags[Record[0]], std::move(Inputs));
        continue;
      }
  
      case bitc::FUNC_CODE_INST_FREEZE: { // FREEZE: [opty,opval]
        unsigned OpNum = 0;
        Value *Op = nullptr;
        if (getValueTypePair(Record, OpNum, NextValueNo, Op, &FullTy))
          return error("Invalid record");
        if (OpNum != Record.size())
          return error("Invalid record");
  
        I = new FreezeInst(Op);
        InstructionList.push_back(I);
        break;
      }
      }
  
      // Add instruction to end of current BB.  If there is no current BB, reject
      // this file.
      if (!CurBB) {
        I->deleteValue();
        return error("Invalid instruction with no BB");
      }
      if (!OperandBundles.empty()) {
        I->deleteValue();
        return error("Operand bundles found with no consumer");
      }
      CurBB->getInstList().push_back(I);
  
      // If this was a terminator instruction, move to the next block.
      if (I->isTerminator()) {
        ++CurBBNo;
        CurBB = CurBBNo < FunctionBBs.size() ? FunctionBBs[CurBBNo] : nullptr;
      }
  
      // Non-void values get registered in the value table for future use.
      if (!I->getType()->isVoidTy()) {
        if (!FullTy) {
          FullTy = I->getType();
          assert(
              !FullTy->isPointerTy() && !isa<StructType>(FullTy) &&
              !isa<ArrayType>(FullTy) &&
              (!isa<VectorType>(FullTy) ||
               cast<VectorType>(FullTy)->getElementType()->isFloatingPointTy() ||
               cast<VectorType>(FullTy)->getElementType()->isIntegerTy()) &&
              "Structured types must be assigned with corresponding non-opaque "
              "pointer type");
        }
  
        assert(I->getType() == flattenPointerTypes(FullTy) &&
               "Incorrect fully structured type provided for Instruction");
        ValueList.assignValue(I, NextValueNo++, FullTy);
      }
    }
  
  OutOfRecordLoop:
  
    if (!OperandBundles.empty())
      return error("Operand bundles found with no consumer");
  
    // Check the function list for unresolved values.
    if (Argument *A = dyn_cast<Argument>(ValueList.back())) {
      if (!A->getParent()) {
        // We found at least one unresolved value.  Nuke them all to avoid leaks.
        for (unsigned i = ModuleValueListSize, e = ValueList.size(); i != e; ++i){
          if ((A = dyn_cast_or_null<Argument>(ValueList[i])) && !A->getParent()) {
            A->replaceAllUsesWith(UndefValue::get(A->getType()));
            delete A;
          }
        }
        return error("Never resolved value found in function");
      }
    }
  
    // Unexpected unresolved metadata about to be dropped.
    if (MDLoader->hasFwdRefs())
      return error("Invalid function metadata: outgoing forward refs");
  
    // Trim the value list down to the size it was before we parsed this function.
    ValueList.shrinkTo(ModuleValueListSize);
    MDLoader->shrinkTo(ModuleMDLoaderSize);
    std::vector<BasicBlock*>().swap(FunctionBBs);
    return Error::success();
  }
  
  /// Find the function body in the bitcode stream
  Error BitcodeReader::findFunctionInStream(
      Function *F,
      DenseMap<Function *, uint64_t>::iterator DeferredFunctionInfoIterator) {
    while (DeferredFunctionInfoIterator->second == 0) {
      // This is the fallback handling for the old format bitcode that
      // didn't contain the function index in the VST, or when we have
      // an anonymous function which would not have a VST entry.
      // Assert that we have one of those two cases.
      assert(VSTOffset == 0 || !F->hasName());
      // Parse the next body in the stream and set its position in the
      // DeferredFunctionInfo map.
      if (Error Err = rememberAndSkipFunctionBodies())
        return Err;
    }
    return Error::success();
  }
  
  SyncScope::ID BitcodeReader::getDecodedSyncScopeID(unsigned Val) {
    if (Val == SyncScope::SingleThread || Val == SyncScope::System)
      return SyncScope::ID(Val);
    if (Val >= SSIDs.size())
      return SyncScope::System; // Map unknown synchronization scopes to system.
    return SSIDs[Val];
  }
  
  //===----------------------------------------------------------------------===//
  // GVMaterializer implementation
  //===----------------------------------------------------------------------===//
  
  Error BitcodeReader::materialize(GlobalValue *GV) {
    Function *F = dyn_cast<Function>(GV);
    // If it's not a function or is already material, ignore the request.
    if (!F || !F->isMaterializable())
      return Error::success();
  
    DenseMap<Function*, uint64_t>::iterator DFII = DeferredFunctionInfo.find(F);
    assert(DFII != DeferredFunctionInfo.end() && "Deferred function not found!");
    // If its position is recorded as 0, its body is somewhere in the stream
    // but we haven't seen it yet.
    if (DFII->second == 0)
      if (Error Err = findFunctionInStream(F, DFII))
        return Err;
  
    // Materialize metadata before parsing any function bodies.
    if (Error Err = materializeMetadata())
      return Err;
  
    // Move the bit stream to the saved position of the deferred function body.
    if (Error JumpFailed = Stream.JumpToBit(DFII->second))
      return JumpFailed;
    if (Error Err = parseFunctionBody(F))
      return Err;
    F->setIsMaterializable(false);
  
    if (StripDebugInfo)
      stripDebugInfo(*F);
  
    // Upgrade any old intrinsic calls in the function.
    for (auto &I : UpgradedIntrinsics) {
      for (auto UI = I.first->materialized_user_begin(), UE = I.first->user_end();
           UI != UE;) {
        User *U = *UI;
        ++UI;
        if (CallInst *CI = dyn_cast<CallInst>(U))
          UpgradeIntrinsicCall(CI, I.second);
      }
    }
  
    // Update calls to the remangled intrinsics
    for (auto &I : RemangledIntrinsics)
      for (auto UI = I.first->materialized_user_begin(), UE = I.first->user_end();
           UI != UE;)
        // Don't expect any other users than call sites
        cast<CallBase>(*UI++)->setCalledFunction(I.second);
  
    // Finish fn->subprogram upgrade for materialized functions.
    if (DISubprogram *SP = MDLoader->lookupSubprogramForFunction(F))
      F->setSubprogram(SP);
  
    // Check if the TBAA Metadata are valid, otherwise we will need to strip them.
    if (!MDLoader->isStrippingTBAA()) {
      for (auto &I : instructions(F)) {
        MDNode *TBAA = I.getMetadata(LLVMContext::MD_tbaa);
        if (!TBAA || TBAAVerifyHelper.visitTBAAMetadata(I, TBAA))
          continue;
        MDLoader->setStripTBAA(true);
        stripTBAA(F->getParent());
      }
    }
  
    // "Upgrade" older incorrect branch weights by dropping them.
    for (auto &I : instructions(F)) {
      if (auto *MD = I.getMetadata(LLVMContext::MD_prof)) {
        if (MD->getOperand(0) != nullptr && isa<MDString>(MD->getOperand(0))) {
          MDString *MDS = cast<MDString>(MD->getOperand(0));
          StringRef ProfName = MDS->getString();
          // Check consistency of !prof branch_weights metadata.
          if (!ProfName.equals("branch_weights"))
            continue;
          unsigned ExpectedNumOperands = 0;
          if (BranchInst *BI = dyn_cast<BranchInst>(&I))
            ExpectedNumOperands = BI->getNumSuccessors();
          else if (SwitchInst *SI = dyn_cast<SwitchInst>(&I))
            ExpectedNumOperands = SI->getNumSuccessors();
          else if (isa<CallInst>(&I))
            ExpectedNumOperands = 1;
          else if (IndirectBrInst *IBI = dyn_cast<IndirectBrInst>(&I))
            ExpectedNumOperands = IBI->getNumDestinations();
          else if (isa<SelectInst>(&I))
            ExpectedNumOperands = 2;
          else
            continue; // ignore and continue.
  
          // If branch weight doesn't match, just strip branch weight.
          if (MD->getNumOperands() != 1 + ExpectedNumOperands)
            I.setMetadata(LLVMContext::MD_prof, nullptr);
        }
      }
    }
  
    // Look for functions that rely on old function attribute behavior.
    UpgradeFunctionAttributes(*F);
  
    // Bring in any functions that this function forward-referenced via
    // blockaddresses.
    return materializeForwardReferencedFunctions();
  }
  
  Error BitcodeReader::materializeModule() {
    if (Error Err = materializeMetadata())
      return Err;
  
    // Promise to materialize all forward references.
    WillMaterializeAllForwardRefs = true;
  
    // Iterate over the module, deserializing any functions that are still on
    // disk.
    for (Function &F : *TheModule) {
      if (Error Err = materialize(&F))
        return Err;
    }
    // At this point, if there are any function bodies, parse the rest of
    // the bits in the module past the last function block we have recorded
    // through either lazy scanning or the VST.
    if (LastFunctionBlockBit || NextUnreadBit)
      if (Error Err = parseModule(LastFunctionBlockBit > NextUnreadBit
                                      ? LastFunctionBlockBit
                                      : NextUnreadBit))
        return Err;
  
    // Check that all block address forward references got resolved (as we
    // promised above).
    if (!BasicBlockFwdRefs.empty())
      return error("Never resolved function from blockaddress");
  
    // Upgrade any intrinsic calls that slipped through (should not happen!) and
    // delete the old functions to clean up. We can't do this unless the entire
    // module is materialized because there could always be another function body
    // with calls to the old function.
    for (auto &I : UpgradedIntrinsics) {
      for (auto *U : I.first->users()) {
        if (CallInst *CI = dyn_cast<CallInst>(U))
          UpgradeIntrinsicCall(CI, I.second);
      }
      if (!I.first->use_empty())
        I.first->replaceAllUsesWith(I.second);
      I.first->eraseFromParent();
    }
    UpgradedIntrinsics.clear();
    // Do the same for remangled intrinsics
    for (auto &I : RemangledIntrinsics) {
      I.first->replaceAllUsesWith(I.second);
      I.first->eraseFromParent();
    }
    RemangledIntrinsics.clear();
  
    UpgradeDebugInfo(*TheModule);
  
    UpgradeModuleFlags(*TheModule);
  
    UpgradeARCRuntime(*TheModule);
  
    return Error::success();
  }
  
  std::vector<StructType *> BitcodeReader::getIdentifiedStructTypes() const {
    return IdentifiedStructTypes;
  }
  
  ModuleSummaryIndexBitcodeReader::ModuleSummaryIndexBitcodeReader(
      BitstreamCursor Cursor, StringRef Strtab, ModuleSummaryIndex &TheIndex,
      StringRef ModulePath, unsigned ModuleId)
      : BitcodeReaderBase(std::move(Cursor), Strtab), TheIndex(TheIndex),
        ModulePath(ModulePath), ModuleId(ModuleId) {}
  
  void ModuleSummaryIndexBitcodeReader::addThisModule() {
    TheIndex.addModule(ModulePath, ModuleId);
  }
  
  ModuleSummaryIndex::ModuleInfo *
  ModuleSummaryIndexBitcodeReader::getThisModule() {
    return TheIndex.getModule(ModulePath);
  }
  
  std::pair<ValueInfo, GlobalValue::GUID>
  ModuleSummaryIndexBitcodeReader::getValueInfoFromValueId(unsigned ValueId) {
    auto VGI = ValueIdToValueInfoMap[ValueId];
    assert(VGI.first);
    return VGI;
  }
  
  void ModuleSummaryIndexBitcodeReader::setValueGUID(
      uint64_t ValueID, StringRef ValueName, GlobalValue::LinkageTypes Linkage,
      StringRef SourceFileName) {
    std::string GlobalId =
        GlobalValue::getGlobalIdentifier(ValueName, Linkage, SourceFileName);
    auto ValueGUID = GlobalValue::getGUID(GlobalId);
    auto OriginalNameID = ValueGUID;
    if (GlobalValue::isLocalLinkage(Linkage))
      OriginalNameID = GlobalValue::getGUID(ValueName);
    if (PrintSummaryGUIDs)
      dbgs() << "GUID " << ValueGUID << "(" << OriginalNameID << ") is "
             << ValueName << "\n";
  
    // UseStrtab is false for legacy summary formats and value names are
    // created on stack. In that case we save the name in a string saver in
    // the index so that the value name can be recorded.
    ValueIdToValueInfoMap[ValueID] = std::make_pair(
        TheIndex.getOrInsertValueInfo(
            ValueGUID,
            UseStrtab ? ValueName : TheIndex.saveString(ValueName)),
        OriginalNameID);
  }
  
  // Specialized value symbol table parser used when reading module index
  // blocks where we don't actually create global values. The parsed information
  // is saved in the bitcode reader for use when later parsing summaries.
  Error ModuleSummaryIndexBitcodeReader::parseValueSymbolTable(
      uint64_t Offset,
      DenseMap<unsigned, GlobalValue::LinkageTypes> &ValueIdToLinkageMap) {
    // With a strtab the VST is not required to parse the summary.
    if (UseStrtab)
      return Error::success();
  
    assert(Offset > 0 && "Expected non-zero VST offset");
    Expected<uint64_t> MaybeCurrentBit = jumpToValueSymbolTable(Offset, Stream);
    if (!MaybeCurrentBit)
      return MaybeCurrentBit.takeError();
    uint64_t CurrentBit = MaybeCurrentBit.get();
  
    if (Error Err = Stream.EnterSubBlock(bitc::VALUE_SYMTAB_BLOCK_ID))
      return Err;
  
    SmallVector<uint64_t, 64> Record;
  
    // Read all the records for this value table.
    SmallString<128> ValueName;
  
    while (true) {
      Expected<BitstreamEntry> MaybeEntry = Stream.advanceSkippingSubblocks();
      if (!MaybeEntry)
        return MaybeEntry.takeError();
      BitstreamEntry Entry = MaybeEntry.get();
  
      switch (Entry.Kind) {
      case BitstreamEntry::SubBlock: // Handled for us already.
      case BitstreamEntry::Error:
        return error("Malformed block");
      case BitstreamEntry::EndBlock:
        // Done parsing VST, jump back to wherever we came from.
        if (Error JumpFailed = Stream.JumpToBit(CurrentBit))
          return JumpFailed;
        return Error::success();
      case BitstreamEntry::Record:
        // The interesting case.
        break;
      }
  
      // Read a record.
      Record.clear();
      Expected<unsigned> MaybeRecord = Stream.readRecord(Entry.ID, Record);
      if (!MaybeRecord)
        return MaybeRecord.takeError();
      switch (MaybeRecord.get()) {
      default: // Default behavior: ignore (e.g. VST_CODE_BBENTRY records).
        break;
      case bitc::VST_CODE_ENTRY: { // VST_CODE_ENTRY: [valueid, namechar x N]
        if (convertToString(Record, 1, ValueName))
          return error("Invalid record");
        unsigned ValueID = Record[0];
        assert(!SourceFileName.empty());
        auto VLI = ValueIdToLinkageMap.find(ValueID);
        assert(VLI != ValueIdToLinkageMap.end() &&
               "No linkage found for VST entry?");
        auto Linkage = VLI->second;
        setValueGUID(ValueID, ValueName, Linkage, SourceFileName);
        ValueName.clear();
        break;
      }
      case bitc::VST_CODE_FNENTRY: {
        // VST_CODE_FNENTRY: [valueid, offset, namechar x N]
        if (convertToString(Record, 2, ValueName))
          return error("Invalid record");
        unsigned ValueID = Record[0];
        assert(!SourceFileName.empty());
        auto VLI = ValueIdToLinkageMap.find(ValueID);
        assert(VLI != ValueIdToLinkageMap.end() &&
               "No linkage found for VST entry?");
        auto Linkage = VLI->second;
        setValueGUID(ValueID, ValueName, Linkage, SourceFileName);
        ValueName.clear();
        break;
      }
      case bitc::VST_CODE_COMBINED_ENTRY: {
        // VST_CODE_COMBINED_ENTRY: [valueid, refguid]
        unsigned ValueID = Record[0];
        GlobalValue::GUID RefGUID = Record[1];
        // The "original name", which is the second value of the pair will be
        // overriden later by a FS_COMBINED_ORIGINAL_NAME in the combined index.
        ValueIdToValueInfoMap[ValueID] =
            std::make_pair(TheIndex.getOrInsertValueInfo(RefGUID), RefGUID);
        break;
      }
      }
    }
  }
  
  // Parse just the blocks needed for building the index out of the module.
  // At the end of this routine the module Index is populated with a map
  // from global value id to GlobalValueSummary objects.
  Error ModuleSummaryIndexBitcodeReader::parseModule() {
    if (Error Err = Stream.EnterSubBlock(bitc::MODULE_BLOCK_ID))
      return Err;
  
    SmallVector<uint64_t, 64> Record;
    DenseMap<unsigned, GlobalValue::LinkageTypes> ValueIdToLinkageMap;
    unsigned ValueId = 0;
  
    // Read the index for this module.
    while (true) {
      Expected<llvm::BitstreamEntry> MaybeEntry = Stream.advance();
      if (!MaybeEntry)
        return MaybeEntry.takeError();
      llvm::BitstreamEntry Entry = MaybeEntry.get();
  
      switch (Entry.Kind) {
      case BitstreamEntry::Error:
        return error("Malformed block");
      case BitstreamEntry::EndBlock:
        return Error::success();
  
      case BitstreamEntry::SubBlock:
        switch (Entry.ID) {
        default: // Skip unknown content.
          if (Error Err = Stream.SkipBlock())
            return Err;
          break;
        case bitc::BLOCKINFO_BLOCK_ID:
          // Need to parse these to get abbrev ids (e.g. for VST)
          if (readBlockInfo())
            return error("Malformed block");
          break;
        case bitc::VALUE_SYMTAB_BLOCK_ID:
          // Should have been parsed earlier via VSTOffset, unless there
          // is no summary section.
          assert(((SeenValueSymbolTable && VSTOffset > 0) ||
                  !SeenGlobalValSummary) &&
                 "Expected early VST parse via VSTOffset record");
          if (Error Err = Stream.SkipBlock())
            return Err;
          break;
        case bitc::GLOBALVAL_SUMMARY_BLOCK_ID:
        case bitc::FULL_LTO_GLOBALVAL_SUMMARY_BLOCK_ID:
          // Add the module if it is a per-module index (has a source file name).
          if (!SourceFileName.empty())
            addThisModule();
          assert(!SeenValueSymbolTable &&
                 "Already read VST when parsing summary block?");
          // We might not have a VST if there were no values in the
          // summary. An empty summary block generated when we are
          // performing ThinLTO compiles so we don't later invoke
          // the regular LTO process on them.
          if (VSTOffset > 0) {
            if (Error Err = parseValueSymbolTable(VSTOffset, ValueIdToLinkageMap))
              return Err;
            SeenValueSymbolTable = true;
          }
          SeenGlobalValSummary = true;
          if (Error Err = parseEntireSummary(Entry.ID))
            return Err;
          break;
        case bitc::MODULE_STRTAB_BLOCK_ID:
          if (Error Err = parseModuleStringTable())
            return Err;
          break;
        }
        continue;
  
      case BitstreamEntry::Record: {
          Record.clear();
          Expected<unsigned> MaybeBitCode = Stream.readRecord(Entry.ID, Record);
          if (!MaybeBitCode)
            return MaybeBitCode.takeError();
          switch (MaybeBitCode.get()) {
          default:
            break; // Default behavior, ignore unknown content.
          case bitc::MODULE_CODE_VERSION: {
            if (Error Err = parseVersionRecord(Record).takeError())
              return Err;
            break;
          }
          /// MODULE_CODE_SOURCE_FILENAME: [namechar x N]
          case bitc::MODULE_CODE_SOURCE_FILENAME: {
            SmallString<128> ValueName;
            if (convertToString(Record, 0, ValueName))
              return error("Invalid record");
            SourceFileName = ValueName.c_str();
            break;
          }
          /// MODULE_CODE_HASH: [5*i32]
          case bitc::MODULE_CODE_HASH: {
            if (Record.size() != 5)
              return error("Invalid hash length " + Twine(Record.size()).str());
            auto &Hash = getThisModule()->second.second;
            int Pos = 0;
            for (auto &Val : Record) {
              assert(!(Val >> 32) && "Unexpected high bits set");
              Hash[Pos++] = Val;
            }
            break;
          }
          /// MODULE_CODE_VSTOFFSET: [offset]
          case bitc::MODULE_CODE_VSTOFFSET:
            if (Record.empty())
              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 historically always the start of the regular bitcode header.
            VSTOffset = Record[0] - 1;
            break;
          // v1 GLOBALVAR: [pointer type, isconst,     initid,       linkage, ...]
          // v1 FUNCTION:  [type,         callingconv, isproto,      linkage, ...]
          // v1 ALIAS:     [alias type,   addrspace,   aliasee val#, linkage, ...]
          // v2: [strtab offset, strtab size, v1]
          case bitc::MODULE_CODE_GLOBALVAR:
          case bitc::MODULE_CODE_FUNCTION:
          case bitc::MODULE_CODE_ALIAS: {
            StringRef Name;
            ArrayRef<uint64_t> GVRecord;
            std::tie(Name, GVRecord) = readNameFromStrtab(Record);
            if (GVRecord.size() <= 3)
              return error("Invalid record");
            uint64_t RawLinkage = GVRecord[3];
            GlobalValue::LinkageTypes Linkage = getDecodedLinkage(RawLinkage);
            if (!UseStrtab) {
              ValueIdToLinkageMap[ValueId++] = Linkage;
              break;
            }
  
            setValueGUID(ValueId++, Name, Linkage, SourceFileName);
            break;
          }
          }
        }
        continue;
      }
    }
  }
  
  std::vector<ValueInfo>
  ModuleSummaryIndexBitcodeReader::makeRefList(ArrayRef<uint64_t> Record) {
    std::vector<ValueInfo> Ret;
    Ret.reserve(Record.size());
    for (uint64_t RefValueId : Record)
      Ret.push_back(getValueInfoFromValueId(RefValueId).first);
    return Ret;
  }
  
  std::vector<FunctionSummary::EdgeTy>
  ModuleSummaryIndexBitcodeReader::makeCallList(ArrayRef<uint64_t> Record,
                                                bool IsOldProfileFormat,
                                                bool HasProfile, bool HasRelBF) {
    std::vector<FunctionSummary::EdgeTy> Ret;
    Ret.reserve(Record.size());
    for (unsigned I = 0, E = Record.size(); I != E; ++I) {
      CalleeInfo::HotnessType Hotness = CalleeInfo::HotnessType::Unknown;
      uint64_t RelBF = 0;
      ValueInfo Callee = getValueInfoFromValueId(Record[I]).first;
      if (IsOldProfileFormat) {
        I += 1; // Skip old callsitecount field
        if (HasProfile)
          I += 1; // Skip old profilecount field
      } else if (HasProfile)
        Hotness = static_cast<CalleeInfo::HotnessType>(Record[++I]);
      else if (HasRelBF)
        RelBF = Record[++I];
      Ret.push_back(FunctionSummary::EdgeTy{Callee, CalleeInfo(Hotness, RelBF)});
    }
    return Ret;
  }
  
  static void
  parseWholeProgramDevirtResolutionByArg(ArrayRef<uint64_t> Record, size_t &Slot,
                                         WholeProgramDevirtResolution &Wpd) {
    uint64_t ArgNum = Record[Slot++];
    WholeProgramDevirtResolution::ByArg &B =
        Wpd.ResByArg[{Record.begin() + Slot, Record.begin() + Slot + ArgNum}];
    Slot += ArgNum;
  
    B.TheKind =
        static_cast<WholeProgramDevirtResolution::ByArg::Kind>(Record[Slot++]);
    B.Info = Record[Slot++];
    B.Byte = Record[Slot++];
    B.Bit = Record[Slot++];
  }
  
  static void parseWholeProgramDevirtResolution(ArrayRef<uint64_t> Record,
                                                StringRef Strtab, size_t &Slot,
                                                TypeIdSummary &TypeId) {
    uint64_t Id = Record[Slot++];
    WholeProgramDevirtResolution &Wpd = TypeId.WPDRes[Id];
  
    Wpd.TheKind = static_cast<WholeProgramDevirtResolution::Kind>(Record[Slot++]);
    Wpd.SingleImplName = {Strtab.data() + Record[Slot],
                          static_cast<size_t>(Record[Slot + 1])};
    Slot += 2;
  
    uint64_t ResByArgNum = Record[Slot++];
    for (uint64_t I = 0; I != ResByArgNum; ++I)
      parseWholeProgramDevirtResolutionByArg(Record, Slot, Wpd);
  }
  
  static void parseTypeIdSummaryRecord(ArrayRef<uint64_t> Record,
                                       StringRef Strtab,
                                       ModuleSummaryIndex &TheIndex) {
    size_t Slot = 0;
    TypeIdSummary &TypeId = TheIndex.getOrInsertTypeIdSummary(
        {Strtab.data() + Record[Slot], static_cast<size_t>(Record[Slot + 1])});
    Slot += 2;
  
    TypeId.TTRes.TheKind = static_cast<TypeTestResolution::Kind>(Record[Slot++]);
    TypeId.TTRes.SizeM1BitWidth = Record[Slot++];
    TypeId.TTRes.AlignLog2 = Record[Slot++];
    TypeId.TTRes.SizeM1 = Record[Slot++];
    TypeId.TTRes.BitMask = Record[Slot++];
    TypeId.TTRes.InlineBits = Record[Slot++];
  
    while (Slot < Record.size())
      parseWholeProgramDevirtResolution(Record, Strtab, Slot, TypeId);
  }
  
  static std::vector<FunctionSummary::ParamAccess>
  parseParamAccesses(ArrayRef<uint64_t> Record) {
    auto ReadRange = [&]() {
      APInt Lower(FunctionSummary::ParamAccess::RangeWidth,
                  BitcodeReader::decodeSignRotatedValue(Record.front()));
      Record = Record.drop_front();
      APInt Upper(FunctionSummary::ParamAccess::RangeWidth,
                  BitcodeReader::decodeSignRotatedValue(Record.front()));
      Record = Record.drop_front();
      ConstantRange Range{Lower, Upper};
      assert(!Range.isFullSet());
      assert(!Range.isUpperSignWrapped());
      return Range;
    };
  
    std::vector<FunctionSummary::ParamAccess> PendingParamAccesses;
    while (!Record.empty()) {
      PendingParamAccesses.emplace_back();
      FunctionSummary::ParamAccess &ParamAccess = PendingParamAccesses.back();
      ParamAccess.ParamNo = Record.front();
      Record = Record.drop_front();
      ParamAccess.Use = ReadRange();
      ParamAccess.Calls.resize(Record.front());
      Record = Record.drop_front();
      for (auto &Call : ParamAccess.Calls) {
        Call.ParamNo = Record.front();
        Record = Record.drop_front();
        Call.Callee = Record.front();
        Record = Record.drop_front();
        Call.Offsets = ReadRange();
      }
    }
    return PendingParamAccesses;
  }
  
  void ModuleSummaryIndexBitcodeReader::parseTypeIdCompatibleVtableInfo(
      ArrayRef<uint64_t> Record, size_t &Slot,
      TypeIdCompatibleVtableInfo &TypeId) {
    uint64_t Offset = Record[Slot++];
    ValueInfo Callee = getValueInfoFromValueId(Record[Slot++]).first;
    TypeId.push_back({Offset, Callee});
  }
  
  void ModuleSummaryIndexBitcodeReader::parseTypeIdCompatibleVtableSummaryRecord(
      ArrayRef<uint64_t> Record) {
    size_t Slot = 0;
    TypeIdCompatibleVtableInfo &TypeId =
        TheIndex.getOrInsertTypeIdCompatibleVtableSummary(
            {Strtab.data() + Record[Slot],
             static_cast<size_t>(Record[Slot + 1])});
    Slot += 2;
  
    while (Slot < Record.size())
      parseTypeIdCompatibleVtableInfo(Record, Slot, TypeId);
  }
  
  static void setSpecialRefs(std::vector<ValueInfo> &Refs, unsigned ROCnt,
                             unsigned WOCnt) {
    // Readonly and writeonly refs are in the end of the refs list.
    assert(ROCnt + WOCnt <= Refs.size());
    unsigned FirstWORef = Refs.size() - WOCnt;
    unsigned RefNo = FirstWORef - ROCnt;
    for (; RefNo < FirstWORef; ++RefNo)
      Refs[RefNo].setReadOnly();
    for (; RefNo < Refs.size(); ++RefNo)
      Refs[RefNo].setWriteOnly();
  }
  
  // Eagerly parse the entire summary block. This populates the GlobalValueSummary
  // objects in the index.
  Error ModuleSummaryIndexBitcodeReader::parseEntireSummary(unsigned ID) {
    if (Error Err = Stream.EnterSubBlock(ID))
      return Err;
    SmallVector<uint64_t, 64> Record;
  
    // Parse version
    {
      Expected<BitstreamEntry> MaybeEntry = Stream.advanceSkippingSubblocks();
      if (!MaybeEntry)
        return MaybeEntry.takeError();
      BitstreamEntry Entry = MaybeEntry.get();
  
      if (Entry.Kind != BitstreamEntry::Record)
        return error("Invalid Summary Block: record for version expected");
      Expected<unsigned> MaybeRecord = Stream.readRecord(Entry.ID, Record);
      if (!MaybeRecord)
        return MaybeRecord.takeError();
      if (MaybeRecord.get() != bitc::FS_VERSION)
        return error("Invalid Summary Block: version expected");
    }
    const uint64_t Version = Record[0];
    const bool IsOldProfileFormat = Version == 1;
    if (Version < 1 || Version > ModuleSummaryIndex::BitcodeSummaryVersion)
      return error("Invalid summary version " + Twine(Version) +
                   ". Version should be in the range [1-" +
                   Twine(ModuleSummaryIndex::BitcodeSummaryVersion) +
                   "].");
    Record.clear();
  
    // Keep around the last seen summary to be used when we see an optional
    // "OriginalName" attachement.
    GlobalValueSummary *LastSeenSummary = nullptr;
    GlobalValue::GUID LastSeenGUID = 0;
  
    // We can expect to see any number of type ID information records before
    // each function summary records; these variables store the information
    // collected so far so that it can be used to create the summary object.
    std::vector<GlobalValue::GUID> PendingTypeTests;
    std::vector<FunctionSummary::VFuncId> PendingTypeTestAssumeVCalls,
        PendingTypeCheckedLoadVCalls;
    std::vector<FunctionSummary::ConstVCall> PendingTypeTestAssumeConstVCalls,
        PendingTypeCheckedLoadConstVCalls;
    std::vector<FunctionSummary::ParamAccess> PendingParamAccesses;
  
    while (true) {
      Expected<BitstreamEntry> MaybeEntry = Stream.advanceSkippingSubblocks();
      if (!MaybeEntry)
        return MaybeEntry.takeError();
      BitstreamEntry Entry = MaybeEntry.get();
  
      switch (Entry.Kind) {
      case BitstreamEntry::SubBlock: // Handled for us already.
      case BitstreamEntry::Error:
        return error("Malformed block");
      case BitstreamEntry::EndBlock:
        return Error::success();
      case BitstreamEntry::Record:
        // The interesting case.
        break;
      }
  
      // Read a record. The record format depends on whether this
      // is a per-module index or a combined index file. In the per-module
      // case the records contain the associated value's ID for correlation
      // with VST entries. In the combined index the correlation is done
      // via the bitcode offset of the summary records (which were saved
      // in the combined index VST entries). The records also contain
      // information used for ThinLTO renaming and importing.
      Record.clear();
      Expected<unsigned> MaybeBitCode = Stream.readRecord(Entry.ID, Record);
      if (!MaybeBitCode)
        return MaybeBitCode.takeError();
      switch (unsigned BitCode = MaybeBitCode.get()) {
      default: // Default behavior: ignore.
        break;
      case bitc::FS_FLAGS: {  // [flags]
        TheIndex.setFlags(Record[0]);
        break;
      }
      case bitc::FS_VALUE_GUID: { // [valueid, refguid]
        uint64_t ValueID = Record[0];
        GlobalValue::GUID RefGUID = Record[1];
        ValueIdToValueInfoMap[ValueID] =
            std::make_pair(TheIndex.getOrInsertValueInfo(RefGUID), RefGUID);
        break;
      }
      // FS_PERMODULE: [valueid, flags, instcount, fflags, numrefs,
      //                numrefs x valueid, n x (valueid)]
      // FS_PERMODULE_PROFILE: [valueid, flags, instcount, fflags, numrefs,
      //                        numrefs x valueid,
      //                        n x (valueid, hotness)]
      // FS_PERMODULE_RELBF: [valueid, flags, instcount, fflags, numrefs,
      //                      numrefs x valueid,
      //                      n x (valueid, relblockfreq)]
      case bitc::FS_PERMODULE:
      case bitc::FS_PERMODULE_RELBF:
      case bitc::FS_PERMODULE_PROFILE: {
        unsigned ValueID = Record[0];
        uint64_t RawFlags = Record[1];
        unsigned InstCount = Record[2];
        uint64_t RawFunFlags = 0;
        unsigned NumRefs = Record[3];
        unsigned NumRORefs = 0, NumWORefs = 0;
        int RefListStartIndex = 4;
        if (Version >= 4) {
          RawFunFlags = Record[3];
          NumRefs = Record[4];
          RefListStartIndex = 5;
          if (Version >= 5) {
            NumRORefs = Record[5];
            RefListStartIndex = 6;
            if (Version >= 7) {
              NumWORefs = Record[6];
              RefListStartIndex = 7;
            }
          }
        }
  
        auto Flags = getDecodedGVSummaryFlags(RawFlags, Version);
        // The module path string ref set in the summary must be owned by the
        // index's module string table. Since we don't have a module path
        // string table section in the per-module index, we create a single
        // module path string table entry with an empty (0) ID to take
        // ownership.
        int CallGraphEdgeStartIndex = RefListStartIndex + NumRefs;
        assert(Record.size() >= RefListStartIndex + NumRefs &&
               "Record size inconsistent with number of references");
        std::vector<ValueInfo> Refs = makeRefList(
            ArrayRef<uint64_t>(Record).slice(RefListStartIndex, NumRefs));
        bool HasProfile = (BitCode == bitc::FS_PERMODULE_PROFILE);
        bool HasRelBF = (BitCode == bitc::FS_PERMODULE_RELBF);
        std::vector<FunctionSummary::EdgeTy> Calls = makeCallList(
            ArrayRef<uint64_t>(Record).slice(CallGraphEdgeStartIndex),
            IsOldProfileFormat, HasProfile, HasRelBF);
        setSpecialRefs(Refs, NumRORefs, NumWORefs);
        auto FS = std::make_unique<FunctionSummary>(
            Flags, InstCount, getDecodedFFlags(RawFunFlags), /*EntryCount=*/0,
            std::move(Refs), std::move(Calls), std::move(PendingTypeTests),
            std::move(PendingTypeTestAssumeVCalls),
            std::move(PendingTypeCheckedLoadVCalls),
            std::move(PendingTypeTestAssumeConstVCalls),
            std::move(PendingTypeCheckedLoadConstVCalls),
            std::move(PendingParamAccesses));
        auto VIAndOriginalGUID = getValueInfoFromValueId(ValueID);
        FS->setModulePath(getThisModule()->first());
        FS->setOriginalName(VIAndOriginalGUID.second);
        TheIndex.addGlobalValueSummary(VIAndOriginalGUID.first, std::move(FS));
        break;
      }
      // FS_ALIAS: [valueid, flags, valueid]
      // Aliases must be emitted (and parsed) after all FS_PERMODULE entries, as
      // they expect all aliasee summaries to be available.
      case bitc::FS_ALIAS: {
        unsigned ValueID = Record[0];
        uint64_t RawFlags = Record[1];
        unsigned AliaseeID = Record[2];
        auto Flags = getDecodedGVSummaryFlags(RawFlags, Version);
        auto AS = std::make_unique<AliasSummary>(Flags);
        // The module path string ref set in the summary must be owned by the
        // index's module string table. Since we don't have a module path
        // string table section in the per-module index, we create a single
        // module path string table entry with an empty (0) ID to take
        // ownership.
        AS->setModulePath(getThisModule()->first());
  
        auto AliaseeVI = getValueInfoFromValueId(AliaseeID).first;
        auto AliaseeInModule = TheIndex.findSummaryInModule(AliaseeVI, ModulePath);
        if (!AliaseeInModule)
          return error("Alias expects aliasee summary to be parsed");
        AS->setAliasee(AliaseeVI, AliaseeInModule);
  
        auto GUID = getValueInfoFromValueId(ValueID);
        AS->setOriginalName(GUID.second);
        TheIndex.addGlobalValueSummary(GUID.first, std::move(AS));
        break;
      }
      // FS_PERMODULE_GLOBALVAR_INIT_REFS: [valueid, flags, varflags, n x valueid]
      case bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS: {
        unsigned ValueID = Record[0];
        uint64_t RawFlags = Record[1];
        unsigned RefArrayStart = 2;
        GlobalVarSummary::GVarFlags GVF(/* ReadOnly */ false,
                                        /* WriteOnly */ false,
                                        /* Constant */ false,
                                        GlobalObject::VCallVisibilityPublic);
        auto Flags = getDecodedGVSummaryFlags(RawFlags, Version);
        if (Version >= 5) {
          GVF = getDecodedGVarFlags(Record[2]);
          RefArrayStart = 3;
        }
        std::vector<ValueInfo> Refs =
            makeRefList(ArrayRef<uint64_t>(Record).slice(RefArrayStart));
        auto FS =
            std::make_unique<GlobalVarSummary>(Flags, GVF, std::move(Refs));
        FS->setModulePath(getThisModule()->first());
        auto GUID = getValueInfoFromValueId(ValueID);
        FS->setOriginalName(GUID.second);
        TheIndex.addGlobalValueSummary(GUID.first, std::move(FS));
        break;
      }
      // FS_PERMODULE_VTABLE_GLOBALVAR_INIT_REFS: [valueid, flags, varflags,
      //                        numrefs, numrefs x valueid,
      //                        n x (valueid, offset)]
      case bitc::FS_PERMODULE_VTABLE_GLOBALVAR_INIT_REFS: {
        unsigned ValueID = Record[0];
        uint64_t RawFlags = Record[1];
        GlobalVarSummary::GVarFlags GVF = getDecodedGVarFlags(Record[2]);
        unsigned NumRefs = Record[3];
        unsigned RefListStartIndex = 4;
        unsigned VTableListStartIndex = RefListStartIndex + NumRefs;
        auto Flags = getDecodedGVSummaryFlags(RawFlags, Version);
        std::vector<ValueInfo> Refs = makeRefList(
            ArrayRef<uint64_t>(Record).slice(RefListStartIndex, NumRefs));
        VTableFuncList VTableFuncs;
        for (unsigned I = VTableListStartIndex, E = Record.size(); I != E; ++I) {
          ValueInfo Callee = getValueInfoFromValueId(Record[I]).first;
          uint64_t Offset = Record[++I];
          VTableFuncs.push_back({Callee, Offset});
        }
        auto VS =
            std::make_unique<GlobalVarSummary>(Flags, GVF, std::move(Refs));
        VS->setModulePath(getThisModule()->first());
        VS->setVTableFuncs(VTableFuncs);
        auto GUID = getValueInfoFromValueId(ValueID);
        VS->setOriginalName(GUID.second);
        TheIndex.addGlobalValueSummary(GUID.first, std::move(VS));
        break;
      }
      // FS_COMBINED: [valueid, modid, flags, instcount, fflags, numrefs,
      //               numrefs x valueid, n x (valueid)]
      // FS_COMBINED_PROFILE: [valueid, modid, flags, instcount, fflags, numrefs,
      //                       numrefs x valueid, n x (valueid, hotness)]
      case bitc::FS_COMBINED:
      case bitc::FS_COMBINED_PROFILE: {
        unsigned ValueID = Record[0];
        uint64_t ModuleId = Record[1];
        uint64_t RawFlags = Record[2];
        unsigned InstCount = Record[3];
        uint64_t RawFunFlags = 0;
        uint64_t EntryCount = 0;
        unsigned NumRefs = Record[4];
        unsigned NumRORefs = 0, NumWORefs = 0;
        int RefListStartIndex = 5;
  
        if (Version >= 4) {
          RawFunFlags = Record[4];
          RefListStartIndex = 6;
          size_t NumRefsIndex = 5;
          if (Version >= 5) {
            unsigned NumRORefsOffset = 1;
            RefListStartIndex = 7;
            if (Version >= 6) {
              NumRefsIndex = 6;
              EntryCount = Record[5];
              RefListStartIndex = 8;
              if (Version >= 7) {
                RefListStartIndex = 9;
                NumWORefs = Record[8];
                NumRORefsOffset = 2;
              }
            }
            NumRORefs = Record[RefListStartIndex - NumRORefsOffset];
          }
          NumRefs = Record[NumRefsIndex];
        }
  
        auto Flags = getDecodedGVSummaryFlags(RawFlags, Version);
        int CallGraphEdgeStartIndex = RefListStartIndex + NumRefs;
        assert(Record.size() >= RefListStartIndex + NumRefs &&
               "Record size inconsistent with number of references");
        std::vector<ValueInfo> Refs = makeRefList(
            ArrayRef<uint64_t>(Record).slice(RefListStartIndex, NumRefs));
        bool HasProfile = (BitCode == bitc::FS_COMBINED_PROFILE);
        std::vector<FunctionSummary::EdgeTy> Edges = makeCallList(
            ArrayRef<uint64_t>(Record).slice(CallGraphEdgeStartIndex),
            IsOldProfileFormat, HasProfile, false);
        ValueInfo VI = getValueInfoFromValueId(ValueID).first;
        setSpecialRefs(Refs, NumRORefs, NumWORefs);
        auto FS = std::make_unique<FunctionSummary>(
            Flags, InstCount, getDecodedFFlags(RawFunFlags), EntryCount,
            std::move(Refs), std::move(Edges), std::move(PendingTypeTests),
            std::move(PendingTypeTestAssumeVCalls),
            std::move(PendingTypeCheckedLoadVCalls),
            std::move(PendingTypeTestAssumeConstVCalls),
            std::move(PendingTypeCheckedLoadConstVCalls),
            std::move(PendingParamAccesses));
        LastSeenSummary = FS.get();
        LastSeenGUID = VI.getGUID();
        FS->setModulePath(ModuleIdMap[ModuleId]);
        TheIndex.addGlobalValueSummary(VI, std::move(FS));
        break;
      }
      // FS_COMBINED_ALIAS: [valueid, modid, flags, valueid]
      // Aliases must be emitted (and parsed) after all FS_COMBINED entries, as
      // they expect all aliasee summaries to be available.
      case bitc::FS_COMBINED_ALIAS: {
        unsigned ValueID = Record[0];
        uint64_t ModuleId = Record[1];
        uint64_t RawFlags = Record[2];
        unsigned AliaseeValueId = Record[3];
        auto Flags = getDecodedGVSummaryFlags(RawFlags, Version);
        auto AS = std::make_unique<AliasSummary>(Flags);
        LastSeenSummary = AS.get();
        AS->setModulePath(ModuleIdMap[ModuleId]);
  
        auto AliaseeVI = getValueInfoFromValueId(AliaseeValueId).first;
        auto AliaseeInModule = TheIndex.findSummaryInModule(AliaseeVI, AS->modulePath());
        AS->setAliasee(AliaseeVI, AliaseeInModule);
  
        ValueInfo VI = getValueInfoFromValueId(ValueID).first;
        LastSeenGUID = VI.getGUID();
        TheIndex.addGlobalValueSummary(VI, std::move(AS));
        break;
      }
      // FS_COMBINED_GLOBALVAR_INIT_REFS: [valueid, modid, flags, n x valueid]
      case bitc::FS_COMBINED_GLOBALVAR_INIT_REFS: {
        unsigned ValueID = Record[0];
        uint64_t ModuleId = Record[1];
        uint64_t RawFlags = Record[2];
        unsigned RefArrayStart = 3;
        GlobalVarSummary::GVarFlags GVF(/* ReadOnly */ false,
                                        /* WriteOnly */ false,
                                        /* Constant */ false,
                                        GlobalObject::VCallVisibilityPublic);
        auto Flags = getDecodedGVSummaryFlags(RawFlags, Version);
        if (Version >= 5) {
          GVF = getDecodedGVarFlags(Record[3]);
          RefArrayStart = 4;
        }
        std::vector<ValueInfo> Refs =
            makeRefList(ArrayRef<uint64_t>(Record).slice(RefArrayStart));
        auto FS =
            std::make_unique<GlobalVarSummary>(Flags, GVF, std::move(Refs));
        LastSeenSummary = FS.get();
        FS->setModulePath(ModuleIdMap[ModuleId]);
        ValueInfo VI = getValueInfoFromValueId(ValueID).first;
        LastSeenGUID = VI.getGUID();
        TheIndex.addGlobalValueSummary(VI, std::move(FS));
        break;
      }
      // FS_COMBINED_ORIGINAL_NAME: [original_name]
      case bitc::FS_COMBINED_ORIGINAL_NAME: {
        uint64_t OriginalName = Record[0];
        if (!LastSeenSummary)
          return error("Name attachment that does not follow a combined record");
        LastSeenSummary->setOriginalName(OriginalName);
        TheIndex.addOriginalName(LastSeenGUID, OriginalName);
        // Reset the LastSeenSummary
        LastSeenSummary = nullptr;
        LastSeenGUID = 0;
        break;
      }
      case bitc::FS_TYPE_TESTS:
        assert(PendingTypeTests.empty());
        PendingTypeTests.insert(PendingTypeTests.end(), Record.begin(),
                                Record.end());
        break;
  
      case bitc::FS_TYPE_TEST_ASSUME_VCALLS:
        assert(PendingTypeTestAssumeVCalls.empty());
        for (unsigned I = 0; I != Record.size(); I += 2)
          PendingTypeTestAssumeVCalls.push_back({Record[I], Record[I+1]});
        break;
  
      case bitc::FS_TYPE_CHECKED_LOAD_VCALLS:
        assert(PendingTypeCheckedLoadVCalls.empty());
        for (unsigned I = 0; I != Record.size(); I += 2)
          PendingTypeCheckedLoadVCalls.push_back({Record[I], Record[I+1]});
        break;
  
      case bitc::FS_TYPE_TEST_ASSUME_CONST_VCALL:
        PendingTypeTestAssumeConstVCalls.push_back(
            {{Record[0], Record[1]}, {Record.begin() + 2, Record.end()}});
        break;
  
      case bitc::FS_TYPE_CHECKED_LOAD_CONST_VCALL:
        PendingTypeCheckedLoadConstVCalls.push_back(
            {{Record[0], Record[1]}, {Record.begin() + 2, Record.end()}});
        break;
  
      case bitc::FS_CFI_FUNCTION_DEFS: {
        std::set<std::string> &CfiFunctionDefs = TheIndex.cfiFunctionDefs();
        for (unsigned I = 0; I != Record.size(); I += 2)
          CfiFunctionDefs.insert(
              {Strtab.data() + Record[I], static_cast<size_t>(Record[I + 1])});
        break;
      }
  
      case bitc::FS_CFI_FUNCTION_DECLS: {
        std::set<std::string> &CfiFunctionDecls = TheIndex.cfiFunctionDecls();
        for (unsigned I = 0; I != Record.size(); I += 2)
          CfiFunctionDecls.insert(
              {Strtab.data() + Record[I], static_cast<size_t>(Record[I + 1])});
        break;
      }
  
      case bitc::FS_TYPE_ID:
        parseTypeIdSummaryRecord(Record, Strtab, TheIndex);
        break;
  
      case bitc::FS_TYPE_ID_METADATA:
        parseTypeIdCompatibleVtableSummaryRecord(Record);
        break;
  
      case bitc::FS_BLOCK_COUNT:
        TheIndex.addBlockCount(Record[0]);
        break;
  
      case bitc::FS_PARAM_ACCESS: {
        PendingParamAccesses = parseParamAccesses(Record);
        break;
      }
      }
    }
    llvm_unreachable("Exit infinite loop");
  }
  
  // Parse the  module string table block into the Index.
  // This populates the ModulePathStringTable map in the index.
  Error ModuleSummaryIndexBitcodeReader::parseModuleStringTable() {
    if (Error Err = Stream.EnterSubBlock(bitc::MODULE_STRTAB_BLOCK_ID))
      return Err;
  
    SmallVector<uint64_t, 64> Record;
  
    SmallString<128> ModulePath;
    ModuleSummaryIndex::ModuleInfo *LastSeenModule = nullptr;
  
    while (true) {
      Expected<BitstreamEntry> MaybeEntry = Stream.advanceSkippingSubblocks();
      if (!MaybeEntry)
        return MaybeEntry.takeError();
      BitstreamEntry Entry = MaybeEntry.get();
  
      switch (Entry.Kind) {
      case BitstreamEntry::SubBlock: // Handled for us already.
      case BitstreamEntry::Error:
        return error("Malformed block");
      case BitstreamEntry::EndBlock:
        return Error::success();
      case BitstreamEntry::Record:
        // The interesting case.
        break;
      }
  
      Record.clear();
      Expected<unsigned> MaybeRecord = Stream.readRecord(Entry.ID, Record);
      if (!MaybeRecord)
        return MaybeRecord.takeError();
      switch (MaybeRecord.get()) {
      default: // Default behavior: ignore.
        break;
      case bitc::MST_CODE_ENTRY: {
        // MST_ENTRY: [modid, namechar x N]
        uint64_t ModuleId = Record[0];
  
        if (convertToString(Record, 1, ModulePath))
          return error("Invalid record");
  
        LastSeenModule = TheIndex.addModule(ModulePath, ModuleId);
        ModuleIdMap[ModuleId] = LastSeenModule->first();
  
        ModulePath.clear();
        break;
      }
      /// MST_CODE_HASH: [5*i32]
      case bitc::MST_CODE_HASH: {
        if (Record.size() != 5)
          return error("Invalid hash length " + Twine(Record.size()).str());
        if (!LastSeenModule)
          return error("Invalid hash that does not follow a module path");
        int Pos = 0;
        for (auto &Val : Record) {
          assert(!(Val >> 32) && "Unexpected high bits set");
          LastSeenModule->second.second[Pos++] = Val;
        }
        // Reset LastSeenModule to avoid overriding the hash unexpectedly.
        LastSeenModule = nullptr;
        break;
      }
      }
    }
    llvm_unreachable("Exit infinite loop");
  }
  
  namespace {
  
  // FIXME: This class is only here to support the transition to llvm::Error. It
  // will be removed once this transition is complete. Clients should prefer to
  // deal with the Error value directly, rather than converting to error_code.
  class BitcodeErrorCategoryType : public std::error_category {
    const char *name() const noexcept override {
      return "llvm.bitcode";
    }
  
    std::string message(int IE) const override {
      BitcodeError E = static_cast<BitcodeError>(IE);
      switch (E) {
      case BitcodeError::CorruptedBitcode:
        return "Corrupted bitcode";
      }
      llvm_unreachable("Unknown error type!");
    }
  };
  
  } // end anonymous namespace
  
  static ManagedStatic<BitcodeErrorCategoryType> ErrorCategory;
  
  const std::error_category &llvm::BitcodeErrorCategory() {
    return *ErrorCategory;
  }
  
  static Expected<StringRef> readBlobInRecord(BitstreamCursor &Stream,
                                              unsigned Block, unsigned RecordID) {
    if (Error Err = Stream.EnterSubBlock(Block))
      return std::move(Err);
  
    StringRef Strtab;
    while (true) {
      Expected<llvm::BitstreamEntry> MaybeEntry = Stream.advance();
      if (!MaybeEntry)
        return MaybeEntry.takeError();
      llvm::BitstreamEntry Entry = MaybeEntry.get();
  
      switch (Entry.Kind) {
      case BitstreamEntry::EndBlock:
        return Strtab;
  
      case BitstreamEntry::Error:
        return error("Malformed block");
  
      case BitstreamEntry::SubBlock:
        if (Error Err = Stream.SkipBlock())
          return std::move(Err);
        break;
  
      case BitstreamEntry::Record:
        StringRef Blob;
        SmallVector<uint64_t, 1> Record;
        Expected<unsigned> MaybeRecord =
            Stream.readRecord(Entry.ID, Record, &Blob);
        if (!MaybeRecord)
          return MaybeRecord.takeError();
        if (MaybeRecord.get() == RecordID)
          Strtab = Blob;
        break;
      }
    }
  }
  
  //===----------------------------------------------------------------------===//
  // External interface
  //===----------------------------------------------------------------------===//
  
  Expected<std::vector<BitcodeModule>>
  llvm::getBitcodeModuleList(MemoryBufferRef Buffer) {
    auto FOrErr = getBitcodeFileContents(Buffer);
    if (!FOrErr)
      return FOrErr.takeError();
    return std::move(FOrErr->Mods);
  }
  
  Expected<BitcodeFileContents>
  llvm::getBitcodeFileContents(MemoryBufferRef Buffer) {
    Expected<BitstreamCursor> StreamOrErr = initStream(Buffer);
    if (!StreamOrErr)
      return StreamOrErr.takeError();
    BitstreamCursor &Stream = *StreamOrErr;
  
    BitcodeFileContents F;
    while (true) {
      uint64_t BCBegin = Stream.getCurrentByteNo();
  
      // We may be consuming bitcode from a client that leaves garbage at the end
      // of the bitcode stream (e.g. Apple's ar tool). If we are close enough to
      // the end that there cannot possibly be another module, stop looking.
      if (BCBegin + 8 >= Stream.getBitcodeBytes().size())
        return F;
  
      Expected<llvm::BitstreamEntry> MaybeEntry = Stream.advance();
      if (!MaybeEntry)
        return MaybeEntry.takeError();
      llvm::BitstreamEntry Entry = MaybeEntry.get();
  
      switch (Entry.Kind) {
      case BitstreamEntry::EndBlock:
      case BitstreamEntry::Error:
        return error("Malformed block");
  
      case BitstreamEntry::SubBlock: {
        uint64_t IdentificationBit = -1ull;
        if (Entry.ID == bitc::IDENTIFICATION_BLOCK_ID) {
          IdentificationBit = Stream.GetCurrentBitNo() - BCBegin * 8;
          if (Error Err = Stream.SkipBlock())
            return std::move(Err);
  
          {
            Expected<llvm::BitstreamEntry> MaybeEntry = Stream.advance();
            if (!MaybeEntry)
              return MaybeEntry.takeError();
            Entry = MaybeEntry.get();
          }
  
          if (Entry.Kind != BitstreamEntry::SubBlock ||
              Entry.ID != bitc::MODULE_BLOCK_ID)
            return error("Malformed block");
        }
  
        if (Entry.ID == bitc::MODULE_BLOCK_ID) {
          uint64_t ModuleBit = Stream.GetCurrentBitNo() - BCBegin * 8;
          if (Error Err = Stream.SkipBlock())
            return std::move(Err);
  
          F.Mods.push_back({Stream.getBitcodeBytes().slice(
                                BCBegin, Stream.getCurrentByteNo() - BCBegin),
                            Buffer.getBufferIdentifier(), IdentificationBit,
                            ModuleBit});
          continue;
        }
  
        if (Entry.ID == bitc::STRTAB_BLOCK_ID) {
          Expected<StringRef> Strtab =
              readBlobInRecord(Stream, bitc::STRTAB_BLOCK_ID, bitc::STRTAB_BLOB);
          if (!Strtab)
            return Strtab.takeError();
          // This string table is used by every preceding bitcode module that does
          // not have its own string table. A bitcode file may have multiple
          // string tables if it was created by binary concatenation, for example
          // with "llvm-cat -b".
          for (auto I = F.Mods.rbegin(), E = F.Mods.rend(); I != E; ++I) {
            if (!I->Strtab.empty())
              break;
            I->Strtab = *Strtab;
          }
          // Similarly, the string table is used by every preceding symbol table;
          // normally there will be just one unless the bitcode file was created
          // by binary concatenation.
          if (!F.Symtab.empty() && F.StrtabForSymtab.empty())
            F.StrtabForSymtab = *Strtab;
          continue;
        }
  
        if (Entry.ID == bitc::SYMTAB_BLOCK_ID) {
          Expected<StringRef> SymtabOrErr =
              readBlobInRecord(Stream, bitc::SYMTAB_BLOCK_ID, bitc::SYMTAB_BLOB);
          if (!SymtabOrErr)
            return SymtabOrErr.takeError();
  
          // We can expect the bitcode file to have multiple symbol tables if it
          // was created by binary concatenation. In that case we silently
          // ignore any subsequent symbol tables, which is fine because this is a
          // low level function. The client is expected to notice that the number
          // of modules in the symbol table does not match the number of modules
          // in the input file and regenerate the symbol table.
          if (F.Symtab.empty())
            F.Symtab = *SymtabOrErr;
          continue;
        }
  
        if (Error Err = Stream.SkipBlock())
          return std::move(Err);
        continue;
      }
      case BitstreamEntry::Record:
        if (Expected<unsigned> StreamFailed = Stream.skipRecord(Entry.ID))
          continue;
        else
          return StreamFailed.takeError();
      }
    }
  }
  
  /// Get a lazy one-at-time loading module from bitcode.
  ///
  /// This isn't always used in a lazy context.  In particular, it's also used by
  /// \a parseModule().  If this is truly lazy, then we need to eagerly pull
  /// in forward-referenced functions from block address references.
  ///
  /// \param[in] MaterializeAll Set to \c true if we should materialize
  /// everything.
  Expected<std::unique_ptr<Module>>
  BitcodeModule::getModuleImpl(LLVMContext &Context, bool MaterializeAll,
                               bool ShouldLazyLoadMetadata, bool IsImporting,
                               DataLayoutCallbackTy DataLayoutCallback) {
    BitstreamCursor Stream(Buffer);
  
    std::string ProducerIdentification;
    if (IdentificationBit != -1ull) {
      if (Error JumpFailed = Stream.JumpToBit(IdentificationBit))
        return std::move(JumpFailed);
      Expected<std::string> ProducerIdentificationOrErr =
          readIdentificationBlock(Stream);
      if (!ProducerIdentificationOrErr)
        return ProducerIdentificationOrErr.takeError();
  
      ProducerIdentification = *ProducerIdentificationOrErr;
    }
  
    if (Error JumpFailed = Stream.JumpToBit(ModuleBit))
      return std::move(JumpFailed);
    auto *R = new BitcodeReader(std::move(Stream), Strtab, ProducerIdentification,
                                Context);
  
    std::unique_ptr<Module> M =
        std::make_unique<Module>(ModuleIdentifier, Context);
    M->setMaterializer(R);
  
    // Delay parsing Metadata if ShouldLazyLoadMetadata is true.
    if (Error Err = R->parseBitcodeInto(M.get(), ShouldLazyLoadMetadata,
                                        IsImporting, DataLayoutCallback))
      return std::move(Err);
  
    if (MaterializeAll) {
      // Read in the entire module, and destroy the BitcodeReader.
      if (Error Err = M->materializeAll())
        return std::move(Err);
    } else {
      // Resolve forward references from blockaddresses.
      if (Error Err = R->materializeForwardReferencedFunctions())
        return std::move(Err);
    }
    return std::move(M);
  }
  
  Expected<std::unique_ptr<Module>>
  BitcodeModule::getLazyModule(LLVMContext &Context, bool ShouldLazyLoadMetadata,
                               bool IsImporting) {
    return getModuleImpl(Context, false, ShouldLazyLoadMetadata, IsImporting,
                         [](StringRef) { return None; });
  }
  
  // Parse the specified bitcode buffer and merge the index into CombinedIndex.
  // We don't use ModuleIdentifier here because the client may need to control the
  // module path used in the combined summary (e.g. when reading summaries for
  // regular LTO modules).
  Error BitcodeModule::readSummary(ModuleSummaryIndex &CombinedIndex,
                                   StringRef ModulePath, uint64_t ModuleId) {
    BitstreamCursor Stream(Buffer);
    if (Error JumpFailed = Stream.JumpToBit(ModuleBit))
      return JumpFailed;
  
    ModuleSummaryIndexBitcodeReader R(std::move(Stream), Strtab, CombinedIndex,
                                      ModulePath, ModuleId);
    return R.parseModule();
  }
  
  // Parse the specified bitcode buffer, returning the function info index.
  Expected<std::unique_ptr<ModuleSummaryIndex>> BitcodeModule::getSummary() {
    BitstreamCursor Stream(Buffer);
    if (Error JumpFailed = Stream.JumpToBit(ModuleBit))
      return std::move(JumpFailed);
  
    auto Index = std::make_unique<ModuleSummaryIndex>(/*HaveGVs=*/false);
    ModuleSummaryIndexBitcodeReader R(std::move(Stream), Strtab, *Index,
                                      ModuleIdentifier, 0);
  
    if (Error Err = R.parseModule())
      return std::move(Err);
  
    return std::move(Index);
  }
  
  static Expected<bool> getEnableSplitLTOUnitFlag(BitstreamCursor &Stream,
                                                  unsigned ID) {
    if (Error Err = Stream.EnterSubBlock(ID))
      return std::move(Err);
    SmallVector<uint64_t, 64> Record;
  
    while (true) {
      Expected<BitstreamEntry> MaybeEntry = Stream.advanceSkippingSubblocks();
      if (!MaybeEntry)
        return MaybeEntry.takeError();
      BitstreamEntry Entry = MaybeEntry.get();
  
      switch (Entry.Kind) {
      case BitstreamEntry::SubBlock: // Handled for us already.
      case BitstreamEntry::Error:
        return error("Malformed block");
      case BitstreamEntry::EndBlock:
        // If no flags record found, conservatively return true to mimic
        // behavior before this flag was added.
        return true;
      case BitstreamEntry::Record:
        // The interesting case.
        break;
      }
  
      // Look for the FS_FLAGS record.
      Record.clear();
      Expected<unsigned> MaybeBitCode = Stream.readRecord(Entry.ID, Record);
      if (!MaybeBitCode)
        return MaybeBitCode.takeError();
      switch (MaybeBitCode.get()) {
      default: // Default behavior: ignore.
        break;
      case bitc::FS_FLAGS: { // [flags]
        uint64_t Flags = Record[0];
        // Scan flags.
        assert(Flags <= 0x3f && "Unexpected bits in flag");
  
        return Flags & 0x8;
      }
      }
    }
    llvm_unreachable("Exit infinite loop");
  }
  
  // Check if the given bitcode buffer contains a global value summary block.
  Expected<BitcodeLTOInfo> BitcodeModule::getLTOInfo() {
    BitstreamCursor Stream(Buffer);
    if (Error JumpFailed = Stream.JumpToBit(ModuleBit))
      return std::move(JumpFailed);
  
    if (Error Err = Stream.EnterSubBlock(bitc::MODULE_BLOCK_ID))
      return std::move(Err);
  
    while (true) {
      Expected<llvm::BitstreamEntry> MaybeEntry = Stream.advance();
      if (!MaybeEntry)
        return MaybeEntry.takeError();
      llvm::BitstreamEntry Entry = MaybeEntry.get();
  
      switch (Entry.Kind) {
      case BitstreamEntry::Error:
        return error("Malformed block");
      case BitstreamEntry::EndBlock:
        return BitcodeLTOInfo{/*IsThinLTO=*/false, /*HasSummary=*/false,
                              /*EnableSplitLTOUnit=*/false};
  
      case BitstreamEntry::SubBlock:
        if (Entry.ID == bitc::GLOBALVAL_SUMMARY_BLOCK_ID) {
          Expected<bool> EnableSplitLTOUnit =
              getEnableSplitLTOUnitFlag(Stream, Entry.ID);
          if (!EnableSplitLTOUnit)
            return EnableSplitLTOUnit.takeError();
          return BitcodeLTOInfo{/*IsThinLTO=*/true, /*HasSummary=*/true,
                                *EnableSplitLTOUnit};
        }
  
        if (Entry.ID == bitc::FULL_LTO_GLOBALVAL_SUMMARY_BLOCK_ID) {
          Expected<bool> EnableSplitLTOUnit =
              getEnableSplitLTOUnitFlag(Stream, Entry.ID);
          if (!EnableSplitLTOUnit)
            return EnableSplitLTOUnit.takeError();
          return BitcodeLTOInfo{/*IsThinLTO=*/false, /*HasSummary=*/true,
                                *EnableSplitLTOUnit};
        }
  
        // Ignore other sub-blocks.
        if (Error Err = Stream.SkipBlock())
          return std::move(Err);
        continue;
  
      case BitstreamEntry::Record:
        if (Expected<unsigned> StreamFailed = Stream.skipRecord(Entry.ID))
          continue;
        else
          return StreamFailed.takeError();
      }
    }
  }
  
  static Expected<BitcodeModule> getSingleModule(MemoryBufferRef Buffer) {
    Expected<std::vector<BitcodeModule>> MsOrErr = getBitcodeModuleList(Buffer);
    if (!MsOrErr)
      return MsOrErr.takeError();
  
    if (MsOrErr->size() != 1)
      return error("Expected a single module");
  
    return (*MsOrErr)[0];
  }
  
  Expected<std::unique_ptr<Module>>
  llvm::getLazyBitcodeModule(MemoryBufferRef Buffer, LLVMContext &Context,
                             bool ShouldLazyLoadMetadata, bool IsImporting) {
    Expected<BitcodeModule> BM = getSingleModule(Buffer);
    if (!BM)
      return BM.takeError();
  
    return BM->getLazyModule(Context, ShouldLazyLoadMetadata, IsImporting);
  }
  
  Expected<std::unique_ptr<Module>> llvm::getOwningLazyBitcodeModule(
      std::unique_ptr<MemoryBuffer> &&Buffer, LLVMContext &Context,
      bool ShouldLazyLoadMetadata, bool IsImporting) {
    auto MOrErr = getLazyBitcodeModule(*Buffer, Context, ShouldLazyLoadMetadata,
                                       IsImporting);
    if (MOrErr)
      (*MOrErr)->setOwnedMemoryBuffer(std::move(Buffer));
    return MOrErr;
  }
  
  Expected<std::unique_ptr<Module>>
  BitcodeModule::parseModule(LLVMContext &Context,
                             DataLayoutCallbackTy DataLayoutCallback) {
    return getModuleImpl(Context, true, false, false, DataLayoutCallback);
    // TODO: Restore the use-lists to the in-memory state when the bitcode was
    // written.  We must defer until the Module has been fully materialized.
  }
  
  Expected<std::unique_ptr<Module>>
  llvm::parseBitcodeFile(MemoryBufferRef Buffer, LLVMContext &Context,
                         DataLayoutCallbackTy DataLayoutCallback) {
    Expected<BitcodeModule> BM = getSingleModule(Buffer);
    if (!BM)
      return BM.takeError();
  
    return BM->parseModule(Context, DataLayoutCallback);
  }
  
  Expected<std::string> llvm::getBitcodeTargetTriple(MemoryBufferRef Buffer) {
    Expected<BitstreamCursor> StreamOrErr = initStream(Buffer);
    if (!StreamOrErr)
      return StreamOrErr.takeError();
  
    return readTriple(*StreamOrErr);
  }
  
  Expected<bool> llvm::isBitcodeContainingObjCCategory(MemoryBufferRef Buffer) {
    Expected<BitstreamCursor> StreamOrErr = initStream(Buffer);
    if (!StreamOrErr)
      return StreamOrErr.takeError();
  
    return hasObjCCategory(*StreamOrErr);
  }
  
  Expected<std::string> llvm::getBitcodeProducerString(MemoryBufferRef Buffer) {
    Expected<BitstreamCursor> StreamOrErr = initStream(Buffer);
    if (!StreamOrErr)
      return StreamOrErr.takeError();
  
    return readIdentificationCode(*StreamOrErr);
  }
  
  Error llvm::readModuleSummaryIndex(MemoryBufferRef Buffer,
                                     ModuleSummaryIndex &CombinedIndex,
                                     uint64_t ModuleId) {
    Expected<BitcodeModule> BM = getSingleModule(Buffer);
    if (!BM)
      return BM.takeError();
  
    return BM->readSummary(CombinedIndex, BM->getModuleIdentifier(), ModuleId);
  }
  
  Expected<std::unique_ptr<ModuleSummaryIndex>>
  llvm::getModuleSummaryIndex(MemoryBufferRef Buffer) {
    Expected<BitcodeModule> BM = getSingleModule(Buffer);
    if (!BM)
      return BM.takeError();
  
    return BM->getSummary();
  }
  
  Expected<BitcodeLTOInfo> llvm::getBitcodeLTOInfo(MemoryBufferRef Buffer) {
    Expected<BitcodeModule> BM = getSingleModule(Buffer);
    if (!BM)
      return BM.takeError();
  
    return BM->getLTOInfo();
  }
  
  Expected<std::unique_ptr<ModuleSummaryIndex>>
  llvm::getModuleSummaryIndexForFile(StringRef Path,
                                     bool IgnoreEmptyThinLTOIndexFile) {
    ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr =
        MemoryBuffer::getFileOrSTDIN(Path);
    if (!FileOrErr)
      return errorCodeToError(FileOrErr.getError());
    if (IgnoreEmptyThinLTOIndexFile && !(*FileOrErr)->getBufferSize())
      return nullptr;
    return getModuleSummaryIndex(**FileOrErr);
  }
  