/*===================== begin_copyright_notice ==================================

Copyright (c) 2017 Intel Corporation

Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

The above copyright notice and this permission notice shall be included
in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.


======================= end_copyright_notice ==================================*/


//===- BitcodeReader.cpp - Internal BitcodeReader implementation ----------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#pragma warning(disable:4141)
#pragma warning(disable:4146)
#pragma warning(disable:4244)
#pragma warning(disable:4624)
#pragma warning(disable:4800)

#include "common/LLVMWarningsPush.hpp"

#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/BitstreamReader.h"
#include "llvm/Bitcode/LLVMBitCodes.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/CallSite.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 <cstddef>
#include <cstdint>
#include <deque>
#include <map>
#include <memory>
#include <set>
#include <string>
#include <system_error>
#include <tuple>
#include <utility>
#include <vector>
#include "common/LLVMWarningsPop.hpp"
#include "BitcodeReader.h"
#include "Probe.h"

using namespace llvm;


//===----------------------------------------------------------------------===//
// upgrade bitcast to addrspacecast when necessary
//===----------------------------------------------------------------------===//
Instruction *upgradeBitCastInst(unsigned Opc, Value *V, Type *DestTy,
    Instruction *&Temp) {
    if (Opc != Instruction::BitCast)
        return nullptr;

    Type *SrcTy = V->getType();
    if (SrcTy->isPtrOrPtrVectorTy() && DestTy->isPtrOrPtrVectorTy() &&
        SrcTy->getPointerAddressSpace() != DestTy->getPointerAddressSpace()) {
        // Convert it to 'addrspacecast' instead.
        return CastInst::Create(Instruction::AddrSpaceCast, V, DestTy);
    }

    return nullptr;
}

Value *upgradeBitCastExpr(unsigned Opc, Constant *C, Type *DestTy) {
    if (Opc != Instruction::BitCast)
        return nullptr;

    Type *SrcTy = C->getType();
    if (SrcTy->isPtrOrPtrVectorTy() && DestTy->isPtrOrPtrVectorTy() &&
        SrcTy->getPointerAddressSpace() != DestTy->getPointerAddressSpace()) {
        // Convert it to 'addrspacecast' instead.
        return ConstantExpr::getAddrSpaceCast(C, DestTy);
    }

    return nullptr;
}

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));
}

/// Helper to read the header common to all bitcode files.
static bool hasValidBitcodeHeader(BitstreamCursor &Stream) {
  // Sniff for the signature.
  if (!Stream.canSkipToPos(4) ||
      Stream.Read(8) != 'B' ||
      Stream.Read(8) != 'C' ||
      Stream.Read(4) != 0x0 ||
      Stream.Read(4) != 0xC ||
      Stream.Read(4) != 0xE ||
      Stream.Read(4) != 0xD)
    return false;
  return true;
}

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 (!hasValidBitcodeHeader(Stream))
    return error("Invalid bitcode signature");

  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;

  for (unsigned i = Idx, e = Record.size(); i != e; ++i)
    Result += (char)Record[i];
  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 (Stream.EnterSubBlock(bitc::IDENTIFICATION_BLOCK_ID))
    return error("Invalid record");

  // Read all the records.
  SmallVector<uint64_t, 64> Record;

  std::string ProducerIdentification;

  while (true) {
    BitstreamEntry Entry = Stream.advance();

    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();
    unsigned BitCode = Stream.readRecord(Entry.ID, Record);
    switch (BitCode) {
    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 = Stream.advance();
    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 (Stream.SkipBlock())
        return error("Malformed block");
      continue;
    case BitstreamEntry::Record:
      Stream.skipRecord(Entry.ID);
      continue;
    }
  }
}

static Expected<bool> hasObjCCategoryInModule(BitstreamCursor &Stream) {
  if (Stream.EnterSubBlock(bitc::MODULE_BLOCK_ID))
    return error("Invalid record");

  SmallVector<uint64_t, 64> Record;
  // Read all the records for this module.

  while (true) {
    BitstreamEntry Entry = Stream.advanceSkippingSubblocks();

    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.
    switch (Stream.readRecord(Entry.ID, Record)) {
    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 = Stream.advance();

    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 (Stream.SkipBlock())
        return error("Malformed block");
      continue;

    case BitstreamEntry::Record:
      Stream.skipRecord(Entry.ID);
      continue;
    }
  }
}

static Expected<std::string> readModuleTriple(BitstreamCursor &Stream) {
  if (Stream.EnterSubBlock(bitc::MODULE_BLOCK_ID))
    return error("Invalid record");

  SmallVector<uint64_t, 64> Record;

  std::string Triple;

  // Read all the records for this module.
  while (true) {
    BitstreamEntry Entry = Stream.advanceSkippingSubblocks();

    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.
    switch (Stream.readRecord(Entry.ID, Record)) {
    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) {
    BitstreamEntry Entry = Stream.advance();

    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 (Stream.SkipBlock())
        return error("Malformed block");
      continue;

    case BitstreamEntry::Record:
      Stream.skipRecord(Entry.ID);
      continue;
    }
  }
}

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;
  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);

  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);

  Type *getTypeByID(unsigned ID);

  Value *getFnValueByID(unsigned ID, Type *Ty) {
    if (Ty && Ty->isMetadataTy())
      return MetadataAsValue::get(Ty->getContext(), getFnMetadataByID(ID));
    return ValueList.getValueFwdRef(ID, Ty);
  }

  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) {
    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);
      return ResVal == nullptr;
    }
    if (Slot == Record.size())
      return true;

    unsigned TypeNo = (unsigned)Record[Slot++];
    ResVal = getFnValueByID(ValNo, getTypeByID(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);
  }

  /// Converts alignment exponent (i.e. power of two (or zero)) to the
  /// corresponding alignment to use. If alignment is too large, returns
  /// a corresponding error code.
  Error parseAlignmentValue(uint64_t Exponent, unsigned &Alignment);
  Error parseAttrKind(uint64_t Code, Attribute::AttrKind *Kind);
  Error parseModule(uint64_t ResumeBit, bool ShouldLazyLoadMetadata = false);

  Error parseComdatRecord(ArrayRef<uint64_t> Record);
  Error parseGlobalVarRecord(ArrayRef<uint64_t> Record);
  Error parseFunctionRecord(ArrayRef<uint64_t> Record);
  Error parseGlobalIndirectSymbolRecord(unsigned BitCode,
                                        ArrayRef<uint64_t> Record);

  Error parseAttributeBlock();
  Error parseAttributeGroupBlock();
  Error parseTypeTable();
  Error parseTypeTableBody();
  Error parseOperandBundleTags();
  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();

  std::pair<ValueInfo, GlobalValue::GUID>
  getValueInfoFromValueId(unsigned ValueId);

  void addThisModule();
  ModuleSummaryIndex::ModuleInfo *getThisModule();
};

} // end anonymous namespace

#if 0
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();
}
#endif

BitcodeReader::BitcodeReader(BitstreamCursor Stream, StringRef Strtab,
                             StringRef ProducerIdentification,
                             LLVMContext &Context)
    : BitcodeReaderBase(std::move(Stream), Strtab), Context(Context),
      ValueList(Context) {
  this->ProducerIdentification = ProducerIdentification;
}

Error BitcodeReader::materializeForwardReferencedFunctions() {
  if (WillMaterializeAllForwardRefs)
    return Error::success();

  // Prevent recursion.
  WillMaterializeAllForwardRefs = true;

  while (!BasicBlockFwdRefQueue.empty()) {
    Function *F = BasicBlockFwdRefQueue.front();
    BasicBlockFwdRefQueue.pop_front();
    IGC_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;
  }
  IGC_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;
  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);

  return GlobalValueSummary::GVFlags(Linkage, NotEligibleToImport, Live, Local);
}

// Decode the flags for GlobalVariable in the summary
static GlobalVarSummary::GVarFlags getDecodedGVarFlags(uint64_t RawFlags) {
  return GlobalVarSummary::GVarFlags((RawFlags & 0x1) ? true : false);
}

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_NEG:
    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;
  }
}

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::getTypeByID(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:
    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::Dereferenceable:
    llvm_unreachable("dereferenceable attribute not supported in raw format");
    break;
  case Attribute::DereferenceableOrNull:
    llvm_unreachable("dereferenceable_or_null attribute not supported in raw "
                     "format");
    break;
  case Attribute::ArgMemOnly:
    llvm_unreachable("argmemonly attribute not supported in raw format");
    break;
  case Attribute::AllocSize:
    llvm_unreachable("allocsize not supported in raw format");
    break;
  default:
      llvm_unreachable("Unsupported attribute type");
    break;
      //return 0;
  }
}

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 (I == Attribute::Dereferenceable ||
        I == Attribute::DereferenceableOrNull ||
        I == Attribute::ArgMemOnly ||
        I == Attribute::AllocSize)
      continue;
    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) {
  // FIXME: Remove in 4.0.

  // 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;
  IGC_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 (Stream.EnterSubBlock(bitc::PARAMATTR_BLOCK_ID))
    return error("Invalid record");

  if (!MAttributes.empty())
    return error("Invalid multiple blocks");

  SmallVector<uint64_t, 64> Record;

  SmallVector<AttributeList, 8> Attrs;

  // Read all the records.
  while (true) {
    BitstreamEntry Entry = Stream.advanceSkippingSubblocks();

    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();
    switch (Stream.readRecord(Entry.ID, Record)) {
    default:  // Default behavior: ignore.
      break;
    case bitc::PARAMATTR_CODE_ENTRY_OLD: // ENTRY: [paramidx0, attr0, ...]
      // FIXME: Remove in 4.0.
      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_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_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_NOCF_CHECK:
    return Attribute::NoCfCheck;
  case bitc::ATTR_KIND_NO_UNWIND:
    return Attribute::NoUnwind;
  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_WRITEONLY:
    return Attribute::WriteOnly;
  case bitc::ATTR_KIND_Z_EXT:
    return Attribute::ZExt;
  }
}

Error BitcodeReader::parseAlignmentValue(uint64_t Exponent,
                                         unsigned &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 = (1 << static_cast<unsigned>(Exponent)) >> 1;
  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 (Stream.EnterSubBlock(bitc::PARAMATTR_GROUP_BLOCK_ID))
    return error("Invalid record");

  if (!MAttributeGroups.empty())
    return error("Invalid multiple blocks");

  SmallVector<uint64_t, 64> Record;

  // Read all the records.
  while (true) {
    BitstreamEntry Entry = Stream.advanceSkippingSubblocks();

    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();
    switch (Stream.readRecord(Entry.ID, Record)) {
    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;

          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 {                     // String attribute
          IGC_ASSERT((Record[i] == 3 || Record[i] == 4) &&
                 "Invalid attribute group entry");
          bool HasValue = (Record[i++] == 4);
          SmallString<64> KindStr;
          SmallString<64> ValStr;

          while (Record[i] != 0 && i != e)
            KindStr += Record[i++];
          IGC_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++];
            IGC_ASSERT(Record[i] == 0 && "Value string not null terminated");
          }

          B.addAttribute(KindStr.str(), ValStr.str());
        }
      }

      MAttributeGroups[GrpID] = AttributeList::get(Context, Idx, B);
      break;
    }
    }
  }
}

Error BitcodeReader::parseTypeTable() {
  if (Stream.EnterSubBlock(bitc::TYPE_BLOCK_ID_NEW))
    return error("Invalid record");

  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) {
    BitstreamEntry Entry = Stream.advanceSkippingSubblocks();

    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;
    switch (Stream.readRecord(Entry.ID, Record)) {
    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.size() < 1)
        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_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.size() < 1)
        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.size() < 1)
        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: {
      // FIXME: attrid is dead, remove it in LLVM 4.0
      // 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.size() < 1)
        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.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.
        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]
      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");
      ResultTy = VectorType::get(ResultTy, Record[0]);
      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");
    IGC_ASSERT(ResultTy && "Didn't read a type?");
    TypeList[NumRecords++] = ResultTy;
  }
}

Error BitcodeReader::parseOperandBundleTags() {
  if (Stream.EnterSubBlock(bitc::OPERAND_BUNDLE_TAGS_BLOCK_ID))
    return error("Invalid record");

  if (!BundleTags.empty())
    return error("Invalid multiple blocks");

  SmallVector<uint64_t, 64> Record;

  while (true) {
    BitstreamEntry Entry = Stream.advanceSkippingSubblocks();

    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.

    if (Stream.readRecord(Entry.ID, Record) != 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 (Stream.EnterSubBlock(bitc::SYNC_SCOPE_NAMES_BLOCK_ID))
    return error("Invalid record");

  if (!SSIDs.empty())
    return error("Invalid multiple synchronization scope names blocks");

  SmallVector<uint64_t, 64> Record;
  while (true) {
    BitstreamEntry Entry = Stream.advanceSkippingSubblocks();
    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.

    if (Stream.readRecord(Entry.ID, Record) != 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 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();
  Stream.JumpToBit(Offset * 32);
#ifndef NDEBUG
  // Do some checking if we are in debug mode.
  BitstreamEntry Entry = Stream.advance();
  IGC_ASSERT(Entry.Kind == BitstreamEntry::SubBlock);
  IGC_ASSERT(Entry.ID == bitc::VALUE_SYMTAB_BLOCK_ID);
#else
  // In NDEBUG mode ignore the output so we don't get an unused variable
  // warning.
  Stream.advance();
#endif
  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 (Stream.EnterSubBlock(bitc::VALUE_SYMTAB_BLOCK_ID))
    return error("Invalid record");

  SmallVector<uint64_t, 64> Record;
  while (true) {
    BitstreamEntry Entry = Stream.advanceSkippingSubblocks();

    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();
    switch (Stream.readRecord(Entry.ID, Record)) {
    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) {
    CurrentBit = jumpToValueSymbolTable(Offset, Stream);
    // If this module uses a string table, read this as a module-level VST.
    if (UseStrtab) {
      if (Error Err = parseGlobalValueSymbolTable())
        return Err;
      Stream.JumpToBit(CurrentBit);
      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 (Stream.EnterSubBlock(bitc::VALUE_SYMTAB_BLOCK_ID))
    return error("Invalid record");

  SmallVector<uint64_t, 64> Record;

  Triple TT(TheModule->getTargetTriple());

  // Read all the records for this value table.
  SmallString<128> ValueName;

  while (true) {
    BitstreamEntry Entry = Stream.advanceSkippingSubblocks();

    switch (Entry.Kind) {
    case BitstreamEntry::SubBlock: // Handled for us already.
    case BitstreamEntry::Error:
      return error("Malformed block");
    case BitstreamEntry::EndBlock:
      if (Offset > 0)
        Stream.JumpToBit(CurrentBit);
      return Error::success();
    case BitstreamEntry::Record:
      // The interesting case.
      break;
    }

    // Read a record.
    Record.clear();
    switch (Stream.readRecord(Entry.ID, Record)) {
    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();
}

static APInt 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 (Stream.EnterSubBlock(bitc::CONSTANTS_BLOCK_ID))
    return error("Invalid record");

  SmallVector<uint64_t, 64> Record;

  // Read all the records for this value table.
  Type *CurTy = Type::getInt32Ty(Context);
  unsigned NextCstNo = ValueList.size();

  while (true) {
    BitstreamEntry Entry = Stream.advanceSkippingSubblocks();

    switch (Entry.Kind) {
    case BitstreamEntry::SubBlock: // Handled for us already.
    case BitstreamEntry::Error:
      return error("Malformed block");
    case BitstreamEntry::EndBlock:
      if (NextCstNo != ValueList.size())
        return error("Invalid constant reference");

      // Once all the constants have been read, go through and resolve forward
      // references.
      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;
    unsigned BitCode = Stream.readRecord(Entry.ID, Record);
    switch (BitCode) {
    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");
      CurTy = TypeList[Record[0]];
      continue;  // Skip the ValueList manipulation.
    case bitc::CST_CODE_NULL:      // NULL
      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->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 = cast<SequentialType>(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(Context, Elts);
        else
          V = ConstantDataArray::getFP(Context, Elts);
      } else if (EltTy->isFloatTy()) {
        SmallVector<uint32_t, 16> Elts(Record.begin(), Record.end());
        if (isa<VectorType>(CurTy))
          V = ConstantDataVector::getFP(Context, Elts);
        else
          V = ConstantDataArray::getFP(Context, Elts);
      } else if (EltTy->isDoubleTy()) {
        SmallVector<uint64_t, 16> Elts(Record.begin(), Record.end());
        if (isa<VectorType>(CurTy))
          V = ConstantDataVector::getFP(Context, Elts);
        else
          V = ConstantDataArray::getFP(Context, 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;
      while (OpNum != Record.size()) {
        Type *ElTy = getTypeByID(Record[OpNum++]);
        if (!ElTy)
          return error("Invalid record");
        Elts.push_back(ValueList.getConstantFwdRef(Record[OpNum++], ElTy));
      }

      if (PointeeType &&
          PointeeType !=
              cast<PointerType>(Elts[0]->getType()->getScalarType())
                  ->getElementType())
        return error("Explicit gep operator type does not match pointee type "
                     "of pointer operand");

      if (Elts.size() < 1)
        return error("Invalid gep with no operands");

      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 or an <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->getNumElements());

      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 // TODO: Remove with llvm 4.0
        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 // TODO: Remove with llvm 4.0
        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");
      Constant *Op0 = ValueList.getConstantFwdRef(Record[0], OpTy);
      Constant *Op1 = ValueList.getConstantFwdRef(Record[1], OpTy);
      Type *ShufTy = VectorType::get(Type::getInt32Ty(Context),
                                                 OpTy->getNumElements());
      Constant *Op2 = ValueList.getConstantFwdRef(Record[2], ShufTy);
      V = ConstantExpr::getShuffleVector(Op0, Op1, Op2);
      break;
    }
    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");
      Constant *Op0 = ValueList.getConstantFwdRef(Record[1], OpTy);
      Constant *Op1 = ValueList.getConstantFwdRef(Record[2], OpTy);
      Type *ShufTy = VectorType::get(Type::getInt32Ty(Context),
                                                 RTy->getNumElements());
      Constant *Op2 = ValueList.getConstantFwdRef(Record[3], ShufTy);
      V = ConstantExpr::getShuffleVector(Op0, Op1, Op2);
      break;
    }
    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.
    // FIXME: Remove with the 4.0 release.
    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];
      PointerType *PTy = cast<PointerType>(CurTy);
      UpgradeInlineAsmString(&AsmStr);
      V = InlineAsm::get(cast<FunctionType>(PTy->getElementType()),
                         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];
      PointerType *PTy = cast<PointerType>(CurTy);
      UpgradeInlineAsmString(&AsmStr);
      V = InlineAsm::get(cast<FunctionType>(PTy->getElementType()),
                         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;
    }
    }

    ValueList.assignValue(V, NextCstNo);
    ++NextCstNo;
  }
}

Error BitcodeReader::parseUseLists() {
  if (Stream.EnterSubBlock(bitc::USELIST_BLOCK_ID))
    return error("Invalid record");

  // Read all the records.
  SmallVector<uint64_t, 64> Record;

  while (true) {
    BitstreamEntry Entry = Stream.advanceSkippingSubblocks();

    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;
    switch (Stream.readRecord(Entry.ID, Record)) {
    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) {
        IGC_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 (Stream.SkipBlock())
    return error("Invalid record");
  return Error::success();
}

Error BitcodeReader::materializeMetadata() {
  for (uint64_t BitPos : DeferredMetadataInfo) {
    // Move the bit stream to the saved position.
    Stream.JumpToBit(BitPos);
    if (Error Err = MDLoader->parseModuleMetadata())
      return Err;
  }

  // Upgrade "Linker Options" module flag to "llvm.linker.options" module-level
  // metadata.
  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();
  IGC_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 (Stream.SkipBlock())
    return error("Invalid record");
  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
  for (Function &F : *TheModule) {
    //LLVM_UPGRADE_TODO
    //check this funciton upgradeDebugIntrinsics (in llvm 4.0 not present)
    //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 global variables which need to be renamed.
  for (GlobalVariable &GV : TheModule->globals())
    UpgradeGlobalVariable(&GV);

  // 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() {
  Stream.JumpToBit(NextUnreadBit);

  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.
  IGC_ASSERT(SeenValueSymbolTable);

  SmallVector<uint64_t, 64> Record;

  while (true) {
    BitstreamEntry Entry = Stream.advance();
    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() {
  Optional<BitstreamBlockInfo> NewBlockInfo = Stream.ReadBlockInfoBlock();
  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] (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 *Ty = getTypeByID(Record[0]);
  if (!Ty)
    return error("Invalid record");
  bool isConstant = Record[1] & 1;
  bool explicitType = Record[1] & 2;
  unsigned AddressSpace;
  if (explicitType) {
    AddressSpace = Record[1] >> 2;
  } else {
    if (!Ty->isPointerTy())
      return error("Invalid type for value");
    AddressSpace = cast<PointerType>(Ty)->getAddressSpace();
    Ty = cast<PointerType>(Ty)->getElementType();
  }

  uint64_t RawLinkage = Record[3];
  GlobalValue::LinkageTypes Linkage = getDecodedLinkage(RawLinkage);
  unsigned Alignment;
  if (Error Err = parseAlignmentValue(Record[4], Alignment))
    return Err;
  std::string Section;
  if (Record[5]) {
    if (Record[5] - 1 >= SectionTable.size())
      return error("Invalid ID");
    Section = SectionTable[Record[5] - 1];
  }
  GlobalValue::VisibilityTypes Visibility = GlobalValue::DefaultVisibility;
  // Local linkage must have default visibility.
  if (Record.size() > 6 && !GlobalValue::isLocalLinkage(Linkage))
    // FIXME: Change to an error if non-default in 4.0.
    Visibility = getDecodedVisibility(Record[6]);

  GlobalVariable::ThreadLocalMode TLM = GlobalVariable::NotThreadLocal;
  if (Record.size() > 7)
    TLM = getDecodedThreadLocalMode(Record[7]);

  GlobalValue::UnnamedAddr UnnamedAddr = GlobalValue::UnnamedAddr::None;
  if (Record.size() > 8)
    UnnamedAddr = getDecodedUnnamedAddrType(Record[8]);

  bool ExternallyInitialized = false;
  if (Record.size() > 9)
    ExternallyInitialized = Record[9];

  GlobalVariable *NewGV =
      new GlobalVariable(*TheModule, Ty, isConstant, Linkage, nullptr, 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);

  ValueList.push_back(NewGV);

  // Remember which value to use for the global initializer.
  if (unsigned InitID = Record[2])
    GlobalInits.push_back(std::make_pair(NewGV, InitID - 1));

  if (Record.size() > 11) {
    if (unsigned ComdatID = Record[11]) {
      if (ComdatID > ComdatList.size())
        return error("Invalid global variable comdat ID");
      NewGV->setComdat(ComdatList[ComdatID - 1]);
    }
  } else if (hasImplicitComdat(RawLinkage)) {
    NewGV->setComdat(reinterpret_cast<Comdat *>(1));
  }

  if (Record.size() > 12) {
    auto AS = getAttributes(Record[12]).getFnAttributes();
    NewGV->setAttributes(AS);
  }

  if (Record.size() > 13) {
    NewGV->setDSOLocal(getDecodedDSOLocal(Record[13]));
  }
  inferDSOLocal(NewGV);

  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 *Ty = getTypeByID(Record[0]);
  if (!Ty)
    return error("Invalid record");
  if (auto *PTy = dyn_cast<PointerType>(Ty))
    Ty = PTy->getElementType();
  auto *FTy = dyn_cast<FunctionType>(Ty);
  if (!FTy)
    return error("Invalid type for value");
  auto CC = static_cast<CallingConv::ID>(Record[1]);
  if (CC & ~CallingConv::MaxID)
    return error("Invalid calling convention ID");

  unsigned AddrSpace = TheModule->getDataLayout().getProgramAddressSpace();
  if (Record.size() > 16)
    AddrSpace = Record[16];

  Function *Func = Function::Create(FTy, GlobalValue::ExternalLinkage,
                                    AddrSpace, Name, TheModule);

  Func->setCallingConv(CC);
  bool isProto = Record[2];
  uint64_t RawLinkage = Record[3];
  Func->setLinkage(getDecodedLinkage(RawLinkage));
  Func->setAttributes(getAttributes(Record[4]));

  unsigned Alignment;
  if (Error Err = parseAlignmentValue(Record[5], Alignment))
    return Err;
  Func->setAlignment(Alignment);
  if (Record[6]) {
    if (Record[6] - 1 >= SectionTable.size())
      return error("Invalid ID");
    Func->setSection(SectionTable[Record[6] - 1]);
  }
  // Local linkage must have default visibility.
  if (!Func->hasLocalLinkage())
    // FIXME: Change to an error if non-default in 4.0.
    Func->setVisibility(getDecodedVisibility(Record[7]));
  if (Record.size() > 8 && Record[8]) {
    if (Record[8] - 1 >= GCTable.size())
      return error("Invalid ID");
    Func->setGC(GCTable[Record[8] - 1]);
  }
  GlobalValue::UnnamedAddr UnnamedAddr = GlobalValue::UnnamedAddr::None;
  if (Record.size() > 9)
    UnnamedAddr = getDecodedUnnamedAddrType(Record[9]);
  Func->setUnnamedAddr(UnnamedAddr);
  if (Record.size() > 10 && Record[10] != 0)
    FunctionPrologues.push_back(std::make_pair(Func, Record[10] - 1));

  if (Record.size() > 11)
    Func->setDLLStorageClass(getDecodedDLLStorageClass(Record[11]));
  else
    upgradeDLLImportExportLinkage(Func, RawLinkage);

  if (Record.size() > 12) {
    if (unsigned ComdatID = Record[12]) {
      if (ComdatID > ComdatList.size())
        return error("Invalid function comdat ID");
      Func->setComdat(ComdatList[ComdatID - 1]);
    }
  } else if (hasImplicitComdat(RawLinkage)) {
    Func->setComdat(reinterpret_cast<Comdat *>(1));
  }

  if (Record.size() > 13 && Record[13] != 0)
    FunctionPrefixes.push_back(std::make_pair(Func, Record[13] - 1));

  if (Record.size() > 14 && Record[14] != 0)
    FunctionPersonalityFns.push_back(std::make_pair(Func, Record[14] - 1));

  if (Record.size() > 15) {
    Func->setDSOLocal(getDecodedDSOLocal(Record[15]));
  }
  inferDSOLocal(Func);

  ValueList.push_back(Func);

  // If this is a function with a body, remember the prototype we are
  // creating now, so that we can match up the body with them later.
  if (!isProto) {
    Func->setIsMaterializable(true);
    FunctionsWithBodies.push_back(Func);
    DeferredFunctionInfo[Func] = 0;
  }
  return Error::success();
}

Error BitcodeReader::parseGlobalIndirectSymbolRecord(
    unsigned BitCode, ArrayRef<uint64_t> Record) {
  // 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 *Ty = getTypeByID(Record[OpNum++]);
  if (!Ty)
    return error("Invalid record");

  unsigned AddrSpace;
  if (!NewRecord) {
    auto *PTy = dyn_cast<PointerType>(Ty);
    if (!PTy)
      return error("Invalid type for value");
    Ty = PTy->getElementType();
    AddrSpace = PTy->getAddressSpace();
  } else {
    AddrSpace = Record[OpNum++];
  }

  auto Val = Record[OpNum++];
  auto Linkage = Record[OpNum++];
  GlobalIndirectSymbol *NewGA;
  if (BitCode == bitc::MODULE_CODE_ALIAS ||
      BitCode == bitc::MODULE_CODE_ALIAS_OLD)
    NewGA = GlobalAlias::create(Ty, AddrSpace, getDecodedLinkage(Linkage), Name,
                                TheModule);
  else
    NewGA = GlobalIFunc::create(Ty, AddrSpace, getDecodedLinkage(Linkage), Name,
                                nullptr, TheModule);
  // Old bitcode files didn't have visibility field.
  // Local linkage must have default visibility.
  if (OpNum != Record.size()) {
    auto VisInd = OpNum++;
    if (!NewGA->hasLocalLinkage())
      // FIXME: Change to an error if non-default in 4.0.
      NewGA->setVisibility(getDecodedVisibility(Record[VisInd]));
  }
  if (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);

  ValueList.push_back(NewGA);
  IndirectSymbolInits.push_back(std::make_pair(NewGA, Val));
  return Error::success();
}

Error BitcodeReader::parseModule(uint64_t ResumeBit,
                                 bool ShouldLazyLoadMetadata) {
  if (ResumeBit)
    Stream.JumpToBit(ResumeBit);
  else if (Stream.EnterSubBlock(bitc::MODULE_BLOCK_ID))
    return error("Invalid record");

  SmallVector<uint64_t, 64> Record;

  // Read all the records for this module.
  while (true) {
    BitstreamEntry Entry = Stream.advance();

    switch (Entry.Kind) {
    case BitstreamEntry::Error:
      return error("Malformed block");
    case BitstreamEntry::EndBlock:
      return globalCleanup();

    case BitstreamEntry::SubBlock:
      switch (Entry.ID) {
      default:  // Skip unknown content.
        if (Stream.SkipBlock())
          return error("Invalid record");
        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.
          IGC_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.
          IGC_ASSERT(VSTOffset > 0);
          if (Stream.SkipBlock())
            return error("Invalid record");
        }
        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;
        }
        IGC_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:
        // 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 (Stream.SkipBlock())
              return error("Invalid record");
            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.
    auto BitCode = Stream.readRecord(Entry.ID, Record);
    switch (BitCode) {
    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]
      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]
      std::string S;
      if (convertToString(Record, 0, S))
        return error("Invalid record");
      size_t index = S.find("-a64:64:64");
      if (index != std::string::npos)
          S.replace(index, 10, "");
      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]
      // FIXME: Remove in 4.0.
      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:
      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.size() < 1)
        return error("Invalid record");
      // Note that we subtract 1 here because the offset is relative to one word
      // before the start of the identification or module block, which was
      // 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) {
  TheModule = M;
  MDLoader = MetadataLoader(Stream, *M, ValueList, IsImporting,
                            [&](unsigned ID) { return getTypeByID(ID); });
  return parseModule(0, ShouldLazyLoadMetadata);
}

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();
}

/// Lazily parse the specified function body block.
Error BitcodeReader::parseFunctionBody(Function *F) {
  if (Stream.EnterSubBlock(bitc::FUNCTION_BLOCK_ID))
    return error("Invalid record");

  // 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.
  for (Argument &I : F->args())
    ValueList.push_back(&I);

  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) {
    BitstreamEntry Entry = Stream.advance();

    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 (Stream.SkipBlock())
          return error("Invalid record");
        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:
        IGC_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;
    unsigned BitCode = Stream.readRecord(Entry.ID, Record);
    switch (BitCode) {
    default: // Default behavior: reject
      return error("Invalid value");
    case bitc::FUNC_CODE_DECLAREBLOCKS: {   // DECLAREBLOCKS: [nblocks]
      if (Record.size() < 1 || 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");
        IGC_ASSERT(!BBRefs.empty() && "Unexpected empty array");
        IGC_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");

      Type *ResTy = getTypeByID(Record[OpNum]);
      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);
          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++];
        Ty = getTypeByID(Record[OpNum++]);
      } else {
        InBounds = BitCode == bitc::FUNC_CODE_INST_INBOUNDS_GEP_OLD;
        Ty = nullptr;
      }

      Value *BasePtr;
      if (getValueTypePair(Record, OpNum, NextValueNo, BasePtr))
        return error("Invalid record");

      if (!Ty)
        Ty = cast<PointerType>(BasePtr->getType()->getScalarType())
                 ->getElementType();
      else if (Ty !=
               cast<PointerType>(BasePtr->getType()->getScalarType())
                   ->getElementType())
        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);

      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))
        return error("Invalid record");

      unsigned RecSize = Record.size();
      if (OpNum == RecSize)
        return error("EXTRACTVAL: Invalid instruction with 0 indices");

      SmallVector<unsigned, 4> EXTRACTVALIdx;
      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("EXTRACTVAL: Invalid type");
        if ((unsigned)Index != Index)
          return error("Invalid value");
        if (IsStruct && Index >= CurTy->getStructNumElements())
          return error("EXTRACTVAL: Invalid struct index");
        if (IsArray && Index >= CurTy->getArrayNumElements())
          return error("EXTRACTVAL: Invalid array index");
        EXTRACTVALIdx.push_back((unsigned)Index);

        if (IsStruct)
          CurTy = CurTy->getStructElementType(Index);
        else
          CurTy = CurTy->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))
        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) ||
          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) ||
          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);
      break;
    }

    case bitc::FUNC_CODE_INST_EXTRACTELT: { // EXTRACTELT: [opty, opval, opval]
      unsigned OpNum = 0;
      Value *Vec, *Idx;
      if (getValueTypePair(Record, OpNum, NextValueNo, Vec) ||
          getValueTypePair(Record, OpNum, NextValueNo, Idx))
        return error("Invalid record");
      if (!Vec->getType()->isVectorTy())
        return error("Invalid type for value");
      I = ExtractElementInst::Create(Vec, Idx);
      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))
        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) ||
          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);
      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");

      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;
      if (CCInfo >> 13 & 1 &&
          !(FTy = dyn_cast<FunctionType>(getTypeByID(Record[OpNum++]))))
        return error("Explicit invoke type is not a function type");

      Value *Callee;
      if (getValueTypePair(Record, OpNum, NextValueNo, Callee))
        return error("Invalid record");

      PointerType *CalleeTy = dyn_cast<PointerType>(Callee->getType());
      if (!CalleeTy)
        return error("Callee is not a pointer");
      if (!FTy) {
        FTy = dyn_cast<FunctionType>(CalleeTy->getElementType());
        if (!FTy)
          return error("Callee is not of pointer to function type");
      } else if (CalleeTy->getElementType() != 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;
      for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i, ++OpNum) {
        Ops.push_back(getValue(Record, OpNum, NextValueNo,
                               FTy->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;
          if (getValueTypePair(Record, OpNum, NextValueNo, Op))
            return error("Invalid record");
          Ops.push_back(Op);
        }
      }

      I = InvokeInst::Create(Callee, NormalBB, UnwindBB, Ops, OperandBundles);
      OperandBundles.clear();
      InstructionList.push_back(I);
      cast<InvokeInst>(I)->setCallingConv(
          static_cast<CallingConv::ID>(CallingConv::MaxID & CCInfo));
      cast<InvokeInst>(I)->setAttributes(PAL);
      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_UNREACHABLE: // UNREACHABLE
      I = new UnreachableInst(Context);
      InstructionList.push_back(I);
      break;
    case bitc::FUNC_CODE_INST_PHI: { // PHI: [ty, val0,bb0, ...]
      if (Record.size() < 1 || ((Record.size()-1)&1))
        return error("Invalid record");
      Type *Ty = getTypeByID(Record[0]);
      if (!Ty)
        return error("Invalid record");

      PHINode *PN = PHINode::Create(Ty, (Record.size()-1)/2);
      InstructionList.push_back(PN);

      for (unsigned i = 0, e = Record.size()-1; i != e; i += 2) {
        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, 1+i, NextValueNo, Ty);
        else
          V = getValue(Record, 1+i, NextValueNo, Ty);
        BasicBlock *BB = getBasicBlock(Record[2+i]);
        if (!V || !BB)
          return error("Invalid record");
        PN->addIncoming(V, BB);
      }
      I = PN;
      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 {
        IGC_ASSERT(BitCode == bitc::FUNC_CODE_INST_LANDINGPAD_OLD);
        if (Record.size() < 4)
          return error("Invalid record");
      }
      Type *Ty = getTypeByID(Record[Idx++]);
      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");
        }

        IGC_ASSERT((CT != LandingPadInst::Catch ||
                !isa<ArrayType>(Val->getType())) &&
               "Catch clause has a invalid type!");
        IGC_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");
      uint64_t AlignRecord = Record[3];
      const uint64_t InAllocaMask = uint64_t(1) << 5;
      const uint64_t ExplicitTypeMask = uint64_t(1) << 6;
      const uint64_t SwiftErrorMask = uint64_t(1) << 7;
      const uint64_t FlagMask = InAllocaMask | ExplicitTypeMask |
                                SwiftErrorMask;
      bool InAlloca = AlignRecord & InAllocaMask;
      bool SwiftError = AlignRecord & SwiftErrorMask;
      Type *Ty = getTypeByID(Record[0]);
      if ((AlignRecord & ExplicitTypeMask) == 0) {
        auto *PTy = dyn_cast_or_null<PointerType>(Ty);
        if (!PTy)
          return error("Old-style alloca with a non-pointer type");
        Ty = PTy->getElementType();
      }
      Type *OpTy = getTypeByID(Record[1]);
      Value *Size = getFnValueByID(Record[2], OpTy);
      unsigned Align;
      if (Error Err = parseAlignmentValue(AlignRecord & ~FlagMask, 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();

      AllocaInst *AI = new AllocaInst(Ty, AS, Size, Align);
      AI->setUsedWithInAlloca(InAlloca);
      AI->setSwiftError(SwiftError);
      I = AI;
      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) ||
          (OpNum + 2 != Record.size() && OpNum + 3 != Record.size()))
        return error("Invalid record");

      Type *Ty = nullptr;
      if (OpNum + 3 == Record.size())
        Ty = getTypeByID(Record[OpNum++]);
      if (Error Err = typeCheckLoadStoreInst(Ty, Op->getType()))
        return Err;
      if (!Ty)
        Ty = cast<PointerType>(Op->getType())->getElementType();

      unsigned Align;
      if (Error Err = parseAlignmentValue(Record[OpNum], Align))
        return Err;
      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) ||
          (OpNum + 4 != Record.size() && OpNum + 5 != Record.size()))
        return error("Invalid record");

      Type *Ty = nullptr;
      if (OpNum + 5 == Record.size())
        Ty = getTypeByID(Record[OpNum++]);
      if (Error Err = typeCheckLoadStoreInst(Ty, Op->getType()))
        return Err;
      if (!Ty)
        Ty = cast<PointerType>(Op->getType())->getElementType();

      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]);

      unsigned Align;
      if (Error Err = parseAlignmentValue(Record[OpNum], Align))
        return Err;
      I = new LoadInst(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;
      if (getValueTypePair(Record, OpNum, NextValueNo, Ptr) ||
          (BitCode == bitc::FUNC_CODE_INST_STORE
               ? getValueTypePair(Record, OpNum, NextValueNo, Val)
               : popValue(Record, OpNum, NextValueNo,
                          cast<PointerType>(Ptr->getType())->getElementType(),
                          Val)) ||
          OpNum + 2 != Record.size())
        return error("Invalid record");

      if (Error Err = typeCheckLoadStoreInst(Val->getType(), Ptr->getType()))
        return Err;
      unsigned Align;
      if (Error Err = parseAlignmentValue(Record[OpNum], Align))
        return Err;
      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;
      if (getValueTypePair(Record, OpNum, NextValueNo, Ptr) ||
          !isa<PointerType>(Ptr->getType()) ||
          (BitCode == bitc::FUNC_CODE_INST_STOREATOMIC
               ? getValueTypePair(Record, OpNum, NextValueNo, Val)
               : popValue(Record, OpNum, NextValueNo,
                          cast<PointerType>(Ptr->getType())->getElementType(),
                          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");

      unsigned Align;
      if (Error Err = parseAlignmentValue(Record[OpNum], Align))
        return Err;
      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) ||
          (BitCode == bitc::FUNC_CODE_INST_CMPXCHG
               ? getValueTypePair(Record, OpNum, NextValueNo, Cmp)
               : popValue(Record, OpNum, NextValueNo,
                          cast<PointerType>(Ptr->getType())->getElementType(),
                          Cmp)) ||
          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]);

      I = new AtomicCmpXchgInst(Ptr, Cmp, New, SuccessOrdering, FailureOrdering,
                                SSID);
      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);
      } 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) ||
          !isa<PointerType>(Ptr->getType()) ||
          popValue(Record, OpNum, NextValueNo,
                    cast<PointerType>(Ptr->getType())->getElementType(), 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]);
      I = new AtomicRMWInst(Operation, Ptr, Val, Ordering, SSID);
      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;
      if (CCInfo >> bitc::CALL_EXPLICIT_TYPE & 1 &&
          !(FTy = dyn_cast<FunctionType>(getTypeByID(Record[OpNum++]))))
        return error("Explicit call type is not a function type");

      Value *Callee;
      if (getValueTypePair(Record, OpNum, NextValueNo, Callee))
        return error("Invalid record");

      PointerType *OpTy = dyn_cast<PointerType>(Callee->getType());
      if (!OpTy)
        return error("Callee is not a pointer type");
      if (!FTy) {
        FTy = dyn_cast<FunctionType>(OpTy->getElementType());
        if (!FTy)
          return error("Callee is not of pointer to function type");
      } else if (OpTy->getElementType() != 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 = CallInst::Create(FTy, Callee, Args, OperandBundles);
      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);
      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);
      Type *ResTy = getTypeByID(Record[2]);
      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.size() < 1 || 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;
    }
    }

    // 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 && !I->getType()->isVoidTy())
      ValueList.assignValue(I, NextValueNo++);
  }

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.
    IGC_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);
  IGC_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.
  Stream.JumpToBit(DFII->second);

  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
      CallSite(*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());
    }
  }

  // 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);

  UpgradeRetainReleaseMarker(*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];
  IGC_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);
  // 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();

  IGC_ASSERT(Offset > 0 && "Expected non-zero VST offset");
  uint64_t CurrentBit = jumpToValueSymbolTable(Offset, Stream);

  if (Stream.EnterSubBlock(bitc::VALUE_SYMTAB_BLOCK_ID))
    return error("Invalid record");

  SmallVector<uint64_t, 64> Record;

  // Read all the records for this value table.
  SmallString<128> ValueName;

  while (true) {
    BitstreamEntry Entry = Stream.advanceSkippingSubblocks();

    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.
      Stream.JumpToBit(CurrentBit);
      return Error::success();
    case BitstreamEntry::Record:
      // The interesting case.
      break;
    }

    // Read a record.
    Record.clear();
    switch (Stream.readRecord(Entry.ID, Record)) {
    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];
      IGC_ASSERT(!SourceFileName.empty());
      auto VLI = ValueIdToLinkageMap.find(ValueID);
      IGC_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];
      IGC_ASSERT(!SourceFileName.empty());
      auto VLI = ValueIdToLinkageMap.find(ValueID);
      IGC_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 (Stream.EnterSubBlock(bitc::MODULE_BLOCK_ID))
    return error("Invalid record");

  SmallVector<uint64_t, 64> Record;
  DenseMap<unsigned, GlobalValue::LinkageTypes> ValueIdToLinkageMap;
  unsigned ValueId = 0;

  // Read the index for this module.
  while (true) {
    BitstreamEntry Entry = Stream.advance();

    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 (Stream.SkipBlock())
          return error("Invalid record");
        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.
        IGC_ASSERT(((SeenValueSymbolTable && VSTOffset > 0) ||
                !SeenGlobalValSummary) &&
               "Expected early VST parse via VSTOffset record");
        if (Stream.SkipBlock())
          return error("Invalid record");
        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();
        IGC_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();
        auto BitCode = Stream.readRecord(Entry.ID, Record);
        switch (BitCode) {
        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) {
            IGC_ASSERT(!(Val >> 32) && "Unexpected high bits set");
            Hash[Pos++] = Val;
          }
          break;
        }
        /// MODULE_CODE_VSTOFFSET: [offset]
        case bitc::MODULE_CODE_VSTOFFSET:
          if (Record.size() < 1)
            return error("Invalid record");
          // Note that we subtract 1 here because the offset is relative to one
          // word before the start of the identification or module block, which
          // was 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 += (size_t)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 void setImmutableRefs(std::vector<ValueInfo> &Refs, unsigned Count) {
  // Read-only refs are in the end of the refs list.
  for (unsigned RefNo = Refs.size() - Count; RefNo < Refs.size(); ++RefNo)
    Refs[RefNo].setReadOnly();
}

// Eagerly parse the entire summary block. This populates the GlobalValueSummary
// objects in the index.
Error ModuleSummaryIndexBitcodeReader::parseEntireSummary(unsigned ID) {
  if (Stream.EnterSubBlock(ID))
    return error("Invalid record");
  SmallVector<uint64_t, 64> Record;

  // Parse version
  {
    BitstreamEntry Entry = Stream.advanceSkippingSubblocks();
    if (Entry.Kind != BitstreamEntry::Record)
      return error("Invalid Summary Block: record for version expected");
    if (Stream.readRecord(Entry.ID, Record) != 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 > 6)
    return error("Invalid summary version " + Twine(Version) +
                 ". Version should be in the range [1-6].");
  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;

  while (true) {
    BitstreamEntry Entry = Stream.advanceSkippingSubblocks();

    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();
    auto BitCode = Stream.readRecord(Entry.ID, Record);
    switch (BitCode) {
    default: // Default behavior: ignore.
      break;
    case bitc::FS_FLAGS: {  // [flags]
      uint64_t Flags = Record[0];
      // Scan flags.
      IGC_ASSERT(Flags <= 0x1f && "Unexpected bits in flag");

      // 1 bit: WithGlobalValueDeadStripping flag.
      // Set on combined index only.
      if (Flags & 0x1)
        TheIndex.setWithGlobalValueDeadStripping();
      // 1 bit: SkipModuleByDistributedBackend flag.
      // Set on combined index only.
      if (Flags & 0x2)
        TheIndex.setSkipModuleByDistributedBackend();
      // 1 bit: HasSyntheticEntryCounts flag.
      // Set on combined index only.
      if (Flags & 0x4)
        TheIndex.setHasSyntheticEntryCounts();
      // 1 bit: DisableSplitLTOUnit flag.
      // Set on per module indexes. It is up to the client to validate
      // the consistency of this flag across modules being linked.
      if (Flags & 0x8)
        TheIndex.setEnableSplitLTOUnit();
      // 1 bit: PartiallySplitLTOUnits flag.
      // Set on combined index only.
      if (Flags & 0x10)
        TheIndex.setPartiallySplitLTOUnits();
      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 NumImmutableRefs = 0;
      int RefListStartIndex = 4;
      if (Version >= 4) {
        RawFunFlags = Record[3];
        NumRefs = Record[4];
        RefListStartIndex = 5;
        if (Version >= 5) {
          NumImmutableRefs = Record[5];
          RefListStartIndex = 6;
        }
      }

      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;
      IGC_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);
      setImmutableRefs(Refs, NumImmutableRefs);
      auto FS = llvm::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));
      PendingTypeTests.clear();
      PendingTypeTestAssumeVCalls.clear();
      PendingTypeCheckedLoadVCalls.clear();
      PendingTypeTestAssumeConstVCalls.clear();
      PendingTypeCheckedLoadConstVCalls.clear();
      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 = llvm::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());

      GlobalValue::GUID AliaseeGUID =
          getValueInfoFromValueId(AliaseeID).first.getGUID();
      auto AliaseeInModule =
          TheIndex.findSummaryInModule(AliaseeGUID, ModulePath);
      if (!AliaseeInModule)
        return error("Alias expects aliasee summary to be parsed");
      AS->setAliasee(AliaseeInModule);
      AS->setAliaseeGUID(AliaseeGUID);

      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;
      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 =
          llvm::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_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 NumImmutableRefs = 0;
      int RefListStartIndex = 5;

      if (Version >= 4) {
        RawFunFlags = Record[4];
        RefListStartIndex = 6;
        size_t NumRefsIndex = 5;
        if (Version >= 5) {
          RefListStartIndex = 7;
          if (Version >= 6) {
            NumRefsIndex = 6;
            EntryCount = Record[5];
            RefListStartIndex = 8;
          }
          NumImmutableRefs = Record[RefListStartIndex - 1];
        }
        NumRefs = Record[NumRefsIndex];
      }

      auto Flags = getDecodedGVSummaryFlags(RawFlags, Version);
      int CallGraphEdgeStartIndex = RefListStartIndex + NumRefs;
      IGC_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;
      setImmutableRefs(Refs, NumImmutableRefs);
      auto FS = llvm::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));
      PendingTypeTests.clear();
      PendingTypeTestAssumeVCalls.clear();
      PendingTypeCheckedLoadVCalls.clear();
      PendingTypeTestAssumeConstVCalls.clear();
      PendingTypeCheckedLoadConstVCalls.clear();
      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 = llvm::make_unique<AliasSummary>(Flags);
      LastSeenSummary = AS.get();
      AS->setModulePath(ModuleIdMap[ModuleId]);

      auto AliaseeGUID =
          getValueInfoFromValueId(AliaseeValueId).first.getGUID();
      auto AliaseeInModule =
          TheIndex.findSummaryInModule(AliaseeGUID, AS->modulePath());
      AS->setAliasee(AliaseeInModule);
      AS->setAliaseeGUID(AliaseeGUID);

      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;
      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 =
          llvm::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:
      IGC_ASSERT(PendingTypeTests.empty());
      PendingTypeTests.insert(PendingTypeTests.end(), Record.begin(),
                              Record.end());
      break;

    case bitc::FS_TYPE_TEST_ASSUME_VCALLS:
      IGC_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:
      IGC_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;
    }
  }
  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 (Stream.EnterSubBlock(bitc::MODULE_STRTAB_BLOCK_ID))
    return error("Invalid record");

  SmallVector<uint64_t, 64> Record;

  SmallString<128> ModulePath;
  ModuleSummaryIndex::ModuleInfo *LastSeenModule = nullptr;

  while (true) {
    BitstreamEntry Entry = Stream.advanceSkippingSubblocks();

    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();
    switch (Stream.readRecord(Entry.ID, Record)) {
    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) {
        IGC_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 upgrader {

    // 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!");
        }
    };

    static ManagedStatic<BitcodeErrorCategoryType> ErrorCategory;

    const std::error_category &BitcodeErrorCategory() {
        return *ErrorCategory;
    }

    static Expected<StringRef> readBlobInRecord(BitstreamCursor &Stream,
        unsigned Block, unsigned RecordID) {
        if (Stream.EnterSubBlock(Block))
            return error("Invalid record");

        StringRef Strtab;
        while (true) {
            BitstreamEntry Entry = Stream.advance();
            switch (Entry.Kind) {
            case BitstreamEntry::EndBlock:
                return Strtab;

            case BitstreamEntry::Error:
                return error("Malformed block");

            case BitstreamEntry::SubBlock:
                if (Stream.SkipBlock())
                    return error("Malformed block");
                break;

            case BitstreamEntry::Record:
                StringRef Blob;
                SmallVector<uint64_t, 1> Record;
                if (Stream.readRecord(Entry.ID, Record, &Blob) == RecordID)
                    Strtab = Blob;
                break;
            }
        }
    }

    //===----------------------------------------------------------------------===//
    // External interface
    //===----------------------------------------------------------------------===//

    Expected<std::vector<BitcodeModule>>
        getBitcodeModuleList(MemoryBufferRef Buffer) {
        auto FOrErr = upgrader::getBitcodeFileContents(Buffer);
        if (!FOrErr)
            return FOrErr.takeError();
        return std::move(FOrErr->Mods);
    }

    Expected<BitcodeFileContents>
        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. 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;

            BitstreamEntry Entry = Stream.advance();
            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 (Stream.SkipBlock())
                        return error("Malformed block");

                    Entry = Stream.advance();
                    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 (Stream.SkipBlock())
                        return error("Malformed block");

                    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 (Stream.SkipBlock())
                    return error("Malformed block");
                continue;
            }
            case BitstreamEntry::Record:
                Stream.skipRecord(Entry.ID);
                continue;
            }
        }
    }

    /// 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) {
        BitstreamCursor Stream(Buffer);

        std::string ProducerIdentification;
        if (IdentificationBit != -1ull) {
            Stream.JumpToBit(IdentificationBit);
            Expected<std::string> ProducerIdentificationOrErr =
                readIdentificationBlock(Stream);
            if (!ProducerIdentificationOrErr)
                return ProducerIdentificationOrErr.takeError();

            ProducerIdentification = *ProducerIdentificationOrErr;
        }

        Stream.JumpToBit(ModuleBit);
        auto *R = new BitcodeReader(std::move(Stream), Strtab, ProducerIdentification,
            Context);

        std::unique_ptr<Module> M =
            llvm::make_unique<Module>(ModuleIdentifier, Context);
        M->setMaterializer(R);

        // Delay parsing Metadata if ShouldLazyLoadMetadata is true.
        if (Error Err =
            R->parseBitcodeInto(M.get(), ShouldLazyLoadMetadata, IsImporting))
            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);
    }

    // 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);
        Stream.JumpToBit(ModuleBit);

        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);
        Stream.JumpToBit(ModuleBit);

        auto Index = llvm::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 (Stream.EnterSubBlock(ID))
            return error("Invalid record");
        SmallVector<uint64_t, 64> Record;

        while (true) {
            BitstreamEntry Entry = Stream.advanceSkippingSubblocks();

            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();
            auto BitCode = Stream.readRecord(Entry.ID, Record);
            switch (BitCode) {
            default: // Default behavior: ignore.
                break;
            case bitc::FS_FLAGS: { // [flags]
                uint64_t Flags = Record[0];
                // Scan flags.
                IGC_ASSERT(Flags <= 0x1f && "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);
        Stream.JumpToBit(ModuleBit);

        if (Stream.EnterSubBlock(bitc::MODULE_BLOCK_ID))
            return error("Invalid record");

        while (true) {
            BitstreamEntry Entry = Stream.advance();

            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 (Stream.SkipBlock())
                    return error("Malformed block");
                continue;

            case BitstreamEntry::Record:
                Stream.skipRecord(Entry.ID);
                continue;
            }
        }
    }

    static Expected<BitcodeModule> getSingleModule(MemoryBufferRef Buffer) {
        Expected<std::vector<BitcodeModule>> MsOrErr = upgrader::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>>
        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>> getOwningLazyBitcodeModule(
        std::unique_ptr<MemoryBuffer> &&Buffer, LLVMContext &Context,
        bool ShouldLazyLoadMetadata, bool IsImporting) {
        auto MOrErr = upgrader::getLazyBitcodeModule(*Buffer, Context, ShouldLazyLoadMetadata,
            IsImporting);
        if (MOrErr)
            (*MOrErr)->setOwnedMemoryBuffer(std::move(Buffer));
        return MOrErr;
    }

    Expected<std::unique_ptr<Module>>
        BitcodeModule::parseModule(LLVMContext &Context) {
        return getModuleImpl(Context, true, false, false);
        // 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>> parseBitcodeFile(MemoryBufferRef Buffer,
        LLVMContext &Context) {
        Expected<BitcodeModule> BM = getSingleModule(Buffer);
        if (!BM)
            return BM.takeError();

        return BM->parseModule(Context);
    }

    Expected<std::string> getBitcodeTargetTriple(MemoryBufferRef Buffer) {
        Expected<BitstreamCursor> StreamOrErr = initStream(Buffer);
        if (!StreamOrErr)
            return StreamOrErr.takeError();

        return readTriple(*StreamOrErr);
    }

    Expected<bool> isBitcodeContainingObjCCategory(MemoryBufferRef Buffer) {
        Expected<BitstreamCursor> StreamOrErr = initStream(Buffer);
        if (!StreamOrErr)
            return StreamOrErr.takeError();

        return hasObjCCategory(*StreamOrErr);
    }

    Expected<std::string> getBitcodeProducerString(MemoryBufferRef Buffer) {
        Expected<BitstreamCursor> StreamOrErr = initStream(Buffer);
        if (!StreamOrErr)
            return StreamOrErr.takeError();

        return readIdentificationCode(*StreamOrErr);
    }

    Error 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>>
        getModuleSummaryIndex(MemoryBufferRef Buffer) {
        Expected<BitcodeModule> BM = getSingleModule(Buffer);
        if (!BM)
            return BM.takeError();

        return BM->getSummary();
    }

    Expected<BitcodeLTOInfo> getBitcodeLTOInfo(MemoryBufferRef Buffer) {
        Expected<BitcodeModule> BM = getSingleModule(Buffer);
        if (!BM)
            return BM.takeError();

        return BM->getLTOInfo();
    }

    Expected<std::unique_ptr<ModuleSummaryIndex>>
        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 upgrader::getModuleSummaryIndex(**FileOrErr);
    }

}
