//===-- LLVMContextImpl.h - The LLVMContextImpl opaque class ----*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//  This file declares LLVMContextImpl, the opaque implementation 
//  of LLVMContext.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_LIB_IR_LLVMCONTEXTIMPL_H
#define LLVM_LIB_IR_LLVMCONTEXTIMPL_H

#include "AttributeImpl.h"
#include "ConstantsContext.h"
#include "llvm/ADT/APFloat.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/FoldingSet.h"
#include "llvm/ADT/Hashing.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Metadata.h"
#include "llvm/IR/ValueHandle.h"
#include "llvm/Support/Dwarf.h"
#include <vector>

namespace llvm {

class ConstantInt;
class ConstantFP;
class DiagnosticInfoOptimizationRemark;
class DiagnosticInfoOptimizationRemarkMissed;
class DiagnosticInfoOptimizationRemarkAnalysis;
class GCStrategy;
class LLVMContext;
class Type;
class Value;

struct DenseMapAPIntKeyInfo {
  static inline APInt getEmptyKey() {
    APInt V(nullptr, 0);
    V.VAL = 0;
    return V;
  }
  static inline APInt getTombstoneKey() {
    APInt V(nullptr, 0);
    V.VAL = 1;
    return V;
  }
  static unsigned getHashValue(const APInt &Key) {
    return static_cast<unsigned>(hash_value(Key));
  }
  static bool isEqual(const APInt &LHS, const APInt &RHS) {
    return LHS.getBitWidth() == RHS.getBitWidth() && LHS == RHS;
  }
};

struct DenseMapAPFloatKeyInfo {
  static inline APFloat getEmptyKey() { return APFloat(APFloat::Bogus, 1); }
  static inline APFloat getTombstoneKey() { return APFloat(APFloat::Bogus, 2); }
  static unsigned getHashValue(const APFloat &Key) {
    return static_cast<unsigned>(hash_value(Key));
  }
  static bool isEqual(const APFloat &LHS, const APFloat &RHS) {
    return LHS.bitwiseIsEqual(RHS);
  }
};

struct AnonStructTypeKeyInfo {
  struct KeyTy {
    ArrayRef<Type*> ETypes;
    bool isPacked;
    KeyTy(const ArrayRef<Type*>& E, bool P) :
      ETypes(E), isPacked(P) {}
    KeyTy(const StructType *ST)
        : ETypes(ST->elements()), isPacked(ST->isPacked()) {}
    bool operator==(const KeyTy& that) const {
      if (isPacked != that.isPacked)
        return false;
      if (ETypes != that.ETypes)
        return false;
      return true;
    }
    bool operator!=(const KeyTy& that) const {
      return !this->operator==(that);
    }
  };
  static inline StructType* getEmptyKey() {
    return DenseMapInfo<StructType*>::getEmptyKey();
  }
  static inline StructType* getTombstoneKey() {
    return DenseMapInfo<StructType*>::getTombstoneKey();
  }
  static unsigned getHashValue(const KeyTy& Key) {
    return hash_combine(hash_combine_range(Key.ETypes.begin(),
                                           Key.ETypes.end()),
                        Key.isPacked);
  }
  static unsigned getHashValue(const StructType *ST) {
    return getHashValue(KeyTy(ST));
  }
  static bool isEqual(const KeyTy& LHS, const StructType *RHS) {
    if (RHS == getEmptyKey() || RHS == getTombstoneKey())
      return false;
    return LHS == KeyTy(RHS);
  }
  static bool isEqual(const StructType *LHS, const StructType *RHS) {
    return LHS == RHS;
  }
};

struct FunctionTypeKeyInfo {
  struct KeyTy {
    const Type *ReturnType;
    ArrayRef<Type*> Params;
    bool isVarArg;
    KeyTy(const Type* R, const ArrayRef<Type*>& P, bool V) :
      ReturnType(R), Params(P), isVarArg(V) {}
    KeyTy(const FunctionType *FT)
        : ReturnType(FT->getReturnType()), Params(FT->params()),
          isVarArg(FT->isVarArg()) {}
    bool operator==(const KeyTy& that) const {
      if (ReturnType != that.ReturnType)
        return false;
      if (isVarArg != that.isVarArg)
        return false;
      if (Params != that.Params)
        return false;
      return true;
    }
    bool operator!=(const KeyTy& that) const {
      return !this->operator==(that);
    }
  };
  static inline FunctionType* getEmptyKey() {
    return DenseMapInfo<FunctionType*>::getEmptyKey();
  }
  static inline FunctionType* getTombstoneKey() {
    return DenseMapInfo<FunctionType*>::getTombstoneKey();
  }
  static unsigned getHashValue(const KeyTy& Key) {
    return hash_combine(Key.ReturnType,
                        hash_combine_range(Key.Params.begin(),
                                           Key.Params.end()),
                        Key.isVarArg);
  }
  static unsigned getHashValue(const FunctionType *FT) {
    return getHashValue(KeyTy(FT));
  }
  static bool isEqual(const KeyTy& LHS, const FunctionType *RHS) {
    if (RHS == getEmptyKey() || RHS == getTombstoneKey())
      return false;
    return LHS == KeyTy(RHS);
  }
  static bool isEqual(const FunctionType *LHS, const FunctionType *RHS) {
    return LHS == RHS;
  }
};

/// \brief Structure for hashing arbitrary MDNode operands.
class MDNodeOpsKey {
  ArrayRef<Metadata *> RawOps;
  ArrayRef<MDOperand> Ops;

  unsigned Hash;

protected:
  MDNodeOpsKey(ArrayRef<Metadata *> Ops)
      : RawOps(Ops), Hash(calculateHash(Ops)) {}

  template <class NodeTy>
  MDNodeOpsKey(const NodeTy *N, unsigned Offset = 0)
      : Ops(N->op_begin() + Offset, N->op_end()), Hash(N->getHash()) {}

  template <class NodeTy>
  bool compareOps(const NodeTy *RHS, unsigned Offset = 0) const {
    if (getHash() != RHS->getHash())
      return false;

    assert((RawOps.empty() || Ops.empty()) && "Two sets of operands?");
    return RawOps.empty() ? compareOps(Ops, RHS, Offset)
                          : compareOps(RawOps, RHS, Offset);
  }

  static unsigned calculateHash(MDNode *N, unsigned Offset = 0);

private:
  template <class T>
  static bool compareOps(ArrayRef<T> Ops, const MDNode *RHS, unsigned Offset) {
    if (Ops.size() != RHS->getNumOperands() - Offset)
      return false;
    return std::equal(Ops.begin(), Ops.end(), RHS->op_begin() + Offset);
  }

  static unsigned calculateHash(ArrayRef<Metadata *> Ops);

public:
  unsigned getHash() const { return Hash; }
};

template <class NodeTy> struct MDNodeKeyImpl;
template <class NodeTy> struct MDNodeInfo;

/// Configuration point for MDNodeInfo::isEqual().
template <class NodeTy> struct MDNodeSubsetEqualImpl {
  typedef MDNodeKeyImpl<NodeTy> KeyTy;
  static bool isSubsetEqual(const KeyTy &LHS, const NodeTy *RHS) {
    return false;
  }
  static bool isSubsetEqual(const NodeTy *LHS, const NodeTy *RHS) {
    return false;
  }
};

/// \brief DenseMapInfo for MDTuple.
///
/// Note that we don't need the is-function-local bit, since that's implicit in
/// the operands.
template <> struct MDNodeKeyImpl<MDTuple> : MDNodeOpsKey {
  MDNodeKeyImpl(ArrayRef<Metadata *> Ops) : MDNodeOpsKey(Ops) {}
  MDNodeKeyImpl(const MDTuple *N) : MDNodeOpsKey(N) {}

  bool isKeyOf(const MDTuple *RHS) const { return compareOps(RHS); }

  unsigned getHashValue() const { return getHash(); }

  static unsigned calculateHash(MDTuple *N) {
    return MDNodeOpsKey::calculateHash(N);
  }
};

/// \brief DenseMapInfo for DILocation.
template <> struct MDNodeKeyImpl<DILocation> {
  unsigned Line;
  unsigned Column;
  Metadata *Scope;
  Metadata *InlinedAt;

  MDNodeKeyImpl(unsigned Line, unsigned Column, Metadata *Scope,
                Metadata *InlinedAt)
      : Line(Line), Column(Column), Scope(Scope), InlinedAt(InlinedAt) {}

  MDNodeKeyImpl(const DILocation *L)
      : Line(L->getLine()), Column(L->getColumn()), Scope(L->getRawScope()),
        InlinedAt(L->getRawInlinedAt()) {}

  bool isKeyOf(const DILocation *RHS) const {
    return Line == RHS->getLine() && Column == RHS->getColumn() &&
           Scope == RHS->getRawScope() && InlinedAt == RHS->getRawInlinedAt();
  }
  unsigned getHashValue() const {
    return hash_combine(Line, Column, Scope, InlinedAt);
  }
};

/// \brief DenseMapInfo for GenericDINode.
template <> struct MDNodeKeyImpl<GenericDINode> : MDNodeOpsKey {
  unsigned Tag;
  MDString *Header;
  MDNodeKeyImpl(unsigned Tag, MDString *Header, ArrayRef<Metadata *> DwarfOps)
      : MDNodeOpsKey(DwarfOps), Tag(Tag), Header(Header) {}
  MDNodeKeyImpl(const GenericDINode *N)
      : MDNodeOpsKey(N, 1), Tag(N->getTag()), Header(N->getRawHeader()) {}

  bool isKeyOf(const GenericDINode *RHS) const {
    return Tag == RHS->getTag() && Header == RHS->getRawHeader() &&
           compareOps(RHS, 1);
  }

  unsigned getHashValue() const { return hash_combine(getHash(), Tag, Header); }

  static unsigned calculateHash(GenericDINode *N) {
    return MDNodeOpsKey::calculateHash(N, 1);
  }
};

template <> struct MDNodeKeyImpl<DISubrange> {
  int64_t Count;
  int64_t LowerBound;

  MDNodeKeyImpl(int64_t Count, int64_t LowerBound)
      : Count(Count), LowerBound(LowerBound) {}
  MDNodeKeyImpl(const DISubrange *N)
      : Count(N->getCount()), LowerBound(N->getLowerBound()) {}

  bool isKeyOf(const DISubrange *RHS) const {
    return Count == RHS->getCount() && LowerBound == RHS->getLowerBound();
  }
  unsigned getHashValue() const { return hash_combine(Count, LowerBound); }
};

template <> struct MDNodeKeyImpl<DIEnumerator> {
  int64_t Value;
  MDString *Name;

  MDNodeKeyImpl(int64_t Value, MDString *Name) : Value(Value), Name(Name) {}
  MDNodeKeyImpl(const DIEnumerator *N)
      : Value(N->getValue()), Name(N->getRawName()) {}

  bool isKeyOf(const DIEnumerator *RHS) const {
    return Value == RHS->getValue() && Name == RHS->getRawName();
  }
  unsigned getHashValue() const { return hash_combine(Value, Name); }
};

template <> struct MDNodeKeyImpl<DIBasicType> {
  unsigned Tag;
  MDString *Name;
  uint64_t SizeInBits;
  uint64_t AlignInBits;
  unsigned Encoding;

  MDNodeKeyImpl(unsigned Tag, MDString *Name, uint64_t SizeInBits,
                uint64_t AlignInBits, unsigned Encoding)
      : Tag(Tag), Name(Name), SizeInBits(SizeInBits), AlignInBits(AlignInBits),
        Encoding(Encoding) {}
  MDNodeKeyImpl(const DIBasicType *N)
      : Tag(N->getTag()), Name(N->getRawName()), SizeInBits(N->getSizeInBits()),
        AlignInBits(N->getAlignInBits()), Encoding(N->getEncoding()) {}

  bool isKeyOf(const DIBasicType *RHS) const {
    return Tag == RHS->getTag() && Name == RHS->getRawName() &&
           SizeInBits == RHS->getSizeInBits() &&
           AlignInBits == RHS->getAlignInBits() &&
           Encoding == RHS->getEncoding();
  }
  unsigned getHashValue() const {
    return hash_combine(Tag, Name, SizeInBits, AlignInBits, Encoding);
  }
};

template <> struct MDNodeKeyImpl<DIDerivedType> {
  unsigned Tag;
  MDString *Name;
  Metadata *File;
  unsigned Line;
  Metadata *Scope;
  Metadata *BaseType;
  uint64_t SizeInBits;
  uint64_t AlignInBits;
  uint64_t OffsetInBits;
  unsigned Flags;
  Metadata *ExtraData;

  MDNodeKeyImpl(unsigned Tag, MDString *Name, Metadata *File, unsigned Line,
                Metadata *Scope, Metadata *BaseType, uint64_t SizeInBits,
                uint64_t AlignInBits, uint64_t OffsetInBits, unsigned Flags,
                Metadata *ExtraData)
      : Tag(Tag), Name(Name), File(File), Line(Line), Scope(Scope),
        BaseType(BaseType), SizeInBits(SizeInBits), AlignInBits(AlignInBits),
        OffsetInBits(OffsetInBits), Flags(Flags), ExtraData(ExtraData) {}
  MDNodeKeyImpl(const DIDerivedType *N)
      : Tag(N->getTag()), Name(N->getRawName()), File(N->getRawFile()),
        Line(N->getLine()), Scope(N->getRawScope()),
        BaseType(N->getRawBaseType()), SizeInBits(N->getSizeInBits()),
        AlignInBits(N->getAlignInBits()), OffsetInBits(N->getOffsetInBits()),
        Flags(N->getFlags()), ExtraData(N->getRawExtraData()) {}

  bool isKeyOf(const DIDerivedType *RHS) const {
    return Tag == RHS->getTag() && Name == RHS->getRawName() &&
           File == RHS->getRawFile() && Line == RHS->getLine() &&
           Scope == RHS->getRawScope() && BaseType == RHS->getRawBaseType() &&
           SizeInBits == RHS->getSizeInBits() &&
           AlignInBits == RHS->getAlignInBits() &&
           OffsetInBits == RHS->getOffsetInBits() && Flags == RHS->getFlags() &&
           ExtraData == RHS->getRawExtraData();
  }
  unsigned getHashValue() const {
    // If this is a member inside an ODR type, only hash the type and the name.
    // Otherwise the hash will be stronger than
    // MDNodeSubsetEqualImpl::isODRMember().
    if (Tag == dwarf::DW_TAG_member && Name)
      if (auto *CT = dyn_cast_or_null<DICompositeType>(Scope))
        if (CT->getRawIdentifier())
          return hash_combine(Name, Scope);

    // Intentionally computes the hash on a subset of the operands for
    // performance reason. The subset has to be significant enough to avoid
    // collision "most of the time". There is no correctness issue in case of
    // collision because of the full check above.
    return hash_combine(Tag, Name, File, Line, Scope, BaseType, Flags);
  }
};

template <> struct MDNodeSubsetEqualImpl<DIDerivedType> {
  typedef MDNodeKeyImpl<DIDerivedType> KeyTy;
  static bool isSubsetEqual(const KeyTy &LHS, const DIDerivedType *RHS) {
    return isODRMember(LHS.Tag, LHS.Scope, LHS.Name, RHS);
  }
  static bool isSubsetEqual(const DIDerivedType *LHS, const DIDerivedType *RHS) {
    return isODRMember(LHS->getTag(), LHS->getRawScope(), LHS->getRawName(),
                       RHS);
  }

  /// Subprograms compare equal if they declare the same function in an ODR
  /// type.
  static bool isODRMember(unsigned Tag, const Metadata *Scope,
                          const MDString *Name, const DIDerivedType *RHS) {
    // Check whether the LHS is eligible.
    if (Tag != dwarf::DW_TAG_member || !Name)
      return false;

    auto *CT = dyn_cast_or_null<DICompositeType>(Scope);
    if (!CT || !CT->getRawIdentifier())
      return false;

    // Compare to the RHS.
    return Tag == RHS->getTag() && Name == RHS->getRawName() &&
           Scope == RHS->getRawScope();
  }
};

template <> struct MDNodeKeyImpl<DICompositeType> {
  unsigned Tag;
  MDString *Name;
  Metadata *File;
  unsigned Line;
  Metadata *Scope;
  Metadata *BaseType;
  uint64_t SizeInBits;
  uint64_t AlignInBits;
  uint64_t OffsetInBits;
  unsigned Flags;
  Metadata *Elements;
  unsigned RuntimeLang;
  Metadata *VTableHolder;
  Metadata *TemplateParams;
  MDString *Identifier;

  MDNodeKeyImpl(unsigned Tag, MDString *Name, Metadata *File, unsigned Line,
                Metadata *Scope, Metadata *BaseType, uint64_t SizeInBits,
                uint64_t AlignInBits, uint64_t OffsetInBits, unsigned Flags,
                Metadata *Elements, unsigned RuntimeLang,
                Metadata *VTableHolder, Metadata *TemplateParams,
                MDString *Identifier)
      : Tag(Tag), Name(Name), File(File), Line(Line), Scope(Scope),
        BaseType(BaseType), SizeInBits(SizeInBits), AlignInBits(AlignInBits),
        OffsetInBits(OffsetInBits), Flags(Flags), Elements(Elements),
        RuntimeLang(RuntimeLang), VTableHolder(VTableHolder),
        TemplateParams(TemplateParams), Identifier(Identifier) {}
  MDNodeKeyImpl(const DICompositeType *N)
      : Tag(N->getTag()), Name(N->getRawName()), File(N->getRawFile()),
        Line(N->getLine()), Scope(N->getRawScope()),
        BaseType(N->getRawBaseType()), SizeInBits(N->getSizeInBits()),
        AlignInBits(N->getAlignInBits()), OffsetInBits(N->getOffsetInBits()),
        Flags(N->getFlags()), Elements(N->getRawElements()),
        RuntimeLang(N->getRuntimeLang()), VTableHolder(N->getRawVTableHolder()),
        TemplateParams(N->getRawTemplateParams()),
        Identifier(N->getRawIdentifier()) {}

  bool isKeyOf(const DICompositeType *RHS) const {
    return Tag == RHS->getTag() && Name == RHS->getRawName() &&
           File == RHS->getRawFile() && Line == RHS->getLine() &&
           Scope == RHS->getRawScope() && BaseType == RHS->getRawBaseType() &&
           SizeInBits == RHS->getSizeInBits() &&
           AlignInBits == RHS->getAlignInBits() &&
           OffsetInBits == RHS->getOffsetInBits() && Flags == RHS->getFlags() &&
           Elements == RHS->getRawElements() &&
           RuntimeLang == RHS->getRuntimeLang() &&
           VTableHolder == RHS->getRawVTableHolder() &&
           TemplateParams == RHS->getRawTemplateParams() &&
           Identifier == RHS->getRawIdentifier();
  }
  unsigned getHashValue() const {
    // Intentionally computes the hash on a subset of the operands for
    // performance reason. The subset has to be significant enough to avoid
    // collision "most of the time". There is no correctness issue in case of
    // collision because of the full check above.
    return hash_combine(Name, File, Line, BaseType, Scope, Elements,
                        TemplateParams);
  }
};

template <> struct MDNodeKeyImpl<DISubroutineType> {
  unsigned Flags;
  uint8_t CC;
  Metadata *TypeArray;

  MDNodeKeyImpl(unsigned Flags, uint8_t CC, Metadata *TypeArray)
      : Flags(Flags), CC(CC), TypeArray(TypeArray) {}
  MDNodeKeyImpl(const DISubroutineType *N)
      : Flags(N->getFlags()), CC(N->getCC()), TypeArray(N->getRawTypeArray()) {}

  bool isKeyOf(const DISubroutineType *RHS) const {
    return Flags == RHS->getFlags() && CC == RHS->getCC() &&
           TypeArray == RHS->getRawTypeArray();
  }
  unsigned getHashValue() const { return hash_combine(Flags, CC, TypeArray); }
};

template <> struct MDNodeKeyImpl<DIFile> {
  MDString *Filename;
  MDString *Directory;

  MDNodeKeyImpl(MDString *Filename, MDString *Directory)
      : Filename(Filename), Directory(Directory) {}
  MDNodeKeyImpl(const DIFile *N)
      : Filename(N->getRawFilename()), Directory(N->getRawDirectory()) {}

  bool isKeyOf(const DIFile *RHS) const {
    return Filename == RHS->getRawFilename() &&
           Directory == RHS->getRawDirectory();
  }
  unsigned getHashValue() const { return hash_combine(Filename, Directory); }
};

template <> struct MDNodeKeyImpl<DISubprogram> {
  Metadata *Scope;
  MDString *Name;
  MDString *LinkageName;
  Metadata *File;
  unsigned Line;
  Metadata *Type;
  bool IsLocalToUnit;
  bool IsDefinition;
  unsigned ScopeLine;
  Metadata *ContainingType;
  unsigned Virtuality;
  unsigned VirtualIndex;
  int ThisAdjustment;
  unsigned Flags;
  bool IsOptimized;
  Metadata *Unit;
  Metadata *TemplateParams;
  Metadata *Declaration;
  Metadata *Variables;

  MDNodeKeyImpl(Metadata *Scope, MDString *Name, MDString *LinkageName,
                Metadata *File, unsigned Line, Metadata *Type,
                bool IsLocalToUnit, bool IsDefinition, unsigned ScopeLine,
                Metadata *ContainingType, unsigned Virtuality,
                unsigned VirtualIndex, int ThisAdjustment, unsigned Flags,
                bool IsOptimized, Metadata *Unit, Metadata *TemplateParams,
                Metadata *Declaration, Metadata *Variables)
      : Scope(Scope), Name(Name), LinkageName(LinkageName), File(File),
        Line(Line), Type(Type), IsLocalToUnit(IsLocalToUnit),
        IsDefinition(IsDefinition), ScopeLine(ScopeLine),
        ContainingType(ContainingType), Virtuality(Virtuality),
        VirtualIndex(VirtualIndex), ThisAdjustment(ThisAdjustment),
        Flags(Flags), IsOptimized(IsOptimized), Unit(Unit),
        TemplateParams(TemplateParams), Declaration(Declaration),
        Variables(Variables) {}
  MDNodeKeyImpl(const DISubprogram *N)
      : Scope(N->getRawScope()), Name(N->getRawName()),
        LinkageName(N->getRawLinkageName()), File(N->getRawFile()),
        Line(N->getLine()), Type(N->getRawType()),
        IsLocalToUnit(N->isLocalToUnit()), IsDefinition(N->isDefinition()),
        ScopeLine(N->getScopeLine()), ContainingType(N->getRawContainingType()),
        Virtuality(N->getVirtuality()), VirtualIndex(N->getVirtualIndex()),
        ThisAdjustment(N->getThisAdjustment()), Flags(N->getFlags()),
        IsOptimized(N->isOptimized()), Unit(N->getRawUnit()),
        TemplateParams(N->getRawTemplateParams()),
        Declaration(N->getRawDeclaration()), Variables(N->getRawVariables()) {}

  bool isKeyOf(const DISubprogram *RHS) const {
    return Scope == RHS->getRawScope() && Name == RHS->getRawName() &&
           LinkageName == RHS->getRawLinkageName() &&
           File == RHS->getRawFile() && Line == RHS->getLine() &&
           Type == RHS->getRawType() && IsLocalToUnit == RHS->isLocalToUnit() &&
           IsDefinition == RHS->isDefinition() &&
           ScopeLine == RHS->getScopeLine() &&
           ContainingType == RHS->getRawContainingType() &&
           Virtuality == RHS->getVirtuality() &&
           VirtualIndex == RHS->getVirtualIndex() &&
           ThisAdjustment == RHS->getThisAdjustment() &&
           Flags == RHS->getFlags() && IsOptimized == RHS->isOptimized() &&
           Unit == RHS->getUnit() &&
           TemplateParams == RHS->getRawTemplateParams() &&
           Declaration == RHS->getRawDeclaration() &&
           Variables == RHS->getRawVariables();
  }
  unsigned getHashValue() const {
    // If this is a declaration inside an ODR type, only hash the type and the
    // name.  Otherwise the hash will be stronger than
    // MDNodeSubsetEqualImpl::isDeclarationOfODRMember().
    if (!IsDefinition && LinkageName)
      if (auto *CT = dyn_cast_or_null<DICompositeType>(Scope))
        if (CT->getRawIdentifier())
          return hash_combine(LinkageName, Scope);

    // Intentionally computes the hash on a subset of the operands for
    // performance reason. The subset has to be significant enough to avoid
    // collision "most of the time". There is no correctness issue in case of
    // collision because of the full check above.
    return hash_combine(Name, Scope, File, Type, Line);
  }
};

template <> struct MDNodeSubsetEqualImpl<DISubprogram> {
  typedef MDNodeKeyImpl<DISubprogram> KeyTy;
  static bool isSubsetEqual(const KeyTy &LHS, const DISubprogram *RHS) {
    return isDeclarationOfODRMember(LHS.IsDefinition, LHS.Scope,
                                    LHS.LinkageName, RHS);
  }
  static bool isSubsetEqual(const DISubprogram *LHS, const DISubprogram *RHS) {
    return isDeclarationOfODRMember(LHS->isDefinition(), LHS->getRawScope(),
                                    LHS->getRawLinkageName(), RHS);
  }

  /// Subprograms compare equal if they declare the same function in an ODR
  /// type.
  static bool isDeclarationOfODRMember(bool IsDefinition, const Metadata *Scope,
                                       const MDString *LinkageName,
                                       const DISubprogram *RHS) {
    // Check whether the LHS is eligible.
    if (IsDefinition || !Scope || !LinkageName)
      return false;

    auto *CT = dyn_cast_or_null<DICompositeType>(Scope);
    if (!CT || !CT->getRawIdentifier())
      return false;

    // Compare to the RHS.
    return IsDefinition == RHS->isDefinition() && Scope == RHS->getRawScope() &&
           LinkageName == RHS->getRawLinkageName();
  }
};

template <> struct MDNodeKeyImpl<DILexicalBlock> {
  Metadata *Scope;
  Metadata *File;
  unsigned Line;
  unsigned Column;

  MDNodeKeyImpl(Metadata *Scope, Metadata *File, unsigned Line, unsigned Column)
      : Scope(Scope), File(File), Line(Line), Column(Column) {}
  MDNodeKeyImpl(const DILexicalBlock *N)
      : Scope(N->getRawScope()), File(N->getRawFile()), Line(N->getLine()),
        Column(N->getColumn()) {}

  bool isKeyOf(const DILexicalBlock *RHS) const {
    return Scope == RHS->getRawScope() && File == RHS->getRawFile() &&
           Line == RHS->getLine() && Column == RHS->getColumn();
  }
  unsigned getHashValue() const {
    return hash_combine(Scope, File, Line, Column);
  }
};

template <> struct MDNodeKeyImpl<DILexicalBlockFile> {
  Metadata *Scope;
  Metadata *File;
  unsigned Discriminator;

  MDNodeKeyImpl(Metadata *Scope, Metadata *File, unsigned Discriminator)
      : Scope(Scope), File(File), Discriminator(Discriminator) {}
  MDNodeKeyImpl(const DILexicalBlockFile *N)
      : Scope(N->getRawScope()), File(N->getRawFile()),
        Discriminator(N->getDiscriminator()) {}

  bool isKeyOf(const DILexicalBlockFile *RHS) const {
    return Scope == RHS->getRawScope() && File == RHS->getRawFile() &&
           Discriminator == RHS->getDiscriminator();
  }
  unsigned getHashValue() const {
    return hash_combine(Scope, File, Discriminator);
  }
};

template <> struct MDNodeKeyImpl<DINamespace> {
  Metadata *Scope;
  Metadata *File;
  MDString *Name;
  unsigned Line;

  MDNodeKeyImpl(Metadata *Scope, Metadata *File, MDString *Name, unsigned Line)
      : Scope(Scope), File(File), Name(Name), Line(Line) {}
  MDNodeKeyImpl(const DINamespace *N)
      : Scope(N->getRawScope()), File(N->getRawFile()), Name(N->getRawName()),
        Line(N->getLine()) {}

  bool isKeyOf(const DINamespace *RHS) const {
    return Scope == RHS->getRawScope() && File == RHS->getRawFile() &&
           Name == RHS->getRawName() && Line == RHS->getLine();
  }
  unsigned getHashValue() const {
    return hash_combine(Scope, File, Name, Line);
  }
};

template <> struct MDNodeKeyImpl<DIModule> {
  Metadata *Scope;
  MDString *Name;
  MDString *ConfigurationMacros;
  MDString *IncludePath;
  MDString *ISysRoot;
  MDNodeKeyImpl(Metadata *Scope, MDString *Name, MDString *ConfigurationMacros,
                MDString *IncludePath, MDString *ISysRoot)
      : Scope(Scope), Name(Name), ConfigurationMacros(ConfigurationMacros),
        IncludePath(IncludePath), ISysRoot(ISysRoot) {}
  MDNodeKeyImpl(const DIModule *N)
      : Scope(N->getRawScope()), Name(N->getRawName()),
        ConfigurationMacros(N->getRawConfigurationMacros()),
        IncludePath(N->getRawIncludePath()), ISysRoot(N->getRawISysRoot()) {}

  bool isKeyOf(const DIModule *RHS) const {
    return Scope == RHS->getRawScope() && Name == RHS->getRawName() &&
           ConfigurationMacros == RHS->getRawConfigurationMacros() &&
           IncludePath == RHS->getRawIncludePath() &&
           ISysRoot == RHS->getRawISysRoot();
  }
  unsigned getHashValue() const {
    return hash_combine(Scope, Name,
                        ConfigurationMacros, IncludePath, ISysRoot);
  }
};

template <> struct MDNodeKeyImpl<DITemplateTypeParameter> {
  MDString *Name;
  Metadata *Type;

  MDNodeKeyImpl(MDString *Name, Metadata *Type) : Name(Name), Type(Type) {}
  MDNodeKeyImpl(const DITemplateTypeParameter *N)
      : Name(N->getRawName()), Type(N->getRawType()) {}

  bool isKeyOf(const DITemplateTypeParameter *RHS) const {
    return Name == RHS->getRawName() && Type == RHS->getRawType();
  }
  unsigned getHashValue() const { return hash_combine(Name, Type); }
};

template <> struct MDNodeKeyImpl<DITemplateValueParameter> {
  unsigned Tag;
  MDString *Name;
  Metadata *Type;
  Metadata *Value;

  MDNodeKeyImpl(unsigned Tag, MDString *Name, Metadata *Type, Metadata *Value)
      : Tag(Tag), Name(Name), Type(Type), Value(Value) {}
  MDNodeKeyImpl(const DITemplateValueParameter *N)
      : Tag(N->getTag()), Name(N->getRawName()), Type(N->getRawType()),
        Value(N->getValue()) {}

  bool isKeyOf(const DITemplateValueParameter *RHS) const {
    return Tag == RHS->getTag() && Name == RHS->getRawName() &&
           Type == RHS->getRawType() && Value == RHS->getValue();
  }
  unsigned getHashValue() const { return hash_combine(Tag, Name, Type, Value); }
};

template <> struct MDNodeKeyImpl<DIGlobalVariable> {
  Metadata *Scope;
  MDString *Name;
  MDString *LinkageName;
  Metadata *File;
  unsigned Line;
  Metadata *Type;
  bool IsLocalToUnit;
  bool IsDefinition;
  Metadata *Variable;
  Metadata *StaticDataMemberDeclaration;

  MDNodeKeyImpl(Metadata *Scope, MDString *Name, MDString *LinkageName,
                Metadata *File, unsigned Line, Metadata *Type,
                bool IsLocalToUnit, bool IsDefinition, Metadata *Variable,
                Metadata *StaticDataMemberDeclaration)
      : Scope(Scope), Name(Name), LinkageName(LinkageName), File(File),
        Line(Line), Type(Type), IsLocalToUnit(IsLocalToUnit),
        IsDefinition(IsDefinition), Variable(Variable),
        StaticDataMemberDeclaration(StaticDataMemberDeclaration) {}
  MDNodeKeyImpl(const DIGlobalVariable *N)
      : Scope(N->getRawScope()), Name(N->getRawName()),
        LinkageName(N->getRawLinkageName()), File(N->getRawFile()),
        Line(N->getLine()), Type(N->getRawType()),
        IsLocalToUnit(N->isLocalToUnit()), IsDefinition(N->isDefinition()),
        Variable(N->getRawVariable()),
        StaticDataMemberDeclaration(N->getRawStaticDataMemberDeclaration()) {}

  bool isKeyOf(const DIGlobalVariable *RHS) const {
    return Scope == RHS->getRawScope() && Name == RHS->getRawName() &&
           LinkageName == RHS->getRawLinkageName() &&
           File == RHS->getRawFile() && Line == RHS->getLine() &&
           Type == RHS->getRawType() && IsLocalToUnit == RHS->isLocalToUnit() &&
           IsDefinition == RHS->isDefinition() &&
           Variable == RHS->getRawVariable() &&
           StaticDataMemberDeclaration ==
               RHS->getRawStaticDataMemberDeclaration();
  }
  unsigned getHashValue() const {
    return hash_combine(Scope, Name, LinkageName, File, Line, Type,
                        IsLocalToUnit, IsDefinition, Variable,
                        StaticDataMemberDeclaration);
  }
};

template <> struct MDNodeKeyImpl<DILocalVariable> {
  Metadata *Scope;
  MDString *Name;
  Metadata *File;
  unsigned Line;
  Metadata *Type;
  unsigned Arg;
  unsigned Flags;

  MDNodeKeyImpl(Metadata *Scope, MDString *Name, Metadata *File, unsigned Line,
                Metadata *Type, unsigned Arg, unsigned Flags)
      : Scope(Scope), Name(Name), File(File), Line(Line), Type(Type), Arg(Arg),
        Flags(Flags) {}
  MDNodeKeyImpl(const DILocalVariable *N)
      : Scope(N->getRawScope()), Name(N->getRawName()), File(N->getRawFile()),
        Line(N->getLine()), Type(N->getRawType()), Arg(N->getArg()),
        Flags(N->getFlags()) {}

  bool isKeyOf(const DILocalVariable *RHS) const {
    return Scope == RHS->getRawScope() && Name == RHS->getRawName() &&
           File == RHS->getRawFile() && Line == RHS->getLine() &&
           Type == RHS->getRawType() && Arg == RHS->getArg() &&
           Flags == RHS->getFlags();
  }
  unsigned getHashValue() const {
    return hash_combine(Scope, Name, File, Line, Type, Arg, Flags);
  }
};

template <> struct MDNodeKeyImpl<DIExpression> {
  ArrayRef<uint64_t> Elements;

  MDNodeKeyImpl(ArrayRef<uint64_t> Elements) : Elements(Elements) {}
  MDNodeKeyImpl(const DIExpression *N) : Elements(N->getElements()) {}

  bool isKeyOf(const DIExpression *RHS) const {
    return Elements == RHS->getElements();
  }
  unsigned getHashValue() const {
    return hash_combine_range(Elements.begin(), Elements.end());
  }
};

template <> struct MDNodeKeyImpl<DIObjCProperty> {
  MDString *Name;
  Metadata *File;
  unsigned Line;
  MDString *GetterName;
  MDString *SetterName;
  unsigned Attributes;
  Metadata *Type;

  MDNodeKeyImpl(MDString *Name, Metadata *File, unsigned Line,
                MDString *GetterName, MDString *SetterName, unsigned Attributes,
                Metadata *Type)
      : Name(Name), File(File), Line(Line), GetterName(GetterName),
        SetterName(SetterName), Attributes(Attributes), Type(Type) {}
  MDNodeKeyImpl(const DIObjCProperty *N)
      : Name(N->getRawName()), File(N->getRawFile()), Line(N->getLine()),
        GetterName(N->getRawGetterName()), SetterName(N->getRawSetterName()),
        Attributes(N->getAttributes()), Type(N->getRawType()) {}

  bool isKeyOf(const DIObjCProperty *RHS) const {
    return Name == RHS->getRawName() && File == RHS->getRawFile() &&
           Line == RHS->getLine() && GetterName == RHS->getRawGetterName() &&
           SetterName == RHS->getRawSetterName() &&
           Attributes == RHS->getAttributes() && Type == RHS->getRawType();
  }
  unsigned getHashValue() const {
    return hash_combine(Name, File, Line, GetterName, SetterName, Attributes,
                        Type);
  }
};

template <> struct MDNodeKeyImpl<DIImportedEntity> {
  unsigned Tag;
  Metadata *Scope;
  Metadata *Entity;
  unsigned Line;
  MDString *Name;

  MDNodeKeyImpl(unsigned Tag, Metadata *Scope, Metadata *Entity, unsigned Line,
                MDString *Name)
      : Tag(Tag), Scope(Scope), Entity(Entity), Line(Line), Name(Name) {}
  MDNodeKeyImpl(const DIImportedEntity *N)
      : Tag(N->getTag()), Scope(N->getRawScope()), Entity(N->getRawEntity()),
        Line(N->getLine()), Name(N->getRawName()) {}

  bool isKeyOf(const DIImportedEntity *RHS) const {
    return Tag == RHS->getTag() && Scope == RHS->getRawScope() &&
           Entity == RHS->getRawEntity() && Line == RHS->getLine() &&
           Name == RHS->getRawName();
  }
  unsigned getHashValue() const {
    return hash_combine(Tag, Scope, Entity, Line, Name);
  }
};

template <> struct MDNodeKeyImpl<DIMacro> {
  unsigned MIType;
  unsigned Line;
  MDString *Name;
  MDString *Value;

  MDNodeKeyImpl(unsigned MIType, unsigned Line, MDString *Name, MDString *Value)
      : MIType(MIType), Line(Line), Name(Name), Value(Value) {}
  MDNodeKeyImpl(const DIMacro *N)
      : MIType(N->getMacinfoType()), Line(N->getLine()), Name(N->getRawName()),
        Value(N->getRawValue()) {}

  bool isKeyOf(const DIMacro *RHS) const {
    return MIType == RHS->getMacinfoType() && Line == RHS->getLine() &&
           Name == RHS->getRawName() && Value == RHS->getRawValue();
  }
  unsigned getHashValue() const {
    return hash_combine(MIType, Line, Name, Value);
  }
};

template <> struct MDNodeKeyImpl<DIMacroFile> {
  unsigned MIType;
  unsigned Line;
  Metadata *File;
  Metadata *Elements;

  MDNodeKeyImpl(unsigned MIType, unsigned Line, Metadata *File,
                Metadata *Elements)
      : MIType(MIType), Line(Line), File(File), Elements(Elements) {}
  MDNodeKeyImpl(const DIMacroFile *N)
      : MIType(N->getMacinfoType()), Line(N->getLine()), File(N->getRawFile()),
        Elements(N->getRawElements()) {}

  bool isKeyOf(const DIMacroFile *RHS) const {
    return MIType == RHS->getMacinfoType() && Line == RHS->getLine() &&
           File == RHS->getRawFile() && File == RHS->getRawElements();
  }
  unsigned getHashValue() const {
    return hash_combine(MIType, Line, File, Elements);
  }
};

/// \brief DenseMapInfo for MDNode subclasses.
template <class NodeTy> struct MDNodeInfo {
  typedef MDNodeKeyImpl<NodeTy> KeyTy;
  typedef MDNodeSubsetEqualImpl<NodeTy> SubsetEqualTy;
  static inline NodeTy *getEmptyKey() {
    return DenseMapInfo<NodeTy *>::getEmptyKey();
  }
  static inline NodeTy *getTombstoneKey() {
    return DenseMapInfo<NodeTy *>::getTombstoneKey();
  }
  static unsigned getHashValue(const KeyTy &Key) { return Key.getHashValue(); }
  static unsigned getHashValue(const NodeTy *N) {
    return KeyTy(N).getHashValue();
  }
  static bool isEqual(const KeyTy &LHS, const NodeTy *RHS) {
    if (RHS == getEmptyKey() || RHS == getTombstoneKey())
      return false;
    return SubsetEqualTy::isSubsetEqual(LHS, RHS) || LHS.isKeyOf(RHS);
  }
  static bool isEqual(const NodeTy *LHS, const NodeTy *RHS) {
    if (LHS == RHS)
      return true;
    if (RHS == getEmptyKey() || RHS == getTombstoneKey())
      return false;
    return SubsetEqualTy::isSubsetEqual(LHS, RHS);
  }
};

#define HANDLE_MDNODE_LEAF(CLASS) typedef MDNodeInfo<CLASS> CLASS##Info;
#include "llvm/IR/Metadata.def"

/// \brief Map-like storage for metadata attachments.
class MDAttachmentMap {
  SmallVector<std::pair<unsigned, TrackingMDNodeRef>, 2> Attachments;

public:
  bool empty() const { return Attachments.empty(); }
  size_t size() const { return Attachments.size(); }

  /// \brief Get a particular attachment (if any).
  MDNode *lookup(unsigned ID) const;

  /// \brief Set an attachment to a particular node.
  ///
  /// Set the \c ID attachment to \c MD, replacing the current attachment at \c
  /// ID (if anyway).
  void set(unsigned ID, MDNode &MD);

  /// \brief Remove an attachment.
  ///
  /// Remove the attachment at \c ID, if any.
  void erase(unsigned ID);

  /// \brief Copy out all the attachments.
  ///
  /// Copies all the current attachments into \c Result, sorting by attachment
  /// ID.  This function does \em not clear \c Result.
  void getAll(SmallVectorImpl<std::pair<unsigned, MDNode *>> &Result) const;

  /// \brief Erase matching attachments.
  ///
  /// Erases all attachments matching the \c shouldRemove predicate.
  template <class PredTy> void remove_if(PredTy shouldRemove) {
    Attachments.erase(
        std::remove_if(Attachments.begin(), Attachments.end(), shouldRemove),
        Attachments.end());
  }
};

/// Multimap-like storage for metadata attachments for globals. This differs
/// from MDAttachmentMap in that it allows multiple attachments per metadata
/// kind.
class MDGlobalAttachmentMap {
  struct Attachment {
    unsigned MDKind;
    TrackingMDNodeRef Node;
  };
  SmallVector<Attachment, 1> Attachments;

public:
  bool empty() const { return Attachments.empty(); }

  /// Appends all attachments with the given ID to \c Result in insertion order.
  /// If the global has no attachments with the given ID, or if ID is invalid,
  /// leaves Result unchanged.
  void get(unsigned ID, SmallVectorImpl<MDNode *> &Result);

  void insert(unsigned ID, MDNode &MD);
  void erase(unsigned ID);

  /// Appends all attachments for the global to \c Result, sorting by attachment
  /// ID. Attachments with the same ID appear in insertion order. This function
  /// does \em not clear \c Result.
  void getAll(SmallVectorImpl<std::pair<unsigned, MDNode *>> &Result) const;
};

class LLVMContextImpl {
public:
  /// OwnedModules - The set of modules instantiated in this context, and which
  /// will be automatically deleted if this context is deleted.
  SmallPtrSet<Module*, 4> OwnedModules;
  
  LLVMContext::InlineAsmDiagHandlerTy InlineAsmDiagHandler;
  void *InlineAsmDiagContext;

  LLVMContext::DiagnosticHandlerTy DiagnosticHandler;
  void *DiagnosticContext;
  bool RespectDiagnosticFilters;

  LLVMContext::YieldCallbackTy YieldCallback;
  void *YieldOpaqueHandle;

  typedef DenseMap<APInt, ConstantInt *, DenseMapAPIntKeyInfo> IntMapTy;
  IntMapTy IntConstants;

  typedef DenseMap<APFloat, ConstantFP *, DenseMapAPFloatKeyInfo> FPMapTy;
  FPMapTy FPConstants;

  FoldingSet<AttributeImpl> AttrsSet;
  FoldingSet<AttributeSetImpl> AttrsLists;
  FoldingSet<AttributeSetNode> AttrsSetNodes;

  StringMap<MDString, BumpPtrAllocator> MDStringCache;
  DenseMap<Value *, ValueAsMetadata *> ValuesAsMetadata;
  DenseMap<Metadata *, MetadataAsValue *> MetadataAsValues;

  DenseMap<const Value*, ValueName*> ValueNames;

#define HANDLE_MDNODE_LEAF_UNIQUABLE(CLASS)                                    \
  DenseSet<CLASS *, CLASS##Info> CLASS##s;
#include "llvm/IR/Metadata.def"

  // Optional map for looking up composite types by identifier.
  Optional<DenseMap<const MDString *, DICompositeType *>> DITypeMap;

  // MDNodes may be uniqued or not uniqued.  When they're not uniqued, they
  // aren't in the MDNodeSet, but they're still shared between objects, so no
  // one object can destroy them.  Keep track of them here so we can delete
  // them on context teardown.
  std::vector<MDNode *> DistinctMDNodes;

  DenseMap<Type*, ConstantAggregateZero*> CAZConstants;

  typedef ConstantUniqueMap<ConstantArray> ArrayConstantsTy;
  ArrayConstantsTy ArrayConstants;
  
  typedef ConstantUniqueMap<ConstantStruct> StructConstantsTy;
  StructConstantsTy StructConstants;
  
  typedef ConstantUniqueMap<ConstantVector> VectorConstantsTy;
  VectorConstantsTy VectorConstants;
  
  DenseMap<PointerType*, ConstantPointerNull*> CPNConstants;

  DenseMap<Type*, UndefValue*> UVConstants;
  
  StringMap<ConstantDataSequential*> CDSConstants;

  DenseMap<std::pair<const Function *, const BasicBlock *>, BlockAddress *>
    BlockAddresses;
  ConstantUniqueMap<ConstantExpr> ExprConstants;

  ConstantUniqueMap<InlineAsm> InlineAsms;

  ConstantInt *TheTrueVal;
  ConstantInt *TheFalseVal;

  std::unique_ptr<ConstantTokenNone> TheNoneToken;

  // Basic type instances.
  Type VoidTy, LabelTy, HalfTy, FloatTy, DoubleTy, MetadataTy, TokenTy;
  Type X86_FP80Ty, FP128Ty, PPC_FP128Ty, X86_MMXTy;
  IntegerType Int1Ty, Int8Ty, Int16Ty, Int32Ty, Int64Ty, Int128Ty;

  
  /// TypeAllocator - All dynamically allocated types are allocated from this.
  /// They live forever until the context is torn down.
  BumpPtrAllocator TypeAllocator;
  
  DenseMap<unsigned, IntegerType*> IntegerTypes;

  typedef DenseSet<FunctionType *, FunctionTypeKeyInfo> FunctionTypeSet;
  FunctionTypeSet FunctionTypes;
  typedef DenseSet<StructType *, AnonStructTypeKeyInfo> StructTypeSet;
  StructTypeSet AnonStructTypes;
  StringMap<StructType*> NamedStructTypes;
  unsigned NamedStructTypesUniqueID;
    
  DenseMap<std::pair<Type *, uint64_t>, ArrayType*> ArrayTypes;
  DenseMap<std::pair<Type *, unsigned>, VectorType*> VectorTypes;
  DenseMap<Type*, PointerType*> PointerTypes;  // Pointers in AddrSpace = 0
  DenseMap<std::pair<Type*, unsigned>, PointerType*> ASPointerTypes;


  /// ValueHandles - This map keeps track of all of the value handles that are
  /// watching a Value*.  The Value::HasValueHandle bit is used to know
  /// whether or not a value has an entry in this map.
  typedef DenseMap<Value*, ValueHandleBase*> ValueHandlesTy;
  ValueHandlesTy ValueHandles;
  
  /// CustomMDKindNames - Map to hold the metadata string to ID mapping.
  StringMap<unsigned> CustomMDKindNames;

  /// Collection of per-instruction metadata used in this context.
  DenseMap<const Instruction *, MDAttachmentMap> InstructionMetadata;

  /// Collection of per-GlobalObject metadata used in this context.
  DenseMap<const GlobalObject *, MDGlobalAttachmentMap> GlobalObjectMetadata;

  /// DiscriminatorTable - This table maps file:line locations to an
  /// integer representing the next DWARF path discriminator to assign to
  /// instructions in different blocks at the same location.
  DenseMap<std::pair<const char *, unsigned>, unsigned> DiscriminatorTable;

  int getOrAddScopeRecordIdxEntry(MDNode *N, int ExistingIdx);
  int getOrAddScopeInlinedAtIdxEntry(MDNode *Scope, MDNode *IA,int ExistingIdx);

  /// \brief A set of interned tags for operand bundles.  The StringMap maps
  /// bundle tags to their IDs.
  ///
  /// \see LLVMContext::getOperandBundleTagID
  StringMap<uint32_t> BundleTagCache;

  StringMapEntry<uint32_t> *getOrInsertBundleTag(StringRef Tag);
  void getOperandBundleTags(SmallVectorImpl<StringRef> &Tags) const;
  uint32_t getOperandBundleTagID(StringRef Tag) const;

  /// Maintain the GC name for each function.
  ///
  /// This saves allocating an additional word in Function for programs which
  /// do not use GC (i.e., most programs) at the cost of increased overhead for
  /// clients which do use GC.
  DenseMap<const Function*, std::string> GCNames;

  /// Flag to indicate if Value (other than GlobalValue) retains their name or
  /// not.
  bool DiscardValueNames = false;

  LLVMContextImpl(LLVMContext &C);
  ~LLVMContextImpl();

  /// Destroy the ConstantArrays if they are not used.
  void dropTriviallyDeadConstantArrays();

  /// \brief Access the object which manages optimization bisection for failure
  /// analysis.
  OptBisect &getOptBisect();
};

}

#endif