//===-- llvm/GlobalObject.h - Class to represent global objects -*- C++ -*-===//

//

//                     The LLVM Compiler Infrastructure

//

// This file is distributed under the University of Illinois Open Source

// License. See LICENSE.TXT for details.

//

//===----------------------------------------------------------------------===//

//

// This represents an independent object. That is, a function or a global

// variable, but not an alias.

//

//===----------------------------------------------------------------------===//

#ifndef LLVM_IR_GLOBALOBJECT_H

#define LLVM_IR_GLOBALOBJECT_H

#include "llvh/ADT/StringRef.h"

#include "llvh/IR/GlobalValue.h"

#include "llvh/IR/Value.h"

#include <string>

#include <utility>

namespace llvh {

class Comdat;

class MDNode;

class Metadata;

class GlobalObject : public GlobalValue {

protected:

  GlobalObject(Type *Ty, ValueTy VTy, Use *Ops, unsigned NumOps,

               LinkageTypes Linkage, const Twine &Name,

               unsigned AddressSpace = 0)

      : GlobalValue(Ty, VTy, Ops, NumOps, Linkage, Name, AddressSpace),

        ObjComdat(nullptr) {

    setGlobalValueSubClassData(0);

  }

  Comdat *ObjComdat;

  enum {

    LastAlignmentBit = 4,

    HasMetadataHashEntryBit,

    HasSectionHashEntryBit,

    GlobalObjectBits,

  };

  static const unsigned GlobalObjectSubClassDataBits =

      GlobalValueSubClassDataBits - GlobalObjectBits;

private:

  static const unsigned AlignmentBits = LastAlignmentBit + 1;

  static const unsigned AlignmentMask = (1 << AlignmentBits) - 1;

  static const unsigned GlobalObjectMask = (1 << GlobalObjectBits) - 1;

public:

  GlobalObject(const GlobalObject &) = delete;

  unsigned getAlignment() const {

    unsigned Data = getGlobalValueSubClassData();

    unsigned AlignmentData = Data & AlignmentMask;

    return (1u << AlignmentData) >> 1;

  }

  void setAlignment(unsigned Align);

  unsigned getGlobalObjectSubClassData() const {

    unsigned ValueData = getGlobalValueSubClassData();

    return ValueData >> GlobalObjectBits;

  }

  void setGlobalObjectSubClassData(unsigned Val) {

    unsigned OldData = getGlobalValueSubClassData();

    setGlobalValueSubClassData((OldData & GlobalObjectMask) |

                               (Val << GlobalObjectBits));

    assert(getGlobalObjectSubClassData() == Val && "representation error");

  }

  /// Check if this global has a custom object file section.

  ///

  /// This is more efficient than calling getSection() and checking for an empty

  /// string.

  bool hasSection() const {

    return getGlobalValueSubClassData() & (1 << HasSectionHashEntryBit);

  }

  /// Get the custom section of this global if it has one.

  ///

  /// If this global does not have a custom section, this will be empty and the

  /// default object file section (.text, .data, etc) will be used.

  StringRef getSection() const {

    return hasSection() ? getSectionImpl() : StringRef();

  }

  /// Change the section for this global.

  ///

  /// Setting the section to the empty string tells LLVM to choose an

  /// appropriate default object file section.

  void setSection(StringRef S);

  bool hasComdat() const { return getComdat() != nullptr; }

  const Comdat *getComdat() const { return ObjComdat; }

  Comdat *getComdat() { return ObjComdat; }

  void setComdat(Comdat *C) { ObjComdat = C; }

  /// Check if this has any metadata.

  bool hasMetadata() const { return hasMetadataHashEntry(); }

  /// Check if this has any metadata of the given kind.

  bool hasMetadata(unsigned KindID) const {

    return getMetadata(KindID) != nullptr;

  }

  bool hasMetadata(StringRef Kind) const {

    return getMetadata(Kind) != nullptr;

  }

  /// Get the current metadata attachments for the given kind, if any.

  ///

  /// These functions require that the function have at most a single attachment

  /// of the given kind, and return \c nullptr if such an attachment is missing.

  /// @{

  MDNode *getMetadata(unsigned KindID) const;

  MDNode *getMetadata(StringRef Kind) const;

  /// @}

  /// Appends all attachments with the given ID to \c MDs in insertion order.

  /// If the global has no attachments with the given ID, or if ID is invalid,

  /// leaves MDs unchanged.

  /// @{

  void getMetadata(unsigned KindID, SmallVectorImpl<MDNode *> &MDs) const;

  void getMetadata(StringRef Kind, SmallVectorImpl<MDNode *> &MDs) const;

  /// @}

  /// Set a particular kind of metadata attachment.

  ///

  /// Sets the given attachment to \c MD, erasing it if \c MD is \c nullptr or

  /// replacing it if it already exists.

  /// @{

  void setMetadata(unsigned KindID, MDNode *MD);

  void setMetadata(StringRef Kind, MDNode *MD);

  /// @}

  /// Add a metadata attachment.

  /// @{

  void addMetadata(unsigned KindID, MDNode &MD);

  void addMetadata(StringRef Kind, MDNode &MD);

  /// @}

  /// Appends all attachments for the global to \c MDs, sorting by attachment

  /// ID. Attachments with the same ID appear in insertion order.

  void

  getAllMetadata(SmallVectorImpl<std::pair<unsigned, MDNode *>> &MDs) const;

  /// Erase all metadata attachments with the given kind.

  ///

  /// \returns true if any metadata was removed.

  bool eraseMetadata(unsigned KindID);

  /// Copy metadata from Src, adjusting offsets by Offset.

  void copyMetadata(const GlobalObject *Src, unsigned Offset);

  void addTypeMetadata(unsigned Offset, Metadata *TypeID);

protected:

  void copyAttributesFrom(const GlobalObject *Src);

public:

  // Methods for support type inquiry through isa, cast, and dyn_cast:

  static bool classof(const Value *V) {

    return V->getValueID() == Value::FunctionVal ||

           V->getValueID() == Value::GlobalVariableVal;

  }

  void clearMetadata();

private:

  void setGlobalObjectFlag(unsigned Bit, bool Val) {

    unsigned Mask = 1 << Bit;

    setGlobalValueSubClassData((~Mask & getGlobalValueSubClassData()) |

                               (Val ? Mask : 0u));

  }

  bool hasMetadataHashEntry() const {

    return getGlobalValueSubClassData() & (1 << HasMetadataHashEntryBit);

  }

  void setHasMetadataHashEntry(bool HasEntry) {

    setGlobalObjectFlag(HasMetadataHashEntryBit, HasEntry);

  }

  StringRef getSectionImpl() const;

};

} // end namespace llvh

#endif // LLVM_IR_GLOBALOBJECT_H