//===- llvm/IR/TrackingMDRef.h - Tracking Metadata references ---*- C++ -*-===//

//

//                     The LLVM Compiler Infrastructure

//

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

// License. See LICENSE.TXT for details.

//

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

//

// References to metadata that track RAUW.

//

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

#ifndef LLVM_IR_TRACKINGMDREF_H

#define LLVM_IR_TRACKINGMDREF_H

#include "llvh/IR/Metadata.h"

#include <algorithm>

#include <cassert>

namespace llvh {

/// Tracking metadata reference.

///

/// This class behaves like \a TrackingVH, but for metadata.

class TrackingMDRef {

  Metadata *MD = nullptr;

public:

  TrackingMDRef() = default;

  explicit TrackingMDRef(Metadata *MD) : MD(MD) { track(); }

  TrackingMDRef(TrackingMDRef &&X) : MD(X.MD) { retrack(X); }

  TrackingMDRef(const TrackingMDRef &X) : MD(X.MD) { track(); }

  TrackingMDRef &operator=(TrackingMDRef &&X) {

    if (&X == this)

      return *this;

    untrack();

    MD = X.MD;

    retrack(X);

    return *this;

  }

  TrackingMDRef &operator=(const TrackingMDRef &X) {

    if (&X == this)

      return *this;

    untrack();

    MD = X.MD;

    track();

    return *this;

  }

  ~TrackingMDRef() { untrack(); }

  Metadata *get() const { return MD; }

  operator Metadata *() const { return get(); }

  Metadata *operator->() const { return get(); }

  Metadata &operator*() const { return *get(); }

  void reset() {

    untrack();

    MD = nullptr;

  }

  void reset(Metadata *MD) {

    untrack();

    this->MD = MD;

    track();

  }

  /// Check whether this has a trivial destructor.

  ///

  /// If \c MD isn't replaceable, the destructor will be a no-op.

  bool hasTrivialDestructor() const {

    return !MD || !MetadataTracking::isReplaceable(*MD);

  }

  bool operator==(const TrackingMDRef &X) const { return MD == X.MD; }

  bool operator!=(const TrackingMDRef &X) const { return MD != X.MD; }

private:

  void track() {

    if (MD)

      MetadataTracking::track(MD);

  }

  void untrack() {

    if (MD)

      MetadataTracking::untrack(MD);

  }

  void retrack(TrackingMDRef &X) {

    assert(MD == X.MD && "Expected values to match");

    if (X.MD) {

      MetadataTracking::retrack(X.MD, MD);

      X.MD = nullptr;

    }

  }

};

/// Typed tracking ref.

///

/// Track refererences of a particular type.  It's useful to use this for \a

/// MDNode and \a ValueAsMetadata.

template <class T> class TypedTrackingMDRef {

  TrackingMDRef Ref;

public:

  TypedTrackingMDRef() = default;

  explicit TypedTrackingMDRef(T *MD) : Ref(static_cast<Metadata *>(MD)) {}

  TypedTrackingMDRef(TypedTrackingMDRef &&X) : Ref(std::move(X.Ref)) {}

  TypedTrackingMDRef(const TypedTrackingMDRef &X) : Ref(X.Ref) {}

  TypedTrackingMDRef &operator=(TypedTrackingMDRef &&X) {

    Ref = std::move(X.Ref);

    return *this;

  }

  TypedTrackingMDRef &operator=(const TypedTrackingMDRef &X) {

    Ref = X.Ref;

    return *this;

  }

  T *get() const { return (T *)Ref.get(); }

  operator T *() const { return get(); }

  T *operator->() const { return get(); }

  T &operator*() const { return *get(); }

  bool operator==(const TypedTrackingMDRef &X) const { return Ref == X.Ref; }

  bool operator!=(const TypedTrackingMDRef &X) const { return Ref != X.Ref; }

  void reset() { Ref.reset(); }

  void reset(T *MD) { Ref.reset(static_cast<Metadata *>(MD)); }

  /// Check whether this has a trivial destructor.

  bool hasTrivialDestructor() const { return Ref.hasTrivialDestructor(); }

};

using TrackingMDNodeRef = TypedTrackingMDRef<MDNode>;

using TrackingValueAsMetadataRef = TypedTrackingMDRef<ValueAsMetadata>;

// Expose the underlying metadata to casting.

template <> struct simplify_type<TrackingMDRef> {

  using SimpleType = Metadata *;

  static SimpleType getSimplifiedValue(TrackingMDRef &MD) { return MD.get(); }

};

template <> struct simplify_type<const TrackingMDRef> {

  using SimpleType = Metadata *;

  static SimpleType getSimplifiedValue(const TrackingMDRef &MD) {

    return MD.get();

  }

};

template <class T> struct simplify_type<TypedTrackingMDRef<T>> {

  using SimpleType = T *;

  static SimpleType getSimplifiedValue(TypedTrackingMDRef<T> &MD) {

    return MD.get();

  }

};

template <class T> struct simplify_type<const TypedTrackingMDRef<T>> {

  using SimpleType = T *;

  static SimpleType getSimplifiedValue(const TypedTrackingMDRef<T> &MD) {

    return MD.get();

  }

};

} // end namespace llvh

#endif // LLVM_IR_TRACKINGMDREF_H