object.h

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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
#ifndef TVM_RUNTIME_OBJECT_H_
#define TVM_RUNTIME_OBJECT_H_

#include <tvm/runtime/c_runtime_api.h>
#include <tvm/runtime/logging.h>

#include <string>
#include <type_traits>
#include <utility>

#ifndef TVM_OBJECT_ATOMIC_REF_COUNTER
#define TVM_OBJECT_ATOMIC_REF_COUNTER 1
#endif

#if TVM_OBJECT_ATOMIC_REF_COUNTER
#include <atomic>
#endif  // TVM_OBJECT_ATOMIC_REF_COUNTER

namespace tvm {
namespace runtime {

struct TypeIndex {
  enum {
    kRoot = 0,
    // Standard static index assignments,
    // Frontends can take benefit of these constants.
    kRuntimeModule = 1,
    kRuntimeNDArray = 2,
    kRuntimeString = 3,
    kRuntimeArray = 4,
    kRuntimeMap = 5,
    kRuntimeShapeTuple = 6,
    kRuntimePackedFunc = 7,
    // static assignments that may subject to change.
    kRuntimeClosure,
    kRuntimeADT,
    kStaticIndexEnd,
    kDynamic = kStaticIndexEnd
  };
};  // namespace TypeIndex

class TVM_DLL Object {
 public:
  typedef void (*FDeleter)(Object* self);
  uint32_t type_index() const { return type_index_; }
  std::string GetTypeKey() const { return TypeIndex2Key(type_index_); }
  size_t GetTypeKeyHash() const { return TypeIndex2KeyHash(type_index_); }
  template <typename TargetType>
  inline bool IsInstance() const;
  inline bool unique() const;
  static std::string TypeIndex2Key(uint32_t tindex);
  static size_t TypeIndex2KeyHash(uint32_t tindex);
  static uint32_t TypeKey2Index(const std::string& key);

#if TVM_OBJECT_ATOMIC_REF_COUNTER
  using RefCounterType = std::atomic<int32_t>;
#else
  using RefCounterType = int32_t;
#endif

  static constexpr const char* _type_key = "runtime.Object";

  static uint32_t _GetOrAllocRuntimeTypeIndex() { return TypeIndex::kRoot; }
  static uint32_t RuntimeTypeIndex() { return TypeIndex::kRoot; }

  // Default object type properties for sub-classes
  static constexpr bool _type_final = false;
  static constexpr uint32_t _type_child_slots = 0;
  static constexpr bool _type_child_slots_can_overflow = true;
  // member information
  static constexpr bool _type_has_method_visit_attrs = true;
  static constexpr bool _type_has_method_sequal_reduce = false;
  static constexpr bool _type_has_method_shash_reduce = false;
  // NOTE: the following field is not type index of Object
  // but was intended to be used by sub-classes as default value.
  // The type index of Object is TypeIndex::kRoot
  static constexpr uint32_t _type_index = TypeIndex::kDynamic;

  // Default constructor and copy constructor
  Object() {}
  // Override the copy and assign constructors to do nothing.
  // This is to make sure only contents, but not deleter and ref_counter
  // are copied when a child class copies itself.
  // This will enable us to use make_object<ObjectClass>(*obj_ptr)
  // to copy an existing object.
  Object(const Object& other) {  // NOLINT(*)
  }
  Object(Object&& other) {  // NOLINT(*)
  }
  Object& operator=(const Object& other) {  // NOLINT(*)
    return *this;
  }
  Object& operator=(Object&& other) {  // NOLINT(*)
    return *this;
  }

 protected:
  // The fields of the base object cell.
  uint32_t type_index_{0};
  RefCounterType ref_counter_{0};
  FDeleter deleter_ = nullptr;
  // Invariant checks.
  static_assert(sizeof(int32_t) == sizeof(RefCounterType) &&
                    alignof(int32_t) == sizeof(RefCounterType),
                "RefCounter ABI check.");

  static uint32_t GetOrAllocRuntimeTypeIndex(const std::string& key, uint32_t static_tindex,
                                             uint32_t parent_tindex, uint32_t type_child_slots,
                                             bool type_child_slots_can_overflow);

  // reference counter related operations
  inline void IncRef();
  inline void DecRef();

 private:
  inline int use_count() const;
  bool DerivedFrom(uint32_t parent_tindex) const;
  // friend classes
  template <typename>
  friend class ObjAllocatorBase;
  template <typename>
  friend class ObjectPtr;
  friend class TVMRetValue;
  friend class ObjectInternal;
};

template <typename RelayRefType, typename ObjectType>
inline RelayRefType GetRef(const ObjectType* ptr);

template <typename SubRef, typename BaseRef>
inline SubRef Downcast(BaseRef ref);

template <typename T>
class ObjectPtr {
 public:
  ObjectPtr() {}
  ObjectPtr(std::nullptr_t) {}  // NOLINT(*)
  ObjectPtr(const ObjectPtr<T>& other)  // NOLINT(*)
      : ObjectPtr(other.data_) {}
  template <typename U>
  ObjectPtr(const ObjectPtr<U>& other)  // NOLINT(*)
      : ObjectPtr(other.data_) {
    static_assert(std::is_base_of<T, U>::value,
                  "can only assign of child class ObjectPtr to parent");
  }
  ObjectPtr(ObjectPtr<T>&& other)  // NOLINT(*)
      : data_(other.data_) {
    other.data_ = nullptr;
  }
  template <typename Y>
  ObjectPtr(ObjectPtr<Y>&& other)  // NOLINT(*)
      : data_(other.data_) {
    static_assert(std::is_base_of<T, Y>::value,
                  "can only assign of child class ObjectPtr to parent");
    other.data_ = nullptr;
  }
  ~ObjectPtr() { this->reset(); }
  void swap(ObjectPtr<T>& other) {  // NOLINT(*)
    std::swap(data_, other.data_);
  }
  T* get() const { return static_cast<T*>(data_); }
  T* operator->() const { return get(); }
  T& operator*() const {  // NOLINT(*)
    return *get();
  }
  ObjectPtr<T>& operator=(const ObjectPtr<T>& other) {  // NOLINT(*)
    // takes in plane operator to enable copy elison.
    // copy-and-swap idiom
    ObjectPtr(other).swap(*this);  // NOLINT(*)
    return *this;
  }
  ObjectPtr<T>& operator=(ObjectPtr<T>&& other) {  // NOLINT(*)
    // copy-and-swap idiom
    ObjectPtr(std::move(other)).swap(*this);  // NOLINT(*)
    return *this;
  }
  explicit operator bool() const { return get() != nullptr; }
  void reset() {
    if (data_ != nullptr) {
      data_->DecRef();
      data_ = nullptr;
    }
  }
  int use_count() const { return data_ != nullptr ? data_->use_count() : 0; }
  bool unique() const { return data_ != nullptr && data_->use_count() == 1; }
  bool operator==(const ObjectPtr<T>& other) const { return data_ == other.data_; }
  bool operator!=(const ObjectPtr<T>& other) const { return data_ != other.data_; }
  bool operator==(std::nullptr_t null) const { return data_ == nullptr; }
  bool operator!=(std::nullptr_t null) const { return data_ != nullptr; }

 private:
  Object* data_{nullptr};
  explicit ObjectPtr(Object* data) : data_(data) {
    if (data != nullptr) {
      data_->IncRef();
    }
  }
  static ObjectPtr<T> MoveFromRValueRefArg(Object** ref) {
    ObjectPtr<T> ptr;
    ptr.data_ = *ref;
    *ref = nullptr;
    return ptr;
  }
  // friend classes
  friend class Object;
  friend class ObjectRef;
  friend struct ObjectPtrHash;
  template <typename>
  friend class ObjectPtr;
  template <typename>
  friend class ObjAllocatorBase;
  friend class TVMPODValue_;
  friend class TVMArgsSetter;
  friend class TVMRetValue;
  friend class TVMArgValue;
  friend class TVMMovableArgValue_;
  template <typename RelayRefType, typename ObjType>
  friend RelayRefType GetRef(const ObjType* ptr);
  template <typename BaseType, typename ObjType>
  friend ObjectPtr<BaseType> GetObjectPtr(ObjType* ptr);
};

class ObjectRef {
 public:
  ObjectRef() = default;
  explicit ObjectRef(ObjectPtr<Object> data) : data_(data) {}
  bool same_as(const ObjectRef& other) const { return data_ == other.data_; }
  bool operator==(const ObjectRef& other) const { return data_ == other.data_; }
  bool operator!=(const ObjectRef& other) const { return data_ != other.data_; }
  bool operator<(const ObjectRef& other) const { return data_.get() < other.data_.get(); }
  bool defined() const { return data_ != nullptr; }
  const Object* get() const { return data_.get(); }
  const Object* operator->() const { return get(); }
  bool unique() const { return data_.unique(); }
  int use_count() const { return data_.use_count(); }
  template <typename ObjectType>
  inline const ObjectType* as() const;

  using ContainerType = Object;
  // Default type properties for the reference class.
  static constexpr bool _type_is_nullable = true;

 protected:
  ObjectPtr<Object> data_;
  Object* get_mutable() const { return data_.get(); }
  template <typename T>
  static T DowncastNoCheck(ObjectRef ref) {
    return T(std::move(ref.data_));
  }
  static void FFIClearAfterMove(ObjectRef* ref) { ref->data_.data_ = nullptr; }
  template <typename ObjectType>
  static ObjectPtr<ObjectType> GetDataPtr(const ObjectRef& ref) {
    return ObjectPtr<ObjectType>(ref.data_.data_);
  }
  // friend classes.
  friend struct ObjectPtrHash;
  friend class TVMRetValue;
  friend class TVMArgsSetter;
  friend class ObjectInternal;
  template <typename SubRef, typename BaseRef>
  friend SubRef Downcast(BaseRef ref);
};

template <typename BaseType, typename ObjectType>
inline ObjectPtr<BaseType> GetObjectPtr(ObjectType* ptr);

struct ObjectPtrHash {
  size_t operator()(const ObjectRef& a) const { return operator()(a.data_); }

  template <typename T>
  size_t operator()(const ObjectPtr<T>& a) const {
    return std::hash<Object*>()(a.get());
  }
};

struct ObjectPtrEqual {
  bool operator()(const ObjectRef& a, const ObjectRef& b) const { return a.same_as(b); }

  template <typename T>
  size_t operator()(const ObjectPtr<T>& a, const ObjectPtr<T>& b) const {
    return a == b;
  }
};

#define TVM_DECLARE_BASE_OBJECT_INFO(TypeName, ParentType)                                     \
  static_assert(!ParentType::_type_final, "ParentObj marked as final");                        \
  static uint32_t RuntimeTypeIndex() {                                                         \
    static_assert(TypeName::_type_child_slots == 0 || ParentType::_type_child_slots == 0 ||    \
                      TypeName::_type_child_slots < ParentType::_type_child_slots,             \
                  "Need to set _type_child_slots when parent specifies it.");                  \
    if (TypeName::_type_index != ::tvm::runtime::TypeIndex::kDynamic) {                        \
      return TypeName::_type_index;                                                            \
    }                                                                                          \
    return _GetOrAllocRuntimeTypeIndex();                                                      \
  }                                                                                            \
  static uint32_t _GetOrAllocRuntimeTypeIndex() {                                              \
    static uint32_t tindex = Object::GetOrAllocRuntimeTypeIndex(                               \
        TypeName::_type_key, TypeName::_type_index, ParentType::_GetOrAllocRuntimeTypeIndex(), \
        TypeName::_type_child_slots, TypeName::_type_child_slots_can_overflow);                \
    return tindex;                                                                             \
  }

#define TVM_DECLARE_FINAL_OBJECT_INFO(TypeName, ParentType) \
  static const constexpr bool _type_final = true;           \
  static const constexpr int _type_child_slots = 0;         \
  TVM_DECLARE_BASE_OBJECT_INFO(TypeName, ParentType)

#if defined(__GNUC__)
#define TVM_ATTRIBUTE_UNUSED __attribute__((unused))
#else
#define TVM_ATTRIBUTE_UNUSED
#endif

#define TVM_STR_CONCAT_(__x, __y) __x##__y
#define TVM_STR_CONCAT(__x, __y) TVM_STR_CONCAT_(__x, __y)

#define TVM_OBJECT_REG_VAR_DEF static TVM_ATTRIBUTE_UNUSED uint32_t __make_Object_tid

#define TVM_REGISTER_OBJECT_TYPE(TypeName) \
  TVM_STR_CONCAT(TVM_OBJECT_REG_VAR_DEF, __COUNTER__) = TypeName::_GetOrAllocRuntimeTypeIndex()

/*
 * \brief Define the default copy/move constructor and assign operator
 * \param TypeName The class typename.
 */
#define TVM_DEFINE_DEFAULT_COPY_MOVE_AND_ASSIGN(TypeName) \
  TypeName(const TypeName& other) = default;              \
  TypeName(TypeName&& other) = default;                   \
  TypeName& operator=(const TypeName& other) = default;   \
  TypeName& operator=(TypeName&& other) = default;

/*
 * \brief Define object reference methods.
 * \param TypeName The object type name
 * \param ParentType The parent type of the objectref
 * \param ObjectName The type name of the object.
 */
#define TVM_DEFINE_OBJECT_REF_METHODS(TypeName, ParentType, ObjectName)                        \
  TypeName() = default;                                                                        \
  explicit TypeName(::tvm::runtime::ObjectPtr<::tvm::runtime::Object> n) : ParentType(n) {}    \
  TVM_DEFINE_DEFAULT_COPY_MOVE_AND_ASSIGN(TypeName);                                           \
  const ObjectName* operator->() const { return static_cast<const ObjectName*>(data_.get()); } \
  const ObjectName* get() const { return operator->(); }                                       \
  using ContainerType = ObjectName;

/*
 * \brief Define object reference methods that is not nullable.
 *
 * \param TypeName The object type name
 * \param ParentType The parent type of the objectref
 * \param ObjectName The type name of the object.
 */
#define TVM_DEFINE_NOTNULLABLE_OBJECT_REF_METHODS(TypeName, ParentType, ObjectName)            \
  explicit TypeName(::tvm::runtime::ObjectPtr<::tvm::runtime::Object> n) : ParentType(n) {}    \
  TVM_DEFINE_DEFAULT_COPY_MOVE_AND_ASSIGN(TypeName);                                           \
  const ObjectName* operator->() const { return static_cast<const ObjectName*>(data_.get()); } \
  const ObjectName* get() const { return operator->(); }                                       \
  static constexpr bool _type_is_nullable = false;                                             \
  using ContainerType = ObjectName;

/*
 * \brief Define object reference methods of whose content is mutable.
 * \param TypeName The object type name
 * \param ParentType The parent type of the objectref
 * \param ObjectName The type name of the object.
 * \note We recommend making objects immutable when possible.
 *       This macro is only reserved for objects that stores runtime states.
 */
#define TVM_DEFINE_MUTABLE_OBJECT_REF_METHODS(TypeName, ParentType, ObjectName)             \
  TypeName() = default;                                                                     \
  TVM_DEFINE_DEFAULT_COPY_MOVE_AND_ASSIGN(TypeName);                                        \
  explicit TypeName(::tvm::runtime::ObjectPtr<::tvm::runtime::Object> n) : ParentType(n) {} \
  ObjectName* operator->() const { return static_cast<ObjectName*>(data_.get()); }          \
  using ContainerType = ObjectName;

/*
 * \brief Define object reference methods that is both not nullable and mutable.
 *
 * \param TypeName The object type name
 * \param ParentType The parent type of the objectref
 * \param ObjectName The type name of the object.
 */
#define TVM_DEFINE_MUTABLE_NOTNULLABLE_OBJECT_REF_METHODS(TypeName, ParentType, ObjectName) \
  explicit TypeName(::tvm::runtime::ObjectPtr<::tvm::runtime::Object> n) : ParentType(n) {} \
  TVM_DEFINE_DEFAULT_COPY_MOVE_AND_ASSIGN(TypeName);                                        \
  ObjectName* operator->() const { return static_cast<ObjectName*>(data_.get()); }          \
  ObjectName* get() const { return operator->(); }                                          \
  static constexpr bool _type_is_nullable = false;                                          \
  using ContainerType = ObjectName;

#define TVM_DEFINE_OBJECT_REF_COW_METHOD(ObjectName)     \
  ObjectName* CopyOnWrite() {                            \
    ICHECK(data_ != nullptr);                            \
    if (!data_.unique()) {                               \
      auto n = make_object<ObjectName>(*(operator->())); \
      ObjectPtr<Object>(std::move(n)).swap(data_);       \
    }                                                    \
    return static_cast<ObjectName*>(data_.get());        \
  }

// Implementations details below
// Object reference counting.
#if TVM_OBJECT_ATOMIC_REF_COUNTER

inline void Object::IncRef() { ref_counter_.fetch_add(1, std::memory_order_relaxed); }

inline void Object::DecRef() {
  if (ref_counter_.fetch_sub(1, std::memory_order_release) == 1) {
    std::atomic_thread_fence(std::memory_order_acquire);
    if (this->deleter_ != nullptr) {
      (*this->deleter_)(this);
    }
  }
}

inline int Object::use_count() const { return ref_counter_.load(std::memory_order_relaxed); }

#else

inline void Object::IncRef() { ++ref_counter_; }

inline void Object::DecRef() {
  if (--ref_counter_ == 0) {
    if (this->deleter_ != nullptr) {
      (*this->deleter_)(this);
    }
  }
}

inline int Object::use_count() const { return ref_counter_; }

#endif  // TVM_OBJECT_ATOMIC_REF_COUNTER

template <typename TargetType>
inline bool Object::IsInstance() const {
  const Object* self = this;
  // NOTE: the following code can be optimized by
  // compiler dead-code elimination for already known constants.
  if (self != nullptr) {
    // Everything is a subclass of object.
    if (std::is_same<TargetType, Object>::value) return true;
    if (TargetType::_type_final) {
      // if the target type is a final type
      // then we only need to check the equivalence.
      return self->type_index_ == TargetType::RuntimeTypeIndex();
    } else {
      // if target type is a non-leaf type
      // Check if type index falls into the range of reserved slots.
      uint32_t begin = TargetType::RuntimeTypeIndex();
      // The condition will be optimized by constant-folding.
      if (TargetType::_type_child_slots != 0) {
        uint32_t end = begin + TargetType::_type_child_slots;
        if (self->type_index_ >= begin && self->type_index_ < end) return true;
      } else {
        if (self->type_index_ == begin) return true;
      }
      if (!TargetType::_type_child_slots_can_overflow) return false;
      // Invariance: parent index is always smaller than the child.
      if (self->type_index_ < TargetType::RuntimeTypeIndex()) return false;
      // The rare slower-path, check type hierarchy.
      return self->DerivedFrom(TargetType::RuntimeTypeIndex());
    }
  } else {
    return false;
  }
}

inline bool Object::unique() const { return use_count() == 1; }

template <typename ObjectType>
inline const ObjectType* ObjectRef::as() const {
  if (data_ != nullptr && data_->IsInstance<ObjectType>()) {
    return static_cast<ObjectType*>(data_.get());
  } else {
    return nullptr;
  }
}

template <typename RefType, typename ObjType>
inline RefType GetRef(const ObjType* ptr) {
  static_assert(std::is_base_of<typename RefType::ContainerType, ObjType>::value,
                "Can only cast to the ref of same container type");
  if (!RefType::_type_is_nullable) {
    ICHECK(ptr != nullptr);
  }
  return RefType(ObjectPtr<Object>(const_cast<Object*>(static_cast<const Object*>(ptr))));
}

template <typename BaseType, typename ObjType>
inline ObjectPtr<BaseType> GetObjectPtr(ObjType* ptr) {
  static_assert(std::is_base_of<BaseType, ObjType>::value,
                "Can only cast to the ref of same container type");
  return ObjectPtr<BaseType>(static_cast<Object*>(ptr));
}

template <typename SubRef, typename BaseRef>
inline SubRef Downcast(BaseRef ref) {
  if (ref.defined()) {
    ICHECK(ref->template IsInstance<typename SubRef::ContainerType>())
        << "Downcast from " << ref->GetTypeKey() << " to " << SubRef::ContainerType::_type_key
        << " failed.";
  } else {
    ICHECK(SubRef::_type_is_nullable) << "Downcast from nullptr to not nullable reference of "
                                      << SubRef::ContainerType::_type_key;
  }
  return SubRef(std::move(ref.data_));
}

}  // namespace runtime
}  // namespace tvm

#endif  // TVM_RUNTIME_OBJECT_H_