runtime/mirror/class.h

/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * Licensed 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 ART_RUNTIME_MIRROR_CLASS_H_
#define ART_RUNTIME_MIRROR_CLASS_H_

#include "gc/allocator_type.h"
#include "invoke_type.h"
#include "modifiers.h"
#include "object.h"
#include "object_callbacks.h"
#include "primitive.h"

/*
 * A magic value for refOffsets. Ignore the bits and walk the super
 * chain when this is the value.
 * [This is an unlikely "natural" value, since it would be 30 non-ref instance
 * fields followed by 2 ref instance fields.]
 */
#define CLASS_WALK_SUPER 3U
#define CLASS_BITS_PER_WORD (sizeof(uint32_t) * 8)
#define CLASS_OFFSET_ALIGNMENT 4
#define CLASS_HIGH_BIT (1U << (CLASS_BITS_PER_WORD - 1))
/*
 * Given an offset, return the bit number which would encode that offset.
 * Local use only.
 */
#define _CLASS_BIT_NUMBER_FROM_OFFSET(byteOffset) \
    ((unsigned int)(byteOffset) / \
     CLASS_OFFSET_ALIGNMENT)
/*
 * Is the given offset too large to be encoded?
 */
#define CLASS_CAN_ENCODE_OFFSET(byteOffset) \
    (_CLASS_BIT_NUMBER_FROM_OFFSET(byteOffset) < CLASS_BITS_PER_WORD)
/*
 * Return a single bit, encoding the offset.
 * Undefined if the offset is too large, as defined above.
 */
#define CLASS_BIT_FROM_OFFSET(byteOffset) \
    (CLASS_HIGH_BIT >> _CLASS_BIT_NUMBER_FROM_OFFSET(byteOffset))
/*
 * Return an offset, given a bit number as returned from CLZ.
 */
#define CLASS_OFFSET_FROM_CLZ(rshift) \
    MemberOffset((static_cast<int>(rshift) * CLASS_OFFSET_ALIGNMENT))

namespace art {

struct ClassClassOffsets;
struct ClassOffsets;
class Signature;
class StringPiece;

namespace mirror {

class ArtField;
class ClassLoader;
class DexCache;
class IfTable;

// C++ mirror of java.lang.Class
class MANAGED Class : public Object {
 public:
  // Class Status
  //
  // kStatusNotReady: If a Class cannot be found in the class table by
  // FindClass, it allocates an new one with AllocClass in the
  // kStatusNotReady and calls LoadClass. Note if it does find a
  // class, it may not be kStatusResolved and it will try to push it
  // forward toward kStatusResolved.
  //
  // kStatusIdx: LoadClass populates with Class with information from
  // the DexFile, moving the status to kStatusIdx, indicating that the
  // Class value in super_class_ has not been populated. The new Class
  // can then be inserted into the classes table.
  //
  // kStatusLoaded: After taking a lock on Class, the ClassLinker will
  // attempt to move a kStatusIdx class forward to kStatusLoaded by
  // using ResolveClass to initialize the super_class_ and ensuring the
  // interfaces are resolved.
  //
  // kStatusResolved: Still holding the lock on Class, the ClassLinker
  // shows linking is complete and fields of the Class populated by making
  // it kStatusResolved. Java allows circularities of the form where a super
  // class has a field that is of the type of the sub class. We need to be able
  // to fully resolve super classes while resolving types for fields.
  //
  // kStatusRetryVerificationAtRuntime: The verifier sets a class to
  // this state if it encounters a soft failure at compile time. This
  // often happens when there are unresolved classes in other dex
  // files, and this status marks a class as needing to be verified
  // again at runtime.
  //
  // TODO: Explain the other states
  enum Status {
    kStatusError = -1,
    kStatusNotReady = 0,
    kStatusIdx = 1,  // Loaded, DEX idx in super_class_type_idx_ and interfaces_type_idx_.
    kStatusLoaded = 2,  // DEX idx values resolved.
    kStatusResolved = 3,  // Part of linking.
    kStatusVerifying = 4,  // In the process of being verified.
    kStatusRetryVerificationAtRuntime = 5,  // Compile time verification failed, retry at runtime.
    kStatusVerifyingAtRuntime = 6,  // Retrying verification at runtime.
    kStatusVerified = 7,  // Logically part of linking; done pre-init.
    kStatusInitializing = 8,  // Class init in progress.
    kStatusInitialized = 9,  // Ready to go.
    kStatusMax = 10,
  };

  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  Status GetStatus() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    COMPILE_ASSERT(sizeof(Status) == sizeof(uint32_t), size_of_status_not_uint32);
    return static_cast<Status>(GetField32<kVerifyFlags>(OFFSET_OF_OBJECT_MEMBER(Class, status_)));
  }

  void SetStatus(Status new_status, Thread* self) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  static MemberOffset StatusOffset() {
    return OFFSET_OF_OBJECT_MEMBER(Class, status_);
  }

  // Returns true if the class has failed to link.
  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  bool IsErroneous() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return GetStatus<kVerifyFlags>() == kStatusError;
  }

  // Returns true if the class has been loaded.
  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  bool IsIdxLoaded() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return GetStatus<kVerifyFlags>() >= kStatusIdx;
  }

  // Returns true if the class has been loaded.
  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  bool IsLoaded() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return GetStatus<kVerifyFlags>() >= kStatusLoaded;
  }

  // Returns true if the class has been linked.
  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  bool IsResolved() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return GetStatus<kVerifyFlags>() >= kStatusResolved;
  }

  // Returns true if the class was compile-time verified.
  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  bool IsCompileTimeVerified() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return GetStatus<kVerifyFlags>() >= kStatusRetryVerificationAtRuntime;
  }

  // Returns true if the class has been verified.
  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  bool IsVerified() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return GetStatus<kVerifyFlags>() >= kStatusVerified;
  }

  // Returns true if the class is initializing.
  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  bool IsInitializing() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return GetStatus<kVerifyFlags>() >= kStatusInitializing;
  }

  // Returns true if the class is initialized.
  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  bool IsInitialized() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return GetStatus<kVerifyFlags>() == kStatusInitialized;
  }

  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  uint32_t GetAccessFlags() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  void SetAccessFlags(uint32_t new_access_flags) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    // Not called within a transaction.
    SetField32<false>(OFFSET_OF_OBJECT_MEMBER(Class, access_flags_), new_access_flags);
  }

  // Returns true if the class is an interface.
  bool IsInterface() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return (GetAccessFlags() & kAccInterface) != 0;
  }

  // Returns true if the class is declared public.
  bool IsPublic() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return (GetAccessFlags() & kAccPublic) != 0;
  }

  // Returns true if the class is declared final.
  bool IsFinal() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return (GetAccessFlags() & kAccFinal) != 0;
  }

  bool IsFinalizable() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return (GetAccessFlags() & kAccClassIsFinalizable) != 0;
  }

  void SetFinalizable() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    uint32_t flags = GetField32(OFFSET_OF_OBJECT_MEMBER(Class, access_flags_));
    SetAccessFlags(flags | kAccClassIsFinalizable);
  }

  // Returns true if the class is abstract.
  bool IsAbstract() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return (GetAccessFlags() & kAccAbstract) != 0;
  }

  // Returns true if the class is an annotation.
  bool IsAnnotation() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return (GetAccessFlags() & kAccAnnotation) != 0;
  }

  // Returns true if the class is synthetic.
  bool IsSynthetic() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return (GetAccessFlags() & kAccSynthetic) != 0;
  }

  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  bool IsReferenceClass() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return (GetAccessFlags<kVerifyFlags>() & kAccClassIsReference) != 0;
  }

  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  bool IsWeakReferenceClass() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return (GetAccessFlags<kVerifyFlags>() & kAccClassIsWeakReference) != 0;
  }

  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  bool IsSoftReferenceClass() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return (GetAccessFlags<kVerifyFlags>() & kAccReferenceFlagsMask) == kAccClassIsReference;
  }

  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  bool IsFinalizerReferenceClass() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return (GetAccessFlags<kVerifyFlags>() & kAccClassIsFinalizerReference) != 0;
  }

  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  bool IsPhantomReferenceClass() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return (GetAccessFlags<kVerifyFlags>() & kAccClassIsPhantomReference) != 0;
  }

  // Can references of this type be assigned to by things of another type? For non-array types
  // this is a matter of whether sub-classes may exist - which they can't if the type is final.
  // For array classes, where all the classes are final due to there being no sub-classes, an
  // Object[] may be assigned to by a String[] but a String[] may not be assigned to by other
  // types as the component is final.
  bool CannotBeAssignedFromOtherTypes() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    if (!IsArrayClass()) {
      return IsFinal();
    } else {
      Class* component = GetComponentType();
      if (component->IsPrimitive()) {
        return true;
      } else {
        return component->CannotBeAssignedFromOtherTypes();
      }
    }
  }

  String* GetName() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);  // Returns the cached name.
  void SetName(String* name) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);  // Sets the cached name.
  // Computes the name, then sets the cached value.
  String* ComputeName() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  bool IsProxyClass() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    // Read access flags without using getter as whether something is a proxy can be check in
    // any loaded state
    // TODO: switch to a check if the super class is java.lang.reflect.Proxy?
    uint32_t access_flags = GetField32<kVerifyFlags>(OFFSET_OF_OBJECT_MEMBER(Class, access_flags_));
    return (access_flags & kAccClassIsProxy) != 0;
  }

  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  Primitive::Type GetPrimitiveType() ALWAYS_INLINE SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  void SetPrimitiveType(Primitive::Type new_type) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    DCHECK_EQ(sizeof(Primitive::Type), sizeof(int32_t));
    SetField32<false>(OFFSET_OF_OBJECT_MEMBER(Class, primitive_type_), new_type);
  }

  // Returns true if the class is a primitive type.
  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  bool IsPrimitive() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return GetPrimitiveType<kVerifyFlags>() != Primitive::kPrimNot;
  }

  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  bool IsPrimitiveBoolean() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return GetPrimitiveType<kVerifyFlags>() == Primitive::kPrimBoolean;
  }

  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  bool IsPrimitiveByte() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return GetPrimitiveType<kVerifyFlags>() == Primitive::kPrimByte;
  }

  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  bool IsPrimitiveChar() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return GetPrimitiveType<kVerifyFlags>() == Primitive::kPrimChar;
  }

  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  bool IsPrimitiveShort() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return GetPrimitiveType<kVerifyFlags>() == Primitive::kPrimShort;
  }

  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  bool IsPrimitiveInt() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return GetPrimitiveType() == Primitive::kPrimInt;
  }

  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  bool IsPrimitiveLong() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return GetPrimitiveType<kVerifyFlags>() == Primitive::kPrimLong;
  }

  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  bool IsPrimitiveFloat() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return GetPrimitiveType<kVerifyFlags>() == Primitive::kPrimFloat;
  }

  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  bool IsPrimitiveDouble() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return GetPrimitiveType<kVerifyFlags>() == Primitive::kPrimDouble;
  }

  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  bool IsPrimitiveVoid() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return GetPrimitiveType<kVerifyFlags>() == Primitive::kPrimVoid;
  }

  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  bool IsPrimitiveArray() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return IsArrayClass<kVerifyFlags>() &&
        GetComponentType<static_cast<VerifyObjectFlags>(kVerifyFlags & ~kVerifyThis)>()->
        IsPrimitive();
  }

  // Depth of class from java.lang.Object
  uint32_t Depth() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    uint32_t depth = 0;
    for (Class* klass = this; klass->GetSuperClass() != NULL; klass = klass->GetSuperClass()) {
      depth++;
    }
    return depth;
  }

  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags, bool kDoReadBarrier = true>
  bool IsArrayClass() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return GetComponentType<kVerifyFlags, kDoReadBarrier>() != NULL;
  }

  bool IsClassClass() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  bool IsStringClass() const;

  bool IsThrowableClass() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  template<bool kDoReadBarrier = true>
  bool IsArtFieldClass() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  template<bool kDoReadBarrier = true>
  bool IsArtMethodClass();

  static MemberOffset ComponentTypeOffset() {
    return OFFSET_OF_OBJECT_MEMBER(Class, component_type_);
  }

  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags, bool kDoReadBarrier = true>
  Class* GetComponentType() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return GetFieldObject<Class, kVerifyFlags, kDoReadBarrier>(ComponentTypeOffset());
  }

  void SetComponentType(Class* new_component_type) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    DCHECK(GetComponentType() == NULL);
    DCHECK(new_component_type != NULL);
    // Component type is invariant: use non-transactional mode without check.
    SetFieldObject<false, false>(ComponentTypeOffset(), new_component_type);
  }

  template<bool kDoReadBarrier = true>
  size_t GetComponentSize() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return Primitive::ComponentSize(
        GetComponentType<kDefaultVerifyFlags, kDoReadBarrier>()->GetPrimitiveType());
  }

  bool IsObjectClass() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return !IsPrimitive() && GetSuperClass() == NULL;
  }
  bool IsInstantiable() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return (!IsPrimitive() && !IsInterface() && !IsAbstract()) || ((IsAbstract()) && IsArrayClass());
  }

  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  bool IsObjectArrayClass() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return GetComponentType<kVerifyFlags>() != nullptr && !GetComponentType<kVerifyFlags>()->IsPrimitive();
  }

  // Creates a raw object instance but does not invoke the default constructor.
  template <bool kIsInstrumented>
  ALWAYS_INLINE Object* Alloc(Thread* self, gc::AllocatorType allocator_type)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  Object* AllocObject(Thread* self)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
  Object* AllocNonMovableObject(Thread* self)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  bool IsVariableSize() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    // Classes and arrays vary in size, and so the object_size_ field cannot
    // be used to get their instance size
    return IsClassClass() || IsArrayClass();
  }

  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags, bool kDoReadBarrier = true>
  uint32_t SizeOf() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return GetField32<kVerifyFlags>(OFFSET_OF_OBJECT_MEMBER(Class, class_size_));
  }

  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  uint32_t GetClassSize() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return GetField32<kVerifyFlags>(OFFSET_OF_OBJECT_MEMBER(Class, class_size_));
  }

  void SetClassSize(uint32_t new_class_size)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  uint32_t GetObjectSize() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  void SetObjectSize(uint32_t new_object_size) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    DCHECK(!IsVariableSize());
    // Not called within a transaction.
    return SetField32<false>(OFFSET_OF_OBJECT_MEMBER(Class, object_size_), new_object_size);
  }

  // Returns true if this class is in the same packages as that class.
  bool IsInSamePackage(Class* that) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  static bool IsInSamePackage(const StringPiece& descriptor1, const StringPiece& descriptor2);

  // Returns true if this class can access that class.
  bool CanAccess(Class* that) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return that->IsPublic() || this->IsInSamePackage(that);
  }

  // Can this class access a member in the provided class with the provided member access flags?
  // Note that access to the class isn't checked in case the declaring class is protected and the
  // method has been exposed by a public sub-class
  bool CanAccessMember(Class* access_to, uint32_t member_flags)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    // Classes can access all of their own members
    if (this == access_to) {
      return true;
    }
    // Public members are trivially accessible
    if (member_flags & kAccPublic) {
      return true;
    }
    // Private members are trivially not accessible
    if (member_flags & kAccPrivate) {
      return false;
    }
    // Check for protected access from a sub-class, which may or may not be in the same package.
    if (member_flags & kAccProtected) {
      if (this->IsSubClass(access_to)) {
        return true;
      }
    }
    // Allow protected access from other classes in the same package.
    return this->IsInSamePackage(access_to);
  }

  // Can this class access a resolved field?
  // Note that access to field's class is checked and this may require looking up the class
  // referenced by the FieldId in the DexFile in case the declaring class is inaccessible.
  bool CanAccessResolvedField(Class* access_to, ArtField* field,
                              DexCache* dex_cache, uint32_t field_idx)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
  bool CheckResolvedFieldAccess(Class* access_to, ArtField* field,
                                uint32_t field_idx)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  // Can this class access a resolved method?
  // Note that access to methods's class is checked and this may require looking up the class
  // referenced by the MethodId in the DexFile in case the declaring class is inaccessible.
  bool CanAccessResolvedMethod(Class* access_to, ArtMethod* resolved_method,
                               DexCache* dex_cache, uint32_t method_idx)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
  template <InvokeType throw_invoke_type>
  bool CheckResolvedMethodAccess(Class* access_to, ArtMethod* resolved_method,
                                 uint32_t method_idx)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  bool IsSubClass(Class* klass) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  // Can src be assigned to this class? For example, String can be assigned to Object (by an
  // upcast), however, an Object cannot be assigned to a String as a potentially exception throwing
  // downcast would be necessary. Similarly for interfaces, a class that implements (or an interface
  // that extends) another can be assigned to its parent, but not vice-versa. All Classes may assign
  // to themselves. Classes for primitive types may not assign to each other.
  inline bool IsAssignableFrom(Class* src) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    DCHECK(src != NULL);
    if (this == src) {
      // Can always assign to things of the same type.
      return true;
    } else if (IsObjectClass()) {
      // Can assign any reference to java.lang.Object.
      return !src->IsPrimitive();
    } else if (IsInterface()) {
      return src->Implements(this);
    } else if (src->IsArrayClass()) {
      return IsAssignableFromArray(src);
    } else {
      return !src->IsInterface() && src->IsSubClass(this);
    }
  }

  Class* GetSuperClass() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  void SetSuperClass(Class *new_super_class) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    // Super class is assigned once, except during class linker initialization.
    Class* old_super_class = GetFieldObject<Class>(OFFSET_OF_OBJECT_MEMBER(Class, super_class_));
    DCHECK(old_super_class == nullptr || old_super_class == new_super_class);
    DCHECK(new_super_class != nullptr);
    SetFieldObject<false>(OFFSET_OF_OBJECT_MEMBER(Class, super_class_), new_super_class);
  }

  bool HasSuperClass() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return GetSuperClass() != NULL;
  }

  static MemberOffset SuperClassOffset() {
    return MemberOffset(OFFSETOF_MEMBER(Class, super_class_));
  }

  ClassLoader* GetClassLoader() ALWAYS_INLINE SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  void SetClassLoader(ClassLoader* new_cl) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  static MemberOffset DexCacheOffset() {
    return MemberOffset(OFFSETOF_MEMBER(Class, dex_cache_));
  }

  enum {
    kDumpClassFullDetail = 1,
    kDumpClassClassLoader = (1 << 1),
    kDumpClassInitialized = (1 << 2),
  };

  void DumpClass(std::ostream& os, int flags) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  DexCache* GetDexCache() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  void SetDexCache(DexCache* new_dex_cache) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  ObjectArray<ArtMethod>* GetDirectMethods() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  void SetDirectMethods(ObjectArray<ArtMethod>* new_direct_methods)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  ArtMethod* GetDirectMethod(int32_t i) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  void SetDirectMethod(uint32_t i, ArtMethod* f)  // TODO: uint16_t
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  // Returns the number of static, private, and constructor methods.
  uint32_t NumDirectMethods() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  ObjectArray<ArtMethod>* GetVirtualMethods() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  void SetVirtualMethods(ObjectArray<ArtMethod>* new_virtual_methods)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  // Returns the number of non-inherited virtual methods.
  uint32_t NumVirtualMethods() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  ArtMethod* GetVirtualMethod(uint32_t i) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  ArtMethod* GetVirtualMethodDuringLinking(uint32_t i) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  void SetVirtualMethod(uint32_t i, ArtMethod* f)  // TODO: uint16_t
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  ObjectArray<ArtMethod>* GetVTable() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  ObjectArray<ArtMethod>* GetVTableDuringLinking() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  void SetVTable(ObjectArray<ArtMethod>* new_vtable)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  static MemberOffset VTableOffset() {
    return OFFSET_OF_OBJECT_MEMBER(Class, vtable_);
  }

  ObjectArray<ArtMethod>* GetImTable() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  void SetImTable(ObjectArray<ArtMethod>* new_imtable)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  static MemberOffset ImTableOffset() {
    return OFFSET_OF_OBJECT_MEMBER(Class, imtable_);
  }

  // Given a method implemented by this class but potentially from a super class, return the
  // specific implementation method for this class.
  ArtMethod* FindVirtualMethodForVirtual(ArtMethod* method)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  // Given a method implemented by this class' super class, return the specific implementation
  // method for this class.
  ArtMethod* FindVirtualMethodForSuper(ArtMethod* method)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  // Given a method implemented by this class, but potentially from a
  // super class or interface, return the specific implementation
  // method for this class.
  ArtMethod* FindVirtualMethodForInterface(ArtMethod* method)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) ALWAYS_INLINE;

  ArtMethod* FindVirtualMethodForVirtualOrInterface(ArtMethod* method)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  ArtMethod* FindInterfaceMethod(const StringPiece& name, const Signature& signature)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  ArtMethod* FindInterfaceMethod(const DexCache* dex_cache, uint32_t dex_method_idx)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  ArtMethod* FindDeclaredDirectMethod(const StringPiece& name, const StringPiece& signature)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  ArtMethod* FindDeclaredDirectMethod(const StringPiece& name, const Signature& signature)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  ArtMethod* FindDeclaredDirectMethod(const DexCache* dex_cache, uint32_t dex_method_idx)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  ArtMethod* FindDirectMethod(const StringPiece& name, const StringPiece& signature)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  ArtMethod* FindDirectMethod(const StringPiece& name, const Signature& signature)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  ArtMethod* FindDirectMethod(const DexCache* dex_cache, uint32_t dex_method_idx)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  ArtMethod* FindDeclaredVirtualMethod(const StringPiece& name, const StringPiece& signature)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  ArtMethod* FindDeclaredVirtualMethod(const StringPiece& name, const Signature& signature)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  ArtMethod* FindDeclaredVirtualMethod(const DexCache* dex_cache, uint32_t dex_method_idx)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  ArtMethod* FindVirtualMethod(const StringPiece& name, const StringPiece& signature)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  ArtMethod* FindVirtualMethod(const StringPiece& name, const Signature& signature)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  ArtMethod* FindVirtualMethod(const DexCache* dex_cache, uint32_t dex_method_idx)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  ArtMethod* FindClassInitializer() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  int32_t GetIfTableCount() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  IfTable* GetIfTable() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  void SetIfTable(IfTable* new_iftable) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  // Get instance fields of the class (See also GetSFields).
  ObjectArray<ArtField>* GetIFields() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  void SetIFields(ObjectArray<ArtField>* new_ifields) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  uint32_t NumInstanceFields() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  ArtField* GetInstanceField(uint32_t i)  // TODO: uint16_t
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  void SetInstanceField(uint32_t i, ArtField* f)  // TODO: uint16_t
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  // Returns the number of instance fields containing reference types.
  uint32_t NumReferenceInstanceFields() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    DCHECK(IsResolved() || IsErroneous());
    return GetField32(OFFSET_OF_OBJECT_MEMBER(Class, num_reference_instance_fields_));
  }

  uint32_t NumReferenceInstanceFieldsDuringLinking() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    DCHECK(IsLoaded() || IsErroneous());
    return GetField32(OFFSET_OF_OBJECT_MEMBER(Class, num_reference_instance_fields_));
  }

  void SetNumReferenceInstanceFields(uint32_t new_num) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    // Not called within a transaction.
    SetField32<false>(OFFSET_OF_OBJECT_MEMBER(Class, num_reference_instance_fields_), new_num);
  }

  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  uint32_t GetReferenceInstanceOffsets() ALWAYS_INLINE SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  void SetReferenceInstanceOffsets(uint32_t new_reference_offsets)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  // Beginning of static field data
  static MemberOffset FieldsOffset() {
    return OFFSET_OF_OBJECT_MEMBER(Class, fields_);
  }

  // Returns the number of static fields containing reference types.
  uint32_t NumReferenceStaticFields() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    DCHECK(IsResolved() || IsErroneous());
    return GetField32(OFFSET_OF_OBJECT_MEMBER(Class, num_reference_static_fields_));
  }

  uint32_t NumReferenceStaticFieldsDuringLinking() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    DCHECK(IsLoaded() || IsErroneous());
    return GetField32(OFFSET_OF_OBJECT_MEMBER(Class, num_reference_static_fields_));
  }

  void SetNumReferenceStaticFields(uint32_t new_num) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    // Not called within a transaction.
    SetField32<false>(OFFSET_OF_OBJECT_MEMBER(Class, num_reference_static_fields_), new_num);
  }

  // Gets the static fields of the class.
  ObjectArray<ArtField>* GetSFields() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  void SetSFields(ObjectArray<ArtField>* new_sfields) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  uint32_t NumStaticFields() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  // TODO: uint16_t
  ArtField* GetStaticField(uint32_t i) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  // TODO: uint16_t
  void SetStaticField(uint32_t i, ArtField* f) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
  uint32_t GetReferenceStaticOffsets() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return GetField32<kVerifyFlags>(OFFSET_OF_OBJECT_MEMBER(Class, reference_static_offsets_));
  }

  void SetReferenceStaticOffsets(uint32_t new_reference_offsets)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  // Find a static or instance field using the JLS resolution order
  ArtField* FindField(const StringPiece& name, const StringPiece& type)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  // Finds the given instance field in this class or a superclass.
  ArtField* FindInstanceField(const StringPiece& name, const StringPiece& type)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  // Finds the given instance field in this class or a superclass, only searches classes that
  // have the same dex cache.
  ArtField* FindInstanceField(const DexCache* dex_cache, uint32_t dex_field_idx)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  ArtField* FindDeclaredInstanceField(const StringPiece& name, const StringPiece& type)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  ArtField* FindDeclaredInstanceField(const DexCache* dex_cache, uint32_t dex_field_idx)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  // Finds the given static field in this class or a superclass.
  ArtField* FindStaticField(const StringPiece& name, const StringPiece& type)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  // Finds the given static field in this class or superclass, only searches classes that
  // have the same dex cache.
  ArtField* FindStaticField(const DexCache* dex_cache, uint32_t dex_field_idx)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  ArtField* FindDeclaredStaticField(const StringPiece& name, const StringPiece& type)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  ArtField* FindDeclaredStaticField(const DexCache* dex_cache, uint32_t dex_field_idx)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  pid_t GetClinitThreadId() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    DCHECK(IsIdxLoaded() || IsErroneous());
    return GetField32(OFFSET_OF_OBJECT_MEMBER(Class, clinit_thread_id_));
  }

  void SetClinitThreadId(pid_t new_clinit_thread_id) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  Class* GetVerifyErrorClass() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    // DCHECK(IsErroneous());
    return GetFieldObject<Class>(OFFSET_OF_OBJECT_MEMBER(Class, verify_error_class_));
  }

  uint16_t GetDexClassDefIndex() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return GetField32(OFFSET_OF_OBJECT_MEMBER(Class, dex_class_def_idx_));
  }

  void SetDexClassDefIndex(uint16_t class_def_idx) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    // Not called within a transaction.
    SetField32<false>(OFFSET_OF_OBJECT_MEMBER(Class, dex_class_def_idx_), class_def_idx);
  }

  uint16_t GetDexTypeIndex() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    return GetField32(OFFSET_OF_OBJECT_MEMBER(Class, dex_type_idx_));
  }

  void SetDexTypeIndex(uint16_t type_idx) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    // Not called within a transaction.
    SetField32<false>(OFFSET_OF_OBJECT_MEMBER(Class, dex_type_idx_), type_idx);
  }

  static Class* GetJavaLangClass() {
    DCHECK(java_lang_Class_ != NULL);
    return java_lang_Class_;
  }

  // Can't call this SetClass or else gets called instead of Object::SetClass in places.
  static void SetClassClass(Class* java_lang_Class);
  static void ResetClass();
  static void VisitRoots(RootCallback* callback, void* arg)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  // When class is verified, set the kAccPreverified flag on each method.
  void SetPreverifiedFlagOnAllMethods() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  template <bool kVisitClass, typename Visitor>
  void VisitReferences(mirror::Class* klass, const Visitor& visitor)
      NO_THREAD_SAFETY_ANALYSIS;

 private:
  void SetVerifyErrorClass(Class* klass) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  template <bool throw_on_failure, bool use_referrers_cache>
  bool ResolvedFieldAccessTest(Class* access_to, ArtField* field,
                               uint32_t field_idx, DexCache* dex_cache)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
  template <bool throw_on_failure, bool use_referrers_cache, InvokeType throw_invoke_type>
  bool ResolvedMethodAccessTest(Class* access_to, ArtMethod* resolved_method,
                                uint32_t method_idx, DexCache* dex_cache)
      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  bool Implements(Class* klass) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
  bool IsArrayAssignableFromArray(Class* klass) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
  bool IsAssignableFromArray(Class* klass) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  void CheckObjectAlloc() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);

  // defining class loader, or NULL for the "bootstrap" system loader
  HeapReference<ClassLoader> class_loader_;

  // For array classes, the component class object for instanceof/checkcast
  // (for String[][][], this will be String[][]). NULL for non-array classes.
  HeapReference<Class> component_type_;

  // DexCache of resolved constant pool entries (will be NULL for classes generated by the
  // runtime such as arrays and primitive classes).
  HeapReference<DexCache> dex_cache_;

  // static, private, and <init> methods
  HeapReference<ObjectArray<ArtMethod> > direct_methods_;

  // instance fields
  //
  // These describe the layout of the contents of an Object.
  // Note that only the fields directly declared by this class are
  // listed in ifields; fields declared by a superclass are listed in
  // the superclass's Class.ifields.
  //
  // All instance fields that refer to objects are guaranteed to be at
  // the beginning of the field list.  num_reference_instance_fields_
  // specifies the number of reference fields.
  HeapReference<ObjectArray<ArtField> > ifields_;

  // The interface table (iftable_) contains pairs of a interface class and an array of the
  // interface methods. There is one pair per interface supported by this class.  That means one
  // pair for each interface we support directly, indirectly via superclass, or indirectly via a
  // superinterface.  This will be null if neither we nor our superclass implement any interfaces.
  //
  // Why we need this: given "class Foo implements Face", declare "Face faceObj = new Foo()".
  // Invoke faceObj.blah(), where "blah" is part of the Face interface.  We can't easily use a
  // single vtable.
  //
  // For every interface a concrete class implements, we create an array of the concrete vtable_
  // methods for the methods in the interface.
  HeapReference<IfTable> iftable_;

  // Interface method table (imt), for quick "invoke-interface".
  HeapReference<ObjectArray<ArtMethod> > imtable_;

  // Descriptor for the class such as "java.lang.Class" or "[C". Lazily initialized by ComputeName
  HeapReference<String> name_;

  // Static fields
  HeapReference<ObjectArray<ArtField>> sfields_;

  // The superclass, or NULL if this is java.lang.Object, an interface or primitive type.
  HeapReference<Class> super_class_;

  // If class verify fails, we must return same error on subsequent tries.
  HeapReference<Class> verify_error_class_;

  // Virtual methods defined in this class; invoked through vtable.
  HeapReference<ObjectArray<ArtMethod> > virtual_methods_;

  // Virtual method table (vtable), for use by "invoke-virtual".  The vtable from the superclass is
  // copied in, and virtual methods from our class either replace those from the super or are
  // appended. For abstract classes, methods may be created in the vtable that aren't in
  // virtual_ methods_ for miranda methods.
  HeapReference<ObjectArray<ArtMethod> > vtable_;

  // Access flags; low 16 bits are defined by VM spec.
  uint32_t access_flags_;

  // Total size of the Class instance; used when allocating storage on gc heap.
  // See also object_size_.
  uint32_t class_size_;

  // Tid used to check for recursive <clinit> invocation.
  pid_t clinit_thread_id_;

  // ClassDef index in dex file, -1 if no class definition such as an array.
  // TODO: really 16bits
  int32_t dex_class_def_idx_;

  // Type index in dex file.
  // TODO: really 16bits
  int32_t dex_type_idx_;

  // Number of instance fields that are object refs.
  uint32_t num_reference_instance_fields_;

  // Number of static fields that are object refs,
  uint32_t num_reference_static_fields_;

  // Total object size; used when allocating storage on gc heap.
  // (For interfaces and abstract classes this will be zero.)
  // See also class_size_.
  uint32_t object_size_;

  // Primitive type value, or Primitive::kPrimNot (0); set for generated primitive classes.
  Primitive::Type primitive_type_;

  // Bitmap of offsets of ifields.
  uint32_t reference_instance_offsets_;

  // Bitmap of offsets of sfields.
  uint32_t reference_static_offsets_;

  // State of class initialization.
  Status status_;

  // TODO: ?
  // initiating class loader list
  // NOTE: for classes with low serialNumber, these are unused, and the
  // values are kept in a table in gDvm.
  // InitiatingLoaderList initiating_loader_list_;

  // Location of first static field.
  uint32_t fields_[0];

  // java.lang.Class
  static Class* java_lang_Class_;

  friend struct art::ClassOffsets;  // for verifying offset information
  DISALLOW_IMPLICIT_CONSTRUCTORS(Class);
};

std::ostream& operator<<(std::ostream& os, const Class::Status& rhs);

class MANAGED ClassClass : public Class {
 private:
  int32_t pad_;
  int64_t serialVersionUID_;
  friend struct art::ClassClassOffsets;  // for verifying offset information
  DISALLOW_IMPLICIT_CONSTRUCTORS(ClassClass);
};

}  // namespace mirror
}  // namespace art

#endif  // ART_RUNTIME_MIRROR_CLASS_H_