src/object.cc

// Copyright 2011 Google Inc. All Rights Reserved.

#include "object.h"

#include <string.h>

#include <algorithm>
#include <string>
#include <utility>

#include "class_linker.h"
#include "class_loader.h"
#include "globals.h"
#include "heap.h"
#include "intern_table.h"
#include "logging.h"
#include "dex_cache.h"
#include "dex_file.h"
#include "runtime.h"

namespace art {

bool Object::IsString() const {
  // TODO use "klass_ == String::GetJavaLangString()" instead?
  return GetClass() == GetClass()->GetDescriptor()->GetClass();
}

// TODO: get global references for these
Class* Field::java_lang_reflect_Field_ = NULL;

void Field::SetClass(Class* java_lang_reflect_Field) {
  CHECK(java_lang_reflect_Field_ == NULL);
  CHECK(java_lang_reflect_Field != NULL);
  java_lang_reflect_Field_ = java_lang_reflect_Field;
}

void Field::ResetClass() {
  CHECK(java_lang_reflect_Field_ != NULL);
  java_lang_reflect_Field_ = NULL;
}

void Field::SetTypeIdx(uint32_t type_idx) {
  SetField32(OFFSET_OF_OBJECT_MEMBER(Field, type_idx_), type_idx, false);
}

Class* Field::GetTypeDuringLinking() const {
  // We are assured that the necessary primitive types are in the dex cache
  // early during class linking
  return GetDeclaringClass()->GetDexCache()->GetResolvedType(GetTypeIdx());
}

Class* Field::GetType() const {
  // Do full linkage (which sets dex cache value to speed next call)
  return Runtime::Current()->GetClassLinker()->ResolveType(GetTypeIdx(), this);
}

Field* Field::FindFieldFromCode(uint32_t field_idx, const Method* referrer) {
  ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
  Field* f = class_linker->ResolveField(field_idx, referrer);
  if (f != NULL) {
    Class* c = f->GetDeclaringClass();
    // If the class is already initializing, we must be inside <clinit>, or
    // we'd still be waiting for the lock.
    if (c->GetStatus() == Class::kStatusInitializing || class_linker->EnsureInitialized(c)) {
      return f;
    }
  }
  UNIMPLEMENTED(FATAL) << "throw an error and unwind";
  return NULL;
}

uint32_t Field::Get32StaticFromCode(uint32_t field_idx, const Method* referrer) {
  Field* field = FindFieldFromCode(field_idx, referrer);
  DCHECK(field->GetType()->PrimitiveSize() == sizeof(int32_t));
  return field->Get32(NULL);
}
void Field::Set32StaticFromCode(uint32_t field_idx, const Method* referrer, uint32_t new_value) {
  Field* field = FindFieldFromCode(field_idx, referrer);
  DCHECK(field->GetType()->PrimitiveSize() == sizeof(int32_t));
  field->Set32(NULL, new_value);
}
uint64_t Field::Get64StaticFromCode(uint32_t field_idx, const Method* referrer) {
  Field* field = FindFieldFromCode(field_idx, referrer);
  DCHECK(field->GetType()->PrimitiveSize() == sizeof(int64_t));
  return field->Get64(NULL);
}
void Field::Set64StaticFromCode(uint32_t field_idx, const Method* referrer, uint64_t new_value) {
  Field* field = FindFieldFromCode(field_idx, referrer);
  DCHECK(field->GetType()->PrimitiveSize() == sizeof(int64_t));
  field->Set64(NULL, new_value);
}
Object* Field::GetObjStaticFromCode(uint32_t field_idx, const Method* referrer) {
  Field* field = FindFieldFromCode(field_idx, referrer);
  DCHECK(!field->GetType()->IsPrimitive());
  return field->GetObj(NULL);
}
void Field::SetObjStaticFromCode(uint32_t field_idx, const Method* referrer, Object* new_value) {
  Field* field = FindFieldFromCode(field_idx, referrer);
  DCHECK(!field->GetType()->IsPrimitive());
  field->SetObj(NULL, new_value);
}

uint32_t Field::Get32(const Object* object) const {
  CHECK((object == NULL) == IsStatic());
  if (IsStatic()) {
    object = declaring_class_;
  }
  return object->GetField32(GetOffset(), IsVolatile());
}

void Field::Set32(Object* object, uint32_t new_value) const {
  CHECK((object == NULL) == IsStatic());
  if (IsStatic()) {
    object = declaring_class_;
  }
  object->SetField32(GetOffset(), new_value, IsVolatile());
}

uint64_t Field::Get64(const Object* object) const {
  CHECK((object == NULL) == IsStatic());
  if (IsStatic()) {
    object = declaring_class_;
  }
  return object->GetField64(GetOffset(), IsVolatile());
}

void Field::Set64(Object* object, uint64_t new_value) const {
  CHECK((object == NULL) == IsStatic());
  if (IsStatic()) {
    object = declaring_class_;
  }
  object->SetField64(GetOffset(), new_value, IsVolatile());
}

Object* Field::GetObj(const Object* object) const {
  CHECK((object == NULL) == IsStatic());
  if (IsStatic()) {
    object = declaring_class_;
  }
  return object->GetFieldObject<Object*>(GetOffset(), IsVolatile());
}

void Field::SetObj(Object* object, const Object* new_value) const {
  CHECK((object == NULL) == IsStatic());
  if (IsStatic()) {
    object = declaring_class_;
  }
  object->SetFieldObject(GetOffset(), new_value, IsVolatile());
}

bool Field::GetBoolean(const Object* object) const {
  DCHECK(GetType()->IsPrimitiveBoolean());
  return Get32(object);
}

void Field::SetBoolean(Object* object, bool z) const {
  DCHECK(GetType()->IsPrimitiveBoolean());
  Set32(object, z);
}

int8_t Field::GetByte(const Object* object) const {
  DCHECK(GetType()->IsPrimitiveByte());
  return Get32(object);
}

void Field::SetByte(Object* object, int8_t b) const {
  DCHECK(GetType()->IsPrimitiveByte());
  Set32(object, b);
}

uint16_t Field::GetChar(const Object* object) const {
  DCHECK(GetType()->IsPrimitiveChar());
  return Get32(object);
}

void Field::SetChar(Object* object, uint16_t c) const {
  DCHECK(GetType()->IsPrimitiveChar());
  Set32(object, c);
}

uint16_t Field::GetShort(const Object* object) const {
  DCHECK(GetType()->IsPrimitiveShort());
  return Get32(object);
}

void Field::SetShort(Object* object, uint16_t s) const {
  DCHECK(GetType()->IsPrimitiveShort());
  Set32(object, s);
}

int32_t Field::GetInt(const Object* object) const {
  DCHECK(GetType()->IsPrimitiveInt());
  return Get32(object);
}

void Field::SetInt(Object* object, int32_t i) const {
  DCHECK(GetType()->IsPrimitiveInt()) << PrettyField(this);
  Set32(object, i);
}

int64_t Field::GetLong(const Object* object) const {
  DCHECK(GetType()->IsPrimitiveLong());
  return Get64(object);
}

void Field::SetLong(Object* object, int64_t j) const {
  DCHECK(GetType()->IsPrimitiveLong());
  Set64(object, j);
}

float Field::GetFloat(const Object* object) const {
  DCHECK(GetType()->IsPrimitiveFloat());
  JValue float_bits;
  float_bits.i = Get32(object);
  return float_bits.f;
}

void Field::SetFloat(Object* object, float f) const {
  DCHECK(GetType()->IsPrimitiveFloat());
  JValue float_bits;
  float_bits.f = f;
  Set32(object, float_bits.i);
}

double Field::GetDouble(const Object* object) const {
  DCHECK(GetType()->IsPrimitiveDouble());
  JValue double_bits;
  double_bits.j = Get64(object);
  return double_bits.d;
}

void Field::SetDouble(Object* object, double d) const {
  DCHECK(GetType()->IsPrimitiveDouble());
  JValue double_bits;
  double_bits.d = d;
  Set64(object, double_bits.j);
}

Object* Field::GetObject(const Object* object) const {
  CHECK(!GetType()->IsPrimitive());
  return GetObj(object);
}

void Field::SetObject(Object* object, const Object* l) const {
  CHECK(!GetType()->IsPrimitive());
  SetObj(object, l);
}

// TODO: get global references for these
Class* Method::java_lang_reflect_Method_ = NULL;

void Method::SetClass(Class* java_lang_reflect_Method) {
  CHECK(java_lang_reflect_Method_ == NULL);
  CHECK(java_lang_reflect_Method != NULL);
  java_lang_reflect_Method_ = java_lang_reflect_Method;
}

void Method::ResetClass() {
  CHECK(java_lang_reflect_Method_ != NULL);
  java_lang_reflect_Method_ = NULL;
}

ObjectArray<String>* Method::GetDexCacheStrings() const {
  return GetFieldObject<ObjectArray<String>*>(
      OFFSET_OF_OBJECT_MEMBER(Method, dex_cache_strings_), false);
}

void Method::SetReturnTypeIdx(uint32_t new_return_type_idx) {
  SetField32(OFFSET_OF_OBJECT_MEMBER(Method, java_return_type_idx_),
             new_return_type_idx, false);
}

Class* Method::GetReturnType() const {
  DCHECK(GetDeclaringClass()->IsResolved());
  // Short-cut
  Class* result = GetDexCacheResolvedTypes()->Get(GetReturnTypeIdx());
  if (result == NULL) {
    // Do full linkage and set cache value for next call
    result = Runtime::Current()->GetClassLinker()->ResolveType(GetReturnTypeIdx(), this);
  }
  CHECK(result != NULL);
  return result;
}

void Method::SetDexCacheStrings(ObjectArray<String>* new_dex_cache_strings) {
  SetFieldObject(OFFSET_OF_OBJECT_MEMBER(Method, dex_cache_strings_),
                 new_dex_cache_strings, false);
}

ObjectArray<Class>* Method::GetDexCacheResolvedTypes() const {
  return GetFieldObject<ObjectArray<Class>*>(
      OFFSET_OF_OBJECT_MEMBER(Method, dex_cache_resolved_types_), false);
}

void Method::SetDexCacheResolvedTypes(ObjectArray<Class>* new_dex_cache_classes) {
  SetFieldObject(OFFSET_OF_OBJECT_MEMBER(Method, dex_cache_resolved_types_),
                 new_dex_cache_classes, false);
}

ObjectArray<Method>* Method::GetDexCacheResolvedMethods() const {
  return GetFieldObject<ObjectArray<Method>*>(
      OFFSET_OF_OBJECT_MEMBER(Method, dex_cache_resolved_methods_), false);
}

void Method::SetDexCacheResolvedMethods(ObjectArray<Method>* new_dex_cache_methods) {
  SetFieldObject(OFFSET_OF_OBJECT_MEMBER(Method, dex_cache_resolved_methods_),
                 new_dex_cache_methods, false);
}

ObjectArray<Field>* Method::GetDexCacheResolvedFields() const {
  return GetFieldObject<ObjectArray<Field>*>(
      OFFSET_OF_OBJECT_MEMBER(Method, dex_cache_resolved_fields_), false);
}

void Method::SetDexCacheResolvedFields(ObjectArray<Field>* new_dex_cache_fields) {
  SetFieldObject(OFFSET_OF_OBJECT_MEMBER(Method, dex_cache_resolved_fields_),
                 new_dex_cache_fields, false);
}

CodeAndDirectMethods* Method::GetDexCacheCodeAndDirectMethods() const {
  return GetFieldPtr<CodeAndDirectMethods*>(
      OFFSET_OF_OBJECT_MEMBER(Method, dex_cache_code_and_direct_methods_),
      false);
}

void Method::SetDexCacheCodeAndDirectMethods(CodeAndDirectMethods* new_value) {
  SetFieldPtr<CodeAndDirectMethods*>(
      OFFSET_OF_OBJECT_MEMBER(Method, dex_cache_code_and_direct_methods_),
      new_value, false);
}

ObjectArray<StaticStorageBase>* Method::GetDexCacheInitializedStaticStorage() const {
  return GetFieldObject<ObjectArray<StaticStorageBase>*>(
      OFFSET_OF_OBJECT_MEMBER(Method, dex_cache_initialized_static_storage_),
      false);
}

void Method::SetDexCacheInitializedStaticStorage(ObjectArray<StaticStorageBase>* new_value) {
  SetFieldObject(
      OFFSET_OF_OBJECT_MEMBER(Method, dex_cache_initialized_static_storage_),
      new_value, false);

}

size_t Method::NumArgRegisters(const StringPiece& shorty) {
  CHECK_LE(1, shorty.length());
  uint32_t num_registers = 0;
  for (int i = 1; i < shorty.length(); ++i) {
    char ch = shorty[i];
    if (ch == 'D' || ch == 'J') {
      num_registers += 2;
    } else {
      num_registers += 1;
    }
  }
  return num_registers;
}

size_t Method::NumArgArrayBytes() const {
  const String* shorty = GetShorty();
  size_t num_bytes = 0;
  for (int i = 1; i < shorty->GetLength(); ++i) {
    char ch = shorty->CharAt(i);
    if (ch == 'D' || ch == 'J') {
      num_bytes += 8;
    } else if (ch == 'L') {
      // Argument is a reference or an array.  The shorty descriptor
      // does not distinguish between these types.
      num_bytes += sizeof(Object*);
    } else {
      num_bytes += 4;
    }
  }
  return num_bytes;
}

size_t Method::NumArgs() const {
  // "1 +" because the first in Args is the receiver.
  // "- 1" because we don't count the return type.
  return (IsStatic() ? 0 : 1) + GetShorty()->GetLength() - 1;
}

// The number of reference arguments to this method including implicit this
// pointer
size_t Method::NumReferenceArgs() const {
  const String* shorty = GetShorty();
  size_t result = IsStatic() ? 0 : 1;  // The implicit this pointer.
  for (int i = 1; i < shorty->GetLength(); i++) {
    char ch = shorty->CharAt(i);
    if ((ch == 'L') || (ch == '[')) {
      result++;
    }
  }
  return result;
}

// The number of long or double arguments
size_t Method::NumLongOrDoubleArgs() const {
  const String* shorty = GetShorty();
  size_t result = 0;
  for (int i = 1; i < shorty->GetLength(); i++) {
    char ch = shorty->CharAt(i);
    if ((ch == 'D') || (ch == 'J')) {
      result++;
    }
  }
  return result;
}

// Is the given method parameter a reference?
bool Method::IsParamAReference(unsigned int param) const {
  CHECK_LT(param, NumArgs());
  if (IsStatic()) {
    param++;  // 0th argument must skip return value at start of the shorty
  } else if (param == 0) {
    return true;  // this argument
  }
  return GetShorty()->CharAt(param) == 'L';
}

// Is the given method parameter a long or double?
bool Method::IsParamALongOrDouble(unsigned int param) const {
  CHECK_LT(param, NumArgs());
  if (IsStatic()) {
    param++;  // 0th argument must skip return value at start of the shorty
  } else if (param == 0) {
    return false;  // this argument
  }
  char ch = GetShorty()->CharAt(param);
  return (ch == 'J' || ch == 'D');
}

static size_t ShortyCharToSize(char x) {
  switch (x) {
    case 'V': return 0;
    case '[': return kPointerSize;
    case 'L': return kPointerSize;
    case 'D': return 8;
    case 'J': return 8;
    default:  return 4;
  }
}

size_t Method::ParamSize(unsigned int param) const {
  CHECK_LT(param, NumArgs());
  if (IsStatic()) {
    param++;  // 0th argument must skip return value at start of the shorty
  } else if (param == 0) {
    return kPointerSize;  // this argument
  }
  return ShortyCharToSize(GetShorty()->CharAt(param));
}

size_t Method::ReturnSize() const {
  return ShortyCharToSize(GetShorty()->CharAt(0));
}

bool Method::HasSameNameAndDescriptor(const Method* that) const {
  return (this->GetName()->Equals(that->GetName()) &&
          this->GetSignature()->Equals(that->GetSignature()));
}

void Method::SetCode(ByteArray* code_array, InstructionSet instruction_set,
                     ByteArray* mapping_table) {
  CHECK(GetCode() == NULL || IsNative());
  SetFieldPtr<ByteArray*>(OFFSET_OF_OBJECT_MEMBER(Method, code_array_), code_array, false);
  SetFieldPtr<ByteArray*>(OFFSET_OF_OBJECT_MEMBER(Method, mapping_table_),
       mapping_table, false);
  int8_t* code = code_array->GetData();
  uintptr_t address = reinterpret_cast<uintptr_t>(code);
  if (instruction_set == kThumb2) {
    // Set the low-order bit so a BLX will switch to Thumb mode
    address |= 0x1;
  }
  SetFieldPtr<const void*>(OFFSET_OF_OBJECT_MEMBER(Method, code_), reinterpret_cast<const void*>(address), false);
}

void Method::SetInvokeStub(const ByteArray* invoke_stub_array) {
  const InvokeStub* invoke_stub = reinterpret_cast<InvokeStub*>(invoke_stub_array->GetData());
  SetFieldPtr<const ByteArray*>(
      OFFSET_OF_OBJECT_MEMBER(Method, invoke_stub_array_), invoke_stub_array, false);
  SetFieldPtr<const InvokeStub*>(
      OFFSET_OF_OBJECT_MEMBER(Method, invoke_stub_), invoke_stub, false);
}

void Method::Invoke(Thread* self, Object* receiver, byte* args, JValue* result) const {
  // Push a transition back into managed code onto the linked list in thread.
  CHECK_EQ(Thread::kRunnable, self->GetState());
  NativeToManagedRecord record;
  self->PushNativeToManagedRecord(&record);

  // Call the invoke stub associated with the method.
  // Pass everything as arguments.
  const Method::InvokeStub* stub = GetInvokeStub();

  bool have_executable_code = (GetCode() != NULL);
#if !defined(__arm__)
  // Currently we can only compile non-native methods for ARM.
  have_executable_code = IsNative();
#endif

  if (have_executable_code && stub != NULL) {
    LOG(INFO) << "invoking " << PrettyMethod(this) << " code=" << (void*) GetCode() << " stub=" << (void*) stub;
    (*stub)(this, receiver, self, args, result);
  } else {
    LOG(WARNING) << "Not invoking method with no associated code: " << PrettyMethod(this);
    if (result != NULL) {
      result->j = 0;
    }
  }

  // Pop transition.
  self->PopNativeToManagedRecord(record);
}

void Class::SetStatus(Status new_status) {
  CHECK(new_status > GetStatus() || new_status == kStatusError ||
      !Runtime::Current()->IsStarted());
  CHECK(sizeof(Status) == sizeof(uint32_t));
  return SetField32(OFFSET_OF_OBJECT_MEMBER(Class, status_),
                    new_status, false);
}

DexCache* Class::GetDexCache() const {
  return GetFieldObject<DexCache*>(
      OFFSET_OF_OBJECT_MEMBER(Class, dex_cache_), false);
}

void Class::SetDexCache(DexCache* new_dex_cache) {
  SetFieldObject(OFFSET_OF_OBJECT_MEMBER(Class, dex_cache_),
                 new_dex_cache, false);
}

Object* Class::AllocObjectFromCode(uint32_t type_idx, Method* method) {
  Class* klass = method->GetDexCacheResolvedTypes()->Get(type_idx);
  if (klass == NULL) {
    klass = Runtime::Current()->GetClassLinker()->ResolveType(type_idx, method);
    if (klass == NULL) {
      UNIMPLEMENTED(FATAL) << "throw an error";
      return NULL;
    }
  }
  return klass->AllocObject();
}

Object* Class::AllocObject() {
  DCHECK(!IsAbstract());
  return Heap::AllocObject(this, this->object_size_);
}

void Class::SetReferenceInstanceOffsets(uint32_t new_reference_offsets) {
  if (new_reference_offsets != CLASS_WALK_SUPER) {
    // Sanity check that the number of bits set in the reference offset bitmap
    // agrees with the number of references
    Class* cur = this;
    size_t cnt = 0;
    while (cur) {
      cnt += cur->NumReferenceInstanceFieldsDuringLinking();
      cur = cur->GetSuperClass();
    }
    CHECK_EQ((size_t)__builtin_popcount(new_reference_offsets), cnt);
  }
  SetField32(OFFSET_OF_OBJECT_MEMBER(Class, reference_instance_offsets_),
             new_reference_offsets, false);
}

void Class::SetReferenceStaticOffsets(uint32_t new_reference_offsets) {
  if (new_reference_offsets != CLASS_WALK_SUPER) {
    // Sanity check that the number of bits set in the reference offset bitmap
    // agrees with the number of references
    CHECK_EQ((size_t)__builtin_popcount(new_reference_offsets),
             NumReferenceStaticFieldsDuringLinking());
  }
  SetField32(OFFSET_OF_OBJECT_MEMBER(Class, reference_static_offsets_),
             new_reference_offsets, false);
}

size_t Class::PrimitiveSize() const {
  switch (GetPrimitiveType()) {
    case kPrimBoolean:
    case kPrimByte:
    case kPrimChar:
    case kPrimShort:
    case kPrimInt:
    case kPrimFloat:
      return sizeof(int32_t);
    case kPrimLong:
    case kPrimDouble:
      return sizeof(int64_t);
    default:
      LOG(FATAL) << "Primitive type size calculation on invalid type " << this;
      return 0;
  }
}

size_t Class::GetTypeSize(const String* descriptor) {
  switch (descriptor->CharAt(0)) {
  case 'B': return 1;  // byte
  case 'C': return 2;  // char
  case 'D': return 8;  // double
  case 'F': return 4;  // float
  case 'I': return 4;  // int
  case 'J': return 8;  // long
  case 'S': return 2;  // short
  case 'Z': return 1;  // boolean
  case 'L': return sizeof(Object*);
  case '[': return sizeof(Array*);
  default:
    LOG(ERROR) << "Unknown type " << descriptor;
    return 0;
  }
}

bool Class::Implements(const Class* klass) const {
  DCHECK(klass != NULL);
  DCHECK(klass->IsInterface());
  // All interfaces implemented directly and by our superclass, and
  // recursively all super-interfaces of those interfaces, are listed
  // in iftable_, so we can just do a linear scan through that.
  int32_t iftable_count = GetIfTableCount();
  ObjectArray<InterfaceEntry>* iftable = GetIfTable();
  for (int32_t i = 0; i < iftable_count; i++) {
    if (iftable->Get(i)->GetInterface() == klass) {
      return true;
    }
  }
  return false;
}

bool Class::CanPutArrayElement(const Class* object_class, const Class* array_class) {
  if (object_class->IsArrayClass()) {
    return array_class->IsArrayAssignableFromArray(object_class);
  } else {
    return array_class->GetComponentType()->IsAssignableFrom(object_class);
  }
}

void Class::CanPutArrayElementFromCode(const Class* object_class, const Class* array_class) {
  if (!CanPutArrayElement(object_class, array_class)) {
    LOG(ERROR) << "Can't put a " << PrettyDescriptor(object_class->GetDescriptor())
               << " into a " << PrettyDescriptor(array_class->GetDescriptor());
    UNIMPLEMENTED(FATAL) << "need to throw ArrayStoreException and unwind stack";
  }
}

// Determine whether "this" is assignable from "klazz", where both of these
// are array classes.
//
// Consider an array class, e.g. Y[][], where Y is a subclass of X.
//   Y[][]            = Y[][] --> true (identity)
//   X[][]            = Y[][] --> true (element superclass)
//   Y                = Y[][] --> false
//   Y[]              = Y[][] --> false
//   Object           = Y[][] --> true (everything is an object)
//   Object[]         = Y[][] --> true
//   Object[][]       = Y[][] --> true
//   Object[][][]     = Y[][] --> false (too many []s)
//   Serializable     = Y[][] --> true (all arrays are Serializable)
//   Serializable[]   = Y[][] --> true
//   Serializable[][] = Y[][] --> false (unless Y is Serializable)
//
// Don't forget about primitive types.
//   Object[]         = int[] --> false
//
bool Class::IsArrayAssignableFromArray(const Class* klass) const {
  DCHECK(IsArrayClass());
  DCHECK(klass->IsArrayClass());
  DCHECK_GT(GetArrayRank(), 0);
  DCHECK_GT(klass->GetArrayRank(), 0);
  DCHECK(GetComponentType() != NULL);
  DCHECK(klass->GetComponentType() != NULL);
  if (GetArrayRank() > klass->GetArrayRank()) {
    // Too many []s.
    return false;
  }
  if (GetArrayRank() == klass->GetArrayRank()) {
    return GetComponentType()->IsAssignableFrom(klass->GetComponentType());
  }
  DCHECK_LT(GetArrayRank(), klass->GetArrayRank());
  // The thing we might be assignable from has more dimensions.  We
  // must be an Object or array of Object, or a standard array
  // interface or array of standard array interfaces (the standard
  // interfaces being java/lang/Cloneable and java/io/Serializable).
  if (GetComponentType()->IsInterface()) {
    // See if we implement our component type.  We know the
    // base element is an interface; if the array class implements
    // it, we know it's a standard array interface.
    return Implements(GetComponentType());
  }
  // See if this is an array of Object, Object[], etc.
  return GetComponentType()->IsObjectClass();
}

bool Class::IsAssignableFromArray(const Class* klass) const {
  DCHECK(!IsInterface());  // handled first in IsAssignableFrom
  DCHECK(klass->IsArrayClass());
  if (!IsArrayClass()) {
    // If "this" is not also an array, it must be Object.
    // klass's super should be java_lang_Object, since it is an array.
    Class* java_lang_Object = klass->GetSuperClass();
    DCHECK(java_lang_Object != NULL);
    DCHECK(java_lang_Object->GetSuperClass() == NULL);
    return this == java_lang_Object;
  }
  return IsArrayAssignableFromArray(klass);
}

bool Class::IsSubClass(const Class* klass) const {
  DCHECK(!IsInterface());
  DCHECK(!klass->IsArrayClass());
  const Class* current = this;
  do {
    if (current == klass) {
      return true;
    }
    current = current->GetSuperClass();
  } while (current != NULL);
  return false;
}

bool Class::IsInSamePackage(const String* descriptor_string_1,
                            const String* descriptor_string_2) {
  const std::string descriptor1(descriptor_string_1->ToModifiedUtf8());
  const std::string descriptor2(descriptor_string_2->ToModifiedUtf8());

  size_t i = 0;
  while (descriptor1[i] != '\0' && descriptor1[i] == descriptor2[i]) {
    ++i;
  }
  if (descriptor1.find('/', i) != StringPiece::npos ||
      descriptor2.find('/', i) != StringPiece::npos) {
    return false;
  } else {
    return true;
  }
}

#if 0
bool Class::IsInSamePackage(const StringPiece& descriptor1,
                            const StringPiece& descriptor2) {
  size_t size = std::min(descriptor1.size(), descriptor2.size());
  std::pair<StringPiece::const_iterator, StringPiece::const_iterator> pos;
  pos = std::mismatch(descriptor1.begin(), descriptor1.begin() + size,
                      descriptor2.begin());
  return !(*(pos.second).rfind('/') != npos && descriptor2.rfind('/') != npos);
}
#endif

bool Class::IsInSamePackage(const Class* that) const {
  const Class* klass1 = this;
  const Class* klass2 = that;
  if (klass1 == klass2) {
    return true;
  }
  // Class loaders must match.
  if (klass1->GetClassLoader() != klass2->GetClassLoader()) {
    return false;
  }
  // Arrays are in the same package when their element classes are.
  if (klass1->IsArrayClass()) {
    klass1 = klass1->GetComponentType();
  }
  if (klass2->IsArrayClass()) {
    klass2 = klass2->GetComponentType();
  }
  // Compare the package part of the descriptor string.
  return IsInSamePackage(klass1->descriptor_, klass2->descriptor_);
}

const ClassLoader* Class::GetClassLoader() const {
  return GetFieldObject<const ClassLoader*>(
      OFFSET_OF_OBJECT_MEMBER(Class, class_loader_), false);
}

void Class::SetClassLoader(const ClassLoader* new_cl) {
  ClassLoader* new_class_loader = const_cast<ClassLoader*>(new_cl);
  SetFieldObject(OFFSET_OF_OBJECT_MEMBER(Class, class_loader_),
                 new_class_loader, false);
}

Method* Class::FindVirtualMethodForInterface(Method* method) {
  Class* declaring_class = method->GetDeclaringClass();
  DCHECK(declaring_class->IsInterface());
  // TODO cache to improve lookup speed
  int32_t iftable_count = GetIfTableCount();
  ObjectArray<InterfaceEntry>* iftable = GetIfTable();
  for (int32_t i = 0; i < iftable_count; i++) {
    InterfaceEntry* interface_entry = iftable->Get(i);
    if (interface_entry->GetInterface() == declaring_class) {
      return interface_entry->GetMethodArray()->Get(method->GetMethodIndex());
    }
  }
  UNIMPLEMENTED(FATAL) << "Need to throw an error of some kind";
  return NULL;
}

Method* Class::FindInterfaceMethod(const StringPiece& name,
                                   const StringPiece& signature) {
  // Check the current class before checking the interfaces.
  Method* method = FindVirtualMethod(name, signature);
  if (method != NULL) {
    return method;
  }

  int32_t iftable_count = GetIfTableCount();
  ObjectArray<InterfaceEntry>* iftable = GetIfTable();
  for (int32_t i = 0; i < iftable_count; i++) {
    method = iftable->Get(i)->GetInterface()->FindVirtualMethod(name, signature);
    if (method != NULL) {
      return method;
    }
  }
  return NULL;
}

Method* Class::FindDeclaredDirectMethod(const StringPiece& name,
                                        const StringPiece& signature) {
  for (size_t i = 0; i < NumDirectMethods(); ++i) {
    Method* method = GetDirectMethod(i);
    if (method->GetName()->Equals(name) &&
        method->GetSignature()->Equals(signature)) {
      return method;
    }
  }
  return NULL;
}

Method* Class::FindDirectMethod(const StringPiece& name,
                                const StringPiece& signature) {
  for (Class* klass = this; klass != NULL; klass = klass->GetSuperClass()) {
    Method* method = klass->FindDeclaredDirectMethod(name, signature);
    if (method != NULL) {
      return method;
    }
  }
  return NULL;
}

Method* Class::FindDeclaredVirtualMethod(const StringPiece& name,
                                         const StringPiece& signature) {
  for (size_t i = 0; i < NumVirtualMethods(); ++i) {
    Method* method = GetVirtualMethod(i);
    if (method->GetName()->Equals(name) &&
        method->GetSignature()->Equals(signature)) {
      return method;
    }
  }
  return NULL;
}

Method* Class::FindVirtualMethod(const StringPiece& name,
                                 const StringPiece& descriptor) {
  for (Class* klass = this; klass != NULL; klass = klass->GetSuperClass()) {
    Method* method = klass->FindDeclaredVirtualMethod(name, descriptor);
    if (method != NULL) {
      return method;
    }
  }
  return NULL;
}

Field* Class::FindDeclaredInstanceField(const StringPiece& name, Class* type) {
  // Is the field in this class?
  // Interfaces are not relevant because they can't contain instance fields.
  for (size_t i = 0; i < NumInstanceFields(); ++i) {
    Field* f = GetInstanceField(i);
    if (f->GetName()->Equals(name) && type == f->GetType()) {
      return f;
    }
  }
  return NULL;
}

Field* Class::FindInstanceField(const StringPiece& name, Class* type) {
  // Is the field in this class, or any of its superclasses?
  // Interfaces are not relevant because they can't contain instance fields.
  for (Class* c = this; c != NULL; c = c->GetSuperClass()) {
    Field* f = c->FindDeclaredInstanceField(name, type);
    if (f != NULL) {
      return f;
    }
  }
  return NULL;
}

Field* Class::FindDeclaredStaticField(const StringPiece& name, Class* type) {
  DCHECK(type != NULL);
  for (size_t i = 0; i < NumStaticFields(); ++i) {
    Field* f = GetStaticField(i);
    if (f->GetName()->Equals(name) && f->GetType() == type) {
      return f;
    }
  }
  return NULL;
}

Field* Class::FindStaticField(const StringPiece& name, Class* type) {
  // Is the field in this class (or its interfaces), or any of its
  // superclasses (or their interfaces)?
  for (Class* c = this; c != NULL; c = c->GetSuperClass()) {
    // Is the field in this class?
    Field* f = c->FindDeclaredStaticField(name, type);
    if (f != NULL) {
      return f;
    }

    // Is this field in any of this class' interfaces?
    for (size_t i = 0; i < c->NumInterfaces(); ++i) {
      Class* interface = c->GetInterface(i);
      f = interface->FindDeclaredStaticField(name, type);
      if (f != NULL) {
        return f;
      }
    }
  }
  return NULL;
}

Array* Array::Alloc(Class* array_class, int32_t component_count, size_t component_size) {
  DCHECK(array_class != NULL);
  DCHECK_GE(component_count, 0);
  DCHECK(array_class->IsArrayClass());
  size_t size = SizeOf(component_count, component_size);
  Array* array = down_cast<Array*>(Heap::AllocObject(array_class, size));
  if (array != NULL) {
    DCHECK(array->IsArrayInstance());
    array->SetLength(component_count);
  }
  return array;
}

Array* Array::Alloc(Class* array_class, int32_t component_count) {
  return Alloc(array_class, component_count, array_class->GetComponentSize());
}

Array* Array::AllocFromCode(uint32_t type_idx, Method* method, int32_t component_count) {
  // TODO: throw on negative component_count
  Class* klass = method->GetDexCacheResolvedTypes()->Get(type_idx);
  if (klass == NULL) {
    klass = Runtime::Current()->GetClassLinker()->ResolveType(type_idx, method);
    if (klass == NULL || !klass->IsArrayClass()) {
      UNIMPLEMENTED(FATAL) << "throw an error";
      return NULL;
    }
  }
  return Array::Alloc(klass, component_count);
}

template<typename T>
PrimitiveArray<T>* PrimitiveArray<T>::Alloc(size_t length) {
  DCHECK(array_class_ != NULL);
  Array* raw_array = Array::Alloc(array_class_, length, sizeof(T));
  return down_cast<PrimitiveArray<T>*>(raw_array);
}

template <typename T> Class* PrimitiveArray<T>::array_class_ = NULL;

// Explicitly instantiate all the primitive array types.
template class PrimitiveArray<uint8_t>;   // BooleanArray
template class PrimitiveArray<int8_t>;    // ByteArray
template class PrimitiveArray<uint16_t>;  // CharArray
template class PrimitiveArray<double>;    // DoubleArray
template class PrimitiveArray<float>;     // FloatArray
template class PrimitiveArray<int32_t>;   // IntArray
template class PrimitiveArray<int64_t>;   // LongArray
template class PrimitiveArray<int16_t>;   // ShortArray

// TODO: get global references for these
Class* String::java_lang_String_ = NULL;

void String::SetClass(Class* java_lang_String) {
  CHECK(java_lang_String_ == NULL);
  CHECK(java_lang_String != NULL);
  java_lang_String_ = java_lang_String;
}

void String::ResetClass() {
  CHECK(java_lang_String_ != NULL);
  java_lang_String_ = NULL;
}

String* String::Intern() {
  return Runtime::Current()->GetInternTable()->InternWeak(this);
}

int32_t String::GetHashCode() const {
  int32_t result = GetField32(
      OFFSET_OF_OBJECT_MEMBER(String, hash_code_), false);
  DCHECK(result != 0 ||
         ComputeUtf16Hash(GetCharArray(), GetOffset(), GetLength()) == 0);
  return result;
}

int32_t String::GetLength() const {
  int32_t result = GetField32(OFFSET_OF_OBJECT_MEMBER(String, count_), false);
  DCHECK(result >= 0 && result <= GetCharArray()->GetLength());
  return result;
}

uint16_t String::CharAt(int32_t index) const {
  // TODO: do we need this? Equals is the only caller, and could
  // bounds check itself.
  if (index < 0 || index >= count_) {
    Thread* self = Thread::Current();
    self->ThrowNewException("Ljava/lang/StringIndexOutOfBoundsException;",
        "length=%i; index=%i", count_, index);
    return 0;
  }
  return GetCharArray()->Get(index + GetOffset());
}

String* String::AllocFromUtf16(int32_t utf16_length,
                               const uint16_t* utf16_data_in,
                               int32_t hash_code) {
  String* string = Alloc(GetJavaLangString(), utf16_length);
  // TODO: use 16-bit wide memset variant
  CharArray* array = const_cast<CharArray*>(string->GetCharArray());
  for (int i = 0; i < utf16_length; i++) {
    array->Set(i, utf16_data_in[i]);
  }
  if (hash_code != 0) {
    string->SetHashCode(hash_code);
  } else {
    string->ComputeHashCode();
  }
  return string;
}

String* String::AllocFromModifiedUtf8(const char* utf) {
  size_t char_count = CountModifiedUtf8Chars(utf);
  return AllocFromModifiedUtf8(char_count, utf);
}

String* String::AllocFromModifiedUtf8(int32_t utf16_length,
                                      const char* utf8_data_in) {
  String* string = Alloc(GetJavaLangString(), utf16_length);
  uint16_t* utf16_data_out =
      const_cast<uint16_t*>(string->GetCharArray()->GetData());
  ConvertModifiedUtf8ToUtf16(utf16_data_out, utf8_data_in);
  string->ComputeHashCode();
  return string;
}

String* String::Alloc(Class* java_lang_String, int32_t utf16_length) {
  return Alloc(java_lang_String, CharArray::Alloc(utf16_length));
}

String* String::Alloc(Class* java_lang_String, CharArray* array) {
  String* string = down_cast<String*>(java_lang_String->AllocObject());
  string->SetArray(array);
  string->SetCount(array->GetLength());
  return string;
}

bool String::Equals(const String* that) const {
  if (this == that) {
    // Quick reference equality test
    return true;
  } else if (that == NULL) {
    // Null isn't an instanceof anything
    return false;
  } else if (this->GetLength() != that->GetLength()) {
    // Quick length inequality test
    return false;
  } else {
    // NB don't short circuit on hash code as we're presumably here as the
    // hash code was already equal
    for (int32_t i = 0; i < that->GetLength(); ++i) {
      if (this->CharAt(i) != that->CharAt(i)) {
        return false;
      }
    }
    return true;
  }
}

bool String::Equals(const uint16_t* that_chars, int32_t that_offset,
                    int32_t that_length) const {
  if (this->GetLength() != that_length) {
    return false;
  } else {
    for (int32_t i = 0; i < that_length; ++i) {
      if (this->CharAt(i) != that_chars[that_offset + i]) {
        return false;
      }
    }
    return true;
  }
}

bool String::Equals(const char* modified_utf8) const {
  for (int32_t i = 0; i < GetLength(); ++i) {
    uint16_t ch = GetUtf16FromUtf8(&modified_utf8);
    if (ch == '\0' || ch != CharAt(i)) {
      return false;
    }
  }
  return *modified_utf8 == '\0';
}

bool String::Equals(const StringPiece& modified_utf8) const {
  // TODO: do not assume C-string representation. For now DCHECK.
  DCHECK_EQ(modified_utf8.data()[modified_utf8.size()], 0);
  return Equals(modified_utf8.data());
}

// Create a modified UTF-8 encoded std::string from a java/lang/String object.
std::string String::ToModifiedUtf8() const {
  const uint16_t* chars = GetCharArray()->GetData() + GetOffset();
  size_t byte_count(CountUtf8Bytes(chars, GetLength()));
  std::string result(byte_count, char(0));
  ConvertUtf16ToModifiedUtf8(&result[0], chars, GetLength());
  return result;
}

Class* StackTraceElement::java_lang_StackTraceElement_ = NULL;

void StackTraceElement::SetClass(Class* java_lang_StackTraceElement) {
  CHECK(java_lang_StackTraceElement_ == NULL);
  CHECK(java_lang_StackTraceElement != NULL);
  java_lang_StackTraceElement_ = java_lang_StackTraceElement;
}

void StackTraceElement::ResetClass() {
  CHECK(java_lang_StackTraceElement_ != NULL);
  java_lang_StackTraceElement_ = NULL;
}

StackTraceElement* StackTraceElement::Alloc(const String* declaring_class,
                                            const String* method_name,
                                            const String* file_name,
                                            int32_t line_number) {
  StackTraceElement* trace =
      down_cast<StackTraceElement*>(GetStackTraceElement()->AllocObject());
  trace->SetFieldObject(OFFSET_OF_OBJECT_MEMBER(StackTraceElement, declaring_class_),
                        const_cast<String*>(declaring_class), false);
  trace->SetFieldObject(OFFSET_OF_OBJECT_MEMBER(StackTraceElement, method_name_),
                        const_cast<String*>(method_name), false);
  trace->SetFieldObject(OFFSET_OF_OBJECT_MEMBER(StackTraceElement, file_name_),
                        const_cast<String*>(file_name), false);
  trace->SetField32(OFFSET_OF_OBJECT_MEMBER(StackTraceElement, line_number_),
                    line_number, false);
  return trace;
}

static const char* kClassStatusNames[] = {
  "Error",
  "NotReady",
  "Idx",
  "Loaded",
  "Resolved",
  "Verifying",
  "Verified",
  "Initializing",
  "Initialized"
};
std::ostream& operator<<(std::ostream& os, const Class::Status& rhs) {
  if (rhs >= Class::kStatusError && rhs <= Class::kStatusInitialized) {
    os << kClassStatusNames[rhs + 1];
  } else {
    os << "Class::Status[" << static_cast<int>(rhs) << "]";
  }
  return os;
}

}  // namespace art