runtime/vm/object.cc

// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

#include "vm/object.h"

#include "include/dart_api.h"
#include "platform/assert.h"
#include "vm/become.h"
#include "vm/bit_vector.h"
#include "vm/bootstrap.h"
#include "vm/class_finalizer.h"
#include "vm/code_observers.h"
#include "vm/compiler/aot/precompiler.h"
#include "vm/compiler/assembler/assembler.h"
#include "vm/compiler/assembler/disassembler.h"
#include "vm/compiler/frontend/kernel_binary_flowgraph.h"
#include "vm/compiler/frontend/kernel_to_il.h"
#include "vm/compiler/intrinsifier.h"
#include "vm/compiler/jit/compiler.h"
#include "vm/compiler_stats.h"
#include "vm/cpu.h"
#include "vm/dart.h"
#include "vm/dart_api_state.h"
#include "vm/dart_entry.h"
#include "vm/datastream.h"
#include "vm/debugger.h"
#include "vm/deopt_instructions.h"
#include "vm/double_conversion.h"
#include "vm/exceptions.h"
#include "vm/growable_array.h"
#include "vm/hash_table.h"
#include "vm/heap.h"
#include "vm/isolate_reload.h"
#include "vm/kernel.h"
#include "vm/native_symbol.h"
#include "vm/object_store.h"
#include "vm/parser.h"
#include "vm/profiler.h"
#include "vm/resolver.h"
#include "vm/reusable_handles.h"
#include "vm/runtime_entry.h"
#include "vm/scopes.h"
#include "vm/stack_frame.h"
#include "vm/symbols.h"
#include "vm/tags.h"
#include "vm/thread_registry.h"
#include "vm/timeline.h"
#include "vm/timer.h"
#include "vm/type_table.h"
#include "vm/unicode.h"
#include "vm/weak_code.h"
#include "vm/zone_text_buffer.h"

namespace dart {

DEFINE_FLAG(int,
            huge_method_cutoff_in_code_size,
            200000,
            "Huge method cutoff in unoptimized code size (in bytes).");
DEFINE_FLAG(
    bool,
    overlap_type_arguments,
    true,
    "When possible, partially or fully overlap the type arguments of a type "
    "with the type arguments of its super type.");
DEFINE_FLAG(
    bool,
    show_internal_names,
    false,
    "Show names of internal classes (e.g. \"OneByteString\") in error messages "
    "instead of showing the corresponding interface names (e.g. \"String\")");
DEFINE_FLAG(bool, use_lib_cache, true, "Use library name cache");
DEFINE_FLAG(bool, use_exp_cache, true, "Use library exported name cache");

DEFINE_FLAG(bool,
            remove_script_timestamps_for_test,
            false,
            "Remove script timestamps to allow for deterministic testing.");

DECLARE_FLAG(bool, show_invisible_frames);
DECLARE_FLAG(bool, trace_deoptimization);
DECLARE_FLAG(bool, trace_deoptimization_verbose);
DECLARE_FLAG(bool, trace_reload);
DECLARE_FLAG(bool, write_protect_code);

static const char* const kGetterPrefix = "get:";
static const intptr_t kGetterPrefixLength = strlen(kGetterPrefix);
static const char* const kSetterPrefix = "set:";
static const intptr_t kSetterPrefixLength = strlen(kSetterPrefix);

// A cache of VM heap allocated preinitialized empty ic data entry arrays.
RawArray* ICData::cached_icdata_arrays_[kCachedICDataArrayCount];

cpp_vtable Object::handle_vtable_ = 0;
cpp_vtable Object::builtin_vtables_[kNumPredefinedCids] = {0};
cpp_vtable Smi::handle_vtable_ = 0;

// These are initialized to a value that will force a illegal memory access if
// they are being used.
#if defined(RAW_NULL)
#error RAW_NULL should not be defined.
#endif
#define RAW_NULL kHeapObjectTag
Object* Object::null_object_ = NULL;
Array* Object::null_array_ = NULL;
String* Object::null_string_ = NULL;
Instance* Object::null_instance_ = NULL;
Function* Object::null_function_ = NULL;
TypeArguments* Object::null_type_arguments_ = NULL;
Array* Object::empty_array_ = NULL;
Array* Object::zero_array_ = NULL;
Context* Object::empty_context_ = NULL;
ContextScope* Object::empty_context_scope_ = NULL;
ObjectPool* Object::empty_object_pool_ = NULL;
PcDescriptors* Object::empty_descriptors_ = NULL;
LocalVarDescriptors* Object::empty_var_descriptors_ = NULL;
ExceptionHandlers* Object::empty_exception_handlers_ = NULL;
Array* Object::extractor_parameter_types_ = NULL;
Array* Object::extractor_parameter_names_ = NULL;
Instance* Object::sentinel_ = NULL;
Instance* Object::transition_sentinel_ = NULL;
Instance* Object::unknown_constant_ = NULL;
Instance* Object::non_constant_ = NULL;
Bool* Object::bool_true_ = NULL;
Bool* Object::bool_false_ = NULL;
Smi* Object::smi_illegal_cid_ = NULL;
LanguageError* Object::snapshot_writer_error_ = NULL;
LanguageError* Object::branch_offset_error_ = NULL;
LanguageError* Object::speculative_inlining_error_ = NULL;
LanguageError* Object::background_compilation_error_ = NULL;
Array* Object::vm_isolate_snapshot_object_table_ = NULL;
Type* Object::dynamic_type_ = NULL;
Type* Object::void_type_ = NULL;
Type* Object::vector_type_ = NULL;

RawObject* Object::null_ = reinterpret_cast<RawObject*>(RAW_NULL);
RawClass* Object::class_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::dynamic_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::vector_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::void_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::unresolved_class_class_ =
    reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::type_arguments_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::patch_class_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::function_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::closure_data_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::signature_data_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::redirection_data_class_ =
    reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::field_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::literal_token_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::token_stream_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::script_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::library_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::namespace_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::kernel_program_info_class_ =
    reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::code_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::instructions_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::object_pool_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::pc_descriptors_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::code_source_map_class_ =
    reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::stackmap_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::var_descriptors_class_ =
    reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::exception_handlers_class_ =
    reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::context_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::context_scope_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::singletargetcache_class_ =
    reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::unlinkedcall_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::icdata_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::megamorphic_cache_class_ =
    reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::subtypetestcache_class_ =
    reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::api_error_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::language_error_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::unhandled_exception_class_ =
    reinterpret_cast<RawClass*>(RAW_NULL);
RawClass* Object::unwind_error_class_ = reinterpret_cast<RawClass*>(RAW_NULL);

const double MegamorphicCache::kLoadFactor = 0.50;

static void AppendSubString(Zone* zone,
                            GrowableArray<const char*>* segments,
                            const char* name,
                            intptr_t start_pos,
                            intptr_t len) {
  char* segment = zone->Alloc<char>(len + 1);  // '\0'-terminated.
  memmove(segment, name + start_pos, len);
  segment[len] = '\0';
  segments->Add(segment);
}

static const char* MergeSubStrings(Zone* zone,
                                   const GrowableArray<const char*>& segments,
                                   intptr_t alloc_len) {
  char* result = zone->Alloc<char>(alloc_len + 1);  // '\0'-terminated
  intptr_t pos = 0;
  for (intptr_t k = 0; k < segments.length(); k++) {
    const char* piece = segments[k];
    const intptr_t piece_len = strlen(segments[k]);
    memmove(result + pos, piece, piece_len);
    pos += piece_len;
    ASSERT(pos <= alloc_len);
  }
  result[pos] = '\0';
  return result;
}

// Remove private keys, but retain getter/setter/constructor/mixin manglings.
RawString* String::RemovePrivateKey(const String& name) {
  ASSERT(name.IsOneByteString());
  GrowableArray<uint8_t> without_key(name.Length());
  intptr_t i = 0;
  while (i < name.Length()) {
    while (i < name.Length()) {
      uint8_t c = name.CharAt(i++);
      if (c == '@') break;
      without_key.Add(c);
    }
    while (i < name.Length()) {
      uint8_t c = name.CharAt(i);
      if ((c < '0') || (c > '9')) break;
      i++;
    }
  }

  return String::FromLatin1(without_key.data(), without_key.length());
}

// Takes a vm internal name and makes it suitable for external user.
//
// Examples:
//
// Internal getter and setter prefixes are changed:
//
//   get:foo -> foo
//   set:foo -> foo=
//
// Private name mangling is removed, possibly multiple times:
//
//   _ReceivePortImpl@709387912 -> _ReceivePortImpl
//   _ReceivePortImpl@709387912._internal@709387912 ->
//      _ReceivePortImpl._internal
//   _C@6328321&_E@6328321&_F@6328321 -> _C&_E&_F
//
// The trailing . on the default constructor name is dropped:
//
//   List. -> List
//
// And so forth:
//
//   get:foo@6328321 -> foo
//   _MyClass@6328321. -> _MyClass
//   _MyClass@6328321.named -> _MyClass.named
//
RawString* String::ScrubName(const String& name) {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();

#if !defined(DART_PRECOMPILED_RUNTIME)
  if (name.Equals(Symbols::TopLevel())) {
    // Name of invisible top-level class.
    return Symbols::Empty().raw();
  }
#endif  // !defined(DART_PRECOMPILED_RUNTIME)

  const char* cname = name.ToCString();
  ASSERT(strlen(cname) == static_cast<size_t>(name.Length()));
  const intptr_t name_len = name.Length();
  // First remove all private name mangling.
  intptr_t start_pos = 0;
  GrowableArray<const char*> unmangled_segments;
  intptr_t sum_segment_len = 0;
  for (intptr_t i = 0; i < name_len; i++) {
    if ((cname[i] == '@') && ((i + 1) < name_len) && (cname[i + 1] >= '0') &&
        (cname[i + 1] <= '9')) {
      // Append the current segment to the unmangled name.
      const intptr_t segment_len = i - start_pos;
      sum_segment_len += segment_len;
      AppendSubString(zone, &unmangled_segments, cname, start_pos, segment_len);
      // Advance until past the name mangling. The private keys are only
      // numbers so we skip until the first non-number.
      i++;  // Skip the '@'.
      while ((i < name.Length()) && (name.CharAt(i) >= '0') &&
             (name.CharAt(i) <= '9')) {
        i++;
      }
      start_pos = i;
      i--;  // Account for for-loop increment.
    }
  }

  const char* unmangled_name = NULL;
  if (start_pos == 0) {
    // No name unmangling needed, reuse the name that was passed in.
    unmangled_name = cname;
    sum_segment_len = name_len;
  } else if (name.Length() != start_pos) {
    // Append the last segment.
    const intptr_t segment_len = name.Length() - start_pos;
    sum_segment_len += segment_len;
    AppendSubString(zone, &unmangled_segments, cname, start_pos, segment_len);
  }
  if (unmangled_name == NULL) {
    // Merge unmangled_segments.
    unmangled_name = MergeSubStrings(zone, unmangled_segments, sum_segment_len);
  }

#if !defined(DART_PRECOMPILED_RUNTIME)
  intptr_t len = sum_segment_len;
  intptr_t start = 0;
  intptr_t dot_pos = -1;  // Position of '.' in the name, if any.
  bool is_setter = false;
  for (intptr_t i = start; i < len; i++) {
    if (unmangled_name[i] == ':') {
      if (start != 0) {
        // Reset and break.
        start = 0;
        dot_pos = -1;
        break;
      }
      ASSERT(start == 0);  // Only one : is possible in getters or setters.
      if (unmangled_name[0] == 's') {
        is_setter = true;
      }
      start = i + 1;
    } else if (unmangled_name[i] == '.') {
      if (dot_pos != -1) {
        // Reset and break.
        start = 0;
        dot_pos = -1;
        break;
      }
      ASSERT(dot_pos == -1);  // Only one dot is supported.
      dot_pos = i;
    }
  }

  if ((start == 0) && (dot_pos == -1)) {
    // This unmangled_name is fine as it is.
    return Symbols::New(thread, unmangled_name, sum_segment_len);
  }

  // Drop the trailing dot if needed.
  intptr_t end = ((dot_pos + 1) == len) ? dot_pos : len;

  unmangled_segments.Clear();
  intptr_t final_len = end - start;
  AppendSubString(zone, &unmangled_segments, unmangled_name, start, final_len);
  if (is_setter) {
    const char* equals = Symbols::Equals().ToCString();
    const intptr_t equals_len = strlen(equals);
    AppendSubString(zone, &unmangled_segments, equals, 0, equals_len);
    final_len += equals_len;
  }

  unmangled_name = MergeSubStrings(zone, unmangled_segments, final_len);
#endif  // !defined(DART_PRECOMPILED_RUNTIME)

  return Symbols::New(thread, unmangled_name);
}

RawString* String::ScrubNameRetainPrivate(const String& name) {
#if !defined(DART_PRECOMPILED_RUNTIME)
  intptr_t len = name.Length();
  intptr_t start = 0;
  intptr_t at_pos = -1;  // Position of '@' in the name, if any.
  bool is_setter = false;

  for (intptr_t i = start; i < len; i++) {
    if (name.CharAt(i) == ':') {
      ASSERT(start == 0);  // Only one : is possible in getters or setters.
      if (name.CharAt(0) == 's') {
        is_setter = true;
      }
      start = i + 1;
    } else if (name.CharAt(i) == '@') {
      // Setters should have only one @ so we know where to put the =.
      ASSERT(!is_setter || (at_pos == -1));
      at_pos = i;
    }
  }

  if (start == 0) {
    // This unmangled_name is fine as it is.
    return name.raw();
  }

  String& result =
      String::Handle(String::SubString(name, start, (len - start)));

  if (is_setter) {
    // Setters need to end with '='.
    if (at_pos == -1) {
      return String::Concat(result, Symbols::Equals());
    } else {
      const String& pre_at =
          String::Handle(String::SubString(result, 0, at_pos - 4));
      const String& post_at =
          String::Handle(String::SubString(name, at_pos, len - at_pos));
      result = String::Concat(pre_at, Symbols::Equals());
      result = String::Concat(result, post_at);
    }
  }

  return result.raw();
#endif                // !defined(DART_PRECOMPILED_RUNTIME)
  return name.raw();  // In AOT, return argument unchanged.
}

template <typename type>
static bool IsSpecialCharacter(type value) {
  return ((value == '"') || (value == '\n') || (value == '\f') ||
          (value == '\b') || (value == '\t') || (value == '\v') ||
          (value == '\r') || (value == '\\') || (value == '$'));
}

static inline bool IsAsciiNonprintable(int32_t c) {
  return ((0 <= c) && (c < 32)) || (c == 127);
}

static inline bool NeedsEscapeSequence(int32_t c) {
  return (c == '"') || (c == '\\') || (c == '$') || IsAsciiNonprintable(c);
}

static int32_t EscapeOverhead(int32_t c) {
  if (IsSpecialCharacter(c)) {
    return 1;  // 1 additional byte for the backslash.
  } else if (IsAsciiNonprintable(c)) {
    return 3;  // 3 additional bytes to encode c as \x00.
  }
  return 0;
}

template <typename type>
static type SpecialCharacter(type value) {
  if (value == '"') {
    return '"';
  } else if (value == '\n') {
    return 'n';
  } else if (value == '\f') {
    return 'f';
  } else if (value == '\b') {
    return 'b';
  } else if (value == '\t') {
    return 't';
  } else if (value == '\v') {
    return 'v';
  } else if (value == '\r') {
    return 'r';
  } else if (value == '\\') {
    return '\\';
  } else if (value == '$') {
    return '$';
  }
  UNREACHABLE();
  return '\0';
}

void Object::InitNull(Isolate* isolate) {
  // Should only be run by the vm isolate.
  ASSERT(isolate == Dart::vm_isolate());

  // TODO(iposva): NoSafepointScope needs to be added here.
  ASSERT(class_class() == null_);

  Heap* heap = isolate->heap();

  // Allocate and initialize the null instance.
  // 'null_' must be the first object allocated as it is used in allocation to
  // clear the object.
  {
    uword address = heap->Allocate(Instance::InstanceSize(), Heap::kOld);
    null_ = reinterpret_cast<RawInstance*>(address + kHeapObjectTag);
    // The call below is using 'null_' to initialize itself.
    InitializeObject(address, kNullCid, Instance::InstanceSize(), true);
  }
}

void Object::InitOnce(Isolate* isolate) {
  // Should only be run by the vm isolate.
  ASSERT(isolate == Dart::vm_isolate());

  // Initialize the static vtable values.
  {
    Object fake_object;
    Smi fake_smi;
    Object::handle_vtable_ = fake_object.vtable();
    Smi::handle_vtable_ = fake_smi.vtable();
  }

  Heap* heap = isolate->heap();

  // Allocate the read only object handles here.
  null_object_ = Object::ReadOnlyHandle();
  null_array_ = Array::ReadOnlyHandle();
  null_string_ = String::ReadOnlyHandle();
  null_instance_ = Instance::ReadOnlyHandle();
  null_function_ = Function::ReadOnlyHandle();
  null_type_arguments_ = TypeArguments::ReadOnlyHandle();
  empty_array_ = Array::ReadOnlyHandle();
  zero_array_ = Array::ReadOnlyHandle();
  empty_context_ = Context::ReadOnlyHandle();
  empty_context_scope_ = ContextScope::ReadOnlyHandle();
  empty_object_pool_ = ObjectPool::ReadOnlyHandle();
  empty_descriptors_ = PcDescriptors::ReadOnlyHandle();
  empty_var_descriptors_ = LocalVarDescriptors::ReadOnlyHandle();
  empty_exception_handlers_ = ExceptionHandlers::ReadOnlyHandle();
  extractor_parameter_types_ = Array::ReadOnlyHandle();
  extractor_parameter_names_ = Array::ReadOnlyHandle();
  sentinel_ = Instance::ReadOnlyHandle();
  transition_sentinel_ = Instance::ReadOnlyHandle();
  unknown_constant_ = Instance::ReadOnlyHandle();
  non_constant_ = Instance::ReadOnlyHandle();
  bool_true_ = Bool::ReadOnlyHandle();
  bool_false_ = Bool::ReadOnlyHandle();
  smi_illegal_cid_ = Smi::ReadOnlyHandle();
  snapshot_writer_error_ = LanguageError::ReadOnlyHandle();
  branch_offset_error_ = LanguageError::ReadOnlyHandle();
  speculative_inlining_error_ = LanguageError::ReadOnlyHandle();
  background_compilation_error_ = LanguageError::ReadOnlyHandle();
  vm_isolate_snapshot_object_table_ = Array::ReadOnlyHandle();
  dynamic_type_ = Type::ReadOnlyHandle();
  void_type_ = Type::ReadOnlyHandle();
  vector_type_ = Type::ReadOnlyHandle();

  *null_object_ = Object::null();
  *null_array_ = Array::null();
  *null_string_ = String::null();
  *null_instance_ = Instance::null();
  *null_function_ = Function::null();
  *null_type_arguments_ = TypeArguments::null();

  // Initialize the empty and zero array handles to null_ in order to be able to
  // check if the empty and zero arrays were allocated (RAW_NULL is not
  // available).
  *empty_array_ = Array::null();
  *zero_array_ = Array::null();

  Class& cls = Class::Handle();

  // Allocate and initialize the class class.
  {
    intptr_t size = Class::InstanceSize();
    uword address = heap->Allocate(size, Heap::kOld);
    class_class_ = reinterpret_cast<RawClass*>(address + kHeapObjectTag);
    InitializeObject(address, Class::kClassId, size, true);

    Class fake;
    // Initialization from Class::New<Class>.
    // Directly set raw_ to break a circular dependency: SetRaw will attempt
    // to lookup class class in the class table where it is not registered yet.
    cls.raw_ = class_class_;
    cls.set_handle_vtable(fake.vtable());
    cls.set_instance_size(Class::InstanceSize());
    cls.set_next_field_offset(Class::NextFieldOffset());
    cls.set_id(Class::kClassId);
    cls.set_state_bits(0);
    cls.set_is_finalized();
    cls.set_is_type_finalized();
    cls.set_is_cycle_free();
    cls.set_type_arguments_field_offset_in_words(Class::kNoTypeArguments);
    cls.set_num_type_arguments(0);
    cls.set_num_own_type_arguments(0);
    cls.set_num_native_fields(0);
    cls.InitEmptyFields();
    isolate->RegisterClass(cls);
  }

  // Allocate and initialize the null class.
  cls = Class::New<Instance>(kNullCid);
  cls.set_num_type_arguments(0);
  cls.set_num_own_type_arguments(0);
  isolate->object_store()->set_null_class(cls);

  // Allocate and initialize the free list element class.
  cls = Class::New<FreeListElement::FakeInstance>(kFreeListElement);
  cls.set_num_type_arguments(0);
  cls.set_num_own_type_arguments(0);
  cls.set_is_finalized();
  cls.set_is_type_finalized();
  cls.set_is_cycle_free();

  // Allocate and initialize the forwarding corpse class.
  cls = Class::New<ForwardingCorpse::FakeInstance>(kForwardingCorpse);
  cls.set_num_type_arguments(0);
  cls.set_num_own_type_arguments(0);
  cls.set_is_finalized();
  cls.set_is_type_finalized();
  cls.set_is_cycle_free();

  // Allocate and initialize the sentinel values of Null class.
  {
    *sentinel_ ^=
        Object::Allocate(kNullCid, Instance::InstanceSize(), Heap::kOld);

    *transition_sentinel_ ^=
        Object::Allocate(kNullCid, Instance::InstanceSize(), Heap::kOld);
  }

  // Allocate and initialize optimizing compiler constants.
  {
    *unknown_constant_ ^=
        Object::Allocate(kNullCid, Instance::InstanceSize(), Heap::kOld);
    *non_constant_ ^=
        Object::Allocate(kNullCid, Instance::InstanceSize(), Heap::kOld);
  }

  // Allocate the remaining VM internal classes.
  cls = Class::New<UnresolvedClass>();
  unresolved_class_class_ = cls.raw();

  cls = Class::New<TypeArguments>();
  type_arguments_class_ = cls.raw();

  cls = Class::New<PatchClass>();
  patch_class_class_ = cls.raw();

  cls = Class::New<Function>();
  function_class_ = cls.raw();

  cls = Class::New<ClosureData>();
  closure_data_class_ = cls.raw();

  cls = Class::New<SignatureData>();
  signature_data_class_ = cls.raw();

  cls = Class::New<RedirectionData>();
  redirection_data_class_ = cls.raw();

  cls = Class::New<Field>();
  field_class_ = cls.raw();

  cls = Class::New<LiteralToken>();
  literal_token_class_ = cls.raw();

  cls = Class::New<TokenStream>();
  token_stream_class_ = cls.raw();

  cls = Class::New<Script>();
  script_class_ = cls.raw();

  cls = Class::New<Library>();
  library_class_ = cls.raw();

  cls = Class::New<Namespace>();
  namespace_class_ = cls.raw();

  cls = Class::New<KernelProgramInfo>();
  kernel_program_info_class_ = cls.raw();

  cls = Class::New<Code>();
  code_class_ = cls.raw();

  cls = Class::New<Instructions>();
  instructions_class_ = cls.raw();

  cls = Class::New<ObjectPool>();
  object_pool_class_ = cls.raw();

  cls = Class::New<PcDescriptors>();
  pc_descriptors_class_ = cls.raw();

  cls = Class::New<CodeSourceMap>();
  code_source_map_class_ = cls.raw();

  cls = Class::New<StackMap>();
  stackmap_class_ = cls.raw();

  cls = Class::New<LocalVarDescriptors>();
  var_descriptors_class_ = cls.raw();

  cls = Class::New<ExceptionHandlers>();
  exception_handlers_class_ = cls.raw();

  cls = Class::New<Context>();
  context_class_ = cls.raw();

  cls = Class::New<ContextScope>();
  context_scope_class_ = cls.raw();

  cls = Class::New<SingleTargetCache>();
  singletargetcache_class_ = cls.raw();

  cls = Class::New<UnlinkedCall>();
  unlinkedcall_class_ = cls.raw();

  cls = Class::New<ICData>();
  icdata_class_ = cls.raw();

  cls = Class::New<MegamorphicCache>();
  megamorphic_cache_class_ = cls.raw();

  cls = Class::New<SubtypeTestCache>();
  subtypetestcache_class_ = cls.raw();

  cls = Class::New<ApiError>();
  api_error_class_ = cls.raw();

  cls = Class::New<LanguageError>();
  language_error_class_ = cls.raw();

  cls = Class::New<UnhandledException>();
  unhandled_exception_class_ = cls.raw();

  cls = Class::New<UnwindError>();
  unwind_error_class_ = cls.raw();

  ASSERT(class_class() != null_);

  // Pre-allocate classes in the vm isolate so that we can for example create a
  // symbol table and populate it with some frequently used strings as symbols.
  cls = Class::New<Array>();
  isolate->object_store()->set_array_class(cls);
  cls.set_type_arguments_field_offset(Array::type_arguments_offset());
  cls.set_num_type_arguments(1);
  cls.set_num_own_type_arguments(1);
  cls = Class::New<Array>(kImmutableArrayCid);
  isolate->object_store()->set_immutable_array_class(cls);
  cls.set_type_arguments_field_offset(Array::type_arguments_offset());
  cls.set_num_type_arguments(1);
  cls.set_num_own_type_arguments(1);
  cls = Class::New<GrowableObjectArray>();
  isolate->object_store()->set_growable_object_array_class(cls);
  cls.set_type_arguments_field_offset(
      GrowableObjectArray::type_arguments_offset());
  cls.set_num_type_arguments(1);
  cls = Class::NewStringClass(kOneByteStringCid);
  isolate->object_store()->set_one_byte_string_class(cls);
  cls = Class::NewStringClass(kTwoByteStringCid);
  isolate->object_store()->set_two_byte_string_class(cls);
  cls = Class::New<Mint>();
  isolate->object_store()->set_mint_class(cls);
  cls = Class::New<Bigint>();
  isolate->object_store()->set_bigint_class(cls);
  cls = Class::New<Double>();
  isolate->object_store()->set_double_class(cls);

  // Ensure that class kExternalTypedDataUint8ArrayCid is registered as we
  // need it when reading in the token stream of bootstrap classes in the VM
  // isolate.
  Class::NewExternalTypedDataClass(kExternalTypedDataUint8ArrayCid);

  // Needed for object pools of VM isolate stubs.
  Class::NewTypedDataClass(kTypedDataInt8ArrayCid);

  // Allocate and initialize the empty_array instance.
  {
    uword address = heap->Allocate(Array::InstanceSize(0), Heap::kOld);
    InitializeObject(address, kImmutableArrayCid, Array::InstanceSize(0), true);
    Array::initializeHandle(
        empty_array_, reinterpret_cast<RawArray*>(address + kHeapObjectTag));
    empty_array_->StoreSmi(&empty_array_->raw_ptr()->length_, Smi::New(0));
    empty_array_->SetCanonical();
  }

  Smi& smi = Smi::Handle();
  // Allocate and initialize the zero_array instance.
  {
    uword address = heap->Allocate(Array::InstanceSize(1), Heap::kOld);
    InitializeObject(address, kImmutableArrayCid, Array::InstanceSize(1), true);
    Array::initializeHandle(
        zero_array_, reinterpret_cast<RawArray*>(address + kHeapObjectTag));
    zero_array_->StoreSmi(&zero_array_->raw_ptr()->length_, Smi::New(1));
    smi = Smi::New(0);
    zero_array_->SetAt(0, smi);
    zero_array_->SetCanonical();
  }

  // Allocate and initialize the empty context object.
  {
    uword address = heap->Allocate(Context::InstanceSize(0), Heap::kOld);
    InitializeObject(address, kContextCid, Context::InstanceSize(0), true);
    Context::initializeHandle(empty_context_, reinterpret_cast<RawContext*>(
                                                  address + kHeapObjectTag));
    empty_context_->StoreNonPointer(&empty_context_->raw_ptr()->num_variables_,
                                    0);
    empty_context_->SetCanonical();
  }

  // Allocate and initialize the canonical empty context scope object.
  {
    uword address = heap->Allocate(ContextScope::InstanceSize(0), Heap::kOld);
    InitializeObject(address, kContextScopeCid, ContextScope::InstanceSize(0),
                     true);
    ContextScope::initializeHandle(
        empty_context_scope_,
        reinterpret_cast<RawContextScope*>(address + kHeapObjectTag));
    empty_context_scope_->StoreNonPointer(
        &empty_context_scope_->raw_ptr()->num_variables_, 0);
    empty_context_scope_->StoreNonPointer(
        &empty_context_scope_->raw_ptr()->is_implicit_, true);
    empty_context_scope_->SetCanonical();
  }

  // Allocate and initialize the canonical empty object pool object.
  {
    uword address = heap->Allocate(ObjectPool::InstanceSize(0), Heap::kOld);
    InitializeObject(address, kObjectPoolCid, ObjectPool::InstanceSize(0),
                     true);
    ObjectPool::initializeHandle(
        empty_object_pool_,
        reinterpret_cast<RawObjectPool*>(address + kHeapObjectTag));
    empty_object_pool_->StoreNonPointer(&empty_object_pool_->raw_ptr()->length_,
                                        0);
    empty_object_pool_->SetCanonical();
  }

  // Allocate and initialize the empty_descriptors instance.
  {
    uword address = heap->Allocate(PcDescriptors::InstanceSize(0), Heap::kOld);
    InitializeObject(address, kPcDescriptorsCid, PcDescriptors::InstanceSize(0),
                     true);
    PcDescriptors::initializeHandle(
        empty_descriptors_,
        reinterpret_cast<RawPcDescriptors*>(address + kHeapObjectTag));
    empty_descriptors_->StoreNonPointer(&empty_descriptors_->raw_ptr()->length_,
                                        0);
    empty_descriptors_->SetCanonical();
  }

  // Allocate and initialize the canonical empty variable descriptor object.
  {
    uword address =
        heap->Allocate(LocalVarDescriptors::InstanceSize(0), Heap::kOld);
    InitializeObject(address, kLocalVarDescriptorsCid,
                     LocalVarDescriptors::InstanceSize(0), true);
    LocalVarDescriptors::initializeHandle(
        empty_var_descriptors_,
        reinterpret_cast<RawLocalVarDescriptors*>(address + kHeapObjectTag));
    empty_var_descriptors_->StoreNonPointer(
        &empty_var_descriptors_->raw_ptr()->num_entries_, 0);
    empty_var_descriptors_->SetCanonical();
  }

  // Allocate and initialize the canonical empty exception handler info object.
  // The vast majority of all functions do not contain an exception handler
  // and can share this canonical descriptor.
  {
    uword address =
        heap->Allocate(ExceptionHandlers::InstanceSize(0), Heap::kOld);
    InitializeObject(address, kExceptionHandlersCid,
                     ExceptionHandlers::InstanceSize(0), true);
    ExceptionHandlers::initializeHandle(
        empty_exception_handlers_,
        reinterpret_cast<RawExceptionHandlers*>(address + kHeapObjectTag));
    empty_exception_handlers_->StoreNonPointer(
        &empty_exception_handlers_->raw_ptr()->num_entries_, 0);
    empty_exception_handlers_->SetCanonical();
  }

  // The VM isolate snapshot object table is initialized to an empty array
  // as we do not have any VM isolate snapshot at this time.
  *vm_isolate_snapshot_object_table_ = Object::empty_array().raw();

  cls = Class::New<Instance>(kDynamicCid);
  cls.set_is_abstract();
  cls.set_num_type_arguments(0);
  cls.set_num_own_type_arguments(0);
  cls.set_is_finalized();
  cls.set_is_type_finalized();
  cls.set_is_cycle_free();
  dynamic_class_ = cls.raw();

  cls = Class::New<Instance>(kVoidCid);
  cls.set_num_type_arguments(0);
  cls.set_num_own_type_arguments(0);
  cls.set_is_finalized();
  cls.set_is_type_finalized();
  cls.set_is_cycle_free();
  void_class_ = cls.raw();

  cls = Class::New<Instance>(kVectorCid);
  cls.set_num_type_arguments(0);
  cls.set_num_own_type_arguments(0);
  cls.set_is_finalized();
  cls.set_is_type_finalized();
  cls.set_is_cycle_free();
  vector_class_ = cls.raw();

  cls = Class::New<Type>();
  cls.set_is_finalized();
  cls.set_is_type_finalized();
  cls.set_is_cycle_free();

  cls = dynamic_class_;
  *dynamic_type_ = Type::NewNonParameterizedType(cls);

  cls = void_class_;
  *void_type_ = Type::NewNonParameterizedType(cls);

  cls = vector_class_;
  *vector_type_ = Type::NewNonParameterizedType(cls);

  // Since TypeArguments objects are passed as function arguments, make them
  // behave as Dart instances, although they are just VM objects.
  // Note that we cannot set the super type to ObjectType, which does not live
  // in the vm isolate. See special handling in Class::SuperClass().
  cls = type_arguments_class_;
  cls.set_interfaces(Object::empty_array());
  cls.SetFields(Object::empty_array());
  cls.SetFunctions(Object::empty_array());

  // Allocate and initialize singleton true and false boolean objects.
  cls = Class::New<Bool>();
  isolate->object_store()->set_bool_class(cls);
  *bool_true_ = Bool::New(true);
  *bool_false_ = Bool::New(false);

  *smi_illegal_cid_ = Smi::New(kIllegalCid);

  String& error_str = String::Handle();
  error_str = String::New("SnapshotWriter Error", Heap::kOld);
  *snapshot_writer_error_ =
      LanguageError::New(error_str, Report::kError, Heap::kOld);
  error_str = String::New("Branch offset overflow", Heap::kOld);
  *branch_offset_error_ =
      LanguageError::New(error_str, Report::kBailout, Heap::kOld);
  error_str = String::New("Speculative inlining failed", Heap::kOld);
  *speculative_inlining_error_ =
      LanguageError::New(error_str, Report::kBailout, Heap::kOld);
  error_str = String::New("Background Compilation Failed", Heap::kOld);
  *background_compilation_error_ =
      LanguageError::New(error_str, Report::kBailout, Heap::kOld);

  // Some thread fields need to be reinitialized as null constants have not been
  // initialized until now.
  Thread* thr = Thread::Current();
  ASSERT(thr != NULL);
  thr->clear_sticky_error();
  thr->clear_pending_functions();

  ASSERT(!null_object_->IsSmi());
  ASSERT(!null_array_->IsSmi());
  ASSERT(null_array_->IsArray());
  ASSERT(!null_string_->IsSmi());
  ASSERT(null_string_->IsString());
  ASSERT(!null_instance_->IsSmi());
  ASSERT(null_instance_->IsInstance());
  ASSERT(!null_function_->IsSmi());
  ASSERT(null_function_->IsFunction());
  ASSERT(!null_type_arguments_->IsSmi());
  ASSERT(null_type_arguments_->IsTypeArguments());
  ASSERT(!empty_array_->IsSmi());
  ASSERT(empty_array_->IsArray());
  ASSERT(!zero_array_->IsSmi());
  ASSERT(zero_array_->IsArray());
  ASSERT(!empty_context_->IsSmi());
  ASSERT(empty_context_->IsContext());
  ASSERT(!empty_context_scope_->IsSmi());
  ASSERT(empty_context_scope_->IsContextScope());
  ASSERT(!empty_descriptors_->IsSmi());
  ASSERT(empty_descriptors_->IsPcDescriptors());
  ASSERT(!empty_var_descriptors_->IsSmi());
  ASSERT(empty_var_descriptors_->IsLocalVarDescriptors());
  ASSERT(!empty_exception_handlers_->IsSmi());
  ASSERT(empty_exception_handlers_->IsExceptionHandlers());
  ASSERT(!sentinel_->IsSmi());
  ASSERT(sentinel_->IsInstance());
  ASSERT(!transition_sentinel_->IsSmi());
  ASSERT(transition_sentinel_->IsInstance());
  ASSERT(!unknown_constant_->IsSmi());
  ASSERT(unknown_constant_->IsInstance());
  ASSERT(!non_constant_->IsSmi());
  ASSERT(non_constant_->IsInstance());
  ASSERT(!bool_true_->IsSmi());
  ASSERT(bool_true_->IsBool());
  ASSERT(!bool_false_->IsSmi());
  ASSERT(bool_false_->IsBool());
  ASSERT(smi_illegal_cid_->IsSmi());
  ASSERT(!snapshot_writer_error_->IsSmi());
  ASSERT(snapshot_writer_error_->IsLanguageError());
  ASSERT(!branch_offset_error_->IsSmi());
  ASSERT(branch_offset_error_->IsLanguageError());
  ASSERT(!speculative_inlining_error_->IsSmi());
  ASSERT(speculative_inlining_error_->IsLanguageError());
  ASSERT(!background_compilation_error_->IsSmi());
  ASSERT(background_compilation_error_->IsLanguageError());
  ASSERT(!vm_isolate_snapshot_object_table_->IsSmi());
  ASSERT(vm_isolate_snapshot_object_table_->IsArray());
}

// An object visitor which will mark all visited objects. This is used to
// premark all objects in the vm_isolate_ heap.  Also precalculates hash
// codes so that we can get the identity hash code of objects in the read-
// only VM isolate.
class FinalizeVMIsolateVisitor : public ObjectVisitor {
 public:
  FinalizeVMIsolateVisitor()
#if defined(HASH_IN_OBJECT_HEADER)
      : counter_(1337)
#endif
  {
  }

  void VisitObject(RawObject* obj) {
    // Free list elements should never be marked.
    ASSERT(!obj->IsMarked());
    // No forwarding corpses in the VM isolate.
    ASSERT(!obj->IsForwardingCorpse());
    if (!obj->IsFreeListElement()) {
      ASSERT(obj->IsVMHeapObject());
      obj->SetMarkBitUnsynchronized();
      if (obj->IsStringInstance()) {
        RawString* str = reinterpret_cast<RawString*>(obj);
        intptr_t hash = String::Hash(str);
        String::SetCachedHash(str, hash);
      }
#if defined(HASH_IN_OBJECT_HEADER)
      // These objects end up in the read-only VM isolate which is shared
      // between isolates, so we have to prepopulate them with identity hash
      // codes, since we can't add hash codes later.
      if (Object::GetCachedHash(obj) == 0) {
        // Some classes have identity hash codes that depend on their contents,
        // not per object.
        ASSERT(!obj->IsStringInstance());
        if (!obj->IsMint() && !obj->IsDouble() && !obj->IsBigint() &&
            !obj->IsRawNull() && !obj->IsBool()) {
          counter_ += 2011;  // The year Dart was announced and a prime.
          counter_ &= 0x3fffffff;
          if (counter_ == 0) counter_++;
          Object::SetCachedHash(obj, counter_);
        }
      }
#endif
    }
  }

 private:
#if defined(HASH_IN_OBJECT_HEADER)
  int32_t counter_;
#endif
};

#define SET_CLASS_NAME(class_name, name)                                       \
  cls = class_name##_class();                                                  \
  cls.set_name(Symbols::name());

void Object::FinalizeVMIsolate(Isolate* isolate) {
  // Should only be run by the vm isolate.
  ASSERT(isolate == Dart::vm_isolate());

  // Allocate the parameter arrays for method extractor types and names.
  *extractor_parameter_types_ = Array::New(1, Heap::kOld);
  extractor_parameter_types_->SetAt(0, Object::dynamic_type());
  *extractor_parameter_names_ = Array::New(1, Heap::kOld);
  extractor_parameter_names_->SetAt(0, Symbols::This());

  ASSERT(!extractor_parameter_types_->IsSmi());
  ASSERT(extractor_parameter_types_->IsArray());
  ASSERT(!extractor_parameter_names_->IsSmi());
  ASSERT(extractor_parameter_names_->IsArray());

  // Set up names for all VM singleton classes.
  Class& cls = Class::Handle();

  SET_CLASS_NAME(class, Class);
  SET_CLASS_NAME(dynamic, Dynamic);
  SET_CLASS_NAME(void, Void);
  SET_CLASS_NAME(unresolved_class, UnresolvedClass);
  SET_CLASS_NAME(type_arguments, TypeArguments);
  SET_CLASS_NAME(patch_class, PatchClass);
  SET_CLASS_NAME(function, Function);
  SET_CLASS_NAME(closure_data, ClosureData);
  SET_CLASS_NAME(signature_data, SignatureData);
  SET_CLASS_NAME(redirection_data, RedirectionData);
  SET_CLASS_NAME(field, Field);
  SET_CLASS_NAME(literal_token, LiteralToken);
  SET_CLASS_NAME(token_stream, TokenStream);
  SET_CLASS_NAME(script, Script);
  SET_CLASS_NAME(library, LibraryClass);
  SET_CLASS_NAME(namespace, Namespace);
  SET_CLASS_NAME(kernel_program_info, KernelProgramInfo);
  SET_CLASS_NAME(code, Code);
  SET_CLASS_NAME(instructions, Instructions);
  SET_CLASS_NAME(object_pool, ObjectPool);
  SET_CLASS_NAME(code_source_map, CodeSourceMap);
  SET_CLASS_NAME(pc_descriptors, PcDescriptors);
  SET_CLASS_NAME(stackmap, StackMap);
  SET_CLASS_NAME(var_descriptors, LocalVarDescriptors);
  SET_CLASS_NAME(exception_handlers, ExceptionHandlers);
  SET_CLASS_NAME(context, Context);
  SET_CLASS_NAME(context_scope, ContextScope);
  SET_CLASS_NAME(singletargetcache, SingleTargetCache);
  SET_CLASS_NAME(unlinkedcall, UnlinkedCall);
  SET_CLASS_NAME(icdata, ICData);
  SET_CLASS_NAME(megamorphic_cache, MegamorphicCache);
  SET_CLASS_NAME(subtypetestcache, SubtypeTestCache);
  SET_CLASS_NAME(api_error, ApiError);
  SET_CLASS_NAME(language_error, LanguageError);
  SET_CLASS_NAME(unhandled_exception, UnhandledException);
  SET_CLASS_NAME(unwind_error, UnwindError);

  // Set up names for object array and one byte string class which are
  // pre-allocated in the vm isolate also.
  cls = isolate->object_store()->array_class();
  cls.set_name(Symbols::_List());
  cls = isolate->object_store()->one_byte_string_class();
  cls.set_name(Symbols::OneByteString());

  // Set up names for the pseudo-classes for free list elements and forwarding
  // corpses. Mainly this makes VM debugging easier.
  cls = isolate->class_table()->At(kFreeListElement);
  cls.set_name(Symbols::FreeListElement());
  cls = isolate->class_table()->At(kForwardingCorpse);
  cls.set_name(Symbols::ForwardingCorpse());

  {
    ASSERT(isolate == Dart::vm_isolate());
    Thread* thread = Thread::Current();
    WritableVMIsolateScope scope(thread);
    HeapIterationScope iteration(thread);
    FinalizeVMIsolateVisitor premarker;
    ASSERT(isolate->heap()->UsedInWords(Heap::kNew) == 0);
    iteration.IterateOldObjectsNoImagePages(&premarker);
    // Make the VM isolate read-only again after setting all objects as marked.
    // Note objects in image pages are already pre-marked.
  }
}

void Object::set_vm_isolate_snapshot_object_table(const Array& table) {
  ASSERT(Isolate::Current() == Dart::vm_isolate());
  *vm_isolate_snapshot_object_table_ = table.raw();
}

// Make unused space in an object whose type has been transformed safe
// for traversing during GC.
// The unused part of the transformed object is marked as an TypedDataInt8Array
// object.
void Object::MakeUnusedSpaceTraversable(const Object& obj,
                                        intptr_t original_size,
                                        intptr_t used_size) {
  ASSERT(Thread::Current()->no_safepoint_scope_depth() > 0);
  ASSERT(!obj.IsNull());
  ASSERT(original_size >= used_size);
  if (original_size > used_size) {
    intptr_t leftover_size = original_size - used_size;

    uword addr = RawObject::ToAddr(obj.raw()) + used_size;
    if (leftover_size >= TypedData::InstanceSize(0)) {
      // Update the leftover space as a TypedDataInt8Array object.
      RawTypedData* raw =
          reinterpret_cast<RawTypedData*>(RawObject::FromAddr(addr));
      uword new_tags = RawObject::ClassIdTag::update(kTypedDataInt8ArrayCid, 0);
      new_tags = RawObject::SizeTag::update(leftover_size, new_tags);
      uint32_t tags = raw->ptr()->tags_;
      uint32_t old_tags;
      // TODO(iposva): Investigate whether CompareAndSwapWord is necessary.
      do {
        old_tags = tags;
        // We can't use obj.CompareAndSwapTags here because we don't have a
        // handle for the new object.
        tags = AtomicOperations::CompareAndSwapUint32(&raw->ptr()->tags_,
                                                      old_tags, new_tags);
      } while (tags != old_tags);

      intptr_t leftover_len = (leftover_size - TypedData::InstanceSize(0));
      ASSERT(TypedData::InstanceSize(leftover_len) == leftover_size);
      raw->StoreSmi(&(raw->ptr()->length_), Smi::New(leftover_len));
    } else {
      // Update the leftover space as a basic object.
      ASSERT(leftover_size == Object::InstanceSize());
      RawObject* raw = reinterpret_cast<RawObject*>(RawObject::FromAddr(addr));
      uword new_tags = RawObject::ClassIdTag::update(kInstanceCid, 0);
      new_tags = RawObject::SizeTag::update(leftover_size, new_tags);
      uint32_t tags = raw->ptr()->tags_;
      uint32_t old_tags;
      // TODO(iposva): Investigate whether CompareAndSwapWord is necessary.
      do {
        old_tags = tags;
        tags = obj.CompareAndSwapTags(old_tags, new_tags);
      } while (tags != old_tags);
    }
  }
}

void Object::VerifyBuiltinVtables() {
#if defined(DEBUG)
  Thread* thread = Thread::Current();
  Isolate* isolate = thread->isolate();
  Class& cls = Class::Handle(thread->zone(), Class::null());
  for (intptr_t cid = (kIllegalCid + 1); cid < kNumPredefinedCids; cid++) {
    if (isolate->class_table()->HasValidClassAt(cid)) {
      cls ^= isolate->class_table()->At(cid);
      ASSERT(builtin_vtables_[cid] == cls.raw_ptr()->handle_vtable_);
    }
  }
  ASSERT(builtin_vtables_[kFreeListElement] == 0);
  ASSERT(builtin_vtables_[kForwardingCorpse] == 0);
#endif
}

void Object::RegisterClass(const Class& cls,
                           const String& name,
                           const Library& lib) {
  ASSERT(name.Length() > 0);
  ASSERT(name.CharAt(0) != '_');
  cls.set_name(name);
  lib.AddClass(cls);
}

void Object::RegisterPrivateClass(const Class& cls,
                                  const String& public_class_name,
                                  const Library& lib) {
  ASSERT(public_class_name.Length() > 0);
  ASSERT(public_class_name.CharAt(0) == '_');
  String& str = String::Handle();
  str = lib.PrivateName(public_class_name);
  cls.set_name(str);
  lib.AddClass(cls);
}

// Initialize a new isolate from source or from a snapshot.
//
// There are three possibilities:
//   1. Running a Kernel binary.  This function will bootstrap from the KERNEL
//      file.
//   2. There is no snapshot.  This function will bootstrap from source.
//   3. There is a snapshot.  The caller should initialize from the snapshot.
//
// A non-NULL kernel argument indicates (1).  A NULL kernel indicates (2) or
// (3), depending on whether the VM is compiled with DART_NO_SNAPSHOT defined or
// not.
RawError* Object::Init(Isolate* isolate, kernel::Program* kernel_program) {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  ASSERT(isolate == thread->isolate());
#if !defined(DART_PRECOMPILED_RUNTIME)
  const bool is_kernel = (kernel_program != NULL);
#endif
  NOT_IN_PRODUCT(TimelineDurationScope tds(thread, Timeline::GetIsolateStream(),
                                           "Object::Init");)

#if defined(DART_NO_SNAPSHOT)
  bool bootstrapping = Dart::vm_snapshot_kind() == Snapshot::kNone;
#elif defined(DART_PRECOMPILED_RUNTIME)
  bool bootstrapping = false;
#else
  bool bootstrapping = is_kernel;
#endif

  if (bootstrapping) {
#if !defined(DART_PRECOMPILED_RUNTIME)
    // Object::Init version when we are bootstrapping from source or from a
    // Kernel binary.
    ObjectStore* object_store = isolate->object_store();

    Class& cls = Class::Handle(zone);
    Type& type = Type::Handle(zone);
    Array& array = Array::Handle(zone);
    Library& lib = Library::Handle(zone);
    TypeArguments& type_args = TypeArguments::Handle(zone);

    // All RawArray fields will be initialized to an empty array, therefore
    // initialize array class first.
    cls = Class::New<Array>();
    object_store->set_array_class(cls);

    // VM classes that are parameterized (Array, ImmutableArray,
    // GrowableObjectArray, and LinkedHashMap) are also pre-finalized, so
    // CalculateFieldOffsets() is not called, so we need to set the offset of
    // their type_arguments_ field, which is explicitly declared in their
    // respective Raw* classes.
    cls.set_type_arguments_field_offset(Array::type_arguments_offset());
    cls.set_num_type_arguments(1);

    // Set up the growable object array class (Has to be done after the array
    // class is setup as one of its field is an array object).
    cls = Class::New<GrowableObjectArray>();
    object_store->set_growable_object_array_class(cls);
    cls.set_type_arguments_field_offset(
        GrowableObjectArray::type_arguments_offset());
    cls.set_num_type_arguments(1);

    // Initialize hash set for canonical_type_.
    const intptr_t kInitialCanonicalTypeSize = 16;
    array = HashTables::New<CanonicalTypeSet>(kInitialCanonicalTypeSize,
                                              Heap::kOld);
    object_store->set_canonical_types(array);

    // Initialize hash set for canonical_type_arguments_.
    const intptr_t kInitialCanonicalTypeArgumentsSize = 4;
    array = HashTables::New<CanonicalTypeArgumentsSet>(
        kInitialCanonicalTypeArgumentsSize, Heap::kOld);
    object_store->set_canonical_type_arguments(array);

    // Setup type class early in the process.
    const Class& type_cls = Class::Handle(zone, Class::New<Type>());
    const Class& type_ref_cls = Class::Handle(zone, Class::New<TypeRef>());
    const Class& type_parameter_cls =
        Class::Handle(zone, Class::New<TypeParameter>());
    const Class& bounded_type_cls =
        Class::Handle(zone, Class::New<BoundedType>());
    const Class& mixin_app_type_cls =
        Class::Handle(zone, Class::New<MixinAppType>());
    const Class& library_prefix_cls =
        Class::Handle(zone, Class::New<LibraryPrefix>());

    // Pre-allocate the OneByteString class needed by the symbol table.
    cls = Class::NewStringClass(kOneByteStringCid);
    object_store->set_one_byte_string_class(cls);

    // Pre-allocate the TwoByteString class needed by the symbol table.
    cls = Class::NewStringClass(kTwoByteStringCid);
    object_store->set_two_byte_string_class(cls);

    // Setup the symbol table for the symbols created in the isolate.
    Symbols::SetupSymbolTable(isolate);

    // Set up the libraries array before initializing the core library.
    const GrowableObjectArray& libraries =
        GrowableObjectArray::Handle(zone, GrowableObjectArray::New(Heap::kOld));
    object_store->set_libraries(libraries);

    // Pre-register the core library.
    Library::InitCoreLibrary(isolate);

    // Basic infrastructure has been setup, initialize the class dictionary.
    const Library& core_lib = Library::Handle(zone, Library::CoreLibrary());
    ASSERT(!core_lib.IsNull());

    const GrowableObjectArray& pending_classes =
        GrowableObjectArray::Handle(zone, GrowableObjectArray::New());
    object_store->set_pending_classes(pending_classes);

    // Now that the symbol table is initialized and that the core dictionary as
    // well as the core implementation dictionary have been setup, preallocate
    // remaining classes and register them by name in the dictionaries.
    String& name = String::Handle(zone);
    cls = object_store->array_class();  // Was allocated above.
    RegisterPrivateClass(cls, Symbols::_List(), core_lib);
    pending_classes.Add(cls);
    // We cannot use NewNonParameterizedType(cls), because Array is
    // parameterized.  Warning: class _List has not been patched yet. Its
    // declared number of type parameters is still 0. It will become 1 after
    // patching. The array type allocated below represents the raw type _List
    // and not _List<E> as we could expect. Use with caution.
    type ^= Type::New(Object::Handle(zone, cls.raw()),
                      TypeArguments::Handle(zone), TokenPosition::kNoSource);
    type.SetIsFinalized();
    type ^= type.Canonicalize();
    object_store->set_array_type(type);

    cls = object_store->growable_object_array_class();  // Was allocated above.
    RegisterPrivateClass(cls, Symbols::_GrowableList(), core_lib);
    pending_classes.Add(cls);

    cls = Class::New<Array>(kImmutableArrayCid);
    object_store->set_immutable_array_class(cls);
    cls.set_type_arguments_field_offset(Array::type_arguments_offset());
    cls.set_num_type_arguments(1);
    ASSERT(object_store->immutable_array_class() !=
           object_store->array_class());
    cls.set_is_prefinalized();
    RegisterPrivateClass(cls, Symbols::_ImmutableList(), core_lib);
    pending_classes.Add(cls);

    cls = object_store->one_byte_string_class();  // Was allocated above.
    RegisterPrivateClass(cls, Symbols::OneByteString(), core_lib);
    pending_classes.Add(cls);

    cls = object_store->two_byte_string_class();  // Was allocated above.
    RegisterPrivateClass(cls, Symbols::TwoByteString(), core_lib);
    pending_classes.Add(cls);

    cls = Class::NewStringClass(kExternalOneByteStringCid);
    object_store->set_external_one_byte_string_class(cls);
    RegisterPrivateClass(cls, Symbols::ExternalOneByteString(), core_lib);
    pending_classes.Add(cls);

    cls = Class::NewStringClass(kExternalTwoByteStringCid);
    object_store->set_external_two_byte_string_class(cls);
    RegisterPrivateClass(cls, Symbols::ExternalTwoByteString(), core_lib);
    pending_classes.Add(cls);

    // Pre-register the isolate library so the native class implementations can
    // be hooked up before compiling it.
    Library& isolate_lib = Library::Handle(
        zone, Library::LookupLibrary(thread, Symbols::DartIsolate()));
    if (isolate_lib.IsNull()) {
      isolate_lib = Library::NewLibraryHelper(Symbols::DartIsolate(), true);
      isolate_lib.SetLoadRequested();
      isolate_lib.Register(thread);
    }
    object_store->set_bootstrap_library(ObjectStore::kIsolate, isolate_lib);
    ASSERT(!isolate_lib.IsNull());
    ASSERT(isolate_lib.raw() == Library::IsolateLibrary());

    cls = Class::New<Capability>();
    RegisterPrivateClass(cls, Symbols::_CapabilityImpl(), isolate_lib);
    pending_classes.Add(cls);

    cls = Class::New<ReceivePort>();
    RegisterPrivateClass(cls, Symbols::_RawReceivePortImpl(), isolate_lib);
    pending_classes.Add(cls);

    cls = Class::New<SendPort>();
    RegisterPrivateClass(cls, Symbols::_SendPortImpl(), isolate_lib);
    pending_classes.Add(cls);

    const Class& stacktrace_cls = Class::Handle(zone, Class::New<StackTrace>());
    RegisterPrivateClass(stacktrace_cls, Symbols::_StackTrace(), core_lib);
    pending_classes.Add(stacktrace_cls);
    // Super type set below, after Object is allocated.

    cls = Class::New<RegExp>();
    RegisterPrivateClass(cls, Symbols::_RegExp(), core_lib);
    pending_classes.Add(cls);

    // Initialize the base interfaces used by the core VM classes.

    // Allocate and initialize the pre-allocated classes in the core library.
    // The script and token index of these pre-allocated classes is set up in
    // the parser when the corelib script is compiled (see
    // Parser::ParseClassDefinition).
    cls = Class::New<Instance>(kInstanceCid);
    object_store->set_object_class(cls);
    cls.set_name(Symbols::Object());
    cls.set_num_type_arguments(0);
    cls.set_num_own_type_arguments(0);
    cls.set_is_prefinalized();
    core_lib.AddClass(cls);
    pending_classes.Add(cls);
    type = Type::NewNonParameterizedType(cls);
    object_store->set_object_type(type);

    cls = Class::New<Bool>();
    object_store->set_bool_class(cls);
    RegisterClass(cls, Symbols::Bool(), core_lib);
    pending_classes.Add(cls);

    cls = Class::New<Instance>(kNullCid);
    object_store->set_null_class(cls);
    cls.set_num_type_arguments(0);
    cls.set_num_own_type_arguments(0);
    cls.set_is_prefinalized();
    RegisterClass(cls, Symbols::Null(), core_lib);
    pending_classes.Add(cls);

    ASSERT(!library_prefix_cls.IsNull());
    RegisterPrivateClass(library_prefix_cls, Symbols::_LibraryPrefix(),
                         core_lib);
    pending_classes.Add(library_prefix_cls);

    RegisterPrivateClass(type_cls, Symbols::_Type(), core_lib);
    pending_classes.Add(type_cls);

    RegisterPrivateClass(type_ref_cls, Symbols::_TypeRef(), core_lib);
    pending_classes.Add(type_ref_cls);

    RegisterPrivateClass(type_parameter_cls, Symbols::_TypeParameter(),
                         core_lib);
    pending_classes.Add(type_parameter_cls);

    RegisterPrivateClass(bounded_type_cls, Symbols::_BoundedType(), core_lib);
    pending_classes.Add(bounded_type_cls);

    RegisterPrivateClass(mixin_app_type_cls, Symbols::_MixinAppType(),
                         core_lib);
    pending_classes.Add(mixin_app_type_cls);

    cls = Class::New<Integer>();
    object_store->set_integer_implementation_class(cls);
    RegisterPrivateClass(cls, Symbols::_IntegerImplementation(), core_lib);
    pending_classes.Add(cls);

    cls = Class::New<Smi>();
    object_store->set_smi_class(cls);
    RegisterPrivateClass(cls, Symbols::_Smi(), core_lib);
    pending_classes.Add(cls);

    cls = Class::New<Mint>();
    object_store->set_mint_class(cls);
    RegisterPrivateClass(cls, Symbols::_Mint(), core_lib);
    pending_classes.Add(cls);

    cls = Class::New<Bigint>();
    object_store->set_bigint_class(cls);
    RegisterPrivateClass(cls, Symbols::_Bigint(), core_lib);
    pending_classes.Add(cls);

    cls = Class::New<Double>();
    object_store->set_double_class(cls);
    RegisterPrivateClass(cls, Symbols::_Double(), core_lib);
    pending_classes.Add(cls);

    // Class that represents the Dart class _Closure and C++ class Closure.
    cls = Class::New<Closure>();
    object_store->set_closure_class(cls);
    cls.ResetFinalization();  // To calculate field offsets from Dart source.
    RegisterPrivateClass(cls, Symbols::_Closure(), core_lib);
    pending_classes.Add(cls);

    cls = Class::New<WeakProperty>();
    object_store->set_weak_property_class(cls);
    RegisterPrivateClass(cls, Symbols::_WeakProperty(), core_lib);

// Pre-register the mirrors library so we can place the vm class
// MirrorReference there rather than the core library.
#if !defined(DART_PRECOMPILED_RUNTIME)
    lib = Library::LookupLibrary(thread, Symbols::DartMirrors());
    if (lib.IsNull()) {
      lib = Library::NewLibraryHelper(Symbols::DartMirrors(), true);
      lib.SetLoadRequested();
      lib.Register(thread);
    }
    object_store->set_bootstrap_library(ObjectStore::kMirrors, lib);
    ASSERT(!lib.IsNull());
    ASSERT(lib.raw() == Library::MirrorsLibrary());

    cls = Class::New<MirrorReference>();
    RegisterPrivateClass(cls, Symbols::_MirrorReference(), lib);
#endif

    // Pre-register the collection library so we can place the vm class
    // LinkedHashMap there rather than the core library.
    lib = Library::LookupLibrary(thread, Symbols::DartCollection());
    if (lib.IsNull()) {
      lib = Library::NewLibraryHelper(Symbols::DartCollection(), true);
      lib.SetLoadRequested();
      lib.Register(thread);
    }

    object_store->set_bootstrap_library(ObjectStore::kCollection, lib);
    ASSERT(!lib.IsNull());
    ASSERT(lib.raw() == Library::CollectionLibrary());
    cls = Class::New<LinkedHashMap>();
    object_store->set_linked_hash_map_class(cls);
    cls.set_type_arguments_field_offset(LinkedHashMap::type_arguments_offset());
    cls.set_num_type_arguments(2);
    cls.set_num_own_type_arguments(0);
    RegisterPrivateClass(cls, Symbols::_LinkedHashMap(), lib);
    pending_classes.Add(cls);

    // Pre-register the developer library so we can place the vm class
    // UserTag there rather than the core library.
    lib = Library::LookupLibrary(thread, Symbols::DartDeveloper());
    if (lib.IsNull()) {
      lib = Library::NewLibraryHelper(Symbols::DartDeveloper(), true);
      lib.SetLoadRequested();
      lib.Register(thread);
    }
    object_store->set_bootstrap_library(ObjectStore::kDeveloper, lib);
    ASSERT(!lib.IsNull());
    ASSERT(lib.raw() == Library::DeveloperLibrary());
    cls = Class::New<UserTag>();
    RegisterPrivateClass(cls, Symbols::_UserTag(), lib);
    pending_classes.Add(cls);

    // Setup some default native field classes which can be extended for
    // specifying native fields in dart classes.
    Library::InitNativeWrappersLibrary(isolate, is_kernel);
    ASSERT(object_store->native_wrappers_library() != Library::null());

    // Pre-register the typed_data library so the native class implementations
    // can be hooked up before compiling it.
    lib = Library::LookupLibrary(thread, Symbols::DartTypedData());
    if (lib.IsNull()) {
      lib = Library::NewLibraryHelper(Symbols::DartTypedData(), true);
      lib.SetLoadRequested();
      lib.Register(thread);
    }
    object_store->set_bootstrap_library(ObjectStore::kTypedData, lib);
    ASSERT(!lib.IsNull());
    ASSERT(lib.raw() == Library::TypedDataLibrary());
#define REGISTER_TYPED_DATA_CLASS(clazz)                                       \
  cls = Class::NewTypedDataClass(kTypedData##clazz##ArrayCid);                 \
  RegisterPrivateClass(cls, Symbols::_##clazz##List(), lib);

    DART_CLASS_LIST_TYPED_DATA(REGISTER_TYPED_DATA_CLASS);
#undef REGISTER_TYPED_DATA_CLASS
#define REGISTER_TYPED_DATA_VIEW_CLASS(clazz)                                  \
  cls = Class::NewTypedDataViewClass(kTypedData##clazz##ViewCid);              \
  RegisterPrivateClass(cls, Symbols::_##clazz##View(), lib);                   \
  pending_classes.Add(cls);

    CLASS_LIST_TYPED_DATA(REGISTER_TYPED_DATA_VIEW_CLASS);
    cls = Class::NewTypedDataViewClass(kByteDataViewCid);
    RegisterPrivateClass(cls, Symbols::_ByteDataView(), lib);
    pending_classes.Add(cls);
#undef REGISTER_TYPED_DATA_VIEW_CLASS
#define REGISTER_EXT_TYPED_DATA_CLASS(clazz)                                   \
  cls = Class::NewExternalTypedDataClass(kExternalTypedData##clazz##Cid);      \
  RegisterPrivateClass(cls, Symbols::_External##clazz(), lib);

    cls = Class::New<Instance>(kByteBufferCid);
    cls.set_instance_size(0);
    cls.set_next_field_offset(-kWordSize);
    RegisterPrivateClass(cls, Symbols::_ByteBuffer(), lib);
    pending_classes.Add(cls);

    CLASS_LIST_TYPED_DATA(REGISTER_EXT_TYPED_DATA_CLASS);
#undef REGISTER_EXT_TYPED_DATA_CLASS
    // Register Float32x4, Int32x4, and Float64x2 in the object store.
    cls = Class::New<Float32x4>();
    RegisterPrivateClass(cls, Symbols::_Float32x4(), lib);
    pending_classes.Add(cls);
    object_store->set_float32x4_class(cls);

    cls = Class::New<Instance>(kIllegalCid);
    RegisterClass(cls, Symbols::Float32x4(), lib);
    cls.set_num_type_arguments(0);
    cls.set_num_own_type_arguments(0);
    cls.set_is_prefinalized();
    type = Type::NewNonParameterizedType(cls);
    object_store->set_float32x4_type(type);

    cls = Class::New<Int32x4>();
    RegisterPrivateClass(cls, Symbols::_Int32x4(), lib);
    pending_classes.Add(cls);
    object_store->set_int32x4_class(cls);

    cls = Class::New<Instance>(kIllegalCid);
    RegisterClass(cls, Symbols::Int32x4(), lib);
    cls.set_num_type_arguments(0);
    cls.set_num_own_type_arguments(0);
    cls.set_is_prefinalized();
    type = Type::NewNonParameterizedType(cls);
    object_store->set_int32x4_type(type);

    cls = Class::New<Float64x2>();
    RegisterPrivateClass(cls, Symbols::_Float64x2(), lib);
    pending_classes.Add(cls);
    object_store->set_float64x2_class(cls);

    cls = Class::New<Instance>(kIllegalCid);
    RegisterClass(cls, Symbols::Float64x2(), lib);
    cls.set_num_type_arguments(0);
    cls.set_num_own_type_arguments(0);
    cls.set_is_prefinalized();
    type = Type::NewNonParameterizedType(cls);
    object_store->set_float64x2_type(type);

    // Set the super type of class StackTrace to Object type so that the
    // 'toString' method is implemented.
    type = object_store->object_type();
    stacktrace_cls.set_super_type(type);

    // Abstract class that represents the Dart class Type.
    // Note that this class is implemented by Dart class _AbstractType.
    cls = Class::New<Instance>(kIllegalCid);
    cls.set_num_type_arguments(0);
    cls.set_num_own_type_arguments(0);
    cls.set_is_prefinalized();
    RegisterClass(cls, Symbols::Type(), core_lib);
    pending_classes.Add(cls);
    type = Type::NewNonParameterizedType(cls);
    object_store->set_type_type(type);

    // Abstract class that represents the Dart class Function.
    cls = Class::New<Instance>(kIllegalCid);
    cls.set_num_type_arguments(0);
    cls.set_num_own_type_arguments(0);
    cls.set_is_prefinalized();
    RegisterClass(cls, Symbols::Function(), core_lib);
    pending_classes.Add(cls);
    type = Type::NewNonParameterizedType(cls);
    object_store->set_function_type(type);

    cls = Class::New<Number>();
    RegisterClass(cls, Symbols::Number(), core_lib);
    pending_classes.Add(cls);
    type = Type::NewNonParameterizedType(cls);
    object_store->set_number_type(type);

    cls = Class::New<Instance>(kIllegalCid);
    RegisterClass(cls, Symbols::Int(), core_lib);
    cls.set_num_type_arguments(0);
    cls.set_num_own_type_arguments(0);
    cls.set_is_prefinalized();
    pending_classes.Add(cls);
    type = Type::NewNonParameterizedType(cls);
    object_store->set_int_type(type);

    cls = Class::New<Instance>(kIllegalCid);
    RegisterPrivateClass(cls, Symbols::Int64(), core_lib);
    cls.set_num_type_arguments(0);
    cls.set_num_own_type_arguments(0);
    cls.set_is_prefinalized();
    pending_classes.Add(cls);
    type = Type::NewNonParameterizedType(cls);
    object_store->set_int64_type(type);

    cls = Class::New<Instance>(kIllegalCid);
    RegisterClass(cls, Symbols::Double(), core_lib);
    cls.set_num_type_arguments(0);
    cls.set_num_own_type_arguments(0);
    cls.set_is_prefinalized();
    pending_classes.Add(cls);
    type = Type::NewNonParameterizedType(cls);
    object_store->set_double_type(type);

    name = Symbols::_String().raw();
    cls = Class::New<Instance>(kIllegalCid);
    RegisterClass(cls, name, core_lib);
    cls.set_num_type_arguments(0);
    cls.set_num_own_type_arguments(0);
    cls.set_is_prefinalized();
    pending_classes.Add(cls);
    type = Type::NewNonParameterizedType(cls);
    object_store->set_string_type(type);

    cls = object_store->bool_class();
    type = Type::NewNonParameterizedType(cls);
    object_store->set_bool_type(type);

    cls = object_store->smi_class();
    type = Type::NewNonParameterizedType(cls);
    object_store->set_smi_type(type);

    cls = object_store->mint_class();
    type = Type::NewNonParameterizedType(cls);
    object_store->set_mint_type(type);

    // The classes 'void' and 'dynamic' are phony classes to make type checking
    // more regular; they live in the VM isolate. The class 'void' is not
    // registered in the class dictionary because its name is a reserved word.
    // The class 'dynamic' is registered in the class dictionary because its
    // name is a built-in identifier (this is wrong).  The corresponding types
    // are stored in the object store.
    cls = object_store->null_class();
    type = Type::NewNonParameterizedType(cls);
    object_store->set_null_type(type);

    // Consider removing when/if Null becomes an ordinary class.
    type = object_store->object_type();
    cls.set_super_type(type);

    // Create and cache commonly used type arguments <int> and <String>
    type_args = TypeArguments::New(1);
    type = object_store->int_type();
    type_args.SetTypeAt(0, type);
    type_args.Canonicalize();
    object_store->set_type_argument_int(type_args);

    type_args = TypeArguments::New(1);
    type = object_store->string_type();
    type_args.SetTypeAt(0, type);
    type_args.Canonicalize();
    object_store->set_type_argument_string(type_args);

    // Finish the initialization by compiling the bootstrap scripts containing
    // the base interfaces and the implementation of the internal classes.
    const Error& error =
        Error::Handle(zone, Bootstrap::DoBootstrapping(kernel_program));
    if (!error.IsNull()) {
      return error.raw();
    }

    ClassFinalizer::VerifyBootstrapClasses();

    // Set up the intrinsic state of all functions (core, math and typed data).
    Intrinsifier::InitializeState();

    // Set up recognized state of all functions (core, math and typed data).
    MethodRecognizer::InitializeState();

    // Adds static const fields (class ids) to the class 'ClassID');
    lib = Library::LookupLibrary(thread, Symbols::DartInternal());
    ASSERT(!lib.IsNull());
    cls = lib.LookupClassAllowPrivate(Symbols::ClassID());
    ASSERT(!cls.IsNull());
    cls.InjectCIDFields();

    isolate->object_store()->InitKnownObjects();
#endif  // !defined(DART_PRECOMPILED_RUNTIME)
  } else {
    // Object::Init version when we are running in a version of dart that has a
    // full snapshot linked in and an isolate is initialized using the full
    // snapshot.
    ObjectStore* object_store = isolate->object_store();

    Class& cls = Class::Handle(zone);

    // Set up empty classes in the object store, these will get initialized
    // correctly when we read from the snapshot.  This is done to allow
    // bootstrapping of reading classes from the snapshot.  Some classes are not
    // stored in the object store. Yet we still need to create their Class
    // object so that they get put into the class_table (as a side effect of
    // Class::New()).
    cls = Class::New<Instance>(kInstanceCid);
    object_store->set_object_class(cls);

    cls = Class::New<LibraryPrefix>();
    cls = Class::New<Type>();
    cls = Class::New<TypeRef>();
    cls = Class::New<TypeParameter>();
    cls = Class::New<BoundedType>();
    cls = Class::New<MixinAppType>();

    cls = Class::New<Array>();
    object_store->set_array_class(cls);

    cls = Class::New<Array>(kImmutableArrayCid);
    object_store->set_immutable_array_class(cls);

    cls = Class::New<GrowableObjectArray>();
    object_store->set_growable_object_array_class(cls);

    cls = Class::New<LinkedHashMap>();
    object_store->set_linked_hash_map_class(cls);

    cls = Class::New<Float32x4>();
    object_store->set_float32x4_class(cls);

    cls = Class::New<Int32x4>();
    object_store->set_int32x4_class(cls);

    cls = Class::New<Float64x2>();
    object_store->set_float64x2_class(cls);

#define REGISTER_TYPED_DATA_CLASS(clazz)                                       \
  cls = Class::NewTypedDataClass(kTypedData##clazz##Cid);
    CLASS_LIST_TYPED_DATA(REGISTER_TYPED_DATA_CLASS);
#undef REGISTER_TYPED_DATA_CLASS
#define REGISTER_TYPED_DATA_VIEW_CLASS(clazz)                                  \
  cls = Class::NewTypedDataViewClass(kTypedData##clazz##ViewCid);
    CLASS_LIST_TYPED_DATA(REGISTER_TYPED_DATA_VIEW_CLASS);
#undef REGISTER_TYPED_DATA_VIEW_CLASS
    cls = Class::NewTypedDataViewClass(kByteDataViewCid);
#define REGISTER_EXT_TYPED_DATA_CLASS(clazz)                                   \
  cls = Class::NewExternalTypedDataClass(kExternalTypedData##clazz##Cid);
    CLASS_LIST_TYPED_DATA(REGISTER_EXT_TYPED_DATA_CLASS);
#undef REGISTER_EXT_TYPED_DATA_CLASS

    cls = Class::New<Instance>(kByteBufferCid);

    cls = Class::New<Integer>();
    object_store->set_integer_implementation_class(cls);

    cls = Class::New<Smi>();
    object_store->set_smi_class(cls);

    cls = Class::New<Mint>();
    object_store->set_mint_class(cls);

    cls = Class::New<Double>();
    object_store->set_double_class(cls);

    cls = Class::New<Closure>();
    object_store->set_closure_class(cls);

    cls = Class::New<Bigint>();
    object_store->set_bigint_class(cls);

    cls = Class::NewStringClass(kOneByteStringCid);
    object_store->set_one_byte_string_class(cls);

    cls = Class::NewStringClass(kTwoByteStringCid);
    object_store->set_two_byte_string_class(cls);

    cls = Class::NewStringClass(kExternalOneByteStringCid);
    object_store->set_external_one_byte_string_class(cls);

    cls = Class::NewStringClass(kExternalTwoByteStringCid);
    object_store->set_external_two_byte_string_class(cls);

    cls = Class::New<Bool>();
    object_store->set_bool_class(cls);

    cls = Class::New<Instance>(kNullCid);
    object_store->set_null_class(cls);

    cls = Class::New<Capability>();
    cls = Class::New<ReceivePort>();
    cls = Class::New<SendPort>();
    cls = Class::New<StackTrace>();
    cls = Class::New<RegExp>();
    cls = Class::New<Number>();

    cls = Class::New<WeakProperty>();
    object_store->set_weak_property_class(cls);

    cls = Class::New<MirrorReference>();
    cls = Class::New<UserTag>();
  }
  return Error::null();
}

#if defined(DEBUG)
bool Object::InVMHeap() const {
  if (FLAG_verify_handles && raw()->IsVMHeapObject()) {
    Heap* vm_isolate_heap = Dart::vm_isolate()->heap();
    ASSERT(vm_isolate_heap->Contains(RawObject::ToAddr(raw())));
  }
  return raw()->IsVMHeapObject();
}
#endif  // DEBUG

void Object::Print() const {
  THR_Print("%s\n", ToCString());
}

RawString* Object::DictionaryName() const {
  return String::null();
}

void Object::InitializeObject(uword address,
                              intptr_t class_id,
                              intptr_t size,
                              bool is_vm_object) {
  uword initial_value = (class_id == kInstructionsCid)
                            ? Assembler::GetBreakInstructionFiller()
                            : reinterpret_cast<uword>(null_);
  uword cur = address;
  uword end = address + size;
  while (cur < end) {
    *reinterpret_cast<uword*>(cur) = initial_value;
    cur += kWordSize;
  }
  uint32_t tags = 0;
  ASSERT(class_id != kIllegalCid);
  tags = RawObject::ClassIdTag::update(class_id, tags);
  tags = RawObject::SizeTag::update(size, tags);
  tags = RawObject::VMHeapObjectTag::update(is_vm_object, tags);
  reinterpret_cast<RawObject*>(address)->tags_ = tags;
#if defined(HASH_IN_OBJECT_HEADER)
  reinterpret_cast<RawObject*>(address)->hash_ = 0;
#endif
  ASSERT(is_vm_object == RawObject::IsVMHeapObject(tags));
}

void Object::CheckHandle() const {
#if defined(DEBUG)
  if (raw_ != Object::null()) {
    if ((reinterpret_cast<uword>(raw_) & kSmiTagMask) == kSmiTag) {
      ASSERT(vtable() == Smi::handle_vtable_);
      return;
    }
    intptr_t cid = raw_->GetClassId();
    if (cid >= kNumPredefinedCids) {
      cid = kInstanceCid;
    }
    ASSERT(vtable() == builtin_vtables_[cid]);
    if (FLAG_verify_handles) {
      Isolate* isolate = Isolate::Current();
      Heap* isolate_heap = isolate->heap();
      Heap* vm_isolate_heap = Dart::vm_isolate()->heap();
      ASSERT(isolate_heap->Contains(RawObject::ToAddr(raw_)) ||
             vm_isolate_heap->Contains(RawObject::ToAddr(raw_)));
    }
  }
#endif
}

RawObject* Object::Allocate(intptr_t cls_id, intptr_t size, Heap::Space space) {
  ASSERT(Utils::IsAligned(size, kObjectAlignment));
  Thread* thread = Thread::Current();
  Isolate* isolate = thread->isolate();
  // New space allocation allowed only in mutator thread (Dart thread);
  ASSERT(thread->IsMutatorThread() || (space != Heap::kNew));
  ASSERT(thread->no_callback_scope_depth() == 0);
  Heap* heap = isolate->heap();

  uword address = heap->Allocate(size, space);
  if (address == 0) {
    // Use the preallocated out of memory exception to avoid calling
    // into dart code or allocating any code.
    const Instance& exception =
        Instance::Handle(isolate->object_store()->out_of_memory());
    Exceptions::Throw(thread, exception);
    UNREACHABLE();
  }
#ifndef PRODUCT
  ClassTable* class_table = isolate->class_table();
  if (space == Heap::kNew) {
    class_table->UpdateAllocatedNew(cls_id, size);
  } else {
    class_table->UpdateAllocatedOld(cls_id, size);
  }
  const Class& cls = Class::Handle(class_table->At(cls_id));
  if (FLAG_profiler && cls.TraceAllocation(isolate)) {
    Profiler::SampleAllocation(thread, cls_id);
  }
#endif  // !PRODUCT
  NoSafepointScope no_safepoint;
  InitializeObject(address, cls_id, size, (isolate == Dart::vm_isolate()));
  RawObject* raw_obj = reinterpret_cast<RawObject*>(address + kHeapObjectTag);
  ASSERT(cls_id == RawObject::ClassIdTag::decode(raw_obj->ptr()->tags_));
  return raw_obj;
}

class StoreBufferUpdateVisitor : public ObjectPointerVisitor {
 public:
  explicit StoreBufferUpdateVisitor(Thread* thread, RawObject* obj)
      : ObjectPointerVisitor(thread->isolate()),
        thread_(thread),
        old_obj_(obj) {
    ASSERT(old_obj_->IsOldObject());
  }

  void VisitPointers(RawObject** first, RawObject** last) {
    for (RawObject** curr = first; curr <= last; ++curr) {
      RawObject* raw_obj = *curr;
      if (raw_obj->IsHeapObject() && raw_obj->IsNewObject()) {
        old_obj_->SetRememberedBit();
        thread_->StoreBufferAddObject(old_obj_);
        // Remembered this object. There is no need to continue searching.
        return;
      }
    }
  }

 private:
  Thread* thread_;
  RawObject* old_obj_;

  DISALLOW_COPY_AND_ASSIGN(StoreBufferUpdateVisitor);
};

bool Object::IsReadOnlyHandle() const {
  return Dart::IsReadOnlyHandle(reinterpret_cast<uword>(this));
}

bool Object::IsNotTemporaryScopedHandle() const {
  return (IsZoneHandle() || IsReadOnlyHandle());
}

RawObject* Object::Clone(const Object& orig, Heap::Space space) {
  const Class& cls = Class::Handle(orig.clazz());
  intptr_t size = orig.raw()->Size();
  RawObject* raw_clone = Object::Allocate(cls.id(), size, space);
  NoSafepointScope no_safepoint;
  // TODO(koda): This will trip when we start allocating black.
  // Revisit code below at that point, to account for the new write barrier.
  ASSERT(!raw_clone->IsMarked());
  // Copy the body of the original into the clone.
  uword orig_addr = RawObject::ToAddr(orig.raw());
  uword clone_addr = RawObject::ToAddr(raw_clone);
  static const intptr_t kHeaderSizeInBytes = sizeof(RawObject);
  memmove(reinterpret_cast<uint8_t*>(clone_addr + kHeaderSizeInBytes),
          reinterpret_cast<uint8_t*>(orig_addr + kHeaderSizeInBytes),
          size - kHeaderSizeInBytes);
  // Add clone to store buffer, if needed.
  if (!raw_clone->IsOldObject()) {
    // No need to remember an object in new space.
    return raw_clone;
  } else if (orig.raw()->IsOldObject() && !orig.raw()->IsRemembered()) {
    // Old original doesn't need to be remembered, so neither does the clone.
    return raw_clone;
  }
  StoreBufferUpdateVisitor visitor(Thread::Current(), raw_clone);
  raw_clone->VisitPointers(&visitor);
  return raw_clone;
}

RawString* Class::Name() const {
  return raw_ptr()->name_;
}

RawString* Class::ScrubbedName() const {
  return String::ScrubName(String::Handle(Name()));
}

RawString* Class::UserVisibleName() const {
#if !defined(PRODUCT)
  ASSERT(raw_ptr()->user_name_ != String::null());
  return raw_ptr()->user_name_;
#endif                               // !defined(PRODUCT)
  return GenerateUserVisibleName();  // No caching in PRODUCT, regenerate.
}

bool Class::IsInFullSnapshot() const {
  NoSafepointScope no_safepoint;
  return raw_ptr()->library_->ptr()->is_in_fullsnapshot_;
}

RawAbstractType* Class::RareType() const {
  const Type& type = Type::Handle(Type::New(
      *this, Object::null_type_arguments(), TokenPosition::kNoSource));
  return ClassFinalizer::FinalizeType(*this, type);
}

RawAbstractType* Class::DeclarationType() const {
  const TypeArguments& args = TypeArguments::Handle(type_parameters());
  const Type& type =
      Type::Handle(Type::New(*this, args, TokenPosition::kNoSource));
  return ClassFinalizer::FinalizeType(*this, type);
}

template <class FakeObject>
RawClass* Class::New() {
  ASSERT(Object::class_class() != Class::null());
  Class& result = Class::Handle();
  {
    RawObject* raw =
        Object::Allocate(Class::kClassId, Class::InstanceSize(), Heap::kOld);
    NoSafepointScope no_safepoint;
    result ^= raw;
  }
  FakeObject fake;
  result.set_handle_vtable(fake.vtable());
  result.set_token_pos(TokenPosition::kNoSource);
  result.set_instance_size(FakeObject::InstanceSize());
  result.set_type_arguments_field_offset_in_words(kNoTypeArguments);
  result.set_next_field_offset(FakeObject::NextFieldOffset());
  COMPILE_ASSERT((FakeObject::kClassId != kInstanceCid));
  result.set_id(FakeObject::kClassId);
  result.set_num_type_arguments(0);
  result.set_num_own_type_arguments(0);
  result.set_num_native_fields(0);
  result.set_state_bits(0);
  if ((FakeObject::kClassId < kInstanceCid) ||
      (FakeObject::kClassId == kTypeArgumentsCid)) {
    // VM internal classes are done. There is no finalization needed or
    // possible in this case.
    result.set_is_finalized();
  } else {
    // VM backed classes are almost ready: run checks and resolve class
    // references, but do not recompute size.
    result.set_is_prefinalized();
  }
  result.set_kernel_offset(-1);
  result.InitEmptyFields();
  Isolate::Current()->RegisterClass(result);
  return result.raw();
}

static void ReportTooManyTypeArguments(const Class& cls) {
  Report::MessageF(Report::kError, Script::Handle(cls.script()),
                   cls.token_pos(), Report::AtLocation,
                   "too many type parameters declared in class '%s' or in its "
                   "super classes",
                   String::Handle(cls.Name()).ToCString());
  UNREACHABLE();
}

void Class::set_num_type_arguments(intptr_t value) const {
  if (!Utils::IsInt(16, value)) {
    ReportTooManyTypeArguments(*this);
  }
  StoreNonPointer(&raw_ptr()->num_type_arguments_, value);
}

void Class::set_num_own_type_arguments(intptr_t value) const {
  if (!Utils::IsInt(16, value)) {
    ReportTooManyTypeArguments(*this);
  }
  StoreNonPointer(&raw_ptr()->num_own_type_arguments_, value);
}

// Initialize class fields of type Array with empty array.
void Class::InitEmptyFields() {
  if (Object::empty_array().raw() == Array::null()) {
    // The empty array has not been initialized yet.
    return;
  }
  StorePointer(&raw_ptr()->interfaces_, Object::empty_array().raw());
  StorePointer(&raw_ptr()->constants_, Object::empty_array().raw());
  StorePointer(&raw_ptr()->functions_, Object::empty_array().raw());
  StorePointer(&raw_ptr()->fields_, Object::empty_array().raw());
  StorePointer(&raw_ptr()->invocation_dispatcher_cache_,
               Object::empty_array().raw());
}

RawArray* Class::OffsetToFieldMap(bool original_classes) const {
  Array& array = Array::Handle(raw_ptr()->offset_in_words_to_field_);
  if (array.IsNull()) {
    ASSERT(is_finalized());
    const intptr_t length = raw_ptr()->instance_size_in_words_;
    array = Array::New(length, Heap::kOld);
    Class& cls = Class::Handle(this->raw());
    Array& fields = Array::Handle();
    Field& f = Field::Handle();
    while (!cls.IsNull()) {
      fields = cls.fields();
      for (intptr_t i = 0; i < fields.Length(); ++i) {
        f ^= fields.At(i);
        if (f.is_instance()) {
          array.SetAt(f.Offset() >> kWordSizeLog2, f);
        }
      }
      cls = cls.SuperClass(original_classes);
    }
    StorePointer(&raw_ptr()->offset_in_words_to_field_, array.raw());
  }
  return array.raw();
}

bool Class::HasInstanceFields() const {
  const Array& field_array = Array::Handle(fields());
  Field& field = Field::Handle();
  for (intptr_t i = 0; i < field_array.Length(); ++i) {
    field ^= field_array.At(i);
    if (!field.is_static()) {
      return true;
    }
  }
  return false;
}

class FunctionName {
 public:
  FunctionName(const String& name, String* tmp_string)
      : name_(name), tmp_string_(tmp_string) {}
  bool Matches(const Function& function) const {
    if (name_.IsSymbol()) {
      return name_.raw() == function.name();
    } else {
      *tmp_string_ = function.name();
      return name_.Equals(*tmp_string_);
    }
  }
  intptr_t Hash() const { return name_.Hash(); }

 private:
  const String& name_;
  String* tmp_string_;
};

// Traits for looking up Functions by name.
class ClassFunctionsTraits {
 public:
  static const char* Name() { return "ClassFunctionsTraits"; }
  static bool ReportStats() { return false; }

  // Called when growing the table.
  static bool IsMatch(const Object& a, const Object& b) {
    ASSERT(a.IsFunction() && b.IsFunction());
    // Function objects are always canonical.
    return a.raw() == b.raw();
  }
  static bool IsMatch(const FunctionName& name, const Object& obj) {
    return name.Matches(Function::Cast(obj));
  }
  static uword Hash(const Object& key) {
    return String::HashRawSymbol(Function::Cast(key).name());
  }
  static uword Hash(const FunctionName& name) { return name.Hash(); }
};
typedef UnorderedHashSet<ClassFunctionsTraits> ClassFunctionsSet;

void Class::SetFunctions(const Array& value) const {
  ASSERT(Thread::Current()->IsMutatorThread());
  ASSERT(!value.IsNull());
  StorePointer(&raw_ptr()->functions_, value.raw());
  const intptr_t len = value.Length();
  if (len >= kFunctionLookupHashTreshold) {
    ClassFunctionsSet set(HashTables::New<ClassFunctionsSet>(len, Heap::kOld));
    Function& func = Function::Handle();
    for (intptr_t i = 0; i < len; ++i) {
      func ^= value.At(i);
      // Verify that all the functions in the array have this class as owner.
      ASSERT(func.Owner() == raw());
      set.Insert(func);
    }
    StorePointer(&raw_ptr()->functions_hash_table_, set.Release().raw());
  } else {
    StorePointer(&raw_ptr()->functions_hash_table_, Array::null());
  }
}

void Class::AddFunction(const Function& function) const {
  ASSERT(Thread::Current()->IsMutatorThread());
  const Array& arr = Array::Handle(functions());
  const Array& new_arr =
      Array::Handle(Array::Grow(arr, arr.Length() + 1, Heap::kOld));
  new_arr.SetAt(arr.Length(), function);
  StorePointer(&raw_ptr()->functions_, new_arr.raw());
  // Add to hash table, if any.
  const intptr_t new_len = new_arr.Length();
  if (new_len == kFunctionLookupHashTreshold) {
    // Transition to using hash table.
    SetFunctions(new_arr);
  } else if (new_len > kFunctionLookupHashTreshold) {
    ClassFunctionsSet set(raw_ptr()->functions_hash_table_);
    set.Insert(function);
    StorePointer(&raw_ptr()->functions_hash_table_, set.Release().raw());
  }
}

void Class::RemoveFunction(const Function& function) const {
  ASSERT(Thread::Current()->IsMutatorThread());
  const Array& arr = Array::Handle(functions());
  StorePointer(&raw_ptr()->functions_, Object::empty_array().raw());
  StorePointer(&raw_ptr()->functions_hash_table_, Array::null());
  Function& entry = Function::Handle();
  for (intptr_t i = 0; i < arr.Length(); i++) {
    entry ^= arr.At(i);
    if (function.raw() != entry.raw()) {
      AddFunction(entry);
    }
  }
}

RawFunction* Class::FunctionFromIndex(intptr_t idx) const {
  const Array& funcs = Array::Handle(functions());
  if ((idx < 0) || (idx >= funcs.Length())) {
    return Function::null();
  }
  Function& func = Function::Handle();
  func ^= funcs.At(idx);
  ASSERT(!func.IsNull());
  return func.raw();
}

RawFunction* Class::ImplicitClosureFunctionFromIndex(intptr_t idx) const {
  const Array& funcs = Array::Handle(functions());
  if ((idx < 0) || (idx >= funcs.Length())) {
    return Function::null();
  }
  Function& func = Function::Handle();
  func ^= funcs.At(idx);
  ASSERT(!func.IsNull());
  if (!func.HasImplicitClosureFunction()) {
    return Function::null();
  }
  const Function& closure_func =
      Function::Handle(func.ImplicitClosureFunction());
  ASSERT(!closure_func.IsNull());
  return closure_func.raw();
}

intptr_t Class::FindImplicitClosureFunctionIndex(const Function& needle) const {
  Thread* thread = Thread::Current();
  if (EnsureIsFinalized(thread) != Error::null()) {
    return -1;
  }
  REUSABLE_ARRAY_HANDLESCOPE(thread);
  REUSABLE_FUNCTION_HANDLESCOPE(thread);
  Array& funcs = thread->ArrayHandle();
  Function& function = thread->FunctionHandle();
  funcs ^= functions();
  ASSERT(!funcs.IsNull());
  Function& implicit_closure = Function::Handle(thread->zone());
  const intptr_t len = funcs.Length();
  for (intptr_t i = 0; i < len; i++) {
    function ^= funcs.At(i);
    implicit_closure ^= function.implicit_closure_function();
    if (implicit_closure.IsNull()) {
      // Skip non-implicit closure functions.
      continue;
    }
    if (needle.raw() == implicit_closure.raw()) {
      return i;
    }
  }
  // No function found.
  return -1;
}

intptr_t Class::FindInvocationDispatcherFunctionIndex(
    const Function& needle) const {
  Thread* thread = Thread::Current();
  if (EnsureIsFinalized(thread) != Error::null()) {
    return -1;
  }
  REUSABLE_ARRAY_HANDLESCOPE(thread);
  REUSABLE_OBJECT_HANDLESCOPE(thread);
  Array& funcs = thread->ArrayHandle();
  Object& object = thread->ObjectHandle();
  funcs ^= invocation_dispatcher_cache();
  ASSERT(!funcs.IsNull());
  const intptr_t len = funcs.Length();
  for (intptr_t i = 0; i < len; i++) {
    object = funcs.At(i);
    // The invocation_dispatcher_cache is a table with some entries that
    // are functions.
    if (object.IsFunction()) {
      if (Function::Cast(object).raw() == needle.raw()) {
        return i;
      }
    }
  }
  // No function found.
  return -1;
}

RawFunction* Class::InvocationDispatcherFunctionFromIndex(intptr_t idx) const {
  Thread* thread = Thread::Current();
  REUSABLE_ARRAY_HANDLESCOPE(thread);
  REUSABLE_OBJECT_HANDLESCOPE(thread);
  Array& dispatcher_cache = thread->ArrayHandle();
  Object& object = thread->ObjectHandle();
  dispatcher_cache ^= invocation_dispatcher_cache();
  object = dispatcher_cache.At(idx);
  if (!object.IsFunction()) {
    return Function::null();
  }
  return Function::Cast(object).raw();
}

void Class::set_signature_function(const Function& value) const {
  ASSERT(value.IsClosureFunction() || value.IsSignatureFunction());
  StorePointer(&raw_ptr()->signature_function_, value.raw());
}

void Class::set_state_bits(intptr_t bits) const {
  StoreNonPointer(&raw_ptr()->state_bits_, static_cast<uint16_t>(bits));
}

void Class::set_library(const Library& value) const {
  StorePointer(&raw_ptr()->library_, value.raw());
}

void Class::set_type_parameters(const TypeArguments& value) const {
  StorePointer(&raw_ptr()->type_parameters_, value.raw());
}

intptr_t Class::NumTypeParameters(Thread* thread) const {
  if (IsMixinApplication() && !is_mixin_type_applied()) {
    ClassFinalizer::ApplyMixinType(*this);
  }
  if (type_parameters() == TypeArguments::null()) {
    const intptr_t cid = id();
    if ((cid == kArrayCid) || (cid == kImmutableArrayCid) ||
        (cid == kGrowableObjectArrayCid)) {
      return 1;  // List's type parameter may not have been parsed yet.
    }
    return 0;
  }
  REUSABLE_TYPE_ARGUMENTS_HANDLESCOPE(thread);
  TypeArguments& type_params = thread->TypeArgumentsHandle();
  type_params = type_parameters();
  return type_params.Length();
}

intptr_t Class::NumOwnTypeArguments() const {
  // Return cached value if already calculated.
  if (num_own_type_arguments() != kUnknownNumTypeArguments) {
    return num_own_type_arguments();
  }
  Thread* thread = Thread::Current();
  Isolate* isolate = thread->isolate();
  Zone* zone = thread->zone();
  const intptr_t num_type_params = NumTypeParameters();
  if (!FLAG_overlap_type_arguments || (num_type_params == 0) ||
      (super_type() == AbstractType::null()) ||
      (super_type() == isolate->object_store()->object_type())) {
    set_num_own_type_arguments(num_type_params);
    return num_type_params;
  }
  ASSERT(!IsMixinApplication() || is_mixin_type_applied());
  const AbstractType& sup_type = AbstractType::Handle(zone, super_type());
  const TypeArguments& sup_type_args =
      TypeArguments::Handle(zone, sup_type.arguments());
  if (sup_type_args.IsNull()) {
    // The super type is raw or the super class is non generic.
    // In either case, overlapping is not possible.
    set_num_own_type_arguments(num_type_params);
    return num_type_params;
  }
  const intptr_t num_sup_type_args = sup_type_args.Length();
  // At this point, the super type may or may not be finalized. In either case,
  // the result of this function must remain the same.
  // The value of num_sup_type_args may increase when the super type is
  // finalized, but the last num_sup_type_args type arguments will not be
  // modified by finalization, only shifted to higher indices in the vector.
  // They may however get wrapped in a BoundedType, which we skip.
  // The super type may not even be resolved yet. This is not necessary, since
  // we only check for matching type parameters, which are resolved by default.
  const TypeArguments& type_params =
      TypeArguments::Handle(zone, type_parameters());
  // Determine the maximum overlap of a prefix of the vector consisting of the
  // type parameters of this class with a suffix of the vector consisting of the
  // type arguments of the super type of this class.
  // The number of own type arguments of this class is the number of its type
  // parameters minus the number of type arguments in the overlap.
  // Attempt to overlap the whole vector of type parameters; reduce the size
  // of the vector (keeping the first type parameter) until it fits or until
  // its size is zero.
  TypeParameter& type_param = TypeParameter::Handle(zone);
  AbstractType& sup_type_arg = AbstractType::Handle(zone);
  for (intptr_t num_overlapping_type_args =
           (num_type_params < num_sup_type_args) ? num_type_params
                                                 : num_sup_type_args;
       num_overlapping_type_args > 0; num_overlapping_type_args--) {
    intptr_t i = 0;
    for (; i < num_overlapping_type_args; i++) {
      type_param ^= type_params.TypeAt(i);
      sup_type_arg = sup_type_args.TypeAt(num_sup_type_args -
                                          num_overlapping_type_args + i);
      // BoundedType can nest in case the finalized super type has bounded type
      // arguments that overlap multiple times in its own super class chain.
      while (sup_type_arg.IsBoundedType()) {
        sup_type_arg = BoundedType::Cast(sup_type_arg).type();
      }
      if (!type_param.Equals(sup_type_arg)) break;
    }
    if (i == num_overlapping_type_args) {
      // Overlap found.
      set_num_own_type_arguments(num_type_params - num_overlapping_type_args);
      return num_type_params - num_overlapping_type_args;
    }
  }
  // No overlap found.
  set_num_own_type_arguments(num_type_params);
  return num_type_params;
}

intptr_t Class::NumTypeArguments() const {
  // Return cached value if already calculated.
  if (num_type_arguments() != kUnknownNumTypeArguments) {
    return num_type_arguments();
  }
  // To work properly, this call requires the super class of this class to be
  // resolved, which is checked by the type_class() call on the super type.
  // Note that calling type_class() on a MixinAppType fails.
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  Isolate* isolate = thread->isolate();
  Class& cls = Class::Handle(zone);
  AbstractType& sup_type = AbstractType::Handle(zone);
  cls = raw();
  intptr_t num_type_args = 0;
  do {
    // Calling NumOwnTypeArguments() on a mixin application class will setup the
    // type parameters if not already done.
    num_type_args += cls.NumOwnTypeArguments();
    // Super type of Object class is null.
    if ((cls.super_type() == AbstractType::null()) ||
        (cls.super_type() == isolate->object_store()->object_type())) {
      break;
    }
    sup_type = cls.super_type();
    // A BoundedType, TypeRef, or function type can appear as type argument of
    // sup_type, but not as sup_type itself.
    ASSERT(sup_type.IsType());
    ClassFinalizer::ResolveTypeClass(cls, Type::Cast(sup_type));
    cls = sup_type.type_class();
    ASSERT(!cls.IsTypedefClass());
  } while (true);
  set_num_type_arguments(num_type_args);
  return num_type_args;
}

RawClass* Class::SuperClass(bool original_classes) const {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  Isolate* isolate = thread->isolate();
  if (super_type() == AbstractType::null()) {
    if (id() == kTypeArgumentsCid) {
      // Pretend TypeArguments objects are Dart instances.
      return isolate->class_table()->At(kInstanceCid);
    }
    return Class::null();
  }
  const AbstractType& sup_type = AbstractType::Handle(zone, super_type());
  const intptr_t type_class_id = sup_type.type_class_id();
  if (original_classes) {
    return isolate->GetClassForHeapWalkAt(type_class_id);
  } else {
    return isolate->class_table()->At(type_class_id);
  }
}

void Class::set_super_type(const AbstractType& value) const {
  ASSERT(value.IsNull() || (value.IsType() && !value.IsDynamicType()) ||
         value.IsMixinAppType());
  StorePointer(&raw_ptr()->super_type_, value.raw());
}

RawTypeParameter* Class::LookupTypeParameter(const String& type_name) const {
  ASSERT(!type_name.IsNull());
  Thread* thread = Thread::Current();
  REUSABLE_TYPE_ARGUMENTS_HANDLESCOPE(thread);
  REUSABLE_TYPE_PARAMETER_HANDLESCOPE(thread);
  REUSABLE_STRING_HANDLESCOPE(thread);
  TypeArguments& type_params = thread->TypeArgumentsHandle();
  TypeParameter& type_param = thread->TypeParameterHandle();
  String& type_param_name = thread->StringHandle();

  type_params ^= type_parameters();
  if (!type_params.IsNull()) {
    const intptr_t num_type_params = type_params.Length();
    for (intptr_t i = 0; i < num_type_params; i++) {
      type_param ^= type_params.TypeAt(i);
      type_param_name = type_param.name();
      if (type_param_name.Equals(type_name)) {
        return type_param.raw();
      }
    }
  }
  return TypeParameter::null();
}

void Class::CalculateFieldOffsets() const {
  Array& flds = Array::Handle(fields());
  const Class& super = Class::Handle(SuperClass());
  intptr_t offset = 0;
  intptr_t type_args_field_offset = kNoTypeArguments;
  if (super.IsNull()) {
    offset = Instance::NextFieldOffset();
    ASSERT(offset > 0);
  } else {
    ASSERT(super.is_finalized() || super.is_prefinalized());
    type_args_field_offset = super.type_arguments_field_offset();
    offset = super.next_field_offset();
    ASSERT(offset > 0);
    // We should never call CalculateFieldOffsets for native wrapper
    // classes, assert this.
    ASSERT(num_native_fields() == 0);
    set_num_native_fields(super.num_native_fields());
  }
  // If the super class is parameterized, use the same type_arguments field,
  // otherwise, if this class is the first in the super chain to be
  // parameterized, introduce a new type_arguments field.
  if (type_args_field_offset == kNoTypeArguments) {
    const TypeArguments& type_params = TypeArguments::Handle(type_parameters());
    if (!type_params.IsNull()) {
      ASSERT(type_params.Length() > 0);
      // The instance needs a type_arguments field.
      type_args_field_offset = offset;
      offset += kWordSize;
    }
  }
  set_type_arguments_field_offset(type_args_field_offset);
  ASSERT(offset > 0);
  Field& field = Field::Handle();
  intptr_t len = flds.Length();
  for (intptr_t i = 0; i < len; i++) {
    field ^= flds.At(i);
    // Offset is computed only for instance fields.
    if (!field.is_static()) {
      ASSERT(field.Offset() == 0);
      field.SetOffset(offset);
      offset += kWordSize;
    }
  }
  set_instance_size(RoundedAllocationSize(offset));
  set_next_field_offset(offset);
}

RawFunction* Class::GetInvocationDispatcher(const String& target_name,
                                            const Array& args_desc,
                                            RawFunction::Kind kind,
                                            bool create_if_absent) const {
  enum { kNameIndex = 0, kArgsDescIndex, kFunctionIndex, kEntrySize };

  ASSERT(kind == RawFunction::kNoSuchMethodDispatcher ||
         kind == RawFunction::kInvokeFieldDispatcher);
  Function& dispatcher = Function::Handle();
  Array& cache = Array::Handle(invocation_dispatcher_cache());
  ASSERT(!cache.IsNull());
  String& name = String::Handle();
  Array& desc = Array::Handle();
  intptr_t i = 0;
  for (; i < cache.Length(); i += kEntrySize) {
    name ^= cache.At(i + kNameIndex);
    if (name.IsNull()) break;  // Reached last entry.
    if (!name.Equals(target_name)) continue;
    desc ^= cache.At(i + kArgsDescIndex);
    if (desc.raw() != args_desc.raw()) continue;
    dispatcher ^= cache.At(i + kFunctionIndex);
    if (dispatcher.kind() == kind) {
      // Found match.
      ASSERT(dispatcher.IsFunction());
      break;
    }
  }

  if (dispatcher.IsNull() && create_if_absent) {
    if (i == cache.Length()) {
      // Allocate new larger cache.
      intptr_t new_len = (cache.Length() == 0)
                             ? static_cast<intptr_t>(kEntrySize)
                             : cache.Length() * 2;
      cache ^= Array::Grow(cache, new_len);
      set_invocation_dispatcher_cache(cache);
    }
    dispatcher ^= CreateInvocationDispatcher(target_name, args_desc, kind);
    cache.SetAt(i + kNameIndex, target_name);
    cache.SetAt(i + kArgsDescIndex, args_desc);
    cache.SetAt(i + kFunctionIndex, dispatcher);
  }
  return dispatcher.raw();
}

RawFunction* Class::CreateInvocationDispatcher(const String& target_name,
                                               const Array& args_desc,
                                               RawFunction::Kind kind) const {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  Function& invocation = Function::Handle(
      zone, Function::New(
                String::Handle(zone, Symbols::New(thread, target_name)), kind,
                false,  // Not static.
                false,  // Not const.
                false,  // Not abstract.
                false,  // Not external.
                false,  // Not native.
                *this, TokenPosition::kMinSource));
  ArgumentsDescriptor desc(args_desc);
  if (desc.TypeArgsLen() > 0) {
    // Make dispatcher function generic, since type arguments are passed.
    const TypeArguments& type_params =
        TypeArguments::Handle(zone, TypeArguments::New(desc.TypeArgsLen()));
    // The presence of a type parameter array is enough to mark this dispatcher
    // as generic. To save memory, we do not copy the type parameters to the
    // array (they are not accessed), but leave it as an array of null objects.
    invocation.set_type_parameters(type_params);
  }

  invocation.set_num_fixed_parameters(desc.PositionalCount());
  invocation.SetNumOptionalParameters(desc.NamedCount(),
                                      false);  // Not positional.
  invocation.set_parameter_types(
      Array::Handle(zone, Array::New(desc.Count(), Heap::kOld)));
  invocation.set_parameter_names(
      Array::Handle(zone, Array::New(desc.Count(), Heap::kOld)));
  // Receiver.
  invocation.SetParameterTypeAt(0, Object::dynamic_type());
  invocation.SetParameterNameAt(0, Symbols::This());
  // Remaining positional parameters.
  intptr_t i = 1;
  for (; i < desc.PositionalCount(); i++) {
    invocation.SetParameterTypeAt(i, Object::dynamic_type());
    char name[64];
    Utils::SNPrint(name, 64, ":p%" Pd, i);
    invocation.SetParameterNameAt(
        i, String::Handle(zone, Symbols::New(thread, name)));
  }

  // Named parameters.
  for (; i < desc.Count(); i++) {
    invocation.SetParameterTypeAt(i, Object::dynamic_type());
    intptr_t index = i - desc.PositionalCount();
    invocation.SetParameterNameAt(i, String::Handle(zone, desc.NameAt(index)));
  }
  invocation.set_result_type(Object::dynamic_type());
  invocation.set_is_debuggable(false);
  invocation.set_is_visible(false);
  invocation.set_is_reflectable(false);
  invocation.set_saved_args_desc(args_desc);

  return invocation.raw();
}

// Method extractors are used to create implicit closures from methods.
// When an expression obj.M is evaluated for the first time and receiver obj
// does not have a getter called M but has a method called M then an extractor
// is created and injected as a getter (under the name get:M) into the class
// owning method M.
RawFunction* Function::CreateMethodExtractor(const String& getter_name) const {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  ASSERT(Field::IsGetterName(getter_name));
  const Function& closure_function =
      Function::Handle(zone, ImplicitClosureFunction());

  const Class& owner = Class::Handle(zone, closure_function.Owner());
  Function& extractor = Function::Handle(
      zone,
      Function::New(String::Handle(zone, Symbols::New(thread, getter_name)),
                    RawFunction::kMethodExtractor,
                    false,  // Not static.
                    false,  // Not const.
                    false,  // Not abstract.
                    false,  // Not external.
                    false,  // Not native.
                    owner, TokenPosition::kMethodExtractor));

  // Initialize signature: receiver is a single fixed parameter.
  const intptr_t kNumParameters = 1;
  extractor.set_num_fixed_parameters(kNumParameters);
  extractor.SetNumOptionalParameters(0, 0);
  extractor.set_parameter_types(Object::extractor_parameter_types());
  extractor.set_parameter_names(Object::extractor_parameter_names());
  extractor.set_result_type(Object::dynamic_type());
  extractor.set_kernel_offset(kernel_offset());

  extractor.set_extracted_method_closure(closure_function);
  extractor.set_is_debuggable(false);
  extractor.set_is_visible(false);

  owner.AddFunction(extractor);

  return extractor.raw();
}

RawFunction* Function::GetMethodExtractor(const String& getter_name) const {
  ASSERT(Field::IsGetterName(getter_name));
  const Function& closure_function =
      Function::Handle(ImplicitClosureFunction());
  const Class& owner = Class::Handle(closure_function.Owner());
  Function& result = Function::Handle(owner.LookupDynamicFunction(getter_name));
  if (result.IsNull()) {
    result ^= CreateMethodExtractor(getter_name);
  }
  ASSERT(result.kind() == RawFunction::kMethodExtractor);
  return result.raw();
}

bool AbstractType::InstantiateAndTestSubtype(
    AbstractType* subtype,
    AbstractType* supertype,
    Error* bound_error,
    const TypeArguments& instantiator_type_args,
    const TypeArguments& function_type_args) {
  if (!subtype->IsInstantiated()) {
    *subtype =
        subtype->InstantiateFrom(instantiator_type_args, function_type_args,
                                 kAllFree, bound_error, NULL, NULL, Heap::kOld);
  }
  if (!bound_error->IsNull()) {
    return false;
  }
  if (!supertype->IsInstantiated()) {
    *supertype = supertype->InstantiateFrom(
        instantiator_type_args, function_type_args, kAllFree, bound_error, NULL,
        NULL, Heap::kOld);
  }
  if (!bound_error->IsNull()) {
    return false;
  }
  bool is_subtype_of =
      subtype->IsSubtypeOf(*supertype, bound_error, NULL, Heap::kOld);
  if (!bound_error->IsNull()) {
    return false;
  }
  return is_subtype_of;
}

RawArray* Class::invocation_dispatcher_cache() const {
  return raw_ptr()->invocation_dispatcher_cache_;
}

void Class::set_invocation_dispatcher_cache(const Array& cache) const {
  StorePointer(&raw_ptr()->invocation_dispatcher_cache_, cache.raw());
}

void Class::Finalize() const {
  ASSERT(Thread::Current()->IsMutatorThread());
  ASSERT(!Isolate::Current()->all_classes_finalized());
  ASSERT(!is_finalized());
  // Prefinalized classes have a VM internal representation and no Dart fields.
  // Their instance size  is precomputed and field offsets are known.
  if (!is_prefinalized()) {
    // Compute offsets of instance fields and instance size.
    CalculateFieldOffsets();
  }
  set_is_finalized();
}

class CHACodeArray : public WeakCodeReferences {
 public:
  explicit CHACodeArray(const Class& cls)
      : WeakCodeReferences(Array::Handle(cls.dependent_code())), cls_(cls) {}

  virtual void UpdateArrayTo(const Array& value) {
    // TODO(fschneider): Fails for classes in the VM isolate.
    cls_.set_dependent_code(value);
  }

  virtual void ReportDeoptimization(const Code& code) {
    if (FLAG_trace_deoptimization || FLAG_trace_deoptimization_verbose) {
      Function& function = Function::Handle(code.function());
      THR_Print("Deoptimizing %s because CHA optimized (%s).\n",
                function.ToFullyQualifiedCString(), cls_.ToCString());
    }
  }

  virtual void ReportSwitchingCode(const Code& code) {
    if (FLAG_trace_deoptimization || FLAG_trace_deoptimization_verbose) {
      Function& function = Function::Handle(code.function());
      THR_Print(
          "Switching %s to unoptimized code because CHA invalid"
          " (%s)\n",
          function.ToFullyQualifiedCString(), cls_.ToCString());
    }
  }

 private:
  const Class& cls_;
  DISALLOW_COPY_AND_ASSIGN(CHACodeArray);
};

#if defined(DEBUG)
static bool IsMutatorOrAtSafepoint() {
  Thread* thread = Thread::Current();
  return thread->IsMutatorThread() || thread->IsAtSafepoint();
}
#endif

void Class::RegisterCHACode(const Code& code) {
  if (FLAG_trace_cha) {
    THR_Print("RegisterCHACode '%s' depends on class '%s'\n",
              Function::Handle(code.function()).ToQualifiedCString(),
              ToCString());
  }
  DEBUG_ASSERT(IsMutatorOrAtSafepoint());
  ASSERT(code.is_optimized());
  CHACodeArray a(*this);
  a.Register(code);
}

void Class::DisableCHAOptimizedCode(const Class& subclass) {
  ASSERT(Thread::Current()->IsMutatorThread());
  CHACodeArray a(*this);
  if (FLAG_trace_deoptimization && a.HasCodes() && !subclass.IsNull()) {
    THR_Print("Adding subclass %s\n", subclass.ToCString());
  }
  a.DisableCode();
}

void Class::DisableAllCHAOptimizedCode() {
  DisableCHAOptimizedCode(Class::Handle());
}

bool Class::TraceAllocation(Isolate* isolate) const {
#ifndef PRODUCT
  ClassTable* class_table = isolate->class_table();
  return class_table->TraceAllocationFor(id());
#else
  return false;
#endif
}

void Class::SetTraceAllocation(bool trace_allocation) const {
#ifndef PRODUCT
  Isolate* isolate = Isolate::Current();
  const bool changed = trace_allocation != this->TraceAllocation(isolate);
  if (changed) {
    ClassTable* class_table = isolate->class_table();
    class_table->SetTraceAllocationFor(id(), trace_allocation);
    DisableAllocationStub();
  }
#else
  UNREACHABLE();
#endif
}

bool Class::ValidatePostFinalizePatch(const Class& orig_class,
                                      Error* error) const {
  ASSERT(error != NULL);
  // Not allowed to add new fields in a post finalization patch.
  if (fields() != Object::empty_array().raw()) {
    *error = LanguageError::NewFormatted(
        *error,  // No previous error.
        Script::Handle(script()), token_pos(), Report::AtLocation,
        Report::kError, Heap::kNew,
        "new fields are not allowed for this patch");
    return false;
  }
  // There seem to be no functions, the patch is pointless.
  if (functions() == Object::empty_array().raw()) {
    *error = LanguageError::NewFormatted(*error,  // No previous error.
                                         Script::Handle(script()), token_pos(),
                                         Report::AtLocation, Report::kError,
                                         Heap::kNew, "no functions to patch");
    return false;
  }
  // Iterate over all functions that will be patched and make sure
  // the original function was declared 'external' and has not executed
  // so far i.e no code has been generated for it.
  Thread* thread = Thread::Current();
  ASSERT(thread->IsMutatorThread());
  Zone* zone = thread->zone();
  const Array& funcs = Array::Handle(zone, functions());
  Function& func = Function::Handle(zone);
  Function& orig_func = Function::Handle(zone);
  String& name = String::Handle(zone);
  for (intptr_t i = 0; i < funcs.Length(); i++) {
    func ^= funcs.At(i);
    name ^= func.name();
    orig_func ^= orig_class.LookupFunctionAllowPrivate(name);
    if (!orig_func.IsNull()) {
      if (!orig_func.is_external() || orig_func.HasCode()) {
        // We can only patch external functions in a post finalized class.
        *error = LanguageError::NewFormatted(
            *error,  // No previous error.
            Script::Handle(script()), token_pos(), Report::AtLocation,
            Report::kError, Heap::kNew,
            !orig_func.is_external()
                ? "'%s' is not external and therefore cannot be patched"
                : "'%s' has already executed and therefore cannot be patched",
            name.ToCString());
        return false;
      }
    } else if (!Library::IsPrivate(name)) {
      // We can only have new private functions that are added.
      *error = LanguageError::NewFormatted(
          *error,  // No previous error.
          Script::Handle(script()), token_pos(), Report::AtLocation,
          Report::kError, Heap::kNew,
          "'%s' is not private and therefore cannot be patched",
          name.ToCString());
      return false;
    }
  }
  return true;
}

void Class::set_dependent_code(const Array& array) const {
  StorePointer(&raw_ptr()->dependent_code_, array.raw());
}

// Apply the members from the patch class to the original class.
bool Class::ApplyPatch(const Class& patch, Error* error) const {
  ASSERT(error != NULL);
  ASSERT(!is_finalized());
  // Shared handles used during the iteration.
  String& member_name = String::Handle();

  const PatchClass& patch_class = PatchClass::Handle(
      PatchClass::New(*this, Script::Handle(patch.script())));

  Array& orig_list = Array::Handle(functions());
  intptr_t orig_len = orig_list.Length();
  Array& patch_list = Array::Handle(patch.functions());
  intptr_t patch_len = patch_list.Length();

  Function& func = Function::Handle();
  Function& orig_func = Function::Handle();
  // Lookup the original implicit constructor, if any.
  member_name = Name();
  member_name = String::Concat(member_name, Symbols::Dot());
  Function& orig_implicit_ctor = Function::Handle(LookupFunction(member_name));
  if (!orig_implicit_ctor.IsNull() &&
      !orig_implicit_ctor.IsImplicitConstructor()) {
    // Not an implicit constructor, but a user declared one.
    orig_implicit_ctor = Function::null();
  }
  const GrowableObjectArray& new_functions =
      GrowableObjectArray::Handle(GrowableObjectArray::New(orig_len));
  for (intptr_t i = 0; i < orig_len; i++) {
    orig_func ^= orig_list.At(i);
    member_name ^= orig_func.name();
    func = patch.LookupFunction(member_name);
    if (func.IsNull()) {
      // Non-patched function is preserved, all patched functions are added in
      // the loop below.
      // However, an implicitly created constructor should not be preserved if
      // the patch provides a constructor or a factory. Wait for now.
      if (orig_func.raw() != orig_implicit_ctor.raw()) {
        new_functions.Add(orig_func);
      }
    } else if (func.UserVisibleSignature() !=
               orig_func.UserVisibleSignature()) {
      // Compare user visible signatures to ignore different implicit parameters
      // when patching a constructor with a factory.
      *error = LanguageError::NewFormatted(
          *error,  // No previous error.
          Script::Handle(patch.script()), func.token_pos(), Report::AtLocation,
          Report::kError, Heap::kNew, "signature mismatch: '%s'",
          member_name.ToCString());
      return false;
    }
  }
  for (intptr_t i = 0; i < patch_len; i++) {
    func ^= patch_list.At(i);
    if (func.IsGenerativeConstructor() || func.IsFactory()) {
      // Do not preserve the original implicit constructor, if any.
      orig_implicit_ctor = Function::null();
    }
    func.set_owner(patch_class);
    new_functions.Add(func);
  }
  if (!orig_implicit_ctor.IsNull()) {
    // Preserve the original implicit constructor.
    new_functions.Add(orig_implicit_ctor);
  }
  Array& new_list = Array::Handle(Array::MakeFixedLength(new_functions));
  SetFunctions(new_list);

  // Merge the two list of fields. Raise an error when duplicates are found or
  // when a public field is being added.
  orig_list = fields();
  orig_len = orig_list.Length();
  patch_list = patch.fields();
  patch_len = patch_list.Length();

  Field& field = Field::Handle();
  Field& orig_field = Field::Handle();
  new_list = Array::New(patch_len + orig_len);
  for (intptr_t i = 0; i < patch_len; i++) {
    field ^= patch_list.At(i);
    field.set_owner(patch_class);
    member_name = field.name();
    // TODO(iposva): Verify non-public fields only.

    // Verify no duplicate additions.
    orig_field ^= LookupField(member_name);
    if (!orig_field.IsNull()) {
      *error = LanguageError::NewFormatted(
          *error,  // No previous error.
          Script::Handle(patch.script()), field.token_pos(), Report::AtLocation,
          Report::kError, Heap::kNew, "duplicate field: %s",
          member_name.ToCString());
      return false;
    }
    new_list.SetAt(i, field);
  }
  for (intptr_t i = 0; i < orig_len; i++) {
    field ^= orig_list.At(i);
    new_list.SetAt(patch_len + i, field);
  }
  SetFields(new_list);

  // The functions and fields in the patch class are no longer needed.
  // The patch class itself is also no longer needed.
  patch.SetFunctions(Object::empty_array());
  patch.SetFields(Object::empty_array());
  Library::Handle(patch.library()).RemovePatchClass(patch);
  return true;
}

static RawString* BuildClosureSource(const Array& formal_params,
                                     const String& expr) {
  const GrowableObjectArray& src_pieces =
      GrowableObjectArray::Handle(GrowableObjectArray::New());
  String& piece = String::Handle();
  src_pieces.Add(Symbols::LParen());
  // Add formal parameters.
  intptr_t num_formals = formal_params.Length();
  for (intptr_t i = 0; i < num_formals; i++) {
    if (i > 0) {
      src_pieces.Add(Symbols::CommaSpace());
    }
    piece ^= formal_params.At(i);
    src_pieces.Add(piece);
  }
  src_pieces.Add(Symbols::RParenArrow());
  src_pieces.Add(expr);
  src_pieces.Add(Symbols::Semicolon());
  return String::ConcatAll(Array::Handle(Array::MakeFixedLength(src_pieces)));
}

RawFunction* Function::EvaluateHelper(const Class& cls,
                                      const String& expr,
                                      const Array& param_names,
                                      bool is_static) {
  const String& func_src =
      String::Handle(BuildClosureSource(param_names, expr));
  Script& script = Script::Handle();
  script =
      Script::New(Symbols::EvalSourceUri(), func_src, RawScript::kEvaluateTag);
  // In order to tokenize the source, we need to get the key to mangle
  // private names from the library from which the class originates.
  const Library& lib = Library::Handle(cls.library());
  ASSERT(!lib.IsNull());
  const String& lib_key = String::Handle(lib.private_key());
  script.Tokenize(lib_key, false);

  const Function& func =
      Function::Handle(Function::NewEvalFunction(cls, script, is_static));
  func.set_result_type(Object::dynamic_type());
  const intptr_t num_implicit_params = is_static ? 0 : 1;
  func.set_num_fixed_parameters(num_implicit_params + param_names.Length());
  func.SetNumOptionalParameters(0, true);
  func.SetIsOptimizable(false);
  return func.raw();
}

RawObject* Class::Evaluate(const String& expr,
                           const Array& param_names,
                           const Array& param_values) const {
  ASSERT(Thread::Current()->IsMutatorThread());
  if (id() < kInstanceCid) {
    const Instance& exception = Instance::Handle(
        String::New("Cannot evaluate against a VM internal class"));
    const Instance& stacktrace = Instance::Handle();
    return UnhandledException::New(exception, stacktrace);
  }

  const Function& eval_func = Function::Handle(
      Function::EvaluateHelper(*this, expr, param_names, true));
  const Object& result =
      Object::Handle(DartEntry::InvokeFunction(eval_func, param_values));
  return result.raw();
}

// Ensure that top level parsing of the class has been done.
RawError* Class::EnsureIsFinalized(Thread* thread) const {
  // Finalized classes have already been parsed.
  if (is_finalized()) {
    return Error::null();
  }
  if (Compiler::IsBackgroundCompilation()) {
    Compiler::AbortBackgroundCompilation(Thread::kNoDeoptId,
                                         "Class finalization while compiling");
  }
  ASSERT(thread->IsMutatorThread());
  ASSERT(thread != NULL);
  const Error& error =
      Error::Handle(thread->zone(), Compiler::CompileClass(*this));
  if (!error.IsNull()) {
    ASSERT(thread == Thread::Current());
    if (thread->long_jump_base() != NULL) {
      Report::LongJump(error);
      UNREACHABLE();
    }
  }
  return error.raw();
}

void Class::SetFields(const Array& value) const {
  ASSERT(!value.IsNull());
#if defined(DEBUG)
  // Verify that all the fields in the array have this class as owner.
  Field& field = Field::Handle();
  intptr_t len = value.Length();
  for (intptr_t i = 0; i < len; i++) {
    field ^= value.At(i);
    ASSERT(field.IsOriginal());
    ASSERT(field.Owner() == raw());
  }
#endif
  // The value of static fields is already initialized to null.
  StorePointer(&raw_ptr()->fields_, value.raw());
}

void Class::AddField(const Field& field) const {
  const Array& arr = Array::Handle(fields());
  const Array& new_arr = Array::Handle(Array::Grow(arr, arr.Length() + 1));
  new_arr.SetAt(arr.Length(), field);
  SetFields(new_arr);
}

void Class::AddFields(const GrowableArray<const Field*>& new_fields) const {
  const intptr_t num_new_fields = new_fields.length();
  if (num_new_fields == 0) return;
  const Array& arr = Array::Handle(fields());
  const intptr_t num_old_fields = arr.Length();
  const Array& new_arr = Array::Handle(
      Array::Grow(arr, num_old_fields + num_new_fields, Heap::kOld));
  for (intptr_t i = 0; i < num_new_fields; i++) {
    new_arr.SetAt(i + num_old_fields, *new_fields.At(i));
  }
  SetFields(new_arr);
}

void Class::InjectCIDFields() const {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  Field& field = Field::Handle(zone);
  Smi& value = Smi::Handle(zone);
  String& field_name = String::Handle(zone);

#define CLASS_LIST_WITH_NULL(V)                                                \
  V(Null)                                                                      \
  CLASS_LIST_NO_OBJECT(V)

#define ADD_SET_FIELD(clazz)                                                   \
  field_name = Symbols::New(thread, "cid" #clazz);                             \
  field = Field::New(field_name, true, false, true, false, *this,              \
                     Type::Handle(Type::IntType()), TokenPosition::kMinSource, \
                     TokenPosition::kMinSource);                               \
  value = Smi::New(k##clazz##Cid);                                             \
  field.SetStaticValue(value, true);                                           \
  AddField(field);

  CLASS_LIST_WITH_NULL(ADD_SET_FIELD)
#undef ADD_SET_FIELD
#undef CLASS_LIST_WITH_NULL
}

template <class FakeInstance>
RawClass* Class::NewCommon(intptr_t index) {
  ASSERT(Object::class_class() != Class::null());
  Class& result = Class::Handle();
  {
    RawObject* raw =
        Object::Allocate(Class::kClassId, Class::InstanceSize(), Heap::kOld);
    NoSafepointScope no_safepoint;
    result ^= raw;
  }
  FakeInstance fake;
  ASSERT(fake.IsInstance());
  result.set_handle_vtable(fake.vtable());
  result.set_token_pos(TokenPosition::kNoSource);
  result.set_instance_size(FakeInstance::InstanceSize());
  result.set_type_arguments_field_offset_in_words(kNoTypeArguments);
  result.set_next_field_offset(FakeInstance::NextFieldOffset());
  result.set_id(index);
  result.set_num_type_arguments(kUnknownNumTypeArguments);
  result.set_num_own_type_arguments(kUnknownNumTypeArguments);
  result.set_num_native_fields(0);
  result.set_state_bits(0);
  result.InitEmptyFields();
  return result.raw();
}

template <class FakeInstance>
RawClass* Class::New(intptr_t index) {
  Class& result = Class::Handle(NewCommon<FakeInstance>(index));
  result.set_kernel_offset(-1);
  Isolate::Current()->RegisterClass(result);
  return result.raw();
}

RawClass* Class::New(const Library& lib,
                     const String& name,
                     const Script& script,
                     TokenPosition token_pos) {
  Class& result = Class::Handle(NewCommon<Instance>(kIllegalCid));
  result.set_library(lib);
  result.set_name(name);
  result.set_script(script);
  result.set_token_pos(token_pos);
  result.set_kernel_offset(-1);
  Isolate::Current()->RegisterClass(result);
  return result.raw();
}

RawClass* Class::NewInstanceClass() {
  return Class::New<Instance>(kIllegalCid);
}

RawClass* Class::NewNativeWrapper(const Library& library,
                                  const String& name,
                                  int field_count) {
  Class& cls = Class::Handle(library.LookupClass(name));
  if (cls.IsNull()) {
    cls = New(library, name, Script::Handle(), TokenPosition::kNoSource);
    cls.SetFields(Object::empty_array());
    cls.SetFunctions(Object::empty_array());
    // Set super class to Object.
    cls.set_super_type(Type::Handle(Type::ObjectType()));
    // Compute instance size. First word contains a pointer to a properly
    // sized typed array once the first native field has been set.
    intptr_t instance_size = sizeof(RawInstance) + kWordSize;
    cls.set_instance_size(RoundedAllocationSize(instance_size));
    cls.set_next_field_offset(instance_size);
    cls.set_num_native_fields(field_count);
    cls.set_is_finalized();
    cls.set_is_type_finalized();
    cls.set_is_synthesized_class();
    cls.set_is_cycle_free();
    cls.set_kernel_offset(-1);
    library.AddClass(cls);
    return cls.raw();
  } else {
    return Class::null();
  }
}

RawClass* Class::NewStringClass(intptr_t class_id) {
  intptr_t instance_size;
  if (class_id == kOneByteStringCid) {
    instance_size = OneByteString::InstanceSize();
  } else if (class_id == kTwoByteStringCid) {
    instance_size = TwoByteString::InstanceSize();
  } else if (class_id == kExternalOneByteStringCid) {
    instance_size = ExternalOneByteString::InstanceSize();
  } else {
    ASSERT(class_id == kExternalTwoByteStringCid);
    instance_size = ExternalTwoByteString::InstanceSize();
  }
  Class& result = Class::Handle(New<String>(class_id));
  result.set_instance_size(instance_size);
  result.set_next_field_offset(String::NextFieldOffset());
  result.set_is_prefinalized();
  return result.raw();
}

RawClass* Class::NewTypedDataClass(intptr_t class_id) {
  ASSERT(RawObject::IsTypedDataClassId(class_id));
  intptr_t instance_size = TypedData::InstanceSize();
  Class& result = Class::Handle(New<TypedData>(class_id));
  result.set_instance_size(instance_size);
  result.set_next_field_offset(TypedData::NextFieldOffset());
  result.set_is_prefinalized();
  return result.raw();
}

RawClass* Class::NewTypedDataViewClass(intptr_t class_id) {
  ASSERT(RawObject::IsTypedDataViewClassId(class_id));
  Class& result = Class::Handle(New<Instance>(class_id));
  result.set_instance_size(0);
  result.set_next_field_offset(-kWordSize);
  return result.raw();
}

RawClass* Class::NewExternalTypedDataClass(intptr_t class_id) {
  ASSERT(RawObject::IsExternalTypedDataClassId(class_id));
  intptr_t instance_size = ExternalTypedData::InstanceSize();
  Class& result = Class::Handle(New<ExternalTypedData>(class_id));
  result.set_instance_size(instance_size);
  result.set_next_field_offset(ExternalTypedData::NextFieldOffset());
  result.set_is_prefinalized();
  return result.raw();
}

void Class::set_name(const String& value) const {
  ASSERT(raw_ptr()->name_ == String::null());
  ASSERT(value.IsSymbol());
  StorePointer(&raw_ptr()->name_, value.raw());
#if !defined(PRODUCT)
  if (raw_ptr()->user_name_ == String::null()) {
    // TODO(johnmccutchan): Eagerly set user name for VM isolate classes,
    // lazily set user name for the other classes.
    // Generate and set user_name.
    const String& user_name = String::Handle(GenerateUserVisibleName());
    set_user_name(user_name);
  }
#endif  // !defined(PRODUCT)
}

#if !defined(PRODUCT)
void Class::set_user_name(const String& value) const {
  StorePointer(&raw_ptr()->user_name_, value.raw());
}
#endif  // !defined(PRODUCT)

RawString* Class::GenerateUserVisibleName() const {
  if (FLAG_show_internal_names) {
    return Name();
  }
  switch (id()) {
    case kFloat32x4Cid:
      return Symbols::Float32x4().raw();
    case kInt32x4Cid:
      return Symbols::Int32x4().raw();
    case kTypedDataInt8ArrayCid:
    case kExternalTypedDataInt8ArrayCid:
      return Symbols::Int8List().raw();
    case kTypedDataUint8ArrayCid:
    case kExternalTypedDataUint8ArrayCid:
      return Symbols::Uint8List().raw();
    case kTypedDataUint8ClampedArrayCid:
    case kExternalTypedDataUint8ClampedArrayCid:
      return Symbols::Uint8ClampedList().raw();
    case kTypedDataInt16ArrayCid:
    case kExternalTypedDataInt16ArrayCid:
      return Symbols::Int16List().raw();
    case kTypedDataUint16ArrayCid:
    case kExternalTypedDataUint16ArrayCid:
      return Symbols::Uint16List().raw();
    case kTypedDataInt32ArrayCid:
    case kExternalTypedDataInt32ArrayCid:
      return Symbols::Int32List().raw();
    case kTypedDataUint32ArrayCid:
    case kExternalTypedDataUint32ArrayCid:
      return Symbols::Uint32List().raw();
    case kTypedDataInt64ArrayCid:
    case kExternalTypedDataInt64ArrayCid:
      return Symbols::Int64List().raw();
    case kTypedDataUint64ArrayCid:
    case kExternalTypedDataUint64ArrayCid:
      return Symbols::Uint64List().raw();
    case kTypedDataInt32x4ArrayCid:
    case kExternalTypedDataInt32x4ArrayCid:
      return Symbols::Int32x4List().raw();
    case kTypedDataFloat32x4ArrayCid:
    case kExternalTypedDataFloat32x4ArrayCid:
      return Symbols::Float32x4List().raw();
    case kTypedDataFloat64x2ArrayCid:
    case kExternalTypedDataFloat64x2ArrayCid:
      return Symbols::Float64x2List().raw();
    case kTypedDataFloat32ArrayCid:
    case kExternalTypedDataFloat32ArrayCid:
      return Symbols::Float32List().raw();
    case kTypedDataFloat64ArrayCid:
    case kExternalTypedDataFloat64ArrayCid:
      return Symbols::Float64List().raw();

#if !defined(PRODUCT)
    case kNullCid:
      return Symbols::Null().raw();
    case kDynamicCid:
      return Symbols::Dynamic().raw();
    case kVoidCid:
      return Symbols::Void().raw();
    case kClassCid:
      return Symbols::Class().raw();
    case kUnresolvedClassCid:
      return Symbols::UnresolvedClass().raw();
    case kTypeArgumentsCid:
      return Symbols::TypeArguments().raw();
    case kPatchClassCid:
      return Symbols::PatchClass().raw();
    case kFunctionCid:
      return Symbols::Function().raw();
    case kClosureDataCid:
      return Symbols::ClosureData().raw();
    case kSignatureDataCid:
      return Symbols::SignatureData().raw();
    case kRedirectionDataCid:
      return Symbols::RedirectionData().raw();
    case kFieldCid:
      return Symbols::Field().raw();
    case kLiteralTokenCid:
      return Symbols::LiteralToken().raw();
    case kTokenStreamCid:
      return Symbols::TokenStream().raw();
    case kScriptCid:
      return Symbols::Script().raw();
    case kLibraryCid:
      return Symbols::Library().raw();
    case kLibraryPrefixCid:
      return Symbols::LibraryPrefix().raw();
    case kNamespaceCid:
      return Symbols::Namespace().raw();
    case kKernelProgramInfoCid:
      return Symbols::KernelProgramInfo().raw();
    case kCodeCid:
      return Symbols::Code().raw();
    case kInstructionsCid:
      return Symbols::Instructions().raw();
    case kObjectPoolCid:
      return Symbols::ObjectPool().raw();
    case kCodeSourceMapCid:
      return Symbols::CodeSourceMap().raw();
    case kPcDescriptorsCid:
      return Symbols::PcDescriptors().raw();
    case kStackMapCid:
      return Symbols::StackMap().raw();
    case kLocalVarDescriptorsCid:
      return Symbols::LocalVarDescriptors().raw();
    case kExceptionHandlersCid:
      return Symbols::ExceptionHandlers().raw();
    case kContextCid:
      return Symbols::Context().raw();
    case kContextScopeCid:
      return Symbols::ContextScope().raw();
    case kSingleTargetCacheCid:
      return Symbols::SingleTargetCache().raw();
    case kICDataCid:
      return Symbols::ICData().raw();
    case kMegamorphicCacheCid:
      return Symbols::MegamorphicCache().raw();
    case kSubtypeTestCacheCid:
      return Symbols::SubtypeTestCache().raw();
    case kApiErrorCid:
      return Symbols::ApiError().raw();
    case kLanguageErrorCid:
      return Symbols::LanguageError().raw();
    case kUnhandledExceptionCid:
      return Symbols::UnhandledException().raw();
    case kUnwindErrorCid:
      return Symbols::UnwindError().raw();
    case kIntegerCid:
    case kSmiCid:
    case kMintCid:
    case kBigintCid:
      return Symbols::Int().raw();
    case kDoubleCid:
      return Symbols::Double().raw();
    case kOneByteStringCid:
    case kTwoByteStringCid:
    case kExternalOneByteStringCid:
    case kExternalTwoByteStringCid:
      return Symbols::_String().raw();
    case kArrayCid:
    case kImmutableArrayCid:
    case kGrowableObjectArrayCid:
      return Symbols::List().raw();
#endif  // !defined(PRODUCT)
  }
  const String& name = String::Handle(Name());
  return String::ScrubName(name);
}

void Class::set_script(const Script& value) const {
  StorePointer(&raw_ptr()->script_, value.raw());
}

void Class::set_token_pos(TokenPosition token_pos) const {
  ASSERT(!token_pos.IsClassifying());
  StoreNonPointer(&raw_ptr()->token_pos_, token_pos);
}

TokenPosition Class::ComputeEndTokenPos() const {
#if defined(DART_PRECOMPILED_RUNTIME)
  return TokenPosition::kNoSource;
#else
  // Return the begin token for synthetic classes.
  if (is_synthesized_class() || IsMixinApplication() || IsTopLevel()) {
    return token_pos();
  }

  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  const Script& scr = Script::Handle(zone, script());
  ASSERT(!scr.IsNull());

  if (scr.kind() == RawScript::kKernelTag) {
    ASSERT(kernel_offset() > 0);
    const Library& lib = Library::Handle(zone, library());
    const TypedData& kernel_data = TypedData::Handle(zone, lib.kernel_data());
    ASSERT(!kernel_data.IsNull());
    const intptr_t library_kernel_offset = lib.kernel_offset();
    ASSERT(library_kernel_offset > 0);
    const intptr_t class_offset = kernel_offset();

    kernel::TranslationHelper helper(thread);
    helper.InitFromScript(scr);
    kernel::StreamingFlowGraphBuilder builder_(&helper, scr, zone, kernel_data,
                                               0);
    builder_.SetOffset(class_offset);
    kernel::ClassHelper class_helper(&builder_);
    class_helper.ReadUntilIncluding(kernel::ClassHelper::kEndPosition);
    if (class_helper.end_position_.IsReal()) return class_helper.end_position_;

    TokenPosition largest_seen = token_pos();

    // Walk through all functions and get their end_tokens to find the classes
    // "end token".
    // TODO(jensj): Should probably walk though all fields as well.
    Function& function = Function::Handle(zone);
    const Array& arr = Array::Handle(functions());
    for (int i = 0; i < arr.Length(); i++) {
      function ^= arr.At(i);
      if (function.script() == script()) {
        if (largest_seen < function.end_token_pos()) {
          largest_seen = function.end_token_pos();
        }
      }
    }
    return TokenPosition(largest_seen);
  }

  const TokenStream& tkns = TokenStream::Handle(zone, scr.tokens());
  if (tkns.IsNull()) {
    ASSERT(Dart::vm_snapshot_kind() == Snapshot::kFullAOT);
    return TokenPosition::kNoSource;
  }
  TokenStream::Iterator tkit(zone, tkns, token_pos(),
                             TokenStream::Iterator::kNoNewlines);
  intptr_t level = 0;
  while (tkit.CurrentTokenKind() != Token::kEOS) {
    if (tkit.CurrentTokenKind() == Token::kLBRACE) {
      level++;
    } else if (tkit.CurrentTokenKind() == Token::kRBRACE) {
      if (--level == 0) {
        return tkit.CurrentPosition();
      }
    }
    tkit.Advance();
  }
  UNREACHABLE();
  return TokenPosition::kNoSource;
#endif
}

int32_t Class::SourceFingerprint() const {
  return Script::Handle(script()).SourceFingerprint(token_pos(),
                                                    ComputeEndTokenPos());
}

void Class::set_is_implemented() const {
  set_state_bits(ImplementedBit::update(true, raw_ptr()->state_bits_));
}

void Class::set_is_abstract() const {
  set_state_bits(AbstractBit::update(true, raw_ptr()->state_bits_));
}

void Class::set_is_type_finalized() const {
  set_state_bits(TypeFinalizedBit::update(true, raw_ptr()->state_bits_));
}

void Class::set_is_patch() const {
  set_state_bits(PatchBit::update(true, raw_ptr()->state_bits_));
}

void Class::set_is_synthesized_class() const {
  set_state_bits(SynthesizedClassBit::update(true, raw_ptr()->state_bits_));
}

void Class::set_is_enum_class() const {
  set_state_bits(EnumBit::update(true, raw_ptr()->state_bits_));
}

void Class::set_is_const() const {
  set_state_bits(ConstBit::update(true, raw_ptr()->state_bits_));
}

void Class::set_is_mixin_app_alias() const {
  set_state_bits(MixinAppAliasBit::update(true, raw_ptr()->state_bits_));
}

void Class::set_is_mixin_type_applied() const {
  set_state_bits(MixinTypeAppliedBit::update(true, raw_ptr()->state_bits_));
}

void Class::set_is_fields_marked_nullable() const {
  set_state_bits(FieldsMarkedNullableBit::update(true, raw_ptr()->state_bits_));
}

void Class::set_is_cycle_free() const {
  ASSERT(!is_cycle_free());
  set_state_bits(CycleFreeBit::update(true, raw_ptr()->state_bits_));
}

void Class::set_is_allocated(bool value) const {
  set_state_bits(IsAllocatedBit::update(value, raw_ptr()->state_bits_));
}

void Class::set_is_finalized() const {
  ASSERT(!is_finalized());
  set_state_bits(
      ClassFinalizedBits::update(RawClass::kFinalized, raw_ptr()->state_bits_));
}

void Class::SetRefinalizeAfterPatch() const {
  ASSERT(!IsTopLevel());
  set_state_bits(ClassFinalizedBits::update(RawClass::kRefinalizeAfterPatch,
                                            raw_ptr()->state_bits_));
  set_state_bits(TypeFinalizedBit::update(false, raw_ptr()->state_bits_));
}

void Class::ResetFinalization() const {
  ASSERT(IsTopLevel() || IsClosureClass());
  set_state_bits(
      ClassFinalizedBits::update(RawClass::kAllocated, raw_ptr()->state_bits_));
  set_state_bits(TypeFinalizedBit::update(false, raw_ptr()->state_bits_));
}

void Class::set_is_prefinalized() const {
  ASSERT(!is_finalized());
  set_state_bits(ClassFinalizedBits::update(RawClass::kPreFinalized,
                                            raw_ptr()->state_bits_));
}

void Class::set_is_marked_for_parsing() const {
  set_state_bits(MarkedForParsingBit::update(true, raw_ptr()->state_bits_));
}

void Class::reset_is_marked_for_parsing() const {
  set_state_bits(MarkedForParsingBit::update(false, raw_ptr()->state_bits_));
}

void Class::set_interfaces(const Array& value) const {
  ASSERT(!value.IsNull());
  StorePointer(&raw_ptr()->interfaces_, value.raw());
}

void Class::set_mixin(const Type& value) const {
  ASSERT(!value.IsNull());
  StorePointer(&raw_ptr()->mixin_, value.raw());
}

bool Class::IsMixinApplication() const {
  return mixin() != Type::null();
}

RawClass* Class::GetPatchClass() const {
  const Library& lib = Library::Handle(library());
  return lib.GetPatchClass(String::Handle(Name()));
}

void Class::AddDirectSubclass(const Class& subclass) const {
  ASSERT(!subclass.IsNull());
  ASSERT(subclass.SuperClass() == raw());
  // Do not keep track of the direct subclasses of class Object.
  ASSERT(!IsObjectClass());
  GrowableObjectArray& direct_subclasses =
      GrowableObjectArray::Handle(raw_ptr()->direct_subclasses_);
  if (direct_subclasses.IsNull()) {
    direct_subclasses = GrowableObjectArray::New(4, Heap::kOld);
    StorePointer(&raw_ptr()->direct_subclasses_, direct_subclasses.raw());
  }
#if defined(DEBUG)
  // Verify that the same class is not added twice.
  for (intptr_t i = 0; i < direct_subclasses.Length(); i++) {
    ASSERT(direct_subclasses.At(i) != subclass.raw());
  }
#endif
  direct_subclasses.Add(subclass, Heap::kOld);
}

void Class::ClearDirectSubclasses() const {
  StorePointer(&raw_ptr()->direct_subclasses_, GrowableObjectArray::null());
}

RawArray* Class::constants() const {
  return raw_ptr()->constants_;
}

void Class::set_constants(const Array& value) const {
  ASSERT(!value.IsNull());
  StorePointer(&raw_ptr()->constants_, value.raw());
}

RawType* Class::canonical_type() const {
  return raw_ptr()->canonical_type_;
}

void Class::set_canonical_type(const Type& value) const {
  ASSERT(!value.IsNull() && value.IsCanonical() && value.IsOld());
  StorePointer(&raw_ptr()->canonical_type_, value.raw());
}

RawType* Class::CanonicalType() const {
  return raw_ptr()->canonical_type_;
}

void Class::SetCanonicalType(const Type& type) const {
  ASSERT((canonical_type() == Object::null()) ||
         (canonical_type() == type.raw()));  // Set during own finalization.
  set_canonical_type(type);
}

void Class::set_allocation_stub(const Code& value) const {
  // Never clear the stub as it may still be a target, but will be GC-d if
  // not referenced.
  ASSERT(!value.IsNull());
  ASSERT(raw_ptr()->allocation_stub_ == Code::null());
  StorePointer(&raw_ptr()->allocation_stub_, value.raw());
}

void Class::DisableAllocationStub() const {
  const Code& existing_stub = Code::Handle(allocation_stub());
  if (existing_stub.IsNull()) {
    return;
  }
  ASSERT(!existing_stub.IsDisabled());
  // Change the stub so that the next caller will regenerate the stub.
  existing_stub.DisableStubCode();
  // Disassociate the existing stub from class.
  StorePointer(&raw_ptr()->allocation_stub_, Code::null());
}

bool Class::IsDartFunctionClass() const {
  return raw() == Type::Handle(Type::DartFunctionType()).type_class();
}

bool Class::IsFutureClass() const {
  // Looking up future_class in the object store would not work, because
  // this function is called during class finalization, before the object store
  // field would be initialized by InitKnownObjects().
  return (Name() == Symbols::Future().raw()) &&
         (library() == Library::AsyncLibrary());
}

bool Class::IsFutureOrClass() const {
  // Looking up future_or_class in the object store would not work, because
  // this function is called during class finalization, before the object store
  // field would be initialized by InitKnownObjects().
  return (Name() == Symbols::FutureOr().raw()) &&
         (library() == Library::AsyncLibrary());
}

// If test_kind == kIsSubtypeOf, checks if type S is a subtype of type T.
// If test_kind == kIsMoreSpecificThan, checks if S is more specific than T.
// Type S is specified by this class parameterized with 'type_arguments', and
// type T by class 'other' parameterized with 'other_type_arguments'.
// This class and class 'other' do not need to be finalized, however, they must
// be resolved as well as their interfaces.
bool Class::TypeTestNonRecursive(const Class& cls,
                                 Class::TypeTestKind test_kind,
                                 const TypeArguments& type_arguments,
                                 const Class& other,
                                 const TypeArguments& other_type_arguments,
                                 Error* bound_error,
                                 TrailPtr bound_trail,
                                 Heap::Space space) {
  // Use the 'this_class' object as if it was the receiver of this method, but
  // instead of recursing, reset it to the super class and loop.
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  Isolate* isolate = thread->isolate();
  Class& this_class = Class::Handle(zone, cls.raw());
  while (true) {
    // Each occurrence of DynamicType in type T is interpreted as the dynamic
    // type, a supertype of all types. So are Object and void types.
    if (other.IsDynamicClass() || other.IsObjectClass() ||
        other.IsVoidClass()) {
      return true;
    }
    // Check for NullType, which, as of Dart 1.5, is a subtype of (and is more
    // specific than) any type. Note that the null instance is not handled here.
    if (this_class.IsNullClass()) {
      return true;
    }
    // Class FutureOr is mapped to dynamic in non-strong mode.
    // Detect snapshots compiled in strong mode and run in non-strong mode.
    ASSERT(isolate->strong() || !other.IsFutureOrClass());
    // In strong mode, check if 'other' is 'FutureOr'.
    // If so, apply additional subtyping rules.
    if (isolate->strong() &&
        this_class.FutureOrTypeTest(zone, type_arguments, other,
                                    other_type_arguments, bound_error,
                                    bound_trail, space)) {
      return true;
    }
    // In the case of a subtype test, each occurrence of DynamicType in type S
    // is interpreted as the bottom type, a subtype of all types, but not in
    // strong mode.
    // However, DynamicType is not more specific than any type.
    if (this_class.IsDynamicClass()) {
      return !isolate->strong() && (test_kind == Class::kIsSubtypeOf);
    }
    // If other is neither Object, dynamic or void, then ObjectType/VoidType
    // can't be a subtype of other.
    if (this_class.IsObjectClass() || this_class.IsVoidClass()) {
      return false;
    }
    // Check for reflexivity.
    if (this_class.raw() == other.raw()) {
      const intptr_t num_type_params = this_class.NumTypeParameters();
      if (num_type_params == 0) {
        return true;
      }
      const intptr_t num_type_args = this_class.NumTypeArguments();
      const intptr_t from_index = num_type_args - num_type_params;
      // Since we do not truncate the type argument vector of a subclass (see
      // below), we only check a subvector of the proper length.
      // Check for covariance.
      if (other_type_arguments.IsNull() ||
          other_type_arguments.IsTopTypes(from_index, num_type_params)) {
        return true;
      }
      if (type_arguments.IsNull() ||
          type_arguments.IsRaw(from_index, num_type_params)) {
        // Other type can't be more specific than this one because for that
        // it would have to have all dynamic type arguments which is checked
        // above.
        return !isolate->strong() && (test_kind == Class::kIsSubtypeOf);
      }
      return type_arguments.TypeTest(test_kind, other_type_arguments,
                                     from_index, num_type_params, bound_error,
                                     bound_trail, space);
    }
    // In strong mode, subtyping rules of callable instances are restricted.
    if (!isolate->strong() && other.IsDartFunctionClass()) {
      // Check if type S has a call() method.
      const Function& call_function =
          Function::Handle(zone, this_class.LookupCallFunctionForTypeTest());
      if (!call_function.IsNull()) {
        return true;
      }
    }
    // Check for 'direct super type' specified in the implements clause
    // and check for transitivity at the same time.
    Array& interfaces = Array::Handle(zone, this_class.interfaces());
    AbstractType& interface = AbstractType::Handle(zone);
    Class& interface_class = Class::Handle(zone);
    TypeArguments& interface_args = TypeArguments::Handle(zone);
    Error& error = Error::Handle(zone);
    for (intptr_t i = 0; i < interfaces.Length(); i++) {
      interface ^= interfaces.At(i);
      if (!interface.IsFinalized()) {
        // We may be checking bounds at finalization time and can encounter
        // a still unfinalized interface.
        if (interface.IsBeingFinalized()) {
          // Interface is part of a still unfinalized recursive type graph.
          // Skip it. The caller will create a bounded type to be checked at
          // runtime if this type test returns false at compile time.
          continue;
        }
        ClassFinalizer::FinalizeType(this_class, interface);
        interfaces.SetAt(i, interface);
      }
      if (interface.IsMalbounded()) {
        // Return the first bound error to the caller if it requests it.
        if ((bound_error != NULL) && bound_error->IsNull()) {
          *bound_error = interface.error();
        }
        continue;  // Another interface may work better.
      }
      interface_class = interface.type_class();
      interface_args = interface.arguments();
      if (!interface_args.IsNull() && !interface_args.IsInstantiated()) {
        // This type class implements an interface that is parameterized with
        // generic type(s), e.g. it implements List<T>.
        // The uninstantiated type T must be instantiated using the type
        // parameters of this type before performing the type test.
        // The type arguments of this type that are referred to by the type
        // parameters of the interface are at the end of the type vector,
        // after the type arguments of the super type of this type.
        // The index of the type parameters is adjusted upon finalization.
        error = Error::null();
        interface_args = interface_args.InstantiateFrom(
            type_arguments, Object::null_type_arguments(), kNoneFree, &error,
            NULL, bound_trail, space);
        if (!error.IsNull()) {
          // Return the first bound error to the caller if it requests it.
          if ((bound_error != NULL) && bound_error->IsNull()) {
            *bound_error = error.raw();
          }
          continue;  // Another interface may work better.
        }
      }
      if (interface_class.TypeTest(test_kind, interface_args, other,
                                   other_type_arguments, bound_error,
                                   bound_trail, space)) {
        return true;
      }
    }
    // "Recurse" up the class hierarchy until we have reached the top.
    this_class = this_class.SuperClass();
    if (this_class.IsNull()) {
      return false;
    }
  }
  UNREACHABLE();
  return false;
}

// If test_kind == kIsSubtypeOf, checks if type S is a subtype of type T.
// If test_kind == kIsMoreSpecificThan, checks if S is more specific than T.
// Type S is specified by this class parameterized with 'type_arguments', and
// type T by class 'other' parameterized with 'other_type_arguments'.
// This class and class 'other' do not need to be finalized, however, they must
// be resolved as well as their interfaces.
bool Class::TypeTest(TypeTestKind test_kind,
                     const TypeArguments& type_arguments,
                     const Class& other,
                     const TypeArguments& other_type_arguments,
                     Error* bound_error,
                     TrailPtr bound_trail,
                     Heap::Space space) const {
  return TypeTestNonRecursive(*this, test_kind, type_arguments, other,
                              other_type_arguments, bound_error, bound_trail,
                              space);
}

bool Class::FutureOrTypeTest(Zone* zone,
                             const TypeArguments& type_arguments,
                             const Class& other,
                             const TypeArguments& other_type_arguments,
                             Error* bound_error,
                             TrailPtr bound_trail,
                             Heap::Space space) const {
  // In strong mode, there is no difference between 'is subtype of' and
  // 'is more specific than'.
  ASSERT(Isolate::Current()->strong());
  if (other.IsFutureOrClass()) {
    if (other_type_arguments.IsNull()) {
      return true;
    }
    const AbstractType& other_type_arg =
        AbstractType::Handle(zone, other_type_arguments.TypeAt(0));
    if (other_type_arg.IsTopType()) {
      return true;
    }
    if (!type_arguments.IsNull() && IsFutureClass()) {
      const AbstractType& type_arg =
          AbstractType::Handle(zone, type_arguments.TypeAt(0));
      if (type_arg.TypeTest(Class::kIsSubtypeOf, other_type_arg, bound_error,
                            bound_trail, space)) {
        return true;
      }
    }
    if (other_type_arg.IsType() &&
        TypeTest(Class::kIsSubtypeOf, type_arguments,
                 Class::Handle(zone, other_type_arg.type_class()),
                 TypeArguments::Handle(other_type_arg.arguments()), bound_error,
                 bound_trail, space)) {
      return true;
    }
  }
  return false;
}

bool Class::IsTopLevel() const {
  return Name() == Symbols::TopLevel().raw();
}

bool Class::IsPrivate() const {
  return Library::IsPrivate(String::Handle(Name()));
}

RawFunction* Class::LookupDynamicFunction(const String& name) const {
  return LookupFunction(name, kInstance);
}

RawFunction* Class::LookupDynamicFunctionAllowAbstract(
    const String& name) const {
  return LookupFunction(name, kInstanceAllowAbstract);
}

RawFunction* Class::LookupDynamicFunctionAllowPrivate(
    const String& name) const {
  return LookupFunctionAllowPrivate(name, kInstance);
}

RawFunction* Class::LookupStaticFunction(const String& name) const {
  return LookupFunction(name, kStatic);
}

RawFunction* Class::LookupStaticFunctionAllowPrivate(const String& name) const {
  return LookupFunctionAllowPrivate(name, kStatic);
}

RawFunction* Class::LookupConstructor(const String& name) const {
  return LookupFunction(name, kConstructor);
}

RawFunction* Class::LookupConstructorAllowPrivate(const String& name) const {
  return LookupFunctionAllowPrivate(name, kConstructor);
}

RawFunction* Class::LookupFactory(const String& name) const {
  return LookupFunction(name, kFactory);
}

RawFunction* Class::LookupFactoryAllowPrivate(const String& name) const {
  return LookupFunctionAllowPrivate(name, kFactory);
}

RawFunction* Class::LookupFunction(const String& name) const {
  return LookupFunction(name, kAny);
}

RawFunction* Class::LookupFunctionAllowPrivate(const String& name) const {
  return LookupFunctionAllowPrivate(name, kAny);
}

RawFunction* Class::LookupCallFunctionForTypeTest() const {
  // If this class is not compiled yet, it is too early to lookup a call
  // function. This case should only occur during bounds checking at compile
  // time. Return null as if the call method did not exist, so the type test
  // may return false, but without a bound error, and the bound check will get
  // postponed to runtime.
  if (!is_finalized()) {
    return Function::null();
  }
  Zone* zone = Thread::Current()->zone();
  Class& cls = Class::Handle(zone, raw());
  Function& call_function = Function::Handle(zone);
  do {
    ASSERT(cls.is_finalized());
    call_function = cls.LookupDynamicFunctionAllowAbstract(Symbols::Call());
    cls = cls.SuperClass();
  } while (call_function.IsNull() && !cls.IsNull());
  if (!call_function.IsNull()) {
    // Make sure the signature is finalized before using it in a type test.
    ClassFinalizer::FinalizeSignature(
        cls, call_function, ClassFinalizer::kFinalize);  // No bounds checking.
  }
  return call_function.raw();
}

// Returns true if 'prefix' and 'accessor_name' match 'name'.
static bool MatchesAccessorName(const String& name,
                                const char* prefix,
                                intptr_t prefix_length,
                                const String& accessor_name) {
  intptr_t name_len = name.Length();
  intptr_t accessor_name_len = accessor_name.Length();

  if (name_len != (accessor_name_len + prefix_length)) {
    return false;
  }
  for (intptr_t i = 0; i < prefix_length; i++) {
    if (name.CharAt(i) != prefix[i]) {
      return false;
    }
  }
  for (intptr_t i = 0, j = prefix_length; i < accessor_name_len; i++, j++) {
    if (name.CharAt(j) != accessor_name.CharAt(i)) {
      return false;
    }
  }
  return true;
}

RawFunction* Class::CheckFunctionType(const Function& func, MemberKind kind) {
  if ((kind == kInstance) || (kind == kInstanceAllowAbstract)) {
    if (func.IsDynamicFunction(kind == kInstanceAllowAbstract)) {
      return func.raw();
    }
  } else if (kind == kStatic) {
    if (func.IsStaticFunction()) {
      return func.raw();
    }
  } else if (kind == kConstructor) {
    if (func.IsGenerativeConstructor()) {
      ASSERT(!func.is_static());
      return func.raw();
    }
  } else if (kind == kFactory) {
    if (func.IsFactory()) {
      ASSERT(func.is_static());
      return func.raw();
    }
  } else if (kind == kAny) {
    return func.raw();
  }
  return Function::null();
}

RawFunction* Class::LookupFunction(const String& name, MemberKind kind) const {
  Thread* thread = Thread::Current();
  if (EnsureIsFinalized(thread) != Error::null()) {
    return Function::null();
  }
  REUSABLE_ARRAY_HANDLESCOPE(thread);
  REUSABLE_FUNCTION_HANDLESCOPE(thread);
  Array& funcs = thread->ArrayHandle();
  funcs ^= functions();
  ASSERT(!funcs.IsNull());
  const intptr_t len = funcs.Length();
  Function& function = thread->FunctionHandle();
  if (len >= kFunctionLookupHashTreshold) {
    // Cache functions hash table to allow multi threaded access.
    const Array& hash_table =
        Array::Handle(thread->zone(), raw_ptr()->functions_hash_table_);
    if (!hash_table.IsNull()) {
      ClassFunctionsSet set(hash_table.raw());
      REUSABLE_STRING_HANDLESCOPE(thread);
      function ^= set.GetOrNull(FunctionName(name, &(thread->StringHandle())));
      // No mutations.
      ASSERT(set.Release().raw() == hash_table.raw());
      return function.IsNull() ? Function::null()
                               : CheckFunctionType(function, kind);
    }
  }
  if (name.IsSymbol()) {
    // Quick Symbol compare.
    NoSafepointScope no_safepoint;
    for (intptr_t i = 0; i < len; i++) {
      function ^= funcs.At(i);
      if (function.name() == name.raw()) {
        return CheckFunctionType(function, kind);
      }
    }
  } else {
    REUSABLE_STRING_HANDLESCOPE(thread);
    String& function_name = thread->StringHandle();
    for (intptr_t i = 0; i < len; i++) {
      function ^= funcs.At(i);
      function_name ^= function.name();
      if (function_name.Equals(name)) {
        return CheckFunctionType(function, kind);
      }
    }
  }
  // No function found.
  return Function::null();
}

RawFunction* Class::LookupFunctionAllowPrivate(const String& name,
                                               MemberKind kind) const {
  Thread* thread = Thread::Current();
  if (EnsureIsFinalized(thread) != Error::null()) {
    return Function::null();
  }
  REUSABLE_ARRAY_HANDLESCOPE(thread);
  REUSABLE_FUNCTION_HANDLESCOPE(thread);
  REUSABLE_STRING_HANDLESCOPE(thread);
  Array& funcs = thread->ArrayHandle();
  funcs ^= functions();
  ASSERT(!funcs.IsNull());
  const intptr_t len = funcs.Length();
  Function& function = thread->FunctionHandle();
  String& function_name = thread->StringHandle();
  for (intptr_t i = 0; i < len; i++) {
    function ^= funcs.At(i);
    function_name ^= function.name();
    if (String::EqualsIgnoringPrivateKey(function_name, name)) {
      return CheckFunctionType(function, kind);
    }
  }
  // No function found.
  return Function::null();
}

RawFunction* Class::LookupGetterFunction(const String& name) const {
  return LookupAccessorFunction(kGetterPrefix, kGetterPrefixLength, name);
}

RawFunction* Class::LookupSetterFunction(const String& name) const {
  return LookupAccessorFunction(kSetterPrefix, kSetterPrefixLength, name);
}

RawFunction* Class::LookupAccessorFunction(const char* prefix,
                                           intptr_t prefix_length,
                                           const String& name) const {
  Thread* thread = Thread::Current();
  if (EnsureIsFinalized(thread) != Error::null()) {
    return Function::null();
  }
  REUSABLE_ARRAY_HANDLESCOPE(thread);
  REUSABLE_FUNCTION_HANDLESCOPE(thread);
  REUSABLE_STRING_HANDLESCOPE(thread);
  Array& funcs = thread->ArrayHandle();
  funcs ^= functions();
  intptr_t len = funcs.Length();
  Function& function = thread->FunctionHandle();
  String& function_name = thread->StringHandle();
  for (intptr_t i = 0; i < len; i++) {
    function ^= funcs.At(i);
    function_name ^= function.name();
    if (MatchesAccessorName(function_name, prefix, prefix_length, name)) {
      return function.raw();
    }
  }

  // No function found.
  return Function::null();
}

RawField* Class::LookupInstanceField(const String& name) const {
  return LookupField(name, kInstance);
}

RawField* Class::LookupStaticField(const String& name) const {
  return LookupField(name, kStatic);
}

RawField* Class::LookupField(const String& name) const {
  return LookupField(name, kAny);
}

RawField* Class::LookupField(const String& name, MemberKind kind) const {
  Thread* thread = Thread::Current();
  if (EnsureIsFinalized(thread) != Error::null()) {
    return Field::null();
  }
  REUSABLE_ARRAY_HANDLESCOPE(thread);
  REUSABLE_FIELD_HANDLESCOPE(thread);
  REUSABLE_STRING_HANDLESCOPE(thread);
  Array& flds = thread->ArrayHandle();
  flds ^= fields();
  ASSERT(!flds.IsNull());
  intptr_t len = flds.Length();
  Field& field = thread->FieldHandle();
  if (name.IsSymbol()) {
    // Use fast raw pointer string compare for symbols.
    for (intptr_t i = 0; i < len; i++) {
      field ^= flds.At(i);
      if (name.raw() == field.name()) {
        if (kind == kInstance) {
          return field.is_static() ? Field::null() : field.raw();
        } else if (kind == kStatic) {
          return field.is_static() ? field.raw() : Field::null();
        }
        ASSERT(kind == kAny);
        return field.raw();
      }
    }
  } else {
    String& field_name = thread->StringHandle();
    for (intptr_t i = 0; i < len; i++) {
      field ^= flds.At(i);
      field_name ^= field.name();
      if (name.Equals(field_name)) {
        if (kind == kInstance) {
          return field.is_static() ? Field::null() : field.raw();
        } else if (kind == kStatic) {
          return field.is_static() ? field.raw() : Field::null();
        }
        ASSERT(kind == kAny);
        return field.raw();
      }
    }
  }
  return Field::null();
}

RawField* Class::LookupFieldAllowPrivate(const String& name,
                                         bool instance_only) const {
  // Use slow string compare, ignoring privacy name mangling.
  Thread* thread = Thread::Current();
  if (EnsureIsFinalized(thread) != Error::null()) {
    return Field::null();
  }
  REUSABLE_ARRAY_HANDLESCOPE(thread);
  REUSABLE_FIELD_HANDLESCOPE(thread);
  REUSABLE_STRING_HANDLESCOPE(thread);
  Array& flds = thread->ArrayHandle();
  flds ^= fields();
  ASSERT(!flds.IsNull());
  intptr_t len = flds.Length();
  Field& field = thread->FieldHandle();
  String& field_name = thread->StringHandle();
  for (intptr_t i = 0; i < len; i++) {
    field ^= flds.At(i);
    field_name ^= field.name();
    if (field.is_static() && instance_only) {
      // If we only care about instance fields, skip statics.
      continue;
    }
    if (String::EqualsIgnoringPrivateKey(field_name, name)) {
      return field.raw();
    }
  }
  return Field::null();
}

RawField* Class::LookupInstanceFieldAllowPrivate(const String& name) const {
  Field& field = Field::Handle(LookupFieldAllowPrivate(name, true));
  if (!field.IsNull() && !field.is_static()) {
    return field.raw();
  }
  return Field::null();
}

RawField* Class::LookupStaticFieldAllowPrivate(const String& name) const {
  Field& field = Field::Handle(LookupFieldAllowPrivate(name));
  if (!field.IsNull() && field.is_static()) {
    return field.raw();
  }
  return Field::null();
}

RawLibraryPrefix* Class::LookupLibraryPrefix(const String& name) const {
  Zone* zone = Thread::Current()->zone();
  const Library& lib = Library::Handle(zone, library());
  const Object& obj = Object::Handle(zone, lib.LookupLocalObject(name));
  if (!obj.IsNull() && obj.IsLibraryPrefix()) {
    return LibraryPrefix::Cast(obj).raw();
  }
  return LibraryPrefix::null();
}

const char* Class::ToCString() const {
  const Library& lib = Library::Handle(library());
  const char* library_name = lib.IsNull() ? "" : lib.ToCString();
  const char* patch_prefix = is_patch() ? "Patch " : "";
  const char* class_name = String::Handle(Name()).ToCString();
  return OS::SCreate(Thread::Current()->zone(), "%s %sClass: %s", library_name,
                     patch_prefix, class_name);
}

// Thomas Wang, Integer Hash Functions.
// https://gist.github.com/badboy/6267743
// "64 bit to 32 bit Hash Functions"
static uword Hash64To32(uint64_t v) {
  v = ~v + (v << 18);
  v = v ^ (v >> 31);
  v = v * 21;
  v = v ^ (v >> 11);
  v = v + (v << 6);
  v = v ^ (v >> 22);
  return static_cast<uint32_t>(v);
}

class CanonicalDoubleKey {
 public:
  explicit CanonicalDoubleKey(const Double& key)
      : key_(&key), value_(key.value()) {}
  explicit CanonicalDoubleKey(const double value) : key_(NULL), value_(value) {}
  bool Matches(const Double& obj) const {
    return obj.BitwiseEqualsToDouble(value_);
  }
  uword Hash() const { return Hash(value_); }
  static uword Hash(double value) {
    return Hash64To32(bit_cast<uint64_t>(value));
  }

  const Double* key_;
  const double value_;

 private:
  DISALLOW_ALLOCATION();
};

class CanonicalMintKey {
 public:
  explicit CanonicalMintKey(const Mint& key)
      : key_(&key), value_(key.value()) {}
  explicit CanonicalMintKey(const int64_t value) : key_(NULL), value_(value) {}
  bool Matches(const Mint& obj) const { return obj.value() == value_; }
  uword Hash() const { return Hash(value_); }
  static uword Hash(int64_t value) {
    return Hash64To32(bit_cast<uint64_t>(value));
  }

  const Mint* key_;
  const int64_t value_;

 private:
  DISALLOW_ALLOCATION();
};

// Traits for looking up Canonical numbers based on a hash of the value.
template <typename ObjectType, typename KeyType>
class CanonicalNumberTraits {
 public:
  static const char* Name() { return "CanonicalNumberTraits"; }
  static bool ReportStats() { return false; }

  // Called when growing the table.
  static bool IsMatch(const Object& a, const Object& b) {
    return a.raw() == b.raw();
  }
  static bool IsMatch(const KeyType& a, const Object& b) {
    return a.Matches(ObjectType::Cast(b));
  }
  static uword Hash(const Object& key) {
    return KeyType::Hash(ObjectType::Cast(key).value());
  }
  static uword Hash(const KeyType& key) { return key.Hash(); }
  static RawObject* NewKey(const KeyType& obj) {
    if (obj.key_ != NULL) {
      return obj.key_->raw();
    } else {
      UNIMPLEMENTED();
      return NULL;
    }
  }
};
typedef UnorderedHashSet<CanonicalNumberTraits<Double, CanonicalDoubleKey> >
    CanonicalDoubleSet;
typedef UnorderedHashSet<CanonicalNumberTraits<Mint, CanonicalMintKey> >
    CanonicalMintSet;

// Returns an instance of Double or Double::null().
RawDouble* Class::LookupCanonicalDouble(Zone* zone, double value) const {
  ASSERT(this->raw() == Isolate::Current()->object_store()->double_class());
  if (this->constants() == Object::empty_array().raw()) return Double::null();

  Double& canonical_value = Double::Handle(zone);
  CanonicalDoubleSet constants(zone, this->constants());
  canonical_value ^= constants.GetOrNull(CanonicalDoubleKey(value));
  this->set_constants(constants.Release());
  return canonical_value.raw();
}

// Returns an instance of Mint or Mint::null().
RawMint* Class::LookupCanonicalMint(Zone* zone, int64_t value) const {
  ASSERT(this->raw() == Isolate::Current()->object_store()->mint_class());
  if (this->constants() == Object::empty_array().raw()) return Mint::null();

  Mint& canonical_value = Mint::Handle(zone);
  CanonicalMintSet constants(zone, this->constants());
  canonical_value ^= constants.GetOrNull(CanonicalMintKey(value));
  this->set_constants(constants.Release());
  return canonical_value.raw();
}

RawBigint* Class::LookupCanonicalBigint(Zone* zone,
                                        const Bigint& value,
                                        intptr_t* index) const {
  ASSERT(this->raw() == Isolate::Current()->object_store()->bigint_class());
  const Array& constants = Array::Handle(zone, this->constants());
  const intptr_t constants_len = constants.Length();
  // Linear search to see whether this value is already present in the
  // list of canonicalized constants.
  Bigint& canonical_value = Bigint::Handle(zone);
  while (*index < constants_len) {
    canonical_value ^= constants.At(*index);
    if (canonical_value.IsNull()) {
      break;
    }
    if (canonical_value.Equals(value)) {
      ASSERT(canonical_value.IsCanonical());
      return canonical_value.raw();
    }
    *index = *index + 1;
  }
  return Bigint::null();
}

class CanonicalInstanceKey {
 public:
  explicit CanonicalInstanceKey(const Instance& key) : key_(key) {
    ASSERT(!(key.IsString() || key.IsInteger() || key.IsAbstractType()));
  }
  bool Matches(const Instance& obj) const {
    ASSERT(!(obj.IsString() || obj.IsInteger() || obj.IsAbstractType()));
    if (key_.CanonicalizeEquals(obj)) {
      ASSERT(obj.IsCanonical());
      return true;
    }
    return false;
  }
  uword Hash() const { return key_.ComputeCanonicalTableHash(); }
  const Instance& key_;

 private:
  DISALLOW_ALLOCATION();
};

// Traits for looking up Canonical Instances based on a hash of the fields.
class CanonicalInstanceTraits {
 public:
  static const char* Name() { return "CanonicalInstanceTraits"; }
  static bool ReportStats() { return false; }

  // Called when growing the table.
  static bool IsMatch(const Object& a, const Object& b) {
    ASSERT(!(a.IsString() || a.IsInteger() || a.IsAbstractType()));
    ASSERT(!(b.IsString() || b.IsInteger() || b.IsAbstractType()));
    return a.raw() == b.raw();
  }
  static bool IsMatch(const CanonicalInstanceKey& a, const Object& b) {
    return a.Matches(Instance::Cast(b));
  }
  static uword Hash(const Object& key) {
    ASSERT(!(key.IsString() || key.IsNumber() || key.IsAbstractType()));
    ASSERT(key.IsInstance());
    return Instance::Cast(key).ComputeCanonicalTableHash();
  }
  static uword Hash(const CanonicalInstanceKey& key) { return key.Hash(); }
  static RawObject* NewKey(const CanonicalInstanceKey& obj) {
    return obj.key_.raw();
  }
};
typedef UnorderedHashSet<CanonicalInstanceTraits> CanonicalInstancesSet;

RawInstance* Class::LookupCanonicalInstance(Zone* zone,
                                            const Instance& value) const {
  ASSERT(this->raw() == value.clazz());
  ASSERT(is_finalized());
  Instance& canonical_value = Instance::Handle(zone);
  if (this->constants() != Object::empty_array().raw()) {
    CanonicalInstancesSet constants(zone, this->constants());
    canonical_value ^= constants.GetOrNull(CanonicalInstanceKey(value));
    this->set_constants(constants.Release());
  }
  return canonical_value.raw();
}

RawInstance* Class::InsertCanonicalConstant(Zone* zone,
                                            const Instance& constant) const {
  ASSERT(this->raw() == constant.clazz());
  Instance& canonical_value = Instance::Handle(zone);
  if (this->constants() == Object::empty_array().raw()) {
    CanonicalInstancesSet constants(
        HashTables::New<CanonicalInstancesSet>(128, Heap::kOld));
    canonical_value ^= constants.InsertNewOrGet(CanonicalInstanceKey(constant));
    this->set_constants(constants.Release());
  } else {
    CanonicalInstancesSet constants(Thread::Current()->zone(),
                                    this->constants());
    canonical_value ^= constants.InsertNewOrGet(CanonicalInstanceKey(constant));
    this->set_constants(constants.Release());
  }
  return canonical_value.raw();
}

void Class::InsertCanonicalDouble(Zone* zone, const Double& constant) const {
  if (this->constants() == Object::empty_array().raw()) {
    this->set_constants(Array::Handle(
        zone, HashTables::New<CanonicalDoubleSet>(128, Heap::kOld)));
  }
  CanonicalDoubleSet constants(zone, this->constants());
  constants.InsertNewOrGet(CanonicalDoubleKey(constant));
  this->set_constants(constants.Release());
}

void Class::InsertCanonicalMint(Zone* zone, const Mint& constant) const {
  if (this->constants() == Object::empty_array().raw()) {
    this->set_constants(Array::Handle(
        zone, HashTables::New<CanonicalMintSet>(128, Heap::kOld)));
  }
  CanonicalMintSet constants(zone, this->constants());
  constants.InsertNewOrGet(CanonicalMintKey(constant));
  this->set_constants(constants.Release());
}

void Class::InsertCanonicalBigint(Zone* zone,
                                  intptr_t index,
                                  const Bigint& constant) const {
  // The constant needs to be added to the list. Grow the list if it is full.
  Array& canonical_list = Array::Handle(zone, constants());
  const intptr_t list_len = canonical_list.Length();
  if (index >= list_len) {
    const intptr_t new_length = list_len + 4 + (list_len >> 2);
    canonical_list ^= Array::Grow(canonical_list, new_length, Heap::kOld);
    set_constants(canonical_list);
  }
  canonical_list.SetAt(index, constant);
}

void Class::RehashConstants(Zone* zone) const {
  intptr_t cid = id();
  if ((cid == kMintCid) || (cid == kBigintCid) || (cid == kDoubleCid)) {
    // Constants stored as a plain list or in a hashset with a stable hashcode,
    // which only depends on the actual value of the constant.
    return;
  }

  const Array& old_constants = Array::Handle(zone, constants());
  if (old_constants.Length() == 0) return;

  set_constants(Object::empty_array());

  CanonicalInstancesSet set(zone, old_constants.raw());
  Instance& constant = Instance::Handle(zone);
  CanonicalInstancesSet::Iterator it(&set);
  while (it.MoveNext()) {
    constant ^= set.GetKey(it.Current());
    ASSERT(!constant.IsNull());
    ASSERT(constant.IsCanonical());
    InsertCanonicalConstant(zone, constant);
  }
  set.Release();
}

RawUnresolvedClass* UnresolvedClass::New(const Object& library_prefix,
                                         const String& ident,
                                         TokenPosition token_pos) {
  const UnresolvedClass& type = UnresolvedClass::Handle(UnresolvedClass::New());
  type.set_library_or_library_prefix(library_prefix);
  type.set_ident(ident);
  type.set_token_pos(token_pos);
  return type.raw();
}

RawUnresolvedClass* UnresolvedClass::New() {
  ASSERT(Object::unresolved_class_class() != Class::null());
  RawObject* raw = Object::Allocate(
      UnresolvedClass::kClassId, UnresolvedClass::InstanceSize(), Heap::kOld);
  return reinterpret_cast<RawUnresolvedClass*>(raw);
}

void UnresolvedClass::set_token_pos(TokenPosition token_pos) const {
  ASSERT(!token_pos.IsClassifying());
  StoreNonPointer(&raw_ptr()->token_pos_, token_pos);
}

void UnresolvedClass::set_ident(const String& ident) const {
  StorePointer(&raw_ptr()->ident_, ident.raw());
}

void UnresolvedClass::set_library_or_library_prefix(
    const Object& library_prefix) const {
  StorePointer(&raw_ptr()->library_or_library_prefix_, library_prefix.raw());
}

RawString* UnresolvedClass::Name() const {
  if (library_or_library_prefix() != Object::null()) {
    Thread* thread = Thread::Current();
    Zone* zone = thread->zone();
    const Object& lib_prefix =
        Object::Handle(zone, library_or_library_prefix());
    String& name = String::Handle(zone);  // Qualifier.
    if (lib_prefix.IsLibraryPrefix()) {
      name = LibraryPrefix::Cast(lib_prefix).name();
    } else {
      name = Library::Cast(lib_prefix).name();
    }
    GrowableHandlePtrArray<const String> strs(zone, 3);
    strs.Add(name);
    strs.Add(Symbols::Dot());
    strs.Add(String::Handle(zone, ident()));
    return Symbols::FromConcatAll(thread, strs);
  } else {
    return ident();
  }
}

const char* UnresolvedClass::ToCString() const {
  const char* cname = String::Handle(Name()).ToCString();
  return OS::SCreate(Thread::Current()->zone(), "unresolved class '%s'", cname);
}

static uint32_t CombineHashes(uint32_t hash, uint32_t other_hash) {
  hash += other_hash;
  hash += hash << 10;
  hash ^= hash >> 6;  // Logical shift, unsigned hash.
  return hash;
}

static uint32_t FinalizeHash(uint32_t hash, intptr_t hashbits) {
  hash += hash << 3;
  hash ^= hash >> 11;  // Logical shift, unsigned hash.
  hash += hash << 15;
  // FinalizeHash gets called with values for hashbits that are bigger than 31
  // (like kBitsPerWord - 1).  Therefore we are careful to use a type
  // (uintptr_t) big enough to avoid undefined behavior with the left shift.
  hash &= (static_cast<uintptr_t>(1) << hashbits) - 1;
  return (hash == 0) ? 1 : hash;
}

intptr_t TypeArguments::ComputeHash() const {
  if (IsNull()) return 0;
  const intptr_t num_types = Length();
  if (IsRaw(0, num_types)) return 0;
  uint32_t result = 0;
  AbstractType& type = AbstractType::Handle();
  for (intptr_t i = 0; i < num_types; i++) {
    type = TypeAt(i);
    // The hash may be calculated during type finalization (for debugging
    // purposes only) while a type argument is still temporarily null.
    if (type.IsNull() || type.IsNullTypeRef()) {
      return 0;  // Do not cache hash, since it will still change.
    }
    result = CombineHashes(result, type.Hash());
  }
  result = FinalizeHash(result, kHashBits);
  SetHash(result);
  return result;
}

RawString* TypeArguments::SubvectorName(intptr_t from_index,
                                        intptr_t len,
                                        NameVisibility name_visibility) const {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  ASSERT(from_index + len <= Length());
  String& name = String::Handle(zone);
  const intptr_t num_strings =
      (len == 0) ? 2 : 2 * len + 1;  // "<""T"", ""T"">".
  GrowableHandlePtrArray<const String> pieces(zone, num_strings);
  pieces.Add(Symbols::LAngleBracket());
  AbstractType& type = AbstractType::Handle(zone);
  for (intptr_t i = 0; i < len; i++) {
    type = TypeAt(from_index + i);
    name = type.BuildName(name_visibility);
    pieces.Add(name);
    if (i < len - 1) {
      pieces.Add(Symbols::CommaSpace());
    }
  }
  pieces.Add(Symbols::RAngleBracket());
  ASSERT(pieces.length() == num_strings);
  return Symbols::FromConcatAll(thread, pieces);
}

bool TypeArguments::IsSubvectorEquivalent(const TypeArguments& other,
                                          intptr_t from_index,
                                          intptr_t len,
                                          TrailPtr trail) const {
  if (this->raw() == other.raw()) {
    return true;
  }
  if (IsNull() || other.IsNull()) {
    return false;
  }
  const intptr_t num_types = Length();
  if (num_types != other.Length()) {
    return false;
  }
  AbstractType& type = AbstractType::Handle();
  AbstractType& other_type = AbstractType::Handle();
  for (intptr_t i = from_index; i < from_index + len; i++) {
    type = TypeAt(i);
    other_type = other.TypeAt(i);
    // Still unfinalized vectors should not be considered equivalent.
    if (type.IsNull() || !type.IsEquivalent(other_type, trail)) {
      return false;
    }
  }
  return true;
}

bool TypeArguments::IsRecursive() const {
  if (IsNull()) return false;
  const intptr_t num_types = Length();
  AbstractType& type = AbstractType::Handle();
  for (intptr_t i = 0; i < num_types; i++) {
    type = TypeAt(i);
    // If this type argument is null, the type parameterized with this type
    // argument is still being finalized and is definitely recursive. The null
    // type argument will be replaced by a non-null type before the type is
    // marked as finalized.
    if (type.IsNull() || type.IsRecursive()) {
      return true;
    }
  }
  return false;
}

void TypeArguments::SetScopeFunction(const Function& function) const {
  if (IsNull()) return;
  const intptr_t num_types = Length();
  AbstractType& type = AbstractType::Handle();
  for (intptr_t i = 0; i < num_types; i++) {
    type = TypeAt(i);
    if (!type.IsNull()) {
      type.SetScopeFunction(function);
    }
  }
}

bool TypeArguments::IsDynamicTypes(bool raw_instantiated,
                                   intptr_t from_index,
                                   intptr_t len) const {
  ASSERT(Length() >= (from_index + len));
  AbstractType& type = AbstractType::Handle();
  Class& type_class = Class::Handle();
  for (intptr_t i = 0; i < len; i++) {
    type = TypeAt(from_index + i);
    if (type.IsNull()) {
      return false;
    }
    if (!type.HasResolvedTypeClass()) {
      if (raw_instantiated && type.IsTypeParameter()) {
        // An uninstantiated type parameter is equivalent to dynamic (even in
        // the presence of a malformed bound in checked mode).
        continue;
      }
      return false;
    }
    type_class = type.type_class();
    if (!type_class.IsDynamicClass()) {
      return false;
    }
  }
  return true;
}

bool TypeArguments::IsTopTypes(intptr_t from_index, intptr_t len) const {
  ASSERT(Length() >= (from_index + len));
  AbstractType& type = AbstractType::Handle();
  for (intptr_t i = 0; i < len; i++) {
    type = TypeAt(from_index + i);
    if (type.IsNull() || !type.IsTopType()) {
      return false;
    }
  }
  return true;
}

bool TypeArguments::TypeTest(TypeTestKind test_kind,
                             const TypeArguments& other,
                             intptr_t from_index,
                             intptr_t len,
                             Error* bound_error,
                             TrailPtr bound_trail,
                             Heap::Space space) const {
  ASSERT(Length() >= (from_index + len));
  ASSERT(!other.IsNull());
  ASSERT(other.Length() >= (from_index + len));
  AbstractType& type = AbstractType::Handle();
  AbstractType& other_type = AbstractType::Handle();
  for (intptr_t i = 0; i < len; i++) {
    type = TypeAt(from_index + i);
    other_type = other.TypeAt(from_index + i);
    if (type.IsNull() || other_type.IsNull() ||
        !type.TypeTest(test_kind, other_type, bound_error, bound_trail,
                       space)) {
      return false;
    }
  }
  return true;
}

bool TypeArguments::HasInstantiations() const {
  const Array& prior_instantiations = Array::Handle(instantiations());
  ASSERT(prior_instantiations.Length() > 0);  // Always at least a sentinel.
  return prior_instantiations.Length() > 1;
}

intptr_t TypeArguments::NumInstantiations() const {
  const Array& prior_instantiations = Array::Handle(instantiations());
  ASSERT(prior_instantiations.Length() > 0);  // Always at least a sentinel.
  intptr_t num = 0;
  intptr_t i = 0;
  while (prior_instantiations.At(i) != Smi::New(StubCode::kNoInstantiator)) {
    i += StubCode::kInstantiationSizeInWords;
    num++;
  }
  return num;
}

RawArray* TypeArguments::instantiations() const {
  return raw_ptr()->instantiations_;
}

void TypeArguments::set_instantiations(const Array& value) const {
  ASSERT(!value.IsNull());
  StorePointer(&raw_ptr()->instantiations_, value.raw());
}

intptr_t TypeArguments::Length() const {
  if (IsNull()) {
    return 0;
  }
  return Smi::Value(raw_ptr()->length_);
}

RawAbstractType* TypeArguments::TypeAt(intptr_t index) const {
  return *TypeAddr(index);
}

void TypeArguments::SetTypeAt(intptr_t index, const AbstractType& value) const {
  ASSERT(!IsCanonical());
  StorePointer(TypeAddr(index), value.raw());
}

bool TypeArguments::IsResolved() const {
  if (IsCanonical()) {
    return true;
  }
  AbstractType& type = AbstractType::Handle();
  const intptr_t num_types = Length();
  for (intptr_t i = 0; i < num_types; i++) {
    type = TypeAt(i);
    if (!type.IsResolved()) {
      return false;
    }
  }
  return true;
}

bool TypeArguments::IsSubvectorInstantiated(intptr_t from_index,
                                            intptr_t len,
                                            Genericity genericity,
                                            intptr_t num_free_fun_type_params,
                                            TrailPtr trail) const {
  ASSERT(!IsNull());
  AbstractType& type = AbstractType::Handle();
  for (intptr_t i = 0; i < len; i++) {
    type = TypeAt(from_index + i);
    // If this type argument T is null, the type A containing T in its flattened
    // type argument vector V is recursive and is still being finalized.
    // T is the type argument of a super type of A. T is being instantiated
    // during finalization of V, which is also the instantiator. T depends
    // solely on the type parameters of A and will be replaced by a non-null
    // type before A is marked as finalized.
    if (!type.IsNull() &&
        !type.IsInstantiated(genericity, num_free_fun_type_params, trail)) {
      return false;
    }
  }
  return true;
}

bool TypeArguments::IsUninstantiatedIdentity() const {
  AbstractType& type = AbstractType::Handle();
  const intptr_t num_types = Length();
  for (intptr_t i = 0; i < num_types; i++) {
    type = TypeAt(i);
    if (type.IsNull()) {
      return false;  // Still unfinalized, too early to tell.
    }
    if (!type.IsTypeParameter()) {
      return false;
    }
    const TypeParameter& type_param = TypeParameter::Cast(type);
    ASSERT(type_param.IsFinalized());
    if ((type_param.index() != i) || type_param.IsFunctionTypeParameter()) {
      return false;
    }
    // TODO(regis): Do the bounds really matter, since they are checked at
    // finalization time (creating BoundedTypes where required)? Understand
    // why ignoring bounds here causes failures.
    // If this type parameter specifies an upper bound, then the type argument
    // vector does not really represent the identity vector. It cannot be
    // substituted by the instantiator's type argument vector without checking
    // the upper bound.
    const AbstractType& bound = AbstractType::Handle(type_param.bound());
    ASSERT(bound.IsResolved());
    if (!bound.IsObjectType() && !bound.IsDynamicType()) {
      return false;
    }
  }
  return true;
  // Note that it is not necessary to verify at runtime that the instantiator
  // type vector is long enough, since this uninstantiated vector contains as
  // many different type parameters as it is long.
}

// Return true if this uninstantiated type argument vector, once instantiated
// at runtime, is a prefix of the type argument vector of its instantiator.
bool TypeArguments::CanShareInstantiatorTypeArguments(
    const Class& instantiator_class) const {
  ASSERT(!IsInstantiated());
  const intptr_t num_type_args = Length();
  const intptr_t num_instantiator_type_args =
      instantiator_class.NumTypeArguments();
  if (num_type_args > num_instantiator_type_args) {
    // This vector cannot be a prefix of a shorter vector.
    return false;
  }
  const intptr_t num_instantiator_type_params =
      instantiator_class.NumTypeParameters();
  const intptr_t first_type_param_offset =
      num_instantiator_type_args - num_instantiator_type_params;
  // At compile time, the type argument vector of the instantiator consists of
  // the type argument vector of its super type, which may refer to the type
  // parameters of the instantiator class, followed by (or overlapping partially
  // or fully with) the type parameters of the instantiator class in declaration
  // order.
  // In other words, the only variables are the type parameters of the
  // instantiator class.
  // This uninstantiated type argument vector is also expressed in terms of the
  // type parameters of the instantiator class. Therefore, in order to be a
  // prefix once instantiated at runtime, every one of its type argument must be
  // equal to the type argument of the instantiator vector at the same index.

  // As a first requirement, the last num_instantiator_type_params type
  // arguments of this type argument vector must refer to the corresponding type
  // parameters of the instantiator class.
  AbstractType& type_arg = AbstractType::Handle();
  for (intptr_t i = first_type_param_offset; i < num_type_args; i++) {
    type_arg = TypeAt(i);
    if (!type_arg.IsTypeParameter()) {
      return false;
    }
    const TypeParameter& type_param = TypeParameter::Cast(type_arg);
    ASSERT(type_param.IsFinalized());
    if ((type_param.index() != i) || type_param.IsFunctionTypeParameter()) {
      return false;
    }
  }
  // As a second requirement, the type arguments corresponding to the super type
  // must be identical. Overlapping ones have already been checked starting at
  // first_type_param_offset.
  if (first_type_param_offset == 0) {
    return true;
  }
  AbstractType& super_type =
      AbstractType::Handle(instantiator_class.super_type());
  const TypeArguments& super_type_args =
      TypeArguments::Handle(super_type.arguments());
  if (super_type_args.IsNull()) {
    return false;
  }
  AbstractType& super_type_arg = AbstractType::Handle();
  for (intptr_t i = 0; (i < first_type_param_offset) && (i < num_type_args);
       i++) {
    type_arg = TypeAt(i);
    super_type_arg = super_type_args.TypeAt(i);
    if (!type_arg.Equals(super_type_arg)) {
      return false;
    }
  }
  return true;
}

bool TypeArguments::IsFinalized() const {
  ASSERT(!IsNull());
  AbstractType& type = AbstractType::Handle();
  const intptr_t num_types = Length();
  for (intptr_t i = 0; i < num_types; i++) {
    type = TypeAt(i);
    if (!type.IsFinalized()) {
      return false;
    }
  }
  return true;
}

bool TypeArguments::IsBounded() const {
  AbstractType& type = AbstractType::Handle();
  const intptr_t num_types = Length();
  for (intptr_t i = 0; i < num_types; i++) {
    type = TypeAt(i);
    if (type.IsBoundedType()) {
      return true;
    }
    if (type.IsTypeParameter()) {
      const AbstractType& bound =
          AbstractType::Handle(TypeParameter::Cast(type).bound());
      if (!bound.IsObjectType() && !bound.IsDynamicType()) {
        return true;
      }
      continue;
    }
    const TypeArguments& type_args =
        TypeArguments::Handle(Type::Cast(type).arguments());
    if (!type_args.IsNull() && type_args.IsBounded()) {
      return true;
    }
  }
  return false;
}

RawTypeArguments* TypeArguments::InstantiateFrom(
    const TypeArguments& instantiator_type_arguments,
    const TypeArguments& function_type_arguments,
    intptr_t num_free_fun_type_params,
    Error* bound_error,
    TrailPtr instantiation_trail,
    TrailPtr bound_trail,
    Heap::Space space) const {
  ASSERT(!IsInstantiated(kAny, num_free_fun_type_params));
  if (!instantiator_type_arguments.IsNull() && IsUninstantiatedIdentity() &&
      (instantiator_type_arguments.Length() == Length())) {
    return instantiator_type_arguments.raw();
  }
  const intptr_t num_types = Length();
  TypeArguments& instantiated_array =
      TypeArguments::Handle(TypeArguments::New(num_types, space));
  AbstractType& type = AbstractType::Handle();
  for (intptr_t i = 0; i < num_types; i++) {
    type = TypeAt(i);
    // If this type argument T is null, the type A containing T in its flattened
    // type argument vector V is recursive and is still being finalized.
    // T is the type argument of a super type of A. T is being instantiated
    // during finalization of V, which is also the instantiator. T depends
    // solely on the type parameters of A and will be replaced by a non-null
    // type before A is marked as finalized.
    if (!type.IsNull() &&
        !type.IsInstantiated(kAny, num_free_fun_type_params)) {
      type = type.InstantiateFrom(instantiator_type_arguments,
                                  function_type_arguments,
                                  num_free_fun_type_params, bound_error,
                                  instantiation_trail, bound_trail, space);
    }
    instantiated_array.SetTypeAt(i, type);
  }
  return instantiated_array.raw();
}

RawTypeArguments* TypeArguments::InstantiateAndCanonicalizeFrom(
    const TypeArguments& instantiator_type_arguments,
    const TypeArguments& function_type_arguments,
    Error* bound_error) const {
  ASSERT(!IsInstantiated());
  ASSERT(instantiator_type_arguments.IsNull() ||
         instantiator_type_arguments.IsCanonical());
  ASSERT(function_type_arguments.IsNull() ||
         function_type_arguments.IsCanonical());
  // Lookup instantiator and, if found, return paired instantiated result.
  Array& prior_instantiations = Array::Handle(instantiations());
  ASSERT(!prior_instantiations.IsNull() && prior_instantiations.IsArray());
  // The instantiations cache is initialized with Object::zero_array() and is
  // therefore guaranteed to contain kNoInstantiator. No length check needed.
  ASSERT(prior_instantiations.Length() > 0);  // Always at least a sentinel.
  intptr_t index = 0;
  while (true) {
    if ((prior_instantiations.At(index) == instantiator_type_arguments.raw()) &&
        (prior_instantiations.At(index + 1) == function_type_arguments.raw())) {
      return TypeArguments::RawCast(prior_instantiations.At(index + 2));
    }
    if (prior_instantiations.At(index) == Smi::New(StubCode::kNoInstantiator)) {
      break;
    }
    index += StubCode::kInstantiationSizeInWords;
  }
  // Cache lookup failed. Instantiate the type arguments.
  TypeArguments& result = TypeArguments::Handle();
  result = InstantiateFrom(instantiator_type_arguments, function_type_arguments,
                           kAllFree, bound_error, NULL, NULL, Heap::kOld);
  if ((bound_error != NULL) && !bound_error->IsNull()) {
    return result.raw();
  }
  // Instantiation did not result in bound error. Canonicalize type arguments.
  result = result.Canonicalize();
  // InstantiateAndCanonicalizeFrom is not reentrant. It cannot have been called
  // indirectly, so the prior_instantiations array cannot have grown.
  ASSERT(prior_instantiations.raw() == instantiations());
  // Add instantiator and function type args and result to instantiations array.
  intptr_t length = prior_instantiations.Length();
  if ((index + StubCode::kInstantiationSizeInWords) >= length) {
    // TODO(regis): Should we limit the number of cached instantiations?
    // Grow the instantiations array by about 50%, but at least by 1.
    // The initial array is Object::zero_array() of length 1.
    intptr_t entries = (length - 1) / StubCode::kInstantiationSizeInWords;
    intptr_t new_entries = entries + (entries >> 1) + 1;
    length = new_entries * StubCode::kInstantiationSizeInWords + 1;
    prior_instantiations =
        Array::Grow(prior_instantiations, length, Heap::kOld);
    set_instantiations(prior_instantiations);
    ASSERT((index + StubCode::kInstantiationSizeInWords) < length);
  }
  prior_instantiations.SetAt(index + 0, instantiator_type_arguments);
  prior_instantiations.SetAt(index + 1, function_type_arguments);
  prior_instantiations.SetAt(index + 2, result);
  prior_instantiations.SetAt(index + 3,
                             Smi::Handle(Smi::New(StubCode::kNoInstantiator)));
  return result.raw();
}

RawTypeArguments* TypeArguments::New(intptr_t len, Heap::Space space) {
  if (len < 0 || len > kMaxElements) {
    // This should be caught before we reach here.
    FATAL1("Fatal error in TypeArguments::New: invalid len %" Pd "\n", len);
  }
  TypeArguments& result = TypeArguments::Handle();
  {
    RawObject* raw = Object::Allocate(TypeArguments::kClassId,
                                      TypeArguments::InstanceSize(len), space);
    NoSafepointScope no_safepoint;
    result ^= raw;
    // Length must be set before we start storing into the array.
    result.SetLength(len);
    result.SetHash(0);
  }
  // The zero array should have been initialized.
  ASSERT(Object::zero_array().raw() != Array::null());
  COMPILE_ASSERT(StubCode::kNoInstantiator == 0);
  result.set_instantiations(Object::zero_array());
  return result.raw();
}

RawAbstractType* const* TypeArguments::TypeAddr(intptr_t index) const {
  ASSERT((index >= 0) && (index < Length()));
  return &raw_ptr()->types()[index];
}

void TypeArguments::SetLength(intptr_t value) const {
  ASSERT(!IsCanonical());
  // This is only safe because we create a new Smi, which does not cause
  // heap allocation.
  StoreSmi(&raw_ptr()->length_, Smi::New(value));
}

RawTypeArguments* TypeArguments::CloneUnfinalized() const {
  if (IsNull() || IsFinalized()) {
    return raw();
  }
  ASSERT(IsResolved());
  AbstractType& type = AbstractType::Handle();
  const intptr_t num_types = Length();
  const TypeArguments& clone =
      TypeArguments::Handle(TypeArguments::New(num_types));
  for (intptr_t i = 0; i < num_types; i++) {
    type = TypeAt(i);
    type = type.CloneUnfinalized();
    clone.SetTypeAt(i, type);
  }
  ASSERT(clone.IsResolved());
  return clone.raw();
}

RawTypeArguments* TypeArguments::CloneUninstantiated(const Class& new_owner,
                                                     TrailPtr trail) const {
  ASSERT(!IsNull());
  ASSERT(IsFinalized());
  ASSERT(!IsInstantiated());
  AbstractType& type = AbstractType::Handle();
  const intptr_t num_types = Length();
  const TypeArguments& clone =
      TypeArguments::Handle(TypeArguments::New(num_types));
  for (intptr_t i = 0; i < num_types; i++) {
    type = TypeAt(i);
    if (!type.IsInstantiated()) {
      type = type.CloneUninstantiated(new_owner, trail);
    }
    clone.SetTypeAt(i, type);
  }
  ASSERT(clone.IsFinalized());
  return clone.raw();
}

RawTypeArguments* TypeArguments::Canonicalize(TrailPtr trail) const {
  if (IsNull() || IsCanonical()) {
    ASSERT(IsOld());
    return this->raw();
  }
  const intptr_t num_types = Length();
  if (IsRaw(0, num_types)) {
    return TypeArguments::null();
  }
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  Isolate* isolate = thread->isolate();
  ObjectStore* object_store = isolate->object_store();
  TypeArguments& result = TypeArguments::Handle(zone);
  {
    SafepointMutexLocker ml(isolate->type_canonicalization_mutex());
    CanonicalTypeArgumentsSet table(zone,
                                    object_store->canonical_type_arguments());
    result ^= table.GetOrNull(CanonicalTypeArgumentsKey(*this));
    object_store->set_canonical_type_arguments(table.Release());
  }
  if (result.IsNull()) {
    // Canonicalize each type argument.
    AbstractType& type_arg = AbstractType::Handle(zone);
    for (intptr_t i = 0; i < num_types; i++) {
      type_arg = TypeAt(i);
      type_arg = type_arg.Canonicalize(trail);
      if (IsCanonical()) {
        // Canonicalizing this type_arg canonicalized this type.
        ASSERT(IsRecursive());
        return this->raw();
      }
      SetTypeAt(i, type_arg);
    }
    // Canonicalization of a type argument of a recursive type argument vector
    // may change the hash of the vector, so recompute.
    if (IsRecursive()) {
      ComputeHash();
    }
    SafepointMutexLocker ml(isolate->type_canonicalization_mutex());
    CanonicalTypeArgumentsSet table(zone,
                                    object_store->canonical_type_arguments());
    // Since we canonicalized some type arguments above we need to lookup
    // in the table again to make sure we don't already have an equivalent
    // canonical entry.
    result ^= table.GetOrNull(CanonicalTypeArgumentsKey(*this));
    if (result.IsNull()) {
      // Make sure we have an old space object and add it to the table.
      if (this->IsNew()) {
        result ^= Object::Clone(*this, Heap::kOld);
      } else {
        result ^= this->raw();
      }
      ASSERT(result.IsOld());
      result.SetCanonical();  // Mark object as being canonical.
      // Now add this TypeArgument into the canonical list of type arguments.
      bool present = table.Insert(result);
      ASSERT(!present);
    }
    object_store->set_canonical_type_arguments(table.Release());
  }
  ASSERT(result.Equals(*this));
  ASSERT(!result.IsNull());
  ASSERT(result.IsTypeArguments());
  ASSERT(result.IsCanonical());
  return result.raw();
}

RawString* TypeArguments::EnumerateURIs() const {
  if (IsNull()) {
    return Symbols::Empty().raw();
  }
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  AbstractType& type = AbstractType::Handle(zone);
  const intptr_t num_types = Length();
  const Array& pieces = Array::Handle(zone, Array::New(num_types));
  for (intptr_t i = 0; i < num_types; i++) {
    type = TypeAt(i);
    pieces.SetAt(i, String::Handle(zone, type.EnumerateURIs()));
  }
  return String::ConcatAll(pieces);
}

const char* TypeArguments::ToCString() const {
  if (IsNull()) {
    return "TypeArguments: null";
  }
  Zone* zone = Thread::Current()->zone();
  const char* prev_cstr = OS::SCreate(zone, "TypeArguments: (@%p H%" Px ")",
                                      raw(), Smi::Value(raw_ptr()->hash_));
  for (int i = 0; i < Length(); i++) {
    const AbstractType& type_at = AbstractType::Handle(zone, TypeAt(i));
    const char* type_cstr = type_at.IsNull() ? "null" : type_at.ToCString();
    char* chars = OS::SCreate(zone, "%s [%s]", prev_cstr, type_cstr);
    prev_cstr = chars;
  }
  return prev_cstr;
}

const char* PatchClass::ToCString() const {
  const Class& cls = Class::Handle(patched_class());
  const char* cls_name = cls.ToCString();
  return OS::SCreate(Thread::Current()->zone(), "PatchClass for %s", cls_name);
}

RawPatchClass* PatchClass::New(const Class& patched_class,
                               const Class& origin_class) {
  const PatchClass& result = PatchClass::Handle(PatchClass::New());
  result.set_patched_class(patched_class);
  result.set_origin_class(origin_class);
  result.set_script(Script::Handle(origin_class.script()));
  result.set_library_kernel_offset(-1);
  return result.raw();
}

RawPatchClass* PatchClass::New(const Class& patched_class,
                               const Script& script) {
  const PatchClass& result = PatchClass::Handle(PatchClass::New());
  result.set_patched_class(patched_class);
  result.set_origin_class(patched_class);
  result.set_script(script);
  result.set_library_kernel_offset(-1);
  return result.raw();
}

RawPatchClass* PatchClass::New() {
  ASSERT(Object::patch_class_class() != Class::null());
  RawObject* raw = Object::Allocate(PatchClass::kClassId,
                                    PatchClass::InstanceSize(), Heap::kOld);
  return reinterpret_cast<RawPatchClass*>(raw);
}

void PatchClass::set_patched_class(const Class& value) const {
  StorePointer(&raw_ptr()->patched_class_, value.raw());
}

void PatchClass::set_origin_class(const Class& value) const {
  StorePointer(&raw_ptr()->origin_class_, value.raw());
}

void PatchClass::set_script(const Script& value) const {
  StorePointer(&raw_ptr()->script_, value.raw());
}

void PatchClass::set_library_kernel_data(const TypedData& data) const {
  StorePointer(&raw_ptr()->library_kernel_data_, data.raw());
}

intptr_t Function::Hash() const {
  return String::HashRawSymbol(name());
}

bool Function::HasBreakpoint() const {
#if defined(PRODUCT)
  return false;
#else
  Thread* thread = Thread::Current();
  return thread->isolate()->debugger()->HasBreakpoint(*this, thread->zone());
#endif
}

void Function::InstallOptimizedCode(const Code& code) const {
  DEBUG_ASSERT(IsMutatorOrAtSafepoint());
  // We may not have previous code if FLAG_precompile is set.
  // Hot-reload may have already disabled the current code.
  if (HasCode() && !Code::Handle(CurrentCode()).IsDisabled()) {
    Code::Handle(CurrentCode()).DisableDartCode();
  }
  AttachCode(code);
}

void Function::SetInstructions(const Code& value) const {
  DEBUG_ASSERT(IsMutatorOrAtSafepoint());
  SetInstructionsSafe(value);
}

void Function::SetInstructionsSafe(const Code& value) const {
  StorePointer(&raw_ptr()->code_, value.raw());
  StoreNonPointer(&raw_ptr()->entry_point_, value.UncheckedEntryPoint());
}

void Function::AttachCode(const Code& value) const {
  DEBUG_ASSERT(IsMutatorOrAtSafepoint());
  // Finish setting up code before activating it.
  value.set_owner(*this);
  SetInstructions(value);
  ASSERT(Function::Handle(value.function()).IsNull() ||
         (value.function() == this->raw()));
}

bool Function::HasCode() const {
  ASSERT(raw_ptr()->code_ != Code::null());
  return raw_ptr()->code_ != StubCode::LazyCompile_entry()->code();
}

void Function::ClearCode() const {
#if defined(DART_PRECOMPILED_RUNTIME)
  UNREACHABLE();
#else
  ASSERT(Thread::Current()->IsMutatorThread());
  StorePointer(&raw_ptr()->unoptimized_code_, Code::null());
  SetInstructions(Code::Handle(StubCode::LazyCompile_entry()->code()));
#endif
}

void Function::EnsureHasCompiledUnoptimizedCode() const {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  ASSERT(thread->IsMutatorThread());

  const Error& error =
      Error::Handle(zone, Compiler::EnsureUnoptimizedCode(thread, *this));
  if (!error.IsNull()) {
    Exceptions::PropagateError(error);
  }
}

void Function::SwitchToUnoptimizedCode() const {
  ASSERT(HasOptimizedCode());
  Thread* thread = Thread::Current();
  Isolate* isolate = thread->isolate();
  Zone* zone = thread->zone();
  ASSERT(thread->IsMutatorThread());
  const Code& current_code = Code::Handle(zone, CurrentCode());

  if (FLAG_trace_deoptimization_verbose) {
    THR_Print("Disabling optimized code: '%s' entry: %#" Px "\n",
              ToFullyQualifiedCString(), current_code.UncheckedEntryPoint());
  }
  current_code.DisableDartCode();
  const Error& error =
      Error::Handle(zone, Compiler::EnsureUnoptimizedCode(thread, *this));
  if (!error.IsNull()) {
    Exceptions::PropagateError(error);
  }
  const Code& unopt_code = Code::Handle(zone, unoptimized_code());
  AttachCode(unopt_code);
  unopt_code.Enable();
  isolate->TrackDeoptimizedCode(current_code);
}

void Function::SwitchToLazyCompiledUnoptimizedCode() const {
  if (!HasOptimizedCode()) {
    return;
  }

  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  ASSERT(thread->IsMutatorThread());

  const Code& current_code = Code::Handle(zone, CurrentCode());
  TIR_Print("Disabling optimized code for %s\n", ToCString());
  current_code.DisableDartCode();

  const Code& unopt_code = Code::Handle(zone, unoptimized_code());
  if (unopt_code.IsNull()) {
    // Set the lazy compile code.
    TIR_Print("Switched to lazy compile stub for %s\n", ToCString());
    SetInstructions(Code::Handle(StubCode::LazyCompile_entry()->code()));
    return;
  }

  TIR_Print("Switched to unoptimized code for %s\n", ToCString());

  AttachCode(unopt_code);
  unopt_code.Enable();
}

void Function::set_unoptimized_code(const Code& value) const {
#if defined(DART_PRECOMPILED_RUNTIME)
  UNREACHABLE();
#else
  ASSERT(Thread::Current()->IsMutatorThread());
  ASSERT(value.IsNull() || !value.is_optimized());
  StorePointer(&raw_ptr()->unoptimized_code_, value.raw());
#endif
}

RawContextScope* Function::context_scope() const {
  if (IsClosureFunction() || IsConvertedClosureFunction()) {
    const Object& obj = Object::Handle(raw_ptr()->data_);
    ASSERT(!obj.IsNull());
    return ClosureData::Cast(obj).context_scope();
  }
  return ContextScope::null();
}

void Function::set_context_scope(const ContextScope& value) const {
  if (IsClosureFunction() || IsConvertedClosureFunction()) {
    const Object& obj = Object::Handle(raw_ptr()->data_);
    ASSERT(!obj.IsNull());
    ClosureData::Cast(obj).set_context_scope(value);
    return;
  }
  UNREACHABLE();
}

RawInstance* Function::implicit_static_closure() const {
  if (IsImplicitStaticClosureFunction()) {
    const Object& obj = Object::Handle(raw_ptr()->data_);
    ASSERT(!obj.IsNull());
    return ClosureData::Cast(obj).implicit_static_closure();
  }
  return Instance::null();
}

void Function::set_implicit_static_closure(const Instance& closure) const {
  if (IsImplicitStaticClosureFunction()) {
    const Object& obj = Object::Handle(raw_ptr()->data_);
    ASSERT(!obj.IsNull());
    ClosureData::Cast(obj).set_implicit_static_closure(closure);
    return;
  }
  UNREACHABLE();
}

RawScript* Function::eval_script() const {
  const Object& obj = Object::Handle(raw_ptr()->data_);
  if (obj.IsScript()) {
    return Script::Cast(obj).raw();
  }
  return Script::null();
}

void Function::set_eval_script(const Script& script) const {
  ASSERT(token_pos() == TokenPosition::kMinSource);
  ASSERT(raw_ptr()->data_ == Object::null());
  set_data(script);
}

RawFunction* Function::extracted_method_closure() const {
  ASSERT(kind() == RawFunction::kMethodExtractor);
  const Object& obj = Object::Handle(raw_ptr()->data_);
  ASSERT(obj.IsFunction());
  return Function::Cast(obj).raw();
}

void Function::set_extracted_method_closure(const Function& value) const {
  ASSERT(kind() == RawFunction::kMethodExtractor);
  ASSERT(raw_ptr()->data_ == Object::null());
  set_data(value);
}

RawArray* Function::saved_args_desc() const {
  ASSERT(kind() == RawFunction::kNoSuchMethodDispatcher ||
         kind() == RawFunction::kInvokeFieldDispatcher);
  const Object& obj = Object::Handle(raw_ptr()->data_);
  ASSERT(obj.IsArray());
  return Array::Cast(obj).raw();
}

void Function::set_saved_args_desc(const Array& value) const {
  ASSERT(kind() == RawFunction::kNoSuchMethodDispatcher ||
         kind() == RawFunction::kInvokeFieldDispatcher);
  ASSERT(raw_ptr()->data_ == Object::null());
  set_data(value);
}

RawField* Function::LookupImplicitGetterSetterField() const {
  // TODO(27590) Store Field object inside RawFunction::data_ if possible.
  Zone* Z = Thread::Current()->zone();
  String& field_name = String::Handle(Z, name());
  switch (kind()) {
    case RawFunction::kImplicitGetter:
    case RawFunction::kImplicitStaticFinalGetter:
      field_name = Field::NameFromGetter(field_name);
      break;
    case RawFunction::kImplicitSetter:
      field_name = Field::NameFromSetter(field_name);
      break;
    default:
      UNREACHABLE();
  }
  ASSERT(field_name.IsSymbol());
  const Class& owner = Class::Handle(Z, Owner());
  ASSERT(!owner.IsNull());
  return owner.LookupField(field_name);
}

RawFunction* Function::parent_function() const {
  if (IsClosureFunction() || IsConvertedClosureFunction() ||
      IsSignatureFunction()) {
    const Object& obj = Object::Handle(raw_ptr()->data_);
    ASSERT(!obj.IsNull());
    if (IsClosureFunction() || IsConvertedClosureFunction()) {
      return ClosureData::Cast(obj).parent_function();
    } else {
      return SignatureData::Cast(obj).parent_function();
    }
  }
  return Function::null();
}

void Function::set_parent_function(const Function& value) const {
  const Object& obj = Object::Handle(raw_ptr()->data_);
  ASSERT(!obj.IsNull());
  if (IsClosureFunction() || IsConvertedClosureFunction()) {
    ClosureData::Cast(obj).set_parent_function(value);
  } else {
    ASSERT(IsSignatureFunction());
    SignatureData::Cast(obj).set_parent_function(value);
  }
}

bool Function::HasGenericParent() const {
  if (IsImplicitClosureFunction()) {
    // The parent function of an implicit closure function is not the enclosing
    // function we are asking about here.
    return false;
  }
  Function& parent = Function::Handle(parent_function());
  while (!parent.IsNull()) {
    if (parent.IsGeneric()) {
      return true;
    }
    parent = parent.parent_function();
  }
  return false;
}

RawFunction* Function::implicit_closure_function() const {
  if (IsClosureFunction() || IsConvertedClosureFunction() ||
      IsSignatureFunction() || IsFactory()) {
    return Function::null();
  }
  const Object& obj = Object::Handle(raw_ptr()->data_);
  ASSERT(obj.IsNull() || obj.IsScript() || obj.IsFunction() || obj.IsArray());
  if (obj.IsNull() || obj.IsScript()) {
    return Function::null();
  }
  if (obj.IsFunction()) {
    return Function::Cast(obj).raw();
  }
  ASSERT(is_native());
  ASSERT(obj.IsArray());
  const Object& res = Object::Handle(Array::Cast(obj).At(1));
  return res.IsNull() ? Function::null() : Function::Cast(res).raw();
}

void Function::set_implicit_closure_function(const Function& value) const {
  ASSERT(!IsClosureFunction() && !IsSignatureFunction() &&
         !IsConvertedClosureFunction());
  const Object& old_data = Object::Handle(raw_ptr()->data_);
  if (is_native()) {
    ASSERT(old_data.IsArray());
    ASSERT((Array::Cast(old_data).At(1) == Object::null()) || value.IsNull());
    Array::Cast(old_data).SetAt(1, value);
  } else {
    // Maybe this function will turn into a native later on :-/
    if (old_data.IsArray()) {
      ASSERT((Array::Cast(old_data).At(1) == Object::null()) || value.IsNull());
      Array::Cast(old_data).SetAt(1, value);
    } else {
      ASSERT(old_data.IsNull() || value.IsNull());
      set_data(value);
    }
  }
}

RawFunction* Function::converted_closure_function() const {
  if (IsClosureFunction() || IsSignatureFunction() || IsFactory()) {
    return Function::null();
  }
  const Object& obj = Object::Handle(raw_ptr()->data_);
  ASSERT(obj.IsNull() || obj.IsFunction());
  if (obj.IsFunction()) {
    return Function::Cast(obj).raw();
  }
  return Function::null();
}

void Function::set_converted_closure_function(const Function& value) const {
  ASSERT(!IsClosureFunction() && !IsSignatureFunction() && !is_native());
  ASSERT((raw_ptr()->data_ == Object::null()) || value.IsNull());
  set_data(value);
}

RawType* Function::ExistingSignatureType() const {
  const Object& obj = Object::Handle(raw_ptr()->data_);
  ASSERT(!obj.IsNull());
  if (IsSignatureFunction()) {
    return SignatureData::Cast(obj).signature_type();
  } else {
    ASSERT(IsClosureFunction() || IsConvertedClosureFunction());
    return ClosureData::Cast(obj).signature_type();
  }
}

RawType* Function::SignatureType() const {
  Type& type = Type::Handle(ExistingSignatureType());
  if (type.IsNull()) {
    // The function type of this function is not yet cached and needs to be
    // constructed and cached here.
    // A function type is type parameterized in the same way as the owner class
    // of its non-static signature function.
    // It is not type parameterized if its signature function is static, or if
    // none of its result type or formal parameter types are type parameterized.
    // Unless the function type is a generic typedef, the type arguments of the
    // function type are not explicitly stored in the function type as a vector
    // of type arguments.
    // The type class of a non-typedef function type is always the non-generic
    // _Closure class, whether the type is generic or not.
    // The type class of a typedef function type is always the typedef class,
    // which may be generic, in which case the type stores type arguments.
    // With the introduction of generic functions, we may reach here before the
    // function type parameters have been resolved. Therefore, we cannot yet
    // check whether the function type has an instantiated signature.
    // We can do it only when the signature has been resolved.
    // We only set the type class of the function type to the typedef class
    // if the signature of the function type is the signature of the typedef.
    // Note that a function type can have a typedef class as owner without
    // representing the typedef, as in the following example:
    // typedef F(f(int x)); where the type of f is a function type with F as
    // owner, without representing the function type of F.
    Class& scope_class = Class::Handle(Owner());
    if (!scope_class.IsTypedefClass() ||
        (scope_class.signature_function() != raw())) {
      scope_class = Isolate::Current()->object_store()->closure_class();
    }
    const TypeArguments& signature_type_arguments =
        TypeArguments::Handle(scope_class.type_parameters());
    // Return the still unfinalized signature type.
    type = Type::New(scope_class, signature_type_arguments, token_pos());
    type.set_signature(*this);
    SetSignatureType(type);
  }
  return type.raw();
}

void Function::SetSignatureType(const Type& value) const {
  const Object& obj = Object::Handle(raw_ptr()->data_);
  ASSERT(!obj.IsNull());
  if (IsSignatureFunction()) {
    SignatureData::Cast(obj).set_signature_type(value);
    ASSERT(!value.IsCanonical() || (value.signature() == this->raw()));
  } else {
    ASSERT(IsClosureFunction() || IsConvertedClosureFunction());
    ClosureData::Cast(obj).set_signature_type(value);
  }
}

bool Function::IsRedirectingFactory() const {
  if (!IsFactory() || !is_redirecting()) {
    return false;
  }
  ASSERT(!IsClosureFunction());  // A factory cannot also be a closure.
  return true;
}

RawType* Function::RedirectionType() const {
  ASSERT(IsRedirectingFactory());
  ASSERT(!is_native());
  const Object& obj = Object::Handle(raw_ptr()->data_);
  ASSERT(!obj.IsNull());
  return RedirectionData::Cast(obj).type();
}

const char* Function::KindToCString(RawFunction::Kind kind) {
  switch (kind) {
    case RawFunction::kRegularFunction:
      return "RegularFunction";
      break;
    case RawFunction::kClosureFunction:
      return "ClosureFunction";
      break;
    case RawFunction::kImplicitClosureFunction:
      return "ImplicitClosureFunction";
      break;
    case RawFunction::kConvertedClosureFunction:
      return "ConvertedClosureFunction";
      break;
    case RawFunction::kSignatureFunction:
      return "SignatureFunction";
      break;
    case RawFunction::kGetterFunction:
      return "GetterFunction";
      break;
    case RawFunction::kSetterFunction:
      return "SetterFunction";
      break;
    case RawFunction::kConstructor:
      return "Constructor";
      break;
    case RawFunction::kImplicitGetter:
      return "ImplicitGetter";
      break;
    case RawFunction::kImplicitSetter:
      return "ImplicitSetter";
      break;
    case RawFunction::kImplicitStaticFinalGetter:
      return "ImplicitStaticFinalGetter";
      break;
    case RawFunction::kMethodExtractor:
      return "MethodExtractor";
      break;
    case RawFunction::kNoSuchMethodDispatcher:
      return "NoSuchMethodDispatcher";
      break;
    case RawFunction::kInvokeFieldDispatcher:
      return "InvokeFieldDispatcher";
      break;
    case RawFunction::kIrregexpFunction:
      return "IrregexpFunction";
      break;
    default:
      UNREACHABLE();
      return NULL;
  }
}

void Function::SetRedirectionType(const Type& type) const {
  ASSERT(IsFactory());
  Object& obj = Object::Handle(raw_ptr()->data_);
  if (obj.IsNull()) {
    obj = RedirectionData::New();
    set_data(obj);
  }
  RedirectionData::Cast(obj).set_type(type);
}

RawString* Function::RedirectionIdentifier() const {
  ASSERT(IsRedirectingFactory());
  const Object& obj = Object::Handle(raw_ptr()->data_);
  ASSERT(!obj.IsNull());
  return RedirectionData::Cast(obj).identifier();
}

void Function::SetRedirectionIdentifier(const String& identifier) const {
  ASSERT(IsFactory());
  Object& obj = Object::Handle(raw_ptr()->data_);
  if (obj.IsNull()) {
    obj = RedirectionData::New();
    set_data(obj);
  }
  RedirectionData::Cast(obj).set_identifier(identifier);
}

RawFunction* Function::RedirectionTarget() const {
  ASSERT(IsRedirectingFactory());
  const Object& obj = Object::Handle(raw_ptr()->data_);
  ASSERT(!obj.IsNull());
  return RedirectionData::Cast(obj).target();
}

void Function::SetRedirectionTarget(const Function& target) const {
  ASSERT(IsFactory());
  Object& obj = Object::Handle(raw_ptr()->data_);
  if (obj.IsNull()) {
    obj = RedirectionData::New();
    set_data(obj);
  }
  RedirectionData::Cast(obj).set_target(target);
}

// This field is heavily overloaded:
//   eval function:           Script expression source
//   signature function:      SignatureData
//   method extractor:        Function extracted closure function
//   noSuchMethod dispatcher: Array arguments descriptor
//   invoke-field dispatcher: Array arguments descriptor
//   redirecting constructor: RedirectionData
//   closure function:        ClosureData
//   irregexp function:       Array[0] = RegExp
//                            Array[1] = Smi string specialization cid
//   native function:         Array[0] = String native name
//                            Array[1] = Function implicit closure function
//   regular function:        Function for implicit closure function
void Function::set_data(const Object& value) const {
  StorePointer(&raw_ptr()->data_, value.raw());
}

bool Function::IsInFactoryScope() const {
  if (!IsLocalFunction()) {
    return IsFactory();
  }
  Function& outer_function = Function::Handle(parent_function());
  while (outer_function.IsLocalFunction()) {
    outer_function = outer_function.parent_function();
  }
  return outer_function.IsFactory();
}

void Function::set_name(const String& value) const {
  ASSERT(value.IsSymbol());
  StorePointer(&raw_ptr()->name_, value.raw());
}

void Function::set_owner(const Object& value) const {
  ASSERT(!value.IsNull() || IsSignatureFunction());
  StorePointer(&raw_ptr()->owner_, value.raw());
}

RawRegExp* Function::regexp() const {
  ASSERT(kind() == RawFunction::kIrregexpFunction);
  const Array& pair = Array::Cast(Object::Handle(raw_ptr()->data_));
  return RegExp::RawCast(pair.At(0));
}

class StickySpecialization : public BitField<intptr_t, bool, 0, 1> {};
class StringSpecializationCid
    : public BitField<intptr_t, intptr_t, 1, RawObject::kClassIdTagSize> {};

intptr_t Function::string_specialization_cid() const {
  ASSERT(kind() == RawFunction::kIrregexpFunction);
  const Array& pair = Array::Cast(Object::Handle(raw_ptr()->data_));
  return StringSpecializationCid::decode(Smi::Value(Smi::RawCast(pair.At(1))));
}

bool Function::is_sticky_specialization() const {
  ASSERT(kind() == RawFunction::kIrregexpFunction);
  const Array& pair = Array::Cast(Object::Handle(raw_ptr()->data_));
  return StickySpecialization::decode(Smi::Value(Smi::RawCast(pair.At(1))));
}

void Function::SetRegExpData(const RegExp& regexp,
                             intptr_t string_specialization_cid,
                             bool sticky) const {
  ASSERT(kind() == RawFunction::kIrregexpFunction);
  ASSERT(RawObject::IsStringClassId(string_specialization_cid));
  ASSERT(raw_ptr()->data_ == Object::null());
  const Array& pair = Array::Handle(Array::New(2, Heap::kOld));
  pair.SetAt(0, regexp);
  pair.SetAt(1, Smi::Handle(Smi::New(StickySpecialization::encode(sticky) |
                                     StringSpecializationCid::encode(
                                         string_specialization_cid))));
  set_data(pair);
}

RawString* Function::native_name() const {
  ASSERT(is_native());
  const Object& obj = Object::Handle(raw_ptr()->data_);
  ASSERT(obj.IsArray());
  return String::RawCast(Array::Cast(obj).At(0));
}

void Function::set_native_name(const String& value) const {
  Zone* zone = Thread::Current()->zone();
  ASSERT(is_native());

  // Due to the fact that kernel needs to read in the constant table before the
  // annotation data is available, we don't know at function creation time
  // whether the function is a native or not.
  //
  // Reading the constant table can cause a static function to get an implicit
  // closure function.
  //
  // We therefore handle both cases.
  const Object& old_data = Object::Handle(zone, raw_ptr()->data_);
  ASSERT(old_data.IsNull() ||
         (old_data.IsFunction() &&
          Function::Handle(zone, Function::RawCast(old_data.raw()))
              .IsImplicitClosureFunction()));

  const Array& pair = Array::Handle(zone, Array::New(2, Heap::kOld));
  pair.SetAt(0, value);
  pair.SetAt(1, old_data);  // will be the implicit closure function if needed.
  set_data(pair);
}

void Function::set_result_type(const AbstractType& value) const {
  ASSERT(!value.IsNull());
  StorePointer(&raw_ptr()->result_type_, value.raw());
}

RawAbstractType* Function::ParameterTypeAt(intptr_t index) const {
  const Array& parameter_types = Array::Handle(raw_ptr()->parameter_types_);
  return AbstractType::RawCast(parameter_types.At(index));
}

void Function::SetParameterTypeAt(intptr_t index,
                                  const AbstractType& value) const {
  ASSERT(!value.IsNull());
  // Method extractor parameters are shared and are in the VM heap.
  ASSERT(kind() != RawFunction::kMethodExtractor);
  const Array& parameter_types = Array::Handle(raw_ptr()->parameter_types_);
  parameter_types.SetAt(index, value);
}

void Function::set_parameter_types(const Array& value) const {
  StorePointer(&raw_ptr()->parameter_types_, value.raw());
}

RawString* Function::ParameterNameAt(intptr_t index) const {
  const Array& parameter_names = Array::Handle(raw_ptr()->parameter_names_);
  return String::RawCast(parameter_names.At(index));
}

void Function::SetParameterNameAt(intptr_t index, const String& value) const {
  ASSERT(!value.IsNull() && value.IsSymbol());
  const Array& parameter_names = Array::Handle(raw_ptr()->parameter_names_);
  parameter_names.SetAt(index, value);
}

void Function::set_parameter_names(const Array& value) const {
  StorePointer(&raw_ptr()->parameter_names_, value.raw());
}

void Function::set_type_parameters(const TypeArguments& value) const {
  StorePointer(&raw_ptr()->type_parameters_, value.raw());
}

intptr_t Function::NumTypeParameters(Thread* thread) const {
  if (type_parameters() == TypeArguments::null()) {
    return 0;
  }
  REUSABLE_TYPE_ARGUMENTS_HANDLESCOPE(thread);
  TypeArguments& type_params = thread->TypeArgumentsHandle();
  type_params = type_parameters();
  // We require null to represent a non-generic function.
  ASSERT(type_params.Length() != 0);
  return type_params.Length();
}

intptr_t Function::NumParentTypeParameters() const {
  if (IsImplicitClosureFunction()) {
    return 0;
  }
  Thread* thread = Thread::Current();
  Function& parent = Function::Handle(parent_function());
  intptr_t num_parent_type_params = 0;
  while (!parent.IsNull()) {
    num_parent_type_params += parent.NumTypeParameters(thread);
    if (parent.IsImplicitClosureFunction()) break;
    parent ^= parent.parent_function();
  }
  return num_parent_type_params;
}

void Function::PrintSignatureTypes() const {
  Function& sig_fun = Function::Handle(raw());
  Type& sig_type = Type::Handle();
  while (!sig_fun.IsNull()) {
    sig_type = sig_fun.SignatureType();
    THR_Print("%s%s\n",
              sig_fun.IsImplicitClosureFunction() ? "implicit closure: " : "",
              sig_type.ToCString());
    sig_fun ^= sig_fun.parent_function();
  }
}

RawTypeParameter* Function::LookupTypeParameter(
    const String& type_name,
    intptr_t* function_level) const {
  ASSERT(!type_name.IsNull());
  Thread* thread = Thread::Current();
  REUSABLE_TYPE_ARGUMENTS_HANDLESCOPE(thread);
  REUSABLE_TYPE_PARAMETER_HANDLESCOPE(thread);
  REUSABLE_STRING_HANDLESCOPE(thread);
  REUSABLE_FUNCTION_HANDLESCOPE(thread);
  TypeArguments& type_params = thread->TypeArgumentsHandle();
  TypeParameter& type_param = thread->TypeParameterHandle();
  String& type_param_name = thread->StringHandle();
  Function& function = thread->FunctionHandle();

  function ^= this->raw();
  while (!function.IsNull()) {
    type_params ^= function.type_parameters();
    if (!type_params.IsNull()) {
      const intptr_t num_type_params = type_params.Length();
      for (intptr_t i = 0; i < num_type_params; i++) {
        type_param ^= type_params.TypeAt(i);
        type_param_name = type_param.name();
        if (type_param_name.Equals(type_name)) {
          return type_param.raw();
        }
      }
    }
    if (function.IsImplicitClosureFunction()) {
      // The parent function is not the enclosing function, but the closurized
      // function with identical type parameters.
      break;
    }
    function ^= function.parent_function();
    if (function_level != NULL) {
      (*function_level)--;
    }
  }
  return TypeParameter::null();
}

void Function::set_kind(RawFunction::Kind value) const {
  set_kind_tag(KindBits::update(value, raw_ptr()->kind_tag_));
}

void Function::set_modifier(RawFunction::AsyncModifier value) const {
  set_kind_tag(ModifierBits::update(value, raw_ptr()->kind_tag_));
}

void Function::set_recognized_kind(MethodRecognizer::Kind value) const {
  // Prevent multiple settings of kind.
  ASSERT((value == MethodRecognizer::kUnknown) || !IsRecognized());
  set_kind_tag(RecognizedBits::update(value, raw_ptr()->kind_tag_));
}

void Function::set_token_pos(TokenPosition token_pos) const {
#if defined(DART_PRECOMPILED_RUNTIME)
  UNREACHABLE();
#else
  ASSERT(!token_pos.IsClassifying() || IsMethodExtractor());
  StoreNonPointer(&raw_ptr()->token_pos_, token_pos);
#endif
}

void Function::set_kind_tag(uint32_t value) const {
  StoreNonPointer(&raw_ptr()->kind_tag_, static_cast<uint32_t>(value));
}

void Function::set_num_fixed_parameters(intptr_t value) const {
  ASSERT(value >= 0);
  ASSERT(Utils::IsInt(16, value));
  StoreNonPointer(&raw_ptr()->num_fixed_parameters_,
                  static_cast<int16_t>(value));
}

void Function::set_num_optional_parameters(intptr_t value) const {
  // A positive value indicates positional params, a negative one named params.
  ASSERT(Utils::IsInt(16, value));
  StoreNonPointer(&raw_ptr()->num_optional_parameters_,
                  static_cast<int16_t>(value));
}

void Function::SetNumOptionalParameters(intptr_t num_optional_parameters,
                                        bool are_optional_positional) const {
  ASSERT(num_optional_parameters >= 0);
  set_num_optional_parameters(are_optional_positional
                                  ? num_optional_parameters
                                  : -num_optional_parameters);
}

bool Function::IsOptimizable() const {
  if (FLAG_precompiled_mode) {
    return true;
  }
  if (is_native()) {
    // Native methods don't need to be optimized.
    return false;
  }
  const intptr_t function_length = end_token_pos().Pos() - token_pos().Pos();
  if (is_optimizable() && (script() != Script::null()) &&
      (function_length < FLAG_huge_method_cutoff_in_tokens)) {
    // Additional check needed for implicit getters.
    return (unoptimized_code() == Object::null()) ||
           (Code::Handle(unoptimized_code()).Size() <
            FLAG_huge_method_cutoff_in_code_size);
  }
  return false;
}

void Function::SetIsOptimizable(bool value) const {
  ASSERT(!is_native());
  set_is_optimizable(value);
  if (!value) {
    set_is_inlinable(false);
    set_usage_counter(INT_MIN);
  }
}

bool Function::CanBeInlined() const {
#if defined(PRODUCT)
  return is_inlinable() && !is_external() && !is_generated_body();
#else
  Thread* thread = Thread::Current();
  return is_inlinable() && !is_external() && !is_generated_body() &&
         !thread->isolate()->debugger()->HasBreakpoint(*this, thread->zone());
#endif
}

intptr_t Function::NumParameters() const {
  return num_fixed_parameters() + NumOptionalParameters();
}

intptr_t Function::NumImplicitParameters() const {
  const RawFunction::Kind k = kind();
  if (k == RawFunction::kConstructor) {
    // Type arguments for factory; instance for generative constructor.
    return 1;
  }
  if ((k == RawFunction::kClosureFunction) ||
      (k == RawFunction::kImplicitClosureFunction) ||
      (k == RawFunction::kSignatureFunction) ||
      (k == RawFunction::kConvertedClosureFunction)) {
    return 1;  // Closure object.
  }
  if (!is_static()) {
    // Closure functions defined inside instance (i.e. non-static) functions are
    // marked as non-static, but they do not have a receiver.
    // Closures are handled above.
    ASSERT((k != RawFunction::kClosureFunction) &&
           (k != RawFunction::kImplicitClosureFunction) &&
           (k != RawFunction::kSignatureFunction));
    return 1;  // Receiver.
  }
  return 0;  // No implicit parameters.
}

bool Function::AreValidArgumentCounts(intptr_t num_type_arguments,
                                      intptr_t num_arguments,
                                      intptr_t num_named_arguments,
                                      String* error_message) const {
  if ((num_type_arguments != 0) &&
      (num_type_arguments != NumTypeParameters())) {
    if (error_message != NULL) {
      const intptr_t kMessageBufferSize = 64;
      char message_buffer[kMessageBufferSize];
      Utils::SNPrint(message_buffer, kMessageBufferSize,
                     "%" Pd " type arguments passed, but %" Pd " expected",
                     num_type_arguments, NumTypeParameters());
      // Allocate in old space because it can be invoked in background
      // optimizing compilation.
      *error_message = String::New(message_buffer, Heap::kOld);
    }
    return false;  // Too many type arguments.
  }
  if (num_named_arguments > NumOptionalNamedParameters()) {
    if (error_message != NULL) {
      const intptr_t kMessageBufferSize = 64;
      char message_buffer[kMessageBufferSize];
      Utils::SNPrint(message_buffer, kMessageBufferSize,
                     "%" Pd " named passed, at most %" Pd " expected",
                     num_named_arguments, NumOptionalNamedParameters());
      // Allocate in old space because it can be invoked in background
      // optimizing compilation.
      *error_message = String::New(message_buffer, Heap::kOld);
    }
    return false;  // Too many named arguments.
  }
  const intptr_t num_pos_args = num_arguments - num_named_arguments;
  const intptr_t num_opt_pos_params = NumOptionalPositionalParameters();
  const intptr_t num_pos_params = num_fixed_parameters() + num_opt_pos_params;
  if (num_pos_args > num_pos_params) {
    if (error_message != NULL) {
      const intptr_t kMessageBufferSize = 64;
      char message_buffer[kMessageBufferSize];
      // Hide implicit parameters to the user.
      const intptr_t num_hidden_params = NumImplicitParameters();
      Utils::SNPrint(message_buffer, kMessageBufferSize,
                     "%" Pd "%s passed, %s%" Pd " expected",
                     num_pos_args - num_hidden_params,
                     num_opt_pos_params > 0 ? " positional" : "",
                     num_opt_pos_params > 0 ? "at most " : "",
                     num_pos_params - num_hidden_params);
      // Allocate in old space because it can be invoked in background
      // optimizing compilation.
      *error_message = String::New(message_buffer, Heap::kOld);
    }
    return false;  // Too many fixed and/or positional arguments.
  }
  if (num_pos_args < num_fixed_parameters()) {
    if (error_message != NULL) {
      const intptr_t kMessageBufferSize = 64;
      char message_buffer[kMessageBufferSize];
      // Hide implicit parameters to the user.
      const intptr_t num_hidden_params = NumImplicitParameters();
      Utils::SNPrint(message_buffer, kMessageBufferSize,
                     "%" Pd "%s passed, %s%" Pd " expected",
                     num_pos_args - num_hidden_params,
                     num_opt_pos_params > 0 ? " positional" : "",
                     num_opt_pos_params > 0 ? "at least " : "",
                     num_fixed_parameters() - num_hidden_params);
      // Allocate in old space because it can be invoked in background
      // optimizing compilation.
      *error_message = String::New(message_buffer, Heap::kOld);
    }
    return false;  // Too few fixed and/or positional arguments.
  }
  return true;
}

bool Function::AreValidArguments(intptr_t num_type_arguments,
                                 intptr_t num_arguments,
                                 const Array& argument_names,
                                 String* error_message) const {
  const intptr_t num_named_arguments =
      argument_names.IsNull() ? 0 : argument_names.Length();
  if (!AreValidArgumentCounts(num_type_arguments, num_arguments,
                              num_named_arguments, error_message)) {
    return false;
  }
  // Verify that all argument names are valid parameter names.
  Zone* zone = Thread::Current()->zone();
  String& argument_name = String::Handle(zone);
  String& parameter_name = String::Handle(zone);
  for (intptr_t i = 0; i < num_named_arguments; i++) {
    argument_name ^= argument_names.At(i);
    ASSERT(argument_name.IsSymbol());
    bool found = false;
    const intptr_t num_positional_args = num_arguments - num_named_arguments;
    const intptr_t num_parameters = NumParameters();
    for (intptr_t j = num_positional_args; !found && (j < num_parameters);
         j++) {
      parameter_name = ParameterNameAt(j);
      ASSERT(argument_name.IsSymbol());
      if (argument_name.Equals(parameter_name)) {
        found = true;
      }
    }
    if (!found) {
      if (error_message != NULL) {
        const intptr_t kMessageBufferSize = 64;
        char message_buffer[kMessageBufferSize];
        Utils::SNPrint(message_buffer, kMessageBufferSize,
                       "no optional formal parameter named '%s'",
                       argument_name.ToCString());
        // Allocate in old space because it can be invoked in background
        // optimizing compilation.
        *error_message = String::New(message_buffer, Heap::kOld);
      }
      return false;
    }
  }
  return true;
}

bool Function::AreValidArguments(const ArgumentsDescriptor& args_desc,
                                 String* error_message) const {
  const intptr_t num_type_arguments = args_desc.TypeArgsLen();
  const intptr_t num_arguments = args_desc.Count();
  const intptr_t num_named_arguments = args_desc.NamedCount();

  if (!AreValidArgumentCounts(num_type_arguments, num_arguments,
                              num_named_arguments, error_message)) {
    return false;
  }
  // Verify that all argument names are valid parameter names.
  Zone* zone = Thread::Current()->zone();
  String& argument_name = String::Handle(zone);
  String& parameter_name = String::Handle(zone);
  for (intptr_t i = 0; i < num_named_arguments; i++) {
    argument_name ^= args_desc.NameAt(i);
    ASSERT(argument_name.IsSymbol());
    bool found = false;
    const intptr_t num_positional_args = num_arguments - num_named_arguments;
    const int num_parameters = NumParameters();
    for (intptr_t j = num_positional_args; !found && (j < num_parameters);
         j++) {
      parameter_name = ParameterNameAt(j);
      ASSERT(argument_name.IsSymbol());
      if (argument_name.Equals(parameter_name)) {
        found = true;
      }
    }
    if (!found) {
      if (error_message != NULL) {
        const intptr_t kMessageBufferSize = 64;
        char message_buffer[kMessageBufferSize];
        Utils::SNPrint(message_buffer, kMessageBufferSize,
                       "no optional formal parameter named '%s'",
                       argument_name.ToCString());
        // Allocate in old space because it can be invoked in background
        // optimizing compilation.
        *error_message = String::New(message_buffer, Heap::kOld);
      }
      return false;
    }
  }
  return true;
}

// Helper allocating a C string buffer in the zone, printing the fully qualified
// name of a function in it, and replacing ':' by '_' to make sure the
// constructed name is a valid C++ identifier for debugging purpose.
// Set 'chars' to allocated buffer and return number of written characters.

enum QualifiedFunctionLibKind {
  kQualifiedFunctionLibKindLibUrl,
  kQualifiedFunctionLibKindLibName
};

static intptr_t ConstructFunctionFullyQualifiedCString(
    const Function& function,
    char** chars,
    intptr_t reserve_len,
    bool with_lib,
    QualifiedFunctionLibKind lib_kind) {
  const char* name = String::Handle(function.name()).ToCString();
  const char* function_format = (reserve_len == 0) ? "%s" : "%s_";
  reserve_len += Utils::SNPrint(NULL, 0, function_format, name);
  const Function& parent = Function::Handle(function.parent_function());
  intptr_t written = 0;
  if (parent.IsNull()) {
    const Class& function_class = Class::Handle(function.Owner());
    ASSERT(!function_class.IsNull());
    const char* class_name = String::Handle(function_class.Name()).ToCString();
    ASSERT(class_name != NULL);
    const Library& library = Library::Handle(function_class.library());
    ASSERT(!library.IsNull());
    const char* library_name = NULL;
    const char* lib_class_format = NULL;
    if (with_lib) {
      switch (lib_kind) {
        case kQualifiedFunctionLibKindLibUrl:
          library_name = String::Handle(library.url()).ToCString();
          break;
        case kQualifiedFunctionLibKindLibName:
          library_name = String::Handle(library.name()).ToCString();
          break;
        default:
          UNREACHABLE();
      }
      ASSERT(library_name != NULL);
      lib_class_format = (library_name[0] == '\0') ? "%s%s_" : "%s_%s_";
    } else {
      library_name = "";
      lib_class_format = "%s%s.";
    }
    reserve_len +=
        Utils::SNPrint(NULL, 0, lib_class_format, library_name, class_name);
    ASSERT(chars != NULL);
    *chars = Thread::Current()->zone()->Alloc<char>(reserve_len + 1);
    written = Utils::SNPrint(*chars, reserve_len + 1, lib_class_format,
                             library_name, class_name);
  } else {
    written = ConstructFunctionFullyQualifiedCString(parent, chars, reserve_len,
                                                     with_lib, lib_kind);
  }
  ASSERT(*chars != NULL);
  char* next = *chars + written;
  written += Utils::SNPrint(next, reserve_len + 1, function_format, name);
  // Replace ":" with "_".
  while (true) {
    next = strchr(next, ':');
    if (next == NULL) break;
    *next = '_';
  }
  return written;
}

const char* Function::ToFullyQualifiedCString() const {
  char* chars = NULL;
  ConstructFunctionFullyQualifiedCString(*this, &chars, 0, true,
                                         kQualifiedFunctionLibKindLibUrl);
  return chars;
}

const char* Function::ToLibNamePrefixedQualifiedCString() const {
  char* chars = NULL;
  ConstructFunctionFullyQualifiedCString(*this, &chars, 0, true,
                                         kQualifiedFunctionLibKindLibName);
  return chars;
}

const char* Function::ToQualifiedCString() const {
  char* chars = NULL;
  ConstructFunctionFullyQualifiedCString(*this, &chars, 0, false,
                                         kQualifiedFunctionLibKindLibUrl);
  return chars;
}

bool Function::HasCompatibleParametersWith(const Function& other,
                                           Error* bound_error) const {
  ASSERT(Isolate::Current()->error_on_bad_override());
  ASSERT(!Isolate::Current()->strong());
  ASSERT((bound_error != NULL) && bound_error->IsNull());
  // Check that this function's signature type is a subtype of the other
  // function's signature type.
  // Map type parameters referred to by formal parameter types and result type
  // in the signature to dynamic before the test.
  // Note that type parameters declared by a generic signature are preserved.
  Function& this_fun = Function::Handle(raw());
  if (!this_fun.HasInstantiatedSignature(kCurrentClass)) {
    this_fun = this_fun.InstantiateSignatureFrom(
        Object::null_type_arguments(), Object::null_type_arguments(),
        kNoneFree,  // Keep function type parameters, do not map to dynamic.
        Heap::kOld);
  }
  Function& other_fun = Function::Handle(other.raw());
  if (!other_fun.HasInstantiatedSignature(kCurrentClass)) {
    other_fun = other_fun.InstantiateSignatureFrom(
        Object::null_type_arguments(), Object::null_type_arguments(),
        kNoneFree,  // Keep function type parameters, do not map to dynamic.
        Heap::kOld);
  }
  if (!this_fun.TypeTest(kIsSubtypeOf, other_fun, bound_error, NULL,
                         Heap::kOld)) {
    // For more informative error reporting, use the location of the other
    // function here, since the caller will use the location of this function.
    *bound_error = LanguageError::NewFormatted(
        *bound_error,  // A bound error if non null.
        Script::Handle(other.script()), other.token_pos(), Report::AtLocation,
        Report::kError, Heap::kNew,
        "signature type '%s' of function '%s' is not a subtype of signature "
        "type '%s' of function '%s'\n",
        String::Handle(UserVisibleSignature()).ToCString(),
        String::Handle(UserVisibleName()).ToCString(),
        String::Handle(other.UserVisibleSignature()).ToCString(),
        String::Handle(other.UserVisibleName()).ToCString());
    return false;
  }
  // We should also check that if the other function explicitly specifies a
  // default value for a formal parameter, this function does not specify a
  // different default value for the same parameter. However, this check is not
  // possible in the current implementation, because the default parameter
  // values are not stored in the Function object, but discarded after a
  // function is compiled.
  return true;
}

RawFunction* Function::InstantiateSignatureFrom(
    const TypeArguments& instantiator_type_arguments,
    const TypeArguments& function_type_arguments,
    intptr_t num_free_fun_type_params,
    Heap::Space space) const {
  Zone* zone = Thread::Current()->zone();
  const Object& owner = Object::Handle(zone, RawOwner());
  // Note that parent pointers in newly instantiated signatures still points to
  // the original uninstantiated parent signatures. That is not a problem.
  const Function& parent = Function::Handle(zone, parent_function());

  // See the comment on kCurrentAndEnclosingFree to understand why we don't
  // adjust 'num_free_fun_type_params' downward in this case.
  bool delete_type_parameters = false;
  if (num_free_fun_type_params == kCurrentAndEnclosingFree) {
    num_free_fun_type_params = kAllFree;
    delete_type_parameters = true;
  } else {
    ASSERT(!HasInstantiatedSignature(kAny, num_free_fun_type_params));

    // A generic typedef may declare a non-generic function type and get
    // instantiated with unrelated function type parameters. In that case, its
    // signature is still uninstantiated, because these type parameters are
    // free (they are not declared by the typedef).
    // For that reason, we only adjust num_free_fun_type_params if this
    // signature is generic or has a generic parent.
    if (IsGeneric() || HasGenericParent()) {
      // We only consider the function type parameters declared by the parents
      // of this signature function as free.
      const int num_parent_type_params = NumParentTypeParameters();
      if (num_parent_type_params < num_free_fun_type_params) {
        num_free_fun_type_params = num_parent_type_params;
      }
    }
  }

  Function& sig = Function::Handle(zone, Function::null());
  if (IsConvertedClosureFunction() && !delete_type_parameters) {
    sig = Function::NewConvertedClosureFunction(
        String::Handle(zone, name()), parent, TokenPosition::kNoSource);
    // TODO(30455): Kernel generic methods undone. Handle type parameters
    // correctly when generic closures are supported. Until then, all type
    // parameters to this target are used for captured type variables, so they
    // aren't relevant to the type of the function.
    sig.set_type_parameters(TypeArguments::Handle(zone, TypeArguments::null()));
  } else {
    sig = Function::NewSignatureFunction(owner, parent,
                                         TokenPosition::kNoSource, space);
    if (!delete_type_parameters) {
      sig.set_type_parameters(TypeArguments::Handle(zone, type_parameters()));
    }
  }

  AbstractType& type = AbstractType::Handle(zone, result_type());
  if (!type.IsInstantiated(kAny, num_free_fun_type_params)) {
    type = type.InstantiateFrom(
        instantiator_type_arguments, function_type_arguments,
        num_free_fun_type_params, NULL, NULL, NULL, space);
  }
  sig.set_result_type(type);
  const intptr_t num_params = NumParameters();
  sig.set_num_fixed_parameters(num_fixed_parameters());
  sig.SetNumOptionalParameters(NumOptionalParameters(),
                               HasOptionalPositionalParameters());
  sig.set_parameter_types(Array::Handle(Array::New(num_params, space)));
  for (intptr_t i = 0; i < num_params; i++) {
    type = ParameterTypeAt(i);
    if (!type.IsInstantiated(kAny, num_free_fun_type_params)) {
      type = type.InstantiateFrom(
          instantiator_type_arguments, function_type_arguments,
          num_free_fun_type_params, NULL, NULL, NULL, space);
    }
    sig.SetParameterTypeAt(i, type);
  }
  sig.set_parameter_names(Array::Handle(zone, parameter_names()));

  if (delete_type_parameters) {
    ASSERT(sig.HasInstantiatedSignature(kFunctions));
  }
  return sig.raw();
}

// If test_kind == kIsSubtypeOf, checks if the type of the specified parameter
// of this function is a subtype or a supertype of the type of the specified
// parameter of the other function. In strong mode, we only check for supertype,
// i.e. contravariance.
// Note that types marked as covariant are already dealt with in the front-end.
// If test_kind == kIsMoreSpecificThan, checks if the type of the specified
// parameter of this function is more specific than the type of the specified
// parameter of the other function.
// Note that for kIsMoreSpecificThan (non-strong mode only), we do not apply
// contravariance of parameter types, but covariance of both parameter types and
// result type.
bool Function::TestParameterType(TypeTestKind test_kind,
                                 intptr_t parameter_position,
                                 intptr_t other_parameter_position,
                                 const Function& other,
                                 Error* bound_error,
                                 TrailPtr bound_trail,
                                 Heap::Space space) const {
  if (Isolate::Current()->strong()) {
    const AbstractType& param_type =
        AbstractType::Handle(ParameterTypeAt(parameter_position));
    if (param_type.IsTopType()) {
      return true;
    }
    const AbstractType& other_param_type =
        AbstractType::Handle(other.ParameterTypeAt(other_parameter_position));
    return other_param_type.IsSubtypeOf(param_type, bound_error, bound_trail,
                                        space);
  }
  const AbstractType& other_param_type =
      AbstractType::Handle(other.ParameterTypeAt(other_parameter_position));
  if (other_param_type.IsDynamicType()) {
    return true;
  }
  const AbstractType& param_type =
      AbstractType::Handle(ParameterTypeAt(parameter_position));
  if (param_type.IsDynamicType()) {
    return test_kind == kIsSubtypeOf;
  }
  if (test_kind == kIsSubtypeOf) {
    return param_type.IsSubtypeOf(other_param_type, bound_error, bound_trail,
                                  space) ||
           other_param_type.IsSubtypeOf(param_type, bound_error, bound_trail,
                                        space);
  }
  ASSERT(test_kind == kIsMoreSpecificThan);
  return param_type.IsMoreSpecificThan(other_param_type, bound_error,
                                       bound_trail, space);
}

bool Function::HasSameTypeParametersAndBounds(const Function& other) const {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();

  const intptr_t num_type_params = NumTypeParameters(thread);
  if (num_type_params != other.NumTypeParameters(thread)) {
    return false;
  }
  if (num_type_params > 0) {
    const TypeArguments& type_params =
        TypeArguments::Handle(zone, type_parameters());
    ASSERT(!type_params.IsNull());
    const TypeArguments& other_type_params =
        TypeArguments::Handle(zone, other.type_parameters());
    ASSERT(!other_type_params.IsNull());
    TypeParameter& type_param = TypeParameter::Handle(zone);
    TypeParameter& other_type_param = TypeParameter::Handle(zone);
    AbstractType& bound = AbstractType::Handle(zone);
    AbstractType& other_bound = AbstractType::Handle(zone);
    for (intptr_t i = 0; i < num_type_params; i++) {
      type_param ^= type_params.TypeAt(i);
      other_type_param ^= other_type_params.TypeAt(i);
      bound = type_param.bound();
      ASSERT(bound.IsFinalized());
      other_bound = other_type_param.bound();
      ASSERT(other_bound.IsFinalized());
      if (!bound.Equals(other_bound)) {
        return false;
      }
    }
  }
  return true;
}

bool Function::TypeTest(TypeTestKind test_kind,
                        const Function& other,
                        Error* bound_error,
                        TrailPtr bound_trail,
                        Heap::Space space) const {
  const intptr_t num_fixed_params = num_fixed_parameters();
  const intptr_t num_opt_pos_params = NumOptionalPositionalParameters();
  const intptr_t num_opt_named_params = NumOptionalNamedParameters();
  const intptr_t other_num_fixed_params = other.num_fixed_parameters();
  const intptr_t other_num_opt_pos_params =
      other.NumOptionalPositionalParameters();
  const intptr_t other_num_opt_named_params =
      other.NumOptionalNamedParameters();
  // This function requires the same arguments or less and accepts the same
  // arguments or more. We can ignore implicit parameters.
  const intptr_t num_ignored_params = NumImplicitParameters();
  const intptr_t other_num_ignored_params = other.NumImplicitParameters();
  if (((num_fixed_params - num_ignored_params) >
       (other_num_fixed_params - other_num_ignored_params)) ||
      ((num_fixed_params - num_ignored_params + num_opt_pos_params) <
       (other_num_fixed_params - other_num_ignored_params +
        other_num_opt_pos_params)) ||
      (num_opt_named_params < other_num_opt_named_params)) {
    return false;
  }
  Isolate* isolate = Isolate::Current();
  if (isolate->reify_generic_functions()) {
    // Check the type parameters and bounds of generic functions.
    if (!HasSameTypeParametersAndBounds(other)) {
      return false;
    }
  }
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  // Check the result type.
  const AbstractType& other_res_type =
      AbstractType::Handle(zone, other.result_type());
  if (isolate->strong()) {
    // In strong mode, 'void Function()' is a subtype of 'Object Function()'.
    if (!other_res_type.IsTopType()) {
      const AbstractType& res_type = AbstractType::Handle(zone, result_type());
      if (!res_type.IsSubtypeOf(other_res_type, bound_error, bound_trail,
                                space)) {
        return false;
      }
    }
  } else {
    // In Dart 1.0, 'void Function()' is not a subtype of 'Object Function()',
    // but it is a subtype of 'dynamic Function()' and of 'void Function()'.
    if (!other_res_type.IsDynamicType() && !other_res_type.IsVoidType()) {
      const AbstractType& res_type = AbstractType::Handle(zone, result_type());
      if (res_type.IsVoidType()) {
        return false;
      }
      if (test_kind == kIsSubtypeOf) {
        if (!res_type.IsSubtypeOf(other_res_type, bound_error, bound_trail,
                                  space) &&
            !other_res_type.IsSubtypeOf(res_type, bound_error, bound_trail,
                                        space)) {
          return false;
        }
      } else {
        ASSERT(test_kind == kIsMoreSpecificThan);
        if (!res_type.IsMoreSpecificThan(other_res_type, bound_error,
                                         bound_trail, space)) {
          return false;
        }
      }
    }
  }
  // Check the types of fixed and optional positional parameters.
  for (intptr_t i = 0; i < (other_num_fixed_params - other_num_ignored_params +
                            other_num_opt_pos_params);
       i++) {
    if (!TestParameterType(test_kind, i + num_ignored_params,
                           i + other_num_ignored_params, other, bound_error,
                           bound_trail, space)) {
      return false;
    }
  }
  // Check the names and types of optional named parameters.
  if (other_num_opt_named_params == 0) {
    return true;
  }
  // Check that for each optional named parameter of type T of the other
  // function type, there exists an optional named parameter of this function
  // type with an identical name and with a type S that is a either a subtype
  // or supertype of T (if test_kind == kIsSubtypeOf) or that is more specific
  // than T (if test_kind == kIsMoreSpecificThan). In strong mode, we only check
  // for supertype, i.e. contravariance.
  // Note that SetParameterNameAt() guarantees that names are symbols, so we
  // can compare their raw pointers.
  const int num_params = num_fixed_params + num_opt_named_params;
  const int other_num_params =
      other_num_fixed_params + other_num_opt_named_params;
  bool found_param_name;
  String& other_param_name = String::Handle(zone);
  for (intptr_t i = other_num_fixed_params; i < other_num_params; i++) {
    other_param_name = other.ParameterNameAt(i);
    ASSERT(other_param_name.IsSymbol());
    found_param_name = false;
    for (intptr_t j = num_fixed_params; j < num_params; j++) {
      ASSERT(String::Handle(zone, ParameterNameAt(j)).IsSymbol());
      if (ParameterNameAt(j) == other_param_name.raw()) {
        found_param_name = true;
        if (!TestParameterType(test_kind, j, i, other, bound_error, bound_trail,
                               space)) {
          return false;
        }
        break;
      }
    }
    if (!found_param_name) {
      return false;
    }
  }
  return true;
}

// The compiler generates an implicit constructor if a class definition
// does not contain an explicit constructor or factory. The implicit
// constructor has the same token position as the owner class.
bool Function::IsImplicitConstructor() const {
  return IsGenerativeConstructor() && (token_pos() == end_token_pos());
}

bool Function::IsImplicitStaticClosureFunction(RawFunction* func) {
  NoSafepointScope no_safepoint;
  uint32_t kind_tag = func->ptr()->kind_tag_;
  return (KindBits::decode(kind_tag) ==
          RawFunction::kImplicitClosureFunction) &&
         StaticBit::decode(kind_tag);
}

RawFunction* Function::New(Heap::Space space) {
  ASSERT(Object::function_class() != Class::null());
  RawObject* raw =
      Object::Allocate(Function::kClassId, Function::InstanceSize(), space);
  return reinterpret_cast<RawFunction*>(raw);
}

RawFunction* Function::New(const String& name,
                           RawFunction::Kind kind,
                           bool is_static,
                           bool is_const,
                           bool is_abstract,
                           bool is_external,
                           bool is_native,
                           const Object& owner,
                           TokenPosition token_pos,
                           Heap::Space space) {
  ASSERT(!owner.IsNull() || (kind == RawFunction::kSignatureFunction));
  const Function& result = Function::Handle(Function::New(space));
  result.set_parameter_types(Object::empty_array());
  result.set_parameter_names(Object::empty_array());
  result.set_name(name);
  result.set_kind(kind);
  result.set_recognized_kind(MethodRecognizer::kUnknown);
  result.set_modifier(RawFunction::kNoModifier);
  result.set_is_static(is_static);
  result.set_is_const(is_const);
  result.set_is_abstract(is_abstract);
  result.set_is_external(is_external);
  result.set_is_native(is_native);
  result.set_is_reflectable(true);  // Will be computed later.
  result.set_is_visible(true);      // Will be computed later.
  result.set_is_debuggable(true);   // Will be computed later.
  result.set_is_intrinsic(false);
  result.set_is_redirecting(false);
  result.set_is_generated_body(false);
  result.set_always_inline(false);
  result.set_is_polymorphic_target(false);
  NOT_IN_PRECOMPILED(result.set_state_bits(0));
  result.set_owner(owner);
  NOT_IN_PRECOMPILED(result.set_token_pos(token_pos));
  NOT_IN_PRECOMPILED(result.set_end_token_pos(token_pos));
  result.set_num_fixed_parameters(0);
  result.set_num_optional_parameters(0);
  NOT_IN_PRECOMPILED(result.set_usage_counter(0));
  NOT_IN_PRECOMPILED(result.set_deoptimization_counter(0));
  NOT_IN_PRECOMPILED(result.set_optimized_instruction_count(0));
  NOT_IN_PRECOMPILED(result.set_optimized_call_site_count(0));
  NOT_IN_PRECOMPILED(result.set_inlining_depth(0));
  NOT_IN_PRECOMPILED(result.set_kernel_offset(0));
  result.set_is_optimizable(is_native ? false : true);
  result.set_is_inlinable(true);
  result.set_allows_hoisting_check_class(true);
  result.set_allows_bounds_check_generalization(true);
  result.SetInstructionsSafe(
      Code::Handle(StubCode::LazyCompile_entry()->code()));
  if (kind == RawFunction::kClosureFunction ||
      kind == RawFunction::kImplicitClosureFunction ||
      kind == RawFunction::kConvertedClosureFunction) {
    ASSERT(space == Heap::kOld);
    const ClosureData& data = ClosureData::Handle(ClosureData::New());
    result.set_data(data);
  } else if (kind == RawFunction::kSignatureFunction) {
    const SignatureData& data =
        SignatureData::Handle(SignatureData::New(space));
    result.set_data(data);
  } else {
    // Functions other than signature functions have no reason to be allocated
    // in new space.
    ASSERT(space == Heap::kOld);
  }
  return result.raw();
}

RawFunction* Function::Clone(const Class& new_owner) const {
  ASSERT(!IsGenerativeConstructor());
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  Function& clone = Function::Handle(zone);
  clone ^= Object::Clone(*this, Heap::kOld);
  const Class& origin = Class::Handle(zone, this->origin());
  const PatchClass& clone_owner =
      PatchClass::Handle(zone, PatchClass::New(new_owner, origin));
  clone.set_owner(clone_owner);
  clone.ClearICDataArray();
  clone.ClearCode();
  clone.set_usage_counter(0);
  clone.set_deoptimization_counter(0);
  clone.set_optimized_instruction_count(0);
  clone.set_inlining_depth(0);
  clone.set_optimized_call_site_count(0);
  clone.set_kernel_offset(kernel_offset());

  if (new_owner.NumTypeParameters() > 0) {
    // Adjust uninstantiated types to refer to type parameters of the new owner.
    const TypeArguments& type_params =
        TypeArguments::Handle(zone, type_parameters());
    if (!type_params.IsNull()) {
      const intptr_t num_type_params = type_params.Length();
      const TypeArguments& type_params_clone =
          TypeArguments::Handle(zone, TypeArguments::New(num_type_params));
      TypeParameter& type_param = TypeParameter::Handle(zone);
      for (intptr_t i = 0; i < num_type_params; i++) {
        type_param ^= type_params.TypeAt(i);
        type_param ^= type_param.CloneUninstantiated(new_owner);
        type_params_clone.SetTypeAt(i, type_param);
      }
      clone.set_type_parameters(type_params_clone);
    }
    AbstractType& type = AbstractType::Handle(zone, clone.result_type());
    type ^= type.CloneUninstantiated(new_owner);
    clone.set_result_type(type);
    const intptr_t num_params = clone.NumParameters();
    Array& array = Array::Handle(zone, clone.parameter_types());
    array ^= Object::Clone(array, Heap::kOld);
    clone.set_parameter_types(array);
    for (intptr_t i = 0; i < num_params; i++) {
      type = clone.ParameterTypeAt(i);
      type ^= type.CloneUninstantiated(new_owner);
      clone.SetParameterTypeAt(i, type);
    }
  }
  return clone.raw();
}

RawFunction* Function::NewClosureFunctionWithKind(RawFunction::Kind kind,
                                                  const String& name,
                                                  const Function& parent,
                                                  TokenPosition token_pos) {
  ASSERT((kind == RawFunction::kClosureFunction) ||
         (kind == RawFunction::kImplicitClosureFunction) ||
         (kind == RawFunction::kConvertedClosureFunction));
  ASSERT(!parent.IsNull());
  // Only static top-level functions are allowed to be converted right now.
  ASSERT((kind != RawFunction::kConvertedClosureFunction) ||
         parent.is_static());
  // Use the owner defining the parent function and not the class containing it.
  const Object& parent_owner = Object::Handle(parent.raw_ptr()->owner_);
  ASSERT(!parent_owner.IsNull());
  const Function& result = Function::Handle(
      Function::New(name, kind,
                    /* is_static = */ parent.is_static(),
                    /* is_const = */ false,
                    /* is_abstract = */ false,
                    /* is_external = */ false,
                    /* is_native = */ false, parent_owner, token_pos));
  result.set_parent_function(parent);
  return result.raw();
}

RawFunction* Function::NewClosureFunction(const String& name,
                                          const Function& parent,
                                          TokenPosition token_pos) {
  return NewClosureFunctionWithKind(RawFunction::kClosureFunction, name, parent,
                                    token_pos);
}

RawFunction* Function::NewImplicitClosureFunction(const String& name,
                                                  const Function& parent,
                                                  TokenPosition token_pos) {
  return NewClosureFunctionWithKind(RawFunction::kImplicitClosureFunction, name,
                                    parent, token_pos);
}

RawFunction* Function::NewConvertedClosureFunction(const String& name,
                                                   const Function& parent,
                                                   TokenPosition token_pos) {
  return NewClosureFunctionWithKind(RawFunction::kConvertedClosureFunction,
                                    name, parent, token_pos);
}

RawFunction* Function::NewSignatureFunction(const Object& owner,
                                            const Function& parent,
                                            TokenPosition token_pos,
                                            Heap::Space space) {
  const Function& result = Function::Handle(Function::New(
      Symbols::AnonymousSignature(), RawFunction::kSignatureFunction,
      /* is_static = */ false,
      /* is_const = */ false,
      /* is_abstract = */ false,
      /* is_external = */ false,
      /* is_native = */ false,
      owner,  // Same as function type scope class.
      token_pos, space));
  result.set_parent_function(parent);
  result.set_is_reflectable(false);
  result.set_is_visible(false);
  result.set_is_debuggable(false);
  return result.raw();
}

RawFunction* Function::NewEvalFunction(const Class& owner,
                                       const Script& script,
                                       bool is_static) {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  const Function& result = Function::Handle(
      zone,
      Function::New(String::Handle(Symbols::New(thread, ":Eval")),
                    RawFunction::kRegularFunction, is_static,
                    /* is_const = */ false,
                    /* is_abstract = */ false,
                    /* is_external = */ false,
                    /* is_native = */ false, owner, TokenPosition::kMinSource));
  ASSERT(!script.IsNull());
  result.set_is_debuggable(false);
  result.set_is_visible(true);
  result.set_eval_script(script);
  return result.raw();
}

RawFunction* Function::ImplicitClosureFunction() const {
  // Return the existing implicit closure function if any.
  if (implicit_closure_function() != Function::null()) {
    return implicit_closure_function();
  }
#if defined(DART_PRECOMPILED_RUNTIME)
  // In AOT mode all implicit closures are pre-created.
  UNREACHABLE();
  return Function::null();
#else
  ASSERT(!IsSignatureFunction() && !IsClosureFunction());
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  // Create closure function.
  const String& closure_name = String::Handle(zone, name());
  const Function& closure_function = Function::Handle(
      zone, NewImplicitClosureFunction(closure_name, *this, token_pos()));

  // Set closure function's context scope.
  if (is_static()) {
    closure_function.set_context_scope(Object::empty_context_scope());
  } else {
    const ContextScope& context_scope = ContextScope::Handle(
        zone, LocalScope::CreateImplicitClosureScope(*this));
    closure_function.set_context_scope(context_scope);
  }

  // Set closure function's type parameters.
  closure_function.set_type_parameters(
      TypeArguments::Handle(zone, type_parameters()));

  // Set closure function's result type to this result type.
  closure_function.set_result_type(AbstractType::Handle(zone, result_type()));

  // Set closure function's end token to this end token.
  closure_function.set_end_token_pos(end_token_pos());

  // The closurized method stub just calls into the original method and should
  // therefore be skipped by the debugger and in stack traces.
  closure_function.set_is_debuggable(false);
  closure_function.set_is_visible(false);

  // Set closure function's formal parameters to this formal parameters,
  // removing the receiver if this is an instance method and adding the closure
  // object as first parameter.
  const int kClosure = 1;
  const int has_receiver = is_static() ? 0 : 1;
  const int num_fixed_params = kClosure - has_receiver + num_fixed_parameters();
  const int num_opt_params = NumOptionalParameters();
  const bool has_opt_pos_params = HasOptionalPositionalParameters();
  const int num_params = num_fixed_params + num_opt_params;
  closure_function.set_num_fixed_parameters(num_fixed_params);
  closure_function.SetNumOptionalParameters(num_opt_params, has_opt_pos_params);
  closure_function.set_parameter_types(
      Array::Handle(zone, Array::New(num_params, Heap::kOld)));
  closure_function.set_parameter_names(
      Array::Handle(zone, Array::New(num_params, Heap::kOld)));
  AbstractType& param_type = AbstractType::Handle(zone);
  String& param_name = String::Handle(zone);
  // Add implicit closure object parameter.
  param_type = Type::DynamicType();
  closure_function.SetParameterTypeAt(0, param_type);
  closure_function.SetParameterNameAt(0, Symbols::ClosureParameter());
  for (int i = kClosure; i < num_params; i++) {
    param_type = ParameterTypeAt(has_receiver - kClosure + i);
    closure_function.SetParameterTypeAt(i, param_type);
    param_name = ParameterNameAt(has_receiver - kClosure + i);
    closure_function.SetParameterNameAt(i, param_name);
  }
  closure_function.set_kernel_offset(kernel_offset());

  // In strong mode, change covariant parameter types to Object in the implicit
  // closure of a method compiled by kernel.
  // The VM's parser erases covariant types immediately in strong mode.
  if (thread->isolate()->strong() && !is_static() && (kernel_offset() > 0)) {
    const Script& function_script = Script::Handle(zone, script());
    kernel::TranslationHelper translation_helper(thread);
    kernel::StreamingFlowGraphBuilder builder(
        &translation_helper, function_script, zone,
        TypedData::Handle(zone, KernelData()), KernelDataProgramOffset());
    translation_helper.InitFromScript(function_script);
    builder.SetOffset(kernel_offset());

    builder.ReadUntilFunctionNode();
    kernel::FunctionNodeHelper fn_helper(&builder);

    // Check the positional parameters, including the optional positional ones.
    fn_helper.ReadUntilExcluding(
        kernel::FunctionNodeHelper::kPositionalParameters);
    intptr_t num_pos_params = builder.ReadListLength();
    ASSERT(num_pos_params ==
           num_fixed_params - 1 + (has_opt_pos_params ? num_opt_params : 0));
    const Type& object_type = Type::Handle(zone, Type::ObjectType());
    for (intptr_t i = 0; i < num_pos_params; ++i) {
      kernel::VariableDeclarationHelper var_helper(&builder);
      var_helper.ReadUntilExcluding(kernel::VariableDeclarationHelper::kEnd);
      if (var_helper.IsCovariant() || var_helper.IsGenericCovariantImpl()) {
        closure_function.SetParameterTypeAt(i + 1, object_type);
      }
    }
    fn_helper.SetJustRead(kernel::FunctionNodeHelper::kPositionalParameters);

    // Check the optional named parameters.
    fn_helper.ReadUntilExcluding(kernel::FunctionNodeHelper::kNamedParameters);
    intptr_t num_named_params = builder.ReadListLength();
    ASSERT(num_named_params == (has_opt_pos_params ? 0 : num_opt_params));
    for (intptr_t i = 0; i < num_named_params; ++i) {
      kernel::VariableDeclarationHelper var_helper(&builder);
      var_helper.ReadUntilExcluding(kernel::VariableDeclarationHelper::kEnd);
      if (var_helper.IsCovariant() || var_helper.IsGenericCovariantImpl()) {
        closure_function.SetParameterTypeAt(num_pos_params + 1 + i,
                                            object_type);
      }
    }
  }
  const Type& signature_type =
      Type::Handle(zone, closure_function.SignatureType());
  if (!signature_type.IsFinalized()) {
    ClassFinalizer::FinalizeType(Class::Handle(zone, Owner()), signature_type);
  }
  set_implicit_closure_function(closure_function);
  ASSERT(closure_function.IsImplicitClosureFunction());
  return closure_function.raw();
#endif  // defined(DART_PRECOMPILED_RUNTIME)
}

void Function::DropUncompiledImplicitClosureFunction() const {
  if (implicit_closure_function() != Function::null()) {
    const Function& func = Function::Handle(implicit_closure_function());
    if (!func.HasCode()) {
      set_implicit_closure_function(Function::Handle());
    }
  }
}

// Converted closure functions represent a pair of a top-level function and a
// vector of captured variables.  When being invoked, converted closure
// functions get the vector as the first argument, and the arguments supplied at
// the invocation are passed as the remaining arguments to that function.
//
// Consider the following example in Kernel:
//
//   static method foo(core::int start) → core::Function {
//     core::int i = 0;
//     return () → dynamic => start.+(
//       let final dynamic #t1 = i in
//         let final dynamic #t2 = i = #t1.+(1) in
//          #t1
//     );
//   }
//
// The method [foo] above produces a closure as a result.  The closure captures
// two variables: function parameter [start] and local variable [i].  Here is
// how this code would look like after closure conversion:
//
//   static method foo(core::int start) → core::Function {
//     final Vector #context = MakeVector(3);
//     #context[1] = start;
//     #context[2] = 0;
//     return MakeClosure<() → dynamic>(com::closure#foo#function, #context);
//   }
//   static method closure#foo#function(Vector #contextParameter) → dynamic {
//     return (#contextParameter[1]).+(
//       let final dynamic #t1 = #contextParameter[2] in
//         let final dynamic #t2 = #contextParameter[2] = #t1.+(1) in
//           #t1
//     );
//   }
//
// Converted closure functions are used in VM Closure instances that represent
// the results of evaluation of [MakeClosure] primitive operations.
//
// Internally, converted closure functions are represented with the same Closure
// class as implicit closure functions (that are used for dealing with
// tear-offs).  The Closure class instances have two fields, one for the
// function, and one for the captured context.  Implicit closure functions have
// pre-defined shape of the context: it's a single variable that is used as
// 'this'.  Converted closure functions use the context field to store the
// vector of captured variables that will be supplied as the first argument
// during invocation.
//
// The top-level functions used in converted closure functions are generated
// during a front-end transformation in Kernel.  Those functions have some
// common properties:
//   * they expect the captured context to be passed as the first argument,
//   * the first argument should be of [Vector] type (index-based storage),
//   * they retrieve the captured variables from [Vector] explicitly, so they
//   don't need the variables from the context to be put into their current
//   scope.
//
// During closure-conversion pass in Kernel, the contexts are generated
// explicitly and are represented as [Vector]s.  Then they are paired together
// with the top-level functions to form a closure.  When the closure, created
// this way, is invoked, it should receive the [Vector] as the first argument,
// and take the rest of the arguments from the invocation.
//
// Converted closure functions in VM follow same discipline as implicit closure
// functions, because they are similar in many ways. For further details, please
// refer to the following methods:
//   -> Function::ConvertedClosureFunction
//   -> StreamingFlowGraphBuilder::BuildGraphOfConvertedClosureFunction
//   -> StreamingFlowGraphBuilder::BuildGraph (small change that calls
//      BuildGraphOfConvertedClosureFunction)
//   -> StreamingFlowGraphBuilder::BuildClosureCreation (converted closure
//      functions are created here)
//
// Function::ConvertedClosureFunction method follows the logic of
// Function::ImplicitClosureFunction method.
RawFunction* Function::ConvertedClosureFunction() const {
  // Return the existing converted closure function if any.
  if (converted_closure_function() != Function::null()) {
    return converted_closure_function();
  }
  ASSERT(!IsSignatureFunction() && !IsClosureFunction());
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  // Create closure function.
  const String& closure_name = String::Handle(zone, name());
  const Function& closure_function = Function::Handle(
      zone, NewConvertedClosureFunction(closure_name, *this, token_pos()));

  // Currently only static top-level functions are allowed to be converted.
  ASSERT(is_static());
  closure_function.set_context_scope(Object::empty_context_scope());

  // Set closure function's type parameters.
  closure_function.set_type_parameters(
      TypeArguments::Handle(zone, type_parameters()));

  // Set closure function's result type to this result type.
  closure_function.set_result_type(AbstractType::Handle(zone, result_type()));

  // Set closure function's end token to this end token.
  closure_function.set_end_token_pos(end_token_pos());

  // Set closure function's formal parameters to this formal parameters,
  // removing the first parameter over which the currying is done, and adding
  // the closure class instance as the first parameter.  So, the overall number
  // of fixed parameters doesn't change.
  const int num_fixed_params = num_fixed_parameters();
  const int num_opt_params = NumOptionalParameters();
  const bool has_opt_pos_params = HasOptionalPositionalParameters();
  const int num_params = num_fixed_params + num_opt_params;

  closure_function.set_num_fixed_parameters(num_fixed_params);
  closure_function.SetNumOptionalParameters(num_opt_params, has_opt_pos_params);
  closure_function.set_parameter_types(
      Array::Handle(zone, Array::New(num_params, Heap::kOld)));
  closure_function.set_parameter_names(
      Array::Handle(zone, Array::New(num_params, Heap::kOld)));

  AbstractType& param_type = AbstractType::Handle(zone);
  String& param_name = String::Handle(zone);

  // Add implicit closure object as the first parameter.
  param_type = Type::DynamicType();
  closure_function.SetParameterTypeAt(0, param_type);
  closure_function.SetParameterNameAt(0, Symbols::ClosureParameter());

  // All the parameters, but the first one, are the same for the top-level
  // function being converted, and the method of the closure class that is being
  // generated.
  for (int i = 1; i < num_params; i++) {
    param_type = ParameterTypeAt(i);
    closure_function.SetParameterTypeAt(i, param_type);
    param_name = ParameterNameAt(i);
    closure_function.SetParameterNameAt(i, param_name);
  }
  closure_function.set_kernel_offset(kernel_offset());

  const Type& signature_type =
      Type::Handle(zone, closure_function.SignatureType());
  if (!signature_type.IsFinalized()) {
    ClassFinalizer::FinalizeType(Class::Handle(zone, Owner()), signature_type);
  }

  set_converted_closure_function(closure_function);

  return closure_function.raw();
}

void Function::DropUncompiledConvertedClosureFunction() const {
  if (converted_closure_function() != Function::null()) {
    const Function& func = Function::Handle(converted_closure_function());
    if (!func.HasCode()) {
      set_converted_closure_function(Function::Handle());
    }
  }
}

void Function::BuildSignatureParameters(
    Thread* thread,
    Zone* zone,
    NameVisibility name_visibility,
    GrowableHandlePtrArray<const String>* pieces) const {
  AbstractType& param_type = AbstractType::Handle(zone);
  const intptr_t num_params = NumParameters();
  const intptr_t num_fixed_params = num_fixed_parameters();
  const intptr_t num_opt_pos_params = NumOptionalPositionalParameters();
  const intptr_t num_opt_named_params = NumOptionalNamedParameters();
  const intptr_t num_opt_params = num_opt_pos_params + num_opt_named_params;
  ASSERT((num_fixed_params + num_opt_params) == num_params);
  intptr_t i = 0;
  if (name_visibility == kUserVisibleName) {
    // Hide implicit parameters.
    i = NumImplicitParameters();
  }
  String& name = String::Handle(zone);
  while (i < num_fixed_params) {
    param_type = ParameterTypeAt(i);
    ASSERT(!param_type.IsNull());
    name = param_type.BuildName(name_visibility);
    pieces->Add(name);
    if (i != (num_params - 1)) {
      pieces->Add(Symbols::CommaSpace());
    }
    i++;
  }
  if (num_opt_params > 0) {
    if (num_opt_pos_params > 0) {
      pieces->Add(Symbols::LBracket());
    } else {
      pieces->Add(Symbols::LBrace());
    }
    for (intptr_t i = num_fixed_params; i < num_params; i++) {
      param_type = ParameterTypeAt(i);
      ASSERT(!param_type.IsNull());
      name = param_type.BuildName(name_visibility);
      pieces->Add(name);
      // The parameter name of an optional positional parameter does not need
      // to be part of the signature, since it is not used.
      if (num_opt_named_params > 0) {
        name = ParameterNameAt(i);
        pieces->Add(Symbols::Blank());
        pieces->Add(name);
      }
      if (i != (num_params - 1)) {
        pieces->Add(Symbols::CommaSpace());
      }
    }
    if (num_opt_pos_params > 0) {
      pieces->Add(Symbols::RBracket());
    } else {
      pieces->Add(Symbols::RBrace());
    }
  }
}

RawInstance* Function::ImplicitStaticClosure() const {
  ASSERT(IsImplicitStaticClosureFunction());
  if (implicit_static_closure() == Instance::null()) {
    Zone* zone = Thread::Current()->zone();
    const Context& context = Object::empty_context();
    Instance& closure =
        Instance::Handle(zone, Closure::New(Object::null_type_arguments(),
                                            Object::null_type_arguments(),
                                            *this, context, Heap::kOld));
    set_implicit_static_closure(closure);
  }
  return implicit_static_closure();
}

RawInstance* Function::ImplicitInstanceClosure(const Instance& receiver) const {
  ASSERT(IsImplicitClosureFunction());
  Zone* zone = Thread::Current()->zone();
  const Context& context = Context::Handle(zone, Context::New(1));
  context.SetAt(0, receiver);
  TypeArguments& instantiator_type_arguments = TypeArguments::Handle(zone);
  if (!HasInstantiatedSignature(kCurrentClass)) {
    instantiator_type_arguments = receiver.GetTypeArguments();
  }
  ASSERT(HasInstantiatedSignature(kFunctions));  // No generic parent function.
  return Closure::New(instantiator_type_arguments,
                      Object::null_type_arguments(), *this, context);
}

intptr_t Function::ComputeClosureHash() const {
  ASSERT(IsClosureFunction());
  const Class& cls = Class::Handle(Owner());
  intptr_t result = String::Handle(name()).Hash();
  result += String::Handle(Signature()).Hash();
  result += String::Handle(cls.Name()).Hash();
  return result;
}

RawString* Function::BuildSignature(NameVisibility name_visibility) const {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  GrowableHandlePtrArray<const String> pieces(zone, 4);
  String& name = String::Handle(zone);
  if (Isolate::Current()->reify_generic_functions()) {
    const TypeArguments& type_params =
        TypeArguments::Handle(zone, type_parameters());
    if (!type_params.IsNull()) {
      const intptr_t num_type_params = type_params.Length();
      ASSERT(num_type_params > 0);
      TypeParameter& type_param = TypeParameter::Handle(zone);
      AbstractType& bound = AbstractType::Handle(zone);
      pieces.Add(Symbols::LAngleBracket());
      for (intptr_t i = 0; i < num_type_params; i++) {
        type_param ^= type_params.TypeAt(i);
        name = type_param.name();
        pieces.Add(name);
        bound = type_param.bound();
        if (!bound.IsNull() && !bound.IsObjectType()) {
          pieces.Add(Symbols::SpaceExtendsSpace());
          name = bound.BuildName(name_visibility);
          pieces.Add(name);
        }
        if (i < num_type_params - 1) {
          pieces.Add(Symbols::CommaSpace());
        }
      }
      pieces.Add(Symbols::RAngleBracket());
    }
  }
  pieces.Add(Symbols::LParen());
  BuildSignatureParameters(thread, zone, name_visibility, &pieces);
  pieces.Add(Symbols::RParenArrow());
  const AbstractType& res_type = AbstractType::Handle(zone, result_type());
  name = res_type.BuildName(name_visibility);
  pieces.Add(name);
  return Symbols::FromConcatAll(thread, pieces);
}

bool Function::HasInstantiatedSignature(Genericity genericity,
                                        intptr_t num_free_fun_type_params,
                                        TrailPtr trail) const {
  // This function works differently for converted closures.
  //
  // Unlike regular closures, it's not possible to know which type parameters
  // are supposed to come from parent functions or classes and which are
  // actually parameters to the closure it represents. For example, consider:
  //
  //     class C<T> {
  //       getf() => (T x) { return x; }
  //     }
  //
  //     class D {
  //       getf() {
  //         dynamic fn<T>(T x) { return x; }
  //         return fn;
  //       }
  //     }
  //
  // The signature of `fn` as a converted closure will in both cases look like
  // `<T>(T) => dynamic`, because the signature of the converted closure
  // function is the same as its top-level target function. However, in the
  // first case the closure's type is instantiated, and in the second case
  // it's not.
  //
  // Since we can never assume a converted closure is instantiated if it has any
  // type parameters, we always return true in these cases.
  if (IsConvertedClosureFunction()) {
    return genericity == kCurrentClass || NumTypeParameters() == 0;
  }

  if (num_free_fun_type_params == kCurrentAndEnclosingFree) {
    num_free_fun_type_params = kAllFree;
  } else if (genericity != kCurrentClass) {
    // A generic typedef may declare a non-generic function type and get
    // instantiated with unrelated function type parameters. In that case, its
    // signature is still uninstantiated, because these type parameters are
    // free (they are not declared by the typedef).
    // For that reason, we only adjust num_free_fun_type_params if this
    // signature is generic or has a generic parent.
    if (IsGeneric() || HasGenericParent()) {
      // We only consider the function type parameters declared by the parents
      // of this signature function as free.
      const int num_parent_type_params = NumParentTypeParameters();
      if (num_parent_type_params < num_free_fun_type_params) {
        num_free_fun_type_params = num_parent_type_params;
      }
    }
  }
  AbstractType& type = AbstractType::Handle(result_type());
  if (!type.IsInstantiated(genericity, num_free_fun_type_params, trail)) {
    return false;
  }
  const intptr_t num_parameters = NumParameters();
  for (intptr_t i = 0; i < num_parameters; i++) {
    type = ParameterTypeAt(i);
    if (!type.IsInstantiated(genericity, num_free_fun_type_params, trail)) {
      return false;
    }
  }
  return true;
}

RawClass* Function::Owner() const {
  if (raw_ptr()->owner_ == Object::null()) {
    ASSERT(IsSignatureFunction());
    return Class::null();
  }
  if (raw_ptr()->owner_->IsClass()) {
    return Class::RawCast(raw_ptr()->owner_);
  }
  const Object& obj = Object::Handle(raw_ptr()->owner_);
  ASSERT(obj.IsPatchClass());
  return PatchClass::Cast(obj).patched_class();
}

RawClass* Function::origin() const {
  if (raw_ptr()->owner_ == Object::null()) {
    ASSERT(IsSignatureFunction());
    return Class::null();
  }
  if (raw_ptr()->owner_->IsClass()) {
    return Class::RawCast(raw_ptr()->owner_);
  }
  const Object& obj = Object::Handle(raw_ptr()->owner_);
  ASSERT(obj.IsPatchClass());
  return PatchClass::Cast(obj).origin_class();
}

RawScript* Function::script() const {
  // NOTE(turnidge): If you update this function, you probably want to
  // update Class::PatchFieldsAndFunctions() at the same time.
  if (token_pos() == TokenPosition::kMinSource) {
    // Testing for position 0 is an optimization that relies on temporary
    // eval functions having token position 0.
    const Script& script = Script::Handle(eval_script());
    if (!script.IsNull()) {
      return script.raw();
    }
  }
  if (IsClosureFunction() || IsConvertedClosureFunction()) {
    return Function::Handle(parent_function()).script();
  }
  const Object& obj = Object::Handle(raw_ptr()->owner_);
  if (obj.IsNull()) {
    ASSERT(IsSignatureFunction());
    return Script::null();
  }
  if (obj.IsClass()) {
    return Class::Cast(obj).script();
  }
  ASSERT(obj.IsPatchClass());
  return PatchClass::Cast(obj).script();
}

RawTypedData* Function::KernelData() const {
  if (IsClosureFunction()) {
    Function& parent = Function::Handle(parent_function());
    ASSERT(!parent.IsNull());
    return parent.KernelData();
  }

  const Object& obj = Object::Handle(raw_ptr()->owner_);
  if (obj.IsClass()) {
    Library& lib = Library::Handle(Class::Cast(obj).library());
    return lib.kernel_data();
  }
  ASSERT(obj.IsPatchClass());
  return PatchClass::Cast(obj).library_kernel_data();
}

intptr_t Function::KernelDataProgramOffset() const {
  if (IsClosureFunction()) {
    Function& parent = Function::Handle(parent_function());
    ASSERT(!parent.IsNull());
    return parent.KernelDataProgramOffset();
  }

  const Object& obj = Object::Handle(raw_ptr()->owner_);
  if (obj.IsClass()) {
    Library& lib = Library::Handle(Class::Cast(obj).library());
    return lib.kernel_offset();
  }
  ASSERT(obj.IsPatchClass());
  return PatchClass::Cast(obj).library_kernel_offset();
}

bool Function::HasOptimizedCode() const {
  return HasCode() && Code::Handle(CurrentCode()).is_optimized();
}

RawString* Function::UserVisibleName() const {
  if (FLAG_show_internal_names) {
    return name();
  }
  return String::ScrubName(String::Handle(name()));
}

RawString* Function::QualifiedName(NameVisibility name_visibility) const {
  ASSERT(name_visibility != kInternalName);  // We never request it.
  // If |this| is the generated asynchronous body closure, use the
  // name of the parent function.
  Function& fun = Function::Handle(raw());
  if (fun.IsClosureFunction()) {
    // Sniff the parent function.
    fun = fun.parent_function();
    ASSERT(!fun.IsNull());
    if (!fun.IsAsyncGenerator() && !fun.IsAsyncFunction() &&
        !fun.IsSyncGenerator()) {
      // Parent function is not the generator of an asynchronous body closure,
      // start at |this|.
      fun = raw();
    }
  }
  // A function's scrubbed name and its user visible name are identical.
  String& result = String::Handle(fun.UserVisibleName());
  if (IsClosureFunction()) {
    while (fun.IsLocalFunction() && !fun.IsImplicitClosureFunction()) {
      fun = fun.parent_function();
      if (fun.IsAsyncClosure() || fun.IsSyncGenClosure() ||
          fun.IsAsyncGenClosure()) {
        // Skip the closure and use the real function name found in
        // the parent.
        fun = fun.parent_function();
      }
      result = String::Concat(Symbols::Dot(), result, Heap::kOld);
      result = String::Concat(String::Handle(fun.UserVisibleName()), result,
                              Heap::kOld);
    }
  }
  const Class& cls = Class::Handle(Owner());
  if (!cls.IsTopLevel()) {
    if (fun.kind() == RawFunction::kConstructor) {
      result = String::Concat(Symbols::ConstructorStacktracePrefix(), result,
                              Heap::kOld);
    } else {
      result = String::Concat(Symbols::Dot(), result, Heap::kOld);
      const String& cls_name = String::Handle(name_visibility == kScrubbedName
                                                  ? cls.ScrubbedName()
                                                  : cls.UserVisibleName());
      result = String::Concat(cls_name, result, Heap::kOld);
    }
  }
  return result.raw();
}

RawString* Function::GetSource() const {
  if (IsImplicitConstructor() || IsSignatureFunction()) {
    // We may need to handle more cases when the restrictions on mixins are
    // relaxed. In particular we might start associating some source with the
    // forwarding constructors when it becomes possible to specify a particular
    // constructor from the mixin to use.
    return String::null();
  }
  Zone* zone = Thread::Current()->zone();
  const Script& func_script = Script::Handle(zone, script());
  const TokenStream& stream = TokenStream::Handle(zone, func_script.tokens());
  if (!func_script.HasSource()) {
    // When source is not available, avoid printing the whole token stream and
    // doing expensive position calculations.
    return stream.GenerateSource(token_pos(), end_token_pos().Next());
  }

  const TokenStream::Iterator tkit(zone, stream, end_token_pos());
  intptr_t from_line;
  intptr_t from_col;
  intptr_t to_line;
  intptr_t to_col;
  func_script.GetTokenLocation(token_pos(), &from_line, &from_col);
  func_script.GetTokenLocation(end_token_pos(), &to_line, &to_col);
  intptr_t last_tok_len = String::Handle(tkit.CurrentLiteral()).Length();
  // Handle special cases for end tokens of closures (where we exclude the last
  // token):
  // (1) "foo(() => null, bar);": End token is `,', but we don't print it.
  // (2) "foo(() => null);": End token is ')`, but we don't print it.
  // (3) "var foo = () => null;": End token is `;', but in this case the token
  // semicolon belongs to the assignment so we skip it.
  if ((tkit.CurrentTokenKind() == Token::kCOMMA) ||   // Case 1.
      (tkit.CurrentTokenKind() == Token::kRPAREN) ||  // Case 2.
      (tkit.CurrentTokenKind() == Token::kSEMICOLON &&
       String::Handle(zone, name()).Equals("<anonymous closure>"))) {  // Cas 3.
    last_tok_len = 0;
  }
  const String& result =
      String::Handle(zone, func_script.GetSnippet(from_line, from_col, to_line,
                                                  to_col + last_tok_len));
  ASSERT(!result.IsNull());
  return result.raw();
}

// Construct fingerprint from token stream. The token stream contains also
// arguments.
int32_t Function::SourceFingerprint() const {
  return Script::Handle(script()).SourceFingerprint(token_pos(),
                                                    end_token_pos());
}

void Function::SaveICDataMap(
    const ZoneGrowableArray<const ICData*>& deopt_id_to_ic_data,
    const Array& edge_counters_array) const {
  // Compute number of ICData objects to save.
  // Store edge counter array in the first slot.
  intptr_t count = 1;
  for (intptr_t i = 0; i < deopt_id_to_ic_data.length(); i++) {
    if (deopt_id_to_ic_data[i] != NULL) {
      count++;
    }
  }
  const Array& array = Array::Handle(Array::New(count, Heap::kOld));
  INC_STAT(Thread::Current(), total_code_size, count * sizeof(uword));
  count = 1;
  for (intptr_t i = 0; i < deopt_id_to_ic_data.length(); i++) {
    if (deopt_id_to_ic_data[i] != NULL) {
      array.SetAt(count++, *deopt_id_to_ic_data[i]);
    }
  }
  array.SetAt(0, edge_counters_array);
  set_ic_data_array(array);
}

void Function::RestoreICDataMap(
    ZoneGrowableArray<const ICData*>* deopt_id_to_ic_data,
    bool clone_ic_data) const {
  if (FLAG_force_clone_compiler_objects) {
    clone_ic_data = true;
  }
  ASSERT(deopt_id_to_ic_data->is_empty());
  Zone* zone = Thread::Current()->zone();
  const Array& saved_ic_data = Array::Handle(zone, ic_data_array());
  if (saved_ic_data.IsNull()) {
    // Could happen with deferred loading.
    return;
  }
  const intptr_t saved_length = saved_ic_data.Length();
  ASSERT(saved_length > 0);
  if (saved_length > 1) {
    const intptr_t restored_length =
        ICData::Cast(Object::Handle(zone, saved_ic_data.At(saved_length - 1)))
            .deopt_id() +
        1;
    deopt_id_to_ic_data->SetLength(restored_length);
    for (intptr_t i = 0; i < restored_length; i++) {
      (*deopt_id_to_ic_data)[i] = NULL;
    }
    for (intptr_t i = 1; i < saved_length; i++) {
      ICData& ic_data = ICData::ZoneHandle(zone);
      ic_data ^= saved_ic_data.At(i);
      if (clone_ic_data) {
        const ICData& original_ic_data = ICData::Handle(zone, ic_data.raw());
        ic_data = ICData::Clone(ic_data);
        ic_data.SetOriginal(original_ic_data);
      }
      (*deopt_id_to_ic_data)[ic_data.deopt_id()] = &ic_data;
    }
  }
}

void Function::set_ic_data_array(const Array& value) const {
  StorePointer(&raw_ptr()->ic_data_array_, value.raw());
}

RawArray* Function::ic_data_array() const {
  return raw_ptr()->ic_data_array_;
}

void Function::ClearICDataArray() const {
  set_ic_data_array(Array::null_array());
}

void Function::SetDeoptReasonForAll(intptr_t deopt_id,
                                    ICData::DeoptReasonId reason) {
  const Array& array = Array::Handle(ic_data_array());
  ICData& ic_data = ICData::Handle();
  for (intptr_t i = 1; i < array.Length(); i++) {
    ic_data ^= array.At(i);
    if (ic_data.deopt_id() == deopt_id) {
      ic_data.AddDeoptReason(reason);
    }
  }
}

bool Function::CheckSourceFingerprint(const char* prefix, int32_t fp) const {
  if (!Isolate::Current()->obfuscate() && (kernel_offset() <= 0) &&
      (SourceFingerprint() != fp)) {
    const bool recalculatingFingerprints = false;
    if (recalculatingFingerprints) {
      // This output can be copied into a file, then used with sed
      // to replace the old values.
      // sed -i.bak -f /tmp/newkeys runtime/vm/compiler/method_recognizer.h
      THR_Print("s/0x%08x/0x%08x/\n", fp, SourceFingerprint());
    } else {
      THR_Print(
          "FP mismatch while recognizing method %s:"
          " expecting 0x%08x found 0x%08x\n",
          ToFullyQualifiedCString(), fp, SourceFingerprint());
      return false;
    }
  }
  return true;
}

RawCode* Function::EnsureHasCode() const {
  if (HasCode()) return CurrentCode();
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  const Object& result =
      Object::Handle(zone, Compiler::CompileFunction(thread, *this));
  if (result.IsError()) {
    Exceptions::PropagateError(Error::Cast(result));
    UNREACHABLE();
  }
  // Compiling in unoptimized mode should never fail if there are no errors.
  ASSERT(HasCode());
  ASSERT(unoptimized_code() == result.raw());
  return CurrentCode();
}

const char* Function::ToCString() const {
  if (IsNull()) {
    return "Function: null";
  }
  const char* static_str = is_static() ? " static" : "";
  const char* abstract_str = is_abstract() ? " abstract" : "";
  const char* kind_str = NULL;
  const char* const_str = is_const() ? " const" : "";
  switch (kind()) {
    case RawFunction::kRegularFunction:
    case RawFunction::kClosureFunction:
    case RawFunction::kImplicitClosureFunction:
    case RawFunction::kConvertedClosureFunction:
    case RawFunction::kGetterFunction:
    case RawFunction::kSetterFunction:
      kind_str = "";
      break;
    case RawFunction::kSignatureFunction:
      kind_str = " signature";
      break;
    case RawFunction::kConstructor:
      kind_str = is_static() ? " factory" : " constructor";
      break;
    case RawFunction::kImplicitGetter:
      kind_str = " getter";
      break;
    case RawFunction::kImplicitSetter:
      kind_str = " setter";
      break;
    case RawFunction::kImplicitStaticFinalGetter:
      kind_str = " static-final-getter";
      break;
    case RawFunction::kMethodExtractor:
      kind_str = " method-extractor";
      break;
    case RawFunction::kNoSuchMethodDispatcher:
      kind_str = " no-such-method-dispatcher";
      break;
    case RawFunction::kInvokeFieldDispatcher:
      kind_str = "invoke-field-dispatcher";
      break;
    case RawFunction::kIrregexpFunction:
      kind_str = "irregexp-function";
      break;
    default:
      UNREACHABLE();
  }
  const char* function_name = String::Handle(name()).ToCString();
  return OS::SCreate(Thread::Current()->zone(), "Function '%s':%s%s%s%s.",
                     function_name, static_str, abstract_str, kind_str,
                     const_str);
}

void ClosureData::set_context_scope(const ContextScope& value) const {
  StorePointer(&raw_ptr()->context_scope_, value.raw());
}

void ClosureData::set_implicit_static_closure(const Instance& closure) const {
  ASSERT(!closure.IsNull());
  ASSERT(raw_ptr()->closure_ == Instance::null());
  StorePointer(&raw_ptr()->closure_, closure.raw());
}

void ClosureData::set_parent_function(const Function& value) const {
  StorePointer(&raw_ptr()->parent_function_, value.raw());
}

void ClosureData::set_signature_type(const Type& value) const {
  StorePointer(&raw_ptr()->signature_type_, value.raw());
}

RawClosureData* ClosureData::New() {
  ASSERT(Object::closure_data_class() != Class::null());
  RawObject* raw = Object::Allocate(ClosureData::kClassId,
                                    ClosureData::InstanceSize(), Heap::kOld);
  return reinterpret_cast<RawClosureData*>(raw);
}

const char* ClosureData::ToCString() const {
  if (IsNull()) {
    return "ClosureData: null";
  }
  const Function& parent = Function::Handle(parent_function());
  const Type& type = Type::Handle(signature_type());
  return OS::SCreate(Thread::Current()->zone(),
                     "ClosureData: context_scope: 0x%" Px
                     " parent_function: %s signature_type: %s"
                     " implicit_static_closure: 0x%" Px,
                     reinterpret_cast<uword>(context_scope()),
                     parent.IsNull() ? "null" : parent.ToCString(),
                     type.IsNull() ? "null" : type.ToCString(),
                     reinterpret_cast<uword>(implicit_static_closure()));
}

void SignatureData::set_parent_function(const Function& value) const {
  StorePointer(&raw_ptr()->parent_function_, value.raw());
}

void SignatureData::set_signature_type(const Type& value) const {
  StorePointer(&raw_ptr()->signature_type_, value.raw());
}

RawSignatureData* SignatureData::New(Heap::Space space) {
  ASSERT(Object::signature_data_class() != Class::null());
  RawObject* raw = Object::Allocate(SignatureData::kClassId,
                                    SignatureData::InstanceSize(), space);
  return reinterpret_cast<RawSignatureData*>(raw);
}

const char* SignatureData::ToCString() const {
  if (IsNull()) {
    return "SignatureData: null";
  }
  const Function& parent = Function::Handle(parent_function());
  const Type& type = Type::Handle(signature_type());
  return OS::SCreate(Thread::Current()->zone(),
                     "SignatureData parent_function: %s signature_type: %s",
                     parent.IsNull() ? "null" : parent.ToCString(),
                     type.IsNull() ? "null" : type.ToCString());
}

void RedirectionData::set_type(const Type& value) const {
  ASSERT(!value.IsNull());
  StorePointer(&raw_ptr()->type_, value.raw());
}

void RedirectionData::set_identifier(const String& value) const {
  StorePointer(&raw_ptr()->identifier_, value.raw());
}

void RedirectionData::set_target(const Function& value) const {
  StorePointer(&raw_ptr()->target_, value.raw());
}

RawRedirectionData* RedirectionData::New() {
  ASSERT(Object::redirection_data_class() != Class::null());
  RawObject* raw = Object::Allocate(
      RedirectionData::kClassId, RedirectionData::InstanceSize(), Heap::kOld);
  return reinterpret_cast<RawRedirectionData*>(raw);
}

const char* RedirectionData::ToCString() const {
  if (IsNull()) {
    return "RedirectionData: null";
  }
  const Type& redir_type = Type::Handle(type());
  const String& ident = String::Handle(identifier());
  const Function& target_fun = Function::Handle(target());
  return OS::SCreate(Thread::Current()->zone(),
                     "RedirectionData: type: %s identifier: %s target: %s",
                     redir_type.IsNull() ? "null" : redir_type.ToCString(),
                     ident.IsNull() ? "null" : ident.ToCString(),
                     target_fun.IsNull() ? "null" : target_fun.ToCString());
}

RawField* Field::CloneFromOriginal() const {
  return this->Clone(*this);
}

RawField* Field::Original() const {
  if (IsNull()) {
    return Field::null();
  }
  Object& obj = Object::Handle(raw_ptr()->owner_);
  if (obj.IsField()) {
    return Field::RawCast(obj.raw());
  } else {
    return this->raw();
  }
}

void Field::SetOriginal(const Field& value) const {
  ASSERT(value.IsOriginal());
  ASSERT(!value.IsNull());
  StorePointer(&raw_ptr()->owner_, reinterpret_cast<RawObject*>(value.raw()));
}

RawString* Field::GetterName(const String& field_name) {
  return String::Concat(Symbols::GetterPrefix(), field_name);
}

RawString* Field::GetterSymbol(const String& field_name) {
  return Symbols::FromGet(Thread::Current(), field_name);
}

RawString* Field::LookupGetterSymbol(const String& field_name) {
  return Symbols::LookupFromGet(Thread::Current(), field_name);
}

RawString* Field::SetterName(const String& field_name) {
  return String::Concat(Symbols::SetterPrefix(), field_name);
}

RawString* Field::SetterSymbol(const String& field_name) {
  return Symbols::FromSet(Thread::Current(), field_name);
}

RawString* Field::LookupSetterSymbol(const String& field_name) {
  return Symbols::LookupFromSet(Thread::Current(), field_name);
}

RawString* Field::NameFromGetter(const String& getter_name) {
  return Symbols::New(Thread::Current(), getter_name, kGetterPrefixLength,
                      getter_name.Length() - kGetterPrefixLength);
}

RawString* Field::NameFromSetter(const String& setter_name) {
  return Symbols::New(Thread::Current(), setter_name, kSetterPrefixLength,
                      setter_name.Length() - kSetterPrefixLength);
}

bool Field::IsGetterName(const String& function_name) {
  return function_name.StartsWith(Symbols::GetterPrefix());
}

bool Field::IsSetterName(const String& function_name) {
  return function_name.StartsWith(Symbols::SetterPrefix());
}

void Field::set_name(const String& value) const {
  ASSERT(value.IsSymbol());
  ASSERT(IsOriginal());
  StorePointer(&raw_ptr()->name_, value.raw());
}

RawObject* Field::RawOwner() const {
  if (IsOriginal()) {
    return raw_ptr()->owner_;
  } else {
    const Field& field = Field::Handle(Original());
    ASSERT(field.IsOriginal());
    ASSERT(!Object::Handle(field.raw_ptr()->owner_).IsField());
    return field.raw_ptr()->owner_;
  }
}

RawClass* Field::Owner() const {
  const Field& field = Field::Handle(Original());
  ASSERT(field.IsOriginal());
  const Object& obj = Object::Handle(field.raw_ptr()->owner_);
  if (obj.IsClass()) {
    return Class::Cast(obj).raw();
  }
  ASSERT(obj.IsPatchClass());
  return PatchClass::Cast(obj).patched_class();
}

RawClass* Field::Origin() const {
  const Field& field = Field::Handle(Original());
  ASSERT(field.IsOriginal());
  const Object& obj = Object::Handle(field.raw_ptr()->owner_);
  if (obj.IsClass()) {
    return Class::Cast(obj).raw();
  }
  ASSERT(obj.IsPatchClass());
  return PatchClass::Cast(obj).origin_class();
}

RawScript* Field::Script() const {
  // NOTE(turnidge): If you update this function, you probably want to
  // update Class::PatchFieldsAndFunctions() at the same time.
  const Field& field = Field::Handle(Original());
  ASSERT(field.IsOriginal());
  const Object& obj = Object::Handle(field.raw_ptr()->owner_);
  if (obj.IsClass()) {
    return Class::Cast(obj).script();
  }
  ASSERT(obj.IsPatchClass());
  return PatchClass::Cast(obj).script();
}

RawTypedData* Field::KernelData() const {
  const Object& obj = Object::Handle(this->raw_ptr()->owner_);
  if (obj.IsClass()) {
    Library& library = Library::Handle(Class::Cast(obj).library());
    return library.kernel_data();
  }
  ASSERT(obj.IsPatchClass());
  return PatchClass::Cast(obj).library_kernel_data();
}

intptr_t Field::KernelDataProgramOffset() const {
  const Object& obj = Object::Handle(raw_ptr()->owner_);
  if (obj.IsClass()) {
    Library& lib = Library::Handle(Class::Cast(obj).library());
    return lib.kernel_offset();
  }
  ASSERT(obj.IsPatchClass());
  return PatchClass::Cast(obj).library_kernel_offset();
}

// Called at finalization time
void Field::SetFieldType(const AbstractType& value) const {
  ASSERT(Thread::Current()->IsMutatorThread());
  ASSERT(IsOriginal());
  ASSERT(!value.IsNull());
  if (value.raw() != type()) {
    StorePointer(&raw_ptr()->type_, value.raw());
  }
}

RawField* Field::New() {
  ASSERT(Object::field_class() != Class::null());
  RawObject* raw =
      Object::Allocate(Field::kClassId, Field::InstanceSize(), Heap::kOld);
  return reinterpret_cast<RawField*>(raw);
}

void Field::InitializeNew(const Field& result,
                          const String& name,
                          bool is_static,
                          bool is_final,
                          bool is_const,
                          bool is_reflectable,
                          const Object& owner,
                          TokenPosition token_pos,
                          TokenPosition end_token_pos) {
  result.set_name(name);
  result.set_is_static(is_static);
  if (!is_static) {
    result.SetOffset(0);
  }
  result.set_is_final(is_final);
  result.set_is_const(is_const);
  result.set_is_reflectable(is_reflectable);
  result.set_is_double_initialized(false);
  result.set_owner(owner);
  result.set_token_pos(token_pos);
  result.set_end_token_pos(end_token_pos);
  result.set_has_initializer(false);
  result.set_is_unboxing_candidate(true);
  result.set_initializer_changed_after_initialization(false);
  result.set_kernel_offset(0);
  Isolate* isolate = Isolate::Current();

  // Use field guards if they are enabled and the isolate has never reloaded.
  // TODO(johnmccutchan): The reload case assumes the worst case (everything is
  // dynamic and possibly null). Attempt to relax this later.
#if defined(PRODUCT)
  const bool use_guarded_cid =
      FLAG_precompiled_mode || isolate->use_field_guards();
#else
  const bool use_guarded_cid =
      FLAG_precompiled_mode ||
      (isolate->use_field_guards() && !isolate->HasAttemptedReload());
#endif  // !defined(PRODUCT)
  result.set_guarded_cid(use_guarded_cid ? kIllegalCid : kDynamicCid);
  result.set_is_nullable(use_guarded_cid ? false : true);
  result.set_guarded_list_length_in_object_offset(Field::kUnknownLengthOffset);
  // Presently, we only attempt to remember the list length for final fields.
  if (is_final && use_guarded_cid) {
    result.set_guarded_list_length(Field::kUnknownFixedLength);
  } else {
    result.set_guarded_list_length(Field::kNoFixedLength);
  }
}

RawField* Field::New(const String& name,
                     bool is_static,
                     bool is_final,
                     bool is_const,
                     bool is_reflectable,
                     const Object& owner,
                     const AbstractType& type,
                     TokenPosition token_pos,
                     TokenPosition end_token_pos) {
  ASSERT(!owner.IsNull());
  const Field& result = Field::Handle(Field::New());
  InitializeNew(result, name, is_static, is_final, is_const, is_reflectable,
                owner, token_pos, end_token_pos);
  result.SetFieldType(type);
  return result.raw();
}

RawField* Field::NewTopLevel(const String& name,
                             bool is_final,
                             bool is_const,
                             const Object& owner,
                             TokenPosition token_pos,
                             TokenPosition end_token_pos) {
  ASSERT(!owner.IsNull());
  const Field& result = Field::Handle(Field::New());
  InitializeNew(result, name, true,       /* is_static */
                is_final, is_const, true, /* is_reflectable */
                owner, token_pos, end_token_pos);
  return result.raw();
}

RawField* Field::Clone(const Class& new_owner) const {
  Field& clone = Field::Handle();
  clone ^= Object::Clone(*this, Heap::kOld);
  const Class& owner = Class::Handle(this->Owner());
  const PatchClass& clone_owner =
      PatchClass::Handle(PatchClass::New(new_owner, owner));
  clone.set_owner(clone_owner);
  if (!clone.is_static()) {
    clone.SetOffset(0);
  }
  if (new_owner.NumTypeParameters() > 0) {
    // Adjust the field type to refer to type parameters of the new owner.
    AbstractType& type = AbstractType::Handle(clone.type());
    type ^= type.CloneUninstantiated(new_owner);
    clone.SetFieldType(type);
  }
  return clone.raw();
}

RawField* Field::Clone(const Field& original) const {
  if (original.IsNull()) {
    return Field::null();
  }
  ASSERT(original.IsOriginal());
  Field& clone = Field::Handle();
  clone ^= Object::Clone(*this, Heap::kOld);
  clone.SetOriginal(original);
  clone.set_kernel_offset(original.kernel_offset());
  return clone.raw();
}

int32_t Field::SourceFingerprint() const {
  return Script::Handle(Script()).SourceFingerprint(token_pos(),
                                                    end_token_pos());
}

RawString* Field::InitializingExpression() const {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  const class Script& scr = Script::Handle(zone, Script());
  ASSERT(!scr.IsNull());
  const TokenStream& tkns = TokenStream::Handle(zone, scr.tokens());
  if (tkns.IsNull()) {
    ASSERT(Dart::vm_snapshot_kind() == Snapshot::kFullAOT);
    return String::null();
  }
  TokenStream::Iterator tkit(zone, tkns, token_pos());
  ASSERT(Token::IsIdentifier(tkit.CurrentTokenKind()));
#if defined(DEBUG)
  const String& literal = String::Handle(zone, tkit.CurrentLiteral());
  ASSERT(literal.raw() == name());
#endif
  tkit.Advance();
  if (tkit.CurrentTokenKind() != Token::kASSIGN) {
    return String::null();
  }
  tkit.Advance();
  const TokenPosition start_of_expression = tkit.CurrentPosition();
  while (tkit.CurrentTokenKind() != Token::kSEMICOLON) {
    tkit.Advance();
  }
  const TokenPosition end_of_expression = tkit.CurrentPosition();
  return scr.GetSnippet(start_of_expression, end_of_expression);
}

RawString* Field::UserVisibleName() const {
  if (FLAG_show_internal_names) {
    return name();
  }
  return String::ScrubName(String::Handle(name()));
}

intptr_t Field::guarded_list_length() const {
  return Smi::Value(raw_ptr()->guarded_list_length_);
}

void Field::set_guarded_list_length(intptr_t list_length) const {
  ASSERT(Thread::Current()->IsMutatorThread());
  ASSERT(IsOriginal());
  StoreSmi(&raw_ptr()->guarded_list_length_, Smi::New(list_length));
}

intptr_t Field::guarded_list_length_in_object_offset() const {
  return raw_ptr()->guarded_list_length_in_object_offset_ + kHeapObjectTag;
}

void Field::set_guarded_list_length_in_object_offset(
    intptr_t list_length_offset) const {
  ASSERT(Thread::Current()->IsMutatorThread());
  ASSERT(IsOriginal());
  StoreNonPointer(&raw_ptr()->guarded_list_length_in_object_offset_,
                  static_cast<int8_t>(list_length_offset - kHeapObjectTag));
  ASSERT(guarded_list_length_in_object_offset() == list_length_offset);
}

const char* Field::ToCString() const {
  if (IsNull()) {
    return "Field: null";
  }
  const char* kF0 = is_static() ? " static" : "";
  const char* kF1 = is_final() ? " final" : "";
  const char* kF2 = is_const() ? " const" : "";
  const char* field_name = String::Handle(name()).ToCString();
  const Class& cls = Class::Handle(Owner());
  const char* cls_name = String::Handle(cls.Name()).ToCString();
  return OS::SCreate(Thread::Current()->zone(), "Field <%s.%s>:%s%s%s",
                     cls_name, field_name, kF0, kF1, kF2);
}

// Build a closure object that gets (or sets) the contents of a static
// field f and cache the closure in a newly created static field
// named #f (or #f= in case of a setter).
RawInstance* Field::AccessorClosure(bool make_setter) const {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  ASSERT(is_static());
  const Class& field_owner = Class::Handle(zone, Owner());

  String& closure_name = String::Handle(zone, this->name());
  closure_name = Symbols::FromConcat(thread, Symbols::HashMark(), closure_name);
  if (make_setter) {
    closure_name =
        Symbols::FromConcat(thread, Symbols::HashMark(), closure_name);
  }

  Field& closure_field = Field::Handle(zone);
  closure_field = field_owner.LookupStaticField(closure_name);
  if (!closure_field.IsNull()) {
    ASSERT(closure_field.is_static());
    const Instance& closure =
        Instance::Handle(zone, closure_field.StaticValue());
    ASSERT(!closure.IsNull());
    ASSERT(closure.IsClosure());
    return closure.raw();
  }

  // This is the first time a closure for this field is requested.
  // Create the closure and a new static field in which it is stored.
  const char* field_name = String::Handle(zone, name()).ToCString();
  String& expr_src = String::Handle(zone);
  if (make_setter) {
    expr_src = String::NewFormatted("(%s_) { return %s = %s_; }", field_name,
                                    field_name, field_name);
  } else {
    expr_src = String::NewFormatted("() { return %s; }", field_name);
  }
  Object& result =
      Object::Handle(zone, field_owner.Evaluate(expr_src, Object::empty_array(),
                                                Object::empty_array()));
  ASSERT(result.IsInstance());
  // The caller may expect the closure to be allocated in old space. Copy
  // the result here, since Object::Clone() is a private method.
  result = Object::Clone(result, Heap::kOld);

  closure_field = Field::New(closure_name,
                             true,   // is_static
                             true,   // is_final
                             true,   // is_const
                             false,  // is_reflectable
                             field_owner, Object::dynamic_type(),
                             this->token_pos(), this->end_token_pos());
  closure_field.SetStaticValue(Instance::Cast(result), true);
  field_owner.AddField(closure_field);

  return Instance::RawCast(result.raw());
}

RawInstance* Field::GetterClosure() const {
  return AccessorClosure(false);
}

RawInstance* Field::SetterClosure() const {
  return AccessorClosure(true);
}

RawArray* Field::dependent_code() const {
  return raw_ptr()->dependent_code_;
}

void Field::set_dependent_code(const Array& array) const {
  ASSERT(IsOriginal());
  StorePointer(&raw_ptr()->dependent_code_, array.raw());
}

class FieldDependentArray : public WeakCodeReferences {
 public:
  explicit FieldDependentArray(const Field& field)
      : WeakCodeReferences(Array::Handle(field.dependent_code())),
        field_(field) {}

  virtual void UpdateArrayTo(const Array& value) {
    field_.set_dependent_code(value);
  }

  virtual void ReportDeoptimization(const Code& code) {
    if (FLAG_trace_deoptimization || FLAG_trace_deoptimization_verbose) {
      Function& function = Function::Handle(code.function());
      THR_Print("Deoptimizing %s because guard on field %s failed.\n",
                function.ToFullyQualifiedCString(), field_.ToCString());
    }
  }

  virtual void ReportSwitchingCode(const Code& code) {
    if (FLAG_trace_deoptimization || FLAG_trace_deoptimization_verbose) {
      Function& function = Function::Handle(code.function());
      THR_Print(
          "Switching '%s' to unoptimized code because guard"
          " on field '%s' was violated.\n",
          function.ToFullyQualifiedCString(), field_.ToCString());
    }
  }

 private:
  const Field& field_;
  DISALLOW_COPY_AND_ASSIGN(FieldDependentArray);
};

void Field::RegisterDependentCode(const Code& code) const {
  ASSERT(IsOriginal());
  DEBUG_ASSERT(IsMutatorOrAtSafepoint());
  ASSERT(code.is_optimized());
  FieldDependentArray a(*this);
  a.Register(code);
}

void Field::DeoptimizeDependentCode() const {
  ASSERT(Thread::Current()->IsMutatorThread());
  ASSERT(IsOriginal());
  FieldDependentArray a(*this);
  a.DisableCode();
}

bool Field::IsConsistentWith(const Field& other) const {
  return (raw_ptr()->guarded_cid_ == other.raw_ptr()->guarded_cid_) &&
         (raw_ptr()->is_nullable_ == other.raw_ptr()->is_nullable_) &&
         (raw_ptr()->guarded_list_length_ ==
          other.raw_ptr()->guarded_list_length_) &&
         (is_unboxing_candidate() == other.is_unboxing_candidate());
}

bool Field::IsUninitialized() const {
  const Instance& value = Instance::Handle(raw_ptr()->value_.static_value_);
  ASSERT(value.raw() != Object::transition_sentinel().raw());
  return value.raw() == Object::sentinel().raw();
}

void Field::SetPrecompiledInitializer(const Function& initializer) const {
  ASSERT(IsOriginal());
  StorePointer(&raw_ptr()->initializer_.precompiled_, initializer.raw());
}

bool Field::HasPrecompiledInitializer() const {
  return raw_ptr()->initializer_.precompiled_->IsHeapObject() &&
         raw_ptr()->initializer_.precompiled_->IsFunction();
}

void Field::SetSavedInitialStaticValue(const Instance& value) const {
  ASSERT(IsOriginal());
  ASSERT(!HasPrecompiledInitializer());
  StorePointer(&raw_ptr()->initializer_.saved_value_, value.raw());
}

void Field::EvaluateInitializer() const {
  ASSERT(IsOriginal());
  ASSERT(is_static());
  if (StaticValue() == Object::sentinel().raw()) {
    SetStaticValue(Object::transition_sentinel());
    const Object& value =
        Object::Handle(Compiler::EvaluateStaticInitializer(*this));
    if (value.IsError()) {
      SetStaticValue(Object::null_instance());
      Exceptions::PropagateError(Error::Cast(value));
      UNREACHABLE();
    }
    ASSERT(value.IsNull() || value.IsInstance());
    SetStaticValue(value.IsNull() ? Instance::null_instance()
                                  : Instance::Cast(value));
    return;
  } else if (StaticValue() == Object::transition_sentinel().raw()) {
    const Array& ctor_args = Array::Handle(Array::New(1));
    const String& field_name = String::Handle(name());
    ctor_args.SetAt(0, field_name);
    Exceptions::ThrowByType(Exceptions::kCyclicInitializationError, ctor_args);
    UNREACHABLE();
    return;
  }
  UNREACHABLE();
}

static intptr_t GetListLength(const Object& value) {
  if (value.IsTypedData()) {
    const TypedData& list = TypedData::Cast(value);
    return list.Length();
  } else if (value.IsArray()) {
    const Array& list = Array::Cast(value);
    return list.Length();
  } else if (value.IsGrowableObjectArray()) {
    // List length is variable.
    return Field::kNoFixedLength;
  } else if (value.IsExternalTypedData()) {
    // TODO(johnmccutchan): Enable for external typed data.
    return Field::kNoFixedLength;
  } else if (RawObject::IsTypedDataViewClassId(value.GetClassId())) {
    // TODO(johnmccutchan): Enable for typed data views.
    return Field::kNoFixedLength;
  }
  return Field::kNoFixedLength;
}

static intptr_t GetListLengthOffset(intptr_t cid) {
  if (RawObject::IsTypedDataClassId(cid)) {
    return TypedData::length_offset();
  } else if (cid == kArrayCid || cid == kImmutableArrayCid) {
    return Array::length_offset();
  } else if (cid == kGrowableObjectArrayCid) {
    // List length is variable.
    return Field::kUnknownLengthOffset;
  } else if (RawObject::IsExternalTypedDataClassId(cid)) {
    // TODO(johnmccutchan): Enable for external typed data.
    return Field::kUnknownLengthOffset;
  } else if (RawObject::IsTypedDataViewClassId(cid)) {
    // TODO(johnmccutchan): Enable for typed data views.
    return Field::kUnknownLengthOffset;
  }
  return Field::kUnknownLengthOffset;
}

const char* Field::GuardedPropertiesAsCString() const {
  if (guarded_cid() == kIllegalCid) {
    return "<?>";
  } else if (guarded_cid() == kDynamicCid) {
    return "<*>";
  }

  const Class& cls =
      Class::Handle(Isolate::Current()->class_table()->At(guarded_cid()));
  const char* class_name = String::Handle(cls.Name()).ToCString();

  if (RawObject::IsBuiltinListClassId(guarded_cid()) && !is_nullable() &&
      is_final()) {
    ASSERT(guarded_list_length() != kUnknownFixedLength);
    if (guarded_list_length() == kNoFixedLength) {
      return Thread::Current()->zone()->PrintToString("<%s [*]>", class_name);
    } else {
      return Thread::Current()->zone()->PrintToString(
          "<%s [%" Pd " @%" Pd "]>", class_name, guarded_list_length(),
          guarded_list_length_in_object_offset());
    }
  }

  return Thread::Current()->zone()->PrintToString(
      "<%s %s>", is_nullable() ? "nullable" : "not-nullable", class_name);
}

void Field::InitializeGuardedListLengthInObjectOffset() const {
  ASSERT(IsOriginal());
  if (needs_length_check() &&
      (guarded_list_length() != Field::kUnknownFixedLength)) {
    const intptr_t offset = GetListLengthOffset(guarded_cid());
    set_guarded_list_length_in_object_offset(offset);
    ASSERT(offset != Field::kUnknownLengthOffset);
  } else {
    set_guarded_list_length_in_object_offset(Field::kUnknownLengthOffset);
  }
}

bool Field::UpdateGuardedCidAndLength(const Object& value) const {
  ASSERT(IsOriginal());
  const intptr_t cid = value.GetClassId();

  if (guarded_cid() == kIllegalCid) {
    // Field is assigned first time.
    set_guarded_cid(cid);
    set_is_nullable(cid == kNullCid);

    // Start tracking length if needed.
    ASSERT((guarded_list_length() == Field::kUnknownFixedLength) ||
           (guarded_list_length() == Field::kNoFixedLength));
    if (needs_length_check()) {
      ASSERT(guarded_list_length() == Field::kUnknownFixedLength);
      set_guarded_list_length(GetListLength(value));
      InitializeGuardedListLengthInObjectOffset();
    }

    if (FLAG_trace_field_guards) {
      THR_Print("    => %s\n", GuardedPropertiesAsCString());
    }

    return false;
  }

  if ((cid == guarded_cid()) || ((cid == kNullCid) && is_nullable())) {
    // Class id of the assigned value matches expected class id and nullability.

    // If we are tracking length check if it has matches.
    if (needs_length_check() &&
        (guarded_list_length() != GetListLength(value))) {
      ASSERT(guarded_list_length() != Field::kUnknownFixedLength);
      set_guarded_list_length(Field::kNoFixedLength);
      set_guarded_list_length_in_object_offset(Field::kUnknownLengthOffset);
      return true;
    }

    // Everything matches.
    return false;
  }

  if ((cid == kNullCid) && !is_nullable()) {
    // Assigning null value to a non-nullable field makes it nullable.
    set_is_nullable(true);
  } else if ((cid != kNullCid) && (guarded_cid() == kNullCid)) {
    // Assigning non-null value to a field that previously contained only null
    // turns it into a nullable field with the given class id.
    ASSERT(is_nullable());
    set_guarded_cid(cid);
  } else {
    // Give up on tracking class id of values contained in this field.
    ASSERT(guarded_cid() != cid);
    set_guarded_cid(kDynamicCid);
    set_is_nullable(true);
  }

  // If we were tracking length drop collected feedback.
  if (needs_length_check()) {
    ASSERT(guarded_list_length() != Field::kUnknownFixedLength);
    set_guarded_list_length(Field::kNoFixedLength);
    set_guarded_list_length_in_object_offset(Field::kUnknownLengthOffset);
  }

  // Expected class id or nullability of the field changed.
  return true;
}

void Field::RecordStore(const Object& value) const {
  ASSERT(IsOriginal());
  if (!Isolate::Current()->use_field_guards()) {
    return;
  }

  if (FLAG_trace_field_guards) {
    THR_Print("Store %s %s <- %s\n", ToCString(), GuardedPropertiesAsCString(),
              value.ToCString());
  }

  if (UpdateGuardedCidAndLength(value)) {
    if (FLAG_trace_field_guards) {
      THR_Print("    => %s\n", GuardedPropertiesAsCString());
    }

    DeoptimizeDependentCode();
  }
}

void Field::ForceDynamicGuardedCidAndLength() const {
  // Assume nothing about this field.
  set_is_unboxing_candidate(false);
  set_guarded_cid(kDynamicCid);
  set_is_nullable(true);
  set_guarded_list_length(Field::kNoFixedLength);
  set_guarded_list_length_in_object_offset(Field::kUnknownLengthOffset);
  // Drop any code that relied on the above assumptions.
  DeoptimizeDependentCode();
}

void LiteralToken::set_literal(const String& literal) const {
  StorePointer(&raw_ptr()->literal_, literal.raw());
}

void LiteralToken::set_value(const Object& value) const {
  StorePointer(&raw_ptr()->value_, value.raw());
}

RawLiteralToken* LiteralToken::New() {
  ASSERT(Object::literal_token_class() != Class::null());
  RawObject* raw = Object::Allocate(LiteralToken::kClassId,
                                    LiteralToken::InstanceSize(), Heap::kOld);
  return reinterpret_cast<RawLiteralToken*>(raw);
}

RawLiteralToken* LiteralToken::New(Token::Kind kind, const String& literal) {
  const LiteralToken& result = LiteralToken::Handle(LiteralToken::New());
  result.set_kind(kind);
  result.set_literal(literal);
  if (kind == Token::kINTEGER) {
    const Integer& value = Integer::Handle(Integer::NewCanonical(literal));
    if (value.IsNull()) {
      // Integer is out of range.
      return LiteralToken::null();
    }
    ASSERT(value.IsSmi() || value.IsOld());
    result.set_value(value);
  } else if (kind == Token::kDOUBLE) {
    const Double& value = Double::Handle(Double::NewCanonical(literal));
    result.set_value(value);
  } else {
    ASSERT(Token::NeedsLiteralToken(kind));
    result.set_value(literal);
  }
  return result.raw();
}

const char* LiteralToken::ToCString() const {
  const String& token = String::Handle(literal());
  return token.ToCString();
}

RawGrowableObjectArray* TokenStream::TokenObjects() const {
  return raw_ptr()->token_objects_;
}

void TokenStream::SetTokenObjects(const GrowableObjectArray& value) const {
  StorePointer(&raw_ptr()->token_objects_, value.raw());
}

RawExternalTypedData* TokenStream::GetStream() const {
  return raw_ptr()->stream_;
}

void TokenStream::SetStream(const ExternalTypedData& value) const {
  StorePointer(&raw_ptr()->stream_, value.raw());
}

void TokenStream::DataFinalizer(void* isolate_callback_data,
                                Dart_WeakPersistentHandle handle,
                                void* peer) {
  ASSERT(peer != NULL);
  ::free(peer);
}

RawString* TokenStream::PrivateKey() const {
  return raw_ptr()->private_key_;
}

void TokenStream::SetPrivateKey(const String& value) const {
  StorePointer(&raw_ptr()->private_key_, value.raw());
}

RawString* TokenStream::GenerateSource() const {
  return GenerateSource(TokenPosition::kMinSource, TokenPosition::kMaxSource);
}

RawString* TokenStream::GenerateSource(TokenPosition start_pos,
                                       TokenPosition end_pos) const {
  Zone* zone = Thread::Current()->zone();
  Iterator iterator(zone, *this, start_pos, Iterator::kAllTokens);
  const ExternalTypedData& data = ExternalTypedData::Handle(zone, GetStream());
  const GrowableObjectArray& literals = GrowableObjectArray::Handle(
      zone, GrowableObjectArray::New(data.Length()));
  const String& private_key = String::Handle(zone, PrivateKey());
  intptr_t private_len = private_key.Length();

  Token::Kind curr = iterator.CurrentTokenKind();
  Token::Kind prev = Token::kILLEGAL;
  // Handles used in the loop.
  Object& obj = Object::Handle(zone);
  String& literal = String::Handle(zone);
  // Current indentation level.
  int indent = 0;

  while ((curr != Token::kEOS) && (iterator.CurrentPosition() < end_pos)) {
    // Remember current values for this token.
    obj = iterator.CurrentToken();
    literal = iterator.MakeLiteralToken(obj);
    // Advance to be able to use next token kind.
    iterator.Advance();
    Token::Kind next = iterator.CurrentTokenKind();

    // Handle the current token.
    if (curr == Token::kSTRING) {
      bool escape_characters = false;
      for (intptr_t i = 0; i < literal.Length(); i++) {
        if (NeedsEscapeSequence(literal.CharAt(i))) {
          escape_characters = true;
        }
      }
      if ((prev != Token::kINTERPOL_VAR) && (prev != Token::kINTERPOL_END)) {
        literals.Add(Symbols::DoubleQuote());
      }
      if (escape_characters) {
        literal = String::EscapeSpecialCharacters(literal);
        literals.Add(literal);
      } else {
        literals.Add(literal);
      }
      if ((next != Token::kINTERPOL_VAR) && (next != Token::kINTERPOL_START)) {
        literals.Add(Symbols::DoubleQuote());
      }
    } else if (curr == Token::kINTERPOL_VAR) {
      literals.Add(Symbols::Dollar());
      if (literal.CharAt(0) == Library::kPrivateIdentifierStart) {
        literal = String::SubString(literal, 0, literal.Length() - private_len);
      }
      literals.Add(literal);
    } else if (curr == Token::kIDENT) {
      if (literal.CharAt(0) == Library::kPrivateIdentifierStart) {
        literal = String::SubString(literal, 0, literal.Length() - private_len);
      }
      literals.Add(literal);
    } else {
      literals.Add(literal);
    }
    // Determine the separation text based on this current token.
    const String* separator = NULL;
    switch (curr) {
      case Token::kLBRACE:
      case Token::kRBRACE:
        if (next != Token::kNEWLINE) {
          separator = &Symbols::Blank();
        }
        break;
      case Token::kPERIOD:
      case Token::kLBRACK:
      case Token::kINTERPOL_VAR:
      case Token::kINTERPOL_START:
      case Token::kINTERPOL_END:
      case Token::kBIT_NOT:
      case Token::kNOT:
        break;
      // In case we see an opening parentheses '(' we increase the indent to
      // align multi-line parameters accordingly. The indent will be removed as
      // soon as we see the matching closing parentheses ')'.
      //
      // Example:
      // SomeVeryLongMethod(
      //     "withVeryLongParameter",
      //     "andAnotherVeryLongParameter",
      //     "andAnotherVeryLongParameter2") { ...
      case Token::kLPAREN:
        indent += 2;
        break;
      case Token::kRPAREN:
        indent -= 2;
        separator = &Symbols::Blank();
        break;
      case Token::kNEWLINE:
        if (prev == Token::kLBRACE) {
          indent++;
        }
        if (next == Token::kRBRACE) {
          indent--;
        }
        break;
      default:
        separator = &Symbols::Blank();
        break;
    }

    // Determine whether the separation text needs to be updated based on the
    // next token.
    switch (next) {
      case Token::kRBRACE:
        break;
      case Token::kNEWLINE:
      case Token::kSEMICOLON:
      case Token::kPERIOD:
      case Token::kCOMMA:
      case Token::kRPAREN:
      case Token::kLBRACK:
      case Token::kRBRACK:
      case Token::kINTERPOL_VAR:
      case Token::kINTERPOL_START:
      case Token::kINTERPOL_END:
        separator = NULL;
        break;
      case Token::kLPAREN:
        if (curr == Token::kCATCH) {
          separator = &Symbols::Blank();
        } else {
          separator = NULL;
        }
        break;
      case Token::kELSE:
        separator = &Symbols::Blank();
        break;
      default:
        // Do nothing.
        break;
    }

    // Update the few cases where both tokens need to be taken into account.
    if (((curr == Token::kIF) || (curr == Token::kFOR)) &&
        (next == Token::kLPAREN)) {
      separator = &Symbols::Blank();
    } else if ((curr == Token::kASSIGN) && (next == Token::kLPAREN)) {
      separator = &Symbols::Blank();
    } else if ((curr == Token::kRETURN || curr == Token::kCONDITIONAL ||
                Token::IsBinaryOperator(curr) ||
                Token::IsEqualityOperator(curr)) &&
               (next == Token::kLPAREN)) {
      separator = &Symbols::Blank();
    } else if ((curr == Token::kLBRACE) && (next == Token::kRBRACE)) {
      separator = NULL;
    } else if ((curr == Token::kSEMICOLON) && (next != Token::kNEWLINE)) {
      separator = &Symbols::Blank();
    } else if ((curr == Token::kIS) && (next == Token::kNOT)) {
      separator = NULL;
    } else if ((prev == Token::kIS) && (curr == Token::kNOT)) {
      separator = &Symbols::Blank();
    } else if ((curr == Token::kIDENT) &&
               ((next == Token::kINCR) || (next == Token::kDECR))) {
      separator = NULL;
    } else if (((curr == Token::kINCR) || (curr == Token::kDECR)) &&
               (next == Token::kIDENT)) {
      separator = NULL;
    }

    // Add the separator.
    if (separator != NULL) {
      literals.Add(*separator);
    }

    // Account for indentation in case we printed a newline.
    if (curr == Token::kNEWLINE) {
      for (int i = 0; i < indent; i++) {
        literals.Add(Symbols::TwoSpaces());
      }
    }

    // Setup for next iteration.
    prev = curr;
    curr = next;
  }
  const Array& source = Array::Handle(Array::MakeFixedLength(literals));
  return String::ConcatAll(source);
}

intptr_t TokenStream::ComputeSourcePosition(TokenPosition tok_pos) const {
  Zone* zone = Thread::Current()->zone();
  Iterator iterator(zone, *this, TokenPosition::kMinSource,
                    Iterator::kAllTokens);
  intptr_t src_pos = 0;
  Token::Kind kind = iterator.CurrentTokenKind();
  while ((iterator.CurrentPosition() < tok_pos) && (kind != Token::kEOS)) {
    iterator.Advance();
    kind = iterator.CurrentTokenKind();
    src_pos++;
  }
  return src_pos;
}

RawTokenStream* TokenStream::New() {
  ASSERT(Object::token_stream_class() != Class::null());
  RawObject* raw = Object::Allocate(TokenStream::kClassId,
                                    TokenStream::InstanceSize(), Heap::kOld);
  return reinterpret_cast<RawTokenStream*>(raw);
}

RawTokenStream* TokenStream::New(intptr_t len) {
  if (len < 0 || len > kMaxElements) {
    // This should be caught before we reach here.
    FATAL1("Fatal error in TokenStream::New: invalid len %" Pd "\n", len);
  }
  uint8_t* data = reinterpret_cast<uint8_t*>(::malloc(len));
  ASSERT(data != NULL);
  Zone* zone = Thread::Current()->zone();
  const ExternalTypedData& stream = ExternalTypedData::Handle(
      zone, ExternalTypedData::New(kExternalTypedDataUint8ArrayCid, data, len,
                                   Heap::kOld));
  stream.AddFinalizer(data, DataFinalizer, len);
  const TokenStream& result = TokenStream::Handle(zone, TokenStream::New());
  result.SetStream(stream);
  return result.raw();
}

// CompressedTokenMap maps String and LiteralToken keys to Smi values.
// It also supports lookup by TokenDescriptor.
class CompressedTokenTraits {
 public:
  static const char* Name() { return "CompressedTokenTraits"; }
  static bool ReportStats() { return false; }

  static bool IsMatch(const Scanner::TokenDescriptor& descriptor,
                      const Object& key) {
    if (!key.IsLiteralToken()) {
      return false;
    }
    const LiteralToken& token = LiteralToken::Cast(key);
    return (token.literal() == descriptor.literal->raw()) &&
           (token.kind() == descriptor.kind);
  }

  // Only for non-descriptor lookup and table expansion.
  static bool IsMatch(const Object& a, const Object& b) {
    return a.raw() == b.raw();
  }

  static uword Hash(const Scanner::TokenDescriptor& descriptor) {
    return descriptor.literal->Hash();
  }

  static uword Hash(const Object& key) {
    if (key.IsLiteralToken()) {
      return String::HashRawSymbol(LiteralToken::Cast(key).literal());
    } else {
      return String::Cast(key).Hash();
    }
  }
};
typedef UnorderedHashMap<CompressedTokenTraits> CompressedTokenMap;

// Helper class for creation of compressed token stream data.
class CompressedTokenStreamData : public Scanner::TokenCollector {
 public:
  static const intptr_t kInitialBufferSize = 16 * KB;
  static const bool kPrintTokenObjects = false;

  CompressedTokenStreamData(const GrowableObjectArray& ta,
                            CompressedTokenMap* map,
                            Obfuscator* obfuscator)
      : buffer_(NULL),
        stream_(&buffer_, Reallocate, kInitialBufferSize),
        token_objects_(ta),
        tokens_(map),
        str_(String::Handle()),
        value_(Object::Handle()),
        fresh_index_smi_(Smi::Handle()),
        num_tokens_collected_(0),
        obfuscator_(obfuscator) {}
  virtual ~CompressedTokenStreamData() {}

  virtual void AddToken(const Scanner::TokenDescriptor& token) {
    if (token.kind == Token::kIDENT) {  // Identifier token.
      AddIdentToken(*token.literal);
    } else if (token.kind == Token::kINTERPOL_VAR) {
      str_ = token.literal->raw();
      str_ = obfuscator_->Rename(str_);

      Scanner::TokenDescriptor token_copy = token;
      token_copy.literal = &str_;
      AddLiteralToken(token_copy);
    } else if (Token::NeedsLiteralToken(token.kind)) {  // Literal token.
      AddLiteralToken(token);
    } else {  // Keyword, pseudo keyword etc.
      ASSERT(token.kind < Token::kNumTokens);
      AddSimpleToken(token.kind);
    }
    num_tokens_collected_++;
  }

  // Return the compressed token stream.
  uint8_t* GetStream() const { return buffer_; }

  // Return the compressed token stream length.
  intptr_t Length() const { return stream_.bytes_written(); }

  intptr_t NumTokens() const { return num_tokens_collected_; }

 private:
  // Add an IDENT token into the stream and the token hash map.
  void AddIdentToken(const String& ident) {
    ASSERT(ident.IsSymbol());
    const intptr_t fresh_index = token_objects_.Length();
    str_ = ident.raw();
    str_ = obfuscator_->Rename(str_);
    fresh_index_smi_ = Smi::New(fresh_index);
    intptr_t index = Smi::Value(
        Smi::RawCast(tokens_->InsertOrGetValue(ident, fresh_index_smi_)));
    if (index == fresh_index) {
      token_objects_.Add(str_);
      if (kPrintTokenObjects) {
        int iid = Isolate::Current()->main_port() % 1024;
        OS::Print("%03x ident <%s -> %s>\n", iid, ident.ToCString(),
                  str_.ToCString());
      }
    }
    WriteIndex(index);
  }

  // Add a LITERAL token into the stream and the token hash map.
  void AddLiteralToken(const Scanner::TokenDescriptor& descriptor) {
    ASSERT(descriptor.literal->IsSymbol());
    bool is_present = false;
    value_ = tokens_->GetOrNull(descriptor, &is_present);
    intptr_t index = -1;
    if (is_present) {
      ASSERT(value_.IsSmi());
      index = Smi::Cast(value_).Value();
    } else {
      const intptr_t fresh_index = token_objects_.Length();
      fresh_index_smi_ = Smi::New(fresh_index);
      const LiteralToken& lit = LiteralToken::Handle(
          LiteralToken::New(descriptor.kind, *descriptor.literal));
      if (lit.IsNull()) {
        // Convert token to an error.
        ASSERT(descriptor.kind == Token::kINTEGER);
        ASSERT(FLAG_limit_ints_to_64_bits);
        Scanner::TokenDescriptor errorDesc = descriptor;
        errorDesc.kind = Token::kERROR;
        errorDesc.literal = &String::Handle(Symbols::NewFormatted(
            Thread::Current(), "integer literal %s is out of range",
            descriptor.literal->ToCString()));
        AddLiteralToken(errorDesc);
        return;
      }
      index = Smi::Value(
          Smi::RawCast(tokens_->InsertOrGetValue(lit, fresh_index_smi_)));
      token_objects_.Add(lit);
      if (kPrintTokenObjects) {
        int iid = Isolate::Current()->main_port() % 1024;
        printf("lit    %03x  %p  %p  %p  <%s>\n", iid, token_objects_.raw(),
               lit.literal(), lit.value(),
               String::Handle(lit.literal()).ToCString());
      }
    }
    WriteIndex(index);
  }

  // Add a simple token into the stream.
  void AddSimpleToken(intptr_t kind) { stream_.WriteUnsigned(kind); }

  void WriteIndex(intptr_t value) {
    stream_.WriteUnsigned(value + Token::kNumTokens);
  }

  static uint8_t* Reallocate(uint8_t* ptr,
                             intptr_t old_size,
                             intptr_t new_size) {
    void* new_ptr = ::realloc(reinterpret_cast<void*>(ptr), new_size);
    return reinterpret_cast<uint8_t*>(new_ptr);
  }

  uint8_t* buffer_;
  WriteStream stream_;
  const GrowableObjectArray& token_objects_;
  CompressedTokenMap* tokens_;
  String& str_;
  Object& value_;
  Smi& fresh_index_smi_;
  intptr_t num_tokens_collected_;
  Obfuscator* obfuscator_;

  DISALLOW_COPY_AND_ASSIGN(CompressedTokenStreamData);
};

RawTokenStream* TokenStream::New(const String& source,
                                 const String& private_key,
                                 bool use_shared_tokens) {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();

  GrowableObjectArray& token_objects = GrowableObjectArray::Handle(zone);
  Array& token_objects_map = Array::Handle(zone);
  if (use_shared_tokens) {
    // Use the shared token objects array in the object store. Allocate
    // a new array if necessary.
    ObjectStore* store = thread->isolate()->object_store();
    if (store->token_objects() == GrowableObjectArray::null()) {
      OpenSharedTokenList(thread->isolate());
    }
    token_objects = store->token_objects();
    token_objects_map = store->token_objects_map();
  } else {
    // Use new, non-shared token array.
    const int kInitialPrivateCapacity = 256;
    token_objects =
        GrowableObjectArray::New(kInitialPrivateCapacity, Heap::kOld);
    token_objects_map = HashTables::New<CompressedTokenMap>(
        kInitialPrivateCapacity, Heap::kOld);
  }
  Obfuscator obfuscator(thread, private_key);
  CompressedTokenMap map(token_objects_map.raw());
  CompressedTokenStreamData data(token_objects, &map, &obfuscator);
  Scanner scanner(source, private_key);
  scanner.ScanAll(&data);
  INC_STAT(thread, num_tokens_scanned, data.NumTokens());

  // Create and setup the token stream object.
  const ExternalTypedData& stream = ExternalTypedData::Handle(
      zone,
      ExternalTypedData::New(kExternalTypedDataUint8ArrayCid, data.GetStream(),
                             data.Length(), Heap::kOld));
  intptr_t external_size = data.Length();
  stream.AddFinalizer(data.GetStream(), DataFinalizer, external_size);
  const TokenStream& result = TokenStream::Handle(zone, New());
  result.SetPrivateKey(private_key);
  {
    NoSafepointScope no_safepoint;
    result.SetStream(stream);
    result.SetTokenObjects(token_objects);
  }

  token_objects_map = map.Release().raw();
  if (use_shared_tokens) {
    thread->isolate()->object_store()->set_token_objects_map(token_objects_map);
  }
  return result.raw();
}

void TokenStream::OpenSharedTokenList(Isolate* isolate) {
  const int kInitialSharedCapacity = 5 * 1024;
  ObjectStore* store = isolate->object_store();
  ASSERT(store->token_objects() == GrowableObjectArray::null());
  const GrowableObjectArray& token_objects = GrowableObjectArray::Handle(
      GrowableObjectArray::New(kInitialSharedCapacity, Heap::kOld));
  store->set_token_objects(token_objects);
  const Array& token_objects_map = Array::Handle(
      HashTables::New<CompressedTokenMap>(kInitialSharedCapacity, Heap::kOld));
  store->set_token_objects_map(token_objects_map);
}

void TokenStream::CloseSharedTokenList(Isolate* isolate) {
  isolate->object_store()->set_token_objects(GrowableObjectArray::Handle());
  isolate->object_store()->set_token_objects_map(Array::null_array());
}

const char* TokenStream::ToCString() const {
  return "TokenStream";
}

TokenStream::Iterator::Iterator(Zone* zone,
                                const TokenStream& tokens,
                                TokenPosition token_pos,
                                Iterator::StreamType stream_type)
    : tokens_(TokenStream::Handle(zone, tokens.raw())),
      data_(ExternalTypedData::Handle(zone, tokens.GetStream())),
      stream_(reinterpret_cast<uint8_t*>(data_.DataAddr(0)), data_.Length()),
      token_objects_(Array::Handle(
          zone,
          GrowableObjectArray::Handle(zone, tokens.TokenObjects()).data())),
      obj_(Object::Handle(zone)),
      cur_token_pos_(token_pos.Pos()),
      cur_token_kind_(Token::kILLEGAL),
      cur_token_obj_index_(-1),
      stream_type_(stream_type) {
  ASSERT(token_pos != TokenPosition::kNoSource);
  if (token_pos.IsReal()) {
    SetCurrentPosition(token_pos);
  }
}

void TokenStream::Iterator::SetStream(const TokenStream& tokens,
                                      TokenPosition token_pos) {
  tokens_ = tokens.raw();
  data_ = tokens.GetStream();
  stream_.SetStream(reinterpret_cast<uint8_t*>(data_.DataAddr(0)),
                    data_.Length());
  token_objects_ = GrowableObjectArray::Handle(tokens.TokenObjects()).data();
  obj_ = Object::null();
  cur_token_pos_ = token_pos.Pos();
  cur_token_kind_ = Token::kILLEGAL;
  cur_token_obj_index_ = -1;
  SetCurrentPosition(token_pos);
}

bool TokenStream::Iterator::IsValid() const {
  return !tokens_.IsNull();
}

Token::Kind TokenStream::Iterator::LookaheadTokenKind(intptr_t num_tokens) {
  intptr_t saved_position = stream_.Position();
  Token::Kind kind = Token::kILLEGAL;
  intptr_t value = -1;
  intptr_t count = 0;
  while (count < num_tokens && value != Token::kEOS) {
    value = ReadToken();
    if ((stream_type_ == kAllTokens) ||
        (static_cast<Token::Kind>(value) != Token::kNEWLINE)) {
      count += 1;
    }
  }
  if (value < Token::kNumTokens) {
    kind = static_cast<Token::Kind>(value);
  } else {
    value = value - Token::kNumTokens;
    obj_ = token_objects_.At(value);
    if (obj_.IsLiteralToken()) {
      const LiteralToken& literal_token = LiteralToken::Cast(obj_);
      kind = literal_token.kind();
    } else {
      ASSERT(obj_.IsString());  // Must be an identifier.
      kind = Token::kIDENT;
    }
  }
  stream_.SetPosition(saved_position);
  return kind;
}

TokenPosition TokenStream::Iterator::CurrentPosition() const {
  return TokenPosition(cur_token_pos_);
}

void TokenStream::Iterator::SetCurrentPosition(TokenPosition token_pos) {
  stream_.SetPosition(token_pos.value());
  Advance();
}

void TokenStream::Iterator::Advance() {
  intptr_t value;
  do {
    cur_token_pos_ = stream_.Position();
    value = ReadToken();
  } while ((stream_type_ == kNoNewlines) &&
           (static_cast<Token::Kind>(value) == Token::kNEWLINE));
  if (value < Token::kNumTokens) {
    cur_token_kind_ = static_cast<Token::Kind>(value);
    cur_token_obj_index_ = -1;
    return;
  }
  cur_token_obj_index_ = value - Token::kNumTokens;
  obj_ = token_objects_.At(cur_token_obj_index_);
  if (obj_.IsLiteralToken()) {
    const LiteralToken& literal_token = LiteralToken::Cast(obj_);
    cur_token_kind_ = literal_token.kind();
    return;
  }
  ASSERT(obj_.IsString());  // Must be an identifier.
  cur_token_kind_ = Token::kIDENT;
}

RawObject* TokenStream::Iterator::CurrentToken() const {
  if (cur_token_obj_index_ != -1) {
    return token_objects_.At(cur_token_obj_index_);
  } else {
    return Smi::New(cur_token_kind_);
  }
}

RawString* TokenStream::Iterator::CurrentLiteral() const {
  obj_ = CurrentToken();
  return MakeLiteralToken(obj_);
}

RawString* TokenStream::Iterator::MakeLiteralToken(const Object& obj) const {
  if (obj.IsString()) {
    return reinterpret_cast<RawString*>(obj.raw());
  } else if (obj.IsSmi()) {
    Token::Kind kind = static_cast<Token::Kind>(
        Smi::Value(reinterpret_cast<RawSmi*>(obj.raw())));
    ASSERT(kind < Token::kNumTokens);
    return Symbols::Token(kind).raw();
  } else {
    ASSERT(obj.IsLiteralToken());  // Must be a literal token.
    const LiteralToken& literal_token = LiteralToken::Cast(obj);
    return literal_token.literal();
  }
}

bool Script::HasSource() const {
  return raw_ptr()->source_ != String::null();
}

RawString* Script::Source() const {
  String& source = String::Handle(raw_ptr()->source_);
  if (source.IsNull()) {
    if (kind() == RawScript::kKernelTag) {
      return String::null();
    }
    return GenerateSource();
  }
  return raw_ptr()->source_;
}

RawString* Script::GenerateSource() const {
  const TokenStream& token_stream = TokenStream::Handle(tokens());
  if (token_stream.IsNull()) {
    ASSERT(Dart::vm_snapshot_kind() == Snapshot::kFullAOT);
    return String::null();
  }
  return token_stream.GenerateSource();
}

void Script::set_compile_time_constants(const Array& value) const {
  StorePointer(&raw_ptr()->compile_time_constants_, value.raw());
}

void Script::set_kernel_program_info(const KernelProgramInfo& info) const {
  StorePointer(&raw_ptr()->kernel_program_info_, info.raw());
}

void Script::set_kernel_script_index(const intptr_t kernel_script_index) const {
  StoreNonPointer(&raw_ptr()->kernel_script_index_, kernel_script_index);
}

RawTypedData* Script::kernel_string_offsets() const {
  KernelProgramInfo& program_info =
      KernelProgramInfo::Handle(kernel_program_info());
  ASSERT(!program_info.IsNull());
  return program_info.string_offsets();
}

RawGrowableObjectArray* Script::GenerateLineNumberArray() const {
  Zone* zone = Thread::Current()->zone();
  const GrowableObjectArray& info =
      GrowableObjectArray::Handle(zone, GrowableObjectArray::New());
  const String& source = String::Handle(zone, Source());
  const String& key = Symbols::Empty();
  const Object& line_separator = Object::Handle(zone);
  Smi& value = Smi::Handle(zone);

  if (kind() == RawScript::kKernelTag) {
    const TypedData& line_starts_data = TypedData::Handle(zone, line_starts());
    if (line_starts_data.IsNull()) {
      // Scripts in the AOT snapshot do not have a line starts array.
      // A well-formed line number array has a leading null.
      info.Add(line_separator);  // New line.
      return info.raw();
    }
#if !defined(DART_PRECOMPILED_RUNTIME)
    intptr_t line_count = line_starts_data.Length();
    ASSERT(line_count > 0);
    const Array& debug_positions_array = Array::Handle(debug_positions());
    intptr_t token_count = debug_positions_array.Length();
    int token_index = 0;

    kernel::KernelLineStartsReader line_starts_reader(line_starts_data, zone);
    intptr_t previous_start = 0;
    for (int line_index = 0; line_index < line_count; ++line_index) {
      intptr_t start = previous_start + line_starts_reader.DeltaAt(line_index);
      // Output the rest of the tokens if we have no next line.
      intptr_t end = TokenPosition::kMaxSourcePos;
      if (line_index + 1 < line_count) {
        end = start + line_starts_reader.DeltaAt(line_index + 1);
      }
      bool first = true;
      while (token_index < token_count) {
        value ^= debug_positions_array.At(token_index);
        intptr_t debug_position = value.Value();
        if (debug_position >= end) break;

        if (first) {
          info.Add(line_separator);          // New line.
          value = Smi::New(line_index + 1);  // Line number.
          info.Add(value);
          first = false;
        }

        value ^= debug_positions_array.At(token_index);
        info.Add(value);                               // Token position.
        value = Smi::New(debug_position - start + 1);  // Column.
        info.Add(value);
        ++token_index;
      }
      previous_start = start;
    }
#endif  // !defined(DART_PRECOMPILED_RUNTIME)
    return info.raw();
  }

  const TokenStream& tkns = TokenStream::Handle(zone, tokens());
  String& tokenValue = String::Handle(zone);
  ASSERT(!tkns.IsNull());
  TokenStream::Iterator tkit(zone, tkns, TokenPosition::kMinSource,
                             TokenStream::Iterator::kAllTokens);
  int current_line = -1;
  Scanner s(source, key);
  s.Scan();
  bool skippedNewline = false;
  while (tkit.CurrentTokenKind() != Token::kEOS) {
    if (tkit.CurrentTokenKind() == Token::kNEWLINE) {
      // Skip newlines from the token stream.
      skippedNewline = true;
      tkit.Advance();
      continue;
    }
    if (s.current_token().kind != tkit.CurrentTokenKind()) {
      // Suppose we have a multiline string with interpolation:
      //
      // 10    '''
      // 11    bar
      // 12    baz
      // 13    foo is $foo
      // 14    '''
      //
      // In the token stream, this becomes something like:
      //
      // 10    string('bar\nbaz\nfoo is\n')
      // 11    newline
      // 12    newline
      // 13    string('') interpol_var(foo) string('\n')
      // 14
      //
      // In order to keep the token iterator and the scanner in sync,
      // we need to skip the extra empty string before the
      // interpolation.
      if (skippedNewline &&
          (s.current_token().kind == Token::kINTERPOL_VAR ||
           s.current_token().kind == Token::kINTERPOL_START) &&
          tkit.CurrentTokenKind() == Token::kSTRING) {
        tokenValue = tkit.CurrentLiteral();
        if (tokenValue.Length() == 0) {
          tkit.Advance();
        }
      }
    }
    skippedNewline = false;
    ASSERT(s.current_token().kind == tkit.CurrentTokenKind());
    int token_line = s.current_token().position.line;
    if (token_line != current_line) {
      // emit line
      info.Add(line_separator);
      value = Smi::New(token_line + line_offset());
      info.Add(value);
      current_line = token_line;
    }
    // TODO(hausner): Could optimize here by not reporting tokens
    // that will never be a location used by the debugger, e.g.
    // braces, semicolons, most keywords etc.
    value = Smi::New(tkit.CurrentPosition().Pos());
    info.Add(value);
    int column = s.current_token().position.column;
    // On the first line of the script we must add the column offset.
    if (token_line == 1) {
      column += col_offset();
    }
    value = Smi::New(column);
    info.Add(value);
    tkit.Advance();
    s.Scan();
  }
  return info.raw();
}

const char* Script::GetKindAsCString() const {
  switch (kind()) {
    case RawScript::kScriptTag:
      return "script";
    case RawScript::kLibraryTag:
      return "library";
    case RawScript::kSourceTag:
      return "source";
    case RawScript::kPatchTag:
      return "patch";
    case RawScript::kEvaluateTag:
      return "evaluate";
    case RawScript::kKernelTag:
      return "kernel";
    default:
      UNIMPLEMENTED();
  }
  UNREACHABLE();
  return NULL;
}

void Script::set_url(const String& value) const {
  StorePointer(&raw_ptr()->url_, value.raw());
}

void Script::set_resolved_url(const String& value) const {
  StorePointer(&raw_ptr()->resolved_url_, value.raw());
}

void Script::set_source(const String& value) const {
  StorePointer(&raw_ptr()->source_, value.raw());
}

void Script::set_line_starts(const TypedData& value) const {
  StorePointer(&raw_ptr()->line_starts_, value.raw());
}

void Script::set_debug_positions(const Array& value) const {
  StorePointer(&raw_ptr()->debug_positions_, value.raw());
}

void Script::set_yield_positions(const Array& value) const {
  StorePointer(&raw_ptr()->yield_positions_, value.raw());
}

RawArray* Script::yield_positions() const {
#if !defined(DART_PRECOMPILED_RUNTIME)
  Array& yields = Array::Handle(raw_ptr()->yield_positions_);
  if (yields.IsNull() && kind() == RawScript::kKernelTag) {
    // This is created lazily. Now we need it.
    kernel::CollectTokenPositionsFor(*this);
  }
#endif  // !defined(DART_PRECOMPILED_RUNTIME)
  return raw_ptr()->yield_positions_;
}

RawTypedData* Script::line_starts() const {
  return raw_ptr()->line_starts_;
}

RawArray* Script::debug_positions() const {
#if !defined(DART_PRECOMPILED_RUNTIME)
  Array& debug_positions_array = Array::Handle(raw_ptr()->debug_positions_);
  if (debug_positions_array.IsNull() && kind() == RawScript::kKernelTag) {
    // This is created lazily. Now we need it.
    kernel::CollectTokenPositionsFor(*this);
  }
#endif  // !defined(DART_PRECOMPILED_RUNTIME)
  return raw_ptr()->debug_positions_;
}

void Script::set_kind(RawScript::Kind value) const {
  StoreNonPointer(&raw_ptr()->kind_, value);
}

void Script::set_load_timestamp(int64_t value) const {
  StoreNonPointer(&raw_ptr()->load_timestamp_, value);
}

void Script::set_tokens(const TokenStream& value) const {
  StorePointer(&raw_ptr()->tokens_, value.raw());
}

void Script::Tokenize(const String& private_key, bool use_shared_tokens) const {
  if (kind() == RawScript::kKernelTag) {
    return;
  }

  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  const TokenStream& tkns = TokenStream::Handle(zone, tokens());
  if (!tkns.IsNull()) {
    // Already tokenized.
    return;
  }

  // Get the source, scan and allocate the token stream.
  VMTagScope tagScope(thread, VMTag::kCompileScannerTagId);
  CSTAT_TIMER_SCOPE(thread, scanner_timer);
  const String& src = String::Handle(zone, Source());
  const TokenStream& ts = TokenStream::Handle(
      zone, TokenStream::New(src, private_key, use_shared_tokens));
  set_tokens(ts);
  INC_STAT(thread, src_length, src.Length());
}

void Script::SetLocationOffset(intptr_t line_offset,
                               intptr_t col_offset) const {
  ASSERT(line_offset >= 0);
  ASSERT(col_offset >= 0);
  StoreNonPointer(&raw_ptr()->line_offset_, line_offset);
  StoreNonPointer(&raw_ptr()->col_offset_, col_offset);
}

// Specialized for AOT compilation, which does this lookup for every token
// position that could be part of a stack trace.
intptr_t Script::GetTokenLineUsingLineStarts(
    TokenPosition target_token_pos) const {
  if (target_token_pos.IsNoSource()) {
    return 0;
  }
  Zone* zone = Thread::Current()->zone();
  TypedData& line_starts_data = TypedData::Handle(zone, line_starts());
  if (line_starts_data.IsNull()) {
    ASSERT(kind() != RawScript::kKernelTag);
    const TokenStream& tkns = TokenStream::Handle(zone, tokens());

    intptr_t line_count = 0;
    {
      // Evaluate the number of lines in the script.
      TokenStream::Iterator tkit(zone, tkns, TokenPosition::kMinSource,
                                 TokenStream::Iterator::kAllTokens);
      while (tkit.CurrentTokenKind() != Token::kEOS) {
        if (tkit.CurrentTokenKind() == Token::kNEWLINE) {
          line_count++;
        }
        tkit.Advance();
      }
    }
    line_starts_data = TypedData::New(kTypedDataInt32ArrayCid, line_count + 1);

    intptr_t cur_line = 0;
    TokenStream::Iterator tkit(zone, tkns, TokenPosition::kMinSource,
                               TokenStream::Iterator::kAllTokens);
    line_starts_data.SetInt32(cur_line, 0);
    while (tkit.CurrentTokenKind() != Token::kEOS) {
      if (tkit.CurrentTokenKind() == Token::kNEWLINE) {
        cur_line++;
        line_starts_data.SetInt32(cur_line << 2,
                                  tkit.CurrentPosition().value() + 1);
      }
      tkit.Advance();
    }
    set_line_starts(line_starts_data);
  }

  if (kind() == RawScript::kKernelTag) {
#if !defined(DART_PRECOMPILED_RUNTIME)
    kernel::KernelLineStartsReader line_starts_reader(line_starts_data, zone);
    return line_starts_reader.LineNumberForPosition(target_token_pos.value());
#else
    return 0;
#endif  // !defined(DART_PRECOMPILED_RUNTIME)
  } else {
    ASSERT(line_starts_data.Length() > 0);
    intptr_t offset = target_token_pos.Pos();
    intptr_t min = 0;
    intptr_t max = line_starts_data.Length() - 1;

    // Binary search to find the line containing this offset.
    while (min < max) {
      int midpoint = (max - min + 1) / 2 + min;
      int32_t token_pos = line_starts_data.GetInt32(midpoint * 4);
      if (token_pos > offset) {
        max = midpoint - 1;
      } else {
        min = midpoint;
      }
    }
    return min + 1;  // Line numbers start at 1.
  }
}

void Script::GetTokenLocation(TokenPosition token_pos,
                              intptr_t* line,
                              intptr_t* column,
                              intptr_t* token_len) const {
  ASSERT(line != NULL);
  Zone* zone = Thread::Current()->zone();

  if (kind() == RawScript::kKernelTag) {
    const TypedData& line_starts_data = TypedData::Handle(zone, line_starts());
    if (line_starts_data.IsNull()) {
      // Scripts in the AOT snapshot do not have a line starts array.
      *line = -1;
      if (column != NULL) {
        *column = -1;
      }
      if (token_len != NULL) {
        *token_len = 1;
      }
      return;
    }
#if !defined(DART_PRECOMPILED_RUNTIME)
    ASSERT(line_starts_data.Length() > 0);
    kernel::KernelLineStartsReader line_starts_reader(line_starts_data, zone);
    line_starts_reader.LocationForPosition(token_pos.value(), line, column);
    if (token_len != NULL) {
      // We don't explicitly save this data: Load the source
      // and find it from there.
      const String& source = String::Handle(zone, Source());
      intptr_t offset = token_pos.value();
      *token_len = 1;
      if (offset < source.Length() &&
          Scanner::IsIdentStartChar(source.CharAt(offset))) {
        for (intptr_t i = offset + 1;
             i < source.Length() && Scanner::IsIdentChar(source.CharAt(i));
             ++i) {
          ++*token_len;
        }
      }
    }
#endif  // !defined(DART_PRECOMPILED_RUNTIME)
    return;
  }

  const TokenStream& tkns = TokenStream::Handle(zone, tokens());
  if (tkns.IsNull()) {
    ASSERT((Dart::vm_snapshot_kind() == Snapshot::kFullAOT));
    *line = -1;
    if (column != NULL) {
      *column = -1;
    }
    if (token_len != NULL) {
      *token_len = 1;
    }
    return;
  }
  if (column == NULL) {
    TokenStream::Iterator tkit(zone, tkns, TokenPosition::kMinSource,
                               TokenStream::Iterator::kAllTokens);
    intptr_t cur_line = line_offset() + 1;
    while ((tkit.CurrentPosition() < token_pos) &&
           (tkit.CurrentTokenKind() != Token::kEOS)) {
      if (tkit.CurrentTokenKind() == Token::kNEWLINE) {
        cur_line++;
      }
      tkit.Advance();
    }
    *line = cur_line;
  } else {
    const String& src = String::Handle(zone, Source());
    intptr_t src_pos = tkns.ComputeSourcePosition(token_pos);
    Scanner scanner(src, Symbols::Empty());
    scanner.ScanTo(src_pos);
    intptr_t relative_line = scanner.CurrentPosition().line;
    *line = relative_line + line_offset();
    *column = scanner.CurrentPosition().column;
    if (token_len != NULL) {
      if (scanner.current_token().literal != NULL) {
        *token_len = scanner.current_token().literal->Length();
      } else {
        *token_len = 1;
      }
    }
    // On the first line of the script we must add the column offset.
    if (relative_line == 1) {
      *column += col_offset();
    }
  }
}

void Script::TokenRangeAtLine(intptr_t line_number,
                              TokenPosition* first_token_index,
                              TokenPosition* last_token_index) const {
  ASSERT(first_token_index != NULL && last_token_index != NULL);
  ASSERT(line_number > 0);

  if (kind() == RawScript::kKernelTag) {
    const TypedData& line_starts_data = TypedData::Handle(line_starts());
    if (line_starts_data.IsNull()) {
      // Scripts in the AOT snapshot do not have a line starts array.
      *first_token_index = TokenPosition::kNoSource;
      *last_token_index = TokenPosition::kNoSource;
      return;
    }
#if !defined(DART_PRECOMPILED_RUNTIME)
    kernel::KernelLineStartsReader line_starts_reader(
        line_starts_data, Thread::Current()->zone());
    line_starts_reader.TokenRangeAtLine(String::Handle(Source()).Length(),
                                        line_number, first_token_index,
                                        last_token_index);
#endif  // !defined(DART_PRECOMPILED_RUNTIME)
    return;
  }

  Zone* zone = Thread::Current()->zone();
  *first_token_index = TokenPosition::kNoSource;
  *last_token_index = TokenPosition::kNoSource;
  const TokenStream& tkns = TokenStream::Handle(zone, tokens());
  line_number -= line_offset();
  if (line_number < 1) line_number = 1;
  TokenStream::Iterator tkit(zone, tkns, TokenPosition::kMinSource,
                             TokenStream::Iterator::kAllTokens);
  // Scan through the token stream to the required line.
  intptr_t cur_line = 1;
  while (cur_line < line_number && tkit.CurrentTokenKind() != Token::kEOS) {
    if (tkit.CurrentTokenKind() == Token::kNEWLINE) {
      cur_line++;
    }
    tkit.Advance();
  }
  if (tkit.CurrentTokenKind() == Token::kEOS) {
    // End of token stream before reaching required line.
    return;
  }
  if (tkit.CurrentTokenKind() == Token::kNEWLINE) {
    // No tokens on the current line. If there is a valid token afterwards, put
    // it into first_token_index.
    while (tkit.CurrentTokenKind() == Token::kNEWLINE &&
           tkit.CurrentTokenKind() != Token::kEOS) {
      tkit.Advance();
    }
    if (tkit.CurrentTokenKind() != Token::kEOS) {
      *first_token_index = tkit.CurrentPosition();
    }
    return;
  }
  *first_token_index = tkit.CurrentPosition();
  // We cannot do "CurrentPosition() - 1" for the last token, because we do not
  // know whether the previous token is a simple one or not.
  TokenPosition end_pos = *first_token_index;
  while (tkit.CurrentTokenKind() != Token::kNEWLINE &&
         tkit.CurrentTokenKind() != Token::kEOS) {
    end_pos = tkit.CurrentPosition();
    tkit.Advance();
  }
  *last_token_index = end_pos;
}

int32_t Script::SourceFingerprint() const {
  return SourceFingerprint(TokenPosition(TokenPosition::kMinSourcePos),
                           TokenPosition(TokenPosition::kMaxSourcePos));
}

int32_t Script::SourceFingerprint(TokenPosition start,
                                  TokenPosition end) const {
  if (kind() == RawScript::kKernelTag) {
    // TODO(30756): Implemented.
    return 0;
  }
  uint32_t result = 0;
  Zone* zone = Thread::Current()->zone();
  TokenStream::Iterator tokens_iterator(
      zone, TokenStream::Handle(zone, tokens()), start);
  Object& obj = Object::Handle(zone);
  String& literal = String::Handle(zone);
  while ((tokens_iterator.CurrentTokenKind() != Token::kEOS) &&
         (tokens_iterator.CurrentPosition() < end)) {
    uint32_t val = 0;
    obj = tokens_iterator.CurrentToken();
    if (obj.IsSmi()) {
      val = Smi::Cast(obj).Value();
    } else {
      literal = tokens_iterator.MakeLiteralToken(obj);
      if (tokens_iterator.CurrentTokenKind() == Token::kIDENT ||
          tokens_iterator.CurrentTokenKind() == Token::kINTERPOL_VAR) {
        literal = String::RemovePrivateKey(literal);
      }
      val = literal.Hash();
    }
    result = 31 * result + val;
    tokens_iterator.Advance();
  }
  result = result & ((static_cast<uint32_t>(1) << 31) - 1);
  ASSERT(result <= static_cast<uint32_t>(kMaxInt32));
  return result;
}

RawString* Script::GetLine(intptr_t line_number, Heap::Space space) const {
  const String& src = String::Handle(Source());
  if (src.IsNull()) {
    ASSERT(Dart::vm_snapshot_kind() == Snapshot::kFullAOT);
    return Symbols::OptimizedOut().raw();
  }
  intptr_t relative_line_number = line_number - line_offset();
  intptr_t current_line = 1;
  intptr_t line_start_idx = -1;
  intptr_t last_char_idx = -1;
  for (intptr_t ix = 0;
       (ix < src.Length()) && (current_line <= relative_line_number); ix++) {
    if ((current_line == relative_line_number) && (line_start_idx < 0)) {
      line_start_idx = ix;
    }
    if (src.CharAt(ix) == '\n') {
      current_line++;
    } else if (src.CharAt(ix) == '\r') {
      if ((ix + 1 != src.Length()) && (src.CharAt(ix + 1) != '\n')) {
        current_line++;
      }
    } else {
      last_char_idx = ix;
    }
  }
  // Guarantee that returned string is never NULL.

  if (line_start_idx >= 0) {
    return String::SubString(src, line_start_idx,
                             last_char_idx - line_start_idx + 1, space);
  } else {
    return Symbols::Empty().raw();
  }
}

RawString* Script::GetSnippet(TokenPosition from, TokenPosition to) const {
  intptr_t from_line;
  intptr_t from_column;
  intptr_t to_line;
  intptr_t to_column;
  GetTokenLocation(from, &from_line, &from_column);
  GetTokenLocation(to, &to_line, &to_column);
  return GetSnippet(from_line, from_column, to_line, to_column);
}

RawString* Script::GetSnippet(intptr_t from_line,
                              intptr_t from_column,
                              intptr_t to_line,
                              intptr_t to_column) const {
  const String& src = String::Handle(Source());
  if (src.IsNull()) {
    ASSERT(Dart::vm_snapshot_kind() == Snapshot::kFullAOT);
    return Symbols::OptimizedOut().raw();
  }
  intptr_t length = src.Length();
  intptr_t line = 1 + line_offset();
  intptr_t column = 1;
  intptr_t scan_position = 0;
  intptr_t snippet_start = -1;
  intptr_t snippet_end = -1;
  if (from_line - line_offset() == 1) {
    column += col_offset();
  }

  while (scan_position != length) {
    if (snippet_start == -1) {
      if ((line == from_line) && (column == from_column)) {
        snippet_start = scan_position;
      }
    }

    char c = src.CharAt(scan_position);
    if (c == '\n') {
      line++;
      column = 0;
    } else if (c == '\r') {
      line++;
      column = 0;
      if ((scan_position + 1 != length) &&
          (src.CharAt(scan_position + 1) == '\n')) {
        scan_position++;
      }
    }
    scan_position++;
    column++;

    if ((line == to_line) && (column == to_column)) {
      snippet_end = scan_position;
      break;
    }
  }
  String& snippet = String::Handle();
  if ((snippet_start != -1) && (snippet_end != -1)) {
    snippet =
        String::SubString(src, snippet_start, snippet_end - snippet_start);
  }
  return snippet.raw();
}

RawScript* Script::New() {
  ASSERT(Object::script_class() != Class::null());
  RawObject* raw =
      Object::Allocate(Script::kClassId, Script::InstanceSize(), Heap::kOld);
  return reinterpret_cast<RawScript*>(raw);
}

RawScript* Script::New(const String& url,
                       const String& source,
                       RawScript::Kind kind) {
  return Script::New(url, url, source, kind);
}

RawScript* Script::New(const String& url,
                       const String& resolved_url,
                       const String& source,
                       RawScript::Kind kind) {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  const Script& result = Script::Handle(zone, Script::New());
  result.set_url(String::Handle(zone, Symbols::New(thread, url)));
  result.set_resolved_url(
      String::Handle(zone, Symbols::New(thread, resolved_url)));
  result.set_source(source);
  result.SetLocationOffset(0, 0);
  result.set_kind(kind);
  result.set_kernel_script_index(0);
  result.set_load_timestamp(
      FLAG_remove_script_timestamps_for_test ? 0 : OS::GetCurrentTimeMillis());
  return result.raw();
}

const char* Script::ToCString() const {
  const String& name = String::Handle(url());
  return OS::SCreate(Thread::Current()->zone(), "Script(%s)", name.ToCString());
}

RawLibrary* Script::FindLibrary() const {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  Isolate* isolate = thread->isolate();
  const GrowableObjectArray& libs =
      GrowableObjectArray::Handle(zone, isolate->object_store()->libraries());
  Library& lib = Library::Handle(zone);
  Array& scripts = Array::Handle(zone);
  for (intptr_t i = 0; i < libs.Length(); i++) {
    lib ^= libs.At(i);
    scripts = lib.LoadedScripts();
    for (intptr_t j = 0; j < scripts.Length(); j++) {
      if (scripts.At(j) == raw()) {
        return lib.raw();
      }
    }
  }
  return Library::null();
}

DictionaryIterator::DictionaryIterator(const Library& library)
    : array_(Array::Handle(library.dictionary())),
      // Last element in array is a Smi indicating the number of entries used.
      size_(Array::Handle(library.dictionary()).Length() - 1),
      next_ix_(0) {
  MoveToNextObject();
}

RawObject* DictionaryIterator::GetNext() {
  ASSERT(HasNext());
  int ix = next_ix_++;
  MoveToNextObject();
  ASSERT(array_.At(ix) != Object::null());
  return array_.At(ix);
}

void DictionaryIterator::MoveToNextObject() {
  Object& obj = Object::Handle(array_.At(next_ix_));
  while (obj.IsNull() && HasNext()) {
    next_ix_++;
    obj = array_.At(next_ix_);
  }
}

ClassDictionaryIterator::ClassDictionaryIterator(const Library& library,
                                                 IterationKind kind)
    : DictionaryIterator(library),
      toplevel_class_(Class::Handle((kind == kIteratePrivate)
                                        ? library.toplevel_class()
                                        : Class::null())) {
  MoveToNextClass();
}

RawClass* ClassDictionaryIterator::GetNextClass() {
  ASSERT(HasNext());
  Class& cls = Class::Handle();
  if (next_ix_ < size_) {
    int ix = next_ix_++;
    cls ^= array_.At(ix);
    MoveToNextClass();
    return cls.raw();
  }
  ASSERT(!toplevel_class_.IsNull());
  cls = toplevel_class_.raw();
  toplevel_class_ = Class::null();
  return cls.raw();
}

void ClassDictionaryIterator::MoveToNextClass() {
  Object& obj = Object::Handle();
  while (next_ix_ < size_) {
    obj = array_.At(next_ix_);
    if (obj.IsClass()) {
      return;
    }
    next_ix_++;
  }
}

LibraryPrefixIterator::LibraryPrefixIterator(const Library& library)
    : DictionaryIterator(library) {
  Advance();
}

RawLibraryPrefix* LibraryPrefixIterator::GetNext() {
  ASSERT(HasNext());
  int ix = next_ix_++;
  Object& obj = Object::Handle(array_.At(ix));
  Advance();
  return LibraryPrefix::Cast(obj).raw();
}

void LibraryPrefixIterator::Advance() {
  Object& obj = Object::Handle(array_.At(next_ix_));
  while (!obj.IsLibraryPrefix() && HasNext()) {
    next_ix_++;
    obj = array_.At(next_ix_);
  }
}

static void ReportTooManyImports(const Library& lib) {
  const String& url = String::Handle(lib.url());
  Report::MessageF(Report::kError, Script::Handle(lib.LookupScript(url)),
                   TokenPosition::kNoSource, Report::AtLocation,
                   "too many imports in library '%s'", url.ToCString());
  UNREACHABLE();
}

void Library::set_num_imports(intptr_t value) const {
  if (!Utils::IsUint(16, value)) {
    ReportTooManyImports(*this);
  }
  StoreNonPointer(&raw_ptr()->num_imports_, value);
}

void Library::set_name(const String& name) const {
  ASSERT(name.IsSymbol());
  StorePointer(&raw_ptr()->name_, name.raw());
}

void Library::set_url(const String& name) const {
  StorePointer(&raw_ptr()->url_, name.raw());
}

void Library::set_kernel_data(const TypedData& data) const {
  StorePointer(&raw_ptr()->kernel_data_, data.raw());
}

void Library::SetName(const String& name) const {
  // Only set name once.
  ASSERT(!Loaded());
  set_name(name);
}

void Library::SetLoadInProgress() const {
  // Must not already be in the process of being loaded.
  ASSERT(raw_ptr()->load_state_ <= RawLibrary::kLoadRequested);
  StoreNonPointer(&raw_ptr()->load_state_, RawLibrary::kLoadInProgress);
}

void Library::SetLoadRequested() const {
  // Must not be already loaded.
  ASSERT(raw_ptr()->load_state_ == RawLibrary::kAllocated);
  StoreNonPointer(&raw_ptr()->load_state_, RawLibrary::kLoadRequested);
}

void Library::SetLoaded() const {
  // Should not be already loaded or just allocated.
  ASSERT(LoadInProgress() || LoadRequested());
  StoreNonPointer(&raw_ptr()->load_state_, RawLibrary::kLoaded);
}

void Library::SetLoadError(const Instance& error) const {
  // Should not be already successfully loaded or just allocated.
  ASSERT(LoadInProgress() || LoadRequested() || LoadFailed());
  StoreNonPointer(&raw_ptr()->load_state_, RawLibrary::kLoadError);
  StorePointer(&raw_ptr()->load_error_, error.raw());
}

// Traits for looking up Libraries by url in a hash set.
class LibraryUrlTraits {
 public:
  static const char* Name() { return "LibraryUrlTraits"; }
  static bool ReportStats() { return false; }

  // Called when growing the table.
  static bool IsMatch(const Object& a, const Object& b) {
    ASSERT(a.IsLibrary() && b.IsLibrary());
    // Library objects are always canonical.
    return a.raw() == b.raw();
  }
  static uword Hash(const Object& key) { return Library::Cast(key).UrlHash(); }
};
typedef UnorderedHashSet<LibraryUrlTraits> LibraryLoadErrorSet;

RawInstance* Library::TransitiveLoadError() const {
  if (LoadError() != Instance::null()) {
    return LoadError();
  }
  Thread* thread = Thread::Current();
  Isolate* isolate = thread->isolate();
  Zone* zone = thread->zone();
  ObjectStore* object_store = isolate->object_store();
  LibraryLoadErrorSet set(object_store->library_load_error_table());
  bool present = false;
  if (set.GetOrNull(*this, &present) != Object::null()) {
    object_store->set_library_load_error_table(set.Release());
    return Instance::null();
  }
  // Ensure we don't repeatedly visit the same library again.
  set.Insert(*this);
  object_store->set_library_load_error_table(set.Release());
  intptr_t num_imp = num_imports();
  Library& lib = Library::Handle(zone);
  Instance& error = Instance::Handle(zone);
  for (intptr_t i = 0; i < num_imp; i++) {
    HANDLESCOPE(thread);
    lib = ImportLibraryAt(i);
    error = lib.TransitiveLoadError();
    if (!error.IsNull()) {
      break;
    }
  }
  return error.raw();
}

void Library::AddPatchClass(const Class& cls) const {
  ASSERT(Thread::Current()->IsMutatorThread());
  ASSERT(cls.is_patch());
  ASSERT(GetPatchClass(String::Handle(cls.Name())) == Class::null());
  const GrowableObjectArray& patch_classes =
      GrowableObjectArray::Handle(this->patch_classes());
  patch_classes.Add(cls);
}

RawClass* Library::GetPatchClass(const String& name) const {
  ASSERT(Thread::Current()->IsMutatorThread());
  const GrowableObjectArray& patch_classes =
      GrowableObjectArray::Handle(this->patch_classes());
  Object& obj = Object::Handle();
  for (intptr_t i = 0; i < patch_classes.Length(); i++) {
    obj = patch_classes.At(i);
    if (obj.IsClass() &&
        (Class::Cast(obj).Name() == name.raw())) {  // Names are canonicalized.
      return Class::RawCast(obj.raw());
    }
  }
  return Class::null();
}

void Library::RemovePatchClass(const Class& cls) const {
  ASSERT(Thread::Current()->IsMutatorThread());
  ASSERT(cls.is_patch());
  const GrowableObjectArray& patch_classes =
      GrowableObjectArray::Handle(this->patch_classes());
  const intptr_t num_classes = patch_classes.Length();
  intptr_t i = 0;
  while (i < num_classes) {
    if (cls.raw() == patch_classes.At(i)) break;
    i++;
  }
  if (i == num_classes) return;
  // Replace the entry with the script. We keep the script so that
  // Library::LoadedScripts() can find it without having to iterate
  // over the members of each class.
  ASSERT(i < num_classes);  // We must have found a class.
  const Script& patch_script = Script::Handle(cls.script());
  patch_classes.SetAt(i, patch_script);
}

static RawString* MakeClassMetaName(Thread* thread,
                                    Zone* zone,
                                    const Class& cls) {
  return Symbols::FromConcat(thread, Symbols::At(),
                             String::Handle(zone, cls.Name()));
}

static RawString* MakeFieldMetaName(Thread* thread,
                                    Zone* zone,
                                    const Field& field) {
  const String& cname = String::Handle(
      zone,
      MakeClassMetaName(thread, zone, Class::Handle(zone, field.Origin())));
  GrowableHandlePtrArray<const String> pieces(zone, 3);
  pieces.Add(cname);
  pieces.Add(Symbols::At());
  pieces.Add(String::Handle(field.name()));
  return Symbols::FromConcatAll(thread, pieces);
}

static RawString* MakeFunctionMetaName(Thread* thread,
                                       Zone* zone,
                                       const Function& func) {
  const String& cname = String::Handle(
      zone,
      MakeClassMetaName(thread, zone, Class::Handle(zone, func.origin())));
  GrowableHandlePtrArray<const String> pieces(zone, 3);
  pieces.Add(cname);
  pieces.Add(Symbols::At());
  pieces.Add(String::Handle(func.QualifiedScrubbedName()));
  return Symbols::FromConcatAll(thread, pieces);
}

static RawString* MakeTypeParameterMetaName(Thread* thread,
                                            Zone* zone,
                                            const TypeParameter& param) {
  const String& cname = String::Handle(
      zone,
      MakeClassMetaName(thread, zone,
                        Class::Handle(zone, param.parameterized_class())));
  GrowableHandlePtrArray<const String> pieces(zone, 3);
  pieces.Add(cname);
  pieces.Add(Symbols::At());
  pieces.Add(String::Handle(param.name()));
  return Symbols::FromConcatAll(thread, pieces);
}

void Library::AddMetadata(const Object& owner,
                          const String& name,
                          TokenPosition token_pos,
                          intptr_t kernel_offset) const {
  Thread* thread = Thread::Current();
  ASSERT(thread->IsMutatorThread());
  Zone* zone = thread->zone();
  const String& metaname = String::Handle(zone, Symbols::New(thread, name));
  const Field& field =
      Field::Handle(zone, Field::NewTopLevel(metaname,
                                             false,  // is_final
                                             false,  // is_const
                                             owner, token_pos, token_pos));
  field.SetFieldType(Object::dynamic_type());
  field.set_is_reflectable(false);
  field.SetStaticValue(Array::empty_array(), true);
  field.set_kernel_offset(kernel_offset);
  GrowableObjectArray& metadata =
      GrowableObjectArray::Handle(zone, this->metadata());
  metadata.Add(field, Heap::kOld);
}

void Library::AddClassMetadata(const Class& cls,
                               const Object& tl_owner,
                               TokenPosition token_pos,
                               intptr_t kernel_offset) const {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  // We use the toplevel class as the owner of a class's metadata field because
  // a class's metadata is in scope of the library, not the class.
  AddMetadata(tl_owner,
              String::Handle(zone, MakeClassMetaName(thread, zone, cls)),
              token_pos, kernel_offset);
}

void Library::AddFieldMetadata(const Field& field,
                               TokenPosition token_pos,
                               intptr_t kernel_offset) const {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  AddMetadata(Object::Handle(zone, field.RawOwner()),
              String::Handle(zone, MakeFieldMetaName(thread, zone, field)),
              token_pos, kernel_offset);
}

void Library::AddFunctionMetadata(const Function& func,
                                  TokenPosition token_pos,
                                  intptr_t kernel_offset) const {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  AddMetadata(Object::Handle(zone, func.RawOwner()),
              String::Handle(zone, MakeFunctionMetaName(thread, zone, func)),
              token_pos, kernel_offset);
}

void Library::AddTypeParameterMetadata(const TypeParameter& param,
                                       TokenPosition token_pos) const {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  AddMetadata(
      Class::Handle(zone, param.parameterized_class()),
      String::Handle(zone, MakeTypeParameterMetaName(thread, zone, param)),
      token_pos);
}

void Library::AddLibraryMetadata(const Object& tl_owner,
                                 TokenPosition token_pos) const {
  AddMetadata(tl_owner, Symbols::TopLevel(), token_pos);
}

RawString* Library::MakeMetadataName(const Object& obj) const {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  if (obj.IsClass()) {
    return MakeClassMetaName(thread, zone, Class::Cast(obj));
  } else if (obj.IsField()) {
    return MakeFieldMetaName(thread, zone, Field::Cast(obj));
  } else if (obj.IsFunction()) {
    return MakeFunctionMetaName(thread, zone, Function::Cast(obj));
  } else if (obj.IsLibrary()) {
    return Symbols::TopLevel().raw();
  } else if (obj.IsTypeParameter()) {
    return MakeTypeParameterMetaName(thread, zone, TypeParameter::Cast(obj));
  }
  UNIMPLEMENTED();
  return String::null();
}

RawField* Library::GetMetadataField(const String& metaname) const {
  ASSERT(Thread::Current()->IsMutatorThread());
  const GrowableObjectArray& metadata =
      GrowableObjectArray::Handle(this->metadata());
  Field& entry = Field::Handle();
  String& entryname = String::Handle();
  intptr_t num_entries = metadata.Length();
  for (intptr_t i = 0; i < num_entries; i++) {
    entry ^= metadata.At(i);
    entryname = entry.name();
    if (entryname.Equals(metaname)) {
      return entry.raw();
    }
  }
  return Field::null();
}

void Library::CloneMetadataFrom(const Library& from_library,
                                const Function& from_fun,
                                const Function& to_fun) const {
  const String& metaname = String::Handle(MakeMetadataName(from_fun));
  const Field& from_field =
      Field::Handle(from_library.GetMetadataField(metaname));
  if (!from_field.IsNull()) {
    AddFunctionMetadata(to_fun, from_field.token_pos(),
                        from_field.kernel_offset());
  }
}

RawObject* Library::GetMetadata(const Object& obj) const {
#if defined(DART_PRECOMPILED_RUNTIME)
  return Object::empty_array().raw();
#else
  if (!obj.IsClass() && !obj.IsField() && !obj.IsFunction() &&
      !obj.IsLibrary() && !obj.IsTypeParameter()) {
    return Object::null();
  }
  const String& metaname = String::Handle(MakeMetadataName(obj));
  Field& field = Field::Handle(GetMetadataField(metaname));
  if (field.IsNull()) {
    // There is no metadata for this object.
    return Object::empty_array().raw();
  }
  Object& metadata = Object::Handle();
  metadata = field.StaticValue();
  if (field.StaticValue() == Object::empty_array().raw()) {
    if (field.kernel_offset() > 0) {
      metadata = kernel::EvaluateMetadata(field);
    } else {
      metadata = Parser::ParseMetadata(field);
    }
    if (metadata.IsArray()) {
      ASSERT(Array::Cast(metadata).raw() != Object::empty_array().raw());
      field.SetStaticValue(Array::Cast(metadata), true);
    }
  }
  return metadata.raw();
#endif  // defined(DART_PRECOMPILED_RUNTIME)
}

static bool ShouldBePrivate(const String& name) {
  return (name.Length() >= 1 && name.CharAt(0) == '_') ||
         (name.Length() >= 5 &&
          (name.CharAt(4) == '_' &&
           (name.CharAt(0) == 'g' || name.CharAt(0) == 's') &&
           name.CharAt(1) == 'e' && name.CharAt(2) == 't' &&
           name.CharAt(3) == ':'));
}

RawObject* Library::ResolveName(const String& name) const {
  Object& obj = Object::Handle();
  if (FLAG_use_lib_cache && LookupResolvedNamesCache(name, &obj)) {
    return obj.raw();
  }
  obj = LookupLocalObject(name);
  if (!obj.IsNull()) {
    // Names that are in this library's dictionary and are unmangled
    // are not cached. This reduces the size of the cache.
    return obj.raw();
  }
  String& accessor_name = String::Handle(Field::LookupGetterSymbol(name));
  if (!accessor_name.IsNull()) {
    obj = LookupLocalObject(accessor_name);
  }
  if (obj.IsNull()) {
    accessor_name = Field::LookupSetterSymbol(name);
    if (!accessor_name.IsNull()) {
      obj = LookupLocalObject(accessor_name);
    }
    if (obj.IsNull() && !ShouldBePrivate(name)) {
      obj = LookupImportedObject(name);
    }
  }
  AddToResolvedNamesCache(name, obj);
  return obj.raw();
}

class StringEqualsTraits {
 public:
  static const char* Name() { return "StringEqualsTraits"; }
  static bool ReportStats() { return false; }

  static bool IsMatch(const Object& a, const Object& b) {
    return String::Cast(a).Equals(String::Cast(b));
  }
  static uword Hash(const Object& obj) { return String::Cast(obj).Hash(); }
};
typedef UnorderedHashMap<StringEqualsTraits> ResolvedNamesMap;

// Returns true if the name is found in the cache, false no cache hit.
// obj is set to the cached entry. It may be null, indicating that the
// name does not resolve to anything in this library.
bool Library::LookupResolvedNamesCache(const String& name, Object* obj) const {
  if (resolved_names() == Array::null()) {
    return false;
  }
  ResolvedNamesMap cache(resolved_names());
  bool present = false;
  *obj = cache.GetOrNull(name, &present);
// Mutator compiler thread may add entries and therefore
// change 'resolved_names()' while running a background compilation;
// ASSERT that 'resolved_names()' has not changed only in mutator.
#if defined(DEBUG)
  if (Thread::Current()->IsMutatorThread()) {
    ASSERT(cache.Release().raw() == resolved_names());
  } else {
    // Release must be called in debug mode.
    cache.Release();
  }
#endif
  return present;
}

// Add a name to the resolved name cache. This name resolves to the
// given object in this library scope. obj may be null, which means
// the name does not resolve to anything in this library scope.
void Library::AddToResolvedNamesCache(const String& name,
                                      const Object& obj) const {
  if (!FLAG_use_lib_cache || Compiler::IsBackgroundCompilation()) {
    return;
  }
  if (resolved_names() == Array::null()) {
    InitResolvedNamesCache();
  }
  ResolvedNamesMap cache(resolved_names());
  cache.UpdateOrInsert(name, obj);
  StorePointer(&raw_ptr()->resolved_names_, cache.Release().raw());
}

bool Library::LookupExportedNamesCache(const String& name, Object* obj) const {
  ASSERT(FLAG_use_exp_cache);
  if (exported_names() == Array::null()) {
    return false;
  }
  ResolvedNamesMap cache(exported_names());
  bool present = false;
  *obj = cache.GetOrNull(name, &present);
// Mutator compiler thread may add entries and therefore
// change 'exported_names()' while running a background compilation;
// do not ASSERT that 'exported_names()' has not changed.
#if defined(DEBUG)
  if (Thread::Current()->IsMutatorThread()) {
    ASSERT(cache.Release().raw() == exported_names());
  } else {
    // Release must be called in debug mode.
    cache.Release();
  }
#endif
  return present;
}

void Library::AddToExportedNamesCache(const String& name,
                                      const Object& obj) const {
  if (!FLAG_use_exp_cache || Compiler::IsBackgroundCompilation()) {
    return;
  }
  if (exported_names() == Array::null()) {
    InitExportedNamesCache();
  }
  ResolvedNamesMap cache(exported_names());
  cache.UpdateOrInsert(name, obj);
  StorePointer(&raw_ptr()->exported_names_, cache.Release().raw());
}

void Library::InvalidateResolvedName(const String& name) const {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  Object& entry = Object::Handle(zone);
  if (LookupResolvedNamesCache(name, &entry)) {
    // TODO(koda): Support deleted sentinel in snapshots and remove only 'name'.
    ClearResolvedNamesCache();
  }
  // When a new name is added to a library, we need to invalidate all
  // caches that contain an entry for this name. If the name was previously
  // looked up but could not be resolved, the cache contains a null entry.
  GrowableObjectArray& libs = GrowableObjectArray::Handle(
      zone, thread->isolate()->object_store()->libraries());
  Library& lib = Library::Handle(zone);
  intptr_t num_libs = libs.Length();
  for (intptr_t i = 0; i < num_libs; i++) {
    lib ^= libs.At(i);
    if (lib.LookupExportedNamesCache(name, &entry)) {
      lib.ClearExportedNamesCache();
    }
  }
}

// Invalidate all exported names caches in the isolate.
void Library::InvalidateExportedNamesCaches() {
  GrowableObjectArray& libs = GrowableObjectArray::Handle(
      Isolate::Current()->object_store()->libraries());
  Library& lib = Library::Handle();
  intptr_t num_libs = libs.Length();
  for (intptr_t i = 0; i < num_libs; i++) {
    lib ^= libs.At(i);
    lib.ClearExportedNamesCache();
  }
}

void Library::RehashDictionary(const Array& old_dict,
                               intptr_t new_dict_size) const {
  intptr_t old_dict_size = old_dict.Length() - 1;
  const Array& new_dict =
      Array::Handle(Array::New(new_dict_size + 1, Heap::kOld));
  // Rehash all elements from the original dictionary
  // to the newly allocated array.
  Object& entry = Class::Handle();
  String& entry_name = String::Handle();
  Object& new_entry = Object::Handle();
  intptr_t used = 0;
  for (intptr_t i = 0; i < old_dict_size; i++) {
    entry = old_dict.At(i);
    if (!entry.IsNull()) {
      entry_name = entry.DictionaryName();
      ASSERT(!entry_name.IsNull());
      const intptr_t hash = entry_name.Hash();
      intptr_t index = hash % new_dict_size;
      new_entry = new_dict.At(index);
      while (!new_entry.IsNull()) {
        index = (index + 1) % new_dict_size;  // Move to next element.
        new_entry = new_dict.At(index);
      }
      new_dict.SetAt(index, entry);
      used++;
    }
  }
  // Set used count.
  ASSERT(used < new_dict_size);  // Need at least one empty slot.
  new_entry = Smi::New(used);
  new_dict.SetAt(new_dict_size, new_entry);
  // Remember the new dictionary now.
  StorePointer(&raw_ptr()->dictionary_, new_dict.raw());
}

void Library::AddObject(const Object& obj, const String& name) const {
  ASSERT(Thread::Current()->IsMutatorThread());
  ASSERT(obj.IsClass() || obj.IsFunction() || obj.IsField() ||
         obj.IsLibraryPrefix());
  ASSERT(name.Equals(String::Handle(obj.DictionaryName())));
  ASSERT(LookupLocalObject(name) == Object::null());
  const Array& dict = Array::Handle(dictionary());
  intptr_t dict_size = dict.Length() - 1;
  intptr_t index = name.Hash() % dict_size;

  Object& entry = Object::Handle();
  entry = dict.At(index);
  // An empty spot will be found because we keep the hash set at most 75% full.
  while (!entry.IsNull()) {
    index = (index + 1) % dict_size;
    entry = dict.At(index);
  }

  // Insert the object at the empty slot.
  dict.SetAt(index, obj);
  // One more element added.
  intptr_t used_elements = Smi::Value(Smi::RawCast(dict.At(dict_size))) + 1;
  const Smi& used = Smi::Handle(Smi::New(used_elements));
  dict.SetAt(dict_size, used);  // Update used count.

  // Rehash if symbol_table is 75% full.
  if (used_elements > ((dict_size / 4) * 3)) {
    // TODO(iposva): Avoid exponential growth.
    RehashDictionary(dict, 2 * dict_size);
  }

  // Invalidate the cache of loaded scripts.
  if (loaded_scripts() != Array::null()) {
    StorePointer(&raw_ptr()->loaded_scripts_, Array::null());
  }
}

// Lookup a name in the library's re-export namespace.
// This lookup can occur from two different threads: background compiler and
// mutator thread.
RawObject* Library::LookupReExport(const String& name,
                                   ZoneGrowableArray<intptr_t>* trail) const {
  if (!HasExports()) {
    return Object::null();
  }

  if (trail == NULL) {
    trail = new ZoneGrowableArray<intptr_t>();
  }
  Object& obj = Object::Handle();
  if (FLAG_use_exp_cache && LookupExportedNamesCache(name, &obj)) {
    return obj.raw();
  }

  const intptr_t lib_id = this->index();
  ASSERT(lib_id >= 0);  // We use -1 to indicate that a cycle was found.
  trail->Add(lib_id);
  const Array& exports = Array::Handle(this->exports());
  Namespace& ns = Namespace::Handle();
  for (int i = 0; i < exports.Length(); i++) {
    ns ^= exports.At(i);
    obj = ns.Lookup(name, trail);
    if (!obj.IsNull()) {
      // The Lookup call above may return a setter x= when we are looking
      // for the name x. Make sure we only return when a matching name
      // is found.
      String& obj_name = String::Handle(obj.DictionaryName());
      if (Field::IsSetterName(obj_name) == Field::IsSetterName(name)) {
        break;
      }
    }
  }
  bool in_cycle = (trail->RemoveLast() < 0);
  if (FLAG_use_exp_cache && !in_cycle && !Compiler::IsBackgroundCompilation()) {
    AddToExportedNamesCache(name, obj);
  }
  return obj.raw();
}

RawObject* Library::LookupEntry(const String& name, intptr_t* index) const {
  Thread* thread = Thread::Current();
  REUSABLE_ARRAY_HANDLESCOPE(thread);
  REUSABLE_OBJECT_HANDLESCOPE(thread);
  REUSABLE_STRING_HANDLESCOPE(thread);
  Array& dict = thread->ArrayHandle();
  dict ^= dictionary();
  intptr_t dict_size = dict.Length() - 1;
  *index = name.Hash() % dict_size;
  Object& entry = thread->ObjectHandle();
  String& entry_name = thread->StringHandle();
  entry = dict.At(*index);
  // Search the entry in the hash set.
  while (!entry.IsNull()) {
    entry_name = entry.DictionaryName();
    ASSERT(!entry_name.IsNull());
    if (entry_name.Equals(name)) {
      return entry.raw();
    }
    *index = (*index + 1) % dict_size;
    entry = dict.At(*index);
  }
  return Object::null();
}

void Library::ReplaceObject(const Object& obj, const String& name) const {
  ASSERT(!Compiler::IsBackgroundCompilation());
  ASSERT(obj.IsClass() || obj.IsFunction() || obj.IsField());
  ASSERT(LookupLocalObject(name) != Object::null());

  intptr_t index;
  LookupEntry(name, &index);
  // The value is guaranteed to be found.
  const Array& dict = Array::Handle(dictionary());
  dict.SetAt(index, obj);
}

void Library::AddClass(const Class& cls) const {
  ASSERT(!Compiler::IsBackgroundCompilation());
  const String& class_name = String::Handle(cls.Name());
  AddObject(cls, class_name);
  // Link class to this library.
  cls.set_library(*this);
  InvalidateResolvedName(class_name);
}

static void AddScriptIfUnique(const GrowableObjectArray& scripts,
                              const Script& candidate) {
  if (candidate.IsNull()) {
    return;
  }
  Script& script_obj = Script::Handle();

  for (int i = 0; i < scripts.Length(); i++) {
    script_obj ^= scripts.At(i);
    if (script_obj.raw() == candidate.raw()) {
      // We already have a reference to this script.
      return;
    }
  }
  // Add script to the list of scripts.
  scripts.Add(candidate);
}

RawArray* Library::LoadedScripts() const {
  ASSERT(Thread::Current()->IsMutatorThread());
  // We compute the list of loaded scripts lazily. The result is
  // cached in loaded_scripts_.
  if (loaded_scripts() == Array::null()) {
    // Iterate over the library dictionary and collect all scripts.
    const GrowableObjectArray& scripts =
        GrowableObjectArray::Handle(GrowableObjectArray::New(8));
    Object& entry = Object::Handle();
    Class& cls = Class::Handle();
    Script& owner_script = Script::Handle();
    DictionaryIterator it(*this);
    while (it.HasNext()) {
      entry = it.GetNext();
      if (entry.IsClass()) {
        owner_script = Class::Cast(entry).script();
      } else if (entry.IsFunction()) {
        owner_script = Function::Cast(entry).script();
      } else if (entry.IsField()) {
        owner_script = Field::Cast(entry).Script();
      } else {
        continue;
      }
      AddScriptIfUnique(scripts, owner_script);
    }

    // Add all scripts from patch classes.
    GrowableObjectArray& patches = GrowableObjectArray::Handle(patch_classes());
    for (intptr_t i = 0; i < patches.Length(); i++) {
      entry = patches.At(i);
      if (entry.IsClass()) {
        owner_script = Class::Cast(entry).script();
      } else {
        ASSERT(entry.IsScript());
        owner_script = Script::Cast(entry).raw();
      }
      AddScriptIfUnique(scripts, owner_script);
    }

    cls ^= toplevel_class();
    if (!cls.IsNull()) {
      owner_script = cls.script();
      AddScriptIfUnique(scripts, owner_script);
      // Special case: Scripts that only contain external top-level functions
      // are not included above, but can be referenced through a library's
      // anonymous classes. Example: dart-core:identical.dart.
      Function& func = Function::Handle();
      Array& functions = Array::Handle(cls.functions());
      for (intptr_t j = 0; j < functions.Length(); j++) {
        func ^= functions.At(j);
        if (func.is_external()) {
          owner_script = func.script();
          AddScriptIfUnique(scripts, owner_script);
        }
      }
    }

    // Create the array of scripts and cache it in loaded_scripts_.
    const Array& scripts_array = Array::Handle(Array::MakeFixedLength(scripts));
    StorePointer(&raw_ptr()->loaded_scripts_, scripts_array.raw());
  }
  return loaded_scripts();
}

// TODO(hausner): we might want to add a script dictionary to the
// library class to make this lookup faster.
RawScript* Library::LookupScript(const String& url) const {
  const intptr_t url_length = url.Length();
  if (url_length == 0) {
    return Script::null();
  }
  const Array& scripts = Array::Handle(LoadedScripts());
  Script& script = Script::Handle();
  String& script_url = String::Handle();
  const intptr_t num_scripts = scripts.Length();
  for (int i = 0; i < num_scripts; i++) {
    script ^= scripts.At(i);
    script_url = script.url();
    const intptr_t start_idx = script_url.Length() - url_length;
    if ((start_idx == 0) && url.Equals(script_url)) {
      return script.raw();
    } else if (start_idx > 0) {
      // If we do a suffix match, only match if the partial path
      // starts at or immediately after the path separator.
      if (((url.CharAt(0) == '/') ||
           (script_url.CharAt(start_idx - 1) == '/')) &&
          url.Equals(script_url, start_idx, url_length)) {
        return script.raw();
      }
    }
  }
  return Script::null();
}

RawObject* Library::LookupLocalObject(const String& name) const {
  intptr_t index;
  return LookupEntry(name, &index);
}

RawField* Library::LookupFieldAllowPrivate(const String& name) const {
  Object& obj = Object::Handle(LookupObjectAllowPrivate(name));
  if (obj.IsField()) {
    return Field::Cast(obj).raw();
  }
  return Field::null();
}

RawField* Library::LookupLocalField(const String& name) const {
  Object& obj = Object::Handle(LookupLocalObjectAllowPrivate(name));
  if (obj.IsField()) {
    return Field::Cast(obj).raw();
  }
  return Field::null();
}

RawFunction* Library::LookupFunctionAllowPrivate(const String& name) const {
  Object& obj = Object::Handle(LookupObjectAllowPrivate(name));
  if (obj.IsFunction()) {
    return Function::Cast(obj).raw();
  }
  return Function::null();
}

RawFunction* Library::LookupLocalFunction(const String& name) const {
  Object& obj = Object::Handle(LookupLocalObjectAllowPrivate(name));
  if (obj.IsFunction()) {
    return Function::Cast(obj).raw();
  }
  return Function::null();
}

RawObject* Library::LookupLocalObjectAllowPrivate(const String& name) const {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  Object& obj = Object::Handle(zone, Object::null());
  obj = LookupLocalObject(name);
  if (obj.IsNull() && ShouldBePrivate(name)) {
    String& private_name = String::Handle(zone, PrivateName(name));
    obj = LookupLocalObject(private_name);
  }
  return obj.raw();
}

RawObject* Library::LookupObjectAllowPrivate(const String& name) const {
  // First check if name is found in the local scope of the library.
  Object& obj = Object::Handle(LookupLocalObjectAllowPrivate(name));
  if (!obj.IsNull()) {
    return obj.raw();
  }

  // Do not look up private names in imported libraries.
  if (ShouldBePrivate(name)) {
    return Object::null();
  }

  // Now check if name is found in any imported libs.
  return LookupImportedObject(name);
}

RawObject* Library::LookupImportedObject(const String& name) const {
  Object& obj = Object::Handle();
  Namespace& import = Namespace::Handle();
  Library& import_lib = Library::Handle();
  String& import_lib_url = String::Handle();
  String& first_import_lib_url = String::Handle();
  Object& found_obj = Object::Handle();
  String& found_obj_name = String::Handle();
  ASSERT(!ShouldBePrivate(name));
  for (intptr_t i = 0; i < num_imports(); i++) {
    import ^= ImportAt(i);
    obj = import.Lookup(name);
    if (!obj.IsNull()) {
      import_lib = import.library();
      import_lib_url = import_lib.url();
      if (found_obj.raw() != obj.raw()) {
        if (first_import_lib_url.IsNull() ||
            first_import_lib_url.StartsWith(Symbols::DartScheme())) {
          // This is the first object we found, or the
          // previously found object is exported from a Dart
          // system library. The newly found object hides the one
          // from the Dart library.
          first_import_lib_url = import_lib.url();
          found_obj = obj.raw();
          found_obj_name = obj.DictionaryName();
        } else if (import_lib_url.StartsWith(Symbols::DartScheme())) {
          // The newly found object is exported from a Dart system
          // library. It is hidden by the previously found object.
          // We continue to search.
        } else if (Field::IsSetterName(found_obj_name) &&
                   !Field::IsSetterName(name)) {
          // We are looking for an unmangled name or a getter, but
          // the first object we found is a setter. Replace the first
          // object with the one we just found.
          first_import_lib_url = import_lib.url();
          found_obj = obj.raw();
          found_obj_name = found_obj.DictionaryName();
        } else {
          // We found two different objects with the same name.
          // Note that we need to compare the names again because
          // looking up an unmangled name can return a getter or a
          // setter. A getter name is the same as the unmangled name,
          // but a setter name is different from an unmangled name or a
          // getter name.
          if (Field::IsGetterName(found_obj_name)) {
            found_obj_name = Field::NameFromGetter(found_obj_name);
          }
          String& second_obj_name = String::Handle(obj.DictionaryName());
          if (Field::IsGetterName(second_obj_name)) {
            second_obj_name = Field::NameFromGetter(second_obj_name);
          }
          if (found_obj_name.Equals(second_obj_name)) {
            return Object::null();
          }
        }
      }
    }
  }
  return found_obj.raw();
}

RawClass* Library::LookupClass(const String& name) const {
  Object& obj = Object::Handle(ResolveName(name));
  if (obj.IsClass()) {
    return Class::Cast(obj).raw();
  }
  return Class::null();
}

RawClass* Library::LookupLocalClass(const String& name) const {
  Object& obj = Object::Handle(LookupLocalObject(name));
  if (obj.IsClass()) {
    return Class::Cast(obj).raw();
  }
  return Class::null();
}

RawClass* Library::LookupClassAllowPrivate(const String& name) const {
  // See if the class is available in this library or in the top level
  // scope of any imported library.
  Zone* zone = Thread::Current()->zone();
  const Class& cls = Class::Handle(zone, LookupClass(name));
  if (!cls.IsNull()) {
    return cls.raw();
  }

  // Now try to lookup the class using its private name, but only in
  // this library (not in imported libraries).
  if (ShouldBePrivate(name)) {
    String& private_name = String::Handle(zone, PrivateName(name));
    const Object& obj = Object::Handle(LookupLocalObject(private_name));
    if (obj.IsClass()) {
      return Class::Cast(obj).raw();
    }
  }
  return Class::null();
}

// Mixin applications can have multiple private keys from different libraries.
RawClass* Library::SlowLookupClassAllowMultiPartPrivate(
    const String& name) const {
  Array& dict = Array::Handle(dictionary());
  Object& entry = Object::Handle();
  String& cls_name = String::Handle();
  for (intptr_t i = 0; i < dict.Length(); i++) {
    entry = dict.At(i);
    if (entry.IsClass()) {
      cls_name = Class::Cast(entry).Name();
      // Warning: comparison is not symmetric.
      if (String::EqualsIgnoringPrivateKey(cls_name, name)) {
        return Class::Cast(entry).raw();
      }
    }
  }
  return Class::null();
}

RawLibraryPrefix* Library::LookupLocalLibraryPrefix(const String& name) const {
  const Object& obj = Object::Handle(LookupLocalObject(name));
  if (obj.IsLibraryPrefix()) {
    return LibraryPrefix::Cast(obj).raw();
  }
  return LibraryPrefix::null();
}

void Library::set_toplevel_class(const Class& value) const {
  ASSERT(raw_ptr()->toplevel_class_ == Class::null());
  StorePointer(&raw_ptr()->toplevel_class_, value.raw());
}

void Library::set_metadata(const GrowableObjectArray& value) const {
  StorePointer(&raw_ptr()->metadata_, value.raw());
}

RawLibrary* Library::ImportLibraryAt(intptr_t index) const {
  Namespace& import = Namespace::Handle(ImportAt(index));
  if (import.IsNull()) {
    return Library::null();
  }
  return import.library();
}

RawNamespace* Library::ImportAt(intptr_t index) const {
  if ((index < 0) || index >= num_imports()) {
    return Namespace::null();
  }
  const Array& import_list = Array::Handle(imports());
  return Namespace::RawCast(import_list.At(index));
}

bool Library::ImportsCorelib() const {
  Zone* zone = Thread::Current()->zone();
  Library& imported = Library::Handle(zone);
  intptr_t count = num_imports();
  for (int i = 0; i < count; i++) {
    imported = ImportLibraryAt(i);
    if (imported.IsCoreLibrary()) {
      return true;
    }
  }
  LibraryPrefix& prefix = LibraryPrefix::Handle(zone);
  LibraryPrefixIterator it(*this);
  while (it.HasNext()) {
    prefix = it.GetNext();
    count = prefix.num_imports();
    for (int i = 0; i < count; i++) {
      imported = prefix.GetLibrary(i);
      if (imported.IsCoreLibrary()) {
        return true;
      }
    }
  }
  return false;
}

void Library::DropDependenciesAndCaches() const {
  StorePointer(&raw_ptr()->imports_, Object::empty_array().raw());
  StorePointer(&raw_ptr()->exports_, Object::empty_array().raw());
  StoreNonPointer(&raw_ptr()->num_imports_, 0);
  StorePointer(&raw_ptr()->resolved_names_, Array::null());
  StorePointer(&raw_ptr()->exported_names_, Array::null());
  StorePointer(&raw_ptr()->loaded_scripts_, Array::null());
}

void Library::AddImport(const Namespace& ns) const {
  Array& imports = Array::Handle(this->imports());
  intptr_t capacity = imports.Length();
  if (num_imports() == capacity) {
    capacity = capacity + kImportsCapacityIncrement + (capacity >> 2);
    imports = Array::Grow(imports, capacity);
    StorePointer(&raw_ptr()->imports_, imports.raw());
  }
  intptr_t index = num_imports();
  imports.SetAt(index, ns);
  set_num_imports(index + 1);
}

// Convenience function to determine whether the export list is
// non-empty.
bool Library::HasExports() const {
  return exports() != Object::empty_array().raw();
}

// We add one namespace at a time to the exports array and don't
// pre-allocate any unused capacity. The assumption is that
// re-exports are quite rare.
void Library::AddExport(const Namespace& ns) const {
  Array& exports = Array::Handle(this->exports());
  intptr_t num_exports = exports.Length();
  exports = Array::Grow(exports, num_exports + 1);
  StorePointer(&raw_ptr()->exports_, exports.raw());
  exports.SetAt(num_exports, ns);
}

static RawArray* NewDictionary(intptr_t initial_size) {
  const Array& dict = Array::Handle(Array::New(initial_size + 1, Heap::kOld));
  // The last element of the dictionary specifies the number of in use slots.
  dict.SetAt(initial_size, Smi::Handle(Smi::New(0)));
  return dict.raw();
}

void Library::InitResolvedNamesCache() const {
  ASSERT(Thread::Current()->IsMutatorThread());
  StorePointer(&raw_ptr()->resolved_names_,
               HashTables::New<ResolvedNamesMap>(64));
}

void Library::ClearResolvedNamesCache() const {
  ASSERT(Thread::Current()->IsMutatorThread());
  StorePointer(&raw_ptr()->resolved_names_, Array::null());
}

void Library::InitExportedNamesCache() const {
  StorePointer(&raw_ptr()->exported_names_,
               HashTables::New<ResolvedNamesMap>(16));
}

void Library::ClearExportedNamesCache() const {
  StorePointer(&raw_ptr()->exported_names_, Array::null());
}

void Library::InitClassDictionary() const {
  // TODO(iposva): Find reasonable initial size.
  const int kInitialElementCount = 16;
  StorePointer(&raw_ptr()->dictionary_, NewDictionary(kInitialElementCount));
}

void Library::InitImportList() const {
  const Array& imports =
      Array::Handle(Array::New(kInitialImportsCapacity, Heap::kOld));
  StorePointer(&raw_ptr()->imports_, imports.raw());
  StoreNonPointer(&raw_ptr()->num_imports_, 0);
}

RawLibrary* Library::New() {
  ASSERT(Object::library_class() != Class::null());
  RawObject* raw =
      Object::Allocate(Library::kClassId, Library::InstanceSize(), Heap::kOld);
  return reinterpret_cast<RawLibrary*>(raw);
}

RawLibrary* Library::NewLibraryHelper(const String& url, bool import_core_lib) {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  ASSERT(thread->IsMutatorThread());
  // Force the url to have a hash code.
  url.Hash();
  const bool dart_scheme = url.StartsWith(Symbols::DartScheme());
  const bool dart_private_scheme =
      dart_scheme && url.StartsWith(Symbols::DartSchemePrivate());
  const Library& result = Library::Handle(zone, Library::New());
  result.StorePointer(&result.raw_ptr()->name_, Symbols::Empty().raw());
  result.StorePointer(&result.raw_ptr()->url_, url.raw());
  result.StorePointer(&result.raw_ptr()->resolved_names_, Array::null());
  result.StorePointer(&result.raw_ptr()->exported_names_, Array::null());
  result.StorePointer(&result.raw_ptr()->dictionary_,
                      Object::empty_array().raw());
  result.StorePointer(&result.raw_ptr()->metadata_,
                      GrowableObjectArray::New(4, Heap::kOld));
  result.StorePointer(&result.raw_ptr()->toplevel_class_, Class::null());
  result.StorePointer(
      &result.raw_ptr()->patch_classes_,
      GrowableObjectArray::New(Object::empty_array(), Heap::kOld));
  result.StorePointer(&result.raw_ptr()->imports_, Object::empty_array().raw());
  result.StorePointer(&result.raw_ptr()->exports_, Object::empty_array().raw());
  result.StorePointer(&result.raw_ptr()->loaded_scripts_, Array::null());
  result.StorePointer(&result.raw_ptr()->load_error_, Instance::null());
  result.set_native_entry_resolver(NULL);
  result.set_native_entry_symbol_resolver(NULL);
  result.set_is_in_fullsnapshot(false);
  result.StoreNonPointer(&result.raw_ptr()->corelib_imported_, true);
  if (dart_private_scheme) {
    // Never debug dart:_ libraries.
    result.set_debuggable(false);
  } else if (dart_scheme) {
    // Only debug dart: libraries if we have been requested to show invisible
    // frames.
    result.set_debuggable(FLAG_show_invisible_frames);
  } else {
    // Default to debuggable for all other libraries.
    result.set_debuggable(true);
  }
  result.set_is_dart_scheme(dart_scheme);
  result.set_kernel_offset(-1);
  result.StoreNonPointer(&result.raw_ptr()->load_state_,
                         RawLibrary::kAllocated);
  result.StoreNonPointer(&result.raw_ptr()->index_, -1);
  result.InitClassDictionary();
  result.InitImportList();
  result.AllocatePrivateKey();
  if (import_core_lib) {
    const Library& core_lib = Library::Handle(zone, Library::CoreLibrary());
    ASSERT(!core_lib.IsNull());
    const Namespace& ns = Namespace::Handle(
        zone,
        Namespace::New(core_lib, Object::null_array(), Object::null_array()));
    result.AddImport(ns);
  }
  return result.raw();
}

RawLibrary* Library::New(const String& url) {
  return NewLibraryHelper(url, false);
}

void Library::InitCoreLibrary(Isolate* isolate) {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  const String& core_lib_url = Symbols::DartCore();
  const Library& core_lib =
      Library::Handle(zone, Library::NewLibraryHelper(core_lib_url, false));
  core_lib.SetLoadRequested();
  core_lib.Register(thread);
  isolate->object_store()->set_bootstrap_library(ObjectStore::kCore, core_lib);
  isolate->object_store()->set_root_library(Library::Handle());

  // Hook up predefined classes without setting their library pointers. These
  // classes are coming from the VM isolate, and are shared between multiple
  // isolates so setting their library pointers would be wrong.
  const Class& cls = Class::Handle(zone, Object::dynamic_class());
  core_lib.AddObject(cls, String::Handle(zone, cls.Name()));
}

RawObject* Library::Evaluate(const String& expr,
                             const Array& param_names,
                             const Array& param_values) const {
  // Evaluate the expression as a static function of the toplevel class.
  Class& top_level_class = Class::Handle(toplevel_class());
  ASSERT(top_level_class.is_finalized());
  return top_level_class.Evaluate(expr, param_names, param_values);
}

void Library::InitNativeWrappersLibrary(Isolate* isolate, bool is_kernel) {
  static const int kNumNativeWrappersClasses = 4;
  COMPILE_ASSERT((kNumNativeWrappersClasses > 0) &&
                 (kNumNativeWrappersClasses < 10));
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  const String& native_flds_lib_url = Symbols::DartNativeWrappers();
  const Library& native_flds_lib = Library::Handle(
      zone, Library::NewLibraryHelper(native_flds_lib_url, false));
  const String& native_flds_lib_name = Symbols::DartNativeWrappersLibName();
  native_flds_lib.SetName(native_flds_lib_name);
  native_flds_lib.SetLoadRequested();
  native_flds_lib.Register(thread);
  native_flds_lib.SetLoadInProgress();
  isolate->object_store()->set_native_wrappers_library(native_flds_lib);
  static const char* const kNativeWrappersClass = "NativeFieldWrapperClass";
  static const int kNameLength = 25;
  ASSERT(kNameLength == (strlen(kNativeWrappersClass) + 1 + 1));
  char name_buffer[kNameLength];
  String& cls_name = String::Handle(zone);
  for (int fld_cnt = 1; fld_cnt <= kNumNativeWrappersClasses; fld_cnt++) {
    Utils::SNPrint(name_buffer, kNameLength, "%s%d", kNativeWrappersClass,
                   fld_cnt);
    cls_name = Symbols::New(thread, name_buffer);
    Class::NewNativeWrapper(native_flds_lib, cls_name, fld_cnt);
  }
  // NOTE: If we bootstrap from a Kernel IR file we want to generate the
  // synthetic constructors for the native wrapper classes.  We leave this up to
  // the [KernelLoader] who will take care of it later.
  if (!is_kernel) {
    native_flds_lib.SetLoaded();
  }
}

// LibraryLookupSet maps URIs to libraries.
class LibraryLookupTraits {
 public:
  static const char* Name() { return "LibraryLookupTraits"; }
  static bool ReportStats() { return false; }

  static bool IsMatch(const Object& a, const Object& b) {
    const String& a_str = String::Cast(a);
    const String& b_str = String::Cast(b);

    ASSERT(a_str.HasHash() && b_str.HasHash());
    return a_str.Equals(b_str);
  }

  static uword Hash(const Object& key) { return String::Cast(key).Hash(); }

  static RawObject* NewKey(const String& str) { return str.raw(); }
};
typedef UnorderedHashMap<LibraryLookupTraits> LibraryLookupMap;

// Returns library with given url in current isolate, or NULL.
RawLibrary* Library::LookupLibrary(Thread* thread, const String& url) {
  Zone* zone = thread->zone();
  Isolate* isolate = thread->isolate();
  ObjectStore* object_store = isolate->object_store();

  // Make sure the URL string has an associated hash code
  // to speed up the repeated equality checks.
  url.Hash();

  // Use the libraries map to lookup the library by URL.
  Library& lib = Library::Handle(zone);
  if (object_store->libraries_map() == Array::null()) {
    return Library::null();
  } else {
    LibraryLookupMap map(object_store->libraries_map());
    lib ^= map.GetOrNull(url);
    ASSERT(map.Release().raw() == object_store->libraries_map());
  }
  return lib.raw();
}

RawError* Library::Patch(const Script& script) const {
  ASSERT(script.kind() == RawScript::kPatchTag);
  return Compiler::Compile(*this, script);
}

bool Library::IsPrivate(const String& name) {
  if (ShouldBePrivate(name)) return true;
  // Factory names: List._fromLiteral.
  for (intptr_t i = 1; i < name.Length() - 1; i++) {
    if (name.CharAt(i) == '.') {
      if (name.CharAt(i + 1) == '_') {
        return true;
      }
    }
  }
  return false;
}

// Create a private key for this library. It is based on the hash of the
// library URI and the sequence number of the library to guarantee unique
// private keys without having to verify.
void Library::AllocatePrivateKey() const {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  Isolate* isolate = thread->isolate();

#if !defined(PRODUCT) && !defined(DART_PRECOMPILED_RUNTIME)
  if (FLAG_support_reload && isolate->IsReloading()) {
    // When reloading, we need to make sure we use the original private key
    // if this library previously existed.
    IsolateReloadContext* reload_context = isolate->reload_context();
    const String& original_key =
        String::Handle(reload_context->FindLibraryPrivateKey(*this));
    if (!original_key.IsNull()) {
      StorePointer(&raw_ptr()->private_key_, original_key.raw());
      return;
    }
  }
#endif  // !defined(PRODUCT) && !defined(DART_PRECOMPILED_RUNTIME)

  // Format of the private key is: "@<sequence number><6 digits of hash>
  const intptr_t hash_mask = 0x7FFFF;

  const String& url = String::Handle(zone, this->url());
  intptr_t hash_value = url.Hash() & hash_mask;

  const GrowableObjectArray& libs =
      GrowableObjectArray::Handle(zone, isolate->object_store()->libraries());
  intptr_t sequence_value = libs.Length();

  char private_key[32];
  Utils::SNPrint(private_key, sizeof(private_key), "%c%" Pd "%06" Pd "",
                 kPrivateKeySeparator, sequence_value, hash_value);
  const String& key =
      String::Handle(zone, String::New(private_key, Heap::kOld));
  key.Hash();  // This string may end up in the VM isolate.
  StorePointer(&raw_ptr()->private_key_, key.raw());
}

const String& Library::PrivateCoreLibName(const String& member) {
  const Library& core_lib = Library::Handle(Library::CoreLibrary());
  const String& private_name = String::ZoneHandle(core_lib.PrivateName(member));
  return private_name;
}

RawClass* Library::LookupCoreClass(const String& class_name) {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  const Library& core_lib = Library::Handle(zone, Library::CoreLibrary());
  String& name = String::Handle(zone, class_name.raw());
  if (class_name.CharAt(0) == kPrivateIdentifierStart) {
    // Private identifiers are mangled on a per library basis.
    name = Symbols::FromConcat(thread, name,
                               String::Handle(zone, core_lib.private_key()));
  }
  return core_lib.LookupClass(name);
}

// Cannot handle qualified names properly as it only appends private key to
// the end (e.g. _Alfa.foo -> _Alfa.foo@...).
RawString* Library::PrivateName(const String& name) const {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  ASSERT(IsPrivate(name));
  // ASSERT(strchr(name, '@') == NULL);
  String& str = String::Handle(zone);
  str = name.raw();
  str = Symbols::FromConcat(thread, str,
                            String::Handle(zone, this->private_key()));
  return str.raw();
}

RawLibrary* Library::GetLibrary(intptr_t index) {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  Isolate* isolate = thread->isolate();
  const GrowableObjectArray& libs =
      GrowableObjectArray::Handle(zone, isolate->object_store()->libraries());
  ASSERT(!libs.IsNull());
  if ((0 <= index) && (index < libs.Length())) {
    Library& lib = Library::Handle(zone);
    lib ^= libs.At(index);
    return lib.raw();
  }
  return Library::null();
}

void Library::Register(Thread* thread) const {
  Zone* zone = thread->zone();
  Isolate* isolate = thread->isolate();
  ObjectStore* object_store = isolate->object_store();

  // A library is "registered" in two places:
  // - A growable array mapping from index to library.
  const String& lib_url = String::Handle(zone, url());
  ASSERT(Library::LookupLibrary(thread, lib_url) == Library::null());
  ASSERT(lib_url.HasHash());
  GrowableObjectArray& libs =
      GrowableObjectArray::Handle(zone, object_store->libraries());
  ASSERT(!libs.IsNull());
  set_index(libs.Length());
  libs.Add(*this);

  // - A map from URL string to library.
  if (object_store->libraries_map() == Array::null()) {
    LibraryLookupMap map(HashTables::New<LibraryLookupMap>(16, Heap::kOld));
    object_store->set_libraries_map(map.Release());
  }

  LibraryLookupMap map(object_store->libraries_map());
  bool present = map.UpdateOrInsert(lib_url, *this);
  ASSERT(!present);
  object_store->set_libraries_map(map.Release());
}

void Library::RegisterLibraries(Thread* thread,
                                const GrowableObjectArray& libs) {
  Zone* zone = thread->zone();
  Isolate* isolate = thread->isolate();
  Library& lib = Library::Handle(zone);
  String& lib_url = String::Handle(zone);

  LibraryLookupMap map(HashTables::New<LibraryLookupMap>(16, Heap::kOld));

  intptr_t len = libs.Length();
  for (intptr_t i = 0; i < len; i++) {
    lib ^= libs.At(i);
    lib_url = lib.url();
    map.InsertNewOrGetValue(lib_url, lib);
  }
  // Now remember these in the isolate's object store.
  isolate->object_store()->set_libraries(libs);
  isolate->object_store()->set_libraries_map(map.Release());
}

RawLibrary* Library::AsyncLibrary() {
  return Isolate::Current()->object_store()->async_library();
}

RawLibrary* Library::ConvertLibrary() {
  return Isolate::Current()->object_store()->convert_library();
}

RawLibrary* Library::CoreLibrary() {
  return Isolate::Current()->object_store()->core_library();
}

RawLibrary* Library::CollectionLibrary() {
  return Isolate::Current()->object_store()->collection_library();
}

RawLibrary* Library::DeveloperLibrary() {
  return Isolate::Current()->object_store()->developer_library();
}

RawLibrary* Library::InternalLibrary() {
  return Isolate::Current()->object_store()->_internal_library();
}

RawLibrary* Library::IsolateLibrary() {
  return Isolate::Current()->object_store()->isolate_library();
}

RawLibrary* Library::MathLibrary() {
  return Isolate::Current()->object_store()->math_library();
}

#if !defined(DART_PRECOMPILED_RUNTIME)
RawLibrary* Library::MirrorsLibrary() {
  return Isolate::Current()->object_store()->mirrors_library();
}
#endif

RawLibrary* Library::NativeWrappersLibrary() {
  return Isolate::Current()->object_store()->native_wrappers_library();
}

RawLibrary* Library::ProfilerLibrary() {
  return Isolate::Current()->object_store()->profiler_library();
}

RawLibrary* Library::TypedDataLibrary() {
  return Isolate::Current()->object_store()->typed_data_library();
}

RawLibrary* Library::VMServiceLibrary() {
  return Isolate::Current()->object_store()->_vmservice_library();
}

const char* Library::ToCString() const {
  const String& name = String::Handle(url());
  return OS::SCreate(Thread::Current()->zone(), "Library:'%s'",
                     name.ToCString());
}

RawLibrary* LibraryPrefix::GetLibrary(int index) const {
  if ((index >= 0) || (index < num_imports())) {
    const Array& imports = Array::Handle(this->imports());
    Namespace& import = Namespace::Handle();
    import ^= imports.At(index);
    return import.library();
  }
  return Library::null();
}

RawInstance* LibraryPrefix::LoadError() const {
  Thread* thread = Thread::Current();
  Isolate* isolate = thread->isolate();
  Zone* zone = thread->zone();
  ObjectStore* object_store = isolate->object_store();
  GrowableObjectArray& libs =
      GrowableObjectArray::Handle(zone, object_store->libraries());
  ASSERT(!libs.IsNull());
  LibraryLoadErrorSet set(HashTables::New<LibraryLoadErrorSet>(libs.Length()));
  object_store->set_library_load_error_table(set.Release());
  Library& lib = Library::Handle(zone);
  Instance& error = Instance::Handle(zone);
  for (int32_t i = 0; i < num_imports(); i++) {
    lib = GetLibrary(i);
    ASSERT(!lib.IsNull());
    HANDLESCOPE(thread);
    error = lib.TransitiveLoadError();
    if (!error.IsNull()) {
      break;
    }
  }
  object_store->set_library_load_error_table(Object::empty_array());
  return error.raw();
}

bool LibraryPrefix::ContainsLibrary(const Library& library) const {
  int32_t num_current_imports = num_imports();
  if (num_current_imports > 0) {
    Library& lib = Library::Handle();
    const String& url = String::Handle(library.url());
    String& lib_url = String::Handle();
    for (int32_t i = 0; i < num_current_imports; i++) {
      lib = GetLibrary(i);
      ASSERT(!lib.IsNull());
      lib_url = lib.url();
      if (url.Equals(lib_url)) {
        return true;
      }
    }
  }
  return false;
}

void LibraryPrefix::AddImport(const Namespace& import) const {
  intptr_t num_current_imports = num_imports();

  // Prefixes with deferred libraries can only contain one library.
  ASSERT((num_current_imports == 0) || !is_deferred_load());

  // The library needs to be added to the list.
  Array& imports = Array::Handle(this->imports());
  const intptr_t length = (imports.IsNull()) ? 0 : imports.Length();
  // Grow the list if it is full.
  if (num_current_imports >= length) {
    const intptr_t new_length = length + kIncrementSize + (length >> 2);
    imports = Array::Grow(imports, new_length, Heap::kOld);
    set_imports(imports);
  }
  imports.SetAt(num_current_imports, import);
  set_num_imports(num_current_imports + 1);
}

RawObject* LibraryPrefix::LookupObject(const String& name) const {
  if (!is_loaded() && !FLAG_load_deferred_eagerly) {
    return Object::null();
  }
  Array& imports = Array::Handle(this->imports());
  Object& obj = Object::Handle();
  Namespace& import = Namespace::Handle();
  Library& import_lib = Library::Handle();
  String& import_lib_url = String::Handle();
  String& first_import_lib_url = String::Handle();
  Object& found_obj = Object::Handle();
  String& found_obj_name = String::Handle();
  for (intptr_t i = 0; i < num_imports(); i++) {
    import ^= imports.At(i);
    obj = import.Lookup(name);
    if (!obj.IsNull()) {
      import_lib = import.library();
      import_lib_url = import_lib.url();
      if (found_obj.raw() != obj.raw()) {
        if (first_import_lib_url.IsNull() ||
            first_import_lib_url.StartsWith(Symbols::DartScheme())) {
          // This is the first object we found, or the
          // previously found object is exported from a Dart
          // system library. The newly found object hides the one
          // from the Dart library.
          first_import_lib_url = import_lib.url();
          found_obj = obj.raw();
          found_obj_name = found_obj.DictionaryName();
        } else if (import_lib_url.StartsWith(Symbols::DartScheme())) {
          // The newly found object is exported from a Dart system
          // library. It is hidden by the previously found object.
          // We continue to search.
        } else if (Field::IsSetterName(found_obj_name) &&
                   !Field::IsSetterName(name)) {
          // We are looking for an unmangled name or a getter, but
          // the first object we found is a setter. Replace the first
          // object with the one we just found.
          first_import_lib_url = import_lib.url();
          found_obj = obj.raw();
          found_obj_name = found_obj.DictionaryName();
        } else {
          // We found two different objects with the same name.
          // Note that we need to compare the names again because
          // looking up an unmangled name can return a getter or a
          // setter. A getter name is the same as the unmangled name,
          // but a setter name is different from an unmangled name or a
          // getter name.
          if (Field::IsGetterName(found_obj_name)) {
            found_obj_name = Field::NameFromGetter(found_obj_name);
          }
          String& second_obj_name = String::Handle(obj.DictionaryName());
          if (Field::IsGetterName(second_obj_name)) {
            second_obj_name = Field::NameFromGetter(second_obj_name);
          }
          if (found_obj_name.Equals(second_obj_name)) {
            return Object::null();
          }
        }
      }
    }
  }
  return found_obj.raw();
}

RawClass* LibraryPrefix::LookupClass(const String& class_name) const {
  const Object& obj = Object::Handle(LookupObject(class_name));
  if (obj.IsClass()) {
    return Class::Cast(obj).raw();
  }
  return Class::null();
}

void LibraryPrefix::set_is_loaded() const {
  StoreNonPointer(&raw_ptr()->is_loaded_, true);
}

bool LibraryPrefix::LoadLibrary() const {
  // Non-deferred prefixes are loaded.
  ASSERT(is_deferred_load() || is_loaded());
  if (is_loaded()) {
    return true;  // Load request has already completed.
  }
  ASSERT(is_deferred_load());
  ASSERT(num_imports() == 1);
  if (Dart::vm_snapshot_kind() == Snapshot::kFullAOT) {
    // The library list was tree-shaken away.
    this->set_is_loaded();
    return true;
  }
  // This is a prefix for a deferred library. If the library is not loaded
  // yet and isn't being loaded, call the library tag handler to schedule
  // loading. Once all outstanding load requests have completed, the embedder
  // will call the core library to:
  // - invalidate dependent code of this prefix;
  // - mark this prefixes as loaded;
  // - complete the future associated with this prefix.
  const Library& deferred_lib = Library::Handle(GetLibrary(0));
  if (deferred_lib.Loaded()) {
    this->set_is_loaded();
    return true;
  } else if (deferred_lib.LoadNotStarted()) {
    Thread* thread = Thread::Current();
    Isolate* isolate = thread->isolate();
    Zone* zone = thread->zone();
    deferred_lib.SetLoadRequested();
    const GrowableObjectArray& pending_deferred_loads =
        GrowableObjectArray::Handle(
            isolate->object_store()->pending_deferred_loads());
    pending_deferred_loads.Add(deferred_lib);
    const String& lib_url = String::Handle(zone, deferred_lib.url());
    Dart_LibraryTagHandler handler = isolate->library_tag_handler();
    Object& obj = Object::Handle(zone);
    {
      TransitionVMToNative transition(thread);
      Api::Scope api_scope(thread);
      obj = Api::UnwrapHandle(handler(Dart_kImportTag,
                                      Api::NewHandle(thread, importer()),
                                      Api::NewHandle(thread, lib_url.raw())));
    }
    if (obj.IsError()) {
      Exceptions::PropagateError(Error::Cast(obj));
    }
  } else {
    // Another load request is in flight or previously failed.
    ASSERT(deferred_lib.LoadRequested() || deferred_lib.LoadFailed());
  }
  return false;  // Load request not yet completed.
}

RawArray* LibraryPrefix::dependent_code() const {
  return raw_ptr()->dependent_code_;
}

void LibraryPrefix::set_dependent_code(const Array& array) const {
  StorePointer(&raw_ptr()->dependent_code_, array.raw());
}

class PrefixDependentArray : public WeakCodeReferences {
 public:
  explicit PrefixDependentArray(const LibraryPrefix& prefix)
      : WeakCodeReferences(Array::Handle(prefix.dependent_code())),
        prefix_(prefix) {}

  virtual void UpdateArrayTo(const Array& value) {
    prefix_.set_dependent_code(value);
  }

  virtual void ReportDeoptimization(const Code& code) {
    // This gets called when the code object is on the stack
    // while nuking code that depends on a prefix. We don't expect
    // this to happen, so make sure we die loudly if we find
    // ourselves here.
    UNIMPLEMENTED();
  }

  virtual void ReportSwitchingCode(const Code& code) {
    if (FLAG_trace_deoptimization || FLAG_trace_deoptimization_verbose) {
      THR_Print("Prefix '%s': disabling %s code for %s function '%s'\n",
                String::Handle(prefix_.name()).ToCString(),
                code.is_optimized() ? "optimized" : "unoptimized",
                code.IsDisabled() ? "'patched'" : "'unpatched'",
                Function::Handle(code.function()).ToCString());
    }
  }

 private:
  const LibraryPrefix& prefix_;
  DISALLOW_COPY_AND_ASSIGN(PrefixDependentArray);
};

void LibraryPrefix::RegisterDependentCode(const Code& code) const {
  ASSERT(is_deferred_load());
  // In background compilation, a library can be loaded while we are compiling.
  // The generated code will be rejected in that case,
  ASSERT(!is_loaded() || Compiler::IsBackgroundCompilation());
  PrefixDependentArray a(*this);
  a.Register(code);
}

void LibraryPrefix::InvalidateDependentCode() const {
  PrefixDependentArray a(*this);
  a.DisableCode();
  set_is_loaded();
}

RawLibraryPrefix* LibraryPrefix::New() {
  RawObject* raw = Object::Allocate(LibraryPrefix::kClassId,
                                    LibraryPrefix::InstanceSize(), Heap::kOld);
  return reinterpret_cast<RawLibraryPrefix*>(raw);
}

RawLibraryPrefix* LibraryPrefix::New(const String& name,
                                     const Namespace& import,
                                     bool deferred_load,
                                     const Library& importer) {
  const LibraryPrefix& result = LibraryPrefix::Handle(LibraryPrefix::New());
  result.set_name(name);
  result.set_num_imports(0);
  result.set_importer(importer);
  result.StoreNonPointer(&result.raw_ptr()->is_deferred_load_, deferred_load);
  result.StoreNonPointer(&result.raw_ptr()->is_loaded_, !deferred_load);
  result.set_imports(Array::Handle(Array::New(kInitialSize)));
  result.AddImport(import);
  return result.raw();
}

void LibraryPrefix::set_name(const String& value) const {
  ASSERT(value.IsSymbol());
  StorePointer(&raw_ptr()->name_, value.raw());
}

void LibraryPrefix::set_imports(const Array& value) const {
  StorePointer(&raw_ptr()->imports_, value.raw());
}

void LibraryPrefix::set_num_imports(intptr_t value) const {
  if (!Utils::IsUint(16, value)) {
    ReportTooManyImports(Library::Handle(importer()));
  }
  StoreNonPointer(&raw_ptr()->num_imports_, value);
}

void LibraryPrefix::set_importer(const Library& value) const {
  StorePointer(&raw_ptr()->importer_, value.raw());
}

const char* LibraryPrefix::ToCString() const {
  const String& prefix = String::Handle(name());
  return OS::SCreate(Thread::Current()->zone(), "LibraryPrefix:'%s'",
                     prefix.ToCString());
}

void Namespace::set_metadata_field(const Field& value) const {
  StorePointer(&raw_ptr()->metadata_field_, value.raw());
}

void Namespace::AddMetadata(const Object& owner, TokenPosition token_pos) {
  ASSERT(Field::Handle(metadata_field()).IsNull());
  Field& field = Field::Handle(Field::NewTopLevel(Symbols::TopLevel(),
                                                  false,  // is_final
                                                  false,  // is_const
                                                  owner, token_pos, token_pos));
  field.set_is_reflectable(false);
  field.SetFieldType(Object::dynamic_type());
  field.SetStaticValue(Array::empty_array(), true);
  set_metadata_field(field);
}

RawObject* Namespace::GetMetadata() const {
#if defined(DART_PRECOMPILED_RUNTIME)
  return Object::empty_array().raw();
#else
  Field& field = Field::Handle(metadata_field());
  if (field.IsNull()) {
    // There is no metadata for this object.
    return Object::empty_array().raw();
  }
  Object& metadata = Object::Handle();
  metadata = field.StaticValue();
  if (field.StaticValue() == Object::empty_array().raw()) {
    metadata = Parser::ParseMetadata(field);
    if (metadata.IsArray()) {
      ASSERT(Array::Cast(metadata).raw() != Object::empty_array().raw());
      field.SetStaticValue(Array::Cast(metadata), true);
    }
  }
  return metadata.raw();
#endif  // defined(DART_PRECOMPILED_RUNTIME)
}

const char* Namespace::ToCString() const {
  const Library& lib = Library::Handle(library());
  return OS::SCreate(Thread::Current()->zone(), "Namespace for library '%s'",
                     lib.ToCString());
}

bool Namespace::HidesName(const String& name) const {
  // Quick check for common case with no combinators.
  if (hide_names() == show_names()) {
    ASSERT(hide_names() == Array::null());
    return false;
  }
  const String* plain_name = &name;
  if (Field::IsGetterName(name)) {
    plain_name = &String::Handle(Field::NameFromGetter(name));
  } else if (Field::IsSetterName(name)) {
    plain_name = &String::Handle(Field::NameFromSetter(name));
  }
  // Check whether the name is in the list of explicitly hidden names.
  if (hide_names() != Array::null()) {
    const Array& names = Array::Handle(hide_names());
    String& hidden = String::Handle();
    intptr_t num_names = names.Length();
    for (intptr_t i = 0; i < num_names; i++) {
      hidden ^= names.At(i);
      if (plain_name->Equals(hidden)) {
        return true;
      }
    }
  }
  // The name is not explicitly hidden. Now check whether it is in the
  // list of explicitly visible names, if there is one.
  if (show_names() != Array::null()) {
    const Array& names = Array::Handle(show_names());
    String& shown = String::Handle();
    intptr_t num_names = names.Length();
    for (intptr_t i = 0; i < num_names; i++) {
      shown ^= names.At(i);
      if (plain_name->Equals(shown)) {
        return false;
      }
    }
    // There is a list of visible names. The name we're looking for is not
    // contained in the list, so it is hidden.
    return true;
  }
  // The name is not filtered out.
  return false;
}

// Look up object with given name in library and filter out hidden
// names. Also look up getters and setters.
RawObject* Namespace::Lookup(const String& name,
                             ZoneGrowableArray<intptr_t>* trail) const {
  Zone* zone = Thread::Current()->zone();
  const Library& lib = Library::Handle(zone, library());

  if (trail != NULL) {
    // Look for cycle in reexport graph.
    for (int i = 0; i < trail->length(); i++) {
      if (trail->At(i) == lib.index()) {
        for (int j = i + 1; j < trail->length(); j++) {
          (*trail)[j] = -1;
        }
        return Object::null();
      }
    }
  }

  intptr_t ignore = 0;
  // Lookup the name in the library's symbols.
  Object& obj = Object::Handle(zone, lib.LookupEntry(name, &ignore));
  if (!Field::IsGetterName(name) && !Field::IsSetterName(name) &&
      (obj.IsNull() || obj.IsLibraryPrefix())) {
    String& accessor_name = String::Handle(zone);
    accessor_name ^= Field::LookupGetterSymbol(name);
    if (!accessor_name.IsNull()) {
      obj = lib.LookupEntry(accessor_name, &ignore);
    }
    if (obj.IsNull()) {
      accessor_name ^= Field::LookupSetterSymbol(name);
      if (!accessor_name.IsNull()) {
        obj = lib.LookupEntry(accessor_name, &ignore);
      }
    }
  }

  // Library prefixes are not exported.
  if (obj.IsNull() || obj.IsLibraryPrefix()) {
    // Lookup in the re-exported symbols.
    obj = lib.LookupReExport(name, trail);
    if (obj.IsNull() && !Field::IsSetterName(name)) {
      // LookupReExport() only returns objects that match the given name.
      // If there is no field/func/getter, try finding a setter.
      const String& setter_name =
          String::Handle(zone, Field::LookupSetterSymbol(name));
      if (!setter_name.IsNull()) {
        obj = lib.LookupReExport(setter_name, trail);
      }
    }
  }
  if (obj.IsNull() || HidesName(name) || obj.IsLibraryPrefix()) {
    return Object::null();
  }
  return obj.raw();
}

RawNamespace* Namespace::New() {
  ASSERT(Object::namespace_class() != Class::null());
  RawObject* raw = Object::Allocate(Namespace::kClassId,
                                    Namespace::InstanceSize(), Heap::kOld);
  return reinterpret_cast<RawNamespace*>(raw);
}

RawNamespace* Namespace::New(const Library& library,
                             const Array& show_names,
                             const Array& hide_names) {
  ASSERT(show_names.IsNull() || (show_names.Length() > 0));
  ASSERT(hide_names.IsNull() || (hide_names.Length() > 0));
  const Namespace& result = Namespace::Handle(Namespace::New());
  result.StorePointer(&result.raw_ptr()->library_, library.raw());
  result.StorePointer(&result.raw_ptr()->show_names_, show_names.raw());
  result.StorePointer(&result.raw_ptr()->hide_names_, hide_names.raw());
  return result.raw();
}

RawKernelProgramInfo* KernelProgramInfo::New() {
  RawObject* raw =
      Object::Allocate(KernelProgramInfo::kClassId,
                       KernelProgramInfo::InstanceSize(), Heap::kOld);
  return reinterpret_cast<RawKernelProgramInfo*>(raw);
}

RawKernelProgramInfo* KernelProgramInfo::New(const TypedData& string_offsets,
                                             const TypedData& string_data,
                                             const TypedData& canonical_names,
                                             const TypedData& metadata_payloads,
                                             const TypedData& metadata_mappings,
                                             const Array& scripts) {
  const KernelProgramInfo& info =
      KernelProgramInfo::Handle(KernelProgramInfo::New());
  info.StorePointer(&info.raw_ptr()->string_offsets_, string_offsets.raw());
  info.StorePointer(&info.raw_ptr()->string_data_, string_data.raw());
  info.StorePointer(&info.raw_ptr()->canonical_names_, canonical_names.raw());
  info.StorePointer(&info.raw_ptr()->metadata_payloads_,
                    metadata_payloads.raw());
  info.StorePointer(&info.raw_ptr()->metadata_mappings_,
                    metadata_mappings.raw());
  info.StorePointer(&info.raw_ptr()->scripts_, scripts.raw());
  return info.raw();
}

const char* KernelProgramInfo::ToCString() const {
  return OS::SCreate(Thread::Current()->zone(), "[KernelProgramInfo]");
}

RawScript* KernelProgramInfo::ScriptAt(intptr_t index) const {
  const Array& all_scripts = Array::Handle(scripts());
  RawObject* script = all_scripts.At(index);
  return Script::RawCast(script);
}

void KernelProgramInfo::set_constants(const Array& constants) const {
  StorePointer(&raw_ptr()->constants_, constants.raw());
}

void KernelProgramInfo::set_potential_natives(
    const GrowableObjectArray& candidates) const {
  StorePointer(&raw_ptr()->potential_natives_, candidates.raw());
}

RawError* Library::CompileAll() {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  Error& error = Error::Handle(zone);
  const GrowableObjectArray& libs = GrowableObjectArray::Handle(
      Isolate::Current()->object_store()->libraries());
  Library& lib = Library::Handle(zone);
  Class& cls = Class::Handle(zone);
  for (int i = 0; i < libs.Length(); i++) {
    lib ^= libs.At(i);
    ClassDictionaryIterator it(lib, ClassDictionaryIterator::kIteratePrivate);
    while (it.HasNext()) {
      cls = it.GetNextClass();
      error = cls.EnsureIsFinalized(thread);
      if (!error.IsNull()) {
        return error.raw();
      }
      error = Compiler::CompileAllFunctions(cls);
      if (!error.IsNull()) {
        return error.raw();
      }
    }
  }

  // Inner functions get added to the closures array. As part of compilation
  // more closures can be added to the end of the array. Compile all the
  // closures until we have reached the end of the "worklist".
  Object& result = Object::Handle(zone);
  const GrowableObjectArray& closures = GrowableObjectArray::Handle(
      zone, Isolate::Current()->object_store()->closure_functions());
  Function& func = Function::Handle(zone);
  for (int i = 0; i < closures.Length(); i++) {
    func ^= closures.At(i);
    if (!func.HasCode()) {
      result = Compiler::CompileFunction(thread, func);
      if (result.IsError()) {
        return Error::Cast(result).raw();
      }
    }
  }
  return Error::null();
}

RawError* Library::ParseAll(Thread* thread) {
  Zone* zone = thread->zone();
  Error& error = Error::Handle(zone);
  Isolate* isolate = thread->isolate();
  const GrowableObjectArray& libs =
      GrowableObjectArray::Handle(isolate->object_store()->libraries());
  Library& lib = Library::Handle(zone);
  Class& cls = Class::Handle(zone);
  for (int i = 0; i < libs.Length(); i++) {
    lib ^= libs.At(i);
    ClassDictionaryIterator it(lib, ClassDictionaryIterator::kIteratePrivate);
    while (it.HasNext()) {
      cls = it.GetNextClass();
      error = cls.EnsureIsFinalized(thread);
      if (!error.IsNull()) {
        return error.raw();
      }
      error = Compiler::ParseAllFunctions(cls);
      if (!error.IsNull()) {
        return error.raw();
      }
    }
  }

  // Inner functions get added to the closures array. As part of compilation
  // more closures can be added to the end of the array. Compile all the
  // closures until we have reached the end of the "worklist".
  const GrowableObjectArray& closures = GrowableObjectArray::Handle(
      zone, Isolate::Current()->object_store()->closure_functions());
  Function& func = Function::Handle(zone);
  for (int i = 0; i < closures.Length(); i++) {
    func ^= closures.At(i);
    if (!func.HasCode()) {
      error = Compiler::ParseFunction(thread, func);
      if (!error.IsNull()) {
        return error.raw();
      }
      func.ClearICDataArray();
      func.ClearCode();
    }
  }
  return error.raw();
}

// Return Function::null() if function does not exist in libs.
RawFunction* Library::GetFunction(const GrowableArray<Library*>& libs,
                                  const char* class_name,
                                  const char* function_name) {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  Function& func = Function::Handle(zone);
  String& class_str = String::Handle(zone);
  String& func_str = String::Handle(zone);
  Class& cls = Class::Handle(zone);
  for (intptr_t l = 0; l < libs.length(); l++) {
    const Library& lib = *libs[l];
    if (strcmp(class_name, "::") == 0) {
      func_str = Symbols::New(thread, function_name);
      func = lib.LookupFunctionAllowPrivate(func_str);
    } else {
      class_str = String::New(class_name);
      cls = lib.LookupClassAllowPrivate(class_str);
      if (!cls.IsNull()) {
        func_str = String::New(function_name);
        if (function_name[0] == '.') {
          func_str = String::Concat(class_str, func_str);
        }
        func = cls.LookupFunctionAllowPrivate(func_str);
      }
    }
    if (!func.IsNull()) {
      return func.raw();
    }
  }
  return Function::null();
}

RawObject* Library::GetFunctionClosure(const String& name) const {
  Thread* thread = Thread::Current();
  Zone* zone = thread->zone();
  Function& func = Function::Handle(zone, LookupFunctionAllowPrivate(name));
  if (func.IsNull()) {
    // Check whether the function is reexported into the library.
    const Object& obj = Object::Handle(zone, LookupReExport(name));
    if (obj.IsFunction()) {
      func ^= obj.raw();
    } else {
      // Check if there is a getter of 'name', in which case invoke it
      // and return the result.
      const String& getter_name = String::Handle(zone, Field::GetterName(name));
      func = LookupFunctionAllowPrivate(getter_name);
      if (func.IsNull()) {
        return Closure::null();
      }
      // Invoke the getter and return the result.
      return DartEntry::InvokeFunction(func, Object::empty_array());
    }
  }
  func = func.ImplicitClosureFunction();
  return func.ImplicitStaticClosure();
}

#if defined(DART_NO_SNAPSHOT) && !defined(PRODUCT)
void Library::CheckFunctionFingerprints() {
  GrowableArray<Library*> all_libs;
  Function& func = Function::Handle();
  bool has_errors = false;

#define CHECK_FINGERPRINTS(class_name, function_name, dest, fp)                \
  func = GetFunction(all_libs, #class_name, #function_name);                   \
  if (func.IsNull()) {                                                         \
    has_errors = true;                                                         \
    OS::Print("Function not found %s.%s\n", #class_name, #function_name);      \
  } else {                                                                     \
    CHECK_FINGERPRINT3(func, class_name, function_name, dest, fp);             \
  }

#define CHECK_FINGERPRINTS2(class_name, function_name, dest, type, fp)         \
  CHECK_FINGERPRINTS(class_name, function_name, dest, fp)

  all_libs.Add(&Library::ZoneHandle(Library::CoreLibrary()));
  CORE_LIB_INTRINSIC_LIST(CHECK_FINGERPRINTS2);
  CORE_INTEGER_LIB_INTRINSIC_LIST(CHECK_FINGERPRINTS2);

  all_libs.Add(&Library::ZoneHandle(Library::MathLibrary()));
  all_libs.Add(&Library::ZoneHandle(Library::TypedDataLibrary()));
  all_libs.Add(&Library::ZoneHandle(Library::CollectionLibrary()));
  all_libs.Add(&Library::ZoneHandle(Library::InternalLibrary()));
  OTHER_RECOGNIZED_LIST(CHECK_FINGERPRINTS2);
  INLINE_WHITE_LIST(CHECK_FINGERPRINTS);
  INLINE_BLACK_LIST(CHECK_FINGERPRINTS);
  POLYMORPHIC_TARGET_LIST(CHECK_FINGERPRINTS);

  all_libs.Clear();
  all_libs.Add(&Library::ZoneHandle(Library::DeveloperLibrary()));
  DEVELOPER_LIB_INTRINSIC_LIST(CHECK_FINGERPRINTS2);

  all_libs.Clear();
  all_libs.Add(&Library::ZoneHandle(Library::MathLibrary()));
  MATH_LIB_INTRINSIC_LIST(CHECK_FINGERPRINTS2);

  all_libs.Clear();
  all_libs.Add(&Library::ZoneHandle(Library::TypedDataLibrary()));
  TYPED_DATA_LIB_INTRINSIC_LIST(CHECK_FINGERPRINTS2);

#undef CHECK_FINGERPRINTS
#undef CHECK_FINGERPRINTS2

#define CHECK_FACTORY_FINGERPRINTS(symbol, class_name, factory_name, cid, fp)  \
  func = GetFunction(all_libs, #class_name, #factory_name);                    \
  if (func.IsNull()) {                                                         \
    has_errors = true;                                                         \
    OS::Print("Function not found %s.%s\n", #class_name, #factory_name);       \
  } else {                                                                     \
    CHECK_FINGERPRINT2(func, symbol, cid, fp);                                 \
  }

  all_libs.Add(&Library::ZoneHandle(Library::CoreLibrary()));
  RECOGNIZED_LIST_FACTORY_LIST(CHECK_FACTORY_FINGERPRINTS);

#undef CHECK_FACTORY_FINGERPRINTS

  if (has_errors) {
    FATAL("Fingerprint mismatch.");
  }
}
#endif  // defined(DART_NO_SNAPSHOT) && !defined(PRODUCT).

RawInstructions* Instructions::New(intptr_t size, bool has_single_entry_point) {
  ASSERT(size >= 0);
  ASSERT(Object::instructions_class() != Class::null());
  if (size < 0 || size > kMaxElements) {
    // This should be caught before we reach here.
    FATAL1("Fatal error in Instructions::New: invalid size %" Pd "\n", size);
  }
  Instructions& result = Instructions::Handle();
  {
    uword aligned_size = Instructions::InstanceSize(size);
    RawObject* raw =
        Object::Allocate(Instructions::kClassId, aligned_size, Heap::kCode);
    NoSafepointScope no_safepoint;
    result ^= raw;
    result.SetSize(size);
    result.SetHasSingleEntryPoint(has_single_entry_point);
  }
  return result.raw();
}

const char* Instructions::ToCString() const {
  return "Instructions";
}

// Encode integer |value| in SLEB128 format and store into |data|.
static void EncodeSLEB128(GrowableArray<uint8_t>* data, intptr_t value) {
  bool is_last_part = false;
  while (!is_last_part) {
    uint8_t part = value & 0x7f;
    value >>= 7;
    if ((value == 0 && (part & 0x40) == 0) ||
        (value == static_cast<intptr_t>(-1) && (part & 0x40) != 0)) {
      is_last_part = true;
    } else {
      part |= 0x80;
    }
    data->Add(part);
  }
}

// Decode integer in SLEB128 format from |data| and update |byte_index|.
static intptr_t DecodeSLEB128(const uint8_t* data,
                              const intptr_t data_length,
                              intptr_t* byte_index) {
  ASSERT(*byte_index < data_length);
  uword shift = 0;
  intptr_t value = 0;
  uint8_t part = 0;
  do {
    part = data[(*byte_index)++];
    value |= static_cast<intptr_t>(part & 0x7f) << shift;
    shift += 7;
  } while ((part & 0x80) != 0);

  if ((shift < (sizeof(value) * 8)) && ((part & 0x40) != 0)) {
    value |= static_cast<intptr_t>(kUwordMax << shift);
  }
  return value;
}

// Encode integer in SLEB128 format.
void PcDescriptors::EncodeInteger(GrowableArray<uint8_t>* data,
                                  intptr_t value) {
  return EncodeSLEB128(data, value);
}

// Decode SLEB128 encoded integer. Update byte_index to the next integer.
intptr_t PcDescriptors::DecodeInteger(intptr_t* byte_index) const {
  NoSafepointScope no_safepoint;
  const uint8_t* data = raw_ptr()->data();
  return DecodeSLEB128(data, Length(), byte_index);
}

RawObjectPool* ObjectPool::New(intptr_t len) {
  ASSERT(Object::object_pool_class() != Class::null());
  if (len < 0 || len > kMaxElements) {
    // This should be caught before we reach here.
    FATAL1("Fatal error in ObjectPool::New: invalid length %" Pd "\n", len);
  }
  ObjectPool& result = ObjectPool::Handle();
  {
    uword size = ObjectPool::InstanceSize(len);
    RawObject* raw = Object::Allocate(ObjectPool::kClassId, size, Heap::kOld);
    NoSafepointScope no_safepoint;
    result ^= raw;
    result.SetLength(len);
    for (intptr_t i = 0; i < len; i++) {
      result.SetTypeAt(i, ObjectPool::kImmediate);
    }
  }

  return result.raw();
}

const char* ObjectPool::ToCString() const {
  Zone* zone = Thread::Current()->zone();
  return zone->PrintToString("ObjectPool len:%" Pd, Length());
}

void ObjectPool::DebugPrint() const {
  THR_Print("Object Pool: 0x%" Px "{\n", reinterpret_cast<uword>(raw()));
  for (intptr_t i = 0; i < Length(); i++) {
    intptr_t offset = OffsetFromIndex(i);
    THR_Print("  %" Pd " PP+0x%" Px ": ", i, offset);
    if (TypeAt(i) == kTaggedObject) {
      RawObject* obj = ObjectAt(i);
      THR_Print("0x%" Px " %s (obj)\n", reinterpret_cast<uword>(obj),
                Object::Handle(obj).ToCString());
    } else if (TypeAt(i) == kNativeFunction) {
      THR_Print("0x%" Px " (native function)\n", RawValueAt(i));
    } else if (TypeAt(i) == kNativeFunctionWrapper) {
      THR_Print("0x%" Px " (native function wrapper)\n", RawValueAt(i));
    } else {
      THR_Print("0x%" Px " (raw)\n", RawValueAt(i));
    }
  }
  THR_Print("}\n");
}

intptr_t PcDescriptors::Length() const {
  return raw_ptr()->length_;
}

void PcDescriptors::SetLength(intptr_t value) const {
  StoreNonPointer(&raw_ptr()->length_, value);
}

void PcDescriptors::CopyData(GrowableArray<uint8_t>* delta_encoded_data) {
  NoSafepointScope no_safepoint;
  uint8_t* data = UnsafeMutableNonPointer(&raw_ptr()->data()[0]);
  for (intptr_t i = 0; i < delta_encoded_data->length(); ++i) {
    data[i] = (*delta_encoded_data)[i];
  }
}

RawPcDescriptors* PcDescriptors::New(GrowableArray<uint8_t>* data) {
  ASSERT(Object::pc_descriptors_class() != Class::null());
  Thread* thread = Thread::Current();
  PcDescriptors& result = PcDescriptors::Handle(thread->zone());
  {
    uword size = PcDescriptors::InstanceSize(data->length());
    RawObject* raw =
        Object::Allocate(PcDescriptors::kClassId, size, Heap::kOld);
    INC_STAT(thread, total_code_size, size);
    INC_STAT(thread, pc_desc_size, size);
    NoSafepointScope no_safepoint;
    result ^= raw;
    result.SetLength(data->length());
    result.CopyData(data);
  }
  return result.raw();
}

RawPcDescriptors* PcDescriptors::New(intptr_t length) {
  ASSERT(Object::pc_descriptors_class() != Class::null());
  Thread* thread = Thread::Current();
  PcDescriptors& result = PcDescriptors::Handle(thread->zone());
  {
    uword size = PcDescriptors::InstanceSize(length);
    RawObject* raw =
        Object::Allocate(PcDescriptors::kClassId, size, Heap::kOld);
    INC_STAT(thread, total_code_size, size);
    INC_STAT(thread, pc_desc_size, size);
    NoSafepointScope no_safepoint;
    result ^= raw;
    result.SetLength(length);
  }
  return result.raw();
}

const char* PcDescriptors::KindAsStr(RawPcDescriptors::Kind kind) {
  switch (kind) {
    case RawPcDescriptors::kDeopt:
      return "deopt        ";
    case RawPcDescriptors::kIcCall:
      return "ic-call      ";
    case RawPcDescriptors::kUnoptStaticCall:
      return "unopt-call   ";
    case RawPcDescriptors::kRuntimeCall:
      return "runtime-call ";
    case RawPcDescriptors::kOsrEntry:
      return "osr-entry    ";
    case RawPcDescriptors::kRewind:
      return "rewind       ";
    case RawPcDescriptors::kOther:
      return "other        ";
    case RawPcDescriptors::kAnyKind:
      UNREACHABLE();
      break;
  }
  UNREACHABLE();
  return "";
}

void PcDescriptors::PrintHeaderString() {
  // 4 bits per hex digit + 2 for "0x".
  const int addr_width = (kBitsPerWord / 4) + 2;
  // "*" in a printf format specifier tells it to read the field width from
  // the printf argument list.
  THR_Print("%-*s\tkind    \tdeopt-id\ttok-ix\ttry-ix\n", addr_width, "pc");
}

const char* PcDescriptors::ToCString() const {
// "*" in a printf format specifier tells it to read the field width from
// the printf argument list.
#define FORMAT "%#-*" Px "\t%s\t%" Pd "\t\t%s\t%" Pd "\n"
  if (Length() == 0) {
    return "empty PcDescriptors\n";
  }
  // 4 bits per hex digit.
  const int addr_width = kBitsPerWord / 4;
  // First compute the buffer size required.
  intptr_t len = 1;  // Trailing '\0'.
  {
    Iterator iter(*this, RawPcDescriptors::kAnyKind);
    while (iter.MoveNext()) {
      len += Utils::SNPrint(NULL, 0, FORMAT, addr_width, iter.PcOffset(),
                            KindAsStr(iter.Kind()), iter.DeoptId(),
                            iter.TokenPos().ToCString(), iter.TryIndex());
    }
  }
  // Allocate the buffer.
  char* buffer = Thread::Current()->zone()->Alloc<char>(len);
  // Layout the fields in the buffer.
  intptr_t index = 0;
  Iterator iter(*this, RawPcDescriptors::kAnyKind);
  while (iter.MoveNext()) {
    index +=
        Utils::SNPrint((buffer + index), (len - index), FORMAT, addr_width,
                       iter.PcOffset(), KindAsStr(iter.Kind()), iter.DeoptId(),
                       iter.TokenPos().ToCString(), iter.TryIndex());
  }
  return buffer;
#undef FORMAT
}

// Verify assumptions (in debug mode only).
// - No two deopt descriptors have the same deoptimization id.
// - No two ic-call descriptors have the same deoptimization id (type feedback).
// A function without unique ids is marked as non-optimizable (e.g., because of
// finally blocks).
void PcDescriptors::Verify(const Function& function) const {
#if defined(DEBUG)
  // Only check ids for unoptimized code that is optimizable.
  if (!function.IsOptimizable()) {
    return;
  }
  intptr_t max_deopt_id = 0;
  Iterator max_iter(*this,
                    RawPcDescriptors::kDeopt | RawPcDescriptors::kIcCall);
  while (max_iter.MoveNext()) {
    if (max_iter.DeoptId() > max_deopt_id) {
      max_deopt_id = max_iter.DeoptId();
    }
  }

  Zone* zone = Thread::Current()->zone();
  BitVector* deopt_ids = new (zone) BitVector(zone, max_deopt_id + 1);
  BitVector* iccall_ids = new (zone) BitVector(zone, max_deopt_id + 1);
  Iterator iter(*this, RawPcDescriptors::kDeopt | RawPcDescriptors::kIcCall);
  while (iter.MoveNext()) {
    // 'deopt_id' is set for kDeopt and kIcCall and must be unique for one kind.
    if (Thread::IsDeoptAfter(iter.DeoptId())) {
      // TODO(vegorov): some instructions contain multiple calls and have
      // multiple "after" targets recorded. Right now it is benign but might
      // lead to issues in the future. Fix that and enable verification.
      continue;
    }
    if (iter.Kind() == RawPcDescriptors::kDeopt) {
      ASSERT(!deopt_ids->Contains(iter.DeoptId()));
      deopt_ids->Add(iter.DeoptId());
    } else {
      ASSERT(!iccall_ids->Contains(iter.DeoptId()));
      iccall_ids->Add(iter.DeoptId());
    }
  }
#endif  // DEBUG
}

void CodeSourceMap::SetLength(intptr_t value) const {
  StoreNonPointer(&raw_ptr()->length_, value);
}

RawCodeSourceMap* CodeSourceMap::New(intptr_t length) {
  ASSERT(Object::code_source_map_class() != Class::null());
  Thread* thread = Thread::Current();
  CodeSourceMap& result = CodeSourceMap::Handle(thread->zone());
  {
    uword size = CodeSourceMap::InstanceSize(length);
    RawObject* raw =
        Object::Allocate(CodeSourceMap::kClassId, size, Heap::kOld);
    NoSafepointScope no_safepoint;
    result ^= raw;
    result.SetLength(length);
  }
  return result.raw();
}

const char* CodeSourceMap::ToCString() const {
  return "CodeSourceMap";
}

bool StackMap::GetBit(intptr_t bit_index) const {
  ASSERT(InRange(bit_index));
  int byte_index = bit_index >> kBitsPerByteLog2;
  int bit_remainder = bit_index & (kBitsPerByte - 1);
  uint8_t byte_mask = 1U << bit_remainder;
  uint8_t byte = raw_ptr()->data()[byte_index];
  return (byte & byte_mask);
}

void StackMap::SetBit(intptr_t bit_index, bool value) const {
  ASSERT(InRange(bit_index));
  int byte_index = bit_index >> kBitsPerByteLog2;
  int bit_remainder = bit_index & (kBitsPerByte - 1);
  uint8_t byte_mask = 1U << bit_remainder;
  NoSafepointScope no_safepoint;
  uint8_t* byte_addr = UnsafeMutableNonPointer(&raw_ptr()->data()[byte_index]);
  if (value) {
    *byte_addr |= byte_mask;
  } else {
    *byte_addr &= ~byte_mask;
  }
}

RawStackMap* StackMap::New(intptr_t pc_offset,
                           BitmapBuilder* bmap,
                           intptr_t slow_path_bit_count) {
  ASSERT(Object::stackmap_class() != Class::null());
  ASSERT(bmap != NULL);
  StackMap& result = StackMap::Handle();
  // Guard against integer overflow of the instance size computation.
  intptr_t length = bmap->Length();
  intptr_t payload_size = Utils::RoundUp(length, kBitsPerByte) / kBitsPerByte;
  if ((length < 0) || (length > kMaxUint16) ||
      (payload_size > kMaxLengthInBytes)) {
    // This should be caught before we reach here.
    FATAL1("Fatal error in StackMap::New: invalid length %" Pd "\n", length);
  }
  if ((slow_path_bit_count < 0) || (slow_path_bit_count > kMaxUint16)) {
    // This should be caught before we reach here.
    FATAL1("Fatal error in StackMap::New: invalid slow_path_bit_count %" Pd
           "\n",
           slow_path_bit_count);
  }
  {
    // StackMap data objects are associated with a code object, allocate them
    // in old generation.
    RawObject* raw = Object::Allocate(
        StackMap::kClassId, StackMap::InstanceSize(length), Heap::kOld);
    NoSafepointScope no_safepoint;
    result ^= raw;
    result.SetLength(length);
  }
  ASSERT(pc_offset >= 0);
  result.SetPcOffset(pc_offset);
  for (intptr_t i = 0; i < length; ++i) {
    result.SetBit(i, bmap->Get(i));
  }
  result.SetSlowPathBitCount(slow_path_bit_count);
  return result.raw();
}

RawStackMap* StackMap::New(intptr_t length,
                           intptr_t slow_path_bit_count,
                           intptr_t pc_offset) {
  ASSERT(Object::stackmap_class() != Class::null());
  StackMap& result = StackMap::Handle();
  // Guard against integer overflow of the instance size computation.
  intptr_t payload_size = Utils::RoundUp(length, kBitsPerByte) / kBitsPerByte;
  if ((length < 0) || (length > kMaxUint16) ||
      (payload_size > kMaxLengthInBytes)) {
    // This should be caught before we reach here.
    FATAL1("Fatal error in StackMap::New: invalid length %" Pd "\n", length);
  }
  if ((slow_path_bit_count < 0) || (slow_path_bit_count > kMaxUint16)) {
    // This should be caught before we reach here.
    FATAL1("Fatal error in StackMap::New: invalid slow_path_bit_count %" Pd
           "\n",
           slow_path_bit_count);
  }

  {
    // StackMap data objects are associated with a code object, allocate them
    // in old generation.
    RawObject* raw = Object::Allocate(
        StackMap::kClassId, StackMap::InstanceSize(length), Heap::kOld);
    NoSafepointScope no_safepoint;
    result ^= raw;
    result.SetLength(length);
  }
  ASSERT(pc_offset >= 0);
  result.SetPcOffset(pc_offset);
  result.SetSlowPathBitCount(slow_path_bit_count);
  return result.raw();
}

const char* StackMap::ToCString() const {
#define FORMAT "%#05x: "
  if (IsNull()) {
    return "{null}";
  } else {
    intptr_t fixed_length = Utils::SNPrint(NULL, 0, FORMAT, PcOffset()) + 1;
    Thread* thread = Thread::Current();
    // Guard against integer overflow in the computation of alloc_size.
    //
    // TODO(kmillikin): We could just truncate the string if someone
    // tries to print a 2 billion plus entry stackmap.
    if (Length() > (kIntptrMax - fixed_length)) {
      FATAL1("Length() is unexpectedly large (%" Pd ")", Length());
    }
    intptr_t alloc_size = fixed_length + Length();
    char* chars = thread->zone()->Alloc<char>(alloc_size);
    intptr_t index = Utils::SNPrint(chars, alloc_size, FORMAT, PcOffset());
    for (intptr_t i = 0; i < Length(); i++) {
      chars[index++] = IsObject(i) ? '1' : '0';
    }
    chars[index] = '\0';
    return chars;
  }
#undef FORMAT
}

RawString* LocalVarDescriptors::GetName(intptr_t var_index) const {
  ASSERT(var_index < Length());
  ASSERT(Object::Handle(*raw()->nameAddrAt(var_index)).IsString());
  return *raw()->nameAddrAt(var_index);
}

void LocalVarDescriptors::SetVar(intptr_t var_index,
                                 const String& name,
                                 RawLocalVarDescriptors::VarInfo* info) const {
  ASSERT(var_index < Length());
  ASSERT(!name.IsNull());
  StorePointer(raw()->nameAddrAt(var_index), name.raw());
  raw()->data()[var_index] = *info;
}

void LocalVarDescriptors::GetInfo(intptr_t var_index,
                                  RawLocalVarDescriptors::VarInfo* info) const {
  ASSERT(var_index < Length());
  *info = raw()->data()[var_index];
}

static int PrintVarInfo(char* buffer,
                        int len,
                        intptr_t i,
                        const String& var_name,
                        const RawLocalVarDescriptors::VarInfo& info) {
  const RawLocalVarDescriptors::VarInfoKind kind = info.kind();
  const int32_t index = info.index();
  if (kind == RawLocalVarDescriptors::kContextLevel) {
    return Utils::SNPrint(buffer, len,
                          "%2" Pd
                          " %-13s level=%-3d"
                          " begin=%-3d end=%d\n",
                          i, LocalVarDescriptors::KindToCString(kind), index,
                          static_cast<int>(info.begin_pos.value()),
                          static_cast<int>(info.end_pos.value()));
  } else if (kind == RawLocalVarDescriptors::kContextVar) {
    return Utils::SNPrint(
        buffer, len,
        "%2" Pd
        " %-13s level=%-3d index=%-3d"
        " begin=%-3d end=%-3d name=%s\n",
        i, LocalVarDescriptors::KindToCString(kind), info.scope_id, index,
        static_cast<int>(info.begin_pos.Pos()),
        static_cast<int>(info.end_pos.Pos()), var_name.ToCString());
  } else {
    return Utils::SNPrint(
        buffer, len,
        "%2" Pd
        " %-13s scope=%-3d index=%-3d"
        " begin=%-3d end=%-3d name=%s\n",
        i, LocalVarDescriptors::KindToCString(kind), info.scope_id, index,
        static_cast<int>(info.begin_pos.Pos()),
        static_cast<int>(info.end_pos.Pos()), var_name.ToCString());
  }
}

const char* LocalVarDescriptors::ToCString() const {
  if (IsNull()) {
    return "LocalVarDescriptors: null";
  }
  if (Length() == 0) {
    return "empty LocalVarDescriptors";
  }
  intptr_t len = 1;  // Trailing '\0'.
  String& var_name = String::Handle();
  for (intptr_t i = 0; i < Length(); i++) {
    RawLocalVarDescriptors::VarInfo info;
    var_name = GetName(i);
    GetInfo(i, &info);
    len += PrintVarInfo(NULL, 0, i, var_name, info);
  }
  char* buffer = Thread::Current()->zone()->Alloc<char>(len + 1);
  buffer[0] = '\0';
  intptr_t num_chars = 0;
  for (intptr_t i = 0; i < Length(); i++) {
    RawLocalVarDescriptors::VarInfo info;
    var_name = GetName(i);
    GetInfo(i, &info);
    num_chars += PrintVarInfo((buffer + num_chars), (len - num_chars), i,
                              var_name, info);
  }
  return buffer;
}

const char* LocalVarDescriptors::KindToCString(
    RawLocalVarDescriptors::VarInfoKind kind) {
  switch (kind) {
    case RawLocalVarDescriptors::kStackVar:
      return "StackVar";
    case RawLocalVarDescriptors::kContextVar:
      return "ContextVar";
    case RawLocalVarDescriptors::kContextLevel:
      return "ContextLevel";
    case RawLocalVarDescriptors::kSavedCurrentContext:
      return "CurrentCtx";
    default:
      UNIMPLEMENTED();
      return NULL;
  }
}

RawLocalVarDescriptors* LocalVarDescriptors::New(intptr_t num_variables) {
  ASSERT(Object::var_descriptors_class() != Class::null());
  if (num_variables < 0 || num_variables > kMaxElements) {
    // This should be caught before we reach here.
    FATAL2(
        "Fatal error in LocalVarDescriptors::New: "
        "invalid num_variables %" Pd ". Maximum is: %d\n",
        num_variables, RawLocalVarDescriptors::kMaxIndex);
  }
  LocalVarDescriptors& result = LocalVarDescriptors::Handle();
  {
    uword size = LocalVarDescriptors::InstanceSize(num_variables);
    RawObject* raw =
        Object::Allocate(LocalVarDescriptors::kClassId, size, Heap::kOld);
    INC_STAT(Thread::Current(), total_code_size, size);
    INC_STAT(Thread::Current(), vardesc_size, size);
    NoSafepointScope no_safepoint;
    result ^= raw;
    result.StoreNonPointer(&result.raw_ptr()->num_entries_, num_variables);
  }
  return result.raw();
}

intptr_t LocalVarDescriptors::Length() const {
  return raw_ptr()->num_entries_;
}

intptr_t ExceptionHandlers::num_entries() const {
  return raw_ptr()->num_entries_;
}

void ExceptionHandlers::SetHandlerInfo(intptr_t try_index,
                                       intptr_t outer_try_index,
                                       uword handler_pc_offset,
                                       bool needs_stacktrace,
                                       bool has_catch_all,
                                       TokenPosition token_pos,
                                       bool is_generated) const {
  ASSERT((try_index >= 0) && (try_index < num_entries()));
  NoSafepointScope no_safepoint;
  ExceptionHandlerInfo* info =
      UnsafeMutableNonPointer(&raw_ptr()->data()[try_index]);
  info->outer_try_index = outer_try_index;
  // Some C compilers warn about the comparison always being true when using <=
  // due to limited range of data type.
  ASSERT((handler_pc_offset == static_cast<uword>(kMaxUint32)) ||
         (handler_pc_offset < static_cast<uword>(kMaxUint32)));
  info->handler_pc_offset = handler_pc_offset;
  info->needs_stacktrace = needs_stacktrace;
  info->has_catch_all = has_catch_all;
  info->is_generated = is_generated;
}

void ExceptionHandlers::GetHandlerInfo(intptr_t try_index,
                                       ExceptionHandlerInfo* info) const {
  ASSERT((try_index >= 0) && (try_index < num_entries()));
  ASSERT(info != NULL);
  *info = raw_ptr()->data()[try_index];
}

uword ExceptionHandlers::HandlerPCOffset(intptr_t try_index) const {
  ASSERT((try_index >= 0) && (try_index < num_entries()));
  return raw_ptr()->data()[try_index].handler_pc_offset;
}

intptr_t ExceptionHandlers::OuterTryIndex(intptr_t try_index) const {
  ASSERT((try_index >= 0) && (try_index < num_entries()));
  return raw_ptr()->data()[try_index].outer_try_index;
}

bool ExceptionHandlers::NeedsStackTrace(intptr_t try_index) const {
  ASSERT((try_index >= 0) && (try_index < num_entries()));
  return raw_ptr()->data()[try_index].needs_stacktrace;
}

bool ExceptionHandlers::IsGenerated(intptr_t try_index) const {
  ASSERT((try_index >= 0) && (try_index < num_entries()));
  return raw_ptr()->data()[try_index].is_generated;
}

bool ExceptionHandlers::HasCatchAll(intptr_t try_index) const {
  ASSERT((try_index >= 0) && (try_index < num_entries()));
  return raw_ptr()->data()[try_index].has_catch_all;
}

void ExceptionHandlers::SetHandledTypes(intptr_t try_index,
                                        const Array& handled_types) const {
  ASSERT((try_index >= 0) && (try_index < num_entries()));
  ASSERT(!handled_types.IsNull());
  const Array& handled_types_data =
      Array::Handle(raw_ptr()->handled_types_data_);
  handled_types_data.SetAt(try_index, handled_types);
}

RawArray* ExceptionHandlers::GetHandledTypes(intptr_t try_index) const {
  ASSERT((try_index >= 0) && (try_index < num_entries()));
  Array& array = Array::Handle(raw_ptr()->handled_types_data_);
  array ^= array.At(try_index);
  return array.raw();
}

void ExceptionHandlers::set_handled_types_data(const Array& value) const {
  StorePointer(&raw_ptr()->handled_types_data_, value.raw());
}

RawExceptionHandlers* ExceptionHandlers::New(intptr_t num_handlers) {
  ASSERT(Object::exception_handlers_class() != Class::null());
  if ((num_handlers < 0) || (num_handlers >= kMaxHandlers)) {
    FATAL1(
        "Fatal error in ExceptionHandlers::New(): "
        "invalid num_handlers %" Pd "\n",
        num_handlers);
  }
  ExceptionHandlers& result = ExceptionHandlers::Handle();
  {
    uword size = ExceptionHandlers::InstanceSize(num_handlers);
    RawObject* raw =
        Object::Allocate(ExceptionHandlers::kClassId, size, Heap::kOld);
    NoSafepointScope no_safepoint;
    result ^= raw;
    result.StoreNonPointer(&result.raw_ptr()->num_entries_, num_handlers);
  }
  const Array& handled_types_data =
      (num_handlers == 0) ? Object::empty_array()
                          : Array::Handle(Array::New(num_handlers, Heap::kOld));
  result.set_handled_types_data(handled_types_data);
  return result.raw();
}

RawExceptionHandlers* ExceptionHandlers::New(const Array& handled_types_data) {
  ASSERT(Object::exception_handlers_class() != Class::null());
  const intptr_t num_handlers = handled_types_data.Length();
  if ((num_handlers < 0) || (num_handlers >= kMaxHandlers)) {
    FATAL1(
        "Fatal error in ExceptionHandlers::New(): "
        "invalid num_handlers %" Pd "\n",
        num_handlers);
  }
  ExceptionHandlers& result = ExceptionHandlers::Handle();
  {
    uword size = ExceptionHandlers::InstanceSize(num_handlers);
    RawObject* raw =
        Object::Allocate(ExceptionHandlers::kClassId, size, Heap::kOld);
    NoSafepointScope no_safepoint;
    result ^= raw;
    result.StoreNonPointer(&result.raw_ptr()->num_entries_, num_handlers);
  }
  result.set_handled_types_data(handled_types_data);
  return result.raw();
}

const char* ExceptionHandlers::ToCString() const {
#define FORMAT1 "%" Pd " => %#x  (%" Pd " types) (outer %d) %s\n"
#define FORMAT2 "  %d. %s\n"
  if (num_entries() == 0) {
    return "empty ExceptionHandlers\n";
  }
  Array& handled_types = Array::Handle();
  Type& type = Type::Handle();
  ExceptionHandlerInfo info;
  // First compute the buffer size required.
  intptr_t len = 1;  // Trailing '\0'.
  for (intptr_t i = 0; i < num_entries(); i++) {
    GetHandlerInfo(i, &info);
    handled_types = GetHandledTypes(i);
    const intptr_t num_types =
        handled_types.IsNull() ? 0 : handled_types.Length();
    len += Utils::SNPrint(NULL, 0, FORMAT1, i, info.handler_pc_offset,
                          num_types, info.outer_try_index,
                          info.is_generated ? "(generated)" : "");
    for (int k = 0; k < num_types; k++) {
      type ^= handled_types.At(k);
      ASSERT(!type.IsNull());
      len += Utils::SNPrint(NULL, 0, FORMAT2, k, type.ToCString());
    }
  }
  // Allocate the buffer.
  char* buffer = Thread::Current()->zone()->Alloc<char>(len);
  // Layout the fields in the buffer.
  intptr_t num_chars = 0;
  for (intptr_t i = 0; i < num_entries(); i++) {
    GetHandlerInfo(i, &info);
    handled_types = GetHandledTypes(i);
    const intptr_t num_types =
        handled_types.IsNull() ? 0 : handled_types.Length();
    num_chars +=
        Utils::SNPrint((buffer + num_chars), (len - num_chars), FORMAT1, i,
                       info.handler_pc_offset, num_types, info.outer_try_index,
                       info.is_generated ? "(generated)" : "");
    for (int k = 0; k < num_types; k++) {
      type ^= handled_types.At(k);
      num_chars += Utils::SNPrint((buffer + num_chars), (len - num_chars),
                                  FORMAT2, k, type.ToCString());
    }
  }
  return buffer;
#undef FORMAT1
#undef FORMAT2
}

void SingleTargetCache::set_target(const Code& value) const {
  StorePointer(&raw_ptr()->target_, value.raw());
}

const char* SingleTargetCache::ToCString() const {
  return "SingleTargetCache";
}

RawSingleTargetCache* SingleTargetCache::New() {
  SingleTargetCache& result = SingleTargetCache::Handle();
  {
    // IC data objects are long living objects, allocate them in old generation.
    RawObject* raw =
        Object::Allocate(SingleTargetCache::kClassId,
                         SingleTargetCache::InstanceSize(), Heap::kOld);
    NoSafepointScope no_safepoint;
    result ^= raw;
  }
  result.set_target(Code::Handle());
  result.set_entry_point(0);
  result.set_lower_limit(kIllegalCid);
  result.set_upper_limit(kIllegalCid);
  return result.raw();
}

void UnlinkedCall::set_target_name(const String& value) const {
  StorePointer(&raw_ptr()->target_name_, value.raw());
}

void UnlinkedCall::set_args_descriptor(const Array& value) const {
  StorePointer(&raw_ptr()->args_descriptor_, value.raw());
}

const char* UnlinkedCall::ToCString() const {
  return "UnlinkedCall";
}

RawUnlinkedCall* UnlinkedCall::New() {
  RawObject* raw = Object::Allocate(UnlinkedCall::kClassId,
                                    UnlinkedCall::InstanceSize(), Heap::kOld);
  return reinterpret_cast<RawUnlinkedCall*>(raw);
}

void ICData::ResetSwitchable(Zone* zone) const {
  ASSERT(NumArgsTested() == 1);
  set_ic_data_array(Array::Handle(zone, CachedEmptyICDataArray(1)));
}

const char* ICData::ToCString() const {
  const String& name = String::Handle(target_name());
  const intptr_t num_args = NumArgsTested();
  const intptr_t num_checks = NumberOfChecks();
  const intptr_t type_args_len = TypeArgsLen();
  return