v8/test/cctest/test-unboxed-doubles.cc

// Copyright 2014 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <stdlib.h>
#include <utility>

#include "src/v8.h"

#include "src/compilation-cache.h"
#include "src/execution.h"
#include "src/factory.h"
#include "src/global-handles.h"
#include "src/ic/ic.h"
#include "src/macro-assembler.h"
#include "test/cctest/cctest.h"

using namespace v8::base;
using namespace v8::internal;

#if (V8_DOUBLE_FIELDS_UNBOXING)


//
// Helper functions.
//


static void InitializeVerifiedMapDescriptors(
    Map* map, DescriptorArray* descriptors,
    LayoutDescriptor* layout_descriptor) {
  map->InitializeDescriptors(descriptors, layout_descriptor);
#ifdef VERIFY_HEAP
  if (FLAG_verify_heap) {
    DCHECK(layout_descriptor->IsConsistentWithMap(map));
  }
#endif
}


static Handle<String> MakeString(const char* str) {
  Isolate* isolate = CcTest::i_isolate();
  Factory* factory = isolate->factory();
  return factory->InternalizeUtf8String(str);
}


static Handle<String> MakeName(const char* str, int suffix) {
  EmbeddedVector<char, 128> buffer;
  SNPrintF(buffer, "%s%d", str, suffix);
  return MakeString(buffer.start());
}


static double GetDoubleFieldValue(JSObject* obj, FieldIndex field_index) {
  if (obj->IsUnboxedDoubleField(field_index)) {
    return obj->RawFastDoublePropertyAt(field_index);
  } else {
    Object* value = obj->RawFastPropertyAt(field_index);
    DCHECK(value->IsMutableHeapNumber());
    return HeapNumber::cast(value)->value();
  }
}

const int kNumberOfBits = 32;


enum TestPropertyKind {
  PROP_CONSTANT,
  PROP_SMI,
  PROP_DOUBLE,
  PROP_TAGGED,
  PROP_KIND_NUMBER
};

static Representation representations[PROP_KIND_NUMBER] = {
    Representation::None(), Representation::Smi(), Representation::Double(),
    Representation::Tagged()};


static Handle<DescriptorArray> CreateDescriptorArray(Isolate* isolate,
                                                     TestPropertyKind* props,
                                                     int kPropsCount) {
  Factory* factory = isolate->factory();

  Handle<String> func_name = factory->InternalizeUtf8String("func");
  Handle<JSFunction> func = factory->NewFunction(func_name);

  Handle<DescriptorArray> descriptors =
      DescriptorArray::Allocate(isolate, 0, kPropsCount);

  int next_field_offset = 0;
  for (int i = 0; i < kPropsCount; i++) {
    EmbeddedVector<char, 64> buffer;
    SNPrintF(buffer, "prop%d", i);
    Handle<String> name = factory->InternalizeUtf8String(buffer.start());

    TestPropertyKind kind = props[i];

    if (kind == PROP_CONSTANT) {
      DataConstantDescriptor d(name, func, NONE);
      descriptors->Append(&d);

    } else {
      DataDescriptor f(name, next_field_offset, NONE, representations[kind]);
      next_field_offset += f.GetDetails().field_width_in_words();
      descriptors->Append(&f);
    }
  }
  return descriptors;
}


TEST(LayoutDescriptorBasicFast) {
  CcTest::InitializeVM();
  v8::HandleScope scope(CcTest::isolate());

  LayoutDescriptor* layout_desc = LayoutDescriptor::FastPointerLayout();

  CHECK(!layout_desc->IsSlowLayout());
  CHECK(layout_desc->IsFastPointerLayout());
  CHECK_EQ(kSmiValueSize, layout_desc->capacity());

  for (int i = 0; i < kSmiValueSize + 13; i++) {
    CHECK_EQ(true, layout_desc->IsTagged(i));
  }
  CHECK_EQ(true, layout_desc->IsTagged(-1));
  CHECK_EQ(true, layout_desc->IsTagged(-12347));
  CHECK_EQ(true, layout_desc->IsTagged(15635));
  CHECK(layout_desc->IsFastPointerLayout());

  for (int i = 0; i < kSmiValueSize; i++) {
    layout_desc = layout_desc->SetTaggedForTesting(i, false);
    CHECK_EQ(false, layout_desc->IsTagged(i));
    layout_desc = layout_desc->SetTaggedForTesting(i, true);
    CHECK_EQ(true, layout_desc->IsTagged(i));
  }
  CHECK(layout_desc->IsFastPointerLayout());

  int sequence_length;
  CHECK_EQ(true, layout_desc->IsTagged(0, std::numeric_limits<int>::max(),
                                       &sequence_length));
  CHECK_EQ(std::numeric_limits<int>::max(), sequence_length);

  CHECK_EQ(true, layout_desc->IsTagged(0, 7, &sequence_length));
  CHECK_EQ(7, sequence_length);
}


TEST(LayoutDescriptorBasicSlow) {
  CcTest::InitializeVM();
  Isolate* isolate = CcTest::i_isolate();
  v8::HandleScope scope(CcTest::isolate());

  Handle<LayoutDescriptor> layout_descriptor;
  const int kPropsCount = kSmiValueSize * 3;
  TestPropertyKind props[kPropsCount];
  for (int i = 0; i < kPropsCount; i++) {
    // All properties tagged.
    props[i] = PROP_TAGGED;
  }

  {
    Handle<DescriptorArray> descriptors =
        CreateDescriptorArray(isolate, props, kPropsCount);

    Handle<Map> map = Map::Create(isolate, kPropsCount);

    layout_descriptor = LayoutDescriptor::New(map, descriptors, kPropsCount);
    CHECK_EQ(LayoutDescriptor::FastPointerLayout(), *layout_descriptor);
    CHECK_EQ(kSmiValueSize, layout_descriptor->capacity());
    InitializeVerifiedMapDescriptors(*map, *descriptors, *layout_descriptor);
  }

  props[0] = PROP_DOUBLE;
  props[kPropsCount - 1] = PROP_DOUBLE;

  Handle<DescriptorArray> descriptors =
      CreateDescriptorArray(isolate, props, kPropsCount);

  {
    int inobject_properties = kPropsCount - 1;
    Handle<Map> map = Map::Create(isolate, inobject_properties);

    // Should be fast as the only double property is the first one.
    layout_descriptor = LayoutDescriptor::New(map, descriptors, kPropsCount);
    CHECK_NE(LayoutDescriptor::FastPointerLayout(), *layout_descriptor);
    CHECK(!layout_descriptor->IsSlowLayout());
    CHECK(!layout_descriptor->IsFastPointerLayout());

    CHECK_EQ(false, layout_descriptor->IsTagged(0));
    for (int i = 1; i < kPropsCount; i++) {
      CHECK_EQ(true, layout_descriptor->IsTagged(i));
    }
    InitializeVerifiedMapDescriptors(*map, *descriptors, *layout_descriptor);
  }

  {
    int inobject_properties = kPropsCount;
    Handle<Map> map = Map::Create(isolate, inobject_properties);

    layout_descriptor = LayoutDescriptor::New(map, descriptors, kPropsCount);
    CHECK_NE(LayoutDescriptor::FastPointerLayout(), *layout_descriptor);
    CHECK(layout_descriptor->IsSlowLayout());
    CHECK(!layout_descriptor->IsFastPointerLayout());
    CHECK(layout_descriptor->capacity() > kSmiValueSize);

    CHECK_EQ(false, layout_descriptor->IsTagged(0));
    CHECK_EQ(false, layout_descriptor->IsTagged(kPropsCount - 1));
    for (int i = 1; i < kPropsCount - 1; i++) {
      CHECK_EQ(true, layout_descriptor->IsTagged(i));
    }

    InitializeVerifiedMapDescriptors(*map, *descriptors, *layout_descriptor);

    // Here we have truly slow layout descriptor, so play with the bits.
    CHECK_EQ(true, layout_descriptor->IsTagged(-1));
    CHECK_EQ(true, layout_descriptor->IsTagged(-12347));
    CHECK_EQ(true, layout_descriptor->IsTagged(15635));

    LayoutDescriptor* layout_desc = *layout_descriptor;
    // Play with the bits but leave it in consistent state with map at the end.
    for (int i = 1; i < kPropsCount - 1; i++) {
      layout_desc = layout_desc->SetTaggedForTesting(i, false);
      CHECK_EQ(false, layout_desc->IsTagged(i));
      layout_desc = layout_desc->SetTaggedForTesting(i, true);
      CHECK_EQ(true, layout_desc->IsTagged(i));
    }
    CHECK(layout_desc->IsSlowLayout());
    CHECK(!layout_desc->IsFastPointerLayout());
#ifdef VERIFY_HEAP
    if (FLAG_verify_heap) {
      DCHECK(layout_descriptor->IsConsistentWithMap(*map));
    }
#endif
  }
}


static void TestLayoutDescriptorQueries(int layout_descriptor_length,
                                        int* bit_flip_positions,
                                        int max_sequence_length) {
  Handle<LayoutDescriptor> layout_descriptor = LayoutDescriptor::NewForTesting(
      CcTest::i_isolate(), layout_descriptor_length);
  layout_descriptor_length = layout_descriptor->capacity();
  LayoutDescriptor* layout_desc = *layout_descriptor;

  {
    // Fill in the layout descriptor.
    int cur_bit_flip_index = 0;
    bool tagged = true;
    for (int i = 0; i < layout_descriptor_length; i++) {
      if (i == bit_flip_positions[cur_bit_flip_index]) {
        tagged = !tagged;
        ++cur_bit_flip_index;
        CHECK(i < bit_flip_positions[cur_bit_flip_index]);  // check test data
      }
      layout_desc = layout_desc->SetTaggedForTesting(i, tagged);
    }
  }

  if (layout_desc->IsFastPointerLayout()) {
    return;
  }

  {
    // Check queries.
    int cur_bit_flip_index = 0;
    bool tagged = true;
    for (int i = 0; i < layout_descriptor_length; i++) {
      if (i == bit_flip_positions[cur_bit_flip_index]) {
        tagged = !tagged;
        ++cur_bit_flip_index;
      }
      CHECK_EQ(tagged, layout_desc->IsTagged(i));

      int next_bit_flip_position = bit_flip_positions[cur_bit_flip_index];
      int expected_sequence_length;
      if (next_bit_flip_position < layout_desc->capacity()) {
        expected_sequence_length = next_bit_flip_position - i;
      } else {
        expected_sequence_length = tagged ? std::numeric_limits<int>::max()
                                          : (layout_desc->capacity() - i);
      }
      expected_sequence_length =
          Min(expected_sequence_length, max_sequence_length);
      int sequence_length;
      CHECK_EQ(tagged,
               layout_desc->IsTagged(i, max_sequence_length, &sequence_length));
      CHECK(sequence_length > 0);

      CHECK_EQ(expected_sequence_length, sequence_length);
    }

    int sequence_length;
    CHECK_EQ(true,
             layout_desc->IsTagged(layout_descriptor_length,
                                   max_sequence_length, &sequence_length));
    CHECK_EQ(max_sequence_length, sequence_length);
  }
}


static void TestLayoutDescriptorQueriesFast(int max_sequence_length) {
  {
    LayoutDescriptor* layout_desc = LayoutDescriptor::FastPointerLayout();
    int sequence_length;
    for (int i = 0; i < kNumberOfBits; i++) {
      CHECK_EQ(true,
               layout_desc->IsTagged(i, max_sequence_length, &sequence_length));
      CHECK(sequence_length > 0);
      CHECK_EQ(max_sequence_length, sequence_length);
    }
  }

  {
    int bit_flip_positions[] = {1000};
    TestLayoutDescriptorQueries(kSmiValueSize, bit_flip_positions,
                                max_sequence_length);
  }

  {
    int bit_flip_positions[] = {0, 1000};
    TestLayoutDescriptorQueries(kSmiValueSize, bit_flip_positions,
                                max_sequence_length);
  }

  {
    int bit_flip_positions[kNumberOfBits + 1];
    for (int i = 0; i <= kNumberOfBits; i++) {
      bit_flip_positions[i] = i;
    }
    TestLayoutDescriptorQueries(kSmiValueSize, bit_flip_positions,
                                max_sequence_length);
  }

  {
    int bit_flip_positions[] = {3, 7, 8, 10, 15, 21, 30, 1000};
    TestLayoutDescriptorQueries(kSmiValueSize, bit_flip_positions,
                                max_sequence_length);
  }

  {
    int bit_flip_positions[] = {0,  1,  2,  3,  5,  7,  9,
                                12, 15, 18, 22, 26, 29, 1000};
    TestLayoutDescriptorQueries(kSmiValueSize, bit_flip_positions,
                                max_sequence_length);
  }
}


TEST(LayoutDescriptorQueriesFastLimited7) {
  CcTest::InitializeVM();
  v8::HandleScope scope(CcTest::isolate());

  TestLayoutDescriptorQueriesFast(7);
}


TEST(LayoutDescriptorQueriesFastLimited13) {
  CcTest::InitializeVM();
  v8::HandleScope scope(CcTest::isolate());

  TestLayoutDescriptorQueriesFast(13);
}


TEST(LayoutDescriptorQueriesFastUnlimited) {
  CcTest::InitializeVM();
  v8::HandleScope scope(CcTest::isolate());

  TestLayoutDescriptorQueriesFast(std::numeric_limits<int>::max());
}


static void TestLayoutDescriptorQueriesSlow(int max_sequence_length) {
  {
    int bit_flip_positions[] = {10000};
    TestLayoutDescriptorQueries(kMaxNumberOfDescriptors, bit_flip_positions,
                                max_sequence_length);
  }

  {
    int bit_flip_positions[] = {0, 10000};
    TestLayoutDescriptorQueries(kMaxNumberOfDescriptors, bit_flip_positions,
                                max_sequence_length);
  }

  {
    int bit_flip_positions[kMaxNumberOfDescriptors + 1];
    for (int i = 0; i < kMaxNumberOfDescriptors; i++) {
      bit_flip_positions[i] = i;
    }
    bit_flip_positions[kMaxNumberOfDescriptors] = 10000;
    TestLayoutDescriptorQueries(kMaxNumberOfDescriptors, bit_flip_positions,
                                max_sequence_length);
  }

  {
    int bit_flip_positions[] = {3,  7,  8,  10, 15,  21,   30,
                                37, 54, 80, 99, 383, 10000};
    TestLayoutDescriptorQueries(kMaxNumberOfDescriptors, bit_flip_positions,
                                max_sequence_length);
  }

  {
    int bit_flip_positions[] = {0,   10,  20,  30,  50,  70,  90,
                                120, 150, 180, 220, 260, 290, 10000};
    TestLayoutDescriptorQueries(kMaxNumberOfDescriptors, bit_flip_positions,
                                max_sequence_length);
  }

  {
    int bit_flip_positions[kMaxNumberOfDescriptors + 1];
    int cur = 0;
    for (int i = 0; i < kMaxNumberOfDescriptors; i++) {
      bit_flip_positions[i] = cur;
      cur = (cur + 1) * 2;
    }
    CHECK(cur < 10000);
    bit_flip_positions[kMaxNumberOfDescriptors] = 10000;
    TestLayoutDescriptorQueries(kMaxNumberOfDescriptors, bit_flip_positions,
                                max_sequence_length);
  }

  {
    int bit_flip_positions[kMaxNumberOfDescriptors + 1];
    int cur = 3;
    for (int i = 0; i < kMaxNumberOfDescriptors; i++) {
      bit_flip_positions[i] = cur;
      cur = (cur + 1) * 2;
    }
    CHECK(cur < 10000);
    bit_flip_positions[kMaxNumberOfDescriptors] = 10000;
    TestLayoutDescriptorQueries(kMaxNumberOfDescriptors, bit_flip_positions,
                                max_sequence_length);
  }
}


TEST(LayoutDescriptorQueriesSlowLimited7) {
  CcTest::InitializeVM();
  v8::HandleScope scope(CcTest::isolate());

  TestLayoutDescriptorQueriesSlow(7);
}


TEST(LayoutDescriptorQueriesSlowLimited13) {
  CcTest::InitializeVM();
  v8::HandleScope scope(CcTest::isolate());

  TestLayoutDescriptorQueriesSlow(13);
}


TEST(LayoutDescriptorQueriesSlowLimited42) {
  CcTest::InitializeVM();
  v8::HandleScope scope(CcTest::isolate());

  TestLayoutDescriptorQueriesSlow(42);
}


TEST(LayoutDescriptorQueriesSlowUnlimited) {
  CcTest::InitializeVM();
  v8::HandleScope scope(CcTest::isolate());

  TestLayoutDescriptorQueriesSlow(std::numeric_limits<int>::max());
}


TEST(LayoutDescriptorCreateNewFast) {
  CcTest::InitializeVM();
  Isolate* isolate = CcTest::i_isolate();
  v8::HandleScope scope(CcTest::isolate());

  Handle<LayoutDescriptor> layout_descriptor;
  TestPropertyKind props[] = {
      PROP_CONSTANT,
      PROP_TAGGED,  // field #0
      PROP_CONSTANT,
      PROP_DOUBLE,  // field #1
      PROP_CONSTANT,
      PROP_TAGGED,  // field #2
      PROP_CONSTANT,
  };
  const int kPropsCount = arraysize(props);

  Handle<DescriptorArray> descriptors =
      CreateDescriptorArray(isolate, props, kPropsCount);

  {
    Handle<Map> map = Map::Create(isolate, 0);
    layout_descriptor = LayoutDescriptor::New(map, descriptors, kPropsCount);
    CHECK_EQ(LayoutDescriptor::FastPointerLayout(), *layout_descriptor);
    InitializeVerifiedMapDescriptors(*map, *descriptors, *layout_descriptor);
  }

  {
    Handle<Map> map = Map::Create(isolate, 1);
    layout_descriptor = LayoutDescriptor::New(map, descriptors, kPropsCount);
    CHECK_EQ(LayoutDescriptor::FastPointerLayout(), *layout_descriptor);
    InitializeVerifiedMapDescriptors(*map, *descriptors, *layout_descriptor);
  }

  {
    Handle<Map> map = Map::Create(isolate, 2);
    layout_descriptor = LayoutDescriptor::New(map, descriptors, kPropsCount);
    CHECK_NE(LayoutDescriptor::FastPointerLayout(), *layout_descriptor);
    CHECK(!layout_descriptor->IsSlowLayout());
    CHECK_EQ(true, layout_descriptor->IsTagged(0));
    CHECK_EQ(false, layout_descriptor->IsTagged(1));
    CHECK_EQ(true, layout_descriptor->IsTagged(2));
    CHECK_EQ(true, layout_descriptor->IsTagged(125));
    InitializeVerifiedMapDescriptors(*map, *descriptors, *layout_descriptor);
  }
}


TEST(LayoutDescriptorCreateNewSlow) {
  CcTest::InitializeVM();
  Isolate* isolate = CcTest::i_isolate();
  v8::HandleScope scope(CcTest::isolate());

  Handle<LayoutDescriptor> layout_descriptor;
  const int kPropsCount = kSmiValueSize * 3;
  TestPropertyKind props[kPropsCount];
  for (int i = 0; i < kPropsCount; i++) {
    props[i] = static_cast<TestPropertyKind>(i % PROP_KIND_NUMBER);
  }

  Handle<DescriptorArray> descriptors =
      CreateDescriptorArray(isolate, props, kPropsCount);

  {
    Handle<Map> map = Map::Create(isolate, 0);
    layout_descriptor = LayoutDescriptor::New(map, descriptors, kPropsCount);
    CHECK_EQ(LayoutDescriptor::FastPointerLayout(), *layout_descriptor);
    InitializeVerifiedMapDescriptors(*map, *descriptors, *layout_descriptor);
  }

  {
    Handle<Map> map = Map::Create(isolate, 1);
    layout_descriptor = LayoutDescriptor::New(map, descriptors, kPropsCount);
    CHECK_EQ(LayoutDescriptor::FastPointerLayout(), *layout_descriptor);
    InitializeVerifiedMapDescriptors(*map, *descriptors, *layout_descriptor);
  }

  {
    Handle<Map> map = Map::Create(isolate, 2);
    layout_descriptor = LayoutDescriptor::New(map, descriptors, kPropsCount);
    CHECK_NE(LayoutDescriptor::FastPointerLayout(), *layout_descriptor);
    CHECK(!layout_descriptor->IsSlowLayout());
    CHECK_EQ(true, layout_descriptor->IsTagged(0));
    CHECK_EQ(false, layout_descriptor->IsTagged(1));
    CHECK_EQ(true, layout_descriptor->IsTagged(2));
    CHECK_EQ(true, layout_descriptor->IsTagged(125));
    InitializeVerifiedMapDescriptors(*map, *descriptors, *layout_descriptor);
  }

  {
    int inobject_properties = kPropsCount / 2;
    Handle<Map> map = Map::Create(isolate, inobject_properties);
    layout_descriptor = LayoutDescriptor::New(map, descriptors, kPropsCount);
    CHECK_NE(LayoutDescriptor::FastPointerLayout(), *layout_descriptor);
    CHECK(layout_descriptor->IsSlowLayout());
    for (int i = 0; i < inobject_properties; i++) {
      // PROP_DOUBLE has index 1 among DATA properties.
      const bool tagged = (i % (PROP_KIND_NUMBER - 1)) != 1;
      CHECK_EQ(tagged, layout_descriptor->IsTagged(i));
    }
    // Every property after inobject_properties must be tagged.
    for (int i = inobject_properties; i < kPropsCount; i++) {
      CHECK_EQ(true, layout_descriptor->IsTagged(i));
    }
    InitializeVerifiedMapDescriptors(*map, *descriptors, *layout_descriptor);

    // Now test LayoutDescriptor::cast_gc_safe().
    Handle<LayoutDescriptor> layout_descriptor_copy =
        LayoutDescriptor::New(map, descriptors, kPropsCount);

    LayoutDescriptor* layout_desc = *layout_descriptor;
    CHECK_EQ(layout_desc, LayoutDescriptor::cast(layout_desc));
    CHECK_EQ(layout_desc, LayoutDescriptor::cast_gc_safe(layout_desc));
    CHECK(layout_descriptor->IsFixedTypedArrayBase());
    // Now make it look like a forwarding pointer to layout_descriptor_copy.
    MapWord map_word = layout_desc->map_word();
    CHECK(!map_word.IsForwardingAddress());
    layout_desc->set_map_word(
        MapWord::FromForwardingAddress(*layout_descriptor_copy));
    CHECK(layout_desc->map_word().IsForwardingAddress());
    CHECK_EQ(*layout_descriptor_copy,
             LayoutDescriptor::cast_gc_safe(layout_desc));

    // Restore it back.
    layout_desc->set_map_word(map_word);
    CHECK_EQ(layout_desc, LayoutDescriptor::cast(layout_desc));
  }
}


static Handle<LayoutDescriptor> TestLayoutDescriptorAppend(
    Isolate* isolate, int inobject_properties, TestPropertyKind* props,
    int kPropsCount) {
  Factory* factory = isolate->factory();

  Handle<String> func_name = factory->InternalizeUtf8String("func");
  Handle<JSFunction> func = factory->NewFunction(func_name);

  Handle<DescriptorArray> descriptors =
      DescriptorArray::Allocate(isolate, 0, kPropsCount);

  Handle<Map> map = Map::Create(isolate, inobject_properties);
  map->InitializeDescriptors(*descriptors,
                             LayoutDescriptor::FastPointerLayout());

  int next_field_offset = 0;
  for (int i = 0; i < kPropsCount; i++) {
    EmbeddedVector<char, 64> buffer;
    SNPrintF(buffer, "prop%d", i);
    Handle<String> name = factory->InternalizeUtf8String(buffer.start());

    Handle<LayoutDescriptor> layout_descriptor;
    TestPropertyKind kind = props[i];
    if (kind == PROP_CONSTANT) {
      DataConstantDescriptor d(name, func, NONE);
      layout_descriptor = LayoutDescriptor::ShareAppend(map, d.GetDetails());
      descriptors->Append(&d);

    } else {
      DataDescriptor f(name, next_field_offset, NONE, representations[kind]);
      int field_width_in_words = f.GetDetails().field_width_in_words();
      next_field_offset += field_width_in_words;
      layout_descriptor = LayoutDescriptor::ShareAppend(map, f.GetDetails());
      descriptors->Append(&f);

      int field_index = f.GetDetails().field_index();
      bool is_inobject = field_index < map->inobject_properties();
      for (int bit = 0; bit < field_width_in_words; bit++) {
        CHECK_EQ(is_inobject && (kind == PROP_DOUBLE),
                 !layout_descriptor->IsTagged(field_index + bit));
      }
      CHECK(layout_descriptor->IsTagged(next_field_offset));
    }
    map->InitializeDescriptors(*descriptors, *layout_descriptor);
  }
  Handle<LayoutDescriptor> layout_descriptor(map->layout_descriptor(), isolate);
#ifdef VERIFY_HEAP
  if (FLAG_verify_heap) {
    DCHECK(layout_descriptor->IsConsistentWithMap(*map));
  }
#endif
  return layout_descriptor;
}


TEST(LayoutDescriptorAppend) {
  CcTest::InitializeVM();
  Isolate* isolate = CcTest::i_isolate();
  v8::HandleScope scope(CcTest::isolate());

  Handle<LayoutDescriptor> layout_descriptor;
  const int kPropsCount = kSmiValueSize * 3;
  TestPropertyKind props[kPropsCount];
  for (int i = 0; i < kPropsCount; i++) {
    props[i] = static_cast<TestPropertyKind>(i % PROP_KIND_NUMBER);
  }

  layout_descriptor =
      TestLayoutDescriptorAppend(isolate, 0, props, kPropsCount);
  CHECK(!layout_descriptor->IsSlowLayout());

  layout_descriptor =
      TestLayoutDescriptorAppend(isolate, 13, props, kPropsCount);
  CHECK(!layout_descriptor->IsSlowLayout());

  layout_descriptor =
      TestLayoutDescriptorAppend(isolate, kSmiValueSize, props, kPropsCount);
  CHECK(!layout_descriptor->IsSlowLayout());

  layout_descriptor = TestLayoutDescriptorAppend(isolate, kSmiValueSize * 2,
                                                 props, kPropsCount);
  CHECK(layout_descriptor->IsSlowLayout());

  layout_descriptor =
      TestLayoutDescriptorAppend(isolate, kPropsCount, props, kPropsCount);
  CHECK(layout_descriptor->IsSlowLayout());
}


TEST(LayoutDescriptorAppendAllDoubles) {
  CcTest::InitializeVM();
  Isolate* isolate = CcTest::i_isolate();
  v8::HandleScope scope(CcTest::isolate());

  Handle<LayoutDescriptor> layout_descriptor;
  const int kPropsCount = kSmiValueSize * 3;
  TestPropertyKind props[kPropsCount];
  for (int i = 0; i < kPropsCount; i++) {
    props[i] = PROP_DOUBLE;
  }

  layout_descriptor =
      TestLayoutDescriptorAppend(isolate, 0, props, kPropsCount);
  CHECK(!layout_descriptor->IsSlowLayout());

  layout_descriptor =
      TestLayoutDescriptorAppend(isolate, 13, props, kPropsCount);
  CHECK(!layout_descriptor->IsSlowLayout());

  layout_descriptor =
      TestLayoutDescriptorAppend(isolate, kSmiValueSize, props, kPropsCount);
  CHECK(!layout_descriptor->IsSlowLayout());

  layout_descriptor = TestLayoutDescriptorAppend(isolate, kSmiValueSize + 1,
                                                 props, kPropsCount);
  CHECK(layout_descriptor->IsSlowLayout());

  layout_descriptor = TestLayoutDescriptorAppend(isolate, kSmiValueSize * 2,
                                                 props, kPropsCount);
  CHECK(layout_descriptor->IsSlowLayout());

  layout_descriptor =
      TestLayoutDescriptorAppend(isolate, kPropsCount, props, kPropsCount);
  CHECK(layout_descriptor->IsSlowLayout());

  {
    // Ensure layout descriptor switches into slow mode at the right moment.
    layout_descriptor =
        TestLayoutDescriptorAppend(isolate, kPropsCount, props, kSmiValueSize);
    CHECK(!layout_descriptor->IsSlowLayout());

    layout_descriptor = TestLayoutDescriptorAppend(isolate, kPropsCount, props,
                                                   kSmiValueSize + 1);
    CHECK(layout_descriptor->IsSlowLayout());
  }
}


static Handle<LayoutDescriptor> TestLayoutDescriptorAppendIfFastOrUseFull(
    Isolate* isolate, int inobject_properties,
    Handle<DescriptorArray> descriptors, int number_of_descriptors) {
  Handle<Map> map = Map::Create(isolate, inobject_properties);

  Handle<LayoutDescriptor> full_layout_descriptor = LayoutDescriptor::New(
      map, descriptors, descriptors->number_of_descriptors());

  int nof = 0;
  bool switched_to_slow_mode = false;

  for (int i = 0; i < number_of_descriptors; i++) {
    PropertyDetails details = descriptors->GetDetails(i);

    // This method calls LayoutDescriptor::AppendIfFastOrUseFull() internally
    // and does all the required map-descriptors related book keeping.
    map = Map::CopyInstallDescriptorsForTesting(map, i, descriptors,
                                                full_layout_descriptor);

    LayoutDescriptor* layout_desc = map->layout_descriptor();

    if (layout_desc->IsSlowLayout()) {
      switched_to_slow_mode = true;
      CHECK_EQ(*full_layout_descriptor, layout_desc);
    } else {
      CHECK(!switched_to_slow_mode);
      if (details.type() == DATA) {
        nof++;
        int field_index = details.field_index();
        int field_width_in_words = details.field_width_in_words();

        bool is_inobject = field_index < map->inobject_properties();
        for (int bit = 0; bit < field_width_in_words; bit++) {
          CHECK_EQ(is_inobject && details.representation().IsDouble(),
                   !layout_desc->IsTagged(field_index + bit));
        }
        CHECK(layout_desc->IsTagged(field_index + field_width_in_words));
      }
    }
#ifdef VERIFY_HEAP
    if (FLAG_verify_heap) {
      DCHECK(map->layout_descriptor()->IsConsistentWithMap(*map));
    }
#endif
  }

  Handle<LayoutDescriptor> layout_descriptor(map->GetLayoutDescriptor(),
                                             isolate);
#ifdef VERIFY_HEAP
  if (FLAG_verify_heap) {
    DCHECK(layout_descriptor->IsConsistentWithMap(*map));
  }
#endif
  return layout_descriptor;
}


TEST(LayoutDescriptorAppendIfFastOrUseFull) {
  CcTest::InitializeVM();
  Isolate* isolate = CcTest::i_isolate();
  v8::HandleScope scope(CcTest::isolate());

  Handle<LayoutDescriptor> layout_descriptor;
  const int kPropsCount = kSmiValueSize * 3;
  TestPropertyKind props[kPropsCount];
  for (int i = 0; i < kPropsCount; i++) {
    props[i] = static_cast<TestPropertyKind>(i % PROP_KIND_NUMBER);
  }
  Handle<DescriptorArray> descriptors =
      CreateDescriptorArray(isolate, props, kPropsCount);

  layout_descriptor = TestLayoutDescriptorAppendIfFastOrUseFull(
      isolate, 0, descriptors, kPropsCount);
  CHECK(!layout_descriptor->IsSlowLayout());

  layout_descriptor = TestLayoutDescriptorAppendIfFastOrUseFull(
      isolate, 13, descriptors, kPropsCount);
  CHECK(!layout_descriptor->IsSlowLayout());

  layout_descriptor = TestLayoutDescriptorAppendIfFastOrUseFull(
      isolate, kSmiValueSize, descriptors, kPropsCount);
  CHECK(!layout_descriptor->IsSlowLayout());

  layout_descriptor = TestLayoutDescriptorAppendIfFastOrUseFull(
      isolate, kSmiValueSize * 2, descriptors, kPropsCount);
  CHECK(layout_descriptor->IsSlowLayout());

  layout_descriptor = TestLayoutDescriptorAppendIfFastOrUseFull(
      isolate, kPropsCount, descriptors, kPropsCount);
  CHECK(layout_descriptor->IsSlowLayout());
}


TEST(LayoutDescriptorAppendIfFastOrUseFullAllDoubles) {
  CcTest::InitializeVM();
  Isolate* isolate = CcTest::i_isolate();
  v8::HandleScope scope(CcTest::isolate());

  Handle<LayoutDescriptor> layout_descriptor;
  const int kPropsCount = kSmiValueSize * 3;
  TestPropertyKind props[kPropsCount];
  for (int i = 0; i < kPropsCount; i++) {
    props[i] = PROP_DOUBLE;
  }
  Handle<DescriptorArray> descriptors =
      CreateDescriptorArray(isolate, props, kPropsCount);

  layout_descriptor = TestLayoutDescriptorAppendIfFastOrUseFull(
      isolate, 0, descriptors, kPropsCount);
  CHECK(!layout_descriptor->IsSlowLayout());

  layout_descriptor = TestLayoutDescriptorAppendIfFastOrUseFull(
      isolate, 13, descriptors, kPropsCount);
  CHECK(!layout_descriptor->IsSlowLayout());

  layout_descriptor = TestLayoutDescriptorAppendIfFastOrUseFull(
      isolate, kSmiValueSize, descriptors, kPropsCount);
  CHECK(!layout_descriptor->IsSlowLayout());

  layout_descriptor = TestLayoutDescriptorAppendIfFastOrUseFull(
      isolate, kSmiValueSize + 1, descriptors, kPropsCount);
  CHECK(layout_descriptor->IsSlowLayout());

  layout_descriptor = TestLayoutDescriptorAppendIfFastOrUseFull(
      isolate, kSmiValueSize * 2, descriptors, kPropsCount);
  CHECK(layout_descriptor->IsSlowLayout());

  layout_descriptor = TestLayoutDescriptorAppendIfFastOrUseFull(
      isolate, kPropsCount, descriptors, kPropsCount);
  CHECK(layout_descriptor->IsSlowLayout());

  {
    // Ensure layout descriptor switches into slow mode at the right moment.
    layout_descriptor = TestLayoutDescriptorAppendIfFastOrUseFull(
        isolate, kPropsCount, descriptors, kSmiValueSize);
    CHECK(!layout_descriptor->IsSlowLayout());

    layout_descriptor = TestLayoutDescriptorAppendIfFastOrUseFull(
        isolate, kPropsCount, descriptors, kSmiValueSize + 1);
    CHECK(layout_descriptor->IsSlowLayout());
  }
}


TEST(Regress436816) {
  CcTest::InitializeVM();
  Isolate* isolate = CcTest::i_isolate();
  Factory* factory = isolate->factory();
  v8::HandleScope scope(CcTest::isolate());

  const int kPropsCount = kSmiValueSize * 3;
  TestPropertyKind props[kPropsCount];
  for (int i = 0; i < kPropsCount; i++) {
    props[i] = PROP_DOUBLE;
  }
  Handle<DescriptorArray> descriptors =
      CreateDescriptorArray(isolate, props, kPropsCount);

  Handle<Map> map = Map::Create(isolate, kPropsCount);
  Handle<LayoutDescriptor> layout_descriptor =
      LayoutDescriptor::New(map, descriptors, kPropsCount);
  map->InitializeDescriptors(*descriptors, *layout_descriptor);

  Handle<JSObject> object = factory->NewJSObjectFromMap(map, TENURED);

  Address fake_address = reinterpret_cast<Address>(~kHeapObjectTagMask);
  HeapObject* fake_object = HeapObject::FromAddress(fake_address);
  CHECK(fake_object->IsHeapObject());

  double boom_value = bit_cast<double>(fake_object);
  for (int i = 0; i < kPropsCount; i++) {
    FieldIndex index = FieldIndex::ForDescriptor(*map, i);
    CHECK(map->IsUnboxedDoubleField(index));
    object->RawFastDoublePropertyAtPut(index, boom_value);
  }
  CHECK(object->HasFastProperties());
  CHECK(!object->map()->HasFastPointerLayout());

  Handle<Map> normalized_map =
      Map::Normalize(map, KEEP_INOBJECT_PROPERTIES, "testing");
  JSObject::MigrateToMap(object, normalized_map);
  CHECK(!object->HasFastProperties());
  CHECK(object->map()->HasFastPointerLayout());

  // Trigger GCs and heap verification.
  CcTest::heap()->CollectAllGarbage(i::Heap::kNoGCFlags);
}


TEST(DoScavenge) {
  CcTest::InitializeVM();
  Isolate* isolate = CcTest::i_isolate();
  Factory* factory = isolate->factory();
  v8::HandleScope scope(CcTest::isolate());

  CompileRun(
      "function A() {"
      "  this.x = 42.5;"
      "  this.o = {};"
      "};"
      "var o = new A();");

  Handle<String> obj_name = factory->InternalizeUtf8String("o");

  Handle<Object> obj_value =
      Object::GetProperty(isolate->global_object(), obj_name).ToHandleChecked();
  CHECK(obj_value->IsJSObject());
  Handle<JSObject> obj = Handle<JSObject>::cast(obj_value);

  {
    // Ensure the object is properly set up.
    Map* map = obj->map();
    DescriptorArray* descriptors = map->instance_descriptors();
    CHECK(map->NumberOfOwnDescriptors() == 2);
    CHECK(descriptors->GetDetails(0).representation().IsDouble());
    CHECK(descriptors->GetDetails(1).representation().IsHeapObject());
    FieldIndex field_index = FieldIndex::ForDescriptor(map, 0);
    CHECK(field_index.is_inobject() && field_index.is_double());
    CHECK_EQ(FLAG_unbox_double_fields, map->IsUnboxedDoubleField(field_index));
    CHECK_EQ(42.5, GetDoubleFieldValue(*obj, field_index));
  }
  CHECK(isolate->heap()->new_space()->Contains(*obj));

  // Trigger GCs so that the newly allocated object moves to old gen.
  CcTest::heap()->CollectGarbage(i::NEW_SPACE);  // in survivor space now

  // Create temp object in the new space.
  Handle<JSArray> temp = factory->NewJSArray(FAST_ELEMENTS, NOT_TENURED);
  CHECK(isolate->heap()->new_space()->Contains(*temp));

  // Construct a double value that looks like a pointer to the new space object
  // and store it into the obj.
  Address fake_object = reinterpret_cast<Address>(*temp) + kPointerSize;
  double boom_value = bit_cast<double>(fake_object);

  FieldIndex field_index = FieldIndex::ForDescriptor(obj->map(), 0);
  Handle<HeapNumber> boom_number = factory->NewHeapNumber(boom_value, MUTABLE);
  obj->FastPropertyAtPut(field_index, *boom_number);

  // Now the object moves to old gen and it has a double field that looks like
  // a pointer to a from semi-space.
  CcTest::heap()->CollectGarbage(i::NEW_SPACE);  // in old gen now

  CHECK(isolate->heap()->old_pointer_space()->Contains(*obj));

  CHECK_EQ(boom_value, GetDoubleFieldValue(*obj, field_index));
}


static void TestLayoutDescriptorHelper(Isolate* isolate,
                                       int inobject_properties,
                                       Handle<DescriptorArray> descriptors,
                                       int number_of_descriptors) {
  Handle<Map> map = Map::Create(isolate, inobject_properties);

  Handle<LayoutDescriptor> layout_descriptor = LayoutDescriptor::New(
      map, descriptors, descriptors->number_of_descriptors());
  InitializeVerifiedMapDescriptors(*map, *descriptors, *layout_descriptor);

  LayoutDescriptorHelper helper(*map);
  bool all_fields_tagged = true;

  int instance_size = map->instance_size();

  int end_offset = instance_size * 2;
  int first_non_tagged_field_offset = end_offset;
  for (int i = 0; i < number_of_descriptors; i++) {
    PropertyDetails details = descriptors->GetDetails(i);
    if (details.type() != DATA) continue;
    FieldIndex index = FieldIndex::ForDescriptor(*map, i);
    if (!index.is_inobject()) continue;
    all_fields_tagged &= !details.representation().IsDouble();
    bool expected_tagged = !index.is_double();
    if (!expected_tagged) {
      first_non_tagged_field_offset =
          Min(first_non_tagged_field_offset, index.offset());
    }

    int end_of_region_offset;
    CHECK_EQ(expected_tagged, helper.IsTagged(index.offset()));
    CHECK_EQ(expected_tagged, helper.IsTagged(index.offset(), instance_size,
                                              &end_of_region_offset));
    CHECK(end_of_region_offset > 0);
    CHECK(end_of_region_offset % kPointerSize == 0);
    CHECK(end_of_region_offset <= instance_size);

    for (int offset = index.offset(); offset < end_of_region_offset;
         offset += kPointerSize) {
      CHECK_EQ(expected_tagged, helper.IsTagged(index.offset()));
    }
    if (end_of_region_offset < instance_size) {
      CHECK_EQ(!expected_tagged, helper.IsTagged(end_of_region_offset));
    } else {
      CHECK_EQ(true, helper.IsTagged(end_of_region_offset));
    }
  }

  for (int offset = 0; offset < JSObject::kHeaderSize; offset += kPointerSize) {
    // Header queries
    CHECK_EQ(true, helper.IsTagged(offset));
    int end_of_region_offset;
    CHECK_EQ(true, helper.IsTagged(offset, end_offset, &end_of_region_offset));
    CHECK_EQ(first_non_tagged_field_offset, end_of_region_offset);

    // Out of bounds queries
    CHECK_EQ(true, helper.IsTagged(offset + instance_size));
  }

  CHECK_EQ(all_fields_tagged, helper.all_fields_tagged());
}


TEST(LayoutDescriptorHelperMixed) {
  CcTest::InitializeVM();
  Isolate* isolate = CcTest::i_isolate();
  v8::HandleScope scope(CcTest::isolate());

  Handle<LayoutDescriptor> layout_descriptor;
  const int kPropsCount = kSmiValueSize * 3;
  TestPropertyKind props[kPropsCount];
  for (int i = 0; i < kPropsCount; i++) {
    props[i] = static_cast<TestPropertyKind>(i % PROP_KIND_NUMBER);
  }
  Handle<DescriptorArray> descriptors =
      CreateDescriptorArray(isolate, props, kPropsCount);

  TestLayoutDescriptorHelper(isolate, 0, descriptors, kPropsCount);

  TestLayoutDescriptorHelper(isolate, 13, descriptors, kPropsCount);

  TestLayoutDescriptorHelper(isolate, kSmiValueSize, descriptors, kPropsCount);

  TestLayoutDescriptorHelper(isolate, kSmiValueSize * 2, descriptors,
                             kPropsCount);

  TestLayoutDescriptorHelper(isolate, kPropsCount, descriptors, kPropsCount);
}


TEST(LayoutDescriptorHelperAllTagged) {
  CcTest::InitializeVM();
  Isolate* isolate = CcTest::i_isolate();
  v8::HandleScope scope(CcTest::isolate());

  Handle<LayoutDescriptor> layout_descriptor;
  const int kPropsCount = kSmiValueSize * 3;
  TestPropertyKind props[kPropsCount];
  for (int i = 0; i < kPropsCount; i++) {
    props[i] = PROP_TAGGED;
  }
  Handle<DescriptorArray> descriptors =
      CreateDescriptorArray(isolate, props, kPropsCount);

  TestLayoutDescriptorHelper(isolate, 0, descriptors, kPropsCount);

  TestLayoutDescriptorHelper(isolate, 13, descriptors, kPropsCount);

  TestLayoutDescriptorHelper(isolate, kSmiValueSize, descriptors, kPropsCount);

  TestLayoutDescriptorHelper(isolate, kSmiValueSize * 2, descriptors,
                             kPropsCount);

  TestLayoutDescriptorHelper(isolate, kPropsCount, descriptors, kPropsCount);
}


TEST(LayoutDescriptorHelperAllDoubles) {
  CcTest::InitializeVM();
  Isolate* isolate = CcTest::i_isolate();
  v8::HandleScope scope(CcTest::isolate());

  Handle<LayoutDescriptor> layout_descriptor;
  const int kPropsCount = kSmiValueSize * 3;
  TestPropertyKind props[kPropsCount];
  for (int i = 0; i < kPropsCount; i++) {
    props[i] = PROP_DOUBLE;
  }
  Handle<DescriptorArray> descriptors =
      CreateDescriptorArray(isolate, props, kPropsCount);

  TestLayoutDescriptorHelper(isolate, 0, descriptors, kPropsCount);

  TestLayoutDescriptorHelper(isolate, 13, descriptors, kPropsCount);

  TestLayoutDescriptorHelper(isolate, kSmiValueSize, descriptors, kPropsCount);

  TestLayoutDescriptorHelper(isolate, kSmiValueSize * 2, descriptors,
                             kPropsCount);

  TestLayoutDescriptorHelper(isolate, kPropsCount, descriptors, kPropsCount);
}


TEST(LayoutDescriptorSharing) {
  CcTest::InitializeVM();
  v8::HandleScope scope(CcTest::isolate());
  Isolate* isolate = CcTest::i_isolate();
  Handle<HeapType> any_type = HeapType::Any(isolate);

  Handle<Map> split_map;
  {
    Handle<Map> map = Map::Create(isolate, 64);
    for (int i = 0; i < 32; i++) {
      Handle<String> name = MakeName("prop", i);
      map = Map::CopyWithField(map, name, any_type, NONE, Representation::Smi(),
                               INSERT_TRANSITION).ToHandleChecked();
    }
    split_map = Map::CopyWithField(map, MakeString("dbl"), any_type, NONE,
                                   Representation::Double(),
                                   INSERT_TRANSITION).ToHandleChecked();
  }
  Handle<LayoutDescriptor> split_layout_descriptor(
      split_map->layout_descriptor(), isolate);
#ifdef VERIFY_HEAP
  if (FLAG_verify_heap) {
    DCHECK(split_layout_descriptor->IsConsistentWithMap(*split_map));
  }
#endif
  CHECK(split_layout_descriptor->IsSlowLayout());
  CHECK(split_map->owns_descriptors());

  Handle<Map> map1 = Map::CopyWithField(split_map, MakeString("foo"), any_type,
                                        NONE, Representation::Double(),
                                        INSERT_TRANSITION).ToHandleChecked();
  CHECK(!split_map->owns_descriptors());
  CHECK_EQ(*split_layout_descriptor, split_map->layout_descriptor());

  // Layout descriptors should be shared with |split_map|.
  CHECK(map1->owns_descriptors());
  CHECK_EQ(*split_layout_descriptor, map1->layout_descriptor());
#ifdef VERIFY_HEAP
  if (FLAG_verify_heap) {
    DCHECK(map1->layout_descriptor()->IsConsistentWithMap(*map1));
  }
#endif

  Handle<Map> map2 = Map::CopyWithField(split_map, MakeString("bar"), any_type,
                                        NONE, Representation::Tagged(),
                                        INSERT_TRANSITION).ToHandleChecked();

  // Layout descriptors should not be shared with |split_map|.
  CHECK(map2->owns_descriptors());
  CHECK_NE(*split_layout_descriptor, map2->layout_descriptor());
#ifdef VERIFY_HEAP
  if (FLAG_verify_heap) {
    DCHECK(map2->layout_descriptor()->IsConsistentWithMap(*map2));
  }
#endif
}


TEST(StoreBufferScanOnScavenge) {
  CcTest::InitializeVM();
  Isolate* isolate = CcTest::i_isolate();
  Factory* factory = isolate->factory();
  v8::HandleScope scope(CcTest::isolate());

  CompileRun(
      "function A() {"
      "  this.x = 42.5;"
      "  this.o = {};"
      "};"
      "var o = new A();");

  Handle<String> obj_name = factory->InternalizeUtf8String("o");

  Handle<Object> obj_value =
      Object::GetProperty(isolate->global_object(), obj_name).ToHandleChecked();
  CHECK(obj_value->IsJSObject());
  Handle<JSObject> obj = Handle<JSObject>::cast(obj_value);

  {
    // Ensure the object is properly set up.
    Map* map = obj->map();
    DescriptorArray* descriptors = map->instance_descriptors();
    CHECK(map->NumberOfOwnDescriptors() == 2);
    CHECK(descriptors->GetDetails(0).representation().IsDouble());
    CHECK(descriptors->GetDetails(1).representation().IsHeapObject());
    FieldIndex field_index = FieldIndex::ForDescriptor(map, 0);
    CHECK(field_index.is_inobject() && field_index.is_double());
    CHECK_EQ(FLAG_unbox_double_fields, map->IsUnboxedDoubleField(field_index));
    CHECK_EQ(42.5, GetDoubleFieldValue(*obj, field_index));
  }
  CHECK(isolate->heap()->new_space()->Contains(*obj));

  // Trigger GCs so that the newly allocated object moves to old gen.
  CcTest::heap()->CollectGarbage(i::NEW_SPACE);  // in survivor space now
  CcTest::heap()->CollectGarbage(i::NEW_SPACE);  // in old gen now

  CHECK(isolate->heap()->old_pointer_space()->Contains(*obj));

  // Create temp object in the new space.
  Handle<JSArray> temp = factory->NewJSArray(FAST_ELEMENTS, NOT_TENURED);
  CHECK(isolate->heap()->new_space()->Contains(*temp));

  // Construct a double value that looks like a pointer to the new space object
  // and store it into the obj.
  Address fake_object = reinterpret_cast<Address>(*temp) + kPointerSize;
  double boom_value = bit_cast<double>(fake_object);

  FieldIndex field_index = FieldIndex::ForDescriptor(obj->map(), 0);
  Handle<HeapNumber> boom_number = factory->NewHeapNumber(boom_value, MUTABLE);
  obj->FastPropertyAtPut(field_index, *boom_number);

  // Enforce scan on scavenge for the obj's page.
  MemoryChunk* chunk = MemoryChunk::FromAddress(obj->address());
  chunk->set_scan_on_scavenge(true);

  // Trigger GCs and force evacuation. Should not crash there.
  CcTest::heap()->CollectAllGarbage(i::Heap::kNoGCFlags);

  CHECK_EQ(boom_value, GetDoubleFieldValue(*obj, field_index));
}


static int LenFromSize(int size) {
  return (size - FixedArray::kHeaderSize) / kPointerSize;
}


TEST(WriteBarriersInCopyJSObject) {
  FLAG_max_semi_space_size = 1;  // Ensure new space is not growing.
  CcTest::InitializeVM();
  Isolate* isolate = CcTest::i_isolate();
  TestHeap* heap = CcTest::test_heap();

  v8::HandleScope scope(CcTest::isolate());

  // The plan: create JSObject which contains unboxed double value that looks
  // like a reference to an object in new space.
  // Then clone this object (forcing it to go into old space) and check
  // that the value of the unboxed double property of the cloned object has
  // was not corrupted by GC.

  // Step 1: prepare a map for the object. We add unboxed double property to it.
  // Create a map with single inobject property.
  Handle<Map> my_map = Map::Create(isolate, 1);
  Handle<String> name = isolate->factory()->InternalizeUtf8String("foo");
  my_map = Map::CopyWithField(my_map, name, HeapType::Any(isolate), NONE,
                              Representation::Double(),
                              INSERT_TRANSITION).ToHandleChecked();
  my_map->set_pre_allocated_property_fields(1);
  int n_properties = my_map->InitialPropertiesLength();
  CHECK_GE(n_properties, 0);

  int object_size = my_map->instance_size();

  // Step 2: allocate a lot of objects so to almost fill new space: we need
  // just enough room to allocate JSObject and thus fill the newspace.

  int allocation_amount =
      Min(FixedArray::kMaxSize, Page::kMaxRegularHeapObjectSize + kPointerSize);
  int allocation_len = LenFromSize(allocation_amount);
  NewSpace* new_space = heap->new_space();
  Address* top_addr = new_space->allocation_top_address();
  Address* limit_addr = new_space->allocation_limit_address();
  while ((*limit_addr - *top_addr) > allocation_amount) {
    CHECK(!heap->always_allocate());
    Object* array = heap->AllocateFixedArray(allocation_len).ToObjectChecked();
    CHECK(new_space->Contains(array));
  }

  // Step 3: now allocate fixed array and JSObject to fill the whole new space.
  int to_fill = static_cast<int>(*limit_addr - *top_addr - object_size);
  int fixed_array_len = LenFromSize(to_fill);
  CHECK(fixed_array_len < FixedArray::kMaxLength);

  CHECK(!heap->always_allocate());
  Object* array = heap->AllocateFixedArray(fixed_array_len).ToObjectChecked();
  CHECK(new_space->Contains(array));

  Object* object = heap->AllocateJSObjectFromMap(*my_map).ToObjectChecked();
  CHECK(new_space->Contains(object));
  JSObject* jsobject = JSObject::cast(object);
  CHECK_EQ(0, FixedArray::cast(jsobject->elements())->length());
  CHECK_EQ(0, jsobject->properties()->length());

  // Construct a double value that looks like a pointer to the new space object
  // and store it into the obj.
  Address fake_object = reinterpret_cast<Address>(array) + kPointerSize;
  double boom_value = bit_cast<double>(fake_object);
  FieldIndex index = FieldIndex::ForDescriptor(*my_map, 0);
  jsobject->RawFastDoublePropertyAtPut(index, boom_value);

  CHECK_EQ(0, static_cast<int>(*limit_addr - *top_addr));

  // Step 4: clone jsobject, but force always allocate first to create a clone
  // in old pointer space.
  AlwaysAllocateScope aa_scope(isolate);
  Object* clone_obj = heap->CopyJSObject(jsobject).ToObjectChecked();
  Handle<JSObject> clone(JSObject::cast(clone_obj));
  CHECK(heap->old_pointer_space()->Contains(clone->address()));

  CcTest::heap()->CollectGarbage(NEW_SPACE, "boom");

  // The value in cloned object should not be corrupted by GC.
  CHECK_EQ(boom_value, clone->RawFastDoublePropertyAt(index));
}

#endif