CSE2410 Fall 2014 Bounce

// Copyright 2012 the V8 project authors. All rights reserved.

// Redistribution and use in source and binary forms, with or without

// modification, are permitted provided that the following conditions are

// met:

//

//     * Redistributions of source code must retain the above copyright

//       notice, this list of conditions and the following disclaimer.

//     * Redistributions in binary form must reproduce the above

//       copyright notice, this list of conditions and the following

//       disclaimer in the documentation and/or other materials provided

//       with the distribution.

//     * Neither the name of Google Inc. nor the names of its

//       contributors may be used to endorse or promote products derived

//       from this software without specific prior written permission.

//

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#ifndef V8_HEAP_INL_H_

#define V8_HEAP_INL_H_

#include "heap.h"

#include "isolate.h"

#include "list-inl.h"

#include "objects.h"

#include "platform.h"

#include "v8-counters.h"

#include "store-buffer.h"

#include "store-buffer-inl.h"

namespace v8 {

namespace internal {

void PromotionQueue::insert(HeapObject* target, int size) {

  if (emergency_stack_ != NULL) {

    emergency_stack_->Add(Entry(target, size));

    return;

  }

  if (NewSpacePage::IsAtStart(reinterpret_cast<Address>(rear_))) {

    NewSpacePage* rear_page =

        NewSpacePage::FromAddress(reinterpret_cast<Address>(rear_));

    ASSERT(!rear_page->prev_page()->is_anchor());

    rear_ = reinterpret_cast<intptr_t*>(rear_page->prev_page()->area_end());

    ActivateGuardIfOnTheSamePage();

  }

  if (guard_) {

    ASSERT(GetHeadPage() ==

           Page::FromAllocationTop(reinterpret_cast<Address>(limit_)));

    if ((rear_ - 2) < limit_) {

      RelocateQueueHead();

      emergency_stack_->Add(Entry(target, size));

      return;

    }

  }

  *(--rear_) = reinterpret_cast<intptr_t>(target);

  *(--rear_) = size;

  // Assert no overflow into live objects.

#ifdef DEBUG

  SemiSpace::AssertValidRange(target->GetIsolate()->heap()->new_space()->top(),

                              reinterpret_cast<Address>(rear_));

#endif

}

void PromotionQueue::ActivateGuardIfOnTheSamePage() {

  guard_ = guard_ ||

      heap_->new_space()->active_space()->current_page()->address() ==

      GetHeadPage()->address();

}

MaybeObject* Heap::AllocateStringFromUtf8(Vector<const char> str,

                                          PretenureFlag pretenure) {

  // Check for ASCII first since this is the common case.

  const char* start = str.start();

  int length = str.length();

  int non_ascii_start = String::NonAsciiStart(start, length);

  if (non_ascii_start >= length) {

    // If the string is ASCII, we do not need to convert the characters

    // since UTF8 is backwards compatible with ASCII.

    return AllocateStringFromOneByte(str, pretenure);

  }

  // Non-ASCII and we need to decode.

  return AllocateStringFromUtf8Slow(str, non_ascii_start, pretenure);

}

template<>

bool inline Heap::IsOneByte(Vector<const char> str, int chars) {

  // TODO(dcarney): incorporate Latin-1 check when Latin-1 is supported?

  // ASCII only check.

  return chars == str.length();

}

template<>

bool inline Heap::IsOneByte(String* str, int chars) {

  return str->IsOneByteRepresentation();

}

MaybeObject* Heap::AllocateInternalizedStringFromUtf8(

    Vector<const char> str, int chars, uint32_t hash_field) {

  if (IsOneByte(str, chars)) {

    return AllocateOneByteInternalizedString(

        Vector<const uint8_t>::cast(str), hash_field);

  }

  return AllocateInternalizedStringImpl<false>(str, chars, hash_field);

}

template<typename T>

MaybeObject* Heap::AllocateInternalizedStringImpl(

    T t, int chars, uint32_t hash_field) {

  if (IsOneByte(t, chars)) {

    return AllocateInternalizedStringImpl<true>(t, chars, hash_field);

  }

  return AllocateInternalizedStringImpl<false>(t, chars, hash_field);

}

MaybeObject* Heap::AllocateOneByteInternalizedString(Vector<const uint8_t> str,

                                                     uint32_t hash_field) {

  if (str.length() > SeqOneByteString::kMaxLength) {

    return Failure::OutOfMemoryException(0x2);

  }

  // Compute map and object size.

  Map* map = ascii_internalized_string_map();

  int size = SeqOneByteString::SizeFor(str.length());

  AllocationSpace space = SelectSpace(size, OLD_DATA_SPACE, TENURED);

  // Allocate string.

  Object* result;

  { MaybeObject* maybe_result = AllocateRaw(size, space, OLD_DATA_SPACE);

    if (!maybe_result->ToObject(&result)) return maybe_result;

  }

  // String maps are all immortal immovable objects.

  reinterpret_cast<HeapObject*>(result)->set_map_no_write_barrier(map);

  // Set length and hash fields of the allocated string.

  String* answer = String::cast(result);

  answer->set_length(str.length());

  answer->set_hash_field(hash_field);

  ASSERT_EQ(size, answer->Size());

  // Fill in the characters.

  OS::MemCopy(answer->address() + SeqOneByteString::kHeaderSize,

              str.start(), str.length());

  return answer;

}

MaybeObject* Heap::AllocateTwoByteInternalizedString(Vector<const uc16> str,

                                                     uint32_t hash_field) {

  if (str.length() > SeqTwoByteString::kMaxLength) {

    return Failure::OutOfMemoryException(0x3);

  }

  // Compute map and object size.

  Map* map = internalized_string_map();

  int size = SeqTwoByteString::SizeFor(str.length());

  AllocationSpace space = SelectSpace(size, OLD_DATA_SPACE, TENURED);

  // Allocate string.

  Object* result;

  { MaybeObject* maybe_result = AllocateRaw(size, space, OLD_DATA_SPACE);

    if (!maybe_result->ToObject(&result)) return maybe_result;

  }

  reinterpret_cast<HeapObject*>(result)->set_map(map);

  // Set length and hash fields of the allocated string.

  String* answer = String::cast(result);

  answer->set_length(str.length());

  answer->set_hash_field(hash_field);

  ASSERT_EQ(size, answer->Size());

  // Fill in the characters.

  OS::MemCopy(answer->address() + SeqTwoByteString::kHeaderSize,

              str.start(), str.length() * kUC16Size);

  return answer;

}

MaybeObject* Heap::CopyFixedArray(FixedArray* src) {

  return CopyFixedArrayWithMap(src, src->map());

}

MaybeObject* Heap::CopyFixedDoubleArray(FixedDoubleArray* src) {

  return CopyFixedDoubleArrayWithMap(src, src->map());

}

MaybeObject* Heap::CopyConstantPoolArray(ConstantPoolArray* src) {

  return CopyConstantPoolArrayWithMap(src, src->map());

}

MaybeObject* Heap::AllocateRaw(int size_in_bytes,

                               AllocationSpace space,

                               AllocationSpace retry_space) {

  ASSERT(AllowHandleAllocation::IsAllowed());

  ASSERT(AllowHeapAllocation::IsAllowed());

  ASSERT(gc_state_ == NOT_IN_GC);

  ASSERT(space != NEW_SPACE ||

         retry_space == OLD_POINTER_SPACE ||

         retry_space == OLD_DATA_SPACE ||

         retry_space == LO_SPACE);

#ifdef DEBUG

  if (FLAG_gc_interval >= 0 &&

      !disallow_allocation_failure_ &&

      Heap::allocation_timeout_-- <= 0) {

    return Failure::RetryAfterGC(space);

  }

  isolate_->counters()->objs_since_last_full()->Increment();

  isolate_->counters()->objs_since_last_young()->Increment();

#endif

  MaybeObject* result;

  if (NEW_SPACE == space) {

    result = new_space_.AllocateRaw(size_in_bytes);

    if (always_allocate() && result->IsFailure()) {

      space = retry_space;

    } else {

      return result;

    }

  }

  if (OLD_POINTER_SPACE == space) {

    result = old_pointer_space_->AllocateRaw(size_in_bytes);

  } else if (OLD_DATA_SPACE == space) {

    result = old_data_space_->AllocateRaw(size_in_bytes);

  } else if (CODE_SPACE == space) {

    result = code_space_->AllocateRaw(size_in_bytes);

  } else if (LO_SPACE == space) {

    result = lo_space_->AllocateRaw(size_in_bytes, NOT_EXECUTABLE);

  } else if (CELL_SPACE == space) {

    result = cell_space_->AllocateRaw(size_in_bytes);

  } else if (PROPERTY_CELL_SPACE == space) {

    result = property_cell_space_->AllocateRaw(size_in_bytes);

  } else {

    ASSERT(MAP_SPACE == space);

    result = map_space_->AllocateRaw(size_in_bytes);

  }

  if (result->IsFailure()) old_gen_exhausted_ = true;

  return result;

}

MaybeObject* Heap::NumberFromInt32(

    int32_t value, PretenureFlag pretenure) {

  if (Smi::IsValid(value)) return Smi::FromInt(value);

  // Bypass NumberFromDouble to avoid various redundant checks.

  return AllocateHeapNumber(FastI2D(value), pretenure);

}

MaybeObject* Heap::NumberFromUint32(

    uint32_t value, PretenureFlag pretenure) {

  if (static_cast<int32_t>(value) >= 0 &&

      Smi::IsValid(static_cast<int32_t>(value))) {

    return Smi::FromInt(static_cast<int32_t>(value));

  }

  // Bypass NumberFromDouble to avoid various redundant checks.

  return AllocateHeapNumber(FastUI2D(value), pretenure);

}

void Heap::FinalizeExternalString(String* string) {

  ASSERT(string->IsExternalString());

  v8::String::ExternalStringResourceBase** resource_addr =

      reinterpret_cast<v8::String::ExternalStringResourceBase**>(

          reinterpret_cast<byte*>(string) +

          ExternalString::kResourceOffset -

          kHeapObjectTag);

  // Dispose of the C++ object if it has not already been disposed.

  if (*resource_addr != NULL) {

    (*resource_addr)->Dispose();

    *resource_addr = NULL;

  }

}

bool Heap::InNewSpace(Object* object) {

  bool result = new_space_.Contains(object);

  ASSERT(!result ||                  // Either not in new space

         gc_state_ != NOT_IN_GC ||   // ... or in the middle of GC

         InToSpace(object));         // ... or in to-space (where we allocate).

  return result;

}

bool Heap::InNewSpace(Address address) {

  return new_space_.Contains(address);

}

bool Heap::InFromSpace(Object* object) {

  return new_space_.FromSpaceContains(object);

}

bool Heap::InToSpace(Object* object) {

  return new_space_.ToSpaceContains(object);

}

bool Heap::InOldPointerSpace(Address address) {

  return old_pointer_space_->Contains(address);

}

bool Heap::InOldPointerSpace(Object* object) {

  return InOldPointerSpace(reinterpret_cast<Address>(object));

}

bool Heap::InOldDataSpace(Address address) {

  return old_data_space_->Contains(address);

}

bool Heap::InOldDataSpace(Object* object) {

  return InOldDataSpace(reinterpret_cast<Address>(object));

}

bool Heap::OldGenerationAllocationLimitReached() {

  if (!incremental_marking()->IsStopped()) return false;

  return OldGenerationSpaceAvailable() < 0;

}

bool Heap::ShouldBePromoted(Address old_address, int object_size) {

  // An object should be promoted if:

  // - the object has survived a scavenge operation or

  // - to space is already 25% full.

  NewSpacePage* page = NewSpacePage::FromAddress(old_address);

  Address age_mark = new_space_.age_mark();

  bool below_mark = page->IsFlagSet(MemoryChunk::NEW_SPACE_BELOW_AGE_MARK) &&

      (!page->ContainsLimit(age_mark) || old_address < age_mark);

  return below_mark || (new_space_.Size() + object_size) >=

                        (new_space_.EffectiveCapacity() >> 2);

}

void Heap::RecordWrite(Address address, int offset) {

  if (!InNewSpace(address)) store_buffer_.Mark(address + offset);

}

void Heap::RecordWrites(Address address, int start, int len) {

  if (!InNewSpace(address)) {

    for (int i = 0; i < len; i++) {

      store_buffer_.Mark(address + start + i * kPointerSize);

    }

  }

}

OldSpace* Heap::TargetSpace(HeapObject* object) {

  InstanceType type = object->map()->instance_type();

  AllocationSpace space = TargetSpaceId(type);

  return (space == OLD_POINTER_SPACE)

      ? old_pointer_space_

      : old_data_space_;

}

AllocationSpace Heap::TargetSpaceId(InstanceType type) {

  // Heap numbers and sequential strings are promoted to old data space, all

  // other object types are promoted to old pointer space.  We do not use

  // object->IsHeapNumber() and object->IsSeqString() because we already

  // know that object has the heap object tag.

  // These objects are never allocated in new space.

  ASSERT(type != MAP_TYPE);

  ASSERT(type != CODE_TYPE);

  ASSERT(type != ODDBALL_TYPE);

  ASSERT(type != CELL_TYPE);

  ASSERT(type != PROPERTY_CELL_TYPE);

  if (type <= LAST_NAME_TYPE) {

    if (type == SYMBOL_TYPE) return OLD_POINTER_SPACE;

    ASSERT(type < FIRST_NONSTRING_TYPE);

    // There are four string representations: sequential strings, external

    // strings, cons strings, and sliced strings.

    // Only the latter two contain non-map-word pointers to heap objects.

    return ((type & kIsIndirectStringMask) == kIsIndirectStringTag)

        ? OLD_POINTER_SPACE

        : OLD_DATA_SPACE;

  } else {

    return (type <= LAST_DATA_TYPE) ? OLD_DATA_SPACE : OLD_POINTER_SPACE;

  }

}

bool Heap::AllowedToBeMigrated(HeapObject* object, AllocationSpace dst) {

  // Object migration is governed by the following rules:

  //

  // 1) Objects in new-space can be migrated to one of the old spaces

  //    that matches their target space or they stay in new-space.

  // 2) Objects in old-space stay in the same space when migrating.

  // 3) Fillers (two or more words) can migrate due to left-trimming of

  //    fixed arrays in new-space, old-data-space and old-pointer-space.

  // 4) Fillers (one word) can never migrate, they are skipped by

  //    incremental marking explicitly to prevent invalid pattern.

  //

  // Since this function is used for debugging only, we do not place

  // asserts here, but check everything explicitly.

  if (object->map() == one_pointer_filler_map()) return false;

  InstanceType type = object->map()->instance_type();

  MemoryChunk* chunk = MemoryChunk::FromAddress(object->address());

  AllocationSpace src = chunk->owner()->identity();

  switch (src) {

    case NEW_SPACE:

      return dst == src || dst == TargetSpaceId(type);

    case OLD_POINTER_SPACE:

      return dst == src && (dst == TargetSpaceId(type) || object->IsFiller());

    case OLD_DATA_SPACE:

      return dst == src && dst == TargetSpaceId(type);

    case CODE_SPACE:

      return dst == src && type == CODE_TYPE;

    case MAP_SPACE:

    case CELL_SPACE:

    case PROPERTY_CELL_SPACE:

    case LO_SPACE:

      return false;

  }

  UNREACHABLE();

  return false;

}

void Heap::CopyBlock(Address dst, Address src, int byte_size) {

  CopyWords(reinterpret_cast<Object**>(dst),

            reinterpret_cast<Object**>(src),

            static_cast<size_t>(byte_size / kPointerSize));

}

void Heap::MoveBlock(Address dst, Address src, int byte_size) {

  ASSERT(IsAligned(byte_size, kPointerSize));

  int size_in_words = byte_size / kPointerSize;

  if ((dst < src) || (dst >= (src + byte_size))) {

    Object** src_slot = reinterpret_cast<Object**>(src);

    Object** dst_slot = reinterpret_cast<Object**>(dst);

    Object** end_slot = src_slot + size_in_words;

    while (src_slot != end_slot) {

      *dst_slot++ = *src_slot++;

    }

  } else {

    OS::MemMove(dst, src, static_cast<size_t>(byte_size));

  }

}

void Heap::ScavengePointer(HeapObject** p) {

  ScavengeObject(p, *p);

}

void Heap::ScavengeObject(HeapObject** p, HeapObject* object) {

  ASSERT(object->GetIsolate()->heap()->InFromSpace(object));

  // We use the first word (where the map pointer usually is) of a heap

  // object to record the forwarding pointer.  A forwarding pointer can

  // point to an old space, the code space, or the to space of the new

  // generation.

  MapWord first_word = object->map_word();

  // If the first word is a forwarding address, the object has already been

  // copied.

  if (first_word.IsForwardingAddress()) {

    HeapObject* dest = first_word.ToForwardingAddress();

    ASSERT(object->GetIsolate()->heap()->InFromSpace(*p));

    *p = dest;

    return;

  }

  if (FLAG_trace_track_allocation_sites && object->IsJSObject()) {

    if (AllocationMemento::FindForJSObject(JSObject::cast(object), true) !=

        NULL) {

      object->GetIsolate()->heap()->allocation_mementos_found_++;

    }

  }

  // AllocationMementos are unrooted and shouldn't survive a scavenge

  ASSERT(object->map() != object->GetHeap()->allocation_memento_map());

  // Call the slow part of scavenge object.

  return ScavengeObjectSlow(p, object);

}

bool Heap::CollectGarbage(AllocationSpace space, const char* gc_reason) {

  const char* collector_reason = NULL;

  GarbageCollector collector = SelectGarbageCollector(space, &collector_reason);

  return CollectGarbage(space, collector, gc_reason, collector_reason);

}

MaybeObject* Heap::PrepareForCompare(String* str) {

  // Always flatten small strings and force flattening of long strings

  // after we have accumulated a certain amount we failed to flatten.

  static const int kMaxAlwaysFlattenLength = 32;

  static const int kFlattenLongThreshold = 16*KB;

  const int length = str->length();

  MaybeObject* obj = str->TryFlatten();

  if (length <= kMaxAlwaysFlattenLength ||

      unflattened_strings_length_ >= kFlattenLongThreshold) {

    return obj;

  }

  if (obj->IsFailure()) {

    unflattened_strings_length_ += length;

  }

  return str;

}

intptr_t Heap::AdjustAmountOfExternalAllocatedMemory(

    intptr_t change_in_bytes) {

  ASSERT(HasBeenSetUp());

  intptr_t amount = amount_of_external_allocated_memory_ + change_in_bytes;

  if (change_in_bytes > 0) {

    // Avoid overflow.

    if (amount > amount_of_external_allocated_memory_) {

      amount_of_external_allocated_memory_ = amount;

    } else {

      // Give up and reset the counters in case of an overflow.

      amount_of_external_allocated_memory_ = 0;

      amount_of_external_allocated_memory_at_last_global_gc_ = 0;

    }

    intptr_t amount_since_last_global_gc = PromotedExternalMemorySize();

    if (amount_since_last_global_gc > external_allocation_limit_) {

      CollectAllGarbage(kNoGCFlags, "external memory allocation limit reached");

    }

  } else {

    // Avoid underflow.

    if (amount >= 0) {

      amount_of_external_allocated_memory_ = amount;

    } else {

      // Give up and reset the counters in case of an underflow.

      amount_of_external_allocated_memory_ = 0;

      amount_of_external_allocated_memory_at_last_global_gc_ = 0;

    }

  }

  if (FLAG_trace_external_memory) {

    PrintPID("%8.0f ms: ", isolate()->time_millis_since_init());

    PrintF("Adjust amount of external memory: delta=%6" V8_PTR_PREFIX "d KB, "

           "amount=%6" V8_PTR_PREFIX "d KB, since_gc=%6" V8_PTR_PREFIX "d KB, "

           "isolate=0x%08" V8PRIxPTR ".\n",

           change_in_bytes / KB,

           amount_of_external_allocated_memory_ / KB,

           PromotedExternalMemorySize() / KB,

           reinterpret_cast<intptr_t>(isolate()));

  }

  ASSERT(amount_of_external_allocated_memory_ >= 0);

  return amount_of_external_allocated_memory_;

}

Isolate* Heap::isolate() {

  return reinterpret_cast<Isolate*>(reinterpret_cast<intptr_t>(this) -

      reinterpret_cast<size_t>(reinterpret_cast<Isolate*>(4)->heap()) + 4);

}

#ifdef DEBUG

#define GC_GREEDY_CHECK(ISOLATE) \

  if (FLAG_gc_greedy) (ISOLATE)->heap()->GarbageCollectionGreedyCheck()

#else

#define GC_GREEDY_CHECK(ISOLATE) { }

#endif

// Calls the FUNCTION_CALL function and retries it up to three times

// to guarantee that any allocations performed during the call will

// succeed if there's enough memory.

// Warning: Do not use the identifiers __object__, __maybe_object__ or

// __scope__ in a call to this macro.

#define CALL_AND_RETRY(ISOLATE, FUNCTION_CALL, RETURN_VALUE, RETURN_EMPTY, OOM)\

  do {                                                                         \

    GC_GREEDY_CHECK(ISOLATE);                                                  \

    MaybeObject* __maybe_object__ = FUNCTION_CALL;                             \

    Object* __object__ = NULL;                                                 \

    if (__maybe_object__->ToObject(&__object__)) RETURN_VALUE;                 \

    if (__maybe_object__->IsOutOfMemory()) {                                   \

      OOM;                                                                     \

    }                                                                          \

    if (!__maybe_object__->IsRetryAfterGC()) RETURN_EMPTY;                     \

    (ISOLATE)->heap()->CollectGarbage(Failure::cast(__maybe_object__)->        \

                                    allocation_space(),                        \

                                    "allocation failure");                     \

    __maybe_object__ = FUNCTION_CALL;                                          \

    if (__maybe_object__->ToObject(&__object__)) RETURN_VALUE;                 \

    if (__maybe_object__->IsOutOfMemory()) {                                   \

      OOM;                                                                     \

    }                                                                          \

    if (!__maybe_object__->IsRetryAfterGC()) RETURN_EMPTY;                     \

    (ISOLATE)->counters()->gc_last_resort_from_handles()->Increment();         \

    (ISOLATE)->heap()->CollectAllAvailableGarbage("last resort gc");           \

    {                                                                          \

      AlwaysAllocateScope __scope__;                                           \

      __maybe_object__ = FUNCTION_CALL;                                        \

    }                                                                          \

    if (__maybe_object__->ToObject(&__object__)) RETURN_VALUE;                 \

    if (__maybe_object__->IsOutOfMemory()) {                                   \

      OOM;                                                                     \

    }                                                                          \

    if (__maybe_object__->IsRetryAfterGC()) {                                  \

      /* TODO(1181417): Fix this. */                                           \

      v8::internal::V8::FatalProcessOutOfMemory("CALL_AND_RETRY_LAST", true);  \

    }                                                                          \

    RETURN_EMPTY;                                                              \

  } while (false)

#define CALL_AND_RETRY_OR_DIE(                                             \

     ISOLATE, FUNCTION_CALL, RETURN_VALUE, RETURN_EMPTY)                   \

  CALL_AND_RETRY(                                                          \

      ISOLATE,                                                             \

      FUNCTION_CALL,                                                       \

      RETURN_VALUE,                                                        \

      RETURN_EMPTY,                                                        \

      v8::internal::V8::FatalProcessOutOfMemory("CALL_AND_RETRY", true))

#define CALL_HEAP_FUNCTION(ISOLATE, FUNCTION_CALL, TYPE)                      \

  CALL_AND_RETRY_OR_DIE(ISOLATE,                                              \

                        FUNCTION_CALL,                                        \

                        return Handle<TYPE>(TYPE::cast(__object__), ISOLATE), \

                        return Handle<TYPE>())                                \

#define CALL_HEAP_FUNCTION_VOID(ISOLATE, FUNCTION_CALL)  \

  CALL_AND_RETRY_OR_DIE(ISOLATE, FUNCTION_CALL, return, return)

#define CALL_HEAP_FUNCTION_PASS_EXCEPTION(ISOLATE, FUNCTION_CALL) \

  CALL_AND_RETRY(ISOLATE,                                         \

                 FUNCTION_CALL,                                   \

                 return __object__,                               \

                 return __maybe_object__,                         \

                 return __maybe_object__)

void ExternalStringTable::AddString(String* string) {

  ASSERT(string->IsExternalString());

  if (heap_->InNewSpace(string)) {

    new_space_strings_.Add(string);

  } else {

    old_space_strings_.Add(string);

  }

}

void ExternalStringTable::Iterate(ObjectVisitor* v) {

  if (!new_space_strings_.is_empty()) {

    Object** start = &new_space_strings_[0];

    v->VisitPointers(start, start + new_space_strings_.length());

  }

  if (!old_space_strings_.is_empty()) {

    Object** start = &old_space_strings_[0];

    v->VisitPointers(start, start + old_space_strings_.length());

  }

}

// Verify() is inline to avoid ifdef-s around its calls in release

// mode.

void ExternalStringTable::Verify() {

#ifdef DEBUG

  for (int i = 0; i < new_space_strings_.length(); ++i) {

    Object* obj = Object::cast(new_space_strings_[i]);

    ASSERT(heap_->InNewSpace(obj));

    ASSERT(obj != heap_->the_hole_value());

  }

  for (int i = 0; i < old_space_strings_.length(); ++i) {

    Object* obj = Object::cast(old_space_strings_[i]);

    ASSERT(!heap_->InNewSpace(obj));

    ASSERT(obj != heap_->the_hole_value());

  }

#endif

}

void ExternalStringTable::AddOldString(String* string) {

  ASSERT(string->IsExternalString());

  ASSERT(!heap_->InNewSpace(string));

  old_space_strings_.Add(string);

}

void ExternalStringTable::ShrinkNewStrings(int position) {

  new_space_strings_.Rewind(position);

#ifdef VERIFY_HEAP

  if (FLAG_verify_heap) {

    Verify();

  }

#endif

}

void Heap::ClearInstanceofCache() {

  set_instanceof_cache_function(the_hole_value());

}

Object* Heap::ToBoolean(bool condition) {

  return condition ? true_value() : false_value();

}

void Heap::CompletelyClearInstanceofCache() {

  set_instanceof_cache_map(the_hole_value());

  set_instanceof_cache_function(the_hole_value());

}

MaybeObject* TranscendentalCache::Get(Type type, double input) {

  SubCache* cache = caches_[type];

  if (cache == NULL) {

    caches_[type] = cache = new SubCache(isolate_, type);

  }

  return cache->Get(input);

}

Address TranscendentalCache::cache_array_address() {

  return reinterpret_cast<Address>(caches_);

}

double TranscendentalCache::SubCache::Calculate(double input) {

  switch (type_) {

    case ACOS:

      return acos(input);

    case ASIN:

      return asin(input);

    case ATAN:

      return atan(input);

    case COS:

      return fast_cos(input);

    case EXP:

      return exp(input);

    case LOG:

      return fast_log(input);

    case SIN:

      return fast_sin(input);

    case TAN:

      return fast_tan(input);

    default:

      return 0.0;  // Never happens.

  }

}

MaybeObject* TranscendentalCache::SubCache::Get(double input) {

  Converter c;

  c.dbl = input;

  int hash = Hash(c);

  Element e = elements_[hash];

  if (e.in[0] == c.integers[0] &&

      e.in[1] == c.integers[1]) {

    ASSERT(e.output != NULL);

    isolate_->counters()->transcendental_cache_hit()->Increment();

    return e.output;

  }

  double answer = Calculate(input);

  isolate_->counters()->transcendental_cache_miss()->Increment();

  Object* heap_number;

  { MaybeObject* maybe_heap_number =

        isolate_->heap()->AllocateHeapNumber(answer);

    if (!maybe_heap_number->ToObject(&heap_number)) return maybe_heap_number;

  }

  elements_[hash].in[0] = c.integers[0];

  elements_[hash].in[1] = c.integers[1];

  elements_[hash].output = heap_number;

  return heap_number;

}

AlwaysAllocateScope::AlwaysAllocateScope() {

  // We shouldn't hit any nested scopes, because that requires

  // non-handle code to call handle code. The code still works but

  // performance will degrade, so we want to catch this situation

  // in debug mode.

  Isolate* isolate = Isolate::Current();

  ASSERT(isolate->heap()->always_allocate_scope_depth_ == 0);

  isolate->heap()->always_allocate_scope_depth_++;

}

AlwaysAllocateScope::~AlwaysAllocateScope() {

  Isolate* isolate = Isolate::Current();

  isolate->heap()->always_allocate_scope_depth_--;

  ASSERT(isolate->heap()->always_allocate_scope_depth_ == 0);

}

#ifdef VERIFY_HEAP

NoWeakObjectVerificationScope::NoWeakObjectVerificationScope() {

  Isolate* isolate = Isolate::Current();

  isolate->heap()->no_weak_object_verification_scope_depth_++;

}

NoWeakObjectVerificationScope::~NoWeakObjectVerificationScope() {

  Isolate* isolate = Isolate::Current();

  isolate->heap()->no_weak_object_verification_scope_depth_--;

}

#endif

void VerifyPointersVisitor::VisitPointers(Object** start, Object** end) {

  for (Object** current = start; current < end; current++) {

    if ((*current)->IsHeapObject()) {

      HeapObject* object = HeapObject::cast(*current);

      CHECK(object->GetIsolate()->heap()->Contains(object));

      CHECK(object->map()->IsMap());

    }

  }

}

double GCTracer::SizeOfHeapObjects() {

  return (static_cast<double>(heap_->SizeOfObjects())) / MB;

}

DisallowAllocationFailure::DisallowAllocationFailure() {

#ifdef DEBUG

  Isolate* isolate = Isolate::Current();

  old_state_ = isolate->heap()->disallow_allocation_failure_;

  isolate->heap()->disallow_allocation_failure_ = true;

#endif

}

DisallowAllocationFailure::~DisallowAllocationFailure() {

#ifdef DEBUG

  Isolate* isolate = Isolate::Current();

  isolate->heap()->disallow_allocation_failure_ = old_state_;

#endif

}

} }  // namespace v8::internal

#endif  // V8_HEAP_INL_H_