text: // 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 <cmath>
  
  #include "heap.h"
  #include "heap-profiler.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);
    HeapProfiler* profiler = isolate_->heap_profiler();
  #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
  
    HeapObject* object;
    MaybeObject* result;
    if (NEW_SPACE == space) {
      result = new_space_.AllocateRaw(size_in_bytes);
      if (always_allocate() && result->IsFailure() && retry_space != NEW_SPACE) {
        space = retry_space;
      } else {
        if (profiler->is_tracking_allocations() && result->To(&object)) {
          profiler->AllocationEvent(object->address(), size_in_bytes);
        }
        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;
    if (profiler->is_tracking_allocations() && result->To(&object)) {
      profiler->AllocationEvent(object->address(), size_in_bytes);
    }
    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* obj, 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.
    // 5) Short external strings can end up in old pointer space when a cons
    //    string in old pointer space is made external (String::MakeExternal).
    //
    // Since this function is used for debugging only, we do not place
    // asserts here, but check everything explicitly.
    if (obj->map() == one_pointer_filler_map()) return false;
    InstanceType type = obj->map()->instance_type();
    MemoryChunk* chunk = MemoryChunk::FromAddress(obj->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) || obj->IsFiller() ||
            (obj->IsExternalString() && ExternalString::cast(obj)->is_short()));
      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::UpdateAllocationSiteFeedback(HeapObject* object) {
    Heap* heap = object->GetHeap();
    ASSERT(heap->InFromSpace(object));
  
    if (!FLAG_allocation_site_pretenuring ||
        !AllocationSite::CanTrack(object->map()->instance_type())) return;
  
    // Check if there is potentially a memento behind the object. If
    // the last word of the momento is on another page we return
    // immediatelly. Note that we do not have to compare with the current
    // top pointer of the from space page, since we always install filler
    // objects above the top pointer of a from space page when performing
    // a garbage collection.
    Address object_address = object->address();
    Address memento_address = object_address + object->Size();
    Address last_memento_word_address = memento_address + kPointerSize;
    if (!NewSpacePage::OnSamePage(object_address,
                                  last_memento_word_address)) {
      return;
    }
  
    HeapObject* candidate = HeapObject::FromAddress(memento_address);
    if (candidate->map() != heap->allocation_memento_map()) return;
  
    AllocationMemento* memento = AllocationMemento::cast(candidate);
    if (!memento->IsValid()) return;
  
    if (memento->GetAllocationSite()->IncrementMementoFoundCount()) {
      heap->AddAllocationSiteToScratchpad(memento->GetAllocationSite());
    }
  }
  
  
  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;
    }
  
    UpdateAllocationSiteFeedback(object);
  
    // 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 v8::GCCallbackFlags callbackFlags) {
    const char* collector_reason = NULL;
    GarbageCollector collector = SelectGarbageCollector(space, &collector_reason);
    return CollectGarbage(collector, gc_reason, collector_reason, callbackFlags);
  }
  
  
  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;
  }
  
  
  int64_t Heap::AdjustAmountOfExternalAllocatedMemory(
      int64_t change_in_bytes) {
    ASSERT(HasBeenSetUp());
    int64_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;
      }
      int64_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",
             static_cast<intptr_t>(change_in_bytes / KB),
             static_cast<intptr_t>(amount_of_external_allocated_memory_ / KB),
             static_cast<intptr_t>(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::Heap::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::Heap::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());
  }
  
  
  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_
  