src/heap/spaces-inl.h

// Copyright 2011 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.

#ifndef V8_HEAP_SPACES_INL_H_
#define V8_HEAP_SPACES_INL_H_

#include "src/heap/incremental-marking.h"
#include "src/heap/spaces.h"
#include "src/isolate.h"
#include "src/msan.h"
#include "src/profiler/heap-profiler.h"
#include "src/v8memory.h"

namespace v8 {
namespace internal {


// -----------------------------------------------------------------------------
// Bitmap

void Bitmap::Clear(MemoryChunk* chunk) {
  Bitmap* bitmap = chunk->markbits();
  for (int i = 0; i < bitmap->CellsCount(); i++) bitmap->cells()[i] = 0;
  chunk->ResetLiveBytes();
}


// -----------------------------------------------------------------------------
// PageIterator

PageIterator::PageIterator(PagedSpace* space)
    : space_(space),
      prev_page_(&space->anchor_),
      next_page_(prev_page_->next_page()) {}


bool PageIterator::has_next() { return next_page_ != &space_->anchor_; }


Page* PageIterator::next() {
  DCHECK(has_next());
  prev_page_ = next_page_;
  next_page_ = next_page_->next_page();
  return prev_page_;
}


// -----------------------------------------------------------------------------
// SemiSpaceIterator

HeapObject* SemiSpaceIterator::Next() {
  while (current_ != limit_) {
    if (NewSpacePage::IsAtEnd(current_)) {
      NewSpacePage* page = NewSpacePage::FromLimit(current_);
      page = page->next_page();
      DCHECK(!page->is_anchor());
      current_ = page->area_start();
      if (current_ == limit_) return nullptr;
    }
    HeapObject* object = HeapObject::FromAddress(current_);
    current_ += object->Size();
    if (!object->IsFiller()) {
      return object;
    }
  }
  return nullptr;
}


HeapObject* SemiSpaceIterator::next_object() { return Next(); }


// -----------------------------------------------------------------------------
// NewSpacePageIterator

NewSpacePageIterator::NewSpacePageIterator(NewSpace* space)
    : prev_page_(NewSpacePage::FromAddress(space->ToSpaceStart())->prev_page()),
      next_page_(NewSpacePage::FromAddress(space->ToSpaceStart())),
      last_page_(NewSpacePage::FromLimit(space->ToSpaceEnd())) {}

NewSpacePageIterator::NewSpacePageIterator(SemiSpace* space)
    : prev_page_(space->anchor()),
      next_page_(prev_page_->next_page()),
      last_page_(prev_page_->prev_page()) {}

NewSpacePageIterator::NewSpacePageIterator(Address start, Address limit)
    : prev_page_(NewSpacePage::FromAddress(start)->prev_page()),
      next_page_(NewSpacePage::FromAddress(start)),
      last_page_(NewSpacePage::FromLimit(limit)) {
  SemiSpace::AssertValidRange(start, limit);
}


bool NewSpacePageIterator::has_next() { return prev_page_ != last_page_; }


NewSpacePage* NewSpacePageIterator::next() {
  DCHECK(has_next());
  prev_page_ = next_page_;
  next_page_ = next_page_->next_page();
  return prev_page_;
}


// -----------------------------------------------------------------------------
// HeapObjectIterator

HeapObject* HeapObjectIterator::Next() {
  do {
    HeapObject* next_obj = FromCurrentPage();
    if (next_obj != NULL) return next_obj;
  } while (AdvanceToNextPage());
  return NULL;
}


HeapObject* HeapObjectIterator::next_object() { return Next(); }


HeapObject* HeapObjectIterator::FromCurrentPage() {
  while (cur_addr_ != cur_end_) {
    if (cur_addr_ == space_->top() && cur_addr_ != space_->limit()) {
      cur_addr_ = space_->limit();
      continue;
    }
    HeapObject* obj = HeapObject::FromAddress(cur_addr_);
    int obj_size = obj->Size();
    cur_addr_ += obj_size;
    DCHECK(cur_addr_ <= cur_end_);
    // TODO(hpayer): Remove the debugging code.
    if (cur_addr_ > cur_end_) {
      space_->heap()->isolate()->PushStackTraceAndDie(0xaaaaaaaa, obj, NULL,
                                                      obj_size);
    }

    if (!obj->IsFiller()) {
      if (obj->IsCode()) {
        DCHECK_EQ(space_, space_->heap()->code_space());
        DCHECK_CODEOBJECT_SIZE(obj_size, space_);
      } else {
        DCHECK_OBJECT_SIZE(obj_size);
      }
      return obj;
    }
  }
  return NULL;
}


// -----------------------------------------------------------------------------
// MemoryAllocator

#ifdef ENABLE_HEAP_PROTECTION

void MemoryAllocator::Protect(Address start, size_t size) {
  base::OS::Protect(start, size);
}


void MemoryAllocator::Unprotect(Address start, size_t size,
                                Executability executable) {
  base::OS::Unprotect(start, size, executable);
}


void MemoryAllocator::ProtectChunkFromPage(Page* page) {
  int id = GetChunkId(page);
  base::OS::Protect(chunks_[id].address(), chunks_[id].size());
}


void MemoryAllocator::UnprotectChunkFromPage(Page* page) {
  int id = GetChunkId(page);
  base::OS::Unprotect(chunks_[id].address(), chunks_[id].size(),
                      chunks_[id].owner()->executable() == EXECUTABLE);
}

#endif


// --------------------------------------------------------------------------
// AllocationResult

AllocationSpace AllocationResult::RetrySpace() {
  DCHECK(IsRetry());
  return static_cast<AllocationSpace>(Smi::cast(object_)->value());
}


// --------------------------------------------------------------------------
// PagedSpace

Page* Page::Initialize(Heap* heap, MemoryChunk* chunk, Executability executable,
                       PagedSpace* owner) {
  Page* page = reinterpret_cast<Page*>(chunk);
  page->mutex_ = new base::Mutex();
  DCHECK(page->area_size() <= kAllocatableMemory);
  DCHECK(chunk->owner() == owner);
  owner->IncreaseCapacity(page->area_size());
  owner->Free(page->area_start(), page->area_size());

  heap->incremental_marking()->SetOldSpacePageFlags(chunk);

  return page;
}


bool PagedSpace::Contains(Address addr) {
  Page* p = Page::FromAddress(addr);
  if (!p->is_valid()) return false;
  return p->owner() == this;
}


bool PagedSpace::Contains(HeapObject* o) { return Contains(o->address()); }


void MemoryChunk::set_scan_on_scavenge(bool scan) {
  if (scan) {
    if (!scan_on_scavenge()) heap_->increment_scan_on_scavenge_pages();
    SetFlag(SCAN_ON_SCAVENGE);
  } else {
    if (scan_on_scavenge()) heap_->decrement_scan_on_scavenge_pages();
    ClearFlag(SCAN_ON_SCAVENGE);
  }
  heap_->incremental_marking()->SetOldSpacePageFlags(this);
}


MemoryChunk* MemoryChunk::FromAnyPointerAddress(Heap* heap, Address addr) {
  MemoryChunk* maybe = reinterpret_cast<MemoryChunk*>(
      OffsetFrom(addr) & ~Page::kPageAlignmentMask);
  if (maybe->owner() != NULL) return maybe;
  LargeObjectIterator iterator(heap->lo_space());
  for (HeapObject* o = iterator.Next(); o != NULL; o = iterator.Next()) {
    // Fixed arrays are the only pointer-containing objects in large object
    // space.
    if (o->IsFixedArray()) {
      MemoryChunk* chunk = MemoryChunk::FromAddress(o->address());
      if (chunk->Contains(addr)) {
        return chunk;
      }
    }
  }
  UNREACHABLE();
  return NULL;
}


PointerChunkIterator::PointerChunkIterator(Heap* heap)
    : state_(kOldSpaceState),
      old_iterator_(heap->old_space()),
      map_iterator_(heap->map_space()),
      lo_iterator_(heap->lo_space()) {}


MemoryChunk* PointerChunkIterator::next() {
  switch (state_) {
    case kOldSpaceState: {
      if (old_iterator_.has_next()) {
        return old_iterator_.next();
      }
      state_ = kMapState;
      // Fall through.
    }
    case kMapState: {
      if (map_iterator_.has_next()) {
        return map_iterator_.next();
      }
      state_ = kLargeObjectState;
      // Fall through.
    }
    case kLargeObjectState: {
      HeapObject* heap_object;
      do {
        heap_object = lo_iterator_.Next();
        if (heap_object == NULL) {
          state_ = kFinishedState;
          return NULL;
        }
        // Fixed arrays are the only pointer-containing objects in large
        // object space.
      } while (!heap_object->IsFixedArray());
      MemoryChunk* answer = MemoryChunk::FromAddress(heap_object->address());
      return answer;
    }
    case kFinishedState:
      return NULL;
    default:
      break;
  }
  UNREACHABLE();
  return NULL;
}


void Page::set_next_page(Page* page) {
  DCHECK(page->owner() == owner());
  set_next_chunk(page);
}


void Page::set_prev_page(Page* page) {
  DCHECK(page->owner() == owner());
  set_prev_chunk(page);
}


// Try linear allocation in the page of alloc_info's allocation top.  Does
// not contain slow case logic (e.g. move to the next page or try free list
// allocation) so it can be used by all the allocation functions and for all
// the paged spaces.
HeapObject* PagedSpace::AllocateLinearly(int size_in_bytes) {
  Address current_top = allocation_info_.top();
  Address new_top = current_top + size_in_bytes;
  if (new_top > allocation_info_.limit()) return NULL;

  allocation_info_.set_top(new_top);
  return HeapObject::FromAddress(current_top);
}


AllocationResult LocalAllocationBuffer::AllocateRawAligned(
    int size_in_bytes, AllocationAlignment alignment) {
  Address current_top = allocation_info_.top();
  int filler_size = Heap::GetFillToAlign(current_top, alignment);

  Address new_top = current_top + filler_size + size_in_bytes;
  if (new_top > allocation_info_.limit()) return AllocationResult::Retry();

  allocation_info_.set_top(new_top);
  if (filler_size > 0) {
    return heap_->PrecedeWithFiller(HeapObject::FromAddress(current_top),
                                    filler_size);
  }

  return AllocationResult(HeapObject::FromAddress(current_top));
}


HeapObject* PagedSpace::AllocateLinearlyAligned(int* size_in_bytes,
                                                AllocationAlignment alignment) {
  Address current_top = allocation_info_.top();
  int filler_size = Heap::GetFillToAlign(current_top, alignment);

  Address new_top = current_top + filler_size + *size_in_bytes;
  if (new_top > allocation_info_.limit()) return NULL;

  allocation_info_.set_top(new_top);
  if (filler_size > 0) {
    *size_in_bytes += filler_size;
    return heap()->PrecedeWithFiller(HeapObject::FromAddress(current_top),
                                     filler_size);
  }

  return HeapObject::FromAddress(current_top);
}


// Raw allocation.
AllocationResult PagedSpace::AllocateRawUnaligned(int size_in_bytes) {
  HeapObject* object = AllocateLinearly(size_in_bytes);

  if (object == NULL) {
    object = free_list_.Allocate(size_in_bytes);
    if (object == NULL) {
      object = SlowAllocateRaw(size_in_bytes);
    }
  }

  if (object != NULL) {
    if (identity() == CODE_SPACE) {
      SkipList::Update(object->address(), size_in_bytes);
    }
    MSAN_ALLOCATED_UNINITIALIZED_MEMORY(object->address(), size_in_bytes);
    return object;
  }

  return AllocationResult::Retry(identity());
}


AllocationResult PagedSpace::AllocateRawUnalignedSynchronized(
    int size_in_bytes) {
  base::LockGuard<base::Mutex> lock_guard(&space_mutex_);
  return AllocateRawUnaligned(size_in_bytes);
}


// Raw allocation.
AllocationResult PagedSpace::AllocateRawAligned(int size_in_bytes,
                                                AllocationAlignment alignment) {
  DCHECK(identity() == OLD_SPACE);
  int allocation_size = size_in_bytes;
  HeapObject* object = AllocateLinearlyAligned(&allocation_size, alignment);

  if (object == NULL) {
    // We don't know exactly how much filler we need to align until space is
    // allocated, so assume the worst case.
    int filler_size = Heap::GetMaximumFillToAlign(alignment);
    allocation_size += filler_size;
    object = free_list_.Allocate(allocation_size);
    if (object == NULL) {
      object = SlowAllocateRaw(allocation_size);
    }
    if (object != NULL && filler_size != 0) {
      object = heap()->AlignWithFiller(object, size_in_bytes, allocation_size,
                                       alignment);
      // Filler objects are initialized, so mark only the aligned object memory
      // as uninitialized.
      allocation_size = size_in_bytes;
    }
  }

  if (object != NULL) {
    MSAN_ALLOCATED_UNINITIALIZED_MEMORY(object->address(), allocation_size);
    return object;
  }

  return AllocationResult::Retry(identity());
}


AllocationResult PagedSpace::AllocateRaw(int size_in_bytes,
                                         AllocationAlignment alignment) {
#ifdef V8_HOST_ARCH_32_BIT
  return alignment == kDoubleAligned
             ? AllocateRawAligned(size_in_bytes, kDoubleAligned)
             : AllocateRawUnaligned(size_in_bytes);
#else
  return AllocateRawUnaligned(size_in_bytes);
#endif
}


// -----------------------------------------------------------------------------
// NewSpace


AllocationResult NewSpace::AllocateRawAligned(int size_in_bytes,
                                              AllocationAlignment alignment) {
  Address top = allocation_info_.top();
  int filler_size = Heap::GetFillToAlign(top, alignment);
  int aligned_size_in_bytes = size_in_bytes + filler_size;

  if (allocation_info_.limit() - top < aligned_size_in_bytes) {
    // See if we can create room.
    if (!EnsureAllocation(size_in_bytes, alignment)) {
      return AllocationResult::Retry();
    }

    top = allocation_info_.top();
    filler_size = Heap::GetFillToAlign(top, alignment);
    aligned_size_in_bytes = size_in_bytes + filler_size;
  }

  HeapObject* obj = HeapObject::FromAddress(top);
  allocation_info_.set_top(top + aligned_size_in_bytes);
  DCHECK_SEMISPACE_ALLOCATION_INFO(allocation_info_, to_space_);

  if (filler_size > 0) {
    obj = heap()->PrecedeWithFiller(obj, filler_size);
  }

  MSAN_ALLOCATED_UNINITIALIZED_MEMORY(obj->address(), size_in_bytes);

  return obj;
}


AllocationResult NewSpace::AllocateRawUnaligned(int size_in_bytes) {
  Address top = allocation_info_.top();
  if (allocation_info_.limit() < top + size_in_bytes) {
    // See if we can create room.
    if (!EnsureAllocation(size_in_bytes, kWordAligned)) {
      return AllocationResult::Retry();
    }

    top = allocation_info_.top();
  }

  HeapObject* obj = HeapObject::FromAddress(top);
  allocation_info_.set_top(top + size_in_bytes);
  DCHECK_SEMISPACE_ALLOCATION_INFO(allocation_info_, to_space_);

  MSAN_ALLOCATED_UNINITIALIZED_MEMORY(obj->address(), size_in_bytes);

  return obj;
}


AllocationResult NewSpace::AllocateRaw(int size_in_bytes,
                                       AllocationAlignment alignment) {
#ifdef V8_HOST_ARCH_32_BIT
  return alignment == kDoubleAligned
             ? AllocateRawAligned(size_in_bytes, kDoubleAligned)
             : AllocateRawUnaligned(size_in_bytes);
#else
  return AllocateRawUnaligned(size_in_bytes);
#endif
}


MUST_USE_RESULT inline AllocationResult NewSpace::AllocateRawSynchronized(
    int size_in_bytes, AllocationAlignment alignment) {
  base::LockGuard<base::Mutex> guard(&mutex_);
  return AllocateRaw(size_in_bytes, alignment);
}


LargePage* LargePage::Initialize(Heap* heap, MemoryChunk* chunk) {
  heap->incremental_marking()->SetOldSpacePageFlags(chunk);
  return static_cast<LargePage*>(chunk);
}


intptr_t LargeObjectSpace::Available() {
  return ObjectSizeFor(heap()->isolate()->memory_allocator()->Available());
}


LocalAllocationBuffer LocalAllocationBuffer::InvalidBuffer() {
  return LocalAllocationBuffer(nullptr, AllocationInfo(nullptr, nullptr));
}


LocalAllocationBuffer LocalAllocationBuffer::FromResult(Heap* heap,
                                                        AllocationResult result,
                                                        intptr_t size) {
  if (result.IsRetry()) return InvalidBuffer();
  HeapObject* obj = nullptr;
  bool ok = result.To(&obj);
  USE(ok);
  DCHECK(ok);
  Address top = HeapObject::cast(obj)->address();
  return LocalAllocationBuffer(heap, AllocationInfo(top, top + size));
}


bool LocalAllocationBuffer::TryMerge(LocalAllocationBuffer* other) {
  if (allocation_info_.top() == other->allocation_info_.limit()) {
    allocation_info_.set_top(other->allocation_info_.top());
    other->allocation_info_.Reset(nullptr, nullptr);
    return true;
  }
  return false;
}

}  // namespace internal
}  // namespace v8

#endif  // V8_HEAP_SPACES_INL_H_