src/third_party/v8/src/heap/basic-memory-chunk.cc

// Copyright 2019 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 "src/heap/basic-memory-chunk.h"

#include <cstdlib>

#include "src/heap/heap-write-barrier-inl.h"
#include "src/heap/incremental-marking.h"
#include "src/objects/heap-object.h"

namespace v8 {
namespace internal {

// Verify write barrier offsets match the the real offsets.
STATIC_ASSERT(BasicMemoryChunk::Flag::INCREMENTAL_MARKING ==
              heap_internals::MemoryChunk::kMarkingBit);
STATIC_ASSERT(BasicMemoryChunk::Flag::FROM_PAGE ==
              heap_internals::MemoryChunk::kFromPageBit);
STATIC_ASSERT(BasicMemoryChunk::Flag::TO_PAGE ==
              heap_internals::MemoryChunk::kToPageBit);
STATIC_ASSERT(BasicMemoryChunk::kFlagsOffset ==
              heap_internals::MemoryChunk::kFlagsOffset);
STATIC_ASSERT(BasicMemoryChunk::kHeapOffset ==
              heap_internals::MemoryChunk::kHeapOffset);

BasicMemoryChunk::BasicMemoryChunk(size_t size, Address area_start,
                                   Address area_end) {
  size_ = size;
  area_start_ = area_start;
  area_end_ = area_end;
}

// static
BasicMemoryChunk* BasicMemoryChunk::Initialize(Heap* heap, Address base,
                                               size_t size, Address area_start,
                                               Address area_end,
                                               BaseSpace* owner,
                                               VirtualMemory reservation) {
  BasicMemoryChunk* chunk = FromAddress(base);
  DCHECK_EQ(base, chunk->address());
  new (chunk) BasicMemoryChunk(size, area_start, area_end);

  chunk->heap_ = heap;
  chunk->set_owner(owner);
  chunk->reservation_ = std::move(reservation);
  chunk->high_water_mark_ = static_cast<intptr_t>(area_start - base);
  chunk->allocated_bytes_ = chunk->area_size();
  chunk->wasted_memory_ = 0;
  chunk->marking_bitmap<AccessMode::NON_ATOMIC>()->Clear();

  return chunk;
}

bool BasicMemoryChunk::InOldSpace() const {
  return owner()->identity() == OLD_SPACE;
}

bool BasicMemoryChunk::InLargeObjectSpace() const {
  return owner()->identity() == LO_SPACE;
}

#ifdef THREAD_SANITIZER
void BasicMemoryChunk::SynchronizedHeapLoad() {
  CHECK(reinterpret_cast<Heap*>(base::Acquire_Load(
            reinterpret_cast<base::AtomicWord*>(&heap_))) != nullptr ||
        InReadOnlySpace());
}
#endif

class BasicMemoryChunkValidator {
  // Computed offsets should match the compiler generated ones.
  STATIC_ASSERT(BasicMemoryChunk::kSizeOffset ==
                offsetof(BasicMemoryChunk, size_));
  STATIC_ASSERT(BasicMemoryChunk::kFlagsOffset ==
                offsetof(BasicMemoryChunk, flags_));
  STATIC_ASSERT(BasicMemoryChunk::kHeapOffset ==
                offsetof(BasicMemoryChunk, heap_));
  STATIC_ASSERT(offsetof(BasicMemoryChunk, size_) ==
                MemoryChunkLayout::kSizeOffset);
  STATIC_ASSERT(offsetof(BasicMemoryChunk, flags_) ==
                MemoryChunkLayout::kFlagsOffset);
  STATIC_ASSERT(offsetof(BasicMemoryChunk, heap_) ==
                MemoryChunkLayout::kHeapOffset);
  STATIC_ASSERT(offsetof(BasicMemoryChunk, area_start_) ==
                MemoryChunkLayout::kAreaStartOffset);
  STATIC_ASSERT(offsetof(BasicMemoryChunk, area_end_) ==
                MemoryChunkLayout::kAreaEndOffset);
  STATIC_ASSERT(offsetof(BasicMemoryChunk, allocated_bytes_) ==
                MemoryChunkLayout::kAllocatedBytesOffset);
  STATIC_ASSERT(offsetof(BasicMemoryChunk, wasted_memory_) ==
                MemoryChunkLayout::kWastedMemoryOffset);
  STATIC_ASSERT(offsetof(BasicMemoryChunk, high_water_mark_) ==
                MemoryChunkLayout::kHighWaterMarkOffset);
  STATIC_ASSERT(offsetof(BasicMemoryChunk, owner_) ==
                MemoryChunkLayout::kOwnerOffset);
  STATIC_ASSERT(offsetof(BasicMemoryChunk, reservation_) ==
                MemoryChunkLayout::kReservationOffset);
};

}  // namespace internal
}  // namespace v8