Upgrade to 3.29
Update V8 to 3.29.88.17 and update makefiles to support building on
all the relevant platforms.
Bug: 17370214
Change-Id: Ia3407c157fd8d72a93e23d8318ccaf6ecf77fa4e
diff --git a/src/heap/spaces.h b/src/heap/spaces.h
new file mode 100644
index 0000000..9ecb3c4
--- /dev/null
+++ b/src/heap/spaces.h
@@ -0,0 +1,2886 @@
+// 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_H_
+#define V8_HEAP_SPACES_H_
+
+#include "src/allocation.h"
+#include "src/base/atomicops.h"
+#include "src/base/bits.h"
+#include "src/base/platform/mutex.h"
+#include "src/hashmap.h"
+#include "src/list.h"
+#include "src/log.h"
+#include "src/utils.h"
+
+namespace v8 {
+namespace internal {
+
+class Isolate;
+
+// -----------------------------------------------------------------------------
+// Heap structures:
+//
+// A JS heap consists of a young generation, an old generation, and a large
+// object space. The young generation is divided into two semispaces. A
+// scavenger implements Cheney's copying algorithm. The old generation is
+// separated into a map space and an old object space. The map space contains
+// all (and only) map objects, the rest of old objects go into the old space.
+// The old generation is collected by a mark-sweep-compact collector.
+//
+// The semispaces of the young generation are contiguous. The old and map
+// spaces consists of a list of pages. A page has a page header and an object
+// area.
+//
+// There is a separate large object space for objects larger than
+// Page::kMaxHeapObjectSize, so that they do not have to move during
+// collection. The large object space is paged. Pages in large object space
+// may be larger than the page size.
+//
+// A store-buffer based write barrier is used to keep track of intergenerational
+// references. See heap/store-buffer.h.
+//
+// During scavenges and mark-sweep collections we sometimes (after a store
+// buffer overflow) iterate intergenerational pointers without decoding heap
+// object maps so if the page belongs to old pointer space or large object
+// space it is essential to guarantee that the page does not contain any
+// garbage pointers to new space: every pointer aligned word which satisfies
+// the Heap::InNewSpace() predicate must be a pointer to a live heap object in
+// new space. Thus objects in old pointer and large object spaces should have a
+// special layout (e.g. no bare integer fields). This requirement does not
+// apply to map space which is iterated in a special fashion. However we still
+// require pointer fields of dead maps to be cleaned.
+//
+// To enable lazy cleaning of old space pages we can mark chunks of the page
+// as being garbage. Garbage sections are marked with a special map. These
+// sections are skipped when scanning the page, even if we are otherwise
+// scanning without regard for object boundaries. Garbage sections are chained
+// together to form a free list after a GC. Garbage sections created outside
+// of GCs by object trunctation etc. may not be in the free list chain. Very
+// small free spaces are ignored, they need only be cleaned of bogus pointers
+// into new space.
+//
+// Each page may have up to one special garbage section. The start of this
+// section is denoted by the top field in the space. The end of the section
+// is denoted by the limit field in the space. This special garbage section
+// is not marked with a free space map in the data. The point of this section
+// is to enable linear allocation without having to constantly update the byte
+// array every time the top field is updated and a new object is created. The
+// special garbage section is not in the chain of garbage sections.
+//
+// Since the top and limit fields are in the space, not the page, only one page
+// has a special garbage section, and if the top and limit are equal then there
+// is no special garbage section.
+
+// Some assertion macros used in the debugging mode.
+
+#define DCHECK_PAGE_ALIGNED(address) \
+ DCHECK((OffsetFrom(address) & Page::kPageAlignmentMask) == 0)
+
+#define DCHECK_OBJECT_ALIGNED(address) \
+ DCHECK((OffsetFrom(address) & kObjectAlignmentMask) == 0)
+
+#define DCHECK_OBJECT_SIZE(size) \
+ DCHECK((0 < size) && (size <= Page::kMaxRegularHeapObjectSize))
+
+#define DCHECK_PAGE_OFFSET(offset) \
+ DCHECK((Page::kObjectStartOffset <= offset) && (offset <= Page::kPageSize))
+
+#define DCHECK_MAP_PAGE_INDEX(index) \
+ DCHECK((0 <= index) && (index <= MapSpace::kMaxMapPageIndex))
+
+
+class PagedSpace;
+class MemoryAllocator;
+class AllocationInfo;
+class Space;
+class FreeList;
+class MemoryChunk;
+
+class MarkBit {
+ public:
+ typedef uint32_t CellType;
+
+ inline MarkBit(CellType* cell, CellType mask, bool data_only)
+ : cell_(cell), mask_(mask), data_only_(data_only) {}
+
+ inline CellType* cell() { return cell_; }
+ inline CellType mask() { return mask_; }
+
+#ifdef DEBUG
+ bool operator==(const MarkBit& other) {
+ return cell_ == other.cell_ && mask_ == other.mask_;
+ }
+#endif
+
+ inline void Set() { *cell_ |= mask_; }
+ inline bool Get() { return (*cell_ & mask_) != 0; }
+ inline void Clear() { *cell_ &= ~mask_; }
+
+ inline bool data_only() { return data_only_; }
+
+ inline MarkBit Next() {
+ CellType new_mask = mask_ << 1;
+ if (new_mask == 0) {
+ return MarkBit(cell_ + 1, 1, data_only_);
+ } else {
+ return MarkBit(cell_, new_mask, data_only_);
+ }
+ }
+
+ private:
+ CellType* cell_;
+ CellType mask_;
+ // This boolean indicates that the object is in a data-only space with no
+ // pointers. This enables some optimizations when marking.
+ // It is expected that this field is inlined and turned into control flow
+ // at the place where the MarkBit object is created.
+ bool data_only_;
+};
+
+
+// Bitmap is a sequence of cells each containing fixed number of bits.
+class Bitmap {
+ public:
+ static const uint32_t kBitsPerCell = 32;
+ static const uint32_t kBitsPerCellLog2 = 5;
+ static const uint32_t kBitIndexMask = kBitsPerCell - 1;
+ static const uint32_t kBytesPerCell = kBitsPerCell / kBitsPerByte;
+ static const uint32_t kBytesPerCellLog2 = kBitsPerCellLog2 - kBitsPerByteLog2;
+
+ static const size_t kLength = (1 << kPageSizeBits) >> (kPointerSizeLog2);
+
+ static const size_t kSize =
+ (1 << kPageSizeBits) >> (kPointerSizeLog2 + kBitsPerByteLog2);
+
+
+ static int CellsForLength(int length) {
+ return (length + kBitsPerCell - 1) >> kBitsPerCellLog2;
+ }
+
+ int CellsCount() { return CellsForLength(kLength); }
+
+ static int SizeFor(int cells_count) {
+ return sizeof(MarkBit::CellType) * cells_count;
+ }
+
+ INLINE(static uint32_t IndexToCell(uint32_t index)) {
+ return index >> kBitsPerCellLog2;
+ }
+
+ INLINE(static uint32_t CellToIndex(uint32_t index)) {
+ return index << kBitsPerCellLog2;
+ }
+
+ INLINE(static uint32_t CellAlignIndex(uint32_t index)) {
+ return (index + kBitIndexMask) & ~kBitIndexMask;
+ }
+
+ INLINE(MarkBit::CellType* cells()) {
+ return reinterpret_cast<MarkBit::CellType*>(this);
+ }
+
+ INLINE(Address address()) { return reinterpret_cast<Address>(this); }
+
+ INLINE(static Bitmap* FromAddress(Address addr)) {
+ return reinterpret_cast<Bitmap*>(addr);
+ }
+
+ inline MarkBit MarkBitFromIndex(uint32_t index, bool data_only = false) {
+ MarkBit::CellType mask = 1 << (index & kBitIndexMask);
+ MarkBit::CellType* cell = this->cells() + (index >> kBitsPerCellLog2);
+ return MarkBit(cell, mask, data_only);
+ }
+
+ static inline void Clear(MemoryChunk* chunk);
+
+ static void PrintWord(uint32_t word, uint32_t himask = 0) {
+ for (uint32_t mask = 1; mask != 0; mask <<= 1) {
+ if ((mask & himask) != 0) PrintF("[");
+ PrintF((mask & word) ? "1" : "0");
+ if ((mask & himask) != 0) PrintF("]");
+ }
+ }
+
+ class CellPrinter {
+ public:
+ CellPrinter() : seq_start(0), seq_type(0), seq_length(0) {}
+
+ void Print(uint32_t pos, uint32_t cell) {
+ if (cell == seq_type) {
+ seq_length++;
+ return;
+ }
+
+ Flush();
+
+ if (IsSeq(cell)) {
+ seq_start = pos;
+ seq_length = 0;
+ seq_type = cell;
+ return;
+ }
+
+ PrintF("%d: ", pos);
+ PrintWord(cell);
+ PrintF("\n");
+ }
+
+ void Flush() {
+ if (seq_length > 0) {
+ PrintF("%d: %dx%d\n", seq_start, seq_type == 0 ? 0 : 1,
+ seq_length * kBitsPerCell);
+ seq_length = 0;
+ }
+ }
+
+ static bool IsSeq(uint32_t cell) { return cell == 0 || cell == 0xFFFFFFFF; }
+
+ private:
+ uint32_t seq_start;
+ uint32_t seq_type;
+ uint32_t seq_length;
+ };
+
+ void Print() {
+ CellPrinter printer;
+ for (int i = 0; i < CellsCount(); i++) {
+ printer.Print(i, cells()[i]);
+ }
+ printer.Flush();
+ PrintF("\n");
+ }
+
+ bool IsClean() {
+ for (int i = 0; i < CellsCount(); i++) {
+ if (cells()[i] != 0) {
+ return false;
+ }
+ }
+ return true;
+ }
+};
+
+
+class SkipList;
+class SlotsBuffer;
+
+// MemoryChunk represents a memory region owned by a specific space.
+// It is divided into the header and the body. Chunk start is always
+// 1MB aligned. Start of the body is aligned so it can accommodate
+// any heap object.
+class MemoryChunk {
+ public:
+ // Only works if the pointer is in the first kPageSize of the MemoryChunk.
+ static MemoryChunk* FromAddress(Address a) {
+ return reinterpret_cast<MemoryChunk*>(OffsetFrom(a) & ~kAlignmentMask);
+ }
+ static const MemoryChunk* FromAddress(const byte* a) {
+ return reinterpret_cast<const MemoryChunk*>(OffsetFrom(a) &
+ ~kAlignmentMask);
+ }
+
+ // Only works for addresses in pointer spaces, not data or code spaces.
+ static inline MemoryChunk* FromAnyPointerAddress(Heap* heap, Address addr);
+
+ Address address() { return reinterpret_cast<Address>(this); }
+
+ bool is_valid() { return address() != NULL; }
+
+ MemoryChunk* next_chunk() const {
+ return reinterpret_cast<MemoryChunk*>(base::Acquire_Load(&next_chunk_));
+ }
+
+ MemoryChunk* prev_chunk() const {
+ return reinterpret_cast<MemoryChunk*>(base::Acquire_Load(&prev_chunk_));
+ }
+
+ void set_next_chunk(MemoryChunk* next) {
+ base::Release_Store(&next_chunk_, reinterpret_cast<base::AtomicWord>(next));
+ }
+
+ void set_prev_chunk(MemoryChunk* prev) {
+ base::Release_Store(&prev_chunk_, reinterpret_cast<base::AtomicWord>(prev));
+ }
+
+ Space* owner() const {
+ if ((reinterpret_cast<intptr_t>(owner_) & kPageHeaderTagMask) ==
+ kPageHeaderTag) {
+ return reinterpret_cast<Space*>(reinterpret_cast<intptr_t>(owner_) -
+ kPageHeaderTag);
+ } else {
+ return NULL;
+ }
+ }
+
+ void set_owner(Space* space) {
+ DCHECK((reinterpret_cast<intptr_t>(space) & kPageHeaderTagMask) == 0);
+ owner_ = reinterpret_cast<Address>(space) + kPageHeaderTag;
+ DCHECK((reinterpret_cast<intptr_t>(owner_) & kPageHeaderTagMask) ==
+ kPageHeaderTag);
+ }
+
+ base::VirtualMemory* reserved_memory() { return &reservation_; }
+
+ void InitializeReservedMemory() { reservation_.Reset(); }
+
+ void set_reserved_memory(base::VirtualMemory* reservation) {
+ DCHECK_NOT_NULL(reservation);
+ reservation_.TakeControl(reservation);
+ }
+
+ bool scan_on_scavenge() { return IsFlagSet(SCAN_ON_SCAVENGE); }
+ void initialize_scan_on_scavenge(bool scan) {
+ if (scan) {
+ SetFlag(SCAN_ON_SCAVENGE);
+ } else {
+ ClearFlag(SCAN_ON_SCAVENGE);
+ }
+ }
+ inline void set_scan_on_scavenge(bool scan);
+
+ int store_buffer_counter() { return store_buffer_counter_; }
+ void set_store_buffer_counter(int counter) {
+ store_buffer_counter_ = counter;
+ }
+
+ bool Contains(Address addr) {
+ return addr >= area_start() && addr < area_end();
+ }
+
+ // Checks whether addr can be a limit of addresses in this page.
+ // It's a limit if it's in the page, or if it's just after the
+ // last byte of the page.
+ bool ContainsLimit(Address addr) {
+ return addr >= area_start() && addr <= area_end();
+ }
+
+ // Every n write barrier invocations we go to runtime even though
+ // we could have handled it in generated code. This lets us check
+ // whether we have hit the limit and should do some more marking.
+ static const int kWriteBarrierCounterGranularity = 500;
+
+ enum MemoryChunkFlags {
+ IS_EXECUTABLE,
+ ABOUT_TO_BE_FREED,
+ POINTERS_TO_HERE_ARE_INTERESTING,
+ POINTERS_FROM_HERE_ARE_INTERESTING,
+ SCAN_ON_SCAVENGE,
+ IN_FROM_SPACE, // Mutually exclusive with IN_TO_SPACE.
+ IN_TO_SPACE, // All pages in new space has one of these two set.
+ NEW_SPACE_BELOW_AGE_MARK,
+ CONTAINS_ONLY_DATA,
+ EVACUATION_CANDIDATE,
+ RESCAN_ON_EVACUATION,
+
+ // WAS_SWEPT indicates that marking bits have been cleared by the sweeper,
+ // otherwise marking bits are still intact.
+ WAS_SWEPT,
+
+ // Large objects can have a progress bar in their page header. These object
+ // are scanned in increments and will be kept black while being scanned.
+ // Even if the mutator writes to them they will be kept black and a white
+ // to grey transition is performed in the value.
+ HAS_PROGRESS_BAR,
+
+ // Last flag, keep at bottom.
+ NUM_MEMORY_CHUNK_FLAGS
+ };
+
+
+ static const int kPointersToHereAreInterestingMask =
+ 1 << POINTERS_TO_HERE_ARE_INTERESTING;
+
+ static const int kPointersFromHereAreInterestingMask =
+ 1 << POINTERS_FROM_HERE_ARE_INTERESTING;
+
+ static const int kEvacuationCandidateMask = 1 << EVACUATION_CANDIDATE;
+
+ static const int kSkipEvacuationSlotsRecordingMask =
+ (1 << EVACUATION_CANDIDATE) | (1 << RESCAN_ON_EVACUATION) |
+ (1 << IN_FROM_SPACE) | (1 << IN_TO_SPACE);
+
+
+ void SetFlag(int flag) { flags_ |= static_cast<uintptr_t>(1) << flag; }
+
+ void ClearFlag(int flag) { flags_ &= ~(static_cast<uintptr_t>(1) << flag); }
+
+ void SetFlagTo(int flag, bool value) {
+ if (value) {
+ SetFlag(flag);
+ } else {
+ ClearFlag(flag);
+ }
+ }
+
+ bool IsFlagSet(int flag) {
+ return (flags_ & (static_cast<uintptr_t>(1) << flag)) != 0;
+ }
+
+ // Set or clear multiple flags at a time. The flags in the mask
+ // are set to the value in "flags", the rest retain the current value
+ // in flags_.
+ void SetFlags(intptr_t flags, intptr_t mask) {
+ flags_ = (flags_ & ~mask) | (flags & mask);
+ }
+
+ // Return all current flags.
+ intptr_t GetFlags() { return flags_; }
+
+
+ // SWEEPING_DONE - The page state when sweeping is complete or sweeping must
+ // not be performed on that page.
+ // SWEEPING_FINALIZE - A sweeper thread is done sweeping this page and will
+ // not touch the page memory anymore.
+ // SWEEPING_IN_PROGRESS - This page is currently swept by a sweeper thread.
+ // SWEEPING_PENDING - This page is ready for parallel sweeping.
+ enum ParallelSweepingState {
+ SWEEPING_DONE,
+ SWEEPING_FINALIZE,
+ SWEEPING_IN_PROGRESS,
+ SWEEPING_PENDING
+ };
+
+ ParallelSweepingState parallel_sweeping() {
+ return static_cast<ParallelSweepingState>(
+ base::Acquire_Load(¶llel_sweeping_));
+ }
+
+ void set_parallel_sweeping(ParallelSweepingState state) {
+ base::Release_Store(¶llel_sweeping_, state);
+ }
+
+ bool TryParallelSweeping() {
+ return base::Acquire_CompareAndSwap(¶llel_sweeping_, SWEEPING_PENDING,
+ SWEEPING_IN_PROGRESS) ==
+ SWEEPING_PENDING;
+ }
+
+ bool SweepingCompleted() { return parallel_sweeping() <= SWEEPING_FINALIZE; }
+
+ // Manage live byte count (count of bytes known to be live,
+ // because they are marked black).
+ void ResetLiveBytes() {
+ if (FLAG_gc_verbose) {
+ PrintF("ResetLiveBytes:%p:%x->0\n", static_cast<void*>(this),
+ live_byte_count_);
+ }
+ live_byte_count_ = 0;
+ }
+ void IncrementLiveBytes(int by) {
+ if (FLAG_gc_verbose) {
+ printf("UpdateLiveBytes:%p:%x%c=%x->%x\n", static_cast<void*>(this),
+ live_byte_count_, ((by < 0) ? '-' : '+'), ((by < 0) ? -by : by),
+ live_byte_count_ + by);
+ }
+ live_byte_count_ += by;
+ DCHECK_LE(static_cast<unsigned>(live_byte_count_), size_);
+ }
+ int LiveBytes() {
+ DCHECK(static_cast<unsigned>(live_byte_count_) <= size_);
+ return live_byte_count_;
+ }
+
+ int write_barrier_counter() {
+ return static_cast<int>(write_barrier_counter_);
+ }
+
+ void set_write_barrier_counter(int counter) {
+ write_barrier_counter_ = counter;
+ }
+
+ int progress_bar() {
+ DCHECK(IsFlagSet(HAS_PROGRESS_BAR));
+ return progress_bar_;
+ }
+
+ void set_progress_bar(int progress_bar) {
+ DCHECK(IsFlagSet(HAS_PROGRESS_BAR));
+ progress_bar_ = progress_bar;
+ }
+
+ void ResetProgressBar() {
+ if (IsFlagSet(MemoryChunk::HAS_PROGRESS_BAR)) {
+ set_progress_bar(0);
+ ClearFlag(MemoryChunk::HAS_PROGRESS_BAR);
+ }
+ }
+
+ bool IsLeftOfProgressBar(Object** slot) {
+ Address slot_address = reinterpret_cast<Address>(slot);
+ DCHECK(slot_address > this->address());
+ return (slot_address - (this->address() + kObjectStartOffset)) <
+ progress_bar();
+ }
+
+ static void IncrementLiveBytesFromGC(Address address, int by) {
+ MemoryChunk::FromAddress(address)->IncrementLiveBytes(by);
+ }
+
+ static void IncrementLiveBytesFromMutator(Address address, int by);
+
+ static const intptr_t kAlignment =
+ (static_cast<uintptr_t>(1) << kPageSizeBits);
+
+ static const intptr_t kAlignmentMask = kAlignment - 1;
+
+ static const intptr_t kSizeOffset = 0;
+
+ static const intptr_t kLiveBytesOffset =
+ kSizeOffset + kPointerSize + kPointerSize + kPointerSize + kPointerSize +
+ kPointerSize + kPointerSize + kPointerSize + kPointerSize + kIntSize;
+
+ static const size_t kSlotsBufferOffset = kLiveBytesOffset + kIntSize;
+
+ static const size_t kWriteBarrierCounterOffset =
+ kSlotsBufferOffset + kPointerSize + kPointerSize;
+
+ static const size_t kHeaderSize =
+ kWriteBarrierCounterOffset + kPointerSize + kIntSize + kIntSize +
+ kPointerSize + 5 * kPointerSize + kPointerSize + kPointerSize;
+
+ static const int kBodyOffset =
+ CODE_POINTER_ALIGN(kHeaderSize + Bitmap::kSize);
+
+ // The start offset of the object area in a page. Aligned to both maps and
+ // code alignment to be suitable for both. Also aligned to 32 words because
+ // the marking bitmap is arranged in 32 bit chunks.
+ static const int kObjectStartAlignment = 32 * kPointerSize;
+ static const int kObjectStartOffset =
+ kBodyOffset - 1 +
+ (kObjectStartAlignment - (kBodyOffset - 1) % kObjectStartAlignment);
+
+ size_t size() const { return size_; }
+
+ void set_size(size_t size) { size_ = size; }
+
+ void SetArea(Address area_start, Address area_end) {
+ area_start_ = area_start;
+ area_end_ = area_end;
+ }
+
+ Executability executable() {
+ return IsFlagSet(IS_EXECUTABLE) ? EXECUTABLE : NOT_EXECUTABLE;
+ }
+
+ bool ContainsOnlyData() { return IsFlagSet(CONTAINS_ONLY_DATA); }
+
+ bool InNewSpace() {
+ return (flags_ & ((1 << IN_FROM_SPACE) | (1 << IN_TO_SPACE))) != 0;
+ }
+
+ bool InToSpace() { return IsFlagSet(IN_TO_SPACE); }
+
+ bool InFromSpace() { return IsFlagSet(IN_FROM_SPACE); }
+
+ // ---------------------------------------------------------------------
+ // Markbits support
+
+ inline Bitmap* markbits() {
+ return Bitmap::FromAddress(address() + kHeaderSize);
+ }
+
+ void PrintMarkbits() { markbits()->Print(); }
+
+ inline uint32_t AddressToMarkbitIndex(Address addr) {
+ return static_cast<uint32_t>(addr - this->address()) >> kPointerSizeLog2;
+ }
+
+ inline static uint32_t FastAddressToMarkbitIndex(Address addr) {
+ const intptr_t offset = reinterpret_cast<intptr_t>(addr) & kAlignmentMask;
+
+ return static_cast<uint32_t>(offset) >> kPointerSizeLog2;
+ }
+
+ inline Address MarkbitIndexToAddress(uint32_t index) {
+ return this->address() + (index << kPointerSizeLog2);
+ }
+
+ void InsertAfter(MemoryChunk* other);
+ void Unlink();
+
+ inline Heap* heap() const { return heap_; }
+
+ static const int kFlagsOffset = kPointerSize;
+
+ bool IsEvacuationCandidate() { return IsFlagSet(EVACUATION_CANDIDATE); }
+
+ bool ShouldSkipEvacuationSlotRecording() {
+ return (flags_ & kSkipEvacuationSlotsRecordingMask) != 0;
+ }
+
+ inline SkipList* skip_list() { return skip_list_; }
+
+ inline void set_skip_list(SkipList* skip_list) { skip_list_ = skip_list; }
+
+ inline SlotsBuffer* slots_buffer() { return slots_buffer_; }
+
+ inline SlotsBuffer** slots_buffer_address() { return &slots_buffer_; }
+
+ void MarkEvacuationCandidate() {
+ DCHECK(slots_buffer_ == NULL);
+ SetFlag(EVACUATION_CANDIDATE);
+ }
+
+ void ClearEvacuationCandidate() {
+ DCHECK(slots_buffer_ == NULL);
+ ClearFlag(EVACUATION_CANDIDATE);
+ }
+
+ Address area_start() { return area_start_; }
+ Address area_end() { return area_end_; }
+ int area_size() { return static_cast<int>(area_end() - area_start()); }
+ bool CommitArea(size_t requested);
+
+ // Approximate amount of physical memory committed for this chunk.
+ size_t CommittedPhysicalMemory() { return high_water_mark_; }
+
+ static inline void UpdateHighWaterMark(Address mark);
+
+ protected:
+ size_t size_;
+ intptr_t flags_;
+
+ // Start and end of allocatable memory on this chunk.
+ Address area_start_;
+ Address area_end_;
+
+ // If the chunk needs to remember its memory reservation, it is stored here.
+ base::VirtualMemory reservation_;
+ // The identity of the owning space. This is tagged as a failure pointer, but
+ // no failure can be in an object, so this can be distinguished from any entry
+ // in a fixed array.
+ Address owner_;
+ Heap* heap_;
+ // Used by the store buffer to keep track of which pages to mark scan-on-
+ // scavenge.
+ int store_buffer_counter_;
+ // Count of bytes marked black on page.
+ int live_byte_count_;
+ SlotsBuffer* slots_buffer_;
+ SkipList* skip_list_;
+ intptr_t write_barrier_counter_;
+ // Used by the incremental marker to keep track of the scanning progress in
+ // large objects that have a progress bar and are scanned in increments.
+ int progress_bar_;
+ // Assuming the initial allocation on a page is sequential,
+ // count highest number of bytes ever allocated on the page.
+ int high_water_mark_;
+
+ base::AtomicWord parallel_sweeping_;
+
+ // PagedSpace free-list statistics.
+ intptr_t available_in_small_free_list_;
+ intptr_t available_in_medium_free_list_;
+ intptr_t available_in_large_free_list_;
+ intptr_t available_in_huge_free_list_;
+ intptr_t non_available_small_blocks_;
+
+ static MemoryChunk* Initialize(Heap* heap, Address base, size_t size,
+ Address area_start, Address area_end,
+ Executability executable, Space* owner);
+
+ private:
+ // next_chunk_ holds a pointer of type MemoryChunk
+ base::AtomicWord next_chunk_;
+ // prev_chunk_ holds a pointer of type MemoryChunk
+ base::AtomicWord prev_chunk_;
+
+ friend class MemoryAllocator;
+};
+
+
+STATIC_ASSERT(sizeof(MemoryChunk) <= MemoryChunk::kHeaderSize);
+
+
+// -----------------------------------------------------------------------------
+// A page is a memory chunk of a size 1MB. Large object pages may be larger.
+//
+// The only way to get a page pointer is by calling factory methods:
+// Page* p = Page::FromAddress(addr); or
+// Page* p = Page::FromAllocationTop(top);
+class Page : public MemoryChunk {
+ public:
+ // Returns the page containing a given address. The address ranges
+ // from [page_addr .. page_addr + kPageSize[
+ // This only works if the object is in fact in a page. See also MemoryChunk::
+ // FromAddress() and FromAnyAddress().
+ INLINE(static Page* FromAddress(Address a)) {
+ return reinterpret_cast<Page*>(OffsetFrom(a) & ~kPageAlignmentMask);
+ }
+
+ // Returns the page containing an allocation top. Because an allocation
+ // top address can be the upper bound of the page, we need to subtract
+ // it with kPointerSize first. The address ranges from
+ // [page_addr + kObjectStartOffset .. page_addr + kPageSize].
+ INLINE(static Page* FromAllocationTop(Address top)) {
+ Page* p = FromAddress(top - kPointerSize);
+ return p;
+ }
+
+ // Returns the next page in the chain of pages owned by a space.
+ inline Page* next_page();
+ inline Page* prev_page();
+ inline void set_next_page(Page* page);
+ inline void set_prev_page(Page* page);
+
+ // Checks whether an address is page aligned.
+ static bool IsAlignedToPageSize(Address a) {
+ return 0 == (OffsetFrom(a) & kPageAlignmentMask);
+ }
+
+ // Returns the offset of a given address to this page.
+ INLINE(int Offset(Address a)) {
+ int offset = static_cast<int>(a - address());
+ return offset;
+ }
+
+ // Returns the address for a given offset to the this page.
+ Address OffsetToAddress(int offset) {
+ DCHECK_PAGE_OFFSET(offset);
+ return address() + offset;
+ }
+
+ // ---------------------------------------------------------------------
+
+ // Page size in bytes. This must be a multiple of the OS page size.
+ static const int kPageSize = 1 << kPageSizeBits;
+
+ // Maximum object size that fits in a page. Objects larger than that size
+ // are allocated in large object space and are never moved in memory. This
+ // also applies to new space allocation, since objects are never migrated
+ // from new space to large object space. Takes double alignment into account.
+ static const int kMaxRegularHeapObjectSize = kPageSize - kObjectStartOffset;
+
+ // Page size mask.
+ static const intptr_t kPageAlignmentMask = (1 << kPageSizeBits) - 1;
+
+ inline void ClearGCFields();
+
+ static inline Page* Initialize(Heap* heap, MemoryChunk* chunk,
+ Executability executable, PagedSpace* owner);
+
+ void InitializeAsAnchor(PagedSpace* owner);
+
+ bool WasSwept() { return IsFlagSet(WAS_SWEPT); }
+ void SetWasSwept() { SetFlag(WAS_SWEPT); }
+ void ClearWasSwept() { ClearFlag(WAS_SWEPT); }
+
+ void ResetFreeListStatistics();
+
+#define FRAGMENTATION_STATS_ACCESSORS(type, name) \
+ type name() { return name##_; } \
+ void set_##name(type name) { name##_ = name; } \
+ void add_##name(type name) { name##_ += name; }
+
+ FRAGMENTATION_STATS_ACCESSORS(intptr_t, non_available_small_blocks)
+ FRAGMENTATION_STATS_ACCESSORS(intptr_t, available_in_small_free_list)
+ FRAGMENTATION_STATS_ACCESSORS(intptr_t, available_in_medium_free_list)
+ FRAGMENTATION_STATS_ACCESSORS(intptr_t, available_in_large_free_list)
+ FRAGMENTATION_STATS_ACCESSORS(intptr_t, available_in_huge_free_list)
+
+#undef FRAGMENTATION_STATS_ACCESSORS
+
+#ifdef DEBUG
+ void Print();
+#endif // DEBUG
+
+ friend class MemoryAllocator;
+};
+
+
+STATIC_ASSERT(sizeof(Page) <= MemoryChunk::kHeaderSize);
+
+
+class LargePage : public MemoryChunk {
+ public:
+ HeapObject* GetObject() { return HeapObject::FromAddress(area_start()); }
+
+ inline LargePage* next_page() const {
+ return static_cast<LargePage*>(next_chunk());
+ }
+
+ inline void set_next_page(LargePage* page) { set_next_chunk(page); }
+
+ private:
+ static inline LargePage* Initialize(Heap* heap, MemoryChunk* chunk);
+
+ friend class MemoryAllocator;
+};
+
+STATIC_ASSERT(sizeof(LargePage) <= MemoryChunk::kHeaderSize);
+
+// ----------------------------------------------------------------------------
+// Space is the abstract superclass for all allocation spaces.
+class Space : public Malloced {
+ public:
+ Space(Heap* heap, AllocationSpace id, Executability executable)
+ : heap_(heap), id_(id), executable_(executable) {}
+
+ virtual ~Space() {}
+
+ Heap* heap() const { return heap_; }
+
+ // Does the space need executable memory?
+ Executability executable() { return executable_; }
+
+ // Identity used in error reporting.
+ AllocationSpace identity() { return id_; }
+
+ // Returns allocated size.
+ virtual intptr_t Size() = 0;
+
+ // Returns size of objects. Can differ from the allocated size
+ // (e.g. see LargeObjectSpace).
+ virtual intptr_t SizeOfObjects() { return Size(); }
+
+ virtual int RoundSizeDownToObjectAlignment(int size) {
+ if (id_ == CODE_SPACE) {
+ return RoundDown(size, kCodeAlignment);
+ } else {
+ return RoundDown(size, kPointerSize);
+ }
+ }
+
+#ifdef DEBUG
+ virtual void Print() = 0;
+#endif
+
+ private:
+ Heap* heap_;
+ AllocationSpace id_;
+ Executability executable_;
+};
+
+
+// ----------------------------------------------------------------------------
+// All heap objects containing executable code (code objects) must be allocated
+// from a 2 GB range of memory, so that they can call each other using 32-bit
+// displacements. This happens automatically on 32-bit platforms, where 32-bit
+// displacements cover the entire 4GB virtual address space. On 64-bit
+// platforms, we support this using the CodeRange object, which reserves and
+// manages a range of virtual memory.
+class CodeRange {
+ public:
+ explicit CodeRange(Isolate* isolate);
+ ~CodeRange() { TearDown(); }
+
+ // Reserves a range of virtual memory, but does not commit any of it.
+ // Can only be called once, at heap initialization time.
+ // Returns false on failure.
+ bool SetUp(size_t requested_size);
+
+ // Frees the range of virtual memory, and frees the data structures used to
+ // manage it.
+ void TearDown();
+
+ bool valid() { return code_range_ != NULL; }
+ Address start() {
+ DCHECK(valid());
+ return static_cast<Address>(code_range_->address());
+ }
+ bool contains(Address address) {
+ if (!valid()) return false;
+ Address start = static_cast<Address>(code_range_->address());
+ return start <= address && address < start + code_range_->size();
+ }
+
+ // Allocates a chunk of memory from the large-object portion of
+ // the code range. On platforms with no separate code range, should
+ // not be called.
+ MUST_USE_RESULT Address AllocateRawMemory(const size_t requested_size,
+ const size_t commit_size,
+ size_t* allocated);
+ bool CommitRawMemory(Address start, size_t length);
+ bool UncommitRawMemory(Address start, size_t length);
+ void FreeRawMemory(Address buf, size_t length);
+
+ private:
+ Isolate* isolate_;
+
+ // The reserved range of virtual memory that all code objects are put in.
+ base::VirtualMemory* code_range_;
+ // Plain old data class, just a struct plus a constructor.
+ class FreeBlock {
+ public:
+ FreeBlock(Address start_arg, size_t size_arg)
+ : start(start_arg), size(size_arg) {
+ DCHECK(IsAddressAligned(start, MemoryChunk::kAlignment));
+ DCHECK(size >= static_cast<size_t>(Page::kPageSize));
+ }
+ FreeBlock(void* start_arg, size_t size_arg)
+ : start(static_cast<Address>(start_arg)), size(size_arg) {
+ DCHECK(IsAddressAligned(start, MemoryChunk::kAlignment));
+ DCHECK(size >= static_cast<size_t>(Page::kPageSize));
+ }
+
+ Address start;
+ size_t size;
+ };
+
+ // Freed blocks of memory are added to the free list. When the allocation
+ // list is exhausted, the free list is sorted and merged to make the new
+ // allocation list.
+ List<FreeBlock> free_list_;
+ // Memory is allocated from the free blocks on the allocation list.
+ // The block at current_allocation_block_index_ is the current block.
+ List<FreeBlock> allocation_list_;
+ int current_allocation_block_index_;
+
+ // Finds a block on the allocation list that contains at least the
+ // requested amount of memory. If none is found, sorts and merges
+ // the existing free memory blocks, and searches again.
+ // If none can be found, returns false.
+ bool GetNextAllocationBlock(size_t requested);
+ // Compares the start addresses of two free blocks.
+ static int CompareFreeBlockAddress(const FreeBlock* left,
+ const FreeBlock* right);
+
+ DISALLOW_COPY_AND_ASSIGN(CodeRange);
+};
+
+
+class SkipList {
+ public:
+ SkipList() { Clear(); }
+
+ void Clear() {
+ for (int idx = 0; idx < kSize; idx++) {
+ starts_[idx] = reinterpret_cast<Address>(-1);
+ }
+ }
+
+ Address StartFor(Address addr) { return starts_[RegionNumber(addr)]; }
+
+ void AddObject(Address addr, int size) {
+ int start_region = RegionNumber(addr);
+ int end_region = RegionNumber(addr + size - kPointerSize);
+ for (int idx = start_region; idx <= end_region; idx++) {
+ if (starts_[idx] > addr) starts_[idx] = addr;
+ }
+ }
+
+ static inline int RegionNumber(Address addr) {
+ return (OffsetFrom(addr) & Page::kPageAlignmentMask) >> kRegionSizeLog2;
+ }
+
+ static void Update(Address addr, int size) {
+ Page* page = Page::FromAddress(addr);
+ SkipList* list = page->skip_list();
+ if (list == NULL) {
+ list = new SkipList();
+ page->set_skip_list(list);
+ }
+
+ list->AddObject(addr, size);
+ }
+
+ private:
+ static const int kRegionSizeLog2 = 13;
+ static const int kRegionSize = 1 << kRegionSizeLog2;
+ static const int kSize = Page::kPageSize / kRegionSize;
+
+ STATIC_ASSERT(Page::kPageSize % kRegionSize == 0);
+
+ Address starts_[kSize];
+};
+
+
+// ----------------------------------------------------------------------------
+// A space acquires chunks of memory from the operating system. The memory
+// allocator allocated and deallocates pages for the paged heap spaces and large
+// pages for large object space.
+//
+// Each space has to manage it's own pages.
+//
+class MemoryAllocator {
+ public:
+ explicit MemoryAllocator(Isolate* isolate);
+
+ // Initializes its internal bookkeeping structures.
+ // Max capacity of the total space and executable memory limit.
+ bool SetUp(intptr_t max_capacity, intptr_t capacity_executable);
+
+ void TearDown();
+
+ Page* AllocatePage(intptr_t size, PagedSpace* owner,
+ Executability executable);
+
+ LargePage* AllocateLargePage(intptr_t object_size, Space* owner,
+ Executability executable);
+
+ void Free(MemoryChunk* chunk);
+
+ // Returns the maximum available bytes of heaps.
+ intptr_t Available() { return capacity_ < size_ ? 0 : capacity_ - size_; }
+
+ // Returns allocated spaces in bytes.
+ intptr_t Size() { return size_; }
+
+ // Returns the maximum available executable bytes of heaps.
+ intptr_t AvailableExecutable() {
+ if (capacity_executable_ < size_executable_) return 0;
+ return capacity_executable_ - size_executable_;
+ }
+
+ // Returns allocated executable spaces in bytes.
+ intptr_t SizeExecutable() { return size_executable_; }
+
+ // Returns maximum available bytes that the old space can have.
+ intptr_t MaxAvailable() {
+ return (Available() / Page::kPageSize) * Page::kMaxRegularHeapObjectSize;
+ }
+
+ // Returns an indication of whether a pointer is in a space that has
+ // been allocated by this MemoryAllocator.
+ V8_INLINE bool IsOutsideAllocatedSpace(const void* address) const {
+ return address < lowest_ever_allocated_ ||
+ address >= highest_ever_allocated_;
+ }
+
+#ifdef DEBUG
+ // Reports statistic info of the space.
+ void ReportStatistics();
+#endif
+
+ // Returns a MemoryChunk in which the memory region from commit_area_size to
+ // reserve_area_size of the chunk area is reserved but not committed, it
+ // could be committed later by calling MemoryChunk::CommitArea.
+ MemoryChunk* AllocateChunk(intptr_t reserve_area_size,
+ intptr_t commit_area_size,
+ Executability executable, Space* space);
+
+ Address ReserveAlignedMemory(size_t requested, size_t alignment,
+ base::VirtualMemory* controller);
+ Address AllocateAlignedMemory(size_t reserve_size, size_t commit_size,
+ size_t alignment, Executability executable,
+ base::VirtualMemory* controller);
+
+ bool CommitMemory(Address addr, size_t size, Executability executable);
+
+ void FreeMemory(base::VirtualMemory* reservation, Executability executable);
+ void FreeMemory(Address addr, size_t size, Executability executable);
+
+ // Commit a contiguous block of memory from the initial chunk. Assumes that
+ // the address is not NULL, the size is greater than zero, and that the
+ // block is contained in the initial chunk. Returns true if it succeeded
+ // and false otherwise.
+ bool CommitBlock(Address start, size_t size, Executability executable);
+
+ // Uncommit a contiguous block of memory [start..(start+size)[.
+ // start is not NULL, the size is greater than zero, and the
+ // block is contained in the initial chunk. Returns true if it succeeded
+ // and false otherwise.
+ bool UncommitBlock(Address start, size_t size);
+
+ // Zaps a contiguous block of memory [start..(start+size)[ thus
+ // filling it up with a recognizable non-NULL bit pattern.
+ void ZapBlock(Address start, size_t size);
+
+ void PerformAllocationCallback(ObjectSpace space, AllocationAction action,
+ size_t size);
+
+ void AddMemoryAllocationCallback(MemoryAllocationCallback callback,
+ ObjectSpace space, AllocationAction action);
+
+ void RemoveMemoryAllocationCallback(MemoryAllocationCallback callback);
+
+ bool MemoryAllocationCallbackRegistered(MemoryAllocationCallback callback);
+
+ static int CodePageGuardStartOffset();
+
+ static int CodePageGuardSize();
+
+ static int CodePageAreaStartOffset();
+
+ static int CodePageAreaEndOffset();
+
+ static int CodePageAreaSize() {
+ return CodePageAreaEndOffset() - CodePageAreaStartOffset();
+ }
+
+ MUST_USE_RESULT bool CommitExecutableMemory(base::VirtualMemory* vm,
+ Address start, size_t commit_size,
+ size_t reserved_size);
+
+ private:
+ Isolate* isolate_;
+
+ // Maximum space size in bytes.
+ size_t capacity_;
+ // Maximum subset of capacity_ that can be executable
+ size_t capacity_executable_;
+
+ // Allocated space size in bytes.
+ size_t size_;
+ // Allocated executable space size in bytes.
+ size_t size_executable_;
+
+ // We keep the lowest and highest addresses allocated as a quick way
+ // of determining that pointers are outside the heap. The estimate is
+ // conservative, i.e. not all addrsses in 'allocated' space are allocated
+ // to our heap. The range is [lowest, highest[, inclusive on the low end
+ // and exclusive on the high end.
+ void* lowest_ever_allocated_;
+ void* highest_ever_allocated_;
+
+ struct MemoryAllocationCallbackRegistration {
+ MemoryAllocationCallbackRegistration(MemoryAllocationCallback callback,
+ ObjectSpace space,
+ AllocationAction action)
+ : callback(callback), space(space), action(action) {}
+ MemoryAllocationCallback callback;
+ ObjectSpace space;
+ AllocationAction action;
+ };
+
+ // A List of callback that are triggered when memory is allocated or free'd
+ List<MemoryAllocationCallbackRegistration> memory_allocation_callbacks_;
+
+ // Initializes pages in a chunk. Returns the first page address.
+ // This function and GetChunkId() are provided for the mark-compact
+ // collector to rebuild page headers in the from space, which is
+ // used as a marking stack and its page headers are destroyed.
+ Page* InitializePagesInChunk(int chunk_id, int pages_in_chunk,
+ PagedSpace* owner);
+
+ void UpdateAllocatedSpaceLimits(void* low, void* high) {
+ lowest_ever_allocated_ = Min(lowest_ever_allocated_, low);
+ highest_ever_allocated_ = Max(highest_ever_allocated_, high);
+ }
+
+ DISALLOW_IMPLICIT_CONSTRUCTORS(MemoryAllocator);
+};
+
+
+// -----------------------------------------------------------------------------
+// Interface for heap object iterator to be implemented by all object space
+// object iterators.
+//
+// NOTE: The space specific object iterators also implements the own next()
+// method which is used to avoid using virtual functions
+// iterating a specific space.
+
+class ObjectIterator : public Malloced {
+ public:
+ virtual ~ObjectIterator() {}
+
+ virtual HeapObject* next_object() = 0;
+};
+
+
+// -----------------------------------------------------------------------------
+// Heap object iterator in new/old/map spaces.
+//
+// A HeapObjectIterator iterates objects from the bottom of the given space
+// to its top or from the bottom of the given page to its top.
+//
+// If objects are allocated in the page during iteration the iterator may
+// or may not iterate over those objects. The caller must create a new
+// iterator in order to be sure to visit these new objects.
+class HeapObjectIterator : public ObjectIterator {
+ public:
+ // Creates a new object iterator in a given space.
+ // If the size function is not given, the iterator calls the default
+ // Object::Size().
+ explicit HeapObjectIterator(PagedSpace* space);
+ HeapObjectIterator(PagedSpace* space, HeapObjectCallback size_func);
+ HeapObjectIterator(Page* page, HeapObjectCallback size_func);
+
+ // Advance to the next object, skipping free spaces and other fillers and
+ // skipping the special garbage section of which there is one per space.
+ // Returns NULL when the iteration has ended.
+ inline HeapObject* Next() {
+ do {
+ HeapObject* next_obj = FromCurrentPage();
+ if (next_obj != NULL) return next_obj;
+ } while (AdvanceToNextPage());
+ return NULL;
+ }
+
+ virtual HeapObject* next_object() { return Next(); }
+
+ private:
+ enum PageMode { kOnePageOnly, kAllPagesInSpace };
+
+ Address cur_addr_; // Current iteration point.
+ Address cur_end_; // End iteration point.
+ HeapObjectCallback size_func_; // Size function or NULL.
+ PagedSpace* space_;
+ PageMode page_mode_;
+
+ // Fast (inlined) path of next().
+ inline HeapObject* FromCurrentPage();
+
+ // Slow path of next(), goes into the next page. Returns false if the
+ // iteration has ended.
+ bool AdvanceToNextPage();
+
+ // Initializes fields.
+ inline void Initialize(PagedSpace* owner, Address start, Address end,
+ PageMode mode, HeapObjectCallback size_func);
+};
+
+
+// -----------------------------------------------------------------------------
+// A PageIterator iterates the pages in a paged space.
+
+class PageIterator BASE_EMBEDDED {
+ public:
+ explicit inline PageIterator(PagedSpace* space);
+
+ inline bool has_next();
+ inline Page* next();
+
+ private:
+ PagedSpace* space_;
+ Page* prev_page_; // Previous page returned.
+ // Next page that will be returned. Cached here so that we can use this
+ // iterator for operations that deallocate pages.
+ Page* next_page_;
+};
+
+
+// -----------------------------------------------------------------------------
+// A space has a circular list of pages. The next page can be accessed via
+// Page::next_page() call.
+
+// An abstraction of allocation and relocation pointers in a page-structured
+// space.
+class AllocationInfo {
+ public:
+ AllocationInfo() : top_(NULL), limit_(NULL) {}
+
+ INLINE(void set_top(Address top)) {
+ SLOW_DCHECK(top == NULL ||
+ (reinterpret_cast<intptr_t>(top) & HeapObjectTagMask()) == 0);
+ top_ = top;
+ }
+
+ INLINE(Address top()) const {
+ SLOW_DCHECK(top_ == NULL ||
+ (reinterpret_cast<intptr_t>(top_) & HeapObjectTagMask()) == 0);
+ return top_;
+ }
+
+ Address* top_address() { return &top_; }
+
+ INLINE(void set_limit(Address limit)) {
+ SLOW_DCHECK(limit == NULL ||
+ (reinterpret_cast<intptr_t>(limit) & HeapObjectTagMask()) == 0);
+ limit_ = limit;
+ }
+
+ INLINE(Address limit()) const {
+ SLOW_DCHECK(limit_ == NULL ||
+ (reinterpret_cast<intptr_t>(limit_) & HeapObjectTagMask()) ==
+ 0);
+ return limit_;
+ }
+
+ Address* limit_address() { return &limit_; }
+
+#ifdef DEBUG
+ bool VerifyPagedAllocation() {
+ return (Page::FromAllocationTop(top_) == Page::FromAllocationTop(limit_)) &&
+ (top_ <= limit_);
+ }
+#endif
+
+ private:
+ // Current allocation top.
+ Address top_;
+ // Current allocation limit.
+ Address limit_;
+};
+
+
+// An abstraction of the accounting statistics of a page-structured space.
+// The 'capacity' of a space is the number of object-area bytes (i.e., not
+// including page bookkeeping structures) currently in the space. The 'size'
+// of a space is the number of allocated bytes, the 'waste' in the space is
+// the number of bytes that are not allocated and not available to
+// allocation without reorganizing the space via a GC (e.g. small blocks due
+// to internal fragmentation, top of page areas in map space), and the bytes
+// 'available' is the number of unallocated bytes that are not waste. The
+// capacity is the sum of size, waste, and available.
+//
+// The stats are only set by functions that ensure they stay balanced. These
+// functions increase or decrease one of the non-capacity stats in
+// conjunction with capacity, or else they always balance increases and
+// decreases to the non-capacity stats.
+class AllocationStats BASE_EMBEDDED {
+ public:
+ AllocationStats() { Clear(); }
+
+ // Zero out all the allocation statistics (i.e., no capacity).
+ void Clear() {
+ capacity_ = 0;
+ max_capacity_ = 0;
+ size_ = 0;
+ waste_ = 0;
+ }
+
+ void ClearSizeWaste() {
+ size_ = capacity_;
+ waste_ = 0;
+ }
+
+ // Reset the allocation statistics (i.e., available = capacity with no
+ // wasted or allocated bytes).
+ void Reset() {
+ size_ = 0;
+ waste_ = 0;
+ }
+
+ // Accessors for the allocation statistics.
+ intptr_t Capacity() { return capacity_; }
+ intptr_t MaxCapacity() { return max_capacity_; }
+ intptr_t Size() { return size_; }
+ intptr_t Waste() { return waste_; }
+
+ // Grow the space by adding available bytes. They are initially marked as
+ // being in use (part of the size), but will normally be immediately freed,
+ // putting them on the free list and removing them from size_.
+ void ExpandSpace(int size_in_bytes) {
+ capacity_ += size_in_bytes;
+ size_ += size_in_bytes;
+ if (capacity_ > max_capacity_) {
+ max_capacity_ = capacity_;
+ }
+ DCHECK(size_ >= 0);
+ }
+
+ // Shrink the space by removing available bytes. Since shrinking is done
+ // during sweeping, bytes have been marked as being in use (part of the size)
+ // and are hereby freed.
+ void ShrinkSpace(int size_in_bytes) {
+ capacity_ -= size_in_bytes;
+ size_ -= size_in_bytes;
+ DCHECK(size_ >= 0);
+ }
+
+ // Allocate from available bytes (available -> size).
+ void AllocateBytes(intptr_t size_in_bytes) {
+ size_ += size_in_bytes;
+ DCHECK(size_ >= 0);
+ }
+
+ // Free allocated bytes, making them available (size -> available).
+ void DeallocateBytes(intptr_t size_in_bytes) {
+ size_ -= size_in_bytes;
+ DCHECK(size_ >= 0);
+ }
+
+ // Waste free bytes (available -> waste).
+ void WasteBytes(int size_in_bytes) {
+ DCHECK(size_in_bytes >= 0);
+ waste_ += size_in_bytes;
+ }
+
+ private:
+ intptr_t capacity_;
+ intptr_t max_capacity_;
+ intptr_t size_;
+ intptr_t waste_;
+};
+
+
+// -----------------------------------------------------------------------------
+// Free lists for old object spaces
+//
+// Free-list nodes are free blocks in the heap. They look like heap objects
+// (free-list node pointers have the heap object tag, and they have a map like
+// a heap object). They have a size and a next pointer. The next pointer is
+// the raw address of the next free list node (or NULL).
+class FreeListNode : public HeapObject {
+ public:
+ // Obtain a free-list node from a raw address. This is not a cast because
+ // it does not check nor require that the first word at the address is a map
+ // pointer.
+ static FreeListNode* FromAddress(Address address) {
+ return reinterpret_cast<FreeListNode*>(HeapObject::FromAddress(address));
+ }
+
+ static inline bool IsFreeListNode(HeapObject* object);
+
+ // Set the size in bytes, which can be read with HeapObject::Size(). This
+ // function also writes a map to the first word of the block so that it
+ // looks like a heap object to the garbage collector and heap iteration
+ // functions.
+ void set_size(Heap* heap, int size_in_bytes);
+
+ // Accessors for the next field.
+ inline FreeListNode* next();
+ inline FreeListNode** next_address();
+ inline void set_next(FreeListNode* next);
+
+ inline void Zap();
+
+ static inline FreeListNode* cast(Object* object) {
+ return reinterpret_cast<FreeListNode*>(object);
+ }
+
+ private:
+ static const int kNextOffset = POINTER_SIZE_ALIGN(FreeSpace::kHeaderSize);
+
+ DISALLOW_IMPLICIT_CONSTRUCTORS(FreeListNode);
+};
+
+
+// The free list category holds a pointer to the top element and a pointer to
+// the end element of the linked list of free memory blocks.
+class FreeListCategory {
+ public:
+ FreeListCategory() : top_(0), end_(NULL), available_(0) {}
+
+ intptr_t Concatenate(FreeListCategory* category);
+
+ void Reset();
+
+ void Free(FreeListNode* node, int size_in_bytes);
+
+ FreeListNode* PickNodeFromList(int* node_size);
+ FreeListNode* PickNodeFromList(int size_in_bytes, int* node_size);
+
+ intptr_t EvictFreeListItemsInList(Page* p);
+ bool ContainsPageFreeListItemsInList(Page* p);
+
+ void RepairFreeList(Heap* heap);
+
+ FreeListNode* top() const {
+ return reinterpret_cast<FreeListNode*>(base::NoBarrier_Load(&top_));
+ }
+
+ void set_top(FreeListNode* top) {
+ base::NoBarrier_Store(&top_, reinterpret_cast<base::AtomicWord>(top));
+ }
+
+ FreeListNode** GetEndAddress() { return &end_; }
+ FreeListNode* end() const { return end_; }
+ void set_end(FreeListNode* end) { end_ = end; }
+
+ int* GetAvailableAddress() { return &available_; }
+ int available() const { return available_; }
+ void set_available(int available) { available_ = available; }
+
+ base::Mutex* mutex() { return &mutex_; }
+
+ bool IsEmpty() { return top() == 0; }
+
+#ifdef DEBUG
+ intptr_t SumFreeList();
+ int FreeListLength();
+#endif
+
+ private:
+ // top_ points to the top FreeListNode* in the free list category.
+ base::AtomicWord top_;
+ FreeListNode* end_;
+ base::Mutex mutex_;
+
+ // Total available bytes in all blocks of this free list category.
+ int available_;
+};
+
+
+// The free list for the old space. The free list is organized in such a way
+// as to encourage objects allocated around the same time to be near each
+// other. The normal way to allocate is intended to be by bumping a 'top'
+// pointer until it hits a 'limit' pointer. When the limit is hit we need to
+// find a new space to allocate from. This is done with the free list, which
+// is divided up into rough categories to cut down on waste. Having finer
+// categories would scatter allocation more.
+
+// The old space free list is organized in categories.
+// 1-31 words: Such small free areas are discarded for efficiency reasons.
+// They can be reclaimed by the compactor. However the distance between top
+// and limit may be this small.
+// 32-255 words: There is a list of spaces this large. It is used for top and
+// limit when the object we need to allocate is 1-31 words in size. These
+// spaces are called small.
+// 256-2047 words: There is a list of spaces this large. It is used for top and
+// limit when the object we need to allocate is 32-255 words in size. These
+// spaces are called medium.
+// 1048-16383 words: There is a list of spaces this large. It is used for top
+// and limit when the object we need to allocate is 256-2047 words in size.
+// These spaces are call large.
+// At least 16384 words. This list is for objects of 2048 words or larger.
+// Empty pages are added to this list. These spaces are called huge.
+class FreeList {
+ public:
+ explicit FreeList(PagedSpace* owner);
+
+ intptr_t Concatenate(FreeList* free_list);
+
+ // Clear the free list.
+ void Reset();
+
+ // Return the number of bytes available on the free list.
+ intptr_t available() {
+ return small_list_.available() + medium_list_.available() +
+ large_list_.available() + huge_list_.available();
+ }
+
+ // Place a node on the free list. The block of size 'size_in_bytes'
+ // starting at 'start' is placed on the free list. The return value is the
+ // number of bytes that have been lost due to internal fragmentation by
+ // freeing the block. Bookkeeping information will be written to the block,
+ // i.e., its contents will be destroyed. The start address should be word
+ // aligned, and the size should be a non-zero multiple of the word size.
+ int Free(Address start, int size_in_bytes);
+
+ // This method returns how much memory can be allocated after freeing
+ // maximum_freed memory.
+ static inline int GuaranteedAllocatable(int maximum_freed) {
+ if (maximum_freed < kSmallListMin) {
+ return 0;
+ } else if (maximum_freed <= kSmallListMax) {
+ return kSmallAllocationMax;
+ } else if (maximum_freed <= kMediumListMax) {
+ return kMediumAllocationMax;
+ } else if (maximum_freed <= kLargeListMax) {
+ return kLargeAllocationMax;
+ }
+ return maximum_freed;
+ }
+
+ // Allocate a block of size 'size_in_bytes' from the free list. The block
+ // is unitialized. A failure is returned if no block is available. The
+ // number of bytes lost to fragmentation is returned in the output parameter
+ // 'wasted_bytes'. The size should be a non-zero multiple of the word size.
+ MUST_USE_RESULT HeapObject* Allocate(int size_in_bytes);
+
+ bool IsEmpty() {
+ return small_list_.IsEmpty() && medium_list_.IsEmpty() &&
+ large_list_.IsEmpty() && huge_list_.IsEmpty();
+ }
+
+#ifdef DEBUG
+ void Zap();
+ intptr_t SumFreeLists();
+ bool IsVeryLong();
+#endif
+
+ // Used after booting the VM.
+ void RepairLists(Heap* heap);
+
+ intptr_t EvictFreeListItems(Page* p);
+ bool ContainsPageFreeListItems(Page* p);
+
+ FreeListCategory* small_list() { return &small_list_; }
+ FreeListCategory* medium_list() { return &medium_list_; }
+ FreeListCategory* large_list() { return &large_list_; }
+ FreeListCategory* huge_list() { return &huge_list_; }
+
+ private:
+ // The size range of blocks, in bytes.
+ static const int kMinBlockSize = 3 * kPointerSize;
+ static const int kMaxBlockSize = Page::kMaxRegularHeapObjectSize;
+
+ FreeListNode* FindNodeFor(int size_in_bytes, int* node_size);
+
+ PagedSpace* owner_;
+ Heap* heap_;
+
+ static const int kSmallListMin = 0x20 * kPointerSize;
+ static const int kSmallListMax = 0xff * kPointerSize;
+ static const int kMediumListMax = 0x7ff * kPointerSize;
+ static const int kLargeListMax = 0x3fff * kPointerSize;
+ static const int kSmallAllocationMax = kSmallListMin - kPointerSize;
+ static const int kMediumAllocationMax = kSmallListMax;
+ static const int kLargeAllocationMax = kMediumListMax;
+ FreeListCategory small_list_;
+ FreeListCategory medium_list_;
+ FreeListCategory large_list_;
+ FreeListCategory huge_list_;
+
+ DISALLOW_IMPLICIT_CONSTRUCTORS(FreeList);
+};
+
+
+class AllocationResult {
+ public:
+ // Implicit constructor from Object*.
+ AllocationResult(Object* object) // NOLINT
+ : object_(object),
+ retry_space_(INVALID_SPACE) {}
+
+ AllocationResult() : object_(NULL), retry_space_(INVALID_SPACE) {}
+
+ static inline AllocationResult Retry(AllocationSpace space = NEW_SPACE) {
+ return AllocationResult(space);
+ }
+
+ inline bool IsRetry() { return retry_space_ != INVALID_SPACE; }
+
+ template <typename T>
+ bool To(T** obj) {
+ if (IsRetry()) return false;
+ *obj = T::cast(object_);
+ return true;
+ }
+
+ Object* ToObjectChecked() {
+ CHECK(!IsRetry());
+ return object_;
+ }
+
+ AllocationSpace RetrySpace() {
+ DCHECK(IsRetry());
+ return retry_space_;
+ }
+
+ private:
+ explicit AllocationResult(AllocationSpace space)
+ : object_(NULL), retry_space_(space) {}
+
+ Object* object_;
+ AllocationSpace retry_space_;
+};
+
+
+class PagedSpace : public Space {
+ public:
+ // Creates a space with a maximum capacity, and an id.
+ PagedSpace(Heap* heap, intptr_t max_capacity, AllocationSpace id,
+ Executability executable);
+
+ virtual ~PagedSpace() {}
+
+ // Set up the space using the given address range of virtual memory (from
+ // the memory allocator's initial chunk) if possible. If the block of
+ // addresses is not big enough to contain a single page-aligned page, a
+ // fresh chunk will be allocated.
+ bool SetUp();
+
+ // Returns true if the space has been successfully set up and not
+ // subsequently torn down.
+ bool HasBeenSetUp();
+
+ // Cleans up the space, frees all pages in this space except those belonging
+ // to the initial chunk, uncommits addresses in the initial chunk.
+ void TearDown();
+
+ // Checks whether an object/address is in this space.
+ inline bool Contains(Address a);
+ bool Contains(HeapObject* o) { return Contains(o->address()); }
+
+ // Given an address occupied by a live object, return that object if it is
+ // in this space, or a Smi if it is not. The implementation iterates over
+ // objects in the page containing the address, the cost is linear in the
+ // number of objects in the page. It may be slow.
+ Object* FindObject(Address addr);
+
+ // During boot the free_space_map is created, and afterwards we may need
+ // to write it into the free list nodes that were already created.
+ void RepairFreeListsAfterBoot();
+
+ // Prepares for a mark-compact GC.
+ void PrepareForMarkCompact();
+
+ // Current capacity without growing (Size() + Available()).
+ intptr_t Capacity() { return accounting_stats_.Capacity(); }
+
+ // Total amount of memory committed for this space. For paged
+ // spaces this equals the capacity.
+ intptr_t CommittedMemory() { return Capacity(); }
+
+ // The maximum amount of memory ever committed for this space.
+ intptr_t MaximumCommittedMemory() { return accounting_stats_.MaxCapacity(); }
+
+ // Approximate amount of physical memory committed for this space.
+ size_t CommittedPhysicalMemory();
+
+ struct SizeStats {
+ intptr_t Total() {
+ return small_size_ + medium_size_ + large_size_ + huge_size_;
+ }
+
+ intptr_t small_size_;
+ intptr_t medium_size_;
+ intptr_t large_size_;
+ intptr_t huge_size_;
+ };
+
+ void ObtainFreeListStatistics(Page* p, SizeStats* sizes);
+ void ResetFreeListStatistics();
+
+ // Sets the capacity, the available space and the wasted space to zero.
+ // The stats are rebuilt during sweeping by adding each page to the
+ // capacity and the size when it is encountered. As free spaces are
+ // discovered during the sweeping they are subtracted from the size and added
+ // to the available and wasted totals.
+ void ClearStats() {
+ accounting_stats_.ClearSizeWaste();
+ ResetFreeListStatistics();
+ }
+
+ // Increases the number of available bytes of that space.
+ void AddToAccountingStats(intptr_t bytes) {
+ accounting_stats_.DeallocateBytes(bytes);
+ }
+
+ // Available bytes without growing. These are the bytes on the free list.
+ // The bytes in the linear allocation area are not included in this total
+ // because updating the stats would slow down allocation. New pages are
+ // immediately added to the free list so they show up here.
+ intptr_t Available() { return free_list_.available(); }
+
+ // Allocated bytes in this space. Garbage bytes that were not found due to
+ // concurrent sweeping are counted as being allocated! The bytes in the
+ // current linear allocation area (between top and limit) are also counted
+ // here.
+ virtual intptr_t Size() { return accounting_stats_.Size(); }
+
+ // As size, but the bytes in lazily swept pages are estimated and the bytes
+ // in the current linear allocation area are not included.
+ virtual intptr_t SizeOfObjects();
+
+ // Wasted bytes in this space. These are just the bytes that were thrown away
+ // due to being too small to use for allocation. They do not include the
+ // free bytes that were not found at all due to lazy sweeping.
+ virtual intptr_t Waste() { return accounting_stats_.Waste(); }
+
+ // Returns the allocation pointer in this space.
+ Address top() { return allocation_info_.top(); }
+ Address limit() { return allocation_info_.limit(); }
+
+ // The allocation top address.
+ Address* allocation_top_address() { return allocation_info_.top_address(); }
+
+ // The allocation limit address.
+ Address* allocation_limit_address() {
+ return allocation_info_.limit_address();
+ }
+
+ // Allocate the requested number of bytes in the space if possible, return a
+ // failure object if not.
+ MUST_USE_RESULT inline AllocationResult AllocateRaw(int size_in_bytes);
+
+ // Give a block of memory to the space's free list. It might be added to
+ // the free list or accounted as waste.
+ // If add_to_freelist is false then just accounting stats are updated and
+ // no attempt to add area to free list is made.
+ int Free(Address start, int size_in_bytes) {
+ int wasted = free_list_.Free(start, size_in_bytes);
+ accounting_stats_.DeallocateBytes(size_in_bytes);
+ accounting_stats_.WasteBytes(wasted);
+ return size_in_bytes - wasted;
+ }
+
+ void ResetFreeList() { free_list_.Reset(); }
+
+ // Set space allocation info.
+ void SetTopAndLimit(Address top, Address limit) {
+ DCHECK(top == limit ||
+ Page::FromAddress(top) == Page::FromAddress(limit - 1));
+ MemoryChunk::UpdateHighWaterMark(allocation_info_.top());
+ allocation_info_.set_top(top);
+ allocation_info_.set_limit(limit);
+ }
+
+ // Empty space allocation info, returning unused area to free list.
+ void EmptyAllocationInfo() {
+ // Mark the old linear allocation area with a free space map so it can be
+ // skipped when scanning the heap.
+ int old_linear_size = static_cast<int>(limit() - top());
+ Free(top(), old_linear_size);
+ SetTopAndLimit(NULL, NULL);
+ }
+
+ void Allocate(int bytes) { accounting_stats_.AllocateBytes(bytes); }
+
+ void IncreaseCapacity(int size);
+
+ // Releases an unused page and shrinks the space.
+ void ReleasePage(Page* page);
+
+ // The dummy page that anchors the linked list of pages.
+ Page* anchor() { return &anchor_; }
+
+#ifdef VERIFY_HEAP
+ // Verify integrity of this space.
+ virtual void Verify(ObjectVisitor* visitor);
+
+ // Overridden by subclasses to verify space-specific object
+ // properties (e.g., only maps or free-list nodes are in map space).
+ virtual void VerifyObject(HeapObject* obj) {}
+#endif
+
+#ifdef DEBUG
+ // Print meta info and objects in this space.
+ virtual void Print();
+
+ // Reports statistics for the space
+ void ReportStatistics();
+
+ // Report code object related statistics
+ void CollectCodeStatistics();
+ static void ReportCodeStatistics(Isolate* isolate);
+ static void ResetCodeStatistics(Isolate* isolate);
+#endif
+
+ // Evacuation candidates are swept by evacuator. Needs to return a valid
+ // result before _and_ after evacuation has finished.
+ static bool ShouldBeSweptBySweeperThreads(Page* p) {
+ return !p->IsEvacuationCandidate() &&
+ !p->IsFlagSet(Page::RESCAN_ON_EVACUATION) && !p->WasSwept();
+ }
+
+ void IncrementUnsweptFreeBytes(intptr_t by) { unswept_free_bytes_ += by; }
+
+ void IncreaseUnsweptFreeBytes(Page* p) {
+ DCHECK(ShouldBeSweptBySweeperThreads(p));
+ unswept_free_bytes_ += (p->area_size() - p->LiveBytes());
+ }
+
+ void DecrementUnsweptFreeBytes(intptr_t by) { unswept_free_bytes_ -= by; }
+
+ void DecreaseUnsweptFreeBytes(Page* p) {
+ DCHECK(ShouldBeSweptBySweeperThreads(p));
+ unswept_free_bytes_ -= (p->area_size() - p->LiveBytes());
+ }
+
+ void ResetUnsweptFreeBytes() { unswept_free_bytes_ = 0; }
+
+ // This function tries to steal size_in_bytes memory from the sweeper threads
+ // free-lists. If it does not succeed stealing enough memory, it will wait
+ // for the sweeper threads to finish sweeping.
+ // It returns true when sweeping is completed and false otherwise.
+ bool EnsureSweeperProgress(intptr_t size_in_bytes);
+
+ void set_end_of_unswept_pages(Page* page) { end_of_unswept_pages_ = page; }
+
+ Page* end_of_unswept_pages() { return end_of_unswept_pages_; }
+
+ Page* FirstPage() { return anchor_.next_page(); }
+ Page* LastPage() { return anchor_.prev_page(); }
+
+ void EvictEvacuationCandidatesFromFreeLists();
+
+ bool CanExpand();
+
+ // Returns the number of total pages in this space.
+ int CountTotalPages();
+
+ // Return size of allocatable area on a page in this space.
+ inline int AreaSize() { return area_size_; }
+
+ void CreateEmergencyMemory();
+ void FreeEmergencyMemory();
+ void UseEmergencyMemory();
+
+ bool HasEmergencyMemory() { return emergency_memory_ != NULL; }
+
+ protected:
+ FreeList* free_list() { return &free_list_; }
+
+ int area_size_;
+
+ // Maximum capacity of this space.
+ intptr_t max_capacity_;
+
+ intptr_t SizeOfFirstPage();
+
+ // Accounting information for this space.
+ AllocationStats accounting_stats_;
+
+ // The dummy page that anchors the double linked list of pages.
+ Page anchor_;
+
+ // The space's free list.
+ FreeList free_list_;
+
+ // Normal allocation information.
+ AllocationInfo allocation_info_;
+
+ // The number of free bytes which could be reclaimed by advancing the
+ // concurrent sweeper threads.
+ intptr_t unswept_free_bytes_;
+
+ // The sweeper threads iterate over the list of pointer and data space pages
+ // and sweep these pages concurrently. They will stop sweeping after the
+ // end_of_unswept_pages_ page.
+ Page* end_of_unswept_pages_;
+
+ // Emergency memory is the memory of a full page for a given space, allocated
+ // conservatively before evacuating a page. If compaction fails due to out
+ // of memory error the emergency memory can be used to complete compaction.
+ // If not used, the emergency memory is released after compaction.
+ MemoryChunk* emergency_memory_;
+
+ // Expands the space by allocating a fixed number of pages. Returns false if
+ // it cannot allocate requested number of pages from OS, or if the hard heap
+ // size limit has been hit.
+ bool Expand();
+
+ // Generic fast case allocation function that tries linear allocation at the
+ // address denoted by top in allocation_info_.
+ inline HeapObject* AllocateLinearly(int size_in_bytes);
+
+ // If sweeping is still in progress try to sweep unswept pages. If that is
+ // not successful, wait for the sweeper threads and re-try free-list
+ // allocation.
+ MUST_USE_RESULT HeapObject* WaitForSweeperThreadsAndRetryAllocation(
+ int size_in_bytes);
+
+ // Slow path of AllocateRaw. This function is space-dependent.
+ MUST_USE_RESULT HeapObject* SlowAllocateRaw(int size_in_bytes);
+
+ friend class PageIterator;
+ friend class MarkCompactCollector;
+};
+
+
+class NumberAndSizeInfo BASE_EMBEDDED {
+ public:
+ NumberAndSizeInfo() : number_(0), bytes_(0) {}
+
+ int number() const { return number_; }
+ void increment_number(int num) { number_ += num; }
+
+ int bytes() const { return bytes_; }
+ void increment_bytes(int size) { bytes_ += size; }
+
+ void clear() {
+ number_ = 0;
+ bytes_ = 0;
+ }
+
+ private:
+ int number_;
+ int bytes_;
+};
+
+
+// HistogramInfo class for recording a single "bar" of a histogram. This
+// class is used for collecting statistics to print to the log file.
+class HistogramInfo : public NumberAndSizeInfo {
+ public:
+ HistogramInfo() : NumberAndSizeInfo() {}
+
+ const char* name() { return name_; }
+ void set_name(const char* name) { name_ = name; }
+
+ private:
+ const char* name_;
+};
+
+
+enum SemiSpaceId { kFromSpace = 0, kToSpace = 1 };
+
+
+class SemiSpace;
+
+
+class NewSpacePage : public MemoryChunk {
+ public:
+ // GC related flags copied from from-space to to-space when
+ // flipping semispaces.
+ static const intptr_t kCopyOnFlipFlagsMask =
+ (1 << MemoryChunk::POINTERS_TO_HERE_ARE_INTERESTING) |
+ (1 << MemoryChunk::POINTERS_FROM_HERE_ARE_INTERESTING) |
+ (1 << MemoryChunk::SCAN_ON_SCAVENGE);
+
+ static const int kAreaSize = Page::kMaxRegularHeapObjectSize;
+
+ inline NewSpacePage* next_page() const {
+ return static_cast<NewSpacePage*>(next_chunk());
+ }
+
+ inline void set_next_page(NewSpacePage* page) { set_next_chunk(page); }
+
+ inline NewSpacePage* prev_page() const {
+ return static_cast<NewSpacePage*>(prev_chunk());
+ }
+
+ inline void set_prev_page(NewSpacePage* page) { set_prev_chunk(page); }
+
+ SemiSpace* semi_space() { return reinterpret_cast<SemiSpace*>(owner()); }
+
+ bool is_anchor() { return !this->InNewSpace(); }
+
+ static bool IsAtStart(Address addr) {
+ return (reinterpret_cast<intptr_t>(addr) & Page::kPageAlignmentMask) ==
+ kObjectStartOffset;
+ }
+
+ static bool IsAtEnd(Address addr) {
+ return (reinterpret_cast<intptr_t>(addr) & Page::kPageAlignmentMask) == 0;
+ }
+
+ Address address() { return reinterpret_cast<Address>(this); }
+
+ // Finds the NewSpacePage containing the given address.
+ static inline NewSpacePage* FromAddress(Address address_in_page) {
+ Address page_start =
+ reinterpret_cast<Address>(reinterpret_cast<uintptr_t>(address_in_page) &
+ ~Page::kPageAlignmentMask);
+ NewSpacePage* page = reinterpret_cast<NewSpacePage*>(page_start);
+ return page;
+ }
+
+ // Find the page for a limit address. A limit address is either an address
+ // inside a page, or the address right after the last byte of a page.
+ static inline NewSpacePage* FromLimit(Address address_limit) {
+ return NewSpacePage::FromAddress(address_limit - 1);
+ }
+
+ // Checks if address1 and address2 are on the same new space page.
+ static inline bool OnSamePage(Address address1, Address address2) {
+ return NewSpacePage::FromAddress(address1) ==
+ NewSpacePage::FromAddress(address2);
+ }
+
+ private:
+ // Create a NewSpacePage object that is only used as anchor
+ // for the doubly-linked list of real pages.
+ explicit NewSpacePage(SemiSpace* owner) { InitializeAsAnchor(owner); }
+
+ static NewSpacePage* Initialize(Heap* heap, Address start,
+ SemiSpace* semi_space);
+
+ // Intialize a fake NewSpacePage used as sentinel at the ends
+ // of a doubly-linked list of real NewSpacePages.
+ // Only uses the prev/next links, and sets flags to not be in new-space.
+ void InitializeAsAnchor(SemiSpace* owner);
+
+ friend class SemiSpace;
+ friend class SemiSpaceIterator;
+};
+
+
+// -----------------------------------------------------------------------------
+// SemiSpace in young generation
+//
+// A semispace is a contiguous chunk of memory holding page-like memory
+// chunks. The mark-compact collector uses the memory of the first page in
+// the from space as a marking stack when tracing live objects.
+
+class SemiSpace : public Space {
+ public:
+ // Constructor.
+ SemiSpace(Heap* heap, SemiSpaceId semispace)
+ : Space(heap, NEW_SPACE, NOT_EXECUTABLE),
+ start_(NULL),
+ age_mark_(NULL),
+ id_(semispace),
+ anchor_(this),
+ current_page_(NULL) {}
+
+ // Sets up the semispace using the given chunk.
+ void SetUp(Address start, int initial_capacity, int maximum_capacity);
+
+ // Tear down the space. Heap memory was not allocated by the space, so it
+ // is not deallocated here.
+ void TearDown();
+
+ // True if the space has been set up but not torn down.
+ bool HasBeenSetUp() { return start_ != NULL; }
+
+ // Grow the semispace to the new capacity. The new capacity
+ // requested must be larger than the current capacity and less than
+ // the maximum capacity.
+ bool GrowTo(int new_capacity);
+
+ // Shrinks the semispace to the new capacity. The new capacity
+ // requested must be more than the amount of used memory in the
+ // semispace and less than the current capacity.
+ bool ShrinkTo(int new_capacity);
+
+ // Returns the start address of the first page of the space.
+ Address space_start() {
+ DCHECK(anchor_.next_page() != &anchor_);
+ return anchor_.next_page()->area_start();
+ }
+
+ // Returns the start address of the current page of the space.
+ Address page_low() { return current_page_->area_start(); }
+
+ // Returns one past the end address of the space.
+ Address space_end() { return anchor_.prev_page()->area_end(); }
+
+ // Returns one past the end address of the current page of the space.
+ Address page_high() { return current_page_->area_end(); }
+
+ bool AdvancePage() {
+ NewSpacePage* next_page = current_page_->next_page();
+ if (next_page == anchor()) return false;
+ current_page_ = next_page;
+ return true;
+ }
+
+ // Resets the space to using the first page.
+ void Reset();
+
+ // Age mark accessors.
+ Address age_mark() { return age_mark_; }
+ void set_age_mark(Address mark);
+
+ // True if the address is in the address range of this semispace (not
+ // necessarily below the allocation pointer).
+ bool Contains(Address a) {
+ return (reinterpret_cast<uintptr_t>(a) & address_mask_) ==
+ reinterpret_cast<uintptr_t>(start_);
+ }
+
+ // True if the object is a heap object in the address range of this
+ // semispace (not necessarily below the allocation pointer).
+ bool Contains(Object* o) {
+ return (reinterpret_cast<uintptr_t>(o) & object_mask_) == object_expected_;
+ }
+
+ // If we don't have these here then SemiSpace will be abstract. However
+ // they should never be called.
+ virtual intptr_t Size() {
+ UNREACHABLE();
+ return 0;
+ }
+
+ bool is_committed() { return committed_; }
+ bool Commit();
+ bool Uncommit();
+
+ NewSpacePage* first_page() { return anchor_.next_page(); }
+ NewSpacePage* current_page() { return current_page_; }
+
+#ifdef VERIFY_HEAP
+ virtual void Verify();
+#endif
+
+#ifdef DEBUG
+ virtual void Print();
+ // Validate a range of of addresses in a SemiSpace.
+ // The "from" address must be on a page prior to the "to" address,
+ // in the linked page order, or it must be earlier on the same page.
+ static void AssertValidRange(Address from, Address to);
+#else
+ // Do nothing.
+ inline static void AssertValidRange(Address from, Address to) {}
+#endif
+
+ // Returns the current total capacity of the semispace.
+ int TotalCapacity() { return total_capacity_; }
+
+ // Returns the maximum total capacity of the semispace.
+ int MaximumTotalCapacity() { return maximum_total_capacity_; }
+
+ // Returns the initial capacity of the semispace.
+ int InitialTotalCapacity() { return initial_total_capacity_; }
+
+ SemiSpaceId id() { return id_; }
+
+ static void Swap(SemiSpace* from, SemiSpace* to);
+
+ // Returns the maximum amount of memory ever committed by the semi space.
+ size_t MaximumCommittedMemory() { return maximum_committed_; }
+
+ // Approximate amount of physical memory committed for this space.
+ size_t CommittedPhysicalMemory();
+
+ private:
+ // Flips the semispace between being from-space and to-space.
+ // Copies the flags into the masked positions on all pages in the space.
+ void FlipPages(intptr_t flags, intptr_t flag_mask);
+
+ // Updates Capacity and MaximumCommitted based on new capacity.
+ void SetCapacity(int new_capacity);
+
+ NewSpacePage* anchor() { return &anchor_; }
+
+ // The current and maximum total capacity of the space.
+ int total_capacity_;
+ int maximum_total_capacity_;
+ int initial_total_capacity_;
+
+ intptr_t maximum_committed_;
+
+ // The start address of the space.
+ Address start_;
+ // Used to govern object promotion during mark-compact collection.
+ Address age_mark_;
+
+ // Masks and comparison values to test for containment in this semispace.
+ uintptr_t address_mask_;
+ uintptr_t object_mask_;
+ uintptr_t object_expected_;
+
+ bool committed_;
+ SemiSpaceId id_;
+
+ NewSpacePage anchor_;
+ NewSpacePage* current_page_;
+
+ friend class SemiSpaceIterator;
+ friend class NewSpacePageIterator;
+
+ public:
+ TRACK_MEMORY("SemiSpace")
+};
+
+
+// A SemiSpaceIterator is an ObjectIterator that iterates over the active
+// semispace of the heap's new space. It iterates over the objects in the
+// semispace from a given start address (defaulting to the bottom of the
+// semispace) to the top of the semispace. New objects allocated after the
+// iterator is created are not iterated.
+class SemiSpaceIterator : public ObjectIterator {
+ public:
+ // Create an iterator over the objects in the given space. If no start
+ // address is given, the iterator starts from the bottom of the space. If
+ // no size function is given, the iterator calls Object::Size().
+
+ // Iterate over all of allocated to-space.
+ explicit SemiSpaceIterator(NewSpace* space);
+ // Iterate over all of allocated to-space, with a custome size function.
+ SemiSpaceIterator(NewSpace* space, HeapObjectCallback size_func);
+ // Iterate over part of allocated to-space, from start to the end
+ // of allocation.
+ SemiSpaceIterator(NewSpace* space, Address start);
+ // Iterate from one address to another in the same semi-space.
+ SemiSpaceIterator(Address from, Address to);
+
+ HeapObject* Next() {
+ if (current_ == limit_) return NULL;
+ 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 NULL;
+ }
+
+ HeapObject* object = HeapObject::FromAddress(current_);
+ int size = (size_func_ == NULL) ? object->Size() : size_func_(object);
+
+ current_ += size;
+ return object;
+ }
+
+ // Implementation of the ObjectIterator functions.
+ virtual HeapObject* next_object() { return Next(); }
+
+ private:
+ void Initialize(Address start, Address end, HeapObjectCallback size_func);
+
+ // The current iteration point.
+ Address current_;
+ // The end of iteration.
+ Address limit_;
+ // The callback function.
+ HeapObjectCallback size_func_;
+};
+
+
+// -----------------------------------------------------------------------------
+// A PageIterator iterates the pages in a semi-space.
+class NewSpacePageIterator BASE_EMBEDDED {
+ public:
+ // Make an iterator that runs over all pages in to-space.
+ explicit inline NewSpacePageIterator(NewSpace* space);
+
+ // Make an iterator that runs over all pages in the given semispace,
+ // even those not used in allocation.
+ explicit inline NewSpacePageIterator(SemiSpace* space);
+
+ // Make iterator that iterates from the page containing start
+ // to the page that contains limit in the same semispace.
+ inline NewSpacePageIterator(Address start, Address limit);
+
+ inline bool has_next();
+ inline NewSpacePage* next();
+
+ private:
+ NewSpacePage* prev_page_; // Previous page returned.
+ // Next page that will be returned. Cached here so that we can use this
+ // iterator for operations that deallocate pages.
+ NewSpacePage* next_page_;
+ // Last page returned.
+ NewSpacePage* last_page_;
+};
+
+
+// -----------------------------------------------------------------------------
+// The young generation space.
+//
+// The new space consists of a contiguous pair of semispaces. It simply
+// forwards most functions to the appropriate semispace.
+
+class NewSpace : public Space {
+ public:
+ // Constructor.
+ explicit NewSpace(Heap* heap)
+ : Space(heap, NEW_SPACE, NOT_EXECUTABLE),
+ to_space_(heap, kToSpace),
+ from_space_(heap, kFromSpace),
+ reservation_(),
+ inline_allocation_limit_step_(0) {}
+
+ // Sets up the new space using the given chunk.
+ bool SetUp(int reserved_semispace_size_, int max_semi_space_size);
+
+ // Tears down the space. Heap memory was not allocated by the space, so it
+ // is not deallocated here.
+ void TearDown();
+
+ // True if the space has been set up but not torn down.
+ bool HasBeenSetUp() {
+ return to_space_.HasBeenSetUp() && from_space_.HasBeenSetUp();
+ }
+
+ // Flip the pair of spaces.
+ void Flip();
+
+ // Grow the capacity of the semispaces. Assumes that they are not at
+ // their maximum capacity.
+ void Grow();
+
+ // Shrink the capacity of the semispaces.
+ void Shrink();
+
+ // True if the address or object lies in the address range of either
+ // semispace (not necessarily below the allocation pointer).
+ bool Contains(Address a) {
+ return (reinterpret_cast<uintptr_t>(a) & address_mask_) ==
+ reinterpret_cast<uintptr_t>(start_);
+ }
+
+ bool Contains(Object* o) {
+ Address a = reinterpret_cast<Address>(o);
+ return (reinterpret_cast<uintptr_t>(a) & object_mask_) == object_expected_;
+ }
+
+ // Return the allocated bytes in the active semispace.
+ virtual intptr_t Size() {
+ return pages_used_ * NewSpacePage::kAreaSize +
+ static_cast<int>(top() - to_space_.page_low());
+ }
+
+ // The same, but returning an int. We have to have the one that returns
+ // intptr_t because it is inherited, but if we know we are dealing with the
+ // new space, which can't get as big as the other spaces then this is useful:
+ int SizeAsInt() { return static_cast<int>(Size()); }
+
+ // Return the allocatable capacity of a semispace.
+ intptr_t Capacity() {
+ SLOW_DCHECK(to_space_.TotalCapacity() == from_space_.TotalCapacity());
+ return (to_space_.TotalCapacity() / Page::kPageSize) *
+ NewSpacePage::kAreaSize;
+ }
+
+ // Return the current size of a semispace, allocatable and non-allocatable
+ // memory.
+ intptr_t TotalCapacity() {
+ DCHECK(to_space_.TotalCapacity() == from_space_.TotalCapacity());
+ return to_space_.TotalCapacity();
+ }
+
+ // Return the total amount of memory committed for new space.
+ intptr_t CommittedMemory() {
+ if (from_space_.is_committed()) return 2 * Capacity();
+ return TotalCapacity();
+ }
+
+ // Return the total amount of memory committed for new space.
+ intptr_t MaximumCommittedMemory() {
+ return to_space_.MaximumCommittedMemory() +
+ from_space_.MaximumCommittedMemory();
+ }
+
+ // Approximate amount of physical memory committed for this space.
+ size_t CommittedPhysicalMemory();
+
+ // Return the available bytes without growing.
+ intptr_t Available() { return Capacity() - Size(); }
+
+ // Return the maximum capacity of a semispace.
+ int MaximumCapacity() {
+ DCHECK(to_space_.MaximumTotalCapacity() ==
+ from_space_.MaximumTotalCapacity());
+ return to_space_.MaximumTotalCapacity();
+ }
+
+ bool IsAtMaximumCapacity() { return TotalCapacity() == MaximumCapacity(); }
+
+ // Returns the initial capacity of a semispace.
+ int InitialTotalCapacity() {
+ DCHECK(to_space_.InitialTotalCapacity() ==
+ from_space_.InitialTotalCapacity());
+ return to_space_.InitialTotalCapacity();
+ }
+
+ // Return the address of the allocation pointer in the active semispace.
+ Address top() {
+ DCHECK(to_space_.current_page()->ContainsLimit(allocation_info_.top()));
+ return allocation_info_.top();
+ }
+
+ void set_top(Address top) {
+ DCHECK(to_space_.current_page()->ContainsLimit(top));
+ allocation_info_.set_top(top);
+ }
+
+ // Return the address of the allocation pointer limit in the active semispace.
+ Address limit() {
+ DCHECK(to_space_.current_page()->ContainsLimit(allocation_info_.limit()));
+ return allocation_info_.limit();
+ }
+
+ // Return the address of the first object in the active semispace.
+ Address bottom() { return to_space_.space_start(); }
+
+ // Get the age mark of the inactive semispace.
+ Address age_mark() { return from_space_.age_mark(); }
+ // Set the age mark in the active semispace.
+ void set_age_mark(Address mark) { to_space_.set_age_mark(mark); }
+
+ // The start address of the space and a bit mask. Anding an address in the
+ // new space with the mask will result in the start address.
+ Address start() { return start_; }
+ uintptr_t mask() { return address_mask_; }
+
+ INLINE(uint32_t AddressToMarkbitIndex(Address addr)) {
+ DCHECK(Contains(addr));
+ DCHECK(IsAligned(OffsetFrom(addr), kPointerSize) ||
+ IsAligned(OffsetFrom(addr) - 1, kPointerSize));
+ return static_cast<uint32_t>(addr - start_) >> kPointerSizeLog2;
+ }
+
+ INLINE(Address MarkbitIndexToAddress(uint32_t index)) {
+ return reinterpret_cast<Address>(index << kPointerSizeLog2);
+ }
+
+ // The allocation top and limit address.
+ Address* allocation_top_address() { return allocation_info_.top_address(); }
+
+ // The allocation limit address.
+ Address* allocation_limit_address() {
+ return allocation_info_.limit_address();
+ }
+
+ MUST_USE_RESULT INLINE(AllocationResult AllocateRaw(int size_in_bytes));
+
+ // Reset the allocation pointer to the beginning of the active semispace.
+ void ResetAllocationInfo();
+
+ void UpdateInlineAllocationLimit(int size_in_bytes);
+ void LowerInlineAllocationLimit(intptr_t step) {
+ inline_allocation_limit_step_ = step;
+ UpdateInlineAllocationLimit(0);
+ top_on_previous_step_ = allocation_info_.top();
+ }
+
+ // Get the extent of the inactive semispace (for use as a marking stack,
+ // or to zap it). Notice: space-addresses are not necessarily on the
+ // same page, so FromSpaceStart() might be above FromSpaceEnd().
+ Address FromSpacePageLow() { return from_space_.page_low(); }
+ Address FromSpacePageHigh() { return from_space_.page_high(); }
+ Address FromSpaceStart() { return from_space_.space_start(); }
+ Address FromSpaceEnd() { return from_space_.space_end(); }
+
+ // Get the extent of the active semispace's pages' memory.
+ Address ToSpaceStart() { return to_space_.space_start(); }
+ Address ToSpaceEnd() { return to_space_.space_end(); }
+
+ inline bool ToSpaceContains(Address address) {
+ return to_space_.Contains(address);
+ }
+ inline bool FromSpaceContains(Address address) {
+ return from_space_.Contains(address);
+ }
+
+ // True if the object is a heap object in the address range of the
+ // respective semispace (not necessarily below the allocation pointer of the
+ // semispace).
+ inline bool ToSpaceContains(Object* o) { return to_space_.Contains(o); }
+ inline bool FromSpaceContains(Object* o) { return from_space_.Contains(o); }
+
+ // Try to switch the active semispace to a new, empty, page.
+ // Returns false if this isn't possible or reasonable (i.e., there
+ // are no pages, or the current page is already empty), or true
+ // if successful.
+ bool AddFreshPage();
+
+#ifdef VERIFY_HEAP
+ // Verify the active semispace.
+ virtual void Verify();
+#endif
+
+#ifdef DEBUG
+ // Print the active semispace.
+ virtual void Print() { to_space_.Print(); }
+#endif
+
+ // Iterates the active semispace to collect statistics.
+ void CollectStatistics();
+ // Reports previously collected statistics of the active semispace.
+ void ReportStatistics();
+ // Clears previously collected statistics.
+ void ClearHistograms();
+
+ // Record the allocation or promotion of a heap object. Note that we don't
+ // record every single allocation, but only those that happen in the
+ // to space during a scavenge GC.
+ void RecordAllocation(HeapObject* obj);
+ void RecordPromotion(HeapObject* obj);
+
+ // Return whether the operation succeded.
+ bool CommitFromSpaceIfNeeded() {
+ if (from_space_.is_committed()) return true;
+ return from_space_.Commit();
+ }
+
+ bool UncommitFromSpace() {
+ if (!from_space_.is_committed()) return true;
+ return from_space_.Uncommit();
+ }
+
+ inline intptr_t inline_allocation_limit_step() {
+ return inline_allocation_limit_step_;
+ }
+
+ SemiSpace* active_space() { return &to_space_; }
+
+ private:
+ // Update allocation info to match the current to-space page.
+ void UpdateAllocationInfo();
+
+ Address chunk_base_;
+ uintptr_t chunk_size_;
+
+ // The semispaces.
+ SemiSpace to_space_;
+ SemiSpace from_space_;
+ base::VirtualMemory reservation_;
+ int pages_used_;
+
+ // Start address and bit mask for containment testing.
+ Address start_;
+ uintptr_t address_mask_;
+ uintptr_t object_mask_;
+ uintptr_t object_expected_;
+
+ // Allocation pointer and limit for normal allocation and allocation during
+ // mark-compact collection.
+ AllocationInfo allocation_info_;
+
+ // When incremental marking is active we will set allocation_info_.limit
+ // to be lower than actual limit and then will gradually increase it
+ // in steps to guarantee that we do incremental marking steps even
+ // when all allocation is performed from inlined generated code.
+ intptr_t inline_allocation_limit_step_;
+
+ Address top_on_previous_step_;
+
+ HistogramInfo* allocated_histogram_;
+ HistogramInfo* promoted_histogram_;
+
+ MUST_USE_RESULT AllocationResult SlowAllocateRaw(int size_in_bytes);
+
+ friend class SemiSpaceIterator;
+
+ public:
+ TRACK_MEMORY("NewSpace")
+};
+
+
+// -----------------------------------------------------------------------------
+// Old object space (excluding map objects)
+
+class OldSpace : public PagedSpace {
+ public:
+ // Creates an old space object with a given maximum capacity.
+ // The constructor does not allocate pages from OS.
+ OldSpace(Heap* heap, intptr_t max_capacity, AllocationSpace id,
+ Executability executable)
+ : PagedSpace(heap, max_capacity, id, executable) {}
+
+ public:
+ TRACK_MEMORY("OldSpace")
+};
+
+
+// For contiguous spaces, top should be in the space (or at the end) and limit
+// should be the end of the space.
+#define DCHECK_SEMISPACE_ALLOCATION_INFO(info, space) \
+ SLOW_DCHECK((space).page_low() <= (info).top() && \
+ (info).top() <= (space).page_high() && \
+ (info).limit() <= (space).page_high())
+
+
+// -----------------------------------------------------------------------------
+// Old space for all map objects
+
+class MapSpace : public PagedSpace {
+ public:
+ // Creates a map space object with a maximum capacity.
+ MapSpace(Heap* heap, intptr_t max_capacity, AllocationSpace id)
+ : PagedSpace(heap, max_capacity, id, NOT_EXECUTABLE),
+ max_map_space_pages_(kMaxMapPageIndex - 1) {}
+
+ // Given an index, returns the page address.
+ // TODO(1600): this limit is artifical just to keep code compilable
+ static const int kMaxMapPageIndex = 1 << 16;
+
+ virtual int RoundSizeDownToObjectAlignment(int size) {
+ if (base::bits::IsPowerOfTwo32(Map::kSize)) {
+ return RoundDown(size, Map::kSize);
+ } else {
+ return (size / Map::kSize) * Map::kSize;
+ }
+ }
+
+ protected:
+ virtual void VerifyObject(HeapObject* obj);
+
+ private:
+ static const int kMapsPerPage = Page::kMaxRegularHeapObjectSize / Map::kSize;
+
+ // Do map space compaction if there is a page gap.
+ int CompactionThreshold() {
+ return kMapsPerPage * (max_map_space_pages_ - 1);
+ }
+
+ const int max_map_space_pages_;
+
+ public:
+ TRACK_MEMORY("MapSpace")
+};
+
+
+// -----------------------------------------------------------------------------
+// Old space for simple property cell objects
+
+class CellSpace : public PagedSpace {
+ public:
+ // Creates a property cell space object with a maximum capacity.
+ CellSpace(Heap* heap, intptr_t max_capacity, AllocationSpace id)
+ : PagedSpace(heap, max_capacity, id, NOT_EXECUTABLE) {}
+
+ virtual int RoundSizeDownToObjectAlignment(int size) {
+ if (base::bits::IsPowerOfTwo32(Cell::kSize)) {
+ return RoundDown(size, Cell::kSize);
+ } else {
+ return (size / Cell::kSize) * Cell::kSize;
+ }
+ }
+
+ protected:
+ virtual void VerifyObject(HeapObject* obj);
+
+ public:
+ TRACK_MEMORY("CellSpace")
+};
+
+
+// -----------------------------------------------------------------------------
+// Old space for all global object property cell objects
+
+class PropertyCellSpace : public PagedSpace {
+ public:
+ // Creates a property cell space object with a maximum capacity.
+ PropertyCellSpace(Heap* heap, intptr_t max_capacity, AllocationSpace id)
+ : PagedSpace(heap, max_capacity, id, NOT_EXECUTABLE) {}
+
+ virtual int RoundSizeDownToObjectAlignment(int size) {
+ if (base::bits::IsPowerOfTwo32(PropertyCell::kSize)) {
+ return RoundDown(size, PropertyCell::kSize);
+ } else {
+ return (size / PropertyCell::kSize) * PropertyCell::kSize;
+ }
+ }
+
+ protected:
+ virtual void VerifyObject(HeapObject* obj);
+
+ public:
+ TRACK_MEMORY("PropertyCellSpace")
+};
+
+
+// -----------------------------------------------------------------------------
+// Large objects ( > Page::kMaxHeapObjectSize ) are allocated and managed by
+// the large object space. A large object is allocated from OS heap with
+// extra padding bytes (Page::kPageSize + Page::kObjectStartOffset).
+// A large object always starts at Page::kObjectStartOffset to a page.
+// Large objects do not move during garbage collections.
+
+class LargeObjectSpace : public Space {
+ public:
+ LargeObjectSpace(Heap* heap, intptr_t max_capacity, AllocationSpace id);
+ virtual ~LargeObjectSpace() {}
+
+ // Initializes internal data structures.
+ bool SetUp();
+
+ // Releases internal resources, frees objects in this space.
+ void TearDown();
+
+ static intptr_t ObjectSizeFor(intptr_t chunk_size) {
+ if (chunk_size <= (Page::kPageSize + Page::kObjectStartOffset)) return 0;
+ return chunk_size - Page::kPageSize - Page::kObjectStartOffset;
+ }
+
+ // Shared implementation of AllocateRaw, AllocateRawCode and
+ // AllocateRawFixedArray.
+ MUST_USE_RESULT AllocationResult
+ AllocateRaw(int object_size, Executability executable);
+
+ // Available bytes for objects in this space.
+ inline intptr_t Available();
+
+ virtual intptr_t Size() { return size_; }
+
+ virtual intptr_t SizeOfObjects() { return objects_size_; }
+
+ intptr_t MaximumCommittedMemory() { return maximum_committed_; }
+
+ intptr_t CommittedMemory() { return Size(); }
+
+ // Approximate amount of physical memory committed for this space.
+ size_t CommittedPhysicalMemory();
+
+ int PageCount() { return page_count_; }
+
+ // Finds an object for a given address, returns a Smi if it is not found.
+ // The function iterates through all objects in this space, may be slow.
+ Object* FindObject(Address a);
+
+ // Finds a large object page containing the given address, returns NULL
+ // if such a page doesn't exist.
+ LargePage* FindPage(Address a);
+
+ // Frees unmarked objects.
+ void FreeUnmarkedObjects();
+
+ // Checks whether a heap object is in this space; O(1).
+ bool Contains(HeapObject* obj);
+
+ // Checks whether the space is empty.
+ bool IsEmpty() { return first_page_ == NULL; }
+
+ LargePage* first_page() { return first_page_; }
+
+#ifdef VERIFY_HEAP
+ virtual void Verify();
+#endif
+
+#ifdef DEBUG
+ virtual void Print();
+ void ReportStatistics();
+ void CollectCodeStatistics();
+#endif
+ // Checks whether an address is in the object area in this space. It
+ // iterates all objects in the space. May be slow.
+ bool SlowContains(Address addr) { return FindObject(addr)->IsHeapObject(); }
+
+ private:
+ intptr_t max_capacity_;
+ intptr_t maximum_committed_;
+ // The head of the linked list of large object chunks.
+ LargePage* first_page_;
+ intptr_t size_; // allocated bytes
+ int page_count_; // number of chunks
+ intptr_t objects_size_; // size of objects
+ // Map MemoryChunk::kAlignment-aligned chunks to large pages covering them
+ HashMap chunk_map_;
+
+ friend class LargeObjectIterator;
+
+ public:
+ TRACK_MEMORY("LargeObjectSpace")
+};
+
+
+class LargeObjectIterator : public ObjectIterator {
+ public:
+ explicit LargeObjectIterator(LargeObjectSpace* space);
+ LargeObjectIterator(LargeObjectSpace* space, HeapObjectCallback size_func);
+
+ HeapObject* Next();
+
+ // implementation of ObjectIterator.
+ virtual HeapObject* next_object() { return Next(); }
+
+ private:
+ LargePage* current_;
+ HeapObjectCallback size_func_;
+};
+
+
+// Iterates over the chunks (pages and large object pages) that can contain
+// pointers to new space.
+class PointerChunkIterator BASE_EMBEDDED {
+ public:
+ inline explicit PointerChunkIterator(Heap* heap);
+
+ // Return NULL when the iterator is done.
+ MemoryChunk* next() {
+ switch (state_) {
+ case kOldPointerState: {
+ if (old_pointer_iterator_.has_next()) {
+ return old_pointer_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;
+ }
+
+
+ private:
+ enum State { kOldPointerState, kMapState, kLargeObjectState, kFinishedState };
+ State state_;
+ PageIterator old_pointer_iterator_;
+ PageIterator map_iterator_;
+ LargeObjectIterator lo_iterator_;
+};
+
+
+#ifdef DEBUG
+struct CommentStatistic {
+ const char* comment;
+ int size;
+ int count;
+ void Clear() {
+ comment = NULL;
+ size = 0;
+ count = 0;
+ }
+ // Must be small, since an iteration is used for lookup.
+ static const int kMaxComments = 64;
+};
+#endif
+}
+} // namespace v8::internal
+
+#endif // V8_HEAP_SPACES_H_