| // Copyright 2011 the V8 project authors. All rights reserved. |
| // Redistribution and use in source and binary forms, with or without |
| // modification, are permitted provided that the following conditions are |
| // met: |
| // |
| // * Redistributions of source code must retain the above copyright |
| // notice, this list of conditions and the following disclaimer. |
| // * Redistributions in binary form must reproduce the above |
| // copyright notice, this list of conditions and the following |
| // disclaimer in the documentation and/or other materials provided |
| // with the distribution. |
| // * Neither the name of Google Inc. nor the names of its |
| // contributors may be used to endorse or promote products derived |
| // from this software without specific prior written permission. |
| // |
| // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| |
| #ifndef V8_SPACES_H_ |
| #define V8_SPACES_H_ |
| |
| #include "allocation.h" |
| #include "list.h" |
| #include "log.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 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 ASSERT_PAGE_ALIGNED(address) \ |
| ASSERT((OffsetFrom(address) & Page::kPageAlignmentMask) == 0) |
| |
| #define ASSERT_OBJECT_ALIGNED(address) \ |
| ASSERT((OffsetFrom(address) & kObjectAlignmentMask) == 0) |
| |
| #define ASSERT_MAP_ALIGNED(address) \ |
| ASSERT((OffsetFrom(address) & kMapAlignmentMask) == 0) |
| |
| #define ASSERT_OBJECT_SIZE(size) \ |
| ASSERT((0 < size) && (size <= Page::kMaxNonCodeHeapObjectSize)) |
| |
| #define ASSERT_PAGE_OFFSET(offset) \ |
| ASSERT((Page::kObjectStartOffset <= offset) \ |
| && (offset <= Page::kPageSize)) |
| |
| #define ASSERT_MAP_PAGE_INDEX(index) \ |
| ASSERT((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); |
| } |
| |
| // Only works for addresses in pointer spaces, not data or code spaces. |
| static inline MemoryChunk* FromAnyPointerAddress(Address addr); |
| |
| Address address() { return reinterpret_cast<Address>(this); } |
| |
| bool is_valid() { return address() != NULL; } |
| |
| MemoryChunk* next_chunk() const { return next_chunk_; } |
| MemoryChunk* prev_chunk() const { return prev_chunk_; } |
| |
| void set_next_chunk(MemoryChunk* next) { next_chunk_ = next; } |
| void set_prev_chunk(MemoryChunk* prev) { prev_chunk_ = prev; } |
| |
| Space* owner() const { |
| if ((reinterpret_cast<intptr_t>(owner_) & kFailureTagMask) == |
| kFailureTag) { |
| return reinterpret_cast<Space*>(owner_ - kFailureTag); |
| } else { |
| return NULL; |
| } |
| } |
| |
| void set_owner(Space* space) { |
| ASSERT((reinterpret_cast<intptr_t>(space) & kFailureTagMask) == 0); |
| owner_ = reinterpret_cast<Address>(space) + kFailureTag; |
| ASSERT((reinterpret_cast<intptr_t>(owner_) & kFailureTagMask) == |
| kFailureTag); |
| } |
| |
| VirtualMemory* reserved_memory() { |
| return &reservation_; |
| } |
| |
| void InitializeReservedMemory() { |
| reservation_.Reset(); |
| } |
| |
| void set_reserved_memory(VirtualMemory* reservation) { |
| ASSERT_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(); |
| } |
| |
| 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, |
| |
| // Pages swept precisely can be iterated, hitting only the live objects. |
| // Whereas those swept conservatively cannot be iterated over. Both flags |
| // indicate that marking bits have been cleared by the sweeper, otherwise |
| // marking bits are still intact. |
| WAS_SWEPT_PRECISELY, |
| WAS_SWEPT_CONSERVATIVELY, |
| |
| // 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_; } |
| |
| // 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; |
| ASSERT_LE(static_cast<unsigned>(live_byte_count_), size_); |
| } |
| int LiveBytes() { |
| ASSERT(static_cast<unsigned>(live_byte_count_) <= size_); |
| return live_byte_count_; |
| } |
| |
| 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 = kPointerSize + kPointerSize; |
| |
| 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 kHeaderSize = |
| kSlotsBufferOffset + kPointerSize + kPointerSize; |
| |
| static const int kBodyOffset = |
| CODE_POINTER_ALIGN(MAP_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() { return heap_; } |
| |
| static const int kFlagsOffset = kPointerSize * 3; |
| |
| 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() { |
| ASSERT(slots_buffer_ == NULL); |
| SetFlag(EVACUATION_CANDIDATE); |
| } |
| |
| void ClearEvacuationCandidate() { |
| ASSERT(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()); |
| } |
| |
| protected: |
| MemoryChunk* next_chunk_; |
| MemoryChunk* prev_chunk_; |
| 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. |
| 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_; |
| |
| static MemoryChunk* Initialize(Heap* heap, |
| Address base, |
| size_t size, |
| Address area_start, |
| Address area_end, |
| Executability executable, |
| Space* owner); |
| |
| friend class MemoryAllocator; |
| }; |
| |
| STATIC_CHECK(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) { |
| ASSERT_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; |
| |
| // Object area size in bytes. |
| static const int kNonCodeObjectAreaSize = kPageSize - kObjectStartOffset; |
| |
| // Maximum object size that fits in a page. |
| static const int kMaxNonCodeHeapObjectSize = kNonCodeObjectAreaSize; |
| |
| // 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 WasSweptPrecisely() { return IsFlagSet(WAS_SWEPT_PRECISELY); } |
| bool WasSweptConservatively() { return IsFlagSet(WAS_SWEPT_CONSERVATIVELY); } |
| bool WasSwept() { return WasSweptPrecisely() || WasSweptConservatively(); } |
| |
| void MarkSweptPrecisely() { SetFlag(WAS_SWEPT_PRECISELY); } |
| void MarkSweptConservatively() { SetFlag(WAS_SWEPT_CONSERVATIVELY); } |
| |
| void ClearSweptPrecisely() { ClearFlag(WAS_SWEPT_PRECISELY); } |
| void ClearSweptConservatively() { ClearFlag(WAS_SWEPT_CONSERVATIVELY); } |
| |
| #ifdef DEBUG |
| void Print(); |
| #endif // DEBUG |
| |
| friend class MemoryAllocator; |
| }; |
| |
| |
| STATIC_CHECK(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_CHECK(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 |
| |
| // After calling this we can allocate a certain number of bytes using only |
| // linear allocation (with a LinearAllocationScope and an AlwaysAllocateScope) |
| // without using freelists or causing a GC. This is used by partial |
| // snapshots. It returns true of space was reserved or false if a GC is |
| // needed. For paged spaces the space requested must include the space wasted |
| // at the end of each when allocating linearly. |
| virtual bool ReserveSpace(int bytes) = 0; |
| |
| 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(const size_t requested_size); |
| |
| // Frees the range of virtual memory, and frees the data structures used to |
| // manage it. |
| void TearDown(); |
| |
| bool exists() { return this != NULL && code_range_ != NULL; } |
| bool contains(Address address) { |
| if (this == NULL || code_range_ == NULL) 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_t* allocated); |
| void FreeRawMemory(Address buf, size_t length); |
| |
| private: |
| Isolate* isolate_; |
| |
| // The reserved range of virtual memory that all code objects are put in. |
| 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) { |
| ASSERT(IsAddressAligned(start, MemoryChunk::kAlignment)); |
| ASSERT(size >= static_cast<size_t>(Page::kPageSize)); |
| } |
| FreeBlock(void* start_arg, size_t size_arg) |
| : start(static_cast<Address>(start_arg)), size(size_arg) { |
| ASSERT(IsAddressAligned(start, MemoryChunk::kAlignment)); |
| ASSERT(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, terminates V8 with FatalProcessOutOfMemory. |
| void 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(PagedSpace* owner, Executability executable); |
| |
| LargePage* AllocateLargePage(intptr_t object_size, |
| Executability executable, |
| Space* owner); |
| |
| 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::kMaxNonCodeHeapObjectSize; |
| } |
| |
| #ifdef DEBUG |
| // Reports statistic info of the space. |
| void ReportStatistics(); |
| #endif |
| |
| MemoryChunk* AllocateChunk(intptr_t body_size, |
| Executability executable, |
| Space* space); |
| |
| Address ReserveAlignedMemory(size_t requested, |
| size_t alignment, |
| VirtualMemory* controller); |
| Address AllocateAlignedMemory(size_t requested, |
| size_t alignment, |
| Executability executable, |
| VirtualMemory* controller); |
| |
| void FreeMemory(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(); |
| } |
| |
| static bool CommitCodePage(VirtualMemory* vm, Address start, size_t 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_; |
| |
| 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); |
| |
| 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) { |
| } |
| |
| Address top; // Current allocation top. |
| Address limit; // Current allocation limit. |
| |
| #ifdef DEBUG |
| bool VerifyPagedAllocation() { |
| return (Page::FromAllocationTop(top) == Page::FromAllocationTop(limit)) |
| && (top <= limit); |
| } |
| #endif |
| }; |
| |
| |
| // 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; |
| 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 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; |
| ASSERT(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; |
| ASSERT(size_ >= 0); |
| } |
| |
| // Allocate from available bytes (available -> size). |
| void AllocateBytes(intptr_t size_in_bytes) { |
| size_ += size_in_bytes; |
| ASSERT(size_ >= 0); |
| } |
| |
| // Free allocated bytes, making them available (size -> available). |
| void DeallocateBytes(intptr_t size_in_bytes) { |
| size_ -= size_in_bytes; |
| ASSERT(size_ >= 0); |
| } |
| |
| // Waste free bytes (available -> waste). |
| void WasteBytes(int size_in_bytes) { |
| size_ -= size_in_bytes; |
| waste_ += size_in_bytes; |
| ASSERT(size_ >= 0); |
| } |
| |
| private: |
| intptr_t 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(); |
| |
| private: |
| static const int kNextOffset = POINTER_SIZE_ALIGN(FreeSpace::kHeaderSize); |
| |
| DISALLOW_IMPLICIT_CONSTRUCTORS(FreeListNode); |
| }; |
| |
| |
| // 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 BASE_EMBEDDED { |
| public: |
| explicit FreeList(PagedSpace* owner); |
| |
| // Clear the free list. |
| void Reset(); |
| |
| // Return the number of bytes available on the free list. |
| intptr_t available() { return 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); |
| |
| // 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); |
| |
| #ifdef DEBUG |
| void Zap(); |
| static intptr_t SumFreeList(FreeListNode* node); |
| static int FreeListLength(FreeListNode* cur); |
| intptr_t SumFreeLists(); |
| bool IsVeryLong(); |
| #endif |
| |
| 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 CountFreeListItems(Page* p, SizeStats* sizes); |
| |
| intptr_t EvictFreeListItems(Page* p); |
| |
| private: |
| // The size range of blocks, in bytes. |
| static const int kMinBlockSize = 3 * kPointerSize; |
| static const int kMaxBlockSize = Page::kMaxNonCodeHeapObjectSize; |
| |
| FreeListNode* PickNodeFromList(FreeListNode** list, int* node_size); |
| |
| FreeListNode* FindNodeFor(int size_in_bytes, int* node_size); |
| |
| PagedSpace* owner_; |
| Heap* heap_; |
| |
| // Total available bytes in all blocks on this free list. |
| int available_; |
| |
| 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; |
| FreeListNode* small_list_; |
| FreeListNode* medium_list_; |
| FreeListNode* large_list_; |
| FreeListNode* huge_list_; |
| |
| DISALLOW_IMPLICIT_CONSTRUCTORS(FreeList); |
| }; |
| |
| |
| 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 Failure::Exception() 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. |
| MUST_USE_RESULT MaybeObject* FindObject(Address addr); |
| |
| // Prepares for a mark-compact GC. |
| virtual 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(); } |
| |
| // 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(); |
| } |
| |
| // 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 |
| // lazy 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() { |
| ASSERT(!IsSweepingComplete() || (unswept_free_bytes_ == 0)); |
| return Size() - unswept_free_bytes_ - (limit() - top()); |
| } |
| |
| // 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; } |
| |
| // Allocate the requested number of bytes in the space if possible, return a |
| // failure object if not. |
| MUST_USE_RESULT inline MaybeObject* AllocateRaw(int size_in_bytes); |
| |
| virtual bool ReserveSpace(int 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 - wasted); |
| return size_in_bytes - wasted; |
| } |
| |
| // Set space allocation info. |
| void SetTop(Address top, Address limit) { |
| ASSERT(top == limit || |
| Page::FromAddress(top) == Page::FromAddress(limit - 1)); |
| allocation_info_.top = top; |
| allocation_info_.limit = limit; |
| } |
| |
| void Allocate(int bytes) { |
| accounting_stats_.AllocateBytes(bytes); |
| } |
| |
| void IncreaseCapacity(int size) { |
| accounting_stats_.ExpandSpace(size); |
| } |
| |
| // Releases an unused page and shrinks the space. |
| void ReleasePage(Page* page); |
| |
| // Releases all of the unused pages. |
| void ReleaseAllUnusedPages(); |
| |
| // The dummy page that anchors the linked list of pages. |
| Page* anchor() { return &anchor_; } |
| |
| #ifdef DEBUG |
| // Print meta info and objects in this space. |
| virtual void Print(); |
| |
| // Verify integrity of this space. |
| virtual void Verify(ObjectVisitor* visitor); |
| |
| // Reports statistics for the space |
| void ReportStatistics(); |
| |
| // 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) {} |
| |
| // Report code object related statistics |
| void CollectCodeStatistics(); |
| static void ReportCodeStatistics(); |
| static void ResetCodeStatistics(); |
| #endif |
| |
| bool was_swept_conservatively() { return was_swept_conservatively_; } |
| void set_was_swept_conservatively(bool b) { was_swept_conservatively_ = b; } |
| |
| // Evacuation candidates are swept by evacuator. Needs to return a valid |
| // result before _and_ after evacuation has finished. |
| static bool ShouldBeSweptLazily(Page* p) { |
| return !p->IsEvacuationCandidate() && |
| !p->IsFlagSet(Page::RESCAN_ON_EVACUATION) && |
| !p->WasSweptPrecisely(); |
| } |
| |
| void SetPagesToSweep(Page* first) { |
| ASSERT(unswept_free_bytes_ == 0); |
| if (first == &anchor_) first = NULL; |
| first_unswept_page_ = first; |
| } |
| |
| void IncrementUnsweptFreeBytes(int by) { |
| unswept_free_bytes_ += by; |
| } |
| |
| void IncreaseUnsweptFreeBytes(Page* p) { |
| ASSERT(ShouldBeSweptLazily(p)); |
| unswept_free_bytes_ += (p->area_size() - p->LiveBytes()); |
| } |
| |
| void DecreaseUnsweptFreeBytes(Page* p) { |
| ASSERT(ShouldBeSweptLazily(p)); |
| unswept_free_bytes_ -= (p->area_size() - p->LiveBytes()); |
| } |
| |
| bool AdvanceSweeper(intptr_t bytes_to_sweep); |
| |
| bool IsSweepingComplete() { |
| return !first_unswept_page_->is_valid(); |
| } |
| |
| Page* FirstPage() { return anchor_.next_page(); } |
| Page* LastPage() { return anchor_.prev_page(); } |
| |
| void CountFreeListItems(Page* p, FreeList::SizeStats* sizes) { |
| free_list_.CountFreeListItems(p, sizes); |
| } |
| |
| 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_; |
| } |
| |
| protected: |
| int area_size_; |
| |
| // Maximum capacity of this space. |
| intptr_t max_capacity_; |
| |
| // 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_; |
| |
| // Bytes of each page that cannot be allocated. Possibly non-zero |
| // for pages in spaces with only fixed-size objects. Always zero |
| // for pages in spaces with variable sized objects (those pages are |
| // padded with free-list nodes). |
| int page_extra_; |
| |
| bool was_swept_conservatively_; |
| |
| // The first page to be swept when the lazy sweeper advances. Is set |
| // to NULL when all pages have been swept. |
| Page* first_unswept_page_; |
| |
| // The number of free bytes which could be reclaimed by advancing the |
| // lazy sweeper. This is only an estimation because lazy sweeping is |
| // done conservatively. |
| intptr_t unswept_free_bytes_; |
| |
| // 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); |
| |
| // Slow path of AllocateRaw. This function is space-dependent. |
| MUST_USE_RESULT virtual HeapObject* SlowAllocateRaw(int size_in_bytes); |
| |
| friend class PageIterator; |
| }; |
| |
| |
| 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::kNonCodeObjectAreaSize; |
| |
| 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 containg 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); |
| } |
| |
| 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() { |
| ASSERT(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; |
| } |
| |
| virtual bool ReserveSpace(int bytes) { |
| UNREACHABLE(); |
| return false; |
| } |
| |
| bool is_committed() { return committed_; } |
| bool Commit(); |
| bool Uncommit(); |
| |
| NewSpacePage* first_page() { return anchor_.next_page(); } |
| NewSpacePage* current_page() { return current_page_; } |
| |
| #ifdef DEBUG |
| virtual void Print(); |
| virtual void Verify(); |
| // 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 capacity of the semi space. |
| int Capacity() { return capacity_; } |
| |
| // Returns the maximum capacity of the semi space. |
| int MaximumCapacity() { return maximum_capacity_; } |
| |
| // Returns the initial capacity of the semi space. |
| int InitialCapacity() { return initial_capacity_; } |
| |
| SemiSpaceId id() { return id_; } |
| |
| static void Swap(SemiSpace* from, SemiSpace* to); |
| |
| 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); |
| |
| NewSpacePage* anchor() { return &anchor_; } |
| |
| // The current and maximum capacity of the space. |
| int capacity_; |
| int maximum_capacity_; |
| int initial_capacity_; |
| |
| // 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(); |
| ASSERT(!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_semispace_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 current capacity of a semispace. |
| intptr_t EffectiveCapacity() { |
| SLOW_ASSERT(to_space_.Capacity() == from_space_.Capacity()); |
| return (to_space_.Capacity() / Page::kPageSize) * NewSpacePage::kAreaSize; |
| } |
| |
| // Return the current capacity of a semispace. |
| intptr_t Capacity() { |
| ASSERT(to_space_.Capacity() == from_space_.Capacity()); |
| return to_space_.Capacity(); |
| } |
| |
| // Return the total amount of memory committed for new space. |
| intptr_t CommittedMemory() { |
| if (from_space_.is_committed()) return 2 * Capacity(); |
| return Capacity(); |
| } |
| |
| // Return the available bytes without growing. |
| intptr_t Available() { |
| return Capacity() - Size(); |
| } |
| |
| // Return the maximum capacity of a semispace. |
| int MaximumCapacity() { |
| ASSERT(to_space_.MaximumCapacity() == from_space_.MaximumCapacity()); |
| return to_space_.MaximumCapacity(); |
| } |
| |
| // Returns the initial capacity of a semispace. |
| int InitialCapacity() { |
| ASSERT(to_space_.InitialCapacity() == from_space_.InitialCapacity()); |
| return to_space_.InitialCapacity(); |
| } |
| |
| // Return the address of the allocation pointer in the active semispace. |
| Address top() { |
| ASSERT(to_space_.current_page()->ContainsLimit(allocation_info_.top)); |
| return allocation_info_.top; |
| } |
| // 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)) { |
| ASSERT(Contains(addr)); |
| ASSERT(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 addresses. |
| Address* allocation_top_address() { return &allocation_info_.top; } |
| Address* allocation_limit_address() { return &allocation_info_.limit; } |
| |
| MUST_USE_RESULT INLINE(MaybeObject* AllocateRaw(int size_in_bytes)); |
| |
| // Reset the allocation pointer to the beginning of the active semispace. |
| void ResetAllocationInfo(); |
| |
| void LowerInlineAllocationLimit(intptr_t step) { |
| inline_allocation_limit_step_ = step; |
| if (step == 0) { |
| allocation_info_.limit = to_space_.page_high(); |
| } else { |
| allocation_info_.limit = Min( |
| allocation_info_.top + inline_allocation_limit_step_, |
| allocation_info_.limit); |
| } |
| 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(); |
| |
| virtual bool ReserveSpace(int bytes); |
| |
| // Resizes a sequential string which must be the most recent thing that was |
| // allocated in new space. |
| template <typename StringType> |
| inline void ShrinkStringAtAllocationBoundary(String* string, int len); |
| |
| #ifdef DEBUG |
| // Verify the active semispace. |
| virtual void Verify(); |
| // 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_; |
| 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 MaybeObject* 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) { |
| page_extra_ = 0; |
| } |
| |
| // The limit of allocation for a page in this space. |
| virtual Address PageAllocationLimit(Page* page) { |
| return page->area_end(); |
| } |
| |
| 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 ASSERT_SEMISPACE_ALLOCATION_INFO(info, space) \ |
| SLOW_ASSERT((space).page_low() <= (info).top \ |
| && (info).top <= (space).page_high() \ |
| && (info).limit <= (space).page_high()) |
| |
| |
| // ----------------------------------------------------------------------------- |
| // Old space for objects of a fixed size |
| |
| class FixedSpace : public PagedSpace { |
| public: |
| FixedSpace(Heap* heap, |
| intptr_t max_capacity, |
| AllocationSpace id, |
| int object_size_in_bytes, |
| const char* name) |
| : PagedSpace(heap, max_capacity, id, NOT_EXECUTABLE), |
| object_size_in_bytes_(object_size_in_bytes), |
| name_(name) { |
| page_extra_ = Page::kNonCodeObjectAreaSize % object_size_in_bytes; |
| } |
| |
| // The limit of allocation for a page in this space. |
| virtual Address PageAllocationLimit(Page* page) { |
| return page->area_end() - page_extra_; |
| } |
| |
| int object_size_in_bytes() { return object_size_in_bytes_; } |
| |
| // Prepares for a mark-compact GC. |
| virtual void PrepareForMarkCompact(); |
| |
| protected: |
| void ResetFreeList() { |
| free_list_.Reset(); |
| } |
| |
| private: |
| // The size of objects in this space. |
| int object_size_in_bytes_; |
| |
| // The name of this space. |
| const char* name_; |
| }; |
| |
| |
| // ----------------------------------------------------------------------------- |
| // Old space for all map objects |
| |
| class MapSpace : public FixedSpace { |
| public: |
| // Creates a map space object with a maximum capacity. |
| MapSpace(Heap* heap, intptr_t max_capacity, AllocationSpace id) |
| : FixedSpace(heap, max_capacity, id, Map::kSize, "map"), |
| 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 (IsPowerOf2(Map::kSize)) { |
| return RoundDown(size, Map::kSize); |
| } else { |
| return (size / Map::kSize) * Map::kSize; |
| } |
| } |
| |
| protected: |
| #ifdef DEBUG |
| virtual void VerifyObject(HeapObject* obj); |
| #endif |
| |
| private: |
| static const int kMapsPerPage = Page::kNonCodeObjectAreaSize / 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 all global object property cell objects |
| |
| class CellSpace : public FixedSpace { |
| public: |
| // Creates a property cell space object with a maximum capacity. |
| CellSpace(Heap* heap, intptr_t max_capacity, AllocationSpace id) |
| : FixedSpace(heap, max_capacity, id, JSGlobalPropertyCell::kSize, "cell") |
| {} |
| |
| virtual int RoundSizeDownToObjectAlignment(int size) { |
| if (IsPowerOf2(JSGlobalPropertyCell::kSize)) { |
| return RoundDown(size, JSGlobalPropertyCell::kSize); |
| } else { |
| return (size / JSGlobalPropertyCell::kSize) * JSGlobalPropertyCell::kSize; |
| } |
| } |
| |
| protected: |
| #ifdef DEBUG |
| virtual void VerifyObject(HeapObject* obj); |
| #endif |
| |
| public: |
| TRACK_MEMORY("CellSpace") |
| }; |
| |
| |
| // ----------------------------------------------------------------------------- |
| // 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 MaybeObject* 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_; |
| } |
| |
| int PageCount() { |
| return page_count_; |
| } |
| |
| // Finds an object for a given address, returns Failure::Exception() |
| // if it is not found. The function iterates through all objects in this |
| // space, may be slow. |
| MaybeObject* FindObject(Address a); |
| |
| // Finds a large object page containing the given pc, returns NULL |
| // if such a page doesn't exist. |
| LargePage* FindPageContainingPc(Address pc); |
| |
| // 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; } |
| |
| // See the comments for ReserveSpace in the Space class. This has to be |
| // called after ReserveSpace has been called on the paged spaces, since they |
| // may use some memory, leaving less for large objects. |
| virtual bool ReserveSpace(int bytes); |
| |
| LargePage* first_page() { return first_page_; } |
| |
| #ifdef DEBUG |
| virtual void Verify(); |
| 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)->IsFailure(); } |
| |
| private: |
| intptr_t max_capacity_; |
| // 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 |
| |
| 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_SPACES_H_ |