| // Copyright 2012 the V8 project authors. All rights reserved. |
| // Redistribution and use in source and binary forms, with or without |
| // modification, are permitted provided that the following conditions are |
| // met: |
| // |
| // * Redistributions of source code must retain the above copyright |
| // notice, this list of conditions and the following disclaimer. |
| // * Redistributions in binary form must reproduce the above |
| // copyright notice, this list of conditions and the following |
| // disclaimer in the documentation and/or other materials provided |
| // with the distribution. |
| // * Neither the name of Google Inc. nor the names of its |
| // contributors may be used to endorse or promote products derived |
| // from this software without specific prior written permission. |
| // |
| // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| |
| #ifndef V8_MARK_COMPACT_H_ |
| #define V8_MARK_COMPACT_H_ |
| |
| #include "compiler-intrinsics.h" |
| #include "spaces.h" |
| |
| namespace v8 { |
| namespace internal { |
| |
| // Callback function, returns whether an object is alive. The heap size |
| // of the object is returned in size. It optionally updates the offset |
| // to the first live object in the page (only used for old and map objects). |
| typedef bool (*IsAliveFunction)(HeapObject* obj, int* size, int* offset); |
| |
| // Forward declarations. |
| class CodeFlusher; |
| class GCTracer; |
| class MarkCompactCollector; |
| class MarkingVisitor; |
| class RootMarkingVisitor; |
| |
| |
| class Marking { |
| public: |
| explicit Marking(Heap* heap) |
| : heap_(heap) { |
| } |
| |
| INLINE(static MarkBit MarkBitFrom(Address addr)); |
| |
| INLINE(static MarkBit MarkBitFrom(HeapObject* obj)) { |
| return MarkBitFrom(reinterpret_cast<Address>(obj)); |
| } |
| |
| // Impossible markbits: 01 |
| static const char* kImpossibleBitPattern; |
| INLINE(static bool IsImpossible(MarkBit mark_bit)) { |
| return !mark_bit.Get() && mark_bit.Next().Get(); |
| } |
| |
| // Black markbits: 10 - this is required by the sweeper. |
| static const char* kBlackBitPattern; |
| INLINE(static bool IsBlack(MarkBit mark_bit)) { |
| return mark_bit.Get() && !mark_bit.Next().Get(); |
| } |
| |
| // White markbits: 00 - this is required by the mark bit clearer. |
| static const char* kWhiteBitPattern; |
| INLINE(static bool IsWhite(MarkBit mark_bit)) { |
| return !mark_bit.Get(); |
| } |
| |
| // Grey markbits: 11 |
| static const char* kGreyBitPattern; |
| INLINE(static bool IsGrey(MarkBit mark_bit)) { |
| return mark_bit.Get() && mark_bit.Next().Get(); |
| } |
| |
| INLINE(static void MarkBlack(MarkBit mark_bit)) { |
| mark_bit.Set(); |
| mark_bit.Next().Clear(); |
| } |
| |
| INLINE(static void BlackToGrey(MarkBit markbit)) { |
| markbit.Next().Set(); |
| } |
| |
| INLINE(static void WhiteToGrey(MarkBit markbit)) { |
| markbit.Set(); |
| markbit.Next().Set(); |
| } |
| |
| INLINE(static void GreyToBlack(MarkBit markbit)) { |
| markbit.Next().Clear(); |
| } |
| |
| INLINE(static void BlackToGrey(HeapObject* obj)) { |
| BlackToGrey(MarkBitFrom(obj)); |
| } |
| |
| INLINE(static void AnyToGrey(MarkBit markbit)) { |
| markbit.Set(); |
| markbit.Next().Set(); |
| } |
| |
| void TransferMark(Address old_start, Address new_start); |
| |
| #ifdef DEBUG |
| enum ObjectColor { |
| BLACK_OBJECT, |
| WHITE_OBJECT, |
| GREY_OBJECT, |
| IMPOSSIBLE_COLOR |
| }; |
| |
| static const char* ColorName(ObjectColor color) { |
| switch (color) { |
| case BLACK_OBJECT: return "black"; |
| case WHITE_OBJECT: return "white"; |
| case GREY_OBJECT: return "grey"; |
| case IMPOSSIBLE_COLOR: return "impossible"; |
| } |
| return "error"; |
| } |
| |
| static ObjectColor Color(HeapObject* obj) { |
| return Color(Marking::MarkBitFrom(obj)); |
| } |
| |
| static ObjectColor Color(MarkBit mark_bit) { |
| if (IsBlack(mark_bit)) return BLACK_OBJECT; |
| if (IsWhite(mark_bit)) return WHITE_OBJECT; |
| if (IsGrey(mark_bit)) return GREY_OBJECT; |
| UNREACHABLE(); |
| return IMPOSSIBLE_COLOR; |
| } |
| #endif |
| |
| // Returns true if the transferred color is black. |
| INLINE(static bool TransferColor(HeapObject* from, |
| HeapObject* to)) { |
| MarkBit from_mark_bit = MarkBitFrom(from); |
| MarkBit to_mark_bit = MarkBitFrom(to); |
| bool is_black = false; |
| if (from_mark_bit.Get()) { |
| to_mark_bit.Set(); |
| is_black = true; // Looks black so far. |
| } |
| if (from_mark_bit.Next().Get()) { |
| to_mark_bit.Next().Set(); |
| is_black = false; // Was actually gray. |
| } |
| return is_black; |
| } |
| |
| private: |
| Heap* heap_; |
| }; |
| |
| // ---------------------------------------------------------------------------- |
| // Marking deque for tracing live objects. |
| class MarkingDeque { |
| public: |
| MarkingDeque() |
| : array_(NULL), top_(0), bottom_(0), mask_(0), overflowed_(false) { } |
| |
| void Initialize(Address low, Address high) { |
| HeapObject** obj_low = reinterpret_cast<HeapObject**>(low); |
| HeapObject** obj_high = reinterpret_cast<HeapObject**>(high); |
| array_ = obj_low; |
| mask_ = RoundDownToPowerOf2(static_cast<int>(obj_high - obj_low)) - 1; |
| top_ = bottom_ = 0; |
| overflowed_ = false; |
| } |
| |
| inline bool IsFull() { return ((top_ + 1) & mask_) == bottom_; } |
| |
| inline bool IsEmpty() { return top_ == bottom_; } |
| |
| bool overflowed() const { return overflowed_; } |
| |
| void ClearOverflowed() { overflowed_ = false; } |
| |
| void SetOverflowed() { overflowed_ = true; } |
| |
| // Push the (marked) object on the marking stack if there is room, |
| // otherwise mark the object as overflowed and wait for a rescan of the |
| // heap. |
| INLINE(void PushBlack(HeapObject* object)) { |
| ASSERT(object->IsHeapObject()); |
| if (IsFull()) { |
| Marking::BlackToGrey(object); |
| MemoryChunk::IncrementLiveBytesFromGC(object->address(), -object->Size()); |
| SetOverflowed(); |
| } else { |
| array_[top_] = object; |
| top_ = ((top_ + 1) & mask_); |
| } |
| } |
| |
| INLINE(void PushGrey(HeapObject* object)) { |
| ASSERT(object->IsHeapObject()); |
| if (IsFull()) { |
| SetOverflowed(); |
| } else { |
| array_[top_] = object; |
| top_ = ((top_ + 1) & mask_); |
| } |
| } |
| |
| INLINE(HeapObject* Pop()) { |
| ASSERT(!IsEmpty()); |
| top_ = ((top_ - 1) & mask_); |
| HeapObject* object = array_[top_]; |
| ASSERT(object->IsHeapObject()); |
| return object; |
| } |
| |
| INLINE(void UnshiftGrey(HeapObject* object)) { |
| ASSERT(object->IsHeapObject()); |
| if (IsFull()) { |
| SetOverflowed(); |
| } else { |
| bottom_ = ((bottom_ - 1) & mask_); |
| array_[bottom_] = object; |
| } |
| } |
| |
| HeapObject** array() { return array_; } |
| int bottom() { return bottom_; } |
| int top() { return top_; } |
| int mask() { return mask_; } |
| void set_top(int top) { top_ = top; } |
| |
| private: |
| HeapObject** array_; |
| // array_[(top - 1) & mask_] is the top element in the deque. The Deque is |
| // empty when top_ == bottom_. It is full when top_ + 1 == bottom |
| // (mod mask + 1). |
| int top_; |
| int bottom_; |
| int mask_; |
| bool overflowed_; |
| |
| DISALLOW_COPY_AND_ASSIGN(MarkingDeque); |
| }; |
| |
| |
| class SlotsBufferAllocator { |
| public: |
| SlotsBuffer* AllocateBuffer(SlotsBuffer* next_buffer); |
| void DeallocateBuffer(SlotsBuffer* buffer); |
| |
| void DeallocateChain(SlotsBuffer** buffer_address); |
| }; |
| |
| |
| // SlotsBuffer records a sequence of slots that has to be updated |
| // after live objects were relocated from evacuation candidates. |
| // All slots are either untyped or typed: |
| // - Untyped slots are expected to contain a tagged object pointer. |
| // They are recorded by an address. |
| // - Typed slots are expected to contain an encoded pointer to a heap |
| // object where the way of encoding depends on the type of the slot. |
| // They are recorded as a pair (SlotType, slot address). |
| // We assume that zero-page is never mapped this allows us to distinguish |
| // untyped slots from typed slots during iteration by a simple comparison: |
| // if element of slots buffer is less than NUMBER_OF_SLOT_TYPES then it |
| // is the first element of typed slot's pair. |
| class SlotsBuffer { |
| public: |
| typedef Object** ObjectSlot; |
| |
| explicit SlotsBuffer(SlotsBuffer* next_buffer) |
| : idx_(0), chain_length_(1), next_(next_buffer) { |
| if (next_ != NULL) { |
| chain_length_ = next_->chain_length_ + 1; |
| } |
| } |
| |
| ~SlotsBuffer() { |
| } |
| |
| void Add(ObjectSlot slot) { |
| ASSERT(0 <= idx_ && idx_ < kNumberOfElements); |
| slots_[idx_++] = slot; |
| } |
| |
| enum SlotType { |
| EMBEDDED_OBJECT_SLOT, |
| RELOCATED_CODE_OBJECT, |
| CODE_TARGET_SLOT, |
| CODE_ENTRY_SLOT, |
| DEBUG_TARGET_SLOT, |
| JS_RETURN_SLOT, |
| NUMBER_OF_SLOT_TYPES |
| }; |
| |
| static const char* SlotTypeToString(SlotType type) { |
| switch (type) { |
| case EMBEDDED_OBJECT_SLOT: |
| return "EMBEDDED_OBJECT_SLOT"; |
| case RELOCATED_CODE_OBJECT: |
| return "RELOCATED_CODE_OBJECT"; |
| case CODE_TARGET_SLOT: |
| return "CODE_TARGET_SLOT"; |
| case CODE_ENTRY_SLOT: |
| return "CODE_ENTRY_SLOT"; |
| case DEBUG_TARGET_SLOT: |
| return "DEBUG_TARGET_SLOT"; |
| case JS_RETURN_SLOT: |
| return "JS_RETURN_SLOT"; |
| case NUMBER_OF_SLOT_TYPES: |
| return "NUMBER_OF_SLOT_TYPES"; |
| } |
| return "UNKNOWN SlotType"; |
| } |
| |
| void UpdateSlots(Heap* heap); |
| |
| void UpdateSlotsWithFilter(Heap* heap); |
| |
| SlotsBuffer* next() { return next_; } |
| |
| static int SizeOfChain(SlotsBuffer* buffer) { |
| if (buffer == NULL) return 0; |
| return static_cast<int>(buffer->idx_ + |
| (buffer->chain_length_ - 1) * kNumberOfElements); |
| } |
| |
| inline bool IsFull() { |
| return idx_ == kNumberOfElements; |
| } |
| |
| inline bool HasSpaceForTypedSlot() { |
| return idx_ < kNumberOfElements - 1; |
| } |
| |
| static void UpdateSlotsRecordedIn(Heap* heap, |
| SlotsBuffer* buffer, |
| bool code_slots_filtering_required) { |
| while (buffer != NULL) { |
| if (code_slots_filtering_required) { |
| buffer->UpdateSlotsWithFilter(heap); |
| } else { |
| buffer->UpdateSlots(heap); |
| } |
| buffer = buffer->next(); |
| } |
| } |
| |
| enum AdditionMode { |
| FAIL_ON_OVERFLOW, |
| IGNORE_OVERFLOW |
| }; |
| |
| static bool ChainLengthThresholdReached(SlotsBuffer* buffer) { |
| return buffer != NULL && buffer->chain_length_ >= kChainLengthThreshold; |
| } |
| |
| INLINE(static bool AddTo(SlotsBufferAllocator* allocator, |
| SlotsBuffer** buffer_address, |
| ObjectSlot slot, |
| AdditionMode mode)) { |
| SlotsBuffer* buffer = *buffer_address; |
| if (buffer == NULL || buffer->IsFull()) { |
| if (mode == FAIL_ON_OVERFLOW && ChainLengthThresholdReached(buffer)) { |
| allocator->DeallocateChain(buffer_address); |
| return false; |
| } |
| buffer = allocator->AllocateBuffer(buffer); |
| *buffer_address = buffer; |
| } |
| buffer->Add(slot); |
| return true; |
| } |
| |
| static bool IsTypedSlot(ObjectSlot slot); |
| |
| static bool AddTo(SlotsBufferAllocator* allocator, |
| SlotsBuffer** buffer_address, |
| SlotType type, |
| Address addr, |
| AdditionMode mode); |
| |
| static const int kNumberOfElements = 1021; |
| |
| private: |
| static const int kChainLengthThreshold = 15; |
| |
| intptr_t idx_; |
| intptr_t chain_length_; |
| SlotsBuffer* next_; |
| ObjectSlot slots_[kNumberOfElements]; |
| }; |
| |
| |
| // CodeFlusher collects candidates for code flushing during marking and |
| // processes those candidates after marking has completed in order to |
| // reset those functions referencing code objects that would otherwise |
| // be unreachable. Code objects can be referenced in three ways: |
| // - SharedFunctionInfo references unoptimized code. |
| // - JSFunction references either unoptimized or optimized code. |
| // - OptimizedCodeMap references optimized code. |
| // We are not allowed to flush unoptimized code for functions that got |
| // optimized or inlined into optimized code, because we might bailout |
| // into the unoptimized code again during deoptimization. |
| class CodeFlusher { |
| public: |
| explicit CodeFlusher(Isolate* isolate) |
| : isolate_(isolate), |
| jsfunction_candidates_head_(NULL), |
| shared_function_info_candidates_head_(NULL), |
| optimized_code_map_holder_head_(NULL) {} |
| |
| void AddCandidate(SharedFunctionInfo* shared_info) { |
| if (GetNextCandidate(shared_info) == NULL) { |
| SetNextCandidate(shared_info, shared_function_info_candidates_head_); |
| shared_function_info_candidates_head_ = shared_info; |
| } |
| } |
| |
| void AddCandidate(JSFunction* function) { |
| ASSERT(function->code() == function->shared()->code()); |
| if (GetNextCandidate(function)->IsUndefined()) { |
| SetNextCandidate(function, jsfunction_candidates_head_); |
| jsfunction_candidates_head_ = function; |
| } |
| } |
| |
| void AddOptimizedCodeMap(SharedFunctionInfo* code_map_holder) { |
| if (GetNextCodeMap(code_map_holder)->IsUndefined()) { |
| SetNextCodeMap(code_map_holder, optimized_code_map_holder_head_); |
| optimized_code_map_holder_head_ = code_map_holder; |
| } |
| } |
| |
| void EvictOptimizedCodeMap(SharedFunctionInfo* code_map_holder); |
| void EvictCandidate(SharedFunctionInfo* shared_info); |
| void EvictCandidate(JSFunction* function); |
| |
| void ProcessCandidates() { |
| ProcessOptimizedCodeMaps(); |
| ProcessSharedFunctionInfoCandidates(); |
| ProcessJSFunctionCandidates(); |
| } |
| |
| void EvictAllCandidates() { |
| EvictOptimizedCodeMaps(); |
| EvictJSFunctionCandidates(); |
| EvictSharedFunctionInfoCandidates(); |
| } |
| |
| void IteratePointersToFromSpace(ObjectVisitor* v); |
| |
| private: |
| void ProcessOptimizedCodeMaps(); |
| void ProcessJSFunctionCandidates(); |
| void ProcessSharedFunctionInfoCandidates(); |
| void EvictOptimizedCodeMaps(); |
| void EvictJSFunctionCandidates(); |
| void EvictSharedFunctionInfoCandidates(); |
| |
| static JSFunction** GetNextCandidateSlot(JSFunction* candidate) { |
| return reinterpret_cast<JSFunction**>( |
| HeapObject::RawField(candidate, JSFunction::kNextFunctionLinkOffset)); |
| } |
| |
| static JSFunction* GetNextCandidate(JSFunction* candidate) { |
| Object* next_candidate = candidate->next_function_link(); |
| return reinterpret_cast<JSFunction*>(next_candidate); |
| } |
| |
| static void SetNextCandidate(JSFunction* candidate, |
| JSFunction* next_candidate) { |
| candidate->set_next_function_link(next_candidate); |
| } |
| |
| static void ClearNextCandidate(JSFunction* candidate, Object* undefined) { |
| ASSERT(undefined->IsUndefined()); |
| candidate->set_next_function_link(undefined, SKIP_WRITE_BARRIER); |
| } |
| |
| static SharedFunctionInfo* GetNextCandidate(SharedFunctionInfo* candidate) { |
| Object* next_candidate = candidate->code()->gc_metadata(); |
| return reinterpret_cast<SharedFunctionInfo*>(next_candidate); |
| } |
| |
| static void SetNextCandidate(SharedFunctionInfo* candidate, |
| SharedFunctionInfo* next_candidate) { |
| candidate->code()->set_gc_metadata(next_candidate); |
| } |
| |
| static void ClearNextCandidate(SharedFunctionInfo* candidate) { |
| candidate->code()->set_gc_metadata(NULL, SKIP_WRITE_BARRIER); |
| } |
| |
| static SharedFunctionInfo* GetNextCodeMap(SharedFunctionInfo* holder) { |
| FixedArray* code_map = FixedArray::cast(holder->optimized_code_map()); |
| Object* next_map = code_map->get(SharedFunctionInfo::kNextMapIndex); |
| return reinterpret_cast<SharedFunctionInfo*>(next_map); |
| } |
| |
| static void SetNextCodeMap(SharedFunctionInfo* holder, |
| SharedFunctionInfo* next_holder) { |
| FixedArray* code_map = FixedArray::cast(holder->optimized_code_map()); |
| code_map->set(SharedFunctionInfo::kNextMapIndex, next_holder); |
| } |
| |
| static void ClearNextCodeMap(SharedFunctionInfo* holder) { |
| FixedArray* code_map = FixedArray::cast(holder->optimized_code_map()); |
| code_map->set_undefined(SharedFunctionInfo::kNextMapIndex); |
| } |
| |
| Isolate* isolate_; |
| JSFunction* jsfunction_candidates_head_; |
| SharedFunctionInfo* shared_function_info_candidates_head_; |
| SharedFunctionInfo* optimized_code_map_holder_head_; |
| |
| DISALLOW_COPY_AND_ASSIGN(CodeFlusher); |
| }; |
| |
| |
| // Defined in isolate.h. |
| class ThreadLocalTop; |
| |
| |
| // ------------------------------------------------------------------------- |
| // Mark-Compact collector |
| class MarkCompactCollector { |
| public: |
| // Set the global flags, it must be called before Prepare to take effect. |
| inline void SetFlags(int flags); |
| |
| static void Initialize(); |
| |
| void SetUp(); |
| |
| void TearDown(); |
| |
| void CollectEvacuationCandidates(PagedSpace* space); |
| |
| void AddEvacuationCandidate(Page* p); |
| |
| // Prepares for GC by resetting relocation info in old and map spaces and |
| // choosing spaces to compact. |
| void Prepare(GCTracer* tracer); |
| |
| // Performs a global garbage collection. |
| void CollectGarbage(); |
| |
| enum CompactionMode { |
| INCREMENTAL_COMPACTION, |
| NON_INCREMENTAL_COMPACTION |
| }; |
| |
| bool StartCompaction(CompactionMode mode); |
| |
| void AbortCompaction(); |
| |
| // During a full GC, there is a stack-allocated GCTracer that is used for |
| // bookkeeping information. Return a pointer to that tracer. |
| GCTracer* tracer() { return tracer_; } |
| |
| #ifdef DEBUG |
| // Checks whether performing mark-compact collection. |
| bool in_use() { return state_ > PREPARE_GC; } |
| bool are_map_pointers_encoded() { return state_ == UPDATE_POINTERS; } |
| #endif |
| |
| // Determine type of object and emit deletion log event. |
| static void ReportDeleteIfNeeded(HeapObject* obj, Isolate* isolate); |
| |
| // Distinguishable invalid map encodings (for single word and multiple words) |
| // that indicate free regions. |
| static const uint32_t kSingleFreeEncoding = 0; |
| static const uint32_t kMultiFreeEncoding = 1; |
| |
| static inline bool IsMarked(Object* obj); |
| |
| inline Heap* heap() const { return heap_; } |
| inline Isolate* isolate() const; |
| |
| CodeFlusher* code_flusher() { return code_flusher_; } |
| inline bool is_code_flushing_enabled() const { return code_flusher_ != NULL; } |
| void EnableCodeFlushing(bool enable); |
| |
| enum SweeperType { |
| CONSERVATIVE, |
| LAZY_CONSERVATIVE, |
| PARALLEL_CONSERVATIVE, |
| CONCURRENT_CONSERVATIVE, |
| PRECISE |
| }; |
| |
| enum SweepingParallelism { |
| SWEEP_SEQUENTIALLY, |
| SWEEP_IN_PARALLEL |
| }; |
| |
| #ifdef VERIFY_HEAP |
| void VerifyMarkbitsAreClean(); |
| static void VerifyMarkbitsAreClean(PagedSpace* space); |
| static void VerifyMarkbitsAreClean(NewSpace* space); |
| void VerifyWeakEmbeddedObjectsInOptimizedCode(); |
| void VerifyOmittedMapChecks(); |
| #endif |
| |
| // Sweep a single page from the given space conservatively. |
| // Return a number of reclaimed bytes. |
| template<SweepingParallelism type> |
| static intptr_t SweepConservatively(PagedSpace* space, |
| FreeList* free_list, |
| Page* p); |
| |
| INLINE(static bool ShouldSkipEvacuationSlotRecording(Object** anchor)) { |
| return Page::FromAddress(reinterpret_cast<Address>(anchor))-> |
| ShouldSkipEvacuationSlotRecording(); |
| } |
| |
| INLINE(static bool ShouldSkipEvacuationSlotRecording(Object* host)) { |
| return Page::FromAddress(reinterpret_cast<Address>(host))-> |
| ShouldSkipEvacuationSlotRecording(); |
| } |
| |
| INLINE(static bool IsOnEvacuationCandidate(Object* obj)) { |
| return Page::FromAddress(reinterpret_cast<Address>(obj))-> |
| IsEvacuationCandidate(); |
| } |
| |
| INLINE(void EvictEvacuationCandidate(Page* page)) { |
| if (FLAG_trace_fragmentation) { |
| PrintF("Page %p is too popular. Disabling evacuation.\n", |
| reinterpret_cast<void*>(page)); |
| } |
| |
| // TODO(gc) If all evacuation candidates are too popular we |
| // should stop slots recording entirely. |
| page->ClearEvacuationCandidate(); |
| |
| // We were not collecting slots on this page that point |
| // to other evacuation candidates thus we have to |
| // rescan the page after evacuation to discover and update all |
| // pointers to evacuated objects. |
| if (page->owner()->identity() == OLD_DATA_SPACE) { |
| evacuation_candidates_.RemoveElement(page); |
| } else { |
| page->SetFlag(Page::RESCAN_ON_EVACUATION); |
| } |
| } |
| |
| void RecordRelocSlot(RelocInfo* rinfo, Object* target); |
| void RecordCodeEntrySlot(Address slot, Code* target); |
| void RecordCodeTargetPatch(Address pc, Code* target); |
| |
| INLINE(void RecordSlot(Object** anchor_slot, |
| Object** slot, |
| Object* object, |
| SlotsBuffer::AdditionMode mode = |
| SlotsBuffer::FAIL_ON_OVERFLOW)); |
| |
| void MigrateObject(HeapObject* dst, |
| HeapObject* src, |
| int size, |
| AllocationSpace to_old_space); |
| |
| bool TryPromoteObject(HeapObject* object, int object_size); |
| |
| inline Object* encountered_weak_collections() { |
| return encountered_weak_collections_; |
| } |
| inline void set_encountered_weak_collections(Object* weak_collection) { |
| encountered_weak_collections_ = weak_collection; |
| } |
| |
| void InvalidateCode(Code* code); |
| |
| void ClearMarkbits(); |
| |
| bool abort_incremental_marking() const { return abort_incremental_marking_; } |
| |
| bool is_compacting() const { return compacting_; } |
| |
| MarkingParity marking_parity() { return marking_parity_; } |
| |
| // Concurrent and parallel sweeping support. |
| void SweepInParallel(PagedSpace* space); |
| |
| void WaitUntilSweepingCompleted(); |
| |
| intptr_t RefillFreeLists(PagedSpace* space); |
| |
| bool AreSweeperThreadsActivated(); |
| |
| bool IsConcurrentSweepingInProgress(); |
| |
| void set_sequential_sweeping(bool sequential_sweeping) { |
| sequential_sweeping_ = sequential_sweeping; |
| } |
| |
| bool sequential_sweeping() const { |
| return sequential_sweeping_; |
| } |
| |
| // Mark the global table which maps weak objects to dependent code without |
| // marking its contents. |
| void MarkWeakObjectToCodeTable(); |
| |
| // Special case for processing weak references in a full collection. We need |
| // to artifically keep AllocationSites alive for a time. |
| void MarkAllocationSite(AllocationSite* site); |
| |
| private: |
| class SweeperTask; |
| |
| explicit MarkCompactCollector(Heap* heap); |
| ~MarkCompactCollector(); |
| |
| bool MarkInvalidatedCode(); |
| bool WillBeDeoptimized(Code* code); |
| void RemoveDeadInvalidatedCode(); |
| void ProcessInvalidatedCode(ObjectVisitor* visitor); |
| |
| void UnlinkEvacuationCandidates(); |
| void ReleaseEvacuationCandidates(); |
| |
| void StartSweeperThreads(); |
| |
| #ifdef DEBUG |
| enum CollectorState { |
| IDLE, |
| PREPARE_GC, |
| MARK_LIVE_OBJECTS, |
| SWEEP_SPACES, |
| ENCODE_FORWARDING_ADDRESSES, |
| UPDATE_POINTERS, |
| RELOCATE_OBJECTS |
| }; |
| |
| // The current stage of the collector. |
| CollectorState state_; |
| #endif |
| |
| // Global flag that forces sweeping to be precise, so we can traverse the |
| // heap. |
| bool sweep_precisely_; |
| |
| bool reduce_memory_footprint_; |
| |
| bool abort_incremental_marking_; |
| |
| MarkingParity marking_parity_; |
| |
| // True if we are collecting slots to perform evacuation from evacuation |
| // candidates. |
| bool compacting_; |
| |
| bool was_marked_incrementally_; |
| |
| // True if concurrent or parallel sweeping is currently in progress. |
| bool sweeping_pending_; |
| |
| Semaphore pending_sweeper_jobs_semaphore_; |
| |
| bool sequential_sweeping_; |
| |
| // A pointer to the current stack-allocated GC tracer object during a full |
| // collection (NULL before and after). |
| GCTracer* tracer_; |
| |
| SlotsBufferAllocator slots_buffer_allocator_; |
| |
| SlotsBuffer* migration_slots_buffer_; |
| |
| // Finishes GC, performs heap verification if enabled. |
| void Finish(); |
| |
| // ----------------------------------------------------------------------- |
| // Phase 1: Marking live objects. |
| // |
| // Before: The heap has been prepared for garbage collection by |
| // MarkCompactCollector::Prepare() and is otherwise in its |
| // normal state. |
| // |
| // After: Live objects are marked and non-live objects are unmarked. |
| |
| friend class RootMarkingVisitor; |
| friend class MarkingVisitor; |
| friend class MarkCompactMarkingVisitor; |
| friend class CodeMarkingVisitor; |
| friend class SharedFunctionInfoMarkingVisitor; |
| |
| // Mark code objects that are active on the stack to prevent them |
| // from being flushed. |
| void PrepareThreadForCodeFlushing(Isolate* isolate, ThreadLocalTop* top); |
| |
| void PrepareForCodeFlushing(); |
| |
| // Marking operations for objects reachable from roots. |
| void MarkLiveObjects(); |
| |
| void AfterMarking(); |
| |
| // Marks the object black and pushes it on the marking stack. |
| // This is for non-incremental marking only. |
| INLINE(void MarkObject(HeapObject* obj, MarkBit mark_bit)); |
| |
| // Marks the object black assuming that it is not yet marked. |
| // This is for non-incremental marking only. |
| INLINE(void SetMark(HeapObject* obj, MarkBit mark_bit)); |
| |
| // Mark the heap roots and all objects reachable from them. |
| void MarkRoots(RootMarkingVisitor* visitor); |
| |
| // Mark the string table specially. References to internalized strings from |
| // the string table are weak. |
| void MarkStringTable(RootMarkingVisitor* visitor); |
| |
| // Mark objects in implicit references groups if their parent object |
| // is marked. |
| void MarkImplicitRefGroups(); |
| |
| // Mark objects reachable (transitively) from objects in the marking stack |
| // or overflowed in the heap. |
| void ProcessMarkingDeque(); |
| |
| // Mark objects reachable (transitively) from objects in the marking stack |
| // or overflowed in the heap. This respects references only considered in |
| // the final atomic marking pause including the following: |
| // - Processing of objects reachable through Harmony WeakMaps. |
| // - Objects reachable due to host application logic like object groups |
| // or implicit references' groups. |
| void ProcessEphemeralMarking(ObjectVisitor* visitor); |
| |
| // If the call-site of the top optimized code was not prepared for |
| // deoptimization, then treat the maps in the code as strong pointers, |
| // otherwise a map can die and deoptimize the code. |
| void ProcessTopOptimizedFrame(ObjectVisitor* visitor); |
| |
| // Mark objects reachable (transitively) from objects in the marking |
| // stack. This function empties the marking stack, but may leave |
| // overflowed objects in the heap, in which case the marking stack's |
| // overflow flag will be set. |
| void EmptyMarkingDeque(); |
| |
| // Refill the marking stack with overflowed objects from the heap. This |
| // function either leaves the marking stack full or clears the overflow |
| // flag on the marking stack. |
| void RefillMarkingDeque(); |
| |
| // After reachable maps have been marked process per context object |
| // literal map caches removing unmarked entries. |
| void ProcessMapCaches(); |
| |
| // Callback function for telling whether the object *p is an unmarked |
| // heap object. |
| static bool IsUnmarkedHeapObject(Object** p); |
| static bool IsUnmarkedHeapObjectWithHeap(Heap* heap, Object** p); |
| |
| // Map transitions from a live map to a dead map must be killed. |
| // We replace them with a null descriptor, with the same key. |
| void ClearNonLiveReferences(); |
| void ClearNonLivePrototypeTransitions(Map* map); |
| void ClearNonLiveMapTransitions(Map* map, MarkBit map_mark); |
| |
| void ClearAndDeoptimizeDependentCode(DependentCode* dependent_code); |
| void ClearNonLiveDependentCode(DependentCode* dependent_code); |
| |
| // Marking detaches initial maps from SharedFunctionInfo objects |
| // to make this reference weak. We need to reattach initial maps |
| // back after collection. This is either done during |
| // ClearNonLiveTransitions pass or by calling this function. |
| void ReattachInitialMaps(); |
| |
| // Mark all values associated with reachable keys in weak collections |
| // encountered so far. This might push new object or even new weak maps onto |
| // the marking stack. |
| void ProcessWeakCollections(); |
| |
| // After all reachable objects have been marked those weak map entries |
| // with an unreachable key are removed from all encountered weak maps. |
| // The linked list of all encountered weak maps is destroyed. |
| void ClearWeakCollections(); |
| |
| // ----------------------------------------------------------------------- |
| // Phase 2: Sweeping to clear mark bits and free non-live objects for |
| // a non-compacting collection. |
| // |
| // Before: Live objects are marked and non-live objects are unmarked. |
| // |
| // After: Live objects are unmarked, non-live regions have been added to |
| // their space's free list. Active eden semispace is compacted by |
| // evacuation. |
| // |
| |
| // If we are not compacting the heap, we simply sweep the spaces except |
| // for the large object space, clearing mark bits and adding unmarked |
| // regions to each space's free list. |
| void SweepSpaces(); |
| |
| int DiscoverAndPromoteBlackObjectsOnPage(NewSpace* new_space, |
| NewSpacePage* p); |
| |
| void EvacuateNewSpace(); |
| |
| void EvacuateLiveObjectsFromPage(Page* p); |
| |
| void EvacuatePages(); |
| |
| void EvacuateNewSpaceAndCandidates(); |
| |
| void SweepSpace(PagedSpace* space, SweeperType sweeper); |
| |
| // Finalizes the parallel sweeping phase. Marks all the pages that were |
| // swept in parallel. |
| void ParallelSweepSpacesComplete(); |
| |
| void ParallelSweepSpaceComplete(PagedSpace* space); |
| |
| #ifdef DEBUG |
| friend class MarkObjectVisitor; |
| static void VisitObject(HeapObject* obj); |
| |
| friend class UnmarkObjectVisitor; |
| static void UnmarkObject(HeapObject* obj); |
| #endif |
| |
| Heap* heap_; |
| MarkingDeque marking_deque_; |
| CodeFlusher* code_flusher_; |
| Object* encountered_weak_collections_; |
| bool have_code_to_deoptimize_; |
| |
| List<Page*> evacuation_candidates_; |
| List<Code*> invalidated_code_; |
| |
| SmartPointer<FreeList> free_list_old_data_space_; |
| SmartPointer<FreeList> free_list_old_pointer_space_; |
| |
| friend class Heap; |
| }; |
| |
| |
| class MarkBitCellIterator BASE_EMBEDDED { |
| public: |
| explicit MarkBitCellIterator(MemoryChunk* chunk) |
| : chunk_(chunk) { |
| last_cell_index_ = Bitmap::IndexToCell( |
| Bitmap::CellAlignIndex( |
| chunk_->AddressToMarkbitIndex(chunk_->area_end()))); |
| cell_base_ = chunk_->area_start(); |
| cell_index_ = Bitmap::IndexToCell( |
| Bitmap::CellAlignIndex( |
| chunk_->AddressToMarkbitIndex(cell_base_))); |
| cells_ = chunk_->markbits()->cells(); |
| } |
| |
| inline bool Done() { return cell_index_ == last_cell_index_; } |
| |
| inline bool HasNext() { return cell_index_ < last_cell_index_ - 1; } |
| |
| inline MarkBit::CellType* CurrentCell() { |
| ASSERT(cell_index_ == Bitmap::IndexToCell(Bitmap::CellAlignIndex( |
| chunk_->AddressToMarkbitIndex(cell_base_)))); |
| return &cells_[cell_index_]; |
| } |
| |
| inline Address CurrentCellBase() { |
| ASSERT(cell_index_ == Bitmap::IndexToCell(Bitmap::CellAlignIndex( |
| chunk_->AddressToMarkbitIndex(cell_base_)))); |
| return cell_base_; |
| } |
| |
| inline void Advance() { |
| cell_index_++; |
| cell_base_ += 32 * kPointerSize; |
| } |
| |
| private: |
| MemoryChunk* chunk_; |
| MarkBit::CellType* cells_; |
| unsigned int last_cell_index_; |
| unsigned int cell_index_; |
| Address cell_base_; |
| }; |
| |
| |
| class SequentialSweepingScope BASE_EMBEDDED { |
| public: |
| explicit SequentialSweepingScope(MarkCompactCollector *collector) : |
| collector_(collector) { |
| collector_->set_sequential_sweeping(true); |
| } |
| |
| ~SequentialSweepingScope() { |
| collector_->set_sequential_sweeping(false); |
| } |
| |
| private: |
| MarkCompactCollector* collector_; |
| }; |
| |
| |
| const char* AllocationSpaceName(AllocationSpace space); |
| |
| } } // namespace v8::internal |
| |
| #endif // V8_MARK_COMPACT_H_ |