};
-// A queue of pointers and maps of to-be-promoted objects during a
-// scavenge collection.
+// A queue of objects promoted during scavenge. Each object is accompanied
+// by it's size to avoid dereferencing a map pointer for scanning.
class PromotionQueue {
public:
void Initialize(Address start_address) {
- front_ = rear_ = reinterpret_cast<HeapObject**>(start_address);
+ front_ = rear_ = reinterpret_cast<intptr_t*>(start_address);
}
bool is_empty() { return front_ <= rear_; }
- void insert(HeapObject* object, Map* map) {
- *(--rear_) = object;
- *(--rear_) = map;
+ void insert(HeapObject* target, int size) {
+ *(--rear_) = reinterpret_cast<intptr_t>(target);
+ *(--rear_) = size;
// Assert no overflow into live objects.
ASSERT(reinterpret_cast<Address>(rear_) >= Heap::new_space()->top());
}
- void remove(HeapObject** object, Map** map) {
- *object = *(--front_);
- *map = Map::cast(*(--front_));
+ void remove(HeapObject** target, int* size) {
+ *target = reinterpret_cast<HeapObject*>(*(--front_));
+ *size = *(--front_);
// Assert no underflow.
ASSERT(front_ >= rear_);
}
private:
// The front of the queue is higher in memory than the rear.
- HeapObject** front_;
- HeapObject** rear_;
+ intptr_t* front_;
+ intptr_t* rear_;
};
// queue is empty.
while (new_space_front < new_space_.top()) {
HeapObject* object = HeapObject::FromAddress(new_space_front);
- object->Iterate(scavenge_visitor);
- new_space_front += object->Size();
+ Map* map = object->map();
+ int size = object->SizeFromMap(map);
+ object->IterateBody(map->instance_type(), size, scavenge_visitor);
+ new_space_front += size;
}
// Promote and process all the to-be-promoted objects.
while (!promotion_queue.is_empty()) {
- HeapObject* source;
- Map* map;
- promotion_queue.remove(&source, &map);
- // Copy the from-space object to its new location (given by the
- // forwarding address) and fix its map.
- HeapObject* target = source->map_word().ToForwardingAddress();
- int size = source->SizeFromMap(map);
- CopyBlock(target->address(), source->address(), size);
- target->set_map(map);
-
-#if defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING)
- // Update NewSpace stats if necessary.
- RecordCopiedObject(target);
-#endif
- // Visit the newly copied object for pointers to new space.
+ HeapObject* target;
+ int size;
+ promotion_queue.remove(&target, &size);
+
+ // Promoted object might be already partially visited
+ // during dirty regions iteration. Thus we search specificly
+ // for pointers to from semispace instead of looking for pointers
+ // to new space.
ASSERT(!target->IsMap());
- IterateAndMarkPointersToNewSpace(target->address(),
- target->address() + size,
- &ScavengePointer);
+ IterateAndMarkPointersToFromSpace(target->address(),
+ target->address() + size,
+ &ScavengePointer);
}
// Take another spin if there are now unswept objects in new space
#if defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING)
-void Heap::RecordCopiedObject(HeapObject* obj) {
+static void RecordCopiedObject(HeapObject* obj) {
bool should_record = false;
#ifdef DEBUG
should_record = FLAG_heap_stats;
should_record = should_record || FLAG_log_gc;
#endif
if (should_record) {
- if (new_space_.Contains(obj)) {
- new_space_.RecordAllocation(obj);
+ if (Heap::new_space()->Contains(obj)) {
+ Heap::new_space()->RecordAllocation(obj);
} else {
- new_space_.RecordPromotion(obj);
+ Heap::new_space()->RecordPromotion(obj);
}
}
}
#endif // defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING)
-
-HeapObject* Heap::MigrateObject(HeapObject* source,
- HeapObject* target,
- int size) {
+// Helper function used by CopyObject to copy a source object to an
+// allocated target object and update the forwarding pointer in the source
+// object. Returns the target object.
+inline static HeapObject* MigrateObject(HeapObject* source,
+ HeapObject* target,
+ int size) {
// Copy the content of source to target.
- CopyBlock(target->address(), source->address(), size);
+ Heap::CopyBlock(target->address(), source->address(), size);
// Set the forwarding address.
source->set_map_word(MapWord::FromForwardingAddress(target));
}
-static inline bool IsShortcutCandidate(HeapObject* object, Map* map) {
- STATIC_ASSERT(kNotStringTag != 0 && kSymbolTag != 0);
- ASSERT(object->map() == map);
- InstanceType type = map->instance_type();
- if ((type & kShortcutTypeMask) != kShortcutTypeTag) return false;
- ASSERT(object->IsString() && !object->IsSymbol());
- return ConsString::cast(object)->unchecked_second() == Heap::empty_string();
+enum ObjectContents { DATA_OBJECT, POINTER_OBJECT };
+enum SizeRestriction { SMALL, UNKNOWN_SIZE };
+
+
+template<ObjectContents object_contents, SizeRestriction size_restriction>
+static inline void EvacuateObject(Map* map,
+ HeapObject** slot,
+ HeapObject* object,
+ int object_size) {
+ ASSERT((size_restriction != SMALL) ||
+ (object_size <= Page::kMaxHeapObjectSize));
+ ASSERT(object->Size() == object_size);
+
+ if (Heap::ShouldBePromoted(object->address(), object_size)) {
+ Object* result;
+
+ if ((size_restriction != SMALL) &&
+ (object_size > Page::kMaxHeapObjectSize)) {
+ result = Heap::lo_space()->AllocateRawFixedArray(object_size);
+ } else {
+ if (object_contents == DATA_OBJECT) {
+ result = Heap::old_data_space()->AllocateRaw(object_size);
+ } else {
+ result = Heap::old_pointer_space()->AllocateRaw(object_size);
+ }
+ }
+
+ if (!result->IsFailure()) {
+ HeapObject* target = HeapObject::cast(result);
+ *slot = MigrateObject(object, target, object_size);
+
+ if (object_contents == POINTER_OBJECT) {
+ promotion_queue.insert(target, object_size);
+ }
+
+ Heap::tracer()->increment_promoted_objects_size(object_size);
+ return;
+ }
+ }
+ Object* result = Heap::new_space()->AllocateRaw(object_size);
+ ASSERT(!result->IsFailure());
+ *slot = MigrateObject(object, HeapObject::cast(result), object_size);
+ return;
}
-void Heap::ScavengeObjectSlow(HeapObject** p, HeapObject* object) {
- ASSERT(InFromSpace(object));
- MapWord first_word = object->map_word();
- ASSERT(!first_word.IsForwardingAddress());
+template<int object_size_in_words, ObjectContents object_contents>
+static inline void EvacuateObjectOfFixedSize(Map* map,
+ HeapObject** slot,
+ HeapObject* object) {
+ const int object_size = object_size_in_words << kPointerSizeLog2;
+ EvacuateObject<object_contents, SMALL>(map, slot, object, object_size);
+}
- // Optimization: Bypass flattened ConsString objects.
- if (IsShortcutCandidate(object, first_word.ToMap())) {
- object = HeapObject::cast(ConsString::cast(object)->unchecked_first());
- *p = object;
- // After patching *p we have to repeat the checks that object is in the
- // active semispace of the young generation and not already copied.
- if (!InNewSpace(object)) return;
- first_word = object->map_word();
+
+template<ObjectContents object_contents>
+static inline void EvacuateObjectOfFixedSize(Map* map,
+ HeapObject** slot,
+ HeapObject* object) {
+ int object_size = map->instance_size();
+ EvacuateObject<object_contents, SMALL>(map, slot, object, object_size);
+}
+
+
+static inline void EvacuateFixedArray(Map* map,
+ HeapObject** slot,
+ HeapObject* object) {
+ int object_size = FixedArray::cast(object)->FixedArraySize();
+ EvacuateObject<POINTER_OBJECT, UNKNOWN_SIZE>(map, slot, object, object_size);
+}
+
+
+static inline void EvacuateByteArray(Map* map,
+ HeapObject** slot,
+ HeapObject* object) {
+ int object_size = ByteArray::cast(object)->ByteArraySize();
+ EvacuateObject<DATA_OBJECT, UNKNOWN_SIZE>(map, slot, object, object_size);
+}
+
+
+static Scavenger GetScavengerForSize(int object_size,
+ ObjectContents object_contents) {
+ ASSERT(IsAligned(object_size, kPointerSize));
+ ASSERT(object_size < Page::kMaxHeapObjectSize);
+
+ switch (object_size >> kPointerSizeLog2) {
+#define CASE(n) \
+ case n: \
+ if (object_contents == DATA_OBJECT) { \
+ return static_cast<Scavenger>( \
+ &EvacuateObjectOfFixedSize<n, DATA_OBJECT>); \
+ } else { \
+ return static_cast<Scavenger>( \
+ &EvacuateObjectOfFixedSize<n, POINTER_OBJECT>); \
+ }
+
+ CASE(1);
+ CASE(2);
+ CASE(3);
+ CASE(4);
+ CASE(5);
+ CASE(6);
+ CASE(7);
+ CASE(8);
+ CASE(9);
+ CASE(10);
+ CASE(11);
+ CASE(12);
+ CASE(13);
+ CASE(14);
+ CASE(15);
+ CASE(16);
+ default:
+ if (object_contents == DATA_OBJECT) {
+ return static_cast<Scavenger>(&EvacuateObjectOfFixedSize<DATA_OBJECT>);
+ } else {
+ return static_cast<Scavenger>(
+ &EvacuateObjectOfFixedSize<POINTER_OBJECT>);
+ }
+
+#undef CASE
+ }
+}
+
+
+static inline void EvacuateSeqAsciiString(Map* map,
+ HeapObject** slot,
+ HeapObject* object) {
+ int object_size = SeqAsciiString::cast(object)->
+ SeqAsciiStringSize(map->instance_type());
+ EvacuateObject<DATA_OBJECT, UNKNOWN_SIZE>(map, slot, object, object_size);
+}
+
+
+static inline void EvacuateSeqTwoByteString(Map* map,
+ HeapObject** slot,
+ HeapObject* object) {
+ int object_size = SeqTwoByteString::cast(object)->
+ SeqTwoByteStringSize(map->instance_type());
+ EvacuateObject<DATA_OBJECT, UNKNOWN_SIZE>(map, slot, object, object_size);
+}
+
+
+static inline bool IsShortcutCandidate(int type) {
+ return ((type & kShortcutTypeMask) == kShortcutTypeTag);
+}
+
+
+static inline void EvacuateShortcutCandidate(Map* map,
+ HeapObject** slot,
+ HeapObject* object) {
+ ASSERT(IsShortcutCandidate(map->instance_type()));
+
+ if (ConsString::cast(object)->unchecked_second() == Heap::empty_string()) {
+ HeapObject* first =
+ HeapObject::cast(ConsString::cast(object)->unchecked_first());
+
+ *slot = first;
+
+ if (!Heap::InNewSpace(first)) {
+ object->set_map_word(MapWord::FromForwardingAddress(first));
+ return;
+ }
+
+ MapWord first_word = first->map_word();
if (first_word.IsForwardingAddress()) {
- *p = first_word.ToForwardingAddress();
+ HeapObject* target = first_word.ToForwardingAddress();
+
+ *slot = target;
+ object->set_map_word(MapWord::FromForwardingAddress(target));
return;
}
+
+ first->map()->Scavenge(slot, first);
+ object->set_map_word(MapWord::FromForwardingAddress(*slot));
+ return;
}
- int object_size = object->SizeFromMap(first_word.ToMap());
- // We rely on live objects in new space to be at least two pointers,
- // so we can store the from-space address and map pointer of promoted
- // objects in the to space.
- ASSERT(object_size >= 2 * kPointerSize);
+ int object_size = ConsString::kSize;
+ EvacuateObject<POINTER_OBJECT, SMALL>(map, slot, object, object_size);
+}
+
- // If the object should be promoted, we try to copy it to old space.
- if (ShouldBePromoted(object->address(), object_size)) {
- Object* result;
- if (object_size > MaxObjectSizeInPagedSpace()) {
- result = lo_space_->AllocateRawFixedArray(object_size);
- if (!result->IsFailure()) {
- HeapObject* target = HeapObject::cast(result);
-
- if (object->IsFixedArray()) {
- // Save the from-space object pointer and its map pointer at the
- // top of the to space to be swept and copied later. Write the
- // forwarding address over the map word of the from-space
- // object.
- promotion_queue.insert(object, first_word.ToMap());
- object->set_map_word(MapWord::FromForwardingAddress(target));
-
- // Give the space allocated for the result a proper map by
- // treating it as a free list node (not linked into the free
- // list).
- FreeListNode* node = FreeListNode::FromAddress(target->address());
- node->set_size(object_size);
-
- *p = target;
+Scavenger Heap::GetScavenger(int instance_type, int instance_size) {
+ if (instance_type < FIRST_NONSTRING_TYPE) {
+ switch (instance_type & kStringRepresentationMask) {
+ case kSeqStringTag:
+ if ((instance_type & kStringEncodingMask) == kAsciiStringTag) {
+ return &EvacuateSeqAsciiString;
} else {
- // In large object space only fixed arrays might possibly contain
- // intergenerational references.
- // All other objects can be copied immediately and not revisited.
- *p = MigrateObject(object, target, object_size);
+ return &EvacuateSeqTwoByteString;
}
- tracer()->increment_promoted_objects_size(object_size);
- return;
- }
- } else {
- OldSpace* target_space = Heap::TargetSpace(object);
- ASSERT(target_space == Heap::old_pointer_space_ ||
- target_space == Heap::old_data_space_);
- result = target_space->AllocateRaw(object_size);
- if (!result->IsFailure()) {
- HeapObject* target = HeapObject::cast(result);
- if (target_space == Heap::old_pointer_space_) {
- // Save the from-space object pointer and its map pointer at the
- // top of the to space to be swept and copied later. Write the
- // forwarding address over the map word of the from-space
- // object.
- promotion_queue.insert(object, first_word.ToMap());
- object->set_map_word(MapWord::FromForwardingAddress(target));
-
- // Give the space allocated for the result a proper map by
- // treating it as a free list node (not linked into the free
- // list).
- FreeListNode* node = FreeListNode::FromAddress(target->address());
- node->set_size(object_size);
-
- *p = target;
+ case kConsStringTag:
+ if (IsShortcutCandidate(instance_type)) {
+ return &EvacuateShortcutCandidate;
} else {
- // Objects promoted to the data space can be copied immediately
- // and not revisited---we will never sweep that space for
- // pointers and the copied objects do not contain pointers to
- // new space objects.
- *p = MigrateObject(object, target, object_size);
-#ifdef DEBUG
- VerifyNonPointerSpacePointersVisitor v;
- (*p)->Iterate(&v);
-#endif
+ ASSERT(instance_size == ConsString::kSize);
+ return GetScavengerForSize(ConsString::kSize, POINTER_OBJECT);
}
- tracer()->increment_promoted_objects_size(object_size);
- return;
- }
+
+ case kExternalStringTag:
+ ASSERT(instance_size == ExternalString::kSize);
+ return GetScavengerForSize(ExternalString::kSize, DATA_OBJECT);
}
+ UNREACHABLE();
}
- // The object should remain in new space or the old space allocation failed.
- Object* result = new_space_.AllocateRaw(object_size);
- // Failed allocation at this point is utterly unexpected.
- ASSERT(!result->IsFailure());
- *p = MigrateObject(object, HeapObject::cast(result), object_size);
+
+ switch (instance_type) {
+ case BYTE_ARRAY_TYPE:
+ return reinterpret_cast<Scavenger>(&EvacuateByteArray);
+
+ case FIXED_ARRAY_TYPE:
+ return reinterpret_cast<Scavenger>(&EvacuateFixedArray);
+
+ case JS_OBJECT_TYPE:
+ case JS_CONTEXT_EXTENSION_OBJECT_TYPE:
+ case JS_VALUE_TYPE:
+ case JS_ARRAY_TYPE:
+ case JS_REGEXP_TYPE:
+ case JS_FUNCTION_TYPE:
+ case JS_GLOBAL_PROXY_TYPE:
+ case JS_GLOBAL_OBJECT_TYPE:
+ case JS_BUILTINS_OBJECT_TYPE:
+ return GetScavengerForSize(instance_size, POINTER_OBJECT);
+
+ case ODDBALL_TYPE:
+ return NULL;
+
+ case PROXY_TYPE:
+ return GetScavengerForSize(Proxy::kSize, DATA_OBJECT);
+
+ case MAP_TYPE:
+ return NULL;
+
+ case CODE_TYPE:
+ return NULL;
+
+ case JS_GLOBAL_PROPERTY_CELL_TYPE:
+ return NULL;
+
+ case HEAP_NUMBER_TYPE:
+ case FILLER_TYPE:
+ case PIXEL_ARRAY_TYPE:
+ case EXTERNAL_BYTE_ARRAY_TYPE:
+ case EXTERNAL_UNSIGNED_BYTE_ARRAY_TYPE:
+ case EXTERNAL_SHORT_ARRAY_TYPE:
+ case EXTERNAL_UNSIGNED_SHORT_ARRAY_TYPE:
+ case EXTERNAL_INT_ARRAY_TYPE:
+ case EXTERNAL_UNSIGNED_INT_ARRAY_TYPE:
+ case EXTERNAL_FLOAT_ARRAY_TYPE:
+ return GetScavengerForSize(instance_size, DATA_OBJECT);
+
+ case SHARED_FUNCTION_INFO_TYPE:
+ return GetScavengerForSize(SharedFunctionInfo::kAlignedSize,
+ POINTER_OBJECT);
+
+#define MAKE_STRUCT_CASE(NAME, Name, name) \
+ case NAME##_TYPE:
+ STRUCT_LIST(MAKE_STRUCT_CASE)
+#undef MAKE_STRUCT_CASE
+ return GetScavengerForSize(instance_size, POINTER_OBJECT);
+ default:
+ UNREACHABLE();
+ return NULL;
+ }
+}
+
+
+void Heap::ScavengeObjectSlow(HeapObject** p, HeapObject* object) {
+ ASSERT(InFromSpace(object));
+ MapWord first_word = object->map_word();
+ ASSERT(!first_word.IsForwardingAddress());
+ Map* map = first_word.ToMap();
+ map->Scavenge(p, object);
}
reinterpret_cast<Map*>(result)->set_map(raw_unchecked_meta_map());
reinterpret_cast<Map*>(result)->set_instance_type(instance_type);
reinterpret_cast<Map*>(result)->set_instance_size(instance_size);
+ reinterpret_cast<Map*>(result)->
+ set_scavenger(GetScavenger(instance_type, instance_size));
reinterpret_cast<Map*>(result)->set_inobject_properties(0);
reinterpret_cast<Map*>(result)->set_pre_allocated_property_fields(0);
reinterpret_cast<Map*>(result)->set_unused_property_fields(0);
Map* map = reinterpret_cast<Map*>(result);
map->set_map(meta_map());
map->set_instance_type(instance_type);
+ map->set_scavenger(GetScavenger(instance_type, instance_size));
map->set_prototype(null_value());
map->set_constructor(null_value());
map->set_instance_size(instance_size);
}
-void Heap::IterateAndMarkPointersToNewSpace(Address start,
- Address end,
- ObjectSlotCallback callback) {
+void Heap::IterateAndMarkPointersToFromSpace(Address start,
+ Address end,
+ ObjectSlotCallback callback) {
Address slot_address = start;
Page* page = Page::FromAddress(start);
while (slot_address < end) {
Object** slot = reinterpret_cast<Object**>(slot_address);
- if (Heap::InNewSpace(*slot)) {
+ if (Heap::InFromSpace(*slot)) {
ASSERT((*slot)->IsHeapObject());
callback(reinterpret_cast<HeapObject**>(slot));
if (Heap::InNewSpace(*slot)) {
projects / platform / upstream / v8.git / commitdiff