dart::RestoreWriteBarrierInvariantVisitor Class Reference

Inheritance diagram for dart::RestoreWriteBarrierInvariantVisitor:

Public Member Functions
	RestoreWriteBarrierInvariantVisitor (IsolateGroup *group, Thread *thread, Thread::RestoreWriteBarrierInvariantOp op)
void	VisitPointers (ObjectPtr *first, ObjectPtr *last) override
Public Member Functions inherited from dart::ObjectPointerVisitor
	ObjectPointerVisitor (IsolateGroup *isolate_group)
virtual	~ObjectPointerVisitor ()
IsolateGroup *	isolate_group () const
virtual void	VisitTypedDataViewPointers (TypedDataViewPtr view, CompressedObjectPtr *first, CompressedObjectPtr *last)
void	VisitCompressedPointers (uword heap_base, CompressedObjectPtr *first, CompressedObjectPtr *last)
void	VisitPointers (ObjectPtr *p, intptr_t len)
void	VisitPointer (ObjectPtr *p)
const char *	gc_root_type () const
void	set_gc_root_type (const char *gc_root_type)
void	clear_gc_root_type ()
virtual bool	visit_weak_persistent_handles () const
virtual bool	trace_values_through_fields () const
const ClassTable *	class_table () const
virtual bool	CanVisitSuspendStatePointers (SuspendStatePtr suspend_state)

Detailed Description

Definition at line 955 of file thread.cc.

Constructor & Destructor Documentation

RestoreWriteBarrierInvariantVisitor()

dart::RestoreWriteBarrierInvariantVisitor::RestoreWriteBarrierInvariantVisitor ( IsolateGroup *  group, Thread *  thread, Thread::RestoreWriteBarrierInvariantOp  op  )

inline

Definition at line 957 of file thread.cc.

      : ObjectPointerVisitor(group),
        thread_(thread),
        current_(Thread::Current()),
        op_(op) {}

Member Function Documentation

VisitPointers()

void dart::RestoreWriteBarrierInvariantVisitor::VisitPointers ( ObjectPtr *  first, ObjectPtr *  last  )

inlineoverridevirtual

Implements dart::ObjectPointerVisitor.

Definition at line 965 of file thread.cc.

                                                                 {
    for (; first != last + 1; first++) {
      ObjectPtr obj = *first;
      // Stores into new-space objects don't need a write barrier.
      if (obj->IsImmediateObject()) continue;
 
      // To avoid adding too much work into the remembered set, skip large
      // arrays. Write barrier elimination will not remove the barrier
      // if we can trigger GC between array allocation and store.
      if (obj->GetClassId() == kArrayCid) {
        const auto length = Smi::Value(Array::RawCast(obj)->untag()->length());
        if (length > Array::kMaxLengthForWriteBarrierElimination) {
          continue;
        }
      }
 
      // Dart code won't store into VM-internal objects except Contexts and
      // UnhandledExceptions. This assumption is checked by an assertion in
      // WriteBarrierElimination::UpdateVectorForBlock.
      if (!obj->IsDartInstance() && !obj->IsContext() &&
          !obj->IsUnhandledException())
        continue;
 
      // Dart code won't store into canonical instances.
      if (obj->untag()->IsCanonical()) continue;
 
      // Objects in the VM isolate heap are immutable and won't be
      // stored into. Check this condition last because there's no bit
      // in the header for it.
      if (obj->untag()->InVMIsolateHeap()) continue;
 
      switch (op_) {
        case Thread::RestoreWriteBarrierInvariantOp::kAddToRememberedSet:
          if (obj->IsOldObject()) {
            obj->untag()->EnsureInRememberedSet(current_);
          }
          if (current_->is_marking()) {
            current_->DeferredMarkingStackAddObject(obj);
          }
          break;
        case Thread::RestoreWriteBarrierInvariantOp::kAddToDeferredMarkingStack:
          // Re-scan obj when finalizing marking.
          ASSERT(current_->is_marking());
          current_->DeferredMarkingStackAddObject(obj);
          break;
      }
    }
  }

---

The documentation for this class was generated from the following file:

• third_party/dart-lang/sdk/runtime/vm/thread.cc