Track external allocated memory for weak persistent handles.

runtime/vm/scavenger.cc

Index: runtime/vm/scavenger.cc
===================================================================
--- runtime/vm/scavenger.cc	(revision 33235)
+++ runtime/vm/scavenger.cc	(working copy)
@@ -271,20 +271,24 @@
 
 class ScavengerWeakVisitor : public HandleVisitor {
  public:
-  explicit ScavengerWeakVisitor(Scavenger* scavenger) : scavenger_(scavenger) {
-  }
+  explicit ScavengerWeakVisitor(Scavenger* scavenger)
+      : scavenger_(scavenger), heap_(scavenger->heap_) {}
 
   void VisitHandle(uword addr) {
     FinalizablePersistentHandle* handle =
-        reinterpret_cast<FinalizablePersistentHandle*>(addr);
+      reinterpret_cast<FinalizablePersistentHandle*>(addr);
     RawObject** p = handle->raw_addr();
+    RawObject* before = *p;
     if (scavenger_->IsUnreachable(p)) {
-      FinalizablePersistentHandle::Finalize(handle);
+      handle->UpdateUnreachable(heap_);
+    } else {
+      handle->UpdateRelocated(before, heap_);
     }
   }
 
  private:
   Scavenger* scavenger_;
+  Heap* heap_;
 
   DISALLOW_COPY_AND_ASSIGN(ScavengerWeakVisitor);
 };
@@ -320,7 +324,8 @@
       object_alignment_(object_alignment),
       scavenging_(false),
       gc_time_micros_(0),
-      collections_(0) {
+      collections_(0),
+      external_size_(0) {
   // Verify assumptions about the first word in objects which the scavenger is
   // going to use for forwarding pointers.
   ASSERT(Object::tags_offset() == 0);
@@ -682,6 +687,11 @@
     OS::PrintErr(" done.\n");
   }
 
+  // During from/to flip and promoted stack use, move external allocation
+  // out of tospace temporarily.
+  intptr_t saved_external = external_size_;
+  FreeExternal(saved_external);
+
   // Setup the visitor and run a scavenge.
   ScavengerVisitor visitor(isolate, this);
   Prologue(isolate, invoke_api_callbacks);
@@ -690,6 +700,9 @@
   ProcessToSpace(&visitor);
   int64_t middle = OS::GetCurrentTimeMicros();
   IterateWeakReferences(isolate, &visitor);
+  // Done with promoted stack; restore external allocation.
+  ASSERT(!PromotedStackHasMore());
+  AllocateExternal(saved_external);
   ScavengerWeakVisitor weak_visitor(this);
   IterateWeakRoots(isolate, &weak_visitor, invoke_api_callbacks);
   visitor.Finalize();
@@ -730,4 +743,19 @@
 }
 
 
+void Scavenger::AllocateExternal(intptr_t size) {
+  ASSERT(size >= 0);
+  external_size_ += size;
+  intptr_t remaining = end_ - top_;
+  end_ -= Utils::Minimum(remaining, size);
+}
+
+
+void Scavenger::FreeExternal(intptr_t size) {
+  ASSERT(size >= 0);
+  external_size_ -= size;
+  ASSERT(external_size_ >= 0);
+  end_ = Utils::Minimum(to_->end(), end_ + size);
+}
+
 }  // namespace dart