Object ID Ring with tests

runtime/vm/scavenger.cc

Index: runtime/vm/scavenger.cc
diff --git a/runtime/vm/scavenger.cc b/runtime/vm/scavenger.cc
index 81aae4d8736f84445e522a85eb336dc2935d9f92..460aabe35d8c59766e283e2fa308d9d372f8d795 100644
--- a/runtime/vm/scavenger.cc
+++ b/runtime/vm/scavenger.cc
@@ -403,6 +403,17 @@ void Scavenger::IterateStoreBuffers(Isolate* isolate,
 }
 
 
+void Scavenger::IterateObjectIdTable(Isolate* isolate,
+                                     ScavengerVisitor* visitor) {
+  RawObject** table = heap_->get_object_id_ring_table();
+  const intptr_t table_size = heap_->get_object_id_ring_table_size();
+  if ((table == NULL) || (table_size <= 0)) {
+    return;
+  }
+  visitor->VisitPointers(&table[0], &table[table_size]);
+}
+
+
 void Scavenger::IterateRoots(Isolate* isolate,
                              ScavengerVisitor* visitor,
                              bool visit_prologue_weak_persistent_handles) {
@@ -412,6 +423,7 @@ void Scavenger::IterateRoots(Isolate* isolate,
                                StackFrameIterator::kDontValidateFrames);
   int64_t middle = OS::GetCurrentTimeMicros();
   IterateStoreBuffers(isolate, visitor);
+  IterateObjectIdTable(isolate, visitor);
   int64_t end = OS::GetCurrentTimeMicros();
   heap_->RecordTime(kVisitIsolateRoots, middle - start);
   heap_->RecordTime(kIterateStoreBuffers, end - middle);
@@ -574,6 +586,31 @@ void Scavenger::ProcessPeerReferents() {
 }
 
 
+void Scavenger::ProcessObjectIdTable() {
+  RawObject** table = heap_->get_object_id_ring_table();
+  const intptr_t table_size = heap_->get_object_id_ring_table_size();
+  if ((table == NULL) || (table_size <= 0)) {
+    return;
+  }
+  for (intptr_t i = 0; i < table_size; i++) {
+    RawObject* raw_obj = table[i];
+    ASSERT(raw_obj->IsHeapObject());
+    if (raw_obj->IsOldObject()) {
+      // SKip old objects.
+      continue;
+    }
+    uword raw_addr = RawObject::ToAddr(raw_obj);
+    uword header = *reinterpret_cast<uword*>(raw_addr);
+    if (IsForwarding(header)) {
+      // The object has survived. Update its address in the table.
+      uword new_addr = ForwardedAddr(header);
+      raw_obj = RawObject::FromAddr(new_addr);
+      table[i] = raw_obj;
+    }
+  }
+}
+
+
 void Scavenger::VisitObjectPointers(ObjectPointerVisitor* visitor) const {
   uword cur = FirstObjectStart();
   while (cur < top_) {
@@ -626,6 +663,7 @@ void Scavenger::Scavenge(bool invoke_api_callbacks) {
   IterateWeakRoots(isolate, &weak_visitor, invoke_api_callbacks);
   visitor.Finalize();
   ProcessPeerReferents();
+  ProcessObjectIdTable();
   int64_t end = OS::GetCurrentTimeMicros();
   heap_->RecordTime(kProcessToSpace, middle - start);
   heap_->RecordTime(kIterateWeaks, end - middle);