Update native gc-roots separately in compaction pause

The concurrent compaction algorithm requires all GC roots to be updated
to post-compact addresses before resuming mutators for concurrent
compaction. Therefore, unlike CC, we cannot update native roots in
classes/dex-caches/class-loaders while visiting references
(VisitReferences) on heap objects.

This CL separates the two and updates all the gc-roots in the compaction
pause.

Bug: 160737021
Test: art/test/testrunner/testrunner.py
Change-Id: I8a57472ba49b9dc30bc0f41a7db3f5efa7eafd9a

1 files changed, 37 insertions, 0 deletions

diff --git a/runtime/class_table-inl.h b/runtime/class_table-inl.h
index 071376cd77..67eeb553a4 100644
--- a/runtime/class_table-inl.h
+++ b/runtime/class_table-inl.h
@@ -104,6 +104,43 @@ void ClassTable::VisitRoots(const Visitor& visitor) {
   }
 }
 
+template <typename Visitor>
+class ClassTable::TableSlot::ClassAndRootVisitor {
+ public:
+  explicit ClassAndRootVisitor(Visitor& visitor) : visitor_(visitor) {}
+
+  void VisitRoot(mirror::CompressedReference<mirror::Object>* klass) const
+      REQUIRES_SHARED(Locks::mutator_lock_) {
+    DCHECK(!klass->IsNull());
+    // Visit roots in the klass object
+    visitor_(klass->AsMirrorPtr());
+    // Visit the GC-root holding klass' reference
+    visitor_.VisitRoot(klass);
+  }
+
+ private:
+  Visitor& visitor_;
+};
+
+template <typename Visitor>
+void ClassTable::VisitClassesAndRoots(Visitor& visitor) {
+  TableSlot::ClassAndRootVisitor class_visitor(visitor);
+  ReaderMutexLock mu(Thread::Current(), lock_);
+  for (ClassSet& class_set : classes_) {
+    for (TableSlot& table_slot : class_set) {
+      table_slot.VisitRoot(class_visitor);
+    }
+  }
+  for (GcRoot<mirror::Object>& root : strong_roots_) {
+    visitor.VisitRoot(root.AddressWithoutBarrier());
+  }
+  for (const OatFile* oat_file : oat_files_) {
+    for (GcRoot<mirror::Object>& root : oat_file->GetBssGcRoots()) {
+      visitor.VisitRootIfNonNull(root.AddressWithoutBarrier());
+    }
+  }
+}
+
 template <ReadBarrierOption kReadBarrierOption, typename Visitor>
 bool ClassTable::Visit(Visitor& visitor) {
   ReaderMutexLock mu(Thread::Current(), lock_);