--- a/src/share/vm/gc/shenandoah/shenandoahMarkCompact.cpp	Wed Sep 16 17:21:00 2015 +0200
+++ b/src/share/vm/gc/shenandoah/shenandoahMarkCompact.cpp	Wed Sep 16 17:21:25 2015 +0200
@@ -139,25 +139,56 @@
 
   _heap->shenandoahPolicy()->record_phase_end(ShenandoahCollectorPolicy::full_gc);
 }
- 
+
+class UpdateRefsClosure: public ExtendedOopClosure {
+public:
+  virtual void do_oop(oop* p) {
+    oop obj = oopDesc::load_heap_oop(p);
+    if (! oopDesc::is_null(obj)) {
+      ShenandoahBarrierSet::resolve_and_update_oop_static(p, obj);
+    }
+  }
+  virtual void do_oop(narrowOop* p) {
+    Unimplemented();
+  }
+};
+
 void ShenandoahMarkCompact::phase1_mark_heap() {
   ShenandoahHeap* _heap = ShenandoahHeap::heap();
   ReferenceProcessor* rp = _heap->ref_processor();
 
   MarkSweep::_ref_processor = rp;
  
-  // Need cleared claim bits for the roots processing
-  ClassLoaderDataGraph::clear_claimed_marks();
- 
-  MarkingCodeBlobClosure follow_code_closure(&MarkSweep::follow_root_closure, !CodeBlobToOopClosure::FixRelocations);
+  // First, update _all_ references in GC roots to point to to-space.
   {
+    // Need cleared claim bits for the roots processing
+    /*
+    ClassLoaderDataGraph::clear_claimed_marks();
+    UpdateRefsClosure uprefs;
+    CLDToOopClosure cld_uprefs(&uprefs);
+    CodeBlobToOopClosure code_uprefs(&uprefs, CodeBlobToOopClosure::FixRelocations);
+    ShenandoahRootProcessor rp(_heap, 1);
+    rp.process_all_roots(&uprefs,
+			 &cld_uprefs,
+			 &code_uprefs);
+    */
+  }
+
+  {
+    MarkingCodeBlobClosure follow_code_closure(&MarkSweep::follow_root_closure, CodeBlobToOopClosure::FixRelocations);
+    // Need cleared claim bits for the roots processing
+    ClassLoaderDataGraph::clear_claimed_marks();
     ShenandoahRootProcessor rp(_heap, 1);
     rp.process_strong_roots(&MarkSweep::follow_root_closure,
 			    &MarkSweep::follow_cld_closure,
 			    &follow_code_closure);
+
+    // Also update (without marking) weak CLD refs, in case they're reachable.
+    UpdateRefsClosure uprefs;
+    CLDToOopClosure cld_uprefs(&uprefs);
+    ClassLoaderDataGraph::roots_cld_do(NULL, &cld_uprefs);
   }
  
- 
   _heap->shenandoahPolicy()->record_phase_start(ShenandoahCollectorPolicy::weakrefs);
   bool clear_soft_refs = false; //fixme 
   rp->setup_policy(clear_soft_refs);