- Implement the old sweeper.

vm/verifier.cc

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/verifier.h"
 
 #include "vm/assert.h"
 #include "vm/dart.h"
+#include "vm/freelist.h"
 #include "vm/heap.h"
 #include "vm/isolate.h"
 #include "vm/object.h"
 #include "vm/raw_object.h"
 #include "vm/stack_frame.h"
 
 namespace dart {
 
 DEFINE_FLAG(bool, verify_on_transition, false, "Verify on dart <==> VM.");
 
 
 void VerifyPointersVisitor::VisitPointers(RawObject** first, RawObject** last) {
   for (RawObject** current = first; current <= last; current++) {
     RawObject* raw_obj = *current;
     if (raw_obj->IsHeapObject()) {
+      // Skip visits of FreeListElements.
+      if (FreeListElement::IsSpecialClass(raw_obj)) {
+        // Only the class of the free list element should ever be visited.
+        ASSERT(first == last);
+        return;
+      }
       uword obj_addr = RawObject::ToAddr(raw_obj);
       if (!Isolate::Current()->heap()->Contains(obj_addr) &&
           !Dart::vm_isolate()->heap()->Contains(obj_addr)) {
         FATAL1("Invalid object pointer encountered 0x%lx\n", obj_addr);
       }
       raw_obj->Validate();
     }
   }
 }
 
 
 void VerifyPointersVisitor::VerifyPointers() {
   NoGCScope no_gc;
   VerifyPointersVisitor visitor;
   Isolate::Current()->VisitObjectPointers(&visitor,
                                           StackFrameIterator::kValidateFrames);
 }
 
 }  // namespace dart