- Premark vm_isolate objects to avoid having to test for them

runtime/vm/gc_marker.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/gc_marker.h"
 
 #include "vm/allocation.h"
 #include "vm/dart_api_state.h"
 #include "vm/isolate.h"
 #include "vm/pages.h"
@@ skipping 150 matching lines @@
 
     // Fast exit if the raw object is marked.
     if (raw_obj->IsMarked()) return;
 
     // Skip over new objects, but verify consistency of heap while at it.
     if (raw_obj->IsNewObject()) {
       // TODO(iposva): Add consistency check.
       return;
     }
 
-    uword raw_addr = RawObject::ToAddr(raw_obj);
-    // TODO(iposva): Premark vm_isolate objects, to avoid this extra check here.
-    if (vm_heap_->Contains(raw_addr)) {
-      return;
-    }
     // TODO(iposva): merge old and code spaces.
-    ASSERT(page_space_->Contains(raw_addr));
+    ASSERT(page_space_->Contains(RawObject::ToAddr(raw_obj)));
     MarkAndPush(raw_obj);
   }
 
   Heap* heap_;
   Heap* vm_heap_;
   PageSpace* page_space_;
   MarkingStack* marking_stack_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(MarkingVisitor);
 };
 
 
 bool IsUnreachable(const RawObject* raw_obj) {
   if (!raw_obj->IsHeapObject()) {
     return false;
   }
+  if (raw_obj == Object::null()) {
+    return true;
+  }
   if (!raw_obj->IsOldObject()) {
     return false;
   }
   return !raw_obj->IsMarked();
 }
 
 
 class MarkingWeakVisitor : public HandleVisitor {
  public:
   MarkingWeakVisitor() {
@@ skipping 117 matching lines @@
   MarkingVisitor mark(isolate, heap_, page_space, &marking_stack);
   IterateRoots(isolate, &mark, !invoke_api_callbacks);
   DrainMarkingStack(isolate, &mark);
   IterateWeakReferences(isolate, &mark);
   MarkingWeakVisitor mark_weak;
   IterateWeakRoots(isolate, &mark_weak, invoke_api_callbacks);
   Epilogue(isolate, invoke_api_callbacks);
 }
 
 }  // namespace dart