Last snapshot bits to get working precompiled hello_world on x64.

runtime/vm/object.cc

Index: runtime/vm/object.cc
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index 123034e7d549837a741459b4a00fa14b5b0e216f..85fd5b824aaca717306b2b07a95f6c99162c3528 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -832,11 +832,15 @@ class PremarkingVisitor : public ObjectVisitor {
   explicit PremarkingVisitor(Isolate* isolate) : ObjectVisitor(isolate) {}
 
   void VisitObject(RawObject* obj) {
-    ASSERT(!obj->IsMarked());
     // Free list elements should never be marked.
     if (!obj->IsFreeListElement()) {
       ASSERT(obj->IsVMHeapObject());
-      obj->SetMarkBitUnsynchronized();
+      if (obj->IsMarked()) {
+        // Precompiled instructions are loaded pre-marked.
+        ASSERT(obj->IsInstructions());
+      } else {
+        obj->SetMarkBitUnsynchronized();
+      }

[siva, 2015/09/14 21:29:34]

Shouldn't this be:

if (obj->IsMarked()) {
  // Precompiled instructions are loaded pre_marked.
  ASSERT(Dart::IsRunningPrecompiledCode());
  ASSERT(obj.IsInstructions());
} else {
  obj->SetMarkBitUnsyncronized();

}

[rmacnak, 2015/09/15 20:07:45]

Done.

     }
   }
 };