- Always write a Null Object for Code objects

vm/raw_object_snapshot.cc

 // Copyright (c) 2012, 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/bigint_operations.h"
 #include "vm/object.h"
 #include "vm/object_store.h"
 #include "vm/snapshot.h"
 #include "vm/visitor.h"
 
@@ skipping 848 matching lines @@
                         intptr_t tags,
                         Snapshot::Kind kind) {
   UNREACHABLE();
   return Code::null();
 }
 
 
 void RawCode::WriteTo(SnapshotWriter* writer,
                       intptr_t object_id,
                       Snapshot::Kind kind) {
-  // Currently we do not serialize any code and hence we write
-  // out a null object for it.
-  ASSERT(writer != NULL);
-  ASSERT(kind != Snapshot::kMessage);
-
-  writer->WriteIndexedObject(Object::kNullObject);
+  // We have already checked for this and written a NULL object, hence we
+  // should not reach here.
+  UNREACHABLE();
 }
 
 
 RawInstructions* Instructions::ReadFrom(SnapshotReader* reader,
                                         intptr_t object_id,
                                         intptr_t tags,
                                         Snapshot::Kind kind) {
   UNREACHABLE();
   return Instructions::null();
 }
@@ skipping 1017 matching lines @@
   writer->WriteIntptrValue(ptr()->flags_);
 
   // Do not write out the data part which is native.
 }
 
 
 RawICData* ICData::ReadFrom(SnapshotReader* reader,
                             intptr_t object_id,
                             intptr_t tags,
                             Snapshot::Kind kind) {
-  UNIMPLEMENTED();
+  UNREACHABLE();
   return NULL;
 }
 
 
 void RawICData::WriteTo(SnapshotWriter* writer,
                         intptr_t object_id,
                         Snapshot::Kind kind) {
-  UNIMPLEMENTED();
+  UNREACHABLE();
 }
 
 
 }  // namespace dart