Add flag for printing the time it took to deserialize the snapshot.

src/snapshot-common.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 84 matching lines @@
     bool success;
     {
       SnapshotByteSource source(str, len);
       Deserializer deserializer(&source);
       ReserveSpaceForSnapshot(&deserializer, snapshot_file);
       success = V8::Initialize(&deserializer);
     }
     DeleteArray(str);
     return success;
   } else if (size_ > 0) {
+    ElapsedTimer timer;
+    if (FLAG_profile_deserialization) {
+      timer.Start();
+    }
     SnapshotByteSource source(raw_data_, raw_size_);
     Deserializer deserializer(&source);
     ReserveSpaceForLinkedInSnapshot(&deserializer);
-    return V8::Initialize(&deserializer);
+    bool success = V8::Initialize(&deserializer);
+    if (FLAG_profile_deserialization) {
+      double ms = timer.Elapsed().InMillisecondsF();
+      PrintF("[Snapshot loading and deserialization took %0.3f ms]\n", ms);
+    }
+    return success;
   }
   return false;
 }
 
 
 bool Snapshot::HaveASnapshotToStartFrom() {
   return size_ != 0;
 }
 
 
@@ skipping 12 matching lines @@
   deserializer.set_reservation(MAP_SPACE, context_map_space_used_);
   deserializer.set_reservation(CELL_SPACE, context_cell_space_used_);
   deserializer.set_reservation(PROPERTY_CELL_SPACE,
                                context_property_cell_space_used_);
   deserializer.DeserializePartial(isolate, &root);
   CHECK(root->IsContext());
   return Handle<Context>(Context::cast(root));
 }
 
 } }  // namespace v8::internal