[wasm] reuse the first compiled module

src/snapshot/code-serializer.cc

Index: src/snapshot/code-serializer.cc
diff --git a/src/snapshot/code-serializer.cc b/src/snapshot/code-serializer.cc
index 8d2f5d933994cbab63e6451973137fe11c50496a..5011558f4623cd71097e6cd0f943af5d670fa193 100644
--- a/src/snapshot/code-serializer.cc
+++ b/src/snapshot/code-serializer.cc
@@ -98,6 +98,10 @@ void CodeSerializer::SerializeObject(HeapObject* obj, HowToCode how_to_code,
     UNREACHABLE();
   }
 
+  if (SkipOver(obj)) {

[vogelheim, 2016/09/05 08:09:52]

I would have preferred a more expressive name, or a comment on why this is here.

You're effectively implementing special case handling for one object type (weak
cells) in one CodeSerializer subclass. But since the name only explains the
mechanism (skip over this value), there is no easy way for a reader to figure
out what the intent is, and if this is a commonly used mechanism or just an edge
case.

[Yang, 2016/09/10 03:58:37]

I wonder whether it' not cleaner to implement a separate Serialize method for
the wasm code serializer that filters weak cells before calling this Serialize
method.

+    return SerializeObject(*isolate()->factory()->undefined_value(),
+                           how_to_code, where_to_point, skip);
+  }
   // Past this point we should not see any (context-specific) maps anymore.
   CHECK(!obj->IsMap());
   // There should be no references to the global object embedded.