Adds a special case for sending an int over a port with the native API.

runtime/vm/isolate.cc

 // Copyright (c) 2013, 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/isolate.h"
 
 #include "include/dart_api.h"
 #include "include/dart_native_api.h"
 #include "platform/assert.h"
 #include "platform/text_buffer.h"
@@ skipping 450 matching lines @@
       if (message->RedirectToDeliveryFailurePort()) {
         PortMap::PostMessage(message);
       } else {
         delete message;
       }
       return kOK;
     }
   }
 
   // Parse the message.
-  MessageSnapshotReader reader(message->data(), message->len(), thread);
-  const Object& msg_obj = Object::Handle(zone, reader.ReadObject());
-  if (msg_obj.IsError()) {
-    // An error occurred while reading the message.
-    delete message;
-    return ProcessUnhandledException(Error::Cast(msg_obj));
+  Instance& msg = Instance::Handle(zone);
+  if (message->len() > 0) {

[Ivan Posva, 2015/12/09 22:45:28]

How about turning it around:
if (message->IsRaw()) {
  msg_obj = message->raw_obj();
  ASSERT(msg_obj.IsSmi() || msg_obj.InVMHeap());
} else {
  // Deserialize the message object.
  ...
}

// Error checking should be done in both cases too.

[zra, 2015/12/10 00:07:29]

Done.

+    MessageSnapshotReader reader(message->data(), message->len(), thread);
+    const Object& msg_obj = Object::Handle(zone, reader.ReadObject());
+    if (msg_obj.IsError()) {
+      // An error occurred while reading the message.
+      delete message;
+      return ProcessUnhandledException(Error::Cast(msg_obj));
+    }
+    if (!msg_obj.IsNull() && !msg_obj.IsInstance()) {
+      // TODO(turnidge): We need to decide what an isolate does with
+      // malformed messages.  If they (eventually) come from a remote
+      // machine, then it might make sense to drop the message entirely.
+      // In the case that the message originated locally, which is
+      // always true for now, then this should never occur.
+      UNREACHABLE();
+    }
+    msg ^= msg_obj.raw();  // Can't use Instance::Cast because may be null.
+  } else {
+    ASSERT(message->len() == 0);
+    msg ^= message->raw_obj();
+    ASSERT(msg.IsSmi() || msg.InVMHeap());
   }
-  if (!msg_obj.IsNull() && !msg_obj.IsInstance()) {
-    // TODO(turnidge): We need to decide what an isolate does with
-    // malformed messages.  If they (eventually) come from a remote
-    // machine, then it might make sense to drop the message entirely.
-    // In the case that the message originated locally, which is
-    // always true for now, then this should never occur.
-    UNREACHABLE();
-  }
-
-  Instance& msg = Instance::Handle(zone);
-  msg ^= msg_obj.raw();  // Can't use Instance::Cast because may be null.
 
   MessageStatus status = kOK;
   if (message->IsOOB()) {
     // OOB messages are expected to be fixed length arrays where the first
     // element is a Smi describing the OOB destination. Messages that do not
     // confirm to this layout are silently ignored.
     if (msg.IsArray()) {
       const Array& oob_msg = Array::Cast(msg);
       if (oob_msg.Length() > 0) {
         const Object& oob_tag = Object::Handle(zone, oob_msg.At(0));
@@ skipping 1995 matching lines @@
 }
 
 
 RawInstance* IsolateSpawnState::BuildMessage(Thread* thread) {
   return DeserializeObject(thread,
                            serialized_message_, serialized_message_len_);
 }
 
 
 }  // namespace dart