Incremental changes from background compilation work

runtime/vm/flow_graph_optimizer.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/flow_graph_optimizer.h"
 
 #include "vm/bit_vector.h"
 #include "vm/cha.h"
 #include "vm/compiler.h"
 #include "vm/cpu.h"
@@ skipping 258 matching lines @@
       const intptr_t cid = Class::Handle(Z, target_function.Owner()).id();
       const ICData& ic_data = ICData::ZoneHandle(Z,
           ICData::NewFrom(*call->ic_data(), 1));
       ic_data.AddReceiverCheck(cid, target_function);
       call->set_ic_data(&ic_data);
       return true;
     }
   }
 
   // Check if getter or setter in function's class and class is currently leaf.
-  if (FLAG_guess_icdata_cid &&
+  // Do not run the optimization below if in background compilation since
+  // resolution of getter functions may create new signature classes.
+  // TODO(regis): Remove test for background compilation once signature classes
+  // are not generated any longer.
+  if (thread()->IsMutatorThread() &&
+      FLAG_guess_icdata_cid &&
       ((call->token_kind() == Token::kGET) ||
           (call->token_kind() == Token::kSET))) {
     const Class& owner_class = Class::Handle(Z, function().Owner());
     if (!owner_class.is_abstract() &&
         !CHA::HasSubclasses(owner_class) &&
         !CHA::IsImplemented(owner_class)) {
       const Array& args_desc_array = Array::Handle(Z,
           ArgumentsDescriptor::New(call->ArgumentCount(),
                                    call->argument_names()));
       ArgumentsDescriptor args_desc(args_desc_array);
@@ skipping 8555 matching lines @@
 
   // Insert materializations at environment uses.
   for (intptr_t i = 0; i < exits_collector_.exits().length(); i++) {
     CreateMaterializationAt(
         exits_collector_.exits()[i], alloc, *slots);
   }
 }
 
 
 }  // namespace dart