Enable export lookup by two threads (mutator and background compiler) by carying a copy of exports_…

runtime/vm/object.h

 // 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.
 
 #ifndef VM_OBJECT_H_
 #define VM_OBJECT_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/utils.h"
@@ skipping 3536 matching lines @@
   }
   void set_toplevel_class(const Class& value) const;
 
   RawGrowableObjectArray* patch_classes() const {
     return raw_ptr()->patch_classes_;
   }
 
   // Library imports.
   RawArray* imports() const { return raw_ptr()->imports_; }
   RawArray* exports() const { return raw_ptr()->exports_; }
+  RawArray* exports2() const { return raw_ptr()->exports_; }

[hausner, 2016/03/29 19:15:23]

Siva found this bug:

you should return exports2_ here.

   void AddImport(const Namespace& ns) const;
   intptr_t num_imports() const { return raw_ptr()->num_imports_; }
   RawNamespace* ImportAt(intptr_t index) const;
   RawLibrary* ImportLibraryAt(intptr_t index) const;
   bool ImportsCorelib() const;
 
   void DropDependencies() const;
 
   // Resolving native methods for script loaded in the library.
   Dart_NativeEntryResolver native_entry_resolver() const {
@@ skipping 4853 matching lines @@
 
 
 RawObject* MegamorphicCache::GetTargetFunction(const Array& array,
                                                intptr_t index) {
   return array.At((index * kEntryLength) + kTargetFunctionIndex);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_