This adds a mechanism to invalidate code that was generated in the background. The invalidation can…

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 2344 matching lines @@
 
   intptr_t NumImplicitParameters() const;
 
   static intptr_t usage_counter_offset() {
     return OFFSET_OF(RawFunction, usage_counter_);
   }
   intptr_t usage_counter() const {
     return raw_ptr()->usage_counter_;
   }
   void set_usage_counter(intptr_t value) const {
+    // TODO(Srdjan): Assert that this is thread-safe, i.e., only
+    // set from mutator-thread or while at a safepoint (e.g., during marking).
     StoreNonPointer(&raw_ptr()->usage_counter_, value);
   }
 
   int16_t deoptimization_counter() const {
     return raw_ptr()->deoptimization_counter_;
   }
   void set_deoptimization_counter(int16_t value) const {
     StoreNonPointer(&raw_ptr()->deoptimization_counter_, value);
   }
 
@@ skipping 5850 matching lines @@
 
 
 RawObject* MegamorphicCache::GetTargetFunction(const Array& array,
                                                intptr_t index) {
   return array.At((index * kEntryLength) + kTargetFunctionIndex);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_