Efficient implementation of Smalltalk activation records in language implementation frameworks

Language implementation frameworks such as RPython or Truffle help to build runtimes for dynamic languages. For this, they make certain design decisions and trade-offs upfront to make common language concepts easy to implement. Because of this, however, some language-specific concepts may be rather tedious to support, especially the modification of activation records. For example, Smalltalk provides reification of activations through context objects. Since they are used to implement other mechanisms such as exception handling on the language level, contexts need to be entirely supported by the underlying runtime. We present an approach for efficiently implementing Smalltalk context objects in frameworks that do not support unrestricted modification of activation records.