A new robust and efficient implementation of controlled types in the GNAT compiler

Abstract

This paper discusses a new implementation model for supporting Ada controlled types in the GNAT compiler. After reviewing the semantics of controlled types, we revisit the original implementation from 1995 and discuss its performance issues. We then describe a new model which addresses all existing limitations and is shown to be superior to its predecessor. Finally, we conclude the paper with the status of the new implementation and possible future enhancements.