HPAC: An Approximate Programming Model with Utilities

This is a baseline implementation of the approximate programming model called HPAC. HPAC extends Clang/LLVM. HPAC supports two approximation techniques perforation and memoization. Perforation supports subclasses of the technique that define the pattern of the perforated loops. Memoization supports two sub-classes of approximate memoization, namely input (iACT), and output (TAF) memorization. Each sub-class can be further parameterized to fine-tune the behavior of the technique. Finally, the release contains a set of scripts that facilitate exploration of the approximation design space and identify opportunities for approximations.