Generating recomputations in reverse mode
by
Thomas Kaminski
Max-Planck-Institut fuer Meteorologie
Coauthors: Ralf Giering (Jet-Propulsion-Laboratory)

The ability to generate recomputations of intermediate results is essential for generating efficient adjoint code. The Tangent linear and Adjoint Model Compiler (TAMC) is the only AD tool that generates recomputations on any level inside a routine. Using an algorithm that is based on demand driven program slicing, TAMC aims at generating only the necessary recomputations. We discuss how this algorithm handles blocks of statements and loops as well as the necessary data flow and data dependence analyses. Currently any array is treated as a scalar. A more sophisticated algorithm, however, would need to take array sections into account. We describe how such extension can be implemented based on a library of operations on array sections.

http://puddle.mit.edu/~ralf/tamc

Date received: December 30, 1999