Feedback directed modification of designs

Feedback-directed modification, a technique for efficiently improving the solution to a structure-sharing problem, is discussed. This technique uses an analysis of the solution to effect structural modifications to reduce resource usage. Efficiency is obtained through: the reuse of the previous solution and the addition of constraints to prevent subsequent modifications from undoing the changes. The technique allows the efficient generation of new designs through modification of old ones. However, if the initial design is very different from the desired solution, the system will take many iterations to converge and might not even be able to find the solution. In such cases, other techniques would be more suitable. Feedback-directed modification permits more direct and fine-grain control of the solution generation process so that solutions can be generated that would otherwise be unreachable with other, more coarse-grain mechanisms. A model of iterative design for VLSI structure-sharing problems is also described