Dependence Analysis for Recursive Data

This paper describes a general and powerful method for dependence analysis in the presence of recursive data constructions. The particular analysis presented is for identifying partially dead recursive data, but the general framework for representing and manipulating recursive substruc-tures applies to all dependence analyses. The method uses projections based on general regular tree grammars extended with notions of live and dead, and deenes the analysis as mutually recursive grammar transformers. To guarantee that the analysis terminates, we use carefully designed approximations. We describe how to approximate argument projections with grammars that can be computed without iterating and how to approximate resulting projections with a widening operation. We design an approximation operation that combines two grammars to give the most precise deterministic result possible. All grammar operations used in the analysis have eecient algorithms. The overall analysis yields signiicantly more precise results than other known methods.