The Impact of Program Transformations on Static Program Analysis

Abstract

Semantics-preserving program transformations, such as those carried out by an optimizing compiler, can affect the results of static program analyses. In the best cases, a transformation increases precision or allows a simpler analysis to replace a complex one. In other cases, transformations have the opposite effect, reducing precision. This work constructs a theoretical framework to analyze this intriguing phenomenon. The framework provides a simple, uniform explanation for precision changes, linking them to bisimulation relations that justify the correctness of a transformation. It offers a mechanism for recovering lost precision through the systematic construction of a new, bisimulating analysis. Furthermore, it is shown that program analyses defined over a class of composite domains can be factored into a program transformation followed by simpler, equally precise analyses of the target program.