A Dataflow Analysis for Comparing and Reordering Predicate Arguments

TL;DR

This paper introduces a data-flow analysis for logic programming that computes detailed argument profiles, aiding program understanding, argument comparison, and predicate normalization by capturing argument functionality.

Contribution

It presents a novel analysis method for argument profiling that surpasses traditional types and modes, enabling finer argument comparison and predicate reordering.

Findings

Provides a way to understand argument roles in predicates

Enables argument comparison for predicate analysis

Supports predicate normalization through argument reordering

Abstract

In this work, which is done in the context of a (moded) logic programming language, we devise a data-flow analysis dedicated to computing what we call argument profiles. Such a profile essentially describes, for each argument of a predicate, its functionality, i.e. the operations in which the argument can be involved during an evaluation of the predicate, as well as how the argument contributes to the consumption and/or construction of data values. While the computed argument profiles can be useful for applications in the context of program understanding (as each profile essentially provides a way to better understand the role of the argument), they more importantly provide a way to discern between arguments in a manner that is more fine-grained than what can be done with other abstract characterizations such as types and modes. This is important for applications where one needs to identify correspondences between the arguments of two or more different predicates that need to be compared, such as during clone detection. Moreover, since a total order can be defined on the abstract domain of profiles, our analysis can be used for rearranging predicate arguments and order them according to their functionality, constituting as such an essential ingredient for predicate normalization techniques.