Assertion-based slicing and slice graphs

• Author(s): Barros, José Bernardo ; Cruz, Daniela da ; Henriques, Pedro Rangel ; Pinto, Jorge Sousa
• Date: 2010
• Persistent ID: http://hdl.handle.net/1822/12731
• Origin: RepositóriUM - Universidade do Minho
• Subject(s): Slicing; Program verification; Preconditions; Postconditions; Verification conditions; Labeled control-flow graph
• Document Type: Article
• Language: English

Description

© 2010 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. This paper revisits the idea of slicing programs based on their axiomatic semantics, rather than using criteria based on control/data dependencies. We show how the forward propagation of preconditions and the backward propagation of post conditions can be combined in a new slicing algorithm that is more precise than the existing specification-based algorithms. The algorithm is based on (i) a precise test for removable statements, and (ii) the construction of a slice graph, a program control flow graph extended with semantic labels. It improves on previous approaches in two aspects: it does not fail to identify removable commands; and it produces the smallest possible slice that can be obtained (in a sense that will be made precise). The paper also reviews in detail, through examples, the ideas behind the use of preconditions and post conditions for slicing programs.