Beyond reachability: Shape abstraction in the presence of pointer arithmetic

Abstract. Previous shape analysis algorithms use a memory model where the heap is composed of discrete nodes that can be accessed only via access paths built from variables and field names, an assumption that is violated by pointer arithmetic. In this paper we show how this assumption can be removed, and pointer arithmetic embraced, by using an analysis based on separation logic. We describe an abstract domain whose elements are certain separation logic formulae, and an abstraction mechanism that automatically transits between a low-level RAM view of memory and a higher, fictional, view that abstracts from the representation of nodes and multiword linked-lists as certain configurations of the RAM. A widening operator is used to accelerate the analysis. We report experimental results obtained from running our analysis on a number of classic algorithms for dynamic memory management.

Making Matters Worse

Catastrophic disasters require additional leadership capabilities because extreme events overwhelm local capabilities and damage emergency response systems themselves. Therefore, leaders at all levels must adapt and rebuild the response system, even while they are addressing the pressing needs of the disaster itself. Leaders can minimize or maximize the effects of the trigger event(s) by their actions and competence in dealing with this especially difficult set of overlapping and, frequently, even inconsistent tasks. This case studies the effects of the Katrina-Rita hurricanes on New Orleans and systematically examines how poor leadership-lacking a series of critical competencies required in extreme conditions-can maximize catastrophic events. © 2008 Sage Publications