Deterministic Parallel Fixpoint Computation. Abstract interpretation is a general framework for expressing static program analyses. It reduces the problem of extracting properties of a program to computing a fixpoint of a system of equations. The de facto approach for computing this fixpoint uses a sequential algorithm based on weak topological order (WTO). This paper presents a deterministic parallel algorithm for fixpoint computation by introducing the notion of weak partial order (WPO). We present an algorithm for constructing a WPO in almostlinear time. Finally, we describe our deterministic parallel abstract interpreter PIKOS. We evaluate the performance of PIKOS on a suite of 207 C programs. We observe a maximum speedup of 9.38x when using 16 cores compared to the existing WTObased sequential abstract interpreter.

On the fly MHP Analysis MayHappeninParallel (MHP) analysis forms the basis for many problems of program analysis and program understanding. MHP analysis can also be used by integrateddevelopmentenvironments (IDEs) to help programmers to refactor parallelprograms, identify racy programs, understand which parts of the program run in parallel, and so on. Since the code keeps changing in the IDE, recomputing the MHP information after every change can be an expensive affair. In this manuscript, we propose a novel scheme to perform onthefly MHP analysis of programs written in APGAS based task parallel languages like X10 to keep the MHP information up to date, in an IDE environment.NThe key insight of our proposed approach to maintain the MHP information up to date is that we need not rebuild (from scratch) every data structure related to MHP information, after each modification (addition or deletion of statements) in the source code. The idea is to reuse the old MHP information as much as possible and recompute the MHP information (of a small set of specific statements) which depends on the statement added or removed. We introduce two new algorithms that deal with addition and removal of parallel constructs like finish, async, atomic, and sequential constructs like loop, if, ifelse and other sequential statements, on the fly. We have implemented these algorithms as part of a plugin for X10DT, a popular IDE (Integrated Development Environment) to develop X10 programs. Our evaluation shows that the proposed onthefly techniques run much faster than the repeated invocations of the fastest known MHP analysis for X10 programs.