We present a new classification system for aspect-oriented programs. This system characterizes the interactions between aspects and methods and identifies classes of interactions that enable modular reasoning about the crosscut program. We argue that this system can help developers structure their understanding of aspect-oriented programs and promotes their ability to reason productively about the consequences of crosscutting a program with a given aspect.

The Real Time Specification for Java (RTSJ) allows a program to create real-time threads with hard real-time constraints. Real-time threads use region-based memory management to avoid unbounded pauses caused by interference from the garbage collector. The RTSJ uses runtime checks to ensure that deleting a region does not create dangling references and that real-time threads do not access references to objects allocated in the garbage-collected heap. This paper presents a static type system that guarantees that these runtime checks will never fail for well-typed programs. Our type system therefore 1) provides an important safety guarantee for real-time programs and 2) makes it possible to eliminate the runtime checks and their associated overhead.Our system also makes several contributions over previous work on region types. For object-oriented programs, it combines the benefits of region types and ownership types in a unified type system framework. For multithreaded programs, it allows long-lived threads to share objects without using the heap and without memory leaks. For real-time programs, it ensures that real-time threads do not interfere with the garbage collector. Our experience indicates that our type system is sufficiently expressive and requires little programming overhead, and that eliminating the RTSJ runtime checks using a static type system can significantly decrease the execution time of real-time programs.

We present an interprocedural and compositional algorithm for nding pairs of compatible allocation sites, which have the property that no object allocated at one site is live at the same time as any object allocated at the other site. If an allocation site is compatible with itself, it is said to be unitary : at most one object allocated at that site is live at any given point in the execution of the program. We use the results of the analysis to statically preallocate memory space for the objects allocated at unitary sites, thus simplifying the computation of an upper bound on the amount of memory required to execute the program. We also use the analysis to enable objects allocated at several compatible allocation sites to share the same preallocated memory. Our experimental results show that, for our set of Java benchmark programs, 60% of the allocation sites are unitary and can be statically preallocated. Moreover, allowing compatible unitary allocation sites to share the same preallocated memory leads to a 95% reduction in the amount of memory preallocated for these sites.

This paper presents a new combined pointer and escape analysis for multithreaded programs. The algorithm uses a new abstraction called parallel interaction graphs to analyze the interactions between threads and extract precise points-to, escape, and action ordering information for objects accessed by multiple threads. The analysis is compositional, analyzing each method or thread once to extract a parameterized analysis result that can be specialized for use in any context. It is also capable of analyzing programs that use the unstructured form of multithreading present in languages such as Java and standard threads packages such as POSIX threads.