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We present a pointer and array access checking technique that provides complete error coverage through a simple set of program transformations. Our technique, based on an extended safe pointer representation, has a number of novel aspects. Foremost, it is the first technique that detects all spatial and temporal access errors. Its use is not limited by the expressiveness of the language; that is, it can be applied successfully to compiled or interpreted languages with subscripted and mutable pointers, local references, and explicit and typeless dynamic storage management, e.g., C. Because it is a source level transformation, it is amenable to both compile- and run-time optimization. Finally, its performance, even without compile-time optimization, is quite good. We implemented a prototype translator for the C language and analyzed the checking overheads of six non-trivial, pointer intensive programs. Execution overheads range from 130 % to 540%; with text and data size overheads typically below 100%.

This article surveys and analyzes these developments by establishing criteria for evaluating trace-driven methods, and then applies these criteria to describe, categorize, and compare over 50 trace-driven simulation tools. We discuss the strengths and weaknesses of different approaches and show that no single method is best when all criteria, including accuracy, speed, memory, flexibility, portability, expense, and ease of use are considered. In a concluding section, we examine fundamental limitations to trace-driven simulation, and survey some recent developments in memory simulation that may overcome these bottlenecks

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Improving the performance of C programs has been a topic of great interest for many years. Both hardware technology and compiler optimization research has been applied in an effort to make C programs execute faster. In many application domains, the C++ language is replacing C as the programming language of choice. In this paper, we measure the empirical behavior of a group of significant C and C++ programs and attempt to identify and quantify behavioral differences between them. Our goal is to determine whether optimization technology that has been successful for C programs will also be successful in C++ programs. We furthermore identify behavioral characteristics of C++ programs that suggest optimizations that should be applied in those programs. Our results show that C++ programs exhibit behavior that is significantly different than C programs. These results should be of interest to compiler writers and architecture designers who are designing systems to execute object-oriented programs.

The current main memory (DRAM) access speeds lag far behind CPU speeds. Cache memory, made of static RAM, is being used in today's architectures to bridge this gap. It provides access latencies of 2--4 processor cycles, in contrast to main memory which requires 15--25 cycles. Therefore, the performance of the CPU depends upon how well the cache can be utilized. We show that there are significant benefits in redesigning our traditional query processing algorithms so that they can make better use of the cache. The new algorithms run 8%--200% faster than the traditional ones. 1 Introduction The DRAM access speeds have not reduced much compared to the CPU cycle time reduction resulting from the improvements in VLSI technology. Cache memories, made of fast static RAM, help alleviate this disparity by exploiting the spatial and temporal locality in the data accesses of a program. However, programs with poor access locality waste significantly many cycles transferring the data to and from th...

Dynamic information collected as a software system executes can help software engineers perform some tasks on a system more effectively. To interpret the sizable amount of data generated from a system's execution, engineers require tool support. We have developed an off-line, flexible approach for visualizing the operation of an object-oriented system at the architectural level. This approach complements and extends existing profiling and visualization approaches available to engineers attempting to utilize dynamic information. In this paper, we describe the technique and discuss preliminary qualitative studies into its usefulness and usability. These studies were undertaken in the context of performance tuning tasks. Keywords Software visualization, programming environments, software structure, program comprehension, execution trace, performance. 1 INTRODUCTION Effective performance of many software engineering tasks requires knowledge of how the system works. Gaining the desired k...

In recent work, we described a data prefetch mechanism for pointer-intensive and numeric computations, and presented some aggregate measurements on a suite of benchmarks to quantify its performance potential [MH95]. The basis for this device is a simple classification of memory access patterns in programs that we introduced earlier [HM94]. In this paper we take a close look at two codes from our suite, an English parser called Link-Gram, and the circuit simulation program spice2g6, and present a detailed analysis of them in the context of our model. Focusing on just two programs allows us to display a wider range of data, and discuss relevant code fragments extracted from their source distributions. Results from this study provide a deeper understanding of our memory access classification scheme, and suggest additional optimizations for future data prefetch mechanisms. Keywords: CPU architecture, data cache, memory access pattern classification, instruction profiling, memory latency t...

In survivability management systems, some management entities reside on application hosts that are not necessarily trustworthy. The integrity of these software entities is essential to the security of the network management scheme. In this talk, I present a novel framework to facilitate software security against malicious execution environments. The approach