Software testing helps ensure not only that the software under development has been implemented correctly, but also that further development does not break it. If developers introduce new defects into the software, these should be detected as early and inexpensively as possible in the development cycle. To help optimize which tests are run at what points in the design cycle, we have built Echelon, a test prioritization system, which prioritizes the application's given set of tests, based on what changes have been made to the program.Echelon builds on the previous work on test prioritization and proposes a practical binary code based approach that scales well to large systems. Echelon utilizes a binary matching system that can accurately compute the differences at a basic block granularity between two versions of the program in binary form. Echelon utilizes a fast, simple and intuitive heuristic that works well in practice to compute what tests will cover the affected basic blocks in the program. Echelon orders the given tests to maximally cover the affected program so that defects are likely to be found quickly and inexpensively. Although the primary focus in Echelon is on program changes, other criteria can be added in computing the priorities.Echelon is part of a test effectiveness infrastructure that runs under the Windows environment. It is currently being integrated into the Microsoft software development process. Echelon has been tested on large Microsoft product binaries. The results show that Echelon is effective in ordering tests based on changes between two program versions.

Software testing helps ensure not only that the software under development has been implemented correctly, but also that further development does not break it. If developers introduce new defects into the software, these should be detected as early and inexpensively as possible in the development cycle. To help optimize which tests are run at what points in the design cycle, we have built Echelon, a test prioritization system, which prioritizes the application's given set of tests, based on what changes have been made to the program.Echelon builds on the previous work on test prioritization and proposes a practical binary code based approach that scales well to large systems. Echelon utilizes a binary matching system that can accurately compute the differences at a basic block granularity between two versions of the program in binary form. Echelon utilizes a fast, simple and intuitive heuristic that works well in practice to compute what tests will cover the affected basic blocks in the program. Echelon orders the given tests to maximally cover the affected program so that defects are likely to be found quickly and inexpensively. Although the primary focus in Echelon is on program changes, other criteria can be added in computing the priorities.Echelon is part of a test effectiveness infrastructure that runs under the Windows environment. It is currently being integrated into the Microsoft software development process. Echelon has been tested on large Microsoft product binaries. The results show that Echelon is effective in ordering tests based on changes between two program versions.

Compilers for new machines with 64-bit addresses must generate code that works when the memory used by the program is large. procedures and global variables are accessed indirectly via global address tables, and calling conventions include code to establish the addressability of the appropriate tables. In the common case of a program that does not require a lot of memory, all of this can be simplified considerably, with a corresponding reduction in program size and execution time.We have used our link-time code modification system OM to perform program transformations related to globat address use on the Alpha AXP. Though simple, many of these are whole-program optimization that can be done only when we can see the entire program at once, so link-time is an ideal occasion to perform them. This paper describes the optimization performed and shows their effects on program size and performance. Relatively modest transformations, possible without moving code, improve the performance of SPEC benchmarks by an average of 1.5Y0.More ambitious transformations, requiring an understanding of program structure that is thorough but not difficult at link-time, can do even better, reducing program size by 10% or more, and improving performance by an average of 3.87i0.Even a program compiled monolithically with interprocedurat optimization can benefit nearly as much from this teehnique, if it contains statically-linked pre-compiled library code. When the benchmark sources were compiled in this way, we were still able to improve their performance by 1.35% with the modest transformations and 3.4% with the ambitious transformations.Permission to co y without fee all or part of this material is J' granted provid that the copies are not made or distributed for direct commercial advantage, the ACM copyright notice and the title of the publication and its date appear, and notice is given that copying is by permission of the Association of Computing Machinery. To copy otherwise, or to republish, requires a tee and/or specific permission. SIGPLAN 94-6/

Unreachable procedures are procedures that can never be invoked. Their existence may adversely affect the performance of a program. Unfortunately, their detection requires the entire program to be present. Using a long-time code modification system, we analyze large, linked, program modules of C++, C, and Fortran. We find that C++ programs using object-oriented programming style contain a large fraction of unreachable procedure code. In contrast, C and Fortran programs have a low and essentially constant fraction of unreachable code. In this article, we present our analysis of C++, C, and Fortran programs, and we discuss how object-oriented programming style generates unreachable procedures.

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