Dr. Dobb's Journal - September 2008 - (Page 56)

d09kilch_p3db 7/11/08 1:31 PM Page 56 State of the Art SIGNALLING INTEGER OVERFLOWS IN JAVA What About C/C++ ? Java and C/C++ differ in their models of arithmetic expression evaluation, but the problem of arithmetic overflow is absolutely similar. Some C/C++ compilers offer an option to generate code that will check integer operations and report overflows. For instance, GCC comes with the -ftrapv flag, but it used to be implemented in a way that does not cover every situation: for instance, it doesn’t signal overflows on shorts, and it is known to miss some overflows on int multiplications. Maybe this is why it doesn’t seem to be popular. We found another attempt to provide instrumentation in GCC as a separate module using GEM, but the information is a bit laconic about the current state of this project (www.ecsl.cs.sunysb.edu/iop/index.html). • COJAC lets you choose between four reporting policies: printing a message on the console (stderr), showing the location in the source code (with or without a detailed stacktrace); writing a similar message to a log file; throwing an ArithmeticException; and applying a user-defined reaction (the user indicates the name of an existing static method that will be used as an error reporting function (Example 4). • It is possible to instrument only a single selected method, instead of the entire class. The instrumentation of course introduces overhead, both in speed and space (bytecode size). Consider first how many bytes are added to the bytecode file. Internally, we do not add any new classes, but in any instrumented class we do add: • Instructions in existing methods (a method call instead of an iadd). • Some items in the constant pool. Get moving. Stay focused. Take control. Enterprise Architect from Sparx Systems redefines visual modeling with a huge set of built-in tools, technologies and capabilities, coupled with a lightweight footprint and great agility. With deep support for UML 2.1 and its related standards, Enterprise Architect 7.1 is the ideal tool to analyze, design, build and manage your next software project. Keep your project moving, keep your team focused and stay in total control. Visit sparxsystems.com for a free trial 56 Dr. Dobb’s Journal l www.ddj.com l September 2008 http://www.ecsl.cs.sunysb.edu/iop/index.html http://sparxsystems.com http://sparxsystems.com http://www.ddj.com

Table of Contents Feed for the Digital Edition of Dr. Dobb's Journal - September 2008

Dr. Dobb's Journal - September 2008 Contents Friday Night Fish Fry Alia Vox Developer Diaries Developer’s Notebook A Conversation With Erik Demaine Application Lifecycle Management Meets Model-Driven Development Building a Robust Development Environment Real Users Really Matter Matching Wildcards: An Algorithm The Android Mobile Phone Platform Managing Application Thread Use Signalling Integer Overflows in Java .NET Development & the IBM WebSphere Portal Server The Agile Edge Effective Concurrency Swaine’s Flames

Dr. Dobb's Journal - September 2008

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