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| Content Provider | ACM Digital Library |
|---|---|
| Author | Guyer, Samuel Z. McKinley, Kathryn S. Kent, Stephen W. Bond, Michael D. Nethercote, Nicholas |
| Abstract | Programs sometimes crash due to unusable values, for example, when Java and C# programs dereference null pointers and when C and C++ programs use undefined values to affect program behavior. A stack trace produced on such a crash identifies the effect of the unusable value, not its cause, and is often not much help to the programmer. This paper presents efficient origin tracking of unusable values; it shows how to record where these values come into existence, correctly propagate them, and report them if they cause an error. The key idea is value piggybacking: when the original program stores an unusable value, value piggybacking instead stores origin information in the spare bits of the unusable value. Modest compiler support alters the program to propagate these modified values through operations such as assignments and comparisons. We evaluate two implementations: the first tracks null pointer origins in a JVM, and the second tracks undefined value origins in a memory-checking tool built with Valgrind. These implementations show that origin tracking via value piggybacking is fast and often useful, and in the Java case, has low enough overhead for use in a production environment. |
| Starting Page | 405 |
| Ending Page | 422 |
| Page Count | 18 |
| File Format | |
| ISSN | 03621340 15581160 |
| DOI | 10.1145/1297105.1297057 |
| Journal | ACM SIGPLAN Notices (SIGP) |
| Volume Number | 42 |
| Issue Number | 10 |
| Language | English |
| Publisher | Association for Computing Machinery (ACM) |
| Publisher Date | 1983-05-01 |
| Publisher Place | New York |
| Access Restriction | One Nation One Subscription (ONOS) |
| Subject Keyword | Java Low-overhead run-time support Undefined values Managed languages Debugging Null pointer exceptions Valgrind |
| Content Type | Text |
| Resource Type | Article |
| Subject | Computer Graphics and Computer-Aided Design Software |
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