Dead code: Difference between revisions

Revision as of 07:26, 13 May 2012

Revision as of 04:48, 15 June 2012

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{{Merge from|Dead code elimination|date=November 2010}}

In [[computer programming]], '''dead code''' is a code in the [[source code]] of a program which is executed but whose result is never used in any other computation.<ref>[http://doi.acm.org/10.1145/349214.349233 Debray, S. K., Evans, W., Muth, R., and De Sutter, B. 2000. Compiler techniques for code compaction. ACM Trans. Program. Lang. Syst. 22, 2 (Mar. 2000), 378-415.]</ref><ref>[[Andrew Appel|Appel, A. W.]] 1998 Modern Compiler Implementation in Java. Cambridge University Press.</ref> The execution of dead code wastes computation time as its results are never used.

While the result of a dead computation may never be used, the dead code may raise [[exceptions]] or affect some global state, thus removal of such code may change the output of the program and introduce unintended [[software bug|bugs]]. Compiler optimizations are typically conservative in their approach to dead code removal if there is any ambiguity as to whether removal of the dead code will affect the program output.