Dead code: Difference between revisions

Revision as of 21:47, 14 January 2013

Revision as of 21:49, 14 January 2013

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In [[computer programming]], '''dead code''' is 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 [[Exception handling|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. The programmer may aid the compiler in this matter by declaringmaking functionsadditional use asof [[Method (computer programming)#Static methods|static]] and/or [[Inline function|inline]] functions and enabling the use of [[link-time optimization]].

== Example ==