Dead store
program variable set but then not used
In computer programming, a dead store is a local variable that is assigned a value but is read by no following instruction. Dead stores waste processor time and memory, and may be detected through the use of static program analysis, and removed by an optimizing compiler.
If the purpose of a store is intentionally to overwrite data, for example when a password is being removed from memory, dead store optimizations can cause the write not to happen, leading to a security issue. Some system libraries have specific functions designed to avoid such dangerous optimizations, e.g. explicit_bzero on OpenBSD.
Examples
Java
Dead store example in Java:
In the above code an ArrayList<String> object was instantiated but never used. Instead, in the next line the variable which references it is set to point to a different object. The ArrayList which was created when list was declared will now need to be de-allocated, for instance by a garbage collector.
JavaScript
Dead store example in JavaScript:
The code in the loop repeatedly overwrites the same variable, so it can be reduced to only one call.
Begin with the source’s own compact description: “Dead store” is program variable set but then not used. The dossier treats that line as a proposition to test through Dead, store and program, not as a finished interpretation.
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Vocabulary and entity names are the principal evidence signals here, because they determine the precision of every later search. The source revision retrieved here is dated Sep 18, 2026. The linked authority identifier is Q3207945.
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This entry incorporates text from “Dead store” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.