Dead store

In computer programming, a local variable that is assigned a value but is not read by any subsequent instruction is referred to as a dead store. 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.