Code within a program that is never executed is known as dead code. The presence of dead code often indicates that a logic error has occurred. Typically, this error is an a result of changes to the program or the environment. Dead code is often identified and optimized out dead code during compilation. However, it should be identified, understood, and removed from a program's source code to improve readability and ensure that logic errors are resolved.
Non-Compliant Code Example
This example, inspired by Fortify demonstrates how dead code can be introduced into a program. Because s
is set to NULL
everything inside if (s)
will never be executed. It requires that condition
be non-null, while on the only path where s
can be assigned a non-null value there is a return statement.
int func(int condition) { int *s = NULL; if (condition) { s = malloc(10); if (s == NULL) { /* Handle Error */ } /* insert data into s */ return; } /* ... */ if (s) { /* This statement is never reached */ } }