gcc attribute overview

List of attributes that can be used improve gcc optimisations.  The ones I find most useful are:

• pure: Function doesn't change any external variables.
• const: Function doesn't read any external variables.
• noreturn: Function will not return e.g. exit() or abort().
• nonnull: Warning if null arguments are passed.
• warn_unused_result: Warns if the result of a function is not used/checked.

http://www.ohse.de/uwe/articles/gcc-attributes.html