suspicious piece of code in RTS(Profiling.c) code

Hi all, I recently found a suspicious piece of code in RTS code. * https://github.com/ghc/ghc/blob/master/rts/Profiling.c#L622 here it's checking that ccs is not EMPTY_STACK. * https://github.com/ghc/ghc/blob/master/includes/rts/prof/CCS.h#L96 here EMPTY_STACK is defined as NULL. Now weird part is that before the if-statement checks for `ccs != NULL` ccs is used to reach some of it's fields(for example, line 601 and 602). As far as I can see either we have a bug here or the if-statement is not necessary and we can move it's body to top level. Am I missing anything here? Thanks. --- Ömer Sinan Ağacan http://osa1.net