Sorry, do not know, how to insert attachment, please find offending file here :
https://github.com/samr7/vanitygen/blob/master/calc_addrs.cl
The problem is now(latest drivers) only misbehaviour (not crash),it calculates incorrect GPU sum compared to CPU :
https://github.com/samr7/vanitygen/issues/19#issuecomment-22161310
but may be solved by downgrading AMDAPP SDK to 2.7 as somebody mentioned , will try ...