https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66248
--- Comment #3 from Steve Ellcey <sje at gcc dot gnu.org> --- My understanding (I don't have a C/C++ standard handy) is that the addition done by 'ret + a[i]' is done in integer mode (not as short). This results in an integer value that may be outside the range of a short, but in the range of a normal integer. So this is not really an overflow. Then the integer result is assigned to ret, which is short. I believe that the truncation of a integer value (with a value outside the range of a short) to a short is not undefined by the C and C++ standards but has a specific way that it needs to work (truncate off the higher bits). This is the truncation that needs to be done on each loop iteration.
