https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112949
--- Comment #3 from Krister Walfridsson <kristerw at gcc dot gnu.org> --- The C program is obviously UB. But the optimization is done on GIMPLE, and it is not obvious to me that the GIMPLE code is UB -- we have a function called __builtin_clz that calls an internal function, so they are different...
