https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100499
--- Comment #18 from bin cheng <amker at gcc dot gnu.org> --- Did some experiments, there are two fallouts after explicitly returning false for unsigned/wrapping types in MULT_EXPR/MINUS_EXPR/PLUS_EXPR. One is the mentioned use of multiple_of_p in number_of_iterations_ne, the other is for alignment warning in stor-layout.c. As pointed out, the latter case is known not overflow/wrap. So I am thinking to introduce an additional parameter indicating that caller knows "top" doesn't overfow/wrap, otherwise, try to get rid of the undocumented assumption. we can always improve the accuracy using ranger or other tools. Not sure if this is the right way to do. As for MULT_NO_OVERFLOW/PLUS_NO_OVERFLOW, IMHO, it's not that simple? For example, unsigned_num(multiple of 4, and larger than 0) + 0xfffffffc is multiple of 4, but it's overflow behavior on which we rely here.
