https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82282
--- Comment #5 from rguenther at suse dot de <rguenther at suse dot de> --- On Fri, 22 Sep 2017, nunoplopes at sapo dot pt wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82282 > > --- Comment #4 from Nuno Lopes <nunoplopes at sapo dot pt> --- > There are two major transformations going on: > if (u != v) { > v = u; > } > => > v = u > > (with v, u integers) > > and: > > glb = (int*)(uinptr_t)foo) > => > glb = foo > > > Doing both triggers the end-to-end miscompilation for a C program that > exhibits > no UB. That means that one of transformations is wrong. > Disabling integer propagation would be really weird and bad. > So we are left with making "(int*)(uinptr_t)foo -> foo" an invalid > transformation in general. It's correct in some cases, but not always. The C standard says it is correct as in, it yields the same pointer.
