https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85315
--- Comment #4 from rguenther at suse dot de <rguenther at suse dot de> --- On April 10, 2018 4:50:49 PM GMT+02:00, "msebor at gcc dot gnu.org" <gcc-bugzi...@gcc.gnu.org> wrote: >https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85315 > >Martin Sebor <msebor at gcc dot gnu.org> changed: > > What |Removed |Added >---------------------------------------------------------------------------- > CC| |msebor at gcc dot gnu.org > >--- Comment #3 from Martin Sebor <msebor at gcc dot gnu.org> --- >A simpler test case that shows the same optimization opportunity is: > > int f (int i) > { > extern int x; > int y; > return &y + i == &x; > } > >A test case that both Clang and GCC get wrong is below. (This will be >discussed at the next WG14 meeting -- see >http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2222.htm#q23-can-one-do-comparison-between-pointers-to-objects-of-compatible-types-with-different-provenances-that-are-not-strictly-within-their-original-allocations) > > int g (int i) > { > int x, y, z; > > int *p = &x + i; > int *q = &y; > > return p == q; > } If you eventually expect a true result then please no - this should be undefined.
