https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82072
--- Comment #8 from Marek Polacek <mpolacek at gcc dot gnu.org> --- (In reply to Jakub Jelinek from comment #7) > (In reply to Marek Polacek from comment #6) > > This should fix the two issues above: > > > > --- a/gcc/convert.c > > +++ b/gcc/convert.c > > @@ -434,6 +434,12 @@ do_narrow (location_t loc, > > typex = lang_hooks.types.type_for_size (TYPE_PRECISION (typex), > > TYPE_UNSIGNED (typex)); > > > > + /* The type demotion below might cause doing unsigned arithmetic > > + instead of signed, and thus hide overflow bugs. */ > > + if (!TYPE_UNSIGNED (typex) > > + && sanitize_flags_p (SANITIZE_SI_OVERFLOW)) > > + return NULL_TREE; > > + > > Shouldn't we check ex_form here too, and only punt if it is an operation > problematic for the particular ubsan sanitization? > There is no reason why we can't e.g. narrow BIT_AND_EXPR. Good idea. > Have you checked the shift and division cases? I did, but try as I might, I'm not able to trigger a similar bug.
