On June 17, 2019 6:23:03 PM GMT+02:00, Richard Sandiford <richard.sandif...@arm.com> wrote: >Jan Hubicka <hubi...@ucw.cz> writes: >>> >> > >>> >> > A more stricter test would be >>> >> > >>> >> > if (!maybe_eq (max_size1, size1) && !maybe_eq (max_size2, >size2)) >>> >> > return true; >>> >> > /* If there's a variable access in one of the refs fall >through >>> >> > to access-path based disambiguation. */ >>> >> > >>> >> > where you'd need to pass down ao_ref_size in addition to >max_size as well. >>> >> >>> >> Proably || here? >>> > >>> > Hmm, !maybe_eq () -> ! max_size1 == size1 -> max_size != size1 >thus >>> > I think && is correct if you want to disambiguate a[1].v2 and >a[i].v1 >>> > >>> > But yes, if you don't want that then || is cheaper. Probably add >>> > another testcase with one of the accesses with a constant index? >>> >>> Might be misunderstanding, but isn't the check for a variable access >>> !known_eq (max_size1, size1) == maybe_ne (max_size1, size1)? >"maybe_eq" >>> means "could be equal in some circumstances, even if they're not >always >>> equal". >> >> Seems I am getting progressively more confused. > >Well, me too :-) I didn't really understand the choice of the original >condition above. It seemed to be "return true if both access sizes are >variable", but the comment implied something else.
Sorry,! Must_eq is obviously fine. >But I was just picking up on the choice of maybe_eq vs. known_eq in the >condition, which as things stand would only matter for SVE. And... > >> I think I want to pass the size down from ao_ref to the functions and >> then see if they are always equal. > >...right, that's what I mean. known_eq gives you "always equal", >i.e. "not variable". The maybe_eq in the original condition seemed odd >because it includes the constant case and (potentially) variable cases >that are size1 or bigger. > >In inverted conditions, !known_eq can be written maybe_ne (but doesn't >need to be, if !known_eq seems clearer). > >Thanks, >Richard > >> >> Why would I want to use maybe variant? >> >> Honza >> >>> >>> Richard
