http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49911
--- Comment #15 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-08-11 13:41:24 UTC --- (In reply to comment #11) > > So, Eric - are you still objecting to make VRP and the middle-end aligned > > by ignoring TYPE_MIN/MAX_VALUE in VRP? > > Just to give a bit of context to the reader: this problem bit the Ada compiler > since VRP had been introduced in 2004. At the time, the consensus was that > the > Ada compiler was lying to the middle-end, because objects of type T could have > values that are outside [TYPE_MIN_VALUE:TYPE_MAX_VALUE] in some cases and this > breaks an invariant of the middle-end. So we changed the Ada compiler in > 2009. > > If it appears that the previous consensus was short-sighted and should now be > reversed, fine with me, but please document what TYPE_MIN_VALUE/TYPE_MAX_VALUE > mean under the new one. And if they don't mean anything, then remove them. No, they still mean "nothing", but VRP assumes they are the canonical value according to precision/signedness. Which C and C++ do not follow. Unfortunately the C and C++ maintainers do not care (and probably have a harder job "fixing" this because they lack the nice separation of the "real" frontend and the interface to GENERIC). As they mean "nothing" I would like to make VRP not assume anything about them (and VRP is really the only one caring for TYPE_MIN/MAX_VALUE apart from array domain uses).
