[Bug tree-optimization/49911] SRA + DOM + VRP + -fstrict-enums incorrectly remove predicate

["ebotcazou at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49911

--- Comment #16 from Eric Botcazou <ebotcazou at gcc dot gnu.org> 2011-08-12 08:01:36 UTC ---
> 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).

They certainly used to mean something, so it would be interesting to know when
they stopped doing so.  The existence of -fstrict-enums is an evidence.

> 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).

The folder cares (or used to care), in particular the range code.

In any case, this particular problem is more of a SRA bug in my opinion.