From: Diego Novillo <dnovillo@redhat.com>
To: Roger Sayle <roger@eyesopen.com>
Cc: gcc@gcc.gnu.org
Subject: PR 23046. Folding predicates involving TYPE_MAX_VALUE/TYPE_MIN_VALUE
Date: Fri, 05 Aug 2005 14:00:00 -0000 [thread overview]
Message-ID: <20050805135953.GA23609@topo.toronto.redhat.com> (raw)
In PR 23046 we ICE inside tree-vrp.c because fold() does not
realize that for
enum enumtype { ENUM1, ENUM2 } x;
the predicate 'if (x > 1)' is always false. This causes VRP to
create the impossible range [2, 1] for that predicate.
While it would be trivial for VRP to paper over this problem, the
real fix should be in fold(). I looked at the logic that detects
these cases and it is fairly convoluted (fold-const.c:9174).
I'm wondering why doesn't fold() just use TYPE_MAX_VALUE/TYPE_MIN_VALUE
if they're available?
Thanks.
next reply other threads:[~2005-08-05 14:00 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-08-05 14:00 Diego Novillo [this message]
2005-08-05 16:35 ` Roger Sayle
2005-08-05 17:58 ` Jeffrey A Law
2005-08-05 20:04 ` PR 23046. Folding predicates involving TYPE_MAX_VALUE/TYPE_MIN_VALUE (Ada RFC) Richard Henderson
2005-08-05 20:15 ` Florian Weimer
2005-08-05 20:56 ` Richard Henderson
2005-08-05 21:04 ` Florian Weimer
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