------- Comment #32 from rguenth at gcc dot gnu dot org 2007-03-28 08:52
-------
There is
/* Refuse to operate on VARYING ranges, ranges of different kinds
and symbolic ranges. As an exception, we allow BIT_AND_EXPR
because we may be able to derive a useful range even if one of
the operands is VR_VARYING or symbolic range. TODO, we may be
able to derive anti-ranges in some cases. */
if (code != BIT_AND_EXPR
&& code != TRUTH_AND_EXPR
&& code != TRUTH_OR_EXPR
&& (vr0.type == VR_VARYING
|| vr1.type == VR_VARYING
|| vr0.type != vr1.type
|| symbolic_range_p (&vr0)
|| symbolic_range_p (&vr1)))
{
set_value_range_to_varying (vr);
return;
}
which sets the value range to varying if vr0.type != vr1.type, so if
vr1.type is not an anti-range, then vr0.type isn't either.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31169
