------- Additional Comments From kenner at vlsi1 dot ultra dot nyu dot edu
2005-05-30 18:36 -------
Subject: Re: [4.0/4.1 Regression] &a[-2] ICE at the top level
The difference in the handling of these two expressions is that
get_inner_reference sets the "offset" out-parameter for &a[-2], but
not for a[2]. That's at odds with its documentation, which says that
offset is only set if the offset is not a constant.
Is this because the value doesn't fit in some type? I don't understand
why it's doing that.
Furthermore, the out-parameter "bitpos" is signed, which suggests that
negative values should be acceptable.
I think this is just consistency: bitpos is signed all over the place.
But, actually, I think there are some cases where the are negative bit
positions: the object a thin pointer in Ada points to comes to mind.
Changing get_inner_reference to use ssizetype and sbitsizetype
throughout fixes the problems -- but I'm not sure if that's 100%
correct.
Nor am I, but I can't offhand think of anything it would breajk.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21135
