[Bug middle-end/51994] [4.6/4.7 Regression] git-1.7.8.3 miscompiled due to negative bitpos from get_inner_reference

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51994

--- Comment #27 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-02-01 15:41:15 UTC ---
(In reply to comment #25)
> I've changed my mind: given that we shouldn't have references outside the base
> object in valid programs, there must be an offset if the bitpos is negative, so
> we can simply add the (rounded) latter to the former.  That's what the callers
> would have to do anyway, so we'd better factor it in get_inner_reference.

I'm not sure it's the best thing to do (adjusting 'offset' by
a BITS_PER_UNIT multiple instead of whatever the caller would like the most).
Only the callers would know how they want to adjust for negative bitpos.