http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51994
--- Comment #19 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-01-26 10:01:23 UTC --- I agree, all callers of get_inner_reference need to cope with a negative bitpos. Those that forward it unchecked to functions that expect an unsigned bitpos are broken. Thus I think fixing the prototypes is correct. If that exposes other issues we have to fix them. The issue in extract_split_bit_field is obviously the same - unsigned prototype and unsigned offset in while (bitsdone < bitsize) { unsigned HOST_WIDE_INT thissize; rtx part, word; unsigned HOST_WIDE_INT thispos; unsigned HOST_WIDE_INT offset; offset = (bitpos + bitsdone) / unit; also thispos = (bitpos + bitsdone) % unit; might not be correct with a negative (bitpos + bitsdone). extract_fixed_bit_field has the same prototype issue, so eventually we want to simply account for them in the callers (if there are less). Only memory operands may have a negative bitpos and those we should be able to adjust via adjust_address (but by what amount?) to make bitpos positive. So you could say already the routines called from the get_inner_reference callers should do that. Eric, you should know this area the best - what do you recommend here? [we could assert in the unsigned bitpos taking functions that the MSB is not set on bitpos]