[Bug middle-end/58970] [4.7/4.8/4.9 Regression] internal compiler error: in get_bit_range, at expr.c:4562

["bernd.edlinger at hotmail dot de" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58970

--- Comment #12 from Bernd Edlinger <bernd.edlinger at hotmail dot de> ---
(In reply to Jakub Jelinek from comment #11)
> (In reply to Bernd Edlinger from comment #10)
> > but this should'nt be neccessary then?
> > 
> >    if (bitoffset > *bitpos)
> >      {
> >        HOST_WIDE_INT adjust = bitoffset - *bitpos;
> > -
> >        gcc_assert ((adjust % BITS_PER_UNIT) == 0);
> > -      gcc_assert (*offset != NULL_TREE);
> >  
> >        *bitpos += adjust;
> > -      *offset
> > -	= size_binop (MINUS_EXPR, *offset, size_int (adjust / BITS_PER_UNIT));
> > +      if (*offset == NULL_TREE)
> > +	*offset = size_int (-adjust / BITS_PER_UNIT);
> > +      else
> > +	*offset
> > +	  = size_binop (MINUS_EXPR, *offset, size_int (adjust / BITS_PER_UNIT));
> >        *bitstart = 0;
> >      }
> 
> Can you prove it isn't necessary?  I mean, *bitpos could still be smaller
> than bitoffset, even when not negative, say with some packed+aligned
> structures containing bitfields or similar.  NULL_TREE *offset is the same
> thing as zero at that spot, just perhaps less efficient in that case, so I
> think if we can't prove it will not be hit, it is easy to handle it.

hmm, my english...

I meant the change here is not necessary, because after the
if (*bitpos < 0) {...},
*offset can no longer be NULL, and I'd leave the assertion untouched.