Re: Fix handling of negative bitpos in expand_debug_expr

[Bernd Schmidt <bschmidt at redhat dot com>]

On 05/05/2016 04:20 PM, Richard Sandiford wrote:
> expand_debug_expr handled negative bit positions using:
>
>              else if (bitpos < 0)
>                {
>                  HOST_WIDE_INT units
>                    = (-bitpos + BITS_PER_UNIT - 1) / BITS_PER_UNIT;
>                  op0 = adjust_address_nv (op0, mode1, units);
>                  bitpos += units * BITS_PER_UNIT;
>                }
>
> Here "units" is the negative of the (negative) byte offset, so I think
> we should be offsetting OP0 by -units instead.  E.g. a bitpos of -17
> would give units==3, so this code would move OP0 up by 3 bytes and set
> bitpos to 7, giving a total bitpos of 31.

> gcc/
> 	* cfgexpand.c (expand_debug_expr): Fix address offset for negative
> 	bitpos.

Ok.


Bernd