gcc-pr22071.patch

   1 --- gcc/gcc/tree-ssa-structalias.c      2005/06/30 22:18:35     2.8
   2 +++ gcc/gcc/tree-ssa-structalias.c      2005/07/01 19:45:23     2.9
   3 @@ -1940,6 +1940,25 @@
   4  }
   5
   6
   7 +/* Return true if an access to [ACCESSPOS, ACCESSSIZE]
   8 +   overlaps with a field at [FIELDPOS, FIELDSIZE] */
   9 +
  10 +static bool
  11 +offset_overlaps_with_access (const unsigned HOST_WIDE_INT fieldpos,
  12 +                            const unsigned HOST_WIDE_INT fieldsize,
  13 +                            const unsigned HOST_WIDE_INT accesspos,
  14 +                            const unsigned HOST_WIDE_INT accesssize)
  15 +{
  16 +  if (fieldpos == accesspos && fieldsize == accesssize)
  17 +    return true;
  18 +  if (accesspos >= fieldpos && accesspos <= (fieldpos + fieldsize))
  19 +    return true;
  20 +  if (accesspos < fieldpos && (accesspos + accesssize > fieldpos))
  21 +    return true;
  22 +
  23 +  return false;
  24 +}
  25 +
  26  /* Given a COMPONENT_REF T, return the constraint_expr for it.  */
  27
  28  static struct constraint_expr
  29 @@ -2000,8 +2019,27 @@
  30          we may have to do something cute here.  */
  31
  32        if (result.offset < get_varinfo (result.var)->fullsize)
  33 -       result.var = first_vi_for_offset (get_varinfo (result.var),
  34 -                                         result.offset)->id;
  35 +       {
  36 +         /* It's also not true that the constraint will actually start at the
  37 +            right offset, it may start in some padding.  We only care about
  38 +            setting the constraint to the first actual field it touches, so
  39 +            walk to find it.  */
  40 +         varinfo_t curr;
  41 +         for (curr = get_varinfo (result.var); curr; curr = curr->next)
  42 +           {
  43 +             if (offset_overlaps_with_access (curr->offset, curr->size,
  44 +                                              result.offset, bitsize))
  45 +               {
  46 +                 result.var = curr->id;
  47 +                 break;
  48 +
  49 +               }
  50 +           }
  51 +         /* assert that we found *some* field there. The user couldn't be
  52 +            accessing *only* padding.  */
  53 +
  54 +         gcc_assert (curr);
  55 +       }
  56        else
  57         if (dump_file && (dump_flags & TDF_DETAILS))
  58           fprintf (dump_file, "Access to past the end of variable, ignoring\n");