[Bug c/31469] New: move_by_pieces in expr.c function bug

[omer dot medan at gmail dot com]

The function move_by_pieces in expr.c enters to endless loop when the backend
defines the sizes of all data types to be the same size (aka CHAR_TYPE_SIZE    
  = SHORT_TYPE_SIZE       = INT_TYPE_SIZE = anyvalue …).

The loop itself occurs in this code section - 
while (max_size > 1)
    {

      for (tmode = GET_CLASS_NARROWEST_MODE (MODE_INT);
           tmode != VOIDmode; tmode = GET_MODE_WIDER_MODE (tmode))
        if (GET_MODE_SIZE (tmode) < max_size)
          mode = tmode;

      if (mode == VOIDmode)
        break;

      icode = mov_optab->handlers[(int) mode].insn_code;
      if (icode != CODE_FOR_nothing && align >= GET_MODE_ALIGNMENT (mode))
        move_by_pieces_1 (GEN_FCN (icode), mode, &data);

      max_size = GET_MODE_SIZE (mode);
    }

The idea here is to decrease the sizes of copying insn, or something like that, 
But what if it isn’t decreasing?

Thanks.


-- 
           Summary: move_by_pieces in expr.c function bug
           Product: gcc
           Version: 4.1.1
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: omer dot medan at gmail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31469