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

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

[omer dot medan at gmail dot com]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain, Size: 1266 bytes --]

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

[Bug middle-end/31469] move_by_pieces in expr.c function bug

[pinskia at gcc dot gnu dot org]

-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|major                       |normal
          Component|c                           |middle-end


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

[Bug middle-end/31469] move_by_pieces in expr.c function bug

[pinskia at gcc dot gnu.org]

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

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2021-08-16
             Status|UNCONFIRMED                 |WAITING
           Keywords|                            |internal-improvement

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
>CHAR_TYPE_SIZE	= SHORT_TYPE_SIZE	= INT_TYPE_SIZE
Won't matter in this loop.

what matters is QImode == 1. 

But if the target overrides machmode.def I doubt this can happen
INT_MODE (QI, 1);
INT_MODE (HI, 2);
INT_MODE (SI, 4);
INT_MODE (DI, 8);
INT_MODE (TI, 16);

[Bug middle-end/31469] move_by_pieces in expr.c function bug

[bigotp at acm dot org]

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

Peter A. Bigot <bigotp at acm dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bigotp at acm dot org

--- Comment #2 from Peter A. Bigot <bigotp at acm dot org> 2011-02-21 09:53:10 UTC ---
(In reply to comment #1)
> Created attachment 23422 [details]
> Fixes problem (resubmit, lost due to collision)

Sorry, bugzilla confused me, this attachment was intended for 42722.

[Bug middle-end/31469] move_by_pieces in expr.c function bug

[bigotp at acm dot org]

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

--- Comment #1 from Peter A. Bigot <bigotp at acm dot org> 2011-02-21 09:51:24 UTC ---
Created attachment 23422
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=23422
Fixes problem (resubmit, lost due to collision)