Re: [PATCH] Use MEM_EXPR only if MEM_P is true

[Stefan Schulze Frielinghaus]

On Wed, Jun 04, 2025 at 05:07:13PM +0200, Jakub Jelinek wrote:
> On Wed, Jun 04, 2025 at 05:02:45PM +0200, Stefan Schulze Frielinghaus wrote:
> > Building a subreg in case of
> >
> >   else if (GET_CODE (x) == CONST)
> >     {
> >       /* Extract the symbol ref from:
> >          (mem:QI (const:DI (unspec:DI [(symbol_ref:DI ("foo"))]
> >                                        UNSPEC_PLT/GOTENT)))  */
>
> Shouldn't that have one extra MEM somewhere?

The MEM referred to in the comment was stripped of previously:

  if (GET_CODE (x) != MEM)
    return orig_x;

  x = XEXP (x, 0);
  if (GET_CODE (x) == PLUS
      && GET_CODE (XEXP (x, 1)) == CONST
      && GET_CODE (XEXP (x, 0)) == REG
      && REGNO (XEXP (x, 0)) == PIC_OFFSET_TABLE_REGNUM)
    {
      y = XEXP (XEXP (x, 1), 0);
      if (GET_CODE (y) == UNSPEC
          && XINT (y, 1) == UNSPEC_GOT)
        y = XVECEXP (y, 0, 0);
      else
        return orig_x;
    }
  else if (GET_CODE (x) == CONST)
    {
      /* Extract the symbol ref from:
         (mem:QI (const:DI (unspec:DI [(symbol_ref:DI ("foo"))]
                                       UNSPEC_PLT/GOTENT)))  */

      y = XEXP (x, 0);
      if (GET_CODE (y) == UNSPEC
          && (XINT (y, 1) == UNSPEC_GOTENT
              || XINT (y, 1) == UNSPEC_PLT31))
        y = XVECEXP (y, 0, 0);
      else
        return orig_x;
    }
  else
    return orig_x;

  if (GET_MODE (orig_x) != Pmode)
    {
      if (GET_MODE (orig_x) == BLKmode)
        return orig_x;
      y = lowpart_subreg (GET_MODE (orig_x), y, Pmode);
      if (y == NULL_RTX)
        return orig_x;
    }
  return y;
}

or did you mean another one?

Cheers,
Stefan