[Bug rtl-optimization/42589] bswap optimization does not work for 32bit (but for 64bit) on 64bit registers

[rguenther at suse dot de]

------- Comment #4 from rguenther at suse dot de  2010-01-03 12:28 -------
Subject: Re:  bswap optimization does not work
 for 32bit (but for 64bit) on 64bit registers

On Sun, 3 Jan 2010, jakub at gcc dot gnu dot org wrote:

> ------- Comment #3 from jakub at gcc dot gnu dot org  2010-01-03 12:19 -------
> Shouldn't that be || (bswap32_p && word_mode == SImode) ? expand_unop
> will only call expand_doubleword_bswap in that case...

Hm, yeah.  I wonder why it doesn't try

  half_mode = smallest_mode_for_size (GET_MODE_PRECISION (mode) / 2, MODE_INT);
      if (GET_MODE_SIZE (mode) == 2 * GET_MODE_SIZE 
(half_mode)
          && optab_handler (unoptab, half_mode)->insn_code != 
CODE_FOR_nothing)
        {
          temp = expand_doubleword_bswap (mode, op0, target);
          if (temp)
            return temp;
        }

or similar.  Though in practice it might not matter...

Richard.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42589