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[Bug rtl-optimization/42589] bswap optimization does not work for 32bit (but for 64bit) on 64bit registers
- From: "rguenther at suse dot de" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 3 Jan 2010 12:28:23 -0000
- Subject: [Bug rtl-optimization/42589] bswap optimization does not work for 32bit (but for 64bit) on 64bit registers
- References: <bug-42589-7834@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- 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