From: Andrew Pinski <andrew.pinski@caviumnetworks.com>
To: Bingfeng Mei <bmei@broadcom.com>
Cc: Richard Guenther <richard.guenther@gmail.com>,
"gcc@gcc.gnu.org" <gcc@gcc.gnu.org>
Subject: Re: Why doesn't GCC generate conditional move for COND_EXPR?
Date: Fri, 04 May 2012 21:26:00 -0000 [thread overview]
Message-ID: <CA+=Sn1kovmxoKop9xiEENs209y=Yiq9bjed70oxN3Ph9wYtEqA@mail.gmail.com> (raw)
In-Reply-To: <7FB04A5C213E9943A72EE127DB74F0ADD15FEADFF8@SJEXCHCCR02.corp.ad.broadcom.com>
On Tue, Oct 25, 2011 at 4:28 AM, Bingfeng Mei <bmei@broadcom.com> wrote:
> Thanks, Andrew. I also implemented a quick patch on our port (based on GCC 4.5).
> I noticed it produced better code now for our applications. Maybe eliminating
> control flow in earlier stage helps other optimizing passes. Currently, tree
> if-conversion pass is not turned on by default (only with tree vectorization
> or some other passes). Maybe it is worth to make it default at -O2 (for those
> processors support conditional move)?
I just committed the patch which does the expansion of COND_EXPR to
condmov to the trunk. I have more patches which do what ifcvt does
but in phiopt (which seems better in general as ifcvt work only over
loops). I hope to post those patches in the coming weeks.
Thanks,
Andrew Pinski
>
> Cheers,
> Bingfeng
>
>> -----Original Message-----
>> From: Andrew Pinski [mailto:pinskia@gmail.com]
>> Sent: 24 October 2011 17:20
>> To: Richard Guenther
>> Cc: Bingfeng Mei; gcc@gcc.gnu.org
>> Subject: Re: Why doesn't GCC generate conditional move for COND_EXPR?
>>
>> On Mon, Oct 24, 2011 at 7:00 AM, Richard Guenther
>> <richard.guenther@gmail.com> wrote:
>> > On Mon, Oct 24, 2011 at 2:55 PM, Bingfeng Mei <bmei@broadcom.com>
>> wrote:
>> >> Hello,
>> >> I noticed that COND_EXPR is not expanded to conditional move
>> >> as MIN_EXPR/MAX_EXPR are (assuming movmodecc is available).
>> >> I wonder why not?
>> >>
>> >> I have some loop that fails tree vectorization, but still contains
>> >> COND_EXPR from tree ifcvt pass. In the end, the generated code
>> >> is worse than if I don't turned -ftree-vectorize on. This
>> >> is on our private port.
>> >
>> > Because nobody touched COND_EXPR expansion since ages.
>>
>> I have a patch which I will be submitting next week or so that does
>> this expansion correctly. In fact I have a few patches which improves
>> the generation of COND_EXPR in simple cases (in PHI-OPT).
>>
>> Thanks,
>> Andrew Pinski
>
prev parent reply other threads:[~2012-05-04 21:26 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-24 14:45 Bingfeng Mei
2011-10-24 16:19 ` Richard Guenther
2011-10-25 3:12 ` Andrew Pinski
2011-10-25 14:10 ` Bingfeng Mei
2012-05-04 21:26 ` Andrew Pinski [this message]
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