From: Xinliang David Li <davidxl@google.com>
To: Andrew Pinski <pinskia@gmail.com>
Cc: Corey Kasten <corey@materialintelligencellc.com>,
Richard Guenther <richard.guenther@gmail.com>,
Nathan Froyd <froydnj@codesourcery.com>,
gcc@gcc.gnu.org
Subject: Re: Better performance on older version of GCC
Date: Sat, 28 Aug 2010 10:08:00 -0000 [thread overview]
Message-ID: <AANLkTi=J1WrBTAic1xNbsVP1t8KY5FoH8EDNJ=GEFVLA@mail.gmail.com> (raw)
In-Reply-To: <AANLkTi=0RPCq1AO-wsp6MLDNM8atN-ekd5sn4VW=FxM0@mail.gmail.com>
Right -- I missed Richard's previous email regarding the options.
Thanks,
David
On Fri, Aug 27, 2010 at 5:21 PM, Andrew Pinski <pinskia@gmail.com> wrote:
> On Fri, Aug 27, 2010 at 5:12 PM, Xinliang David Li <davidxl@google.com> wrote:
>> Briefly looked at it -- the trunk gcc also regresses a lot compared to
>> the binary you attached. (To match your binary, also added
>> -mfpmath=387 -m32 options)
>>
>> Two problems:
>>
>> 1) more register spills in the trunk version -- the old compiler seems
>> more effective in using fp stack registers;
>> 2) the complex multiplication -- the old version emits inline sequence
>> while the trunk version emits call to _muld3c intrinsinc.
>
> Neither of these seems like real bug reportable ones. The first one
> is that due to -fexcess-precision=standard being default in 4.5 and
> above (see PR 323). The second one is due to -fcx-limited-range not
> being default any more (I cannot remember the bug number which changed
> that though).
>
> Thanks,
> Andrew Pinski
>
prev parent reply other threads:[~2010-08-28 1:06 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-27 13:50 Corey Kasten
2010-08-27 14:20 ` H.J. Lu
2010-08-27 14:23 ` Nathan Froyd
2010-08-27 15:03 ` Corey Kasten
2010-08-27 15:40 ` Richard Guenther
2010-08-27 16:29 ` Corey Kasten
2010-08-28 1:06 ` Xinliang David Li
2010-08-28 8:23 ` Andrew Pinski
2010-08-28 10:08 ` Xinliang David Li [this message]
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