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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/53967] GCC produces slow code for convolution algorithm with -mfpmath=sse (the AMD_64 default)
Date: Mon, 16 Jul 2012 14:57:00 -0000 [thread overview]
Message-ID: <bug-53967-4-mdvtLt73nl@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-53967-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53967
--- Comment #9 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-07-16 14:56:59 UTC ---
(In reply to comment #8)
> I used -march=native in this case. It is interesting that this enabled AVX
> (this particular CPU does support it).
>
> To be clear, the problem also occurs with
>
> -m64 -mtune=generic -march=x86-64 -mfpmath=sse
>
> vs
>
> -m64 -mtune=generic -march=x86-64 -mfpmath=387
>
> and is also observed on a 5-year old Opteron.
>
> With GCC 4.7.1, and for a specific application benchmark case and with generic
> architecture and tuning, -mfpmath=387 produces 0.133 iter/s and -mfpmath=sse
> produces 0.047 iter/s. A different (non-GCC) compiler on the same system
> produces 0.155 iter/s.
>
> In the course of testing, I have indeed tried -march=corei7 and it did not
> provide an improvement.
What kind of optimization options are you using? -O3? Or are you really
using -O0 (aka nothing)?
next prev parent reply other threads:[~2012-07-16 14:57 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-14 20:52 [Bug c/53967] New: " bfriesen at simple dot dallas.tx.us
2012-07-14 20:56 ` [Bug c/53967] " bfriesen at simple dot dallas.tx.us
2012-07-14 20:57 ` bfriesen at simple dot dallas.tx.us
2012-07-14 20:58 ` bfriesen at simple dot dallas.tx.us
2012-07-14 20:59 ` bfriesen at simple dot dallas.tx.us
2012-07-14 21:06 ` [Bug target/53967] " bfriesen at simple dot dallas.tx.us
2012-07-14 21:42 ` bfriesen at simple dot dallas.tx.us
2012-07-16 12:42 ` rguenth at gcc dot gnu.org
2012-07-16 14:17 ` bfriesen at simple dot dallas.tx.us
2012-07-16 14:57 ` rguenth at gcc dot gnu.org [this message]
2012-07-16 15:35 ` bfriesen at simple dot dallas.tx.us
2012-07-16 15:41 ` bfriesen at simple dot dallas.tx.us
2012-07-17 9:20 ` rguenth at gcc dot gnu.org
2012-07-18 9:45 ` evstupac at gmail dot com
2012-07-18 10:50 ` rguenth at gcc dot gnu.org
2012-07-18 14:28 ` bfriesen at simple dot dallas.tx.us
2012-07-18 20:42 ` bfriesen at simple dot dallas.tx.us
2012-07-19 14:29 ` bfriesen at simple dot dallas.tx.us
2012-07-21 1:05 ` bfriesen at simple dot dallas.tx.us
2012-08-12 15:41 ` xunxun1982 at gmail dot com
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