From: Colin Paul Gloster <Colin_Paul_Gloster@ACM.org>
Subject: Re: compiler settings in AdaGIDE
Date: Tue, 27 Jul 2010 16:11:12 +0100
Date: 2010-07-27T16:11:12+01:00 [thread overview]
Message-ID: <alpine.LRH.2.00.1007271606050.27547@64bit-RedHat-Enterprise-Linux6beta> (raw)
In-Reply-To: <e715e179-6053-4190-94d4-6a348f9ea635@q22g2000yqm.googlegroups.com>
On Sat, 24 Jul 2010, Jonathan sent:
|----------------------------------------------------------------------|
|"[..] |
| |
| time ./bench |
| |
|Let's look at the best results first, and compare the |
|'09 and '10 GNAT GPL compilers: |
| |
| 2010 GNAT GPL: |
| gnatmake bench.adb -gnatnp -O2 -march=native -ffast-math -funroll- |
|loops |
| 3.61 seconds |
| |
| 2009 GNAT GPL: |
| gnatmake bench.adb -gnatnp -O2 -march=native -ffast-math -funroll- |
|loops |
| 4.57 seconds |
| |
|This came as a nice surprise to me! |
|We can learn some more about the compiler switches by |
|toggling them. I'll stick to the 2010 GNAT GPL from now on: |
| |
| change -O2 to -O3: |
| (gnatmake bench.adb -gnatnp -O3 -march=native -ffast-math -funroll-|
|loops) |
| running time changes from 3.61 to 3.63 seconds |
| |
| remove -funroll-loops: |
| (gnatmake bench.adb -gnatnp -O2 -march=native -ffast-math) |
| running time changes from 3.61 to 3.66 seconds |
| |
| remove -ffast-math: |
| (gnatmake bench.adb -gnatnp -O2 -march=native) |
| running time changes from 3.61 to 4.35 seconds |
| |
|The -ffast-math had an amazing affect. I've never seen that |
|before ... maybe an interaction with complex number arithmetic. |
| |
|[..]" |
|----------------------------------------------------------------------|
The GNU Compiler Collection's -ffast-math switch used to provide a
significant increase in speed for various frontends excluding GNAT. In
my experience at least, this effect had no special relationship with
complex numbers.
next prev parent reply other threads:[~2010-07-27 15:11 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-23 9:52 compiler settings in AdaGIDE Ada novice
2010-07-23 11:56 ` Gautier write-only
2010-07-23 14:23 ` Ada novice
[not found] ` <f72678ba-23ce-4c9a-b17e-b33fbd45300d@l14g2000yql.googlegroups.com>
2010-07-23 14:54 ` Georg Bauhaus
2010-07-23 15:16 ` Robert A Duff
2010-07-23 15:22 ` Georg Bauhaus
2010-07-23 16:51 ` sjw
2010-07-23 18:03 ` Robert A Duff
2010-07-23 18:27 ` Ada novice
2010-07-23 20:33 ` Simon Wright
2010-07-23 19:31 ` Dmitry A. Kazakov
2010-07-23 21:01 ` Robert A Duff
2010-07-23 22:32 ` Peter C. Chapin
2010-07-24 1:48 ` BrianG
2010-07-23 20:34 ` Simon Wright
2010-07-23 20:52 ` Robert A Duff
2010-07-24 10:30 ` Ada novice
2010-07-24 12:03 ` Robert A Duff
2010-07-24 12:36 ` Ada novice
2010-07-24 18:21 ` jonathan
2010-07-25 13:29 ` Ada novice
2010-07-25 19:30 ` Jeffrey R. Carter
2010-07-26 14:13 ` Ada novice
2010-07-26 15:48 ` sjw
2010-07-26 17:12 ` Dmitry A. Kazakov
2010-07-26 17:18 ` Ada novice
2010-07-25 22:57 ` jonathan
2010-07-26 14:12 ` Ada novice
2010-07-25 23:40 ` jonathan
2010-07-26 8:02 ` Making measurements (Was: compiler settings in AdaGIDE) Jacob Sparre Andersen
2010-07-26 9:57 ` jonathan
2010-07-26 13:50 ` Making measurements Jacob Sparre Andersen
2010-07-27 15:11 ` Colin Paul Gloster [this message]
2010-08-01 16:39 ` compiler settings in AdaGIDE Ada novice
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