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* [Bug rtl-optimization/52576] New: fib.c (attached) is slower on current (4.8.0) than 4.6.x
@ 2012-03-13 6:34 cw at f00f dot org
2012-11-19 12:49 ` [Bug rtl-optimization/52576] " jakub at gcc dot gnu.org
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: cw at f00f dot org @ 2012-03-13 6:34 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52576
Bug #: 52576
Summary: fib.c (attached) is slower on current (4.8.0) than
4.6.x
Classification: Unclassified
Product: gcc
Version: 4.8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: cw@f00f.org
The following is found to be slower using gcc 4.8.0 (svn head) compared to gcc
4.6.2 (Debian provided gcc).
gcc version 4.6.2 (Debian 4.6.2-12) 0m24.395s
gcc version 4.8.0 20120309 (experimental) (GCC) 0m29.159s
The results are quite repeatable. The generated code is different (gcc -O3 -c,
objdump -d, diff)
Built using:
gcc -Wall -c -O3 fib.c
---------------
#include <stdio.h>
unsigned int fib(unsigned int n)
{
if (n < 2)
return n;
return fib(n-2) + fib(n-1);
}
int main()
{
printf("%d\n", fib(48));
return 0;
}
---------------
(48 was chosen to show the different in performance but also run in a tolerable
about of time)
Testing various options didn't close the gap, with only a slight improvement
from -mtune=opteron with is unexpected as these are Intel Westmere systems.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug rtl-optimization/52576] fib.c (attached) is slower on current (4.8.0) than 4.6.x
2012-03-13 6:34 [Bug rtl-optimization/52576] New: fib.c (attached) is slower on current (4.8.0) than 4.6.x cw at f00f dot org
@ 2012-11-19 12:49 ` jakub at gcc dot gnu.org
2013-02-08 15:41 ` [Bug rtl-optimization/52576] [4.7 Regression] fib.c (attached) is slower on 4.7.x " rguenth at gcc dot gnu.org
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: jakub at gcc dot gnu.org @ 2012-11-19 12:49 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52576
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2012-11-19
CC| |jakub at gcc dot gnu.org
Ever Confirmed|0 |1
--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-11-19 12:49:07 UTC ---
Seems this has regressed (at least for -O3 -m64 -mtune=generic on SandyBridge
CPU) with http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=179284 and improved
again (in fact, seems to be faster than before) with LRA merge
http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=192719 . So, can we mark this
as fixed for 4.8?
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug rtl-optimization/52576] [4.7 Regression] fib.c (attached) is slower on 4.7.x than 4.6.x
2012-03-13 6:34 [Bug rtl-optimization/52576] New: fib.c (attached) is slower on current (4.8.0) than 4.6.x cw at f00f dot org
2012-11-19 12:49 ` [Bug rtl-optimization/52576] " jakub at gcc dot gnu.org
@ 2013-02-08 15:41 ` rguenth at gcc dot gnu.org
2013-04-03 9:43 ` rguenth at gcc dot gnu.org
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: rguenth at gcc dot gnu.org @ 2013-02-08 15:41 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52576
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Known to work| |4.6.3, 4.8.0
Target Milestone|--- |4.7.3
Summary|fib.c (attached) is slower |[4.7 Regression] fib.c
|on current (4.8.0) than |(attached) is slower on
|4.6.x |4.7.x than 4.6.x
Known to fail| |4.7.2
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug rtl-optimization/52576] [4.7 Regression] fib.c (attached) is slower on 4.7.x than 4.6.x
2012-03-13 6:34 [Bug rtl-optimization/52576] New: fib.c (attached) is slower on current (4.8.0) than 4.6.x cw at f00f dot org
2012-11-19 12:49 ` [Bug rtl-optimization/52576] " jakub at gcc dot gnu.org
2013-02-08 15:41 ` [Bug rtl-optimization/52576] [4.7 Regression] fib.c (attached) is slower on 4.7.x " rguenth at gcc dot gnu.org
@ 2013-04-03 9:43 ` rguenth at gcc dot gnu.org
2013-04-11 7:59 ` rguenth at gcc dot gnu.org
2014-06-12 13:06 ` rguenth at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: rguenth at gcc dot gnu.org @ 2013-04-03 9:43 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52576
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Priority|P3 |P2
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug rtl-optimization/52576] [4.7 Regression] fib.c (attached) is slower on 4.7.x than 4.6.x
2012-03-13 6:34 [Bug rtl-optimization/52576] New: fib.c (attached) is slower on current (4.8.0) than 4.6.x cw at f00f dot org
` (2 preceding siblings ...)
2013-04-03 9:43 ` rguenth at gcc dot gnu.org
@ 2013-04-11 7:59 ` rguenth at gcc dot gnu.org
2014-06-12 13:06 ` rguenth at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: rguenth at gcc dot gnu.org @ 2013-04-11 7:59 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52576
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|4.7.3 |4.7.4
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> 2013-04-11 07:59:21 UTC ---
GCC 4.7.3 is being released, adjusting target milestone.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug rtl-optimization/52576] [4.7 Regression] fib.c (attached) is slower on 4.7.x than 4.6.x
2012-03-13 6:34 [Bug rtl-optimization/52576] New: fib.c (attached) is slower on current (4.8.0) than 4.6.x cw at f00f dot org
` (3 preceding siblings ...)
2013-04-11 7:59 ` rguenth at gcc dot gnu.org
@ 2014-06-12 13:06 ` rguenth at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: rguenth at gcc dot gnu.org @ 2014-06-12 13:06 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52576
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution|--- |FIXED
Target Milestone|4.7.4 |4.8.0
Known to fail| |4.7.4
--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed for 4.8.0.
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2014-06-12 13:06 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2012-03-13 6:34 [Bug rtl-optimization/52576] New: fib.c (attached) is slower on current (4.8.0) than 4.6.x cw at f00f dot org
2012-11-19 12:49 ` [Bug rtl-optimization/52576] " jakub at gcc dot gnu.org
2013-02-08 15:41 ` [Bug rtl-optimization/52576] [4.7 Regression] fib.c (attached) is slower on 4.7.x " rguenth at gcc dot gnu.org
2013-04-03 9:43 ` rguenth at gcc dot gnu.org
2013-04-11 7:59 ` rguenth at gcc dot gnu.org
2014-06-12 13:06 ` rguenth at gcc dot gnu.org
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