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* [Bug fortran/31139] sum(w_re(1:nn,1)*fi(i(1:nn, ii))) up to 3.5x slower than C version
[not found] <bug-31139-4@http.gcc.gnu.org/bugzilla/>
@ 2013-06-22 16:55 ` dominiq at lps dot ens.fr
2015-10-10 9:21 ` dominiq at lps dot ens.fr
1 sibling, 0 replies; 10+ messages in thread
From: dominiq at lps dot ens.fr @ 2013-06-22 16:55 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31139
Dominique d'Humieres <dominiq at lps dot ens.fr> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |WAITING
--- Comment #8 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
> I have not tested this with latest trunk, but I wonder if any of the recent
> optimization work has improved this. Can it be closed yet?
A quick test on a 2.5Ghz Core2Duo at revision 200321 with -Ofast shows
Fortran: 0.330040932
c_sse: 0.225150943
c_struct: 0.227035046
and with -Ofast -funroll-loops
Fortran: 0.213014960
c_sse: 0.223238945
c_struct: 0.209081888
The change occured between 4.5 and 4.6 (note that 4.6 and 4.7 gives 0.263675928
without -funroll-loops). Is this still an issue?
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug fortran/31139] sum(w_re(1:nn,1)*fi(i(1:nn, ii))) up to 3.5x slower than C version
[not found] <bug-31139-4@http.gcc.gnu.org/bugzilla/>
2013-06-22 16:55 ` [Bug fortran/31139] sum(w_re(1:nn,1)*fi(i(1:nn, ii))) up to 3.5x slower than C version dominiq at lps dot ens.fr
@ 2015-10-10 9:21 ` dominiq at lps dot ens.fr
1 sibling, 0 replies; 10+ messages in thread
From: dominiq at lps dot ens.fr @ 2015-10-10 9:21 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=31139
Dominique d'Humieres <dominiq at lps dot ens.fr> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|WAITING |RESOLVED
Resolution|--- |FIXED
--- Comment #9 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
> The change occured between 4.5 and 4.6 (note that 4.6 and 4.7 gives
> 0.263675928 without -funroll-loops). Is this still an issue?
No feedback for over two years. Closing as FIXED.
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug fortran/31139] sum(w_re(1:nn,1)*fi(i(1:nn, ii))) up to 3.5x slower than C version
2007-03-11 22:38 [Bug fortran/31139] New: " burnus at gcc dot gnu dot org
` (6 preceding siblings ...)
2007-04-18 5:56 ` fxcoudert at gcc dot gnu dot org
@ 2010-09-12 15:45 ` jvdelisle at gcc dot gnu dot org
7 siblings, 0 replies; 10+ messages in thread
From: jvdelisle at gcc dot gnu dot org @ 2010-09-12 15:45 UTC (permalink / raw)
To: gcc-bugs
------- Comment #7 from jvdelisle at gcc dot gnu dot org 2010-09-12 15:45 -------
I have not tested this with latest trunk, but I wonder if any of the recent
optimization work has improved this. Can it be closed yet?
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31139
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug fortran/31139] sum(w_re(1:nn,1)*fi(i(1:nn, ii))) up to 3.5x slower than C version
2007-03-11 22:38 [Bug fortran/31139] New: " burnus at gcc dot gnu dot org
` (5 preceding siblings ...)
2007-03-12 8:16 ` burnus at gcc dot gnu dot org
@ 2007-04-18 5:56 ` fxcoudert at gcc dot gnu dot org
2010-09-12 15:45 ` jvdelisle at gcc dot gnu dot org
7 siblings, 0 replies; 10+ messages in thread
From: fxcoudert at gcc dot gnu dot org @ 2007-04-18 5:56 UTC (permalink / raw)
To: gcc-bugs
--
fxcoudert at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Ever Confirmed|0 |1
Last reconfirmed|0000-00-00 00:00:00 |2007-04-18 06:56:03
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31139
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug fortran/31139] sum(w_re(1:nn,1)*fi(i(1:nn, ii))) up to 3.5x slower than C version
2007-03-11 22:38 [Bug fortran/31139] New: " burnus at gcc dot gnu dot org
` (4 preceding siblings ...)
2007-03-12 7:58 ` burnus at gcc dot gnu dot org
@ 2007-03-12 8:16 ` burnus at gcc dot gnu dot org
2007-04-18 5:56 ` fxcoudert at gcc dot gnu dot org
2010-09-12 15:45 ` jvdelisle at gcc dot gnu dot org
7 siblings, 0 replies; 10+ messages in thread
From: burnus at gcc dot gnu dot org @ 2007-03-12 8:16 UTC (permalink / raw)
To: gcc-bugs
------- Comment #6 from burnus at gcc dot gnu dot org 2007-03-12 08:16 -------
> Can someone try instead of doing "__real__ a += w[j] *__real__ mfi[*index];"
> Use "a+= xxx* yyy" and also use -std=c99 to get the correct multiplication?
Well, -std=c99 was used already and the "real(!) * complex" calculation was
already correct. "c_cmplx" below uses now:
a += w[j ] * mfi[*index++];
Compiled with:
gcc -std=c99 -O3 -funroll-loops -ftree-vectorize -march=opteron -msse3
-ffast-math -m64
gfortran -O3 -funroll-loops -ftree-vectorize -march=opteron -msse3 -ffast-math
-m64
Fortran: 0.4360271
Fortran: 0.4280267
c_nosse: 0.2440166
c_nosse: 0.2320151
c_sse: 0.2320137
c_sse: 0.2400150
c_struct: 0.2320151
c_struct: 0.2320147
c_cmplx: 0.2360163
c_cmplx: 0.2320147
And using a non-manually unrolled version: 0.3760242, 0.3760242
for(i = 0; i < np ; i++) {
for(j = 1; j < n; j++)
a += w[j ] * mfi[*index++];
fo[i] = a;
}
Thus the unrolling seems to do most of the speed up. With -funroll-all-loops,
the timings of fortran an the non-unrolled version remain the same.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31139
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug fortran/31139] sum(w_re(1:nn,1)*fi(i(1:nn, ii))) up to 3.5x slower than C version
2007-03-11 22:38 [Bug fortran/31139] New: " burnus at gcc dot gnu dot org
` (3 preceding siblings ...)
2007-03-12 5:38 ` pinskia at gcc dot gnu dot org
@ 2007-03-12 7:58 ` burnus at gcc dot gnu dot org
2007-03-12 8:16 ` burnus at gcc dot gnu dot org
` (2 subsequent siblings)
7 siblings, 0 replies; 10+ messages in thread
From: burnus at gcc dot gnu dot org @ 2007-03-12 7:58 UTC (permalink / raw)
To: gcc-bugs
------- Comment #5 from burnus at gcc dot gnu dot org 2007-03-12 07:58 -------
> complex * complex is not a simple cross product in FP world.
Well, the program calculates: real * complex
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31139
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug fortran/31139] sum(w_re(1:nn,1)*fi(i(1:nn, ii))) up to 3.5x slower than C version
2007-03-11 22:38 [Bug fortran/31139] New: " burnus at gcc dot gnu dot org
` (2 preceding siblings ...)
2007-03-12 5:33 ` pinskia at gcc dot gnu dot org
@ 2007-03-12 5:38 ` pinskia at gcc dot gnu dot org
2007-03-12 7:58 ` burnus at gcc dot gnu dot org
` (3 subsequent siblings)
7 siblings, 0 replies; 10+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2007-03-12 5:38 UTC (permalink / raw)
To: gcc-bugs
------- Comment #4 from pinskia at gcc dot gnu dot org 2007-03-12 05:37 -------
> The hand-made SSE version (USE_VECTORS) crashes here for -m32
Because well complex(8)'s alignment is the same as double which means it is
only 8 byte aligned and not 16 byte aligned, it is just magical that the SSE
case works for -m64 also.
I am thinking about declaring this bug as invalid as right now the C testcase
is not even closely related to the Fortran case.
Can someone try instead of doing "__real__ a += w[j ] * __real__ mfi[*index
];" Use "a+= xxx* yyy" and also use -std=c99 to get the correct multiplication?
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31139
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug fortran/31139] sum(w_re(1:nn,1)*fi(i(1:nn, ii))) up to 3.5x slower than C version
2007-03-11 22:38 [Bug fortran/31139] New: " burnus at gcc dot gnu dot org
2007-03-11 22:45 ` [Bug fortran/31139] " burnus at gcc dot gnu dot org
2007-03-11 22:50 ` burnus at gcc dot gnu dot org
@ 2007-03-12 5:33 ` pinskia at gcc dot gnu dot org
2007-03-12 5:38 ` pinskia at gcc dot gnu dot org
` (4 subsequent siblings)
7 siblings, 0 replies; 10+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2007-03-12 5:33 UTC (permalink / raw)
To: gcc-bugs
------- Comment #3 from pinskia at gcc dot gnu dot org 2007-03-12 05:33 -------
The problem here is obvious, in the Fortran case, there is a temp array being
created while in the C case, there is not. Also in the optimized C case, the
multiplication of the complex numbers is incorrect unless you add -ffast-math.
Actually I think in both C cases it is incorrect. Can someone try with
-ffast-math for both the C and Fortran cases?
complex * complex is not a simple cross product in FP world.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31139
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug fortran/31139] sum(w_re(1:nn,1)*fi(i(1:nn, ii))) up to 3.5x slower than C version
2007-03-11 22:38 [Bug fortran/31139] New: " burnus at gcc dot gnu dot org
2007-03-11 22:45 ` [Bug fortran/31139] " burnus at gcc dot gnu dot org
@ 2007-03-11 22:50 ` burnus at gcc dot gnu dot org
2007-03-12 5:33 ` pinskia at gcc dot gnu dot org
` (5 subsequent siblings)
7 siblings, 0 replies; 10+ messages in thread
From: burnus at gcc dot gnu dot org @ 2007-03-11 22:50 UTC (permalink / raw)
To: gcc-bugs
------- Comment #2 from burnus at gcc dot gnu dot org 2007-03-11 22:50 -------
Created an attachment (id=13191)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=13191&action=view)
test.tar.gz
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31139
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug fortran/31139] sum(w_re(1:nn,1)*fi(i(1:nn, ii))) up to 3.5x slower than C version
2007-03-11 22:38 [Bug fortran/31139] New: " burnus at gcc dot gnu dot org
@ 2007-03-11 22:45 ` burnus at gcc dot gnu dot org
2007-03-11 22:50 ` burnus at gcc dot gnu dot org
` (6 subsequent siblings)
7 siblings, 0 replies; 10+ messages in thread
From: burnus at gcc dot gnu dot org @ 2007-03-11 22:45 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from burnus at gcc dot gnu dot org 2007-03-11 22:45 -------
Contains the test case. The hand-made SSE version (USE_VECTORS) crashes here
for -m32, but as it is C vs. Fortran, one can completely ignore that test case
(for -m64 USE_VECTORS is about as fast as the other C versions anyhow).
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31139
^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~2015-10-10 9:21 UTC | newest]
Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
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[not found] <bug-31139-4@http.gcc.gnu.org/bugzilla/>
2013-06-22 16:55 ` [Bug fortran/31139] sum(w_re(1:nn,1)*fi(i(1:nn, ii))) up to 3.5x slower than C version dominiq at lps dot ens.fr
2015-10-10 9:21 ` dominiq at lps dot ens.fr
2007-03-11 22:38 [Bug fortran/31139] New: " burnus at gcc dot gnu dot org
2007-03-11 22:45 ` [Bug fortran/31139] " burnus at gcc dot gnu dot org
2007-03-11 22:50 ` burnus at gcc dot gnu dot org
2007-03-12 5:33 ` pinskia at gcc dot gnu dot org
2007-03-12 5:38 ` pinskia at gcc dot gnu dot org
2007-03-12 7:58 ` burnus at gcc dot gnu dot org
2007-03-12 8:16 ` burnus at gcc dot gnu dot org
2007-04-18 5:56 ` fxcoudert at gcc dot gnu dot org
2010-09-12 15:45 ` jvdelisle at gcc dot gnu dot org
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