This is the mail archive of the
gcc-bugs@gcc.gnu.org
mailing list for the GCC project.
[Bug lto/45810] 40% slowdown when using LTO for a single-file program
- From: "dominiq at lps dot ens.fr" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Wed, 16 Feb 2011 18:38:36 +0000
- Subject: [Bug lto/45810] 40% slowdown when using LTO for a single-file program
- Auto-submitted: auto-generated
- References: <bug-45810-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45810
--- Comment #25 from Dominique d'Humieres <dominiq at lps dot ens.fr> 2011-02-16 18:38:19 UTC ---
AFAICT the patch in http://gcc.gnu.org/ml/gcc-patches/2011-02/msg00973.html
seems to fix most of the fatigue.f90 problems:
At revision 170178 without the patch, I get
[macbook] lin/test% gfcp -Ofast fatigue.f90
[macbook] lin/test% time a.out > /dev/null
8.903u 0.005s 0:08.91 99.8% 0+0k 0+2io 0pf+0w
[macbook] lin/test% gfcp -Ofast -fwhole-program fatigue.f90
[macbook] lin/test% time a.out > /dev/null
6.392u 0.002s 0:06.39 100.0% 0+0k 0+0io 0pf+0w
[macbook] lin/test% gfcp -Ofast -finline-limit=322 -fwhole-program fatigue.f90
[macbook] lin/test% time a.out > /dev/null
4.653u 0.002s 0:04.65 100.0% 0+0k 0+1io 0pf+0w
[macbook] lin/test% gfcp -Ofast -finline-limit=322 -fwhole-program -flto
fatigue.f90
[macbook] lin/test% time a.out > /dev/null
8.212u 0.004s 0:08.22 99.8% 0+0k 0+2io 0pf+0w
[macbook] lin/test% gfcp -Ofast -finline-limit=322 --param
large-function-growth=132 -fwhole-program -flto fatigue.f90
[macbook] lin/test% time a.out > /dev/null
4.526u 0.004s 0:04.53 99.7% 0+0k 0+1io 0pf+0w
At revision 170212 with the patch, I get
[macbook] lin/test% gfc -Ofast fatigue.f90
[macbook] lin/test% time a.out > /dev/null
4.628u 0.002s 0:04.63 99.7% 0+0k 0+0io 0pf+0w
[macbook] lin/test% gfc -Ofast -fwhole-program fatigue.f90
[macbook] lin/test% time a.out > /dev/null
4.654u 0.002s 0:04.65 100.0% 0+0k 0+1io 0pf+0w
[macbook] lin/test% gfc -Ofast -finline-limit=322 -fwhole-program fatigue.f90
[macbook] lin/test% time a.out > /dev/null
4.657u 0.002s 0:04.66 99.7% 0+0k 0+1io 0pf+0w
[macbook] lin/test% gfc -Ofast -finline-limit=322 -fwhole-program -flto
fatigue.f90
[macbook] lin/test% time a.out > /dev/null
4.715u 0.003s 0:04.72 99.7% 0+0k 0+1io 0pf+0w
[macbook] lin/test% gfc -Ofast -finline-limit=322 --param
large-function-growth=132 -fwhole-program -flto fatigue.f90
[macbook] lin/test% time a.out > /dev/null
4.713u 0.003s 0:04.71 100.0% 0+0k 0+1io 0pf+0w
[macbook] lin/test% gfc -Ofast -finline-limit=322 --param
large-function-growth=137 -fwhole-program -flto fatigue.f90
[macbook] lin/test% time a.out > /dev/null
4.524u 0.003s 0:04.52 100.0% 0+0k 0+1io 0pf+0w
[macbook] lin/test% gfc -Ofast --param large-function-growth=137
-fwhole-program -flto fatigue.f90
[macbook] lin/test% time a.out > /dev/null
4.564u 0.003s 0:04.57 99.7% 0+0k 0+1io 0pf+0w
[macbook] lin/test% gfc -Ofast --param large-function-growth=137
-fwhole-program fatigue.f90
[macbook] lin/test% time a.out > /dev/null
4.479u 0.003s 0:04.48 99.7% 0+0k 0+2io 0pf+0w
A quick check of the other tests does not show any obvious slowdown with the
patch.