http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59487
Bug ID: 59487
Summary: [4.9 Regression] When compiled with -fwhole-program
rnflow.f90 runs up to 40% slower after r202826
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: dominiq at lps dot ens.fr
CC: burnus at gcc dot gnu.org, Ganesh.Gopalasubramanian at amd
dot com,
rguenth at gcc dot gnu.org
When compiled with -fwhole-program rnflow.f90 runs up to 40% slower after
r202826 (Core i7 at 2.8Ghz):
[Book15] lin/test% /opt/gcc/gcc4.9p-202828/bin/gfortran -Ofast -fwhole-program
rnflow.f90
[Book15] lin/test% time a.out > /dev/null
18.244u 0.020s 0:18.26 100.0% 0+0k 3+1io 0pf+0w
[Book15] lin/test% /opt/gcc/gcc4.9p-202825/bin/gfortran -Ofast -fwhole-program
rnflow.f90
[Book15] lin/test% time a.out > /dev/null
13.022u 0.024s 0:13.04 100.0% 0+0k 4+1io 0pf+0w
[Book15] lin/test% gfcc -Ofast -fwhole-program rnflow.f90
[Book15] lin/test% time a.out > /dev/null
18.533u 0.036s 0:18.58 99.8% 0+0k 0+0io 45pf+0w
[Book15] lin/test% gfcc -Ofast rnflow.f90
[Book15] lin/test% time a.out > /dev/null
13.059u 0.020s 0:13.08 99.9% 0+0k 0+0io 0pf+0w
[Book15] lin/test% gfc -Ofast -fwhole-program rnflow.f90
[Book15] lin/test% time a.out > /dev/null
12.940u 0.028s 0:12.97 99.9% 0+0k 0+0io 14pf+0w
gfcc is r205891 and gfc r205924 with the patch for pr58721 at
http://gcc.gnu.org/ml/fortran/2013-12/msg00069.html which fixes also this
slowdown (the slowdown is ~20% on a Core2Duo at 2.5Ghz). This has been noticed
in the last comment of pr58464.
