http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53340
Bug #: 53340
Summary: [4.8 Regression] rnflow.f90 is ~20% slower after
revision 187092
Classification: Unclassified
Product: gcc
Version: 4.8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: domi...@lps.ens.fr
CC: rgue...@gcc.gnu.org, ubiz...@gmail.com
On x86_64-apple-darwin10, rnflow.f90 is ~20% slower after revision 187092
[macbook] test/dbg_rnflow% /opt/gcc/gcc4.8p-187091/bin/gfortran -O3 -ffast-math
-funroll-loops rnflow.f90
[macbook] test/dbg_rnflow% time a.out > /dev/null
22.038u 0.352s 0:22.52 99.3% 0+0k 2+0io 0pf+0w
[macbook] test/dbg_rnflow% /opt/gcc/gcc4.8p-187092/bin/gfortran -O3 -ffast-math
-funroll-loops rnflow.f90
[macbook] test/dbg_rnflow% time a.out > /dev/null
27.480u 0.349s 0:27.83 99.9% 0+0k 0+0io 0pf+0w
The slowdown comes from the optimization of cptrf2
[macbook] test/dbg_rnflow% /opt/gcc/gcc4.8p-187092/bin/gfortran -c -O3
-ffast-math -funroll-loops timctr.f90 cmpcpt.f90 cptrf2.f90 dger.f90 dgetri.f90
dswap.f90 dtrsm.f90 evlrnf.f90 idamax.f90 main.f90 mattrs.f90 cmpmat.f90
dgemm.f90 dgetf2.f90 dlaswp.f90 dtrmm.f90 dtrti2.f90 extpic.f90 ilaenv.f90
matcnt.f90 reaseq.f90 xerbla.f90 cptrf1.f90 dgemv.f90 dgetrf.f90 dscal.f90
dtrmv.f90 dtrtri.f90 gentrs.f90 lsame.f90 matsim.f90
[macbook] test/dbg_rnflow% makeo ; time a.out > /dev/null27.567u 0.349s 0:27.92
99.9% 0+0k 0+0io 0pf+0w[macbook] test/dbg_rnflow%
/opt/gcc/gcc4.8p-187091/bin/gfortran -c -O3 -ffast-math -funroll-loops
cptrf2.f90
[macbook] test/dbg_rnflow% makeo ; time a.out > /dev/null
22.136u 0.345s 0:22.48 99.9% 0+0k 0+0io 0pf+0w
[macbook] test/dbg_rnflow% /opt/gcc/gcc4.8p-187091/bin/gfortran -c -O2
cptrf2.f90
[macbook] test/dbg_rnflow% makeo ; time a.out > /dev/null
21.453u 0.348s 0:21.80 99.9% 0+0k 0+0io 0pf+0w
