http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53342
Bug #: 53342 Summary: [4.8 Regression] rnflow.f90 is ~5% slower after revision 187340 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: m...@gcc.gnu.org, rgue...@gcc.gnu.org, ubiz...@gmail.com Created attachment 27401 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27401 source evlrnf.f90 extracted from rnflow.f90 On x86_64-apple-darwin10, rnflow.f90 is ~5% slower after revision 187340 [macbook] test/dbg_rnflow% /opt/gcc/gcc4.8p-187339/bin/gfortran -O3 -ffast-math -funroll-loops rnflow.f90 [macbook] test/dbg_rnflow% time a.out > /dev/null 27.542u 0.348s 0:27.93 99.8% 0+0k 0+0io 0pf+0w [macbook] test/dbg_rnflow% /opt/gcc/gcc4.8p-187340/bin/gfortran -O3 -ffast-math -funroll-loops rnflow.f90 [macbook] test/dbg_rnflow% time a.out > /dev/null 29.196u 0.348s 0:29.59 99.7% 0+0k 0+0io 0pf+0w The slowdown comes from the optimization of evlrnf (compiled on top of the last last set in pr53340#c1) [macbook] test/dbg_rnflow% /opt/gcc/gcc4.8p-187339/bin/gfortran -c -O3 -ffast-math -funroll-loops evlrnf.f90 [macbook] test/dbg_rnflow% makeo ; time a.out > /dev/null 21.168u 0.348s 0:21.52 99.9% 0+0k 0+0io 0pf+0w [macbook] test/dbg_rnflow% /opt/gcc/gcc4.8p-187340/bin/gfortran -c -O3 -ffast-math -funroll-loops evlrnf.f90 [macbook] test/dbg_rnflow% makeo ; time a.out > /dev/null 22.758u 0.347s 0:23.11 99.9% 0+0k 0+0io 0pf+0w