http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55585
--- Comment #4 from Joost VandeVondele <Joost.VandeVondele at mat dot ethz.ch> 2012-12-04 10:43:10 UTC --- Interestingly, the magic switch is -fstrict-aliasing... 20x speedup. for a Fortran code quite a surprise. > time gfortran -c -O1 -fbounds-check -g -fstrict-aliasing slow.f90 real 0m11.483s I think for Fortran -fstrict-aliasing could well be the default at -O1, but maybe there is an underlying reason why this flag is needed ?
