help build mpich with gcc6

[Steve Kargl]

On Tue, Feb 21, 2017 at 10:15:42AM -0800, Anton Shterenlikht wrote:
> >From mexas Tue Feb 21 15:00:10 2017
> >To: freebsd-ports at freebsd.org
> >Subject: help build mpich with gcc6
> >Reply-To: mexas at bris.ac.uk
> >
> >I added
> >
> >USE_GCC=        6+
> >
> >to net/mpich/Makefile
> >
> >but it seems this affected only the C and C++ parts:
> >
> >$ mpichversion
> >*skip*
> >
> >MPICH CC:       gcc6  -O2 -pipe  -fstack-protector -Wl,-rpath=/usr/local/lib/gcc6 -fno-strict-aliasing 
> >MPICH CXX:      g++6  -O2 -pipe -fstack-protector -Wl,-rpath=/usr/local/lib/gcc6 -fno-strict-aliasing  -Wl,-rpath=/usr/local/lib/gcc6
> >MPICH F77:      gfortran49  -O -Wl,-rpath=/usr/local/lib/gcc49
> >MPICH FC:       gfortran49  -Wl,-rpath=/usr/local/lib/gcc49
> >
> >The Fortran parts remained at lang/gcc level.
> >
> >What settings shall I use to make Fortran components
> >built with gfortran6 instead?
> >
> 
> I moved one step further.
> With
> 
> DEFAULT_VERSIONS=gcc=6
> 
> in /etc/make.conf
> 
> I get:
> 
> MPICH CC:       cc  -O2 -pipe  -fstack-protector -fno-strict-aliasing 
> MPICH CXX:      c++  -O2 -pipe -fstack-protector -fno-strict-aliasing 
> MPICH F77:      gfortran6  -O -Wl,-rpath=/usr/local/lib/gcc6
> MPICH FC:       gfortran6  -Wl,-rpath=/usr/local/lib/gcc6
> 

That's what I use along with

FFLAGS+= -O2 -pipe -march=bdver2 -mtune=bdver2
FFLAGS+= -funroll-loops --param max-unroll-times=4 -ftree-vectorize

in /etc/make.conf.  You'll, of course, want to set -march
and -mtune to your hardware or set them to native.

-- 
Steve
20161221 https://www.youtube.com/watch?v=IbCHE-hONow