Editing Software Development Platforms (section)

===gcc including gfortran===

gcc is included in XCode, however gfortran is not included, so we have to obtain gcc another way.


====binary installer ====

Get from http://hpc.sourceforge.net .  This is now the recommended method.



====from source====

I really don't recommend installing gcc from source, since it is non-trivial to do so.  Install it with macports if at all possible.  However, if for some reason you are unable to build gcc with macports, these instructions may be useful.

We require the 4.3 or newer gcc series, since it supports some Fortran 2003 features that we need (for cross-language building).  Also, the auto-vectorization of 4.3 is superior to earlier versions.

Installing and building gcc from source is not trivial, but it can be done as follows.  I recommend having a dedicated source-code build directory in your home direectory:

 mkdir -p Documents/source
 cd Documents/source

* Install GMP

 wget ftp://ftp.gnu.org/gnu/gmp/gmp-4.2.4.tar.bz2
 tar xvjf gmp-4.2.4.tar.bz2
 cd gmp-4.2.4
 ./configure ABI=32
 make -j 8
 make check
 sudo make install
 cd ..

NOTE: The -j 8 flag tells make to launch up to 8 building threads when possible.  This is to maximize the use of the 8 cores on the MacPro.

*Install MPFR

 wget http://www.mpfr.org/mpfr-current/mpfr-2.3.2.tar.bz2
 tar xvjf mpfr-2.3.2.tar.bz2
 cd mpfr-2.3.2
 ./configure --with-gmp-build=../source/gmp-4.2.4
 make -j 8
 make check
 sudo make install
 cd ..

*Install gcc

 wget http://gcc-ca.internet.bs/releases/gcc-4.3.2/gcc-4.3.2.tar.bz2
 tar xvjf gcc-4.3.2.tar.bz2
 mkdir build-gcc-4.3.2
 cd build-gcc-4.3.2
 ../gcc-4.3.2/configure --prefix=/opt/gcc-4.3.2 --enable-languages=c,c++,fortran --with-mpfr=../mpfr-2.3.2 --build=i686-apple-darwin9 --host=i686-apple-darwin9 --target=i686-apple-darwin9
 make -j 8
 # Now go have coffee, maybe lunch :)
 sudo make install

====Note on using custom-built gcc====

Generally, to use a custom-built gcc, you just have to specify the complete path to the compiler, like this:

 /opt/gcc-4.3.2/bin/gcc myprogram.c

Most build-systems will respect the environment variables CC, CXX and FC, so to set the default compilers, this will generally work:

 export CC=/opt/gcc-4.3.2/bin/gcc
 export CXX=/opt/gcc-4.3.2/bin/g++
 export FC=/opt/gcc-4.3.2/bin/gfortran

In addition, similarly-named variables exist by default for make files, so you can generally also do this:

 make CC=/opt/gcc-4.3.2/bin/gcc CXX=/opt/gcc-4.3.2/bin/g++ FC=/opt/gcc-4.3.2/bin/gfortran
o specify the complete path to the compiler, like this:

 /opt/gcc-4.3.2/bin/gcc myprogram.c

Most build-systems will respect the environment variables CC, CXX and FC, so to set the default compilers, this will generally work:

 export CC=/opt/gcc-4.3.2/bin/gcc
 export CXX=/opt/gcc-4.3.2/bin/g++
 export FC=/opt/gcc-4.3.2/bin/gfortran

In addition, similarly-named variables exist by default for make files, so you can generally also do this:

 make CC=/opt/gcc-4.3.2/bin/gcc CXX=/opt/gcc-4.3.2/bin/g++ FC=/opt/gcc-4.3.2/bin/gfortran