Available Compilers

The Faculty Linux systems have access to the GNU (gcc), Intel and PGI compilers.

The default setting is to use the system version of the GNU compilers (/usr/bin/gcc, /usr/bin/gfortran, /usr/bin/g++).

The compilers are loaded using the Environment Modules software.

 

GNU compilers

The default setting on the Faculty Linux machines is to use the system version of the GNU compilers, found in /usr/bin.

There will generally be at least one (more recent) version of the GNU compilers available in the modules, which can be found with:

module avail gnu

On the Faculty systems:

module load gcc

will load the most recent version of the GNU compilers available on the system, and:

module load gnu

will load the default / system version.

 

GNU compiler variables

The following variables will be set when using the GNU compilers:

 

• CC gcc
• CXX g++
• FC gfortran
• F77 gfortran
• F90 gfortran

 

g77 Fortran compiler

The Faculty Linux systems continue (at present) to provide the g77 compiler (/usr/bin/g77), mostly to allow the compilation of code which only compiles with g77 ...

g77 has not been updated in many years, may be removed from the systems in the future, and is not recommended for general use.

If you have / have to use code which will only compile with g77, be prepared for it to stop working at any time!

 

Intel compilers

The Intel compilers are a licensed product, for which the University has a number of licenses available for use on Linux systems only - the University does not have licenses available for the Windows or Apple versions of the compilers.

The intel compilers can be loaded with:

module load intel

 

Intel compiler variables

The following variables will be set when using the Intel compilers:

 

• CC icc
• CXX icpc
• FC ifort
• F77 ifort
• F90 ifort

 

Using the Math Kernel Library

The Intel compilers have access to the Intel Math Kernel Library, which can be linked in at compilation time with the mkl option:

ifort -mkl -o program source.f90

 

PGI compilers

The PGI compilers are a licensed product, for which the University has a number of licenses available for use on Linux systems. The intel compilers can be loaded with:

module load pgi

 

PGI compiler variables

The following variables will be set when using the PGI compilers:

 

• CC pgcc
• CXX pgc++
• FC pgf95
• F77 pgf77
• F90 pgf95

 

MPI Libraries

The Faculty Linux systems have versions of the Open MPI and MPICH MPI libraries available.

By default, the OpenMPI libraries will be loaded at login to the Linux systems. To load the OpenMPI libraries:

module load openmpi

To load the MPICH libraries:

module load mpich

When the compiler is changed (e.g. module load intel), the MPI libraries will automatically be switched to version that is compatible with the compiler:

 

% echo ${CC}
gcc
% mpicc -v
Using built-in specs.
COLLECT_GCC=/usr/bin/gcc
...
% module load intel
% echo ${CC}
icc
% mpicc -v
icc version 17.0.0 (gcc version 4.8.5 compatibility)

Available Debuggers

The Faculty Linux systems have access to the GNU gdb debugger, the ArmDDT (formally Allinea DDT) debugger (as part of the Arm Forge package), as well as the PGI debugger which is provided with the compiler suite.

Detailed usage of debuggers is beyond the scope of these notes, but some information on accessing the various debuggers is included below.

 

GDB Debugger

The default version of gdb will be installed at /usr/bin/gdb, and can be accessed by simply running:

gdb

gdb is a purely command line program, though the DDD graphical front end is also installed on the Faculty Linux systems, and can be launched with:

ddd

 

ArmDDT Debugger

The Armddt debugger is a licensed product for which the University has a number of Licenses.

The Arm software (formally Allinea) can be loaded with:

module load allinea

The ddt debugger can then be loaded with:

ddt

This will launch the Arm Forge graphical program, from which the debugging process can be started.

The Arm Forge software is very powerful, and compatible with various compilers and MPI environments.

Allinea documentation can be found at:

https://developer.arm.com/docs/101136/1910/ddt/getting-started

 

Arm MAP Profiler

The ArmForge software also includes access to the MAP profiler, which can be used to closely inspect programs and their activity, and can be a great help in optimising code.

Once the ArmForge software has been loaded:

module load allinea

The MAP profiler, which is a graphical application, can be launched with:

map

 

PGI Debugger

When the PGI compilers are in use / have been loaded with:

module load pgi

The PGI debugger can be launched with:

pgdbg

This will launch a graphical application by default.