Compiling

Programming environments

The Keeneland System uses modules to control the programming environment. For instance, there are compilers from several different vendors, each of which may have several releases available. Modules generally interact with your environment variables (eg: $PATH) to choose which compiler is being used, and which libraries are being linked in.

By default, several modules are already loaded:

$ module list
Currently Loaded Modulefiles:
  1) modules
  2) torque/2.5.11
  3) moab/6.1.5
  4) gold
  5) mkl/2011_sp1.8.273
  6) intel/2011_sp1.8.273
  7) openmpi/1.5.1-intel
  8) PE-intel
  9) cuda/4.1

The PE-intel module sets up the environment to use Intel compilers (icc and ifort). The module show command lists all the actions that loading this module will make: in this case, it checks to see whether another programming environment is already loaded, and quits if that is the case. Otherwise, it loads the default version of the Intel compilers, and the version of OpenMPI intended to work with Intel, and sets some generic environmental variables to be used in Makefiles (ie: $CC should always refer to the current C compiler):

$ module show PE-intel
-------------------------------------------------------------------
/opt/modulefiles/PE-intel:

conflict     PE-pgi PE-gnu PE-intel 
module         load intel 
module         load openmpi/1.5.1-intel 
setenv         CC icc 
setenv         CPP icc -E 
setenv         CXX icpc 
setenv         FC ifort 
setenv         F77 ifort 
setenv         F90 ifort 
-------------------------------------------------------------------

In order to change compilers, use module swap. Third party libraries may need to be reloaded after this as they often check which programming environment is loaded and set paths accordingly. This changes from Intel compilers to PGI:

$ module swap PE-intel PE-pgi

Notes:

• Some third party software (notably DDT) does not work with the new version of CUDA yet, it may still be advisable to give that version a try.
• The default version of gcc without modules is 4.1.2.User may load other newer version of gcc.

Compiling for CPU

In order to compile non-MPI, non-CUDA code, the compilers may be called directly. Additional documentation is also provided in the man pages for each compiler, for example man gcc.

Notes:

• In addition, the modules should define $CPP to be the generic C pre-processor
• icc will compile C or C++ depending on the suffix of the source code, icpc is the same compiler, but it forces C++
• Similarly, the Fortran compilers may have several different names, corresponding to the Fortran 77 or Fortran 90 standards. Refer to the man pages for more specifics.