Development/Intel Compiler

Intel Compiler
module load	compiler/intel/xxx
License	GPL
Citing
Links	Homepage
Graphical Interface	No
Included in module	icc, icpc, ifort, idb

The Intel Compiler of the Intel Composer XE Suite consists of tools to compile and debug C, C++ and Fortran programs:

icc	Intel C compiler
icpc	Intel C++ compiler
ifort	Intel Fortran compiler
idb	Intel debugger in GUI mode
idbc	Intel debugger in console mode

Aside from that the suite also includes the TBB (Threading Building Blocks) and IPP (Integrated Performance Primitives) libraries.

Loading

There are different versions of the Intel compilers installed. To get a list of these installations execute the following command:

$ module avail compiler/intel

There is a default version which will be loaded when no version is explicitly specified, so the command

$ module load compiler/intel

will load the default version.

A current list of the versions available on the bwUniCluster and bwForClusters can be obtained from the Cluster Information System: CIS Information on Intel or here: {{#widget:Iframe |url=https://cis-hpc.uni-konstanz.de/prod.cis/bwUniCluster/compiler/intel |width=99% |height=280 |border=1 }}

Online documentation

http://software.intel.com/en-us/articles/intel-c-composer-xe-documentation

Local documentation

For version specific documentation see the help page of the module. For example

$ module help compiler/intel

will show the information for the default version. For detailed lists of the different program options consult the particular man page:

$ man icc
$ man icpc
$ man ifort
$ man idb

Optimizations

You can turn on various optimization options to enhance the performance of your program. Which options are the best depends on the specific program and can be determined by benchmarking your code. A command which gives good performance and a decent file size is

$ icc -xHost -O2 ex.c

There are more aggressive optimization flags and levels (e.g. -O3 or -fast and implied options) but the compiled programs can get quite large due to inlining. Additionally the compilation process will probably take longer. Moreover it may happen that the compiled program is even slower -- or may require installation of additional statically-linked libraries. Such a command would be for example:

$ icc -fast ex.c

Profiling

Profiling an application means augmenting the compiled binary with information on execution counts per source-line (and basic blocks) -- e.g. one may see how many times an if-statement has been evaluated to true. To do so, compile your code with the profile flag:

$ icc -p ex.c -o ex

Using the gprof tool, one may manually inspect execution count of each executed line of source code.

For compiler optimization, recompile Your source using

$ icc -prof-gen ex.c -o ex

then execute the most common and typical use-case of Your application, and then recompile using the generated profile count (and using optimization):

$ icc -prof-use -O2 ex.c -o ex

Further literature

A tutorial on optimization can be found at https://software.intel.com/sites/default/files/managed/c1/61/compiler-essentials.1.pdf and to get the different optimization options execute

$ icc -help opt
$ icc -help advanced

or the previously described catch-all option -v --help.