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Intel Compilers

The Intel Compiler from 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
gdb-ia Intel version of GNU debugger in console mode

The intel compiler suite also includes the TBB (Threading Building Blocks) and IPP (Integrated Performance Primitives) libraries.

Versions and Availability

We generally support the last three releases. You can get a list of available versions using the command module avail compiler/intel.

Environment Variables

To see a list of all environment variables set by the modules use the command module show compiler/gnu/version.

Example:

setenv("AR","/opt/intel/compilers_and_libraries_2020/linux/bin/intel64/xiar")
setenv("CC","/opt/intel/compilers_and_libraries_2020/linux/bin/intel64/icc")
setenv("CXX","/opt/intel/compilers_and_libraries_2020/linux/bin/intel64/icpc")
setenv("F77","/opt/intel/compilers_and_libraries_2020/linux/bin/intel64/ifort")
setenv("FC","/opt/intel/compilers_and_libraries_2020/linux/bin/intel64/ifort")
setenv("CFLAGS","-O2 -xCORE-AVX2")
setenv("CXXFLAGS","-O2 -xCORE-AVX2")
setenv("FFLAGS","-O2 -xCORE-AVX2")
setenv("FCFLAGS","-O2 -xCORE-AVX2")
setenv("INTEL_VERSION","19.1.0.166")
setenv("INTEL_HOME","/opt/intel/compilers_and_libraries_2020/linux")
setenv("INTEL_BIN_DIR","/opt/intel/compilers_and_libraries_2020/linux/bin/intel64")
setenv("INTEL_LIB_DIR","/opt/intel/compilers_and_libraries_2020/linux/lib/intel64")
setenv("INTEL_INC_DIR","/opt/intel/compilers_and_libraries_2020/linux/include")
setenv("INTEL_MAN_DIR","/opt/intel/compilers_and_libraries_2020/linux/man/common")
setenv("INTEL_DOC_DIR","/opt/intel/compilers_and_libraries_2020/linux/documentation/en")
setenv("GDB_VERSION","19.1.0.166")
setenv("GDB_HOME","/opt/intel/debugger_2020/gdb/intel64")
setenv("GDB_BIN_DIR","/opt/intel/debugger_2020/gdb/intel64/bin")
setenv("GDB_LIB_DIR","/opt/intel/debugger_2020/libipt/intel64/lib")
setenv("GDB_INC_DIR","/opt/intel/debugger_2020/gdb/intel64/include")
setenv("GDB_INF_DIR","/opt/intel/documentation_2020/en/debugger/gdb-ia/info")
setenv("GDB_MAN_DIR","/opt/intel/documentation_2020/en/debugger/gdb-ia/man")
setenv("KMP_AFFINITY","noverbose,granularity=core,respect,warnings,compact,1")
...

Documentation

The official documentation can be found online:

For a detailed lists of the different program options you can also consult the man pages installed on HoreKa:

$ man icc
$ man icpc
$ man ifort
$ man idb
$ man gdb-ia

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

With the option -xHost instructions for the highest instruction set available on the compilation host processor are generated. If you want to generate optimal code on bwUniCluster for both nodes with Sandy Bridge architecture and nodes with Broadwell architecture, you must compile your code with the options -xAVX -axCORE-AVX2 (instead of -xHost).

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

A tutorial on optimization can be found here.

To get the different optimization options execute

icc -help opt
icc -help advanced

Or use the previously described catch-all option -v --help.


Last update: May 31, 2021