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.