After installation of the Intel C++ Compiler you need to source the compiler script in order to use all tools, for example (when you did a root install): $ source /opt/intel/Compiler/11.1/072/bin/iccvars.sh ia32|intel64 or (user install) $ source $HOME/intel/Compiler/11.1/072/bin/iccvars.sh ia32|intel64 If you have a 32-bit system, use the ia32 parameter, for 64-bit systems use intel64.
gcc is the GNU compiler dirver and doesn't work with Intel specific options like -ipo. The Intel compiler is being invoked with driver 'icc', for example $ icc -g -ipo hello.c
In your build script, before you call make, you may call source xxx to set the icc build environment, and then call 'which icc' to see if the icc path is set correctly. In addition, if you use sudo to call make like 'sudo make', you may call sudo -s first to go to root build environment, and then source the icc environment, then call make. Thanks. -Yang