It is highly recommended that you uninstall any previous versions of XL C/C++ before you install XL C/C++ V8.0. If you use the xlc_install utility to install the new version to the default location (/opt/ibmcmp/), it will remove the old files for you.
xlc_install will detect the presence of a previous version and will require that you uninstall it before it proceeds with the installation.
Before you use the xlc_install utility to install and configure XL C/C++ V8.0, use the pre-installation checklist in Table 4 to ensure that all prerequisite conditions are satisfied.