The canonical ICD loader made public by Khronos does the following:
It opens the files /etc/OpenCL/vendors/*.icd which should all be text files with a single line, holding a shared library name. All such *.icd files will correspond to one platform in the application. The ICD will try to load these libraries via the C runtime's dlopen(), hence the system linker must be able to find them through means of the Linux distribution at hand (ld.so.conf, LD_LIBRARY_PATH, etc.).
foreach ($Platform in (Get-Item HKLM:\SOFTWARE\Khronos\OpenCL\Vendors\)) { $Platform }