The OpenMPOpt pass is a CG-SCC pass in which OpenMP specific
optimizations can reside.
The OpenMPOpt pass uses the OpenMPKinds.def file to identify runtime
calls and their uses. This allows targeted transformations and eases
This initial patch deduplicates __kmpc_global_thread_num calls. We can
also identify arguments that are equivalent to such a call result and
use it instead. Later we can determine "gtid" arguments based on the use
in kernel functions etc.