None
Asserts that all functions with Message Passing Interface (MPI) names are in fact MPI functions and not a user function with different semantics.
-qnolibmpi
MPI is a library interface specification for message passing. It addresses the message-passing parallel programming model in which data is moved from the address space of one process to another through cooperative operations. For details about MPI, see the Message Passing Interface Forum.
-qlibmpi allows the compiler to generate better code because it knows about the behavior of a given function, such as whether or not it has any side effects.
When you use -qlibmpi, the compiler assumes that all functions with the name of an MPI library function are in fact MPI functions. -qnolibmpi makes no such assumptions.
None.
xlc -O5 myprogram.c -qlibmpi