A system and associated method for creating a library method stub in source code form corresponding to an original library call in machine-executable form. Sequential code subject to pipeline-parallelization includes the original library call of which source code is not available for profiling. The original library call is annotated for a library method signature to specify formal arguments and parameters accessible to the formal arguments. Memory operations of the original library call are summarized with on one or more idiom sentences, which are mapped to a respective code stub that simulates the original library call. The library method stub is created for profiling of the original library call in source code level such that the sequential code is parallelized via the created library method stub.