Metaprogramming-Enabled Parallel Execution of Apparently Sequential C++ Code

Task-based execution models have received considerable attention in recent years to meet the performance challenges facing high-performance computing (HPC). In this paper we introduce MetaPASS - Metaprogramming-enabled Para-llelism from Apparently Sequential Semantics - a proof-of-concept, non-intrusive header library that enables implicit task-based parallelism in a sequential C++ code. MetaPASS is a data-driven model, relying on dependency analysis of variable read-/write accesses to derive a directed acyclic graph (DAG) of the computation to be performed. MetaPASS enables embedding of runtime dependency analysis directly in C++ applications using only template metaprogramming. Rather than requiring verbose task-based code or source-to-source compilers, a native C++ code can be made task-based with minimal modifications. We present an overview of the programming model enabled by MetaPASS and the C++ runtime API required to support it. Details are provided regarding how standard template metaprogramming is used to capture task dependencies. We finally discuss how the programming model can be deployed in both an MPI+X and in a standalone distributed memory context.