XDP: A compiler intermediate language extension for the representation and optimization of data movement

Abstract

The ability to represent, manipulate, and optimize data placement and movement between processors in a distributed address space machine is crucial in allowing compilers to generate efficient code. Data placement is embodied in the concept of dataownership. Data movement can include not just the transfer of data values but the transfer of ownership as well. However, most existing compilers for distributed address space machines either represent these notions in a language-or machine-dependent manner, or represent data or ownership transfer implicitly. In this paper we describe XDP, a set of intermediate language extensions for representing and manipulating data and ownership transfers explicitly in a compller. XDP is supported by a set of per-processor structures that can be used to implement ownership testing and manipulation at run-time, XDP provides a uniform framework for translating and optimizing sequential, data parallel, and message-passing programs to a distributed address space machine. We describe analysis and optimization techniques for this explicit representation. Finally, we compare the intermediate languages of some current distributed address space compilers with XDP.