A balanced code placement framework

Abstract

Give-N-Take is a code placement framework which uses a generic producer-consumer mechanism. An instance of this could be a communication step between a processor that computes (produces) some data, and other processors that subsequently reference (consume) these data in an expression. An advantage of Give-N-Take over traditional partial redundancy elimination techniques is its concept of production regions , instead of single locations, which can be beneficial for general latency hiding. Give-N-Take also guarantees balanced production, i.e., each production will be started and stopped exactly once. The framework can also take advantage of production coming “for free,” as induced by side effects, without disturbing balance. Give-N-Take can place production either before or after consumption, and it also provides the option to speculatively hoist code out of potentially zero-trip loop (nest) constructs. Give-N-Take uses a fast elimination method based on Tarjan intervals, with a complexity linear in the program size in most cases. We have implemented Give-N-Take as partof a Fortran D compiler prototype, where it solves various communication generation problems associated with compiling data-parallel languages onto distributed-memory architectures.