Generating OpenCL C kernels from OpenACC

Abstract

Hardware accelerators are now a common way to improve the performances of compute nodes. This performance improvement has a cost: applications need to be rewritten to take advantage of the new hardware. OpenACC is a set of compiler directives to target hardware accelerators with minimal modification of the original application. In this paper, we present the generation of OpenCL C kernels from OpenACC annotated codes. We introduce a method to produce multiple kernels for each OpenACC compute region. We evaluate these kernels on different hardware accelerators (NVidia GPU, Intel MIC). Finally, we show that the produced kernels give different performances for different accelerators. Hence this method produces a tuning space in which we can search for the best kernel version for a given accelerator.