Extending the Capabilities of the Cray Programming Environment with Clang-LLVM Framework Integration

Recent developments in programming for multicore processors and accelerators using C++11, OpenCL and Domain Specific Languages (DSL) have prompted us to look into tools that offer compilers and both static and runtime analysis toolchains to complement the Cray Programming Environment capabilities. In this paper we report our preliminary experiences from using the CLang-LLVM framework on a hybrid Cray XC30 to perform tasks such as generating NVIDIA PTX code from C++ and OpenCL in a portable and flexible manner. Specifically we investigate how to overcome some of the limitations currently imposed by the standard tools such as the complete lack of C++11 support in CUDA C and outdated 32 bit versions of OpenCL. We also demonstrate how Clang-LLVM tools, for example, the static analyzer can bring additional capabilities to the Cray environment. Finally we describe how CLang-LLVM integrates with the standard Cray Programming Environment (PE), for instance, Cray MPI, perftools and libraries, and the steps required to properly install such tools on various Cray platforms. Keywords-Programming Environment (PE); Cray XC30; GPU; Clang; LLVM (key words); CUDA, OpenCL