SIMD Code Translation in an Enhanced HQEMU

Abstract

HQEMU is a multi-threaded and re-targetable dynamic binary translator built on top of QEMU and LLVM. It combines the fast and reliable code translation in the TCG (Tiny Code Generator) of QEMU and the rich optimizations in LLVM to achieve high performance for both short running and long running applications. One weakness of HQEMU lies in the lack of efficient SIMD instruction translation. This work investigates on how to remedy that. Two approaches have been designed and tested. One simple approach is to modify the help function to emit LLVM vector IR, and a more complete approach is to add a newly introduced vector IR in the TCG phase. Although both approaches can exploit the SIMD instructions of the host machine, the second and more complete approach has superior runtime as well as compile time advantages.