Add a Cache Prefetching Recommendation Tool and a Sample Microbenchmark

Created by: kharbutli

The goal is to have a microbenchmark and a SW cache prefetching recommendation tool, so we can motivate upstreaming the other tooling changes required for profile-guided prefetching (llvm/create_llvm_prof).

The tool would run the DRCacheSim cache simulator and based on the pattern of LLC misses, the tool may recommend adding SW prefetching instructions at certain instruction addresses. These addresses would correspond to the load instructions contributing to a significant number of the LLC misses. The tool would also recommend a prefetching distance.