Traditional data prefetching based on static compiler analysis mainly aims at array access. Now, linked data structures due to pointers abound in applications, which is difficult to prefetch by traditional technique. Feedback directed data prefetching optimization has become one of the advanced compiler optimization techniques. it can do well in linked data prefetching. This paper researches the profile guided optimization in ORC compiler, improves the prefetching algorithm according to features of Alpha architecture. SPEC2000 performance test shows 4.1% speedup.