In modern processors, both the hardware implementation and optimizing compilers are very complex, and they often interact in unpredictable ways. A high performance microarchitecture typically issues instructions out-of-order and must deal with a number of disruptive miss events such as branch mispredictions and cache misses. An optimizing compiler implements a large number of individual optimizations which not only interact with the microarchitecture, but also interact with each other. These interactions can be constructive, destructive, or neutral. Furthermore, whether there is performance gain or loss often depends on the particular program being optimized and executed.