Static Speculation, Dynamic Resolution

This paper proposes a new compiler technique that enables speculative execution of alternative program paths. In our approach separate threads are generated that simultaneously speculate on the outcome of branches and that may run in parallel. Our technique goes beyond the capabilities of usual global instruction scheduling algorithms, because we overcome the restrictions to speculative instruction movement introduced by branches that could not be handled. The architectural requirements are the ability to run two or more threads in parallel and an enhanced instruction set to control threads. Our technique aims at simultaneous multithreaded, nanothreaded, and microthreaded processors, but can be modified for multiscalar, datascalar, and trace processors. We evaluate our approach using program kernels from the SPECint benchmark suite. I. Introduction The continuous progress in microprocessor technology allows to implement a growing number of execution units on a single chip. With a sing..