Spike: An Optimizer for Alpha/NT Executables

Spike is a profile-directed optimizer for Alpha/NT executables that is actively being used to optimize shipping products. Spike consists of the Spike Optimization Environment (SOE) and the Spike Optimizer. Through both a graphical interface and a commandline interface, the Spike Optimization Environment provides a simple means to instrument and optimize large applications consisting of many images. SOE manages the instrumented and optimized images as well as any profile information collected for those images, freeing the user from many tedious and errorprone tasks typically associated with profile-directed optimization. SOE also simplifies the collection of profile information with Transparent Application Substitution (TAS). With TAS, the user invokes the original version of the application and the instrumented or optimized version of the application is transparently executed in its. SOE uses the Spike Optimizer to optimize images. The Spike Optimizer performs code layout to improve instruction cache behavior [Pettis90], hot cold optimization [Cohn96] and register allocation. The optimizations are targeted at large call-intensive applications, where loops span multiple routines, and each routine contains complex control-flow. For this class of applications, Spike provides significant performance improvement, reducing execution time by as much as 20%.