Optimization for a superscalar out-of-order machine

Compiler optimization plays a key role in unlocking the performance of the PA-8000, an innovative dynamically-scheduled machine which is the first implementation of the 64-bit PA 2.0 member of the HP PA-RISC architecture family. This wide superscalar, long out-of-order machine provides significant execution bandwidth and automatically hides latency at runtime; however despite its ample hardware resources, many of the optimizing transformations which proved effective for the PA-8000 served to augment its ability to exploit the available bandwidth and to hide latency. Further machine-specific factors influenced all levels of optimization to a degree without precedent in the set of previous PA-RISC processors. While legacy codes benefit from the PA-8000's sophisticated hardware, recompilation of old binaries can be vital to realizing the full potential of the PA-8000, given the impact of new compilers in achieving peak performance for this machine.