Automatic, template-based run-time specialization: Implementation and experimental study

Specializing programs with respect to run-time valves has been shown to drastically improve code performance on realistic programs ranging from operating systems to graphics. Recently, various approaches to specializing code at run-time have been proposed. However, these approaches still suffer from shortcomings that limit their applicability: they are manual, too expensive, or require programs to be written in a dedicated language. We solve these problems by introducing new techniques to implement run-time specialization. The key to our approach is the use of code templates. Templates are automatically generated from ordinary programs and are optimized before run time, allowing high-quality code to be quickly generated at ran time. Experimental results obtained on scientific and graphics code indicate that our approach is highly effective. Little run-time overhead is introduced, since code generation primarily consists of copying instructions. Run-time specialized programs run vp to 10 times faster, and are nearly as fast as fully optimized programs (80% on average). The combination of lour run-time overhead and high code quality enables specialization to be amortized in as few as 3 runs. Although this approach is highly effective, its implementation is relatively simple since it exploits existing partial evaluation and compiler technologies.