A General Approach for Run-Time Specialization and its Application to C

Specializing programs with respect to run-time invariants is an optimization technique that has shown to improve the performance of programs substantially. It allows a program to adapt to execution contexts that are valid for a limited time. Run-time specialization is being actively investigated in a variety of areas. For example, recently, major operating system research projects have been focusing on run-time specialization as a means to obtain efficiency from highly extensible and parameterized systems. This paper describes a general approach to run-time specialization. For a given program and a declaration of its runtime invariants, it automatically produces source templates at compile time, and transforms them so that they can be processed by a standard compiler. At run time, only minor operations need to be performed: selecting and copying templates, filling holes with run-time values, and relocating jump targets. As a consequence, run-time specialization is performed very effici..