Lightweight Run-Time Code Generation
Mark Leone and Peter Lee


Run-time code generation is an alternative and complement to
compile-time program analysis and optimization.  Static analyses are
inherently imprecise because most interesting aspects of run-time
behavior are uncomputable.  By deferring aspects of compilation to run
time, more precise information about program behavior can be
exploited, leading to greater opportunities for code improvement.

The cost of performing optimization at run time is of paramount
importance, since it must be repaid by improved performance in order
to obtain an overall speedup.  This paper describes a lightweight
approach to run-time code generation, called deferred compilation, in
which compile-time specialization is employed to reduce the cost of
optimizing and generating code at run time.  Implementation strategies
developed for a prototype compiler are discussed, and the results of
preliminary experiments demonstrating significant overall speedup are
presented.