Abstract

Dynamic scripting languages offer programmers increased flexibility by allowing properties of programs to be defined at run-time. Typically, program execution begins with an interpreter where type checks are implemented using conditional statements. Recent JIT compilers have begun removing run-time checks by specializing native code to program properties discovered at JIT time. This paper presents a novel intermediate representation for scripting languages that explicitly encodes types of variables. The dynamic representation is a flow graph, where each node is a specialized virtual instruction and each edge directs program flow based on control and type changes in the program. The interpreter thus performs specialized execution of whole programs. We present techniques for the efficient interpretation of our representation showing speedups of greater than 2x overstaticinterpretation, with an average speedup of approximately 1.3x. 1.

Citations