Turbo DiSL: partial evaluation for high-level bytecode instrumentation

Bytecode instrumentation is a key technique for the implementation of dynamic program analysis tools such as profilers and debuggers. Traditionally, bytecode instrumentation has been supported by low-level bytecode engineering libraries that are difficult to use. Recently, the domain-specific aspect language DiSL has been proposed to provide high-level abstractions for the rapid development of efficient bytecode instrumentations. While DiSL supports user-defined expressions that are evaluated at weave-time, the DiSL programming model requires these expressions to be implemented in separate classes, thus increasing code size and impairing code readability and maintenance. In addition, the DiSL weaver may produce a significant amount of dead code, which may impair some optimizations performed by the runtime. In this paper we introduce Turbo, a novel partial evaluator for DiSL, which processes the generated instrumentation code, performs constant propagation, conditional reduction, and pattern-based code simplification, and executes pure methods at weave-time. With Turbo, it is often unnecessary to wrap expressions for evaluation at weave-time in separate classes, thus simplifying the programming model. We present Turbo's partial evaluation algorithm and illustrate its benefits with several case studies. We evaluate the impact of Turbo on weave-time performance and on runtime performance of the instrumented application.