Compiling almost-whole Java programs

This paper presents a strategy, called almost-whole-program compilation, for extending the benefits of whole-program optimization to large collections of Java components that are packaged as a group after the development phase. This strategy has been implemented in a framework that uses Java visibility and scoping rules to transform a collection of classes into a package that is amenable to whole-program optimizations, without precluding extensions to the optimized and compiled code. Thus, it enables the Java developer to balance performance against flexibility of the program after the development phase, without compromising the design process. The transformation is shown to incur only modest performance penalties, which are more than compensated for by the interprocedural optimizations it enables. The paper concludes with experimental results showing the benefits that can be achieved using this approach. Copyright c © 2005 John Wiley & Sons, Ltd.