Field analysis: getting useful and low-cost interprocedural information

We present a new limited form of interprocedural analy-sis called eld analysis that can be used by a compiler to reduce the costs of modern language features such as object-oriented programming, automatic memorymanagement, and run-time checks required for type safety. Unlike many pre-vious interprocedural analyses, our analysis is cheap, and does not require access to the entire program. Field analy-sis exploits the declared access restrictions placed on elds in a modular language (e.g. eld access modiers in Java) in order to determine useful properties of elds of an object. We describe our implementation of eld analysis in the Swift optimizing compiler for Java, as well a set of opti-mizations that exploit the results of eld analysis. These optimizations include removal of run-time tests, compile-time resolution of method calls, object inlining, removal of unnecessary synchronization, and stack allocation. Our re-sults demonstrate that eld analysis is eÆcient and eective. Speedups average 7 % on a wide range of applications, with some times reduced by up to 27%. Compile time overhead of eld analysis is about 10%.