Run-Time Support for Optimizations Based on Escape Analysis

Abstract

We implemented a new escape analysis algorithm for Sun Microsystems' Java HotSpottrade VM. The results are used to replace objects with scalar variables, to allocate objects on the stack, and to remove synchronization. This paper deals with the representation of optimized objects in the debugging information and with reallocation and garbage collection support for a safe execution of optimized methods. Assignments to fields of parameters that can refer to both stack and heap objects are associated with an extended write barrier which skips card marking for stack objects. The traversal of objects during garbage collection uses a wrapper that abstracts from stack objects and presents their pointer fields as root pointers to the garbage collector