Automatic inference of stationary fields: a generalization of java's final fields

Java programmers can document that the relationship between two objects is unchanging by declaring the field that encodes that relationship to be final. This information can be used in program understanding and detection of errors in new code additions. Unfortunately, few fields in programs are actually declared final. Programs often contain fields that could be final, but are not declared so. Moreover, the definition of final has restrictions on initialization that limit its applicability. We introduce stationary fields as a generalization of final. A field in a program is stationary if, for every object that contains it, all writes to the field occur before all the reads. Unlike the definition of final fields, there can be multiple writes during initialization, and initialization can span multiple methods. We have developed an efficient algorithm for inferring which fields are stationary in a program, based on the observation that many fields acquire their value very close to object...

• Type: Conference
• Year: 2008
• Where: POPL
• Authors: Christopher Unkel, Monica S. Lam
• Keywords: Efficient Pointer Alias, General Terms Algorithms, Initialization This Work, POPL 2008, Programming Languages