Sun Microsystems, Inc.

Kasper V Lund

Lars Bak

Jacob R Andersen

One embodiment of the present invention provides a system for type tagging values in a compiled activation frame in a lazy manner to facilitate garbage collection. This system operates in a mixed-mode environment that supports both interpretation of byte codes and execution of compiled native code. Upon receiving an invocation of a method, the system creates an activation frame for the method on the execution stack. If the method is executing in interpreted mode, the interpreter maintains a tag for each value in the activation frame during execution. The tag indicates whether the value is a reference type or a primitive type. However, if the method is executing in compiled mode, the system allocates space for tags for each value in the activation frame, but does not fill in the tags during execution. This allows the tags to be filled in at a future time when needed.

Method and apparatus for facilitating lazy type tagging for compiled activations

One embodiment of the present invention provides a system that gathers code usage information to facilitate removing compiled code that has not been recently used. This method operates in a mixed-mode system that supports execution of both compiled code and interpreter code. During operation, the system gathers usage information for compiled methods within an application while the application is executing. Next, the system identifies compiled methods to be removed based on this usage information, and removes identified compiled methods so that interpreter code is executed for the compiled methods instead of compiled code. In this way, the system frees up the memory space used to store the compiled methods.

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Aarhus C, Denmark

Kasper V Lund