Sun Microsystems, Inc.

Tymesys Corporation

Scott D Robbins

Peter Cadwell Dibble

David S Hardin

Gregory Bollella

Pratik Solanki

C Douglass Locke

Benjamin M Brosgol

A technique for implementing a data processor to determine if an exception has been thrown. Specifically, the technique may be used in an interpretive environment where a table known as a bytecode (upcode) dispatch table is used. The dispatch table contains addresses for code that implements each bytecode. When the interpreter executes normally, these addresses point to the basic target machine code for executing each bytecode. However, when an Asynchrounously Interrupted Exception (AIE) is thrown, then the dispatch table is repopulated so that all byte codes point to routines that can handle the exception. These may point to a routine, such as an athrow, that has been extended to handle the special case of the AIE. Alternatively, the rewritten table can point to a routine that is specifically written to handle the firing of an AIE. The table contents are restored to their prior state once the exception handling is complete. The scheme may also be implemented non-rewriting of the table if a thread is in a non-Asynchronous Transfer of Control (to defer ATC) deferred state.

Techniques for exception handling by rewriting dispatch table elements

An invention is provided for a synchronous transfer of control. An asynchronous interrupt exception is received, and in response, the value of a reference counter is determined. The value of the reference counter is based on the execution of synchronized code. Generally, the reference counter is initialized to a predetermined number, and altered based on the execution of synchronized code. When the asynchronous interrupt exception is received, the method is asynchronously interrupted when the value of the reference counter is equal to the predetermined number.

System and method for asynchronous transfer of control

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Scott D Robbins