Efficient virtual function calls for compiled/interpreted environments

A computer program product comprising a computer usable medium bearing computer readable code for a computer programming environment supporting virtual function calls and supporting both interpretation of functions in a set of functions and execution of compiled code representing functions in the set of functions, the set of functions being referenced in one or more loaded classes in, a set of computer code, the computer program product comprising computer readable code for generating, for each loaded class:

• a first virtual function table for access by an interpreter for interpreting a call in the computer code to one of the functions in the set of functions, and
• a second virtual function table for access during execution of the compiled code for calling one of the functions in the set of functions;
• and, wherein
• for each loaded class, a class object comprising a first end and a second end, in which the first virtual function table for the loaded class is contiguous with the first end of the class object, and the second virtual function table for the loaded class is contiguous with the second end of the class object and in which the first virtual function table and the second virtual function table are structured symmetrically about the class object.

A Java virtual machine, which operates on a computer system, comprising an interpreter, supporting virtual method calls and supporting both interpretation of methods in a set of methods and execution of compiled code representing methods in the set of methods, the set of methods being referenced in one or more loaded Java classes, the Java virtual machine comprising a computer usable medium having computer readable code recorded therein, comprising

• computer readable program code for generating, for each loaded Java class;
• a first virtual function table for access by the interpreter for interpreting a call to one of the methods and comprising interpretation entries, each interpretation entry being associated with a method and pointing to a corresponding function data structure;
• and
• a second virtual function table for access in the execution of the compiled code to execute a call to one of the methods and comprising compilation entries, each compilation entry being associated with a function in the set of functions and pointing to either a corresponding block of executable code or to a corresponding block of interpreter transition code,
• the interpreter transition code corresponding to a compilation entry for a selected associated function being executable to access the function data structure pointed to by the interpretation entry for the said selected associated function.

A Java language programming environment running on a computer system, supporting virtual method calls and supporting both interpretation of methods in a set of methods and execution of compiled code representing methods in the set of methods, the set of methods being referenced in one or more loaded Java classes, the Java language programming environment comprising, for each loaded Java class:

• a first virtual function table for access by the interpreter for interpreting a call to one of the methods and comprising interpretation entries, each interpretation entry being associated with a method and pointing to a corresponding function data structure;
• and
• a second virtual function table for access in the execution of the compiled code to execute a call to one of the methods and comprising compilation entries, each compilation entry being associated wit a function in the set of functions and pointing to either a corresponding block of executable code or to a corresponding block of interpreter transition code,
• the interpreter transition code corresponding to a compilation entry for a selected associated function being executable to access the function data structure pointed to by the interpretation entry for the said selected associated function.