Data processing: software development – installation – and managem – Software program development tool – Translation of code
Reexamination Certificate
1998-12-03
2001-11-27
Powell, Mark R. (Department: 2122)
Data processing: software development, installation, and managem
Software program development tool
Translation of code
Reexamination Certificate
active
06324687
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
The present invention is related to applications entitled A Method and Apparatus to Coordinate and Control the Simultaneous Use of Multiple Just In Time Compilers with a Java Virtual Machine, Ser. No. 09/204,513, Method and Apparatus for Automatic Service of JIT Compiler Generated Errors, Ser. No. 09/204,511, Method and Apparatus for Dynamically Selecting Bytecodes for Just in Time Compiling in a User's Environment, Ser. No. 09/204,976, A Method and Apparatus for Dynamic Selection of which Bytecodes should be Just In Time Compiled, Ser. No. 09/204,519, JIT/Compiler Java Language Extensions to Enable Field Performance and Serviceability, Ser. No. 09,204,968, Dynamic Selection/Definition of which Class/Methods should or should not be JIT'ed Using Information Stored in a JAR File, Ser. No. 09/204,975, and Method and Apparatus for Dynamic Selection of Instructions for Compiling Using Tags, Ser. No. 09/204,516, all of which are field even date hereof, assigned to the same assignee, and incorporated herein by reference.
1. Technical Field
The present invention relates generally to an improved data processing system and in particular to an improved method and apparatus for processing a method in a Java virtual machine. Still more particularly, the present invention relates to a method and apparatus for selectively controlling just in time compilation of a method.
2. Description of Related Art
Java is an object oriented programming language and environment focusing on defining data as objects and the methods that may be applied to those objects. Java is designed to solve a number of problems in modern programming practice. Java is able to support applications for many types of data processing systems, which may contain a variety of central processing units and operating systems architectures. To enable a Java application to execute on different types of data processing systems, a compiler typically generates an architecture-neutral file format—the compiled code is executable on many processors, given the presence of the Java run time system. The Java compiler generates bytecode instructions that are non-specific to a particular computer architecture. A bytecode is a machine independent code generated by the Java compiler and executed by a Java interpreter. A Java interpreter is a module that alternately decodes and executes a bytecode. The decoding of the bytecode places the instruction into an executable form for the computer on which the code is to be executed. Then, the instruction is executed by the computer. These bytecode instructions are designed to be easy to interpret on any machine and easily translated on the fly into native machine code.
The Java virtual machine (JVM) is a virtual computer component that resides only in memory. A JVM includes components necessary to run a program on a computer, including an interpreter. The JVM allows Java programs to be executed on different platforms as opposed to only the one platform for which the code was compiled. Java programs are compiled for the JVM. In this manner, Java is able to support applications for many types of data processing systems, which may contain a variety of central processing units and operating systems architectures. To enable a Java application to execute on different types of data processing systems, a compiler typically generates an architecture-neutral file format -the compiled code is executable on many processors, given the presence of the Java run time system. The Java compiler generates bytecode instructions that are nonspecific to a particular computer architecture. A bytecode is a machine independent code generated by the Java compiler and executed by a Java interpreter.
When extra speed in executing a Java program or applets is needed, a just in time (JIT) compiler may be used to translate bytecodes for a method or class into native machine instructions before executing them. Typically, this compilation only occurs once per method. Some JIT compilers may compile entire classes, rather than one method at a time.
In some situations, a JIT compiler may produce invalid results when compiling bytecodes from a given method of a class into instructions or machine code for execution on the computer. These errors do not occur if the code is not just in time compiled. Typically, these errors in execution of native instructions occur as a result of faulty logic in the JIT compiler. Currently, a mechanism for avoiding these errors is unavailable.
Therefore, it would be advantageous to have an improved method and apparatus for just in time compiling of methods.
SUMMARY OF THE INVENTION
The present invention provides a method and apparatus for executing bytecodes. Bytecodes are received for execution and a determination is made as to whether the bytecodes should be compiled. The bytecodes are sent to a just in time compiler responsive to a determination that the method should be compiled. The bytecodes form a method, and the method is sent to an interpreter, responsive to an absence of a determination that the method should be compiled.
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Beadle Bruce Anthony
Brown Michael Wayne
Paolini Michael Anthony
Rothert Douglas Scott
Chavis John Q.
International Business Machines - Corporation
LaBow Jeffrey S.
Nichols Michael R.
Powell Mark R.
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