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AssigneeInternational Business Machines Corporation
InventorsAndrew Clement, Matthew Webster
Estimating the term…
The invention concerns the use of a Java JIT compiler to change the status of run-time determined software routines between being activated and deactivated in an application program. Conditional statements which are used at run-time to determine whether such a routine has been activated or deactivated are presented as discrete conditions that always evaluate to a known result by using an invariant flag in the compiled bytecode. The JIT compiler optimises an application program by excluding discrete condition checks. Consequently, if the branch of the discrete condition that will never execute includes a run-time determined software routine, then the routine will be excluded from the JIT compilation and will not form part of the JIT compiled native machine code. A run-time class or code replacement facility is used as a means of activating or deactivating a run-time determined software routine at run-time by changing the value of the invariant flag of said routine. Such a facility is provided by Sun Microsystems' Java programming language HotSwap class file replacement feature of its Java Platform Debugger Architecture (JPDA). International Business Machines (IBM) also provides a similar functionality called “Hot Code Replace” (HCR) for its “J9” JVM platform.
A method of changing a status of a run-time determined software routine between activated and deactivated, comprises the steps of:
A method as claimed in 2, wherein said final static Boolean parameter comprises a final static Boolean data type.
A method of just-in-time (JIT) compiling a Java class file comprises the steps of:
A method as claimed in 10, wherein the invariant flag comprises one of a final static Boolean parameter, a numerical test on an invariant field and a hard coded statement and wherein said step of utilising a run-time code replacement facility to change said invariant flag comprises changing a value of the Boolean parameter, changing the invariant field or replacing the hard coded statement by its converse.
A method of just-in-time (JIT) compiling a Java class file comprises the steps of:
A method as claimed in 14, wherein the invariant flag comprises one of a final static Boolean parameter, a numerical test on an invariant field and a hard coded statement and wherein said step of utilising a run-time code replacement facility to change said invariant flag comprises changing a value of the Boolean parameter, changing the invariant field or replacing the hard coded statement by its converse.
A Java Virtual Machine (JVM) arranged to carry out the method of changing a status of a run-time determined software routine between activated and deactivated, the JVM being arranged to carry out the steps of:
A JVM arranged to carry out the method of just-in-time (JIT) compiling a Java class file, the method comprising the steps of:
A JVM arranged to carry out the method of just-in-time (JIT) compiling a Java class file, the method comprising the steps of:
A Java just-in-time (JIT) compiler arranged to carry out the method of changing a status of a run-time determined software routine between activated and deactivated, the method comprising the steps of:
A Java JIT compiler for compiling a Java class file containing a run-time determined software routine, said JIT compiler being arranged to carry out the steps of:
A Java JIT compiler for compiling a Java class file containing a run-time determined software routine, said JIT compiler being arranged to carry out the steps of:
A computer program product in a computer readable medium for carrying out the method of changing a status of a run-time determined software routine between activated and deactivated, said method comprising the steps of:
A computer program product in a computer readable medium for carrying out the method of just-in-time (JIT) compiling a Java class file, the method comprising the steps of:
A computer program product in a computer readable medium for carrying out the method of just-in-time (JIT) compiling a Java class file, the method comprising the steps of:
Dependencies are inferred from the claim text.