Abstract: A computer implemented method, computer usable program code, and a data processing system for selecting a candidate implementation of a virtual overridden method for inlining into a calling method. A determination as to which implementation of a virtual overridden method to inline is made based on its relative “hotness” compared to the other implementations of the same method. The relative hotness can be inferred from the invocation count and sampling count that the virtual machine and the just-in-time compiler already collect for other purposes, that is, without collecting and storing of call-edge profiling information. When a method is being compiled and it is identified that the method contains a call to an overridden method, a candidate for inlining from among the implementations of the overridden method is selected based on relative hotness values. The candidate implementation of the overridden method is then inlined, with a guard, into the calling method.

Abstract: A method, system and computer program product for collecting profiling information during runtime of a multithreaded program. According to the method, a plurality of instructions of the program for execution in an application thread are first received; a plurality of variable size profiling records are then stored in a buffer assigned exclusively to the application thread during execution of the plurality of instructions; and the plurality of profiling records in the buffer are then processed. The program may be written in Java bytecode for execution in a Java virtual machine with the processing of profiling buffers performed by a component of a JIT compiler for insertion into a repository in internal JIT format, e.g. a hash table, for later optimization processing.

Abstract: The present invention provides a method, system and computer program product for optimizing computer program execution during class loading phase. As a code method of the program is received for compiling prior to execution, a check is performed whether program execution is in class loading phase. Program execution is in class loading phase where the class loading rate exceeds a pre-determined level during a pre-determined interval. If the program is in class loading phase, then compiling is reduced by lowering frequency of JIT compilation, lowering optimization level of just-in-time compilation, or a combination of the two. The code method may also be passed to an interpreter to be interpreted.

Abstract: Under the present invention, program code is examined (statically or dynamically) for characteristics indicative of a potential to generate multiple threads. If none are found, single threaded optimization(s) such as desynchronization, optimization of globals, etc., can be implemented. In addition, if the program code is later revealed to have the potential to generate multiple threads, the single threaded optimization(s) can be corrected to avoid incorrect execution.

Abstract: A method for compiler optimization particularly well suited to object-oriented language that permit dynamic class loading. The method permits the compiler optimization of code associated with a potentially polymorphic object that is a call parameter to a virtual procedure where the procedure is a candidate for devirtualization through inlining. The method includes steps for guarded devirtualizing of the procedure, insertion of code to ensure privatization of the object before the procedure is executed, creation of a guard assumptions associated with the object and application of known optimization techniques to the code associated with the object.