International Business Machines Corporation

T Mark W Bottomley

Peter Wiebe Burka

Aleksandr Kennberg

Olivier P Thomann

Nicholas J Doyle

Orlando E Marquez

Amey A Shirodkar

Automated injection of Java bytecode instructions for Java load time optimization via runtime checking with upcasts. Exemplary embodiments include a method including generating a stack for each of a plurality of bytecodes, generating a subclass configured to keep a history of instructions that have modified the stack, statically scanning a plurality of Java classes associated with the plurality of bytecodes to locate class file configurations and bytecode patterns that cause loading of additional classes to complete a verification of each of the classes in the plurality of Java classes, rewriting the bytecodes to delay the loading of the additional classes until required at a runtime, recording modifications that have been made to the stack by the instructions, and applying the modifications to each of the bytecodes in the plurality of bytecodes.

Systems, methods, and computer products for automated injection of java bytecode instructions for java load time optimization via runtime checking with upcasts

A source code file can be compiled to generate bytecode. During compilation, a first use of a local variable within a set of instructions of the source code can be detected. A local variable usage list can be examined for at least one inactive local variable in use by the set of instructions. An existence of an acceptable type pairing between a type descriptor corresponding to a local variable and a type descriptor of the local variable may be determined. When the acceptable type pairing exists, an index of the local variable array corresponding to the determined acceptable type pairing for the local variable can be reused. Otherwise, a new index can be assigned for the local variable. Compiling bytecode in this manner avoids extraneous class loads that would otherwise occur during a verification phase of the bytecode, which has still been optimized to reuse local variable slots.

Intelligent reuse of local variables during bytecode compilation

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Orleans, CA, United States of America

T Mark W Bottomley