Transitive Limited

International Business Machines Corporation

Jason Souloglou

Alasdair Rawsthorne

John Graham

John H Sandham

A method of dynamic real time translation of first program code written for a first programmable machine into second program code (target code) for running on a second programmable machine employing run time generation of an intermediate representation of the first program code. Upon first encountering a given portion of program code, only the target code necessary to execute that portion of program code under a prevailing set of entry conditions is initially generated and stored. When the same portion of program code is again encountered, a determination is made as to whether intermediate representation corresponding to a second subsequent set of conditions has been generated. If not, the target code necessary to execute the same portion of program code under that second set of conditions is generated.

Program code conversion

Program code conversion for program code referring to variable size registers

A method of dynamic real time translation of first program code written for a first programmable machine into second program code (target code) for running on a second programmable machine, the method employing run time generation of an intermediate representation of the first program code. Upon first encountering a given portion of program code, only the target code necessary to execute that portion of program code under a prevailing set of entry conditions is initially generated and stored. When the same portion of program code is again encountered, a determination is made as to whether intermediate representation corresponding to a second subsequent set of conditions has been generated. If not, the target code necessary to execute the same portion of program code under that second set of conditions is generated.

An execution apparatus () such as a user PC identifies that translation of generic code representation is required (e.g. Java bytecode included or referenced as part of a web page downloaded from a content provider ()), and requests a translation of the generic code representation from a remote translation apparatus (), i.e. a translation server. A translated native code version of the generic code representation specific to a particular execution environment () is identified and sent from the translation apparatus () immediately ready for native execution on the execution apparatus () at full native speed. This avoids perceived slow start-up and unresponsiveness associated with interpretation or compilation of generic code representation at the execution apparatus ().

Obtaining translation of generic code representation

Program code conversion for a register-based program code

A method for generating an intermediate representation of computer program code written for running on a programmable machine comprises: (i) generating a plurality of register objects for holding variable values to be generated by the program code; and (ii) generating a plurality of expression objects representing fixed values and/or relationships between said fixed values and said variable values according to said program code; said objects being organized into a branched tree-like network having all register objects at the lowest basic root or tree-trunk level of the network with no register object feeding into any other register object.

A method of handling exceptions for use in an emulator () performing program code conversion. Registers (X) of a subject machine () being emulated () are represented by a pair of abstract registers (X,X) on the target machine (), suitably using memory locations of the target machine and/or any available target registers. One of the pair (e.g., Reg X) holds a definitive value at entry into a section () of subject code () while the other (e.g., Reg X) holds a speculative value which is updated during translation and execution of that section of code. Exceptions are handled by recovering the conditions of the virtual subject machine () upon entry into the section of subject code () using the definitive version of each abstract register (i.e., Reg X). Advantageously, the function of the pair of registers (X,X) is alternated upon successful completion of each section of subject code () such that a definitive version of each register is always available for exception handling while avoiding time consuming copy and storing operations.

Exception handling method and apparatus for use in program code conversion

A method of dynamic real time translation of first program code written for a first programmable machine into second program code (target code) for running on a second programmable machine employing run time generation of an intermediate representation of the first program code. The intermediate representation is generated to include a combination of register objects and expression objects. Register objects represent abstract registers that provide a representation of the state of the first programmable machine based on expected effects of the instructions within the first program code, while expression objects represent elements, such as operations or sub-operations, of the instructions in the first program code. In the intermediate representation, a branched tree-like network is formed in which each register object serves as a basic root of the network and references expression objects to which they relate either directly or indirectly through references from other expression objects.

Register-based program code conversion

A program storage medium storing an emulation system for performing dynamic real time translation of first program code written for the first programmable machine into second program code (target code) for running on a second programmable machine employing run time generation of an intermediate representation of the first program code. Upon first encountering a given portion of program code, only the target code necessary to execute that portion of program code under a prevailing set of entry conditions is initially generated and stored. When the same portion of program code is again encountered, a determination is made as to whether intermediate representation corresponding to a second subsequent set of conditions has been generated. If not, the target code necessary to execute the same portion of program code under that second set of conditions is generated.

A combination of a first programmable machine and an emulation system operable to perform dynamic real time translation of first program code written for the first programmable machine into second program code (target code) for running on a second programmable machine employing run time generation of an intermediate representation of the first program code. Upon first encountering a given portion of program code, only the target code necessary to execute that portion of program code under a prevailing set of entry conditions is initially generated and stored. When the same portion of program code is again encountered, a determination is made as to whether intermediate representation corresponding to a second subsequent set of conditions has been generated. If not, the target code necessary to execute the same portion of program code under that second set of conditions is generated.

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Manchester, United Kingdom

Jason Souloglou