Unisys Corporation

G Lawrence Krablin

Andrew T Jennings

William Stratton

Timothy Neilson Fender

Stephen R Bartels

An intermediate representation of sequences of instructions for a stacked based computer is a code graph using a numbering method on the nodes of the graph, along with a set of relations among the nodes, to determine, in a single pass, the independence of each node or sub-graph represented by the node. The numbering is a post-order that directly, by numerical comparison defines the relevant hierarchical relationships among sub-graphs. The sub-graph of a particular node may have one or more alias nodes that refers to target nodes, a target node being a node representing an argument which is the result of a previous program instruction. For a subgraph to be considered independent, any aliases generated by nodes within the subgraph must themselves be contained in it, and conversely, any aliases in the subgraph must have been generated by nodes also within it.

System and methods for determination of independence of sub-graphs in a graph-based intermediate representation of program instructions

An emulation system, computer program product, and method for emulating the execution of a target program comprising instructions of an instruction set of a target computer on a host computer having a different instruction set operate by performing a static translation of the instructions of the target program into a series of instructions of an intermediate instruction set, the intermediate instruction set being optimized for interpretation on the host computer, and then executing the series of instructions of the intermediate instruction set by interpretation on the host computer.

System, computer program product, and methods for emulation of computer programs

A method, a translator, and a computer-readable medium for translating compiled programming code from a first code state to a second code state are disclosed. The programming code in the first state has a plurality of basic blocks, where each basic block has a set of instructions. At least one basic block ends in a dynamic branch, the dynamic branch being a transfer to one of a set of destinations based on a calculation of a destination address. The plurality of basic blocks in the first state of the programming code are identified, as are links between the identified basic blocks. A control flow graph (CFG) of the programming code is then constructed based on the identified basic blocks and identified links, where the CFG is in a preliminary form. At least one basic block ending in a dynamic branch is identified, and all identified basic blocks that lead to the dynamic branch are explored, based on the CFG, as far back as is necessary to fully determine a set of destination addresses for the dynamic branch. The set of destination addresses defines the set of destinations from the dynamic branch. Such set of destinations is examined to identify a branch table, and the CFG is updated to reflect the set of destinations and the identified branch table. The programming code is then translated from the first state to the second state based at least in part on the updated CFG.

Determining destinations of a dynamic branch

An emulation system functions to translate instructions comprising a target application of a target system into corresponding instructions native to a host system and executes the instructions on the host system. During execution, the emulation system encounters target disk read/write operations. As the memory architectures of the host and target computer systems differ, the data in host memory is conformed to a target memory format when data in keyboard memory buffer is processed. Also, the host and target disk controllers cause storage of data on diskettes in differing byte orders. However, the emulation system performs disk/read write operations without byte-reversal prior to disk-write or subsequent to disk read operations. Thus, the host does not produce storage media having data conforming to that of target storage media. However, despite this drawback, the emulation system strikes a favorable balance between the need for precise replication of target application functionality on the one hand, and the importance of overall emulation system performance on the other.

Method for enhanced I/O in an emulated computing environment

A first dynamic link library (DLL) of a first computing environment, which exports one or more procedures that an application program executing in the first computing environment can call, is replaced with a second DLL that executes in a second computing environment, in a manner that is transparent to the calling application. A source code skeleton of the second DLL is automatically generated based on information contained in a directory of the compiled object code of the first DLL. The exported procedures of the second DLL have interfaces that are identical (from the perspective of the calling application) to the interfaces of the corresponding exported procedures of the first DLL, but the exported procedures of the second DLL comprise native code of the second computing environment. The calling application executing in the first computing environment is the linked dynamically to the exported procedures of the second DLL in the second computing environment in a manner that is transparent to the calling application.

METHOD, APPARATUS, AND COMPUTER PROGRAM PRODUCT FOR REPLACING A DYNAMIC LINK LIBRARY (DLL) OF A FIRST COMPUTING ENVIRONMENT WITH A DLL OF A SECOND COMPUTING ENVIRONMENT THAT CAN BE INVOKED FROM THE FIRST COMPUTING ENVIRONMENT IN A TRANSPARENT MANNER

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Downingtown, PA, United States of America

G Lawrence Krablin