Emulation method and computer system

• US 20070271084A1
• Filed: 05/11/2007
• Published: 11/22/2007
• Est. Priority Date: 05/17/2006
• Status: Active Grant

• Current Assignee: NEC Platforms, Ltd. (NEC Corporation)
• Original Assignee: NEC Computertechno Ltd. (NEC Corporation)
• Inventors: Fujihara, Tsutomu
• Granted Patent: US 8,392,893 B2
• Time in Patent Office: Days
• US Class Current: 703/26
• CPC Class Codes: G06F 9/45504 Abstract machines for programme code execution, e.g. Java virtual machine [JVM], interpreters, emulators

Abstract

The computer system of the present invention emulates target instructions. The computer system includes a processing unit for branching to collective emulation coding for emulating plural of target instructions created beforehand collectively, thereby processing those instructions collectively according to the coding when those target instructions are combined so as to be processed collectively and a memory for storing the collective emulation coding.

Claims

1. An emulation method, comprising the step of:

branching to coding for a collective processing of a plurality of target instructions created beforehand when those target instructions are combined so as to be processed collectively, thereby executing said collective processing according to said coding.

2. The emulation method according to claim 1, further comprising:

creating beforehand individual emulation coding for emulating said plurality of target instructions individually, collective emulation coding for emulating said plurality of target instructions collectively, and an instruction combination table denoting whether or not it is possible to execute said collective emulation processing for each combination of said target instructions;

fetching and decoding said plurality of target instructions, then determining whether or not it is possible to execute said collective emulation for said plurality of target instructions by referring to said instruction combination table;

branching to said collective emulation coding when those instructions are combined so as to be processed collectively, then emulating those target instructions collectively according to said coding; and

branching to said individual emulation coding when those instructions are not combined so as to be processed collectively, then emulating one target instruction according to said coding.

3. The emulation method according to claim 1, further comprising:

creating beforehand said individual emulation coding, said collective emulation coding, and a process branch table for denoting a relationship between information for identifying said plurality of target instructions and information denoting a branch destination of said collective emulation coding;

reading said identifying information and branching to said collective emulation coding when it is determined by referring to said process branch table that said identifying information is registered in said table, then executing said collective emulation according to said coding; and

fetching and decoding one target instruction when said identifying information is not registered in said table, then branching to said individual emulation coding to process said one target instruction according to said coding.

4. The emulation method according to claim 3, wherein said method further comprises executing simultaneously both of a processing for reading said identifying information, as well as a processing for fetching and decoding said one target instruction.

5. The emulation method according to claim 1, further comprising:

creating beforehand said individual emulation coding, said collective emulation coding, and an instruction combination history table for denoting a relationship between a combination of a plurality of target instructions processed collectively and information denoting a branch destination of said collective emulation coding;

fetching and decoding a plurality of target instructions and branching to said collective emulation coding when said combination of said plurality of target instructions processed collectively is registered in said instruction combination history table, then processing those instructions collectively according to said coding; and

branching to said individual emulation coding when said combination is not registered in said table, then emulating said one target instruction according to said coding.

6. The emulation method according to claim 5, further comprising:

creating beforehand an instruction combination table for denoting whether or not it is possible to execute collective emulation for each combination of target instructions;

determining whether or not it is possible to process said plurality of target instructions by referring to said instruction combination table when said combination is not registered in said table; and

branching to said collective emulation coding when said combination can be subjected to said collective emulation, then processing those instructions collectively according to said coding.

7. The emulation method according to claim 6, wherein said method further comprises executing simultaneously both of a processing for fetching and decoding a plurality of target instructions to be executed next and a processing for determining whether or not it is possible to process said plurality of target instructions collectively by referring to said instruction combination history table when a combination of said decoded plurality of target instructions is not registered in said table while said plurality of target instructions are processed according to said collective emulation coding or said individual emulation coding.

8. The emulation method according to claim 7, wherein said method uses different processors for executing the different steps of:

branching to said collective emulation coding or said individual emulation coding; and

fetching and decoding a plurality of target instructions to be executed next, then determining whether or not it is possible to process said plurality of target instructions collectively by referring to said instruction combination table when said combination of said decoded target instructions is not registered in said instruction combination history table.

9. The emulation method according to claim 7, further comprising:

rewriting said plurality of target instructions to non-used instruction codes when a plurality of target instructions to be executed next can be processed collectively.

10. A computer system, comprising:

a processing unit for branching to collective emulation coding for emulating a plurality of target instructions created beforehand collectively when those instructions are combined so as to be processed collectively, then processing those instructions collectively according to said coding; and

a memory for storing said collective emulation coding.

11. The computer system according to claim 10,

wherein said memory stores individual emulation coding for emulating target instructions created beforehand individually, collective emulation coding for emulating said plurality of target instructions collectively, and an instruction combination table for denoting whether or not it is possible to execute said collective emulation for each combination of said target instructions,

wherein said processing unit executes the processings for:

fetching and decoding a plurality of target instructions and determining whether or not it is possible process those instructions collectively by referring to said instruction combination table;

branching to said collective emulation coding when those target instructions are combined so as to be processed collectively, then processing those instructions collectively according to said coding; and

branching to said individual emulation coding when said instructions are not combined so as to be processed collectively, then processing one target instruction according to said coding.

12. The computer system according to claim 10,

wherein said memory stores a process branch table for denoting said individual emulation coding, said collective emulation coding, and a relationship between information for identifying said plurality of target instructions and information of a branch destination of said collective emulation coding, and

wherein said processing unit reads said identifying information and branches to said collective emulation coding when it is determined by referring to said process branch table that said identifying information is registered in said table, then branching to said collective emulation coding to process those instructions collectively according to said coding or fetches and decodes one target instruction when said identifying information is not stored in said table, then branching to said individual emulation coding to process said one target instruction according to said coding.

13. The computer system according to claim 12,

wherein said processing unit executes both of a processing for reading said identifying information and a processing for fetching and decoding said one target instruction simultaneously.

14. The computer system according to claim 10,

wherein said memory stores an instruction combination history table for denoting said individual emulation coding, said collective emulation coding, and a relationship between each combination of a plurality of target instructions processed collectively and information denoting a branch destination to said collective emulation coding, and

wherein said processing unit fetches and decodes a plurality of target instructions, then branching to said collective emulation coding when said combination of said plurality of target instructions is registered in said instruction combination history table, then processing those instructions collectively according to said coding, and

branching to said individual emulation coding when said combination is not registered in said table, then processing one target instruction according to said coding.

15. The computer system according to claim 14,

wherein said memory stores an instruction combination table for denoting whether or not it is possible to execute said collective emulation for each combination of said target instructions created beforehand, and

wherein said processing unit refers to said instruction combination table to determine whether or not it is possible to process said plurality of target instructions collectively when said combination of said plurality of decoded target instructions is not registered in said instruction combination history table;

and branches to said collective emulation coding when those instructions are combined so as to be processed collectively, then processing those instructions collectively according to said coding.

16. The computer system according to claim 15,

wherein said processing units executes simultaneously both of a processing for fetching and decoding a plurality of target instructions to be processed next and a processing for referring to said instruction combination table to determine whether or not it is possible to process those instructions collectively when said combination of said decoded target instructions is not registered in said table while said plurality of target instructions are processed according to said collective emulation coding or said individual emulation coding.

17. The computer system according to claim 16,

wherein said processing unit further includes:

a first processor for executing a processing according to said collective emulation coding or said individual emulation coding; and

a second processor for fetching and decoding a plurality of target instructions to be processed next, then referring to said instruction combination table to determine whether or not it is possible to process said plurality of target instructions collectively when said combination of said plurality of decoded target instructions is not registered in said instruction combination history table.

18. The computer system according to claim 16,

wherein said processing unit rewrites said plurality of target instructions to non-used instruction codes when said combination of said plurality of target instructions to be processed next can be subjected to said collective emulation.

19. A program for enabling a computer to execute emulation,

wherein said program branches to collective emulation coding for emulating a plurality of target instructions created beforehand collectively when said target instructions are combined so as to be processed collectively, then enabling said computer to process those instructions collectively according to said coding.

20. The program according to claim 19,

wherein said program enables said computer to execute the processings of:

fetching and decoding a plurality of target instructions, then referring to an instruction combination table for denoting whether or not it is possible to execute collective emulation for each combination of said target instructions created beforehand to determine whether or not it is possible to process those instructions collectively;

branching to said collective emulation coding when said plurality of target instructions are combined so as to be processed collectively, then processing those instructions created beforehand collectively according to said coding; and

branching to said individual emulation coding for emulating one target instruction created beforehand when said target instructions are not combined so as to be processed collectively, then processing said one target instruction according to said coding.

21. The program according to claim 19,

wherein said program enables said computer to execute the processings of:

reading information for identifying said plurality of target instructions;

referring to a process branch table for denoting a relationship between said identifying information and a branch destination of said collective emulation coding;

branching to said collective emulation coding when said read identifying information is registered in said process branch table, then processing those instructions collectively according to said coding; and

fetching and decoding one target instruction created beforehand when said read identifying information is not registered in said process branch table, then branching to said individual emulation coding to process said one target instruction individually.

22. The program according to claim 21,

wherein said program enables said computer to execute simultaneously both of a processing for reading said identifying information and a processing for fetching and decoding said one target instruction.

23. The program according to claim 19,

wherein said program enables said computer to execute the processings of:

fetching and decoding a plurality of target instructions;

referring to said instruction combination history table for denoting a relationship between a combination of a plurality of target instructions created beforehand and processed collectively and information for denoting a branch destination of said collective emulation coding;

branching to said collective emulation coding to process those instructions collectively when said combination of said plurality of decoded target instructions is registered in said instruction combination history table; and

branching to said individual emulation coding to process said one target instruction created beforehand when said combination is not registered in said table.

24. The program according to claim 23,

wherein said program enables said computer to execute the processings of:

referring to said instruction combination table to determine whether or not it is possible to process said plurality of target instructions collectively when said combination of said plurality of decoded target instructions is not registered in said instruction combination history table for denoting whether or not it is possible to execute said collective emulation for each target instruction combination; and

branching to said collective emulation coding to process said target instructions collectively when said combination can be subjected to said collective emulation.

25. The program according to claim 24,

wherein said program enables said computer to execute simultaneously both of a processing for fetching and decoding a plurality of target instructions to be processed next and a processing for referring to said instruction combination table to determine whether or not it is possible to process said plurality of target instructions collectively when said combination of said decoded target instructions is not registered in said instruction combination history table while said plurality of target instructions are processed according to said collective emulation coding or said individual emulation coding.

26. The program according to claim 25,

wherein said program enables said computer to rewrite said plurality of target instructions to non-used instruction codes when a plurality of target instructions to be processed next can be processed collectively.