Method and apparatus for resolving data references in generated code

• US RE38,104 E1
• Filed: 03/03/1999
• Issued: 04/29/2003
• Est. Priority Date: 12/22/1992
• Status: Expired due to Term

• Current Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Gosling, James
• Primary Examiner(s): Heckler, Thomas M.
• Application Number:
  US09/261,970
• Time in Patent Office: 1,518 Days
• Field of Search: 717/2, 717/5, 717/7, 717/8, 717/106-108, 717/114, 717/116, 717/146-147
• US Class Current: 717/140
• CPC Class Codes: G06F 8/41 Compilation
• CPC Class Codes: G06F 8/447 Target code generation
• CPC Class Codes: G06F 8/54 Link editing before load time
• CPC Class Codes: G06F 9/44521 Dynamic linking or loading; Link editing at or after load time, e.g. Java class loading
• CPC Class Codes: G06F 9/45508 Runtime interpretation or emulation, e g. emulator loops, bytecode interpretation

Abstract

A hybrid compiler-interpreter comprising a compiler for “compiling” source program code, and an interpreter for interpreting the “compiled” code, is provided to a computer system. The compiler comprises a code generator that generates code in intermediate form with data references made on a symbolic basis. The interpreter comprises a main interpretation routine, and two data reference handling routines, a dynamic field reference routine for handling symbolic references, and a static field reference routine for handling numeric references. The dynamic field reference routine, when invoked, resolves a symbolic reference and rewrites the symbolic reference into a numeric reference. After re-writing, the dynamic field reference routine returns to the main interpretation routine without advancing program execution to the next instruction, thereby allowing the rewritten instruction with numeric reference to be reexecuted. The static field reference routine, when invoked, obtain data for the program from a data object based on the numeric reference. After obtaining data, the static field reference routine advances program execution to the next instruction before returning to the interpretation routine. The main interpretation routine selectively invokes the two data reference handling routines depending on whether the data reference in an interaction in a symbolic or a numeric reference.

Claims

1. In a computer system comprising a program in source code form, a method for generating executable code for said program and resolving data references in said generated code, said method comprising the steps of:

a) generating executable code in intermediate form for said program in source code form with data references being made in said generated code on a symbolic basis, said generated code comprising a plurality of instructions of said computer system;

b) interpreting said instructions, one at a time, in accordance to a program execution control;

c) resolving said symbolic references to corresponding numeric references, replacing said symbolic references with their corresponding numeric references, and continuing interpretation without advancing program execution, as said symbolic references are encountered while said instructions are being interpreted; and

d) obtaining data in accordance to said numeric references, and continuing interpretation after advancing program execution, as said numeric references are encountered while said instruction are being interpreted;

said steps b) through d) being performed iteratively and interleaving.

2. The method as set forth in claim 1, wherein, said program in source code form is implemented in source code form of an object oriented programming language.

3. The method as set forth in claim 2, wherein said programming language is C.

4. The method as set forth in claim 2, wherein, said programming language is C++.

5. The method as set forth in claim 1, wherein, said program execution control is a program counter said continuing interpretation in step c) is achieved by performing said step b) after said c) without incrementing said program counter;

and

said continuing interpretation in said step d) is achieved by performing said step b) after said d) after incrementing said program counter.

14. The method of claim 3, wherein said substep of storing said numerical reference comprises the substep of replacing said symbolic reference with said numerical reference.

15. The method of claim 3, wherein said step of resolving said symbolic reference further comprises the substep of executing said instruction containing said symbolic reference using the stored numerical reference.

16. The method of claim 3, wherein said step of resolving said symbolic reference further comprises the substep of advancing program execution control after said substep of executing said instruction containing said symbolic reference.

6. In a computer system comprising a program in source code form, an apparatus for generating executable code for said program and resolving data references in said generated code, said apparatus comprising:

a) compilation means for receiving said program in source code form and generating executable code in intermediate form for said program in source code form with data references being made in said generated code on a symbolic basis, said generated code comprising a plurality of instructions of said computer system;

b) interpretation means for receiving said generated code and interpreting said instructions, one at a time;

c) dynamic reference handling means coupled to said interpretation means for resolving said symbolic references to corresponding numeric references, replacing said symbolic references with their corresponding numeric references, and continuing interpretation by said interpretation means without advancing program execution, as said symbolic references are encountered while said instructions are being interpreted by said interpretation means; and

d) static reference handling means coupled to said interpretation means for obtaining data in accordance to said numeric references, and continuing interpretation by said interpretation means after advancing program execution, as said numeric references are encountered while said instruction are being interpreted by said interpretation means;

said interpretation means, said dynamic reference handling means, and said static reference handling means performing their corresponding functions iteratively and interleavingly.

7. The apparatus as set forth in claim 6, wherein, said program in source code form is implemented in source code form of an object oriented programming language.

8. The apparatus as set forth in claim 7, wherein, said programming language is C.

9. The apparatus as set forth in claim 7, wherein, said programming language is C++.

10. The apparatus as set forth in claim 6, wherein, and program execution control is a program counter.

11. An apparatus comprising:

12. A computer-readable medium containing instructions for controlling a data processing system to perform a method for interpreting intermediate form object code comprised of instructions, certain of said instructions containing one or more symbolic references, said method comprising the steps of:

13. A computer-implemented method for executing instructions, certain of said instructions containing one or more symbolic references, said method comprising the steps of:

17. In a computer system comprising a program, a method for executing said program comprising the steps of:

18. A computer-implemented method for executing program operations, each operation being comprised of a set of instructions, certain of said instructions containing one or more symbolic references, said method comprising the steps of:

19. A memory for use in executing a program by a processor, the memory comprising:

20. A computer-implemented method comprising:

21. A data processing system, comprising:

22. An apparatus comprising:

23. A computer-implemented method, comprising:

24. A computer-implemented method for executing a program comprised of bytecodes, the method comprising:

25. A data processing system, comprising:

26. A computer program product containing instructions for causing a computer to perform a method for executing a program comprised of bytecodes, the method comprising:

27. A computer-implemented method comprising:

28. A data processing system, comprising:

29. A computer program product containing instructions for causing a computer to perform a method, the method comprising:

30. A computer-implemented method comprising:

31. A data processing system, comprising:

32. A computer program product containing control instructions for causing a computer to perform a method, the method comprising:

33. A computer-implemented method, comprising:

34. A data processing system, comprising:

35. A computer program product containing control instructions for causing a computer to perform a method, the method comprising:

36. A computer-implemented method for executing a program comprised of bytecodes, the method comprising:

37. A data processing system, comprising:

38. A computer program product containing instructions for causing a computer to perform a method for executing a program comprised of bytecodes, the method comprising:

39. A computer-implemented method comprising:

40. A data processing system, comprising:

41. A computer program product containing control instructions for causing a computer to perform a method, the method comprising: