Method of controlling the execution of object-oriented programs

• US 5,093,914 A
• Filed: 12/15/1989
• Issued: 03/03/1992
• Est. Priority Date: 12/15/1989
• Status: Expired due to Term

• Current Assignee: American Telephone & Telegraph Company (AT&T, Inc.), Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Original Assignee: AT&T, Inc.
• Inventors: Coplien, James O., Williams, Thomas V.
• Primary Examiner(s): Fleming, Michael R.
• Assistant Examiner(s): AUVE, GLENN ALLEN
• Application Number:
  US07/451,390
• Time in Patent Office: 809 Days
• Field of Search: 364/200, 364/275.5, 364/900, 371/19, 371/12, 371/13
• US Class Current: 717/129
• CPC Class Codes: G06F 11/3644 by instrumenting at runtime

Abstract

A method used by a digital computer in controlling execution of an object-oriented program to effect a defined action, e.g., stopping the program, when a specified virtual function is invoked on a specified object during execution of the program. A breakpoint address is determined at run time, advantageously after the specified object is created in accordance with execution of the program. The breakpoint address determination is not based solely on symbol table, pre-execution, information, but in addition on information generated in conjunction with the creation of the specified object. The breakpoint is inserted while program execution is stopped at an intermediate program point after the specified object is created. After program execution is resumed and the specified virtual function is invoked in accordance with the program, the breakpoint fires. However, the defined action is performed only in response to determining that the firing occurred on the specified object.

Claims

1. A method for use by a digital computer in controlling execution of an object-oriented program to effect a defined action when a specified virtual function is invoked on a specified object during execution of said program, said method comprising,

initiating execution of said program,

creating said specified object in accordance with execution of said program,

after said creating, determining an address of a function that is called when said specified virtual function is invoked on said specified object, and

inserting a breakpoint at said determined address of a function.

2. A method in accordance with claim 1 further comprising

after said creating and before said determining, stopping execution at an intermediate point of said program,

after said inserting, resuming execution of said program from said intermediate point,

detecting a firing of said breakpoint,

in response to detecting said firing, determining whether said firing occurred on said specified object, and

in response to determining that said firing occurred on said specified object, performing said defined action.

3. A method in accordance with claim 2 further comprising

after said resuming and before said detecting, invoking said specified virtual function on said specified object in accordance with execution of said program.

4. A method in accordance with claim 2 wherein said action is defined by default.

5. A method in accordance with claim 2 wherein said action comprises stopping execution of said program.

6. A method in accordance with claim 2 wherein said action is defined by a user as part of a request to effect said defined action when said specified virtual function is invoked on said specified object.

7. A method in accordance with claim 1 further comprising

after said creating, selecting, in accordance with execution of said program and as a function of the class of said specified object, said function that is called when said specified virtual function is invoked on said specified object.

8. A method in accordance with claim 1 wherein said determining comprises

obtaining an address of said specified object, said method further comprising

after said creating and before said determining, stopping execution at an intermediate point of said program,

storing an entry in a breakpoint table, said entry defining said determined address of a function and said obtained address of said specified object for said breakpoint,

after inserting said breakpoint, resuming execution of said program from said intermediate point,

detecting a firing of a breakpoint,

in response to detecting said firing, ascertaining an address of said detected firing of a breakpoint and an address of a present object,

when said ascertained address of said detected firing of a breakpoint and present object address respectively correspond to said determined address of a function and object address of said entry in said breakpoint table, performing said defined action.

9. A method in accordance with claim 1 wherein said determining comprises

obtaining an address and base type of said specified object,

using said obtained address and base type of said specified object, locating a virtual function table for said specified object and

obtaining said determined address of a function as an address from said virtual function table that maps, via a predefined address to function mapping, into said specified virtual function.

10. A method in accordance with claim 1 further comprising before said initiating, compiling said program.

11. A method in accordance with claim 10 wherein said compiling comprises

generating a symbol table for said program, said symbol table defining an address and a type for each of a plurality of variables of said program, one of said variables being a pointer to said specified object.

12. A method in accordance with claim 11 wherein said determining comprises

determining from said symbol table an address and a type of said pointer variable,

reading a contents of said determined address of said pointer variable to obtain an address of said specified object,

using said determined type of said pointer variable and said obtained address of said specified object, locating a virtual function table for said specified object, said virtual function table containing addresses for virtual functions,

obtaining said determined address of a function as an address from said virtual function table that maps, via a predefined address to function mapping, into said specified virtual function.

13. A method in accordance with claim 1 wherein said program is a C++ program.

14. A method for use by a digital computer in controlling execution of an object-oriented program, said method comprising

compiling said program,

after said compiling, initiating execution of said program,

stopping execution at an intermediate point of said program,

after stopping execution and in response to a request to effect a defined action when a specified virtual function is invoked on a specified object during execution of said program, determining an address of a function that is called when said specified virtual function is invoked on said specified object, and

inserting a breakpoint at said determined function address.

15. A method in accordance with claim 14 further comprising

after inserting said breakpoint, resuming execution of said program from said intermediate point,

detecting a firing of said breakpoint,

in response to detecting said firing, determining whether said firing occurred on said specified object, and

in response to determining that said firing occurred on said specified object, performing said defined action.

16. A method for use by a digital computer in effecting a defined action when a specified function is invoked on a specified object during execution of an object-oriented program, said method comprising

determining an address of a function that is called when said specified function is invoked on said specified object,

inserting a breakpoint at said determined address of a function,

obtaining an address of said specified object,

storing an entry in a breakpoint table, said entry defining said determined address of a function and said obtained address of said specified object for said breakpoint,

in response to detecting firing of a breakpoint, ascertaining an address of said detected firing of a breakpoint and an address of a present object and

when the ascertained breakpoint address and present object address respectively correspond to the address of a function and object address of said entry in said breakpoint table, performing said defined action.

17. A method in accordance with claim 16 wherein said specified function is a non-virtual function and said determining comprises

determining an address of said specified function.

18. A method in accordance with claim 16 wherein said specified function is a virtual function, said method further comprising the following steps performed prior to said determining:

compiling said program,

after said compiling, initiating execution of said program and

stopping execution at an intermediate point of said program after creation of said specified object.

19. A method in accordance with claim 16 wherein said specified function is any one of a plurality of functions of said program including both virtual functions and non-virtual functions.

20. A method for use by a digital computer in controlling execution of an object-oriented program to effect a defined action when a specified function is invoked with a specified argument during execution of said program, said method comprising

initiating execution of said program,

creating an object in accordance with execution of said program,

after said creating, determining an address of a function that is called when said specified function is invoked with said specified argument and said specified argument is associated with said object, and

inserting a breakpoint at said determined address of a function.

21. A method in accordance with claim 20 further comprising

after said creating and before said determining, stopping execution at an intermediate point of said program,

after said inserting, resuming execution of said program from said intermediate point,

detecting a firing of said breakpoint,

in response to detecting said firing, determining whether said firing occurred on said object, and

in response to determining that said firing occurred on said object, performing said defined action.