Method and apparatus for debugging optimized code

• US 6,553,565 B2
• Filed: 04/23/1999
• Issued: 04/22/2003
• Est. Priority Date: 04/23/1999
• Status: Active Grant

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Vick, Christopher A., Paleczny, Michael H., Click, Clifford N. Jr.
• Primary Examiner(s): Morse, Gregory
• Assistant Examiner(s): Vo, Ted T.
• Application Number:
  US09/298,692
• Publication Number:
  US 20020100018A1
• Time in Patent Office: 1,460 Days
• Field of Search: 717/4, 717/5, 717/7, 717/8, 717/9, 717/11, 717/124-133, 717/145-147
• US Class Current: 717/129
• CPC Class Codes: G06F 11/3628 of optimised code optimisation G06F8/443
• CPC Class Codes: G06F 11/3636 by tracing the execution of the program
• CPC Class Codes: G06F 11/3644 by instrumenting at runtime

Abstract

Methods and apparatus for providing a substantially full set of state information to a debugger, without significantly compromising system performance, in order to debug optimized computer program code are disclosed. According to one aspect of the present invention, a method for obtaining information associated with program code includes adding a segment of code, which includes a representation that is effectively not used after it is computed, to the program code. Debugging code is added in proximity to the segment of code, and machine code is generated from the program code. The machine code includes a break point that is associated with the debugging code, and includes an instruction at the breakpoint. Finally, the method includes replacing the instruction at the break point with a branch instruction that is arranged to cause the debugging code to execute.

Claims

1. A computer-implemented method for obtaining information associated with program code, the computer-implemented method comprising:

adding a segment of code to the program code, the segment of code including a representation associated with a computation, the representation being arranged to be substantially unprocessed;

adding debugging code in proximity to the segment of code;

optimizing the program code;

generating machine code associated with the optimized program code, the machine code including a break point and an associated instruction, the break point being associated with the debugging code; and

replacing the instruction at the break point with a branch instruction, the branch instruction being arranged to cause the debugging code to execute, wherein when the debugging code executes, information associated with the representation is obtained.

2. A computer-implemented method as recited in claim 1 wherein adding debugging code in proximity to the segment of code includes integrating the debugging code into the segment of code.

3. A computer-implemented method as recited in claim 1 wherein the segment of code is associated with a program loop.

4. A computer-implemented method as recited in claim 3 wherein adding debugging code in proximity to the segment of code includes integrating the debugging code into the program loop.

5. A computer-implemented method as recited in claim 4 wherein the debugging code includes code that calls a debugging function arranged to debug the program code.

6. A computer-implemented method as recited in claim 4 wherein the debugging code includes code that calls a de-optimizing function arranged to de-optimize the program code.

7. A computer-implemented method as recited in claim 1 further including:

converting the program code into an internal representation, wherein generating the machine code associated with the program code includes generating the machine code from the internal representation.

8. A computer-implemented method as recited in claim 1 wherein generating the machine code associated with the program code includes generating machine code associated with the representation.

9. A computer-implemented method as recited in claim 8 further including:

executing the debugging code, wherein executing the debugging code is arranged to provide information associated with the representation.

10. A computer-implemented method as recited in claim 9 wherein the debugging code is executed by one of a debugger and a deoptimizer.

11. A computer apparatus for obtaining information associated with program code, the computer apparatus comprising:

a programming interface arranged to add a segment of code to the program code, the segment of code including a representation associated with a computation, the representation being arranged to be substantially unprocessed, the programming interface further being arranged to add debugging code in proximity to the segment of code;

an optimizer arranged to optimize the program code;

a machine code generator arranged to generate machine code associated with the optimized program code, the machine code including a break point, the break point being associated with the debugging code, wherein the machine code further includes a instruction at the break point location; and

a decompiler arranged to replace the instruction with a branch instruction, wherein the branch instruction is arranged to cause the debugging code to execute.

12. A computer apparatus according to claim 11 wherein the programming interface arranged to add debugging code in proximity to the segment of code is further arranged to integrate the debugging code into the segment of code.

13. A computer apparatus according to claim 11 wherein the segment of code is associated with a program loop, and the programming interface arranged to debugging code in proximity to the segment of code is further arranged to integrate the debugging code into the program loop.

14. A computer apparatus according to claim 11 further including:

a code converter arranged to convert the program code into an internal representation, wherein the machine code generator is arranged to generate the machine code from the internal representation.

15. A computer apparatus according to claim 14 further including:

a debugger arranged to execute the debugging code, wherein executing the debugging code is arranged to provide information associated with the representation.

16. A computer apparatus according to claim 14 further including:

a deoptimizer arranged to execute the debugging code, wherein executing the debugging code is arranged to provide information associated with the program representation.

17. A computer program product for obtaining information associated with a particular set of instructions, the computer program product comprising:

computer code that includes a representation associated with a computation, the representation being arranged to be substantially unprocessed, wherein the computer code includes debugging code;

computer code for generating machine code associated with the computer code that includes the representation and the debugging code, the machine code including a break point, the break point being associated with the debugging code, wherein the machine code further includes a instruction;

computer code for replacing the instruction with a branch instruction, the branch instruction being arranged to cause the debugging code to execute, wherein causing the debugging code to execute provides information associated with the representation; and

a computer-readable medium that stores the program codes.

18. A computer program product according to claim 17 wherein the computer-readable medium is one selected from the group consisting of a data signal embodied in a carrier wave, a CD-ROM, a hard disk, a floppy disk, a tape drive, and flash memory.

19. A computer-implemented method for obtaining information associated with program code, the computer-implemented method comprising:

adding a call to a subroutine, the subroutine being associated with the program code, the call to the subroutine including a plurality of arguments, wherein at least one of the plurality of arguments is a reference to a representation associated with a computation, the representation being unused with respect to the program code and the subroutine; and

generating machine code associated with the program code, wherein generating the machine code includes substantially transforming the call to the subroutine into debugging code.

20. A computer-implemented method for debugging optimized code, the computer-implemented method comprising:

generating a higher-level program representation, the higher-level program representation including a loop section, the loop section having an associated counter value, wherein the loop section includes a segment of break point code;

optimizing the higher-level program representation, wherein optimizing the higher-level program representation includes converting the higher-level program representation into lower-level code, the lower-level code including a section associated with the debugging code and a instruction;

replacing the instruction with a branch instruction, branch instruction being arranged to cause the section associated with the debugging code to execute; and

executing the branch instruction, wherein executing branch instruction causes the section associated with the debugging code to execute and to provide information associated with the counter value.