System, method and program product to optimize code during run time

• US 7,797,690 B2
• Filed: 03/15/2005
• Issued: 09/14/2010
• Est. Priority Date: 03/15/2005
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: O'Connell, Brian Marshall, Vaughan, Kevin Edward, Nesbitt, Richard Elderkin
• Primary Examiner(s): Dam; Tuan Q
• Assistant Examiner(s): Lee; Marina
• Application Number:
  US11/081,054
• Publication Number:
  US 20060212862A1
• Time in Patent Office: 2,009 Days
• Field of Search: 717/153
• US Class Current: 717/153
• CPC Class Codes: G06F 8/443 Optimisation
• CPC Class Codes: G06F 9/449 Object-oriented method invocation or resolution
• CPC Class Codes: G06F 9/45525 Optimisation or modification within the same instruction set architecture, e.g. HP Dynamo

Abstract

System, process and program product for optimizing a computer program during run time. During run time, a determination is made whether the computer program calls a method which includes a conditional evaluation of a variable which is fixed and the evaluation of the fixed variable does not result in anything productive being accomplished except to return to execution of the computer program. If so, the call to the method which includes the conditional evaluation is deleted from the computer program for subsequent iterations of the computer program. Consequently, the subsequent execution of the computer program will yield a same result as if the conditional evaluation was executed. If the evaluation of the fixed variable results in something productive being accomplished, the call to the method which includes the conditional evaluation is not deleted from the subsequent execution of the computer program.

Claims

1. A process for optimizing a computer program during run time, said computer program including a call to a first method, said first method including a call to a second method, said process comprising the steps of:

during run time, a processor of a computer determining if said second method includes a conditional evaluation of a variable which is fixed such that the execution of said second method does not result in anything productive being accomplished except to return to said first method, and

if so, deleting in said first method said call to said second method, and

if not, not deleting said call in said first method to said second method.

2. A process as set forth in claim 1 wherein said first method also includes instructions to compute an argument required for said call to said second method, and said second method includes a conditional evaluation of a variable which is fixed such that execution of said second method does not result in anything productive being accomplished except to return to said first method, and further comprising the step of deleting from said first method said instructions to compute said argument required for said call to said second method.

3. A process for optimizing a computer program during run time of the computer program, said process comprising executing a program tool on a processor of a computer during said run time of the computer program, said program tool stored in a memory of the computer, said computer program being object code configured to be executed on the processor, said object code having been previously compiled by a compiler from source code, said computer program comprising a sequence of program statements declared explicitly in the source code to be a method, said executing the program tool during said run time comprising:

fetching an instruction of the computer program;

said processor determining that the fetched instruction consists of a call to the method, said fetched instruction being comprised by program code of the computer program;

responsive to said determining that the fetched instruction consists of said call to the method, said processor determining that a program statement of the declared sequence of program statements of the method includes a conditional evaluation of a fixed variable, wherein a declaration statement appearing in the source code explicitly declares the fixed variable as having a fixed value, and wherein an assignment statement appearing in the source code assigns the fixed value to the fixed variable, and wherein the declaration statement and the assignment statement are different statements in the source code;

responsive to said determining that said program statement includes said conditional evaluation, said processor determining that an immediate return condition exits in the method such that an evaluation of the fixed variable results in an immediate return from the method to the program code without performance of any other program statement of the method; and

responsive to said determining that the immediate return condition exits, deleting from the computer program the fetched instruction that consists of the call to the method.

4. The process of claim 3,

wherein the program code comprises program code instructions that compute at least one argument for said call to the method in the fetched instruction, and

wherein said executing the program tool during said run time further comprises deleting the program code instructions comprised by the program code in response to said determining that the immediate return condition exits.

5. The process of claim 4, wherein the program tool performs both said deleting the call to the method and said deleting the program code instructions by rewriting the object code.

6. The process of claim 4, wherein said executing the program tool during said run time further comprises after said deleting the fetched instruction from the computer program and after said deleting the program code instructions comprised by the program code, performing a loop for processing multiple instructions of the computer program, said performing the loop consisting of:

ascertaining whether a next instruction of the multiple instructions exists;

responsive to said ascertaining, exiting the loop to terminate said processing multiple instructions if said ascertaining ascertains that said next instruction does not exist or getting the next instruction if said ascertaining ascertains that said next instruction exists;

responsive to said ascertaining that said next instruction exists, determining whether said next instruction consists of calling the method;

responsive to determining that said next instruction does not consist of said calling the method, executing said next instruction followed by looping back to said ascertaining; and

responsive to determining that said next instruction consists of said calling the method, processing the next instruction,

wherein said processing the next instruction comprises;

determining whether the method includes a conditional evaluation of a constant variable;

responsive to determining that the method does not include said conditional evaluation of a constant variable, looping back to said ascertaining;

responsive to determining that the method includes said conditional evaluation of a constant variable, determining whether an evaluation of the constant variable would result in immediately returning from the method;

responsive to determining that said evaluation of the constant variable would not result in said immediately returning from the method, performing said looping back to said ascertaining; and

responsive to determining that said evaluation of the constant variable would result in said immediately returning from the method, deleting said calling the method followed by performing said looping back to said ascertaining.

7. The process of claim 3,

wherein said executing the program tool during said run time comprises monitoring the program statements of the sequence of program statements while passing the object code to a run-time interpreter,

wherein the process comprises said run-time interpreter executing the object code during said run time, and

wherein said executing the program tool during said run comprises said deleting the fetched instruction from the computer program.

8. The process of claim 3, wherein the method called by the fetched instruction is a second method that is called by a first method, wherein the computer program comprises a set of programming instructions declared explicitly in the source code to be the first method, and wherein the set of programming instructions comprises the program code that comprises the fetched instruction.

9. A computer program product for optimizing a computer program during run time of the computer program, said computer program product comprising computer readable storage media and multiple program instructions to execute a program tool on a processor of a computer during said run time of the computer program, said program tool stored in a memory of the computer, said computer program being object code configured to be executed on the processor, said object code having been previously compiled by a compiler from source code, said computer program comprising a sequence of program statements declared explicitly in the source code to be a method, said multiple program instructions stored on the computer readable storage media, said multiple program instructions comprising:

first program instructions to fetch an instruction of the computer program;

second program instructions to determine that the fetched instruction consists of a call to the method, said fetched instruction being comprised by program code of the computer program;

third program instructions to determine, in response to prior execution of the second program instructions, that a program statement of the declared sequence of program statements of the method includes a conditional evaluation of a fixed variable, wherein a declaration statement appearing in the source code explicitly declares the fixed variable as having a fixed value, and wherein an assignment statement appearing in the source code assigns the fixed value to the fixed variable, and wherein the declaration statement and the assignment statement are different statements in the source code;

fourth program instructions to determine, in response to prior execution of the third program instructions, that an immediate return condition exits in the method such that an evaluation of the fixed variable results in an immediate return from the method to the program code without performance of any other program statement of the method; and

fifth program instructions to delete from the computer program, in response to prior execution of the fourth program instructions, the fetched instruction that consists of the call to the method.

10. The computer program product of claim 9,

wherein the program code comprises program code instructions to compute at least one argument for said call to the method in the fetched instruction, and

wherein to execute the program tool during said run time comprises to delete the program code instructions comprised by the program code in response to a determination having been made that the immediate return condition exits.

11. The computer program product of claim 10, wherein the program tool includes program tool instructions to delete the call to the method and to delete the program code instructions by rewriting the object code.

12. The computer program product of claim 10, wherein the multiple program instructions further comprises program instructions to perform a loop, after the fetched instruction has been deleted from the computer program and after the program code instructions comprised by the program code have been deleted, to process multiple instructions of the computer program, wherein the program instructions to perform the loop consist of instructions to perform the steps of:

ascertaining whether a next instruction of the multiple instructions exists;

responsive to said ascertaining, exiting the loop to terminate said processing multiple instructions if said ascertaining ascertains that said next instruction does not exist or getting the next instruction if said ascertaining ascertains that said next instruction exists;

responsive to said ascertaining that said next instruction exists, determining whether said next instruction consists of calling the method;

responsive to determining that said next instruction does not consist of said calling the method, executing said next instruction followed by looping back to said ascertaining; and

responsive to determining that said next instruction consists of said calling the method, processing the next instruction,

wherein said processing the next instruction comprises;

determining whether the method includes a conditional evaluation of a constant variable;

responsive to determining that the method does not include said conditional evaluation of a constant variable, looping back to said ascertaining;

responsive to determining that the method includes said conditional evaluation of a constant variable, determining whether an evaluation of the constant variable would result in immediately returning from the method;

responsive to determining that said evaluation of the constant variable would not result in said immediately returning from the method, performing said looping back to said ascertaining; and

responsive to determining that said evaluation of the constant variable would result in said immediately returning from the method, deleting said calling the method followed by performing said looping back to said ascertaining.

13. The computer program product of claim 9,

wherein to execute the program tool during said run time comprises to monitor the program statements of the sequence of program statements while passing the object code to a run-time interpreter,

wherein the computer program product comprises said nm-time interpreter configured to execute the object code during said run time, and

wherein to execute the program tool during said run comprises to delete the fetched instruction from the computer program.

14. The computer program product of claim 9, wherein the method is a second method, wherein the call to the second method is in a first method, wherein the computer program comprises a set of programming instructions declared explicitly in the source code to be the first method, and wherein the set of programming instructions comprises the program code that comprises the fetched instruction.

15. A system for optimizing a computer program during run time of the computer program, said system comprising a processor of a computer, a computer readable memory, computer readable storage media, and multiple program instructions to execute a program tool on the processor during said run time of the computer program, said program tool stored in the computer readable memory, said computer program being object code configured to be executed on the processor, said object code having been previously compiled by a compiler from source code, said computer program comprising a sequence of program statements declared explicitly in the source code to be a method, said multiple program instructions stored on the computer readable storage media for execution by the processor, said multiple program instructions comprising:

first program instructions to fetch an instruction of the computer program;

second program instructions to determine that the fetched instruction consists of a call to the method, said fetched instruction being comprised by program code of the computer program;

third program instructions to determine, in response to prior execution of the second program instructions, that a program statement of the declared sequence of program statements of the method includes a conditional evaluation of a fixed variable, wherein a declaration statement appearing in the source code explicitly declares the fixed variable as having a fixed value, and wherein an assignment statement appearing in the source code assigns the fixed value to the fixed variable, and wherein the declaration statement and the assignment statement are different statements in the source code;

fourth program instructions to determine, in response to prior execution of the third program instructions, that an immediate return condition exits in the method such that an evaluation of the fixed variable results in an immediate return from the method to the program code without performance of any other program statement of the method; and

fifth program instructions to delete from the computer program, in response to prior execution of the fourth program instructions, the fetched instruction that consists of the call to the method.

16. The system of claim 15,

wherein the program code comprises program code instructions to compute at least one argument for said call to the method in the fetched instruction, and

wherein to execute the program tool during said run time comprises to delete the program code instructions comprised by the program code in response to a determination having been made that the immediate return condition exits.

17. The system of claim 16, wherein the program tool includes program tool instructions to delete the call to the method and to delete the program code instructions by rewriting the object code.

18. The system of claim 16, wherein the multiple program instructions further comprises program instructions to perform a loop, after the fetched instruction has been deleted from the computer program and after the program code instructions comprised by the program code have been deleted, to process multiple instructions of the computer program, wherein the program instructions to perform the loop consist of instructions to perform the steps of:

ascertaining whether a next instruction of the multiple instructions exists;

responsive to said ascertaining, exiting the loop to terminate said processing multiple instructions if said ascertaining ascertains that said next instruction does not exist or getting the next instruction if said ascertaining ascertains that said next instruction exists;

responsive to said ascertaining that said next instruction exists, determining whether said next instruction consists of calling the method;

responsive to determining that said next instruction does not consist of said calling the method, executing said next instruction followed by looping back to said ascertaining; and

responsive to determining that said next instruction consists of said calling the method, processing the next instruction,

wherein said processing the next instruction comprises;

determining whether the method includes a conditional evaluation of a constant variable;

responsive to determining that the method does not include said conditional evaluation of a constant variable, looping back to said ascertaining;

responsive to determining that the method includes said conditional evaluation of a constant variable, determining whether an evaluation of the constant variable would result in immediately returning from the method;

responsive to determining that said evaluation of the constant variable would not result in said immediately returning from the method, performing said looping back to said ascertaining; and

responsive to determining that said evaluation of the constant variable would result in said immediately returning from the method, deleting said calling the method followed by performing said looping back to said ascertaining.

19. The system of claim 15,

wherein to execute the program tool during said run time comprises to monitor the program statements of the sequence of program statements while passing the object code to a run-time interpreter,

wherein the system comprises said run-time interpreter configured to execute the object code during said run time, and

wherein to execute the program tool during said run comprises to delete the fetched instruction from the computer program.

20. The system of claim 15, wherein the method is a second method, wherein the call to the second method is in a first method, wherein the computer program comprises a set of programming instructions declared explicitly in the source code to be the first method, and wherein the set of programming instructions comprises the program code that comprises the fetched instruction.