Method for defining alias sets

Patent metadata

Field	Value
Publication number	US-2017123772-A1
Application number	US-201514929448-A
Country	US
Kind code	A1
Filing date	Nov 2, 2015
Priority date	Nov 2, 2015
Publication date	May 4, 2017
Grant date	—

Abstract

One or more processors determine whether a first procedure within a first program meets a first criterion. The first criterion is included in a plurality of criteria that are configured for pessimistic aliasing. Responsive to the determination, one or more processors determine whether to flag the first procedure for pessimistic aliasing.

First claim

1 - 7 . (canceled)

8 . A computer program product comprising:
one or more computer-readable storage media and program instructions stored on at least one of the one or more computer-readable storage media, the program instructions comprising:
program instructions to determine whether a first procedure within a first program has access to one or more variables declared outside the scope of the first procedure;
program instructions to generate a call graph computation that includes searching from a vertex representing the first procedure until one or more of a plurality of criteria that are configured for pessimistic aliasing cause the first procedure to be flagged;
program instructions to determine whether the first procedure within the first program meets a first criterion, wherein the first criterion is included in the plurality of criteria; and
responsive to the determination, program instructions to determine whether to flag the first procedure for pessimistic aliasing.

9 . The computer program product of claim 8 , wherein the plurality of criteria include one or more of: 1) the first program exceeds a threshold number of calls from a second procedure on a call graph, wherein the second procedure does not call any other procedure, 2) the first program is capable of a call to a pointer function, 3) the first program is capable of a call to a second procedure, wherein the second procedure is capable of a call to a pointer function; 4) the first program is beyond a threshold criterion of complexity, 5) the first program is capable of a call to an external variable, 6) the first program is capable of a call to a second procedure, wherein the second procedure is capable of making a call to an external variable, 7) the first program is capable of exceeding a threshold number for making pointer de-references, 8) the first program is capable of a call to a second procedure, wherein the second procedure exceeds a threshold number for making pointer de-references, 9) the first program is capable of a call to a second procedure, wherein the second procedure is flagged as requiring a pessimistic alias set.

10 . The computer program product of claim 9 , wherein the threshold number of calls between the first procedure and the second procedure on the call graph is one or more of: 1) a number of calls set by a user, 2) based, at least in part, on a statistical analysis of historical data from one or more second programs substantially similar to the first program, 3) based, at least in part, on an amount of computation that can be tolerated by a compiler, and 4) two.

11 . The computer program product of claim 9 , wherein the threshold criterion of complexity includes one or more of: 1) the first procedure exceeds a threshold value for size, 2) the first procedure exceeds making a threshold number of calls to other procedures, and 3) the first procedure has one or more difficult-to-analyze constructs.

12 . (canceled)

13 . The computer program product of claim 8 , wherein the program includes one or more of: 1) COBOL, 2) PL/I, 3) C programming language, 4) methods in object-oriented languages, and 5) ‘C’ functions that can access file scope variables.

14 . (canceled)

15 . A computer system comprising:
one or more computer processors; one or more computer-readable storage media; and program instructions stored on at least one of the one or more computer-readable storage media for execution by at least one of the one or more processors, the program instructions comprising:
program instructions to determine whether a first procedure within a first program has access to one or more variables declared outside the scope of the first procedure;
program instructions to generate a call graph computation that includes searching from a vertex representing the first procedure until one or more of a plurality of criteria that are configured for pessimistic aliasing cause the first procedure to be flagged;
program instructions to determine whether the first procedure within the first program meets a first criterion, wherein the first criterion is included in the plurality of criteria; and
responsive to the determination, program instructions to determine whether to flag the first procedure for pessimistic aliasing.

16 . The computer system of claim 15 , wherein the plurality of criteria include one or more of: 1) the first program exceeds a threshold number of calls from a second procedure on a call graph, wherein the second procedure does not call any other procedure, 2) the first program is capable of a call to a pointer function, 3) the first program is capable of a call to a second procedure, wherein the second procedure is capable of a call to a pointer function; 4) the first program is beyond a threshold criterion of complexity, 5) the first program is capable of a call to an external variable, 6) the first program is capable of a call to a second procedure, wherein the second procedure is capable of making a call to an external variable, 7) the first program is capable of exceeding a threshold number for making pointer de-references, 8) the first program is capable of a call to a second procedure, wherein the second procedure exceeds a threshold number for making pointer de-references, 9) the first program is capable of a call to a second procedure, wherein the second procedure is flagged as requiring a pessimistic alias set.

17 . The computer system of claim 16 , wherein the threshold number of calls between the first procedure and the second procedure on the call graph is one or more of: 1) a number of calls set by a user, 2) based, at least in part, on a statistical analysis of historical data from one or more second programs substantially similar to the first program, 3) based, at least in part, on an amount of computation that can be tolerated by a compiler, and 4) two.

18 . The computer system of claim 16 , wherein the threshold criterion of complexity includes one or more of: 1) the first procedure exceeds a threshold value for size, 2) the first procedure exceeds making a threshold number of calls to other procedures, and 3) the first procedure has one or more difficult-to-analyze constructs.

19 . (canceled)

20 . The computer system of claim 15 , wherein the program includes one or more of: 1) COBOL, 2) PL/I, 3) C programming language, 4) methods in object-oriented languages, and 5) ‘C’ functions that can access file scope variables.

Assignees

• IBM

Inventors

• Perry Sean D
• Tremaine David

Classifications

• G06F8/443 Primary

  Optimisation · CPC title

• G06F8/41

  Compilation · CPC title

• G06F8/434

  Pointers; Aliasing · CPC title

• G06F8/315

  Object-oriented languages · CPC title