Microsoft KB Archive/108461

= FIX: DO Loop/Computed GOTO Errors with /Ox and /4Yb =

PSS ID Number: 108461

Article Last Modified on 3/24/2000

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The information in this article applies to:


 * Microsoft Fortran Powerstation 32 for Windows NT 1.0

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This article was previously published under Q108461



SYMPTOMS
DO loops may not function properly when compiled with both optimization for time (/Ox) and extended error handling (/4Yb or $DEBUG). A similar problem exists using computed GOTO statements.



RESOLUTION
Do not compile with /Ox and /4Yb at the same time. Use the Visual Workbench debugger to track down run-time errors that occur when using /Ox.



STATUS
Microsoft has confirmed this to be a problem in Microsoft FORTRAN PowerStation 32 for Windows NT, version 1.0. This problem was fixed in FORTRAN PowerStation, version 4.0.



MORE INFORMATION
The following code illustrates the DO loop problem when compiling with /Ox and /4Yb:

Sample Code #1
c FORTRAN Compile options needed: /Ox /4Yb ieof = 0 DO i = 1, 4 IF ( i .EQ. 4 ) ieof = 999 i1 = i + 1 WRITE (*,1000) i, i1, ieof ENDDO 1000 FORMAT (3i6) END

Output
Expected results:   1     2     0 2    3     0   3     4     0   4     5   999 Results with -Ox -4Yb:   1     2     0 1    2     0   2     3     0   3     4     0 The sample program below executes in an infinite loop when compiling with /Ox and /4Yb:

Sample Code #2
c FORTRAN Compile options needed: /Ox /4Yb J = 0 1 CONTINUE WRITE(*,*) 'Label 1' WRITE(*,*) 'J = ', J

J = J + 1 IF (J.EQ.2) THEN K = 1 ELSE K = 1 ENDIF

WRITE(*,*) 'J = ', J     GOTO(1,2), J        ! Computed GOTO always branches to label 1

2 CONTINUE WRITE(*,*) 'Label 2' END

Additional query words: 1.00

Keywords: kbbug KB108461

Technology: kbAudDeveloper kbFORTRANPower32100NT kbFortranSearch kbZNotKeyword2

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