PSS ID Number: 108461
Article Last Modified on 3/24/2000
The information in this article applies to:
- Microsoft Fortran Powerstation 32 for Windows NT 1.0
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
