FIX: Using /4Yb and /Ox Together Is Not Recommended

The information in this article applies to:

• Microsoft FORTRAN PowerStation for MS-DOS, version 1.0

SYMPTOMS

Running a program compiled with both full optimization (/Ox) and extended error handling ($DEBUG or /4Yb) may cause several problems including: incorrect results, incorrect range errors, or hanging.

RESOLUTION

To avoid these problems, remove either the full optimization compiler switch (/Ox) or the extended run-time debugging option (/4Yb or $DEBUG).

STATUS

Microsoft has confirmed this to be a problem in FORTRAN PowerStation for MS-DOS, version 1.0. This problem has been resolved with FORTRAN Powerstation maintenance release version 1.0a for MS-DOS.

FORTRAN PowerStation version 1.0 can be differentiated from the maintenance release version 1.0a by invoking the linker. Typing "link32 | more" from \f32\BIN directory will show version 2.8 for FORTRAN PowerStation version 1.0, and it will show 1.0f for the maintenance release version 1.0a.

MORE INFORMATION

The following code generates an incorrect range error if compiled with both /Ox and /4Yb, but runs correctly if either /Ox or /4Yb is not used:

   1
   test.for(6) : run-time error F6096: $DEBUG
   - array subscript expression out of range
   Execution traceback:
      from main program in test.for(6)

Sample Code

C Compiler options required: /Ox and /4Yb

        INTEGER IA(4)
        data IA / 1, 2, 3, 4 /
        DO 20 I=1,2
          write(*,*) i
          WRITE(*,*) (IA(J),J=(I-1)*2+1,4)
20      CONTINUE
        end