FIX: Combining -4Yb with -Ox May Cause Invalid Run-Time Errors (110002)

SYMPTOMS

On some rare boundary cases, using optimizations (-Ox) with extended error handling ($DEBUG or -4Yb) can cause invalid run-time errors to be output, such as:

run-time error F6096: $DEBUG
- array subscript expression out of range

RESOLUTION

If you have determined that a run-time error such as the above is not correct for the code indicated, you can prevent your program from terminating with the error. To do this, place a $NODEBUG metacommand before the line of code that is being flagged, and place a $DEBUG metacommand after it.

STATUS

Microsoft has confirmed this to be a problem in FORTRAN PowerStation 32 for Windows NT and MS-DOS, version 1.0 and 1.0A. This problem was corrected in FORTRAN PowerStation 32, version 4.0.

MORE INFORMATION

The sample below illustrates the problem:

Sample Code

c Compile options required: -Ox -4Yb
c
      CHARACTER CA(512),CB(512),CC(512)
      OPEN(7,FILE='N117.TMP',FORM='UNFORMATTED',RECL=128,
     +     ACCESS='DIRECT')
      DO 10 I=1,512
        CA(I)=CHAR(48)
10    CONTINUE
      DO 20 I=1,16
        WRITE(7,REC=I) (CA(J),J=(I-1)*32+1,(I-1)*32+32)
c The F6096 error incorrectly occurs on the following line.
        WRITE(7,REC=16+I) (CA(J),J=(16-I)*32+32,(16-I)*32+1,-1)
20    CONTINUE
      DO 30 I=1,16
        IE1=(16-I)*32+32
        IE2=(16-I)*32+1
        READ(7,REC=I+16) (CC(J),J=IE1,IE2,-1)
30    CONTINUE
      IE=1
      DO 40 I=1,512
        IF(CA(I).NE.CB(I).OR.CA(I).NE.CC(I)) IE=0
40    CONTINUE
      END