Ifort dialect options for very old code
I was unexpectedly provided with some very old fortran codes to compile and work in my research group. Using ifort while compiling the code, I get the following error:error #6526: A branch to a do-term-shared-stmt has occurred from outside the range of the corresponding inner-shared-do-construct.
Here's the bit of code that seems to be at fault:
...
IF(THRU.GT.0.D0) GO TO 120 00011900
L1=LL 00012000
A1=AA 00012100
DR1=DRR 00012200
RMAX1=RMAXX 00012300
RMIN1=RMINN 00012400
IF(DR1.EQ.0.D0) DR1=DRP 00012500
KMAX1=(RMAX1-RMIN1)/DR1+1.D-08 00012600
IF(KMAX1.GT.NN .OR. KMAX1.LE.0) KMAX1=NN 00012700
RINT1=RMAX1 00012800
IF(RMAX1.NE.0.D0) 00012900
2RMAX1=DR1*DFLOAT(KMAX1)+RMIN1 00013000
IUP=KMAX1 00013100
R=RMIN1 00013200
DO 120 K1=1,KMAX1 00013300
R=R+DR1 00013400
XX(K1)=R 00013500
120 CONTINUE 00013600
WRITE(IW,940) NAM1,IOPT1,L1,A1,DR1,RMAX1,RMIN1,ANU1,BNU1,CNU1 00013700
121 CONTINUE 00013800
...
Being completely unfamiliar with fortran, I do some searching and I see that it doesn't like the IF statement branching into a DO loop terminal statement. Also, it seems that some older dialects or compilers supported this.
My questions are: Is there an option that will allow ifort to compile this successfully? IE Is there a specific dialect compatibility option on ifort that will make this legal?
What are the side effects of this particular code on the compiler that would accept it? Is it possible that besides the write statement, the side effects are identical to branching to line 121? Or maybe the do loop should go up to 121?
I would consider changing the code if it weren't for the fact that my advisor told me that I shouldn't make any changes without consulting him in the first place, and so I ask this question to find out if whether I should consult him or not. However, if my only option is to modify the code sentences, I'll be happy about that so that I have an idea of what to do when I go to my advisor.
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Note that this code is not valid even as Fortran 77, but people have become strange things again in the fog of time. I will give it to any historian or person with experience. In particular, one has to be very careful to understand any intricacies of the code in relation to my "answer" here.
If we assume that the intent is goto
to jump to the code after the loop has completed, then my answer is a minimal code change.
Strikethrough line number comments for clarity, then
DO 120 K1=1,KMAX1
R=R+DR1
XX(K1)=R
120 CONTINUE
WRITE(IW,940) NAM1,IOPT1,L1,A1,DR1,RMAX1,RMIN1,ANU1,BNU1,CNU1
can be replaced with
DO K1=1,KMAX1
R=R+DR1
XX(K1)=R
END DO
120 WRITE(IW,940) NAM1,IOPT1,L1,A1,DR1,RMAX1,RMIN1,ANU1,BNU1,CNU1
I would be quite surprised if the author of the code assumed that the loop would continue 121
: no variable referenced by the statement write
is updated in the loop. Possibly what was goto
meant to be referenced 121
, but I can see that many variables are not updated in the section to be skipped.
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