items in common are zero

items in common are zero

We are new to the Compaq Visual Fortran (CVF) Compiler and have found something that we can't explain. We are merging 2 programs together with all data transfer between them via a shared common block. We are linking an object (from Program A) provided by CVF developer A with another 3 objects from Program B provided by CVF developer B. The developers do not share their source code. As noted, the programs share a common block (via include) which contains all of the variables needed to pass back and forth between programs. The group A and B objects are linked by CVF developer A and an program executable is created. Upon execution, Program A initializes two variables in the shared common (an integer*4 and a character*180) to specific non-zero values, then calls Program B as a subroutine. When Program B prints these variables, they are both zero (as if they have been reset to zero).

We have done some similar tests linking 2 small test program object files with this same ?shared common? method of passing variables and it seems to work fine. Developer A has also successfully tested this approach using a small callable ?dummy? version of Program B (that returns some dummy variables back just like Program B would have). Similarly, Developer B has successfully tested this approach using a small dummy ?caller? version of Program A (that sends some dummy variables like Program A would have).

Has anyone encountered this before? What could we be missing? Any ideas/suggestions are welcome.



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Here's what I would do. In "program A", print out LOC(common-variable-name). In "program B", do the same. See if you get the same value printed in both parts of the application. If you don't, then a link map, searching for the common name, might be enlightening.

Either your two parts of the program really aren't sharing the common, or your code violates the Fortran standard in a way that makes the compiler think it doesn't need to fetch from the common (for example, if you pass the common variable as an argument and reference it both ways.)

I wonder if the two sets of objects are being compiled with different switch settings - for example, if one was compiled with /names:lowercase and the other wasn't, you'd get two sets of commons. The link map would tell you this. (Project..Settings..Link..Generate map file)


Retired 12/31/2016


Some of the parameters used to size things in the common from program A were different than those used to size things in the common for program B - whiched caused a major misalignment.

Also, we did have to change to /names:lowercase.

Thanks for your suggestions.


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