Re: in gfortran, is it faster compile times with *.mod files ?

On 11/12/2024 2:01 AM, Thomas Koenig wrote:

Lynn McGuire <lynnmcguire5@gmail.com> schrieb:

On 11/11/2024 4:01 PM, Thomas Koenig wrote:

Lynn McGuire <lynnmcguire5@gmail.com> schrieb:

In gfortran, is it faster compile times with *.mod files ?  Or is it
just as fast compiling to include the module interface information in
each subroutine / function file ?

>
I haven't benchmarked this, but I think likely that there would only
be a small difference.  Usually, the front end only takes a small part of
compilation time (but there are pathological cases).
>
In general, modules are better because of automatic checking.
If you want to avoid recompilation cascades, submodules (where
you can separate the definition from the implementation) might
be worth looking into.
>

Is there any chance that gfortran will automatically generate and use
module files in the future like IVF ?

>
Not sure what you're asking for.  Can you give an example?

>
1. you compile abc.f in IVF
2. IVF automagically creates an abc__genmod.f90 file in your release
subdirectory with the subroutine / function module interface in it

 I think I get the general gist (but it would help me understand
if you could post a complete example).
 But gfortran currently does not have such a feature (which appears
to duplicate modules).  It is also not immediately clear what should
happen if, for example, a procedure uses a derived type from another
module... (This may not be relevant to your case, but as a compiler
writer, you have to think about this kind of thing :-|)
 What would go wrong if you simply encapsulated abc.f in
        MODULE ABC
       CONTAINS
C  Your code here
       END MODULE ABC
 ?

I am not sure what that would get me.  I have 6,000+ subroutines and functions in 5,000+ files.  And I would still have to modify each file.
I am going to write a C++ program to put a USE statement in each subroutine / function with the name of the subroutine / function to be excluded.  It should not take me more than a day or three.
I scanned through the Fortran Language doc but it did not have a USE case for this.
    https://j3-fortran.org/doc/year/24/24-007.pdf
Thanks,
Lynn McGuire