Experimental hacking of gfortran

["N.M. Maclaren" <nmm1 at cam dot ac dot uk>]

I have some interest in doing some experimental hacking of gfortran (for C 
interoperability, especially for MPI) and should appreciate any pointers to 
documents, places in the source and so on that would reduce the effort in 
finding my way around it. Specifically, I would like to do the following:

   Introduce a new option to BIND - say, BIND(DESCRIPTOR)
   Change the calling sequence to pass everything by descriptor
   Create descriptors for the argument, recursively[*]
   Diagnose things that I can't or won't handle

[*] It would be enough for my initial purposes if I could handle the case of
a derived type that contains an allocatable or pointer array component, but
it would be better to allow an indefinite level of nesting.

Designing the descriptor layout is easy (I have done it many times before, 
for several languages) and the only difficulty is in finding out where to 
hit the compiler and which features to use for doing this. I can then use 
the Doxygen documentation in the normal way. Unfortunately, I can't spend a 
huge amount of time on this, so I need to jump over the reverse engineering 
cliff somehow.

I know NOTHING about the structure of gfortran or gcc, though I have hacked
the latter for such purposes in the past - don't ask :-)

Ideas on how I should proceed would be welcome.


Regards,
Nick Maclaren,
University of Cambridge Computing Service,
New Museums Site, Pembroke Street, Cambridge CB2 3QH, England.
Email:  nmm1@cam.ac.uk
Tel.:  +44 1223 334761    Fax:  +44 1223 334679