(g)fortran support for MPX (was: Re: [PATCH, MPX, 2/X] Pointers Checker [8/25] Languages support)

[Tobias Burnus <burnus at net-b dot de>]

Ilya Enkovich wrote:
> The issue is that users do not get what expect. I do not want someone
> having mixed codes get instrumentation for his Java/Fortran/Ada
> functions which slows them down and does nothing useful. What is the
> point to allow checks of pointer bounds for language with no pointers?

Talking about Fortran, I wonder which modifications are required to get 
it working. Can you give some pointers? I lost a bit track.

(For readers, who haven't followed: See
http://gcc.gnu.org/wiki/Intel_MPX_support_in_the_GCC_compiler )

In Fortran, often an array is described by an array descriptor, a struct 
which carries both the pointer address and the array bounds. Thus, that 
makes it simpler to check for bound violations at runtime (existing 
-fcheck=bounds). However, arrays can also be passed as in a way that 
only the address is known – in that case, one has the same issues as 
with C. One place where the issue occurs is interoperating with C, but 
also within Fortran it can occur. I think especially for 
interoperability with C (C++ with extern "c", etc.), having the checks 
would be useful.

I have to admit that it is not completely clear to me when to best add 
MPX annotations with Fortran, but as it is explicitly controlled by a 
compile-time flag, there is no real reason for not using it.

Tobias