Re: [fortran-dev, patch] PR29962 - add simplifier for dot_product, matmul, transpose (F2003)

[Tobias Schlüter <tobias dot schlueter at physik dot uni-muenchen dot de>]

Tobias Schlüter wrote:
> On a similar note, I have been thinking for a long time that an 
> infrastructure where initialization expressions need not be evaluated as 
> a whole during compilation would be a better idea than expanding large 
> array constructors (NB we still have limits on those, even though its 
> controlled by a command line flag).
>
>
> So if you have
>  REAL, PARAMETER :: X(N,M) = [ ... ], Y(M,L) = [ ... ]
>  REAL, PARAMETER :: Z(N,L) = MATMUL(X,Y)
>  ...
>  PRINT *, Z(1,1)
> you would only evaluate Z(1,1) at compile time (if at all), never 
> expanding the MATMUL as a whole (it should be relatively easy to defer 
> that to the runtime, just allocate space for Z and initialize it by 
> building the function call).  Currently this is not possible because our 
> way of checking for initialization expressions is to simplify them, and 
> then seeing if a constant expressions turns up.

Sorry to reply to myself, but it just occurred to me that something like 
this would also be a great tool for checking if the implementation in 
simplify.c matches the one in the library: just add a flag that pushes 
all function evaluations into the binary instead of doing them at 
compile time, and then use this flag to compare the two implementations.

Cheers,
- Tobi