[FORTRAN PATCH] Optimize FORALLs with constant mask expressions

[FX Coudert]

> I'm wondering what the gfortran maintainers think about  
> implementing these
> sort of source-to-source transformations earlier, perhaps during  
> parsing
> or a simplification pass?

My opinion is that a simplification pass in the front-end, just after  
resolution and just before generating the trees, could be nice.

> The following code has been tested on x86_64-unknown-linux-gnu with  
> a full
> "make bootstrap", including gfortran, and regression tested with a
> top-level "make -k check" with no new failures.
>
> Ok for mainline?

OK.

PS: Roger, since you're working hard on FORALL, I wonder if you are  
aware of PR30400 ("ANY not accepted as mask in FORALL")?