Introduce new typedefs: const_tree, const_rtx, etc.

[Richard Guenther]

On 8/12/06, Kaveh R. Ghazi <ghazi@caipclassic.rutgers.edu> wrote:
> As discussed here:
> http://gcc.gnu.org/ml/gcc/2006-06/msg00929.html
>
> I'd like to introduce auxiliary const typedefs that parallel existing
> core types in GCC.  This will allow us to constify various things,
> mainly function parameters that currently take a plain tree, rtx, etc.
>
> The first step is to add the new types to coretypes.h.  We must also
> update the "checking" macros to use __typeof() to preserve the
> constness of the supplied expression.  Thanks to Dave and Ian for the
> suggestion.
> http://gcc.gnu.org/ml/gcc/2006-07/msg00303.html
>
> Bootstrapped on sparc-sun-solaris2.10, I used --enable-checking=yes,rtl
> to ensure we exercise the modified RTL checking macros.  There were no
> regressions.
>
> Okay for mainline stage1 ?

What is the benefit of this apart from being able to check const
correctness?

Richard.