pointer checking run time code

[Florian Weimer]

* Robert Dewar:

> shreyas krishnan wrote:
>
>> Ideas, other pointers would be great
>
> Note that of course this kind of check is standard in Ada
> and hence in GNAT, so you can get an idea from GNAT
> generated code how well the backend can eliminate
> such checks (answer: getting better with gcc 4).

Doesn't it eleminate too many checks, even? 8-/

And, to be absolutely honest, Ada only requires a small subset of all
the checks that are required to make pointers completely safe.  Once
you use 'Unchecked_Access, Unchecked_Deallocation, or GNAT's
'Unrestricted_Access, all bets are off.