[Bug tree-optimization/30911] VRP fails to eliminate range checks in Ada code

[rguenther at suse dot de]

------- Comment #63 from rguenther at suse dot de  2008-03-30 15:56 -------
Subject: Re:  VRP fails to eliminate range checks
 in Ada code

On Sun, 30 Mar 2008, ebotcazou at gcc dot gnu dot org wrote:

> ------- Comment #62 from ebotcazou at gcc dot gnu dot org  2008-03-30 15:45 -------
> > Yes, even with -gnato.  With -gnato it checks that the
> > addition doesn't overflow.
> 
> Oh, sorry, I thought we were talking about the overflow check...
> 
> > But there are no checks on the array access.  It looks like the f-e
> > doesn't generate them in the first place (as opposed to fold or gigi
> > making a mistake).
> 
> This is as documented in the GNAT manual, section 3.2.4 Validity Checking.
> You need to pass -gnatVs to have them.

So even GNAT assumes parameter values are in-range?  Wouldn't that
cause an bounded error to become an unbounded error if it were
out-of-range?

I'm somewhat confused on what the Ada language specification is and
what is GNAT implementation freedom...

Richard.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30911