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Re: -funsafe-loop-optimizations
On Sun, 02 Jan 2005 11:35:15 -0500, Robert Dewar <dewar@adacore.com> wrote:
> Richard Guenther wrote:
>
> > Well, this is just the builtin_true() that will transform
> >
> > if (!builtin_true(n == MAX_UNSIGNED))
> > abort();
> >
> > to nothing in case 3, and of course VRP and other optimizations
> > take advantage about the fact.
>
> Not really, since this does not establish an invariant for n (at least
> if I understand it), instead it is essentially an assertion at a
> particular point in time, so presumably you have to pepper the
> code with this construct at various points, even for a single
> variable ???
If you change it, yes. So you cannot say simply n will not become
MAX_UNSIGNED anytime. But for particular testcases you probably
will be able to construct something that will help.
Richard.