------- Additional Comments From rakdver at atrey dot karlin dot mff dot cuni
dot cz 2005-01-25 11:16 -------
Subject: Re: [4.0 Regression] IV-OPTS is O(N^3)
> > How? If the reference is left in symbolic form, it means that you know
> > nothing about its value, so the only thing you can do with it is to
> > check its equality/inequality, in code like
> >
> > while (...)
> > {
> > i = something_weird ();
> >
> > a[i] = ...; (a)
> > a[i+1] = ...; (b)
> > a[i] = ...; (c)
> > }
> >
>
> The following is probably a more frequent case:
>
> i = 0
> x = something_weird () or a function parameter
> loop
> i = i + 1
> a[i] = ...
> ... = a[i + x]
> endloop
>
> where you end with a symbolic distance vector.
But here x is a loop invariant. Nothing would change here if we were
keeping the evolutions fully instantiated.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18595
