Improve VRP, remove DOM nonzero property tracking

[Jeffrey A Law]

On Fri, 2006-02-17 at 09:40 +0100, Paolo Bonzini wrote:
> Steven Bosscher wrote:
> > On Friday 17 February 2006 05:14, Jeffrey A Law wrote:
> >> Here's the next installment in ripping out those bits in DOM which
> >> are implemented better elsewhere in the compiler.
> > 
> > Yay, very nice.
> > Bonus: I think your patch makes PHI_ARG_NONZERO unused...?
> 
> Very nice indeed, but I don't like the ping-pong of function calls 
> between VRP and fold.  Can't we have a function in tree-vrp that does
> 
> if (TREE_CODE (t) == SSA_NAME)
>    blah-blah-query-the-ranges
> else
>    return tree_expr_nonzero_p (t);
> 
> instead?
No, you miss too much with that kind of style.  To pick up the
cases we want you either have to ping-pong or you have to duplicate
a boatload of code.

The ping-pong is the cleanest way to get what we want.

jeff