[tree-ssa] CCP inefficiencies

[Diego Novillo]

On Fri, 2003-02-14 at 03:44, Daniel Berlin wrote:

> On Fri, 14 Feb 2003, Diego Novillo wrote:
> 
> > On second thought, what I said above is completely wrong.  Knowing that
> > the expression is constant is not enough, we *really* need to fold it to
> > compute and return its lattice value from tree-ssa-ccp.c:evaluate_stmt.
> 
> I was only talking about replacement, not about evaluation.
>
Right.  That's why I ammended my original comment :)

> For replacement, an expression can't become constant unless you've
> replaced at least one variable with a constant.
> For evaluation, you can't do it without copying.
>
Yes.


Diego.