LOOP_HEADER tree code?

[Devang Patel]

On 10/25/06, Andrew Pinski <pinskia@earth.geop.uc.edu> wrote:
> >
> > > and seeing the reaction of people,
> > > I probably won't use it.  The main reason for considering to use
> > > the tree node for me was the possibility to make the number of iterations
> > > of the loop as its operand, so that I would not need to worry about
> > > keeping it alive through dce, copy/constant propagation, etc. (without
> > > a statement carrying it in IL, I do not see a solution that would not
> > > be just asking for introducing bugs and getting broken accidentally).
> >
> > One way to achieve this is to mark n_1 (in your example) as
> > "do not dead strip because I know it is used" , kind of attribute((used)).
>
> This is what as I understand LOOP_HEADER is used for.

Big difference. New tree vs TREE_USED or DECL_PRESERVE_P bit.

-
Devang
> You just make the statement
> as useful when doing DCE so you don't loose it.  Then nothing goes funny and only
> very few things have to be updated, DCE is one and that is it.
>
> -- Pinski
>


-- 
-
Devang