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Re: Minor CCP improvement and add comments to tree.h
On Wed, 2004-09-22 at 11:00, Jeffrey A Law wrote:
> > OK. If that's the case, it would be better to mark them VARYING right
> > off the bat. That saves us more propagation work. After all, CCP won't
> > be able to substitute and fold them.
> No because you can still use them to derive other constants
> (think about address arithmetic).
>
Now I need an example. I am having a hard time understanding this
part. If replacing this constant value in an expression didn't give us
another constant to work with in DOM, why would it in CCP? The
replacing and folding rules are the same.
> > If we have a persistent value holding slot, then how do we make sure
> > that its contents are valid from pass to pass?
> Err, by designing it correctly.
>
Well, of course :)
But let's get rid of one of the two. We don't need an additional field
in tree_ssa_name. If you are so convinced that we need this type of
persistence, let's pick one and go with it.
Diego.