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Re: [tree-ssa] Make PHI nodes reachable by GGC
Richard Henderson <rth@redhat.com> writes:
> On Sat, Nov 29, 2003 at 01:11:14AM +0100, Jan Hubicka wrote:
> > We have no way to expose the fact that there are multiple linked lists
> > per node, so we probably need some extension to deal with this more
> > nicely.
>
> When do we need this?
>
> Iteration should begin with the bb->next list. Now all blocks are
> marked (but not their subobjects). Next, we begin marking subobjects
> of blocks, namely edges. Choose the next link associated with the
> edge list that will be traversed first. That is, if we mark bb->prev
> first, then make bb->prev_next the next link.
>
> I would expect this to take care of the bulk of the problem. Failing
> that, extend gengtype to handle multiple next links. Shouldn't be hard.
gengtype can either:
(a) already do this, or
(b) can't do this because it's impossible
depending on what you mean.
For (a), look at RTX_NEXT and RTX_PREV and how they're used; but
forget how RTX_NEXT is defined, that's a horrible hack. RTX_PREV is
nicer.
--
- Geoffrey Keating <geoffk@geoffk.org>