Forgive me for asking the classic question: "What are you really trying to do?"
Edward
Excerpts from Simon Marlow's message of Tue Aug 13 09:25:51 -0400 2013:
> On 13/08/13 13:03, Jan Stolarek wrote:
> > I have yet another Hoopl question. One of my rewrites allocates a new
> > unique local register and this register is later added as a fact. So I have
> > Cmm code that looks like this:
> >
> > I32[(old + 4)] = complicated_expr
> >
> > which is rewritten to:
> >
> > newReg1 = complicated_expr
> > I32[(old + 4)] = newReg1
> >
> > and then I add { I32[(old + 4)] = newReg1 } as a fact. When Hoopl reaches
> > end of the iteration it realizes it has learned some new facts, so it keeps
> > the facts (including fact about a new unique register) and discards
> > rewritten graph (including said new register). In the next iteration it
> > performs the rewrite again, allocating a different new register and adding
> > fact about this different register. At the end of this iteration same thing
> > happens again: facts are kept, rewrite is discarded. And so my code falls
> > into an infinite loop, because every time I'm allocating a different
> > register and every time hoopl thinks it learned sth new and discards the
> > rewritten graph. How can I perform this rewrite and avoid falling into a
> > loop?
>
> Your transfer function is not monotonic, because each time you apply it
> it gives a different result.
>
> The next question is "well how do I do this then?". I'm not quite sure,
> maybe you need to use a deterministic name supply monad.
>
> Cheers,
> Simon
>
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