Hello,

> >>>The attached fixes *that*, but this just causes a crash deeper in trying 
> >>>to free some chains.
> >>>      
> >>[...]
> >>Sorry for the problems and thanks for looking into them.
> >>    
> >
> >Ken, please reread the email.  The issue is *not* fixed according to
> >Daniel, there's still another problem.  Could you look into it,
> >please?
> >
> I would like permission to revert zdenek's patch for a few days.  There 
> is nothing wrong with zdenek's patch, pe se, but it excercises a part of 
> df that should work but does not.

I don't quite like this idea; as you yourself say, the problem is not in
that patch (in fact, mainline bootstraps and passes regtesting with it
without your patch); so I think that if we indeed want to go into
reverting patches, it should be the one causing the problem (and I have
a followup patch that I would like to be able to test).

Btw.: of course it may happen that some patch sometimes breaks
bootstrap, it happened to everyone of us.  But, with your patch, not
even libgcc builds.  This means that you did not even try to build gcc
before commiting your patch.  Please do that next time.  In fact,
running at least a partial bootstrap till gengtype is run helped me
avoid introducing bootstrap failures (caused by unexpected interaction
with patches commited since I tested the patch fully the last time)
several times, so it is a good idea even if you are quite sure that no
such problem may occur.

> We could revert my storage patch, but the problem is much deeper than 
> that.  The storage patch only causes this problem to happen when 
> bootstrapping.  The problem will still be there and may cause random 
> ices when running zdeneks code.
> 
> The problem is that when ever you delete any basic blocks, you need to 
> get rid of the def use and use def chains that either start or end in 
> the deleted block, furthermore,  this has to be done before the 
> instructions are deleted for those blocks.  This will take me a day to 
> get correct.
> Zdenek's patch is the only code that manipulates the blocks after 
> use-def or def-use chains are built.

This analysis seems wrong to me -- the crash occurs when called from
estimate_probability, and we do not change CFG in branch prediction.

Zdenek

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