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Re: [tree-ssa] Avoid nondeterminism in tree-ssanames


> Jan Hubicka <jh@suse.cz> writes:
> 
> > Hi,
> > I've run into problem that tree-ssanames in combination with garbage
> > collector may produce non-deterministic results.  The problem is that
> > garbage collector invoked form the middle of SSA compilation path (not
> > done in official tree) zaps the free list of nodes.
> 
> Can you try to work out why zapping a freelist should produce
> different results?  It shouldn't.
> 
> If you find that bug, then this patch is unnecessary.
It is not bug and this patch also saves memory.
It is same as with RTL - if you change register numbers, you change
hashtables and you change decisions in some corner cases.  This is IMO
OK and it is very wrong to have different SSA_VERSIONs depending on GGC
decisiosns.

Honza
> 
> -- 
> - Geoffrey Keating <geoffk@geoffk.org>


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