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[Bug tree-optimization/83072] Late VRP optimization


https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83072

--- Comment #4 from rguenther at suse dot de <rguenther at suse dot de> ---
On Tue, 21 Nov 2017, glisse at gcc dot gnu.org wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83072
> 
> --- Comment #3 from Marc Glisse <glisse at gcc dot gnu.org> ---
> (In reply to Richard Biener from comment #2)
> > The issue is that when EVRP records value-ranges that only hold temporarily
> > it doesn't update SSA_NAME_RANGE_INFO but only the internal lattice while
> > if the range is determined at the SSA definition point it also updates
> > SSA_NAME_RANGE_INFO.
> 
> Seems obvious now you've said it... And VRP1, which would have a separate
> SSA_NAME, does not generally call into match-simplify yet.
> 
> I wonder if we'll take the ugly route of making the EVRP lattice global, and
> having get_range_info use it if it isn't empty (or checking some flag) and fall
> back to the current behavior otherwise. Seems simpler and cheaper than the
> alternatives I am trying to think about.

Once Jeff is settlet with his re-orgs I'm going to simply temporarily
adjust SSA_NAME_RANGE_INFO.  Should be a very simple thing do to.

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