[Bug tree-optimization/18595] [4.0 Regression] IV-OPTS is O(N^3)

["rakdver at atrey dot karlin dot mff dot cuni dot cz" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From rakdver at atrey dot karlin dot mff dot cuni dot cz  2005-01-25 00:27 -------
Subject: Re:  [4.0 Regression] IV-OPTS is O(N^3)

> >>> Other part is that scev tries to be too clever.  Without need to
> >>> represent nonaffine induction variables (that we do not use anywhere)
> >>> we could use more memory efficient representation of ivs.
> >>> Without need to handle symbolic references (that we also do not use
> >>> anywhere, we could store evolutions in a fully instantiated form, and
> >>> we would not need instantiate_parameters/resolve_mixers functions atall.
> >>
> >> Uh, symbolic references are or will be used to do data dependence when
> >> MEM_REF and ARRAY_REF couldn't be generated from the pointers.
> >
> > How?  If the reference is left in symbolic form, it means that you know
> > nothing about its value,
> 
> Wrong.
> 
> We could know things about it's value, such as ranges. We just don't know 
> an exact number.

OK.  This is work for VRP, not scev.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18595