This is the mail archive of the
gcc@gcc.gnu.org
mailing list for the GCC project.
Re: Dropping of old loop optimizer
On Thu, Feb 27, 2003 at 05:39:17PM +0100, Zdenek Dvorak wrote:
>
> The problem I see is that rtl ssa is broken (or never worked?); but
Last time I had a close look at rtl was about two years ago :-)
Dan is the expert to ask about the status of SSA at rtl level (he adapted
the CCP code from rtl to tree-ssa).
> perhaps we could do this kind of optimizations just on trees (that
> unfortunately also aren't ready for serious usage yet, right?)?
>
CCP (Conditional constant propagation) and
DCE (Dead code elimination)
seem to work fine on tree-SSA.
> > Right now I have a working multivariate and periodic CR system.
> > I have extended the CR system to flip-flop operations that introduce
> > periodicity effects.
> >
> > I still work on extending the CR system to undefined operations
> > that nor Zima, nor Engelen defined (for example the multiplication
> > of exponential CRs by polynomial CRs, or the addition of exponential CRs).
> > I will perform these operations symbolically without expecting to
> > have a code generator at the end as it is the case in the previous papers.
> > I think that analyzers and optimizers should be implemented without mixes.
> >
> > Interfacing with the existing tree-SSA is the next step in my todo list.
> > Then I'll look at how it could be adapted to RTL.
>
> How long do you think it will take you before the result is usable (I
Since this is an analyzer the work could be done faster than for an optimization
pass since difficult cases could be delayed to a later refinement.
In these difficult cases the analyzer will just reply "don't know".
> wonder whether it makes sense to work on some temporary, not so clean
> but faster solution)?
>
Seems possible with successive refinements.
Sebastian