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Re: Tree-SSA and POST_INC address mode inompatible in GCC4?
2007/11/3, Kenneth Zadeck <zadeck@naturalbridge.com> wrote:
> J.C. Pizarro wrote:
> > They need to add an algorithm post-SSA that the code reuse the variables
> > converting a_j <- phi(a_i,...) to a_k <- phi(a_k,...).
> >
> > The algorithms of POST_INC and POST_DEC are very specific, so an above
> > general algorithm is sufficient.
>
> This is a little too simple. It assumes that the tree passes did
> nothing. In fact you want to try to discover what the induction
> variables are and rewrite them into a canonical form that auto-inc-dec
> can then pick up on.
The general algorithm is not simple, it has to explore and to reorganize
the complex graph, and can fall to conflicts.
J.C. Pizarro