[tree-ssa] RFC: Making control flow more explicit

[Zdenek Dvorak]

Hello,

> In message <Pine.LNX.4.44.0308120047480.19843-100000@wotan.suse.de>, Michael Ma
> tz writes:
>  >> Very very rarely within the DCE optimizer.
>  >
>  >Control dependence or postdoms also are necessary in if-conversion and for
>  >some edge probability predicators.
> Yup.  One of the unaddressed questions in my mind is whether or not it makes
> sense to compute postdoms once early in the SSA path and keep them up-to-date
> through the SSA optimizers or not.  We compute them on-demand in a few
> places, mostly in areas dealing with IF removal.

in the current state when almost no non-trivial cfg transformations are
done, it would IMHO make sense and it would not be difficult.  Keeping
postdominators up-to-date for example during high-level loop transformations
would be a pain.

Zdenek