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

[Michael Matz]

Hi,

On Mon, 11 Aug 2003 law@redhat.com wrote:

>  >because parent obviously is not what you want here. IIRC in the ssa dce
>  >algorithm marking of the neccesary control statements is somehow
>  >done using dominator information.
> The RTL version does use dominator information, the tree version does not
> use dominator information to find necessary control statements.
>
> The tree version uses the nested control structure and goto following to
> deduce control dependency.

The question is, do we eventually somewhen will need postdoms anyway?  If
yes, then it doesn't make much sense in inventing a clever method of
avoiding calculating them.  postdoms itself are not that slow to compute,
and if one updates them when changing the CFG, where possible, the overall
effect should be reasonable.  I guess the answer to the first question is
yes.


Ciao,
Michael.