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Re: [tree-ssa] RFC: Making control flow more explicit
- From: Michael Matz <matz at suse dot de>
- To: law at redhat dot com
- Cc: Zdenek Dvorak <rakdver at atrey dot karlin dot mff dot cuni dot cz>,Andrew MacLeod <amacleod at redhat dot com>,Steven Bosscher <s dot bosscher at student dot tudelft dot nl>,Daniel Berlin <dberlin at dberlin dot org>,Diego Novillo <dnovillo at redhat dot com>,gcc mailing list <gcc at gcc dot gnu dot org>
- Date: Tue, 12 Aug 2003 00:23:41 +0200 (CEST)
- Subject: Re: [tree-ssa] RFC: Making control flow more explicit
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.