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Re: [tree-ssa] RFC: Making control flow more explicit
- From: Zdenek Dvorak <rakdver at atrey dot karlin dot mff dot cuni dot cz>
- To: law at redhat dot com
- Cc: Michael Matz <matz at suse dot de>,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 19:18:37 +0200
- Subject: Re: [tree-ssa] RFC: Making control flow more explicit
- References: <Pine.LNX.4.44.0308120047480.19843-100000@wotan.suse.de> <200308112314.h7BNEDHb008978@speedy.slc.redhat.com>
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