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Re: Loop optimizer issues
- From: Zdenek Dvorak <rakdver at atrey dot karlin dot mff dot cuni dot cz>
- To: David Edelsohn <dje at watson dot ibm dot com>
- Cc: Jan Hubicka <jh at suse dot cz>,"S. Bosscher" <S dot Bosscher at student dot tudelft dot nl>,'Richard Henderson ' <rth at redhat dot com>,'Geoff Keating ' <geoffk at geoffk dot org>,'Diego Novillo ' <dnovillo at redhat dot com>,'Jason Merrill ' <jason at redhat dot com>,'Daniel Berlin ' <dberlin at dberlin dot org>,"'pop at gauvain dot u-strasbg dot fr '" <pop at gauvain dot u-strasbg dot fr>,"'gcc at gcc dot gnu dot org '" <gcc at gcc dot gnu dot org>
- Date: Thu, 3 Jul 2003 01:34:42 +0200
- Subject: Re: Loop optimizer issues
- References: <20030702223328.GF9134@kam.mff.cuni.cz> <200307022243.SAA33174@makai.watson.ibm.com>
Hello,
> Jan> Zdenek is speaking about the invariant motion. Clearly there are many
> Jan> cases where RTL expansion will bring oppurtunities for invariant motion,
> Jan> so these needs to be re-done on the RTL.
>
> Jan> Concerning libcalls, they should not exist in post-tree-SSA world as
> Jan> they are just papering over the problem that such complex things should
> Jan> have been moved earlier.
>
> How about starting with a Tree-SSA loop optimization
> infrastructure and then back-filling RTL loop optimizations where they are
> profitable instead of guessing?
how will you judge that without actually trying it?
In this concrete instance there is not much guessing, really. There
will be some code motion done on tree-ssa as well as on rtl; the only
question is how much will be done where.
Zdenek