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Re: new auto-inc-dec pass
- From: Roman Zippel <zippel at linux-m68k dot org>
- To: Joern Rennecke <amylaar at spamcop dot net>
- Cc: gcc at gcc dot gnu dot org
- Date: Tue, 6 Mar 2007 14:14:50 +0100 (CET)
- Subject: Re: new auto-inc-dec pass
- References: <20070306061010.kq75cskoc4wkgcks@webmail.spamcop.net>
Hi,
On Tue, 6 Mar 2007, Joern Rennecke wrote:
> In http://gcc.gnu.org/ml/gcc/2007-03/msg00128.html, you wrote:
> > One case is about multiple increments, the tree optimizer merges them and
> > increments the register only once, so if one only looks at the size of the
> > pointer value one misses them, e.g. something like this:
> >
> > (set (mem (reg)) (x))
> > (set (mem (plus (reg) (const_int 4))) (x))
> > (set (reg) (plus (reg) (const_int 8))
>
> The patches attached to PR20211 handle this case.
Hmm, it seems to do a bit more. I have to agree with the last comment
insofar, that regmove.c is probably not the best place for this. Most of
the auto-inc-dec business should be done before combine.
bye, Roman