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Re: Dropping of old loop optimizer
- From: Jan Hubicka <jh at suse dot cz>
- To: Daniel Berlin <dberlin at dberlin dot org>
- Cc: Pop Sébastian <pop at gauvain dot u-strasbg dot fr>,Zdenek Dvorak <rakdver at atrey dot karlin dot mff dot cuni dot cz>,tm_gccmail at mail dot kloo dot net, gcc at gcc dot gnu dot org,m dot hayes at elec dot canterbury dot ac dot nz, rth at redhat dot com, law at redhat dot com,dan at dberlin dot org, jh at suse dot cz
- Date: Fri, 28 Feb 2003 10:54:45 +0100
- Subject: Re: Dropping of old loop optimizer
- References: <20030227171331.GA18239@gauvain.u-strasbg.fr> <BBA53658-4A8B-11D7-8451-000393575BCC@dberlin.org>
>
> On Thursday, February 27, 2003, at 12:13 PM, Pop Sébastian wrote:
>
> >On Thu, Feb 27, 2003 at 05:39:17PM +0100, Zdenek Dvorak wrote:
> >>
> >>The problem I see is that rtl ssa is broken (or never worked?); but
> >Last time I had a close look at rtl was about two years ago :-)
> >Dan is the expert to ask about the status of SSA at rtl level (he
> >adapted
> >the CCP code from rtl to tree-ssa).
> The problem with RTL SSA is hard registers and subregs.
> There are hard registers assigned in certain cases during initial RTL
> generation.
> These can't be renamed, obviously.
The tree-SSA represents the SSA form as datastructure on the top of the
trees not modifying the trees themselves, right? Why it is not feasible
for RTL (ie you won't need to rename the registers)
Honza