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Re: Loop unrolling-related SPEC regressions?
- From: Jan Hubicka <jh at suse dot cz>
- To: Andreas Jaeger <aj at suse dot de>
- Cc: Dale Johannesen <dalej at apple dot com>, Laurent Guerby <guerby at acm dot org>, Paolo Carlini <pcarlini at unitus dot it>, gcc at gcc dot gnu dot org, rth at redhat dot com
- Date: Thu, 7 Feb 2002 12:48:36 +0100
- Subject: Re: Loop unrolling-related SPEC regressions?
- References: <E2995D70-1B52-11D6-826C-003065C86F94@apple.com> <email@example.com>
> Dale Johannesen <firstname.lastname@example.org> writes:
> > Intelligent use of profiling info from the first pass is
> > important. You'll see the published numbers do this.
> > Last time I looked gcc used this only for branch
> > straightening; it can also be used effectively to
> > drive inlining and register allocation.
> AFAIK the infrastructure is there, it only needs to be used for
> inlining - and also in the new register allocator. Michal, is this
It is not possible to use it for inlining yet, as our loop optimization
pass kill profile info, so unless we want to have multiple passes needed
for optimization, we need to rewrite that one as well as RTL code
generation first. We are working on that.
It is already used for register allocation in the mainline as well as
for few of other decision. CFG branch is more aggressive already deriving
about 5% benefit. I hope this to improve as the code matures.