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Re: Dropping of old loop optimizer
- From: Pop Sébastian <pop at gauvain dot u-strasbg dot fr>
- To: Daniel Berlin <dberlin at dberlin dot org>
- Cc: 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: Thu, 27 Feb 2003 17:14:48 +0100
- Subject: Re: Dropping of old loop optimizer
- References: <20030227151807.GA15920@gauvain.u-strasbg.fr> <3779E2EC-4A6A-11D7-B465-000393575BCC@dberlin.org>
On Thu, Feb 27, 2003 at 10:43:28AM -0500, Daniel Berlin wrote:
>
> I had started to work on this method, but decided it was too complex,
> and moved to monotonic evolution.
>
In contrast to the CR method, monotonic evolution (ME) gives approximate
data dependences: you'll have the direction but not the distance vector
of a dependence. Fact: not all optimizers use approximate vectors.
In this point you cannot compare these two passes, but anyway ...
> Are you sure CR's are going to be fast enough?
>
..., I agree CR is slower than ME. ME was designed to be faster.
We could speed up CRs by generating them on demand. This way we'll
limit this "expensive" ("not so-" in my opinion since I haven't
tested it yet :-) pass to a single loop nest.
Sebastian