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Re: Revisiting the use of cselib in alias.c for scheduling
- From: Bernd Schmidt <bernds at codesourcery dot com>
- To: Steven Bosscher <stevenb dot gcc at gmail dot com>
- Cc: GCC Mailing List <gcc at gcc dot gnu dot org>, Richard Guenther <richard dot guenther at gmail dot com>, Alexander Monakov <amonakov at gcc dot gnu dot org>, Steve Ellcey <sje at cup dot hp dot com>
- Date: Wed, 21 Jul 2010 16:44:43 +0200
- Subject: Re: Revisiting the use of cselib in alias.c for scheduling
- References: <AANLkTimC+WLCxQLuAvG51+2MuW-UrtWsX=120FBcZ+vk@mail.gmail.com>
On 07/21/2010 03:06 PM, Steven Bosscher wrote:
> 3. GCC now has better alias analysis than it used to, especially with
> the alias-exporting stuff that exports the GIMPLE points-to analysis
> results, but also just all the other little things that were
> contributed over the last 10 years (little things like tree-ssa :)
[...]
> It looks like ~9% extra !true_dependence cases are found with cselib,
> with is not insignificant:
So, if you want to do something useful in this area, try finding out why
cselib is still useful despite your point 3 above. Maybe alias analysis
can be improved?
If that can't be improved, I think that rather than remove cselib from
the scheduler, the question should be: if it's useful, why don't we use
it for other schedulers rather than only sched-ebb?
Bernd